CN112320754B - Online testing structure and method for line width of semiconductor conductive film - Google Patents

Abstract

The invention discloses an online test structure and method for line width of a semiconductor conductive film, wherein a round semiconductor film integrally connected with one end side of the semiconductor conductive film to be tested is prepared, four contact electrodes are arranged on the periphery of the round semiconductor film, and the opening angle of the contact electrodes is measured and calculated by adopting an improved four-point probe method, so that the semiconductor square resistance of the semiconductor film is further obtained. And then, applying voltage to the semiconductor conductive film to be tested, calculating the resistance value by measuring the current between the two electrodes, and finally obtaining the width value of the line width of the semiconductor conductive film according to the relation between the resistance and the geometric dimension of the semiconductor conductive film to be tested. The test structure of the invention is completed by adopting a basic micro-electromechanical processing technology, and the processing process is synchronous with the micro-electromechanical device, thereby meeting the requirement of on-line test. The test process adopts a simple direct current source as an excitation source, and can complete all excitation and test processes by adopting common voltage test equipment.

Description

An online testing structure and method for the line width of semiconductor conductive films

Technical field

The invention relates to an online testing structure and method for semiconductor conductive film line width.

Background technique

The film line width of microelectromechanical thin film devices is an important parameter affecting device performance. By measuring the line width of the film online, the size of the device can be obtained and the accuracy of the device can be controlled.

Semiconductors are important materials used in surface micromachining. The basic process of processing is: first deposit a layer of material on the silicon wafer, called a sacrificial layer. Then photolithography defines the pattern layer, and then uses chemical vapor deposition and other methods to create a structural layer film on the sacrificial layer. Finally, the sacrificial layer is removed by etching to separate the movable part of the micro component 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 microelectromechanical products hope to be able to monitor the line width of semiconductor conductive films online and reflect process errors in the manufacturing process in real time. Therefore, online testing of microelectromechanical products without leaving the processing environment and using convenient equipment has become a necessary means to control the process.

Contents of the invention

Objective of the invention: In view of the above-mentioned existing technology, an online testing structure and method for the line width of semiconductor conductive films is proposed.

Technical solution: an online testing method for the line width of semiconductor conductive films. In the Cartesian coordinate system, the semiconductor conductive film to be measured on the surface of the flat dielectric layer is parallel to the x-axis direction, the effective length is L ₁ and the width is W; so The method described includes the following steps:

Step 1: Prepare a circular semiconductor film on one end side of the semiconductor conductive film to be measured, and the circular semiconductor film and the semiconductor conductive film to be measured are connected into an integrated structure;

Step 2: Make two anchor areas at intervals on the insulating substrate on both sides of the semiconductor conductive film to be tested along the x-axis direction;

Step 3: Prepare metal electrodes connected to the semiconductor conductive film to be measured in the anchor area;

Step 4: Prepare first to fourth contact electrodes at intervals along the circumference of the circular semiconductor film, and the opening angle of the connection between the first to fourth contact electrodes and the circular semiconductor film is α;

Step 5: Use the first to fourth contact electrodes to measure the semiconductor sheet resistance R _sq of the circular semiconductor film using an improved four-point probe method;

Step 6: Apply a constant current to the two metal electrodes on the same side of the semiconductor conductive film to be measured along the x-axis direction, and measure the voltage between the two metal electrodes on the other side. The ratio of the voltage to the current is the resistance _RA ;

Step 7: Calculate the width of the semiconductor conductive film to be tested according to the following formula:

Further, the step 5 includes the following specific steps:

Step 501: Apply a constant current between the first contact electrode and the fourth contact electrode, and measure 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 502: Apply a constant current between the first contact electrode and the fourth contact electrode, measure the voltage between the second contact electrode and the fourth contact electrode, and the ratio of the voltage to the current is the resistance R _b ;

Step 503: Calculate the semiconductor sheet resistance R _sq according to the following formula:

In the formula, i is the imaginary unit, P, Q, S, and T are all intermediate quantities, specifically:

Among them, K[·] is the complete elliptic integral function of the first kind; substitute the measured R _a and R _b into the following equations to solve for α:

R _a /R _b = g _a (α)/g _b (α)

in:

An online test structure for the line width of a semiconductor conductive film, including a semiconductor conductive film to be tested, four metal electrodes, a circular semiconductor film, and first to fourth contact electrodes; the semiconductor conductive film to be tested is located on the surface of a flat dielectric layer; The four metal electrodes are arranged in pairs on anchor areas on both sides of the semiconductor conductive film to be measured along the length direction, and the metal electrodes are electrically connected to the semiconductor conductive film to be measured; the circular semiconductor film Disposed on one end side of the semiconductor conductive film to be measured, and connected with the semiconductor conductive film to be measured into an integrated structure; the first to fourth contact electrodes are evenly disposed on the peripheral side of the circular semiconductor film, and connected with the semiconductor conductive film to be measured. The opening angle of the circular semiconductor film connection is α.

Further, the anchor area is provided on an insulating substrate.

Further, the opening angle α ranges from 30° to 45°.

Beneficial effects: The test structure of the present invention is completed using basic micro-electromechanical processing technology. The processing process is synchronized with the micro-electromechanical device. There are no special processing requirements and it fully meets the requirements of online testing. The test process uses a simple DC current source as the excitation source, and only requires ordinary voltage test equipment to complete all excitation and test processes. The test equipment requirements are low, and the test process and test parameter values are stable.

Description of the drawings

Figure 1 is a schematic diagram of the online measurement structure of the semiconductor conductive film line width of the present invention.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

As shown in Figure 1, an online measurement structure for the line width of a semiconductor conductive film includes a semiconductor conductive film to be measured 101, four metal electrodes 103, a circular semiconductor film 201, and first to fourth contact electrodes 201 to 205. The semiconductor conductive film 101 to be tested is located on the surface of the flat dielectric layer. Four metal electrodes 103 are arranged in pairs on anchor areas 102 on both sides of the semiconductor conductive film 101 to be tested along the length direction. The anchor areas 102 are arranged on the insulating substrate. The metal electrode 103 is electrically connected to the semiconductor conductive film 101 to be tested. The circular semiconductor film 201 is disposed on one end side of the semiconductor conductive film 101 to be tested, and is connected with the semiconductor conductive film 101 to be tested to form an integrated structure. The first to fourth contact electrodes 201 to 205 are evenly arranged on the peripheral side of the circular semiconductor film 201, and the opening angle connected to the circular semiconductor film 201 is α, and the size of α is 30°≤α≤45°.

An online measurement method for the line width of semiconductor conductive films. In the Cartesian coordinate system, the semiconductor conductive film 101 to be measured on the surface of the flat dielectric layer is parallel to the x-axis direction, the effective length is L ₁ and the width is W; the method includes the following step:

Step 1: Prepare a circular semiconductor film 201 on one end side of the semiconductor conductive film 101 to be tested, and the circular semiconductor film 201 and the semiconductor conductive film 101 to be tested are connected to form an integrated structure.

Step 2: Make two anchor areas 102 at intervals on the insulating substrate on both sides of the semiconductor conductive film 101 to be tested along the x-axis direction.

Step 3: Prepare metal electrodes 103 connected to the semiconductor conductive film 101 to be tested in the anchor area 102 respectively.

Step 4: Prepare first to fourth contact electrodes 201 to 205 on the circumferential side of the circular semiconductor film 201 at intervals along the circumference. The opening angle of the connection between the first to fourth contact electrodes 201 to 205 and the circular semiconductor film 201 is α.

Step 5: Use the first to fourth contact electrodes 201 to 205 to measure the semiconductor sheet resistance R _sq of the circular semiconductor film 201 using the four-point probe method, including the following specific steps:

Step 501: Apply a constant current between the first contact electrode 201 and the fourth contact electrode 204, and measure the voltage between the first contact electrode 201 and the fourth contact electrode 204. The ratio of the voltage to the current is the resistance _Ra ;

Step 502: Apply a constant current between the first contact electrode 201 and the fourth contact electrode 204, and measure the voltage between the second contact electrode 202 and the fourth contact electrode 204. The ratio of the voltage to the current is the resistance R _b ;

Step 503: Through the definition of sheet resistance, the expressions of resistance R _a and R _b can be obtained:

R _sq is the semiconductor sheet resistance, g _a (α) and g _b (α) are functions only related to the contact electrode opening angle α. By mapping the circular semiconductor film structure to a simple structure, g a (α) and g _b (α) can be obtained The expression of g _b (α) is as follows:

In the formula, i is the imaginary unit, P, Q, S, and T are all intermediate quantities, specifically:

Among them, K[·] is the elliptic integral function of the first kind;

Substitute the measured R _a and R _b into equation (2), and solve α according to the following equation:

R _a /R _b = g _a (α)/g _b (α) (3)

Then substitute the obtained α into the following formula to calculate the semiconductor sheet resistance R _sq :

Step 6: Apply a constant current to the two metal electrodes 103 on the same side of the semiconductor conductive film 101 to be tested along the x-axis direction, and measure the voltage between the two metal electrodes 103 on the other side. The ratio of the voltage to the current is the resistance _RA .

Step 7: Based on the relationship between the resistance and geometric dimensions of the semiconductor conductive film to be measured, calculate the width of the semiconductor conductive film 101 to be measured according to the following formula:

The following uses a typical two-layer semiconductor MEMS surface processing process to illustrate the fabrication process of the test structure.

Select an N-type semiconductor silicon wafer, thermally grow a 100-nanometer-thick silicon dioxide layer, and deposit a 500-nanometer-thick silicon nitride layer through a low-pressure chemical vapor deposition process to form an insulating substrate. A low-pressure chemical vapor deposition process is used to deposit a layer of 300-nanometer semiconductor and is heavily doped with N-type to make this layer of semiconductor a conductor. A part of the anchor region 102 is formed by etching through a photolithography process. A low-pressure chemical vapor deposition process is used to deposit dielectric layers with a thickness of 2000 nanometers, and the pattern of the anchor region 102 is formed through a photolithography process. A low-pressure chemical vapor deposition process is used to deposit a layer of semiconductor with a thickness of 1500 nanometers, and the semiconductor is heavily doped with N-type. The photolithography process forms the semiconductor test structure pattern 101 and the anchor area 102. The thickness of the anchor area is between the thickness of the two semiconductors. and. A stripping process is used to form a pattern of the metal electrode 103 on the anchor area 102, and finally the structure is released by etching the dielectric layer.

The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications can also be made. should be regarded as the protection scope of the present invention.

Claims (4)

1. Semiconductor deviceThe on-line test method of the line width of the conductive film is characterized in that in a Cartesian coordinate system, a semiconductor conductive film (101) to be tested on the surface of a flat dielectric layer is parallel to the x-axis direction, and the effective length is L ₁ The width is W; the method comprises the following steps:

step 1: preparing a circular semiconductor film (201) at one end side of a semiconductor conductive film (101) to be tested, wherein the circular semiconductor film (201) and the semiconductor conductive film (101) to be tested are connected into an integrated structure;

step 2: two anchor areas (102) are respectively manufactured on the insulating substrates at two sides of the semiconductor conductive film (101) to be tested along the x-axis direction at intervals;

step 3: preparing metal electrodes (103) connected with the semiconductor conductive film (101) to be tested in the anchor areas (102) respectively;

step 4: first to fourth contact electrodes (202 to 205) are sequentially prepared at intervals along the circumference on the circumferential side of the circular semiconductor film (201), and the opening angle of the connection of the first to fourth contact electrodes (202 to 205) and the circular semiconductor film (201) is alpha;

step 5: the semiconductor sheet resistance R of the circular semiconductor film (201) is measured by the improved four-point probe method by using the first to fourth contact electrodes (202 to 205) _sq ；

Step 6: applying constant current to two metal electrodes (103) on the same side of the semiconductor conductive film (101) to be tested along the x-axis direction, measuring the voltage between the two metal electrodes (103) on the other side, wherein the ratio of the voltage to the current is the resistor R _A ；

Step 7: the width of the semiconductor conductive film (101) to be measured is calculated according to the following formula:

the step 5 comprises the following specific steps:

step 501: measuring a first contact by applying a constant current between the first contact electrode (202) and the fourth contact electrode (205)The voltage between the electrode (202) and the fourth contact electrode (205) is the ratio of the voltage to the current is the resistance R _a ；

Step 502: applying a constant current between the first contact electrode (202) and the fourth contact electrode (205), measuring the voltage between the second contact electrode (203) and the fourth contact electrode (205), the ratio of the voltage to the current being the resistance R _b ；

Step 503: the semiconductor square resistance R is calculated according to the following formula _sq ：

Wherein i is an imaginary unit, P, Q, S, T is an intermediate amount, and specifically:

wherein K [. Cndot.]A complete elliptic integral function of the first class; r is measured _a And R is _b Substituting the following equation to solve α:

R _a /R _b ＝g _a (α)/g _b (α)

wherein:

2. an on-line test structure of the line width of a semiconductor conductive film is characterized by comprising a semiconductor conductive film (101) to be tested, four metal electrodes (103), a round semiconductor film (201) and first to fourth contact electrodes (202-205); the semiconductor conductive film (101) to be tested is positioned on the surface of the flat dielectric layer; the four metal electrodes (103) are arranged on anchor areas (102) on two sides of the semiconductor conductive film (101) to be tested along the length direction at intervals, and the metal electrodes (103) are electrically connected with the semiconductor conductive film (101) to be tested; the round semiconductor film (201) is arranged at one end side of the semiconductor conductive film (101) to be tested and is connected with the semiconductor conductive film (101) to be tested into an integrated structure; the first to fourth contact electrodes (202 to 205) are uniformly arranged on the peripheral side of the circular semiconductor film (201), and the opening angle of the connection with the circular semiconductor film (201) is alpha.

3. The on-line test structure of a semiconductor conductive film line width according to claim 2, wherein the anchor region (102) is disposed on an insulating substrate.

4. The on-line test structure of a line width of a semiconductor conductive film according to claim 2, wherein the opening angle α is 30 ° to 45 °.