Apparatus for forming thin layers of materials on micro-device workpieces
A method of forming a layer on a micro-device workpiece includes dispensing a first pulse of a first precursor at a first region of the workpiece to flow toward a second region of the workpiece. The second region of the workpiece is located radially outward relative to the first region of the workpiece. The embodiment of this method further includes dispensing a first pulse of a purge gas at the first region of the workpiece to flow toward the second region of the workpiece after terminating the first pulse of the first precursor. Additionally, this embodiment also includes dispensing a second pulse of a first precursor at the second region of the workpiece to flow radially outward concurrently with dispensing the first pulse of a purge gas in the first region of the workpiece. The first pulse of the purge gas is terminated at the first region of the workpiece, and the second pulse of the first precursor is terminated at the second region. At this stage, the method further includes dispensing a first pulse of a second precursor at the first region of the workpiece to flow radially outward toward the second region, and dispensing a second pulse of the purge gas at the second region of the workpiece to flow radially outward concurrently with the first pulse of the second precursor in the first region. A single cycle of the process can further include dispensing a third pulse of the purge gas onto the first region of the workpiece to flow radially outward after terminating the first pulse of the second precursor, and concurrently dispensing a second pulse of the second precursor in the second region to flow radially outward.
The present invention is related to the field of thin film deposition in the manufacturing of microelectronic devices, micromechanical devices and other types of micro-devices.
BACKGROUNDThin film deposition techniques are widely used in the manufacturing of microelectronic devices to form a coating on a workpiece that closely conforms to the surface typography. The size of the individual components in the devices is constantly decreasing, and the number of layers in the devices is increasing. As a result, the density of components and the aspect ratios of depressions (e.g., the ratio of the depth to the size of the opening) is constantly increasing. The size of the workpieces is also increasing to provide more real estate for forming more dies (i.e., chips) on a single workpiece. Many fabricators, for example, are transitioning from 200 mm to 300 mm workpieces, and even larger workpieces will likely be used in the future. Thin film deposition techniques accordingly strive to produce highly uniform conformal layers that cover the sidewalls, bottoms and corners in deep depressions that have very small openings.
One widely used thin film deposition technique is Chemical Vapor Deposition (“CVD”). In a CVD system, one or more precursors that are capable of reacting to form a solid thin film are mixed in a gas or vapor state, and then the precursor mixture is presented to the surface of the workpiece. The surface of the workpiece catalyzes the reaction between the precursors to form a thin solid film that closely follows the contour of the surface typography on the workpiece. The most common way to catalyze the reaction at the surface of the workpiece is to heat the workpiece to a temperature that causes the reaction.
Although CVD techniques are useful in many applications, they also have several drawbacks. For example, if the precursors are not highly reactive, then a high workpiece temperature is needed to achieve a reasonable deposition rate. Such high temperatures are typically not desirable because heating the workpiece can be detrimental to the structures and other materials that are already formed on the workpiece. Implanted or doped materials, for example, migrate in the silicon substrate when a workpiece is heated. On the other hand, if more reactive precursors are used so that the reaction temperature of the workpiece can be lower, then reactions may occur prematurely in the gas phase before reaching the substrate. This is not desirable because the film quality and uniformity may suffer, and also because it limits the type of precursors that can be used. Thus, CVD techniques may not be appropriate for many thin film applications.
Atomic Layer Deposition (“ALD”) is another thin film deposition technique that addresses several of the drawbacks associated with CVD techniques.
One drawback of ALD processing is that the film thickness may be different at the center of the workpiece than at the periphery. To overcome this problem, the center of some distributor plates do not have any holes 72. In practice, however, this may cause the film at the center of the workpiece to be thinner than the film at the periphery. Moreover, the center portion of such plates may become coated with the solid material because it is difficult to purge all of the precursors from this portion of the gas distributor 60 during normal purge cycles.
Another drawback of ALD processing is that it has a low throughput compared to CVD techniques. For example, ALD processing typically takes about eight to eleven seconds to perform each Ax-purge-By-purge cycle. This results in a total process time of approximately eight to eleven minutes to form a thin layer of only 60 Å. In contrast to ALD processing, CVD techniques only require about one minute to form a 60 Å thick layer. The low throughput of existing ALD techniques limits the utility of this technology in its current state because ALD may be a bottleneck in the fab. Thus, it would be useful to increase the throughput of ALD techniques so that they can be used in a wider range of applications.
SUMMARYThe present invention is directed toward reactors for depositing materials onto a micro-device workpiece, systems that include such reactors, and methods for depositing materials onto micro-device workpieces. In one embodiment, a method of forming a layer on a micro-device workpiece includes dispensing a first pulse of a first precursor at a first region of the workpiece to flow toward a second region of the workpiece. The second region of the workpiece is located radially outward relative to the first region of the workpiece. This embodiment further includes dispensing a first pulse of a purge gas at the first region of the workpiece to flow toward the second region of the workpiece after terminating the first pulse of the first precursor, and concurrently dispensing a second pulse of a first precursor at the second region of the workpiece to flow radially outward while dispensing the first pulse of the purge gas in the first region of the workpiece. The first pulse of the purge gas and the second pulse of the first precursor are then terminated. This embodiment further includes dispensing a first pulse of a second precursor at the first region of the workpiece to flow radially outward toward the second region, and concurrently dispensing a second pulse of the purge gas at the second region of the workpiece to flow radially outward while dispensing the first pulse of the second precursor in the first region. This embodiment continues by dispensing a third pulse of the purge gas onto the first region of the workpiece to flow radially outward after terminating the first pulse of the second precursor, and concurrently dispensing a second pulse of the second precursor in the second region to flow radially outward while dispensing the third pulse of the purge gas.
This embodiment accordingly provides a continuous pulse train in which discrete areas of the workpiece are exposed to one of the first or second precursors while adjacent areas are exposed to the purge gas. A continuous pulse train can accordingly be presented to the surface of the wafer without having to completely purge the first and second precursors from the entire surface area of the workpiece during each purge cycle. This is expected to greatly reduce the processing time for forming a layer of material on the workpiece.
Another aspect of the invention is directed toward a reactor for forming a layer of material on a micro-device workpiece. In one embodiment, a reactor includes a reaction chamber having an inlet and an outlet, and a workpiece support in the reaction chamber between the inlet and the outlet. The workpiece support can have a first zone and a second zone. The second zone is located radially outward relative to the first zone. The reactor can further include a gas distributor in the reaction chamber between the inlet and the workpiece support. The gas distributor can comprise a first dispensing section and a second dispensing section. The second dispensing section is located radially outward relative to the first dispensing section. The first dispensing section is configured to dispense separate pulses of a first precursor, a purge gas, or a second precursor over the first zone of the workpiece support. The second dispensing section is configured to dispense separate pulses of the first precursor, the purge gas, or the second precursor over the second zone of the workpiece support independently from the type of gas dispensed from the first dispensing section. As such, the first dispensing section can dispense one type of gas over the first zone while the second dispensing section concurrently dispenses a different type of gas over the second zone.
The reactor can be part of a system that further includes a gas supply assembly and a controller coupled to the gas supply assembly. The gas supply assembly can include a first gas source for a first precursor, a second gas source for a second precursor, and a third gas source for a purge gas. The controller can contain computer readable instructions that cause the first precursor, second precursor and purge gas to flow through the first and second dispensing sections of the gas distributor in a manner that effectuates embodiments of methods in accordance with the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The following disclosure describes several embodiments of reactors for depositing a material onto a micro-device workpiece, systems including such reactors, and methods for depositing materials onto micro-device workpieces. Many specific details of the invention are described below with reference to depositing materials onto micro-device workpieces. The term “micro-device workpiece” is used throughout to include substrates upon which and/or in which microelectronic devices, micromechanical devices, data storage elements, read/write components, and other features are fabricated. For example, micro-device workpieces can be semiconductor wafers such as silicon or galium arsenide wafers, glass substrates, insulative substrates, and many other types of materials. The term “gas” is used throughout to include any form of matter that has no fixed shape and will conform in volume to the space available, which specifically includes vapors (i.e., a gas having a temperature less than the critical temperature so that it may be liquified or solidified by compression at a constant temperature). Additionally, several aspects of the invention are described with respect to Atomic Layer Deposition (“ALD”), but certain aspects may be applicable to other types of deposition processes. Several embodiments in accordance with the invention are set forth in
A. Deposition Systems
The gas supply 130 includes a plurality of gas sources 132 (identified individually as 132a-c), a valve assembly 133 having a plurality of valves, and a plurality of gas lines 136 and 137. The gas sources 132 can include a first gas source 132a for providing a first precursor A, a second gas source 132b for providing a second precursor B, and a third gas source 132c for providing a purge gas P. The first and second precursors A and B are the gas or vapor phase constituents that react to form the thin, solid layer on the workpiece W. The purge gas P can be a suitable type of gas that is compatible with the reaction chamber 120 and the workpiece W. The gas supply 130 can include more gas sources 132 for applications that require additional precursors or purge gases in other embodiments. As explained in more detail below, the valve assembly is operated by a controller 142 that generates signals for pulsing the individual gases through the reaction chamber 120.
The reaction chamber 110 in the embodiment illustrated in
The gas distributor 160 is positioned at the inlet 122 of the reaction chamber 120. The gas distributor 160 includes a first dispensing section 161a and a second dispensing section 161b. The first dispensing section 161a is generally juxtaposed to the first zone Z1, and the first dispensing section 161a is coupled to the valve assembly 133 to dispense at least one of the first precursor A, the second precursor B, or the purge gas P over the first zone Z1. The first dispensing section 161a can have a circular shape to create a gas flow F1 that flows radially outward from the center region C of the workpiece W. The second dispensing section 161b can have an annular shape that concentrically surrounds the first dispensing section 161a to be juxtaposed to the second zone Z2. The second dispensing section 161b is coupled to the valve assembly 133 to dispense a different one of the first precursor A, the second precursor B, or the purge gas P over the second zone Z2 independently from the first dispensing section 161a. The second dispensing section 161b accordingly produces a second gas flow F2 that flows radially outward across the workpiece W. In operation, the first dispensing section 161a can dispense a pulse of one type of gas over the first zone Z1 while the second dispensing section 161b simultaneously dispenses a pulse of a different type of gas over the second zone Z2. The separate pulses of gases that form the gas flows F1 and F2 are coordinated to provide the desired combination of gases at separate regions on the surface of the workpiece. For example, pulse trains of different gases are dispensed through each of the first and second dispensing sections 161a-b concurrently to provide a continuous deposition process that does not completely purge the first and/or the second precursor from the entire surface of the workpiece until the end of the deposition process.
B. Methods for Forming Layers on Micro-Device Workpieces
The system 100 shown in
The particular embodiment of the method shown in
Another embodiment of the method for forming layers on micro-device workpieces shown in
The embodiment of method set forth in
C. Gas Distributors
In operation, a pulse of one type of gas flows through the first compartment 166 while a pulse of a different type of gas simultaneously flows through the second compartment 168 to provide the pulse trains described above with reference to
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. For example, although the foregoing embodiments illustrate circular reactors and gas distributors, several aspects of the invention are also useful in linear reactors. The methods, therefore, can include dispensing independent pulses of gases linearly over first and second regions of a workpiece. Several embodiments of the invention may also be used in other geometries according to the shape of the reactor and the gas distributor. Accordingly, the invention is not limited except as by the appended claims.
Claims
1-29. (canceled)
30. A reactor for forming a layer of material on a micro-device workpiece, comprising:
- a reaction chamber having an inlet and an outlet;
- a workpiece support in the reaction chamber between the inlet and the outlet, the workpiece support having a first zone and a second zone located radially outward relative to the first zone;
- a gas distributor in the reaction chamber between the inlet and the workpiece support, the gas distributor comprising a first dispensing section and a second dispensing section located radially outward relative to the first dispensing section, first dispensing section being configured to dispense at least one of a first precursor, a purge gas or a second precursor over the first zone, and the second dispensing section being configured to dispense a different one of the first precursor, the purge gas or the second precursor over the second zone independently from the first dispensing section.
31. The reactor of claim 30 wherein the gas distributor comprises:
- a gas box to receive flows of the first precursor, the purge gas and the second precursor;
- a distributor plate having a plurality of first passageways juxtaposed to the first zone of the support and a plurality of second passageways juxtaposed to the second zone of the support, wherein the distributor plate is proximate to the gas box; and
- an annular divider in the gas box aligned with a boundary between the first zone and the second zone, the divider forming a first compartment over the first passageways that defines the first dispensing section and a second compartment over the second passageways that defines the second dispensing section.
32. The reactor of claim 30 wherein the gas distributor comprises:
- a distributor plate having a plurality of first passageways juxtaposed to the first
- zone of the support and a plurality of second passageways juxtaposed to the second zone of the support, wherein the distributor plate is proximate to the gas box;
- a first set of purge gas lines coupled to a purge gas set of the first passageways;
- a second set of purge gas lines coupled to a purge gas set of the second passageways;
- a first set of first precursor lines coupled to a first precursor set of the first passageways;
- a second set of first precursor lines coupled to a first precursor set of the second passageway;
- a first set of second precursor lines coupled to a second precursor set of the first passage ways; and
- a second set of second precursor lines coupled to a second precursor set of the second passageways.
33. The reactor of claim 30 wherein the gas distributor further comprises a third dispensing section radially outward from the second dispensing section, the third dispensing section being configured to dispense one of the first precursor, the second precursor or the purge gas over a third zone of the workpiece support that is located radially outward from the second zone of the workpiece support.
34. The reactor of claim 30 wherein the first dispensing section has a circular shape over the first zone and the second dispensing section has an annular shape over the second zone.
35. The reactor of claim 30 wherein:
- the first dispensing section has a circular shape over the first zone;
- the second dispensing section has an annular shape over the second zone; and
- the gas dispenser has a third dispensing section having an annular shape radially outward from the second dispensing section.
36. A reactor for forming a layer of material on a micro-device workpiece, comprising:
- a reaction chamber having an inlet and an outlet;
- a gas distributor in the reaction chamber between the inlet and the outlet, the gas distributor having a plenum, a first divider that partitions the plenum into a center compartment and a first annular compartment radially outward from the center compartment, and a distributor plate having a plurality of first openings in the first compartment and a plurality of second openings in the second compartment.
37. A reactor for forming a layer of material on a micro-device workpiece, comprising:
- a reaction chamber having an inlet and an outlet;
- a workpiece support in the reaction chamber between the inlet and the outlet, the workpiece support having a first zone and a second zone located radially outward relative to the first zone;
- a gas distributor in the reaction chamber between the inlet and the workpiece support, the gas distributor having a first plurality of conduits in a first section juxtaposed to the first zone and a second plurality of conduits in a second section juxtaposed to the second zone, wherein the first plurality of conduits are coupled to a gas supply to selective dispense at least one of a first precursor, a purge gas or a second precursor over the first zone, and wherein the second plurality of conduits are coupled to the gas supply to concurrently dispense a different one of the first precursor, the purge gas or the second precursor over the second zone.
38. A system for forming a layer of material on a surface of a micro-device workpiece, comprising:
- a gas supply assembly having a first gas source for a first precursor, a second gas source for a second precursor, and a third gas source for a purge gas;
- a reaction chamber coupled to the gas supply;
- a workpiece support in the reaction chamber, the support member having a first zone and a second zone located radially outward relative to the first zone;
- a gas distributor in the reaction chamber, the gas distributor being coupled to the gas supply assembly, and the gas distributor having a first dispensing section juxtaposed to the first zone of the support and a second dispensing section juxtaposed to the second zone of support; and
- a controller coupled to the gas supply assembly, wherein the controller contains computer readable instructions that cause the gas supply to dispense a first pulse of a first precursor through the first dispensing section; dispense a first pulse of a purge gas through the first dispensing section after terminating the first pulse of the first precursor; and dispense a second pulse of the first precursor through the second dispensing section concurrently while dispensing the first pulse of the purge gas.
39. A system for forming a layer of material on a surface of a microelectronic workpiece, comprising:
- a gas supply assembly having a first gas source for a first precursor, a second gas source for a second precursor, and a third gas source for a purge gas;
- a reaction chamber coupled to the gas supply; a workpiece support in the reaction chamber;
- a gas distributor in the reaction chamber, the gas distributor being coupled to the gas supply assembly, and the gas distributor having a first dispensing section juxtaposed to a central zone of the support and a second dispensing section juxtaposed to an outer annular zone; and
- a controller coupled to the gas supply assembly, wherein the controller contains computer readable instructions that cause the gas supply to dispense a first pulse of a first precursor from the first dispensing section to flow radially outward over the central zone; dispense a first pulse of a purge gas from the first dispensing section to flow radially outward over the central zone after terminating the first pulse of the first precursor; and dispense a second pulse of the first precursor from the second section to flow radially outward over the outer annular zone while concurrently dispensing the first pulse of the purge gas.
Type: Application
Filed: Dec 29, 2004
Publication Date: Jul 7, 2005
Inventors: Garo Derderian (Boise, ID), Gurtej Sandhu (Boise, ID)
Application Number: 11/027,825