JP5436955B2 - Method for producing foam - Google Patents

Description

  The present invention relates to a method for producing a foam, and more particularly, production of a foam such as foamed polyurethane suitable for a workpiece holding material or a polishing pad for holding a workpiece to be processed such as polishing. Regarding the method.

  A foam, for example, polyurethane foam, is used as a backing material for holding a workpiece in polishing of the workpiece such as a semiconductor wafer or LCD glass.

  FIG. 3 is a diagram showing a polishing apparatus for polishing a workpiece such as a semiconductor wafer or LCD glass. A workpiece 10 to be polished is held on the upper surface plate 9 of the surface plate facing the upper and lower sides of the polishing apparatus, and a polishing pad 12 is attached to the lower surface plate 11, and the surface of the workpiece 10 The platen 9 and 11 are rotated relative to each other as indicated by arrows while supplying a polishing liquid containing abrasive grains between the platens 9 and 11 while being pressed against the polishing pad 12.

  The workpiece 10 has a backing material 13 as a workpiece holding material that holds the back surface thereof by suction, and a frame that surrounds the outer periphery of the workpiece 10 and prevents the workpiece 10 from being displaced on the backing material surface. And is held on the upper surface plate 9 using a template 14 (see, for example, Patent Document 1).

  The backing material 13 is generally formed by applying a urethane resin solution in which a urethane resin is dissolved in an organic solvent to a base material and wet coagulating it in an aqueous coagulation liquid to form a foam layer on the base material. It is obtained by buffing the surface of the foamed layer that becomes a holding surface for holding the workpiece 10 in some cases.

JP 09-32001 A

  As described above, the surface of the foam layer serves as a holding surface for holding the workpiece, and the size, shape, number, etc. of the bubbles (pores) in the foam layer are the warpage and undulation of the workpiece. The performance of the workpiece holding material such as the compression rate and the adsorption holding force for absorbing the water greatly affects the control of the bubble shape and the like.

  For this reason, conventionally, a surfactant is added to the urethane resin solution, but the resulting foam layer has a low foaming frequency, small bubbles are formed in multiple stages, and the compression rate is low. It was.

  By adding carbon black, which is a porous particle, to the urethane resin solution, the replacement of the solvent with water can be promoted to form large bubbles and the compression rate can be increased. However, there are the following problems. .

  That is, when the urethane resin solution layer applied to the base material is immersed in the coagulation liquid, there is a difference in the penetration of water from the coagulation liquid between the surface side and the base material side. Large bubbles on the side, so-called teardrop-shaped bubbles are formed, but by adding carbon black, the substrate side becomes teardrop-shaped bubbles that grow excessively large, and the substrate coated with the urethane resin solution is solidified. Because it is allowed to enter the liquid in an inclined state, while a large bubble is formed, it is formed in a state where a teardrop-shaped bubble is inclined under the influence of gravity or the like. There is a problem of end.

  The present invention has been made in view of the above-described problems, and an object thereof is to enable formation of relatively large bubbles without inclining by wet foaming.

  In order to achieve the above object, the present invention is configured as follows.

The method for producing a foam of the present invention is a method for producing a foam in which a resin solution is applied to the surface of a base material and wet-coagulated to form a foam layer on the surface of the base material. It contains carbon black and 0.01 wt% to 0.15 wt% azo pigment , the resin solution is a solution in which a urethane resin is dissolved in a solvent, and the foam is processed A workpiece holding material for holding an object .

  Azo pigments include C.I. I. Pigment Red 2, 5, 9, 12, 14, 17, 22, 23, 48, 57, 60, 68, 112, 114, 127, 144, 146, 147, 150, 151, 170, 175, 184, 185, 186, 187, 188, 210, 213, 221, 242, 247, 256, 258, 49: 1, 50: 1, 53: 1, 57: 1, 58: 4, 58: 2, 60: 1, C.I. I. Pigment Orange 13, 16, 43, 188, C.I. I. Pigment Yellow 1, 3, 6, 12, 13, 14, 17, 55, 81, 83, 95, 97, 128, 139, 142, 152, 167, 180, C.I. I. Pigment Blue 25, C.I. I. Pigment Violet 23, C.I. I. It is preferably at least one selected from Pigment Brown 23.

  In addition to the above, the azo pigments include Lakelet C, 4R, Carmine 6B (Red 57), Brilliant Carmine 6B, Carmine FB (Red 5), Carmine BS (Red 23), Carmine 3B (Red 60), and Carmine FBB (Red 146). , Monoazo red, disazo red, polyazo red, watch young red, naphthol red, chromophthal red, chromophthal scarlet RN, permanent red FRLL (Red 9), permanent red 2B, permanent red FGR (Red 112), permanent orange HL, permanent orange G (Orange 13), monoazo yellow, disazo yellow, polyazo yellow, first yellow, nickel azo yellow, benzimidazolone yellow, Lomophthal Yellow 3G, Naphthol Carbamide Yellow (Red 170), Hansa Yellow G (Yellow 1), Hansa Yellow 3G (Yellow 6), Hansa Yellow 10G (Yellow 3), Bencidin Yellow 5G (Yellow 14), p-phenylazophenol, β- Examples thereof include naphthol monoazo pigments, naphthol AS monoazo pigments, acetoacetate arylide disazo pigments, pyrazolone monoazo pigments, and 2-hydroxy-3-naphthoanilides.

  According to the present invention, by adding carbon black to the resin solution and adding 0.01 wt% to 0.15 wt% of an azo pigment, the effect of introducing water is promoted during wet foaming, Since relatively large bubbles can be formed quickly, it is possible to prevent the bubbles from being inclined and formed under the influence of gravity or the like when forming the bubbles.

  According to the present invention, since carbon black is added to the resin solution and a predetermined amount of azo pigment is added, the effect of introducing water is promoted during wet foaming, and relatively large bubbles are inclined. And a foam having a high compression rate can be obtained.

It is a schematic sectional drawing of the workpiece holding material obtained by the manufacturing method which concerns on one Embodiment of this invention. It is a scanning electron microscope (SEM) photograph of the section of comparative examples 1 and 2 and examples 1 and 2. It is a schematic block diagram of a grinding | polishing apparatus.

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

  In this embodiment, description will be made by applying to the above-described method for manufacturing a workpiece holding material that holds a workpiece such as a semiconductor wafer to be polished as a foam.

  FIG. 1 is a schematic cross-sectional view of a workpiece holding material 1 obtained by the manufacturing method according to the embodiment.

  The workpiece holding material 1 includes a base material 2 and a foam layer 3 formed on the base material 2 by wet foaming.

  In the foamed layer 3, a large number of teardrop-shaped bubbles 4 that are larger on the substrate 2 side than on the surface side are formed, and a large number of minute bubbles 5 are formed on the surface side.

  In the foam manufacturing method of this embodiment, a later-described urethane resin solution is applied onto a base material 2 such as a PET (polyethylene terephthalate) film, and wet coagulated in an aqueous coagulating liquid. The foamed layer 3 is formed, then washed in warm water to remove the solvent, dried, and buffed on the surface of the foamed layer 3 as necessary.

  The substrate 2 is preferably a resin film such as PET (polyethylene terephthalate), but may be one obtained by impregnating a nonwoven fabric or woven fabric with a resin solution such as a urethane resin solution and wet coagulating it.

  The urethane resin solution for forming the foam layer 3 is obtained by dissolving a urethane resin and an additive in an organic solvent such as dimethylformamide (DMF). In order to adjust the shape, carbon black is added and an azo pigment is added so as to have a concentration of 0.01 wt% to 0.15 wt%.

  If the amount of the azo pigment added is less than 0.01% by weight, the shape of the bubbles cannot be adjusted sufficiently. Conversely, if it exceeds 0.15% by weight, the strength of the resin constituting the foamed layer This is not preferable.

  As the urethane resin, polyester resins, polyether resins, polycarbonate resins and the like can be used, and different types of urethane resins may be blended.

  As the organic solvent for dissolving the urethane resin, in addition to the above-mentioned dimethylformamide, for example, a solvent such as dimethylsulfoxide, tetrahydrofuran, dimethylacetamide or the like can be used.

  As carbon black, various carbon blacks such as channel black and furnace black can be used.

  Examples of the azo pigment include C.I. I. Pigment Red 2, 5, 9, 12, 14, 17, 22, 23, 48, 57, 60, 68, 112, 114, 127, 144, 146, 147, 150, 151, 170, 175, 184, 185, 186, 187, 188, 210, 213, 221, 242, 247, 256, 258, 49: 1, 50: 1, 53: 1, 57: 1, 58: 4, 58: 2, 60: 1, C.I. I. Pigment Orange 13, 16, 43, 188, C.I. I. Pigment Yellow 1, 3, 6, 12, 13, 14, 17, 55, 81, 83, 95, 97, 128, 139, 142, 152, 167, 180, C.I. I. Pigment Blue 25, C.I. I. Pigment Violet 23, C.I. I. Pigment Brown 23, Lakelet C, 4R, Carmine 6B (Red 57), Brilliant Carmine 6B, Carmine FB (Red 5), Carmine BS (Red 23), Carmine 3B (Red 60), Carmine FBB (Red 146), Monoazo Red, Disazo Red, Polyazo Red , Watch Young Red, Naphthol Red, Chromophthal Red, Chromophthal Scarlet RN, Permanent Red FRLL (Red 9), Permanent Red 2B, Permanent Red FGR (Red 112), Permanent Orange HL, Permanent Orange G (Orange 13), Monoazo Yellow, Disazo Yellow, polyazo yellow, first yellow, nickel azo yellow, benzimidazolone yellow, chromo Phthal Yellow 3G, Naphthol Carbamide Yellow (Red170), Hansa Yellow G (Yellow1), Hansa Yellow 3G (Yellow6), Hansa Yellow 10G (Yellow3), Bencidin Yellow 5G (Yellow14), p-phenylazophenol, β-naphthol It is possible to use at least one selected from a series monoazo pigment, a naphthol AS monoazo pigment, an acetoacetyl arylide disazo pigment, a pyrazolone monoazo pigment, and 2-hydroxy-3-naphthoanilides.

  Among these azo pigments, C.I. I. Pigment Red 2, 5, 9, 12, 14, 17, 22, 23, 48, 57, 60, 68, 112, 114, 127, 144, 146, 147, 150, 151, 170, 175, 184, 185, 186, 187, 188, 210, 213, 221, 242, 247, 256, 258, 49: 1, 50: 1, 53: 1, 57: 1, 58: 4, 58: 2, 60: 1, C.I. I. Pigment Orange 13, 16, 43, 188, C.I. I. Pigment Yellow 1, 3, 6, 12, 13, 14, 17, 55, 81, 83, 95, 97, 128, 139, 142, 152, 167, 180, C.I. I. Pigment Blue 25, C.I. I. Pigment Violet 23, C.I. I. Pigment Brown 23 is preferable, and C.I. I. Pigment Red 2, 5, 9, 12, 14, 17, 22, 23, 48, 57, 60, 68, 112, 114, 127, 144, 146, 147, 150, 151, 170, 175, 184, 185, 186, 187, 188, 210, 213, 221, 242, 247, 256, 258, 49: 1, 50: 1, 53: 1, 57: 1, 58: 4, 58: 2, 60: 1, C.I. I. Pigment Blue 25 is preferred.

  The azo pigment is preferably porous. By being porous, the effect of introducing water from the coagulation liquid can be further enhanced.

  In the foam production method of this embodiment, first, urethane resin, carbon black, azo pigment, and the like are dissolved in an organic solvent such as dimethylformamide (DMF) and mixed, defoamed, filtered, and then urethane. A resin solution is prepared.

  This urethane resin solution is applied onto a substrate such as a PET film, immersed in a coagulation liquid containing water as a main component, wet coagulated to form a foamed layer, washed to remove the solvent, and then dried. Thus, the workpiece holding material 1 shown in FIG. 1 is obtained.

  In this embodiment, since carbon black is added to the urethane resin solution and 0.01% to 0.15% by weight of an azo pigment is added, the substrate on which the urethane resin solution is applied. Is immersed in the coagulation liquid, the penetration of water from the coagulation liquid into the urethane resin solution layer and the replacement of the solvent with water are promoted, so that the substrate side does not become excessively large and is inclined. It is possible to form neat teardrop-shaped bubbles without doing so.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

  A workpiece holding material that has been wet-coagulated by applying a urethane resin solution to which a pigment and carbon black have not been added to a base material is Comparative Example 1. A urethane resin solution to which carbon black has been added is applied to a base material and wet-coagulated. The workpiece holding material thus prepared was Comparative Example 2, and the workpiece holding material obtained by wet coagulation by applying a urethane resin solution to which Pigment Blue 25, which is carbon black and an azo pigment, was added, to the base material, Example 1, Carbon A workpiece holding material obtained by applying a urethane resin solution to which Pigment Red 127, which is a black pigment and an azo pigment, was added to a base material and wet-coagulating the substrate was taken as Example 2.

  A DMF paste having a concentration of 30% by weight and a specific gravity of 1.29 was used as the carbon black of Comparative Example 2 and Examples 1 and 2, and as Pigment Blue 25 of Example 1, the concentration was 30% by weight and the specific gravity was 1.05. A DMF paste having a concentration of 30 wt% and a specific gravity of 1.14 was used as Pigment Red 127 of Example 2. Moreover, the specific gravity of the urethane resin as the main material was 1.04, and the specific gravity of DMF was 0.944.

  The addition amount of carbon black in the urethane resin solutions of Comparative Example 2 and Examples 1 and 2 was 2.50 wt%, and the addition amount of Pigment Blue 25 in the urethane resin solution of Example 1 was 0.05 wt%. The amount of Pigment Red 127 added to the urethane resin solution of Example 2 was 0.15% by weight.

  The cross sections of the workpiece holding materials obtained in Comparative Examples 1 and 2 and Examples 1 and 2 were observed with a scanning electron microscope (SEM), and the compression ratio was measured. The compression rate was measured by measuring the thickness T1 when an initial load was applied to each sample of Comparative Examples 1 and 2 and Examples 1 and 2, and then measuring the thickness T2 when a second load was applied for 1 minute. And calculated by the following equation.

Compression rate (%) = [(T1-T2) / T1] × 100
2A, 2B, 2C and 2D show SEM photographs of Comparative Examples 1 and 2 and Examples 1 and 2 at a magnification of 50 times. In Comparative Example 2 in FIG. 2B, the application thickness of the urethane resin solution is slightly thicker than the others.

  Table 1 below shows the compression ratios of Comparative Examples 1 and 2 and Examples 1 and 2.

  As shown in FIG. 2 (a), Comparative Example 1, which is a workpiece holding material manufactured using a urethane resin solution to which no pigment and carbon black are added, has small teardrop-shaped bubbles in the foam layer. However, it was formed in multiple stages, and the compression rate was as low as 14.9%.

  As shown in FIG. 2B, Comparative Example 2, which is a workpiece holding material manufactured using a urethane resin solution to which only carbon black has been added without adding a pigment, has a comparative example in the foam layer. Compared to 1, a teardrop-shaped bubble is formed, and the compression rate is as high as 21.3%.

  However, in the foamed layer of Comparative Example 2, the base material side (lower side) is excessively larger in the form of teardrop-shaped bubbles than the surface side (upper side), and these teardrop-shaped bubbles are inclined. It is formed in a state, that is, skewed, and therefore, there is a problem that local compressive deformation is likely to occur and the life as a holding material is shortened.

  On the other hand, as shown in FIG. 2 (c), an example of a workpiece holding material manufactured using a urethane resin solution added with carbon black and Pigment Blue 25 has a teardrop-like shape on the foam layer. Are formed on the base material side without being excessively large compared to the surface side, and without being inclined, and the compression rate is as high as 29.3%.

  In addition, Example 2 which is a workpiece holding material manufactured using a urethane resin solution to which carbon black and Pigment Red 127 are added has, as shown in FIG. However, the base material side is not excessively larger than the front surface side, and is formed without being inclined, and further, a communication hole communicating with teardrop-shaped bubbles is also formed. For this reason, the compression rate is the highest at 29.5%.

  The compressibility of the workpiece holding material is preferably 20% or more and 50% or less in order to absorb warpage or swell of the workpiece.

  In a workpiece holding material in which a carbon resin is added and a urethane resin solution to which a predetermined amount of Pigment Blue 25 or Pigment Red 127, which is an azo pigment, is added is applied to a base material and wet solidified, relatively large tear Drop-like bubbles are formed without tilting, and a sufficient compressibility can be obtained, whereby the warpage and swell of the workpiece can be absorbed, and the flatness of the workpiece can be improved. Can do.

  The present invention is useful for polishing semiconductor wafers and precision glass substrates.

DESCRIPTION OF SYMBOLS 1 Workpiece holding material 2 Base material 3 Foamed layer 4,5 Bubble

Claims (1)

A method for producing a foam by applying a resin solution to a surface of a base material and wet-coagulating to form a foam layer on the surface of the base material,
The resin solution contains carbon black and 0.01 wt% to 0.15 wt% of an azo pigment ,
The resin solution is a solution in which a urethane resin is dissolved in a solvent,
A method for producing a foam , wherein the foam is a workpiece holding material for holding a workpiece .