Semiconductor device with no stress generated at the trench corner portion and the method for making the same
First Claim
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1. A semiconductor device comprising:
- a semiconductor substrate having a main surface, a prescribed impurity concentration of a first conductivity type and a trench;
a thick insulating film formed on either a bottom portion or a sidewall portion of said trench, an end portion of said thick insulating film extending in either a vertical upward direction when said thick insulating film is formed on the bottom portion or a horizontal direction when the thick insulating film is formed on the sidewall portion;
a thin insulating film extending in the direction orthogonal to said thick insulating film and connected to the end portion of said thick insulating film; and
a first impurity region of a second conductivity type formed in said semiconductor substrate on either the sidewall portion or the bottom portion and the sidewall portion of said trench on which said thick insulating film is not formed, only in the side portion or lower portion of said thin insulating film, said thick insulating film is formed byforming a two-layer film constituted by an oxide film and a nitride film on the main surface of said semiconductor substrate, side portions and a portion of the bottom portion of the trench, andforming a selective oxide film to form said thick insulating film on the bottom portion of the trench of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon, wherebythe direction of extension of the end portion of said selective oxide film changing from horizontal to vertical upward with a large curvature.
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Abstract
The semiconductor device in which no stress occurs at the corner portion of the trench comprises a p type semiconductor substrate having a trench and a main surface, a thick insulating film formed on the bottom portion of the trench, a thin insulating film formed on the sidewall portion of the trench and connected to the end portion of the thick insulating film, and an n type impurity region formed in the semiconductor substrate only on the side portion of the thin insulating film.
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Citations
14 Claims
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1. A semiconductor device comprising:
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a semiconductor substrate having a main surface, a prescribed impurity concentration of a first conductivity type and a trench; a thick insulating film formed on either a bottom portion or a sidewall portion of said trench, an end portion of said thick insulating film extending in either a vertical upward direction when said thick insulating film is formed on the bottom portion or a horizontal direction when the thick insulating film is formed on the sidewall portion; a thin insulating film extending in the direction orthogonal to said thick insulating film and connected to the end portion of said thick insulating film; and a first impurity region of a second conductivity type formed in said semiconductor substrate on either the sidewall portion or the bottom portion and the sidewall portion of said trench on which said thick insulating film is not formed, only in the side portion or lower portion of said thin insulating film, said thick insulating film is formed by forming a two-layer film constituted by an oxide film and a nitride film on the main surface of said semiconductor substrate, side portions and a portion of the bottom portion of the trench, and forming a selective oxide film to form said thick insulating film on the bottom portion of the trench of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon, whereby the direction of extension of the end portion of said selective oxide film changing from horizontal to vertical upward with a large curvature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A semiconductor device comprising:
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a semiconductor substrate having a main surface, a prescribed impurity concentration of a first conductivity type and a trench; a thick insulating film formed on either a bottom portion or a sidewall portion of said trench, and an end portion of said thick insulating film extending in either a vertical upward direction when said thick insulating film is formed on the bottom portion or a horizontal direction when the thick insulating film is formed on the sidewall portion; a thin insulating film extending in the direction orthogonal to said thick insulating film and connected to the end portion of said thick insulating film; and a first impurity region of a second conductivity type formed in said semiconductor substrate on either the sidewall portion or the bottom portion and the sidewall portion of said trench on which said thick insulating film is not formed, only in the side portion or lower portion of said thin insulating film, said thick insulating film is formed by; forming a two-layer film constituted by an oxide film and a nitride film on the main surface of said semiconductor substrate and on that region of the sidewall portion of said trench other than the regions adjacent to the bottom portion of said trench, forming a selective oxide film to form said thick insulating film on the bottom portion of the trench of said semiconductor substrate by oxidizing said semiconductor substrate with said two-layer film formed thereon with the bottom portion of said trench and the regions of the sidewall portion of said trench adjacent to said bottom portion being exposed, whereby an end portion of said selective oxide film extending only in the vertical upward direction.
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Specification