Claims
- 1. A process of producing a semiconductor device, comprising the steps of:forming a first polycrystalline silicon film, of a first crystal grain size, above a substrate; implanting ions in said first polycrystalline silicon film by ion implantation so as to render amorphous a portion of the thickness of the first polycrystalline silicon film, leaving a remaining portion thereof having the first crystal grain size; and crystallizing the amorphous portion of the thickness by heat treatment so as to form a second polycrystalline silicon film, thereby to provide a layer-built film, wherein the second polycrystalline silicon film has a second crystal grain size larger than the first crystal grain size.
- 2. A process of producing a semiconductor device, comprising the steps of:forming a first polycrystalline silicon layer above a substrate, said first polycrystalline silicon layer having a first temperature dependence of resistance; and forming a second polycrystalline silicon layer overlying said first polycrystalline silicon layer, so as to form a layer-built film including the first and second polycrystalline silicon layers, said second polycrystalline silicon layer having a second temperature dependence of resistance different from said first temperature dependence of resistance.
- 3. A process as claimed in claim 2, wherein one of said first and second polycrystalline silicon layers is formed to have crystals of a first grain size, and the other of the first and second polycrystalline silicon layers is formed to have crystals of a second grain size smaller than the first grain size.
- 4. A process as claimed in claim 2, wherein the second polycrystalline silicon layer is formed to have one of a positive and a negative temperature dependence of resistance, and the first polycrystalline silicon layer is formed to have the other of the positive and the negative temperature dependence of resistance.
- 5. A process as claimed in claim 2, wherein said second polycrystalline silicon layer is thicker than said first polycrystalline silicon layer.
- 6. A process as claimed in claim 2, wherein said second polycrystalline silicon layer has a larger grain size than that of the first polycrystalline silicon layer.
- 7. A process as claimed in claim 2, wherein said second polycrystalline silicon layer is thicker than the first polycrystalline silicon layer, and has a larger grain size than that of the first polycrystalline silicon layer.
- 8. A process as claimed in claim 1, wherein the first polycrystalline silicon layer has a different temperature dependence of resistance than that of the second polycrystalline silicon layer.
- 9. A process as claimed in claim 1, wherein said second polycrystalline silicon layer is thicker than said first polycrystalline silicon layer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
5-047730 |
Mar 1993 |
JP |
|
Parent Case Info
This application is a Divisional application of application Ser. No. 08/519,096, filed Aug. 24, 1995 now U.S. Pat. No. 5,793,097, the contents of which are incorporated herein by reference in their entirety, which application Ser. No. 08/519,096 is a Continuation application of application Ser. No. 08/207,132, filed Mar. 7, 1994 now abandoned.
US Referenced Citations (4)
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Continuations (1)
|
Number |
Date |
Country |
Parent |
08/207132 |
Mar 1994 |
US |
Child |
08/519096 |
|
US |