Browse Prior Art Database

Complementary FET Devices Having Composite Gate Dielectric and Composite Gate Electrode Structures

IP.com Disclosure Number: IPCOM000079938D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Barile, CA: AUTHOR [+8]

Abstract

Prior complementary field-effect transistor (FET) devices employ aluminum-silicon nitride-silicon oxide gate structures. Such gate structures are subject to three disadvantages, i.e., the P-channel FET exhibits high-threshold voltage, the N-channel FET exhibits low-threshold voltage, and both P and N-channel FETs are subject to significant threshold voltage shift in response to temperature-bias stressing.

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 64% of the total text.

Page 1 of 2

Complementary FET Devices Having Composite Gate Dielectric and Composite Gate Electrode Structures

Prior complementary field-effect transistor (FET) devices employ aluminum- silicon nitride-silicon oxide gate structures. Such gate structures are subject to three disadvantages, i.e., the P-channel FET exhibits high-threshold voltage, the N-channel FET exhibits low-threshold voltage, and both P and N-channel FETs are subject to significant threshold voltage shift in response to temperature-bias stressing.

The foregoing disadvantages are avoided by employing an aluminum, P- doped polycrystalline silicon, oxygen annealed silicon nitride, thermal oxide gate structure. A P-doped polycrystalline silicon gate has a more positive gate-to- substrate work function than an aluminum gate. Therefore, with everything else equal, N-channel FETs with an aluminum silicon gate have a substantially higher threshold voltage than N-channel aluminum gate FETs. The corresponding P- channel devices have a much lower threshold voltage than aluminum gate P- channel FETs. The oxygen annealing of the silicon nitride layer improves the threshold voltage stability of both the P and N-channel FETs.

The complementary FET devices shown in the drawing are fabricated as follows: P diffusions 1 and 2 are made in N substrate 3, N diffusions 4 and 5 are made in P pocket 6 formed within substrate 3, and thick oxide 7 is formed in a conventional manner. The thick oxide is etched away in the device chann...