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Complementary Bipolar Transistor Process using Seven Masking Steps

IP.com Disclosure Number: IPCOM000080080D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 161K

Publishing Venue

IBM

Related People

Abbas, SA: AUTHOR [+8]

Abstract

NPN and epi-base PNP bipolar transistors are formed in a monolithic structure using only seven masking steps. Isolation is obtained by a through-epi oxidation technique. Independent control of the bases and emitters of the NPN and PNP devices is achieved without process complexity.

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Complementary Bipolar Transistor Process using Seven Masking Steps

NPN and epi-base PNP bipolar transistors are formed in a monolithic structure using only seven masking steps. Isolation is obtained by a through-epi oxidation technique. Independent control of the bases and emitters of the NPN and PNP devices is achieved without process complexity.

The structure resulting at the conclusion of intermediate process steps are represented in Figs. 1-3. The final structure is shown in Fig. 4. Initial oxide is grown on P substrate 1. Photoresist is applied (first masking step) and N1+ subcollector regions 2 and 3 are defined. The subcollector areas are diffused and reoxidized. photoresist is applied (second masking step) and the P1+ regions 4, 5 and 6 are defined. The P1+ diffusions are made and the areas are reoxidized to yield the structure shown in Fig. 1.

The oxide region 7 is stripped and N epitaxial layer 8 of Fig. 2 is deposited. Successive layers comprising 500 angstroms of grown oxide 9, 500 angstroms of deposited silicon nitride 10, and 3000 angstroms of deposited pyrolytic oxide 11 are placed on epi 8. Photoresist is applied (third masking step) and the regions 12-18 of dielectric isolation are defined, and through-epi oxidation is performed to yield the structure shown in Fig. 2.

Photoresist is applied (fourth masking step) and the P2+ regions 19, 20 and 25 of Fig. 3 are defined. The P2+ diffusions are made and the areas are reoxidized.

The pyrolytic oxide,...