JP2006303049A - Supporting plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic supporting plate which can support an extremely thin wafer during manufacturing and reduce breakdown for use to obtain the wafer having a smooth polishing surface, and moreover assure higher tranmsparency, rigidity, and a small line expansion coefficient. <P>SOLUTION: The supporting plate is formed by molding a molding material which is constituted of a synthetic resin of 15 to 95 weight% and a fiber reinforced material of 5 to 85 wt.% having a substantially identical refractive index and/or the Abbe's number and assures an ultraviolet ray transmissivity of 30% or higher. Here, the substantially identical refractive index means that the refractive index is matched in a range for verifying a light beam transmissivity of 50% or higher and an ultraviolet ray transmissivity of 50% or higher. It is preferable that refractive indices are matched in a range of ±0.015. The substantially identical Abbe's number means that the Abbe's number is matched in a range for verifying the light beam transmissivity of 50% or higher and the ulratraviolet ray transmissivity of 50% or higher. It is preferable that the Abbe's numbers are matched in a range of ±10. The ultraviolet ray means light in a wavelength region of 320 to 370 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plastic support plate used to support a plate-like object such as a silicon wafer when it is polished.

  A semiconductor integrated circuit (hereinafter referred to as an IC chip) is usually formed by slicing a high-purity silicon single crystal or the like to form a silicon wafer, and then forming a predetermined circuit pattern on the wafer surface using a photoresist. It is manufactured by polishing the back surface with a polishing machine to reduce the thickness of the wafer, and finally dicing the wafer into chips.

  In recent years, the use of IC chips has expanded, and an extremely thin silicon wafer (hereinafter referred to as an ultrathin wafer) having a thickness of about 50 μm has been required. However, the ultra-thin wafer is inferior in handling because it has a large warp and is easily broken by impact compared to the conventional one with a thickness of about 100 to 600 μm, and it breaks when trying to process like a conventional silicon wafer There is.

  In addition, an ultra-thin wafer is easily damaged by an impact and has a high risk of breakage in a polishing process or a dicing process, and is easily broken when a bump (fine electrode) is formed on an IC chip, so that the yield is poor. For this reason, it is required to improve the handleability of the wafer in the process of manufacturing the IC chip from the ultra-thin wafer.

  In response to this requirement, a method has been proposed in which a wafer is affixed to a support plate using a support tape, and the wafer is polished while being fixed to the support plate. According to this method, the handleability of the wafer is improved, and ultrathin wafers and IC chips can be manufactured with a high yield.

  Various tapes have been developed as support tapes (see Patent Document 1). In particular, there is a commercially available product that controls the adhesive strength of the tape by applying light stimulation to the support tape (manufactured by Sekisui Chemical Co., Ltd.). "Selfa BG"). In such a method for controlling the adhesive force by light, it is considered that there is less damage to the wafer and no adverse effect on peripheral devices than the method of controlling the adhesive force by applying heat stimulation. A glass plate is widely used as the support plate. This is because glass can transmit visible light and ultraviolet light and can control the adhesive force of the support tape, and the handleability is not good, but it has a low coefficient of linear expansion and is suitable for polishing.

In recent years, plastic support plates have been developed. However, this has the disadvantages of low rigidity, a large linear expansion coefficient, and a narrow range of application to silicon wafers.
JP 2003-171624 A

  In order to solve the above-mentioned points, for the purpose of improving the bending rigidity of the plastic support plate and lowering the linear expansion coefficient, a fibrous reinforcing material having a high linear expansion coefficient such as glass fiber is added to the synthetic resin for plate molding. It is possible to mix them. However, a plastic support plate molded from a synthetic resin blended with such a different material has a problem that the transparency is lowered, and visible light and ultraviolet light for controlling the adhesive force of the support plate cannot be transmitted. This is because the refractive index and Abbe number are greatly different between the synthetic resin and the fibrous reinforcing material, and visible light and ultraviolet rays are scattered at the interface between the synthetic resin and the fibrous reinforcing material.

  In view of the above situation, the present invention provides a plastic support plate that can be used to obtain a wafer having a smooth polished surface, which can reduce the breakage of the wafer by supporting the wafer even when manufacturing an ultra-thin wafer. Another object of the present invention is to provide a support plate having high transparency, rigidity, and a low linear expansion coefficient.

  The support plate according to the present invention is formed by molding a molding material consisting of 15 to 95% by weight of a synthetic resin and 5 to 85% by weight of a fibrous reinforcing material having substantially the same refractive index and / or Abbe number as this, The ultraviolet transmittance is 30% or more.

  Here, the fact that the refractive indexes are substantially the same means that the refractive indexes coincide within a range in which a light transmittance of 50% or more and an ultraviolet transmittance of 50% or more can be confirmed. It is preferable that the refractive indexes of both coincide in the range of ± 0.015. The fact that the Abbe numbers are substantially the same means that the light transmittance matches within a range where the light transmittance is 50% or more and the ultraviolet transmittance is 50% or more. It is preferable that both Abbe numbers correspond in the range of ± 10. Ultraviolet light refers to light in the wavelength region of 320 nm to 370 nm.

The bending elastic modulus of the support plate according to the present invention is preferably 1 to 40 GPa, and the linear expansion coefficient is preferably 1.0 × 10 ^{−5 to} 7.5 × 10 ⁻⁵ (1 / ° C.).

  The ratio of the synthetic resin and the fibrous reinforcing material is 5 to 85% by weight with respect to the former 15 to 95% by weight. If the latter compounding ratio is too small, the effect of imparting rigidity to the support plate and lowering the linear expansion coefficient cannot be obtained sufficiently, and if it is too large, the transparency of the support plate decreases and the adhesive force of the support plate is controlled. It cannot transmit visible light or ultraviolet light.

  When using a support tape that can control the adhesive force by applying ultraviolet light stimulation, the support plate needs to sufficiently transmit ultraviolet light. If the refractive index of the synthetic resin and the fibrous reinforcing material is substantially the same in the ultraviolet region, the ultraviolet rays can be transmitted without being disturbed and the support tape can be stimulated. Thereby, the adhesive force of the support tape can be freely controlled. Therefore, the ultraviolet transmittance of the support plate according to the present invention is limited to 30% or more, and preferably 50% or more.

  In the present invention, the synthetic resin that forms the main component of the molding material for producing the support plate is at least one selected from the group consisting of thermoplastic resins, thermosetting resins, and photocurable resins. The thermoplastic resin is not particularly limited, but acrylonitrile-butadiene-styrene copolymer resin, polyethylene resin, polyethylene terephthalate resin, styrene polymer, epoxy resin, fluororesin, cycloolefin polymer, liquid crystal polymer, polycarbonate Resins, polymethyl methacrylic resins, and polyimide resins are preferred, and these can be used alone or in combination of two or more. Examples of the thermosetting resin include a phenol resin, a melamine resin, and an epoxy resin. As a photocurable resin, what mixed the low polymer of an epoxy acrylate, a reactive diluent, and a photoinitiator can be illustrated.

The fibrous reinforcing material, which is another component of the molding material, is composed of an inorganic or organic fibrous material having a linear expansion coefficient of preferably 1.0 × 10 ⁻⁵ (1 / ° C.) or less. The fibers constituting this substance have an aspect ratio of preferably 1 to 500, and the cross-sectional shape of the fibers is not limited, but in the case of a circle, the diameter is preferably 1 to 60 μm. The material of such a fibrous reinforcing material is not limited, but may be glass, thermosetting resin, engineering plastic, or the like.

  The size and shape of the support plate are not limited and may be circular or polygonal, and preferably have a diameter corresponding to the shape of the wafer, for example, about 150 mm, about 200 mm, about 350 mm, or about 400 mm. It is a plate.

  The basic thickness of the support plate, that is, the thickness over the entire plate is preferably 0.5 to 3 mm, and the variation in the basic thickness is preferably 1% or less, more preferably within 2 μm.

  Since the support plate according to the present invention sufficiently transmits light, it is possible to use a self-peeling adhesive tape of a system that controls the adhesive force of the adhesive tape by giving light stimulation, and there is no damage to the wafer, and the tape Can be easily peeled off from the support plate. In addition, since the support plate according to the present invention is made of synthetic resin, the material cost can be reduced, and the weight of the support plate can be reduced compared to that made of glass, the rigidity is high, and the linear expansion coefficient is glass. Comparable to those made.

  Thus, according to the present invention, even when an ultra-thin wafer is manufactured, it is possible to reduce damage to the wafer by supporting it, and a plastic support plate used to obtain a wafer having a smooth polished surface, Moreover, it is possible to provide a support plate having high transparency, rigidity, and a small linear expansion coefficient.

  Next, in order to describe the present invention specifically, examples of the present invention will be given.

Example 1
A support plate made of a molding material comprising 80% by weight of polycarbonate having the refractive index and Abbe number shown in Table 1 and 20% by weight of glass fiber having the refractive index and Abbe number (substantially the same as that of polycarbonate) shown in Table 1. Was molded. The obtained support plate was measured for ultraviolet transmittance, flexural modulus, and linear expansion coefficient. These measured values are shown in Table 1.

Comparative Example 1
A support plate made of a molding material comprising 80% by weight of polycarbonate having the refractive index and Abbe number shown in Table 1 and 20% by weight of glass fiber having the refractive index and Abbe number (substantially different from that of polycarbonate) shown in Table 1. Was molded. The obtained support plate was measured for ultraviolet transmittance, flexural modulus, and linear expansion coefficient. These measured values are shown in Table 1.

  As is apparent from Table 1, in Example 1, the use of the fibrous reinforcing material improves the bending rigidity, decreases the linear expansion coefficient, and further substantially reduces the refractive index and Abbe number to those of the polycarbonate resin. Good transmittance was obtained by the same.

Example 1
In the same manner as in Example 1, a support plate was molded from a molding material comprising 80% by weight of polycarbonate and 20% by weight of glass fibers having substantially the same refractive index and Abbe number. The ultraviolet transmittance of this support plate was 70%. A support tape (“Selfa BG” manufactured by Sekisui Chemical Co., Ltd.) was attached to the support plate, and a wafer was fixed on the support plate to polish the surface. Thereafter, gas was generated from the support tape by ultraviolet irradiation (using a high-pressure mercury lamp with a central wavelength of 365 nm, irradiation intensity of 100 mW) from the back surface of the support tape, thereby reducing the adhesive strength of the support tape. This peeled off the wafer from the support tape. The time from gas generation to wafer peeling was 18 seconds.

Example 2
In the same manner as in Reference Example 1, a support plate was molded from a molding material comprising 80% by weight of polycarbonate and 20% by weight of glass fibers having a refractive index and an Abbe number substantially different from those. The ultraviolet transmittance of this support plate was 15%. A support tape (“Selfa BG” manufactured by Sekisui Chemical Co., Ltd.) was attached to the support plate, and a wafer was fixed on the support plate to polish the surface. Thereafter, ultraviolet irradiation (using a high-pressure mercury lamp with a central wavelength of 365 nm, irradiation intensity: 100 mW) was performed from the back surface of the support tape, but only a slight amount of gas was generated from the support tape, and the wafer was not peeled off from the support tape.

Claims (1)

A molding material comprising 15 to 95% by weight of a synthetic resin and 5 to 85% by weight of a fibrous reinforcing material having substantially the same refractive index and / or Abbe number as this, and having an ultraviolet transmittance of 30% or more Is the support plate.