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Single Device Memory Cell Having a Transistor Metal Silicate Capacitor Dielectric and Ion Implanted Storage Node

IP.com Disclosure Number: IPCOM000050800D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Adler, E: AUTHOR [+3]

Abstract

This process for a single-device dynamic memory cell in double polysilicon MOSFET technology incorporates a transition metal silicate as the capacitor dielectric and includes a self aligned ion-implanted storage node through the use of lift-off processing.

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Single Device Memory Cell Having a Transistor Metal Silicate Capacitor Dielectric and Ion Implanted Storage Node

This process for a single-device dynamic memory cell in double polysilicon MOSFET technology incorporates a transition metal silicate as the capacitor dielectric and includes a self aligned ion-implanted storage node through the use of lift-off processing.

As shown in Fig. 1, the process begins with the growth of recessed oxide isolation regions 12 on semiconductor substrate 10 in order to delineate active device areas. A photolithographic lift-off process is used to define a lift-off mask 14 over all areas except those designated for storage capacitance nodes. About 200 angstroms of a transition metal silicide, TMxSiy, 16 is evaporated. Tantalum, yttrium and hafnium silicides are suitable materials for silicide layer 16. Following deposition of silicide 16, n-type ions 18, for n-channel active devices, are ion-implanted using lift-off mask 14 and overlying silicide layer 16 as an implant mask to provide n+ storage node predeposit 20 under portion 16' of the silicide. The lift-off mask is removed, and the wafer is cleaned. This is followed by an oxidation step in dry oxygen, which causes the silicide to be converted to a silicate, having a dielectric constant about 3 to 4 times that of thermal silicon dioxide. The oxidation process is continued until a desired thickness of silicon dioxide is grown in the remainder of the active area to act as a gate di...