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Lowering the Laser Formed Contact Resistance between Al and Si

IP.com Disclosure Number: IPCOM000082150D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

d'Heurle, FM: AUTHOR [+2]

Abstract

Recent work on the formation of laser connections between aluminum lines and N and P-doped silicon, indicate that connections can be made through an SiO(2) insulator. The resulting contacts tend to have resistances of 50 ohms, after thermal annealing. Although such connections are useful for redundancy purposes in present field-effect transmitter technology, it is desirable to reduce the resistance to approximately 1 ohm. Two approaches for producing laser connections with much lower contact resistance than heretofore are described in what follows:

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Lowering the Laser Formed Contact Resistance between Al and Si

Recent work on the formation of laser connections between aluminum lines and N and P-doped silicon, indicate that connections can be made through an SiO(2) insulator. The resulting contacts tend to have resistances of 50 ohms, after thermal annealing. Although such connections are useful for redundancy purposes in present field-effect transmitter technology, it is desirable to reduce the resistance to approximately 1 ohm. Two approaches for producing laser connections with much lower contact resistance than heretofore are described in what follows:

In prior art arrangements, a laser pulse or pulses of short duration are applied to a metal line which is disposed on an SiO(2) insulating layer. Both the metal and the insulation are deposited on a semiconductor substrate. The laser pulse or pulses penetrate through both the metal and the insulation layer, to form a connection with the underlying semiconductor material.

To provide a connection between the overlying metal and the semiconductor of relatively low resistance, a material which chemically reduces the SiO(2) layer upon application of a laser pulse or pulses can be provided. Specifically, a thin layer of magnesium evaporated onto the SiO(2) insulating layer prior to the deposition of a metal such as aluminum, rapidly reduces the SiO(2) upon localized heating. This provides an easy path for molten silicon to reach the aluminum, thereby facilitating...