Browse Prior Art Database

Dynamic SCR Memory with Poly Si Diode

IP.com Disclosure Number: IPCOM000076881D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Doo, VY: AUTHOR [+3]

Abstract

This cell (Fig. 1) consists of a silicon-controlled rectifier (SCR) device 10 and a diode 12, and can be readily implemented, as shown in Fig. 2, to form a monolithic random-access memory.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Dynamic SCR Memory with Poly Si Diode

This cell (Fig. 1) consists of a silicon-controlled rectifier (SCR) device 10 and a diode 12, and can be readily implemented, as shown in Fig. 2, to form a monolithic random-access memory.

The implementation essentially utilizes a stacking polysilicon diode on top of an SCR device in the same isolation well or pocket. Thus, the isolation well can be made somewhat smaller than other known techniques, such as, (1) a SCR device with lateral PNP and a PN junction diode in two separately isolated wells, or (2) a stacking SCR device and a PN junction diode in two separately isolated wells, because the area normally required for an N diffusion (the cathode of the PN junction) is eliminated. Further, implementing the diode in the stacking polysilicon layer eliminates unwanted NPN transistors so as to liberalize design constraints.

Polysilicon films can be deposited on the SiO(2) layers to a desired dopant level and film thickness. Both vertical and lateral junction planar transistors are obtainable by using conventional mask-diffusion techniques, and no additional processes in the photolithographic and diffusion steps are necessary, because the processes are incorporated into the emitter diffusion step. Lateral polysilicon diodes possess low capacitance and relatively high-forward resistance. However, the forward resistance of vertical polysilicon diodes are a magnitude of order lower than in a conventional lateral junction diode.

The device comprises a P type substrate 16 into which is formed an N+ collector region 18. Isolation regions 20 and 22 f...