Browse Prior Art Database

Fabrication of Field Effect Transistors

IP.com Disclosure Number: IPCOM000095171D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Lehman, HS: AUTHOR [+3]

Abstract

This method fabricates field effect transistors. The method is especially adaptable for producing both depletion, normally on, and enhancement, normally off, mode field effect transistors in the same silicon wafer.

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 58% of the total text.

Page 1 of 2

Fabrication of Field Effect Transistors

This method fabricates field effect transistors. The method is especially adaptable for producing both depletion, normally on, and enhancement, normally off, mode field effect transistors in the same silicon wafer.

In the formation of the field effect transistor of drawing A, SiO(2) layer 10 is grown on the surface of relatively low-resistivity P-type wafer 11. Holes are etched in selected areas of film 10. Thus, N-type source and drain regions 12 and 13 are created by diffusing N-type impurity atoms through the holes using layer 10 as a mask. Metal terminals or electrodes 14... 16 are deposited by evaporation. If a thin N-type inversion layer or channel is created between the N- type regions 12 and 13, the effective thickness of the channel can be controlled or modulated. Such is effected by the bias applied to the gate electrode thus providing control of current now between the source and drain regions. Such a device is a normally on device. It can be turned off by applying a negative signal of the proper magnitude to the gate electrode. This is a depletion mode field effect device.

For some applications, a normally off or enhancement mode field effect device is employed. In this case, the device does not contain the N-type inversion channel in its normal condition without the application of any kind of potential to the gate electrode.

A normally on device capable of carrying a greater channel current can be made from a n...