Browse Prior Art Database

Photoresist Technique to Deposit High Conductance Metals on Active Areas of Semiconductor Devices

IP.com Disclosure Number: IPCOM000092706D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 54K

Publishing Venue

IBM

Related People

Fink, MS: AUTHOR [+2]

Abstract

The realization of high-speed semiconductor devices has established the need for reducing the junction size. A typical semiconductor device structure requires the emitter region to be a very narrow and elongated structure. Further, it is e ssential that base contacts which run parallel to the emitter contacts on both elongated side s should be positioned as close to the emitter contacts as possible. Fabrication of these devices is becoming increasingly more difficult because of the limitations of pre sent photoengraving technology. He re po sitive and negative photore sist technique s are employed so that metals of high electric conductivity can be deposited on the desired areas. The deposited metal is then used as a resist for the removal of excess base metal.

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 52% of the total text.

Page 1 of 3

Photoresist Technique to Deposit High Conductance Metals on Active Areas of Semiconductor Devices

The realization of high-speed semiconductor devices has established the need for reducing the junction size. A typical semiconductor device structure requires the emitter region to be a very narrow and elongated structure. Further, it is e ssential that base contacts which run parallel to the emitter contacts on both elongated side s should be positioned as close to the emitter contacts as possible. Fabrication of these devices is becoming increasingly more difficult because of the limitations of pre sent photoengraving technology. He re po sitive and negative photore sist technique s are employed so that metals of high electric conductivity can be deposited on the desired areas. The deposited metal is then used as a resist for the removal of excess base metal.

There are two general processes which can be used. First, a noble metal, such as platinum, is deposited by any conventional vacuum procedure onto the surface of a semiconductor device. The latter is coated with silicon dioxide layer 1 having openings in it to the elements of the underlying semiconductor device. The platinum is then alloyed with the silicon by raising the temperature of the coated structure to approximately 500 degrees C. Such forms the alloy layers 2 of platinum silicide on the active device areas. The excess platinum is then etched from layer 1 with aqua regia. Layers 2 are not significantly attacked by aqua regia. A second metal layer 3, such as molybdenum, nickel, or aluminum, is deposited over the wafer by any conventional vacuum procedure. Layer 3 is etched using a conventional positive photoresist in the pattern shown in drawing
A. The metal is removed from between the stripes except in the areas of the stubby finger contacts 4 to the underlying semiconductor device through layers 2.

Photoresist 5 which still covers layer 3is re-exposed to mercury light...