Patent Application
20050121145
The present invention relates generally to systems and methods for heat-treating objects, such as substrates. More specifically, the present invention relates to an apparatus and method for heat treating, annealing, and depositing layers of material on or removing layers of material from a semiconductor wafer or substrate.
Thermal processing apparatuses are commonly used in the manufacture of integrated circuits (ICs) or semiconductor devices from semiconductor substrates or wafers. Thermal processing of semiconductor wafers include, for example, heat treating, annealing, diffusion or driving of dopant material, deposition or growth of layers of material, and etching or removal of material from the substrate. These processes often call for the wafer to be heated to a temperature as high as 1300° C. and as low as 300° C. before and during the process, and that one or more fluids, such as a process gas or reactant, be delivered to the wafer. Moreover, these processes typically require that the wafer be maintained at a uniform temperature throughout the process, despite variations in the temperature of the process gas or the rate at which it is introduced into the process chamber.
A conventional thermal processing apparatus typically consists of a voluminous process chamber positioned in or surrounded by a furnace. Substrates to be thermally processed are sealed in the process chamber, which is then heated by the furnace to a desired temperature at which the processing is performed. For many processes, such as Chemical Vapor Deposition (CVD), the sealed process chamber is first evacuated, and once the process chamber has reached the desired temperature a reactive or process gases are introduced to form or deposit reactant species on the substrates.
In the past, thermal processing apparatus typically and in particular vertical thermal processing apparatuses, required guard heaters disposed adjacent to sidewalls of the process chamber above and below the process zone in which product wafers were processed. This arrangement is undesirable since it entails a larger chamber volume that must be pumped down, filled with process gas or vapor, and backfilled or purged, resulting in increased processing time. Moreover, this configuration takes up a tremendous amount of space and power due to a poor view factor of the wafers from the heaters.
Other problems with conventional thermal processing apparatuses include the considerable time required both before processing to ramp up the temperature of the process chamber and the wafer to be treated, and the time required after processing to ramp down the temperature. Furthermore, additional time is often required to ensure the temperature of the process chamber has stabilized uniformly at the desired temperature before processing can begin. While the actual time required for processing of the wafers may be half hour or less, pre- and post-processing times typically take 1 to 3 hours or longer. Thus, the time required to quickly ramp up and/or down the temperature of the process chamber to a uniform temperature significantly limits the throughput of the conventional thermal processing apparatus.
A fundamental reason for the relatively long ramp up and ramp down times is the thermal mass of the process chamber and/or furnace in conventional thermal processing apparatuses, which must be heated or cooled prior to effectively heating or cooling the wafer.
A common approach to minimizing or offsetting this limitation on throughput of conventional thermal processing apparatus has been to increase the number of wafers capable of being processed in a single cycle or run. Simultaneous processing of a large number of wafers helps to maximize the effective throughput of the apparatus by reducing the effective processing time on a per wafer basis. However, this approach also increases the magnitude of the risk should something go wrong during processing. That is a larger number of wafers could be destroyed or damaged by a single failure, for example, if there was an equipment or process failure during a single processing cycle. This is particularly a concern with larger wafer sizes and more complex integrated circuits where a single wafer could be valued at from $1,000 to $10,000 depending on the stage of processing.
Another problem with this solution is that increasing the size of the process chamber to accommodate a larger number of wafers increases the thermal mass effects of the process chamber, thereby reducing the rate at which the wafer can be heated or cooled. Moreover, larger process chambers processing larger batches of wafers leads to or compounds a first-in-last-out syndrome in which the first wafers loaded into the chamber are also the last wafers removed, resulting in these wafers being exposed to elevated temperatures for longer periods and reducing uniformity across the batch of wafers.
Another problem with the above approach is that systems and apparatuses used for many of the processes before and after thermal processing are not amenable to simultaneous processing of large numbers of wafers. Thus, thermal processing of large batches or large numbers wafers, while increasing the throughput of the thermal processing apparatus, can do little to improve the overall throughput of the semiconductor fabrication facility and may actually reduce it by requiring wafers to accumulate ahead of the thermal processing apparatus or causing wafers to bottleneck at other systems and apparatuses downstream therefrom.
An alternative to the conventional thermal processing apparatus described above, are rapid thermal processing (RTP) systems that have been developed for rapidly thermal processing of wafers. Conventional RTP systems generally use high intensity lamps to selectively heat a single wafer or small number of wafers within a small, transparent, usually quartz, process chamber. RTP systems minimize or eliminate the thermal mass effects of the process chamber, and since the lamps have very low thermal mass, the wafer can be heated and cooled rapidly by instantly turning the lamps on or off.
Unfortunately, conventional RTP systems have significant shortcomings including the placement of the lamps, which in the past were arranged in zones or banks each consisting of a number of lamps adjacent to sidewalls of the process chamber. This configuration is problematic because it takes up a tremendous amount of space and power in order to be effective due to their poor view factor, all of which are at a premium in the latest generation of semiconductor processing equipment.
Another problem with conventional RTP systems is their inability to provide uniform temperature distribution across multiple wafers within a single batch of wafers and even across a single wafer. There are several reasons for this non-uniform temperature distribution including (i) a poor view factor of one or more of the wafers by one or more of the lamps, and (ii) variation in output power from the lamps.
Moreover, failure or variation in the output of a single lamp can adversely affect the temperature distribution across the wafer. Because of this in most lamp-based systems, the wafer or wafers are rotated to ensure that the temperature non-uniformity due to the variation in lamp output is not transferred to the wafer during processing. However, the moving parts required to rotate the wafer, particularly the rotating feedthrough into the process chamber, adds to the cost and complexity of the system, and reduces the overall reliability thereof.
Yet another troublesome area for RTP systems is in maintaining uniform temperature distribution across the outer edges and the center of the wafer. Most conventional RTP systems have no adequate means to adjust for this type of temperature non-uniformity. As a result, transient temperature fluctuations occur across the surface of the wafer that can cause the formation of slip dislocations in the wafer at high temperatures, unless a black body susceptor is used that is larger in diameter than the wafer.
Conventional lamp-based RTP systems have other drawbacks. For example, there are no adequate means for providing uniform power distribution and temperature uniformity during transient periods, such as when the lamps are powered on and off, unless phase angle control is used which produces electrical noise. Repeatability of performance is also usually a drawback of lamp-based systems, since each lamp tends to perform differently as it ages. Replacing lamps can also be costly and time consuming, especially when one considers that a given lamp system may have upwards of 180 lamps. The power requirement may also be costly, since the lamps may have a peak power consumption of about 250 kWatts.
Accordingly, there is a need for an apparatus and method for quickly and uniformly heating a batch of one or more substrates to a desired temperature across the surface of each substrate in the batch of during thermal processing.
The present invention provides a solution to these and other problems, and offers other advantages over the prior art.
The present invention provides an apparatus and method for isothermally heating work pieces, such as semiconductor substrates or wafers, for performing processes such as annealing, diffusion or driving of dopant material, deposition or growth of layers of material, and etching or removal of material from the wafer.
A thermal processing apparatus is provided for processing substrates held in a carrier at high or elevated temperatures. The apparatus includes a process chamber having a top wall, a side wall and a bottom wall, and a heating source having a number of heating elements proximal to the top wall, the side wall and the bottom wall of the process chamber to provide an isothermal environment in a process zone in which the carrier is positioned to thermally process the substrates. According to one aspect, the dimensions of the process chamber are selected to enclose a volume substantially no larger than a volume necessary to accommodate the carrier, and the process zone extends substantially throughout the process chamber. Preferably, the process chamber has dimensions selected to enclose a volume substantially no larger than 125% of that necessary to accommodate the carrier. More preferably, the apparatus further includes a pumping system to evacuate the process chamber prior to processing pressure and a purge system to backfill the process chamber after processing is complete, and the dimensions of the process chamber are selected to provide both a rapid evacuation and a rapid backfilling of the process chamber.
According to another aspect of the invention, the bottom wall of the process chamber includes a movable pedestal having at least one heating element therein, and the movable pedestal is adapted to be lowered and raised to enable the carrier with the substrates to be inserted into and removed from the process chamber. In one embodiment, the apparatus further includes a removable thermal shield adapted to be inserted between heating element in the pedestal and the substrates held the carrier. The thermal shield is adapted to reflect thermal energy from the heating element in the pedestal back to the pedestal, and to shield the substrates on the carrier from thermal energy from the heating element in the pedestal. In one version of this embodiment, the apparatus further includes a shutter adapted to be moved into place above the carrier to isolate the process chamber when the pedestal is in a lowered position. Where the apparatus includes a pumping system to evacuate the process chamber, and the shutter can be adapted to seal with the process chamber, thereby enabling the pumping system to evacuate the process chamber when the pedestal is in the lowered position.
In yet another embodiment, the apparatus further includes a magnetically coupled repositioning system that repositions the carrier during thermal processing of the substrates. Preferably, the mechanical energy used to reposition the carrier is magnetically coupled through the pedestal to the carrier without use of a movable feedthrough into the process chamber, and substantially without moving the heating element in the pedestal. More preferably, the magnetically coupled repositioning system is a magnetically coupled rotation system that rotates the carrier within the process zone during thermal processing of the substrates.
According to yet another aspect of the invention, the apparatus further includes a liner separating the carrier from the top wall and the side wall of the process chamber, and a distributive or cross-flow injection system to direct flow of a fluid across surfaces of each of the substrates held in the carrier. The cross-flow injection system generally includes a cross-flow injector having a number of injection ports positioned relative to substrates held in the carrier, and through which the fluid is introduced on one side of the number of substrates. A number of exhaust ports in the liner positioned relative to the substrates held in the carrier cause the fluid to flow across the surfaces of the substrates. Fluids introduced by the cross-flow injection system can include process gas or vapor, and inert purge gases or vapor used for purging or backfilling the chamber or for cooling the substrates therein.
In another aspect, the apparatus of the present invention includes an injection system which provides for selectable injection of gases to the process chamber. In general, the injection system of the present invention comprises one or more elongated injection tubes having a plurality of injection ports or orifices distributed in the tubes for directing flow of reactant and other gases across the surface of each substrate. The elongated injection tubes are rotatable about an axis in 360 degrees.
In another embodiment, the apparatus of the present invention comprises a process chamber providing a process region for a plurality of substrates held in a carrier, a cross-flow liner enclosing the carrier, and a cross-flow injection system disposed between the carrier and the cross-flow liner to direct flow of one or more gases across the surface of each substrate. The cross-flow injection system comprising a plurality of injection ports rotatable about an axis.
These and various other features and advantages of the present invention will be apparent upon reading of the following detailed description in conjunction with the accompanying drawings and the appended claims provided below, where:
The present invention is directed to an apparatus and method for processing a relatively small number or mini-batch of one or more work pieces, such as semiconductor substrates or wafers, held in a carrier, such as a cassette or boat, that provides reduced processing cycle times and improved process uniformity.
As used herein the term “mini-batch” means a number of wafers less than the hundreds of wafers found in the typical batch systems, and preferably in the range of from one to about fifty-three semiconductor wafers or wafers, of which from one to fifty are product wafers and the remainder are non-product wafers used for monitoring purposes and as baffle wafers.
By thermal processing it is meant processes that in which the work piece or wafer is heated to a desired temperature which is typically in the range of about 350° C. to 1300° C. Thermal processing of semiconductor wafers can include, for example, heat treating, annealing, diffusion or driving of dopant material, deposition or growth of layers of material, such as chemical vapor deposition or CVD, and etching or removal of material from the wafers.
A thermal processing apparatus according to an embodiment will now be described with reference to
Generally, the vessel 101 is sealed by a seal, such as an o-ring 122, to a platform or base-plate 124 to form the process chamber 102, which completely encloses the wafers 108 during thermal processing. The dimensions of the process chamber 102 and the base-plate 124 are selected to provide a rapid evacuation, rapid heating and a rapid backfilling of the process chamber. Advantageously, the vessel 101 and the base-plate 124 are sized to provide a process chamber 102 having dimensions selected to enclose a volume substantially no larger than necessary to accommodate the carrier 106 with the wafers 108 held therein. Preferably, the vessel 101 and the base-plate 124 are sized to provide a process chamber 102 having dimensions of from about 125 to about 150% of that necessary to accommodate the carrier 106 with the wafers 108 held therein, and more preferably, the process chamber has dimensions no larger than about 125% of that necessary to accommodate the carrier and the wafers in order to minimize the chamber volume which aids in pump down and back-fill time required.
Openings for the injectors 116, T/Cs 114 and vents 118 are sealed using seals such as o-rings, VCR®, or CF® fittings Gases or vapor released or introduced during processing are evacuated through a foreline or exhaust port 126 formed in a wall of the process chamber 102 (not shown) or in a plenum 127 of the base-plate 124, as shown in
In another embodiment, shown in
Additionally, the base-plate 124 shown in
The vessel 101 and liner 120 can be made of any metal, ceramic, crystalline or glass material that is capable of withstanding the thermal and mechanical stresses of high temperature and high vacuum operation, and which is resistant to erosion from gases and vapors used or released during processing. Preferably, the vessel 101 and liner 120 are made from an opaque, translucent or transparent quartz glass having a sufficient thickness to withstand the mechanical stresses and that resists deposition of process byproducts, thereby reducing potential contamination of the processing environment. More preferably, the vessel 101 and liner 120 are made from quartz that reduces or eliminates the conduction of heat away from the region or process zone 128 in which the wafers 108 are processed.
The batch of wafers 108 is introduced into the thermal processing apparatus 100 through a load lock or loadport (not shown) and then into the process chamber 102 through an access or opening in the process chamber or base-plate 124 capable of forming a gas tight seal therewith. In the configuration shown in
The heating elements 112 include elements positioned proximal to a top 134 (elements 112-3), side 136 (elements 112-2) and bottom 138 (elements 112-1) of the process chamber 102. Advantageously, the heating elements 112 surround the wafers to achieve a good view factor of the wafers and thereby provide an isothermal control volume or process zone 128 in the process chamber in which the wafers 108 are processed. The heating elements 112-1 proximal to the bottom 138 of the process chamber 102 can be disposed in or on the pedestal 130. If desired, additional heating elements may be disposed in or on the base plate 124 to supplement heat from the heating elements 112-1.
In the embodiment shown in
The side heating elements 112-2 and the top heating elements 112-3 may be disposed in or on an insulating block 110 about the vessel 101. Preferably the side heating elements 112-2 and the top heating elements 112-3 are recessed in the insulating block 110.
The heating elements 112 and the insulating blocks 110 and 140 may be configured in any of a variety of ways and may be made in any of a variety of ways and with any of a variety of materials.
Preferably, to attain desired processing temperatures of up to 1150° C. the heating elements 112-1 proximal to the bottom 138 of the process chamber 102 have a maximum power output of from about 0.1 kW to about 10 kW with a maximum process temperature of at least 1150° C. More preferably, these bottom heating elements 112-1 have a power output of at least about 3.8 kW with a maximum process temperature of at least 950° C. In one embodiment, the side heating elements 112-2 are functionally divided into multiple zones, including a lower zone nearest the pedestal 130 and upper zone, each of which are capable of being operated independently at different power levels and duty cycles from each other and from the top heating elements 112-3 and bottom heating elements 112-1.
The heating elements 112 are controlled in any suitable manner, either by using a control technique of a type well known in the art.
Contamination from the insulating block 140 and bottom heating elements 112-1 is reduced if not eliminated by housing the heating element and insulation block in an inverted quartz crucible 142, which serves as a barrier between the heating element and insulation block and the process chamber 102. The crucible 142 is also sealed against the loadport and BHU environment to further reduce or eliminate contamination of the processing environment. Generally, the interior of the crucible 142 is at standard atmospheric pressure, so that the crucible 142 should be strong enough to withstand a pressure differential between the process chamber 102 and the pedestal 130 across the crucible 142 of as much as 1 atmosphere.
While the wafers 108 are being loaded or unloaded, that is while the pedestal 130 is in the lowered position (
In order to further reduce preprocessing time, that is the time required to prepare the thermal processing apparatus 100 for processing, the bottom heating elements 112-1 can be ramped to at or below the desired process temperature during the push or load, that is while the pedestal 130 with a boat 106 of wafers 108 positioned thereon is being raised. However, to minimize thermal stresses on the wafers 108 and components of the thermal processing apparatus 100 it is preferred to have the bottom heating elements 112-1 reach the desired process temperature at the same time as the heating elements 112-3 and 112-2 located proximal to respectively the top 134 and side 136 of the process chamber 102. Thus, for some processes, such as those requiring higher desired process temperatures, the temperature of the bottom heating elements 112-1 can begin being ramped up before the pedestal 130 begins being raised, while the last of the wafers 108 in a batch are being loaded.
Similarly, it will be appreciated that after processing and during the pull or unload cycle, that is while the pedestal 128 is being lowered, power to the bottom heating elements 112-1 can be reduce or removed completely to begin ramping down the pedestal 130 to the idle temperature, in preparation for cooling of the wafers 108 and unloading by the BHU.
To assist in cooling the pedestal 130 to a pull temperature prior to the pull or unload cycle, a purge line for air or an inert purge gas, such as nitrogen, is installed through the insulating block 140. Preferably, nitrogen is injected through a passage 144 through the center of the insulating block 140 and allowed to flow out between the top of the insulating block 140 and the interior of the crucible 142 to a perimeter thereof. The hot nitrogen is then exhausted to the environment either through High Efficiency Particulate Air (HEPA) filter (not shown) or to a facility exhaust (not shown). This center injection configuration facilitates the faster cooling of the center of the wafers 108, and therefore is ideal to minimize the center/edge temperature differential of the bottom wafer or wafers, which could otherwise result in damage due to slip-dislocation of the crystal lattice structure.
As noted above, to increase or extend the life of bottom heating element 112-1 the idle temperature can be set higher, closer to the desired processing temperature to reduce the effects of thermal cycling. In addition, it is also desirable to periodically bake out the heating elements 112-1 in an oxygen rich environment to promote the formation of a protective oxide surface coat. For example, where the resistive heating elements are formed from an Aluminum containing alloy, such as Kanthal®, baking out the heating elements 112-1 in an oxygen rich environment promotes an alumna oxide surface growth. Thus, the insulating block 140 can further include an oxygen line (not shown) to promote the formation of the protective oxide surface coat during bake out of the heating elements 112-1. Alternatively, oxygen for bake out can be introduced through the purge line used during processing to supply cooling nitrogen via a three-way valve.
Alternatively, the rotable shaft 150 can be a mounted on or affixed to another part of the thermal processing apparatus 100 and adapted to move axially in synchronization with the pedestal 130, or to rotate the thermal shield 146 into position only when the pedestal is fully lowered.
According to one embodiment the thermal shield 146 can be made from a single material such as silicon-carbide (SiC), opaque quartz or stainless steel which has been polished on one side and scuffed, abraded or roughened on the other. Roughening a surface of the thermal shield 146 can significantly change its heat transfer properties, particularly its reflectivity.
In another embodiment, the thermal shield 146 can be made from two different layers of material.
In yet another embodiment, the thermal shield 146 further includes an internal cooling channel 156 to further insulate the wafers 108 from the bottom heating elements 112-1. In one version of this embodiment, shown in
As shown in
For a process chamber 102 that is normally operated under vacuum, such as in a CVD system, the shutter 158 could form a vacuum seal against the base-plate 124 to allow the process chamber 102 to be pumped down to the process pressure or vacuum. For example, it may be desirable to pump down the process chamber 102 between sequential batches of wafers to reduce or eliminate the potential for contaminating the process environment. Forming a vacuum seal is preferably done with a large diameter seal, such as an o-ring, and thus the shutter 158 can desirably include a number of water channels 160 to cool the seal. In the embodiment shown in
For a thermal processing apparatus 130 in which the process chamber 102 is normally operated at atmospheric pressure, the shutter 158 is simply an insulating plug designed to reduce heat loss from the bottom of the process chamber. One embodiment for accomplishing this involves the use of an opaque quartz plate, which may or may not further include a number of cooling channels underneath or internal thereto.
When the pedestal 130 is in the fully lowered position, the shutter 158 is moved into position below the process chamber 102 and then raised to isolate the process chamber by one or more electric, hydraulic or pneumatic actuators (not shown). Preferably, the actuators are pneumatic actuators using from about 15 to 60 pounds per square inch gauge (PSIG) air, which is commonly available on thermal processing apparatus 100 for operation of pneumatic valves. For example, in one version of this embodiment the shutter 158 can comprise a plate having a number of wheels attached via short arms or cantilevers to two sides thereof. In operation, the plate or shutter 158 is rolled into position beneath the process chamber 102 on two parallel guide rails. Stops on the guide rails then cause the cantilevers to pivot translating the motion of the shutter 158 into an upward direction to seal the process chamber 102.
As shown in
The wafer rotation system 162 includes a drive assembly or rotating mechanism 164 having a rotating motor 166, such as an electric or pneumatic motor, and a magnet 168 encased in a chemically resistive container, such as annealed polytetrafluoroethylene or stainless steel. A steel ring 170 located just below the insulating block 140 of the pedestal 130, and a drive shaft 172 with the insulating block transfer the rotational energy to another magnet 174 located above the insulating block in a top portion of the pedestal. The steel ring 170, drive shaft 172 and second magnet 174 are also encased in a chemically resistive container compound. The magnet 174 located in the side of the pedestal 130 magnetically couples through the crucible 142 with a steel ring or magnet 176 embedded in or affixed to the support 104 in the process chamber 102.
Magnetically coupling the rotating mechanism 164 through the pedestal 130 eliminates the need for locating it within the processing environment or for having a mechanical feedthrough, thereby eliminating a potential source of leaks and contamination. Furthermore, locating rotating mechanism 164 outside and at some distance from the processing minimizes the maximum temperature of to which it is exposed, thereby increasing the reliability and operating life of the wafer rotation system 162.
In addition to the above, the wafer rotation system 162 can further include one or more sensors (not shown) to ensure proper boat 106 position and proper magnetic coupling between the steel ring or magnet 176 in the process chamber 102 and the magnet 174 in the pedestal 130. A sensor which determines the relative position of the boat 106, or boat position verification sensor, is particularly useful. In one embodiment, the boat position verification sensor includes a sensor protrusion (not shown) on the boat 106 and an optical or laser sensor located below the base-plate 124. In operation, after the wafers 108 have been processed and the pedestal 130 is lowered about 3 inches below the base-plate 124. There, the wafer rotation system 162 is commanded to turn the boat 106 until the boat sensor protrusion can be seen. Then, the wafer rotation system 162 is operated to align the boat so that the wafers 108 can be unloaded. After this is done, the boat is lowered to the load/unload height. After the initial check, it is only capable of verifying the boat location from the flag sensor.
As shown in
Additionally, X-flow injectors 216 can serve other purposes, including the injection of gases for cool-down (e.g., helium, nitrogen, hydrogen) for forced convective cooling between the wafers 108. Use of X-flow injectors 216 results in a more uniform cooling between wafers 108 whether disposed at the bottom or top of the stack or batch and those wafers that are disposed in the middle, as compared with earlier up-flow or down flow configurations. Preferably, the injector 216 orifices 180 are sized, shaped and position to provide a spray pattern that promotes forced convective cooling between the wafers 108 in a manner that does not create a large temperature gradient across the wafer.
Also as shown in
Advantageously, the injectors 116, 216, and/or the liner 120 can be quickly and easily replaced or swapped with other injectors and liners having different points for the injection and exhausting of the process gas from the process zone 128. It will be appreciated by those skilled in the art that the embodiment of the x-flow injector 216 shown in
The injectors 116, 216, and the liner 120 can be separate components, or the injector can be integrally formed with liner as a single piece. The latter embodiment is particular useful in applications where it is desirable to frequently change the process chamber 102 configuration.
An illustrative method or process for operating the thermal processing apparatus 100 is described with reference to
A method or process for a thermal processing apparatus 100 according to another embodiment will now be described with reference to
It has been determined that the thermal processing apparatus 100 provided and operated as described above, reduces the processing or cycle time by about 75% over conventional systems. For example, a conventional large batch thermal processing apparatus may process 100 product wafers in about 232 minutes, including pre-processing and post-processing time. The inventive thermal processing apparatus 100 performs the same processing on a mini-batch of 25 product wafers 108 in about 58 minutes.
An injection system in accordance with one embodiment of the present invention will be now described with reference to
Injectors having injection ports or orifices distributed in elongated tubes have been used in both horizontal and vertical furnaces to control gas concentration across the surface of substrates. Typically, two or more injectors are used to distribute similar or different gases depending on specific applications. For example, for deposition of P-doped polysilicon, injectors with distributed injection ports have been used to introduce PH3 gas across a wafer load in a furnace to provide a uniform gas concentration. Injectors with distributed injection ports are used to ensure that the properties of the deposited films are the same across the wafer load. Traditionally, the injectors are fixed, i.e., the direction of injection ports or orifices in the injectors are fixed and typically face toward the center of wafers. Even so, films deposited on the wafers still exhibit an undesirable within-wafer uniformity. The uniformity, quality and repeatability of deposited films depend on not only gas flow rates, concentration, pressure and temperature, but also gas flow pattern and distribution of gases. The present invention provides an injection system that is angularly adjustable to promote the momentum transfer of “ballistic mixing” of different gases to provide improved flow uniformity and thus improved quality and uniformity of the deposited films. In general, the injection system of the present invention comprises one or more elongated injection tubes having a plurality of injection ports or orifices distributed in the tubes for directing flow of reactant and other gases across the surface of each substrate. The elongated injection tubes are rotatable about an axis in 360 degrees.
The cross-flow injection system 250 includes one or more elongated injection tubes.
For example, when the index pin in the elongated tube 256 is locked in notch 274A, the injection ports 252 are oriented to face the inner surface of the liner 232. Gases exiting the injection ports 252 impinge the wall and mix prior to flowing across the surface of each substrate 242. In another embodiment, the index pin in the elongated tube 256 is locked in notch 274B. The injection ports 252 in each injection tube 256 are oriented to face each other. Gases exiting the injection ports 252 impinge each other and mix prior to flowing across the surface of each substrate 242. In a further embodiment, the index pin in the elongated tube 256 is locked in notch 274C so that the injection ports 252 are oriented to face the center of the substrate 242. The number of notches formed in the openings can be as many as desired so that the elongated tube 256 can be rotated in 360 degrees and stabilized in a desired position, and accordingly the injection ports 252 can be oriented to a desired direction.
Of advantage, the injection system of the present invention enables full freedom of rotation of the injection ports to promote the momentum transfer of “ballistic mixing” of gases, which may vary in different processes. The orientation of the injection ports or orifices that influence gas mixing and flow direction can be adjusted on a run-to-run basis without the need of process chamber modification.
In one embodiment, the injection system of the present invention is used in connection with a cross flow liner having a bulging section. U.S. application Ser. No. ______ (Attorney Docket No. 33586/US/1) filed currently with this application further describes a cross-flow liner, the disclosure of which is hereby incorporated by reference in its entirety.
In one embodiment shown in
The following examples are provided to further illustrate the present invention and are not intended to limit the scope of the invention in any way.
This example illustrates deposition of silicon nitride using dichlorosilane (DCS) and NH3 gases. The deposition is performed in a thermal processing apparatus including an injection system of the present invention. The injection system comprises a first injection tubes for introducing DCS gas and a second injection tube for introducing NH3 gas. Each of the first and second injection tubes is provided with a plurality of ports or orifices for directing gas flow across the surface of each substrate.
In one variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face the inner surface of the liner. DCS and NH3 gases exiting the injection ports away from wafers and impinge the liner inner surface prior to flowing across the surface of each substrate.
In another variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face the center of the substrate. DCS and NH3 gases exit the injection ports and flow across the surface of each substrate.
This example illustrates deposition of silicon nitride using bis tertiarybutylamino silane (BTBAS) and NH3 gases. The deposition is performed in a thermal processing apparatus including an injection system of the present invention. The injection system comprises a first injection tube for introducing BTBAS gas and a second injection tube for introducing NH3 gas. Each of the first and second injection tubes is provided with a plurality of ports or orifices for directing gas flow across the surface of each substrate.
In one variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face the inner surface of the liner. BTBAS and NH3 gases exiting the injection ports away from wafers and impinge the liner wall prior to flowing across the surface of each substrate.
In another variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face each other. BTBAS and NH3 gases exit the injection ports and impinge and mix prior to flowing across the surface of each substrate.
This example illustrates deposition of aluminum oxide (Al2O3) using trimethyl aluminum (TMA) and ozone (O3) gases. The deposition is performed in a thermal processing apparatus including an injection system of the present invention. The injection system comprises a first injection tube for introducing TMA gas and a second injection tube for introducing O3 gas. Each of the first and second injection tubes is provided with a plurality of ports or orifices for directing gas flow across the surface of each substrate.
In one variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face the inner surface of the liner. TMA and O3 gases exiting the injection ports away from wafers and impinge the liner wall prior to flowing across the surface of each substrate.
In one variation, the elongated tubes are rotated and adjusted so that the injection ports are oriented to face each other. TMA and O3 gases exit the injection ports and impinge and mix prior to flowing across the surface of each substrate.
The foregoing description of specific embodiments and examples of the invention have been presented for the purpose of illustration and description, and although the invention has been described and illustrated by certain of the preceding examples, it is not to be construed as being limited thereby. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications, improvements and variations within the scope of the invention are possible in light of the above teaching. It is intended that the scope of the invention encompass the generic area as herein disclosed, and by the claims appended hereto and their equivalents.
This application claims the benefit of and priority to U.S. Provisional Patent Application No. 60/506,354 filed Sep. 25, 2003, the disclosure of which is hereby incorporated by reference in its entirety, and is related to PCT application Serial No. PCT/US03/21575 entitled Thermal Processing System and Configurable Vertical Chamber, which claims priority to U.S. Provisional patent application Ser. Nos. 60/396,536 and 60/428,526, the disclosures of all of which are hereby incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60506354 | Sep 2003 | US |
