JP2011124302A - Low center of gravity airbag type polishing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem: balls corresponding to inclination of a work head plate are intervened, a gimbal point becomes high, a pressure applied downward to the work head plate is hardly averaged, stabilization is not achieved because a wafer cannot follow subtle inclination of a polishing head in the outer periphery, resulting in a factor of flyout of the wafer in lifting up the polishing head. <P>SOLUTION: The polishing head includes: a spindle shaft 1; a head holding member 3 integrally having a cylindrical upper portion 3a and a cup-like lower portion 3b; an outer spherical bearing 4; a plurality of drive pins 5; an inner spherical bearing 6; a head body 7 on which a plurality of drive pin inserting holes 7b for inserting the drive pins 5 are engraved; a circular airbag 8; a flexible film 10; and a connecting bolt 11. A gimbal point P formed by the outer spherical surface bearing 4 and the inner spherical bearing 6 is matched with the lower surface of the flexible film 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a low center-of-gravity airbag type polishing head, and more specifically, in a CMP polishing apparatus in which a semiconductor wafer is adhered to a flexible film on a lower surface with a water-filled or adhesive layer and polished with a polishing cloth. The present invention relates to a low center-of-gravity airbag type polishing head in which a gimbal point by a spherical bearing coincides with the lower surface of a flexible film.

  There are remarkable technological innovations that are not relaxed at present, and due to the development of its advanced technology, many excellent various product groups have been sent out, especially MEMS devices or NEMS devices used in electronic related equipment such as computers and microcomputers. Various types of semiconductor wafer grinding devices in the process of manufacturing have been developed and used, and semiconductor wafers that are required to be ground in recent years are extremely thin from the viewpoint of miniaturization of devices to be mounted, The diameter is increased from the viewpoint of productivity, and the entire surface from the viewpoint of yield is flat processing and mirror surface processing with uniformity with ultra-high accuracy, and is extremely thinned, expanded in diameter, and material characteristics. Is surpassing how hard and brittle semiconductor wafers are finished with ultra-high accuracy and efficiency.

For this purpose, for example, a metal bearing previously disclosed by the present applicant, in which a spherical bearing 4 is interposed between the spindle shaft 2 and the work head 3, the center hole 5a is opened, and the flange portion 5b is bulged. The suspension 5, the sun sphere 4 a of the spherical bearing 4, the concave receiving portion 4 b, the gap portion 4 c, a large number of planetary spheres 4 d embedded in the concave receiving portion 4 b, the pressurizing chamber 3 a formed in the work head 3, And a flexible membrane 6 stretched on the pressure chamber 3a, and a fluid flow system 7 for expanding and contracting the flexible membrane 6 by flowing a gel-like fluid into the pressure chamber 3a is a spindle on which the solar sphere 4a is fixed. The main shaft 6, the spherical bearing 4, the holding plate 3, and the leaf spring disclosed in the art, in which the shaft center of the shaft 2, the center hole 5 a of the metal suspension 5 and the work head 3 are communicated (see Patent Document 1), and others. 2 or the like. The workpiece 9 is mounted on the lower surface of the holding plate 3, the holding plate 3 is connected to the lower end portion of the main shaft 6 via the spherical bearing 4 and the leaf spring 2, and the main shaft 6 is connected to the rotation drive mechanism. The spherical bearing 4 has a tilt center on the rotation axis of the main shaft 6. The leaf spring 2 has an axisymmetric shape, has an opening 27 in the center, and has a plurality of arm portions 21 extending radially in the outer peripheral portion. A mounting hole 25 is formed along the inner periphery of the leaf spring 2, and the support plate 1 is coupled thereto. A mounting hole 26 is formed at the tip of each arm portion 21, and the holding plate 3 is coupled thereto. The mounting hole 26 and the mounting hole 25 are located on two large and small concentric circles centered on the rotation axis of the main shaft 6 (see Patent Document 2), and the polishing apparatus includes a base (23), A turntable (27), a polishing pad (29), and a drive mechanism (45) for rotating the polishing head (63) are included. The polishing head holds at least one wafer (35) and meshes the surface of the wafer with the work surface of the polishing pad. A spherical bearing assembly (75) places the polishing pad (63) on the drive mechanism and pivots the polishing head about the gimbal point (p). When the polishing head holds the wafer so as to mesh with the polishing head, the gimbal point is not higher than the workpiece surface. This pivoting allows the wafer surface to continuously self-align so that the pressure on the wafer surface is equal, while the polishing head is rotated by a drive mechanism. This discloses a semiconductor wafer, particularly one that performs more uniform polishing in the vicinity of the lateral edge of the wafer (see Patent Document 3) and the like while maintaining the surface and the workpiece surface in a continuous parallel relationship. Yes.
JP 2008-284634 A (FIG. 1) Japanese Patent Laid-Open No. 10-118919 (FIG. 1) Japanese translation of PCT publication No. 2004-520705 (FIG. 1)

  However, each of Patent Documents 1 to 3 is provided with a spherical bearing so as to correspond to the inclination of the work head plate, but as shown in FIG. 1, a spherical surface is provided on the upper surface of the work head plate. A bearing is provided, but a sphere is interposed, the gimbal point becomes high, and it is difficult to average the pressure applied downward on the work head plate for polishing the wafer with ultra-high accuracy. Yes, even if the average can be achieved at the center side, the outer periphery cannot follow the slight tilt of the polishing head and cannot be stabilized, and this causes the flyout of the wafer when lifting the polishing head, Each had problems.

  In view of the above-mentioned problems, the present invention solves these problems as a result of diligent research, and includes a spindle shaft that is provided so as to be movable up and down and rotatable, and a connecting member interposed at the lower end of the spindle shaft. A head holding member integrally provided with a cylindrical upper portion for fixing and a cup-shaped lower portion having an opening at the bottom, an outer spherical bearing provided inside the cup-shaped lower portion of the head holding member, and a cup shape of the head holding member A plurality of drive pins for transmitting the rotational force projecting from the lower edge, an inner spherical bearing to be joined to the outer spherical bearing, an annular groove for fixing the inner spherical bearing, and a plurality of drive pins to be inserted through the plurality of drive pins A head body which is engraved with a drive pin insertion hole and has a connecting cylindrical portion standing upward, and a head surface which protrudes slightly from the lower surface of the head body. An annular airbag fixed to the periphery of the body, a flexible film stretched by a back plate on the lower surface of the airbag, and a connection bolt for connecting the head body and the connection member. The gimbal point by the outer spherical bearing and the inner spherical bearing is made to coincide with the lower surface of the flexible film.

  The low center-of-gravity airbag type polishing head of the present invention configured as described above has a gimbal point by an outer spherical bearing housed inside the cup-shaped lower portion of the head holding member and an inner spherical bearing fitted to the outer spherical bearing. It can be matched with the flexible film stretched on the lower surface of the head body, and an air bag is interposed above the flexible film, so that it can sufficiently follow the delicate inclination of the wafer to be polished. It is possible to average the pressing force over the entire polishing surface even with a slight inclination during polishing, and to minimize the flyout of the wafer when lifting the polishing head. It is a novel invention.

  The embodiment of the low center of gravity airbag type polishing head of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic explanatory view of a grinding apparatus of an embodiment of the low center of gravity airbag type polishing head of the present invention. is there.

  The present invention relates to a low center-of-gravity airbag type polishing head, and more specifically, in a CMP polishing apparatus in which a semiconductor wafer is adhered to a flexible film on a lower surface with a water-filled or adhesive layer and polished with a polishing cloth. The present invention relates to a low center-of-gravity airbag type polishing head characterized in that the gimbal point of a spherical bearing is made to coincide with the lower surface of the flexible membrane, and a spindle shaft 1 provided so that the polishing apparatus can be raised and lowered and rotated, A head holding member 3 integrally including a cylindrical upper part 3a for fixing a connecting member 2 to a lower end of the spindle shaft 1 and a cup-like lower part 3b having an opening at the bottom, and the head holding member The outer spherical bearing 4 housed inside the cup-shaped lower part 3b of 3 and the rotational force protruding from the edge of the cup-shaped lower part 3b of the head holding member 3 are transmitted. A plurality of drive pins 5, an inner spherical bearing 6 fitted to the outer spherical bearing 4, an annular groove 7 a for fixing the inner spherical bearing 6, and a plurality of drive pin insertions for inserting the plurality of drive pins 6. A head main body 7 engraved with a hole 7b and provided with a connecting cylindrical portion 7c upright, and an annular airbag fixed to the circumference of the head main body 7 with its lower surface slightly protruding from the lower surface of the head main body 7 8, a flexible membrane 10 stretched on the lower surface of the airbag 8 with a back plate 9 interposed therebetween, and a connection bolt 11 for connecting the head body 7 and the connection member 2. The gimbal point P formed by the outer spherical bearing 4 and the inner spherical bearing 6 is made to coincide with the lower surface of the flexible film 10.

  That is, the spindle shaft 1 of the low center-of-gravity airbag type polishing head of the present invention is suspended from a column (not shown) of the CMP polishing apparatus, and is mechanically connected to a motor drive source (not shown) to obtain power. It is provided so as to be movable up and down and rotatable.

  As shown in FIG. 1, the connecting member 2 is a short tubular member having a thickness. On the circumferential surface in the axial direction, a plurality of head holding members 3 to be described later are fixed to the lower end of the spindle shaft 1 for fixing. A plurality of fixing bolt insertion holes for fixing with the bolt 2a are penetrated, and a connecting bolt screw hole 2b to be screwed with a connecting bolt 11 described later is penetrated at the center. is there.

  Next, the head holding member 3 is fixed to the lower end of the spindle shaft 1. The lower end side of the spindle shaft 1 is inserted upward, and the connecting member 2 is interposed in the annular step at the lower end of the spindle shaft 1. And a cylindrical upper part 3a for fixing with a fixing bolt 2a, and a cup-like lower part 3b having a lower diameter and an opening formed integrally with the cylindrical upper part 3a and a flange. Thus, a dust-proof cover 3c is mounted on the outer side of the head holding member 3, an outer spherical bearing 4 described later is provided in the cup-shaped lower portion 3b, and a drive pin 5 described later projects on the outer peripheral edge. It is something to be installed.

  Next, the outer spherical bearing 4 has a cylindrical outer peripheral surface, a flat upper surface, and a central hole through which a connecting bolt 11 for fixing a head main body 7 to be described later is inserted with a gap at the center. And a concave spherical sliding portion 4a serving as a spherical bearing that is a part of a sphere that is narrow at the top and narrowed at the bottom connected to the center hole. The interior is provided from below the cup-shaped lower part 3b that is open at the bottom, and the inner surface and the top plate of the cup-shaped lower part 3b are disposed in close contact with the outer peripheral surface and the upper surface of the outer spherical bearing 4.

  Further, the plurality of drive pins 5 protrude from the edge of the cup-shaped lower part 3b of the head holding member 3 so as to transmit the rotational force from the spindle shaft 1 to the head body 7 described later. belongs to.

  Furthermore, the inner spherical bearing 6 is a substantially hemispherical shape obtained by cutting the upper part of the sphere in the lateral direction, and the upper surface and the lower surface have a flat surface, and the upper surface of the head body 7 to be described later is erected at the center. A center hole 6a through which the connecting cylindrical portion 7c is inserted is provided, and the upper part, which is a part of a sphere that is joined to the concave spherical sliding portion 4a inside the outer spherical bearing 4 to form a spherical bearing, has a small diameter. The lower part is provided with a convex spherical sliding surface 6b having a large diameter, and as is well known, it becomes a spherical bearing capable of following the inclination in all directions.

  In addition, the head body 7 has a substantially convex outer shape, and has a connecting cylindrical portion 7c upright at the center of the upper surface, and the inside of the connecting cylindrical portion 7c penetrates the connecting hole 7d, A connecting bolt 11 to be described later is inserted into the connecting hole 7d. The connecting cylindrical portion 7c is inserted into the center hole 6a of the inner spherical bearing 6 and the upper surface of the head main body 7 has an annular recess. A groove 7a is formed to place the lower surface of the inner spherical bearing 6 thereon.

  A concave spherical washer receiving portion 7f for mounting the spherical washer 7e is formed below the connection hole 7d of the head main body 7. The spherical washer receiving portion 7f accommodates the spherical washer 7e, and the head main body 7 and the outer A head body 7 is formed by screwing a spherical bearing 4 and an inner spherical bearing 6 with a connecting bolt screw hole 2b screwed into a connecting member 2 interposed in a head holding member 3 and a connecting bolt 11 described later. Is fixed so as to be slightly movable in all directions.

  A spindle projecting from the edge of the cup-shaped lower portion 3b of the head holding member 3 is provided outside the annular groove 7a on the upper surface of the head body 7 on which the lower surface of the inner spherical bearing 6 is placed. A plurality of drive pin insertion holes 7b through which a plurality of drive pins 5 that transmit the rotational force of the shaft 1 to the head main body 7 are inserted so as to be slightly movable are provided.

  Next, the airbag 8 is annular and protrudes downward from the lower surface of the head body 7 and is attached to the outside of the head body 7. A back plate 9 is laminated on the lower surface of the airbag 8, The flexible film 10 is stretched on the lower surface of the back plate 9.

  Next, the connecting bolt 11 has a lumen at the center, and forms a fluid supply system that fluidly pressurizes the back surface of the flexible membrane 10, and has a hexagonal head whose diameter is expanded at the lower end. A connecting screw 11 a is screwed on the upper end side and is screwed into a connecting bolt screw hole 2 b at the center of the connecting member 2.

  Then, the gimbal point P of the spherical bearing formed by the outer spherical bearing 4 and the inner spherical bearing 6 is made to coincide with the lower surface of the flexible film 10 as shown in FIG.

  That is, in the low center-of-gravity airbag type polishing head of the present invention, the spindle shaft 1 and the head holding member 3 are integrally fixed with the fixing bolt 2a by inserting the connecting member 2 inside the head holding member 3. Is.

  On the other hand, in the head main body 7, a connecting cylindrical portion 7 c protruding upward is inserted into the center hole 6 a of the inner spherical bearing 6 and placed in the annular concave groove 7 a, so that the convex spherical surface of the inner spherical bearing 6 is provided. The concave spherical sliding portion 4a of the outer spherical bearing 4 is fitted on the sliding surface 6b.

  Then, the spherical washer 7e is inserted into the connection bolt 11, and is inserted into the connection hole 7d in a state where the inner spherical bearing 6 and the outer spherical bearing 4 of the head main body 7 are placed, and the connection member 2 is connected. It is screwed into a screw hole and connected so as to be slightly movable.

  Further, an airbag 8 is fixed to the outer periphery of the head body 7, and a flexible film 10 is stretched on the airbag 8 with a back plate 9 interposed therebetween.

  The low center-of-gravity airbag type polishing head of the present invention has a gimbal point on the lower surface of the head body by an outer spherical bearing housed inside the cup-shaped lower portion of the head holding member and an inner spherical bearing fitted to the outer spherical bearing. It can be matched with the stretched flexible film, and an air bag is interposed above the flexible film, and can sufficiently follow the delicate inclination of the wafer polished by the CMP polishing apparatus. An object of the present invention is to provide a polishing head in which the pressing force is averaged over the entire surface of the wafer even at a slight inclination during polishing, and the flyout of the wafer when lifting the polishing head is minimized.

FIG. 1 is a schematic explanatory view of a grinding apparatus of an embodiment of a low center of gravity airbag type polishing head of the present invention.

W Wafer R Retainer 1 Spindle shaft 2 Connection member 2a Fixing bolt 2b Connection bolt screw hole 3 Head holding member 3a Cylindrical upper part 3b Cup-like lower part 3c Cover 4 Outer spherical bearing 4a Concave spherical sliding part 5 Drive pin 6 Inner spherical bearing 6a Center hole 6b Convex spherical sliding part 7 Head body 7a Annular groove 7b Drive pin insertion hole 7c Connection cylindrical part 7d Connection hole 7e Spherical washer 7f Spherical washer receiving part 8 Air bag 9 Back plate 10 Flexible membrane 11 Connection bolt 11a Connection screw P Gimbal point

Claims (1)

  A spindle shaft provided so as to be movable up and down and rotatable in the polishing apparatus, a cylindrical upper portion for fixing the lower end of the spindle shaft with a connecting member, and a cup-shaped lower portion having an opening at the bottom are integrally provided. A head holding member, an outer spherical bearing housed inside the cup-shaped lower portion of the head holding member, and a plurality of drive pins for transmitting a rotational force projecting from an edge of the cup-shaped lower portion of the head holding member; An inner spherical bearing to be joined to the outer spherical bearing, an annular concave groove for fixing the inner spherical bearing, and a plurality of drive pin insertion holes for inserting the plurality of drive pins are provided, and a connecting cylindrical portion is provided above. A head body provided, an annular airbag fixed to the circumference of the head body with a lower surface slightly protruding from the lower surface of the head body, and the airbag A gimbal formed by the outer spherical bearing and the inner spherical bearing, comprising: a flexible film stretched through a back plate on a lower surface; and a connecting bolt for connecting the head body and the connecting member. A low center-of-gravity airbag type polishing head characterized in that a point coincides with the lower surface of the flexible film.

Images