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Method to prevent underfill wicking during semiconductor packaging

IP.com Disclosure Number: IPCOM000243969D
Publication Date: 2015-Nov-02
Document File: 3 page(s) / 87K

Publishing Venue

The IP.com Prior Art Database

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 69% of the total text.

Page 01 of 3

Title

Method to prevent underfill wicking during semiconductor packaging

Abstract

Disclosed is a process to prevent Underfilling (UF) wicking on the backside of the first Silicon (Si) die during semiconductor packaging. The core concept is to protect the backside of the thin bottom die by patterning a sacrificial layer on it.

Problem

Underfilling (UF) wicking on the backs of large and thin dies for three-dimensional (3D) stacking is a major area of concern during semiconductor packaging. This UF wicking on the backside of bottom die (thin die with through Silicon vias (TSV)) prevents stacking on second tier die of the same size, and is larger than the bottom die or has an overhanging design.

Existing solutions use a film during UF process and then remove this film through a mechanical process. During this removal, some UF wicks to the back surface of the bottom die, which is unacceptable for this application.

Another option is to heat the UF sidewalls using specially designed heaters; however, this application is limited to 100um thick Silicon (Si). The Si target thickness is 50um.

A effective process is needed to prevent this UF wicking.

Figure 1: Illustration of the problem


Page 02 of 3

Figure 2: Prior art: Undesirable UF wicking during removal of protective film

Solution/Novel Contribution

The novel contribution is a process to prevent UF wicking on the backside of the first Si die. The core concept is to protect the backside of thin bottom die by patterning...