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US 6,207,493 B1Granted
Formation of out-diffused bitline by laser anneal
AssigneeInternational Business Machines Corporation
InventorsToshiharu Furukawa, Mark C. Hakey, Steven J. Holmes, David V. Horak, Thomas S. Kanarsky
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Abstract
The present invention provides methods of forming an out-diffused bitline in a semiconductor substrate by utilizing a laser annealing step wherein the dopant material in the trench region is out-diffused into the semiconductor substrate. The out-diffused bitline can also be formed utilizing an ion implantation step.
Claims21
A method of forming a bitline buried below the transfer gate of a vertical semiconductor memory cell, said method comprising the steps of:
- (a) forming at least one trench region in a semiconductor substrate;
- (b) forming a conformal layer in said at least one trench region and on exposed surfaces of said semiconductor substrate, wherein said conformal layer comprises a dopant source material which comprises a dopant carrying material and a dopant element which is capable of being released upon exposure to laser light;
- (c) depositing a recessable material on the structure provided in step (b);
- (d) recessing some, but not all, of said recessable material and said dopant source material leaving a masked region of said recessable material on a layer of said dopant source material in said at least one trench region;
- (e) stripping the recessable material from said trench;
- (f) laser annealing the structure provided in step (e) to out-diffuse the dopant element from the recessed dopant source material into said semiconductor substrate;
- (g) stripping any remaining recessed source material from said at least one trench region;
- and
- (h) etching the out-diffused region under conditions effective to form a buried bitline in said semiconductor substrate.
6 more elements
Dependencies are inferred from the claim text.