Claims
- 1. A nonvolatile semiconductor storage device comprising:
- a nonvolatile semiconductor storage element having a floating gate including a polycrystalline silicon film formed on a semiconductor substrate through a first insulating film and a control gate including a polycrystalline silicon film formed on the floating gate through a second insulating film;
- a MOS transistor having a gate electrode including a first polycrystalline silicon film formed on said semiconductor substrate through a third insulating film, a fourth insulating film formed on the first polycrystalline silicon film, and a second polycrystalline silicon film formed on the fourth insulating film, said first polycrystalline silicon film contacting said second polycrystalline film through an opening formed in the fourth insulating film, outside edges of said first and second polycrystalline silicon films and said fourth insulating film being substantially aligned vertically so as to form a laminate structure; and
- an impurity diffused layer formed on said semiconductor substrate and held in common by said nonvolatile semiconductor storage element and said MOS transistor.
- 2. A nonvolatile semiconductor storage device according to claim 1, wherein:
- said floating gate is formed on said impurity diffused layer so as to have a portion overlapping said impurity diffused layer; and
- a film thickness of said first insulating film at least at the overlapping portion is substantially uniform within a range of 5 to 15 nm.
- 3. A nonvolatile semiconductor storage device according to claim 1, wherein said first insulating film has a substantially uniform film thickness as a whole within a range of 5 to 15 nm.
- 4. A nonvolatile semiconductor storage device according to claim 1, wherein said MOS transistor is a select transistor of said nonvolatile semiconductor storage element; and
- said nonvolatile semiconductor storage element and said select transistor hold the impurity diffused layer on one side in common.
- 5. A nonvolatile semiconductor storage device according to claim 1, wherein said first and second polycrystalline silicon films and said fourth insulating film are formed over an element region of said semiconductor substrate where no field oxide film is formed.
- 6. A nonvolatile semiconductor storage device according to claim 5, wherein:
- said floating gate is formed on said impurity diffused layer so as to have a portion overlapping said impurity diffused layer; and
- a film thickness of said first insulating film at least at the overlapping portion is substantially uniform within a range of 5 to 15 nm.
- 7. A nonvolatile semiconductor storage device according to claim 5, wherein said first insulating film has a substantially uniform film thickness as a whole with a range of 5 to 15 nm.
- 8. A nonvolatile semiconductor storage device according to claim 5, wherein said MOS transistor is a select transistor of said nonvolatile semiconductor storage element; and
- said nonvolatile semiconductor storage element and said select transistor hold the impurity diffused layer on one side in common.
Priority Claims (2)
Number |
Date |
Country |
Kind |
6-079811 |
Mar 1994 |
JPX |
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06-114019 |
Apr 1994 |
JPX |
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Parent Case Info
This application is a continuation of U.S. patent application Ser. No. 08/409,815, filed Mar. 24, 1995 now abandoned.
US Referenced Citations (6)
Continuations (1)
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Number |
Date |
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Parent |
409815 |
Mar 1995 |
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