FET having gate insulating film of nonuniform thickness and asymmetrical source and drain structures
First Claim
1. A high withstand voltage transistor comprising:
- a semiconductor substrate;
a channel stop region located on said substrate and formed of the same impurity as that of said substrate;
field oxide films formed on said channel stop region;
a channel region having a nonuniform impurity concentration on an active region between said field oxide films;
a gate insulating film having a step difference formed on said channel region;
a source and drain region having asymmetrical impurity distribution on both sides of said channel region, said source and drain region being LDD structures and said asymmetrical impurity distribution of said source and drain region having n+ and n- type impurities, respectively;
a gate electrode having a step difference formed on said gate insulating film;
a spacer formed on the sidewalls of said gate electrode;
an interlayer dielectric film having a contact hole formed on the whole surface of the resultant structure; and
a metal electrode formed by filling said contact hole;
wherein said channel region comprises a first channel region at low concentration and a second channel region at high concentration formed by ion-implanted impurities of the same conductivity type as that of the semiconductor substrate; and
wherein a first gate insulating film region is formed on said first channel region, and a second gate insulating film region is formed on said second channel region.
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Accused Products
Abstract
A high withstand voltage transistor and a method for manufacturing the same are disclosed. The transistor includes a semiconductor substrate, a field oxide film, a channel region formed of first and second channel regions each having a different concentration level, a gate insulating film having a step difference, a gate electrode having a step difference, a drain region including first, second, and third impurity regions, a source region including first and third impurity regions, a spacer, an interlayer dielectric film and a metal electrode. Threshold voltage can be maintained to an appropriate level, junction break voltage can be increased, and the punchthrough characteristic can also be enhanced.
116 Citations
11 Claims
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1. A high withstand voltage transistor comprising:
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a semiconductor substrate; a channel stop region located on said substrate and formed of the same impurity as that of said substrate; field oxide films formed on said channel stop region; a channel region having a nonuniform impurity concentration on an active region between said field oxide films; a gate insulating film having a step difference formed on said channel region; a source and drain region having asymmetrical impurity distribution on both sides of said channel region, said source and drain region being LDD structures and said asymmetrical impurity distribution of said source and drain region having n+ and n- type impurities, respectively; a gate electrode having a step difference formed on said gate insulating film; a spacer formed on the sidewalls of said gate electrode; an interlayer dielectric film having a contact hole formed on the whole surface of the resultant structure; and a metal electrode formed by filling said contact hole; wherein said channel region comprises a first channel region at low concentration and a second channel region at high concentration formed by ion-implanted impurities of the same conductivity type as that of the semiconductor substrate; and wherein a first gate insulating film region is formed on said first channel region, and a second gate insulating film region is formed on said second channel region. - View Dependent Claims (2, 3)
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4. A high withstand voltage transistor comprising:
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a semiconductor substrate; a channel stop region located on said substrate and formed of the same impurity as that of said substrate; field oxide films formed on said channel stop region; a channel region having a nonuniform impurity concentration on an active region between said field oxide films; a gate insulating film having a step difference formed on said channel region; a source and drain region having asymmetrical impurity distribution on both sides of said channel region, said source and drain region being LDD structures and said asymmetrical impurity distribution of said source and drain region having n+ and n- type impurities, respectively; a gate electrode having a step difference formed on said gate insulating film; a spacer formed on the sidewalls of said gate electrode; an interlayer dielectric film having a contact hole formed on the whole surface of the resultant structure; and a metal electrode formed by filling said contact hole; wherein said gate insulating film comprises a thick first gate insulating film region and a thin second gate insulating film region; and wherein said first gate insulating film region is formed on a first channel region, and said second gate insulating film region is formed on a second channel region. - View Dependent Claims (5, 6)
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7. A high withstand voltage transistor comprising:
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a semiconductor substrate; a channel stop region located on said substrate and formed of the same impurity as that of said substrate; field oxide films formed on said channel stop region; a channel region having a nonuniform impurity concentration on an active region between said field oxide films; a gate insulating film having a step difference formed on said channel region; a source and drain region having asymmetrical impurity distribution on both sides of said channel region, said source and drain region being LDD structures and said asymmetrical impurity distribution of said source and drain region having n+ and n- type impurities, respectively; a gate electrode having a step difference formed on said gate insulating film; a spacer formed on the sidewalls of said gate electrode; an interlayer dielectric film having a contact hole formed on the whole surface of the resultant structure; and a metal electrode formed by filling said contact hole; wherein said drain region includes shallow first and deep second impurity regions at low concentration formed of an opposite conductive impurity to that of said semiconductor substrate and a shallow third impurity region at high concentration. - View Dependent Claims (8, 9)
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10. A high withstand voltage transistor comprising:
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a semiconductor substrate; a channel stop region located on said substrate and formed of the same impurity as that of said substrate; field oxide films formed on said channel stop region; a channel region having a nonuniform impurity concentration on an active region between said field oxide films; a gate insulating film having a step difference formed on said channel region; a source and drain region having asymmetrical impurity distribution on both sides of said channel region, said source and drain region being LDD structures and said asymmetrical impurity distribution of said source and drain region having n+ and n- type impurities, respectively; a gate electrode having a step difference formed on said gate insulating film; a spacer formed on the sidewalls of said gate electrode; an interlayer dielectric film having a contact hole formed on the whole surface of the resultant structure; and a metal electrode formed by filling said contact hole; wherein said source region includes a shallow first impurity region at low concentration and a shallow third impurity region at high concentration. - View Dependent Claims (11)
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Specification