Method for etching and filling deep trenches
AssigneeShanghai Hua Hong NEC Electronics Co., Ltd.
InventorsXiaohua Cheng, Shengan Xiao
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Abstract
A method of etching and tilling deep trenches is disclosed, which includes: forming an ONO(oxide-nitride-oxide) sandwich layer on a semiconductor substrate; forming deep trenches by using top oxide of the sandwich layer as a stop layer; removing the top oxide and middle SiN of the sandwich layer; tilling the deep trenches with epitaxial film or polysilicon film; polishing the wafer to get a planarized surface by stopping at the surface of the bottom oxide layer; removing the bottom oxide layer.
Claims13
A method for etching and filling deep trenches, comprising the following steps in the sequence set forth:
- depositing an ONO layer on a substrate, the ONO layer comprising a bottom silicon oxide layer, a middle silicon nitride layer and a top silicon oxide layer;
- etching a deep trench in the substrate, further comprising:
- forming a shallow trench in the ONO layer by removing at least part of the top silicon oxide layer;
- etching in the shallow trench to form a deep trench by using a remaining part of the top silicon oxide layer as an etch stop layer;
- removing the top silicon oxide layer and the middle silicon nitride layer;
- filling the deep trench with epitaxial film and/or polysilicon film;
- planarizing surface of the deep trench by using the bottom silicon oxide layer as a stop layer;
- and
- removing the bottom silicon oxide layer.
Dependencies are inferred from the claim text.