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Introduction of the Gettering DP wheel

Application processing examples

When the silicon wafer is polished, there has been a problem to date where the gettering effect*1 is lost while die strength rose.
This introduces the Gettering DP wheel that enables polishing that combines high die strength and the gettering effect.

*1 The gettering effect is a mechanism that forms crystal defects or distortions (= gettering sites) inside the silicon wafer (bulk or backside) and then captures impurities in these gettering sites.
Gettering DP wheel introduced this time forms the gettering site due minute scars on the wafer backside, capturing the heavy-metal impurities.

Gettering effect diagram
Photo.1 Gettering effect diagram(This drawing is made by DISCO.)

Conventionally: approach from grinding

The DISCO lineup includes UltraPoligrind (UPG), which achieves high die strength while maintaining a gettering effect. UPG achieves die strength greater than or equal to that with Gettering DP, but the DGP series Z3-axis must be retrofitted with the grinding specification.

Gettering DP: approach from polishing

Gettering DP is a DP wheel that can achieve a gettering effect while maintaining die strength (minimum value) equal to that with UPG and can be installed as is with the Z3-axis DP specification standard on the DGP series.

Gettering DP processing results

The depth of damage with Gettering DP is about 50nm same as UPG. Moreover, the UPG surface is rough due to grinding with abrasive grains as opposed to the Gettering DP mirror surface from the polishing process.

Cross sections of UPG and Gettering DP
Photo.2 Cross sections of UPG and Gettering DP
Surface roughness with UPG and Gettering DP
Photo.3 Surface roughness with UPG and Gettering DP

In die strength (ball-bending), Minimum value almost equal to the stress relief by UPG is achieved. (Figure.1)

Die Strength Comparison
Figure. 1 Die Strength Comparison

For detailed process methods, please contact the head office Applications R&D Department.


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