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Browse Prior Art Database

Formation of Submicron Grooves in Silicon

IP.com Disclosure Number: IPCOM000047579D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Riseman, J: AUTHOR

Abstract

This article describes methods for forming narrow, such as submicrometer, dimensioned mask openings on a semiconductor body. Two insulator materials having different etching characteristics are used. One method involves depositing a P+ doped polysilicon layer 10 upon a silicon substrate 12. Layer 14 of silicon nitride (Si3N4) and layer 15 of silicon dioxide (SiO2) are formed over layer 10. Then using lithography and etching techniques portions of layers 14, 15 are removed to produce the Fig. 1 structure. A Si3N4 sidewall 16 is grown by a blanket deposition followed by anisotropic reaction ion etching to form a 200- to 300-nanometer layer 18 of silicon dioxide, as seen in Fig. 2. The exposed silicon is thermally oxidized. The silicon nitride sidewall layer 16 is removed by either chemical or plasma etching, as shown in Fig.

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Formation of Submicron Grooves in Silicon

This article describes methods for forming narrow, such as submicrometer, dimensioned mask openings on a semiconductor body. Two insulator materials having different etching characteristics are used. One method involves depositing a P+ doped polysilicon layer 10 upon a silicon substrate 12. Layer 14 of silicon nitride (Si3N4) and layer 15 of silicon dioxide (SiO2) are formed over layer 10. Then using lithography and etching techniques portions of layers 14, 15 are removed to produce the Fig. 1 structure. A Si3N4 sidewall 16 is grown by a blanket deposition followed by anisotropic reaction ion etching to form a 200- to 300-nanometer layer 18 of silicon dioxide, as seen in Fig. 2. The exposed silicon is thermally oxidized. The silicon nitride sidewall layer 16 is removed by either chemical or plasma etching, as shown in Fig. 3. The silicon dioxide layers 15, 18 remaining are essentially a mask. One can now ion implant through the openings, use the mask to reactive ion etching through the polysilicon layer 10 and into the silicon 12, or thermally nitride the polysilicon layer 10 to convert this mask into its negative, after removing the silicon dioxide layers 15, 18. By using the mask 15, 18 and reactive ion etching through the polysilicon layer 10, the Fig. 4 structure is obtained. The Fig. 3 structure can be used to form a bipolar device by boron implanting into the silicon through the mask openings to form regions
20. The silicon dioxide and silicon nitride layers are removed and the polysilicon layer partially oxidized to form layer 22. An N+ dopant is implanted into the polysilicon where the emitter is desired and diffused into the silicon to form the emitter region 24. Prior to the N+ doping a heat treatment had formed extrinsic base 26 and intrinsic base 28 by outdiffusion of P from the polysilicon layer 10, as seen in Fig. 5. Another bipolar transistor application of the Fig. 3 structure is as fol...