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Temperature-Compensated Isolated Buried Reference Zener Diode

IP.com Disclosure Number: IPCOM000038798D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Ward, WA: AUTHOR

Abstract

A device structure is described which adds temperature stability to a noise-immune, on-chip reference voltage device, e.g., the one described in the IBMM Technical Disclosure Bulletin , 27, 1782-3 (August 1984). This temperature stability is achieved by adding back-to-back diodes which have equal and opposite temperature coefficients within the device structure . Fig. 1 shows the new structure which is similar to much of the structure of the reference. This new structure is comprised of an N-type epitaxial silicon (EPI) 2 grown on P-type substrate silicon 4, with top and bottom isolation P+regions 6, a P base region 8, with an N+ contact 10 to a P+ diffusion 12, above a buried N+ sub-collector 14. An N+ reach-through diffusion 16 makes contact to the sub-collector 14.

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Temperature-Compensated Isolated Buried Reference Zener Diode

A device structure is described which adds temperature stability to a noise- immune, on-chip reference voltage device, e.g., the one described in the IBMM Technical Disclosure Bulletin , 27, 1782-3 (August 1984). This temperature stability is achieved by adding back-to-back diodes which have equal and opposite temperature coefficients within the device structure . Fig. 1 shows the new structure which is similar to much of the structure of the reference. This new structure is comprised of an N-type epitaxial silicon (EPI) 2 grown on P-type substrate silicon 4, with top and bottom isolation P+regions 6, a P base region 8, with an N+ contact 10 to a P+ diffusion 12, above a buried N+ sub-collector 14. An N+ reach-through diffusion 16 makes contact to the sub-collector 14. Metal 18, through a via hole in insulator layer 20, completes the con nection to the EPI layer 2. Metal 22 is the cathode contact. Fig. 2 is the equivalent circuit of the new device thus created. The diodes shown are the result of interfaces of the two doped regions of Fig. 1 given on either side of the diodes in Fig. 2. For instance, surface Zener diode SZ is the result of the interface of region 10 with region 8. The buried Zener diode BZ has a lower threshold than does surface Zener diode SZ, thus only BZ will be conducting under normal use conditions. Since the anode of BZ is isolated from the substrate, this device provides noise im...