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A. Backes, U. Schmid:
"Impact of doping level on the metal assisted chemical etching of p-type silicon";
Sensors and Actuators B: Chemical, 193 (2014), 883 - 887.

The impact of doping level on the metal assisted chemical etching of p-type silicon using silver particlesis investigated. 12 boron doped wafers with doping levels ranging from 1012up to 1019cm−3were used.Silver particles generated from a sputter-deposited thin film via a dewetting procedure act as catalyst in aHF:H2O2etch mixture. The characteristics of the etch rate as a function of time was investigated, revealingin addition an enhanced material removal at the beginning (i.e. in the range of several seconds) and anundesired etching of silver free regions at longer etch times (i.e. >15 min). Furthermore, a strong decreasein etch rate at doping levels exceeding 1016cm−3is observed. Only at these highly doped samples, aporous sub-structure is detected located adjacent and in-between the pores which are generated by theAg particles. It is assumed that the injected holes representing majority charge carriers in p-type silicondiffuse at higher doping levels faster and more efficiently away from the metal-semiconductor interfaceinto the silicon sample resulting in a decreased etch rate.

The impact of doping level on the metal assisted chemical etching of p-type silicon using silver particlesis investigated. 12 boron doped wafers with doping levels ranging from 1012up to 1019cm−3were used.Silver particles generated from a sputter-deposited thin film via a dewetting procedure act as catalyst in aHF:H2O2etch mixture. The characteristics of the etch rate as a function of time was investigated, revealingin addition an enhanced material removal at the beginning (i.e. in the range of several seconds) and anundesired etching of silver free regions at longer etch times (i.e. >15 min). Furthermore, a strong decreasein etch rate at doping levels exceeding 1016cm−3is observed. Only at these highly doped samples, aporous sub-structure is detected located adjacent and in-between the pores which are generated by theAg particles. It is assumed that the injected holes representing majority charge carriers in p-type silicondiffuse at higher doping levels faster and more efficiently away from the metal-semiconductor interfaceinto the silicon sample resulting in a decreased etch rate.

Metal assisted chemical etching; Doping level; Silver particlesThermal dewetting; Etch rate; Porous silicon

http://dx.doi.org/10.1016/j.snb.2013.11.009

Project Head Ulrich Schmid:
Mikrosystemtechnik Projektkonto Schmid