JPS5917242A - Quartz glass for manufacturing semiconductor - Google Patents

Abstract

PURPOSE:To disperse thermal energy, and to enable uniform heating even when there are a temperature unevenness in a heat source to some extent by using quartz glass formed through pyrolysis as an inner surface and bubbled quartz glass as an outer surface. CONSTITUTION:Quartz glass formed by pyrolyzing silica tetrachloride is used as an inner layer, while a quartz glass electrically melted under a vaccuum state is used as an intermediate layer and bubbled silica glass formed through a rotary melting method from raw-material powder as an outer layer, one end of a tubular laminate of these three layers is sealed, the laminate is heated from the circumference by an oxyhydrogen burner while being sucked by a vacuum pump from the other end, and three layers are unified. An inner diameter is 130mm., an outer diameter 146mm. and length 2,000mm. in the size of a core pipe for a diffusion furnace obtained by stretching the laminate out while heating it, and the inner layer is 2mm., the intermediate layer 4mm. and the outer layer 2mm. in each layer. When the core pipe is compared with a core pipe obtained through a vacuum electric melting method of the same size and used for the diffusion treatment of a silicon wafer for an MOS, it was proved that there existed no defect, while the semiconductor characteristics of the core pipe through the vacuum electric melting method showed seatterings extremely, and it was proved that it could not be adopted for practical use.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of quartz glass used in the complete manufacture of semiconductors. Quartz glass is heat resistant,
It has excellent properties such as low thermal expansion and high purity, and is widely used, especially in the semiconductor field. This quartz glass also has different characteristics depending on the manufacturing method, and is used differently depending on its characteristics. For example, flame-fused natural quartz has many bubbles, OH groups, and impurities, and cannot be used particularly for MO8 stones that require high purity. Flame-melted π materials tend to have a large number of OH groups, and OH groups have a large effect on the viscosity of quartz glass, so they cannot be used in high-temperature applications that require heavy loads, such as glass or large glass. Although high-purity products can be obtained by thermally decomposing silicon compounds, they contain many OH groups and are unsuitable for large-sized furnace tubes. As described above, there are differences in the properties of quartz glass depending on the various raw materials and manufacturing methods, and although quartz glass is used depending on its properties, it does not necessarily satisfy all the required conditions.

The inventors of the present application took all of these circumstances into account, researched quartz glass that could compensate for its drawbacks while taking advantage of its respective characteristics, and completed the present invention.

In other words, the inner surface of quartz glass for semiconductor manufacturing, which requires high purity, is made of quartz glass produced by thermal decomposition.
The outer surface is made of porous quartz glass. Quartz glass with a fully porous outer surface is heated from the surroundings, for example in a crucible for silicon pulling or in a furnace core tube for a diffusion furnace, but with transparent quartz glass, the temperature difference of the heat source is directly affected by the heating problem. Since it is easy to heat, by using all the quartz glass with bubbles, the thermal energy is dispersed and uniform heating is possible even if the temperature of the heat source is slightly uneven. In this case, it is preferable to use vacuum-fused silica glass for the intermediate layer because it has high viscosity and properties and is less likely to deform even when used at high temperatures.

To manufacture such quartz glass gold, all quartz glass elements with the required wall thickness are laminated, one end of which is sealed, pressure is reduced from the other end, and the outer layer is heated from the outside to form an integral outer layer. It will be destroyed.

EXAMPLE The inner layer is quartz glass produced by thermally decomposing silicon tetrachloride, the middle layer is quartz glass melted by full-vacuum electricity, and the outer layer is multifoamed quartz glass produced by full-rotation melting of raw material powder. One end of the laminate is sealed, and the other end is heated with an oxyhydrogen burner while suction is applied with a vacuum pump.
It was made into one thing. This was further heated and stretched to obtain a furnace core tube for a diffusion furnace.

The dimensions of this item are inner diameter 130u, outer diameter 14611, and length 2. Out) ms, each layer had 2 Ils for the inner layer, 48 for the middle layer, and 2 Ils for the outer layer. When compared with a furnace core tube obtained by the vacuum electric melting method of the same size and used for the diffusion treatment of silicon wafers for MO8, the one of the present invention rarely had any defects; The electric melting method showed extreme variations in semiconductor properties and was proven to be unusable.

In the embodiments of the present invention, a three-layer structure was compared, but three layers are not necessarily required for pulling silicon single crystals, and may be adapted depending on the required characteristics.

Alternatively, it has become clear that even when the quartz glass of the present invention is used on the inner surface of a multicellular quartz glass tube or in an arc tube, it exhibits all the characteristics that are not found in those of a single structure.

Claims (1)

[Claims] 1. A quartz glass for semiconductor manufacturing, characterized in that at least the inner surface is made of a quartz glass layer produced by thermal decomposition, and the outer surface is made of a multicellular quartz glass layer.