RU2815294C1 - Method for processing reverse side of silicon transistor structure - Google Patents

Abstract

FIELD: semiconductor devices.

SUBSTANCE: according to the invention, the surface of the silicon substrate is treated in a sandblasting unit, and silicon carbide (SiC) powder with a sand particle size of no more than 5-6 mcm is used as an abrasive material, while a stream of silicon carbide is directed onto the surface of the silicon wafer at a certain distance at the following technological modes: air pressure in the nozzle - 2±0.3 kg/cm², time - 6±0.1 minutes, distance from the nozzle to the plate surface - 15±5 cm, and table rotation speed - 15±5 rpm.

EFFECT: surface has good adhesive properties, the spread in plate thickness is no more than 1.5±0.01 mcm, and occurrence of microcracks, mechanical stresses, irregularities, and chips is eliminated.

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Description

The invention relates to the technology of manufacturing semiconductor devices, in particular to a method for processing the reverse side of a silicon transistor structure before deposition processes.

Various chemical and mechanical methods are known for processing and preparing the back side of silicon substrates with ready-made transistor structures to improve the adhesive properties of the surface before deposition processes during deposition [1].

Mechanical methods are based on the use of abrasive material during grinding and polishing [2]. The main disadvantage of these methods is that during processing microcracks are formed, which subsequently lead to the creation of a network of cracks and cause chipping of individual sections, which worsens the characteristics of the device and reduces the percentage of usable devices.

Chemical methods are based on the use of chemical solutions and etchants. There are known methods for processing semiconductor materials in an etchant: nitric acid with hydrofluoric acid, in alkali solutions KOH, NaOH at temperatures of 90-100°C, etc. [2].

The disadvantage of these methods is that chemical reagents introduce unwanted impurities onto the surface of the silicon substrate, which worsen its electrical properties, and etchants can unevenly etch the surface, which affects the unevenness of subsequent deposition.

The purpose of the invention is to obtain a surface of a silicon transistor structure with good adhesion to sprayed metals when forming a contact to the collector region of the transistor, with the absence of mechanical stresses, cracks, irregularities and chips.

This goal is achieved by treating the surface of the silicon substrate in a sandblasting installation and silicon carbide (SiC) powder with a sand particle size of no more than 5-6 microns is used as an abrasive material.

The essence of the method is that a stream of silicon carbide sand is directed onto the surface of a silicon wafer at a certain distance under the following technological conditions: air pressure in the nozzle - 2±0.3 kg/ ^cm2 , time - 6±0.1 minutes and rotation speed table - 15±5 rpm, the distance from the nozzle to the surface of the processed silicon wafer is 15±5 cm. In this case, the surface has good adhesive properties, the spread in the thickness of the wafer is no more than 1.5±0.01 microns and the occurrence of microcracks is excluded, mechanical stresses, irregularities and chips.

The essence of the invention is confirmed by the following examples:

EXAMPLE 1: The process is carried out similarly to the conditions of example 1. The sandblasting process is carried out under the following modes: air pressure in the nozzle - 2.0±0.3 kg/cm ² , time - 10±0.1 minutes, nominal table rotation speed - 10 ±4 rpm, distance from the nozzle to the surface of the plate - 20±5 cm.

Control is carried out according to the thickness of the plate, the spread of which is 2.0 µm ±5%. The yield percentage is 80-85%.

EXAMPLE 2: The process is carried out similarly to the conditions of example 1. The sandblasting process is carried out under the following modes: air pressure in the nozzle - 2.5±0.3 kg/cm ² , time - 5±0.1 minutes and table rotation speed - 20± 4 rpm, distance from the nozzle to the plate surface -10±5 cm.

Control is carried out according to the thickness of the plates, the spread of which is 1.5 μm ± 5%. The yield percentage is 85-90%.

EXAMPLE 3: The process is carried out similarly to the conditions of example 1. The sandblasting process is carried out under the following modes: air pressure in the nozzle - 3.0±0.3 kg/cm ² , time - 3±0.1 minutes, nominal table rotation speed - 20 ±4 rpm, distance from the nozzle to the surface of the plate - 15±5 cm.

Control is carried out according to the thickness of the plates, the spread of which is 2.2 µm ±5%. The yield percentage is 90-95%.

Thus, the proposed method, in comparison with the prototype, makes it possible to obtain plates with good adhesion, uniform thickness, where the spread is 1.5 μm ± 5% and without microcracks, mechanical stresses and chips.

LITERATURE

1. Patent RU 2587096, H01L 21/302, 10/06/2016.

2. Kurnosov A.I., Yudin V.V. Technology of production of semiconductor devices and integrated circuits, M: “Higher School”, 1986, p. 177-178.

Claims (1)

A method for processing the back side of a silicon transistor structure, including processing silicon wafers in a sandblasting installation, characterized in that silicon carbide particles no larger than 5-6 microns in size are used as sand under the following conditions: air pressure in the nozzle - 2±0.3 kg /cm ² , duration - 6±0.1 minutes, distance from the nozzle to the wafer surface - 15±5 cm and nominal table rotation speed 15±5 rpm, with a silicon wafer thickness size of no more than 1.5±0.01 µm.