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Silicon Oxynitride Masks for Solid State Diffusion

IP.com Disclosure Number: IPCOM000082988D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bratter, RL: AUTHOR

Abstract

In diffusion from the solid state, it is customary to use a doped silicon dioxide source such as arsenic doped glass. After the diffusion is completed, the doped glass source is removed.

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Silicon Oxynitride Masks for Solid State Diffusion

In diffusion from the solid state, it is customary to use a doped silicon dioxide source such as arsenic doped glass. After the diffusion is completed, the doped glass source is removed.

In large-scale integration, arsenicdoped emitters may be diffused from a solid source of arsenic doped silicon dioxide. One conventional method for the formation of such emitters involves, utilizing a composite mask comprising a lower layer of silicon dioxide and an upper layer of silicon nitride, in which openings defining the emitters are formed. Then, the above described arsenic solid source diffusion is carried out in these openings to form the emitters.

At this stage, the arsenicdoped silicon dioxide source must be removed from the emitter openings, in order that the conductive emitter contacts may be subsequently formed in the openings. With a composite silicon dioxide/silicon nitride mask described above, the etchant used in removing the doped source also attacks the bottom silicon dioxide layer in the mask, producing undercutting beneath the top silicon nitride layer.

The present approach avoids this problem by using a silicon oxynitride mask for the emitter diffusion in place of the composite mask. In accordance with Figs. 1 3, silicon oxynitride mask 10 is formed over silicon substrate 11 which may conveniently be a P-type base region. A solid source 12, comprising arsenic doped silicon dioxide, is deposited in emitter...