Manufacture of mos semiconductor element

Abstract

Abstract PURPOSE:To form a reverse taper surely below a gate edge, to relax field concentration and to improve the gate breakdown strength by oxidizing a gate electrode consisting of polycrystalline silicon, etc., whose impurity concentration is higher in an upper part than in a lower part and by forming a sidewall oxide film which corresponds to the distribution of impurity concentration. CONSTITUTION:A gate electrode 13 consists of polycrystalline or amorphous silicon having a specified distribution whose concentration of conductive impurity contact is higher in a lower part 13a than in an upper part 13b. The gate electrode 13 is formed on a semiconductor substrate 10 through an oxide film 12. Then, the gate electrode 13 is oxidized to form side wall oxide films 16, 17 having a film thickness corresponding to concentration distribution of the said conductive impurity onto the sidewall of the gate electrode 13. For example, after a polycrystalline Si gate 13 is formed which consists of high concentration phosphorus content layer 13a and a low concentration phosphorus content layer 13b, n-type impurity is doped to form an n-type high concentration source/drain region 11. Then, a polycrystalline Si gate 13 is thermally oxidized by wet oxidation at 750 deg.C to form an oxide film on the upper side and the sidewall of the polycrystalline Si gate 13.

Inventors

• 👤 Nobuyoshi Sakakibara
• 👤 伸義 榊原
• 👤 Hisazumi Oshima
• 👤 久純 大島
• 👤 Yoshiki Ueno
• 👤 上野　祥樹

Bibliographic Details