Browse Prior Art Database

REWORK PROCEDURE FOR DEFECTIVE PtSi FORMATION

IP.com Disclosure Number: IPCOM000043197D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Baran, EF: AUTHOR [+2]

Abstract

A chemical process has been developed for removing defective platinum silicide (PtSi) from semiconductor wafers, permitting reclamation. In the process, a SiO2 passivation layer is removed with buffered HF, the PtSi removed with aqua regia, and a byproduct hydrated SiO2 layer removed with buffered HF. During PtSi formation, the Si diffuses toward the PtSi surface. At elevated processing temperatures, a SiO2 passivation layer forms. This layer prevents the removal of the defective PtSi and must be removed for the rework procedure to succeed. This layer is removed by immersing the wafers in 15:1:4 NH4F:HF:H2O (buffered HF) for a suitable time. The SiO2 removal rate is about 10 ˜/sec. Outside the contact region a layer of silicon nitride protects the wafer surface.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

REWORK PROCEDURE FOR DEFECTIVE PtSi FORMATION

A chemical process has been developed for removing defective platinum silicide (PtSi) from semiconductor wafers, permitting reclamation. In the process, a SiO2 passivation layer is removed with buffered HF, the PtSi removed with aqua regia, and a byproduct hydrated SiO2 layer removed with buffered HF. During PtSi formation, the Si diffuses toward the PtSi surface. At elevated processing temperatures, a SiO2 passivation layer forms. This layer prevents the removal of the defective PtSi and must be removed for the rework procedure to succeed. This layer is removed by immersing the wafers in 15:1:4 NH4F:HF:H2O (buffered HF) for a suitable time. The SiO2 removal rate is about 10 ~/sec. Outside the contact region a layer of silicon nitride protects the wafer surface. The defective PtSi is then removed using 1:2:1 HNO3:HCl:H2O at 60OEC for 20 minutes. The etch products are soluble chloroplatinic acid and insoluble hydrated SiO2 . The hydrated SiO2 is removed by immersing in 15:1:4 buffered HF for 15-30 seconds. The wafers can then be sputter cleaned, if necessary, and Pt redeposited either by evaporation at substrate temperatures of less than 340OEC or by room temperature sputtering.

1