Determination of etching parameters for pulsed XeF₂etching of silicon using chamber pressure data

Abstract

A technique is presented for determination of the depletion of the etchant, etched depth, and instantaneous etch rate for Si etching with XeF2 in a pulsed etching system in real time. The only experimental data required is the pressure data collected temporally. Coupling the pressure data with the knowledge of the chemical reactions allows for the determination of the etching parameters of interest. Using this technique, it is revealed that pulsed etching processes are nonlinear, with the initial etch rate being the highest and monotonically decreasing as the etchant is depleted. With the pulsed etching system introduced in this paper, the highest instantaneous etch rate of silicon was recorded to be 19.5 µm min−1 for an initial pressure of 1.2 Torr for XeF2. Additionally, the same data is used to determine the rate constant for the reaction of XeF2 with Si; the reaction is determined to be second order in nature. The effect of varying the exposed surface area of Si as well as the effect that pressure has on the instantaneous etch rate as a function of time is shown applying the same technique. As a proof of concept, an AlN resonator is released using XeF2 pulses to remove a sacrificial poly-Si layer.

Cavities etched by pulsed and continuous flow of XeF2 for multispectral infrared sensors

“…In this process, the etch rate is at its highest at the beginning of the soaking step. As the etchant is consumed during the etch, the etch rate decreases making it more suitable for the removal of sacrificial Si where there is no need for a constant and well controlled etch rate [9] and when efficient use of XeF2 is needed [10].…”

Noble-Gas Chemistry More than Half a Century after the First Report of the Noble-Gas Compound

“…Its main use is in its ability of fluorination of various organic compounds [ 9 , 10 ] and as an etching reagent for surfaces of various metals, oxides, nitrides, etc. [ 11 , 12 , 13 , 14 , 15 , 16 ]. It is also used for the preparation of fluorographenes [ 17 , 18 , 19 ].…”

Fabrication of microparabolic reflector for infrared antenna coupled detectors

“…The etching technique has been extensively studied in the literature [16, 18, 19, 23–27]. The studies reported an average etching rate that varied from to .…”

“…Several parametric studies have previously been presented illustrating the Si etching characteristics and providing an estimate for the etching rate [16,18,19,[23][24][25]. Some efforts have also been placed into modelling and simulating this process [26].…”