Dynamic Wet Etching of Silicon through Isopropanol Alcohol Evaporation

Tiago Monteiro,Graça Minas,Luís Gonçalves,Susana Cardoso,Pamakštys Kastytis

doi:10.3390/mi6101437

Abstract

In this paper, Isopropanol (IPA) availability during the anisotropic etching of silicon in Potassium Hydroxide (KOH) solutions was investigated. Squares of 8 to 40 µm were patterned to (100) oriented silicon wafers through DWL (Direct Writing Laser) photolithography. The wet etching process was performed inside an open HDPE (High Density Polyethylene) flask with ultrasonic agitation. IPA volume and evaporation was studied in a dynamic etching process, and subsequent influence on the silicon etching was inspected. For the tested conditions, evaporation rates for water vapor and IPA were determined as approximately 0.0417 mL/min and 0.175 mL/min, respectively. Results demonstrate that IPA availability, and not concentration, plays an important role in the definition of the final structure. Transversal SEM (Scanning Electron Microscopy) analysis demonstrates a correlation between microloading effects (as a consequence of structure spacing) and the angle formed towards the (100) plane.

Highlights

Surface texturing of crystalline silicon wafers is a widely used process in different areas of application
The silicon wet etching process is a common manufacture process that involves the use of liquid etchants in the removal of exposed areas of the sample
Isotropic or anisotropic profiles can be achieved, depending on the crystalline orientation of the silicon wafer and the etchants used in the process

Summary

Introduction

Surface texturing of crystalline silicon wafers is a widely used process in different areas of application. The silicon wet etching process is a common manufacture process that involves the use of liquid etchants in the removal of exposed areas of the sample. Isotropic or anisotropic profiles can be achieved, depending on the crystalline orientation of the silicon wafer and the etchants used in the process.

Results

Conclusion