JPH06241231A - Sliding bearing - Google Patents

Abstract

PURPOSE:To provide a sliding bearing that will not harm any lubricity even in a cryogenic state and prevent abrasion powder from scattering around as particulates. CONSTITUTION:In a slide bearing supporting a shaft 72 inserted into an insertional part 88 shiftablt, an expanded curved surface part 94 is formed on an inner wall 92 of an opening part 90 of this insertional part 88 while a solid film antifriction is coated as a lubricant. With this constitution, lubricity in a cryogenic state is secured and, what is more, abrasion powder to be produced is made to stay on the curved surface 94.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slide bearing which supports a pusher pin of a plasma etching apparatus or the like.

[0002]

2. Description of the Related Art Generally, in a semiconductor manufacturing process, an object to be processed, for example, a semiconductor wafer, is repeatedly subjected to a sputtering process, an etching process and the like by various processing apparatuses. Taking an etching apparatus as an example, an electrostatic chuck is provided in the processing container, and the wafer is attracted and held by the Coulomb force to the susceptor side to which the chuck is attached.

Further, this wafer can be mounted on the chuck from the handling arm, or can be vertically moved through the chuck or susceptor in order to pass the wafer mounted on the chuck to the handling arm. A plurality of pusher pins made are provided via slide bearings. When the wafer is placed on the chuck by the handling arm, the pusher pin is lifted to push up the wafer supported by the handling arm to deliver the wafer onto the pin, and the pusher pin is lowered after the arm is retracted. This places the wafer on the chuck. Further, in order to transfer the wafer placed on the chuck to the handling arm, the reverse operation to the above is performed. Further, on the lower surface of the susceptor, provided is a cooling block having a coolant passage through which a coolant or the like for cooling the temperature of the wafer heated by plasma or the like to a predetermined processing temperature is circulated, The cold heat from now on is supplied to the wafer.

[0004]

By the way, recently, a so-called low-temperature etching process, in which a wafer is cooled and kept at an ultra-low temperature of about -150 ° C. using, for example, liquid nitrogen, and an etching process is performed under a reduced pressure in this state A method has been developed, and this low-temperature etching treatment makes it possible to increase the selection ratio with respect to the base in comparison with the conventional method when etching, for example, polysilicon or a silicon oxide film. In addition, the anisotropy can be sufficiently ensured.

However, the slide bearing for supporting the pusher pin slidably in the vertical direction is generally a casing 1 formed in a hollow cylindrical body as shown in FIG.
00 is provided with a large number of ball bodies 102 that can be circulated by rolling in the sliding direction of the shaft 72 that supports the pusher pin on the inner wall surface of 00, and the shaft 72 is inserted into the hollow insertion portion 104. Although it is slidably supported, it has the following improvements because the lubricant used is, for example, fluorine grease or mineral oil. That is, the fluorine-based grease as a lubricant has a low glass transition temperature of about −100 ° C., but when the above-mentioned ultra-low temperature etching treatment of about −150 ° C. is performed, this grease is a glass. It had the improvement point that it became solidified and solidified, the frictional resistance rapidly increased, and the function of the lubricant was not fulfilled.

Further, in the processing of wafers, since microfabrication is performed, it is necessary to suppress the generation of particles and the like, which cause a decrease in yield as much as possible, but as described above, when the frictional resistance becomes large, abrasion powder is generated. In particular, the attachment of wear powder to the pusher pins that come into direct contact with the wafer has been a serious problem. In addition, the etching process uses a corrosive gas, but the mineral oil described above has a low corrosion resistance and may be deteriorated by this gas, or the lubricity deteriorates at a low temperature of -150 ° C. Had.

Therefore, it is conceivable to use a solid film lubricant which does not impair the lubricity even at an extremely low temperature as a lubricant, but this lubricant is microscopically obtained by scraping off the scale-like thin films laminated at the time of rubbing. Since the lubricity is maintained, it is unavoidable that some abrasion powder is generated, and this may become particles. The present invention is
It was devised to pay attention to the above problems and effectively solve them. An object of the present invention is to provide a slide bearing that does not impair lubricity even in an ultra-low temperature state, and in which abrasion powder does not scatter as particles.

[0008]

SUMMARY OF THE INVENTION The present invention provides a slide bearing having a hollow cylindrical casing having an insertion portion for inserting a shaft to be supported in order to solve the above-mentioned problems. On the inner wall of the opening portion of the portion, a curved surface portion whose opening diameter is gradually enlarged toward the outside from the inside of the casing is formed, and a solid film lubricant is applied as a lubricant.

[0009]

Since the present invention is configured as described above, when the shaft inserted through the insertion portion of the casing slides, the solid coating lubricant used as a lubricant generates abrasion powder due to friction. Not only stays in the curved surface portion formed in the opening of the casing insertion portion and is prevented from scattering outside, but also functions as a lubricant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the slide bearing of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a sectional view showing a plasma etching apparatus to which a slide bearing according to the present invention is applied, FIG. 2 is a sectional view showing a slide bearing according to the present invention, and FIG. 3 is an enlarged view of a portion A in FIG.

First, prior to the description of the slide bearing of the present invention, a plasma etching apparatus to which the slide bearing is applied will be described. As shown in the drawing, the etching apparatus 2 has a processing container 4 which is formed of a conductive material such as aluminum into a cylindrical or rectangular shape. The bottom of the container 4 is formed of ceramics such as a ring. A substantially columnar mounting table 8 for mounting an object to be processed, such as a semiconductor wafer W, is housed via an insulating plate 6. This mounting table 8
The susceptor support base 10 is made of aluminum or the like in a cylindrical shape, and a susceptor 14 made of aluminum or the like is detachably provided on the susceptor support base 10 by means of bolts 12.

The susceptor support 10 has a cooling means,
For example, a cooling jacket 16 is provided, and a refrigerant such as liquid nitrogen is provided in the jacket 16 as the refrigerant introducing pipe 1.
It is introduced via 8 and circulates in the jacket, and is discharged from the refrigerant discharge pipe 20 to the outside of the container. The susceptor 14 is
The central portion is formed in a disk shape having a protrusion shape, and an electrostatic chuck 22, for example, is formed as a chuck portion on the wafer mounting portion at the center thereof in an area substantially the same as the wafer area. The electrostatic chuck 22 is formed, for example, by sandwiching a conductive film 24 such as a copper foil in an insulating state between two polymer polyimide films. The conductive film 24 is a filter that cuts a high frequency on the way by a voltage supply lead 26. It is connected to the DC high voltage source 27 via 28. Therefore, by applying a high voltage to the conductive film 24, the chuck 22
The upper surface of the wafer W can be suction-held by the Coulomb force. A gas passage 30 is formed in the susceptor support 10 and the susceptor 14 for supplying a heat transfer promoting gas such as He to the back surface of the wafer W. still,
A large number of vent holes (not shown) are formed in the electrostatic chuck 22 to allow the heat transfer promoting gas to pass therethrough.

An annular focus ring 32 is arranged at the upper peripheral edge of the susceptor 14 so as to surround the wafer W. The focus ring 32 is made of an insulating material that does not attract the reactive ions, and allows the reactive ions to effectively enter only the semiconductor wafer W inside. The susceptor 14 is provided with a pipe lead 34 made of a hollow conductor that penetrates the susceptor support 10. The pipe lead 34 has a wiring 36.
Is connected to a high frequency power source 38 for generating plasma of 13.56 MHz, for example. Therefore, the susceptor 14 is configured as a lower electrode. And
A matching capacitor 40 is provided on the wiring 36.

Above the susceptor 14, the upper electrode 4 is grounded at a distance of about 15 to 20 mm.
2 is provided, a process gas, for example, an etching gas such as CF ₄ is supplied to the upper electrode 42 through a gas supply pipe 44, and a large number of small holes 46 formed on the electrode surface of the upper electrode 42. The etching gas is blown out into the processing space below. An exhaust pipe 48 is connected to the lower side wall of the processing container 4 so that the atmosphere in the processing container 4 can be exhausted by an exhaust pump (not shown).

A temperature adjusting heater 50 is provided between the electrostatic chuck 22 and the cooling jacket 16. The heater 50 is formed in a plate shape having a thickness of about several mm, and has, for example, tungsten, carbon, river light, or Feclaloy (Fe-Cr-A) inside.
A linear or strip-shaped resistance heating element 52 made of (a small amount of La and Y added to the l base) (trade name) is arranged in a meandering or single-stroke form over the whole. The entire resistance heating element 52 is covered with an insulator 54 made of sintered AlN (aluminum nitride). When the heater 50 is attached, the internal heating element 52 is attached.
Is configured to be electrically insulated from the external base side. A power supply lead 53 is connected to the heater 50, and a power source 55 is connected to the lead 53. The heater 50 is completely accommodated in the heater accommodating groove formed in the upper portion of the heater fixing base 56 provided on the upper surface of the susceptor supporting base 10 with its upper surface at the same level. The heater fixing base 56 is made of a material having good thermal conductivity, such as aluminum. The size of this heater 50 is
It is preferable that the area is set to be substantially the same as or larger than the wafer area. The temperature of the wafer W is adjusted by controlling the transfer of cold heat from the cooling jacket 16 located below the wafer area to the wafer W. Configured to do. A branch passage 58 connected to the gas passage 30 is formed in the heater fixing base 56 at the boundary between the upper surface of the heater 50 and the lower surface of the susceptor 14 in order to supply a heat transfer promoting medium such as He. .

In addition, the electrostatic chuck 22 has a thermometer, for example, a fluorometer, which utilizes the fact that the round trip time of light changes depending on the temperature in order to detect the wafer temperature.
Thermometry (Fluoropic Thermom)
temperature detector 60 composed of an "try" (trademark) or a thermocouple
Is provided. And, in this temperature detector 60,
The temperature detection lead 62 for transmitting the detected value is connected. This temperature detection lead 62 is composed of an optical fiber when a fluororope thermometry is used as the temperature detector 60, but when a thermocouple is used, an ordinary conductor is used, and in this case, high frequency noise is generated. A filter 64 for removing the
For example, it is input to a control unit (not shown) including a computer or the like. This control unit controls the entire apparatus by a predetermined program as described above. For example, the high frequency power source 38, the power source 55 to the heater 50, and the DC high voltage source 27 to the electrostatic chuck 22 are distributed. To control. Also,
An insulator 66 is provided in a penetrating portion of the pipe lead 34 at the bottom of the processing container to electrically insulate it from the container side. In addition, a large number of sealing members for preventing unnecessary gas from flowing into the processing chamber are provided at predetermined joining points of the mounting table 8.

The susceptor 14 and the electrostatic chuck 22 have a plurality of through holes 68 penetrating in the vertical direction in the figure.
Is formed therein, and the pusher pin 70 that is vertically movable is accommodated therein. A plurality of pusher pins 70, for example, four pusher pins 70 are evenly arranged in the entire chuck surface so that the tip of the pusher pins 70 can support the wafer W. In the illustrated example, two pusher pins are shown as a representative, and one of them shows only the upper part. A shaft 72 is connected to the lower end of the pusher pin 70, and a pusher pin drive motor 74 for vertically moving the pusher pin 70 is provided outside the container below the shaft 72. The drive shaft 76 of the motor 74 is connected to the shaft 72 through a transmission mechanism such as a rack and a pinion, and the pusher pin 7 is connected as necessary.
It is possible to freely project and retract 0 above the upper surface of the chuck 22.

(Description of Slide Bearing) A slide bearing 78 according to the present invention is provided to slidably support the shaft 72 to which the pusher pin 70 is connected. Specifically, the slide bearing 78 is accommodated in a bearing accommodating space 80 formed in the susceptor support base 10, and the lower end portion thereof is fixed to the susceptor support base 10 side to stand upright. There is. A bellows 82 is provided between the shaft 72 and the bottom surface of the bearing accommodating space 80 so as to cover the slide bearing 78, and the bearing 78 is provided to suppress scattering of particles.
The gas that comes into contact with the gas does not flow directly to the processing space. A vent hole (not shown) is provided at the bottom of the bearing housing space 80 to secure the supply and discharge of gas in the bellows 82.

As shown in FIGS. 2 and 3, the slide bearing 78 is formed like a known slide bearing as a whole, except that the inner walls of both ends of the opening of the casing 86 are expanded. The points are formed in a curved surface shape.
That is, the slide bearing 78 has a hollow cylindrical casing 86 having an insertion portion 88 for inserting the shaft 72 in the center thereof.

Then, the opening portions 9 at both ends of the insertion portion 88 are formed.
The inner wall 92 of 0 is formed with a curved surface portion 94 whose opening diameter is sequentially increased from the inside of the casing toward the outside in the axial direction. The dimension at this time is, for example, as shown in FIG. 3, when the diameter D1 of the shaft 72 is about 5 mm, the curved surface portion 9
4 has a depth D2 of about 2 to 10 mm and a width D3 of 5 mm
Set to a degree. The curvature R of the curved surface portion 94 is 6
Set to about 50 mm. Further, the depth D2 is preferably set to be larger than the stroke of the pusher pin in the vertical direction so as to suppress the abrasion powder from scattering outside the system as much as possible.
The specific numerical values are not limited to these values. Then, the inner wall 9 of the insertion portion 88 of the casing 86
A solid coating lubricant is applied as a lubricant to the entire surface of No. 2 and the outer peripheral surface of the shaft 72, or one of them, to form a coating 96.
Are formed with a thickness of, for example, several μm to several tens of μm. In the illustrated example, the case where the coating 96 is formed only on the inner wall 92 on the casing side is shown.

This solid coating lubricant is a metal chalcogenide which is a compound of a metal with a chalcogen such as O, S, Se, Te or Po which is a Group VI element of the periodic table, for example, molybdenum disulfide or tungsten disulfide, It is made by binding tungsten diselenide or the like with PTFE (fluorine resin) or the like, and has a scale-like laminated structure.
Then, due to friction, this lubricant is generated as abrasion powder, and sufficient lubricity can be ensured even in an ultra-low temperature state of, for example, about −150 ° C. In this case, the abrasion powder generated as described below adheres to the wall surface of the curved surface portion 94 of the casing 86 and is prevented from scattering to the outside.

Next, the operation of this embodiment configured as described above will be described. First, a wafer W supported by a handling arm (not shown) is loaded into a processing container 4 which is depressurized to a predetermined pressure, for example, about 1 × 10 ⁻⁴ to several Torr from a load lock chamber (not shown), and the pusher pin 70 is used. Susceptor 1 by passing it down and lowering it
The wafer W is placed on top of the electrostatic chuck 22
Due to the Coulomb force, it is adsorbed and held on the susceptor 14 side. Then, the upper electrode 42 and the lower electrode (susceptor) 14
Plasma is generated by applying a high frequency through the pipe lead 34 between and, and at the same time, a process gas is caused to flow from the upper electrode 42 side into the processing space to perform etching processing.

Further, in order to perform low temperature etching, a cooling medium such as liquid nitrogen is circulated in the cooling jacket 16 of the susceptor support 10 to maintain this portion at -196 ° C., and the cooling heat from this portion is passed through the susceptor 14 above this. Wafer W
It is supplied to and cooled. In this case, a temperature adjusting heater 50 is provided between the cooling jacket 16 and the wafer W, and the temperature of cooling the wafer W is adjusted by adjusting the heat generation amount of this portion, and the wafer W is cooled to a predetermined temperature, for example, Maintain at about -150 ° C to -180 ° C. In the conventional apparatus, the wafer temperature is controlled by controlling the temperature of the cooling medium itself. Moreover, the distance between the cooling jacket and the wafer is long, and there are many member interfaces, so the thermal response is extremely poor. It was On the other hand, in the present embodiment, as described above, the cooling jacket 16 is fixed at a constant low temperature, for example, -196 ° C, while the heater 50 approaches the wafer W at a distance of, for example, 15 to 20 mm. Since the temperature of the heater 50 is changed, the change in the amount of heat generated by the heater 50 immediately appears as a change in the temperature of the wafer W. Therefore, the thermal response is good, and the wafer temperature can be quickly controlled. Therefore, when the heater 50 is turned off, the wafer cooling temperature by only liquid nitrogen, for example, −16.
The temperature difference between 0 ° C (liquid nitrogen (-196 ° C) and 36 ° C is the temperature difference caused by the inherent thermal resistance of each member such as the susceptor as the minimum temperature value, and more quickly within the temperature range up to room temperature. It is possible to control the wafer temperature linearly and linearly.

He is provided on the interface between the heater 50 and the susceptor 14 and on the lower surface of the wafer W through the gas passage 30.
Since the heat transfer accelerating gas such as the above is introduced, the heat transfer efficiency between the upper and lower parts does not deteriorate, and the above-mentioned thermal responsiveness can be further improved. Then, when the plasma processing is completed, the pusher pin 70 is lifted to push up the wafer W attracted and held on the upper surface of the electrostatic chuck 22, and in this state, a handling arm (not shown) crosses the pusher pin 70 from the horizontal direction. Let it invade as you would. Then, by lowering the pusher pin 70, the wafer W is transferred to the handling arm, and after the processed wafer is unloaded, the unprocessed wafer is loaded into the processing container 4 as described above.
The above operation is repeated.

In this way, the pusher pin drive motor 7 is loaded every time the wafer W is loaded into or unloaded from the processing container 4.
4 rotates to frequently move the shaft 72 connected to the pusher pin 70 up and down. At this time, this shaft 7
A slide bearing 78 that supports 2 allows the shaft 72 to move up and down. Here, in this embodiment, since the wafer is subjected to the ultra-low temperature etching process, the slide bearing 7 is cooled by the cooling heat from the cooling jacket 16.
8 is cooled to, for example, −110 ° C. or lower, but a solid coating lubricant coating 96 is formed on the inner wall of the casing 86, the outer peripheral surface of the shaft 72, and the like as necessary (in FIG. 3, only the inner wall of the casing is formed). Since this is formed, it gradually peels off to become abrasion powder, and even in the above-mentioned ultra-low temperature state, this abrasion powder exerts a lubricating function, so that the vertical movement of the pusher pin 70 is not hindered,
It is possible to guarantee smooth vertical movement.

As described above, the solid coating lubricant is, so to speak, a self-sacrificing lubricant because it is easy to cause shearing, and the lubricity can be maintained even at an extremely low temperature, but the wear powder that has fallen off is discharged to the outside of the system. easy. However, in the present embodiment, the casing opening 90 is sequentially enlarged to form the curved surface portion 9
Since No. 4 is formed, the generated abrasion powder 98 adheres to and stays on the inner wall 92 of the curved surface portion 94 without being discharged to the outside of the system. Therefore, even if the abrasion powder 98 is generated, it is possible to prevent the abrasion powder 98 from becoming particles and scattering and flowing into the processing container 4.

As described above, since the solid film lubricant is used as the lubricant of the bearing to further form the curved surface portion 94 which is expanded in the opening portion of the shaft insertion portion 88, the friction coefficient is maintained even in an ultra-low temperature state. It is possible to prevent the abrasion powder 98 generated while maintaining a high lubricity by making it small and scattering from the system. Further, the abrasion powder 98 attached and retained on the inner wall 92 of the opening 90 moves along with the inside of the insertion portion when the shaft 72 moves in the opposite direction and can be repeatedly used as a lubricant, so that the entire life is extended. It is possible to suppress not only the amount of the abrasion powder 98 generated, but also the amount of the abrasion powder 98 generated.

When the solid coating lubricant is formed only on the inner wall 92 of the casing 86, the overall friction coefficient is reduced, but the lubricant is applied not only to the inner wall 92 of the casing 86 but also to the outer peripheral surface of the shaft 72. Once formed, the overall life can be extended and can be selected according to the application. In the present embodiment, the coating film 96 of the solid coating lubricant is formed to have a thickness of about 13 μm when applied on one side, and a thickness of about 5 to 7 μm when applied on both sides, at a temperature of −196 ° C. to +500.
When the friction coefficient was measured in the range of ℃, this value was 0.0
A low value of 5 to 0.2 was obtained, and good results could be obtained. At this time, the shaft was made of stainless steel material, and the casing was made of copper gun metal. In the above embodiment, the case where the slide bearing is applied to the plasma etching apparatus has been described, but an apparatus that requires pusher pins for transferring a wafer, for example, a CVD apparatus,
Of course, it can be applied to any device such as an ashing device and a sputtering device.

[0029]

As described above, according to the slide bearing of the present invention, the following excellent operational effects can be exhibited. Since a solid film lubricant is used as a lubricant and a curved surface portion that retains the generated wear powder is formed, it is possible to prevent the generated wear powder from scattering out of the system while maintaining high lubricity even in an ultra-low temperature state. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view showing a plasma etching apparatus to which a slide bearing according to the present invention is applied.

FIG. 2 is a sectional view showing a slide bearing according to the present invention.

FIG. 3 is an enlarged view of part A in FIG.

FIG. 4 is a sectional view showing a linear motion bearing for explaining a conventional support structure of a pusher pin.

[Explanation of symbols]

 2 Plasma Etching Device 4 Processing Container 14 Susceptor 16 Cooling Jacket 22 Electrostatic Chuck 50 Temperature Adjusting Heater 72 Shaft 78 Slide Bearing 80 Bearing Housing Space 82 Bellows 86 Casing 88 Insertion Portion 90 Opening 92 Inner Wall 94 Curved Surface 96 Coating (Solid) Coating lubricant) 98 Wear powder W Semiconductor wafer

Claims (1)

[Claims] 1. A slide bearing having a hollow cylindrical casing having an insertion portion for inserting a shaft to be supported, wherein an inner wall of an opening of the insertion portion of the casing extends outward from the inside of the casing. According to the above, the slide bearing is characterized in that a curved surface portion whose opening diameter is sequentially enlarged is formed and a solid film lubricant is applied as a lubricant.