SPECIFICS OF DESIGNING AN INFRARED PYROMETER-REFLECTOMETER FOR SEMICONDUCTOR HETEROSTRUCTURE FABRICATION

ISSN (p) 0321-2211, ISSN (e) 2663-3450 Аналітичне та екологічне приладобудування АНАЛІТИЧНЕ ТА ЕКОЛОГІЧНЕ ПРИЛАДОБУДУВАННЯ DOI: 10.20535/1970.67(1).2024.306723 UDC: 681.7.015.2 SPECIFICS OF DESIGNING AN INFRARED PYROMETER-REFLECTOMETER FOR SEMICONDUCTOR HETEROSTRUCTURE FABRICATION Andriy Voronko, Denys Novikov, Dmytro Verbitskiy, Maksym Chmyr, Oleksandr Voloshyn, Oleksii Belkevych, Marharyta Holubets National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine Email: There are general technical requirements for all types of reactors for chemical vapour deposition technology using AIII- BV metalorganic compounds. Among them, it is worth highlighting the large temperature gradients that cause the origin of convection loops, which in turn, taking into account the high speed of the gas flow, lead to turbulence in the reactor instead of the expected laminar flow. It is also important to take into account the change in parameters of the wafer surface during the growth process and the need for signal separation between the useful signal from the wafer surface and the background signal from the wafer carrier, which rotates at fixed speed for uniform deposition of compounds. To obtain high-quality heterostructures with reproducible parameters, it is important to have a system of precise temperature control on the wafer surface directly in the deposition area, since the deposition process for many complex semiconductor devices (for example, laser diodes, LEDs, photodiodes, transistors on heterojunctions) is very sensitive to temperature changes. The method of optical pyrometry is a non-contact method that allows to precisely determine the temperature of the wafer surface and meets the technical requirements of CVD epitaxy growth reactors. This article is devoted to the analysis of the features of the development of optoelectronic systems for precise temperature measurement during epitaxial growth in order to determine the criteria for the selection or development of components of the optoelectronic system of the pyrometer-reflectometer. The main physical processes, electro-optical characteristics of Si photodiode, AlGaAs/GaAs LED and parameters of bandpass interference filters were investigated. Based on the analysis of the obtained research and measurement results, scientific recommendations have been developed. The recommendations aimed at the selection and optimization of the parameters of the components of the pyrometer-reflectometer (photodetectors, light emitting diodes, optical filters) in order to improve the accuracy and temperature stability of measurements in the pyrometer’s operation conditions, which take into account the compensation of emissivity change from the surface of the wafer. Keywords: AIII-BV semiconductors; metalorganic chemical vapour deposition; MOCVD; photodiode; light emitting diode; pyrometry with emissivity compensation; optoelectronic systems for monitoring parameters; optical filter. Introduction Currently, the main method of obtaining semiconductor heterostructures based on AIII-BV solid solutions for micro-optoelectronic devices is the method of metalorganic chemical vapour deposition (MOCVD). This method allows for the production of high-quality semiconductor structures with a minimal number of defects in the crystal lattice. During epitaxial layer growth, one of the important parameters is the wafer temperature. This parameter is particularly crucial for obtaining quantum-sized structures, active layers of lasers, and LEDs [1]. For example, in emitting semiconductor devices, a change in the temperature of the wafer from that specified in the technological recipe, or temperature non-uniformity across the wafer surface leads to variations in one of the main parameters – the wavelength of radiation. Therefore, precise temperature control during the deposition of epitaxial layers is a critical aspect. To obtain layers with the necessary parameters, during the epitaxy process, it is necessary to maintain the temperature with an accuracy of ±0.4 °C [2]. The technology of chemical vapor deposition (CVD) involves the use of highly reactive reagents at high temperatures. To ensure maximum purity, there should be no impurities in the reactor environment that can cause unwanted chemical reactions. Epitaxy occurs by depositing reagents on the surface of a semiconductor wafer. Epitaxy occurs by depositing reagents onto the surface of the semiconductor wafer. To ensure a laminar flow during deposition, the wafer, which is placed on a graphite carrier, rotates at a fixed speed that depends on the design and parameters of the reactor. Optical methods, particularly optical pyrometry, are used for temperature control. This method allows for non-contact temperature measurement of the wafer Вісник КПІ. Серія ПРИЛАДОБУДУВАННЯ, Вип. 67(1), 2024 25 ISSN 0201-744X, ISSN 0321-2211 Аналітичне та екологічне приладобудування surface inside the reactor. However, during the heteroepitaxy process, the optical properties of the wafer surface change, so the temperature control system must take these changes into account. To solve this issue, a method called emissivity-compensated pyrometry is employed. This method consists in measuring not only the thermal radiation of the plate, but also in the additional measurement of the reflectivity of its surface using a reflectometer to compensate for changes in the optical parameters of the wafer surface and further precise determination of the real temperature. Depending on the tasks and the spectral range of measurement, silicon photodiodes [3], GaAs photodetectors [4], position-sensitive photodetectors, including matrices of photosensitive elements [5] are used in radiation-compensated pyrometersreflectometers. The use of position-sensitive photodetectors allows to control the change in the curvature of the plate surface during epitaxy, using optical deflectometry methods. Problem statement The research task consists in a detailed analysis of the method of registration and formation of an optical signal in a pyrometer-reflectometer, determination of the optimal spectral range, research of the characteristics of detectors and IR range emitters. The purpose of the article is to determine the main technical criteria for the selection or development of optoelectronic elements for a precision substrate temperature control system during the production of semiconductor heterostructures based on AIII-B5 solid solutions for microoptoelectronics devices fabrication. Functional scheme of the pyrometerreflectometer optical unit To ensure the laminar flow of the depositing reagents, the wafer carrier rotates at a fixed speed determined by the design and parameters of the reactor. Considering that physical sensors have inertia and the impossibility of directly measuring the temperature of the wafer surface, as well as separating the signal from the wafer surface and the wafer carrier, the use of (...truncated)