METHODS AND APPARATUS FOR PLASMA LINERS WITH HIGH FLUID CONDUCTANCE
Methods and apparatus for confining plasma in a process chamber. In some embodiments, the apparatus includes a first liner with a first set of openings, the first liner configured to surround a substrate support when installed and a second liner with a second set of openings, the second liner configured to surround the substrate support under the first liner when installed, wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.
This application claims benefit of U.S. provisional patent application Ser. No. 62/722,000, filed Aug. 23, 2018 which is herein incorporated by reference in its entirety.
FIELDEmbodiments of the present principles generally relate to semiconductor processing.
BACKGROUNDPlasma is often used in semiconductor manufacturing. For example, some processes form a plasma for deposition of material on a substrate. Thus, the plasma is beneficial to the deposition process as long as the generated plasma is contained in an area where deposition is desired. If not contained, the plasma may have negative effects such as deposition on parts of the chamber itself or may cause arcing between parts of the chamber which causes pitting and other damage including defects in substrates. To prevent unwanted plasma effects, liners may be employed in a semiconductor chamber to help contain the plasma and prevent damage. One such liner may surround the substrate platform to prevent plasma from reaching the backside of the substrate. The liner is usually made from a fine mesh to control the plasma while allowing some gas flow to an exhaust pump located below the substrate. While the fine mesh liner may provide sufficient plasma control, the inventors have found that the fine mesh liner has very poor gas conductance. The poor gas conductance significantly inhibits the evacuation of gases in the semiconductor processing chamber, slowing the production rate.
Accordingly, the inventors have provided improved methods and apparatus for containing plasma in a semiconductor chamber while increasing gas conductance.
SUMMARYMethods and apparatus for plasma liners with high fluid conductance for use in semiconductor processing are provided herein.
In some embodiments, an apparatus for confining plasma in a process may comprise a first liner with a first set of openings for fluid flow, the first liner configured to surround a substrate support of the process chamber when installed in the process chamber and a second liner with a second set of openings for fluid flow, the second liner configured to surround the substrate support of the process chamber under the first liner when installed in the process chamber, wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.
In some embodiments, the apparatus may further comprise wherein the first liner or the second liner is electrically conductive, wherein the first liner or the second liner is formed form an aluminum based material, wherein the first liner or the second liner is coated with a yttrium-based material, wherein the first liner or the second liner is electrically grounded, wherein the first liner or the second liner is configured to form a symmetrical radio frequency (RF) ground return path when installed in the process chamber, wherein the first liner and the second liner are configured to be spaced apart vertically from approximately 0.25 inches to approximately 0.375 inches when installed in the process chamber, wherein a vertical distance between the first liner and the second liner is configured to be adjustable when installed in the process chamber, wherein a distance from a top surface of the first liner and a top surface of the substrate support is configured to be adjustable when the first liner is installed in the process chamber, wherein the first set of openings or the second set of openings is configured in size to prevent parasitic plasma formation when the first liner or second liner is installed in the process chamber, wherein the first liner has a first key for maintaining a first orientation when installed in the process chamber and the second liner has a second key for maintaining a second orientation when installed in the process chamber, wherein the first orientation of the first liner and the second orientation of the second liner yields an offset that provides no line-of-sight through the first liner and the second liner from a top down viewpoint when installed in the process chamber, wherein the first liner and the second liner are ohmically connected via at least one conductive gasket, and/or wherein the first liner or second liner is circular in shape with an inner cutout, wherein the first set of openings or the second set of openings, respectively, extend radially outward from an inner edge near the inner cutout towards an outer edge of the first liner or the second liner, respectively.
In some embodiments, an apparatus for confining plasma in a process chamber may comprise a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner under the first conductive liner when installed in the process chamber.
In some embodiments, the apparatus may further comprise wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber, wherein the first conductive liner has a vertical inner periphery wall that is configured to be grounded to the substrate support when installed in the process chamber, and/or wherein the first conductive liner has a vertical outer periphery wall with an uppermost portion that is configured to make ohmic contact with a ground of the process chamber.
In some embodiments, an apparatus for confining plasma in a process chamber may comprise a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner above the first conductive liner when installed in the process chamber.
In some embodiments, the apparatus may further comprise wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber, and/or wherein the first conductive liner has a top inner periphery edge portion that is configured to make ohmic contact with a bottom inner periphery edge portion of the second conductive liner and a top outer periphery edge portion that is configured to make ohmic contact with a bottom outer periphery edge portion of the second conductive liner when installed in the process chamber.
Other and further embodiments are disclosed below.
Embodiments of the present principles, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the principles depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the principles and are thus not to be considered limiting of scope, for the principles may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
DETAILED DESCRIPTIONThe methods and apparatus provide a chamber liner for containing plasma in a semiconductor process chamber that has high fluid conductance and provides a uniform RF return path between the chamber liner and chamber ground. The chamber liner provides a continuous conductive boundary for RF currents in plasma to return back to the source and also incorporates, at the same time, symmetrical non-line-of-sight multiple pumping slots or openings. The non-line-of-sight pumping slots are achieved by a staggered, two plane structure at different heights with each layer having pump slots that are offset from pump slots in the other layer. From a top down vantage point, the plasma boundary provided by the chamber liner appears as a continuous liner. Unlike a traditional approach that uses a fine metal grid with hole sizes selected to confine the plasma, the chamber liner according to the present principles does not inhibit fluid conductance and may provide approximately 40 percent to approximately 50 percent or more increased fluid conductance over traditional approaches.
In some embodiments of the present principles, the two plane, staggered approach provides an equipotential continuous metal structure for plasma RF currents to return while providing high gas conductance for evacuating the process chamber quickly, improving throughput and reducing costs. Large, symmetrical pumping slots in each plane allow high gas conductance while the staggered relationship of the pumping slots in each plane provide no direct line-of-sight to the plasma to minimize unpredictable parasitic plasma ignition. The inventors have found that with traditional approaches, images of the pumping ports of a process chamber may be found on wafers after processing. The images are caused by the highly restrictive screens of traditional approaches that inhibit gas flow except for high vacuum areas directly above the pumping ports. The non-uniform flow pattern caused by the restrictive screens affects the processing of the wafer near the pumping port locations. By using embodiments of the present principles, uniform flow conductance is maintained and wafer processing issues caused by the pumping port locations are minimized or eliminated altogether.
The gas distribution plate assembly 204 is positioned on the chamber body 202. A power source 211, such as a radio frequency (RF) power source, is coupled to gas distribution plate assembly 204 to electrically bias the gas distribution plate assembly 204 relative to the substrate support 206 to facilitate plasma generation within the process chamber 200. The substrate support 206 includes an electrostatic chuck 218, in which the electrostatic chuck 218 may be connected to a power source 209a to facilitate chucking of the substrate 201 and/or to influence a plasma located within the processing volume 208. The power source 209a includes a power supply, such as a DC or RF power supply, and is connected to one or more electrodes 220 of the electrostatic chuck 218. A bias source 209a may additionally or alternatively be coupled with the substrate support 206 to assist with plasma generation and/or control, such as to an edge ring assembly. The bias source 209b may illustratively be a source of up to about 1000 W (but not limited to about 1000 W) of RF energy at a frequency of, for example, approximately 13.56 MHz, although other frequencies and powers may be provided as desired for particular applications. The bias source 209b is capable of producing either or both of continuous or pulsed power. In some aspects, the bias source may be capable of providing multiple frequencies, such as 13.56 MHz and 2 MHz.
The process chamber 200 may also include a controller 295. The controller 295 includes a programmable central processing unit (CPU) 296 that is operable with a memory 297 and a mass storage device, an input control unit, and a display unit (not shown), such as power supplies, clocks, cache, input/output (I/O) circuits, and the liner, coupled to the various components of the processing system to facilitate control of the substrate processing. To facilitate control of the process chamber 200 described above, the CPU 296 may be one of any form of general purpose computer processor that can be used in an industrial setting, such as a programmable logic controller (PLC), for controlling various chambers and sub-processors. The memory 297 is coupled to the CPU 296 and the memory 297 is non-transitory and may be one or more of random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote. Support circuits 298 are coupled to the CPU 296 for supporting the processor. Applications or programs for charged species generation, heating, and other processes are generally stored in the memory 297, typically as software routine. The software routine may also be stored and/or executed by a second CPU (not shown) that is remotely located from the process chamber 200 being controlled by the CPU 296.
The memory 297 is in the form of computer-readable storage media that contains instructions, when executed by the CPU 296, to facilitate the operation of the process chamber 200. The instructions in the memory 297 are in the form of a program product such as a program that implements the method of the present disclosure. The program code may conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on a computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the aspects (including the methods described herein). Illustrative computer-readable storage media include, but are not limited to: non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are aspects of the present principles.
The plasma liners 310A, 310B include an upper plasma liner 310A and a lower plasma liner 310B positioned under the upper plasma liner 310A. The upper plasma liner 310A includes one or more openings 312A formed therethrough, and the lower plasma liner 310B correspondingly includes one or more openings 312B formed therethrough. The plasma liners 310A, 310B are positioned about the substrate support 306 such that the openings 312A of the upper plasma liner 310A are rotationally offset from the openings 312B of the lower plasma liner 310B, such as with respect to an axis of the substrate support 306. For example, as shown specifically in
In some embodiments, the openings 312A of the upper plasma liner 310A may be the same number as the openings 312B of the lower plasma liner 310B. In some embodiments, the openings 312A of the upper plasma liner 310A may be the same size and/or shape as the openings 312B of the lower plasma liner 310B. In some embodiments, the upper plasma liner 310A may be identical to the lower plasma liner 310B. In some embodiments, the upper plasma liner 310A may also be rotationally offset from the lower plasma liner 310B by approximately one degree, approximately five degrees, or more. For example, in the embodiments shown in
In some embodiments, the upper plasma liner 310A and/or the lower plasma liner 310B may be integrally formed with the substrate support 306, or may be formed separately from and one or more of the plasma liners 310A, 310B may be coupled to the substrate support 306. In some embodiments in which one or both of the upper plasma liner 310A and the lower plasma liner 310B are formed separate from the substrate support 306, one or more spacers 314 may be positioned between the upper plasma liner 310A and the lower plasma liner 310B. The spacers 314 may facilitate spacing and positioning between the upper plasma liner 310A and the lower plasma liner 310B. In some embodiments, the spacers 314 may incorporated directly into the upper plasma liner 310A and/or the lower plasma liner 3106 and may include a recess for an RF gasket (RF conductive material) and the like. In some embodiments, the spacers 314 may be located near an inner periphery of the upper plasma liner 310A and the lower plasma liner 310B and/or may be located near an outer periphery of the upper plasma liner 310A and the lower plasma liner 3106.
In some embodiments, the outer liner wall 808 of the upper plasma liner 802 may only make ohmic contact with other process chamber assemblies (not shown) at an upper portion 816 of the outer liner wall 808. In some embodiments, the upper plasma liner 802 may have a recess 826 formed in the upper portion 816 of the outer liner wall 808 that holds a third RF gasket 828. The third RF gasket mates with another assembly (not shown, see
A second distance 908 from an upper surface 918 of the upper plasma liner 904 to an upper surface 912 of a substrate support 910 may be adjusted to compensate for edge uniformity effects of the plasma generated above the upper plasma liner 904. The second distance 908 may be varied based upon RF frequency and/or RF power levels used to generate the plasma. In some embodiments, the second distance is approximately two inches. In some embodiments, the upper plasma liner 904 and the lower plasma liner 902 may be adjusted to facilitate in differences in operating parameters of a given process chamber. In some embodiments, the upper plasma liner 904 and the lower plasma liner 902 may be manually and/or automatically adjusted up or down (arrow 924) by an actuator 914 that is connected via an actuator assembly 916 to the upper plasma liner 904 and/or the lower plasma liner 902. The second distance 908 may then be adjusted for different processes in the process chamber. The controller 295 of
Embodiments in accordance with the present principles may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more computer readable media, which may be read and executed by one or more processors. A computer readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform or a “virtual machine” running on one or more computing platforms). For example, a computer readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, the computer readable media may include a non-transitory computer readable medium.
While the foregoing is directed to embodiments of the present principles, other and further embodiments of the principles may be devised without departing from the basic scope thereof.
Claims
1. An apparatus for confining plasma in a process chamber, comprising:
- a first liner with a first set of openings for fluid flow, the first liner configured to surround a substrate support of the process chamber when installed in the process chamber; and
- a second liner with a second set of openings for fluid flow, the second liner configured to surround the substrate support of the process chamber under the first liner when installed in the process chamber,
- wherein the first set of openings and the second set of openings are configured to be offset from each other when installed in the process chamber to prevent a line-of-sight through the first liner and the second liner from a top down viewpoint, and
- wherein the first liner and the second liner are configured to be spaced apart vertically when installed in the process chamber to allow high fluid conductance through the first set of openings and the second set of openings.
2. The apparatus of claim 1, wherein the first liner or the second liner is electrically conductive.
3. The apparatus of claim 2, wherein the first liner or the second liner is formed form an aluminum based material.
4. The apparatus of claim 3, wherein the first liner or the second liner is coated with a yttrium-based material.
5. The apparatus of claim 2, wherein the first liner or the second liner is electrically grounded.
6. The apparatus of claim 5, wherein the first liner or the second liner is configured to form a symmetrical radio frequency (RF) ground return path when installed in the process chamber.
7. The apparatus of claim 1, wherein the first liner and the second liner are configured to be spaced apart vertically from approximately 0.25 inches to approximately 0.375 inches when installed in the process chamber.
8. The apparatus of claim 1, wherein a vertical distance between the first liner and the second liner is configured to be adjustable when installed in the process chamber.
9. The apparatus of claim 1, wherein a distance from a top surface of the first liner and a top surface of the substrate support is configured to be adjustable when the first liner is installed in the process chamber.
10. The apparatus of claim 1, wherein the first set of openings or the second set of openings is configured in size to prevent parasitic plasma formation when the first liner or second liner is installed in the process chamber.
11. The apparatus of claim 1, wherein the first liner has a first key for maintaining a first orientation when installed in the process chamber and the second liner has a second key for maintaining a second orientation when installed in the process chamber, wherein the first orientation of the first liner and the second orientation of the second liner yields an offset that provides no line-of-sight through the first liner and the second liner from a top down viewpoint when installed in the process chamber.
12. The apparatus of claim 1, wherein the first liner and the second liner are ohmically connected via at least one conductive gasket.
13. The apparatus of claim 1, wherein the first liner or second liner is circular in shape with an inner cutout, wherein the first set of openings or the second set of openings, respectively, extend radially outward from an inner edge near the inner cutout towards an outer edge of the first liner or the second liner, respectively.
14. An apparatus for confining plasma in a process chamber, comprising:
- a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner under the first conductive liner when installed in the process chamber.
15. The apparatus of claim 14, wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber.
16. The apparatus of claim 14, wherein the first conductive liner has a vertical inner periphery wall that is configured to be grounded to the substrate support when installed in the process chamber.
17. The apparatus of claim 14, wherein the first conductive liner has a vertical outer periphery wall with an uppermost portion that is configured to make ohmic contact with a ground of the process chamber.
18. An apparatus for confining plasma in a process chamber, comprising:
- a first conductive liner with a first set of openings for fluid flow that is configured to surround a substrate support when installed in the process chamber, wherein the first set of openings are configured to be oriented with an offset relative to a second set of openings of a second conductive liner above the first conductive liner when installed in the process chamber.
19. The apparatus of claim 18, wherein the first conductive liner is configured to be spaced apart from the second conductive liner when installed in the process chamber.
20. The apparatus of claim 18, wherein the first conductive liner has a top inner periphery edge portion that is configured to make ohmic contact with a bottom inner periphery edge portion of the second conductive liner and a top outer periphery edge portion that is configured to make ohmic contact with a bottom outer periphery edge portion of the second conductive liner when installed in the process chamber.
Type: Application
Filed: Jun 21, 2019
Publication Date: Feb 27, 2020
Inventors: HAMID NOORBAKHSH (FREMONT, CA), KARTIK RAMASWAMY (SAN JOSE, CA), SERGIO F. SHOJI (SAN JOSE, CA), KENNY DOAN (SAN JOSE, CA), JOSEPH PERRY (SAN JOSE, CA)
Application Number: 16/448,536