JP2017218360A - Production method of regenerated silicon member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a regenerated silicon member more quickly and easily with less energy.SOLUTION: A production method of a regenerated silicon member includes steps for: (1) placing a foil 2 of a metal forming eutectoid with silicon on the surface of a used silicon member 1, and placing another silicon member 3 of the foil 2; (2) generating a metal melt containing silicon by heating from the upper side of placed another silicon member 3; and (3) bonding the used silicon member 1 to another silicon member 3 by solidifying the metal melt containing silicon.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a recycled silicon member, and more particularly to a method for manufacturing a recycled silicon member by joining another silicon member to a used silicon member via a metal foil.

  As an etching apparatus in manufacturing a semiconductor integrated device such as an LSI, a dry etching apparatus using plasma is used. In this apparatus, when a wafer to be etched is placed on the cathode of the planar electrode and an etching gas is introduced into the apparatus, a high frequency voltage is applied between the counter electrode (anode) and the cathode by a high frequency oscillator. Etching gas plasma is generated between the electrodes. Etching is performed when positive ions, which are active gases in the plasma, are incident on the wafer surface.

  Inside the dry etching apparatus, if metal parts are used, metal contamination occurs, so silicon parts are used. Typical silicon parts include a donut-shaped focus ring surrounding the wafer to be etched, a ground ring surrounding the lower electrode, an upper electrode plate, and protective members above and below the etching chamber. Of these, the focus ring or the like needs to have a larger diameter than the wafer to be etched, and the current mainstream one for 300 mm wafers is made from a silicon crystal ingot having a diameter of 320 mm or more, which is expensive. . As these silicon parts are used, the surface is gradually etched and thinned. When the thickness becomes thinner than a certain level, it is discarded as scrap silicon, and a method for reusing it has been demanded.

  As a method of regenerating the focus ring, etc., clean silicon waste, measure the content of impurities, determine the silicon materials and impurities to be added, and then melt them in a crucible to prepare a polycrystalline silicon ingot However, a method for manufacturing a new focus ring or the like has been proposed (Patent Document 1). Also, a method has been proposed in which one of the two used focus rings is provided with a convex step by machining, and a concave step is provided on the other, and the two pieces are overlapped and reproduced as a combined focus ring. (Patent Document 2).

JP 2013-16532 A Japanese Patent Laid-Open No. 2004-79983

  However, since the method described in Patent Document 1 melts the entire silicon waste material, it requires a great deal of energy and time and costs. The method described in Patent Document 2 is troublesome because both of the two used focus rings are machined, and only one of the two waste materials can be regenerated.

  Accordingly, an object of the present invention is to provide a method capable of manufacturing a recycled silicon member more quickly and easily with less energy.

That is, the present invention is as follows.
[1] (1) A process of placing a metal foil that forms a eutectic with silicon on the surface of a used silicon member, and placing another silicon member on the foil;
(2) A step of heating from the upper side of the placed other silicon member to generate a melt of the metal containing silicon,
(3) solidifying the silicon-containing metal melt, and joining the used silicon member and the another silicon member;
The manufacturing method of the reproduction | regeneration silicon | silicone member containing this.
[2] The method according to [1], wherein the metal is any one of Al, Ga, Ge, and Sn.
[3] The method according to [1] or [2], wherein the foil has a thickness of 0.1 to 100 μm.
[4] The method according to any one of [1] to [3], wherein in the step (2), the heating is performed by light heating.
[5] The method according to [4], wherein the light heating is performed by a xenon lamp or a halogen lamp.
[6] The method according to [4] or [5], wherein the step (2) is performed while scanning the surface of the another silicon member with the condensed light.
[7] The method according to any one of [1] to [6], wherein the used silicon member is a focus ring, a ground ring, or an electrode plate of a dry etching apparatus.

  The method for producing a recycled silicon member of the present invention can rapidly produce a recycled silicon member with less energy than a method for melting the entire silicon waste material. Moreover, since it is only necessary to place and heat a metal foil between silicon members, it is simpler than machining. This makes it possible to reuse silicon members that have been discarded as waste silicon, leading to a reduction in the cost of consumables.

It is a schematic sectional drawing of an example of the apparatus for enforcing the method of this invention. FIG. 2A is a front view of a ring-shaped used silicon member 1 having an L-shaped cross section, on which a plurality of other fan-shaped silicon members 3 are mounted, and FIG. 2B is a partial perspective view thereof. is there. It is a schematic sectional drawing of the other example of the apparatus for enforcing the method of this invention.

The method for producing a recycled silicon member of the present invention includes the following steps.
(1) placing a metal foil that forms a eutectic with silicon on the surface of a used silicon member, and placing another silicon member on the foil;
(2) A step of heating from the upper side of the placed other silicon member to generate a melt of the metal containing silicon,
(3) A step of solidifying the silicon-containing metal melt and joining the used silicon member and the another silicon member.

  In the step (1), the used silicon member (hereinafter sometimes referred to as “used member”) may be single crystal or polycrystalline, and its manufacturing method, purity, crystal orientation, shape, etc. may be arbitrary. Examples of the used member in the dry etching apparatus include a focus ring, a ground ring, and an electrode plate.

  A used member in a dry etching apparatus may have a roughened surface due to etching and may be contaminated with a contaminant such as metal. For this reason, prior to the regeneration, it is preferable to perform a grinding process or the like so that a gap is not generated on the joint surface with another silicon member (hereinafter, also referred to as “another member”). There is no problem as long as the surface of the processed surface is a ground surface, but it is possible to polish it with about 1000 abrasive grains such as alumina. The bonding surface may be a mirror surface by buffing or the like, but it can be sufficiently bonded by a ground surface or a polished surface. Contamination generated after grinding or polishing can be removed by etching the surface with a mixed solution of hydrofluoric acid and nitric acid. As the mixed solution, a chemical polishing solution (hydrofluoric acid (49%): nitric acid (70%): acetic acid (100%) = 3: 5: 3) defined in JIS standard H0609 can be used.

  Examples of the metal that forms a eutectic with silicon include Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi, Ag, and Au. Among these, since the diffusion coefficient in the silicon crystal is low, the diffusion in the used member is small, the deep level that is electrically problematic is difficult to make, and there is no problem to the environment, Al, Ga, Ge, and Sn are preferable, and Al is most preferable in that it is inexpensive. The purity of the metal is not particularly limited as long as a eutectic can be formed, and is preferably 98% or more. The eutectic may be included in at least a part of the joint portion between the used member and the separate member, and the entire joint portion does not need to be made of the eutectic.

  In the present invention, the metal foil (hereinafter sometimes referred to as “metal foil”) is used. Although it is considered possible to join a used member and another member using metal powder or particles, a foil is preferable in that it can be easily placed at a uniform concentration on the surface of the used member. . In the case of a low-melting-point metal such as In or Ga, a film obtained by directly applying a melt of the metal to the joint surface of a used member and / or another member may be replaced with a foil. Therefore, in the present specification, the “metal foil” includes a metal film. The thickness of the metal foil is preferably thin in that less energy is required for melting, but is preferably 0.1 to 100 μm, and preferably 0.5 to 20 μm in order to obtain bonding strength. More preferred. If it is thinner than the above lower limit value, it tends to be damaged when a metal foil is placed on the joint surface, and in the case of a film, there may be a portion where the metal amount is insufficient. On the other hand, if it is thicker than the above upper limit value, a portion where bonding with silicon is not sufficient is likely to occur.

  After joining the used member and the separate member, it is preferable to melt the silicon at the end of the used member and / or the separate member so that the joint including the metal-silicon eutectic is not visible from the outside. Normally, when the silicon at the end is melted, the molten silicon penetrates into the groove between the used member and another member by about several millimeters, so the size of the metal foil is so that the molten silicon does not contact the joint. The size is preferably a few mm away from the end.

  The separate member may be either single crystal or polycrystalline. Moreover, although the thickness is adjusted depending on the thickness of the silicon targeted for regeneration, it is preferably 1 mm to 50 mm. Since the eutectic temperature of silicon and aluminum is sufficiently lower than the melting point of silicon, even relatively thick materials can be heated and bonded from above, but if the upper limit is exceeded, the metal foil is heated sufficiently Therefore, it becomes difficult to melt and it takes some time to form the eutectic. On the other hand, if the thickness is less than the lower limit, another member may move due to the flow of argon gas for adjusting the atmosphere during heating.

  The place where the separate member is placed is on the surface of the place where it is desired to regenerate the used member, and may be a specific place or the entire face. For example, FIG. 2 shows a mounting form of another member when a ring-shaped member having an L-shaped cross section is reproduced in Example 4 described later. FIG. 2A is a front view of a ring-shaped used member 1 having an L-shaped cross section on which a plurality of separate members 3a and 3c are placed, and FIG. 2B is a partial perspective view thereof. A metal foil 2 (not shown) is placed between the used member 1 and the separate members 3a to 3c.

  Preferably, when mounting a plurality of separate members, the separate members are mounted so that there is no gap as much as possible. And as a finishing process of the reclaimed member, as in the case of the melting at the end face of the reclaimed member, the end surface of each separate member and the surface of the used member underneath are heated to melt, It is preferable to close the gap.

  In the step (2), the heating method is not particularly limited, and can be performed by resistance heating, light heating, or the like. Preferably, light heating is used in that the heating part can be easily moved and the amount of heating can be easily changed in accordance with the supplied power. For example, various lamps and lasers are used. As the lamp, a xenon lamp or a halogen lamp generally used in an infrared crystal growth apparatus can be used. The output is preferably about 1 to 30 kW.

  Heating is performed from the upper side of another member. What is necessary is just to be an upper side, and it is not limited to the upper side in the vertical direction with respect to another member, and may be from the upper side. For example, even when the metal foil 2 is placed in the vertical direction along the wall surface of the L-shaped cross section as in the form shown in FIG. 2B, the heating is performed from an oblique direction inclined about 30 degrees from the vertical direction. There was no problem. Although not intended to limit the present invention, in the method of the present invention, the metal foil is first melted by heating to form a melt of the metal. Next, the surface of the used member and another member in contact with the melt is attacked by the metal melt, and a metal melt containing silicon is generated. When heating is stopped and the temperature is lowered, the melt is solidified while forming an alloy phase containing a eutectic, and it is considered that the joining is completed. For example, when an aluminum foil was used, the used member and the separate member could be sufficiently joined by heating up to about 800 ° C. The amount of erosion eroded by the metal melt on the surfaces of the used member and the separate member is considered to be approximately the same as the thickness of the metal foil.

  In the case of using the xenon lamp or the like, it is preferable to collect light using a light collecting means such as an elliptical mirror. At this time, the heating power may be increased by overlapping and condensing a plurality or types of heating means. The condensing region is usually about 10 to 30 mm in diameter, but by shifting the light emission position of the lamp from the focal point of the elliptical mirror, the condensing region can be expanded to about 30 to 100 mm and the heating range can be expanded. . Furthermore, it is preferable to heat the condensing region by scanning the entire surface of the metal foil and another member.

  The heating time varies depending on the output of the heating means, the thickness of another member, etc., but in the case of the combination of the 11 μm aluminum foil used in Example 1 described later and another member of about 121 × 60 × 5 mm, about 1 to 5 minutes. Met.

  In the step (3), the metal melt containing silicon is solidified by cooling to form a joint including the metal-silicon eutectic, and the used member and another member are joined. For example, when the metal is Al, when it is cooled to about 577 ° C., a joint containing an Al—silicon eutectic (12.2 atomic% Al) is formed. The cooling rate varies depending on the metal used, but when using Al, it is preferable to control the cooling rate to be 100 to 10 ° C./min. If the speed is less than the lower limit, the cooling time becomes long and the regeneration efficiency is poor. If it is larger than the upper limit, strain tends to remain in the joint. The cooling rate is such that after the melting of the metal foil is completed, the output of the heating means is gradually decreased, and the heating is stopped when it is estimated that the temperature of the joint is lower than the melting temperature of the eutectic. Can be controlled by. For such control of the heating temperature, for example, a thermocouple is installed between silicon members having the same shape as that actually bonded, the relationship between the power and temperature of the heating means is measured in advance, and the measurement result is Can be done.

  Steps (2) and (3) are preferably performed in a chamber having an argon atmosphere of 10 to 200 torr (about 1333 to 26664 Pa) in order to prevent oxidation of metal and silicon. Oxidation can be prevented by reducing the pressure without using argon gas. However, if the pressure is reduced, the evaporation of silicon occurs and the inside of the chamber may become dirty, which is not preferable. Nitrogen gas can also prevent oxidation, but is not desirable because silicon nitridation occurs at 1200 ° C. or higher.

  FIG. 1 is a schematic sectional view of an example of an apparatus for carrying out the method of the present invention. In the figure, a metal foil 2 that forms a eutectic with silicon on the used member 1 is placed on the metal foil 2, and another member 3 is placed on the metal foil 2. From the upper side of the separate member 3, the used member 1 and the separate member 3 are joined by heating by the heating unit 4 such as a xenon lamp condensed by the light collecting unit 5.

  FIG. 3 is a schematic cross-sectional view of another example of an apparatus for carrying out the method of the present invention. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the apparatus, heating is performed while rotating the used member 1 in the chamber 6 so that light scans the surfaces of the plurality of separate members 3. Argon gas is supplied in the direction indicated by the arrow from an argon gas inlet 8 to which a gas cylinder (not shown) or the like is connected, and is discharged by an exhaust pump 10.

  A quartz window 7 is provided in the chamber 6, and light from the heating means 4 is irradiated to another member 3 through the quartz window 7, and the used member 1 and the like are rotated by a turntable 9 rotated by a motor 11. It rotates at a constant speed so that the condensing region of the heating means 4 scans on the surface of the separate member 3. The scanning speed varies depending on the metal used and the output of the heating means 4, but it is preferable to adjust the scanning speed so that a metal melt containing metal and / or silicon is always present in the light collection region. If the condensing region is moved to a part where the melt is not present at all because the scanning is too fast, the metal is not sufficiently melted. On the other hand, if it is too slow, the reproduction efficiency will deteriorate. For example, in Example 1 described later, the ring-shaped used member 1 having an outer diameter of 390 mm, an inner diameter of 330 mm, and a thickness of 5 mm was rotated at an angular velocity of 10 degrees / minute.

  The turntable 9 is disposed on the X, Y-stage 12. The X, Y-stage 12 may be used to move the used member 1 or the like in the X, Y-direction while rotating it so that the condensing region scans in the same direction.

  As described above, when the used member 1 is locally heated, distortion may occur in the used member 1 due to a temperature difference between the heating region and a portion adjacent to the heated region, which may cause poor bonding with the metal. In the apparatus shown in FIG. 3, in order to alleviate this temperature difference, the entire used member 1 can be heated from below by the auxiliary heating means 13 to a temperature lower than the melting point of the metal, for example, 400 to 550 ° C. in the case of Al. it can. The auxiliary heating is started prior to the start of heating for melting the metal, and after the used member 1 reaches a predetermined temperature, heating for melting the metal is started. In step (3), after the heating for melting is stopped, that is, after the heating means 4 is turned off, the auxiliary heating means 13 is turned off. As the auxiliary heating means 13, a general resistance heater using a heating wire such as Kanthal (iron-chromium aluminum alloy) or a ceramic such as SiC can be used. In FIG. 3, the auxiliary heating means 13 is provided at a location corresponding to the light collection region, but is not limited thereto, and may be another location.

  As the heating zone moves, the temperature of the melt in the portion past the heating zone gradually decreases and begins to solidify. When the last metal foil 2 on the used member 1 has been melted, the heating temperature is lowered. The cooling rate of the joint at this time is as described above. The rotation of the used member 1 is continued while the output of the heating unit 4 is reduced, and the auxiliary heating unit 13 is turned off after the heating unit 4 is turned off. To do.

The recycled member obtained by the above method can be used as it is, but is preferably polished. The method of polishing is not particularly limited, and a conventional method such as lapping or buffing may be used.
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this Example.

  Using an apparatus as shown in FIG. 3, an aluminum foil 2 (thickness: 17 μm) is placed on the surface of a ring-shaped used member 1 having an outer diameter of 390 mm, an inner diameter of 330 mm, and a thickness of 5 mm used in a dry etching apparatus. Then, ten silicon plates (separate member 3) having an outer chord length of 123 mm, an inner chord length of 104 mm, and a thickness of about 5 mm were joined and regenerated into a ring-shaped member having a thickness of about 10 mm.

As a pre-treatment, when the joined surface of the used member 1 is polished with No. 2000 SiC polishing paper and another member 3 having a flat surface is placed, the area between the used member 1 and the other member 3 is 1 cm. ² and a height of 50 μm or more were prevented. The other member 3 was subjected to surface polishing with alumina No. 2000 abrasive grains. After polishing each material, the polishing debris was washed away with pure water, the surface was washed with a clean room wiper (manufactured by Toray Industries Inc.) containing ethanol (electronic industry grade), and then dried. After the used member 1 was placed on the turntable 9, an aluminum foil 2 (Mitsubishi Aluminum) having a thickness of 17 μm was spread on the upper surface of the used member 1. Ten separate members 3 are installed on the aluminum foil 2 with almost no gap, the inside of the chamber 6 is evacuated, and an argon gas is flowed at 5 L / min, so that the inside of the chamber 6 is about 100 torr (13332 Pa) of argon. A gas atmosphere was used.

The maximum temperature of the lower surface of the used member 1 before the heating means 4 is irradiated from the lower part of the used member 1 by a cantal heater 13 (manufactured by Sakaguchi Electric Heat Co., Ltd.) installed in the chamber 6. Was heated to 400 ° C. Next, a 5 kW xenon lamp (manufactured by USHIO INC., Hereinafter referred to as “lamp”) was used as the heating means 4, and an elliptical mirror was used as the light collecting means 5. By shifting the position of the light emitting part of the lamp from the focal position of the mirror, the spread of light at the irradiation position was adjusted so that a range of about 50 mm in diameter could be irradiated. The power of the lamp was set so that the temperature at the portion where the used member 1 and the separate member 3 were joined became 800 ° C. at the irradiated portion of the lamp. This power was determined in advance from measurement using a dummy member sandwiching a thermocouple. After maintaining the power of the lamp for 3 minutes, the rotating table 9 starts to rotate at 10 degrees / minute while maintaining the power, and after rotating once, the power is reduced and the temperature is lowered to 400 ° C. in 10 minutes. The power was turned off in the order of the heater.
When the cross section of the obtained recycled member was cut out and observed with a microscope, the metallic luster of aluminum was not seen, and almost all the aluminum reacted with silicon to form an alloy phase containing eutectic and separated from the used member 1 It was confirmed that the member 3 was joined.

A ring-shaped recycled silicon member was regenerated by the same method as in Example 1 except that the thickness of the aluminum foil was changed to 15 μm.
When the cross section of the obtained recycled member was cut out and observed with a microscope, the metallic luster of aluminum was not seen, and almost all the aluminum reacted with silicon to form an alloy phase containing eutectic and separated from the used member 1 It was confirmed that the member 3 was joined.

The groove remaining between the different members 3 of the recycled silicon member prepared in Example 1 was closed by melting silicon.
Adjust the lamp position so that the focal position of the mirror matches the position of the light emitting part of the lamp, and adjust the height of the upper surface of the reclaimed silicon member so that it becomes another focal position of the mirror. The width of the condensing part was about 3 mm. In this state, when the power of the lamp is increased by aligning the light collecting portion with the groove position, the surface begins to melt at 60% of the lamp rating (surface temperature is estimated to be 1420 ° C.), and the groove is filled at 90% of the lamp rating. Molten silicon flowed in and closed a part of the groove. In this state, the condensing part was scanned along the groove at a speed of 5 mm / min from end to end of the groove, thereby filling the groove with molten silicon and closing the groove. After that, the melted silicon starts to harden. The lamp power is lowered to 55% of the lamp rating in 2 minutes and held in that state for 5 minutes. Then, the turntable 9 is rotated to melt the adjacent groove in the same manner. All the grooves were plugged.
After the obtained recycled member was cooled, the groove portion was observed with a microscope, and it was confirmed that no crack was generated and the groove was completely blocked.

  2 types of used members 1 having an L-shaped cross section shown in FIG. 2 (inner diameter 400 mm, outer diameter 450 mm, outer diameter portion 10 mm, inner diameter portion 20 mm, thickness 20 mm portion width 10 mm) As shown in FIG. 2B, the separate members 3 a to 3 c having the shapes of 2 were placed in accordance with the used member 1 and bonded together under the same conditions as in Example 1. However, regarding the heating of the separate member 3b standing vertically, the lamp was tilted 30 degrees from the vertical direction so that the heating light could be irradiated obliquely. As for the power of the lamp, by measuring the temperature using a dummy member embedded with a thermocouple in advance, the power is such that the temperature becomes 800 ° C. at the irradiation position of the lamp corresponding to each of the other members 3a to 3c. Then, each member was irradiated with that power to regenerate the member having an L-shaped cross section.

The silicon member was regenerated in the same manner as in Example 1 except that indium was used instead of aluminum. A part of the used member 1 is placed on a hot plate having a top plate size of 170 × 170 mm, the part of the used member 1 is heated to 110 ° C. or more, and the indium is melted as soon as the indium particles are placed. . By spreading the molten indium with a spatula made of silicon pieces, it was possible to apply indium to the part of the used member 1. Then, indium was apply | coated to the whole joining surface of the used member 1 by apply | coating indium similarly, shifting the position of the used member 1. FIG. After the used member 1 was cooled to room temperature, another member 3 was placed on the joint surface coated with indium and heated with a lamp and a cantal heater in the same manner as in Example 1. However, the lamp power is adjusted so that the temperature of the joint becomes 500 ° C., the temperature is raised to 500 ° C. in 5 minutes, and immediately after the temperature rises, rotation of 10 ° / min is started. And the Kanthal heater turned off.
When the obtained recycled member was cut and the cross section was observed, it was confirmed that an alloy phase containing a eutectic of indium and silicon was formed, and the used member 1 and the separate member 3 were joined.

  The method of the present invention can produce a recycled silicon member more quickly and easily with less energy.

DESCRIPTION OF SYMBOLS 1 Used silicon member 2 Metal foil 3 Another silicon member 4 Heating means 5 Condensing means 6 Chamber 7 Quartz window 8 Argon gas inlet 9 Turntable 10 Exhaust pump 11 Motor 12 X, Y-stage 13 Auxiliary heating means

Claims (7)

(1) placing a metal foil that forms a eutectic with silicon on the surface of a used silicon member, and placing another silicon member on the foil;
(2) A step of heating from the upper side of the placed other silicon member to generate a melt of the metal containing silicon,
(3) solidifying the silicon-containing metal melt, and joining the used silicon member and the another silicon member;
The manufacturing method of the reproduction | regeneration silicon | silicone member containing this.   The method according to claim 1, wherein the metal is any one of Al, Ga, Ge, and Sn.   The method according to claim 1, wherein the foil has a thickness of 0.1 to 100 μm.   The method according to claim 1, wherein in the step (2), the heating is performed by light heating.   The method according to claim 4, wherein the light heating is performed by a xenon lamp or a halogen lamp.   The method according to claim 4 or 5, wherein the step (2) is performed while scanning the surface of the another silicon member with the collected light.   The method according to claim 1, wherein the used silicon member is a focus ring, a ground ring, or an electrode plate of a dry etching apparatus.

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