On the Mechanism of Chemically Etching Germanium and Silicon

Abstract

The electrode potential of germanium or silicon in a chemical etching solution is a function of solution pH, rate of etching, physical condition of the surface, conductivity type, and resistivity. The results suggest that excess holes and electrons are produced at the surface of the semiconductor during chemical etching. Holes are injected at cathode sites, but only a portion of these holes are consumed at anode sites since the anode reaction involves current multiplication.

Etch rates for micromachining processing

“…Turner has found the peak etch rate of silicon to occur at an HF:HNOs ratio of 4.5, the same ratio as in the balanced reaction given above [26]. The rate-limiting step for the etch solution in this table, which has a low HF concentration, is the supply of HF to the reaction site [26].…”

“…Many metal etches not discussed in this paper also remove material in this twostep manner. The overall reaction is [2], [26] HN03 (70%) : H2O : NH4F (40%).…”

“…The rate-limiting step for the etch solution in this table, which has a low HF concentration, is the supply of HF to the reaction site [26]. The etch rate of a given bath decreases with use as the HF is depleted.…”

Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

“…31,32 In both cases, increasing the H 2 O 2 or HF concentration increases the oxidation rate and dissolution rate, respectively, resulting in nanostructures with varying optical properties. 33 Figures 1(a) to 1(h) show the crosssection SEM micrographs and TEM images acquired from the NW samples grown with HF concentration of 1.8 M, 2.8 M, 4.8 M, and 5.8 M in a fixed H 2 O 2 concentration of 0.5 M. From Fig.…”

Анодные Процессы В Условиях Химического И Электрохимического Травления Кристаллов Кремния В Кислых Фторидных Растворах. Механизм Порообразования

“…Предложен ряд физических моделей, предлагающих объяснение от-дельных аспектов процессов порообразования исходя из представлений о неустойчивости к малым пери-одическим возмущениям планарной границы раздела кремний−электролит в условиях электрохимического травления [1,2] и локализации анодного тока на вогнутой поверхности дна прорастающих пор вследствие туннель-ного или лавинного пробоя слоя объемного заряда в полупроводнике или диэлектрическом слое оксидной фазы на его поверхности [3][4][5][6][7]. Химические модели концентрируются на объяснении величины эффективной валентности кремния и механизма выделения водорода, сопровождающего переход в раствор атомов поверх-ностного слоя кристалла [8][9][10]. Наиболее признанными…”