阅读说明：本技术 工件研磨装置和工件研磨装置中的加压盘用树脂垫体 (Work polishing apparatus and resin pad for pressure plate in work polishing apparatus ) 是由 桥诘健二 宫岛佐辅 于 2021-09-02 设计创作，主要内容包括：本发明提供一种工件研磨装置和工件研磨装置中的加压盘用树脂垫体,其中,树脂垫对顶环(加压盘)的接合良好、能够获得适当的对载盘的压力分布。本发明的工件研磨装置具备：定盘；和顶环,其配置于定盘的上方,在与定盘之间夹着在下表面保持有工件的载盘,并将工件向定盘面按压。顶环具备：加压盘,其按压载盘的上表面；按压机构,其利用空气压按压加压盘；顶环主体,其具备围绕加压盘并按压载盘的周边部的环状部。加压盘形成为除了载盘的周边部以外对载盘的上表面整面进行按压的尺寸；按压机构具有对加压盘的上表面中央部进行局部按压的活塞；在加压盘的下表面整面粘贴有厚度为1～4mm、压缩率为1～8％、具有弹性的树脂垫。(The invention provides a work polishing apparatus and a resin pad for a pressure plate in the work polishing apparatus, wherein the resin pad has good joint to a top ring (pressure plate) and can obtain proper pressure distribution to a carrier plate. The workpiece polishing apparatus of the present invention includes: fixing a disc; and a top ring which is disposed above the surface plate, sandwiches the carrier plate, which holds the workpiece on the lower surface thereof, with the surface plate, and presses the workpiece against the surface plate. The top ring is provided with: a pressing plate which presses an upper surface of the carrier plate; a pressing mechanism for pressing the pressurizing plate by air pressure; and a top ring main body having an annular portion surrounding the pressure plate and pressing a peripheral portion of the carrier plate. The pressing plate is formed into a size of pressing the whole upper surface of the carrier plate except the peripheral part of the carrier plate; the pressing mechanism is provided with a piston for locally pressing the central part of the upper surface of the pressure plate; a resin pad having a thickness of 1 to 4mm and a compression rate of 1 to 8% and having elasticity is adhered to the entire lower surface of the pressing plate.)

1. A workpiece polishing apparatus is provided with:

a fixed plate, the upper surface of which is stuck with a grinding cloth and rotates in a horizontal plane; and

a top ring which is disposed above the surface plate so as to be vertically movable and rotatable in a horizontal plane, and which is configured to press a workpiece against the surface plate with a carrier plate having a workpiece held on a lower surface thereof interposed therebetween,

the workpiece polishing apparatus is characterized in that,

the top ring is provided with:

a pressurizing plate that presses an upper surface of the carrier plate;

a pressing mechanism that presses the pressure plate against the upper surface of the carrier plate by air pressure; and

a top ring main body having an annular portion surrounding the pressure plate and pressing a peripheral portion of the carrier plate,

the pressing plate is formed as: a dimension of pressing the entire upper surface of the carrier plate except for the peripheral portion of the carrier plate pressed by the annular portion,

the pressing mechanism is provided with a piston for partially pressing the central part of the upper surface of the pressure plate,

the whole surface of the lower surface of the pressure plate is stuck with an elastic resin pad,

the thickness of the resin pad is 1 mm-4 mm, and the compression rate is 1% -8%.

2. The workpiece polishing apparatus as set forth in claim 1, wherein the resin pad is made of a urethane resin.

3. A workpiece polishing apparatus as set forth in claim 1 or claim 2, characterized in that a hole is provided in a central portion of said resin pad, and a fixing bolt for fixing said pressurizing plate to said piston is inserted through the hole.

4. The workpiece polishing apparatus as set forth in claim 1 or claim 2, wherein the top ring has a weight removably mounted on the top ring body.

5. A resin pad for a pressure plate, which is a resin pad adhered to the entire lower surface of the pressure plate in a workpiece polishing device,

the workpiece polishing apparatus includes:

a fixed plate, the upper surface of which is stuck with a grinding cloth and rotates in a horizontal plane; and

a top ring which is disposed above the surface plate so as to be vertically movable and rotatable in a horizontal plane, and which is configured to press a workpiece against the surface plate with a carrier plate having a workpiece held on a lower surface thereof interposed therebetween,

the top ring is provided with:

a pressurizing plate that presses an upper surface of the carrier plate;

a pressing mechanism that presses the pressure plate against the upper surface of the carrier plate by air pressure; and

a top ring main body having an annular portion surrounding the pressure plate and pressing a peripheral portion of the carrier plate,

the pressing plate is formed as: a dimension of pressing the entire upper surface of the carrier plate except for the peripheral portion of the carrier plate pressed by the annular portion,

the pressing mechanism is provided with a piston for partially pressing the central part of the upper surface of the pressure plate,

the resin pad body for the pressure plate is characterized in that,

the resin cushion body is an elastic resin cushion with the thickness of 1 mm-4 mm and the compression rate of 1% -8%,

an adhesive layer is formed on the surface of the pressure-applying plate that is adhered to the entire lower surface side thereof, and a release paper is adhered to the adhesive layer so as to be peelable.

6. The resin mat body for a pressure plate as set forth in claim 5, wherein said resin mat is made of a polyurethane resin.

7. The resin pad for a pressure plate according to claim 5 or claim 6, wherein a hole is provided in a central portion of the resin pad, and a fixing bolt for fixing the pressure plate to the piston is inserted into the hole.

8. The resin pad for a pressure disk according to claim 5 or claim 6, wherein the release paper is provided with 2 or more small holes for air release.

9. The resin pad for a pressure plate of claim 5 or claim 6, wherein the release paper is provided with a folding line dividing the release paper into 2 or more regions.

10. The resin pad for a pressure plate of claim 5 or claim 6, wherein the resin pad polishes the front and back surfaces in a manner intersecting in the X-Y direction to adjust the thickness balance.

Technical Field

The present invention relates to a workpiece polishing apparatus for polishing a workpiece such as a wafer, and a resin pad attached to a pressure plate of a top ring in the workpiece polishing apparatus.

Background

Various types of polishing apparatuses for workpieces such as silicon wafers have been proposed.

For example, a workpiece polishing apparatus shown in patent document 1 (japanese patent application laid-open No. 7-130687) includes: a fixed plate, the upper surface of which is stuck with a grinding pad and rotates in a horizontal plane by a driving part; and a top ring which is disposed above the surface plate so as to be vertically movable and rotatable in a horizontal plane, and which is configured to press the workpiece against the surface plate while sandwiching a carrier plate having the workpiece held on a lower surface thereof between the top ring and the surface plate, wherein the workpiece polishing apparatus polishes the workpiece by rotating the surface plate and the top ring in a desired direction while supplying the slurry from the slurry supply unit.

The top ring has a pressing plate pressing the carrier plate.

Incidentally, when the carrier plate is directly pressed by the metal pressing plate, the pressing force from the pressing plate is not uniformly transmitted to the carrier plate, and the workpiece cannot be uniformly pressed against the polishing pad, and thus satisfactory polishing cannot be performed.

Therefore, conventionally, a rubber pad having elasticity is attached to the lower surface of the pressure plate using a double-sided tape, and the pressure plate is pressed through the rubber pad. As the rubber pad, a pad (fig. 5) in which a large number of small pyramidal protrusions are formed in a matrix shape on the lower surface side of the pressing tray was used.

However, in order to fix the rubber pad to the metal pressure plate, it is not possible to fix the rubber pad satisfactorily by using a double-sided tape using a general adhesive. Therefore, first, a liquid curable adhesive agent exclusively for rubber is applied to a rubber pad, a double-sided tape is bonded to the pad via the adhesive agent exclusively for rubber, and then the pad is bonded to the lower surface of the platen with the adhesive agent for double-sided tape.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 7-130687

Disclosure of Invention

Problems to be solved by the invention

However, as described above, in the rubber pad having a large number of small pyramidal protrusions, it is difficult to uniformly transmit pressure to the carrier plate due to the uneven thickness of the pad itself, the uneven thickness of the joining layer, and the like. More specifically, the following disadvantages may occur: the pressure distribution to the carrier plate changes sharply in the radial direction of the carrier plate, and the pressure distribution does not gradually spread uniformly concentrically from the center portion of the carrier plate toward the peripheral portion, but spreads unevenly toward the peripheral portion (for example, the pressure distribution is elliptical).

Means for solving the problems

The present invention has been made to solve the above-described problems, and an object thereof is to provide a work polishing apparatus and a resin pad for a top ring pressure plate in the work polishing apparatus, in which the joining of the resin pad to the top ring (pressure plate) is good and an appropriate pressure distribution to a carrier plate can be obtained.

To achieve the above object, the present invention has the following configuration.

That is, the workpiece polishing apparatus according to the present invention is characterized by comprising: a fixed plate, the upper surface of which is stuck with a grinding cloth and rotates in a horizontal plane; and a top ring which is disposed above the surface plate so as to be vertically movable and rotatable in a horizontal plane, and which is configured to press a workpiece against the surface plate with a carrier plate held on a lower surface thereof interposed between the top ring and the surface plate, the top ring comprising: a pressure plate for pressing the upper surface of the carrier plate; a pressing mechanism for pressing the pressure plate against the upper surface of the carrier plate by air pressure; and a top ring main body having an annular portion surrounding the pressure plate and pressing a peripheral portion of the carrier plate, the pressure plate being formed with: the pressing mechanism has a piston for partially pressing the central part of the upper surface of the pressure plate, the entire lower surface of the pressure plate is adhered with an elastic resin pad, the thickness of the resin pad is 1mm to 4mm, and the compression ratio is 1% to 8%.

The resin pad is preferably made of a polyurethane resin.

Preferably, a hole is provided in a central portion of the resin pad, and a fixing bolt for fixing the pressure plate to the piston is inserted into the hole.

The top ring may be formed of an article having a weight detachably mounted on the top ring body.

Further, a resin pad for a pressure plate according to the present invention is a resin pad attached to the entire lower surface of a pressure plate in a workpiece polishing apparatus including: a fixed plate, the upper surface of which is stuck with a grinding cloth and rotates in a horizontal plane; and a top ring which is disposed above the surface plate so as to be vertically movable and rotatable in a horizontal plane, and which is configured to press a workpiece against the surface plate with a carrier plate held on a lower surface thereof interposed between the top ring and the surface plate, the top ring comprising: a pressure plate for pressing the upper surface of the carrier plate; a pressing mechanism for pressing the pressure plate against the upper surface of the carrier plate by air pressure; and a top ring main body having an annular portion surrounding the pressure plate and pressing a peripheral portion of the carrier plate, the pressure plate being formed with: the pressing mechanism has a piston for partially pressing the central part of the upper surface of the pressure plate, the resin pad body is an elastic resin pad with the thickness of 1-4 mm and the compression ratio of 1-8%, an adhesive layer is formed on the surface of the pressure plate adhered to the whole lower surface side, and a release paper is adhered on the adhesive layer in a releasable manner.

The resin pad is preferably made of a polyurethane resin.

Preferably, a hole is provided in a central portion of the resin pad body, and a fixing bolt for fixing the pressurizing plate to the piston is inserted into the hole.

Preferably, the release paper is provided with 2 or more small holes for air release.

Preferably, the release paper is provided with a folding line dividing the release paper into 2 or more regions.

Preferably, the resin pad polishes the front and back surfaces in a manner to cross in the X-Y direction to adjust the thickness balance.

Effects of the invention

According to the present invention, the following effects can be exhibited.

That is, according to the present invention, since the resin pad has elasticity, it is possible to easily attach the resin pad to the top ring (pressing plate) by using a general double-sided tape adhesive without using a liquid curing adhesive exclusively for rubber as in the conventional art, and since the resin pad having excellent flatness is used, the degree of pressing the workpiece is uniform, and the workpiece can be polished with high precision. The pressing force of the annular portion against the peripheral portion of the carrier disk and the pressing force of the pressing disk against the peripheral portion from the central portion of the carrier disk are balanced, and thus, an ideal pressing force against the workpiece can be realized.

Drawings

Fig. 1 is a front view of a workpiece polishing apparatus.

Fig. 2 is a plan view showing the position of the top ring on the surface plate.

Fig. 3 is a sectional view of the top ring.

Fig. 4A is a plan view of the resin pad body, and fig. 4B is a front view thereof.

Fig. 5 is an explanatory diagram showing a state of a small protrusion of a conventional rubber mat.

Fig. 6 is a photograph showing the load distribution of the carrier plate in the workpiece polishing apparatus for the examples (urethane pad) and the comparative examples (post pad).

Fig. 7 is a graph showing the flatness (GBIR) of a workpiece polished by the workpiece polishing apparatuses of the examples (urethane pad) and the comparative examples (column pad).

Fig. 8 is a graph showing the flatness (SFQR) of a workpiece polished by using the workpiece polishing apparatuses of the example (urethane pad) and the comparative example (post pad).

Fig. 9 is a diagram showing a surface image of a workpiece and a height distribution of the surface in a comparative example.

Fig. 10 is a diagram showing a surface image of a workpiece and a height distribution of the surface in the example after grinding.

Detailed Description

Preferred embodiments of the present invention will be described below in detail based on the drawings.

Fig. 1 is a front view of the workpiece polishing apparatus 10, and fig. 2 is a plan view showing the position of the top ring 16 on the surface plate 14.

The workpiece polishing apparatus 10 includes a surface plate 14, and the surface plate 14 is provided with a polishing cloth attached to an upper surface thereof and is rotatable in a horizontal plane by a known drive device (not shown). Above the fixed plate 14, 4 top rings 16 are arranged in the rotation direction of the fixed plate 14. Although not shown, a slurry supply mechanism for supplying the slurry onto the surface plate 14 is provided.

In fig. 2, A, B, C, D indicates the position of each top ring 16 with respect to the surface plate 14. Each top ring 16 is provided to be movable up and down by a cylinder device 20 provided at an upper portion of the device body 18 so as to be close to or distant from an upper surface of the surface plate 14.

A center roller 22 is rotatably provided at the center of the fixed plate 14, and each top ring is brought into contact with the center roller 22 at A, B, C, D positions, and is rotated by transmitting a rotational force from the center roller 22. Guide rollers 24a, 24b, 24c, and 24d are provided on the periphery of the surface plate 14, and contact the outer peripheral surface of the top ring 16 at positions A, B, C, D, respectively. Each top ring 16 is constituted by: the rollers rotate at A, B, C, D while being held between the center roller 22 and the guide roller 24. Since the surface plate 14 rotates, the rotational force due to the contact friction from the surface plate 14 is also transmitted to each top ring 16.

The guide rollers 24a, 24b, 24c, and 24d are provided at the distal end of an arm (not shown) that pivots about a pivot shaft located outside the surface plate 14, and the guide rollers 24 are movable between a position outside the entire surface plate 14 and a position on the peripheral edge of the surface plate 14 by the pivoting of the arm.

Fig. 3 is a sectional view of the top ring 16.

The top ring 16 is constituted by: the carrier 32 is pressed against the surface plate 14, and a workpiece 30 such as a silicon wafer to be polished is suitably bonded to the lower surface of the carrier 32 with wax, and the surface to be polished (lower surface) of the workpiece 30 is pressed against the polishing pad of the surface plate 14. The carrier 32 is suitably attached with at least 2 (e.g., 5 to 7) workpieces 30.

The top ring 16 will be explained below.

Reference numeral 34 denotes a top ring body, which has a recess 35 formed on the lower surface side and an annular portion 36 formed on the outer peripheral portion of the lower surface side. The outer peripheral surface of the annular portion 36 is in contact with the center roller 22, and transmits a rotational force. A seal ring 37 is fitted into a recess formed in the lower surface of the annular portion 36, and the annular portion 36 presses the peripheral portion of the carrier disk 32 via the seal ring 37.

A through hole 41 is formed in the top plate center portion of the top ring body 34, and the through hole 41 has a tapered surface 40 whose wall surface expands downward.

Reference numeral 43 denotes a hollow vertical moving shaft.

A clutch ring 45 is provided on a flange portion at the lower end of the upper and lower moving shafts 43, and the clutch ring 45 is rotatable about the upper and lower moving shafts 43 via a bearing 44. The outer peripheral surface of the clutch ring 45 is formed as a tapered surface 46 spreading upward. The vertical moving shaft 43 is vertically moved by the cylinder device 20. The tapered surface 40 and the tapered surface 46 come into contact with or separate from each other by the vertical movement of the vertical moving shaft 43. The top ring 16 moves up and down as a whole by moving up and down the vertical moving shaft 43.

A pressure plate 50 is disposed in the recess 35 of the top ring body 34.

A piston 51 is fixed to the upper surface of the pressure plate 50.

A support plate 52 is fixed to the top ring body 34 so as to close the lower side of the through hole 41 of the top plate, and a cylinder chamber 53 is formed in the support plate 52. The piston 51 is provided to be movable up and down in the cylinder chamber 53. The piston 51 is prevented from falling downward by a flange 54 fixed to a backup plate 52. Grooves and ridges (not shown) that engage with each other and extend in the axial direction are formed on the outer wall of the piston 51 and the inner wall of the cylinder chamber 53. Therefore, the pressurizing plate 50 can move up and down with respect to the top ring body 34 via the cylinder device, and can rotate about the up-down moving shaft 43 together with the top ring body 34.

Even in a state where the entire top ring 16 is lifted upward by the vertical moving shaft 43, the top ring body 34 and the pressure plate 50 can be rotated with respect to the vertical moving shaft 43 via the clutch ring 45. This also facilitates the reattachment of the resin pad 64 to the lower surface of the pressure plate 50, as will be described later.

The pressure plate 50 is pressurized by supplying compressed air from a pressure source, not shown, into the cylinder chamber 53 through the flow path 55, the hose 56, the flow path 57, the joint, and the like, and the carriage plate 32 can be pressed. The piston 51, the cylinder chamber 53, the pressure source, the flow path 55, the flow path 57, the hose 56, and the like constitute a pressing mechanism.

As clearly shown in fig. 3, the pressurizing plate 50 is formed to have the following dimensions: the substantially entire upper surface of the carrier plate 32 is pressed except for the peripheral portion of the carrier plate 32 pressed by the annular portion 36 of the top ring body 34. The piston 51 in the pressing mechanism is formed as a piston that partially presses the center portion of the upper surface of the pressure plate 50.

The top ring body 34 is stacked with at least 2 weights 60, and the load on the carrier plate 32 can be adjusted by increasing or decreasing the number of weights 60.

And 62 is a cover that covers the weight 60, preventing the slurry from adhering to the weight 60.

A resin pad 64 made of a resin having elasticity is attached to the lower surface of the pressure plate 50.

The resin pad 64 is a resin pad made of a polyurethane resin having elasticity.

The resin pad 64 preferably has a thickness of 1 to 4mm and a compression ratio of 1 to 8%. The compression ratio is measured according to the method of JIS L-1096 (Japanese Industrial Standard).

Regarding the compression ratio k, when the pressure increases by Δ P and the volume V decreases by Δ V, k is defined as ═ Δ V/V)/Δ P.

The elastic resin pad 64 is not limited to being made of urethane resin.

Fig. 4A and 4B are explanatory views of the resin pad 65 before being attached to the top ring 16. Fig. 4A is a plan view from the paper-peeling side thereof, and fig. 4B is a front view.

The resin pad body 65 is formed with an adhesive layer 66 on the surface of the elastic urethane resin pad 64 attached to the lower surface side of the top ring 16 (pressure plate 50), and a release paper 67 is releasably attached to the adhesive layer 66.

The adhesive layer 66 and the release paper 67 are so-called double-sided tapes, and in the present embodiment, a double-sided tape 442J manufactured by 3M corporation in the united states is used.

As shown in fig. 4A, the release paper 67 is preferably provided with a folding line 68 that divides the release paper 67 into 2 or more regions (two regions in the illustrated example). By providing the folding line 68, when the resin pad 64 is attached to the lower surface of the pressure plate 50d, while the release paper on one side is sequentially peeled off by the folding line 68, the resin pad 64 on one side is attached to the lower surface of the pressure plate 50 via the exposed adhesive layer 66 on one side, and then the release paper 67 on the other side is sequentially peeled off while the resin pad 64 on the other side is attached to the lower surface of the pressure plate 50 via the exposed adhesive layer 66 on the other side, whereby the attachment work can be easily performed. The resin pad 64 is adhered to the entire lower surface of the pressing plate 50.

It is preferable that a large number of small holes (not shown) for air release be provided in the release paper 67 using a roller (not shown) in which a large number of needles are embedded. Thus, when the resin pad 64 is attached, the resin pad 64 can be attached while preventing air from being trapped between the resin pad 64 and the lower surface of the top ring 16.

As shown in fig. 4A, 6 holes for inserting fixing bolts are provided in the center portion of the resin pad 65, and the holes are used for fixing the pressure plate 50 to the piston 51. The 6 holes are not necessarily provided.

The workpiece 30 is ground using the workpiece grinding apparatus 10 as follows.

First, 2 or more pieces of the work 30 are stuck to the lower surface of the carrier plate 32 using wax and by a conventional method.

Next, the carrier tray 32 to which the work 30 is attached is carried into the surface plate 14. The loading of the tray 32 is performed, for example, as follows.

In fig. 2, an arm, not shown, is rotated to move the guide roller 24D corresponding to the innermost position D where the carrier tray 32 is carried in so as to be positioned on the peripheral portion of the surface plate 14. With the other guide rollers 24a, 24b, 24c located outside the surface plate 14.

Next, the surface plate 14 is rotated in the direction of the arrow in fig. 2, and the worker drops the boat 32 onto the surface plate 14 from, for example, the position a. In this way, the carriage plate 32 moves with the rotation of the fixed plate 14, and is carried into a position abutting against the guide roller 24D, i.e., a D position.

Similarly, the guide roller 24C corresponding to the next loading position C is rotated on the peripheral portion of the fixed tray 14, and the operator loads the tray 32 onto the fixed tray 14 from the position a. The carriage plate 32 moves with the rotation of the fixed plate 14 and is carried into a position where it abuts against the guide roller 24C, i.e., the C position.

Similarly, the disks 32 are carried into the position B and finally carried into the position a, and all the disks 32 can be arranged at the predetermined positions a to D on the fixed disk 14.

Next, the 4 top rings 16 are lowered by the cylinder device 20 and brought into contact with the carrier plates 32 at the corresponding positions by their own weight. The annular portion 36 presses the peripheral portion of the carrier disk 32 via a seal ring 37. Further, the pressing plate 50 is pressed by pressurizing the cylinder chamber 53 by the pressing mechanism, and the upper surface of the carrier plate 32 is pressed.

Slurry containing an abrasive is supplied onto the surface plate 14 from a slurry supply unit not shown.

By rotating and driving the center roller 22, the top rings 16 are guided by the guide rollers 24 and rotate at the a position, the B position, the C position, and the D position, respectively. The carrier plate 32 is also pressed by the top ring 16 and rotates at the a position, the B position, the C position, and the D position. Thereby, the lower surface side of the workpiece 30 attached to the lower surface of the carrier plate 32 is polished.

The workpiece polishing apparatus 10 of the present embodiment using the above-described resin pad as the resin pad 64 and the workpiece polishing apparatus in which the conventional rubber pad is attached to the top ring 16 (comparative example: not shown, the same as the polishing apparatus of the present embodiment except for the rubber pad) polish the workpiece 30, and the results thereof will be described below.

In the present embodiment (example), the resin pad 64 is made of polyurethane resin having elasticity, the thickness of the resin pad 64 used is 2mm, the compression ratio is 4%, and the double-sided tape is 442J manufactured by 3M company. The resin pad 64 used is a pad in which the front and back surfaces are polished so as to intersect in the X-Y direction (longitudinal and transverse directions) to adjust the surface state.

On the other hand, as the rubber pad in the comparative example, a rubber pad (fig. 5) having a thickness of about 2mm (including small protrusions) which is a commercially available pillar pad (trade name) and in which a large number of small protrusions in a pyramid shape are arranged in a matrix on the lower surface was used.

On the back surface side of the rubber pad, a liquid curable adhesive (EC 1368ET manufactured by 3M) exclusively for rubber was applied by brush coating with a thinner, dried, and then adhered to the lower surface of the pressing plate 50 of the top ring 16 using the same double-sided tape (442J manufactured by 3M) as used in the examples. Further, the rubber pad is processed so that the height of the small protrusions is constant.

Fig. 6 is a photograph showing pressure distributions of comparative example (column pad) and example (polyurethane pad) among 4 top rings 16(TP1, TP2, TP3, TP 4). That is, the pressure distribution on the carrier plate 32 side when the load of 0KPa, 100KPa, or 200KPa is applied to the pressure plate 50 by the own weight of the top ring 16 and the pressing mechanism. White indicates a high pressure state.

As is clear from fig. 6, in both the comparative example and the example, the pressure is uniformly applied from the annular portion 36 to the peripheral portion of the carrier plate 32.

However, in the center portion of the boat 32 (load from the pressurizing plate 50), it is known that: in the comparative example (column pad), the load is biased toward the center (and is not uniform in the circumferential direction: it is distributed in an elliptical shape); in the case of the embodiment, the load on the boat 32 is a pressure distribution that spreads uniformly concentrically from the central portion toward the peripheral portion.

As described above, in the case of the present embodiment, the load on the boat 32 is a pressure distribution that spreads uniformly concentrically from the central portion toward the peripheral portion, which is achieved by: the pressure plate 50 is formed in such a size that the peripheral portion of the carrier plate 32 pressed by the annular portion 36 of the top ring body 34 presses substantially the entire upper surface of the carrier plate 32, and the piston 51 in the pressing mechanism is formed as a piston 51 that partially presses the central portion of the upper surface of the pressure plate 50.

That is, since the central portion of the pressure plate 50 is pressed by the piston 51 and the pressing force on the central portion is sequentially transmitted to the peripheral portion of the pressure plate 50, the load on the carrier plate 32 is distributed to a pressure uniformly spread concentrically from the central portion toward the peripheral portion. With such a center pressing mechanism, the pressing force of the annular portion 36 against the peripheral portion of the carrier plate 32 and the pressing force of the pressing plate 50 against the carrier plate 32 from the center portion toward the peripheral portion are balanced, and an ideal pressing force against the workpiece 30 can be obtained.

The flatness of the workpiece 30 after polishing when the workpiece 30 was polished using the workpiece polishing apparatuses of examples and comparative examples was evaluated by GBIR (Global back edge range) and SFQR (Site front surface square range), and table 1 is a table showing the evaluation values. The total number of workpieces 30 is 60. For easy comparison, the Average Value (AVE) of GBIR and SFQR in the column pad (comparative example) is set to a conversion value of 1.00. The smaller the value, the higher the flatness.

[ Table 1]

μm

Fig. 7 and 8 are graphs obtained by plotting table 1.

As is clear from table 1, fig. 7, and fig. 8, in the example using the resin pad 64 made of urethane resin, GBIR and SFQR were small values (smaller by about 27% and 14%, respectively), and it was found that the workpiece 30 was polished to a high flatness.

Fig. 9 is a diagram showing a surface image and a height distribution of the surface of the workpiece 30 in the comparative example after polishing, and fig. 10 is a diagram showing a surface image and a height distribution of the surface of the workpiece 30 in the example after polishing. The workpiece 30 of the example was significantly more planar than the workpiece of the comparative example.

The elastic resin pad 64 is not limited to the urethane resin pad described above.

In the above embodiment, the rotation of the top ring 16 is a method of transmitting the rotation of the center roller 22, but may be a top ring directly rotated by the driving force of a motor, as shown in japanese patent application laid-open No. 2014-647.