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Technique for Analysis and Distribution of Autodoping in Epitaxial Films

IP.com Disclosure Number: IPCOM000085242D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Deines, JL: AUTHOR [+3]

Abstract

The present technique provides a fast, relative measure of the extent of autodoping in epitaxial films. The silicon wafer shown in Fig. 1 contains multiple five square Square N+ diffusions, e.g., arsenic. After the epitaxial deposition, an anodic etching technique is employed to disclose the autodoping extent and its distribution around the original diffusion.

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Technique for Analysis and Distribution of Autodoping in Epitaxial Films

The present technique provides a fast, relative measure of the extent of autodoping in epitaxial films. The silicon wafer shown in Fig. 1 contains multiple five square Square N+ diffusions, e.g., arsenic. After the epitaxial deposition, an anodic etching technique is employed to disclose the autodoping extent and its distribution around the original diffusion.

Fig. 1 shows an anodic cell 3 which is usable in this technique. The electrode 4 and container 5 are connected as the cathode of the cell. The back side of the wafer 6 which contains diffusions 7 is connected as the anode of the cell. The container contains a suitable electrode 8.

Data has shown that subcollector diffusions in the original wafer enhance the formation of pores (embryonic porous silicon) in the epitaxial film. The anodic etching technique is sensitive to changes in resistivity in the epitaxial layer. The higher the N dopant concentration at the epitaxial layer substrate interface, the heavier the pore formation.

The extent of autodoping can be mapped using optical or infrared TV microscopy methods. The larger and more dense the pore structure, the heavier the autodoping. The size and density of the pore structure will change as the extent of autodoping changes away from the (autodoping) diffusion, as shown in Fig. 2 by the dashed arrows.

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