Method for manufacturing semiconductor device and oxidation handling method for plasma body

Abstract

A polysilicon electrode layer (103) (a first electrode layer) is formed by forming a polysilicon film on a gate oxide film (102) on a silicon wafer (101). A tungsten layer (105) (a second electrode layer) is formed on this polysilicon electrode layer (103). In addition, a barrier layer (104) is formed on the polysilicon electrode layer (103) before the formation of the tungsten layer (105). Etching is then conducted using a silicon nitride layer (106) as the etching mask. Next, an oxide insulating film (107) is formed on an exposed surface of the polysilicon layer (103) by plasma oxidation wherein a process gas containing oxygen gas and hydrogen gas is used at a process temperature not less than 300 1 / 2 C. With this method, a selective oxidation of the polysilicon electrode layer (103) can be carried out without oxidizing the tungsten layer (105).

Description

technical field [0001] The present invention relates to a method of manufacturing a semiconductor device in which a semiconductor substrate is treated with plasma, and a plasma oxidation treatment method. Background technique [0002] In recent years, gate oxide films and the like have been made ultra-thin due to high-speed transistors and device size reductions. A gate of a transistor is usually formed in this order of a well (well), a gate insulating film, and a gate electrode. After the gate electrode is formed, a side surface of the gate electrode is subjected to wet etching. As a result, the gate electrode is exposed, and when a voltage is applied to the gate electrode, electric field concentration occurs in the exposed portion, causing disadvantages such as an increase in leakage current. Therefore, an insulating film is usually formed on the exposed portion of the gate electrode. [0003] Generally, polysilicon is used as a gate electrode, but since polysilicon has...

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Problems solved by technology

[0004] However, since tungsten is rapidly oxidized at about 300°C, the resistance value of the tungsten layer will increase when the gate electrode is thermally oxidized

As a result, the resistance value of the gate electrode increases as

In addition, the reaction between tungsten and polysilicon may cause the diffusion of tungsten nitride (WN) in the diffusion prevention layer, resulting in an increase in resistivity

[0005] In addition, thermal oxidation treatment itself takes a relatively long time

Therefore, it is hindered to increase the production volume to improve the productivity

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