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Profile Determination in N+ Diffused Regions

IP.com Disclosure Number: IPCOM000087562D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Briska, M: AUTHOR [+2]

Abstract

A wafer piece with As or P diffusion is activated by neutrons in a nuclear reactor. Above the activated wafer a thin plate of optical glass is arranged and adjusted at a distance of several mum. The spot to be analyzed is radiated by means of a pulsed laser beam, whereby a layer having a thickness of several hundred Angstroms evaporates. The vapor condenses in the form of a spot on the glass plate above.

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Profile Determination in N+ Diffused Regions

A wafer piece with As or P diffusion is activated by neutrons in a nuclear reactor. Above the activated wafer a thin plate of optical glass is arranged and adjusted at a distance of several mum. The spot to be analyzed is radiated by means of a pulsed laser beam, whereby a layer having a thickness of several hundred Angstroms evaporates. The vapor condenses in the form of a spot on the glass plate above.

After each pulse, the plate is advanced by several mm in such a manner that the doping profile is represented by a row and an array of radioactive spots. Absolute concentration determination is obtained by measuring the radioactivity of the individual spots. The lowest measurable value is 5.10/16/ atoms/cm/3/. The radioactivity is preferably measured by radiography (P-32 isotope) or by means of a solid-state detector.

This rapid and absolute measuring method permits measuring the vaporized spots belonging to layers arranged in the wafer several mum below the surface, thus ensuring particularly accurate results.

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