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US4745086A Removable sidewall spacer for lightly doped drain formation using one mask level and differential oxidation 失效
用于轻掺杂漏极形成的可拆卸侧壁间隔,使用一个掩模级和差示氧化

Removable sidewall spacer for lightly doped drain formation using one
mask level and differential oxidation
摘要:
A method of using removable sidewall spacers to minimize the need for mask levels in forming lightly doped drains (LDDs) in the formation of CMOS integrated circuits. Aluminum or chemical vapor deposition (CVD) metals such as tungsten are suitable materials to form removable sidewall spacers which exist around CMOS gates during heavily doped source/drain region implants. Other materials such as CVD polysilicon may also be useful for the sidewall spacers. The sidewall spacers are removed before implantation of the lightly doped drain regions around the gates. This implanation sequence is exactly the reverse of what is currently practiced for lightly doped drain formation. The invention also includes the use of a differential oxide layer. A second set of disposable sidewall spacers or the use of permanent sidewall spacers form optional embodiments.
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