IP Library › Granted Patent US 7,955,966
Granted Patent B2
US 7,955,966 · App. 12/543,811 · Granted Jun 7, 2011

Injection molded solder ball method

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 7,955,966
App. No.
12/543,811
Granted
Jun 7, 2011
Kind
B2
Abstract

Methods for making solder balls, which can be used to bump semiconductor wafers are disclosed. Methods for bumping semiconductor wafers with the solder balls are also disclosed. The solder balls can be made using an injection molded soldering (IMS) process.

Claims (16)

1. A method for forming a solder bump on a semiconductor wafer comprising:

providing a mold comprising at least one cavity;

filling said at least one cavity with a molten solder in a low oxygen environment;

reflowing the solder to form at least one solder ball as soon as a constraining effect of a solder fill head has passed the at least one cavity;

aligning the at least one cavity with at least one receiving pad;

heating to cause the at least one solder ball to flow from the at least one cavity to the at least one receiving pad in order to form at least one solder bump; and

removing the mold,

wherein the shape of the at least one cavity is pyramidal.

2. The method of claim 1 , wherein the molten solder comprises at least one material selected from the group consisting of Sn, Pb, SnPb, SnCu, SnAg, SnBi, SnAgCu, and SnAgCuBi.

3. The method of claim 1 , wherein the mold comprises at least one material selected from the group consisting of glass, silicon, metal, graphite, and polyimide.

4. The method of claim 1 , wherein the diameter of the cavity ranges from about 25 microns to about 500 microns.

5. The method of claim 1 , wherein the diameter of the solder ball ranges from about 25 microns to about 500 microns.

6. The method of claim 1 , wherein the semiconductor wafer comprises <100> silicon.

7. The method of claim 1 , wherein the at least one receiving pad comprises at least one material selected from the group consisting of Cr, Cu, CrCu, Ti, TiW, N, and Au.

8. The method of claim 1 , wherein the step of heating to cause the at least one solder ball to flow from the at least one cavity to the at least one receiving pad in order to form at least one solder bump is conducted in an oxide reducing atmosphere.

9. The method of claim 8 , wherein the oxide reducing atmosphere comprises formic acid.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 25, 2014
From: INTERNATIONAL BUSINESS MACHINES CORPORATION
To: ULTRATECH, INC.; ULTRATECH, INC.
Reel/Frame 032523/0745 →