Browse Prior Art Database

PROCESS FOR ETCHING TIWNx BARRIER FILM IN THE PRESENCE OF PB-SN SOLDER

IP.com Disclosure Number: IPCOM000009876D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-25
Document File: 1 page(s) / 62K

Publishing Venue

Motorola

Related People

Lakshmi N. Ramanathan: AUTHOR [+2]

Abstract

A flip chip interconnection system was developed using the following steps: I) sputtering a TiWNx barrier layer, (2) sputtering a Cu electroplating bus layer, (3) covering the whole wafer with photoresist, followed by development of photoresist to expose the bond pads, (4) electroplating a Cu stud on the sputtered Cu layer exposed over the bond pads, (5) electroplating Pb~Sn solder as an alloy (either eutectic or high-Pb), (6) stripping the photoresist, (7) selectively etching the Cu bus layer (in the presence of the Pb-Sn solder), (8) selectively stripping the TiWNx sputtered layer, and (9) reflowing the solder reflowed under appropriate conditions.

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MOTOROLA

Technical Developments

PROCESS FOR ETCHING TIWNx BARRIER FILM IN THE PRESENCE OF PB-SN SOLDER

Lakshmi N. Ramanathan and Doug Mitchell

A flip chip interconnection system was developed using the following steps: I) sputtering a TiWNx barrier layer, (2) sputtering a Cu electroplating bus layer, (3) covering the whole wafer with photoresist, followed by development of photoresist to expose the bond pads, (4) electroplating a Cu stud on the sputtered Cu layer exposed over the bond pads, (5) electroplating Pb~Sn solder as an alloy (either eutectic or high-Pb), (6) stripping the photoresist, (7) selectively etching the Cu bus layer (in the presence of the Pb-Sn solder), (8) selectively stripping the TiWNx sputtered layer, and (9) reflowing the solder reflowed under appropriate conditions.

An important step in the above process is the selective etching of the sputtered Cu (step 7) bus layer and the TiWNx barrier layer (step 8), in the presence of the Pb-Sn solder. A commercial etchant

(Metex FA and FB produced by Macdermide Corporation) was used for selectively etching the Cu bus layer in the presence of the Pb-Sn solder.

PROCESS CLAIM AND PROCEDURE

In this disclosure a process is outlined for selectively etching the TiWNx film, described in step 7 above, in the presence of Pb-Sn solders containing 63-97% Pb and 37-3% Sn by weight. The compostion of this etchant is as follows: 2-15% by volume of commercial 30% hydrogen peroxide, 0.5 -10% by volume of connnercial 30% annnoni...