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Method of Ensuring Temperature Uniformity in Radiation-Annealed Wafers

IP.com Disclosure Number: IPCOM000042652D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Hodgson, RT: AUTHOR [+2]

Abstract

This article relates generally to apparatus for annealing wafers and more particularly to support apparatus which eliminates temperature gradients during radiation annealing of semiconductor wafers. In known support arrangements, the edges of a wafer radiate more power than the central portions. A temperature gradient and occasional slip lines are noted. A wafer support and guard ring setup are shown in cross section in the above figure. In the figure, a silicon wafer 1 is supported on an oxide-covered silicon wafer 2 which has one inch larger diameter than wafer 1. An oxide-covered guard ring 3 which is cut from a silicon wafer of the same size as wafer 2 surrounds wafer 1.

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Method of Ensuring Temperature Uniformity in Radiation-Annealed Wafers

This article relates generally to apparatus for annealing wafers and more particularly to support apparatus which eliminates temperature gradients during radiation annealing of semiconductor wafers. In known support arrangements, the edges of a wafer radiate more power than the central portions. A temperature gradient and occasional slip lines are noted. A wafer support and guard ring setup are shown in cross section in the above figure. In the figure, a silicon wafer 1 is supported on an oxide-covered silicon wafer 2 which has one inch larger diameter than wafer 1. An oxide-covered guard ring 3 which is cut from a silicon wafer of the same size as wafer 2 surrounds wafer 1. Assuming that incoming radiation (6000 A) is uniform over the entire area of wafer 1 and guard ring 3, the absorption of light in guard ring 3 can be enhanced by a g/4 antireflective SiO2 film 4 (g/4 for 6000 A equals 1000 A thick) on the front face. Re-radiation from the back face at the edges can be cut down by a g/2 SiO2 film
5. (The re-radiation peak at 1500OEK is approximately 2 micrometers. A g/2 film of quartz would be 7500 A thick.) Wafer 2 is supported by quartz pins 6 within the annealing system. The reflection of incoming radiation can be changed from 30% to 6% in this way, and the emission coefficient of the holder can be changed from 0.74 to 0.68. This N40% change in the power balance counteracts the 10% chang...