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Source/Drain Personalization of High Density CMOS Read-Only Store

IP.com Disclosure Number: IPCOM000060475D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Oppold, JH: AUTHOR [+2]

Abstract

This read-only storage (ROS) array personalization technique enables programming of data into the ROS array late in its processing by personalization of block masks normally used in the complementary metal oxide semiconductor (CMOS) process. Normally, P-channel devices are protected from the implantation ion beam during N-channel doping and, conversely, N-channel devices are protected from the ion implantation beam during P-channel doping by these block masks. In a P-channel ROS array, personalizing the block mask to protect portions of the source- drain regions of selected P-channel transistors during the P-channel doping implantation leaves those transistors incomplete, thus becoming permanently stored "ones" in the ROS array. All other P-channel transistors in the array are complete and become "zeros".

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Source/Drain Personalization of High Density CMOS Read-Only Store

This read-only storage (ROS) array personalization technique enables programming of data into the ROS array late in its processing by personalization of block masks normally used in the complementary metal oxide semiconductor (CMOS) process. Normally, P-channel devices are protected from the implantation ion beam during N-channel doping and, conversely, N-channel devices are protected from the ion implantation beam during P-channel doping by these block masks. In a P-channel ROS array, personalizing the block mask to protect portions of the source- drain regions of selected P-channel transistors during the P-channel doping implantation leaves those transistors incomplete, thus becoming permanently stored "ones" in the ROS array. All other P-channel transistors in the array are complete and become "zeros". A ROS array comprised of N-channel devices may be programmed by personalizing the block mask used during N-channel implantation. Referring to the figure, a ROS array is fabricated by providing a plurality of device regions 10, defined by recessed oxide, for all potential memory devices including source regions S, drain regions D and channel regions C. A conductive access or word line 12 is provided over all of the the channel regions C. With the block mask personalized to result in photoresist being left in region 14, normal self- aligned channel doping during ion implantation is prevented in the...