Browse Prior Art Database

Fine-Pitch Solder Bump Formation by Electroplating

IP.com Disclosure Number: IPCOM000106302D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Kan, Y: AUTHOR [+4]

Abstract

Disclosed is a process for forming fine-pitch solder bumps on semiconductor devices by electroplating and ion beam milling.

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

Fine-Pitch Solder Bump Formation by Electroplating

      Disclosed is a process for forming fine-pitch solder bumps on
semiconductor devices by electroplating and ion beam milling.

      The current technique to form solder bumps by evaporation of
solder through a metal mask cannot be applied to future devices
requiring fine pitch I/O pads due to the restriction of metal mask
hole size limitation.

The proposed process is as follows:

o   Deposit a pad-limited metal layer on the entire surface of a chip

o   Apply a photoresist layer on the metal layer

o   Pattern the resist layer to coat only those regions of the metal
    layer where pads are to be formed

o   Etch away, by ion beam milling, those portions of the metal layer
    not coated with the resist to form metal pads

o   Strip the resist

o   Deposit aluminum on the entire surface of the chip to
    electrically connect all the pads in common

o   Apply photoresit on the aluminum layer

o   Pattern the resist layer to expose only those portions of the
    aluminum layer corresponding to the metal pads

o   Etch the aluminum layer to expose the pads

o   Deposit solder onto the exposed pads by electroplating with the
    aluminum layer being used as a common electrode

o   Strip the resist

o   Etch away the aluminum layer, and

o   Reflow the deposited solder to form solder bumps