APPARATUS AND METHOD ESPECIALLY FOR DEGASSING OF SUBSTRATES

Abstract

A heater or cooler vacuum chamber for degassing includes an enclosure and within the enclosure a controllably heatable or coolable pocket. Within the pocket is a workpiece holder and a gas feedline discharging the pocket. The inner surface of the pocket surrounds the workpiece in a closely spaced manner. The two halves forming the pocket may be controllably separate so as to allow a gas flow connection which establishes a negligible gas flow restriction to the remainder of the enclosure.

Claims

1. A heater and/or cooler vacuum chamber, for at least one workpiece, preferably a single workpiece, especially a degasser chamber, comprising: an enclosure enclosing an enclosure volume; within said enclosure volume, a controllably heatable and/or coolable pocket enclosing a pocket volume; a workpiece holder in said pocket volume a gas feedline discharging in said pocket volume a port from the surrounding of said enclosure into said enclosure volume; wherein: a) the inner surface of said pocket is tailored to surround said workpiece applied on said workpiece holder in a closely spaced manner, distant from said workpiece b) said pocket comprises a controllably closable and openable gas flow connection from the pocket volume into the remainder said enclosure volume, said gas flow connection representing, in open state, a negligible gas flow restriction.

2. The chamber of claim 1 wherein said pocket comprises two mutually controllably joinable and separable parts, separated through said pocket volume.

3. The chamber of claim 2 for a plate shaped workpiece, wherein said parts are separable perpendicularly to the extended surfaces of said plate shaped workpiece on said workpiece holder, preferably adjacent the periphery of said plate shaped workpiece.

4. The chamber of claim 2 only one of said parts comprising a heater and/or cooler, preferably a two-zone heater.

5. The chamber of claim 4 wherein said one part has a thermal mass which is substantially smaller than the thermal mass of the other part of said two parts.

6. The chamber of claim 2 wherein said workpiece on said workpiece holder is more distant from at least one of said parts, preferably from both of said parts, in open state of said pocket than in closed state.

7. The chamber of claim 1 wherein said pocket is substantially thermally decoupled from said enclosure.

8. The chamber of claim 2 wherein one part of said pocket is a part of the wall of said enclosure.

9. The chamber of claim 2 wherein the parts are separable by at least 50 mm.

10. The chamber of claim 1 wherein a ratio of the enclosure volume to the pocket volume is at least 10, preferably at least 30, preferably at least 35.

11. The chamber of claim 1 wherein said enclosure comprises cooling means and/or heating means for said enclosure volume, preferably a water cooling and/or heating arrangement.

12. The chamber of claim 2 wherein at least one part of the pocket is movably linked to said enclosure by means of a bellow, said gas feed line being arranged within said bellow, towards and into said pocket volume.

13. A heater and/or cooler apparatus comprising a chamber according to claim 1 and comprising a gas reservoir operationally connected to said gas feed line and preferably containing at least one of Ar, N.sub.2, He.

14. The apparatus of claim 13 comprising a vacuum pump operationally connected to said port of said chamber.

15. A method of manufacturing at least one heated or cooled workpiece, especially of a single workpiece, especially of at least one degassed workpiece, comprising the steps of: providing a workpiece on a workpiece holder at a vacuum pressure enclosing said workpiece on said workpiece holder in a pocket and in a closely spaced manner at said vacuum pressure pressurizing the volume containing said workpiece in said pocket with a gas to a first pressure higher than said vacuum pressure; heating or cooling said pocket before and/or during said enclosing and said pressurizing step establishing or maintaining in an enclosure volume surrounding said pocket a second pressure substantially lower than said first pressure wide opening said pocket towards said enclosure volume at least one of before and of after said enclosing, said enclosure volume being substantially larger than said volume of said pocket containing said workpiece and as pressurized.

16. The method of claim 15 comprising pumping gas from said enclosure volume at least one of before said enclosing, of during said enclosing and of after said wide opening.

17. The method of claim 15 comprising pressurizing said volume with He to at least 10 mbar (1000 Pa).

18. The method of claim 15, said wide opening comprising separating two parts of said pocket through said volume of said pocked containing said workpiece, said heating or cooling comprising preferably heating or cooling of at least the one of said parts, preferably of just one of said parts, and preferably selecting the thermal mass of said one part substantially smaller than the thermal mass of the other of said parts, and, preferably, thermally coupling said one part substantially less to said enclosure than to the other of said parts during said heating or cooling, and, preferably, maintaining said workpiece substantially closer to the one of said parts during said heating or cooling than after wide opening.

19. The method of claim 15 said enclosure being heated or cooled, preferably cooled.

20. The method of claim 15 for manufacturing at least one degassed workpiece.

21. The method of claim 15 for manufacturing at least one thermally treated substrate.

Description

[0063] The invention shall now further be exemplified with help of figures. The figures show:

[0064] FIG. 1 schematically and simplified an embodiment of the chamber in a split display, showing the chamber in two positions, and of the apparatus according to the invention, especially for workpiece-degassing, substantially according to an actual realisation.

[0065] FIG. 2 the dependences of gas related heat transfer versus pressure in a 1 mm gas gap for two gases, namely Ar and He.

[0066] FIG. 3 schematically and simplified, an example of a degasser design according to the invention and operating the method according to the invention in a first, closed, position,

[0067] FIG. 4 the degasser of FIG. 3 in a second, opened, position.

DETAILED DESCRIPTION OF THE INVENTION

[0068] FIGS. 3 and 4 show an example of a degasser design according to the invention with closed and opened inner chamber or pocket 1. The degasser comprises an outer housing 3 with an inner, heatable pocket 1 for the substrate 5 to be treated. The inner enclosure, the pocket 1, is designed like a clam with an upper 1a and a lower 1b shell which can be separated or closed as shown in FIGS. 3 and 4. The clam or pocket 1 is optimized to receive and support a substrate 5, such as a wafer or a composite substrate (fan-out substrate) with only little surrounding space when in closed state. The lower shell 1b may exhibit pins, ball-shaped supports or a contoured surface with means to support a substrate to be treated.

[0069] The upper 1a or the lower 1b shell may be fixedly mounted to the outer housing 3, thus leaving only the other shell as movable part. Of course one may realize the degasser according to the invention also as a clam, i.e. pocket 1, with both shells 1a, 1b, as parts of the pocket 1, being movable.

[0070] Upper and/or lower shell 1a, 1b shall include means for introducing a working gas such as Ar, N.sub.2 or He into the gap to enhance the heat transfer.

[0071] When closed, the upper and lower shells 1a, 1b envelop a certain volume. The contact area of upper and lower shell 1a, 1b may be sealed, e.g. by a Viton O-ring. Alternatively the edges where upper and lower shells 1a, 1b meet may be construed to be not thoroughly gas tightthey allow a certain amount of gas to evade from the gap formed by the clam. Depending on the type of substrates 5 to be treated, one may foresee even additional openings like feedthroughs to allow more leaking of gas. It has to be noted that a flush of gas is not the goal of these leaks, since the thermal transport is accomplished by the gas remaining in the volume. However, outgassing molecules and excess gas may have a defined path to evade. The man skilled in the art will in this case limit the supply of gas to the lowest possible flow needed.

[0072] The shells 1a, 1b are being machined from a material with good thermal capacity and/or conductance so they can buffer and/or transfer heat. They may both be heated e.g. electrically, preferably constantly so the shells 1a, 1b allow to rapidly release heat to a substrate 5 freshly inserted into the clam, i.e. pocket 1. Access ports for the substrate to be degassed and pump exhausts are not shown in FIGS. 3 and 4.

[0073] In a preferred embodiment the upper shell 1a will not be actively heated but exhibit a large thermal mass. Preferably this will be the one fixedly mounted to the top of the outer enclosure 3 via insulating posts. The large thermal mass will provide a reservoir of heat for any freshly inserted substrate 5 and will at the same time absorb any excess heat provided by the lower, heated shell 1b. After opening the clam, i.e. pocket 1, and thus separating the clam, the upper, hot shell 1a will be far more distant than before and thus immediately be less actively heating the substrate 5 as before. If it is the goal of allowing a rapid heat-up AND cool down, one may choose a material with low thermal mass for the lower (heated) shell 1b thus supporting the cool down as soon as the clam 1 is being opened. A man skilled in the art will add heat reflectors or shields as appropriate or necessary for the processes to be performed.

[0074] An inventive heat-up and degas process will comprise at least the following steps: [0075] 1) Opening the inner enclosure in the outer housing to accept a substrate [0076] 2) Inserting a substrate into the degasser, e.g. by means of a handler or a robot with appropriate transporting means (gripper, fork, [0077] 3) Placing the substrate on the lower part of the clam (lower shell) or moving the lower shell upwards so as to lift the substrate of the handler. [0078] 4) Removing the handler from the clam [0079] 5) Closing the shell. [0080] 6) Introducing the working gas for heat transfer. [0081] 7) As soon as the substrate has reached the desired temperature the clam is being opened [0082] 8) The outgassing molecules evade into the outer housing and thus can be pumped away very effectively via the enlarged pumping profile/pumping cross-section.

[0083] Heating the upper and lower shell 1a, 1b can be accomplished by a constant feed of power to the clam, the heat dissipating to the substrate 5 will be supplied during the load/unload times of a substrate and/or idle times. It goes without saying that applying a power profile with enhanced heating during actual operation is also possible. The man skilled in the art will realize this according to the need of the substrate to be heated.

[0084] An actual embodiment of the invention could looks like that:

[0085] The inner chamber 7 (gap of the clam) has a height of 3 mm and a diameter of 320 mm. Its volume is 241 cm.sup.3 without the Si wafer (substrate). The outer chamber 3 with an inner height of 100 mm and a diameter of 400 mm has, after subtracting the outer dimensions of the inner chamber (40 mm height, diameter 360 mm) a volume of 8494 cm.sup.3. By opening the inner chamber 1 the gas which has been used to fill up the inner chamber is expanding to a volume, which is 35 times higher. This pressure burst can easily be taken up by the high vacuum pumps connected to the outer chamber.

[0086] Material which has to be outgassed from the substrate can be pumped out easily if a wide gap 7a is provided as shown in FIG. 4 with 51 mm. In high vacuum the outgassing material is in the molecular flow regime and follows the path of direct sight, as indicated by the dotted lines E in FIG. 4. The substrate 5 will also cool down due to radiation to the water-cooled walls of the outer chamber 3. This additional effect, also indicated by the dotted lines E in FIG. 4, is wanted and also requires a wide open gap 7a of the inner chamber, i.e. pocket 1.

[0087] FIG. 1 shows an embodiment closer to the actual realization in a split-display. The left part of the figure addresses the closed clam state where the vacuum pump 9 (turbo) is acting mainly on the volume of the outer housing 3 while the gas is being fed11via the lower shell 1b. A pressure sensor 15 may allow controlling the actual pressure inside the clam's gap 7, 7a. A pyrometer 13 can be installed to control the temperature of the substrate 5. FIG. 1 shows the substrate being placed on hooks inside the clam. The left side of FIG. 1 mentions a gate valve 17 establishing a sealable interface to further enclosure which will house an outside handler usable for the load/unload of substrates.

[0088] FIG. 2 shows the dependencies of the gas related heat transfer vs. pressure in a 1 mm gas gap for two gases such as Ar and He. One can learn that increasing the Ar pressure in such a 1 mm gap from 100 to 1000 Pa will not considerably enhance the heat transfer. Using He instead of Ar will allow to have a heat transfer at least 3 higher at 100 Pa and even more than 6 higher at 1000 Pa.

[0089] The degasser can be used also as a pure heating station, since the inventive clam inside an outer enclosure will also serve its purpose with a non-degassing substrate. In reverse the same structure can provide heat transfer in the other direction, as a cooling station, where a substrate can be effectively cooled in a clam within a larger enclosure.

[0090] For both pure heating and pure cooling as well as degassing embodiments is valid that the small volume useful for gas-related heat transfer in the gap of the clam is being mechanically expanded to a larger volume allowing for quick removal of the working gases. Whether additional outgassing material is part of the removed gases, is relevant only for the time the substrate remains in the opened lower shell after the heat transfer treatment. The criterion for the transport to a next process station will be the residual pressure in the outer housing and/or the temperature of the substrate.

TECHNICAL FEATURES IN SUMMARY

[0091] A degasser setup including:

[0092] 1. A pocket (clam) to accept a substrate inside a vacuum enclosure.

[0093] 2. A minimal volume inside this clam surrounding the substrate to enable a fast gas fill and a fast pump out.

[0094] 3. The substrate is placed in the middle of top and bottom plates (shells) of the clam.

[0095] 4. The substrate is placed on 3 balls in the bottom plate to minimize the contact of the substrate to the plate and to allow its relaxation during heat-up

[0096] 5. The clam comprises a heated bottom plate (lower shell) with a 2-zone heater

[0097] 6. Thermally decoupling the heated bottom plate from a base plate to thermally decouple it from the chamber.

[0098] 7. The clam having optionally an unheated top plate, which has a certain thermal mass to store heat, but is otherwise decoupled thermally from the chamber

[0099] 8. The clam being able to be opened up to at least 50 mm to enable a high pumping speed for outgassing material.

[0100] 9. The volume of the outer chamber being at least 10 times higher than the volume of the inner chamber, preferably >30 or even >35 times higher

[0101] 10. The walls of the outer chamber being water-cooled and directed towards the substrate to enable heat exchange by radiation

[0102] 11. The setup can be used in almost the same design as a cooler, where the heater plate in the bottom plate is replaced by a water-cooled plate.

[0103] A method to use a clam degasser according to the invention:

[0104] 1. The top plate is heated up in clam closed position preferably filled with He up to 10 mbar (1000 Pa), during conditioning of the module

[0105] 2. The degas process consists of 2 steps:

[0106] 3. Heat up with closed clam

[0107] 4. Degas with open clam

[0108] 5. For the heat up the clam is filled with gas up to 10 mbar, preferably with He

[0109] For the degassing step the clam is opened as much as possible providing a very direct path of the outgassing material to the pumps.