SU1691722A1 - Method for control of semiconductor plate parameters - Google Patents

Abstract

The invention relates to a measuring technique. The purpose of the invention is to reduce the time while ensuring control in two parameters simultaneously. The method of controlling the parameters of a semiconductor wafer is implemented as follows. Microwave power is applied to a reference semiconductor wafer (EPG), the front face of which is at a fixed distance from the radiation source. For EPP fixed metal reflector (MO). Movement of the MOs establishes a minimum of the reflected microwave signal, which corresponds to the fact that the air-semiconductor-air-metal structure becomes resonant. Then, the EPP is replaced with the test one so that its front face is at the same distance from the microwave power source as the front face of the EPC. If the conductivity and thickness of the sample under investigation correspond to the parameters of the EPG, then the power of the reflected microwave signal does not change. Otherwise, an increase in the reflected signal occurs. 2 Il. cl

Description

The invention relates to a measurement technique, in particular, to a technique for contactless measurement of semiconductor parameters, and can be used in the production of semiconductor materials, in technological processes of their screening, sorting.

The purpose of the invention is to reduce the time while ensuring control in two parameters simultaneously.

FIG. 1 shows a structural electrical circuit of the device for implementing a method for monitoring parameters of a semiconductor wafer; in fig. 2 is a graph of the microwave power reflectance as a function of the conductivity and thickness of the semiconductor.

The device contains microwave radiation sources, including a generator 1 and a directional coupler 2 with a radiating end, the semiconductor plate 3 under study, a metal reflector 4 equipped with a micrometric system of movement, an indicator unit 5.

The method of controlling the parameters of the semiconductor wafer is carried out as follows.

The microwave power from the oscillator 1 through the directional coupler 2 falls on a reference conductor plate, the front face of which is at a fixed distance from the radiation source and behind

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mounted on one base with a metal reflector 4 and a micrometric system of movement. The movement of the metal reflector 4, located behind the reference semiconductor plate, establishes the minimum of the reflected microwave signal observed on the indicator unit 5. This corresponds to the fact that the air-semiconductor air-metal structure formed by the metal reflector 4, semiconductor plate 3 and air gaps between by them and the radiation source becomes resonant. In this case, the parameters of the semiconductor wafer must satisfy the conditions

a d 0,53 KG2 y arcth V5T;

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where a is the specific conductivity of the material of a semiconductor wafer (OM) 1;

d is the thickness of the semiconductor wafer, m;

e is the relative dielectric constant of the semiconductor wafer material;

I is the distance between the semiconductor plate and the metal reflector, m;

/, / The wave number of the semiconductor and air, respectively.

The reference semiconductor wafer is then replaced with the test one so that its front face is at the same distance from the radiation source as the front face of the reference. If the conductivity and the thickness of the sample being measured correspond to the reference, then the power of the reflected microwave signal is not

changes, otherwise. an increase in the reflected signal occurs.

The proposed method makes it possible to simultaneously control not only the specific conductivity of a semiconductor, but also its thickness, which is necessary at the initial stages of screening semiconductor wafers under industrial conditions, thereby reducing

economic costs in the control of semiconductors on equipment, since a variety of instruments are required to control the conductivity and thickness of the semiconductor.

F o rumlula and z o breetn

A method for controlling the parameters of a semiconductor wafer, which includes irradiating a semiconductor wafer with microwave radiation and receiving a reflected signal, characterized in that, in order to reduce time while ensuring control simultaneously by two parameters, the reference semiconductor wafer is irradiated with microwave radiation

known values of conductivity and thickness behind which the metal reflector is placed, move the metal reflector to obtain the minimum value of the reflected signal, then, instead of the reference semiconductor plate, the investigated semiconductor plate is set so that the distance from its front face to the microwave source is equal to from the front face of the reference semiconductor wafer to the source of microwave radiation, and by changing or not changing the minimum value of the reflected The signal is judged on the deviation or coincidence of the thickness and specific conductivity of the semiconductor wafer under study from the reference one.

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Claims (1)

Claim A method of controlling parameters of a semiconductor wafer, comprising irradiating the semiconductor wafer with microwave radiation and receiving a reflected signal, characterized in that that, in order to reduce time while monitoring simultaneously in two parameters, a reference semiconductor wafer with known values of specific conductivity and thickness, behind which a metal reflector is placed, is preliminarily irradiated with microwave radiation, the metal reflector is moved until the minimum value of the reflected signal is obtained, then instead of the reference semiconductor wafers install the investigated semiconductor wafer so that the distance from its front face to the microwave radiation source equal to the distance from the front face of the reference semiconductor wafer to the microwave radiation source, and by changing or not changing the minimum value of the reflected signal, one can judge the deviation or coincidence of the thickness and conductivity of the investigated semiconductor wafer from the reference. FIG. 1 Figure 2