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Insulating Lateral Surfaces on Semiconductor Chips

IP.com Disclosure Number: IPCOM000094755D
Original Publication Date: 1965-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Lehman, HS: AUTHOR [+3]

Abstract

These semiconductor chips have their lateral surfaces coated with an insulating film. The film prevents the lateral edge of a chip device shorting through solder on a circuit board when attached to it. The film is applied at temperatures below the flow point of any metallurgy used in fabricating the chip devices.

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Insulating Lateral Surfaces on Semiconductor Chips

These semiconductor chips have their lateral surfaces coated with an insulating film. The film prevents the lateral edge of a chip device shorting through solder on a circuit board when attached to it. The film is applied at temperatures below the flow point of any metallurgy used in fabricating the chip devices.

Semiconductor wafer 10 has emitter junctions 12, base junctions 14 and contact metallurgy 16. Grooves 18 are cut along the surface of wafer 10. Metallurgy 16 is coated with protecting film 20, typically wax. Lateral surfaces 22 of wafer 10 are coated with an insulating film by either a metal halide reaction or a spray coating operation.

The hydrolysis of metal chlorides develops a vapor phase which deposits an adherent oxide film on the lateral surfaces. In one form, titanium chloride and water react to form titanium dioxide. This, when deposited on lateral surfaces of wafer 22, provides excellent surface coverage with good electrical insulating qualities and chemical durability. The titanium chloride reaction process is as follows: TiCl(4) + 2H(2)O + ----> TiO(2) + 4HCl. Typically, the reaction is carried out at 200 degrees C temperature for two minutes. The resulting film is of the order of 3000 angstroms. The reaction temperature is considerably less than the flow point of metallurgy 16. Other materials suitable in similar reactions are SiCl(4) and AlCl(3).

As an alternative, the lateral surfaces are...