CN113267118B - A kind of semiconductor conductive film thickness on-line test structure and test method - Google Patents

Abstract

The invention discloses an on-line testing structure for the thickness of a semiconductor conductive film, which comprises a four-probe resistance testing bridge structure and a continuous ladder structure, wherein the structure utilizes a plurality of steps to average random errors in the manufacturing process of the steps, and utilizes the plurality of steps to increase the numerical value of resistance change, thereby facilitating measurement. The invention also discloses an on-line testing method for the thickness of the semiconductor conductive film, which is simple, has low requirement on testing equipment, stable testing process and testing parameter values, synchronous processing process and micro-electromechanical device, has no special processing requirement, completely meets the requirement of on-line testing, and is only limited by a simple mathematical formula.

Description

A kind of semiconductor conductive film thickness on-line test structure and test method

technical field

The invention relates to the field of on-line measurement of semiconductor conductive films, in particular to a structure for on-line testing of the thickness of semiconductor conductive films and a testing method thereof.

Background technique

The film thickness of MEMS thin-film devices is an important parameter that affects device performance. By measuring the thickness of the thin film online, the size of the device can be obtained and the precision of the device can be controlled. Semiconductor is an important material used in the surface micromachining process. The basic process of processing is: first deposit a layer of material on the silicon wafer, which is called a sacrificial layer. Then, the pattern layer is defined by photolithography, and then the structure layer film is formed on the sacrificial layer by chemical vapor deposition and other methods. Finally, the sacrificial layer is removed by etching, so that the movable part of the micro component is separated from the sacrificial layer to form a semiconductor thin film structure. The material of the sacrificial layer is usually a dielectric material, and the structural layer is a semiconductor material. Manufacturers of MEMS products hope to be able to monitor the thickness of semiconductor conductive films online and reflect process errors in the manufacturing process in real time. Therefore, online testing of MEMS products without leaving the processing environment and using convenient equipment has become a necessary means of controlling the process. The online test structure usually adopts the method of electrical excitation and electrical measurement, and obtains the geometrical parameters of the material through the electrical quantity value and the targeted calculation method.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide an on-line testing structure and method for measuring the thickness of a semiconductor conductive thin film, which can be used for on-line measurement of the thickness of a semiconductor conductive thin film by using convenient equipment without leaving the processing environment.

In order to achieve the above-mentioned purpose, the present invention realizes through the following technical solutions:

An on-line test structure for the thickness of a semiconductor conductive thin film, comprising a circular semiconductor thin layer and first to fourth contact electrodes, the four contact electrodes are uniformly arranged on the peripheral side of the circular semiconductor thin layer and are connected with the circular semiconductor thin layer. The four contact electrodes are electrically connected with the circular semiconductor thin layer, and the opening angle formed by the four contact electrodes and the circular semiconductor thin layer is α; it also includes: a four-probe resistance test bridge structure, and the four-probe resistance test bridge structure is provided with On the surface of the dielectric layer, a part of the surface of the dielectric layer is etched into a plurality of mutually parallel and identical grooves, and steps are formed between the grooves, the steps have the same length, and the plurality of grooves are formed. The groove and the corresponding steps together form a continuous ladder structure, and the two sidewalls of the groove and the surface of the dielectric layer have the same included angle; the four-probe resistance test bridge structure includes a first four-probe semiconductor resistance bridge and a second four-probe semiconductor resistor bridge, where,

The first four-probe semiconductor resistance bridge includes a first semiconductor resistance strip and four metal electrodes, wherein one metal electrode is electrically connected at both ends and at each side of the first semiconductor resistance strip, the The middle part of the first semiconductor resistance strip climbs over the continuous ladder structure, one end of the first semiconductor resistance strip is connected with the circular semiconductor thin layer to form an integrated structure, and the other end is connected with the second four-probe semiconductor resistance bridge;

The second four-probe semiconductor resistance bridge includes a second semiconductor resistance strip and two metal electrodes, wherein the second semiconductor resistance strip is arranged at the other end of the first semiconductor resistance strip and is connected with the first semiconductor resistance strip. Resistor bars are connected, the second semiconductor resistor bars share two metal electrodes with the first semiconductor resistor bars, the second semiconductor resistor bars are arranged on the surface of the flat dielectric layer, and the second semiconductor resistor bars are connected to the first semiconductor resistor bars. The first semiconductor resistance strips have the same width.

Further, the metal electrode is disposed on an anchor region, and the anchor region is formed by etching the surface of the dielectric layer.

Further, the dielectric layer is disposed on the insulating substrate.

An on-line test method for the thickness of a semiconductor conductive film, comprising the following steps:

Step S1, by mapping the circular semiconductor thin layer to a simple structure, combined with the definition of sheet resistance, obtain the sheet resistance R _sq of the circular semiconductor thin layer;

Step S2, applying a constant current to the two metal electrodes on the same side of the first semiconductor resistance strip, and then measuring the voltage between the two metal electrodes on the other side, the ratio of the voltage to the current is the resistance R ₁ ;

Step S3, applying a constant current to the two metal electrodes on the same side of the second semiconductor resistance strip, and then measuring the voltage between the two metal electrodes on the other side, and the ratio of the voltage to the current is the resistance _RA ;

Step S4, according to the resistance R ₁ , the relationship between the sheet resistance R _sq and the geometric dimension of the second semiconductor resistance strip, according to the relationship between the thickness of the first semiconductor resistance strip and the geometric dimension of the step, and according to the resistance R ₁ , The relationship between the sheet resistance R _sq and the geometric size of the first semiconductor resistance strip is established by formula group (1), and the expression is:

In formula group (1), W represents the width of the second semiconductor resistance strip, R _sq represents the sheet resistance, R ₁ represents the resistance of the first semiconductor resistance strip, L ₁ represents the effective length of the second semiconductor resistance strip, R _A Represents the resistance of the second semiconductor resistor strip, S ₁ represents the length of the top surface of the groove, S ₂ represents half the length of the step, S ₃ represents the length of the side wall of the groove, β represents the angle between the side wall of the groove and the bottom surface of the groove , t ₁ represents the thickness of the first semiconductor resistance strip, x is an intermediate variable introduced, which has no specific physical meaning, just to make the formula (1) appear concise and clear, γ represents the correction factor of the corner resistance, and n represents the step quantity;

Step S5: Substitute the sheet resistance R _sq obtained in step S1, the resistance R1 obtained in step S2, and the resistance _RA obtained in step S3 into the formula group ( ₁ ), obtained by measuring: the resistance of the second semiconductor resistance strip. Effective length L ₁ , groove top length S ₁ , half step length S ₂ , groove side wall length S ₃ , number n of steps, correction factor γ for corner resistance, and groove side walls and groove bottom The included angle β of is substituted into the formula group (1) to obtain the thickness of the semiconductor conductive film.

Further, the step S1 specifically includes:

Step S101, applying a constant current between the first contact electrode and the fourth contact electrode, and measuring the voltage between the first contact electrode and the fourth contact electrode, the ratio of the voltage to the current is the resistance _Ra ;

Step S102, applying a constant current between the first contact electrode and the fourth contact electrode, and measuring the voltage between the second contact electrode and the fourth contact electrode, the ratio of the voltage to the current is the resistance R _b ;

Step S103 , according to the mapping from the circular semiconductor thin layer to the simple structure and the definition of the sheet resistance, formula group (2) is established:

In formula group (2), P, Q, S and T all represent intermediate quantities, α is an unknown number, and represents the opening angle formed by the four contact electrodes and the circular semiconductor thin layer, i is an imaginary unit, K[ ] represents the first kind of elliptic integral function, R _sq represents the sheet resistance of the circular semiconductor thin layer, g _a (α) and g _b (α) represent functions only related to the opening angle α;

Step S103: Substitute the resistance R _{a obtained in step S101 and the resistance R b obtained} in step S102 into the formula group (2), and obtain the opening angle α formed by the four contact electrodes and the circular semiconductor thin layer;

Step S104: Substitute the opening angle α obtained in step S103 into formula (3) to obtain the sheet resistance R _sq , and the expression of formula (3) is:

In formula (3), g _a (α) represents a function only related to the opening angle α, i is an imaginary unit, and P, Q, S, and T all represent intermediate quantities.

Further, in the step S5, the thickness of the semiconductor conductive film is expressed as:

The beneficial effects of the present invention are:

1. The test method provided by the present invention is simple, the test equipment requirements are low, and the test process and test parameter values are stable. The processing process is synchronized with the micro-electromechanical device, there is no special processing requirements, and it fully meets the requirements of online testing. Calculation methods are limited to simple mathematical formulas.

2. In the present invention, the semiconductor climbs over multiple steps of the sacrificial layer, and the random errors in the manufacturing process of the steps are averaged by using the multiple steps; the value of the resistance change is increased by using the multiple steps, which is convenient for measurement. The measurement uses the four-probe method to test two semiconductor resistors. Finally, combined with the sheet resistance obtained from the circular thin-layer structure, the thickness of the semiconductor is calculated.

Description of drawings

FIG. 1 is a schematic structural diagram of a circular semiconductor thin layer.

FIG. 2 is a schematic structural diagram of a four-probe resistance test bridge structure.

FIG. 3 is an enlarged cross-sectional view of a single stepped structure.

In the attached picture:

101-first contact electrode, 102-second contact electrode, 103-third contact electrode, 104-fourth contact electrode, 105-round semiconductor thin layer, 106-second semiconductor resistance strip, 107-groove, 108 - The first semiconductor resistance strips, 109, 110, 111, 112, 113 and 114 all represent anchor regions, 115 - metal electrode, 116 - semiconductor layer, 117 - dielectric layer, 118 - insulating substrate.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

Referring to FIG. 1 , FIG. 2 and FIG. 3 , this embodiment provides an on-line test structure for the thickness of a semiconductor conductive thin film, including a circular semiconductor thin layer 105 , a first contact electrode 101 , a second contact electrode 102 , a third contact electrode 103 and The fourth contact electrode 104, the four contact electrodes are evenly arranged on the peripheral side of the circular semiconductor thin layer 105 and are electrically connected to the circular semiconductor thin layer 105, and the opening angle formed by the four contact electrodes and the circular semiconductor thin layer 105 is α; specifically, the circular semiconductor thin layer 105 is used to measure sheet resistance, and the first to fourth contact electrodes are used to apply current and measure voltage.

The semiconductor conductive thin film thickness on-line test structure also includes: a four-probe resistance test bridge structure and a continuous ladder structure. The four-probe resistance test bridge structure is set on the surface of the dielectric layer 117, the dielectric layer 117 is set on the insulating substrate 118, the dielectric A part of the surface of the layer 117 is etched into n parallel and identical grooves 107. Please refer to FIG. 3 for details. Steps are formed between the grooves 107, and the steps have the same length. The surface of the dielectric layer 117 has the same angle β, and the n grooves 107 and the interdependent steps together form the above-mentioned continuous step structure.

The four-probe resistance test bridge structure includes a first four-probe semiconductor resistance bridge and a second four-probe semiconductor resistance bridge.

Specifically, the first four-point probe semiconductor resistance bridge and the second four-point probe semiconductor resistance bridge each include a semiconductor resistance bar and four metal electrodes 115 for performing four-point probe measurement. In addition, the first four-point probe semiconductor resistance bridge and the second four-point probe semiconductor resistance bridge share two metal electrodes 115 , and in the Cartesian coordinate system, the semiconductor resistance bars and the x-axis direction are parallel. More specifically, the first four-probe semiconductor resistance bridge includes a first semiconductor resistance bar 108 and four metal electrodes 115. Both sides of the leftmost end of the first semiconductor resistance bar 108 are electrically connected to a metal electrode 115. Both sides of the rightmost end of the resistor bar 108 are electrically connected to one metal electrode 115 , totaling four metal electrodes 115 , and the middle part of the first semiconductor resistor bar 108 climbs the continuous ladder structure.

The second four-probe semiconductor resistance bridge includes a second semiconductor resistance bar 106 and two metal electrodes 115, the second semiconductor resistance bar 106 is disposed at the rightmost end of the first semiconductor resistance bar 108 and is connected to the first semiconductor resistance bar 108, and It is arranged on the surface of the flat dielectric layer 117 . A metal electrode 115 is provided on both sides of the rightmost end of the second semiconductor resistance bar 106 , and the leftmost end of the second semiconductor resistance bar 106 uses the two metal electrodes 115 at the rightmost end of the first semiconductor resistance bar 108 . More specifically, the length of the first semiconductor resistance strip 108 and the second semiconductor resistance strip 106 along the y-axis direction is W, and the design dimension of the groove 107 along the y-axis direction is greater than 3 times the W value of the semiconductor resistance strip, The length in the x-axis direction is S ₁ , and the effective length of the second semiconductor resistance strip 106 is L ₁ .

Specifically, the metal electrodes 115 in this embodiment are disposed on the corresponding six anchor regions, and the six anchor regions are formed by etching the surface of the dielectric layer 117. In this embodiment, the four-probe resistance test bridge structure The three anchor areas on the lower side are from left to right: anchor area 109, anchor area 110, anchor area 111; the three anchor areas on the lower side of the four-probe resistance test bridge structure are from right to left, in order: : Anchor area 112, Anchor area 113, Anchor area 114.

Referring to FIG. 3, FIG. 3 is an enlarged AA cross-sectional view of a single groove structure, 118 is an insulating substrate, on which a dielectric layer 117 is deposited with a thickness of t ₂ , and the groove 107 is etched, and its design size is along The length in the x-axis direction is S ₁ . Due to process limitations, the sidewall of the groove 107 is inclined at a certain angle, which is denoted as β. A layer of semiconductor layer 116 with a thickness of _t1 is deposited, climbs over the steps at the groove 107, and forms a symmetrical structure with the vertical midline of the groove 107 as the symmetry axis. The symmetrical structure includes the following parts: on the surfaces of the unetched dielectric layer 117 on both sides of the groove 107, there is a semiconductor resistance strip with a length of S ₂ ; 1-2x semiconductor resistance strips _; the side walls of the two grooves 107 are respectively covered by a semiconductor resistance strip with a length of S ₃ , and are connected with the front two parts through four corner semiconductor resistances. By connecting n number of ladder structures shown in FIG. 3 in series, the continuous ladder structure in FIG. 2 is obtained.

Example 2

Referring to FIG. 1 and FIG. 2 , this embodiment provides an on-line test method for the thickness of a semiconductor conductive film. The method of this embodiment is implemented based on the test structure in Embodiment 1, and specifically includes the following steps:

Step S1, by mapping the circular semiconductor thin layer 105 to a simple structure, and then combining with the definition of the sheet resistance, obtain the sheet resistance R _sq of the circular semiconductor thin layer 105;

In step S1, the four-probe method is specifically used for measurement, which specifically includes:

Step S101, applying a constant current between the first contact electrode 101 and the fourth contact electrode 104, and measuring the voltage between the first contact electrode 101 and the fourth contact electrode 104, the ratio of the voltage to the current is the resistance _Ra ;

Step S102, applying a constant current between the first contact electrode 101 and the fourth contact electrode 104, and measuring the voltage between the second contact electrode 102 and the fourth contact electrode 104, the ratio of the voltage to the current is the resistance _Rb ;

Step S103, according to the mapping from the circular semiconductor thin layer 105 to the simple structure and the definition of the sheet resistance, establish the following formula group:

In the formula group, P, Q, S, and T all represent intermediate quantities, α is an unknown number, and represents the opening angle formed by the four contact electrodes and the circular semiconductor thin layer 105, i is an imaginary unit, and K[ ] represents the first A class of elliptic integral functions, R _sq represents the sheet resistance of the circular semiconductor thin layer 105, g _a (α) and g _b (α) represent functions only related to the opening angle α;

Step S103: Substitute the resistance R _{a obtained in step S101 and the resistance R b obtained} in step S102 into the above formula group, and obtain the opening angle α formed by the four contact electrodes 101-104 and the circular semiconductor thin layer 105;

Step S104: Substitute the opening angle α obtained in step S103 into the following formula to obtain the sheet resistance R _sq , the expression of which is:

In the formula, ga (α) represents _a function only related to the opening angle α, i is an imaginary unit, and P, Q, S and T all represent intermediate quantities.

Step S2, apply a constant current between the anchor region 109 and the anchor region 110 of the first semiconductor resistance strip 108, and then measure the voltage between the anchor region 113 and the anchor region 114 on the other side, and the ratio of the voltage to the current is the resistance R ₁ ;

Step S3, applying a constant current between the anchor region 112 and the anchor region 113 of the second semiconductor resistance strip 106, and then measuring the voltage between the anchor region 110 and the anchor region 111, and the ratio of the voltage to the current is the resistance _RA ;

Step S4, according to the resistance R ₁ , the sheet resistance R _sq and the geometrical dimension relationship of the second semiconductor resistance strip 106 , according to the thickness of the first semiconductor resistance strip 108 and the geometric dimension relationship of the steps, and according to the resistance R ₁ , the square resistance R _sq The relationship with the geometric size of the first semiconductor resistance strip 108 is established, and a formula group is established, and the expression is:

In the formula group, W represents the width of the second semiconductor resistance strip 106, R _sq represents the sheet resistance, R ₁ represents the resistance of the first semiconductor resistance strip 108, L ₁ represents the effective length of the second semiconductor resistance strip 106, and R _A represents the first semiconductor resistance strip 106. The resistance of the _two semiconductor resistance strips 106, S1 represents the length of the top surface _of the groove 107, S2 represents half the length _of the step, S3 represents the length of the sidewall of the groove 107, β represents the sidewall of the groove 107 and the bottom surface of the groove 107 , t ₁ represents the thickness of the first semiconductor resistance strip 108, x is an intermediate variable introduced, which has no specific physical meaning, just to make the formula (1) appear concise and clear, γ represents the correction factor of the corner resistance, n represents the number of steps;

Step S5: Substitute the sheet resistance R _sq obtained in step S1, the resistance R1 obtained in step S2, and the resistance _RA obtained in step S3 into the formula group ( ₁ ), obtained by measuring: the effective value of the second semiconductor resistance strip 106 The length L ₁ , the length S ₁ of the top surface of the groove 107 , the half of the step length S ₂ , the length S ₃ of the side walls of the groove 107 , the number n of the steps, the correction factor γ of the corner resistance, and the side walls of the groove 107 and the groove 107 . The included angle β of the bottom surface of the groove 107 is substituted into the formula set established in step S4 to obtain the thickness of the semiconductor conductive film, and the expression is:

To sum up, the testing method of the present invention is simple, using a simple DC current source as the excitation source, and using common voltage testing equipment to complete all excitation and testing processes. The test structure was completed using a basic MEMS process.

Referring to FIG. 3 , the fabrication process of the test structure is illustrated below with a typical two-layer semiconductor MEMS surface processing process.

An N-type semiconductor silicon wafer is selected, a silicon dioxide layer with a thickness of 100 nanometers is thermally grown, and a layer of silicon nitride with a thickness of 500 nanometers is deposited by a low pressure chemical vapor deposition process to form an insulating substrate 118 . A layer of 300 nm semiconductor is deposited by a low pressure chemical vapor deposition process and heavily doped with N type to make this layer of semiconductor a conductor, and a part of the anchor region (109-114) is formed by etching through a photolithography process. The dielectric layer 117 with a thickness of 2000 nm is deposited by a low pressure chemical vapor deposition process, and the patterns of the anchor regions (109-114) and the grooves 107 are formed by a photolithography process.

A layer of semiconductor layer 116 with a thickness of 1500 nanometers is deposited by a low pressure chemical vapor deposition process, N-type heavy doping is performed on the semiconductor layer 116, and a photolithography process is used to form a semiconductor test structure pattern and anchor regions (109-114), anchor regions (109 The thickness of -114) is the sum of the thicknesses of the two semiconductors.

The parts that are not described in detail in the present invention are known techniques of those skilled in the art.

The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the prior art according to the concept of the present invention shall fall within the protection scope determined by the claims.

Claims (6)

1. The thickness online test structure for the semiconductor conductive thin film comprises a circular semiconductor thin layer and first to fourth contact electrodes, wherein the four contact electrodes are uniformly arranged on the peripheral side of the circular semiconductor thin layer and are electrically connected with the circular semiconductor thin layer, and the opening angle formed by the four contact electrodes and the circular semiconductor thin layer is alpha; it is characterized by also comprising: the four-probe resistance testing bridge structure is arranged on the surface of the dielectric layer, a part of the surface of the dielectric layer is etched into a plurality of mutually parallel and same grooves, steps are formed among the grooves and have the same length, the grooves and the corresponding steps form a continuous stepped structure together, and the two side walls of the grooves and the surface of the dielectric layer have the same included angle; the four-probe resistance test bridge structure includes a first four-probe semiconductor resistance bridge and a second four-probe semiconductor resistance bridge, wherein,

the first four-probe semiconductor resistance bridge comprises a first semiconductor resistance strip and four metal electrodes, wherein one metal electrode is electrically connected to each side of the two ends of the first semiconductor resistance strip, the middle part of the first semiconductor resistance strip climbs over the continuous ladder structure, one end of the first semiconductor resistance strip is connected with the round semiconductor thin layer to form an integral structure, and the other end of the first semiconductor resistance strip is connected with the second four-probe semiconductor resistance bridge;

the second four-probe semiconductor resistance bridge comprises a second semiconductor resistance strip and two metal electrodes, wherein the second semiconductor resistance strip is arranged at the other end of the first semiconductor resistance strip and is connected with the first semiconductor resistance strip, the second semiconductor resistance strip and the first semiconductor resistance strip share the two metal electrodes, the second semiconductor resistance strip is arranged on the surface of a flat dielectric layer, and the second semiconductor resistance strip and the first semiconductor resistance strip have the same width.

2. The structure of claim 1, wherein the metal electrode is disposed on an anchor region formed by etching a surface of the dielectric layer.

3. The structure of claim 2, wherein the dielectric layer is disposed on the insulating substrate.

4. A method for testing a semiconductor conductive film thickness on-line test structure according to any one of claims 1-3, comprising the steps of:

step S1, obtaining the square resistance R of the circular semiconductor thin layer by mapping the circular semiconductor thin layer to a simple structure and combining the definition of the square resistance_sq；

Step S2, applying constant current to the two metal electrodes on the same side of the first semiconductor resistor strip, and measuring the voltage between the two metal electrodes on the other side, wherein the ratio of the voltage to the current is the resistor R₁；

Step S3, applying constant current to the two metal electrodes on the same side of the second semiconductor resistor strip, and measuring the voltage between the two metal electrodes on the other side, wherein the ratio of the voltage to the current is the resistor R_A；

Step S4, according to the resistance R₁Square resistance R_sqThe geometrical relation with the second semiconductor resistor strip, the geometrical relation between the thickness of the first semiconductor resistor strip and the step, and the relation between the resistance R₁Square resistance R_sqEstablishing a formula set (1) according to the relation of the geometric dimension of the first semiconductor resistor strip, wherein the formula is as follows:

in the formula group (1), W represents the width of the second semiconductor resistor strip, R_sqDenotes the square resistance, R₁Representing the resistance, L, of the first semiconducting resistor strip₁Representing the effective length, R, of the second semiconducting resistive track_ARepresenting the resistance, S, of the second semiconductor resistor strip₁Indicates the length of the top surface of the groove, S₂Representing half the length of the step, S₃Indicating the length of the side wall of the grooveBeta represents the angle between the side wall and the bottom of the groove, t₁The thickness of the first semiconductor resistor strip is expressed, an intermediate variable is introduced, no specific physical significance is realized, gamma is expressed as a correction factor of corner resistance, and n is expressed as the number of steps;

step S5, the sheet resistance R obtained in step S1_sqResistance R obtained in step S2₁And the resistance R obtained in step S3_ASubstituting into said set of equations (1), obtained by measuring: effective length L of second semiconductor resistor strip₁Length S of the top surface of the groove₁Half of step length S₂Length S of side wall of groove₃The number n of the steps, the correction factor gamma of the corner resistor and the included angle beta of the side wall of the groove and the bottom surface of the groove are substituted into the formula set (1) to obtain the thickness of the semiconductor conductive film.

5. The method as claimed in claim 4, wherein the step S1 specifically comprises:

step S101, applying a constant current between the first contact electrode and the fourth contact electrode, and measuring a voltage between the first contact electrode and the fourth contact electrode, wherein the ratio of the voltage to the current is a resistor R_a；

Step S102, applying a constant current between the first contact electrode and the fourth contact electrode, and measuring a voltage between the second contact electrode and the fourth contact electrode, wherein the ratio of the voltage to the current is a resistor R_b；

Step S103, establishing a formula set (2) according to the mapping from the circular semiconductor thin layer to the simple structure and the definition of the square resistance:

in formula group (2), P, Q, S and T both represent intermediate quantities, α is an unknown number, and represents the opening angle formed by the four contact electrodes and the circular semiconductor thin layer, and i is an imaginary unit，K[·]Representing an elliptic integral function of the first kind, R_sqDenotes the square resistance, g, of a circular semiconductor thin layer_a(. alpha.) and g_b(α) represents a function related only to the opening angle α;

step S103, the resistor R obtained in step S101_aAnd the resistance R obtained in step S102_bSubstituting the four contact electrodes into a formula group (2) to obtain the opening angle alpha formed by the four contact electrodes and the circular semiconductor thin layer;

step S104, substituting the opening angle alpha obtained in step S103 into formula (3) to obtain the square resistance R_sqThe expression of formula (3) is:

in the formula (3), g_aAnd (alpha) represents a function related to the opening angle alpha only, i is an imaginary unit, and P, Q, S and T both represent intermediate quantities.

6. The method as claimed in claim 5, wherein in step S5, the semiconductor conductive film thickness is expressed as:

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