JP2011156634A - Workpiece holding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve strength of a workpiece holding member for holding a workpiece to make the member hard to get damaged. <P>SOLUTION: A resin solution is applied on a base material 1 and wet-solidified to form a foaming layer 2. The base material 1 on the rear of the foaming layer 2 is exfoliated. The foaming layer 2 is sandwiched between smooth members 3, and heat and pressure are applied. Strength is improved by crushing bubbles or the like on front and rear faces 2a-1 and 2b-1 of the foaming layer 2 to make dense. A density distribution of the foaming layer 2 exhibits a gradually inclined distribution as it is smaller at the center than on the front and rear faces in a thickness direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a workpiece holding material that holds a workpiece to be processed such as polishing.

  Polishing of a workpiece such as a semiconductor wafer or LCD glass is performed as follows, for example. That is, as shown in FIG. 18, the 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 the polishing pad 12 is mounted on the lower surface plate 11. By pasting the surface of the workpiece 10 against the polishing pad 12 and supplying a polishing liquid containing abrasive grains between the two surface plates, the surface plates 9 and 11 are relatively rotated as indicated by arrows. Done.

  Conventionally, the workpiece 10 is fixed to the upper surface plate 9 and surrounds the backing material 13 as a workpiece holding material that sucks and holds the back surface of the workpiece 10 and the outer periphery of the workpiece 10. 10 is held on the upper surface plate 9 using a frame-shaped template 14 that prevents the position of the back 10 from shifting on the surface of the backing material 13 (see, for example, Patent Document 1).

  As the backing material 13, for example, a DMF (dimethylformamide) solution layer of urethane resin applied to a base material is wet-coagulated in water, washed in warm water, and dried with hot air. For the purpose of forming the foam layer 2 on the base material 1 as shown in Fig. 19 and aligning it to the required thickness, the surface 2a of the foam layer 2 is buffed as shown in Fig. 19 (b). (See, for example, Patent Document 2).

  The surface 2a-2 of the foamed layer 2 after the buffing serves as a holding surface for adsorbing and holding the workpiece. However, the buffing does not provide a sufficiently smooth surface. Adsorption holding power was insufficient.

  For this reason, as shown in FIG. 20A, without buffing the surface 2a of the foamed layer 2 formed on the base material 1, as shown in FIG. 20 is peeled off, the surface 2a is pressed against the flat pressure roller 7 as shown in FIG. 20 (c), and the back surface 2b side of the foam layer 2 is buffed as shown in FIG. 20 (d). As shown in FIG. 20 (e), there is a backing material bonded again to the double-sided tape 8 or the like (see, for example, Patent Document 3).

JP 09-32001 A Japanese Patent No. 3187769 JP 2006-62058 A

  In such a backing material, since a large number of bubbles are opened on the surface, the surface is cracked and easily broken, and the workpiece holding material may be damaged when the workpiece is detached.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a workpiece holding material with increased strength.

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

  The workpiece holding material of the present invention is a workpiece holding material provided with a foam layer, and the surface of the foam layer is a holding surface for holding the workpiece, and the foam layer has a density thereof. However, it has a density distribution inclined so as to be smaller on the center side than on the front and back surfaces in the thickness direction.

  According to the present invention, the foam layer has a density distribution that is inclined so that the density is smaller on the center side than on the front and back surfaces in the thickness direction. Therefore, the front and back surfaces are dense, dense, and strong. Since the density becomes higher and the density gradually decreases toward the center side, there is no sudden change in density inside, and it is difficult to break.

  Further, the workpiece holding material of the present invention is a workpiece holding material provided with a foam layer, and the surface of the foam layer is a holding surface for holding the workpiece, and the foam layer includes: It has a porosity distribution that is inclined so that the porosity, which is the ratio of the voids per unit area in the longitudinal section, is larger on the center side than on the front and back surfaces in the thickness direction.

  According to the present invention, the foam layer has a porosity distribution that is inclined so that the porosity is larger on the center side than on the front and back surfaces in the thickness direction. In other words, the foam layer has a density of Since the density distribution is inclined so that it is smaller on the center side than on the front and back surfaces in the thickness direction, the front and back surfaces are large, dense and high in strength, and the density is increased toward the center portion. Since it becomes gradually smaller, there is no sudden change in density inside, and it becomes difficult to break.

  In a preferred embodiment, the foam layer is formed by applying a resin solution onto a substrate and wet coagulating the resin layer, and the resin solution is preferably a urethane resin solution.

  According to the present invention, the foam layer has a density distribution that is inclined so that the density is smaller on the center side than on the front and back surfaces in the thickness direction, so the front and back surfaces are dense, dense and strong. Since the density gradually decreases toward the center side, there is no sudden change in density inside, and it is difficult to break. Thereby, it is possible to prevent the workpiece holding material from being damaged when the workpiece is detached.

It is a figure which shows the manufacturing process of the workpiece holding material which concerns on embodiment of this invention. It is a figure which shows the heating-pressing process by a heat roll. It is a scanning electron micrograph of the surface side 500 times of a comparative example. It is a scanning electron micrograph of the surface side 500 times of an Example. It is the scanning electron micrograph of the surface side 2000 times of a comparative example. It is the scanning electron micrograph of the surface side 2000 times of an Example. It is a scanning electron micrograph of the back surface 1000 times of a comparative example. It is a scanning electron micrograph of the back surface 1000 times of an Example. It is a figure which shows distribution of the porosity of an Example. It is a figure which shows distribution of the porosity of a comparative example. It is a figure which shows the average bubble diameter of an Example. It is a figure which shows the average bubble diameter of a comparative example. It is a figure which shows the waviness curve of the surface of a comparative example. It is a figure which shows the waviness curve of the surface of an Example. It is a figure which shows the waviness curve of the surface of another comparative example. It is a figure which shows the waviness curve of the surface of another Example. It is a figure which shows the manufacturing process of the workpiece holding material which concerns on other embodiment of this invention. It is a schematic block diagram of a grinding | polishing apparatus. It is a figure which shows the manufacturing process of a prior art example. It is a figure which shows the manufacturing process of another prior art example.

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

  FIG. 1 is a diagram illustrating a method for manufacturing a workpiece holding material according to an embodiment of the present invention.

  The workpiece holding material of this embodiment is manufactured as follows. First, a DMF (dimethylformamide) solution of a urethane resin is applied onto a base material 1 such as a PET film, and is wet-coagulated to form teardrops on the base material 1 as shown in FIG. A porous foamed layer 2 having a large number of bubbles, such as bubbles, is formed. The foam layer 2 is peeled from the substrate 1 as shown in FIG.

  Next, as shown in FIG. 1C, the front and back surfaces 2a and 2b of the foam layer 2 are overlapped with a resin film 3 such as a PET film as a smooth member, and passed between two heat rolls. As shown in FIG. 1 (d), they are heated and pressurized to be integrated.

  Thereafter, the resin film 3 on the front and back surfaces is peeled off as shown in FIG. 1 (e), the double-sided tape 4 is attached to the back surface 2b-1, and the surface 2a-1 is processed as shown in FIG. 1 (f). It is possible to obtain a workpiece holding material according to the present invention that has a holding surface.

  In the step of forming the foamed layer 2 by the wet coagulation method, the foamed layer contracts slightly during the wet foaming, whereas the base material 1 made of PET film or the like does not contract, so that the foamed layer 2 is distorted. This distortion appears as a streak on the surface of the foamed layer 2 that holds the object to be polished. For example, in low-pressure polishing of 2 psi or less, the streak cannot be crushed, which affects the polished surface. However, in this embodiment, since the base material 1 is peeled from the foam layer 2, the strain of the foam layer 2 is released, thereby causing the above-described problems caused by the strain. It does not occur.

  As the urethane resin for forming the foamed layer 2, a urethane resin such as polyester, polyether, or polycarbonate can be used, and different types of urethane resins may be blended.

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

  In the workpiece holding material of this embodiment, the smooth resin film 3 is sandwiched between the front and back surfaces 2a, 2b of the foam layer 2 peeled off from the base material 1, and heated and pressurized with a heat roll. The front surface 2a-1 side and the back surface 2b-1 side have fewer voids and a higher density than the central part in the thickness direction, and the density decreases as going to the central part side in the thickness direction. The density distribution is inclined as follows.

  Thus, the foamed layer 2 has a density distribution that is inclined so that the density gradually decreases on the center side rather than on the front and back surfaces in the thickness direction, that is, the density rapidly changes in the thickness direction. Because it is not, it will be difficult to break.

  In particular, on the front and back sides, since bubbles and the like are crushed and dense as described above, the strength is high, and it becomes more difficult to break, and the workpiece holding material breaks when the workpiece is detached. Can be prevented.

  Further, since the front and back sides are dense with few voids, the penetration of the polishing liquid is prevented by the dense front and back surfaces during polishing. Thereby, the flatness of the workpiece can be deteriorated, and the foam layer 2 can be prevented from being peeled off from the double-sided tape 4.

  In addition, since the resin film 3 is peeled after being heated and pressurized with the smooth resin film 3 sandwiched therebetween, the front and back surfaces 2a-1 and 2b-1 of the foamed layer 2 become smooth, whereby the workpiece holding material The adsorption holding force of the surface 2a-1 of the foam layer 2 that becomes the holding surface for holding the surface is improved.

  Furthermore, since it is not necessary to buff both the front surface and the back surface of the foamed layer, the buff powder does not remain in the pores of the opened bubbles (pores).

  The foam layer 2 was evaluated as follows. That is, as shown in FIG. 1 (c), the foamed layer 2 having a thickness of 1.2 mm by overlapping a smooth resin film 3 on both the front and back surfaces 2a and 2b has a gap of 1.0 mm as shown in FIG. Then, it passes between the upper and lower heat rolls 5 and 6 at 150 ° C. at 1.0 m / min, and then the surface side from which the resin film 3 is peeled off, that is, the foam layer 2 of the embodiment shown in FIG. The surface 2a-1 side is observed with a scanning electron microscope (SEM), and the back surface from which the resin film 3 is peeled, that is, the back surface 2b-1 shown in FIG. 1 (e) is scanned with a scanning electron microscope (SEM). ).

  On the other hand, as a comparative example, the surface 2a and the back surface 2b of the foamed layer 2 peeled from the base material 1 shown in FIG. Similarly, the front surface 2a and the back surface 2b of the foam layer 2 were observed with a scanning electron microscope (SEM).

  Furthermore, in order to evaluate the density distribution of the foam layers of Examples and Comparative Examples, the porosity was measured as follows based on SEM photographs of the cross sections of the foam layers.

  This porosity was calculated using image processing software (WinROOF, manufactured by Mitani Corp.) in the SEM photograph of the cross section of the foamed layer, the ratio (%) occupied by the voids per unit area. That is, for each 100 μm thickness from the surface, the measurement was performed with the WinROOF measurement conditions of contrast: 100, brightness: 50, and threshold: 0-200 for an area of 100 μm square.

  Moreover, about the Example and the comparative example, the bubble per unit area was measured similarly, the average value was computed, and the average bubble diameter was calculated | required.

  3 and 4 are SEM photographs of the edge portion of the surface of the comparative example and the example with a magnification of 500 times, and FIGS. 5 and 6 are SEM images of the edge portion of the surface of the comparative example and the example with a magnification of 2000 times. In these drawings, the edge portion of the surface is an SEM image so that the surface and side surfaces can be observed.

  7 and 8 are SEM photographs of the back surface of the comparative example and the example with a magnification of 1000 times.

  After the resin film 3 is overlapped and the heat rolls 5 and 6 are passed, the surface side of the foamed layer of the example shown in FIGS. 4 and 6 where the resin film 3 is peeled off is the comparative example of FIGS. 3 and 5. Compared to the surface side of the foam layer, small bubbles (pores) are crushed, the voids are few and dense, and the surface is smooth.

  In addition, small bubbles (pores) are crushed on the back surface of the foamed layer in the embodiment of FIG. 8 and are denser than the comparative example of FIG.

  The measurement result of the above-mentioned porosity of an Example and a comparative example is shown in FIG. 9 and FIG.

  In these figures, the horizontal axis corresponds to the distance (μm) from the surface, and the vertical axis corresponds to the porosity (%).

  In the example of FIG. 9, the porosity of the foam layer is small on the front side, increases as it goes to the center in the thickness direction, and decreases as it goes beyond the center and goes to the back side. That is, it has a distribution in which the porosity of the foamed layer is inclined so as to be larger on the center side than on the front and back surfaces in the thickness direction. In other words, using the density, the density of the foamed layer has a distribution that is inclined so as to be smaller on the center side than on the front and back surfaces in the thickness direction.

  On the other hand, in the comparative example of FIG. 10, the porosity of the foam layer is small on the front side and increases as it goes to the center in the thickness direction. It is getting bigger.

  In the example of FIG. 9, the porosity gradually increases from the front and back surfaces to the central portion in the thickness direction, whereas in the comparative example of FIG. The porosity is also large on the back side, and the change in the porosity is abrupt compared to the examples.

 As described above, the embodiment has a density distribution that is inclined so that the central portion side is gradually smaller than the front and back surfaces in the thickness direction. Therefore, in the conventional example in which the density rapidly changes inside the thickness direction. In comparison, it is less likely to break, and in particular, in the examples, the front and back surfaces are dense and the strength is high.

  FIG. 11 and FIG. 12 show the measurement results of the average bubble diameters of the examples and comparative examples.

  In the example of FIG. 11, the average bubble diameter is small on the front and back sides and the front and back sides are dense, whereas in the comparative example of FIG. 12, the average bubble diameter increases from the front side to the back side. It is getting bigger.

  As described above, in the examples, the front side and the back side are both denser with less voids than the front side and the back side of the comparative example. It will be blocked by the side and back side. Accordingly, it is possible to suppress the polishing liquid from penetrating and deteriorating the flatness of the workpiece, or to prevent the foamed layer from peeling off from the double-sided tape. Furthermore, the strength is increased by the front surface layer and the back surface layer in which the openings are crushed, and the density is distributed so that the central side is gradually smaller than the front and back surfaces in the thickness direction. Since there is no portion where the abrupt change occurs, it becomes difficult to break, and it is possible to prevent the workpiece holding material from being damaged when the workpiece is detached.

  Furthermore, since the surface of the foam layer serving as a holding surface for holding the workpiece holding material is a smooth surface, the suction holding force for holding the workpiece holding material is improved.

In order to evaluate the smoothness of the surface of this foam layer, the surface waviness of the above examples and comparative examples was measured.
The measurement conditions are as shown in Table 1 below.

  FIG. 13 shows a filtered undulation curve of the comparative example, and FIG. 14 shows a filtered undulation curve of the example.

  In addition, Wa (arithmetic mean waviness), Wcmax (maximum value of the waviness curve element height), and Wfpd (straightness about a certain reference length in the filtered centerline waviness curve) of the example and the comparative example, Table 2 shows the measurement results of the maximum value within the range of the evaluation length.

  As shown in FIGS. 13 and 14 and Table 2, it can be seen that the surface of the foamed layer of the example has reduced swell compared to the comparative example.

  As shown in Table 2, the maximum height Wcmax of the waviness curve element of the example is 2.18 μm and within 3 μm, whereas the maximum height of the waviness curve element of the comparative example is The value Wcmax is 5.93 μm.

  Therefore, according to the workpiece holding material of the embodiment, the flatness of the workpiece can be improved.

  Furthermore, the compressibility of the workpiece holding material in which the double-sided tape was attached to the back surface of the foamed layer of the example was measured.

  The compression rate was calculated by the following equation by measuring the thickness T1 when an initial load was applied to the sample for 1 minute, and then measuring the thickness T2 when the second load was applied for 1 minute.

Compression rate (%) = [(T1-T2) / T1] × 100
The compression ratio of the workpiece holding material of the example was 35.1%.

  This compression rate is preferably 20% to 60%.

  Further, different examples and comparative examples were manufactured using low modulus foamed polyurethane resins having different compositions from the above examples and comparative examples, and surface waviness was measured in the same manner.

  FIG. 15 shows a filtered undulation curve of the comparative example, and FIG. 16 shows a filtered undulation curve of the example.

  Table 3 shows the measurement results of Wa, Wcmax, and Wfpd of the example and the comparative example.

  As shown in FIGS. 15 and 16 and Table 3, it can be seen that the swell is reduced even with polyurethane foam resins having different compositions.

  As shown in Table 3, the maximum value Wcmax of the waviness curve element of the example is 2.06 μm and within 3 μm, whereas the maximum height of the waviness curve element of the comparative example is The value Wcmax is 3.33 μm.

  FIG. 17 is a diagram illustrating a method for manufacturing a workpiece holding material according to another embodiment of the present invention, and the same reference numerals are given to the portions corresponding to FIG. 1 described above.

  In the workpiece holding material of this embodiment, first, a DMF (dimethylformamide) solution of a urethane resin is applied onto a substrate 1 such as a PET film, and then as shown in FIG. In addition, a porous foam layer 2 having a large number of bubbles such as teardrop-shaped bubbles is formed on the substrate 1.

  Next, as shown in FIG. 17 (b), the base material 1 on which the foam layer 2 is formed is sandwiched between resin films 3 and passed between two heat rolls, as shown in FIG. 17 (c). As shown in FIG. Thereafter, the resin films 3 on the front and back surfaces are peeled as shown in FIG. 17D to obtain a workpiece holding material having the surface 2a-1 as the holding surface of the workpiece.

In the workpiece holding material of this embodiment, since the resin film 3 is superimposed on the surface of the foam layer 2 and heated and pressurized by a heat roll, bubbles and the like are crushed on the surface 2a-1 side of the foam layer 2. As a result, a dense layer 2a-1a with few voids is formed, and the surface 2a-1 is smooth.
Other configurations are the same as those of the above-described embodiment.

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

DESCRIPTION OF SYMBOLS 1 Base material 2 Foam layer 3 Resin film 4 Double-sided tape 5,6 Heat roll

Claims (4)

A workpiece holding material provided with a foam layer, wherein the surface of the foam layer is a holding surface for holding the workpiece,
The workpiece holding material characterized in that the foam layer has a density distribution inclined such that the density is smaller on the center side than on the front and back sides in the thickness direction. A workpiece holding material provided with a foam layer, wherein the surface of the foam layer is a holding surface for holding the workpiece,
The foam layer has a porosity distribution that is inclined so that a porosity, which is a ratio of a void portion per unit area in a longitudinal section thereof, is larger on the center side than on the front and back surfaces in the thickness direction. Workpiece holding material.   The workpiece holding material according to claim 1, wherein the foamed layer is formed by applying a resin solution on a base material and wet coagulating the resin solution.   The workpiece holding material according to claim 3, wherein the resin solution is a urethane resin solution.