RU2032242C1 - Process of manufacture of laser target of cathode-ray tube on base of monocrystal of semiconductor of a 002b - 006 type - Google Patents

Abstract

FIELD: manufacture of laser cathode-ray tubes. SUBSTANCE: chemical and mechanical polishing of first surface of starting semiconductor plate is conducted. Heterostructure composed of monocrystal film of direct-gap semiconductor of A₂B₆, type grown on substrate of semiconductor of A₃B₅, type is used as starting plate. Output mirror is applied and heterostructure is anchored on cooling agent line. Then substrate of semiconductor of A₃B₅ type is removed by method of selective chemical pickling, for instance with aqueous solution of H₂O₂ and NH₄OH. Surface of monocrystal film of A₃B₅ semiconductor contacting A₂B₆ semiconductor substrate is polished by chemical method and dummy mirror in the form of reflecting coat is applied on it. EFFECT: facilitated manufacture of laser targets. 3 cl, 1 dwg

Description

 The invention relates to a technology for the manufacture of laser cathode ray tubes (LELT), in particular to methods for manufacturing active elements, or laser targets of tubes.

 A known method of manufacturing a LELT target, including cutting an oriented semiconductor ingot from a wafer, grinding and polishing the first side of the wafer, applying a dielectric mirror, gluing the wafer to a sapphire substrate, polishing, mechanical polishing, chemical-mechanical polishing of the second side of the wafer, applying a “deaf” mirror to the second side of the plate [1].

 The disadvantage of this method is the use of mechanical grinding and polishing of the plate, since these types of processing introduce structural defects into the crystal (Akimova I.V. et al. Quantum Electronics, 1977, v. 4, p. 1357).

 Closest to the proposed one is a method of manufacturing a laser target of a cathode ray tube, including chemical-mechanical polishing of the first surface of the original semiconductor wafer, applying an output mirror, fixing the semiconductor wafer to a cold conductor, polishing the second surface of the wafer and applying a dull mirror to the second surface of the semiconductor wafer [2 ]. In this method, mechanical grinding of both surfaces of the plate is carried out.

The disadvantage of this method is the presence of mechanical processing of the semiconductor wafer, in which structural defects are introduced into the surface layer and wafer volume that reduce the radiation parameters of the semiconductor and the efficiency of LELT targets (Bushueva G.V. et al. Surface: Physics, Chemistry, Mechanics, 1991, N 11, p. 157). Another disadvantage of this method is the use of 1.2-1.5 mm thick semiconductor wafers A ₂ B ₆ as the source of the laser target obtained by cutting a bulk crystal-ingot. Actually cutting a bulk crystal into wafers is accompanied by the introduction of structural defects into the wafer volume, in addition, when using this method, a target (active element) having a thickness of 15-30 μm is made from the original semiconductor wafer with a thickness of 1.2-1.5 mm, t .e. approximately 99.9% of the expensive semiconductor material goes into waste (highly toxic) processing.

 The aim of the invention is to increase the yield of suitable targets and increase their efficiency.

To this end, in a method of manufacturing a laser target of a cathode ray tube, including chemically-mechanical polishing of the first surface of the original semiconductor wafer, applying an output mirror, fixing the semiconductor wafer to a cold conductor, polishing the second surface of the wafer and applying a deaf mirror to the second surface of the semiconductor wafer, semiconductor wafers use a heterostructure consisting of a single crystal film of a direct-gap semiconductor type A ₂ B ₆ , you grown on a substrate of type A ₃ B ₅ semiconductor, after a fixed heterostructure on the cold conductor, the substrate of A ₃ B ₅ semiconductor is removed by selective chemical etching, and the surface of the single crystal semiconductor film A ₂ B ₆ that is in contact with the substrate of A ₃ B _{5 is} polished chemically and apply a reflective coating to it.

As the initial heterostructure, Zn _x Cd _1-x S _y Se _1-y / GaAs _z P _1-z heterostructures are used.

The best result is achieved by the fact that selective chemical etching of the GaAd _z P _1-z substrate is carried out in an etchant consisting of a solution of hydrogen peroxide H ₂ O ₂ and ammonia NH ₄ OH in water.

 The scheme of the proposed method is a sequence of technological operations shown in the drawing.

As the initial plate-blanks of the target in the proposed method, heterostructures of zinc-cadmium selenide sulfide on gallium arsenophosphide obtained by chemical vapor deposition or by molecular beam epitaxy are used. The same methods make it possible to obtain very perfect single-crystal ZnSe, ZnS _x Se _1-x , Cds, CdSe, Zn _x Cd _1-x S and other direct-gap A ₂ B ₆ semiconductors on these substrates with high emissive properties in the visible range at a thickness films from 10-12 to 15-18 microns. Moreover, relatively inexpensive FaAs _z P _1-z wafers obtained, for example, by melt crystallization, are used as growth substrates. In relation to the invention, such heterostructures possess important properties: the chemical heterogeneity of the film and the substrate, which makes it possible to select and use selective chemical etchers to remove the substrate. As experiments have shown, when using an aqueous ammonia solution as an etchant, the etching rate (dissolution in it) of a GaAs _z P _1-z substrate exceeds the etching rate of A ₂ B ₆ film by an order of magnitude or more, and the process of etching the substrate can be visually controlled.

The chemical-mechanical polishing of the growth surface of the film A ₂ B ₆ in the proposed method is used to remove the surface texture and give it the necessary microroughness.

After removing the substrate from A ₃ B _5, the film surface in contact with the substrate undergoes chemical polishing (for example, in a solution of hydrochloric acid and chromium oxide) to remove the “transition” layer that appears in the thin (0.5-1 μm) layers of the film and containing impurities and defects that reduce the emissive properties of the film and, accordingly, the efficiency of the LELT target.

 Since the proposed method does not apply mechanical effects on the semiconductor wafer (cutting, mechanical grinding and polishing), the yield of suitable targets is increased, since there are no types of defects associated with machining: cracking of plates, elastic stresses, plastic deformation of crystals, etc.

 The proposed method is as follows.

The growth surface of A ₂ B _{6 of the} initial heterostructure is chemically mechanically polished with a removal depth of 1-1.5 μm.

 After washing, a reflective coating (for example, a multilayer dielectric) is applied to this surface.

 Glue the surface of the film with the target cold conductor (for example, with a leucosapphire disk).

The A ₃ B ₅ substrate is removed by selective chemical etching.

The surface of the A ₂ B ₆ film in contact with the substrate is chemically polished with a removal depth of 0.5-1 μm.

 After washing and controlling the surface, a reflective coating (for example, metal-dielectric) is applied to it.

 As an example, we present the results of manufacturing LELT targets from ZnSe / GaAs type heterostructures. For comparison, similar results are presented for targets from ZnSe bulk plates obtained by the most advanced method of vapor growth using the Davydov-Markov method (heterostructures were obtained by the MOCVD method - chemical vapor deposition).

 The diameter of the ZnSe / GaAs heterostructures is 28-35 mm, the diameter of the ZnSe plates is 30-38 mm. The initial thickness of the ZnSe film on a GaAs substrate is 12–18 μm, and the thickness of a GaAs substrate is 1.0–1.1 mm. The initial thickness of the ZnSe plates is 1.1-1.2 mm.

LELT targets were made: from bulk ZnSe plates according to the prototype method; from ZnSe / GaAs heterostructures according to the proposed method. Suitable LELT targets were obtained: from 10 volume ZnSe plates — 2 pcs; out of 10 ZnSe / GaAs heterostructures - 4 pcs. Efficiency targets were measured in the composition at a pump LEBT electron energy 63 KeV, current pump beam 1.0 mA at ³⁰⁰ K.

Measurement Results:
The efficiency of targets manufactured by the prototype method is 0.2-0.3%, according to the proposed method - 1.3-1.9%.

Claims (3)

1. METHOD FOR PRODUCING A LASER TARGET OF AN ELECTRON BEAM TUBE BASED ON A ₂ B ₆ SEMICONDUCTOR SINGLE-CRYSTAL MONOCRYSTAL, including chemical-mechanical polishing of the first surface of the initial semiconductor wafer, applying an output mirror, fixing the semiconductor wafer to the surface of the semiconductor wafer and x on the second surface of the semiconductor wafer, characterized in that a heterostructure of After a heterostructure is attached to a cold conductor, an A ₃ B ₅ semiconductor, which is grown from a single-crystal film of a direct-gap semiconductor of type A ₂ B ₆ grown on a substrate of a type A ₃ B ₅ semiconductor, is removed by selective chemical etching, and polishing in contact with the substrate from type A ₃ B ₅ semiconductor of the second surface of the semiconductor wafer in the form of a single crystal semiconductor film of type A ₂ B _{6 is} carried out chemically. 2. The method according to claim 1, characterized in that the initial heterostructures use heterostructures Zn _x Cd _{1 - x} S _y Se _{1 - y} / GaAs _z P _{1 - z} , where x, y, z take values from 0 to 1 and x + y = 1. 3. The method according to claim 2, characterized in that the selective chemical etching of the GaAs substrate _z P _{1 - z is} carried out in an etchant consisting of a solution of hydrogen peroxide H ₂ O ₂ and ammonia NH ₄ OH in water.

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