JP2004253725A - Wafer polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer polishing device that can polish a wafer and, at the same time, can surely transport the wafer at the time of ending or starting the polishing. <P>SOLUTION: This wafer polishing device polishes the wafer held by a wafer carrier by bringing the wafer into contact with a rotating polishing pad while supplying slurry. The wafer carrier has a back plate 22 which imparts a pressing force to the wafer, a retainer ring 23 which presses the polishing pad by controlling the radial movement of the wafer, and a protective sheet 24 which has a suction port 24A for sucking the wafer and transmits the pressing force from the back plate 22 to the wafer by coming into contact with the wafer. At the portion of the back plate 22 corresponding to the suction port 24A of the protective sheet 24, an air hole 22B is formed for discharging a fluid and sucking the fluid. A sheet material 70 having a through hole 70A at the position corresponding to the suction port 24A of the protective sheet 24 is provided in contact with the upper surface of the protective sheet 24 or the lower surface of the back plate 22. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer polishing apparatus that can be suitably used for polishing a wafer by chemical mechanical polishing (CMP).
[0002]
[Prior art]
In recent years, with the development of semiconductor technology, finer design rules and multilayer wiring have been promoted, and in order to reduce costs, the diameter of wafers has also been increasing. Therefore, as in the prior art, when trying to form the pattern of the next layer as it is on the layer on which the pattern is formed, it is difficult to form a good pattern in the next layer due to the unevenness of the previous layer, Defects were likely to occur.
[0003]
Therefore, the surface of the layer on which the pattern is formed is flattened, and thereafter, the pattern of the next layer is formed. In this case, as a flattening means, a wafer polishing apparatus using a CMP method is used.
[0004]
As a wafer polishing apparatus by this CMP method, there is a disk-shaped polishing platen with a polishing pad attached to the surface, and a wafer carrier that holds one surface of the wafer and abuts the other surface of the wafer against the polishing pad. The polishing of the other surface of the wafer while rotating the polishing platen and rotating the wafer carrier to bring the wafer into contact with the polishing pad and supplying a slurry as an abrasive between the polishing pad and the wafer. Polishing apparatuses are generally widely known.
[0005]
The wafer carrier that holds the wafer has a back plate that applies a pressing force by air to the wafer, a retainer ring that regulates the radial movement of the wafer and presses the polishing pad, and a suction port for wafer suction. A protection sheet that contacts the wafer and transmits the pressing force of air from the back plate to the wafer, and a protection sheet that prevents the back surface of the wafer from directly contacting the hard surface of the back plate to prevent scratching (For example, see Patent Document 1).
[0006]
The wafer carrier has a structure in which the pressure of the air injected from the back plate is transmitted to the wafer via the protective sheet and presses the wafer against the polishing pad. For this reason, the protective sheet needs to press the wafer uniformly, and is formed of a material that has a property that it is difficult to stretch but is easily bent.
[0007]
The protection sheet is formed with a suction port for sucking a wafer, and is used to hold the wafer by suction when the wafer is transferred. When transporting a wafer, the wafer is first placed in a retainer ring of a wafer carrier, and air is sucked from an air suction port of a back plate to reduce the pressure inside the protective sheet.
[0008]
Due to the reduced-pressure atmosphere inside the protective sheet, the wafer comes into close contact with the surface of the protective sheet and is transported in this state. The wafer conveyed to the upper surface of the polishing pad is released from the air suction, the air suction port on the back plate is changed to an air injection port, and the wafer is pressed against the polishing pad by receiving the pressing force via the protective sheet. Then, polishing is started.
[0009]
[Patent Document 1]
JP 2000-317819 A
[Problems to be solved by the invention]
However, air pressure is applied to the protective sheet to press the wafer against the polishing pad during polishing, and decompression force is applied to suction the wafer during wafer transfer. In addition, in many cases, the repetition due to the long-term operation gradually causes sag. As a result, it has been pointed out that the wafer hardly adheres to the surface of the protective sheet, or that the protective sheet hardly adheres to the surface of the back plate, resulting in poor transport.
[0011]
The present invention has been made in view of such circumstances, and can perform polishing of a wafer by pressurization with a fluid such as air, at the end of polishing, or at the start of polishing, without malfunction, the wafer. It is an object of the present invention to provide a wafer polishing apparatus capable of reliably sucking and transferring.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a wafer polishing apparatus for polishing a wafer held in a wafer carrier by contacting the wafer with a rotating polishing pad while supplying slurry, wherein the wafer carrier presses the wafer. A back plate that applies pressure, a retainer ring that regulates movement of the wafer in the radial direction and presses the polishing pad, and has a suction port for wafer suction and contacts the wafer and reduces the pressing force from the back plate. A protective sheet for transmitting to the wafer, and a vent hole for fluid discharge and fluid suction is provided at a position of the back plate corresponding to the suction port of the protection sheet. A sheet material having a through hole at a corresponding position is in contact with the upper surface of the protective sheet or on the lower surface of the back plate. To provide a wafer polishing apparatus according to claim is provided with.
[0013]
According to the present invention, a vent hole for fluid discharge and fluid suction is provided at a position of the back plate corresponding to the suction port of the protection sheet, and a through-hole is provided at a position corresponding to the suction port of the protection sheet. Since the sheet material provided is provided in contact with the upper surface of the protection sheet or the lower surface of the back plate, the sheet material is interposed between the back plate and the protection sheet. As a result, even if sagging occurs in the protective sheet, the presence of this sheet material not only improves the adhesion of the wafer to the protective sheet surface, but also improves the adhesion between the back plate and the protective sheet. Become. Therefore, the wafer can be polished by pressurization with a fluid such as air, and the wafer can be reliably sucked and transferred without malfunction at the end of polishing or at the start of polishing.
[0014]
The pressurization and depressurization of such a wafer polishing apparatus are generally performed by air, but the present invention is not necessarily limited to the pressurization and depressurization by air, as with a vent hole for fluid suction. However, the present invention can be applied to pressurization and decompression by other fluids such as a fluid such as nitrogen gas, water, and hydraulic oil.
[0015]
In the present invention, the hardness of the sheet material is preferably 90 or less according to a test method specified in JIS K6301A. If the sheet material has such a hardness, the sheet is easily deformed by pressing or the like, and even if the protective sheet is sagged, the sag is absorbed and the adhesion of the wafer to the protective sheet surface is further improved. .
[0016]
The hardness of the sheet material is more preferably 80 or less, and even more preferably 70 or less, according to a test method specified in JIS K6301A.
[0017]
Further, in the present invention, it is preferable that the surface roughness of the sheet material is 5 μm or less in Ra specified in JIS B0601. If the sheet material has such a surface roughness, when the sheet material comes into contact with the back plate or the protection sheet, the close contact between them can be improved, and the adhesion of the wafer to the protection sheet surface is further improved.
[0018]
In addition, the surface roughness of the sheet material is more preferably 3 μm or less, more preferably 1 μm or less in terms of Ra specified in JIS B0601.
[0019]
In the present invention, it is preferable that the sheet material has an annular shape in contact with only a predetermined range around a suction port of the protection sheet or a ventilation hole of the back plate. As described above, if the sheet material exists only in a predetermined range around the suction hole of the protection sheet or the ventilation hole of the back plate, the state of close contact with the back plate or the protection sheet can be improved, and the surface of the protection sheet of the wafer can be formed. This is because the adhesiveness of the film is further improved.
[0020]
Further, in the present invention, a concave portion is formed around the ventilation hole of the back plate, and the lower surface of the back plate and the lower surface of the sheet material are formed by disposing the sheet material in the concave portion. Are preferably flush. As described above, if the lower surface of the back plate and the lower surface of the sheet material are flush, in addition to the effect of further improving the adhesion of the wafer to the surface of the protective sheet, the back plate and the protective sheet are formed. This is because the effect of making the thickness of the space compact can be obtained.
[0021]
Further, in the present invention, the annular member having a hole having substantially the same size as the suction port of the protection sheet and having a thickness smaller than that of the protection sheet is provided near the suction port of the protection sheet or the ventilation hole of the back plate. It is preferable that the peripheral edge of the annular member is fixed to the protective sheet or the back plate in an airtight state. As described above, if the annular member having a thickness smaller than that of the protective sheet is air-tightly fixed in the vicinity of the suction port of the protective sheet or in the vicinity of the ventilation hole of the back plate, the back plate is connected to the back plate through the annular member. The protection sheet is connected. Thereby, the adhesion of the wafer to the surface of the protective sheet can be further improved.
[0022]
Further, in the present invention, it is preferable that when the wafer is held by the wafer carrier, the suction port of the protective sheet is provided so as to be located at least 50 mm inside the outer peripheral portion of the wafer.
[0023]
Providing a suction port for the protection sheet at such a position can ensure a sufficient distance required for sealing between the wafer and the protection sheet. With such a configuration, the fluid (usually air) supplied for pressurization during polishing is less likely to flow out of the gap between the wafer and the protective sheet.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a wafer polishing apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same members are given the same numbers or symbols.
[0025]
FIG. 1 is a sectional view showing one embodiment of a wafer polishing apparatus according to the present invention. In the wafer polishing apparatus 10, as shown in FIG. 1, a polishing pad 12 is attached to a surface of a rotating polishing platen 11. A wafer carrier 20 is arranged above the polishing pad 12 so as to rotate while holding the wafer W, and to bring the wafer W into contact with the polishing pad 12.
[0026]
The wafer carrier 20 includes a carrier body 21, a back plate 22, a retainer ring 23, a protection sheet 24 (see FIG. 2), an air bag 28 for a back plate, and an air bag 29 for a retainer ring.
[0027]
The back plate airbag 28 is a space formed by the rubber sheet 27 and the carrier body 21, and is supplied with air from an air line 50 </ b> C to press the back plate 22 toward the polishing pad 12. The retainer ring airbag 29 is a space formed by the rubber sheet 27 and the carrier body 21 and is provided on the outer peripheral side of the back plate airbag 28. Air is supplied to the retainer ring airbag 29 from the air line 50D, and presses the retainer ring 23 toward the polishing pad 12.
[0028]
FIG. 2 is an enlarged cross-sectional view illustrating a pressure mechanism of the wafer W of the wafer carrier 20. On the lower surface of the back plate 22, air outlets 22A, 22A, which are vent holes for fluid discharge, are provided on the outer peripheral portion, and air outlets 22B, 22B, which are vent holes for fluid discharge and fluid suction are provided in the center portion. Is formed. Are connected to a main air path 55 via a regulator 54, and the air outlets 22B, 22B are connected to a sub air path 52 via a regulator 51. The sub air path 52 is connected to a positive pressure line 53 and a negative pressure line 58 via a regulator 57 or an atmosphere open line 59 by a switching valve 56.
[0029]
The retainer ring 23 serves to regulate the radial movement of the wafer W and to press the polishing pad 12 to stabilize its surface.
[0030]
The protection sheet 24 is held on the retainer ring 23 at the peripheral edge, prevents the wafer W from directly contacting the hard back plate 22, and contacts the wafer W to apply the air pressure from the back plate 22 to the wafer W. introduce. Air injected from the back plate 22 is exhausted to the outside through a gap 23A between the back plate 22 and the retainer ring 23. The polishing shape of the wafer W is controlled by adjusting the air pressure by the main air path 55 and the air pressure by the sub air path 52, respectively.
[0031]
Switching between the positive pressure line 53, the negative pressure line 58, or the atmosphere release line 59, the air pressure through the main air path 55 and the air pressure through the sub air path 52, and the suction pressure through the negative pressure line 58 are optimized by the CPU 60. Is controlled.
[0032]
The protection sheet 24 is formed with a suction port 24A (see FIG. 3) for sucking a wafer, and is used for sucking and holding the wafer W when the wafer W is transferred. That is, when the wafer W is suctioned, the switching valve 56 switches the sub air path 52 to the negative pressure line 58, and transmits the suction force to the wafer W via the suction port 24A.
[0033]
The wafer carrier 20 is configured as described above. The wafer W held by the wafer carrier 20 is pressed against the polishing pad 12 on the polishing platen 11, and the polishing is performed while rotating the polishing platen 11 and the wafer carrier 20 respectively. By supplying the slurry on the pad 12, the wafer W is polished.
[0034]
FIG. 3 is a bottom view showing the protection sheet 24 and the retainer ring 23. The protection sheet 24 has a property that it is difficult to stretch because it is necessary to protect the surface of the wafer W held by the wafer carrier 20 and transmit the air pressure from the back plate 22 to uniformly press the wafer W. However, it is made of a thin material that has easy bending properties. Also, resistance to acid or alkali contained in the slurry is required.
[0035]
The material of the protective sheet 24 is, for example, Teflon (trademark of du Pont, polytetrafluoroethylene) film, PEТ (polyethylene terephthalate) film, PFA (perfluoroalkyl vinyl ether tetrafluoride) film, polyethylene film, polyester film, Silicon rubber films and the like are preferred.
[0036]
The protective sheet 24 has a suction port 24A formed at the center. The position and the number of the suction ports 24A formed in the protection sheet 24 may take other forms. For example, a configuration may be adopted in which a suction port 24A is formed at the center of the protection sheet 24, and four suction ports 24A, 24A,... Are formed on the circumference to cover this. However, as described above, it is preferable that the suction holes 24A, 24A,...
[0037]
The fixing of the protection sheet 24 to the retainer ring 23 is performed as shown in the conceptual diagram of FIG. In the figure, (a) is an enlarged bottom view, and (b) is a cross-sectional view taken along line AA ′ of (a). The retainer ring 23 is divided into an upper portion 23A and a lower portion 23B, and is integrated by fixing bolts 40, 40. The protection sheet 24 is fixed by being sandwiched between the upper part 23A and the lower part 23B.
[0038]
Further, the retainer ring 23 is provided with a tension adjusting mechanism for the protection sheet 24 so as to cope with a case where the protection sheet 24 is bent. The tension adjusting mechanism includes a fitting groove 42 formed on the lower surface of the upper portion 23A, a screw hole 44 provided through the lower portion 23B, and a bolt 46 having a protrusion 46A at the tip for screwing with the screw hole 44. It is composed of When the protection sheet 24 is bent, the protection sheet 24 is pulled into the fitting groove 42 by tightening the bolt 46, and tension is applied to the protection sheet 24.
[0039]
As shown in FIG. 4B, the through hole 23D of the lower portion 23B is formed in a step shape so that the head of the bolt 46 does not protrude from the lower surface of the retainer ring 23. Similarly, the through hole for 40 is formed in a stepped shape so that the head of the fixing bolt 40 does not protrude from the lower surface of the retainer ring 23.
[0040]
In the present embodiment, the protection sheet 24 is fixed to the retainer ring 23 using bolts 40 or the like, but may be fixed by other methods, for example, by bonding with an adhesive.
[0041]
Next, a configuration for improving the adhesion of the wafer to the surface of the protective sheet 24 in the present invention will be described. FIG. 5 is a cross-sectional view of a main part showing the first embodiment. Among them, (a) shows a state in which the wafer W is being sucked when the wafer is transferred, and (b) shows a state in which the wafer W is being polished. The arrows in the figure indicate the direction in which the air flows.
[0042]
In this configuration, an air outlet 22 </ b> B is provided on the back plate 22 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. Further, a sheet material 70 having a through hole 70 </ b> A is provided on a lower surface of the back plate 22 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. The sheet member 70 is formed in an annular shape in contact with only a predetermined area around the ventilation hole 22B of the back plate 22, is disposed in a recess 22C formed around the ventilation hole 22B of the back plate 22, and has a lower surface of the back plate 22. And the lower surface of the sheet material 70 are flush.
[0043]
The sheet material 70 preferably has a hardness of 90 or less according to a test method specified in JIS K6301A, and preferably has a surface roughness of 5 μm or less in Ra specified in JIS B0601. However, even if the value is out of this range, a predetermined effect can be obtained although the effect is somewhat inferior. The thickness of the sheet member 70 is preferably 0.5 mm or more, and more preferably 1 mm or more.
[0044]
The material of the sheet material 70 is not particularly limited as long as it satisfies the above-described conditions, but for example, a rubber material such as chloroprene rubber and silicone rubber can be preferably used.
[0045]
With the above configuration, the sheet member 70 having a predetermined hardness is interposed between the back plate 22 and the protection sheet 24. As a result, even if sagging occurs in the protective sheet 24, the sheet material 80 and the protective sheet 24 can easily adhere to each other, and airtightness can be ensured. As a result, the adhesiveness of the wafer W to the surface of the protective sheet 24 can be improved. Will be improved. Therefore, as shown in FIG. 5B, the wafer can be polished by pressurization with a fluid such as air, and when the polishing is completed or when the polishing is started, as shown in FIG. Thus, the wafer W can be reliably sucked and transferred without malfunction. Note that FIG. 5A is illustrated with emphasis compared to the actual case, and the deformation of the protection sheet 24 is not so large.
[0046]
FIG. 6 is a cross-sectional view of a main part showing the second embodiment. Among them, (a) shows a state in which the wafer W is being sucked when the wafer is transferred, and (b) shows a state in which the wafer W is being polished. The arrows in the figure indicate the direction in which the air flows.
[0047]
In this configuration, an air outlet 22 </ b> B is provided on the back plate 22 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. Further, a sheet material 80 having a through hole 80 </ b> A is provided on the upper surface of the protection sheet 24 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. The sheet material 80 has an annular shape in contact with only a predetermined area around the suction port 24A of the protection sheet 24.
[0048]
The sheet material 80 preferably has a hardness of 90 or less according to a test method specified in JIS K6301A, and preferably has a surface roughness of 5 μm or less in Ra specified in JIS B0601. However, even if the value is out of this range, a predetermined effect can be obtained although the effect is somewhat inferior. The thickness of the sheet material 80 is preferably 0.05 to 1 mm, more preferably 0.1 to 0.5 mm.
[0049]
The material of the sheet material 80 is not particularly limited as long as it satisfies the above-described conditions. For example, a rubber material such as chloroprene rubber and silicone rubber can be preferably used.
[0050]
With the above configuration, the sheet material 80 having a predetermined hardness is interposed between the back plate 22 and the protection sheet 24. As a result, even if sagging occurs in the protective sheet 24, the sheet material 80 and the back plate 22 are easily adhered to each other, and airtightness can be secured, whereby the adhesiveness of the wafer W to the surface of the protective sheet 24 is improved. Will be improved. Accordingly, as shown in FIG. 6B, the wafer can be polished by pressurization with a fluid such as air, and when the polishing is completed or when the polishing is started, as shown in FIG. Thus, the wafer W can be reliably sucked and transferred without malfunction. FIG. 6A illustrates the protection sheet 24 more emphasized than the actual one, and the deformation of the protection sheet 24 is not so large.
[0051]
FIG. 7 is a cross-sectional view of a main part showing the third embodiment. Among them, (a) shows a state in which the wafer W is being sucked when the wafer is transferred, and (b) shows a state in which the wafer W is being polished. The arrows in the figure indicate the direction in which the air flows.
[0052]
In this configuration, an air outlet 22 </ b> B is provided on the back plate 22 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. Further, a sheet material 70 having a through hole 70 </ b> A is provided on a lower surface of the back plate 22 at a position corresponding to the suction port 24 </ b> A of the protection sheet 24. The sheet member 70 is formed in an annular shape in contact with only a predetermined area around the ventilation hole 22B of the back plate 22, is disposed in a recess 22C formed around the ventilation hole 22B of the back plate 22, and has a lower surface of the back plate 22. And the lower surface of the sheet material 70 are flush. The above configuration is the same as that of the first embodiment shown in FIG.
[0053]
In this configuration, an annular member 90 having a hole 90A of substantially the same size as the suction port 24A of the protection sheet 24 and having a smaller thickness than the protection sheet 24 is arranged near the suction port 24A of the protection sheet 24. In addition, a configuration is adopted in which the peripheral edge of the annular member 90 is fixed to the protective sheet 24 in an airtight state.
[0054]
As in the first embodiment, the sheet material 70 preferably has a hardness of 90 or less according to the test method specified in JIS K6301A, and has a surface roughness of 5 μm or less in Ra specified in JIS B0601. Can be preferably used. However, even if the value is out of this range, a predetermined effect can be obtained although the effect is somewhat inferior. The thickness of the sheet member 70 is preferably 0.5 mm or more, and more preferably 1 mm or more.
[0055]
The material of the sheet material 70 is not particularly limited as long as it satisfies the above-described conditions, but for example, a rubber material such as chloroprene rubber and silicone rubber can be preferably used.
[0056]
It is preferable that the annular member 90 has a thickness smaller than that of the protection sheet 24 and is a flexible material that can maintain airtightness with the sheet member 70. The thickness of the annular member 90 is not particularly limited except that the thickness is smaller than that of the protective sheet 24, but specifically, it is preferably 0.25 mm or less.
[0057]
Examples of the material of the annular member 90 include Teflon (trademark of du Pont, polytetrafluoroethylene) film, PEТ (polyethylene terephthalate) film, PFA (perfluoroalkylvinyl ether tetrafluoride) film, polyethylene film, polyester film And a silicon rubber film.
[0058]
Means for fixing the peripheral edge of the annular member 90 to the protective sheet 24 in an airtight manner depends on the material of the annular member 90 and the protective sheet 24, but generally includes an adhesive with an adhesive, an adhesive with a double-sided adhesive tape, Various known means such as thermocompression bonding can be employed.
[0059]
With the above configuration, the sheet member 70 having a predetermined hardness and the annular member 90 thinner than the protection sheet 24 are interposed between the back plate 22 and the protection sheet 24. As a result, even if the protection sheet 24 sags, airtightness can be ensured by the close contact of the annular member 90 with the sheet material 70, and the adhesion of the wafer W to the surface of the protection sheet 24 is improved. . Therefore, as shown in FIG. 7B, the wafer can be polished by pressurization with a fluid such as air, and when the polishing is completed or when the polishing is started, as shown in FIG. Thus, the wafer W can be reliably sucked and transferred without malfunction. Note that FIG. 7A is illustrated with emphasis on the actual state, and the deformation of the annular member 90 is not so large.
[0060]
As described above, the example of the embodiment of the wafer polishing apparatus according to the present invention has been described, but the present invention is not limited to the example of the above embodiment, and various aspects can be adopted. For example, the sheet materials 70 and 80 shown in FIGS. 5 to 7 are annular in contact with only a predetermined range around the suction port 24A of the protection sheet or the ventilation hole 22B of the back plate. Can be adopted in such a size as to cover substantially the entire surface. This is because a predetermined effect can be obtained even in this case.
[0061]
Although the sheet member 80 shown in FIG. 6 is provided in contact with the upper surface of the protective sheet 24, a configuration in which the sheet member 80 is provided in contact with the lower surface of the back plate 22 may be adopted instead. This is because even in this case, substantially the same effect can be obtained.
[0062]
【The invention's effect】
As described above, according to the present invention, at the position corresponding to the suction port of the protection sheet, the vent hole for discharging fluid and suction of the fluid is provided at the position corresponding to the suction port of the protection sheet. Since a sheet material having a through hole at a position where the sheet material is provided is in contact with the upper surface of the protection sheet or the lower surface of the back plate, the sheet material is interposed between the back plate and the protection sheet. . As a result, even if the protective sheet sags, the presence of the sheet material improves the adhesion of the wafer to the protective sheet surface. Therefore, the wafer can be polished by pressurization with a fluid such as air, and the wafer can be reliably sucked and transferred without malfunction at the end of polishing or at the start of polishing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a wafer polishing apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a wafer pressing mechanism of a wafer carrier. FIG. 3 is a bottom view showing a protective sheet and a retainer ring. FIG. 5 is a conceptual view showing a method of fixing the protective sheet to the retainer ring. FIG. 5 is a cross-sectional view of a main part showing a first embodiment of the present invention. FIG. 6 is a cross-sectional view of a main part showing a second embodiment of the present invention. FIG. 7 is a sectional view of a main part showing a third embodiment of the present invention.
W: Wafer, 10: Wafer polishing apparatus, 11: Polishing table, 12: Polishing pad, 20: Wafer carrier, 21: Carrier body, 22: Back plate, 22A, 22B: Air ejection port, 23: Retainer ring, 24 ... Protective sheet, 24A ... Suction port, 70, 80 ... Sheet material

Claims (7)

While supplying the slurry, in a wafer polishing apparatus for polishing the wafer held in the wafer carrier by contacting the rotating polishing pad,
The wafer carrier has a back plate that applies a pressing force to the wafer, a retainer ring that controls the radial movement of the wafer and presses the polishing pad, and has a suction port for wafer suction and is in contact with the wafer. Having a protective sheet for transmitting the pressing force from the back plate to the wafer,
At the position corresponding to the suction port of the protection sheet of the back plate, a vent hole for fluid discharge and fluid suction is provided,
A wafer polishing apparatus, wherein a sheet material having a through hole at a position corresponding to a suction port of the protection sheet is provided in contact with an upper surface of the protection sheet or in contact with a lower surface of the back plate. The wafer polishing apparatus according to claim 1, wherein the hardness of the sheet material is 90 or less according to a test method specified in JIS K6301A. 3. The wafer polishing apparatus according to claim 1, wherein the surface roughness of the sheet material is 5 μm or less in Ra defined in JIS B0601. 4. 4. The wafer polishing apparatus according to claim 1, wherein the sheet material has an annular shape in contact with only a predetermined range around a suction port of the protection sheet or a ventilation hole of the back plate. 5. A concave portion is formed around the ventilation hole of the back plate, and the lower surface of the back plate is flush with the lower surface of the sheet material by disposing the sheet material in the concave portion. The wafer polishing apparatus according to claim 4. An annular member having a hole of substantially the same size as the suction port of the protection sheet and having a smaller thickness than the protection sheet is disposed near the suction port of the protection sheet or near the ventilation hole of the back plate,
The wafer polishing apparatus according to claim 1, wherein a peripheral edge of the annular member is fixed to the protection sheet or the back plate in an airtight state. The wafer polishing apparatus according to any one of claims 1 to 6, wherein when the wafer is held by the wafer carrier, the suction port of the protection sheet is provided at least 50 mm inside the outer peripheral portion of the wafer. .

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