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Photolithographic Process to Personalize Integrated Circuits

IP.com Disclosure Number: IPCOM000076576D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brouillard, A: AUTHOR [+2]

Abstract

The purpose of the described process is to personalize integrated circuits, particularly as used in program-controlled memories. In this process, it is proposed to produce microholes by photolithographic techniques. The originality of the process lies mainly in that it permits cutoff of aluminum conductors on a semiconductor chip mounted on a ceramic substrate. The chip has previously received the appropriate aluminum pattern to achieve the desired electrical interconnections. No final passivation (quartz or glass) of the chip has been made. The following steps may be used: 1) Gold Deposition: in order to coat pins on the substrate and prevent them from being damaged during aluminum etching. 2) Wire bonding: gold wires are used to connect pads to the pins.

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Photolithographic Process to Personalize Integrated Circuits

The purpose of the described process is to personalize integrated circuits, particularly as used in program-controlled memories. In this process, it is proposed to produce microholes by photolithographic techniques. The originality of the process lies mainly in that it permits cutoff of aluminum conductors on a semiconductor chip mounted on a ceramic substrate. The chip has previously received the appropriate aluminum pattern to achieve the desired electrical interconnections. No final passivation (quartz or glass) of the chip has been made.

The following steps may be used:
1) Gold Deposition: in order to coat pins on the substrate and

prevent them from being damaged during aluminum etching.
2) Wire bonding: gold wires are used to connect pads to the pins.
3) Photoresist application: a positive photoresist, such as AZ

1350 H* is used to coat the chip by centrifugation.
4) Baking under free air.
5) Exposure: a hole-by-hole exposure may be performed either

manually or automatically; commercially available apparatus

may be satisfactorily used for this particular step.
6) Photoresist Development
7) Rinsing: in deionized water and drying.
8) Etching: for example using phosphoric, nitric and acetic acids,

plus water (16:1:1:2).
9) Photoresist removal using ethyl acetate.
10) Coating: a protective coating is then applied

to protect the chip.
11) Encapsulation to obtain a completed module. * Product of Shipley...