US20030066606A1

US20030066606A1 - Dual wafer position loadlock chamber

Info

Publication number: US20030066606A1
Application number: US10/290,546
Authority: US
Inventors: Andrew Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-07-03
Filing date: 2002-11-08
Publication date: 2003-04-10
Also published as: EP1303449A4; KR20020047143A; EP1303449B1; WO2002002445A1; HK1051992A1; US6562141B2; EP1303449A1; DE60119119D1; CN1386105A; JP2004503099A; CN1193922C; JP5048198B2; US20020000194A1; ATE324341T1; DE60119119T2

Abstract

A dual wafer position loadlock chamber for a cluster tool includes a block which defines the chamber, a platen that projects into the chamber, a heat lamp assembly that radiates into the loadlock chamber and a plurality of rails for positioning a wafer within the chamber. The platen selectively cools the wafer and includes a bell portion located within the loadlock chamber. The heat lamp assembly is mounted to the block across the chamber from the bell portion. The rails extend into the loadlock chamber around the bell portion, and an upper flange and lower flange extend perpendicularly from each rail. During cooling operations, the wafer is placed on the upper flanges, which positions the wafer immediately proximate the bell portion for cooling the wafer. During degassing operations, the wafer is placed on the lower flanges and the heat lamp assembly illuminates and establishes a focal plane of uniform radiation intensity which is co-planar with the wafer. In this manner, the loadlock chamber allows both wafer degassing and wafer cooling functions to be performed within the loadlock chamber, which eliminates the need for a dedicated degassing chamber and cooling chamber in the cluster tool.

Description

This application is a Divisional Application of application Ser. No. 09/798,048, which was filed Mar. 5, 2002, which further is a Divisional Application of application Ser. No. 09/609,733, which was filed Jul. 3, 2000.[0001]

FIELD OF THE INVENTION

The present invention pertains generally to cluster tools and processes which use a cluster tool. More particularly, the present invention pertains to a loadlock chamber for a cluster tool. The invention is particularly, but not exclusively, useful as a loadlock chamber which allows for selective positioning of a wafer therein so that both cooling and degassing processes can be efficiently performed on the wafer while it is still in the loadlock chamber.

BACKGROUND OF THE INVENTION

In the semiconductor industry, a sputtering, or deposition, process is used to coat silicon wafers with a uniform, extremely thin coating, and the devices that accomplish this result are known in the industry as cluster tools. To accomplish the deposition process, however, the silicon wafer must be processed within a cluster tool capable of maintaining an extreme vacuum condition to ensure film purity. In addition to the vacuum issue, all water vapor molecules must be removed from the wafer to prevent contamination of the vacuum processes within the cluster tool, as water vapor is an undesirable process component that affects the quality of the finished wafer. Finally, outgoing wafers may be hot after undergoing a plurality of vacuum processes, and it is desirable to cool the wafers within the cluster tool, to reduce the risk of oxidation or corrosion.

Prior art cluster tools typically have a dedicated degassing chamber for degassing the wafer, or removing the entrained water vapor molecules from the wafer. In the prior art, once the cassette module is under “rough” to mid-range vacuum conditions (10 ⁻²torr to 10⁻³torr, where 760 torr=1 Atm=atmospheric pressure), the wafers are successively placed in the dedicated degassing chamber for individual degassing prior to undergoing several vacuum processes. The dedicated degassing chamber is usually within the high vacuum body of the prior art cluster tool. What is desired is a cluster tool that degasses the wafers in the loadlock chamber under rough vacuum conditions. This eliminates the need for a dedicated processing position within the high vacuum body of the cluster tool.

Degassed water vapor is removed from the high vacuum body of the cluster tool by cryopumps. A cryopump typically consists of a refrigeration unit that maintains an extremely low temperature on an array of metallic plates. The array is positioned in communication with the chamber and the water vapor molecules therein, and the water molecules impinge on the plate and are frozen thereto. These cryopumps are expensive and difficult to maintain. What is desired is a cluster tool that eliminates the need for a dedicated cryopump for each degassing chamber. One way to eliminate a dedicated cryopump is to remove water vapor molecules from the wafer while the wafer is at rough vacuum in the loadlock chamber. This will reduce the amount of residual water vapor in the proximity of the high vacuum body of the cluster. If this can be accomplished, vacuum quality and vacuum process quality can be enhanced. Also, the required number of cryopumps for the cluster tool would decrease, which would further decrease the maintenance requirements for the cluster tool and increase the overall reliability of the tool.

In the prior art, wafers are introduced to the loadlock in a 25-wafer cassette module, which is typically placed in the loadlock chamber before the loadlock chamber (along with the entire cassette module) is pumped down to high vacuum. Once at high vacuum, each wafer from the cassette module is degassed. Next, the wafer is successively placed in a plurality of vacuum processing chambers and undergoes a plurality of vacuum processes. After completion of the processes, the wafer may be placed in a dedicated chamber for cooling. The wafer is then returned to the cassette module, and another wafer is selected from the cassette to begin the processes discussed above. When all of the wafers in the cassette module have finished processing, the entire cassette module is removed from the loadlock chamber.

With the above configuration, however, the first wafer spends more time cooling after its process is completed than the final wafer. Conversely, the last wafer to be processed has spent more time “drying” under vacuum before undergoing its vacuum processes. This can lead to a drift in measurable process quality in the wafers being loaded one at a time from the cassette module into the cluster tool for processing. This is known in the prior art as the “first wafer effect”. What is desired is a cluster tool with loadlock chambers that are capable of performing both degas and cooling functions during processing of the wafer, to standardize the amount of time each wafer spends at each step of the process and, thereby, to improve the consistency of the finished wafer quality.

In view of the above, it is an object of the present invention to provide a cluster tool with a loadlock chamber that selectively allows for both degassing and for cooling the wafer therein, to decrease the overall processing time and increase wafer throughput for the cluster tool. It is another object of the present invention to provide a cluster tool that allows for multiple wafer positions to more for efficiently perform the degassing and the cooling steps within the loadlock chamber. Yet another object of the present invention is to provide a cluster tool with a loadlock chamber that eliminates the need for separate dedicated degassing and cooling chambers. It is another object of the present invention to provide a cluster tool with a loadlock chamber that is sized to process a single wafer at a time, to thereby minimize the required volume to be placed under vacuum and eliminate what is known as “the first wafer effect”. Another object of the present invention is to provide a process chamber which can be easily manufactured in a cost effective manner.

SUMMARY OF THE INVENTION

A cluster tool having a loadlock chamber for performing both cooling and degassing processes in accordance with the present invention includes a block formed with a loadlock chamber and a platen. The block is formed with a top wall, side walls and a bottom wall which cooperate to define the loadlock chamber. The platen comprises a stem that merges into a bell portion. The platen stem is slidingly positioned within an opening in the top wall and mounted to the block so that the platen projects downwardly into the loadlock chamber and the bell portion is located completely within the loadlock chamber. The bell portion terminates at a flat bottom surface. The platen may also form a fixed top or ceiling for the chamber, and the wafer holding mechanism may be designed to move the wafer up into close proximity.

The loadlock chamber of the present invention also includes a holding means for selectively positioning a silicon wafer within the loadlock chamber. The holding means comprises a plurality of rails that extend downwardly from the top wall in a surrounding relationship with the bell portion of the platen. Each rail has an upper flange and a lower flange that project perpendicularly from the rail to thereby establish an inverted F-shape for the rail. When the wafer is resting on the upper flanges, the wafer is parallel to and immediately proximate the bell portion bottom surface. The platen (particularly the bell portion) is refrigerated, and the proximity of the wafer to the bottom surface allows for a transfer of heat, which cools the wafer. Alternatively, the bell portion may be at room temperature with a “showerhead” configuration that allows some portion of the venting gas (Nitrogen, for example) to flow over the wafer in order to cool it.

The loadlock chamber of the present invention further includes a heat lamp assembly. The bottom wall is of the loadlock chamber is made of a material which allows the efficient passage of radiant energy therethrough, and the reflector is fixed to the outer surface of the bottom wall so that the upper heat lamps and lower heat lamps are oriented to radiate through the bottom wall into the loadlock chamber. When the wafer is resting upon the lower flanges of the holding means, the wafer is preferably parallel to and immediately proximate the bottom wall and receives radiation from the heat lamp assembly to thereby degas the wafer while within the loadlock chamber.

The heat lamp assembly comprises an upper plurality of upper heat lamps and a lower plurality of lower heat lamps that are mounted to a reflector. The upper heat lamps have an upper spacing and illuminate with an intensity which establishes a first focal plane of uniform radiation intensity. Preferably, when the wafer is resting on the lower flanges and the upper heat lamps are illuminated, the wafer is coextensive with the first focal plane. Similarly, the lower heat lamps have a lower spacing and illuminates with a lower intensity which establishes a second focal plane of uniform radiation intensity that is co-planar with the first focal plane and with the wafer. Alternatively, the heat lamps consist or an array of individual bulbs positioned to allow uniform heating of the wafer. For example, the bulbs may be of the tungsten-halogen bar type commonly used in work lights, arranged circularly in columnar fashion. In this manner, the plate, holding means and heat lamp assembly combine to establish a loadlock chamber which can perform both a cooling and a degassing function, thereby reducing the number of loadlock chambers required for the cluster tool.

For the method of the present invention, the wafer is placed in the loadlock chamber on the lower flanges. Simultaneously, the heat lamps are activated to radiate heat energy to the wafer, thereby causing the release of water vapor molecules from the wafer, thereby degassing the wafer. Thereafter, the wafer undergoes a plurality of manufacturing processes in a manner known in the art. When returned to the loadlock chamber, the wafer is positioned on the upper flanges and a cooling gas is force through the platen to cool the wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar characters refer to similar parts, and in which: [0014]
FIG. 1 is a top plan view of the cluster tool of the present invention with a large portion of the top wall of the tool removed for clarity. [0015]
FIG. 2 is a cross-sectional view of the front portion of FIG. 1 as seen along lines [0016] 2-2 in FIG. 1.
FIG. 3 is a cross-sectional view of a single loadlock chamber and the high vacuum chamber of the front portion of FIG. 2 during a degassing operation. [0017]
FIG. 4 is the same view as FIG. 3 with the slot valve open and the high vacuum pump operating. [0018]
FIG. 5 is the same view as FIG. 3 during a cooling operation. [0019]
FIG. 6 is an isometric view of the reflector and heat lamp assembly portions of FIG. 3, with portions removed for clarity [0020]
FIG. 7 is a cross sectional view of the reflector, heat lamp assembly and holding means of the loadlock chamber of FIG. 3 during a degassing operation. [0021]
FIG. 8 is an isometric view of an alternative embodiment of the heat lamp assembly shown in FIG. 7, with portions removed for clarity.[0022]

WRITTEN DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to FIGS. 1 and 2, the cluster tool of the present invention is shown and generally designated by [0023] reference character 10. As shown, the structural framework for a cluster tool comprises a block 12 which includes a front portion 14 and a rear portion 16. The front portion includes a front wall 25 and a valve retaining wall 27 behind the front wall and is oriented somewhat parallel thereto. A pair of symmetrically opposed front portion side walls 13, 13 respectively merge into similarly opposed rear portion side walls 15, 15. The rear portion side walls further merge rearward into a first diagonal wall 43 and a second diagonal wall 44. The first and second diagonal walls merge into rear portion rear wall 40, as shown in FIG. 1. The front portion side walls, rear portion side walls, first and second diagonal walls and rear portion rear wall all project about perpendicularly from bottom wall 62.
The front portion of the block includes two [0024] loadlock chambers 18, 18. As best seen in FIG. 2, the front portion further includes a high vacuum chamber 20 that is in communication with each respective loadlock chamber. Each loadlock chamber is selectively isolated from the high vacuum chamber with a slot valve 22, 22 that is attached to top wall 56, front wall 25 and valve retaining wall 27 in a manner hereinafter more fully described. By referring to both FIGS. 1 and 2, it can be seen that the cluster tool includes a pair of top cover plates 80, 80, with each top cover plate being attached to a respective front portion wall notch 79 and top wall notch 81.
In the preferred embodiment, the block is made from an aluminum alloy. However, other types of machinable and/or castable metal alloys may be used without departing from the scope of the present invention. [0025]
A [0026] front loader 24 is attached to front wall 25 of the block. The front loader includes a pair of bay doors 26, 26 that correspond to front openings 28, 28 in the front wall. The front openings provide an access through the front wall to the loadlock chambers. A plurality of cassette modules, of which module 30 a is representative, are attached to the front loader. These may be open wafer cassettes, SMIF (Standard Mechanical Interface Format) devices, FOUP's (Front Opening Universal Pods) or other structures known in the art for holding wafers. The front loader has internal structure (not shown), typically a front loader robot, for selectively transferring silicon wafers 32 from the cassette module through the bay doors to the loadlock chambers in a manner known in the prior art. An exemplary front loader of the type discussed is manufactured by Asyst® or Brooks Automation®.
In [0027] rear portion 16, a plurality of processing pods 34 are attached to the bottom wall of the block for accomplishing a sequence of vacuum processes on silicon wafer 32. The rear portion also includes an etching station 36, which is electrically connected to a radio frequency (RF) matching unit/power supply 38 that is mounted on rear wall 40 of the block.
First [0028] rear cryopump 41 is attached to rear diagonal wall 43, and second rear cryopump 42 is attached to rear diagonal wall 44 of the block in communication with rear portion chamber 19, as shown in FIG. 1. The first and second rear cryopumps remove water vapor and gas molecules and establish a high vacuum in rear portion chamber 19 in a manner known in the prior art.
As further seen in FIG. 1, a [0029] rear robot 46 is centrally placed within the rear portion and attached to bottom wall 62. The rear robot selectively accesses the loadlock chambers through loadlock access valves 52, 52 that are attached to valve retaining wall 27 and front portion side walls 13, 13. The rear robot selectively transfers the wafer between loadlock chambers in the front portion of the cluster tool and the various processing pods in the rear portion chamber. The rear robot further transfers wafers between the vacuum process pods and the etching station, according to a predetermined algorithm that is programmed by a user (not shown) according to design requirements for the finished wafer.
Referring now to FIGS. [0030] 2-5, the front portion of the block is shown with the high vacuum chamber 20 transversely centered within the front portion. As stated above, the high vacuum chamber is between the loadlock chambers and also is in communication with each loadlock chamber. As also stated above, a slot valve is mounted between each loadlock chamber and the high vacuum chamber for selectively isolating each loadlock chamber from the high vacuum chamber. Each slot valve includes a valve body 54 which is mounted to top wall 56 of the block.
The valve body includes a [0031] valve stem 58 which is slidingly disposed within the valve body and has an extended position wherein the valve stem protrudes downwardly through the block into the high vacuum chamber. Valve stem 58 further has a retracted position wherein the valve stem is substantially encased by the valve body.
For each slot valve, a [0032] valve seat 60 is machined into the inner surface of bottom wall 62 of the block opposite from the valve stem. As best seen in FIGS. 2-5, when the valve stem 58 is in the retracted position within the valve body, a path of communication will exist between the corresponding loadlock chamber and the high vacuum chamber. When the valve stem is in the extended position, the valve stem will be seated in valve seat 60, and the corresponding loadlock chamber will be isolated from the high vacuum chamber.
A [0033] water pump 64 which includes a refrigeration unit 68 and a cryoplate 70 is attached to top wall 56 of the block. The refrigeration unit extends upwardly therefrom. The cryoplate is in thermal communication with the refrigeration unit and extends downwardly therefrom through the top wall and into the high vacuum chamber.
The refrigeration unit includes a [0034] cryoplate cooling line 72 which extends from the refrigeration unit and is routed internally within the cryoplate. The cryoplate cooling line circulates coolant (not shown) from the refrigeration unit through the cryoplate and back to the refrigeration unit, for maintaining a desired temperature on the cryoplate surface. In the preferred embodiment, the cryoplate is maintained at a temperature of approximately one hundred degrees Kelvin (T=100° K). Further, it is to be appreciated that other configurations for the heat exchanger and cryoplate are envisioned, provided the cryoplate can maintain the desired low temperatures.
A [0035] flat face 76 of the cryoplate is directly in front of the slot valve opening 74 of each loadlock chamber, for reasons to be described. With this configuration, a single water pump can serve a plurality of loadlock chambers.
A high vacuum pump [0036] 78 (depicted in schematic in FIGS. 2-5) is attached in communication with the high vacuum chamber for establishing a high vacuum therein in a manner known in the art. Once the corresponding slot valve is open, the loadlock chamber will be in communication with high vacuum chamber 20, and a high vacuum will also be established in the corresponding loadlock chamber. In a preferred embodiment, the high vacuum pump is a magnetic-levitation-bearing turbopump for producing a vacuum in the range of 10⁻⁴to 10⁻⁸torr. An exemplary type of pump is manufactured by Varian®.
With further reference to FIGS. [0037] 2-5, the loadlock chamber of the present invention also includes a platen 82. The platen comprises a platen stem 83 that merges into a lower bell portion 84. The platen stem is oriented vertically and is slidingly disposed within an opening 85 in the top cover plate. With the platen stem oriented in this manner, the bell portion of the platen will be located within the loadlock chamber, and bell portion bottom surface 86 will be oriented horizontally within the loadlock chamber.
To maintain a predetermined platen temperature, a [0038] platen cooling system 92 is connected to the platen stem. Specifically, a platen cooling supply line 94 is attached to the platen cooling system. The supply line extends internally within the platen stem and merges into a platen cooling return line 96. The platen cooling return line 96 is also internally located within the platen stem and exits therefrom to connect with the platen cooling system. With this configuration, refrigerant (not shown) is circulated from the platen cooling system internally through the platen stem and back to the platen cooling system for cooling the platen.
A platen [0039] gas supply line 98 also is mounted internally within the platen stem. The platen gas supply line extends from a platen gas supply 100 and terminates at the bottom surface of the platen. A platen gas line flow-controlling valve 102 is attached to the platen gas line to selectively isolate the loadlock chamber from the platen gas supply and to control the flow of gas therefrom. This configuration allows a path of fluid communication to be selectively established between the platen gas supply and the loadlock chamber, for cooling a wafer as described below.
A bellows [0040] 88 is mounted to the top cover plate outer surface 90, and the bellows is further attached in a surrounding relationship to the platen stem 83. The bellows allows for a sliding up-and-down movement of the platen, while at the same time maintaining vacuum integrity within the loadlock chamber.
Each loadlock chamber includes a [0041] chamber gas supply 103 for venting the loadlock chamber. A chamber gas supply line 105 is attached to the chamber gas supply and terminates at the inner wall 108 of the loadlock chamber to provide a path of fluid communication between the chamber gas supply and the loadlock chamber. A vent valve 107 in the chamber gas supply line 105 selectively isolates the chamber gas supply from the loadlock chamber.
In the preferred embodiment, a gas, such as Argon or Nitrogen, is used as the working gas for the platen gas supply, as well as the chamber gas supply. It is to be appreciated, however, that other gases could be used for performing the cooling function of the platen gas supply and the venting function of the chamber gas supply, as described above. [0042]
With reference to FIG. 2, each loadlock chamber includes a [0043] respective roughing pump 104 for establishing an initial “rough” (approximately 10⁻²to 10⁻³torr) vacuum on the loadlock chamber. The roughing pump is connected in fluid communication with the loadlock chamber via a roughing pump line 106 which extends through the front portion side wall and terminates at inner surface 108 of the front portion side wall. A roughing pump valve 110 is placed in the roughing pump line to selectively isolate the roughing pump from the loadlock chamber.
Each loadlock chamber has a dedicated roughing pump. It is to be appreciated, however, that two loadlock chambers are never pumped to rough vacuum conditions at the same time, as hereinafter discussed in the Operation section of this specification. Accordingly, roughing [0044] pump line 106 could be routed to a plurality of loadlock chambers so that only one roughing pump can be used for a plurality of loadlock chambers.
A [0045] bottom cover plate 112 is attached to the bottom wall 62 of the block at a pair of opposing bottom wall niches 118. The bottom cover plate has an underside 114 and a top side 116 and is attached to the bottom wall niches with the top side facing into the loadlock chamber. Below the bottom cover plate, a heat lamp assembly 120 is attached to the block in a manner more fully described below.
Referring now primarily to FIGS. [0046] 4-7, the heat lamp assembly comprises a reflector 122 that is somewhat U-shaped when viewed in cross-section, with a lower reflector surface 124 and an upper reflector surface 125. The reflector further includes an outer encasement surface 126 and a circumferential mounting surface 128 (See FIG. 2) at the outer periphery of the U-shaped reflector. A mounting bracket 130 is attached to mounting surface 128, and the mounting brackets are secured to the bottom wall and the underside 116 of the bottom cover plate to fix the heat lamp assembly thereto.
An upper plurality of [0047] heat lamps 131 are attached to upper reflector surface 125 and a lower plurality of heat lamps 132 are attached to the upper reflector surface 124. The upper plurality and lower plurality radiate heat energy towards bottom cover plate 112. The upper and lower pluralities of heat lamps are arranged in concentric circles, with the upper plurality circle being outside the lower plurality circle. More specifically, the upper plurality 131 has an upper spacing d₁between each other. As best seen in FIGS. 6 and 7, the upper plurality illuminates with an intensity i₁and is oriented to establish a first focal plane 150 when illuminated. First focal plane 150 is located by an upper distance h₁from the upper plurality. Similarly, lower plurality of heat lamps 132 has a lower spacing d₂and illuminates with a lower intensity i₂to establish a second focal plane 152 at a lower distance h₂from lower plurality 132. Preferably, first focal plane 150 and a second focal plane 152 are coplanar with each other, and with a heating plane that is defined by wafer 32 when it is resting on lower flanges 144.
In an alternative embodiment, and referring now to FIG. 8, the [0048] heat lamp assembly 120′ can have a cylindrical configuration, with a flat bottom wall 127 and circular outer wall that terminated at mounting surface 128′, as shown in FIG. 8. For this configuration, a plurality of bar type lights 133, preferably the tungsten-halogen type commonly used in work lights), are mounted to surface 128, in a circular configuration. As discussed above, the lights 133 emit radiation which passes through the bottom cover plate and heats the wafer in a uniform manner.
In the preferred embodiment, the bottom cover plate is made of a material, such as quartz, which allows free passage of the radiation from the heat lamp assembly to pass therethrough into the loadlock chamber. This allows for more effective heating of the wafer during degassing operations. [0049]
The cluster tool of the present invention further includes a [0050] tray 134 which is attached to the top cover plate for accurately positioning the wafer within the loadlock chamber. The tray comprises a plurality of rails 136, 136, that are mounted to the top cover plate so that they extend vertically downward therefrom in a surrounding relationship with the bell portion 84. Each rail has an upper flange 138 and a lower flange 140 that project substantially perpendicularly from the rail, so that each rail has an inverted F-shape. The inverted F-shape establishes an upper flange horizontal surface 142 and a lower flange horizontal surface 144 for each rail.
The tray rails [0051] 136 extend downwardly into the loadlock chamber so that the upper flanges 138 of the trays are directly below the bell portion bottom surface 86. The lower flanges 140 are located directly above topside 114 of bottom cover plate 112. When a wafer is positioned at rest on the upper flange horizontal surfaces 142, the wafer defines a cooling plane that is immediately proximate bell portion bottom surface 86. When the wafer 32 is positioned at rest on the lower flange horizontal surfaces 144, the wafer is spaced-apart from bottom surface 86 and immediately above the bottom cover plate. As mentioned above, when in this position the wafer further defines a heating plane, and first focal plane 150 and second focal plane 152 are co-planar with this heating plane. In sum, the upper and lower flanges facilitate alignment of the wafer so that it can be selectively cooled and/or degassed within the loadlock chamber in an efficient manner.

OPERATION

To operate the cluster tool, [0052] front loader 24 transfers wafer 32 from a cassette module 30, (SMIF device or FOUP) to one of the loadlock chambers 18, 18 for processing. Initially, the wafer is placed on tray 134 within the loadlock chamber so that it rests on the lower flange horizontal surfaces 144, as shown in FIG. 3. The associated slot valve 22 for the loadlock chamber is closed, and the roughing pump 104 is stopped. Next, the roughing pump valve 110 is opened and the roughing pump is actuated to establish an initial vacuum, preferably on the order of 10⁻²to 10⁻³torr as indicated by a chamber vacuum gage 146.
As the roughing pump establishes an initial vacuum in the loadlock chamber, the wafer is simultaneously degassed by the [0053] heat lamp assembly 120. To do this, the upper plurality and lower plurality of lamps are activated and direct heat energy through the bottom cover plate to the wafer. This establishes a first focal plane 152 and second focal plane 154 which are co-extensive with a heating plane that is defined by wafer 32. As radiant energy is transferred to the wafer, the wafer becomes heated.
As the wafer is heated, entrained [0054] water molecules 148 in the wafer are released into the loadlock chamber, and the wafer becomes degassed. The structure of the holding means (the tray) allows the wafer to be degassed while within the loadlock chamber. Further, the degassing of the wafer is accomplished simultaneously with the establishment of an initial rough vacuum on the loadlock chamber. Thus, these features decrease overall processing time and increase the capacity of the cluster tool.
Once the initial vacuum is established on the loadlock chamber, the roughing pump valve is closed and the roughing pump is stopped. The adjacent [0055] high vacuum chamber 20 is placed in communication with the loadlock chamber that contains the wafer by opening a corresponding slot valve 22.
Referring to FIG. 4, as the slot valve opens; the high vacuum pump (which preferably operates continuously) draws remaining gas and water vapor molecules from the loadlock chamber through the slot valve opening. As the water molecules are drawn into the high vacuum chamber from the slot valve opening, they impinge directly onto the cryoplate face [0056] 76 of the water pump (which may also operates continuously), which is directly in front of the slot valve opening 74. As the water molecules contact the cryoplate, they freeze thereon because the cryoplate is maintained at a temperature at, or below, their freezing point at high vacuum conditions. The removal of water vapor molecules from the wafer while the wafer is still in the loadlock chamber reduces the “water load” for the cryopumps 41, 42 in the rear portion of the block and is one of the operative aspects of the invention.
After the wafer has been processed in the loadlock chamber as described above, the [0057] loadlock access valve 52 opens and the rear robot 46 transfers the wafer from the loadlock chamber to the vacuum processing pod(s) in the rear portion 16 of the block. As discussed above, the first and second rear cryopumps have established a high vacuum in the rear portion. Since the rear portion is under high vacuum conditions similar to that of the loadlock chamber, the wafer remains under a high vacuum as it is transferred from the loadlock chamber to the rear portion. The wafer may then be transferred to all or part of the processing pods according to a predetermined algorithm that is based on design requirements for the finished wafer.
After the wafer has undergone the last manufacturing procedure, the rear robot removes the processed wafer from the rear portion and places the wafer in the loadlock chamber on upper flange surfaces [0058] 142 of tray 134. Because the bell portion is refrigerated, and the platen is immediately proximate bottom surface 86, heat transfer from the wafer to the bell portion occurs and the wafer is cooled. Gas from platen gas supply system 100 is transported through the platen stem and escapes from the lower bell portion 84 onto the wafer, to further cool the wafer. Similarly, the vent valve 107 is opened and gas from chamber gas supply 103 is vented into the loadlock chamber, in order to raise the loadlock pressure to one atmosphere (P=1 atm). Because the loadlock chamber volume is minimized, less gas is required to vent the chamber, and the wafer is cooled and unloaded more quickly than prior art systems.
Once the wafer has cooled, [0059] front loader 24 removes the cooled wafer from the loadlock chamber and replaces the finished wafer in the cassette module, SMIF device or FOUP.
While the particular cluster tool, as herein shown and disclosed in detail, is fully capable of obtaining the objects and providing the advantages above stated, it is to be understood that the presently preferred embodiments are merely illustrative of the invention. As such, no limitations are intended other than as defined in the appended claims. [0060]

Claims

What is claimed is:

1. A device for processing a wafer comprising:

a block defining a chamber;

a platen extending through said block into said chamber;

a heat lamp assembly attached to said block opposite from said platen; and,

a plurality of wafer support structures for positioning said wafer between said platen and said heat lamps.

2. The device of claim 1 wherein each said wafer support structure further comprises:

a tine having an upper flange and a lower flange; and,

said upper flanges defining a cooling plane.

3. The device of claim 2 wherein said cooling plane is immediately proximate said platen.

4. The device of claim 2 wherein said lower flanges define a heating plane, said heating plane being located between said upper flanges and said heat lamp assembly.

5. The device of claim 1 wherein said heat lamp assembly further comprises:

a curved reflector mounted to said block;

a first plurality of heat lamps mounted to said reflector and being oriented for illumination into said chamber; and,

a second plurality of heat lamps mounted to said reflector and being oriented for illumination into said chamber.

6. The device of claim 5 wherein said first plurality has a first spacing for establishing a first plane of uniform radiation intensity in said chamber, said first plane being co-planar with said heating plane.

7. The device of claim 6 wherein said second plurality has a second spacing for establishing a second plane of uniform radiation intensity in said chamber, said second plane being co-planar with said first plane.

8. The device of claim 1 further comprising:

a cylindrical reflector mounted to said block;

a plurality of elongated heat lamps mounted within said reflector and oriented for illumination into said chamber; and

9. The device of claim 1 wherein said platen has a gas supply line extending internally therethrough, said gas supply line having a first end connected to a pressurized gas source, and further having a second end in fluid communication with said chamber.

10. An apparatus for processing a wafer comprising;

a block having a chamber defined by a top wall, a bottom wall, and a plurality of side walls;

a platen mounted to said block and having a flat surface located within said chamber;

a heat lamp assembly mounted to said block and arranged to direct radiation toward said wafer; and,

a holding means for selectively supporting a wafer in said chamber immediately proximate said flat surface and said bottom wall.

11. The apparatus of claim 10 wherein said holding means further comprises a plurality of vertical rails attached to said block in a surrounding relationship with said platen, each rail having an upper flange and a lower flange that projects outwardly from said rail.

12. The apparatus of claim 11 wherein said wafer defines an upper position when resting on said upper flanges and said wafer is parallel to said flat surface when in said upper position.

13. The apparatus of claim 11 wherein said wafer further defines a lower position when resting on said lower flanges, said lower position being located between said upper position and said heat lamp assembly.

14. The apparatus of claim 13 wherein said bottom wall allows for illumination therethrough, and said heat lamp assembly further comprises:

a curved reflector mounted to said bottom wall;

a first plurality of heat lamps mounted to said reflector and being oriented for illumination through said bottom wall and into said chamber; and,

a second plurality of heat lamps mounted to said reflector and being oriented for illumination through said bottom wall and into said chamber.

15. The apparatus of claim 14 wherein said first plurality has a first spacing for establishing a first plane of uniform radiation intensity in said chamber, said first plane being co-planar with said lower plane.

16. The apparatus of claim 15 wherein said second plurality has a second spacing for establishing a second plane of uniform radiation intensity in said chamber, said second plane being co-planar with said first plane.

17. The apparatus of claim 10 further comprising a cooling system in thermal communication with said platen.

18. The apparatus of claim 10 wherein said platen has a gas supply line extending internally therethrough, said gas supply line having a first end connected to a pressurized gas source, and further having a second end in fluid communication with said chamber.

19. A method for cooling and degassing a wafer which comprises the steps of:

A) providing a block;

B) defining a chamber within said block;

C) mounting a platen to said block so that said platen extends through said block into said chamber;

D) attaching a heat lamp assembly to said block opposite from said platen;

E) arranging a plurality of wafer support structures around said platen and within said chamber, each wafer support structure having an upper flange and a lower flange extending from a tine, said upper flanges and said lower flanges being located between said platen and said heat lamp assembly; and,

F) selectively positioning said wafer on said upper flanges to cool said wafer within said chamber.

20. The method of claim 19 further comprising the steps of:

G) placing said wafer on said lower flanges; and,

H) illuminating said heat lamp assembly.