ПРОГРАМНО-АПАРАТНИЙ АВТОМАТИЗОВАНИЙ КОМЛЕКС УПРАВЛІННЯ ФОРМУВАННЯМ ПОРУВАТОГО ШАРУ НА НАПІВПРОВІДНИКОВИХ ПЛАСТИНАХ

Abstract

Purpose. Porous silicon is widely used in devices such as light emitters, sensors, and medical devices. The quality of operation of these devices depends on the diameter of the pore, the uniformity of its surface, and the thickness of the layer. To control the characteristics of the porous layer, the current density, etching time, and current shape are changed. As a rule, the growth is carried out using a constant current density. In this case, hydrogen bubbles are formed in the pores with a simultaneous decrease in the etching rate, which leads to the formation of small pores. This limits the pos-sibility of obtaining porous silicon with a high degree of reproducibility. Methodology The research was carried out on a semiconductor wafer. After cleaning, the silicon wafers were etched in an electrochemical cell at room temperature. For the study, two types of etching current were used: current in the form of rectangular pulses with a variable duty cycle and direct current. For the pulsed current, the density was 20 mA/cm2, the duty cycle of the pulses varied from 40 to 80% at a frequency of 7 Hz. For direct current, the etching current density was 20 mA/cm2. The etching time in both experiments was 30 minutes. Findings. The paper shows the influence of the shape of the silicon etching current on the formation of a porous layer. To control the etching process, a hardware-software automated complex for controlling the formation of a porous layer on semiconductor wafers was developed. Originality. When using a pulsed current, the structure of the porous layer becomes more uniform, as evidenced by an increase in the intensity of the photolumines-cence spectrum at a wavelength of 650 nm. Practical value. The results of the work can be used in the development of such devices as light emitters, sensors and medical devices. Сonclusions The method of etching single-crystal silicon has been improved in order to obtain a porous layer having a uniform structure by using the etching current in the form of pulses with a duty cycle of 80% and a frequency of 7 Hz.