Browse Prior Art Database

Contact via Etch Masks for Double Polysilicon Process

IP.com Disclosure Number: IPCOM000049284D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bergendahl, AS: AUTHOR

Abstract

This contact-etching process reduces the required number of contact etch masks from three to two in a single- or double-polysilicon semiconductor device process which includes buried polysilicon-to-substrate contacts. Over-sized, partially etched contact holes are formed for first-level polysilicon and substrate contacts at the time buried contact holes are being etched by under-sized mask images.

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Contact via Etch Masks for Double Polysilicon Process

This contact-etching process reduces the required number of contact etch masks from three to two in a single- or double-polysilicon semiconductor device process which includes buried polysilicon-to-substrate contacts. Over-sized, partially etched contact holes are formed for first-level polysilicon and substrate contacts at the time buried contact holes are being etched by under-sized mask images.

Fig. 1 shows a partially processed semiconductor device including silicon substrate 10 passivated with recessed-oxide 12 and including a dielectrically passivated first-level polysilicon electrode 14. Ml represents a photolithographic mask image used for buried contact hole 16 which is required to be formed prior to the deposition of a second polysilicon layer which will contact substrate 10. Normally, buried contact hole 16 would be etched through a thin gate oxide layer using a mask image size substantially equal to the size of the desired contact hole. Here, buried contact mask M1 is provided with an under-sized buried contact image D1 and over-sized contact images D2 and D3 positioned at points where contacts to first-level polysilicon and the substrate will be later formed. During the contact etching step sufficient etching is performed to remove the passivation oxide over electrode 14 and to etch about one-half of the recessed- oxide thickness, while the buried contact is over-etched to provide a contact hole 1...