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A METHOD OF MAKING ZENER DIODES AND ZENER TRIGGERED SCRs IN SUB-HALF MICRON TECHNOLOGY

IP.com Disclosure Number: IPCOM000007768D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-22
Document File: 2 page(s) / 77K

Publishing Venue

Motorola

Related People

Henry Choe: AUTHOR

Abstract

Zener Diodes' have been commonly used for ESD protection circuits. Traditional Zener imple- mentation can cause severe leakage due to surface conditions. Consequently, the I/O circuits can be very leaky under normal operation conditions and products will not meet specs. New method of mak- ing low leakage current Zeners and Zener Triggered SCRs (they are shown in Figure 1 and 2, respec- tively) was proposed.

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M-RO&A Technical Developments

8

A METHOD OF MAKING ZENER DIODES AND ZENER TRIGGERED SCRs IN SUB-HALF MICRON TECHNOLOGY

by Henry Choe

PURPOSE:

  Zener Diodes' have been commonly used for ESD protection circuits. Traditional Zener imple- mentation can cause severe leakage due to surface conditions. Consequently, the I/O circuits can be very leaky under normal operation conditions and products will not meet specs. New method of mak- ing low leakage current Zeners and Zener Triggered SCRs (they are shown in Figure 1 and 2, respec- tively) was proposed.

at the Zener areas. Nitride is used for salicide block. It also forms the sidewall spacers for the transistors on the chip. TEOS is needed as an etch stop for the subsequent Salicide Block (nitride) etch. TEOS also provides a buffer layer between the thermal oxide and the salicide block nitride to reduce the impact of possible charge trapping at the Nitride/Oxide inter- face. The process flow is shown in Figure 3.

SUMMARY:

  New method of making low leakage current Zeners and Zener Triggered SCR were achieved using a thermally grown oxide at the Si-SiO, interface.

PROPOSAL:

  Since the Zener diodes, Figure 2, implemented in our products are lateral devices, their characteris- tics depend on the implant doses/energies and con- ditions of the Si-SiO, interface. The idea here is to avoid having dangling bonds or trapped oxide charges at the Si-SiO, interface. Thermally grown oxide is necessary for a really "passivated" Si-SiO,...