Etching of Silicon Wafers by Soaking
Using Alkaline Detergents

I. Purpose

The purpose of this test was to determine the etch characteristics of VALTRON^® alkaline detergents on silicon wafers by soaking.

II. Parameters of the Experiment

1. Conditioning of the Substrates:
   Several clean silicon wafer pieces were used for evaluation.  No further conditioning was necessary.
2. Preparation of Detergent Solutions:
   2.25% VALTRON^® DP160 pH (concentrate) 13.5
   2.25% VALTRON^® DP94001 pH (concentrate) 14.0
   
   Each of the above solutions were prepared in separate 250mL beakers and heated to and maintained at 194°F/90°C.

III. The Experiment

1. 200mL of 2.25% VALTRON^® DP160 was prepared in a 250mL beaker.
2. The solution was heated to and maintained at 194°F/90°C.
3. A silicon wafer was immersed into the solution and soaked for 9 minutes to determine the etch characteristics of the bath.
4. Next, the substrate was given a 15 second spray rinse of low-pressured deionized water at room temperature.
5. The substrate was allowed to air dry and then it was visually inspected under fluorescent lighting for etching effects.
6. Steps 1-5 were repeated using 2.25% VALTRON^® DP94001.
7. The results are summarized in Table 1 below.

IV. Results

Table 1: Etching of Silicon Wafers by Soaking

V. Conclusion

The VALTRON^® DP160 solution resulted in even etching as compared to VALTRON® DP94001 which resulted in spotting of the wafer.

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