RU158292U1 - PHOTO RECEIVER OF IR RANGE - Google Patents

Abstract

The proposed utility model relates to the field of microelectronics and optoelectronics, in particular to the design of an infrared array photodetector integrated photodetector (IR FPU) and can be used to register optical signals in transmitting television cameras, in optical spectrometers, gas and liquid media analyzers, and in artificial view of robots in infrared (IR) imaging systems for military, industrial, research and medical purposes. The proposed device has increased radiation resistance, speed, low power consumption and heat dissipation, and a more technological design. This is achieved by the fact that in the known device containing a matrix of photosensitive elements made in an epitaxial layer of cadmium-mercury-tellurium located on a buffer layer of cadmium telluride, and a processing circuit made in silicon, a buffer layer of cadmium telluride is located on a dielectric sapphire substrate, and The processing scheme is performed in an epitaxial silicon layer of orientation (100) located on the same side of the sapphire substrate.

Description

The proposed utility model relates to the field of microelectronics and optoelectronics, in particular to the design of an infrared array photodetector integrated array (FPU) and can be used to record optical signals in transmitting television cameras, in optical spectrometers, gas and liquid media analyzers, and in artificial view of robots in systems for the formation of infrared (IR) images of military, industrial, research and medical purposes.

Photodetector devices (FPUs) are made on the basis of infrared photodetectors with photosensitive elements (PSEs) and photo signal processing circuits (multiplexers) with control electronics.

At present, the most demanded are IR FPUs operating in the field of atmospheric transparency (wavelengths λ = 3-5 and λ = 8-14 μm). In this wavelength range, cadmium-mercury-tellurium (Cd _x Hg _1-x Te) materials are most sensitive, the composition of which is determined by the required wavelength range. For such photosensitive arrays (PMFs), a processing circuit (multiplexers) is fabricated on silicon silicon wafers with an orientation of (100) using standard integrated circuit (IC) manufacturing technology. At the same time, the switching of the PSM and the multiplexer is carried out using indium columns [1 Matrix photodetector devices of the infrared range. Novosibirsk "Science" with. 361, 2001].

Known infrared photodetectors [2 V.I. Stafeev, K.O. Boltar, I.D. Burlakov et al. Matrix photodetectors in the middle and far infrared spectral ranges based on photodiodes from Cd _x Hg _1-x Te-FTP, 2005, Volume 39 (10) p. 1257-1265.] Containing a matrix of photosensitive elements based on KPT epitaxial layers grown on a CdZnTe substrate or on a GaAs substrate through CdZnTe or CdTe buffer layers and multiplexers made on a silicon substrate. The matrix of photosensitive elements with multiplexers is coupled by the method of “cold” compression welding of indium microcontacts (flip-chip).

The disadvantages of this device are:

- the complexity of the technology and, as a result, reduced yield and increased cost of the product due to the need to use specially developed infrared microscopes for the precise positioning of many thousands of indium microcontacts (columns) of the crystal of the photosensitive element matrix and silicon substrate containing the processing circuit (multiplexers);

- increased heat dissipation and low reliability of communication points of various circuit elements under the influence of vibration and thermal deformation;

- mechanical stresses arising from the mismatch of the thermal expansion coefficients of the materials used, which leads to rupture of the indium microcontacts [3 A.V. Sorochkin, B.C. Varavin, A.V. Predein, I.V. Sabinina, M.V. Yakushev Investigation of the photovoltaic characteristics of diodes in prototype photosensitive pixels for a monolithic matrix IR photodetector FTP, 2012, vol. 46, issue 4 s. 551-557.];

- uncontrolled changes in the characteristics of photosensitive elements up to complete degradation due to mechanical stresses at the sites of indium microcontacts during compression welding of a matrix of photosensitive elements with multiplexers [1 Matrix infrared photodetector devices. Novosibirsk "Science" with. 361, 2001].

- decrease in detectability due to increased noise:

- the occurrence of stray capacitances and resistances, which also lead to a decrease in the detection ability [3 A.V. Sorochkin, B.C. Varavin, A.V. Predein, I.V. Sabinina, M.V. Yakushev Investigation of the photovoltaic characteristics of diodes in prototype photosensitive pixels for a monolithic matrix IR photodetector FTP, 2012, vol. 46, issue 4 s. 551-557].

In addition, it is known infrared photodetector [3 A.V. Sorochkin, BC Varavin, A.V. Predein, I.V. Sabinina, M.V. Yakushev Investigation of the photovoltaic characteristics of diodes in prototype photosensitive pixels for a monolithic matrix IR photodetector FTP, 2012, vol. 46, issue 4 s. 551-557. (p. 552); 4 M.V. Yakushev, V.V. Vasiliev, S.A. Dvoretsky et al. Development of technology elements for a monolithic infrared photodetector. Applied Physics No. 2, 2009 p. 120-126 (p. 121)], which is the prototype of the proposed utility model, containing a line of photosensitive elements made in the form of photodiodes in the epitaxial layer (CMT) of cadmium-mercury-tellurium (Cd _x Hg _1-x Te) grown through a buffer layer cadmium telluride (CdTe) in specially designated areas on the surface of a monolithic silicon substrate orientation (310), on which multiplexers are prefabricated.

However, this device has the following disadvantages: low radiation resistance of the processing circuits, low speed of the processing circuits, increased heat dissipation and power consumption in the processing circuits, as in the prototype processing schemes are made in monolithic silicon, and low manufacturability because The processing scheme was performed on silicon substrates of orientation (310).

The objective (technical result) of the proposed utility model is to increase radiation resistance, speed, reduce power consumption and heat and manufacturability of the design of the infrared photodetector.

The problem is achieved in that in the known device containing a matrix of photosensitive elements made in an epitaxial layer of cadmium-mercury-tellurium located on a buffer layer of cadmium telluride, and a processing circuit made in silicon, a buffer layer of cadmium telluride is located on a dielectric sapphire substrate, and the processing scheme is performed in an epitaxial silicon layer of orientation (100), located on the same side of the sapphire substrate.

Photosensitive elements and multiplexers are formed in a single technological cycle in the epitaxial layers of cadmium-mercury-tellurium and Si (100), respectively, located on the planar side of the sapphire substrate. The connection of the photocells and the processing circuit is carried out by the In ₂ O ₃ conductor transparent on the planar side in the IR region.

In drawing 1 shows a structural diagram of the proposed device. The proposed device contains a sapphire substrate (Al ₂ O ₃ ) - 1 and sequentially arranged buffer layer of cadmium telluride (CdTe) - 2; an epitaxial silicon layer - 3, in which a photosignal processing circuit (multiplexer) is formed, an epitaxial layer of a photosensitive semiconductor (Cd _x Hg _1-x Te) - 4, in which a matrix of photosensitive elements and metal buses - 5 are formed.

The device operates as follows. Infrared radiation through a transparent (in the ranges 1-5 and 8-14 μm) sapphire substrate with a layer of cadmium telluride (CdTe) enters the photocell created in the photosensitive cadmium-mercury-tellurium layer (Cd _x Hg _1-x Te). When radiation enters the photocell, a photo signal arises in it, which, through the metal bus 5, falls on the elements of the multiplexer and is registered by the processing circuit located in the epitaxial silicon layer (3) located on the periphery of the same dielectric substrate.

In the proposed IR FPU device, the processing circuit is made in an epitaxial silicon layer located on a dielectric substrate, which allows increasing the radiation resistance of the photo-processing circuit by orders of magnitude due to a sharp decrease in the number of radiation-generated charge carriers compared to their number in the same circuit, but made in bulk silicon, which increases the radiation resistance of the design of the proposed FPU IR range.

The processing circuit of the photo signal, made in an epitaxial silicon layer located on a dielectric substrate, allows the dielectric isolation of the elements of the processing circuit, which leads to a decrease in stray capacitance of the areas of the source and drain of MOS transistors in the processing circuit, a decrease in leakage currents and a decrease in stray interelement capacities as compared to the processing schemes photosignals made in bulk silicon (and using isolation by pn junctions), which improves the performance of current FPU IR range.

Reducing the leakage currents between the processing circuit and the substrate and reducing the capacitances of the pn junctions in the photo signal processing circuit made in an epitaxial silicon layer located on the dielectric substrate allows to reduce the supply voltage of the processing circuit, which reduces the power consumption and heat generation in the proposed IR FPA range.

Reducing heat release can reduce the requirements for the FPU cooling system, which also increases the manufacturability and reliability of the proposed design.

The matrix of photosensitive elements and the processing circuit of the photosignal are made on the same substrate on one side, which simplifies the manufacture of the structure and improves its manufacturability, excluding the operation of attaching individual elements of the device to a common board. The use of epitaxial silicon of orientation (100) instead of monolithic silicon of orientation (310) makes it possible to use standard well-developed operations that fit into production routes for processing the FPU of the proposed design, which also increases manufacturability (and, consequently, cost).

Thus, the technical result of the proposed device is to increase radiation resistance, speed, reduce power consumption and heat and manufacturability of the design of the infrared photodetector.

Claims (1)

An infrared photodetector containing an array of photosensitive elements made in an epitaxial cadmium-mercury-tellurium layer located on a cadmium telluride buffer layer, and a processing circuit made in silicon, characterized in that the cadmium telluride buffer layer is located on a dielectric sapphire substrate, and The processing scheme is performed in an epitaxial silicon layer of orientation (100) located on the same side of the sapphire substrate.

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