Browse Prior Art Database

Tin Deposition Rate Control

IP.com Disclosure Number: IPCOM000059983D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Lupul, FT: AUTHOR [+3]

Abstract

In the fabrication of contact pads for semiconductor integrated circuit devices, it is desirable to accurately control the deposition of tin used in the contact pad metallurgy. The described monitoring apparatus uses sensor crystals to permit the precise control of tin content or the thickness of a tin layer on the contact pads. Prior deposition processes used lead-tin pellets evaporated from a single source cup to produce a contact pad of the desired height and having a specified tin content. A predetermined amount of tin was completely evaporated from the source cup during the deposition step. If the process were interrupted, for example, by a failure of the source cup, it was difficult to determine the exact amount of tin required to complete the evaporation.

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Tin Deposition Rate Control

In the fabrication of contact pads for semiconductor integrated circuit devices, it is desirable to accurately control the deposition of tin used in the contact pad metallurgy. The described monitoring apparatus uses sensor crystals to permit the precise control of tin content or the thickness of a tin layer on the contact pads. Prior deposition processes used lead-tin pellets evaporated from a single source cup to produce a contact pad of the desired height and having a specified tin content. A predetermined amount of tin was completely evaporated from the source cup during the deposition step. If the process were interrupted, for example, by a failure of the source cup, it was difficult to determine the exact amount of tin required to complete the evaporation. The present apparatus, shown in the figure, includes a conventional vacuum deposition chamber 1 including a wafer dome 2 and a source cup 3 for holding the material to be deposited. Also included is an infrared temperature monitor 4 for conventional end-point detection of lead ddeposition. A dual crystal sensor head 5, mounted in close proximity to the wafer dome 2, is used to monitor and control the rate of tin deposition as well as the final thickness of the tin layer. A shutter 6, mounted in front of the crystal sensor head 5, protects the sensor during lead deposition. The shutter 6 is opened during tin deposition. If one sensor 5 fails, the second sensor continues to provi...