Kabushiki Kaisha Toshiba

Kabushiki Kaisha Tobisha

Tsutomu Amai

Masanobu Ogino

Takanobu Kamakura

Shuichi Samata

Yoshihiro Ueno

A method for manufacturing a semiconductor device can reduce a micro-roughness and does not change a construction and electric characteristics of elements formed in the semiconductor device. In the method for manufacturing the semiconductor device including a pre-oxidation process in which an oxide layer is first formed on a silicon wafer, and the oxide layer is secondly eliminated to eliminate impurities on a surface of the silicon wafer, a formation of the oxide layer in the pre-oxidation process is performed in an oxidization atmosphere including H.sub.2 O and gas including germanium hydride (german --GeH.sub.4 --). Since german (GeH.sub.4) is included in the oxidization atmosphere, it is possible to reduce a softening temperature of the silicon dioxide formed in pre-oxidation, thereby decreasing the micro-roughness on the surface of the silicon wafer. Furthermore, since it is possible to perform the pre-oxidation process in a low temperature and in a short time, there is no change of a construction and electric characteristics of elements formed in the semiconductor device.

Method for manufacturing a semiconductor device including pre-oxidation

A manufacturing method of this invention improves nonuniformity in film thickness of a circuit element formation region produced due to a poor flatness of a semiconductor substrate in the manufacture of a semiconductor substrate having a dielectric isolating structure. Mirror-polished surfaces of first and second semiconductor substrates are opposed and bonded to each other so as to sandwich a dielectric having a predetermined thickness, and the first semiconductor substrate is ground from the surface opposite to the adhesion surface to have a predetermined thickness with reference to the dielectric. An impurity is doped in the first semiconductor substrate to form a high-concentration impurity layer having an impurity concentration corresponding to a predetermined low-concentration impurity layer having a predetermined thickness thereon, thereby constituting a circuit element region. This invention is a method of manufacturing a semiconductor substrate, which improves film thickness precision of each circuit element formation layer for forming a circuit element.

Method of manufacturing semiconductor substrate dielectric isolating

The ratio between variations in the oxygen concentration before and after a silicon wafer is subjected to two types of heat treatments in which the temperatures and processing times are different is defined. The silicon wafer is subjected to a first heat treatment, and the interstitial oxygen concentrations before and after the first heat treatment are respectively set to [Oi].sub.1ini and [Oi].sub.1af. The silicon wafer is successively subjected to second and third heat treatments, and the interstitial oxygen concentrations before and after the second and third heat treatments are respectively set to [Oi].sub.2ini and [Oi].sub.2af. At this time, the interstitial oxygen concentrations [Oi].sub.1ini, [Oi].sub.1af, [Oi].sub.2ini and [Oi].sub.2af are so set as to satisfy the condition that ([Oi].sub.2ini -[Oi].sub.2af)/[Oi].sub.1ini -[Oi].sub.1af).gtoreq.20.

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Tokyo, Japan

Tsutomu Amai