Reactors having gas distributors and methods for depositing materials onto micro-device workpieces
Reactors having gas distributors for depositing materials onto micro-device workpieces, systems that include such reactors, and methods for depositing materials onto micro-device workpieces are disclosed herein. In one embodiment, a reactor for depositing material on a micro-device workpiece includes a reaction chamber and a gas distributor in the reaction chamber. The gas distributor includes a first gas conduit having a first injector and a second gas conduit having a second injector. The first injector projects a first gas flow along a first vector and the second injector projects a second gas flow along a second vector that intersects the first vector in an external mixing zone facing the workpiece. In another embodiment, the mixing zone is an external mixing recess on a surface of the gas distributor that faces the workpiece.
The present invention is related to reactors having gas distributors and methods for depositing materials in thin film deposition processes used in the manufacturing of micro-devices.
BACKGROUNDThin film deposition techniques are widely used in the manufacturing of micro-devices to form a coating on a workpiece that closely conforms to the surface topography. 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) are increasing. The size of 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 at the workpiece surface. 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 not typically 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, can migrate in the silicon substrate at higher temperatures. On the other hand, if more reactive precursors are used so that the workpiece temperature 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 types of precursors that can be used.
One conventional system to prevent premature reactions injects the precursors into the reaction chamber through separate ports. For example, each port of a shower head can be coupled to a dedicated gas line for a single gas. Systems that present the precursors through dedicated ports proximate to the surface of the workpiece, however, may not sufficiently mix the precursors. Accordingly, the precursors may not react properly to form a thin solid film at the workpiece surface. Furthermore, conventional systems also have a jetting effect that produces a higher deposition rate directly below the ports. Thus, conventional CVD systems may not be appropriate for many thin film applications.
Atomic Layer Deposition (ALD) is another thin film deposition technique.
One drawback of ALD processing is that it has a relatively low throughput compared to CVD techniques. For example, ALD processing typically takes several seconds to perform each Ax-purge-By-purge cycle. This results in a total process time of several minutes to form a single thin layer of only 60-100 Å. In contrast to ALD processing, CVD techniques require much less time to form similar layers. The low throughput of existing ALD techniques limits the utility of the technology in its current state because ALD may be a bottleneck in the overall manufacturing process. Thus, it would be useful to increase the throughput of ALD techniques so that they can be used in a wider range of applications. Another drawback of ALD processing is that it is difficult to control the uniformity of the deposited films because the holes 72 in the distributor plate 70 also cause a jetting affect that results in a higher deposition rate in-line with the holes 72. Therefore, a need exists in semiconductor fabrication to increase the deposition uniformity in both CVD and ALD processes.
SUMMARYThe present invention is directed toward reactors having gas distributors for depositing materials onto micro-device workpieces, systems that include such reactors, and methods for depositing materials onto micro-device workpieces. In one embodiment, a reactor for depositing material onto a micro-device workpiece includes a reaction chamber and a gas distributor in the reaction chamber. The gas distributor includes a first gas conduit having a first injector and a second gas conduit having a second injector. In one aspect of this embodiment, the first injector projects a first gas flow along a first vector and the second injector projects a second gas flow along a second vector that intersects the first vector in a mixing zone. In another aspect of this embodiment, the gas distributor can also include a mixing recess that defines the mixing zone. The mixing recess can have a variety of configurations, such as a conical, cubical, cylindrical, frusto-conical, pyramidical or other configurations. The first injector can project the first gas flow into the mixing recess along the first vector, and the second injector can project the second gas flow into the mixing recess along the second vector. In a further aspect of this embodiment, the first and second injectors are positioned within the mixing recess. The mixing zone can be positioned partially within the mixing recess.
In another embodiment, a reactor for depositing material onto a micro-device workpiece includes a reaction chamber, a workpiece support in the reaction chamber, and a gas distributor with a mixing recess in the reaction chamber. The mixing recess is exposed to the workpiece support. The gas distributor includes a first gas conduit having a first injector and a second gas conduit having a second injector. The first injector projects a first gas flow into the mixing recess along a first vector and the second injector projects a second gas flow into the mixing recess along a second vector.
These reactors can be used to perform several methods for depositing materials onto micro-device workpieces. In one embodiment, a method includes flowing the first gas through the first injector of the gas distributor along a first vector, and flowing the second gas through the second injector of the gas distributor along a second vector. The second vector intersects the first vector in the mixing zone over the micro-device workpiece. In another embodiment, a method includes flowing the first gas through the first injector of the gas distributor into the mixing recess, and flowing the second gas through the second injector of the gas distributor into the mixing recess over the micro-device workpiece. In a further embodiment, a method includes dispensing a first pulse of the first gas from a first outlet into a recess in the gas distributor, and dispensing a second pulse of the second gas from a second outlet into the recess in the gas distributor after terminating the first pulse of the first gas.
BRIEF DESCRIPTION OF THE DRAWINGS
The following disclosure describes several embodiments of reactors having gas distributors for depositing material onto micro-device workpieces, 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 gallium 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 liquefied or solidified by compression at a constant temperature). 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. The valve assembly 133 is operated by a controller 142 that generates signals for pulsing the individual gases through the reaction chamber 120.
The reactor 110 in the embodiment illustrated in
B. Gas Distributors
In the embodiment illustrated in
Each of the first injectors 270 is oriented to project a first gas flow into the mixing recesses 280 along a first vector V1 at an angle σ with respect to the workpiece W. Each of the second injectors 272 is oriented to project a second gas flow into the mixing recesses 280 along a second vector V2 at an angle α with respect to the workpiece W. The second vector V2 forms an angle β with respect to the first vector V1. In the illustrated embodiment, the second vector V2 is transverse (i.e., non-parallel) to the first vector V1. In other embodiments, such as the embodiment described below with reference to
C. Methods for Depositing Material on Micro-Device Workpieces
Referring to
In a further aspect of this embodiment, the gas distributor 160 can be used in both continuous flow and pulsed CVD applications. In a pulsed CVD application, a pulse of both the first precursor A and the second precursor B can be dispensed substantially simultaneously. After a pulse of the first and second precursors A and B, the third injector 274 can dispense a pulse of purge gas P along the third vector V3 into the mixing recesses 280 to purge excess molecules of the first and second precursors A and B. After purging, the process can be repeated with pulses of the first and second precursors A and B. In another pulsed CVD application, the purge gas P flows continuously and pulses of the first and second precursors are injected into the continuous flow of the purge gas. The purge gas P, for example, can flow continuously along the third vector V3.
In another aspect of this embodiment, the gas distributor 160 can be used in ALD processing. For example, the first injectors 270 can project the first precursor A containing molecules Ax into the mixing recesses 280. In the illustrative embodiment, the orientation of the first injectors 270 in the mixing recesses 280 causes the first precursor molecules Ax to mix sufficiently to form a uniform layer across the surface of the workpiece W. Next, the third injector 274 can project the purge gas P to purge excess first precursor molecules Ax from the mixing recesses 280. This process can form a monolayer of Ax molecules on the surface of the workpiece W because the Ax molecules at the surface are held in .place during the purge cycle by physical adsorption forces at moderate temperatures or chemisorption forces at higher temperatures. The second injectors 272 can then project the second precursor B containing By molecules into the mixing recesses 280. The By molecules also mix and form a uniform layer across the surface of the workpiece W. The Ax molecules react with the By molecules to form an extremely thin solid layer of material on the workpiece W. The mixing recesses 280 are then purged again and the process is repeated.
In a further aspect of this embodiment, the first and second injectors 270 and 272 can sequentially project the first and second precursors A and B to induce a vortex within the mixing recesses 280 in order to further increase the mixing. For example, referring to
One advantage of this embodiment with respect to the CVD process is that by using dedicated injectors 270, 272 and 274 and gas conduits 232 for each gas, the precursors A and B are kept separate, and accordingly, do not react prematurely. Furthermore, because the precursors A and B do not react prematurely, precursors that are highly reactive can be used, avoiding the need to heat the workpiece W to detrimentally high temperatures. Another advantage of this embodiment with respect to the ALD and CVD processes is that the enhanced mixing of the gases reduces the jetting effect and creates a uniform deposition across the surface of the workpiece W. A further advantage of this embodiment is that the position of the purge gas injectors 274 at the base of the mixing recesses 280 prevents the other gases from being trapped in the mixing recesses 280. Another advantage of this embodiment is that the flow to each mixing recess can be independently controlled to compensate for nonuniformities on the workpiece W. For example, if the surface at the center of the workpiece W is too thick, the flow of gases from the injectors over the center of the workpiece W can be reduced. Still another advantage is that the chemical composition of the deposited film can be controlled precisely because the mixing at the outlets provides more precise reactions at the workpiece surface.
D. Other Gas Distributors
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. Accordingly, the invention is not limited except as by the appended claims.
Claims
1-54. (canceled)
55. A method for depositing material onto a micro-device workpiece in a reaction chamber, comprising:
- passing a first gas flow through a first injector of a gas distributor along a first vector; and
- passing a second gas flow through a second injector of the gas distributor along a second vector that intersects with the first vector in a mixing zone exposed to and over the micro-device workpiece.
56. The method of claim 55, further comprising mixing the first gas flow and the second gas flow in the mixing zone.
57. The method of claim 55 wherein passing a first gas flow and passing a second gas flow occur at least partially simultaneously.
58. The method of claim 55 wherein passing a second gas flow occurs after terminating passing the first gas flow.
59. The method of claim 55, further comprising passing a third gas flow through a third injector of the gas distributor.
60. The method of claim 55 wherein the first and second gas flows comprise the same gas.
61. The method of claim 55 wherein the first gas flow comprises a first precursor and the second gas flow comprises a second precursor, and wherein passing the first gas flow and passing the second gas flow occur at least substantially simultaneously.
62. The method of claim 55, further comprising:
- passing a third gas flow through a third injector of the gas distributor; and
- wherein passing the first gas flow comprises passing a first precursor through the first injector and then terminating the first gas flow, wherein passing the third gas flow comprises passing a purge gas through the third injector after terminating the first gas flow and then terminating the third gas flow, and wherein passing the second gas flow comprises passing a second precursor through the second injector after terminating the third gas flow.
63. The method of claim 55, further comprising:
- passing a third gas flow through a third injector of the gas distributor; and
- wherein passing the first gas flow comprises passing a first precursor, wherein passing the second gas flow comprises passing a second precursor at least substantially simultaneously with passing the first gas flow, and wherein passing the third gas flow comprises passing a purge gas after terminating the first and second gas flows.
64. The method of claim 55 wherein passing the first gas flow and passing the second gas flow comprise creating a vortex in the mixing zone of the first and second gas flows.
65. A method for depositing material onto a micro-device workpiece in a reaction chamber, comprising:
- flowing a first gas flow through a first injector of a gas distributor into an external mixing recess in the gas distributor; and
- flowing a second gas flow through a second injector of the gas distributor into the external mixing recess over the micro-device workpiece.
66. The method of claim 65, further comprising mixing the first gas flow and the second gas flow in the mixing zone.
67. The method of claim 65 wherein flowing the first gas flow and flowing the second gas flow occur at least partially simultaneously.
68. The method of claim 65 wherein flowing the second gas flow occurs after terminating flowing the first gas flow.
69. The method of claim 65, further comprising flowing a third gas flow through a third injector of the gas distributor.
70. The method of claim 65 wherein flowing the first gas flow comprises flowing the first gas flow along a first vector, and flowing the second gas flow comprises flowing the second gas flow along a second vector transverse to the first vector.
71. The method of claim 65 wherein flowing the first gas flow comprises flowing the first gas flow along a first vector, and flowing the second gas flow comprises flowing the second gas flow along a second vector generally parallel to the first vector.
72. The method of claim 65, further comprising creating a vortex in the mixing recess with the first and second gas flows.
73. A method for depositing material onto a micro-device workpiece in a reaction chamber having a gas distributor, comprising:
- dispensing a pulse of a first gas from a first outlet in the gas distributor into an external recess in the gas distributor; and
- dispensing a pulse of a second gas from a second outlet in the gas distributor into the external recess in the gas distributor after terminating the pulse of the first gas.
74. The method of claim 73, further comprising mixing the first gas and the second gas on a surface of the workpiece.
75. The method of claim 73, further comprising dispensing a pulse of a purge gas through a third outlet into the recess of the gas distributor between the pulse of the first gas and the pulse of the second gas.
76. The method of claim 73 wherein dispensing the pulse of the first gas comprises dispensing the first gas along a first vector, and dispensing the pulse of the second gas comprises dispensing the second gas along a second vector transverse to the first vector.
77. The method of claim 73 wherein the dispensing procedures are repeated in serial order creating a vortex within the external recess in the gas distributor.
Type: Application
Filed: Dec 13, 2004
Publication Date: Jun 2, 2005
Inventors: Cem Basceri (Boise, ID), Gurtej Sandhu (Boise, ID)
Application Number: 11/010,534