Patent Application
20090000742
The present invention relates to a shower plate which is used for supplying a process gas uniformly onto a large substrate (wafer) in a semiconductor manufacturing apparatus, and a method of manufacturing the shower plate.
Heretofore, in a semiconductor manufacturing process, there have been employed semiconductor manufacturing apparatus such as a CVD apparatus for film-formation and a dry etching apparatus in which a process gas is supplied onto a surface of a wafer.
Such semiconductor manufacturing apparatus are adapted to apply a high-frequency voltage between a wafer and a shower plate from which a process gas is blown out, so as to energize the process gas into a plasma state to form a thin film on a surface of the wafer or etch the wafer surface.
In view of ensuring machinability required for forming a large number of small blowing holes, the shower plate has been formed using a plate of aluminum, silicon or the like. These materials involve problems about difficulty in mirror-finishing inner surfaces of the small blowing holes, and severe wear and tear due to poor corrosion resistance to plasma to be generated from a fluorine or chlorine-based process gas in a reaction space. On the above problems, the following Patent Publication 1 discloses a shower plate structure designed to facilitate a formation of blowing holes even using a ceramic material which has difficulty in hole machining. As shown in
As a shower-plate material having excellent corrosion resistance, high strength and high machinability, the following Patent Publication 2 discloses a ceramic material having a primary crystal phase consisting of a compound of alumina and YAG This ceramic material comprises alumina and 3 to 50 weight % of YAG, and therefore has both characteristics of alumina, such as high bending strength and high hardness, and characteristics of YAG, such as excellent corrosion resistance. In addition, each of respective average grain sizes of alumina and YAG, a ratio between the average grain sizes, a fracture toughness value of the shower plate and a thermal shock resistance of the shower plate is limited to a specific range. In the Patent Publication 2, it is described that the shower plate with the above characteristics allows a plurality of small holes to be machined with a high degree of accuracy without occurrence of chipping and cracking during machining of fine-holes, outlet ports, etc. However, in order to form the plurality of fine-holes and outlet ports for blowing out gas therefrom, this shower plate is required to employ a process of machining a hole using a fine drill having a desired size or an ultrasonic machining process of gradually drilling a hole while applying ultrasonic vibration to a drilling tool and supplying free abrasive grains thereto. Thus, the drilling tool will be subject to severe wear or abrasion to cause an increase in tool costs, and a process time for machining the large number of fine-holes will be considerably extended. Moreover, this ceramic material is a sintered material having high strength and hardness, and thereby it is extremely difficult to form an ultra-fine outlet port in view of a strength margin of a drilling tool. Thus, due to an inevitable increase in tool diameter, the outlet port must be formed to have a diameter of 0.3 mm or more, which cases a problem about backflow of plasma as a consequent adverse effect. Furthermore, it is extremely difficult to finish the plurality of fine-holes and outlet ports in a desired configuration and a desired dimensional tolerance with a high degree of accuracy.
The following Patent Publication 3 discloses a shower plate formed of a ceramic porous body which contains alumina at a content rate of 99.5 weight % or more and has a porosity of 30 to 65%. Considering that a conventional shower plate has difficulty in uniformly blowing gas in a vacuum chamber due to a gas blowing hole with a predetermined diameter, number, pitch and depth, this shower plate is intended to form pores having an average diameter of 20 to 30 μm, in an uniformly distributed manner, so as to allow the pores to serve as gas passages capable of uniformly blowing out a process gas onto a wafer. The shower plate formed of a porous body is manufactured by adding and mixing a resin material to/with alumina at a predetermined ratio to obtain a raw material, forming the raw material into a given shape, and sintering the shaped body. Thus, unevenness in mixing of the resin material and variations in sintering degree and porosity will inevitably occur to cause difficulty in providing a shower plate with stable quality and interchangeability. Moreover, in the shower plate formed of a porous body, grinding chips or fine particles generated during finish machining for outside dimensions will attach to the pores having a complicated configuration to cause a problem about outbreak of particles during an actual operation.
Patent Publication 1: JP 11-297672A
Patent Publication 2: JP 2003-133237A
Patent Publication 3: JP 2003-282462A
It is an object of the present invention to provide a shower plate made of a high-purity material and formed with a large number of process-gas blowing holes having a simple structure and a fine diameter with high dimensional accuracy without the risk of unevenness in blowing of a process gas, outbreak of particles and backflow of plasma, while ensuring constant quality and interchangeability, and a method of manufacturing a shower plate using a high-purity material while allowing a large number of blowing hole to be machined therein with a high degree of accuracy and in an easy manner.
The present invention provides a shower plate which comprises a disc-shaped plate body; a gas inlet passage including an elongated hole and an opening in communication with said elongated hole, wherein the elongated hole is extended linearly from a side face of said plate body toward a center portion thereof, and the opening is bored in the disc-shaped plate body to extend from an end of the elongated hole to a back surface of the disc-shaped plate body in a direction perpendicular to the elongated hole; and a number of blowing holes for blowing out a process gas therefrom, wherein each of the blowing holes is bored in the disc-shaped plate body from the back surface to a front surface of the disc-shaped plate body. In this shower plate, each of the blowing holes includes a main hole portion and an outlet port which are arranged in communication on the same axis. The outlet port has a diametral dimension of from 0.1 mm to less than 0.3 mm with a dimensional tolerance of the diameter of said outlet port being within ±0.002 mm.
In the shower plate of the present invention, the dimensional tolerance in the diametral dimension of the outlet port of the blowing hole is preferably within ±0.001 mm, and a surface roughness of an inner surface of the outlet port is preferably 1.0 s or less, more preferably 0.5 s or less.
According to the present invention, the outlet port in each of the large number of the blowing holes is formed to have a fine diameter with a high degree of accuracy without variation, and therefore a variation in flow rate of a process gas to be blown from the blowing holes can be substantially eliminated. This makes it possible to perform a film-forming operation or an etching operation for a large substrate (wafer) in a uniform or even manner which has not been able to be achieved by conventional shower plates, so as to manufacture high-quality semiconductors free of variation.
Preferably, in the shower plate of the present invention, the disc-shaped plate body is comprised of a ceramic material obtained by sintering a raw powder which is in turn obtained by milling and mixing 95 to 100 mass % of Al2O3 fine powder having a purity of 99.95% or more and an average grain size of 0.8 μm or less, more preferably 0.5 μm or less and 0 to 5 mass % of fine powder having a purity of 99.9% or more and consisting of at least one selected from the group consisting of Y2O3, Ce2O3 and MgO, forming the raw powder into a given shape, and sintering the obtained compact, wherein the ceramic material has a relative density of 99.4% or more, or a relative density of 97.5 to 99% and a dielectric loss of 5×10−3 to 1×10−5.
In this specific embodiment, the high-purity starting powder is prepared and sintered as the ceramic material having a low dielectric loss. Thus, a heat generation due to absorption of microwaves is almost eliminated to provide enhanced transparency to microwaves so as to achieve enhanced plasma generator efficiency and reduced energy less. The relative density may be set at 99.4% or more to provide a dense sintered ceramic material having almost no pore. In this case, a volume of gas to be absorbed therein can be reduced to allow a semiconductor manufacturing apparatus to reach a desired degree of vacuum. Alternatively, the relative density may be set in the range of 97.5 to 99% to leave a given level of pores in the sintered ceramic material. In this case, under conditions where cracks due to thermal shock are highly likely to occur, the pores can prevent crack propagation due to thermal shock.
As to a material for use in the shower plate and the shower-plate manufacturing method of the present invention, an Al2O3 fine powder having an average grain size of 0.8 μm or less may be used as a starting powder. This Al2O3 fine powder can be sintered at a relatively low temperature to suppress undesirable abnormal grain growth in a crystal structure of the sintered ceramic material. If an Al2O3 fine powder having a purity of less than 99.95% is used as the raw powder, impurities will absorb microwaves to hinder transmission of the microwaves, and the dielectric loss will exceed 5×10−3 to cause undesirable increase in energy loss. Thus, a purity of the raw powder is preferably set at 99.95% or more. 1 mass % or less of the above Al2O3 fine powder may be substituted with a high-purity MgO without problems. Preferably, Y2O3, Ce2O3 and MgO as a raw powder to be mixed with the Al2O3 fine powder is a fine powder which is as fine as possible. This raw powder may have at least an average grain size of 1 μm or less, so that it can be uniformly mixed and dispersed with/in the Al2O3 fine powder in the milling/mixing process using a ball mill or the like. Further, the raw powder having a purity of 99.9% can be used to avoid deterioration in dielectric loss.
As to a mixing ratio between the Al2O3 fine powder and the Y2O3, Ce2O3 and/or MgO fine powder, the raw powder for the shower plate may comprise 95 mass % of Al2O3 fine powder with the remainder being 5 mass % or less of Y2O3, Ce2O3 and/or MgO fine powder, to improve a degree of sintering of Al2O3 so as to provide enhanced low-temperature sinterability. If the mixing rate of the Y2O3, Ce2O3 and/or MgO fine powder exceeds 5 mass %, a liquid phase product of the Al2O3 and the Y2O3, Ce2O3 and/or MgO will be excessively increased to cause an increase in grain size of the sintered ceramic material, although the low-temperature sinterability will be improved. Moreover, a volume of pores is unexpectedly increased to cause difficulties in controllably sintering the raw powder to have a relative density in an intended range, and in obtaining a dense sintered ceramic material for the shower plate. Thus, in order to allow a sintered ceramic material for the shower plate to have a uniform fine crystal structure and a controlled relative density or high density, the mixing rate of the Y2O3, Ce2O3 and/or MgO fine powder is preferably set at 1 mass % or less. Particularly, when an Al2O3 fine powder having an average grain size of 0.5 μm or less is used as the raw powder, excellent low-temperature sinterability can be obtained. Thus, in this case, the mixing rate of the Y2O3, Ce2O3 and/or MgO fine powder may be 0 (zero) mass %, i.e., the Y2O3, Ce2O3 and/or MgO fine powder may not be mixed at all.
The present invention also provides a method of manufacturing the above shower plate which comprises the steps of forming the above raw powder for the ceramic material into a disc-shaped compact having a configuration determined in consideration of a sintering shrinkage value and a machining value; boring blind holes serving as the main hole portions of the blowing holes, from a back surface of the disc-shaped compact at predetermined positions; boring small holes serving as the outlet ports of the blowing holes, from either side of a front surface or a back surface of the disc-shaped compact, along the axis of each of the blind holes serving as the main hole portions, in such a manner that each of said small holes communicate with each of said blind holes; and thereafter sintering the disc-shaped compact.
In the method of the present invention, in a stage after forming the raw powder for sintering into the disc-shaped compact and before sintering the disc-shaped compact, i.e., when the disc-shaped compact is relatively soft, the main hole portion and the outlet port of the blowing hole are arranged in communication with on the same axis. This can provide enhanced machining efficiency, and reduce wear of drilling tools so as to provide enhanced economic efficiency.
In another aspect, the present invention provides a method of manufacturing the above shower plate which comprises the steps of forming the above raw powder for the ceramic material into a disc-shaped compact having a configuration determined in consideration of a sintering shrinkage value and a machining value; machining a side face of the disc-shaped compact, using a short drill, to form an inlet of the gas inlet passage; boring an elongated hole, using a long drill, to extend up to a center portion of the disc-shaped compact so as to communicate with the inlet on the same axis thereof, and so as to communicate with an opening bored from the back surface of the disc-shaped compact; and thereafter sintering the disc-shaped compact.
In an operation of forming the gas inlet passage in the shower plate, for example, when the disc-shaped compact obtained from the raw powder to manufacture the shower plate has a post-sintering diametral dimension of 360 mm and a post-sintering thickness dimension of 20 mm, and the gas inlet passage having a pre-sintering diametral dimension corresponding to a post-sintering diametral dimension of 1 mm is formed in the disc-shaped compact, a length of the gas inlet passage is about 200 mm which is one-half of the diameter of the shower plate, i.e., the gas inlet passage has a small diameter and an extremely long length. Thus, during the operation of boring the elongated hole using a long drill, the elongated hole is likely to be offset from an intended axis or curved so as to form micro-cracks or generate a residual stress, in an inner surface of the elongated hole. In this case, the gas inlet passage is highly likely to cause occurrence of sintering cracks during sintering of the disc-shaped compact. In the above method of the present invention, by use of a short drill, the inlet of the gas inlet passage is firstly bored along an intended axis by a predetermined distance causing no runout. During an operation of boring the elongated hole using a long drill, the inlet effectively serves as a guide hole for the long drill so as to prevent the long hole from being offset from the intended axis.
In yet another aspect, the present invention provides a method of manufacturing the above shower plate which comprises the steps of: inserting a lapping wire having a taper-shaped end portion, into one of the blowing holes of the shower plate comprised of the sintered ceramic material, to penetrate therethrough; and reciprocatingly moving the lapping wire or the shower plate, while slidingly displacing the lapping wire in such a manner that a portion of the lapping wire located in the outlet port of the blowing hole is changed from the end portion toward a base portion of the lapping wire, so as to lap the outlet port of the blowing hole.
In this method of the present invention, the taper-shaped lapping wire is inserted in the blowing hole, and the lapping wire or the shower plate is reciprocatingly moved in a direction parallel to an axis of the blowing hole, while supplying diamond abrasive grains or the like onto the lapping wire. In this manner, the outlet port can be accurately lapped to have a dimensional accuracy within ±0.002 mm, and a surface roughness of 1 s or less, more preferably 0.5 s or less.
The above shower-plate manufacturing method of the present invention may include the step of, after the step of inserting a lapping wire having a taper-shaped end portion into one of the blowing holes of the shower plate comprised of the sintered ceramic material to penetrate therethrough, clampingly attaching the end portion and the base portion of the lapping wire, respectively, to two rotatable members, in a tensioned manner, wherein the step of reciprocatingly moving the lapping wire or the shower plate includes coaxially rotating the rotatable members having the end and base portions attached thereto, at a same rotational speed. In this specific embodiment, the taper-shaped lapping wire penetrating through the blowing hole of the shower plate along the axis of the blowing hole is clampingly attached to the upper and lower rotatable members, in a tensioned manner, and the lapping wire or the shower plate is reciprocatingly moved while rotating the lapping wire to lap the outlet port of the blowing hole. Thus, the lapping operation is performed in combined directions of the rotational movement and the upward/downward movement of the lapping wire. This provides enhanced lapping efficiency and surface roughness.
The above shower-plate manufacturing method of the present invention may include the step of, after the step of inserting a lapping wire having a taper-shaped end portion into one of the blowing holes of the shower plate comprised of the sintered ceramic material to penetrate therethrough, fixedly fastening the base portion of the lapping wire to a wire fastening portion of an ultrasonic machining device, in a tensioned manner, wherein the step of reciprocatingly moving the lapping wire or the shower plate includes applying ultrasonic vibration generated by the ultrasonic machining device to the lapping wire in an axial direction of the blowing hole.
In this specific embodiment, the taper-shaped lapping wire penetrating through the blowing hole of the shower plate along the axis of the blowing hole, or the shower plate, is reciprocatingly moved in an upward/downward direction while applying the ultrasonic vibration to the lapping wire in the direction parallel to the axis of the blowing hole. This makes it possible to drastically reduce a process time required for lapping, and lap the outlet port in a dimensional accuracy within ±0.002 mm.
The above shower-plate manufacturing method of the present invention may include the steps of: after the step of inserting a lapping wire having a taper-shaped end portion into one of the blowing holes of the shower plate comprised of the sintered ceramic material to penetrate therethrough, fixing the end and base portions of the lapping wire in a tensioned manner, respectively, to two arms extending from respective upper and lower portions of a shaft adapted to be moved in an upward/downward direction; and attaching an ultrasonic vibrator to an upper of lower end of the shaft in such a manner as to be located on an axis the shaft, wherein the step of reciprocatingly moving the lapping wire or the shower plate includes applying ultrasonic vibration generated by the ultrasonic vibrator to the lapping wire which is being moved in conjunction with the shaft, in an axial direction of the blowing hole, through the shaft and the arms.
While this method is different from the above specific embodiment in a configuration for applying ultrasonic vibration, an ultrasonic vibration phenomenon acting on the taper shaped lapping wire is the same as that in the above specific embodiment. Further, the lapping operation is performed in the same manner as that in the above specific embodiment. Thus, the same effects as those in the above specific embodiment can be obtained.
The above shower-plate manufacturing method of the present invention may include the step of, after the step of inserting a lapping wire having a taper-shaped end portion into one of the blowing holes of the shower plate comprised of the sintered ceramic material to penetrate therethrough, fastening either one of the end and base portions of the lapping wire to a wire fastening device which is adapted to be rotated and moved in an upward/downward direction, and coupled to an ultrasonic vibrator, wherein the step of reciprocatingly moving the lapping wire or the shower plate includes applying ultrasonic vibration generated by the ultrasonic vibrator, in an axial direction of the blowing hole, and rotation, to the lapping wire through the wire fastening device.
In this specific embodiment, the outlet port is lapped while applying the ultrasonic vibration in the axial direction of the blowing hole and the rotation to the taper-shaped lapping wire penetrating through the blowing hole of the shower plate along the axis of the blowing hole. This makes it possible to provide strong lapping power based on large acceleration generated by the rotation and the ultrasonic vibration, and accurately lap the outlet port in a dimensional accuracy within ±0.002 mm and a surface roughness of 0.5 s or less. In the shower-plate manufacturing methods according to the above specific embodiments of the present invention, the operation of lapping the outlet port of the blowing hole after inserting a lapping wire having a taper-shaped end portion into one of the blowing holes of the shower plate comprised of the sintered ceramic material to penetrate therethrough, is performed by reciprocatingly moving the lapping wire or the shower plate, while slidingly displacing the lapping wire in such a manner that a portion of the lapping wire located in the outlet port of the blowing hole is changed from the end portion toward a base portion of the lapping wire. As above, the lapping operation is performed while slidingly displacing the lapping wire in such a manner that a portion of the lapping wire located in the outlet port of the blowing hole is changed from the end portion toward the base portion of the lapping wire. This makes it possible to drastically reduce a process time required for lapping, and lap the outlet port in a dimensional accuracy within ±0.002 mm. Further, through improvement in operational accuracy of a lapping apparatus, and appropriately selection of an abrasive grain size, the outlet port can be lapped to achieve a dimensional accuracy within ±0.001 mm and an inner surface roughness of 0.4 s or less.
In the shower-plate manufacturing methods of the present invention, the lapping may be performed to allow abrasive striations to be formed in an inner surface of the outlet port of the blowing hole in a direction parallel to an axis of the blowing hole.
For example, when the lapping operation for the outlet port is performed by applying a diamond paste having an average grain size of 5 μm, onto the lapping wire, and reciprocatingly moving the lapping wire or the shower plate, the outlet port can be lapped to have an inner surface roughness of 0.5 s or less, and abrasive striations in a direction parallel to the axis of the blowing hole. The abrasive striations serve as a flow-rectifying means to prevent turbulences from occurring in a process gas flow passing through the outlet port at a high speed.
1. The outlet port of the blowing hole has a diametral dimension of from 0.1 mm to less than 0.3 mm, and the diametral dimension has a dimensional tolerance within ±0.002 mm. Thus, there is substantially no variation in flow rate of a process gas to be blown out from the large number of blowing holes.
2. The outlet port of the blowing hole has a small diametral dimension of from 0.1 mm to less than 0.3 mm. Thus, backflow of plasma can be prevented.
3. A film-forming operation or an etching operation can be performed for a large substrate (wafer) in a uniform or even manner which has not been able to be achieved by conventional shower plates, so as to manufacture high-quality semiconductors.
4. The blowing hole can have an inner surface with a surface roughness of 0.5 s or less. Thus, a flow resistance of a process gas to be blown out can be reduced.
5. The blowing hole of the shower plate is lapped using the lapping wire having a taper-shaped end portion. This makes it possible to provide the blowing hole with high degree of accuracy, and stably manufacture shower plates having no variation in flow rate of a process gas to be blown out from the large number of blowing holes, i.e., having interchangeability.
6. The material of the shower plate has a high purity, and an excellent dielectric loss of 5×10−3 to 1×10−5. Thus, the shower plate can exhibit excellent transparency to microwave and low energy loss.
7. The blowing hole is bored from the back surface to the front surface of the disc-shaped plate body. Thus, the blowing hole itself has a simple structure and therefore can be machined and formed in an easy manner.
8. The gas inlet passage and the blowing holes are formed in the pre-sintering stage of the disc-shaped compact. This makes it possible to significantly reduce wear/abrasion of drilling tools and drastically reduce a process time required for boring the holes.
9. The ceramic material having a low dielectric constant can be sintered to have a relative density of 99.4% or more, and the both surfaces of the shower plate and the inner surface of the blowing hole can have a surface roughness of 1 s or less, more preferably 0.5 s or less. This makes it possible to prevent breakout of particles.
10. The shower plate may be controllably sintered to have a relative density of 97.5% to 99%. This shower plate is suitably used under conditions where cracks due to thermal shock are highly likely to occur.
11. Either one or both of rotation and ultrasonic vibration may be applied to the lapping wire. This makes it possible to provide enhanced blowing hole lapping efficiency.
12. Abrasive striations are formed in an inner surface of the outlet port of the blowing hole in a direction parallel to the axis of the blowing hole. The abrasive striations do not generate turbulences in a process gas to be blown out, but rather serve as a flow-rectifying means.
With reference to the accompanying drawings, an embodiment of the present invention will now be described below. The following embodiment disclosed in the accompanying drawings is illustrative only, and various other structures/configurations and machining/manufacturing processes may be appropriately combined therewith out departing from the spirit and scope of the present invention.
As shown in
As shown in
In this embodiment, the diameter D of the main hole portion 2b of the blowing hole 2 is set at 1 mm, and the diameter d of the outlet port 2a is set at 0.1 mm. An inner surface of the blowing hole 2 including the outlet port 2a is subjected to grinding to have a surface roughness of 0.5 s or less. The inner surface of the outlet port 2a is further subjected to wire-lapping using an after-mentioned taper-shaped lapping wire, to have a dimensional accuracy of Φd within ±0.002 mm, more preferably within +0.001 mm The shower plate 1 subjected to the above finish machining can ensure constant quality without variation in quality, where a process gas is blown from each of the large number of blowing holes 2 at substantially the same flow rate.
As shown in
In the above embodiment, the shower plate 1 is fixed, and the wire 14 having the taper-shaped end is reciprocatingly moved in the axial direction of the blowing hole 2. Alternatively, the wire-lapping operation may be performed under the condition that the taper-shaped wire 14 penetrating through the blowing hole 2 is fixed, and the shower plate 1 is reciprocatingly moved in an upward/downward direction. As above, the wire 14 is reciprocatingly moved in a direction parallel to the axis of the blowing hole 2 within the outlet port 2a of the blowing hole. Thus, abrasive striations in the inner surface of the outlet port 2a will be formed in a direction parallel to the axis of the blowing hole 2.
Although an apparatus for forming an end of a wire into a taper shape is not illustrated, the end of the wire may be formed into a taper shape in the following manner. Firstly, a wire is placed on an upwardly-facing surface of a first plate or grindstone reciprocatable in a lateral direction, to extend in a direction perpendicular to the reciprocating direction of the first plate or grindstone, and a second plate or grindstone having a downwardly-facing surface is disposed to be imposed on the wire at a predetermined pressure. The downwardly-facing surface of the second plate or grindstone has a lateral axis parallel to the upwardly-facing surface of the first plate or grindstone, and a longitudinal axis inclined relative to the upwardly-facing surface of the first plate or grindstone. Thus, the first grindstone having the upwardly-facing surface can be reciprocatingly moved in the lateral direction to prepare a wire having a taper-shaped end. When the two plates having the upwardly-facing and downwardly-facing surfaces are used in place of the grindstones, abrasive grains can be supplied to the surfaces of the plates during a reciprocating movement of the first plate to prepare a wire having a taper-shaped end.
First and second collets 29a, 29b are attached, respectively, to the first and second rotatable members 28a, 28b, in such a manner as to allow a lapping wire 14 penetrating through one of the blowing holes 2 of the shower plate 1, to be fastened in a tensioned manner. In this state, the shower plate 1 is reciprocatingly moved in an upward/downward direction together with a base 10, or the entire rotating mechanism, i.e., the lapping wire 14, is reciprocatingly moved in the upward/downward direction, while slidingly displacing the lapping wire 14 in such a manner that a portion of the lapping wire 14 located in the outlet port 2a of the blowing hole 2 is changed from an end portion toward a base portion thereof, so as to efficiently lap the outlet port 2a based on the rotating lapping wire 14 coated or supplied with abrasive grains. The reference numeral 30 in
In this lapping apparatus, a base plate 37 is reciprocatingly moved in an upward/downward direction (i.e., the lapping wire 14 is reciprocatingly moved), or the shower plate 1 is reciprocatingly moved in the upward/downward direction together with a base 10, while slidingly moving the lapping wire 14 in such a manner that a portion of the lapping wire 14 is located in the lapping wire 14 of the blowing hole 2 is changed from the end portion toward the base portion thereof, so as to lap the outlet port 2a.
In this lapping apparatus, a base plate 37 is reciprocatingly moved in an upward/downward direction (i.e., the lapping wire 14 is reciprocatingly moved), or the shower plate 1 is reciprocatingly moved in the upward/downward direction together with a base 10, while slidingly moving the lapping wire 14 in such a manner that a portion of the lapping wire 14 located in the outlet port 2a of the blowing hole 2 is changed from the end portion toward the base portion thereof, so as to lap the outlet port 2a, in the same manner as that in the lapping apparatus illustrated in
Although not illustrated in
In this lapping apparatus, the motor-directly-coupled ultrasonic vibrator 39 is coupled to a supporting column 36 through a linear ball bearing 30. The outlet port of the blowing hole 2 is reciprocatingly moved in an upward/downward direction while applying rotation and axial ultrasonic vibration to the lapping wire 14, so as to lap the outlet port 2a of the blowing hole 2.
A specific example of the shower plate of the present invention and a manufacturing method therefor will be described with reference to
A raw powder for sintering prepared by mixing an Y2O3 fine powder having a purity of 99.9% or more with an Al2O3 fine powder having a purity of 99.95% or more, in an amount of 0.1 to 5 mass %, was formed through a Cold Isostatic Press (CIP) to obtain a disc-shaped compact having a configuration determined in consideration of a sintering shrinkage value (i.e., a value of shrinkage due to sintering) and a machining value (i.e., a value to be machined). After machining one side region of a circumferential surface of the disc-shaped compact toward a center of the disc-shaped compact using a short drill having a diameter corresponding to that (Φ1 mm) of the gas inlet passage 3 of the finished shower plate, to form an inlet 3a, an elongated hole 3b was bored along an axis of the inlet 3a to extend up to the center of the disc-shaped compact, using a long drill. In this manner, the short and long drills were used in combination so that the elongated hole 3b of the gas inlet passage 3 could be formed in such a manner as to allow each of a coaxiality and a straightness thereof to be 0.002 mm or less. Then, an opening 3c was bored from a central region of a back surface 6 of the disc-shaped compact, using a short drill having the same size as that of the above short drill, to provide communication with an end portion of the elongated hole 3b. Alternatively, after boring the opening 3c, the elongated hole 3b may be bored to extend up to the center of the disc-shaped compact so as to provide communication between the inlet 3a and the opening 3c.
Further, a blind hole was bored from the back surface 6 toward a front surface 5 of the disc-shaped compact to extend up to a position which allows the outlet port 2a of the blowing hole 2 of the finished shower plate to have a length of 0.5 mm, using a drill having a size which allows the main hole portion 2b of the blowing hole 2 of the finished shower plate to have a diameter D of 1 mm.
Then, an outlet port 2a was bored from the front surface 5 or from the side of the back surface 6 of the disc-shaped compact along an axis of the blind hole, using a small-size drill which allows the outlet port 2a of the blowing hole 2 of the finished shower plate to have a diameter d of 0.1 mm, to establish communication of the blowing hole 2.
The above disc-shaped compact formed with the gas inlet passage and a large number of the blowing holes 2 was sintered in a conventional manner, and then subjected to a Hot Isostatic Press (HIP), to obtain a dense shower-plate sintered material having a relative density of 99.4% or more, more preferably 99.5% or more, and a dielectric loss of 5×10−3 to 1×10−5.
The front and back surface or an entire outer peripheral surface of the sintered material was subjected to grinding and abrasive finishing, using a diamond grindstone and diamond abrasive grains, in such a manner as to have a surface roughness of 1 s or less, more preferably 0.5 s or less.
Then, in order to subject the gas inlet passage 3 having a diameter of 1 mm to abrasive finishing, a mandrel having a base portion with a diameter of 0.9 mm, and an end portion with a length of 10 mm, a diameter of 0.990 mm and at least one slit, more preferably two slits, for dividing the end portion into equal portions around an axis of the mandrel, was prepared. A diamond paste having an abrasive grain size of 5 μm was applied on the divided portions of the end portion of the mandrel, and the mandrel was inserted into the gas inlet passage 3 along its axis while being rotated at a high speed. According to the high-speed rotation, a diameter of the divided portions of the end portion of the mandrel is increased by a centrifugal force to generate a grinding force. In this manner, the abrasive finishing was carried out to allow the gas inlet passage 3 to have a surface roughness of 1 s or less, more preferably 0.5 s or less.
The following description will be made about an abrasive finishing for the blowing hole 2. In the sintered material of this example, a diametral dimension of the main body portion 2b of the blowing hole 2 was set in the range of 0.995 to 1.00 mm, and a diametral dimension of the outlet port 2a of the blowing hole 2 was set in the range of 0.093 to 0.098 mm.
In the abrasive finishing for the main body portion 2b of the blowing hole 2, a diamond paste having an abrasive grain size of 5 μm was applied on a mandrel having the same size as that of the aforementioned mandrel, and the mandrel was inserted into the blowing hole 2 along its axis while being rotated at a high speed, so as to allow the main body portion 2b of the blowing hole 2 to have a diameter D of 1.0 mm and a dimensional accuracy within ±0.002 mm.
Further, in order to lap the outlet port 2a of the blowing hole 2, a lapping wire was prepared in such a manner that it has a diametral dimension of 0.093 mm and an overall length 200 mm, and an end portion thereof having a length of 100 mm is machined into a taper shape to provide an end edge with a diametral dimension of 0.08 mm.
Then, the shower-plate sintered material subjected to the above machining and finishing was attached to the wire-lapping apparatus illustrated in
As a final treatment, the shower plate subjected to the grinding and abrasive finishing was subjected to a precision ultrasonic cleaning process to fully remove fine particles and contaminants attached or fixed on each portion. Finally, a finished shower plate free of breakout of particles could be obtained.
The present invention can be applied to a shower plate for use in a semiconductor manufacturing apparatus, such as a CVD apparatus or a dry etching apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-120256 | Apr 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/307928 | 4/14/2006 | WO | 00 | 5/21/2008 |
