US20050000943A1

US20050000943A1 - Processing apparatus, method for fabrication of semiconductor device by using the processing apparatus, and semiconductor device fabricated by this method

Info

Publication number: US20050000943A1
Application number: US10/853,172
Authority: US
Inventors: Isao Sugaya; Akinori Ito; Isao Komatsu
Original assignee: Nikon Corp; Nikon Technologies Inc
Current assignee: Nikon Corp; Nikon Technologies Inc
Priority date: 2003-05-30
Filing date: 2004-05-26
Publication date: 2005-01-06
Also published as: JP2004356563A; KR20040103392A; JP4269259B2; TW200510113A

Abstract

The processing apparatus in accordance with the present invention comprises an object holding unit for holding a processing object, a tool holding unit for holding a tool for processing the processing object, and a relative movement mechanism for causing relative movement of the processing object held in the object holding unit and the tool held in the tool holding unit, while maintaining contact therebetween. The object holding unit and/or the tool holding unit are composed of a plurality of support plates of almost flat shape having elastic property which are arranged in a row.

Description

FIELD OF THE INVENTION

The present invention relates to a processing apparatus comprising an object holding unit for holding a processing object, a tool holding unit for holding a tool for processing the processing object, and a relative movement mechanism for causing relative movement of the processing object held in the object holding unit and the tool held in the tool holding unit, while maintaining contact therebetween. The present invention also relates to a method for the fabrication of a semiconductor device in which the processing object is a semiconductor wafer and the processing apparatus is used as a polishing apparatus for polishing of the semiconductor wafer and also to a semiconductor device fabricated by this method.

BACKGROUND OF THE INVENTION

Examples of the aforementioned processing apparatuses include polishing apparatuses in which a semiconductor wafer serving as a processing object is held with a holding unit and surface polishing of the semiconductor wafer is conducted by causing relative rotational movement of the semiconductor substrate and a polishing tool (polishing pad), which is a processing tool, while maintaining contact therebetween. Polishing apparatuses for conducting surface polishing of semiconductor wafers in the above-described manner are required to carry out extremely accurate and uniform polishing. For this reason, care was taken to maintain constantly the optimum processing state by employing a configuration in which a polishing tool changed the posture thereof according to peaks and valleys of the wafer (processing object) surface or the wafer changed the posture thereof.
For example, in the polishing apparatus disclosed in U.S. Pat. No. 6,251,215, a highly flexible rubber sheet is used in the head portion for holding the wafer and the wafer is pressed against the polishing pad serving as a polishing tool via the rubber sheet by applying air pressure to the back surface side of the rubber sheet. Furthermore, in the apparatus disclosed in Japanese Patent Application Laid-open No. H10-235555, a head portion for holding a wafer is linked to a rotary drive shaft via a ball joint structure and the head portion is rotary driven via the ball joint unit so that it is free to swing. Using the aforementioned rubber sheet or ball joint structure allows the wafer to change pliably the posture thereof according to peaks and valleys on the surface thereof, the wafer is in constant and uniform contact with the polishing pad, and uniform surface polishing can be conducted.
By contrast with the above-described configuration, an apparatus is also known which is so constructed that the polishing tool, that is, the polishing pad can pliably change the posture thereof (Japanese Patent Application Laid-open No. H11-156711). In this apparatus, a wafer is vacuum suction attached to a wafer chuck, so that the surface of the wafer which is to be polished faces up (face-up state), and rotates together with the wafer chuck. A polishing head is disposed opposite the wafer and above it. The polishing head comprises a pad plate having pasted thereon a polishing pad which is to be in contact with the wafer surface which is to be polished, a drive plate and a rubber sheet (diaphragm) for flexibly supporting the pad plat, and a head housing having formed therein an inner space for constituting a pressure chamber for applying the air pressure to the aforementioned components. The outer periphery of the drive plate and rubber sheet are joined at the outer periphery of the lower edge of the head housing, the drive plate and rubber sheet are joined with the pad plate in the inner peripheral portion thereof, and the inner space of the head housing is covered by those drive plate and rubber sheet, thereby forming the pressure chamber. As a result, the pad plate is supported by the head housing via the drive plate, and a pressure is uniformly received inside the pressure chamber via the rubber sheet. If the head housing is rotary driven, then the rotary driving force is transmitted to the pad plate via the drive plate, and the entire configuration is rotated.
A process for polishing a wafer by using such a polishing apparatus is conducted by bringing the polishing pad into contact with the surface of the wafer which is suction held by the wafer chuck, while rotating the head housing. In this process, the head housing is moved sidewise in a plane and the entire surface of the wafer is uniformly polished. When the wafer surface is thus polished, the drive plate is required to have sufficient flexibility in the up-down direction (thickness direction) so that the polishing pad can pliably change the posture thereof according to peaks and valleys of the substrate surface. The drive plate is further required to allow the head housing and pad plate to be rotated by transmitting the rotary drive force (drive torque for processing) of the head housing via the pad plate and to have a strength and endurance sufficient to withstand the action of the rotary drive force or contact resistance (resistance torque during processing) between the polishing pad and wafer during rotation.
As described hereinabove, the outer periphery of the drive plate is joined to the outer periphery of the lower end of the pad housing and the pad plate is engaged with the inner periphery of the drive plate. Therefore, the pad plate moves in the up-down direction with respect to the pad housing because the inner periphery moves in the direction perpendicular to the drive plate surface with respect to the outer periphery of the drive plate due to elastic deformation thereof. Thus, large movement caused by elastic deformation in the direction perpendicular to the plane on the inner periphery with respect to the outer periphery of the drive plate means that the drive plate has a high degree of flexibility in the up-down direction. In order to provide the drive plate with such large flexibility in the up-down direction, a configuration was used, for example, as shown in FIG. 19, in which the drive plate 100 was produced by forming a disk with a round hole in the center from a thin metal sheet and then forming multiple openings positioned on concentric circles in the disk. In such a drive plate 100, when the outer periphery 102 is joined and held on the outer periphery of the lower end of the pad housing, the inner periphery 101 where the pad plate is joined can be elastically deformed to a large degree in the up-down direction and, therefore, the drive plate has large flexibility in the up-down direction.
However, the requirements placed on flexibility of the drive plate in the up-down direction and strength and endurance against the resistance torque or drive during processing are mutually exclusive and are difficult to satisfy at the same time. For example, as shown in FIG. 19, flexibility in the up-down direction can be increased by providing multiple openings 103 in the drive plate 100. However, if the number or size of the openings 103 is too large, then strength against the resistance torque or drive during processing decreases and the drive plate can be deformed or fractured. In particular, because the openings 103 in the drive plate 100 are subjected to cyclic stresses during processing, there is a risk of those cyclic stresses causing fatigue damage and fracture (for example, damage and fracture such as a crack 100 a shown in FIG. 19).
Furthermore, large flexibility of the drive plate in the up-down direction is required not only for tracing the peaks and valleys on the wafer surface during processing, as described hereinabove, but also from the following standpoint. First, if polishing is conducted by pressing a polishing pad against the wafer surface, then the polishing pad surface is worn and thinned as the wafer surface is polished. The problem associated with this effect is that the amount of deformation of the drive plate in the up-down direction increases accordingly, a restoration force in the up-down direction is generated to restore the original shape, this force acts in the direction opposite that of the air pressure created by the pressure chamber, and the contact pressure between the polishing pad and wafer surface changes (decreases). In order to minimize these changes in contact pressure, it is desired that the flexibility of the drive plate in the up-down direction be increased, that is, that the elastic constant relating to elastic deformation in the up-down direction be decreased.
Further, in order to minimize the effect of the restoration force generated by such deformation of the drive plate in the up-down direction, the adjustment is conducted so that the drive plate assumes a neutral position (position in which the restoration force does not act) in a state where the polishing pad is brought into contact with the wafer surface which is to be polished, before the polishing is started. However, the accuracy of such adjustment is limited. Furthermore, because of a spread in thickness of the pad plate and polishing pad, the position of the drive plate unavoidably shifts to a certain extent from the neutral position in the up-down direction after the processing is started. As a result, a certain restoration force acts after the processing has been started. In order to resolve these problems, it is desired that the flexibility of the drive plate in the up-down direction be increased within a range of satisfactory endurance, that is, that the elastic constant relating to elastic deformation in the up-down direction be decreased.
Furthermore, a high polishing accuracy of wafer surface cannot be attained by merely increasing the flexibility of the drive plate in the up-down direction. More specifically, it is necessary to hold the polishing pad and wafer surface parallel to each other and to provide the drive plate with an appropriate flexibility in the inclined direction, that is, to ensure a suitable rigidity thereof, so that the polishing pad and wafer surface maintain intimate contact during polishing. This issue was not heretofore given much attention, and at the stage of designing the drive plate, the principle emphasis was on flexibility in the up-down direction. For this reason, when the polishing pad protruded from the wafer surface and overhung during swinging of the polishing head, the drive plate could not provide a restoration force sufficient to check a momentum force acting upon the polishing pad, the positioning pad tilted, and eventually stress concentration occurred in the edge portions of the wafer. Such stress concentration at the edge circumference is typically called “edge exclusion”. Because it produces an excess polishing region, the polishing rate becomes much higher in this region than in other places and this region cannot be employed as a device region. This rises a problem with brittle materials such as low-k materials that have recently become materials of choice, because the structure itself can be compression fractured by stress concentration.
Yet another problem associated with the conventional drive plate is that the so-called chatter vibrations originate in the polishing pad, and these vibrations make it necessary to interrupt the polishing process.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a processing apparatus in which the rigidity of the drive plate in the up-down direction can be decreased, while maintaining sufficient strength and endurance during polishing.
Another object of the present invention is to provide a processing apparatus that ensures correct rigidity of the drive plate in the inclined direction.
Yet another object of the present invention is to provide a processing apparatus with a structure such that makes it possible to suppress vibrations of the polishing pad.
The processing apparatus in accordance with the present invention, comprises an object holding unit (for example, a substrate holding table 95 in the embodiment) for holding a processing object (for example, a substrate 90 in the embodiment), a tool holding unit (for example, a polishing head 30 in the embodiment) for holding a tool (for example, a polishing tool 50 having a polishing pad 60 mounted thereon in the embodiment) for processing the processing object, and a relative movement mechanism (for example, a support frame 20 in the embodiment) for causing relative movement of the processing object held in the object holding unit and the tool held in the tool holding unit, while maintaining contact therebetween, wherein the object holding unit and/or tool holding unit are composed of a plurality of support plates (for example, a drive plate 33 in the embodiment) of almost flat shape having elastic property which are arranged in a row. It is especially preferred that a plurality of support plates be disposed by stacking in a row in the plate thickness direction.
Thus, in the processing apparatus in accordance with the present invention, the support plates such as drive plates are used upon stacking a plurality thereof in the up-down direction (plate thickness direction). For example, let us consider a case in which two drive plates are stacked. FIG. 3 is a schematic sectional view illustrating the main elements peripheral to the processing tool (polishing tool) 50 of the processing apparatus in accordance with the present invention. The processing tool 50 is supported in the center of the support plate (drive plate) 33 and is attached to the tool holding unit (polishing head) 30 via the drive plate 33. Therefore, if the drive plate 33 is deformed, the polishing tool 50 shifts accordingly. Here, in case of two drive plates 33, the configuration can be considered as a parallel spring in which plate springs 33 a, 33 b are arranged in a row one above the other and fixed at both ends thereof with mixing members 33 c, as shown in FIG. 4. The properties of a parallel spring are such that the amount of displacement (amount of curving) caused by a force acting in the up-down direction is half that of one plate spring, whereas the displacement caused by a force acting in the inclined direction is much less than half that of one plate spring. Thus, in a parallel spring, the rigidity in the inclined direction is greater than that in the up-down direction. This difference becomes more significant with the increase in the number of plate springs. Therefore, if a plurality of the drive plates are arranged by stacking in a row so as to obtain a parallel spring configuration, then the rigidity in the up-down direction and rigidity in the inclined direction can be independently controlled and set to a desired balance by controlling the thickness and number of the drive plates. For example, if a randomly selected drive plate is compared with a configuration obtained by stacking two drive plates which has a thickness of 1/³{square root}{square root over ( )}2 of the selected drive plate, the rigidity in the up-down direction will be the same, but the rigidity of the former configuration in the inclined direction is substantially higher than that of the single drive plate. Therefore, the present invention makes it possible to increase easily only the rigidity in the inclined direction. Furthermore, in the processing apparatus in accordance with the present invention, a plurality of support plates may be disposed by lining them up parallel to each other with a prescribed spacing and stacking in the plate thickness direction, and it is preferred that each of a plurality of support plates is provided with one or more openings for providing the plate with elastic properties.
Further, stacking a plurality of support plates (drive plates) also controls the above-described chatter vibrations caused by resonance, that is, demonstrates a vibration suppressing effect on the processing tool. First, vibrations caused by external forces acting in the inclined direction, are suppressed by the increase in rigidity in the inclined direction due to the increase in the number of drive palter. Further, if the number of drive plates is increased, then the vibrations of drive plates will interfere with each other and vibrations in the inclined direction and up-down direction (plate thickness direction) can be attenuated. Therefore, it is preferred that in the support plate of the processing apparatus in accordance with the present invention, a plurality of support plates be disposed by stacking in the plate thickness direction, so that the openings in the support plates that adjoin each other in the up-down direction are shifted with respect to each other. This is because when the openings in the stacked support plates (drive plates) are disposed with a displacement with respect to each other, the places in the plates that face each other have different phases of deformation. A configuration may be used in which the openings providing the plate with elastic property are formed in at least two support plates of a plurality of support plates, and the patterns of the openings in the two support plates differ, if viewed from the plate thickness direction of the support plates.
Further, it is also preferred that in the processing apparatus in accordance with the present invention, at least part of the openings be formed by a chemical removal process. With the processing apparatus of such configuration, because the openings are formed by a chemical removal process, the occurrence of strain concentration at the periphery of the openings can be suppressed, the strength and endurance against the resistance torque and drive torque during processing can be improved despite the increased number and size of the openings, flexibility in the up-down direction (direction perpendicular to the plate surface) of the support plate is increased and strength and endurance can be ensured.
Furthermore, it is preferred that the chemical removal process be etching and that the average surface roughness of the support plates subjected to the chemical removal process be 0.2 a or less. It is further desirable that the openings formed by the chemical removal process be chamfered by barrel polishing or after-etching.
The openings in the support plate are composed of curved or linear slits and almost round open portions formed at the ends of the slits and having a diameter larger than the width of the slits. With the processing apparatus of such configuration, because the openings comprise round open portions at the ends of the slits, the occurrence of stress concentration in the end portions of the openings is suppressed, the strength and endurance against the resistance torque and drive torque during processing can be improved despite the increased number and size of the openings, flexibility in the up-down direction (direction perpendicular to the plate surface) of the support plate is increased and strength and endurance can be ensured. Therefore, the openings may be composed of curved or linear slits and portions with a shape reducing shear stresses to which the support portion is subjected when the processing object is processed with the tool.
Further, in the processing apparatus of the above-described configuration, the support plate is preferably produced from a material with a tensile strength of 1000 N/mm²or higher, and this material is preferably an austenitic stainless steel. Further, the fatigue life of the support plate based on the maximum value of the equivalent stress amplitude to which the support portion is subjected when the processing object is processed with the tool is no less than the actual use period of the processing apparatus. Moreover, it is preferred that at least the support plate be placed in vacuum environment or environment of a substance with low chemical reactivity with respect to the constituent materials of the support plate during processing of the processing object with the tool.
On the other hand, in the method for the fabrication of a semiconductor device in accordance with the present invention, the processing object is a semiconductor substrate and the method comprises the step of planarizing the surface of the semiconductor substrate by using the processing apparatus of the above-described configuration. Further, the semiconductor device in accordance with the present invention is fabricated by this method for the fabrication of a semiconductor device.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present invention.
FIG. 1 is a front view illustrating the CMP apparatus which is a representative example of the processing apparatus in accordance with the present invention;
FIG. 2 is cross-sectional view illustrating the first embodiment of the polishing head constituting the CMP apparatus;
FIG. 3 is a schematic cross-sectional view of the polishing head;
FIG. 4 schematically simulates the structure of two stacked drive plates with a parallel spring;
FIG. 5 is a plan view illustrating an example of a drive plate used in the polishing head;
FIG. 6 is a perspective view illustrating the shape of a test piece for which the S-N curves shown in FIGS. 7 and 8 were found;
FIG. 7 is a graph illustrating the S-N curve relating to the test piece shown in FIG. 6 that was produced by laser processing and etching from stainless steel SUS304;
FIG. 8 is a graph showing the relationship between the equivalent stress amplitude σeq, mean stress σm, and cyclic stress amplitude σa;
FIG. 9 is a graph illustrating the S-N curve relating to the test piece shown in FIG. 6 that was produced by laser processing and etching from stainless steels SUS304 and SUS301;
FIG. 10 is a graph illustrating the relationship between tensile strength and fatigue limit;
FIG. 11 is an analytical drawing illustrating the pattern of deformations in the up-down direction and inclined direction of the drive plate analogous to the drive plate shown in FIG. 3;
FIG. 12 illustrates a deformation state of one of the two stacked drive plates;
FIG. 13 illustrates a deformation state of the other of two stacked drive plates, this figure shows a pattern obtained by shifting the drive plate shown in FIG. 11 through 36° in the rotation direction;
FIG. 14 shows one of the two drive plates provided with multiple spiral grooves;
FIG. 15 shows the other of the two drive plates provided with multiple spiral grooves, this figure shows a pattern obtained by forming the spiral grooves with the winding direction opposite to that of the drive plate shown in FIG. 14;
FIG. 16 shows a modification example of the drive plate shown in FIG. 14;
FIG. 17 shows a modification example of the drive plate shown in FIG. 15;
FIG. 18 is a flowchart illustrating a process for the fabrication of a semiconductor device;
FIG. 19 is a plan view illustrating the shape of the conventional drive plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be described hereinbelow with reference to the appended drawings. A CMP apparatus (chemical-mechanical polishing apparatus) which is a representative example of the polishing apparatus in accordance with the present invention is shown in FIG. 1. This CMP apparatus 1 comprises a wafer holding table 95 which can detachably attach and hold a wafer 90 as a polishing object on the upper surface side thereof and a polishing head 30 which is disposed in the position above the wafer holding table 95 and holds a polishing member 50 having a polishing pad 65 mounted thereon, this polishing pad facing the polish surface 91 of the wafer 90 held on the wafer holding table 95. In this CMP apparatus 1, the size (diameter) of the polishing pad 65 is less than the size (diameter) of the waver 90, which is the polishing object (in other words, the polishing pad 65 has a smaller diameter than the wafer 90) and the entire polish surface (upper surface) 91 of the wafer 90 can be polished by moving the polishing pad 65 with respect to the wafer 90, while maintaining contact therebetween.
A support frame 20 for supporting those wafer holding table 95 and polishing pad 30 comprises a horizontal stand 21, a first stage 21 so provided that it can move in the Y direction along a rail (not shown in the figure) provided in the extending condition in the Y direction (direction perpendicular to the paper sheet, this direction is considered as a front-rear direction) on the stand 21, a vertical frame 23 so provided as to extend vertically (Z direction) from the first stage 22, a second stage 24 so provided that it is free to move along the Z direction (up-down direction) on the vertical frame 23, a horizontal frame 25 so provided as to extend horizontally (X direction) from above the second stage 24, and a third stage 26 so provided that it can move in the X direction (left-right direction) on the horizontal frame 25.
A first electric motor M1 is provided in the first stage 22 and rotary driving the motor makes it possible to move the first stage 22 in the Y direction along the rail. A second electric motor M2 is provided in the second stage 24 and rotary driving the motor makes it possible to move the second stage 24 in the Z direction along the vertical frame 23. A third electric motor M3 is provided in the third stage 26 and rotary driving the motor makes it possible to move the third stage 26 in the X direction along the horizontal frame 25. Therefore, the third stage 26 can be moved to any position above the wafer holding table 95 by combining the rotary operation of the electric motors M1 to M3.
The wafer holding table 95 is mounted horizontally on the upper end portion of a rotary shaft 28 provided in extending condition vertically upward from a table support portion 27 provided on the stand 21. The rotary shaft 28 is rotated by rotary driving a fourth electric motor M4 provided inside the table support unit 27, thereby making it possible to rotate the wafer holding table 95 in the XY plane (horizontal plane).
The polishing head 30 is mounted on the lower end portion of a spindle 29 provided in extending condition vertically downward from the third stage 26. The spindle 29 is rotated by rotary driving a fifth electric motor M5 provided inside the third stage 26. As a result, the entire polishing head 30 can be rotated and the polishing pad 65 can be rotated in the XY plane (horizontal plane).
Further, the polishing head 30, as shown in FIG. 2, comprises an open-end cylindrical head housing 10 having an opening at the lower surface side which is linked via a linking member 11 with bolts B1 to the lower end portion of the spindle 29, a holding ring 31 mounted by using bolts B2 on the upper side portion inside the head housing 10, a ring member 32 mounted by using bolts B3 on the lower surface side of the holding ring 31, a disk-like drive plate 33 sandwiched at the outer peripheral portion thereof between those holding ring 31 and ring member 32, and the polishing member 50 mounted upon positioning on the lower surface side of the drive plate 33. Further, the opening of the head housing 10 is sealed by the polishing member 50 and a pressure chamber H1 is formed inside the head housing 10.
An air suction orifice 12 is formed in the central portion of the linking member 11 and the air from the air supply channel 80 so formed as to pass through the center inside the spindle 29 is passed through this air suction orifice 12 and supplied into the head housing 10 (pressure chamber H1). Further, the air supply channel 80 is connected to an air supply source (not shown in the figures) and the air pressure inside the head housing 10 can be adjusted to the desired pressure with the air supplied form the air supply source.
The drive plate 33 is produced from a metal sheet such as an austenitic stainless steel sheet. In this drive plate, as shown in detail in FIG. 5, multiple openings 33 b, c arranged along the concentric circles are formed, as shown in the figure, in the disk having a round hole 33 a formed in the center thereof. Each opening 33 b is composed of a slit 33 d extending in the circumferential direction and round open portions 33 g having a diameter larger than the slit width and formed at both ends of the slit 33 d. The openings 33 c formed on the innermost periphery and outermost periphery are composed only of slits 33 d. As for the openings 33 b in the intermediate portions, because stresses generated at both ends of slits 33 d increase when a wafer is polished, the round open portions 33 g are provided to prevent stress concentration and reduce the generated stresses. On the other hand, in the slits 33 c on the innermost periphery and outermost periphery, stresses generated during polishing are small and it is suffice to employ only the slits 33 d. Furthermore, the drive plates 33 are arranged as a stack of two drive plates in the up-down direction (plate thickness direction). Such a two-plate arrangement will be described below.
The polishing member 50 comprises a disk-like reference plate 51 positioned and mounted on the lower surface side of the drive plate 33 and a polishing tool 60 detachably mounted by vacuum suction on the lower surface of the reference plate 51. The reference plate 51 is formed as a disk provided with a step wherein the outer diameter of the upper portion thereof is slightly less than the inner diameter of the ring member 32, and the outer diameter of the lower portion thereof is somewhat less than the inner diameter (that is, the opening diameter) of a flange 10 a at the lower end of the head housing 10. Further, the reference plate 51 closes the opening of the head housing 10, seals the inside of the head housing 10, and forms the pressure chamber H1 inside the head housing 10.
A disk-like central member 55 having a radius somewhat less than that of the round hole 33 a of the drive plate 33 is fixed with bolts B4 to the upper surface side in the central portion of the reference plate 51, and the inner peripheral portion of the drive plate 33 which is aligned with this central member 55 is sandwiched between the reference plate 51 and a fixing ring 56 fixed with bolts B5 to the upper surface side of the reference plate 51. The reference plate 51 is thus fixed to the head housing 10 via the drive plate 33, and the rotary drive force of the spindle 29 is transmitted to the reference plate 51 via the drive plate 33.
Further, the outer diameter of a flange 51 a protruding outwardly from the outer peripheral portion of the reference plate 51 is larger than the inner diameter of the flange 10 a protruding inwardly from the inner peripheral portion at the lower end of the head housing 10, and the reference plate 51 is prevented from coming out of the head housing 10.
The polishing tool 60 is composed of a disk-like pad plate 61 having a diameter almost equal to that of the reference plate 51 and a round polishing pad (polishing cloth) 65 mounted on the polishing pad mounting source 61 a which is the lower surface of the pad plate 61. Here, because the polishing 65 is an expendable product which degrades in the course of polishing, it is detachably mounted on the polishing pad mounting surface 61 a (for example, with an adhesive) and can be easily replaced. Further, the lower surface side of the polishing pad 65 serves as a polishing surface 66 facing the polish surface 91 of the wafer 90.
As shown in FIG. 2, an air intake channel 71 having a plurality of suction openings at the lower surface side thereof is formed inside the reference plate 51. This air intake channel 71 extends also to the central member 55 and opens at the side of the pressure chamber H1 of the head housing 10. An intake pipe 72 extending inside the air supply channel 80 of the spindle 29 is connected to this open portion, and the pad plate 61 can be suction mounted on the reference plate 51 by taking air in from the intake pipe 72 after the pad plate 61 has been placed on the lower surface side of the reference plate 51. Here, the alignment of the pad plate 61 and positioning thereof in the rotation direction is conducted with a center pin P1 and positioning pin P2 provided between the pad plate 61 and reference plate 51.
Furthermore, a polishing agent supply tube 81 connected to a polishing agent supply unit (not shown in the figures) extends in the air supply channel 80 and is connected via a connection tool 82 positioned between the spindle 29 and the central member 55 to a flow channel 83 so provided as to pass through the central member 55, a flow channel 84 passing through inside the center pin P1, a flow channel 85 provided inside the pad plate 61, and a flow channel (not shown in the figure) provided in the polishing pad 65.
Further, the ring member 32 is formed to have a ring-like shape with an inner diameter slightly larger than the outer diameter of the upper portion of the reference plate 51. This ring member surrounds the upper portion of the reference plate 51 located inside the head housing 10 and is so composed that a prescribed gap S1 appears between the inner peripheral surface of the ring member 32 and the outer peripheral surface of the upper portion of the reference plate 51. Further, the air pressure inside the pressure chamber H1 is received by the upper surface in the center of the reference plate 51, and the reference plate 51 mounted and held on the lower surface side of the drive plate 33, that is, the polishing member 50 can move reciprocally in the up-down direction (toward the polish surface 91).
As a result, because the inner diameter of the ring member 32 is slightly larger than the outer diameter of the upper portion of the reference plate 51, the cross-sectional area of the gap S1 becomes extremely small, and the air located inside the pressure chamber H1 that was formed inside the head housing 10 is prevented from flowing out from the pressure chamber H1 through this gap S1. Therefore, the pressure chamber H1 can be formed inside the head housing 10, without using special sealing means such as a rubber sheet. The elastic deformation of the rubber sheet and the effect of the elastic force thereof on the reference plate 51 (polishing member 50) are thus eliminated. Therefore, the linearity of propulsion force of the polishing member 50 (polishing pad 65) with respect to the air pressure inside the head housing 10 can be improved. Further, control performance in a pressurizing control conducted when the polishing pad 65 is pressed against the wafer 90 can be improved and processing accuracy of the wafer 90 can be increased.
Further, a labyrinth space H2 communicating with the pressure chamber H1 via the gap S1 is formed between the lower surface side of the ring member 32 and the upper surface side of the edge portion of the reference plate 51, and an air release passage 13 linked to this labyrinth space H2 is formed in the side portion of the head housing 10. The air release passage is formed to extend to an air release opening 14 formed at the side surface side of the head housing 10, and the air present inside the head housing 10 passes from the labyrinth space H2 through the air release passage 13 and air release opening 14 and is released to the outside of the head housing 10.
A joint 15 and an air release tube 16 are mounted in the air release opening 14, and the air release passage 13 is linked to the air release tube 16 via the joint 15. The air release tube 16 is linked to a vacuum source (not shown in the figure) and the air pressure inside the head housing 10 can be reduced and adjusted to the described pressure. As a result, because the air release opening 14 is formed separately from the air suction opening 12, the air pressure inside the head housing 10 can be rapidly reduced and adjusted to the desired pressure, and the control rate in pressurizing control conducted when the polishing pad 65 is pressed against the wafer 90 can be increased.
In order to conduct polishing of the wafer 90 by using the CMP apparatus 1 of the above-described configuration, first, the wafer 90 which is the polishing object is suction mounted on the upper surface of the wafer holding table 95 (in this process, the center of the wafer 90 is aligned with the rotation center of the wafer holding table 95) and the wafer holding table 95 is rotated by driving the electric motor M4. Then, the electric motors M1 to M3 are driven, the third movement stage 26 is positioned above the wafer 90, the spindle 29 is driven with the electric motor M5, and the polishing head 30 is rotated. The electric motor M2 is then driven, the third stage 26 is lowered, and the lower surface of the polishing pad 65 (polishing surface) is pressed against the upper surface (surface which is to be polished) of the wafer 90.
Then, the air pressure inside the pressure chamber H1 is adjusted and the contact pressure of the wafer 90 and the polishing pad 65 is set to the prescribed value by supplying air from the air supply source into the head housing 10 or releasing the air from the head housing 10 by using the vacuum source. The electric motors M1, M3 are then driven, and the polishing head 30 is caused to swing in the XY direction (the in-plane direction of the contact surface of the wafer 90 and the polishing pad 65). At the same time a polishing agent (liquid slurry comprising silica particles) is fed under pressure from the polishing agent supply unit and the polishing agent is supplied to the lower surface side of the polishing pad 65. As a result the polish surface 91 of the wafer 90 is polished by the rotary movement of the wafer 90 itself and the rotary and swinging movement of the polishing head 30 (that is, the polishing pad 65), while the polishing agent is being supplied.
When the polish surface 91 of the wafer 90 is thus polished, because the polishing member 50 comprising the polishing pad 65 is supported by the head housing 10 via the drive plate 33, the posture of the polishing member 50 changes according to the inclination or roughness of the polish surface 91 under the effect of elastic deformation of the drive plate 33, and the polish surface 91 is uniformly polished.
As a result, decreasing the cross-sectional area of the gap S1 between the ring member 32 and reference plate 51 (polishing member 50) makes it possible to form the pressure chamber H1 inside the head housing 10, without using sealing means such as a rubber sheet, because the air present inside the pressure chamber H1 that was formed inside the head housing 10 is prevented form passing through the gap S1 and flowing out to the outside of the pressure chamber H1. For this reason, the elastic deformation of the rubber sheet and the effect of the elastic force thereof on the reference plate 51 (polishing member 50) are thus eliminated. Therefore, the linearity of propulsion force of the polishing member 50 (polishing pad 65) with respect to the air pressure inside the head housing 10 can be improved. Further, control performance in pressurizing control conducted when the polishing pad 65 is pressed against the wafer 90 can be improved and processing accuracy of the wafer 90 can be increased.
Two drive plates 33 were stacked (as described hereinabove), but here we will first consider the deformation of a single plate 33 and the internal stresses generated during polishing. As described hereinabove, the drive plate 33 comprises multiple openings 33 b, 33 c′ arranged along the concentric circles. Therefore, when a force acts in the up-down direction (direction perpendicular to the drive plate surface) upon the inner peripheral portion 33 h thereof after the outer peripheral portion 33 f thereof has been fixed to the outer periphery at the lower end of the head housing 10, the amount of deformation in the up-down direction of the inner peripheral portion 33 h caused by elastic deformation of the drive plate 33 is substantially larger than that when no openings are provided. Thus, an elastic constant of elastic deformation of the drive plate 33 in response to the movement of the inner peripheral portion 33 h decreases. For this reason, the polishing tool 50 which is mounted by bonding to the inner peripheral portion of the drive plate 33 can move pliably in the up-down direction, the polishing tool 50 moves or tilts in the up-down direction following the inclination or roughness of the polish surface 91 of the substrate 90, the posture of the polishing member changes pliably, and the polish surface 91 is uniformly polished with good accuracy.
However, because the drive plate 33 transmits the rotation of the spindle 29 from the head housing 10 to the polishing tool 50, it serves to cause the rotation of the polishing tool integrally with the spindle 29. Therefore, the drive plate is required to have a sufficient strength to transmit the drive torque necessary for such a rotation. For this reason, the following measures were taken to provide the drive plate 33 with sufficient strength.
First, polishing agents comprise polishing liquids such as strong acids and strong alkalis, and the drive plate 33 can be exposed to such polishing liquids. In particular, when the drive plate 33 is detached for maintenance, there is a risk of splashed polishing liquid adhering to the drive plate and causing rust or corrosion. Such rust and corrosion decrease the endurance of the drive plate 33. Another problem is that the rust that appeared on the drive plate contaminates the substrate (wafer) 90 or the parts of the polishing apparatus. For this reason, the drive plate 33 has been produced from a stainless steel (SUS) material, and among stainless steel materials, austenitic stainless steel that has corrosion resistance superior to that of martensitic steels was used. From the standpoint of yield strength and elasticity, there are materials superior to stainless steels (for example, beryllium copper), but such materials require plating for corrosion protection, and if plating is conducted with the aim of protecting the metal against corrosion, the yield strength and elastic properties thereof are typically degraded due to hydrogen embitterment. Because of this problem and the problem of possible peeling of the plated layer and also because of cost and reliability considerations, stainless steel becomes the most suitable material.
The drive plate 33, as shown in FIG. 5 is produced by forming multiple openings 33 b, c. The formation of those openings 33 b, c has conventionally been conducted by laser processing and pressing. Stainless steel materials have a high cold rolling ratio, but the material strength typically cannot be expected to increase in quenching. Therefore, hardness and tensile strength have been increased by compression processing during cold rolling. In other words, the material strength was increased by introducing strains and stresses into the crystal structure by compressive forces. When the drive plate 33 is fabricated by forming the openings 33 b, c by laser processing of such stainless steel materials, the problem is that the cut surface which received the laser processing heat assumes an annealed state, strains and stresses contained therein are relieved, and the strength of the cut surface is decreased. Another problem is that the cut surface which was subjected to laser processing is a rough processed surface with a large number of small peaks and valleys, stress concentration easily occurs therein, and the fatigue strength decreases. On the other hand, when the openings 33 b, c are formed by pressing, stress relieving by heat as in the laser processing is avoided, but burrs and shear drops appear on the cut surface and a large number of small peaks and valleys are present therein. As a result, stress concentration occurs and strength (in particular, fatigue strength) decreases.
With the foregoing in view, in accordance with the present invention, the drive plate 33 is produced by processing a sheet of a stainless steel material by a chemical removal process (for example, by etching) conducted so as to obtain a disk-like shape shown in FIG. 5 which has a round hole 33 a in the center and multiple openings 33 b, c. When chemical removal processing such as etching is thus conducted, the decrease in fatigue strength is small. Therefore, the service life of the drive plate obtained by such processing can be longer than that of the drive plates produced by the conventional laser processing or pressing, provided that the drive plates have the same shape.
To confirm the above-described assumptions, the inventors have produces a rectangular test piece 110 having a notched portion 111 shown in FIG. 6 from a stainless steel material SUS304-CSP-H and tested the fatigue life of the test piece by applying a tensile cyclic load F to both ends thereof. In the test, fatigue fracture originated in the plane 112 passing through the notched portion 111. Accordingly, FIG. 7 shows a S-N curve based on the test results, this curve representing the relationship between the equivalent stress amplitude σeq acting upon the plane 112 and the number of cycles N (fatigue life). Line A in the figure represents test results obtained when the test piece 110 was produced by etching, and line B represents test results obtained when it was produced by laser processing. Those results clearly demonstrate that though the materials and shapes were the same, longer fatigue life was obtained with the test piece produced by etching. Further, the equivalent stress amplitude σeq means a stress amplitude σeq at which the equivalent life is obtained when a mean stress σm becomes zero, where the stress with an amplitude σa acts, as shown in FIG. 8, with a mean stress σm. The equivalent stress amplitude can be found from the following equation:
σeq=σa/{1−(σm/σB)} (1)
where σB is tensile strength.
The inventors have also conducted a comparative fatigue life test in which a test piece with the shape shown in FIG. 6 was produced by laser processing from different materials. The S-N curves based on the results obtained are shown in FIG. 9. In this figure, line C represents test results for a test piece produced by laser processing from stainless steel SUS304-CSP-H in the same manner as described above, and line D represents test results for a test piece produced by laser processing from stainless steel SUS301-CSP-EH. Those results demonstrated that SUS301 test piece had longer life than that from SUS304.
As explained hereinabove, in case of etching processing, because strains are not relieved by processing heat, the problem of strength decrease at the processed surface is avoided and the processed surface is smooth and have small peaks and valleys. Therefore, stress concentration hardly occurs and the above-described long service life can be obtained. However, when etching is conducted, a rectangular shape with sharp corners (ridge portions) of the openings and pointed cross section is obtained. Therefore, any impact can damage the corners, thereby forming peaks and valleys. For this reason, after the openings 33 b, c have been formed by etching in the drive plate 33, the corners were rounded by conducting after-etching in which the entire mask was stripped and the entire surface was again exposed to the liquid etchant. Barrel polishing may be employed instead of after-etching.
Further, from the standpoint of fatigue life of the drive plate 33, it is preferred that the surface of the drive plate 33 be smoothed out and the peaks and valleys causing stress concentration be removed as thoroughly as possible. For this purpose, in the drive plate 33 of the present embodiment, the fatigue strength was further increased by mirror finishing the surface of the drive plate 33 to obtain a surface roughness Ra<0.2 a.
In carbon steels and structural alloys, the correlation between tensile strength and tension-compression fatigue limit of the material is known to be within a hatched region sandwiched between lines E and F, as shown in FIG. 10. This relation demonstrates that a strong positive correlation can be observed between tensile strength and tension-compression fatigue limit in the vicinity of a tensile strength of 100 kg/mm²(about 1000 N/mm²), but at a higher tensile strength, the correlation decreases. In other words, if a material with a tensile strength of 100 kg/mm²(about 1000 N/mm²) or less is used, the fatigue limit changes according to the tensile strength, but a maximum fatigue life is normally obtained if a material with a tensile strength of 100 kg/mm²(about 1000 N/mm²) or higher is used. For this reason, in the present embodiment, the drive plate 33 was produced from a stainless steel material with a tensile strength of 100 kg/mm²(about 1000 N/mm²) or higher. The two stainless steels SUS301 and SUS304 used for the test illustrated by FIG. 9 had a tensile strength of 100 kg/mm²(about 1000 N/mm²) or higher.
With the aforesaid in view, it is preferred that the drive plate 33 be produced by forming stainless steel SUS301-CSP-EH by etching to obtain the shape shown in FIG. 5, 10 followed by after-etching and mirror finishing to a surface roughness of 0.2 a or less. However, the drive plate in accordance with the present invention is not limited to the above-described process and a variety of other modes, such as etching of stainless steel SUS304, can be considered. Specific is shapes are described below on specific examples.
Stacking of drive plates 33 will be explained below.
The effect obtained with the above-described drive plate 33 is that the occurrence of stress concentration around the openings can be suppressed, strength and endurance with respect to a drive torque or resistance torque during processing conducted after the number or size of the openings has been increased can be improved, flexibility of the support plate in the up-down direction (direction perpendicular to the plate surface) is increased (rigidity is decreased), and strength and endurance can be ensured. However, when only one drive plate 33 was used, simply increasing the number or size of the openings or decreasing the plate thickness was insufficient for reducing the rigidity in the up-down direction (plate thickness direction) and the decrease in rigidity of the drive plate 33 in the up-down direction was at the same time also connected to the decrease in rigidity of the plate 33 in the inclined direction. More specifically, in the case of the drive plate 33 provided with flexibility by openings such as slits, in a linear region of the microdeformation range, the rigidity in both the up-down direction (plate thickness direction) and the inclined direction of the drive plate 33 was found to change almost with the third power of plate thickness. This is apparently because both the deformation in the up-down direction and the deformation in the inclined direction proceed as bending of the bridge portions between the openings (slits) and the deformation components are identical, as shown in FIGS. 11(a), (b). Therefore, if the drive plate 33 is composed of one plate, the rigidity in the inclined direction is difficult to maintain within the prescribed range at the same time, while reducing the rigidity in the up-down direction (plate thickness direction) at the same time, and once the polishing tool 60 (in particular, the polishing pad 65) which is held by the polishing head 30 via the drive plate 33, as described hereinabove, protrudes beyond the wafer surface 91 and overhangs during swinging, the inclination of the polishing tool 60 cannot be restored and stresses concentrate at the edge circumference of the wafer.
In accordance with the present invention, the drive plate 33 is composed of at least two stacked plates in order to resolve this problem. If two drive plates are stacked, not only the rigidity in the up-down direction and tilting direction are simply doubled, but also +αrigidity is provided in the tilting direction by a parallel elastic effect (described hereinbelow). As a result, the rigidity in the up-down direction (plate thickness direction (pressurizing direction)) and the rigidity in the tilting direction of the stacked drive plates 33 can be controlled independently and set to attain the desired balance. Furthermore, for example, when the rigidity in the up-down direction is increased by employing two drive plates and the allowed range of pressure change accompanying the wear of the polishing pad 65 is exceeded, using a stack of two plates with a thickness 1/³{square root}{square root over ( )}2 that of one drive plate 33 which is within the allowed range makes it possible to increase the rigidity in the inclined direction, while maintaining the rigidity in the up-down direction, and the polishing tool 60 can be effectively prevented from tilting.
Furthermore, stacking two drive plates 33 is also effective for suppressing the below-described chatter vibrations occurring during polishing. The two drive plates 33 are stacked upon turning one with respect to another through a prescribed angle in the XY plane shown in FIG. 1. The prescribed angle as referred to herein is set according to the number of slits disposed on concentric circles in the circumferential direction of the drive plates. More specifically, in the drive plate 33 shown in FIG. 5, three slits 33 d are provided on concentric circles. Therefore, vibrations with three wavelengths per one cycle are produced, one wavelength is 360°:3 wavelengths=120°, and if two drive plates 33 are arranged with a 120°:2=60° shift (half wavelength), then the peaks and valleys of the vibrations will overlap, interference will occur between the two plates, and an attenuation effect will be produced. FIGS. 12, 13 illustrate a case in which two drive plates 33′ similar to that shown in FIG. 5, but having five slits in one circle are shifted with respect to each other and deformed in the inclined direction. In this case, the drive plates 33′ are shifted through the prescribed angle of 36° calculated by the above-described computational method (360°:5 wavelengths:2), and the vibrations of the drive plate 33′ shown in FIG. 12 and the drive plate 33′ shown in FIG. 13 which are shifted by 36° mutually interfere and attenuate each other. In other words, if the two drive plates 33 are so arranged that the vibrations in the opposing positions of the plates are in almost opposite phases, then the chatter vibrations can be suppressed.
In the explanation hereinabove, drive plates 33, 33′ shown in FIG. 3 or FIGS. 12, 13 similar thereto were considered, but drive plates of other shapes can be also employed. In particular, those drive plates that could not be employed in the conventional systems composed of one drive plate can be used in stacks of a plurality thereof. Further, the methods for processing and materials of the two drive plates 333, 433 that will be discussed as examples can be understood by referring to the explanation of the drive plate 33 shown in FIG. 5 that was discussed hereinabove.
The drive plate 333 provided with multiple spiral grooves 333 a will be explained with reference to FIG. 14. The advantage of this plate 333 is that the rigidity in the up-down direction (direction of paper sheet surface) can be greatly reduced because one groove 333 a can have a very large length. On the other hand, when a rotary force acted in the W direction shown in FIG. 14, the bridge portions were easily buckled. As a result, the conventional system composed of one drive plate could not be used. On the other hand, the drive plate 333 shown in FIG. 14 features a high strength against the rotary force in the direction opposite to the W direction. Therefore, if a stacking method in accordance with the present invention is used, then stacking with the drive plate 333 having spiral grooves 333 b (see FIG. 15) with a winding direction opposite to that of the spiral grooves 333 a shown in FIG. 14 will make it possible to obtain a high rigidity of one of the two plates and to avoid buckling, regardless of the direction of rotary force action.
Furthermore, drive plates 433 shown in FIGS. 16, 17 can be also employed as modification examples of the drive plates 333 equipped with the spiral grooves 333 a shown in FIGS. 14, 15. The drive plates 433 shown in FIGS. 16, 17 correspond to drive plates 333 shown in FIGS. 14, 15, respectively.
An embodiment of the method for the fabrication of a semiconductor device in accordance with the present invention will be described below. FIG. 18 is a flow chart illustrating the semiconductor device fabrication process. When the semiconductor fabrication process is started, first, in step S200, an adequate treatment process is selected from those of the below-described steps S201 to S204 and the processing flow advances to that step.
Here, step S201 is an oxidation process for oxidizing the substrate surface. Step S202 is a CVD process for forming an insulating film or dielectric film on the substrate surface by CVD or the like. Step S203 is an electrode formation process for forming electrodes on the wafer by deposition or the like. Step S204 is an ion implantation process for implanting ions into the wafer.
After the CVD process (S202) or electrode formation process (S203), the processing flow advances to step S205. Step S205 is a CMP process. The CMP process comprising a step of flattening the interlayer insulating film, polishing the metal film present on the semiconductor device surface, or polishing the dielectric film with the polishing apparatus in accordance with the present invention. A damascene process can be also employed.
Upon completion of the CMP process (S205) or oxidation process (S201), the processing flow advances to step S206. Step S206 is a photolithography process. In this process, a resist is coated on the wafer, the circuit pattern is baked onto the wafer by exposure using an exposure device, and the exposed wafer is developed. Further, the next step S207 is an etching process in which portions other than the developed resist image are removed by etching, then resist peeling is conducted, and the resist that became unnecessary after etching was completed is removed.
Then, in step S208, a decision is made as to whether the entire necessary process was completed, and if it were not completed, the processing flow returns to step S200, subsequent steps are repeated, and a circuit pattern is formed on the wafer. If a decision were made in step S208 that the entire process has been completed, the processing ends.
With the method for the fabrication of semiconductor devices in accordance with the present invention, processing accuracy and yield of wafers are increased because the polishing apparatus in accordance with the present invention is used in the CMP process. As a result, semiconductor devices can be fabricated at a lower cost than with the conventional method for the fabrication of semiconductor devices. Furthermore, the polishing apparatus in accordance with the present invention may be also used in CMP of semiconductor device fabrication processes other than the above-described semiconductor device fabrication process. The semiconductor devices fabricated by the semiconductor device fabrication method in accordance with the present invention are high-yield and low-cost semiconductor devices.
In the above-described embodiment of the processing apparatus in accordance with the present invention, the explanation was conducted with respect to a CMP apparatus using a plurality of drive plates and having a slit pattern formed by a chemical removal process. However, the present invention is not limited to such an apparatus, and it is obvious to a person skilled in the art that the technological concept of the present invention can be easily diverted to other processing apparatuses which require that the relative positions of the tool and processing object be traced.
As described hereinabove, arranging a plurality of support plates (drive plates) of a processing apparatus in a row in accordance with the present invention makes it possible to attain “the decrease in rigidity in the up-down direction (plate thickness direction)” and at the same time “to ensure the appropriate rigidity in the inclined direction”, while “ensuring rigidity and endurance against the torque or swinging direction”. Further, with the processing apparatus in accordance with the present invention, the so-called chatter vibrations generated in the tool—tool holder configurations can be also suppressed.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

RELATED APPLICATIONS

This application claims the priority of Japanese Patent Application No.2003-155319 filed on May 30, 2003 which is incorporated herein by reference.

Claims

1. A processing apparatus comprising an object holding unit for holding a processing object, a tool holding unit for holding a tool for processing said processing object, and a relative movement mechanism for causing relative movement of the processing object held in said object holding unit and the tool held in said tool holding unit, while maintaining contact therebetween, wherein

said object holding unit and/or said tool holding unit are composed of a plurality of support plates of almost flat shape having elastic property which are arranged in a row.

2. The processing apparatus according to claim 1, wherein said plurality of support plates are disposed by stacking in a row in the plate thickness direction.

3. The processing apparatus according to claim 2, wherein said plurality of support plates are disposed by lining up parallel to each other with a prescribed spacing and stacking in the plate thickness direction.

4. The processing apparatus according to claim 2, wherein said plurality of support plates have formed therein at least one opening providing them with said elastic property, and said plurality of support plates are disposed by stacking in the plate thickness direction, so that the openings in said support plates that adjoin each other in the vertical direction are shifted with respect to each other.

5. The processing apparatus according to claim 2, wherein an opening providing with said elastic property is formed in at least two support plates of said plurality support plates, and the patterns of said openings in said two support plates differ, if viewed from the plate thickness direction of said support plates.

6. The processing apparatus according to claim 4 or 5, wherein at least part of said openings is formed by a chemical removal process.

7. The processing apparatus according to claim 6, wherein said chemical removal process is etching.

8. The processing apparatus according to claim 6, wherein an average surface roughness of said support plates subjected to said chemical removal process is 0.2 a or less.

9. The processing apparatus according to claim 6, wherein said openings formed by said chemical removal process are chamfered by barrel polishing or after-etching.

10. The processing apparatus according to claim 4 or 5, wherein said openings are composed of curved or linear slits and almost round open portions formed at the ends of said slits and having a diameter larger than the width of said slits.

11. The processing apparatus according to claim 4 or 5, wherein said openings are composed of curved or linear slits and opening portions with a shape reducing shear stresses to which said support portion is subjected when said processing object is processed with said tool.

12. The processing apparatus according to any of claims 1 to 5, wherein said support plate is produced from a material with a tensile strength of 1000 N/mm²or higher.

13. The processing apparatus according to claim 12, wherein said material is an austenitic stainless steel.

14. The processing apparatus according to any of claims 1 to 5, wherein the fatigue life of said support plate based on the maximum value of the equivalent stress amplitude to which said support portion is subjected when said processing object is processed with said tool is no less than the actual use period of said processing apparatus.

15. The processing apparatus according to any of claims 1 to 5, wherein at least said support plate is placed in vacuum environment or environment of a substance with low chemical reactivity with respect to the constituent materials thereof during processing of said processing object with said tool.

16. A method for the fabrication of a semiconductor device, wherein

said processing object is a semiconductor wafer, and

the surface of said semiconductor wafer is planarized by using the processing apparatus described in any of claims 1 to 5.

17. A semiconductor device fabricated by the method for the fabrication of a semiconductor device described in claim 16.