Contact mark contamination of Si wafers in Marangoni drying is related to water retention at the contact area between wafers and a process holder. The formation of water retention at wafer/holder contact is addressed with a conceptual model. A technical approach of capillary drainage is proposed to tackle the contact mark issue, along with experimental verification.
Author archive for: dlong
Wet Chemical Processing with Megasonics Assist for the Removal of Bumping Process Photomasks
A new generation of negative tone and chemically amplified positive tone photoresists by TOK, JSR, Dow Chemical and others has gained momentum for advanced packaging applications. Resist thickness requirements are increasing to the 40-100 µm range as Cu pillars and micro-bumps are adopted to accommodate the tighter pitches required in the newest multi-chip package designs. In order to form the pillars, the resist mask must be thicker to contain the entire bump structure.
Correlation Between Conductivity and pH Measurements for KOH Texturing Solutions and Additives
The ability to control the chemical concentration of etching baths is a critical step in being able to achieve uniform and repeatable texturization of solar cells. It also maximizes the chemical usage by being able to extend the usable bath life of the process. This in turn, cuts down on waste and reduces the overall cost of ownership (COO). The use of conductivity as a means of control has long been in use for oxide etching baths. The ability to extend that technology to other chemicals has been explored. This paper demonstrates the use of pH and conductivity sensors to monitor and control the concentration of KOH solutions. The effects of various additives as well as silicate buildup on pH and conductivity have been investigated and the results showed that the bath life can be extended and stable processes obtained.