TWI666696B - Polishing method - Google Patents

Abstract

The present invention provides a method for preventing damage to a polishing tape, and using the polishing tape to polish a peripheral edge portion of a wafer on which a hard film is formed.

The polishing method of the present invention uses a polishing tape 180 having a base material film made of polyimide, a binder made of polyimide, and abrasive particles held by the binder. In this polishing method, the silicon substrate W having the silicon carbide film formed on the surface is rotated, and the polishing tape 180 is pressed lightly on the silicon carbide film on the peripheral portion of the silicon substrate W, and the silicon carbide film is removed from the peripheral portion of the silicon substrate W.

Description

Grinding method

The present invention relates to a method for polishing a peripheral edge portion of a substrate such as a wafer using a polishing tape.

When manufacturing a semiconductor device, a polishing device for polishing a peripheral portion of a wafer using a polishing tape is generally used. The structure of the polishing tape includes a base material film made of PET (polyethylene terephthalate); Abrasive particles.

The conventional polishing tape has a relatively low mechanical strength. Therefore, when a peripheral portion of a wafer having a hard film made of silicon carbide (SiC) is polished on the surface, the polishing tape is damaged. The twenty-ninth figure is a cross-sectional view of a wafer having a structure in which a SiC film is formed on a silicon substrate. As shown in FIG. 29, a SiC film (silicon carbide film) 310 is formed on the entire surface of the silicon substrate 301 including the peripheral edge portion. An element structure including wiring, an insulating film, and the like may be formed on the SiC film 310 in some cases. Since the SiC film 310 is a hard film, when the peripheral edge portion of the wafer shown in FIG. 29 is polished with the above-mentioned polishing tape, the abrasive particles may fall off or the polishing tape may be broken.

In addition, when polishing the peripheral edge portion of a SOI (Silicon on Insulator) wafer, the polishing tape may be damaged. The SOI wafer is manufactured by bonding an element substrate and a silicon substrate. More specifically, as shown in FIGS. 30 (a) and 30 (b), the element substrate 302 and the silicon substrate 301 are bonded to each other with an adhesive 313, and the element substrate 302 is polished by a grinder from the back surface thereof. And get the thirtieth (c) The figure shows an SOI wafer with a silicon layer 315 and an element layer 316 stacked. Further, as shown in FIG. 30 (d), the polishing tape is pressed down on the peripheral edge portion of the SOI wafer, and the peripheral portions of the silicon layer 315, the element layer 316, and the silicon substrate 301 are removed together with the adhesive 313.

Since the adhesive 313 existing between the element substrate 302 and the silicon substrate 301 is a hard film, as shown in FIG. 30 (d), when the peripheral edge portion of the SOI wafer is polished with a polishing tape, abrasive particles may fall off. The abrasive belt even broke off.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2014-24128

[Patent Document 2] Japanese Patent Laid-Open No. 2011-171647

[Patent Document 3] Japanese Patent Laid-Open No. 2006-142388

[Patent Document 4] Japanese Patent No. 3534115

When the polishing tape is damaged during wafer polishing, the polishing tape needs to be replaced. Frequent replacement of the polishing belt causes a reduction in the productivity of the polishing device.

Therefore, an object of the present invention is to provide a method for preventing a polishing tape from being damaged and polishing a peripheral portion of a wafer having a hard film formed thereon by using the polishing tape.

In order to achieve the above object, a polishing method of one aspect of the present invention uses a polishing tape having: a base material film composed of polyimide; a binder composed of polyimide; and the aforementioned adhesive The retained abrasive particles are characterized in that a silicon carbide film is formed on the surface. The silicon substrate is rotated, and the polishing tape is pressed against the silicon carbide film on the periphery of the silicon substrate with a light force, and the silicon carbide film is removed from the periphery of the silicon substrate.

A suitable feature of the present invention is that the surface of the adhesive is water-repellent by contacting the silicon carbide film, and the polishing tape is pressed against the silicon carbide film on the peripheral portion of the silicon substrate.

A suitable feature of the present invention is that after removing the silicon carbide film, the processing polishing tape is pressed against the peripheral edge portion of the silicon substrate, and the peripheral polishing of the silicon substrate is performed.

In another aspect of the present invention, the polishing method uses a polishing tape having a base material film made of polyimide, a binder made of polyimide, and abrasive particles held by the aforementioned binder. It is characterized in that the SOI wafer having a structure in which two substrates are bonded by an adhesive is rotated, and the polishing tape is pressed against the peripheral portion of the SOI wafer with a light force, and The peripheral part removes the aforementioned adhesive.

A suitable feature of the present invention is that after removing the adhesive, the processing polishing tape is pressed against the peripheral edge portion of the SOI wafer and the peripheral edge portion of the SOI wafer is processed and polished.

In the present invention, a polishing tape with high mechanical strength is used, and the polishing tape is further pressed against the peripheral edge portion of the wafer with a light force (for example, a force in a range of 3N to 10N). Therefore, the polishing tape is not damaged by a hard film such as a SiC film formed on a wafer peripheral portion or a solidified adhesive, and the polishing film can be used to remove the hard film.

1‧‧‧ grinding head

2‧‧‧Grinding liquid supply nozzle

3‧‧‧ Wafer holding section

4‧‧‧ keep the stage

4a‧‧‧ trench

5‧‧‧ hollow shaft

6‧‧‧ Ball Spline Bearing

7‧‧‧ Connected Path

8‧‧‧ Rotary Joint

9‧‧‧vacuum line

10‧‧‧Nitrogen Supply Line

11‧‧‧Action Control Department

12, 14‧‧‧ shell

15‧‧‧air cylinder

18‧‧‧ Radial Bearing

20‧‧‧ partition

20a‧‧‧ port

21‧‧‧ base plate

22‧‧‧Grinding Room

23‧‧‧ door

25‧‧‧grinding unit

27‧‧‧Setting table

28‧‧‧arm block

30‧‧‧ Grinding unit moving mechanism

31‧‧‧ball screw mechanism

32‧‧‧ Motor

33‧‧‧Power Transmission Agency

40A, 40B‧‧‧ linear guide

41A, 41B‧‧‧Connecting blocks

42A, 42B‧‧‧Motor

43A, 43B‧‧‧ Ball Screw

44A, 44B‧‧‧Supporting parts

50‧‧‧Grinding head

51‧‧‧Pressing parts

51a‧‧‧through hole

52‧‧‧Press part holder

53‧‧‧Air Cylinder

54‧‧‧ linear guide

55‧‧‧ holding parts

56‧‧‧Air Cylinder

57‧‧‧Mounting parts

58‧‧‧ linear guide

60‧‧‧vacuum line

62‧‧‧box

63‧‧‧Position sensor

63A‧‧‧Light Project Department

63B‧‧‧Light receiving section

64‧‧‧ convex claw

70‧‧‧ Abrasive belt supply recovery mechanism

71‧‧‧Supply Scroll

72‧‧‧ Recovery Scroll

73, 74‧‧‧Tension motor

76‧‧‧Grinding belt feeding mechanism

77‧‧‧ with feed roller

78‧‧‧ pinch roller

79‧‧‧ with feed motor

81‧‧‧base

82, 83‧‧‧ support arm

84A, 84B, 84C, 84D, 84E‧‧‧Guide rollers

100‧‧‧ with edge detection sensor

100A‧‧‧light projection department

100B‧‧‧Light receiving section

110‧‧‧ Corner Grinding Unit

111‧‧‧Grinding head assembly

112‧‧‧ Abrasive belt supply recovery mechanism

124‧‧‧Supply Scroll

125‧‧‧ Recovery Scroll

131‧‧‧ grinding head

135‧‧‧arm

138‧‧‧ Motor

140‧‧‧mobile station

141‧‧‧ linear guide

143‧‧‧Link board

145‧‧‧ linear actuator

146‧‧‧connector

150‧‧‧Pressing mechanism

151‧‧‧ with feed mechanism

151a‧‧‧with feed roller

151b‧‧‧ pinch roller

151c‧‧‧Motor

153A, 153B, 153C, 153D, 153E, 153F, 153G‧‧‧Guide rollers

155‧‧‧Pressing parts

156‧‧‧Air Cylinder

161a, 161b‧‧‧‧protrusions

162‧‧‧Press pad

180‧‧‧ abrasive belt

181‧‧‧Matrix material film

182‧‧‧First floor

183‧‧‧second floor

184‧‧‧ Abrasive particles

185‧‧‧ surface

190‧‧‧ processing abrasive belt

191‧‧‧First Coating

192‧‧‧Second Coating

195‧‧‧ divider

200‧‧‧ manufacturing equipment

210‧‧‧coater storage tank

220‧‧‧ Notch roller

230‧‧‧coating roller

240, 250‧‧‧ roller

260‧‧‧ hot air dryer

270‧‧‧ mandrel

290‧‧‧ Oven

301‧‧‧ silicon substrate

302‧‧‧Element substrate

310‧‧‧ Silicon Carbide Film (SiC Film)

313‧‧‧Adhesive

315‧‧‧Si layer

316‧‧‧component layer

b2‧‧‧belt

Ct‧‧‧rotation axis

E1, E2‧‧‧Edge

M1‧‧‧Motor

P‧‧‧Upward slope

p1, p2, p3, p4‧‧‧ pulley

Q‧‧‧ lower slope

R‧‧‧ side

W‧‧‧ Wafer

The first (a) and the first (b) views are enlarged cross-sectional views showing the peripheral portion of the wafer.

The second figure is a schematic diagram of a polishing apparatus that can perform a polishing method according to an embodiment of the present invention.

The third figure is a cross-sectional view showing the detailed structure of the polishing tape shown in the second figure.

The fourth diagram is a diagram showing a manufacturing process of the above-mentioned polishing tape.

The fifth figure is a schematic configuration diagram showing an apparatus for manufacturing a polishing tape.

The sixth diagram is an explanatory diagram of a situation in which the abrasive belt is rolled up.

The seventh figure is a plan view of a polishing device including: an edge grinding unit capable of grinding a wafer edge portion; and a corner grinding unit capable of grinding a wafer corner portion (Bevel).

The eighth figure is a longitudinal sectional view of the polishing apparatus shown in the seventh figure.

The ninth figure is a figure viewed from an arrow G direction of the eighth figure.

The tenth figure is a plan view of the polishing head and polishing tape supply and recovery mechanism.

The eleventh figure is a front view of the polishing head and polishing tape supply and recovery mechanism.

The twelfth figure is a sectional view taken along the line H-H shown in the eleventh figure.

The thirteenth figure is a side view of the polishing tape supply and recovery mechanism shown in the eleventh figure.

The fourteenth figure is a longitudinal sectional view of the polishing head shown in the eleventh figure when viewed from the direction indicated by the arrow I.

The fifteenth figure is a view of the position sensor and the dog viewed from above.

The sixteenth figure is a plan view of the polishing head and polishing tape supply and recovery mechanism moved to a designated polishing position.

The seventeenth figure is a schematic view of the pressing member, the polishing tape, and the wafer viewed in the polishing position in a lateral direction.

The eighteenth figure is a diagram showing a state where the polishing tape is pressed against the wafer by the pressing member.

The nineteenth (a) diagram is a view of the polishing tape and the pressing member at the polishing position viewed from the radial direction of the wafer, and the nineteenth (b) diagram is a diagram showing a state where the lower surface of the pressing member is in contact with the upper surface of the polishing tape. The nineteenth (c) diagram is a diagram showing a state where the pressing member presses the polishing tape against the wafer.

FIG. 20 is an enlarged view showing a peripheral edge portion of a wafer polished by a polishing tape.

Figures 21 (a), 21 (b), and 21 (c) are explanatory diagrams of the operation when detecting the edge portion of the polishing belt.

Figure 22 is an enlarged view of the polishing head shown in Figure 8.

The twenty-third figure is a front view of the pressing member shown in the twenty-second figure.

The twenty-fourth figure is a side view of the pressing member shown in the twenty-third figure.

The twenty-fifth figure is a sectional view taken along the line J-J of the twenty-third figure.

The twenty-sixth figure is a view showing a situation where the corner grinding unit grinds the corners of the wafer.

The twenty-seventh figure is a view showing a situation where the corner grinding unit grinds the upper edge portion of the wafer.

The twenty-eighth figure is a view showing a situation where the corner grinding unit grinds the lower edge portion of the wafer.

The twenty-ninth figure is a cross-sectional view of a wafer having a structure in which a SiC film is formed on a silicon substrate.

Figures thirty (a), thirty (b), thirty (c), and thirty (d) are explanatory diagrams of the SOI wafer manufacturing process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The polishing apparatus of this embodiment polishes the peripheral edge portion of the wafer by sliding the polishing surface of the polishing tape to the peripheral edge portion of the wafer. In this specification, the peripheral edge portion of a wafer is defined as a region including a corner portion located on the outermost periphery of the wafer and an edge portion located on the inner side in the radial direction of the corner portion.

The first (a) and the first (b) views are enlarged cross-sectional views showing the peripheral portion of the wafer. More specifically, the first (a) diagram is a so-called straight-side wafer cross-sectional view, and the first (b) diagram is a so-called round-shaped wafer cross-sectional view. In the wafer W of the first (a) figure, the corner portion is formed by the upper inclined portion (the upper corner portion). The outermost peripheral surface (denoted by symbol B) of the wafer W constituted by P, the lower inclined portion (lower corner portion) Q, and the side portion (top end) R. In the wafer W of the first (b) diagram, the corner portions are portions (designated by symbol B) having a curved cross-section that constitute the outermost peripheral surface of the wafer W. The edge portions E1 and E2 are regions located inside the corner portion B. The upper edge portion E1 is a flat portion located inside the corner portion B and located outside the region D where the element is formed. The lower edge portion E2 is a flat portion on the back surface of the wafer W located on the opposite side of the upper edge portion E1. In the following description, the upper edge portion E1 and the lower edge portion E2 may be collectively referred to as the edge portion E for short.

The second figure is a schematic diagram of a polishing apparatus that can perform a polishing method according to an embodiment of the present invention. The polishing apparatus includes: a wafer holding portion 3 that holds the wafer W and rotates around its axis; and a polishing tape 180 that presses the polishing tape 180 on the peripheral portion of the wafer W held on the wafer holding portion 3 to polish the peripheral portion of the wafer W. A polishing head 1; and a polishing liquid supply nozzle 2 that supplies a polishing liquid to the surface (upper surface) of the wafer W held on the wafer holding portion 3. An example of the polishing liquid used is pure water.

The wafer W polished by the polishing method of this embodiment is a wafer in which a hard film is formed on a silicon substrate. The hard film is a film composed of a silicon carbide film (SiC film) 310 shown in FIG. 29 or a solidified adhesive 313 shown in FIG. 30.

Wafer W is polished as follows. The wafer W is placed on a wafer holding portion 3 by a transfer device (not shown), and the wafer holding portion 3 holds the lower surface of the wafer W by a known means such as vacuum suction. The wafer holding unit 3 rotates the wafer W about its axis. The polishing liquid supply nozzle 2 supplies a polishing liquid (for example, pure water) onto the rotating wafer W (including the peripheral edge portion of the wafer W), and the polishing head 1 presses the polishing surface of the polishing tape 180 against the peripheral edge portion of the wafer W ( That is, the edge portion and the corner portion), and the hard film (SiC film or adhesive) is removed from the peripheral edge portion of the wafer W.

After removing the hard film (SiC film or adhesive) from the peripheral edge of the wafer W, A processing polishing tape 190 is provided on the polishing head 1 instead of the polishing tape 180, and the processing polishing tape 190 is pressed against the peripheral edge portion of the wafer W by the polishing head 1 to perform processing polishing on the peripheral edge portion of the wafer W. The processing abrasive belt 190 has abrasive grains smaller than the abrasive belt 180. The base material film of the processing abrasive belt 190 is a polyimide belt or a PET belt. By performing such processing and polishing, the surface of the wafer after polishing can be smoothed, and dust or particles cannot be easily attached to the wafer W.

The polishing tape 180 has abrasive particles held on a polyimide as a binder. Therefore, the polishing surface of the polishing belt 180 is composed of abrasive particles and polyimide. When the SiC film on a silicon substrate was polished using the polishing tape 180, polyimide as a binder contacted the SiC film, and the polyimide had water repellency (hydrophobicity). Therefore, during wafer W polishing, the polishing surface of the polishing tape 180 polishes the peripheral edge portion of the wafer W in a water-repellent state.

In wafer W polishing, the force exerted by the polishing tape 180 on the periphery of the wafer W should preferably be 3N to 10N. Because of this, the polishing speed (removal speed) decreases when the peripheral edge portion of the wafer W is polished with a force smaller than 3N. When the peripheral edge portion of the wafer W is polished with a force larger than 10N, the polishing tape may be damaged as described above. Generally, the force applied to the wafer by the polishing tape is about 12N. However, the force applied to the wafer W by the polishing tape 180 in this embodiment is in the range of 3N to 10N, which is smaller than the force generally used. By polishing the wafer W with such a low load, the pressure on the wafer W is reduced, and damage to the polishing tape 180 is reduced. As a result, the service life of the polishing belt 180 can be extended, and the usage amount of the polishing belt 180 can be reduced.

The third figure is a cross-sectional view showing the detailed structure of the polishing tape shown in the second figure. The polishing tape 180 includes a base material film 181, a first layer 182, and a second layer 183. The first layer 182 is formed on one side of the base material film 181. The second layer 183 is formed on the first layer 182. The second layer 183 contains abrasive particles 184. Most of the abrasive particles 184 are located inside the second layer 183. A part of the abrasive particles 184, and more specifically, a part of the abrasive particles 184 having a relatively large particle diameter are in the first layer 182. Grind The surface of the particles 184 may be completely covered by the second layer 183, or a part thereof may be exposed from the surface of the second layer 183.

The base material film 181 imparts necessary strength to the polishing tape 180 and improves the rationality of the polishing tape 180. The base material film 181 of this embodiment is made of polyimide. When polyfluorene is used, the strength can be improved compared to a conventional abrasive tape using PET or the like as a base material film.

The thickness of the base material film 181 in this embodiment is 38 μm. The thickness of the base material film 181 should be 10 μm or more. As described above, when the polishing tape 180 is manufactured, wrinkles and fractures are less likely to occur on the base material film 181, and handling properties are improved. In addition, the thickness of the base material film 181 should be 50 μm or less. In this way, when polishing the wafer, the polishing tape 180 easily bends along the shape of the peripheral edge portion of the wafer.

The first layer 182 and the second layer 183 have a function of holding an adhesive of the abrasive particles 184. The first layer 182 also functions as a base layer of the second layer 183. The first layer 182 and the second layer 183 of this embodiment are made of polyimide. The first layer 182 may be made of polyimide, and the second layer 183 may be made of polyimide and a filler. The filler is a material that enhances the affinity of the polyimide and the abrasive particles 184. As the filler, for example, silica particles can be used. The first layer 182 can improve the adhesion between the first layer 182 and the base material film 181 by using the same material as the base material film 181.

The thickness of the first layer 182 in this embodiment is 10 μm. The thickness of the second layer 183 is about 3 μm. The thickness of the second layer 183 should be more than 1/5 of the average particle diameter of the abrasive particles 184. In this way, the holding strength of the abrasive particles 184 can be appropriately obtained. The thickness of the second layer 183 should be ½ or less of the average particle diameter of the abrasive particles 184. As such, the abrasive particles 184 are not excessively covered by the second layer 183. As a result, it is possible to appropriately obtain the function of the abrasive particles 184 as a blade.

The abrasive particles 184 are abrasive particles, and generate a blade effect when grinding a wafer. Abrasive grains 184 can be used, for example, diamond particles, silicon carbide (SiC), alumina (Al ₂ O _3), silicon dioxide (SiO _2), manganese oxide (MnO ₂₎ and the like. The abrasive particles 184 of this embodiment are particles of industrial diamond (polycrystalline diamond). The average particle diameter of the abrasive particles 184 in this embodiment is 9 μm. However, the average particle diameter of the abrasive particles 184 can be appropriately selected between 0.1 μm and 20 μm.

In the above-mentioned polishing tape 180, the first layer 182 and the second layer 183 are distinguished conceptually according to the manufacturing method of the polishing tape 180 described below, and are not limited to the physical identification of the two after the polishing tape 180 is manufactured. For example, when the first layer 182 and the second layer 183 are made of the same material, the boundary between the first layer 182 and the second layer 183 cannot be actually confirmed. Therefore, the first layer 182 and the second layer 183 may be regarded as one surface layer 185.

As shown in the third figure, in the polishing belt 180, all the abrasive grains 184 are located in the thickness (approximately 13 μm) direction of the surface layer 185 on the half of the opposite side to the base material film 181, in other words, in the range of half of the surface side. The abrasive grains 184 are held near the surface of the surface layer 185. In other words, it is not a state in which the plurality of abrasive particles 184 are stacked in the thickness direction of the base material film 181. Therefore, the entire surface or substantially the entire surface of each abrasive particle 184 is held in contact with the surface layer 185 as a binder. As described above, since the abrasive particles 184 are strongly held on the surface layer 185 as an adhesive, the polishing tape 180 can polish the hard film described above. In addition, since the surface layer 185 is mainly formed of polyimide, the holding strength of the abrasive grains 184 is further improved compared to when a polyester or the like is used.

In addition, since the abrasive particles 184 do not accumulate in the thickness direction of the polishing belt 180, the amount of the abrasive particles 184 can be reduced. The result contributes to cost reduction and resource conservation. Moreover, the protruding heights of the abrasive particles 184 of the abrasive belt 180 are not significantly irregular. Therefore, during polishing, since the protrusions of the abrasive particles 184 are brought into substantially uniform contact with the object to be polished, it is possible to suppress uneven polishing or scratches. In addition, since there are no abrasive particles 184 on the contact surface between the base material film 181 and the first layer 182, the adhesion between the base material film 181 and the first layer 182 is also high. Of these abrasive belts 180 The feature is realized by a manufacturing method of the polishing tape 180 described later.

In addition, since the polishing tape 180 uses a polyimide having high strength as the material of the base material film 181, the base material itself has high tensile strength and breaking strength. Therefore, compared with the case where PET, PEN, PP, and PE are generally used as the base material, the polishing tape 180 can suppress the problems of the extension of the polishing tape or unstable processing during processing. This problem tends to occur when the width of the polishing tape is small, for example, 10 mm or less.

The fourth diagram is a manufacturing process diagram of the polishing belt 180 described above. The fifth diagram is a schematic configuration diagram showing the manufacturing apparatus 200 of the polishing tape 180. As shown in the fourth figure, when manufacturing the polishing tape 180, first, a base material film 181 is prepared, and a first coating material 191 is applied to one of the base material films 181 (step S110).

The substrate film 181 of this embodiment is a polyimide-based Pomiran N38 (made by Arakawa Chemical). The base material film 181 should be a thin film that has been completely imidized in advance. As such, since the strength of the base material film 181 is high, the rationality of the base material film 181 is improved. Whether the substrate is completely imidized can be again imidized, and the base film 181 can be imidized again, and it can be investigated by comparing the weight before and after. For example, a 5 cm ² area is cut out of the base material film 181 as a sample, and the sample is imidized under the conditions of a heating temperature of 300 ° C. and a heating time of 1 hour. It can be said that the sample having a sulfonium imidization rate of 70% or more calculated from the weight change and the amount of by-product water generated during the sulfonization process has been completely sulfonated.

The first paint 191 includes a solvent and a binder made of a resin. The resin solid content of the adhesive finally becomes the first layer 182. The adhesive is originally high in viscosity. By adding a solvent to the adhesive, the first coating material 191 is adjusted to a viscosity suitable for coating. The adhesive of this embodiment is a polyimide-silica hybrid varnish HBI-58 Manufactured by Sichuan Chemical Industry Co., Ltd.). As the solvent, for example, an alkylamidoamine solvent can be used. Due to the high polarity of the alkylamidine solvent, it can effectively disperse the dissolved matter whether it is organic or inorganic. As the alkylamidoamine solvent of this embodiment, DMAc (dimethylacetamido) is used. However, DMF (dimethylformamide) can also be used.

The first coating material 191 of this embodiment is prepared by dissolving 200 g of a binder and dissolving 50 g of DMAc in a vacuum container, and degassing and degassing in a vacuum container. The ratio of the solid resin content of the binder in the first coating material 191 is 20% by weight. This embodiment is between 25,000 and 30,000 mPa. The adhesive is provided at s / 25 ° C, and the viscosity of the first coating 191 is adjusted to 10,000 to 20,000 mPa by adding a solvent. s / 25 ° C.

The produced first coating material 191 is applied to one surface of the base material film 181. Specifically, as shown in the fifth figure, first, a base material film 181 (here, a width of 300 mm and a length of about 20 m) rolled into a roll is set in a manufacturing apparatus 200, and a notch roll The base material film 181 is sequentially sent between 220 and the coating roller 230. Thereby, the first coating material 191 stored in the coater dam 210 is coated on the base material film 181. The feeding speed (coating speed) of the base material film 181 may be, for example, 0.5 m / min.

The coating thickness of the first coating material 191 can be controlled by adjusting the gap between the notch roller 220 and the base material film 181. After the coating thickness of the first coating material 191 is dried in step S120 described later, it should be equal to or larger than the average particle diameter of the abrasive particles 184. In this way, in step S170 described later, a suitable thickness of the first layer 182 for sinking the abrasive particles 184 having a large particle diameter to the base material film side can be obtained. In addition, the coating thickness of the first coating material 191 should be 3 times or less the average particle diameter of the abrasive particles 184 after drying in step S120 described later. In this way, the first layer 182 is not formed excessively thick.

After the first coating material 191 is applied, as shown in the fourth figure, the first coating material 191 is dried to form a first layer 182 (step S120). In this embodiment, the first coating material 191 is dried by heating the first coating material 191 at a drying temperature of 130 ° C. for 2 minutes. Specifically, as shown in the fifth figure, the base material film 181 coated with the first coating material 191 is transported on rollers 240 and 250, and is heated by a hot air dryer 260 provided above the transport path of the base material film 181 Order dried. The heating range of the hot air dryer 260 may be, for example, a range of 1.0 m in the conveying direction of the base material film 181.

After the first coating material 191 is dried, as shown in the fourth figure, the base material film 181 on which the first layer 182 has been formed is rolled up into a roll shape (step S130). As shown in the fifth figure, the base material film 181 is wound on the hollow cylindrical mandrel 270.

After the base material film 181 is rolled up, as shown in the fourth figure, the rolled up base material film 181 is sequentially delivered, and a second coating material 192 is applied on the first layer 182 (step S140). The coating in step S140 is performed in the same manner as in the above-mentioned step 110 using the manufacturing apparatus 200 (see the fifth figure). In addition, the equipment for applying the first coating material 191 and the equipment for applying the second coating material 192 are provided separately. However, for the sake of simplicity, the fifth figure is shown by common equipment.

The second paint 192 includes a solvent, abrasive particles 184, and a binder made of resin. The resin solid content of the adhesive finally becomes the second layer 183. The adhesive used in the second paint 192 in this embodiment is the same type as the adhesive used in the first paint 191. The solvent and the binder of this embodiment are the same as those of the first coating material 191. In addition, the second coating material 192 was adjusted in viscosity similarly to the first coating material 191, was stirred, and was defoamed and degassed in a vacuum container to produce it. The ratio of the abrasive particles 184 in the second coating material 192 of this embodiment is 15 wt% based on the resin solid content of the second coating material 192. In addition, the ratio of the solid resin content of the binder in the second coating material 192 is 18% by weight.

The viscosity of the first paint 191 and the second paint 192 should be 10,000 mPa. s / 25 ℃ above, and it is 30,000mPa. s / 25 ℃ or less. When the viscosity is adjusted within this range, each component of the first coating material 191 and the second coating material 192 can obtain appropriate dispersibility. The ratio of the solid content of the resin to the first coating material 191 should be 5 wt% or more and 50 wt% or less. In this way, an appropriate film thickness of the first layer 182 and an appropriate dispersibility of the adhesive in the first paint 191 can be obtained. The ratio of the abrasive particles in the second coating material 192 to the resin solid content of the second coating material 192 should be 5 wt% or more and 30 wt% or less. The ratio of the solid content of the resin to the second coating material 192 should be 10 wt% or more and 50 wt% or less. In this way, an appropriate film thickness of the second layer 183, an appropriate holding strength of the abrasive particles 184, and an appropriate dispersibility of the binder and the abrasive particles 184 in the second coating material 192 can be obtained. In addition, compared with the conventional abrasive belt, the amount of abrasive particles 184 used can be greatly reduced.

After the second coating material 192 is applied, the second coating material 192 is dried to form a second layer 183 (step S150). The drying in step S150 is performed in the same manner as in the above step S120 using the manufacturing apparatus 200 (see the fifth figure).

After the second coating material 192 is dried, the base material film 181 having the first layer 182 and the second layer 183 formed thereon is rolled up into a roll shape (step S160). The rewinding in step S160 is performed in the same manner as in the above step S130 using the manufacturing apparatus 200 (see the fifth figure). However, in step S160, as shown in the sixth figure, a separator sheet 195 is disposed on the second layer 183, and a roll of the base material film 181 having the first layer 182 and the second layer 183 is formed. Close. In other words, the winding is performed so that the separator 195 is sandwiched between the base material films 181 adjacent to each other in the radial direction.

As the separator 195, various materials whose properties are not changed under the temperature conditions of the fluorene imidization step (step S170) described later can be used. For example, the separator 195 may be a non-woven fabric made of fully imidized polyimide fibers, or a polyimide film that is wrinkled. Separate As the sheet 195, an air-permeable cloth sheet such as a non-woven fabric should be used. In this way, the gas and moisture generated by the imidization are easily discharged.

After rolling up the base material film 181 having the first layer 182 and the second layer 183, finally, as shown in the fourth figure, the base material film 181 is placed in a vacuum oven, and the first layer 182 and The second layer 183 is imidized (step S170). In this embodiment, after the oven is closed and evacuated, the temperature is gradually increased, and the first layer 182 and the second layer 183 are heated at a temperature of 250 to 300 ° C. for 1 to 2 hours. Then, nitrogen or dry air is supplied in a vacuum oven, and naturally cooled under normal pressure. With this treatment, the imidization (hardening reaction) of the polyimide resin can be completed earlier than under normal temperature and pressure conditions. The processing conditions in step S170 may be appropriately set. However, in order to obtain an effective hardening reaction, the processing conditions should be heating in a range of 200 ° C or higher and 350 ° C or lower for 1 hour or more and 4 hours or less.

In step S170, the imidization (thermosetting reaction) starts from the periphery of the second layer 183 and the abrasive grains 184 having high thermal conductivity. Then, in a state where the first hardened film 183 presses the abrasive particles 184 into the first layer 182 side, the entire first layer 182 is gradually imidized (hardened) to the protruding height of the abrasive particles 184. A surface layer 185 (a first layer 182 and a second layer 183) is formed in a substantially neat manner near the surface of the second layer 183.

In step S170, as shown in the fifth figure, the rolled-up base material film 181 should be installed in the oven 290 with the rolled-up shaft facing the horizontal direction. By performing sulfonimidization in this state, the rolled base material film 181 is thermally expanded, and it is possible to suppress the occurrence of loosening or curling. In this manner, after the fluorene imidization is performed, the polishing belt 180 is completed.

Next, a detailed configuration of a polishing apparatus for executing the polishing method of the present embodiment will be described. The seventh diagram shows that the upper edge portion of the wafer can be polished (refer to the first (a) diagram and the first diagram). A (b) symbol E1) of the grinding unit 25 (hereinafter referred to as the edge grinding unit; and Bevel) (refer to the first (a) and the first (b) symbol B) A plan view of the grinding device of the corner grinding unit 110. The eighth figure is a longitudinal sectional view of the grinding device shown in the seventh figure.

The polishing apparatus includes a wafer holding unit 3 that horizontally holds and rotates a wafer W that is an object to be polished, and supplies a polishing liquid (for example, pure water) over the entire wafer W held by the wafer holding unit 3.的 磨 磨 液 Supplying nozzle 2. The eighth figure shows a state where the wafer holding portion 3 holds the wafer W. The wafer holding portion 3 includes a holding stage 4 that holds the lower surface of the wafer W by vacuum suction, a hollow shaft 5 connected to a central portion of the holding stage 4, and a motor M1 that rotates the hollow shaft 5. The wafer W is placed on a holding stage 4 in which the center of the wafer W is aligned with the axis of the hollow shaft 5. The holding stage 4 is arranged in a polishing chamber 22 formed by a partition wall 20 and a base plate 21.

As shown in FIGS. 7 to 9, the partition wall 20 includes a transfer port 20 a for carrying the wafer W into and out of the polishing chamber 22. The transfer opening 20a is formed with a notch extending horizontally. The transfer port 20 a can be closed by a shutter 23.

The hollow shaft 5 is supported by a ball spline bearing (linear motion bearing) 6 to move up and down freely. A groove 4 a is formed on the holding stage 4, and the groove 4 a communicates with a communication path 7 extending through the hollow shaft 5. The communication path 7 is connected to the vacuum line 9 via a rotary joint 8 installed at the lower end of the hollow shaft 5. The communication path 7 is also connected to a nitrogen supply line 10 for separating the processed wafer W from the holding stage 4. By switching between the vacuum line 9 and the nitrogen supply line 10, the wafer W can be held or detached from the holding stage 4.

The hollow shaft 5 is rotated by the motor M1 via a pulley p1 connected to the hollow shaft 5, a pulley p2 mounted on a rotating shaft of the motor M1, and a belt b1 hanging on the pulleys p1 and p2. The ball spline bearing 6 is a bearing that allows the hollow shaft 5 to move freely in its length direction. roll The bead spline bearing 6 is fixed in a cylindrical casing 12. Therefore, the hollow shaft 5 can move linearly up and down to the housing 12, and the hollow shaft 5 and the housing 12 rotate integrally. The hollow shaft 5 is connected to the air cylinder 15 (elevating mechanism), and the hollow shaft 5 and the holding stage 4 can be raised and lowered by the air cylinder 15.

A radial bearing 18 is interposed between the housing 12 and a cylindrical housing 14 concentrically arranged on the outside thereof, and the housing 12 is rotatably supported by the bearing 18. With this configuration, the wafer holding unit 3 can rotate the wafer W around its central axis, and can raise and lower the wafer W along its central axis.

A polishing unit 25 that polishes the peripheral edge portion of the wafer W is disposed outside the wafer W held in the wafer holding portion 3 in the radial direction. The polishing unit 25 is disposed inside the polishing chamber 22. As shown in the ninth figure, the entire polishing unit 25 is fixed on the setting table 27. The setting table 27 is connected to the polishing unit moving mechanism 30 via an arm block 28.

The polishing unit moving mechanism 30 includes a ball screw mechanism 31 that holds the arm block 28 slidably, a motor 32 that drives the ball screw mechanism 31, and a power transmission mechanism 33 that connects the ball screw mechanism 31 and the motor 32. The power transmission mechanism 33 includes a pulley, a belt, and the like. When the motor 32 is operated, the ball screw mechanism 31 moves the arm block 28 in the direction indicated by the arrow in the ninth figure, and the entire polishing unit 25 moves in the tangential direction of the wafer W. The polishing unit moving mechanism 30 may also function as an oscillating mechanism that causes the polishing unit 25 to swing at a predetermined amplitude and a predetermined speed.

The polishing unit 25 includes a polishing head 50 that polishes the periphery of the wafer W using the polishing tape 180, and a polishing tape supply recovery mechanism 70 that supplies the polishing tape 180 to the polishing head 50 and recovers the polishing tape 50 from the polishing head 50. The polishing head 50 presses the polishing surface of the polishing tape 180 downward on the peripheral edge portion of the wafer W to polish the upper edge portion of the wafer W (refer to the symbol E1 in the first (a) and first (b) drawings). Edge grinding head.

The tenth figure is a plan view of the polishing head 50 and the polishing-belt supply and recovery mechanism 70, the eleventh figure is a front view of the polishing head 50 and the polishing-belt supply and recovery mechanism 70, and the twelfth image is a cross-section taken on line HH shown in the eleventh figure FIG. 13 is a side view of the polishing tape supply and recovery mechanism 70 shown in FIG. 11, and FIG. 14 is a longitudinal sectional view of the polishing head 50 shown in FIG. 11 as viewed from a direction indicated by an arrow I .

On the setting table 27, two linear guides 40A and 40B extending parallel to the radial direction of the wafer W are arranged. The polishing head 50 and the linear guide 40A are connected via a connection block 41A. The polishing head 50 is connected to a motor 42A and a ball screw 43A that move the polishing head 50 along the linear guide 40A (that is, the radial direction of the wafer W). More specifically, the ball screw 43A is fixed to the connection block 41A, and the motor 42A is fixed to the installation base 27 via the support member 44A. The motor 42A is configured to rotate the screw shaft of the ball screw 43A, whereby the connection block 41A and the polishing head 50 connected thereto move along the linear guide 40A. The motor 42A, the ball screw 43A, and the linear guide 40A constitute a first moving mechanism that moves the polishing head 50 in the radial direction of the wafer W held by the wafer holding portion 3.

Similarly, the polishing-belt supply-recovery mechanism 70 and the linear guide 40B are connected via a connection block 41B. The polishing tape supply and recovery mechanism 70 is connected to a motor 42B and a ball screw 43B that move the polishing tape supply and recovery mechanism 70 along the linear guide 40B (that is, in the radial direction of the wafer W). More specifically, the ball screw 43B is fixed to the connection block 41B, and the motor 42B is fixed to the installation base 27 via the support member 44B. The motor 42B is configured to rotate the screw shaft of the ball screw 43B, whereby the connection block 41B and the polishing-belt supply and recovery mechanism 70 connected thereto move along the linear guide 40B. The motor 42B, the ball screw 43B, and the linear guide 40B constitute a second moving mechanism that moves the polishing tape supply and recovery mechanism 70 in the radial direction of the wafer W held by the wafer holding portion 3.

As shown in FIG. 14, the polishing head 50 includes: pressing the polishing tape 180 on the wafer W; A pressing member 51; a pressing member holder 52 that holds the pressing member 51; and an air cylinder 53 as an actuator that depresses the pressing member holder 52 (and the pressing member 51). The air cylinder 53 is held by a holding member 55. The holding member 55 is connected to the air cylinder 56 as a lifting mechanism via a linear guide 54 extending in the vertical direction. When a gas such as air is supplied from a gas supply source (not shown) to the air cylinder 56, the air cylinder 56 lifts up the holding member 55. Thereby, the holding member 55, the air cylinder 53, the pressing member holder 52, and the pressing member 51 are lifted along the linear guide 54.

The air cylinder 56 is fixed to a mounting member 57 fixed to the connecting block 41A. The mounting member 57 and the pressing member holder 52 are connected via a linear guide 58 extending in the vertical direction. When the pressing member holder 52 is depressed by the air cylinder 53, the pressing member 51 moves downward along the linear guide 58, and the polishing tape 180 is pressed against the peripheral edge portion of the wafer W. The pressing member 51 is formed of a resin such as PEEK (polydiether ketone), a metal such as stainless steel, or a ceramic such as SiC (silicon carbide).

The pressing member 51 includes a plurality of through holes 51 a extending in the vertical direction, and the through hole 51 a is connected to a vacuum line 60. A valve (not shown) is provided in the vacuum line 60, and a vacuum can be formed in the through hole 51a of the pressing member 51 by opening the valve. When a vacuum is formed in the through-hole 51 a while the pressing member 51 is in contact with the upper surface of the polishing belt 180, the upper surface of the polishing belt 180 is held below the pressing member 51. In addition, one through hole 51a of the pressing member 51 may be provided.

The pressing member holder 52, the air cylinder 53, the holding member 55, the air cylinder 56, and the mounting member 57 are housed in a box 62. The lower part of the pressing member holder 52 protrudes from the bottom of the box 62, and the lower part of the pressing member holder 52 is mounted with a pressing member 51. A position sensor 63 that detects a position of the pressing member 51 in the vertical direction is arranged in the case 62. The position sensor 63 is mounted on a mounting member 57. The pressing member holder 52 is provided with a dog 64 as a sensor target. The position sensor 63 can detect the position of the pressing member 51 in the vertical direction from the position of the dog 64 in the vertical direction.

The fifteenth figure is a view of the position sensor 63 and the pawl 64 as viewed from above. The position sensor 63 includes a light projecting section 63A and a light receiving section 63B. When the claw 64 is lowered together with the pressing member holder 52 (and the pressing member 51), a part of the light emitted from the light projecting portion 63A is shielded by the claw 64. Therefore, the position of the claw 64, that is, the position of the pressing member 51 in the vertical direction can be detected from the amount of light received by the light receiving section 63B. In addition, the position sensor 63 shown in FIG. 15 is a so-called transmissive optical sensor, but other types of position sensors may be used.

The polishing tape supply and recovery mechanism 70 includes a supply reel 71 for supplying the polishing tape 180 and a recovery reel 72 for collecting the polishing tape 180. The supply reel 71 and the recovery reel 72 are connected to tension motors 73 and 74, respectively. These tension motors 73 and 74 can apply a specified torque to the supply reel 71 and the recovery reel 72 to apply a predetermined tension to the polishing belt 180.

A polishing belt feeding mechanism 76 is provided between the supply reel 71 and the recovery reel 72. The polishing belt feeding mechanism 76 includes a belt feeding roller 77 that feeds the polishing belt 180, a nip roller 78 that presses the polishing belt 180 against the belt feeding roller 77, and a belt feeding motor 79 that rotates the belt feeding roller 77. The polishing belt 180 is sandwiched between a nip roller 78 and a belt feed roller 77. The abrasive belt 180 is fed from the supply reel 71 to the recovery reel 72 by rotating the belt feed roller 77 in the direction indicated by the arrow in FIG. 11.

The tension motors 73 and 74 and the belt feeding motor 79 are provided on the base 81. The base 81 is fixed to the connecting block 41B. The base 81 includes two support arms 82 and 83 extending from the supply reel 71 and the recovery reel 72 toward the polishing head 50. A plurality of guide rollers 84A, 84B, 84C, 84D, and 84E supporting the polishing belt 180 are mounted on the support arms 82 and 83. The polishing belt 180 is guided by the guide rollers 84A to 84E so as to surround the polishing head 50.

When the direction in which the polishing tape 180 extends is viewed from above, it is perpendicular to the radial direction of the wafer W. The two guide rollers 84D, 84E located below the grinding head 50 use the grinding surface of the grinding belt 180 and the crystal The circular W surface (upper surface) supports the polishing belt 180 in a parallel manner. The polishing belt 180 between the two guide rollers 84D and 84E extends parallel to the tangential direction of the wafer W. A gap is formed between the polishing tape 180 and the wafer W in the vertical direction.

The polishing apparatus further includes a belt edge detection sensor 100 that detects the position of the edge of the polishing belt 180. The edge detection sensor 100 is a transmission-type optical sensor similar to the position sensor 63 described above. The band edge detection sensor 100 includes a light projecting section 100A and a light receiving section 100B. The light projecting section 100A is fixed to the installation table 27 as shown in the tenth figure, and the light receiving section 100B is fixed to the base plate 21 forming the polishing chamber 22 as shown in the eighth figure. The belt edge detection sensor 100 is configured to detect the edge position of the polishing tape 180 from the amount of light received by the light receiving unit 100B.

As shown in FIG. 16, when the wafer W is polished, the polishing head 50 and the polishing tape supply and recovery mechanism 70 are moved to designated polishing positions by the motors 42A and 42B and the ball screws 43A and 43B, respectively. The polishing tape 180 at the polishing position extends in a tangential direction of the wafer W. The seventeenth figure is a schematic view of the pressing member 51, the polishing tape 180, and the wafer W viewed from the lateral direction in the polishing position. As shown in FIG. 17, the polishing tape 180 is located above the peripheral edge portion of the wafer W, and a pressing member 51 is further provided above the polishing tape 180. The eighteenth figure is a diagram showing a state where the polishing tape 180 is pressed against the wafer W by the pressing member 51. As shown in FIG. 18, the edge portion of the pressing member 51 at the polishing position coincides with the edge portion of the polishing belt 180. That is, the polishing head 50 and the polishing tape supply / recovery mechanism 70 are independently moved to the polishing position so that the edge portion of the pressing member 51 and the edge portion of the polishing belt 180 coincide with each other.

Next, the polishing operation of the polishing apparatus configured as described above will be described. The operation of the polishing apparatus described below is controlled by the operation control unit 11 shown in FIG. The wafer W is held on the wafer holding portion 3 with a film (for example, an element layer) formed on the surface thereof facing upward, and is rotated around the center of the wafer W. The center of the rotating wafer W is supplied with liquid from a liquid supply mechanism (not shown). (For example, pure water). The pressing member 51 and the polishing belt 180 of the polishing head 50 are respectively moved to a predetermined polishing position as shown in FIG. 17.

The nineteenth (a) diagram shows the polishing tape 180 and the pressing member 51 at the polishing position when viewed from the radial direction of the wafer W. In a state where the pressing member 51 shown in the nineteenth (a) is lifted by the air cylinder 56 (see the fourteenth figure), the pressing member 51 is positioned above the polishing belt 180. Next, the operation of the air cylinder 56 is stopped, and the piston rod is lowered. As shown in FIG. 19 (b), the pressing member 51 is lowered until the lower surface thereof contacts the upper surface of the polishing belt 180. In this state, a vacuum is formed in the through-hole 51 a of the pressing member 51 through the vacuum line 60, and the polishing tape 180 is held below the pressing member 51. While holding the polishing belt 180, the pressing member 51 is lowered by the air cylinder 53 (refer to FIG. 14). As shown in FIG. Pressed on the peripheral edge portion of the wafer W. The polishing load can be adjusted by the gas pressure supplied to the air cylinder 53.

The peripheral portion of the wafer W is polished by the sliding contact between the rotating wafer W and the polishing tape 180. In order to improve the polishing rate of the wafer W, the polishing belt 180 is also shaken along the tangential direction of the wafer W by the polishing unit moving mechanism 30 during the wafer W polishing. During polishing, a liquid (for example, pure water) is supplied to the center of the rotating wafer W, and the wafer W is polished in the presence of water. The liquid supplied to the wafer W is spread to the entire upper surface of the wafer W by the centrifugal force, thereby preventing the grinding debris from adhering to the elements formed on the wafer W. As described above, during polishing, the polishing tape 180 is held by the pressing member 51 by vacuum suction, so that the position of the polishing tape 180 and the pressing member 51 is prevented from being shifted. Therefore, the polishing position and the polishing shape can be stabilized. Furthermore, even if the polishing load is increased, since the positions of the polishing belt 180 and the pressing member 51 are not shifted, the polishing time can be shortened.

Since the polishing tape 180 is pressed down by the pressing member 51, it can be polished The upper edge portion of the wafer W (see the symbol E1 in the first (a) and first (b) drawings). The twentieth figure is an enlarged view showing the peripheral edge portion of the wafer W polished by the polishing tape 180. As shown in FIG. 20, in a state where the edge portion of the polishing tape 180 and the edge portion of the pressing member 51 coincide, the flat portion including the edge portion of the polishing tape 180 is pressed against the peripheral edge portion of the wafer W. As shown in FIG. 30 (d), the polishing tape 180 may form a right-angle stepped recess in the peripheral portion of the wafer W.

The diameter of the wafer W polished in this embodiment is in the range of 150 mm to 450 mm. The width of the polishing tape 180 used for polishing the wafer W is 30 mm to 80 mm. The width of the pressing member 51 (the width in a direction perpendicular to the length direction of the polishing tape 180) is 4 mm smaller than the width of the polishing tape 180 to the specific polishing. With 180 wide width. Under these conditions, the polishing tape 180 polishes the peripheral edge portion of the wafer W, especially the upper edge portion of the wafer W with a force of 3 to 10 N (refer to the symbol E1 in the first (a) and first (b) drawings). .

Compared with the conventional polishing tape made of PET (polyethylene terephthalate), the polishing tape 180 of this embodiment is less susceptible to damage because it has high strength and heat resistance. In particular, since the peripheral edge portion of the wafer W is polished with a small force of 3 to 10 N, the pressure of the polishing tape 180 becomes small. Therefore, even when the hard film of the wafer W is polished, the replacement frequency of the polishing tape 180 can still be reduced.

After the peripheral edge portion of the wafer W is polished with the polishing tape 180, instead of the polishing tape 180, a processing polishing tape may be set on the polishing head 50 and the polishing tape supply recovery mechanism 70 to perform processing polishing on the peripheral edge portion of the wafer W. As the processing abrasive belt, the processing abrasive belt 190 described with reference to the second figure can be used.

The position of the pressing member 51 in the vertical direction during the wafer W polishing is detected by the position sensor 63. Therefore, the polishing end point can be detected from the position of the pressing member 51 in the vertical direction. For example, when the position of the pressing member 51 in the vertical direction reaches a designated target position, the wafer W cycle can be ended. Edge grinding. The designated target position is determined according to the target polishing amount.

When the wafer W is polished, the supply of gas to the air cylinder 53 is stopped, whereby the pressing member 51 is raised to the position shown in the nineteenth (b). At the same time, the vacuum suction of the polishing belt 180 is stopped. Further, the pressing member 51 is raised to the position shown in the nineteenth (a) diagram by the air cylinder 56. Thereafter, the polishing head 50 and the polishing tape supply and recovery mechanism 70 are moved to the avoiding position shown in the tenth figure.

The polished wafer W is raised by the wafer holding portion 3 and is carried out of the polishing chamber 22 by an arm of a transfer mechanism (not shown). Before the next wafer starts to be polished, the polishing tape 180 is fed by the polishing tape feeding mechanism 76 from the supply reel 71 to a specified distance to the recovery reel 72. As a result, a new polishing surface is used for polishing the next wafer. The wafer W may also be polished by the polishing tape feeding mechanism 76 feeding the polishing tape 180 at a specified speed. At this time, it is not necessary to hold the polishing tape 180 by vacuum suction. Furthermore, the polishing belt 180 may be fed by the polishing belt feeding mechanism 76 while the polishing belt 180 is maintained by vacuum suction.

The abrasive belt 180 is an elongated belt-shaped abrasive tool. The width of the polishing tape 180 is substantially constant over its entire length. However, there may be some differences in the width of different portions of the polishing tape 180. Therefore, the edge position of the polishing tape 180 at the polishing position may vary from wafer to wafer. The position of the pressing member 51 at the polishing position is always constant. Therefore, in order to align the edge portion of the polishing tape 180 with the edge portion of the pressing member 51, the edge position of the polishing tape 180 is detected by the belt edge detection sensor 100 described above before moving to the polishing position.

The diagrams from the twenty-first (a) to the twenty-first (c) are operation explanatory diagrams when the edge portion of the polishing tape 180 is detected. Before the wafer W is polished, the polishing tape 180 is moved from the avoidance position shown in FIG. 21 (a) to the tape edge detection position shown in FIG. 21 (b). At this tape edge detection position, the position of the edge of the polishing tape 180 on the wafer side is detected by the tape edge detection sensor 100. Then, as As shown in FIG. 21 (c), the polishing tape 180 is moved to the polishing position so that the edge portion of the polishing tape 180 matches the edge portion of the pressing member 51. Since the polishing belt 180 can be moved independently from the polishing head 50, the polishing belt 180 can be moved by a distance that varies depending on the width of the polishing belt 180.

The edge position of the pressing member 51 at the polishing position is stored in the motion control unit 11 in advance (see the seventh figure). Therefore, the motion control unit 11 can calculate the moving distance of the polishing tape 180 that matches the edge of the polishing tape 180 with the edge of the pressing member 51 from the detected edge position of the polishing tape 180 and the edge position of the pressing member 51. . In this way, since the moving distance of the polishing tape 180 is determined based on the detected edge position of the polishing tape 180, the edge of the polishing tape 180 can always be aligned with the pressing member 51 regardless of the width variation of the polishing tape 180. Of the edge.

As shown in FIGS. 7 and 8, the corner polishing unit 110 further includes: a polishing head assembly 111 that grinds the corner portion by abutting the polishing tape 180 against the corner portion of the wafer W; and The polishing tape supply and recovery mechanism 112 that supplies the polishing tape 180 to the head assembly 111 is provided. The polishing head assembly 111 is disposed inside the polishing chamber 22, and the polishing tape supply and recovery mechanism 112 is disposed outside the polishing chamber 22.

Although the widths of the grinding belt 180 provided in the corner grinding unit 110 and the grinding belt 180 provided in the edge grinding unit 25 are different from each other, each grinding belt 180 has a structure shown in the third figure.

The polishing tape supply and recovery mechanism 112 includes a feeding reel 124 for supplying the polishing tape 180 to the polishing head assembly 111, and a retrieval reel 125 for the polishing tape 180 used for recovering the polished wafer W. Motors 129 and 129 are respectively connected to the supply reel 124 and the recovery reel 125 (only the motor 129 connected to the supply reel 124 is shown in the seventh figure). Each of the motors 129 and 129 applies a specified torque to the supply reel 124 and the recovery reel 125, and enables the polishing belt 180 Apply the specified tension.

The polishing head assembly 111 includes a polishing head 131 for abutting the polishing tape 180 on the peripheral edge portion of the wafer W. The polishing tape 180 is supplied to the polishing head 131 so that the polishing surface of the polishing tape 180 faces the wafer W. The polishing tape 180 is supplied from the supply reel 124 to the polishing head 131 through the opening portion 20b provided in the partition wall 20, and the used polishing tape 180 is recovered to the collection reel 125 through the opening portion 20b.

The polishing head 131 is fixed to one end of a support arm 135, and the support arm 135 is configured to rotate freely around a rotation axis Ct parallel to the tangential direction of the wafer W. The other end of the arm 135 is connected to the motor 138 via pulleys p3 and p4 and a belt b2. By rotating the motor 138 clockwise and counterclockwise by a predetermined degree of angle, the arm 135 is rotated around the axis Ct by a predetermined degree of angle. In this embodiment, the motor 138, the arm 135, the pulleys p3, p4, and the belt b2 constitute a tilting mechanism that tilts the polishing head 131 to the surface of the wafer W.

The tilt mechanism is mounted on the mobile stage 140. The moving stage 140 is movably connected to the base plate 21 via a linear guide 141. The linear guide 141 extends linearly along the radial direction of the wafer W held by the wafer holding portion 3, and the moving stage 140 can linearly move in the radial direction of the wafer W. A connecting plate 143 penetrating the base plate 21 is mounted on the mobile stage 140, and a linear actuator 145 is connected to the connecting plate 143 via a joint 146. The linear actuator 145 is directly or indirectly fixed to the base plate 21.

The linear actuator 145 may be an air cylinder or a combination of a positioning motor and a ball screw. The linear actuator 145 and the linear guide 141 constitute a moving mechanism that linearly moves the polishing head 131 in the radial direction of the wafer W. That is, the moving mechanism operates so that the polishing head 131 approaches or leaves the wafer W along the linear guide 141. The polishing tape supply and recovery mechanism 112 is fixed to the base plate 21.

The twenty-second figure is an enlarged view of the polishing head 131 shown in the eighth figure. As shown in FIG. 22, the polishing head 131 includes a pressing mechanism 150 that presses the polishing surface of the polishing tape 180 on the wafer W with a predetermined force. Further, the polishing head 131 includes a tape feeding mechanism 151 that feeds a polishing tape 180 from a supply reel 124 to a recovery reel 125. The polishing head 131 has a plurality of guide rollers 153A, 153B, 153C, 153D, 153E, 153F, and 153G. These guide rollers guide the polishing belt 180 so that the polishing belt 180 travels in a direction orthogonal to the tangential direction of the wafer W. .

The tape feeding mechanism 151 provided in the polishing head 131 includes a tape feeding roller 151a, a nip roller 151b, and a motor 151c that rotates the tape feeding roller 151a. A motor 151c is provided on the side of the polishing head 131, and a belt feed roller 151a is mounted on a rotation shaft of the motor 151c. The nip roller 151b is arranged adjacent to the tape feed roller 151a. The nip roller 151b is supported by a mechanism (not shown) so as to generate a force in a direction indicated by an arrow NF (direction toward the tape feeding roller 151a) in FIG. 22, and is configured to press the tape feeding roller 151a.

When the motor 151c rotates in the direction of the arrow indicated in FIG. 22, the belt feed roller 151a rotates, and the polishing tape 180 is fed from the supply reel 124 to the recovery reel 125 through the polishing head 131. The pinch roller 151b is configured to be rotatable around its own axis.

The pressing mechanism 150 includes a pressing member 155 disposed on the back surface side of the polishing tape 180, and an air cylinder 156 that moves the pressing member 155 toward the peripheral edge portion of the wafer W. The polishing load on the wafer W is adjusted by controlling the pressure of the gas supplied to the air cylinder 156.

Figure 23 is a front view of the pressing member 155 shown in Figure 22, Figure 24 is a side view of the pressing member 155 shown in Figure 23, and Figure 25 is the second Section 13 of the JJ line. As shown in FIGS. 23 to 25, the pressing member 155 has two protruding portions 161a and 161b formed on the front surface thereof. These protrusions 161a, 161b have rails The strips are arranged side by side. The protrusions 161a and 161b are bent along the circumferential direction of the wafer W. More specifically, the protrusions 161a and 161b have a circular arc shape having a curvature substantially the same as the curvature of the wafer W.

The two protrusions 161a and 161b are symmetrically arranged with respect to the rotation axis Ct. As shown in FIG. 23, when viewed from the front of the pressing member 155, the protrusions 161a and 161b are bent inside toward the rotation axis Ct. The polishing head 131 is provided so that the center line (that is, the rotation axis Ct) between the front ends of the protrusions 161a and 161b coincides with the center of the wafer W in the thickness direction. The protrusions 161a and 161b are arranged closer to the wafer W than the guide rollers 153D and 153E arranged in front of the polishing head 131, and the polishing tape 180 is supported from the back by the protrusions 161a and 161b. The protrusions 161a and 161b are formed of a resin such as PEEK (polydiether ketone).

A pressing pad (corner pad) 162 is disposed between the two protruding portions 161a and 161b. The pressing pad 162 is made of an elastic and independent foaming material such as silicone. The height of the pressing pad 162 is slightly lower than the height of the protrusions 161a and 161b. When the pressing member 155 is moved toward the wafer W by the air cylinder 156 in a state where the polishing head 131 is maintained horizontally, the pressing pad 162 presses the polishing tape 180 against the corner of the wafer W from the rear surface side.

When polishing the corners of the wafer W, as shown in FIG. 26, the tilt angle of the polishing head 131 is continuously changed by the tilt mechanism, and the polishing tape 180 is pressed against the wafer W by the pressing pad 162 Corners. During polishing, the polishing tape 180 is fed by a belt feeding mechanism 151 at a specified speed. In addition, the polishing head 131 can polish the upper edge portion of the wafer W (refer to symbols E1 in the first (a) and first (b) drawings). That is, as shown in FIG. 27, the polishing head 131 is tilted upward, and the polishing tape 180 is pressed against the upper edge portion of the wafer W by the protrusion portion 161a to polish the upper edge portion. As shown in FIG. 28, the polishing head 131 can also be inclined downward, and the polishing tape 180 can be pressed against the lower edge portion by the protruding portion 161b (refer to the first (a) and first (b) drawings). Symbol E2) Grind the lower edge.

The polishing devices shown in FIGS. 7 and 8 can polish the entire peripheral portion of the wafer W including the edge portion and the corner portion. For example, the corner polishing unit 110 may polish the corner portions of the wafer W, and thereafter, the edge grinding unit 25 may polish the edges of the wafer W. In this polishing apparatus, the upper edge portion of the wafer W can be polished by using one or both of the edge polishing unit 25 and the corner polishing unit 110. A plurality of corner grinding units 110 may be provided, but not shown.

The above-mentioned embodiment is described for the purpose that a person having ordinary knowledge in the technical field to which the present invention pertains can implement the present invention. Those skilled in the art can of course form various modifications of the above-mentioned embodiment, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be interpreted into the broadest scope according to the technical idea defined by the scope of patent application.

Claims (2)

A polishing method uses a polishing tape having a base material film composed of polyimide, a binder composed of polyimide, and abrasive particles held by the foregoing binder, which are characterized by: The SOI wafer having a structure formed by bonding two substrates with an adhesive is rotated, and the polishing tape is pressed against the peripheral edge portion of the SOI wafer with a light force, and the bonding is removed from the peripheral edge portion of the SOI wafer. Agent. For example, in the polishing method of the second item of the patent application, after removing the adhesive, the processing polishing tape is pressed against the peripheral edge portion of the SOI wafer, and the peripheral edge portion of the SOI wafer is processed and polished.