Claims
- 1. A method for fabricating a flash memory cell on a semiconductor substrate, the method comprising the steps of:
implanting a channel dopant into said semiconductor substrate, wherein a concentration of said channel dopant in said semiconductor substrate from implantation is less than about 4×1013/cm2; forming a source line mask over said substrate, wherein said source line mask has an opening to expose a source line of said semiconductor substrate; implanting a source line dopant of a first conductivity type into said exposed source line of said semiconductor substrate through said opening of said source line mask; wherein a conductivity type of said channel dopant is same as said first conductivity type of said source line dopant; removing said source line mask from said semiconductor substrate; forming a drain mask over said semiconductor substrate, wherein said drain mask has an opening to expose a drain region of said semiconductor substrate; implanting a drain dopant of a second conductivity type into said exposed drain region of said semiconductor substrate through said opening of said drain mask to form a drain region of said flash memory cell; wherein said first conductivity type of said source line dopant is opposite to said second conductivity type of said drain dopant; wherein a channel region of said semiconductor substrate is disposed between said source line and said drain region; and using said source line dopant that diffuses from said source line into said channel region to alter a threshold voltage of said flash memory cell or to reduce short channel effects of said flash memory cell.
- 2. The method of claim 1, wherein said source line dopant and said channel dopant are comprised of boron when said drain dopant is an n-type dopant.
- 3. The method of claim 1, wherein said step of implanting said channel dopant is not performed such that said concentration of said channel dopant in said semiconductor substrate from implantation is substantially zero.
- 4. The method of claim 1, further comprising the step of:
heating said semiconductor substrate such that said source line dopant diffuses into said channel region.
- 5. The method of claim 4, wherein said semiconductor substrate is heated to a temperature in a range of from about 400° Celsius to about 1200° Celsius.
- 6. The method of claim 1, wherein said source line dopant is implanted at an energy of from about 10 keV to about 40 keV with a dosage of from about 1×1013 atoms/cm2 to about 5×1014 atoms/cm.
- 7. The method of claim 1, wherein said drain dopant is implanted at an energy of from about 30 keV to about 60 keV with a dosage of from about 5×1013 atoms/cm2 to about 5×1015 atoms/cm2.
- 8. The method of claim 1, wherein said flash memory cell comprises a first poly layer disposed on a tunnel oxide, an ONO multi-layer dielectric over said first poly layer, and a second poly layer over the ONO multi-layer dielectric.
- 9. The method of claim 1, wherein said flash memory cell comprises an ONO charge trapping layer, and a poly layer over the ONO charge trapping layer.
- 10. The method of claim 1, further comprising the step of:
implanting a source region dopant having a conductivity type that is same as the second conductivity type of said drain dopant to form a source region of said flash memory cell.
- 11. A flash memory cell fabricated on a semiconductor substrate, the flash memory cell comprising:
a source line formed from implantation of a source line dopant of a first conductivity type into said semiconductor substrate; a drain region formed from implantation of a drain dopant of a second conductivity type into said semiconductor substrate; wherein said first conductivity type of said source line dopant is opposite to said second conductivity type of said drain dopant; a channel region disposed between said source line and said drain region, and wherein a channel dopant is implanted into said channel region such that a concentration of said channel dopant in said channel region from implantation is less than about 4×1013/cm2; and wherein a conductivity type of said channel dopant is same as said first conductivity type of said source line dopant; and wherein said source line dopant of said source line that diffuses from said source line into said channel region alters a threshold voltage of said flash memory cell or reduces short channel effects of said flash memory cell.
- 12. The flash memory cell of claim 11, wherein said source line dopant and said channel dopant are comprised of boron when said drain dopant is an n-type dopant.
- 13. The flash memory cell of claim 11, wherein said implantation of said channel dopant is not performed such that said concentration of said channel dopant in said semiconductor substrate from implantation is substantially zero.
- 14. The flash memory cell of claim 11, wherein said semiconductor substrate is heated such that said source line dopant diffuses into said channel region.
- 15. The flash memory cell of claim 11, wherein said source line dopant is implanted at an energy of from about 10 keV to about 40 keV with a dosage of from about 1×1013 atoms/cm2 to about 5×1014 atoms/cm2.
- 16. The flash memory cell of claim 11, wherein said drain dopant is implanted at an energy of from about 30 keV to about 60 keV with a dosage of from about 5×1013 atoms/cm2 to about 5×1015 atoms/cm2.
- 17. The flash memory cell of claim 11, further comprising a first poly layer disposed on a tunnel oxide, an ONO multi-layer dielectric over said first poly layer, and a second poly layer over the ONO multi-layer dielectric.
- 18. The flash memory cell of claim 11, further comprising an ONO charge trapping layer, and a poly layer over the ONO charge trapping layer.
- 19. The flash memory cell of claim 11, further comprising:
a source region formed by implanting a source region dopant having a conductivity type that is same as the second conductivity type of said drain dopant.
Parent Case Info
[0001] This patent application is a continuation-in-part of an earlier filed copending patent application with Ser. No. 09/699,711 filed on Oct. 30, 2000, for which priority is claimed. This earlier filed copending patent application with Ser. No. 09/699,711 is in its entirety incorporated herewith by reference.
[0002] In addition, this patent application claims priority from the provisional patent application with Ser. No. 60/291,859 filed on May 18, 2001 and with the same title and inventorship herewith. The provisional patent application with Serial No. 60/291,859 is in its entirety incorporated herewith by reference.
Provisional Applications (1)
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Number |
Date |
Country |
|
60291859 |
May 2001 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09699711 |
Oct 2000 |
US |
Child |
10012666 |
Oct 2001 |
US |