Surfactant for developers.pptx Surfactant is a catalyst between two phases of material.

Surfactant plays a critical dynamic role in photoresist patterning. Physical aspects are discussed. Any molecule containing at least one hydrophilic group and at least one hydrophobic group is considered surface active. In the classical definition, the hydrophobic group needs to be greater than 8 carbons in order to make appreciable interactions with the non-polar material of interest. Surfactants serve as an interface between different phases as a result of polarity difference. One simple example is a soap used for washing oily hands. It would take almost forever for tap water to rinse off the oil because oil and water just don't mix.

1. Surfactant for Developers

2. Facts Surfactant selection is based on Surface tension reduction Foam control Colloid stability Synergism (1+1 > 2) Metal ion contamination Transport phenomena Filter-absorption effect Surfactant ( Surf ace act ive a ge nt ) is effective only at the interface. Solid-Liquid interface Liquid-Liquid interface Liquid-Air interface

3. Classification All types of surfactants contain polar and a non-polar functional groups.

4. Surface tension Surfactant efficiency is defined as the ratio of surfactant concentration at the interface to that in the bulk (liquid) phase C interface / C bulk . Reduction in surface tension is achieved by Increase in the number of carbon atoms in the hydrophobic chain. A straight alkyl chain as the hydrophobic group, rather than a branched alkyl chain. A single hydrophilic group situated at the end of the hydrophobic group, rather than one at a central position. For ionic surfactants Use of a more tightly bound counterion .

5. Foam control Foam reduction is achieved by Shift of the hydrophilic group to a more central position in the molecule. Surfactant with highly branched chains. Two hydrophilic groups in the molecule, forcing it to lie flat in the interface (Theories of film elasticity)

6. Colloid stability Colloid is a defect source. It forms when the surfactant concentration is above the CMC. Excessive non-polar groups.

7. Surfactant vs. Process Window Based on studies by Ultratech & Shin-Etsu using SIPR 9270M broadband photoresist and TMAH developer, increased surfactant concentration may reduce dev. time, but also reduce the process window (dark loss). Selection of surfactant is very important!

8. Conclusion There are > 1000 types of surfactants in the chemical industry. Proper selection is very important for the electronic industry to minimize trade-offs D ev time D ark loss M etal contamination Foam Defect