Method for chalcogen treatment of n-type gallium arsenide surface

FIELD: semiconductor electrochemistry and semiconductor device technology.

SUBSTANCE: in addition to standard technology, n-type gallium arsenide semiconductor electrode surface is given chemical treatment in solutions of chalcogen-containing compounds prior to electrochemical evaporation of metal on this surface. Specimen is sequentially held at first for 3 minutes in 0.05 M aqueous solution of sodium sulfate (Na2S), then it is dipped for 1-2 seconds in warm (45-50 °C) distilled water, whereupon it is immersed for 3-4 minutes in 0.1 M aqueous solution of sodium selenite (Na2SeO3) and washed for 30 seconds in two portions of hot (60-70 °C) distilled water. In this way nanometric junction layer of arsenide and gallium chalcogenides is formed at metal-semiconductor interface which is coherently integrated with semiconductor and metal phases.

EFFECT: enhanced stability of electrophysical characteristics of metal-semiconductor rectifying contacts at high temperatures in oxidizing atmosphere.

1 cl, 2 tbl

 

The invention relates to electrochemistry of semiconductors and technology of semiconductor devices, used in microelectronics when creating rectifying contacts before the electrochemical deposition of the metal to the semiconductor.

There are many ways of pre-processing the surface of the gallium arsenide in pairs and in different solutions chalcogenidebased compounds (chalcogenide passivation), please review Bessonova [1]. Ways of pre-processing the surface of the gallium arsenide in solutions chalcogenides of alkali metals [1, 2] contribute to the elimination of oxides of gallium and arsenic sulfide or Zelenina processing) from the surface of the semiconductor. Due to the fact that on the surface of gallium arsenide in addition to the oxides of the elements constituting the semiconductor element is present arsenic, the use of only the solutions of the chalcogenides of alkali metals for pre-treatment of the surface of the gallium arsenide does not allow for a proper reconstruction of the surface layers of the semiconductor, and therefore create a coherent boundary metal-semiconductor. Get on the border rectifying contacts less stable under thermal and oxidative effects.

Known technical solutions closest to destination and technical is eskay nature of the claimed object (the prototype) is in addition to standard surface of gallium arsenide of n-type before the electrochemical deposition of the metal in 0.05 M aqueous solution of sodium sulfide with subsequent washing of the sample in two servings of boiled, hot (60-70° (C) distilled water for 30 sec in each [2].

The disadvantage of this method is the inability to remove from the surface of the semiconductor element arsenic, which is reflected on the electrophysical characteristics of the rectifying contacts and their stability.

The method of chalcogen processing the surface of the gallium arsenide of n-type is that the surface of the semiconductor electrode before the electrochemical deposition of the metal is subjected to additional standard chemical processing solutions chalcogenidebased compounds according to the invention that the sample sequentially incubated first in 0.05 M aqueous solution of sodium sulfide (Na2S) 3 min, then dip 1-2 with warm (45-50° (C) distilled water, then immersed for 3-4 min in 0.1 M solution of sodium Selenite (Na2SeO3) and washed for 30 s in two servings of boiled, hot (60-70° (C) distilled water with subsequent introduction into the electrolyte for the deposition of metal. The present invention allows to form at the interface of the metal-semiconductor nanometer transition layer chalcogenides arsenic and gallium, which is coherently combined with semiconductor and metal phases and contributes to the improvement is stabilnosti electrophysical characteristics of rectifying contacts metal - the semiconductor when exposed to high temperatures and oxidizing atmospheres (table 1, 2).

The proposed method (chalcogen passivation) additional pre-treatment of the surface of the gallium arsenide helps to remove from the surface of the semiconductor and oxide layer, and elemental arsenic present after standard acid-peroxide etching of the sample and rinsing it with distilled water. When the etching of the semiconductor sample and washing them in distilled water is the contact surface of the semiconductor to air and oxidation, therefore, education on the surface of a semiconductor oxides of gallium and arsenic can no longer be avoided. And the presence of elemental arsenic on the surface of gallium arsenide after the standard operations etching and leaching due to its stability in aqueous solutions.

The action of sodium sulfide is reduced to the exchange reactions, in which the oxides of gallium and arsenic are transferred into the corresponding sulfides. Therefore removes oxides from the surface of gallium arsenide. Elemental arsenic goes into soluble form due to redox reactions with Selenite ions, which is likely the formation selenide ions, also contributing to the removal of residual oxides from the surface of the semiconductor.

redlagaemaya in the invention of sequential exposure of the surface of the gallium arsenide in sulfide and Selenite solutions followed by rinsing in two servings of boiled, hot (60-70° (C) distilled water contributes to the consistency of values of the electrical parameters (the height of the barrier f, measured in eV and the ideality factor β) contacts metal-semiconductor storage in an atmosphere of air (more than 240 hours) at a temperature of 25°and exposure to elevated temperatures (up to 300°). In tables 1, 2 presents the comparison results of the proposed method of surface passivation of gallium arsenide of n-type (surface orientation (111) a, b) with the results of processing the surface of a semiconductor in a solution of sodium sulfide (0.05 M) for example, Nickel contacts.

The implementation of the invention is achieved as follows. Working side electrode of the single-crystal sample (concentration of majority carriers (2,4-7)·1016cm-3) GaAs n-type sequentially subjected to polishing with diamond powder M8, polished to a mirror finish on the suede with diamond paste, serial degreasing butyl ether, acetic acid, toluene, carbon tetrachloride, etching in sulfuric acid-peroxide-provide the Etchant composition of H2SO4:H2O2:H2O=3:1:1 at a temperature of 70°C for 10-12 min, washing in hot (60-70° (C) boiled distilled water and drying in air for 20 minutes, the Concentration of sulfur is acid is 93%, hydrogen peroxide is 28-30%, distilled water is used. Then, the semiconductor electrode sequentially incubated first in freshly prepared 0.05 M aqueous solution of sodium sulfide (Na2S) 3 min, then immersed for 1-2 seconds in warm (45-50° (C) distilled water, then immersed for 3-4 minutes in a 0.1 M aqueous solution of sodium Selenite (Na2SeO3), washed for 30 seconds in two servings of boiled, hot (60-70° (C) distilled water and a drop of water on the sample surface under the current transfer in the electrolyte for the electrochemical deposition of the metal. Electrodeposition of metal is carried out according to known literature methods.

The above proposed pre-treatment of the surface of the gallium arsenide in solutions of sulfide and sodium Selenite (chalcogen passivation) used to create the rectifying contacts the metal of group VIII/gallium arsenide of n-type, which are more resistant to the effects of high temperatures and oxygen, in comparison with the same contacts, obtained by treating the surface of the gallium arsenide only in the sodium sulfide solution.

Rectifying contacts metal-gallium arsenide of n-type are widely used in the creation of semiconductor devices in microelectronics.

Sources of information

1. Bessonov V.N., The M.V. Lebedev, halco Enigma surface passivation of semiconductors And C. Review / Physics and technics of semiconductors. - 1998. - So 32. No Church - S-1299.

2. Batenkov VA, Fomin L.V., V. Sukhanov. The impact of sulfatirovnie the surface of the semiconductor to the heat resistance of the Ni structures, Ir-GaAs n-type / Izvestiya vuzov. Physics. App. - 2002. - T. No. 8. - P.95-100.

Table 1

Thermal degradation of contacts Ni/GaAs n-type
ProcessingOptionsTemperature, °
2550100150200250300
Na2Sβ1.03±0.02-1.06±0.051.12±0.051.16±0.031.16±0.031.17±0.04
F, eV0.97±0.05-0.92±0.060.91±0.090.94±0.030.90±0.080.9±0.1
Na2S, Na2SeO3β1.02±0.021.03±0.021.02±0.021.02±0.021.04±0.031.05±0.031.06±0.02
F, eV0.63±0.010.64±0.030.64±0.030.63±0.020.64±0.030.64±0.020.65±0.02
Table 2

The degradation kinetics of contacts Ni/GaAs n-type in air at 251°
ProcessingOptionsTime, h
02472168240288
Na2Sβ1.02±0.021.02±0.031.08±0.071.08±0.061.11±0.03-
F, e the 0.88±0.050.90±0.020.89±0.020.76±0.030.78±0.04-
Na2S, Na2SeO3β1.01±0.021.01±0.021.02±0.021.04±0.021.05±0.011.05±0.03
F, eV0.63±0.010.63±0.010.63±0.010.62±0.010.61±0.020.62±0.02

The way the chalcogenide surface treatment of gallium arsenide of n-type, based on the fact that the surface of the semiconductor electrode before the electrochemical deposition of the metal is subjected to additional standard chemical processing solutions chalcogenidebased compounds, characterized in that the sample sequentially incubated first in 0.05 M aqueous solution of sodium sulfide (Na2S) 3 min, then dip on 1÷2 with warm (45÷50° (C) distilled water, flow is immersed for 3÷ 4 min in 0.1 M solution of sodium Selenite (Na2SeO3) and washed for 30 s in two servings of boiled, hot (60÷70° (C) distilled water.



 

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