Method for wet etching polysilicon

Details Method for wet etching polysilicon Method for wet etching polysilicon

1994-12-23

1996-05-21

Hearn, Brian E.

Fishing, trapping, and vermin destroying

1566621, 1566281, 1566301, 1566331, 1566541, 437247, H01L 21469

Patent

active

055189660

ABSTRACT:
A method is disclosed for the wet etching of polysilicon, which comprises the steps of: annealing a lamination structure of a doped polysilicon and an undoped polysilicon at a predetermined temperature for a predetermined period; and applying to the annealed lamination structure a chemical etchant comprising nitric acid, fluoric acid, acetic acid and deionized water with the volume ratio of nitric acid to acetic acid to fluoric acid to deionized water being 30:3:x:15+(1-x) wherein x is a real number ranging from 0.2 to 1.0, so as to remove the doped polysilicon film. Instead of fluoric acid, alcohol may be used in the chemical etchant without affecting the etching selectivity. This method is superior in performance with regard to selective etching between the undoped polysilicon and the doped polysilicon. Therefore, the doped polysilicon which is useful in many ways, for example, storage electrode, insertion layer and contact, can be etched in such a thickness as is needed, with the chemical etchant. Consequently, the present method is very useful in developing new semiconductor devices.

REFERENCES:
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patent: 4415383 (1983-11-01), Naem et al.
patent: 4554046 (1985-11-01), Taguchi et al.
patent: 4584055 (1986-04-01), Kayanuma et al.
patent: 4681657 (1987-07-01), Hwang et al.
patent: 5013675 (1991-05-01), Shen et al.

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