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Self Aligned Silicon Structures Using Laser Annealing

IP.com Disclosure Number: IPCOM000052813D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Fowler, AB: AUTHOR [+3]

Abstract

Semiconductor structures may be fabricated by laser annealing of amorphous silicon layers on heavily doped substrate regions whereby the amorphous silicon layer will recrystallize selectively where the substrate is heavily doped.

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Self Aligned Silicon Structures Using Laser Annealing

Semiconductor structures may be fabricated by laser annealing of amorphous silicon layers on heavily doped substrate regions whereby the amorphous silicon layer will recrystallize selectively where the substrate is heavily doped.

The technique is illustrated with respect to Figs. 1 and 2. The silicon film is recrystallized over heavily doped diffusions. Then the sample is etched in pyrocatechol which will etch the crystalline silicon selectively on the <100> surface, leaving the amorphous material.

The structure of Fig. 1 in cross section is produced. A solid and a dashed line are used to denote the boundary of the amorphous film. For high energy the solid line obtains. For low energy the dashed line obtains.

The amorphous films may further be doped and act as diffusion sources. For instance, if the amorphous film were n doped and the substrate were p-type after further annealing, the structure of Fig. 2 will result.

The structure could still further be oxidized at the same time. The structure of Fig. 2 is a cross section of a self-aligned n-p-n bipolar transistor. The base width is set by the overlap of the laser recrystallized structure over the original diffusion and by the annealing and drive-in.

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