rus
Issue #2/2014
V.Karpov, V.Petrenko, A.Lytkin, V.Semenov, K.Chizh
Cooled Monolithic Arrays of Infra-Red Band. Batch Production Use
Cooled Monolithic Arrays of Infra-Red Band. Batch Production Use
Currently, for the operation within the range of 1.5–5.5 µm cooled photon detector arrays are widely used. In IR micro-photoelectronic technologies two types of photodetecting arrays are used: monolithic and hybrid. The results of environmental tests products afford ground for chossing the monolithic designs.
In the monolithic construction photo-sensitive areas and reading circuits are formed on one crystal. In the hybrid construction photo-sensitive areas are located on one crystal and the reading circuit is located on the second crystal; further, they are joined together with the help of the technology of indium micropillars.
The main parameters of the thermal imagers produced by different firms which use the monolithic arrays of IR band based on PtSi/Si are specified in Table.
Pursuant to the table data, the main parameter of NETD thermal imager is identical for the domestic and foreign firms, and it can be concluded that the technology of such arrays production in Russia can ensure the parameters comparable with the arrays produced in foreign countries.
The following advantages of cooled monolithic arrays based on PtSi/Si Schottky barriers draw attention of the developers of commercially produced thermal imaging devices. Sensitivity inhomogeneity of these arrays is not more than 3% and it is lower than the sensitivity inhomogeneity of the arrays produced on the basis of hybrid technology by many times. This may be due to the fact that the generation and recombination processes of media occur not in the semiconductor volume or its surface layer but in the thin layer of platinum silicide PtSi forming the barrier. Therefore, quantum efficiency does not depend on the semiconductor parameters and their scattering on the area of photo-sensitive layer.
Measures for the enhancement of quantum efficiency are taken in the array. Thus, after the formation of Schottky barrier dielectrical layer of SiO2 is applied on the thin film of PtSi and then aluminum layer is applied. Si front side is coated with the anti-reflective layer. In this manner the resonator between reflective and anti-reflective layers is formed; it considerably increases the quantum efficiency due to the multiple reflection of incident radiation in it.
The fact, that for the production of arrays it is possible to use existing batch technology of production of silicon integrated circuits and devices with the charge coupling which allows obtaining the percentage of "uitable" arrays output considerably (by an order) exceeding the percentage of "suitable" arrays output made on the basis of hybrid construction, is critically important advantage.
Reliability of the operation of monolithic cooled arrays is higher than the reliability of the operation of hybrid arrays, contact coupling of which is interrupted and causes the growth of defective elements upon the periodical chilling down to the temperature of 80K during 5 min. Analogous situation can be observed when operating under the conditions of set vibrations and shocks.
Number of the defective elements in the monolithic arrays is ≈0.02% of the total number of elements, and for the hybrid arrays this parameter is ≈2%.
Chilled mass of the monolithic arrays is three times lower in comparison with the same parameter of the hybrid arrays.
Radiation resistance of silicon structures allows enduring the influence of the special external factors according to GOST RV 20.39.305:
7И1 – 2nd degree of fixity with the coefficient of 10–2;
7И6 – 2nd degree of fixity with the coefficient of 10–2;
7И7 – 2nd degree of fixity with the coefficient of 10–2.
Manufacturing cost of the monolithic arrays is considerably lower than manufacturing cost of the hybrid arrays.
Specifically for this reason currently SAPFIR Moscow Plant OJSC develops the batch production of cooled photodetecting array (MFPU 2 OM) using the cooled matrix 1204TsM2N4 AEYaR.431150.168 TU commercially produced by Angstrem OJSC on the basis of PtSi/Si Schottky barriers and with CCD signal reading circuit.
This unit is the component of thermal imaging device and intended for the transformation of thermal images formed by the lens into the digital video signal.
The main technical characteristics of MFPU 2 OM unit:
Spectral sensitivity range, µm 3–5;
Array dimensions, elements 256×256;
Dimensions of array photo-sensitive field, mm 9.2×6.9;
Step of photo-sensitive elements, µm 36×27;
Array operating temperature, K 78–80;
Threshold irradiance
(when background level is 1·10–4 W/cm2), W/cm2 ≤2·10–7;
Number of sporadic defects:
In the central part of the field (10%) 0;
In 30% zone, not more than 15;
In 60% zone, not more than 15;
Accumulation time, ms……………………………………………40;
Frequency of data output, MHz…………………………………2.5;
Dynamic range, dB ≥50;
Output signal parallel ten-digit binary code;
Cooled mass, g 5.7;
Supply voltage, V 15.0 and 5.0;
Power consumption, W ≤3;
Weight, kg ≤0.75;
Overall dimensions, mm 120×95×85.
The main application of MFPU 2 OM unit according to the service conditions refers to the group 5V on the basis of GOST V 20.39.404; climatic category – temperate frigid climate.
Over the recent years, results of the use of commercially produced monolithic array 1204TsM2N4 AEYaR.431150.168 TU based on
PtSi/Si Schottky barriers in SAPFIR Moscow Plant OJSC have shown that the technology of monolithic silicon structures is preferable for the cooled IR photodetectors, and prospects of the future use in this area have not been exhausted yet. ▪
The main parameters of the thermal imagers produced by different firms which use the monolithic arrays of IR band based on PtSi/Si are specified in Table.
Pursuant to the table data, the main parameter of NETD thermal imager is identical for the domestic and foreign firms, and it can be concluded that the technology of such arrays production in Russia can ensure the parameters comparable with the arrays produced in foreign countries.
The following advantages of cooled monolithic arrays based on PtSi/Si Schottky barriers draw attention of the developers of commercially produced thermal imaging devices. Sensitivity inhomogeneity of these arrays is not more than 3% and it is lower than the sensitivity inhomogeneity of the arrays produced on the basis of hybrid technology by many times. This may be due to the fact that the generation and recombination processes of media occur not in the semiconductor volume or its surface layer but in the thin layer of platinum silicide PtSi forming the barrier. Therefore, quantum efficiency does not depend on the semiconductor parameters and their scattering on the area of photo-sensitive layer.
Measures for the enhancement of quantum efficiency are taken in the array. Thus, after the formation of Schottky barrier dielectrical layer of SiO2 is applied on the thin film of PtSi and then aluminum layer is applied. Si front side is coated with the anti-reflective layer. In this manner the resonator between reflective and anti-reflective layers is formed; it considerably increases the quantum efficiency due to the multiple reflection of incident radiation in it.
The fact, that for the production of arrays it is possible to use existing batch technology of production of silicon integrated circuits and devices with the charge coupling which allows obtaining the percentage of "uitable" arrays output considerably (by an order) exceeding the percentage of "suitable" arrays output made on the basis of hybrid construction, is critically important advantage.
Reliability of the operation of monolithic cooled arrays is higher than the reliability of the operation of hybrid arrays, contact coupling of which is interrupted and causes the growth of defective elements upon the periodical chilling down to the temperature of 80K during 5 min. Analogous situation can be observed when operating under the conditions of set vibrations and shocks.
Number of the defective elements in the monolithic arrays is ≈0.02% of the total number of elements, and for the hybrid arrays this parameter is ≈2%.
Chilled mass of the monolithic arrays is three times lower in comparison with the same parameter of the hybrid arrays.
Radiation resistance of silicon structures allows enduring the influence of the special external factors according to GOST RV 20.39.305:
7И1 – 2nd degree of fixity with the coefficient of 10–2;
7И6 – 2nd degree of fixity with the coefficient of 10–2;
7И7 – 2nd degree of fixity with the coefficient of 10–2.
Manufacturing cost of the monolithic arrays is considerably lower than manufacturing cost of the hybrid arrays.
Specifically for this reason currently SAPFIR Moscow Plant OJSC develops the batch production of cooled photodetecting array (MFPU 2 OM) using the cooled matrix 1204TsM2N4 AEYaR.431150.168 TU commercially produced by Angstrem OJSC on the basis of PtSi/Si Schottky barriers and with CCD signal reading circuit.
This unit is the component of thermal imaging device and intended for the transformation of thermal images formed by the lens into the digital video signal.
The main technical characteristics of MFPU 2 OM unit:
Spectral sensitivity range, µm 3–5;
Array dimensions, elements 256×256;
Dimensions of array photo-sensitive field, mm 9.2×6.9;
Step of photo-sensitive elements, µm 36×27;
Array operating temperature, K 78–80;
Threshold irradiance
(when background level is 1·10–4 W/cm2), W/cm2 ≤2·10–7;
Number of sporadic defects:
In the central part of the field (10%) 0;
In 30% zone, not more than 15;
In 60% zone, not more than 15;
Accumulation time, ms……………………………………………40;
Frequency of data output, MHz…………………………………2.5;
Dynamic range, dB ≥50;
Output signal parallel ten-digit binary code;
Cooled mass, g 5.7;
Supply voltage, V 15.0 and 5.0;
Power consumption, W ≤3;
Weight, kg ≤0.75;
Overall dimensions, mm 120×95×85.
The main application of MFPU 2 OM unit according to the service conditions refers to the group 5V on the basis of GOST V 20.39.404; climatic category – temperate frigid climate.
Over the recent years, results of the use of commercially produced monolithic array 1204TsM2N4 AEYaR.431150.168 TU based on
PtSi/Si Schottky barriers in SAPFIR Moscow Plant OJSC have shown that the technology of monolithic silicon structures is preferable for the cooled IR photodetectors, and prospects of the future use in this area have not been exhausted yet. ▪
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