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Corrugated Capacitor Structure and Process

IP.com Disclosure Number: IPCOM000039900D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Davis, A: AUTHOR [+2]

Abstract

Sidewall spacer technology is used to create a corrugated deep trench capacitor comprised of two concentric, cylindrical trenches in the example described. The figure is comprised of cross-sections (a),(b),(c),(d) and (e) showing a progression of processing stages in making the corrugated capacitor structure. Photo processing is first used to define and etch an opening in silicon dioxide (SiO2) layer 2, as shown in cross-section (a). By the use of a directional silicon etch, the underlying silicon substrate 4 is etched to an arbitrary depth. To illustrate practical dimensions for the structure by this process, the opening in layer 2 may be 0.5 micron. Layer 2 thickness is then 200 nm and the depth of the etched hole in substrate 4 is an additional 300 nm.

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Corrugated Capacitor Structure and Process

Sidewall spacer technology is used to create a corrugated deep trench capacitor comprised of two concentric, cylindrical trenches in the example described. The figure is comprised of cross-sections (a),(b),(c),(d) and (e) showing a progression of processing stages in making the corrugated capacitor structure. Photo processing is first used to define and etch an opening in silicon dioxide (SiO2) layer 2, as shown in cross-section (a). By the use of a directional silicon etch, the underlying silicon substrate 4 is etched to an arbitrary depth. To illustrate practical dimensions for the structure by this process, the opening in layer 2 may be 0.5 micron. Layer 2 thickness is then 200 nm and the depth of the etched hole in substrate 4 is an additional 300 nm. A 100 nm thick conformal polysilicon layer 6 is applied, as shown in cross-section (b). To achieve the structure shown in (c), sidewall spacer technology is applied: a 100 nm film of SiO2 is conformally deposited and a directional, selective etch is used to remove all of the SiO2 except for the sidewall coatings 8. Another 100 nm of conformal polysilicon film 10 is deposited, as shown in cross-section (d). Concentric deep trenches, shown in cross-section (e), are achieved by performing a directional, selective etch for silicon. The initial SiO2 layer 2 and the sidewall SiO2 8 provide the masking. The only remaining polysilicon is represented by the small regions of poly...