RU2303315C1 - Semiconductor device manufacturing process - Google Patents

Abstract

FIELD: electronic engineering; manufacturing gallium arsenide based devices.

SUBSTANCE: proposed gallium arsenide based devices are manufactured from device structures with active-region electron concentration higher than required to ensure desired output parameters of devices; upon manufacture devices are irradiated with fast neutron fluency whose value is found from formula F_n=(1-K)/(7.2·10^-4n₀ ^-0.77) neutron/cm², where F_n is neutron fluency value; K = n₁/n₀ is variation level of electron original concentration in device active region when irradiated with fast neutron fluency F_n; n₀ is electron concentration in device active region before irradiation, cm^-3; n₁ is electron concentration in device active region after irradiation needed to provide for desired output parameters, cm^-3; upon irradiation devices are given trial run with power continuously supplied to them at temperature of 85 ± 5 °C for 10-24 h.

EFFECT: enhanced resistance to irradiation with electrons and gamma-quanta.

1 cl, 1 dwg

Description

The invention relates to the field of electronic technology and can be used in the manufacture of semiconductor devices based on gallium arsenide.

A known method of manufacturing silicon-based transistors (RF Patent No. 1424634, IPC H01L 21/363. The method of radiation processing of transistors / Beletsky PN, Vaysburd D.I., Orlov V.M., Chmukh Z.N., Shemendyuk A .P. - declared on 12.01.1987, published by BIPM No. 11, 04/20/2000), the essence of which is to irradiate silicon wafers with transistor structures with protons with energy at which the proton range is not less than the thickness of the plate, and a dose of 7 · 10 ¹³ to 25 · 10 ¹³ proton / cm ² and then conduct heat treatment at 400-450 ° C for 20-30 minutes

This method cannot be used for devices based on gallium arsenide.

A known method of increasing the radiation resistance of silicon (RF Patent No. 847833, IPC H01L 21/324 / Akhmetov V.D., Bolotov V.V., Smirnov L.S., IPP SB USSR Academy of Sciences, declared. 08.23.1979, publ. BIMP No. 17, 06/20/2000 - prototype), which consists in the fact that they conduct heat treatment of silicon in the temperature range 500-600 ° C for 100-800 hours in an inactive environment.

This method, as described above, cannot be used for devices based on gallium arsenide.

The problem to which the invention is directed, is the manufacture of devices based on gallium arsenide with high resistance to irradiation with electrons and gamma rays.

This object is achieved by the fact that in the method of manufacturing devices based on gallium arsenide, which includes the manufacture of devices and subsequent processing, the devices are made of device structures with an electron concentration in the active region greater than that required to provide the output parameters of the devices, and after manufacture, the devices are irradiated with fast neutron fluence, the value of which is determined by the formula

- уровень изменения исходной концентрации электронов в активной области прибора при облучении флюенсом быстрых нейтронов; n₀ - концентрация электронов в активной области прибора до облучения, см^-3; n₁ - концентрация электронов в активной области приборов, требуемая для обеспечения выходных параметров, см^-3; а после облучения проводят токовую тренировку в непрерывном режиме питания при температуре 85±5°С в течение 10-24 часов.where F _n is the neutron fluence;

- the level of change in the initial concentration of electrons in the active region of the device when irradiated with a fast neutron fluence; n ₀ - electron concentration in the active region of the device before irradiation, cm ^-3 ; n ₁ is the electron concentration in the active region of the devices required to provide output parameters, cm ^-3 ; and after irradiation, current training is carried out in a continuous diet at a temperature of 85 ± 5 ° C for 10-24 hours.

Using a temperature of less than + 80 ° C during subsequent current training in a continuous power mode does not allow stabilizing the parameters of devices subjected to preliminary irradiation with fast neutrons, while using a temperature of more than + 90 ° C can lead to degradation of the parameters of devices.

The process of stabilization of the structure of radiation defects is completely completed during current training in a continuous diet at a temperature of 85 ± 5 ° C for 10-24 hours and with further annealing, the parameters of the devices remain unchanged.

The above invention provides the following beneficial effect. After irradiation with fast neutrons, the electron concentration in gallium arsenide decreases to the value necessary to ensure the required parameters of the devices, which allows to guarantee the receipt of devices with the required parameters, but their resistance to electrons and gamma rays increases.

The physical nature of the proposed method is as follows. As a result of the action of the fast neutron flux in gallium arsenide, particle paths are formed, which are the site of the flow of radiation defects introduced by subsequent irradiation with electrons and gamma rays. As a result of the collection of radiation defects created by subsequent irradiation with electrons and gamma rays, the path of fast neutrons slows down the degradation of the electrophysical properties of gallium arsenide upon subsequent irradiation with electrons and gamma rays and, accordingly, their radiation resistance increases.

Conducting a current training in a continuous diet after preliminary irradiation with fast neutrons makes it possible to stabilize the parameters of the devices (to exclude the slow drift of the parameters of the devices during operation) by stabilizing the structure of radiation defects introduced as a result of preliminary irradiation with fast neutrons.

The use of a higher electron concentration in the initial instrument structures eliminates the deterioration of the output parameters of the devices due to a decrease in the electron concentration in the active layers as a result of preliminary irradiation with fast neutrons below an acceptable level.

The drawing shows a graph of the average value of the power of microwave generation of Gunn diodes of the millimeter wavelength range for various batches of devices when irradiated with electrons with an energy of 3 MeV. Here: 1 - diodes are made of device structures with the required electron concentration in the active layers without the use of fast neutron irradiation; 2 - diodes are made of instrument structures with the required electron concentration in the active layers when using fast neutron irradiation with a fluence of F _n = 6.28 · 10 ¹³ neutrons / cm ² , an increase in the neutron fluence above this value leads to a decrease in the resistance of the diodes during subsequent electron irradiation; 3 - diodes are made of device structures with a high concentration of electrons in the active layers when using fast neutron irradiation with a fluence of F _n = 4.3 · 10 ¹⁴ neutrons / cm ² . In all cases, after irradiation with fast neutrons, a current training was conducted in a continuous diet at + 85 ° C for 10 hours. For all batches of devices, the microwave power after irradiation with electrons is normalized to its value before irradiation.

Consider the implementation of the proposed method on the example of Gunn diodes. Using conventional sandwich technology, including various operations (creating contacts, forming active elements using photolithography methods, scribing plates onto individual crystals and thermocompression assembly in a ceramic-metal casing), Gunn diodes are made from device structures with an increased electron concentration in the active layers. After thermocompression assembly in metal-ceramic cases, the resulting diodes are irradiated with a fast neutron fluence, the value of which is determined by the formula (1).

After irradiation of the diodes, a current training is carried out in a continuous power mode at a temperature of + 85 ° C for 10 hours. Thus, Gunn diodes with increased resistance to irradiation with electrons and gamma rays are obtained.

As can be seen from the results presented in the drawing, preliminary irradiation with fast neutrons can significantly increase the resistance of Gunn diodes to subsequent electron irradiation. But the use of the initial gallium arsenide with the required electron concentration does not allow to achieve a possible maximum increase in the radiation resistance of Gunn diodes, while the use of instrument structures with an increased initial electron concentration and the use of high values of fast neutron fluences (see Chart 3) can further increase the radiation resistance in comparison with instrumental structures having the optimal value of electron concentration in active layers (see graph 2). Estimates show that the maximum increase in resistance to subsequent electron irradiation can exceed 10 times. Similar results are observed upon subsequent exposure to gamma rays.

For other types of Gunn diodes, other types of semiconductor devices based on gallium arsenide, identical results are observed when using preliminary irradiation with fast neutrons and subsequent current training, which confirms the effectiveness of the practical use of the proposed method for manufacturing semiconductor devices.

Thus, the proposed method can significantly increase the radiation resistance of devices based on gallium arsenide to the effects of electrons and gamma rays. The practical implementation of the proposed method does not cause any difficulties.

Claims (1)

A method of manufacturing semiconductor devices based on gallium arsenide, including the manufacture of devices and subsequent processing, characterized in that the devices are made from device structures with an electron concentration in the active region greater than that required to provide the output parameters of the devices, after manufacture, the devices are irradiated with a fast neutron fluence, the value of which is determined according to the formula

where F _n is the neutron fluence;

- the level of change in the initial concentration of electrons in the active region of the device when irradiated with a fast neutron fluence F _n ; n ₀ - electron concentration in the active region of the device before irradiation, cm ^-3 ; n ₁ - electron concentration in the active region of the devices after irradiation, required to provide output parameters, cm ^-3 ; and after irradiation, current training is carried out in a continuous diet at a temperature of 85 ± 5 ° C for 10-24 hours.