Alternating asymmetrical plasma generation in a process chamber
Embodiments of the invention generally provide etch or CVD plasma processing methods and apparatus used to generate a uniform plasma across the surface of a substrate by modulation pulsing the power delivered to a plurality of plasma controlling devices found in a plasma processing chamber. The plasma generated and/or sustained in the plasma processing chamber is created by the one or more plasma controlling devices that are used to control, generate, enhance, and/or shape the plasma during the plasma processing steps by use of energy delivered from a RF power source. Plasma controlling devices may include, for example, one or more coils (inductively coupled plasma), one or more electrodes (capacitively coupled plasma), and/or any other energy inputting device such as a microwave source.
Latest Patents:
- PHARMACEUTICAL COMPOSITIONS OF AMORPHOUS SOLID DISPERSIONS AND METHODS OF PREPARATION THEREOF
- AEROPONICS CONTAINER AND AEROPONICS SYSTEM
- DISPLAY SUBSTRATE AND DISPLAY DEVICE
- DISPLAY APPARATUS, DISPLAY MODULE, ELECTRONIC DEVICE, AND METHOD OF MANUFACTURING DISPLAY APPARATUS
- DISPLAY PANEL, MANUFACTURING METHOD, AND MOBILE TERMINAL
This application claims benefit of provisional U.S. Patent Application Ser. No. 60/566,718, filed Apr. 30, 2004, entitled “Alternating Asymmetrical Plasma Generation In A Process Chamber,” [Attorney Docket No. 8459L] and is herein incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
Embodiments of the invention generally relate to plasma processing systems and materials and apparatus for controlling plasma uniformity in plasma processing systems.
2. Description of the Related Art
Plasma chambers are regularly utilized in various electronic device fabrication processes, such as etching processes, chemical vapor deposition (CVD) processes, and other processes related to the manufacture of electronic devices on substrates. Many ways have been employed to generate and/or control the plasma density, shape, and electrical characteristics in processing chambers, such as capacitively or inductively coupled plasma chambers. An inductively coupled RF plasma chamber typically has an inductive coil antenna wound around the chamber and connected to a plasma source RF power supply. A capacitively coupled plasma chamber typically has two parallel plate electrodes, i.e., “showerhead” and substrate support, between which plasma is generated.
Inductively coupled and capacitively coupled plasma chambers typically have a plasma ion density distribution across the surface of the substrate being processed that varies greatly depending upon various processing parameters. These processing parameters, for example, may include the type of process gas or gas mixture introduced into the chamber, the gas pressure, and/or the energy (e.g., RF power, etc.) delivered into the chamber to excite the gas or gas mixture. The plasma ion density may be high, for example, at the substrate center and low at the substrate periphery for one process gas, while for another process gas the plasma ion density may be low at the substrate center and high at the substrate periphery. As a result of these types of processing characteristics, conventional plasma chamber RF coil designs, or electrode designs, are customized for each process or process gas in order to provide a specific plasma uniformity across a substrate surface in the chamber. Multiple RF coil or electrode designs, typically two coils or electrodes, have also been implemented in order to improve plasma uniformity in processing chambers. In these configurations, the first RF coil or electrode is in electrical communication with a first power supply through, for example, a first matching network/circuit, while the second RF coil or electrode is in electrical communication with a second RF power supply through a second matching network/circuit. Therefore, the respective RF power supplies and accompanying matching networks operate to individually control the power supplied to the respective coils or electrodes.
During conventional electronic device fabrication processing methods, the RF power is held constant during a substrate processing sequence. This is undesirable for some processing sequences, because the plasma uniformity over the surface of the substrate generated in a particular processing chamber may be acceptable for one portion of a sequence, while causing substrate damage during another portion of the sequence. Conventional processing chambers may vary the ion density and uniformity by varying pressure in the chamber (the density or flow of the process gas into the chamber) or the power applied to the coils or electrodes. However, varying the gas flow is also undesirable, since the gas flow affects the plasma composition and is harder to control due to transient effects created due to the pressure changes. Uniformity achieved in a plasma processing chamber may also be affected by the interaction of the electric and/or magnetic fields generated by two or more plasma controlling devices (e.g., coils, electrodes, etc.) used in the plasma processing chamber. The interaction of the fields are an inherent part of the chamber design, and fields may interact to a greater degree or to a lesser degree based on the configuration of the chamber hardware and process variable settings. Overlapping fields will constructively interfere, thus increasing the ion density in places where the fields interact and decreasing uniformity and the ability to control the process uniformity.
The uniformity of the generated plasma may vary as the process conditions are varied (e.g., power, pressure, gas mixture, etc.), the number and shape of the plasma controlling devices in the chamber are varied, the way the plasma controlling devices are installed and/or the inherent physical characteristics of the plasma controlling devices and their relative position to the surface of the substrate. To compensate for any plasma non-uniformity, it is common to adjust the configuration of the plasma controlling hardware and/or plasma process variables such as, for example, a continuous power delivered to each plasma controlling device, chamber pressure or the position of the substrate in the plasma. Once all of the various hardware and process related variables have been optimized, the process uniformity may still exceed a desired value due to the interaction of the fields (i.e., magnetic or electric fields) created when power is delivered to a plurality of plasma controlling devices or due to other effects caused by the interaction of the plasma generated by the plasma controlling devices. The non-uniformity in the process results, for example, may create a variation between the center and edge of the substrate or an edge to edge type variation (e.g., right-side/left-side variation, saddle shaped variation, etc.).
Therefore, there is a need for an improved apparatus and methods for controlling plasma uniformity, wherein the apparatus and methods allow for plasma uniformity adjustment without adjusting conventional processing parameters and changing hardware configurations.
SUMMARY OF THE INVENTIONEmbodiments of the invention provide an apparatus for plasma processing a substrate, wherein the apparatus includes first and second plasma controlling devices that are in communication with a processing region of a plasma chamber. The first plasma controlling device and second plasma controlling device are connected to a first RF power source and a second RF power source, respectively. A controller that is connected to the first RF power source and the second RF power source controls the modulation of the amplitude of the RF power supplied to the first plasma controlling device and the second plasma controlling device such that the overlap in time of the RF power supplied to the first and second plasma controlling devices is controlled to improve the uniformity of the plasma process completed on a substrate mounted in the processing region.
Embodiments of the invention further provide an apparatus for plasma processing a substrate, wherein the apparatus includes first and second plasma controlling devices that are in communication with a processing region of a plasma chamber. The first plasma controlling device and second plasma controlling device are connected to a first RF power source and a second RF power source, respectively. A controller that is connected to the first RF power source and the second RF power source synchronizes and controls the amplitude modulation of the RF power supplied to the first plasma controlling device and the second plasma controlling device such that the power, modulation pulse frequency, modulation pulse duration, rest time between modulation pulses, and overlap of the modulation pulse to the first and/or second plasma controlling devices can be varied as a function of time.
Embodiments of the invention further provide an apparatus for plasma processing a substrate, wherein the apparatus includes first, second and third plasma controlling devices that are in communication with a processing region of a plasma chamber. The first plasma controlling device, the second plasma controlling device and the third plasma controlling device are connected to a first RF power source, a second RF power source, and a third RF power source, respectively. A controller that is connected to the first RF power source, the second RF power source and third RF power source controls the modulation of the amplitude of the RF power supplied to the first, the second and the third plasma controlling devices such that the overlap in time of the RF power supplied to the first and second plasma controlling devices is controlled to improve the uniformity of the plasma process completed on a substrate mounted in the processing region.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes amplitude modulating the RF power to a first plasma controlling device and a second plasma controlling device. The method generally includes modulating the pulse frequency and RF power level, to each of the plasma controlling devices, synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device; and controlling the amplitude modulation of the RF power such that the overlap of the amplitude modulated RF power delivered to the first and second plasma controlling devices is controlled to improve the uniformity of the process completed on the substrate.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes generating first and second torroidal paths of plasma, which are not coincident, that pass near and traverse the surface of a substrate. The method generally includes varying the plasma density in the vicinity of the substrate by amplitude modulating the first torroidal path of plasma at a first modulation pulsing frequency and a first RF power and modulation pulsing the second torroidal path of plasma at a second modulation pulsing frequency and a second RF power as a function of time.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes generating a plasma over a first area of a substrate and a second area of a substrate, wherein the first plasma controlling device generates a plasma in a first region near the substrate and the second plasma controlling device generates a plasma in a second region near the substrate and the first and second regions overlap. The method also generally includes varying the plasma density generated in the first region, in the second region, and a region between the first and second region by amplitude modulating the RF power delivered to the first plasma controlling device and the second plasma controlling device.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes amplitude modulating the RF power to a first plasma controlling device and a second plasma controlling device. The method also includes varying the modulation pulse frequency and RF power level, to each of the plasma controlling devices and synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device to adjust the plasma density in the plasma chamber to compensate for a non-uniform area on a substrate surface.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes amplitude modulating the RF power to a first plasma controlling device and a second plasma controlling device. The method also includes amplitude modulating the RF power delivered to each of the plasma controlling devices, synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device, and controlling the shape of the amplitude modulated RF power, wherein the shape of the modulated RF power is rectangular, triangular, trapezoidal or sinusoidal.
Embodiments of the invention further provide a method for processing a substrate in a plasma chamber, wherein the method includes amplitude modulating the RF power to a first plasma controlling device and a second plasma controlling device. The method also includes amplitude modulating the RF power delivered to each of the plasma controlling devices, synchronizing the amplitude modulation of the RF power to the first and the second plasma controlling devices, controlling the shape of the amplitude modulation of the RF power, and controlling the overlap and/or gap between the amplitude modulated RF power to the first and second plasma controlling devices.
BRIEF DESCRIPTION OF THE DRAWINGSSo that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Embodiments of the present invention generally provide etch or CVD plasma processing methods and apparatus used to generate a uniform etch or deposition profile on the surface of a substrate by modulating the amplitude of the RF power delivered to a plurality of plasma controlling devices associated with a plasma processing chamber. The amplitude modulated RF power, delivered to the plasma controlling devices, generates a uniform plasma, which thus develops the uniform etch or deposition profile. The plasma generated and/or sustained in the plasma processing chamber is created by the one or more plasma controlling devices that are used to control, generate, enhance, and/or shape the plasma during the plasma processing steps by use of energy delivered from a RF power source. A plasma controlling device may include, for example, one or more coils (inductively coupled plasma), one or more electrodes (capacitively coupled plasma), a substrate pedestal, and/or any other energy inputting device such as a microwave source.
Embodiments of the invention are used to correct process non-uniformities by synchronizing the amplitude modulation of the RF power delivered to each plasma controlling device to reduce the interaction of the field(s) created by the plasma controlling devices, overcome inherent chamber design shortcomings, and/or hardware installation issues. By varying the nature and extent of interaction of the fields, and generated plasma, created by the plasma controlling devices, a temporal and spatial variation in the plasma density can be controlled and thus averaged over the plasma processing time to yield a desired process result. The term “spatial variation” in the plasma density is meant to denote a change in the plasma density (or composition) over a localized area of the substrate and/or a shifting, or translation, of the generated plasma across the surface of the substrate. The term “temporal variation” in the plasma density is meant to denote any change in the plasma density (or composition) over a localized area of the substrate as a function of time.
In operation, embodiments of the invention generally provide a plasma-based electronic device fabrication processing sequence, wherein the plasma uniformity or flux of ions and neutrals at the surface of a substrate is varied during the processing sequence to achieve more uniform process results on the surface of the substrate. Therefore, embodiments of the invention allow for an infinite number of variations in plasma and/or etch uniformity within a processing sequence, and within recipe steps of the processing sequence, and generally do not require any disassembly or reconfiguration of the plasma controlling devices in order to accomplish plasma uniformity variation. Embodiments of the invention generally provide for varying the plasma uniformity by modulating the amplitude of the RF power delivered to each of the plasma controlling devices as a function of time, since the plasma uniformity and plasma ion density are directly affected by the magnetic field strength or electric field strength in the plasma region of the chamber. A single recurring component of the amplitude modulated RF power waveform, or modulation pulse, can have an infinite number of shapes. FIGS. 12A-C illustrate three examples of amplitude modulated RF power waveforms, or modulation pulse 4 (or modulating waveform), and the underlying amplitude modulated RF power 3 (or carrier). In configurations that contain more than two plasma controlling devices, it may be possible, for example, to vary the order of the modulation pulses delivered to each plasma controlling device as a function of time (e.g., the order of the modulation pulse delivered to the plasma controlling devices need not be sequential, etc.), the length of the modulation pulse, and the power level needed to achieve the desired uniformity across the substrate. In various embodiments of the invention, the frequency of the modulation pulse may vary between about 0.1 hertz and about 100,000 hertz, but preferably varies between about 0.1 hertz and about 10,000 hertz. The power delivered to each of the plasma controlling devices may vary between about 0 Watts to about 5000 Watts at a RF frequency of about 13.56 MHz. The frequency of the power delivered by the RF power source is not limited to frequencies around 13.56 MHz and may be run at frequencies between about 0.4 MHz to greater than 10 GHz.
The amplitude modulated RF power delivered to each of the plasma controlling devices is synchronized and controlled by use of a controller 300 (see
The controller 300 in conjunction with an RF power source, for example, RF power source 180 (see
Hardware Configurations
The torroidal plasma source 172, or torroidal type of plasma controlling device, generally contains a conduit 150, a magnetically permeable core 1015, antenna 170, an impedance match element 175, and a RF power source 180. The antenna 170, which includes a winding or coil section, is wound around a closed magnetically permeable core 1015, which surrounds the conduit 150. The closed magnetically permeable core 1015 is used to inductively couple to the plasma generated inside the hollow conduit 150 by use of the antenna 170, the impedance match element 175, and the RF power source 180. In one embodiment, dynamic impedance matching may be provided to the antenna 170 by frequency tuning, impedance matching network tuning or frequency tuning with forward power servoing. In an alternate embodiment an impedance match may be achieved without the impedance match element 175 by using, instead, a secondary winding 1120 (not shown) around the core 1015 connected across a tuning capacitor 1130 (not shown). The capacitance of the tuning capacitor 1130 (not shown) is selected to resonate the secondary winding 1120 (not shown) at the frequency of the RF power source 180. For a fixed tuning capacitor 1130 (not shown), dynamic impedance matching may be provided.
The half-torroidal hollow tube enclosure or conduit 150 extends above the ceiling 110 in a half circle. The conduit 150, although extending externally outwardly from ceiling 110, is nevertheless part of the chamber and forms a wall of the chamber. Internally the conduit 150 shares the same evacuated atmosphere as exists elsewhere in the chamber. The conduit 150 has one open end 157 sealed around a first opening, port 155, in the chamber ceiling 110 and its other end 158 sealed around a second opening, port 160, in the chamber ceiling 110. The two openings, port 155 and port 160, are located on generally opposite sides of the substrate pedestal 115. The hollow conduit 150 is reentrant in that it provides a flow path which exits the main portion of the chamber at one opening and re-enters at the other opening. The conduit 150 may be described herein as being half-torroidal, in that the conduit is hollow and provides a portion of a closed path in which plasma generated in the conduit 150 may flow across the process region overlying the substrate pedestal 115. Notwithstanding the use of the term “torroidal”, the trajectory of the closed path as well as the cross-sectional shape of the path or conduit 150 may be circular or non-circular, and may be square, rectangular or any other shape, regular or irregular.
In order to avoid edge effects at the substrate periphery, the ports 155 and 160 are separated by a distance that exceeds the diameter of the substrate. For example, for a 12-inch diameter substrate, the ports 155 and 160 are about 16 to 22 inches apart. For an 8-inch diameter substrate, the ports 155 and 160 are about 10 to 16 inches apart.
The external conduit 150 may be formed of a relatively thin conductor such as sheet metal and may contain a first insulating gap 152 and a second insulating gap 153 filled with an insulating ring 154 made from a ceramic material. The insulating gaps, which extend across and through the conduit 150, suppress eddy currents in the sheet metal of the hollow conduit 150 and thereby facilitate coupling of an RF inductive field into the interior of the conduit 150. An RF power source 162 applies RF bias power to the substrate pedestal 115 and substrate 120 through an impedance match element 164. In one embodiment, dynamic impedance matching may be provided to the substrate pedestal by frequency tuning, impedance matching network tuning or frequency tuning with forward power servoing which are well known in the art.
Process gases from the chamber 100 fill the hollow conduit 150. In addition, a separate process gas supply 190 may supply process gases directly into the hollow conduit 150 through a gas inlet 195. The RF field in the external hollow conduit 150 ionizes the gases in the tube to produce a plasma. The RF field induced by the magnetically permeable core 1015 is such that the plasma formed in the conduit 150 reaches through the region between the substrate 120 and the ceiling 110 to complete a torroidal path that includes the half-torroidal hollow conduit 150. As employed herein, the term “torroidal” refers to the closed and solid nature of the path, but does not refer to or limit its cross-sectional shape or trajectory, either of which may be circular or non-circular or square or otherwise. Plasma circulates through the complete torroidal path or region which may be thought of as a closed plasma circuit or plasma current path. The RF inductive field generated in the conduit 150 by the closed magnetically permeable core 1015 is closed, as are all magnetic fields, and therefore induces a plasma current along the closed torroidal path. The current is generally uniform along the closed path length and alternates at the frequency of the RF signal applied to the closed magnetically permeable core 1015 by the RF power source 180 through the antenna 170 is varied. The torroidal region extends across the diameter of the substrate 120 and, in certain embodiments, has a sufficient width in the plane of the substrate so that it overlies the entire substrate surface.
By modulation pulsing the RF power delivered to the plasma controlling devices, the first conduit and the second conduit, it has been found that the uniformity of the plasma process can be improved. By adapting the hardware and processing steps, various plasma modulation pulsing recipes can be utilized to improve the processing uniformity. The RF power modulation pulse characteristics may be varied, for example, at the transition between recipe steps in a plasma processing chamber recipe, at one or more times within individual recipe steps of a plasma processing chamber recipe, or continuously throughout the plasma processing process. In one embodiment, a user is able to input the desired modulation pulse characteristics (as described above) and other process variables, for example, chamber pressure, gas types, gas flow rates, etc., into a recipe from which the controller 300 is able to monitor and control all aspects of the plasma chamber process.
In operation, the plasma processing system receives a substrate 120 on substrate pedestal 115 for processing in plasma chamber 10. Plasma chamber 10 may then be pulled to a predetermined pressure/vacuum by a vacuum pump system (not shown). Once the predetermined pressure is achieved, a process gas may be introduced into the plasma chamber 10 by gas inlet 25, while the vacuum pumping system continues to pump the plasma chamber 10, such that an equilibrium processing pressure is obtained. The processing pressure is adjustable through, for example, throttling the communication of the vacuum system to the plasma chamber 10 or adjusting the flow rate of the process gases being introduced into plasma chamber 10 by gas inlet 25. Once the pressure and gas flows are established, the respective power supplies may be activated. Power can be independently supplied to the first RF coil 52 and second RF coil 54, and the substrate pedestal 115. The application of power to the first RF coil 52 and second RF coil 54 facilitates striking of a plasma in the region immediately above the substrate pedestal 115. The ion density of the plasma may be increased or decreased through adjustment of the power supplied to the first RF coil 52 and second RF coil 54 or through adjustment of the processing pressure in plasma chamber 10, that is, through increased/decreased flow rate of the process gas or an increase/decrease in the chamber pumping rate.
The inductively coupled plasma processing chamber, illustrated in
In one embodiment of the plasma processing chamber 400 the gas distribution showerhead 410 (not shown) is not RF biased. In this embodiment RF power is only delivered to a side electrode 450 and a substrate pedestal 115 (not shown). A controller 300 is adapted to control the impedance match elements (i.e., 428, 164 and 175A (if biased)), the RF power sources (i.e., 429, 162 and 180A (if biased)) and all other aspects of the plasma process.
The uniformity of the generated plasma in the capacitively coupled plasma processing chambers 305, 320 and 400 may vary depending on the process conditions are varied (e.g., power, pressure, gas mixture, etc.), the way the plasma controlling devices are positioned, the position of the substrate in the plasma and/or the inherent physical characteristics (e.g., surface characteristics, surface area, etc.) of the plasma controlling devices. By use of aspects described herein, the plasma uniformity can be optimized by modulation pulsing the power delivered to the plasma controlling devices (e.g., showerhead 410, second electrode 415 (
In addition to amplitude modulating the RF power to coils, electrodes, torroidal sources relative to each other, as described above, in some embodiments of the invention the RF power delivered to the substrate pedestal is modulation pulsed relative to one or more plasma controlling devices in the chamber, for example, a torroidal plasma source, an RF coil 52, an RF coil 54, a showerhead 210, etc. Modulation pulsing the RF power to the substrate pedestal relative to other plasma controlling devices can: reduce RF field interaction between the substrate pedestal and the plasma controlling device(s), shape the plasma, control plasma bombardment of the substrate surface, and/or vary the plasma sheath thickness and/or voltage.
In another aspect of the invention, two or more RF power sources are attached to the substrate pedestal 115 mounted in a torroidal plasma processing chamber, an inductively coupled plasma processing chamber or a capacitively coupled plasma processing chamber.
In another aspect of the invention, the substrate pedestal 115 contains two or more segmented regions that are RF biasable as illustrated in
Amplitude Modulation Control
While the embodiments illustrated in
Other embodiments of the invention having different modulation pulse shapes may be devised without departing from the basic scope of the present invention. In one embodiment, the ramp up to the peak power and/or the ramp down from the peak power may not be linear, as shown in
The following non-limiting examples are provided to further illustrate embodiments of the invention. However, the examples are not intended to be all-inclusive and are not intended to limit the scope of the inventions described herein.
Example 1Examples of different plasma processing recipes utilizing an amplitude modulation of RF power delivered to an orthogonal two plasma controlling device torroidal source are described below for a silicon dioxide etching process. The general process parameters used to etch the surface of a substrate having a silicon dioxide thickness of 20,000 Angstroms are as follows: a chamber process pressure of 30 mTorr, a flow rate of 60 sccm of hexafluoro-1,3-butadiene (C4F6), a flow rate of 60 sccm of oxygen (O2), a flow rate of 500 sccm of argon, a substrate pedestal temperature of 20 degrees Celsius, a substrate backside helium pressure of 25 Torr, a constant substrate pedestal bias of 2000 Watts at a RF frequency of 13.56 MHz, and a plasma processing time of 60 seconds. All RF power delivered to the other plasma controlling devices was delivered using dynamic impedance matching at an RF frequency of about 13.56 MHz+/−1 MHz. The 1 sigma, or 1 standard deviation, uniformity values discussed below were measured using a Tencor Prometrix UV 1050's 49-point contour map at a substrate edge exclusion of 3 millimeters. The Tencor Prometrix UV 1050's 49-point contour map uniformity data was collected by measuring the difference, or change, in the surface profile of the substrate before and after plasma etching.
Example 1AUsing a constant RF power level of 1000 Watts to both of the plasma controlling devices achieved an average etch rate of 3400 Angstroms/minute and a uniformity of about 8.4%.
Example 1B An average etch rate of 4930 Angstroms/minute and uniformity of about 1.6% was achieved using a rectangular-shaped amplitude modulated RF power pulse sequence, as shown in
An average etch rate of 5027 Angstroms/minute and uniformity of about 1.5% was achieved using a rectangular-shaped amplitude modulated RF power pulse sequence, as shown in
An average etch rate of 4602 Angstroms/minute and uniformity of about 1.2% was achieved using a rectangular-shaped amplitude modulated RF power pulse sequence, as shown in
An average etch rate of 4170 Angstroms/minute and uniformity of about 2.7% was achieved using a rectangular-shaped amplitude modulated RF power pulse sequence, as shown in
An average etch rate of 3522 Angstroms/minute and uniformity of about 8.7% was achieved using a rectangular-shaped amplitude modulated RF power pulse sequence, as shown in
In one aspect, by varying the frequency of the amplitude modulation of the RF power, or the modulation pulse frequency, it is possible to vary the plasma density across the surface of the substrate. In one embodiment the frequency of the amplitude modulation of the RF power is varied at various times during the process to tailor the plasma density to match a desired etch or deposition profile on the surface of the substrate. In cases where the user knows the profile of the surface of the substrate prior to processing in the plasma chamber, varying the modulation pulse frequency during plasma processing can allow the etch or deposition profile to be adjusted to compensate for the initial non-uniformity. For example, in a case where the starting substrate profile is edge thick versus the center of the substrate the modulation pulse frequency can be varied to increase the plasma density near the edge of the substrate relative to the center of the substrate to assure the results of the plasma process are uniform. Since each plasma processing chamber configuration, process sequence, and process recipe can cause the etch or deposition plasma density to vary from chamber to chamber, sequence to sequence and/or recipe to recipe it is likely that an optimum frequency to achieve a desired plasma density profile will need to be empirically found. An example of such results are shown in Example 2 below.
Example 2FIGS. 13A-E illustrate examples of how varying the amplitude modulation pulse characteristics in a plasma processing chamber can vary the plasma density across the surface of the substrate. The results shown below were collected using an orthogonal two plasma controlling device torroidal source utilizing a rectangular-shaped amplitude modulation of RF power to complete a silicon dioxide etching process. The general process parameters used to etch the surface of a substrate having a silicon dioxide thickness of 20,000 Angstroms are as follows: a chamber process pressure of 30 mTorr, a flow rate of 60 sccm of hexafluoro-1,3-butadiene (C4F6), a flow rate of 60 sccm of oxygen (O2), a flow rate of 500 sccm of argon, a substrate pedestal temperature of 20 degrees Celsius, a substrate backside helium pressure of 25 Torr, a constant substrate pedestal bias of 2000 Watts at a RF frequency of 13.56 MHz, and a plasma processing time of 60 seconds. All RF power delivered to the other plasma controlling devices was delivered using dynamic impedance matching at an RF frequency of about 13.56 MHz+/−1 MHz. The same hardware configuration process configurations were used throughout this example. The 1 sigma, or 1 standard deviation, uniformity values described herein were measured using a Tencor Prometrix UV 1050's 49 point contour map at a substrate edge exclusion of 3 millimeters. The Tencor Prometrix UV 1050's 49 point contour map uniformity data was collected by measuring the difference, or change, in the surface profile of the substrate before and after plasma etching.
FIGS. 13A-D illustrate Tencor Prometrix UV 1050 49-point contour maps of the production surface of an etched silicon dioxide layer on a substrate using a rectangular-shaped amplitude modulated RF power, similar to the RF power modulation profiles shown in
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims
1. A plasma chamber for plasma processing a substrate, comprising:
- a first plasma controlling device in communication with a processing region of a plasma chamber, wherein the first plasma controlling device is connected to a first RF power source;
- a second plasma controlling device in communication with the processing region of the plasma chamber, wherein the second plasma controlling device is connected to a second RF power source; and
- a controller adapted to synchronize the amplitude modulation of the RF power delivered to the first plasma controlling device and the second plasma controlling device such that the shape of the amplitude modulated waveform and overlap in time of the RF power supplied to the first and second plasma controlling devices is controlled to improve the uniformity of the plasma process completed on a substrate mounted in the processing region.
2. The plasma chamber of claim 1, wherein the controller, the first RF power source, and the second RF power source modulate the amplitude of the RF power, and wherein modulating the amplitude of the RF power includes synchronizing the RF power delivered to the first and second plasma controlling devices, controlling the ratio of power delivered to the first and second plasma controlling devices, and controlling the shape and duration of the amplitude modulated power.
3. The plasma chamber of claim 1, wherein the shape of the amplitude modulated RF power supplied to the first and second plasma controlling devices, is rectangular in shape, trapezoidal in shape, triangular in shape or sinusoidal in shape.
4. The plasma chamber of claim 1, wherein the amplitude modulated RF power is rectangular in shape and the amplitude modulated RF power supplied to the second plasma controlling devices is at 0 Watts when the first plasma controlling device is at a power level greater than 0 Watts, and the amplitude modulated RF power supplied to the first plasma controlling devices is 0 Watts when the second plasma controlling device is at a power level greater than 0 Watts.
5. The plasma chamber of claim 1, wherein the amplitude modulated RF power is rectangular in shape and the amplitude modulated RF power supplied to the first plasma devices and the second plasma controlling device overlap an amount less than the full pulse width.
6. The plasma chamber of claim 1, wherein the controller, the first RF power source, and the second RF power source control the interaction of the plasma generated by the first and second plasma controlling devices by varying the frequency of the amplitude modulations of the RF power.
7. The plasma chamber of claim 1, wherein the overlap in time is a rest time between the amplitude modulations of the RF power.
8. The plasma chamber of claim 1, wherein the first plasma controlling device is an inductive coil, an electrode or a torroidal source.
9. The plasma chamber of claim 1, wherein the second plasma controlling device is an inductive coil, an electrode or a torroidal source.
10. The plasma chamber of claim 1, further comprising a pedestal that is adapted to support the substrate, wherein the pedestal is connected to a third RF power source that is capable of amplitude modulation of the RF power delivered to the pedestal.
11. The plasma chamber of claim 10, further comprising a fourth RF power source connected to the pedestal that is capable of amplitude modulation of the RF power delivered to the pedestal, wherein the RF frequency of the fourth RF power source is greater than the RF frequency of the third RF power source.
12. A plasma chamber for processing a substrate, comprising:
- a first plasma controlling device connected to a first RF power source that is capable of amplitude modulation of the RF power delivered to the first plasma controlling device;
- a second plasma controlling device connected to a second RF power source that is capable of amplitude modulation of the RF power delivered to the second plasma controlling device;
- a third plasma controlling device connected to a third RF power source that is capable of amplitude modulation of the RF power delivered to the third plasma controlling device; and
- a controller adapted to synchronize the amplitude modulation of the RF power delivered to the first plasma controlling device, the second plasma controlling device and the third plasma controlling device such that the shape of the amplitude modulated waveform and overlap in time of the RF power supplied to the first, second and third plasma controlling devices is controlled to improve the uniformity of the plasma process completed on a substrate mounted in the processing region.
13. The plasma chamber of claim 12, wherein the first plasma controlling device is an inductive coil, an electrode, or a torroidal source.
14. The plasma chamber of claim 12, wherein the second plasma controlling device is an inductive coil, an electrode, or a torroidal source.
15. The plasma chamber of claim 12, wherein the third plasma controlling device is a torroidal source, an inductive coil, or a electrode.
16. The plasma chamber of claim 12, further comprising a pedestal that is adapted to support the substrate, wherein the pedestal is connected to a fourth RF power source that is capable of amplitude modulation of the RF power delivered to the pedestal.
17. The plasma chamber of claim 16, further comprising a fifth RF power source connected to the pedestal that is capable of amplitude modulation of the RF power delivered to the pedestal, wherein the RF frequency of the fifth power source is greater than the RF frequency of the fourth RF power source.
18. The plasma chamber of claim 12, wherein the overlap in time is a rest time between the amplitude modulations of the RF power.
19. A method of processing a substrate in a plasma chamber, comprising:
- amplitude modulating the RF power delivered to a first plasma controlling device at a first modulation pulse frequency and at a first power level;
- amplitude modulating the RF power delivered to a second plasma controlling device at a second modulation pulse frequency and at a second power level;
- synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device; and
- controlling the amplitude modulation of the RF power such that the overlap in time and the shape of the amplitude modulated RF power delivered to the first and second plasma controlling devices is controlled to improve the uniformity of the process completed on the substrate.
20. The method of claim 19, wherein the first modulation pulsing frequency and the second modulation pulsing frequency are between about 0.1 Hz and about 100,000 Hz.
21. The method of claim 19, wherein the first RF power level and the second RF power level are between about 0 Watts and about 5000 Watts.
22. The method of claim 19, wherein the ratio of the first RF power level to the second RF power level or the second RF power level to the first RF power level is between about 1:1 and about 100:1.
23. The method of claim 19, wherein the first plasma controlling device is an inductive coil, an electrode, or a torroidal source.
24. The method of claim 19, wherein the second plasma controlling device is an inductive coil, an electrode or a torroidal source.
25. The method of claim 19, wherein the amplitude modulating of the RF power supplied to the second plasma controlling devices is less than the first plasma controlling device at a first time, and the RF power supplied to the first plasma controlling devices is less than the second plasma controlling device at a second time.
26. The method of claim 19, wherein the shape of the amplitude modulated RF power is rectangular in shape, trapezoidal in shape, triangular in shape or sinusoidal in shape.
27. The method of claim 19, further comprising:
- amplitude modulating the RF power delivered to a third plasma controlling device at a third modulation pulsing frequency and at a third power level;
- synchronizing the amplitude modulating of the RF power to the first, second and third plasma controlling devices; and
- controlling the amplitude modulation of the RF power such that the overlap of the amplitude modulated RF power delivered to the first, second and third plasma controlling devices is controlled to improve the uniformity of the process completed on the substrate.
28. A method of processing a substrate in a plasma chamber, comprising:
- generating a first torroidal path of plasma that passes near and transverse a surface of the substrate using a first torroidal plasma controlling device;
- generating a second torroidal path of plasma that passes near and transverse a surface of the substrate using a second torroidal plasma controlling device, wherein the first torroidal path is not coincident to the second torroidal path; and
- varying the plasma density in the vicinity of the substrate by amplitude modulating the first torroidal path of plasma at a first modulation pulsing frequency and a first RF power and modulation pulsing the second torroidal path of plasma at a second modulation pulsing frequency and a second RF power as a function of time.
29. The method of claim 28, wherein the first modulation pulsing frequency and the second modulation pulsing frequency are between about 0.1 Hz and about 100,000 Hz.
30. The method of claim 28, wherein the first RF power level and the second RF power level are between about 0 Watts and about 5000 Watts.
31. The method of claim 28, wherein the ratio of the first RF power to the second RF power level is between about 1:1 and about 100:1.
32. A method of processing a substrate in a plasma chamber, comprising:
- generating a plasma over a surface of a substrate using a first plasma controlling device;
- generating a plasma over a surface of the substrate using a second plasma controlling device, wherein the first plasma controlling device generates a plasma in a first region near the substrate and the second plasma controlling device generates a plasma in a second region near the substrate and the first and second regions overlap; and
- varying the plasma density generated in the first region, in the second region, and a region between the first and second region by amplitude modulating the RF power delivered to the first plasma controlling device and the second plasma controlling device.
33. The method of claim 32, wherein the first modulation pulse frequency and the second modulation pulse frequency are between about 0.1 Hz and about 100,000 Hz.
34. The method of claim 32, wherein the first RF power level and the second RF power level are between about 0 Watts and about 5000 Watts.
35. The method of claim 32, wherein the ratio of the first RF power to the second RF power ev is between about 1:1 and about 100:1.
36. The method of claim 32, wherein the first plasma controlling device is a first inductive coil and the second plasma controlling device is a second inductive coil.
37. The method of claim 32, wherein the first plasma controlling device is a first electrode and the second plasma controlling device is a second electrode.
38. The method of claim 32, wherein the first plasma controlling device is a first torroidal source and the second plasma controlling device is a second torroidal source.
39. A method of processing a substrate in a plasma chamber, comprising:
- amplitude modulating the RF power to a first plasma controlling device at a first modulation pulse frequency and at a first power level;
- amplitude modulating the RF power to a second plasma controlling device at a second modulation pulse frequency and at a second power level;
- synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device; and
- varying the first and second modulation pulse frequencies to adjust the plasma density in a plasma chamber to compensate for a non-uniform area on a substrate surface.
40. A method of processing a substrate in a plasma chamber, comprising:
- amplitude modulating the RF power to a first plasma controlling device at a first modulation pulse frequency and at a first power level;
- amplitude modulating the RF power to a second plasma controlling device at a second modulation pulse frequency and at a second power level;
- synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device; and
- controlling the shape of the amplitude modulated RF power to the first and second plasma controlling devices, wherein the shape of the amplitude modulated RF power is rectangular, trapezoidal, triangular or sinusoidal.
41. A method of processing a substrate in a plasma chamber, comprising:
- amplitude modulating the RF power to a first plasma controlling device at a first modulation pulse frequency and at a first power level;
- amplitude modulating the RF power to a second plasma controlling device at a second modulation pulse frequency and at a second power level;
- synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device,
- controlling the shape of the amplitude modulated RF power to the first and second plasma controlling devices; and
- controlling the overlap and/or gap between the amplitude modulated RF power to the first plasma controlling device and the second plasma controlling device.
42. A method of processing a substrate in a plasma chamber, comprising:
- amplitude modulating the RF power to a first plasma controlling device at a first modulation pulse frequency and at a first power level;
- amplitude modulating the RF power to a second plasma controlling device at a second modulation pulse frequency and at a second power level;
- synchronizing the amplitude modulation of the RF power to the first plasma controlling device and the second plasma controlling device,
- controlling the amplitude modulation of the RF power to the first plasma controlling device and amplitude modulation of the RF power to the second plasma controlling device such that the power, modulation pulse frequency, modulation pulse duration, rest time between modulation pulses, and overlap of the modulation pulse to the first and/or second plasma controlling devices can be varied as a function of time.
Type: Application
Filed: Feb 18, 2005
Publication Date: Nov 3, 2005
Applicant:
Inventors: Alexander Paterson (San Jose, CA), Elizabeth Pavel (San Jose, CA), Valentin Todorow (Palo Alto, CA), Huong Nguyen (San Ramon, CA), Thomas Kropewnicki (San Mateo, CA), Brian Hatcher (San Jose, CA), John Holland (San Jose, CA)
Application Number: 11/060,980