JPH06349797A - Grinding-polishing supporting substrate - Google Patents

Abstract

PURPOSE:To prevent the generation of a crack in the surface to be supported of a semiconductor substrate due to the intrusion of foreign matters, etc., in grinding and polishing by forming a grinding-polishing supporting substrate into a disc having an orientation flat part and also by forming the substrate from carbon. CONSTITUTION:A carbon substrate 1 is formed into a disc and an orientation flat part is formed in a part of the substrate. When the carbon substrate 1 is used for grinding and polishing of a silicon substrate 4 being a semiconductor substrate with active layer 3 formed therein, the carbon substrate 1 is bonded to the surface provided with the active layer 3 of the silicon substrate 4. Then, the surface with no active layer 3 formed therein of the semiconductor substrate 4 is ground or polished after the carbon substrate 1 is mounted on a supporting part. Thus, it is possible to prevent the breakdown of the semiconductor substrate and that of an element caused by the intrusion of foreign matters in grinding and polishing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for grinding / polishing, which has a high strength and is excellent in flatness and surface accuracy, which is particularly used for grinding / polishing a semiconductor substrate.

[0002]

2. Description of the Related Art Silicon (Si) with an element formed inside
A substrate or a semiconductor substrate such as a gallium arsenide (GaAs) substrate leaves an active layer (element portion), and other portions are essentially unnecessary for the operation of the element. Furthermore, by removing this unnecessary portion, the device performance can be greatly improved. For this reason, as a method of removing this unnecessary portion, a supporting substrate for element protection is attached to the element side of the semiconductor substrate, the non-element forming side of the semiconductor substrate is ground / polished, and the semiconductor substrate having only the active layer is removed. SOI (Silicon On Insulator) technology, which is used by sticking to an insulating substrate of the above, has been developed.

As the grinding / polishing support substrate, a highly flat and highly smooth substrate is required because it is necessary to precisely control the grinding / polishing allowance of the semiconductor substrate. In addition, an existing semiconductor substrate such as a silicon substrate or a gallium arsenide substrate is provided with an orientation flat portion for clarifying the crystal orientation. Further, in order to prevent chipping of the edge of the substrate during element formation, a beveling process for rounding the outer peripheral portion of the substrate is performed. As a substrate for grinding / polishing support, a semiconductor having such a shape is used. It must have the same shape as the substrate. Therefore, at present, a silicon substrate having the same shape as the semiconductor substrate on which the element is formed is mainly used as a substrate for grinding / polishing support.

[0004]

However, when a silicon substrate is used as a substrate for grinding / polishing a semiconductor substrate, foreign matter (polishing agent, various dusts) or the like is generated when performing grinding / polishing after adhering to the semiconductor substrate. The biting causes cracks on the surface of the silicon substrate, and in the worst case, the device itself is destroyed.

The present invention has been made in view of the above problems, and it is possible to prevent the occurrence of cracks on the surface of a semiconductor substrate to be supported due to the inclusion of foreign matter or the like during grinding / polishing, and Grinding that can prevent the destruction of
An object is to provide a substrate for polishing support.

[0006]

The substrate for grinding / polishing support according to the present invention is characterized in that it has a disk shape having an orientation flat portion and is made of carbon.

[0007]

First, the present inventor investigated the state of destruction of substrates made of various materials in order to prevent the destruction of the semiconductor substrate due to the inclusion of foreign matter during grinding and polishing. The results are shown in Table 1 below.
Shown in.

[0008]

[Table 1]

The test was conducted by imposing minute scratches (indentations) on the surface of the substrate in order to simulate the destruction of the substrate due to the entrapment of foreign matter. The indentation was formed by pressing the indenter against each substrate with a load of 3 kg for 30 seconds using a micro Vickers hardness meter. After that, a three-point bending test was performed to measure changes in bending strength depending on the presence or absence of minute scratches (indentations). As a result, as shown in Table 1, in the tempered glass substrate, the crystallized glass substrate, and the silicon substrate, the bending strength is significantly reduced due to the indentation. However, in the case of a carbon substrate, the bending strength is 25 kg / mm ² when there is no indentation, whereas the bending strength is 22 kg / mm ² when there is an indentation. Is hardly seen. In other words, in substrates other than the carbon substrate, the fracture test after making the indentation propagated cracks starting from the indentation, and the fracture strength decreased, whereas in the case of the carbon substrate, the fracture strength almost decreased. It is thought that it will not occur. From the above test results, the present invention selects the carbon substrate as the grinding / polishing support substrate capable of preventing the element destruction due to the entrapment of foreign matter.

[0010]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a plan view showing a grinding / polishing support substrate according to an embodiment of the present invention, and FIG. 2 is a substrate cross-sectional view at the time of grinding / polishing a semiconductor substrate. The carbon substrate 1 has a disc shape, and an orientation flat portion 2 is formed on a part thereof.

When this carbon substrate 1 is used for grinding / polishing a silicon substrate 4 which is a semiconductor substrate on which the active layer 3 is formed, the active layer 3 of the silicon substrate 4 is provided as shown in FIG. The carbon substrate 1 is adhered to the surface on which it is formed. Then, after mounting the carbon substrate 1 on the support portion,
The surface of the semiconductor substrate 4 on which the active layer 3 is not formed is ground or polished.

Next, a method of manufacturing the carbon substrate of this embodiment will be described. A phenol resin, which is a thermosetting resin that becomes vitreous carbon after carbonization and firing, is hot-press molded into a disk shape having an orientation flat portion. Then, this is heated to a temperature of, for example, 1500 ° C. in a nitrogen gas atmosphere and pre-baked. Next, this is subjected to HIP treatment by applying an isotropic pressure of 1800 atm while being heated to 2600 ° C. using a hot isostatic press (HIP). The obtained molded body is subjected to predetermined beveling processing and surface mirror finishing, and for example, a surface roughness Ra of about 10Å
An inch type grinding / polishing support substrate is produced. At this time, the flatness is, for example, 4 μm, which is about the same as that of a normal silicon substrate.

Next, the carbon substrate (Example) actually manufactured under the above-mentioned conditions is adhered to the element forming side of the 5-inch type silicon substrate on which the element is formed, and the surface of the silicon substrate on the non-element forming side is bonded. The results of grinding and polishing will be described. Further, as a comparative example, the same grinding / polishing was carried out on a silicon substrate having the same shape stuck as a grinding / polishing supporting substrate. Each of the 10 grinding / polishing support substrates of the examples and comparative examples was continuously ground / polished, and then the substrates were washed and dried. Then, the state of cracks and breakage on the substrate surface was visually evaluated. The results are shown in Table 2 below.

[0014]

[Table 2]

As shown in Table 2, when a silicon substrate (comparative example) is used as a substrate for supporting grinding / polishing,
Cracks occurred in the grinding / polishing support substrate in 8 out of 10 substrates. In addition, in the case of destruction, cracks reaching the element formed on the semiconductor substrate also existed. However, when a carbon substrate was used, no cracks or breaks were observed on any of the substrates and devices.

[0016]

As described above, since the grinding / polishing supporting substrate according to the present invention uses carbon as a constituent material,
It is possible to prevent breakage of the semiconductor substrate and breakage of the element due to foreign matter being caught during grinding / polishing. Therefore, the present invention can contribute to a significant improvement in device performance.

[Brief description of drawings]

FIG. 1 is a plan view showing the shape of a carbon substrate for grinding / polishing support according to an embodiment of the present invention.

FIG. 2 shows a cross-sectional view of a substrate during grinding / polishing.

[Explanation of symbols]

 1; Carbon substrate 2; Orientation flat part 3; Active layer 4; Silicon substrate

Claims (1)

[Claims] 1. A substrate for grinding / polishing support, which has a disk shape having an orientation flat portion and is formed of carbon.