CN111060029A - Curvature radius measuring device and measuring method thereof - Google Patents

Abstract

The invention relates to a curvature radius measuring device and a measuring method thereof, wherein the curvature radius measuring device comprises a sample stage, a diffraction light array generating module and a detection and analysis module, the diffraction light array generating module generates and emits a diffraction light array to a sample, the diffraction light array is reflected by the surface of the sample to emit a reflection light array after reaching the surface of the sample, and the detection and analysis module receives the reflection light array and obtains the curvature radius of the sample according to the size of the received reflection light array. The invention designs a mathematical model for measuring the curvature radius by using the diffraction light array by utilizing the characteristic that the array size is different when the distance between the diffraction light array and the light source is different, and realizes the curvature radius measuring device which has simple structure, high measuring speed and lower requirements on hardware such as a laser, a sensor and the like on the basis of the mathematical model.

Description

Curvature radius measuring device and measuring method

technical field

The invention relates to the technical field of thin film measurement, in particular to a curvature radius measurement device and a measurement method thereof.

Background technique

Thin film technology is widely used in optical, electrical, material and other technical fields, but in the process of film manufacturing, physical vapor deposition and other preparation processes will cause large residual stress inside the formed film, and the residual stress will cause the film to bend or even When the device fails, the curvature radius of the thin film is the most direct way to evaluate the residual stress. Therefore, after the thin film is formed, measuring its curvature radius is a key thin film measurement step.

The single-spot line scanning method is a relatively mature method for measuring the curvature radius of thin films. The measuring beam is reflected by the deformed sample surface, and after optical path amplification, the offset position is collected to calculate the equivalent curvature radius of the sample. The light point line scanning method needs to measure multiple groups (usually more than 10 groups) of data before calculating the value of the radius of curvature once. A single measurement takes more than 20 seconds, and multiple groups of measurement data are susceptible to interference such as environmental vibration, which affects the measurement results. .

In order to solve the measurement time and accuracy problems of the single-spot line scanning method, the researchers proposed the parallel light array method. By changing the measurement beam to a parallel light array, the radius of curvature of the sample can be calculated through one data acquisition, and it avoids the need for The effect of environmental disturbances on measurement accuracy. However, the parallel light array method requires high-quality parallel light spot arrays, which requires higher design of optical devices. The manufacturing cost of the optical device Etalon, which is most commonly used to generate parallel light arrays, is high, and the brightness of the generated beam ends is low. Therefore, there are high requirements on the laser intensity, sensor sensitivity and reflectivity of the sample surface.

SUMMARY OF THE INVENTION

Based on this, it is necessary to provide a curvature radius measurement device and a measurement method for the problems that the existing curvature radius measurement methods have high requirements on laser intensity, sensor sensitivity and reflectivity of the sample surface.

In order to realize the purpose of the present invention, the present invention adopts following technical scheme:

A curvature radius measuring device, comprising:

Sample stage, used to carry the sample to be measured;

a diffracted light array generating module, used for generating and emitting a diffracted light array to the sample;

The detection and analysis module is configured to receive the reflected light array emitted by the sample, and obtain the radius of curvature of the sample according to the size of the received reflected light array.

In one embodiment, the detection and analysis module includes:

a sensor imaging screen, used for receiving the reflected light array emitted by the sample, and converting the light signal of the reflected light array into an electrical signal;

The analysis unit is electrically connected to the sensor imaging screen, and is used for acquiring the curvature radius of the sample according to the electrical signal.

In one embodiment, the emission direction of the diffracted light array is perpendicular to the sample stage, and the radius of curvature of the sample is calculated according to the following formula:

in,

R is the radius of curvature of the sample;

S is the length of the first path of the diffracted light array from the diffracted light array generating module to the sample surface;

H is the length of the second path of the reflected light array from the sample surface to the sensor imaging screen;

β is the divergence angle of the diffracted light array;

D is the distance between the actual landing point and the set landing point of the reflected light array on the detector.

In one of the embodiments, the curvature radius measuring device further includes a semi-reflective and semi-mirror sheet, the semi-reflective and semi-mirror sheet is arranged between the diffractive light array generating module and the sample stage, and the semi-reflective and semi-mirror sheet is The included angle with the sample stage is 45°;

The diffracted light array passes through the semi-reflection and semi-mirror sheet to reach the surface of the sample, and is then reflected by the sample surface and the semi-reflection and semi-mirror sheet, and is projected on a sensor imaging screen arranged perpendicular to the sample stage.

In one embodiment, the sample stage includes:

table top, used to carry the sample to be measured;

A two-dimensional motion mechanism is used to drive the table top to move horizontally.

In one embodiment, the diffractive light array generating module includes:

a laser for emitting the initial probe beam;

A diffractive optical lens is used to convert the initial probe beam into a diffractive light array.

The technical scheme of the present invention also provides a method for measuring the radius of curvature, including:

Place the sample on the sample stage;

emitting an array of diffracted light onto the surface of the sample;

Receive the reflected light array emitted by the sample;

According to the reflected light array, the single point curvature radius of the sample is obtained.

In one embodiment, before the step of placing the sample on the sample stage, the method further includes: correcting the mechanical parameters of the curvature radius measuring device.

In one of the embodiments, the step of correcting the mechanical parameters of the radius of curvature measuring device includes:

Place the first calibration sheet on the sample stage;

transmitting the diffracted light array to the surface of the first correction plate;

receiving the first reflected light array emitted by the first correction sheet;

Replace the first calibration sheet with the second calibration sheet, and repeat the above steps of emitting the diffracted light array and receiving the reflected light array to obtain the second reflected light array;

According to the curvature radius of the first reflected light array, the second reflected light array and the first correction sheet and the second correction sheet, obtain the mechanical parameter correction data of the curvature radius measuring device;

Import the correction data into the analysis unit.

In one embodiment, after the step of obtaining the single point curvature radius, the step further includes:

Move the sample stage according to the set direction and step size;

emitting an array of diffracted light onto the surface of the sample;

Receive the reflected light array emitted by the sample;

According to the reflected light array, obtain the single point curvature radius of the current position of the sample;

Determine whether the current position is the final position, if so, end the measurement and output the multi-point curvature radius of the sample; otherwise, repeat the above steps of moving the sample stage, transmitting the diffracted light array and receiving the reflected light array to obtain the curvature radius of the next position of the sample .

In one embodiment, after the step of acquiring the multi-point curvature radii of the sample, the method further includes: drawing a curvature radius distribution map of the sample according to the multi-point curvature radii.

The above-mentioned curvature radius measuring device includes a sample stage, a diffractive light array generating module and a detection and analysis module. The diffracted light array generating module generates and emits a diffracted light array to the sample. After reaching the sample surface, the reflected light array is reflected on the sample surface and detected. The analysis module receives the reflected light array, and obtains the radius of curvature of the sample according to the size of the received reflected light array. Each laser beam in the diffracted light array has a certain angle with the central beam, so the size of the light spot array will be different depending on the distance from the light source. A mathematical model for measuring the radius of curvature using a diffractive light array is designed, and the device for measuring the radius of curvature is implemented based on the mathematical model. The diffractive optical device is less customized and easy to process, and the brightness of each beam of the generated light spot array is similar , which effectively avoids the problem of high hardware requirements caused by the low brightness of some beams in the prior art, thereby realizing a curvature radius measurement device with simple structure, fast measurement speed, and low hardware requirements such as lasers and sensors.

Description of drawings

1 is a schematic diagram of a calculation model of a curvature radius measuring device in an embodiment;

2 is a schematic structural diagram of a curvature radius measuring device in an embodiment;

3 is a schematic diagram of a diffracted light array in an embodiment;

4 is a flowchart of a method for measuring a radius of curvature in an embodiment;

5 is a flowchart of steps S500 of the method for measuring the radius of curvature in an embodiment;

FIG. 6 is a flowchart of a multi-point curvature radius measurement method in an embodiment.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the related drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", etc. is based on the drawings shown in the drawings. The method or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention .

An embodiment of the present invention provides a curvature radius measurement device, including:

The sample stage 100 is used to carry the sample to be measured;

a diffracted light array generating module 200, configured to generate and emit a diffracted light array to the sample;

The detection and analysis module is configured to receive the reflected light array emitted by the sample, and obtain the radius of curvature of the sample according to the size of the received reflected light array.

Fig. 1 is a schematic diagram of the calculation model of the curvature radius measuring device of the present embodiment. The diffracted light array is emitted from the light source point O. After the emitted diffracted light array reaches the surface of the sample (the bold solid line in Fig. 1 is the surface of the sample), Reflection from the sample surface, emits an array of reflected light to the light-receiving plane.

In this calculation model, it is assumed that the diffracted light array includes two light rays, wherein the light ray whose exit direction is perpendicular to the tangential direction of the point to be measured on the sample surface is defined as the first light ray, and the exit direction is the same as the direction of the first light ray. Another different ray is defined as the second ray, the second ray irradiates the point A on the surface of the sample, the angle between the first ray and the second ray is β, between O'A and O'O The included angle is α (O' is the center of the virtual circle where the sample is located, and the radius of the virtual circle is the radius of curvature R of the sample). First, assuming that the radius of curvature of the film sample is infinite, that is, the sample is a plane without curvature, the set point of the reflected light of the second light on the light-receiving plane is P1; however, the actual radius of curvature of the film sample is not equal to is not infinite, then the actual landing point of the reflected light on the light receiving plane is P2, and there is a certain offset distance D between the positions of P1 and P2. In addition, define the distance from the light source O point to the sample surface as S, the vertical distance from the sample surface point A to the light receiving plane as H, the vertical distance from A point to O'O as W, the parameters α, β, R, D , S, H and W satisfy the following formulas:

D=KP2-KP1=Htan(2α+β)-Htan(β) (1)

In addition, the radius of curvature of the sample bending caused by the thin film deposition process is usually greater than 5m, and the distance between the first light and the second light irradiated on the surface of the sample is not greater than 5mm. Therefore, the following approximate calculation formula can be obtained:

W≈Stan(β) (3)

cos(α)≈1 (4)

By solving the formulas (1) to (4), the following formulas for calculating the radius of curvature can be obtained:

Further, based on the premise that the radius of curvature of the sample is generally greater than 5 m, and the distance between the first light and the second light irradiated on the surface of the sample is not greater than 5 mm, the gap between the sample and the sample stage 100 is extremely small, and S can be approximately equal to point O of the light source. The distance to the surface of the sample stage 100, H can be approximately equal to the distance from the surface of the sample stage 100 to the light receiving plane, so S and H can be considered as inherent mechanical parameters of the curvature radius measuring device. And β is the divergence angle of the diffracted light array, so β is the inherent optical parameter of the scattered light array. Then the parameters S, H and β in the curvature radius calculation formula are all known numbers, and according to the measurement result of the offset distance D, the curvature radius R of the sample can be obtained by using the curvature radius calculation formula.

According to the calculation formula of the radius of curvature, based on this calculation model, the radius of curvature of a point on the surface of the sample can be obtained by only one measurement, without the need to continuously acquire multiple sets of data for measurement, and avoid interference such as vibration on the results of different sets of data. Therefore, a curvature radius measurement model with faster measurement speed and more accurate results is realized.

In one embodiment, the detection and analysis module includes:

a sensor imaging screen 310, configured to receive the reflected light array emitted by the sample, and convert the light signal of the reflected light array into an electrical signal;

The analysis unit is electrically connected to the sensor imaging screen 310, and is used for acquiring the radius of curvature of the sample according to the electrical signal.

As shown in FIG. 2 , the sensor imaging screen 310 is the aforementioned light receiving plane, and the analysis unit is a data processing device electrically connected to the sensor imaging screen 310 , such as a computer (not shown in the figure). In an example, the sensor imaging screen 310 is composed of a CCD image sensor, and the measurement accuracy is 10um, that is, two light rays with a distance of not less than 10um of landing points can be distinguished, so as to accurately measure the reflected light array with a distance of not less than 10um of adjacent light spots. , the sensor imaging screen 310 acquires the reflected light array and sends an electrical signal to the analysis unit, and the analysis unit acquires the curvature radius of the sample according to the curvature radius calculation formula.

In this example, H and S of the curvature radius measuring device are both less than 1 m. Based on the sensor imaging screen 310 with a measurement accuracy of 10 μm, the curvature radius measuring device in this example can be used to measure the curvature radius of 5 m to 200 m. samples, and the systematic error is less than ±1%. further. Corresponding H and S can be selected according to the radius of curvature of the sample. For example, when the radius of curvature is larger, a larger distance H from the sample to the sensor imaging screen 310 is selected to enlarge the reflected light array to obtain more accurate measurement results.

In one embodiment, the diffractive light array generating module 200 includes:

a laser 210 for emitting an initial probe beam;

The diffractive optical lens 220 is used to convert the initial probe beam into a diffracted light array.

In an example, the diffractive light array is a 5×5 light spot array as shown in FIG. 3 . It can be understood that the more light spots the diffracted light array contains, the more spots projected on the sensor imaging screen 310 . The more points, the more points can be used to calculate the radius of curvature of the sample, resulting in a higher measurement accuracy. However, on the premise that the luminous intensity of the laser 210 remains unchanged, the light intensity of each light spot obtained after being transformed by the diffractive optical lens 220 is inversely proportional to the number of light spots. Further, if the divergence angle β of the formed diffracted light array is unchanged , the distance between each light spot is also inversely proportional to the number of light spots, and the light intensity of the light spot and the distance between adjacent light spots will put forward corresponding requirements on the measurement accuracy of the sensor imaging screen 310, the higher the measurement accuracy requirements That means higher manufacturing difficulty and manufacturing cost. Therefore, an appropriate diffractive optical lens 220 should be selected to generate a diffractive light array with an appropriate number of light spots, so as to better balance the relationship between measurement accuracy and manufacturing cost.

In one embodiment, as shown in FIG. 2 , the curvature radius measuring device further includes a semi-reflection and semi-mirror sheet 400 , and the semi-reflection and semi-mirror sheet 400 is disposed between the diffractive light array generating module 200 and the sample stage 100 . During the period, the angle between the semi-reflective semi-mirror sheet 400 and the sample stage 100 is 45°;

The diffracted light array passes through the half mirror plate 400 to reach the sample surface, and is reflected by the sample surface and the half mirror half mirror plate 400 , and projected on the sensor imaging screen 310 arranged perpendicular to the sample stage 100 .

By changing the emission direction of the reflected light array by the semi-reflective semi-mirror sheet 400, the laser 210 and the diffractive optical lens 220 can be prevented from blocking the reflected light array, so that a complete reflected light array can be obtained on the sensor imaging screen 310. In this implementation In the example, S is the path length from the diffractive optical lens 220 to the sample surface, H is the path length H1 from the sample surface to the semi-mirror sheet 400 and the path length H2 from the semi-mirror sheet 400 to the sensor imaging screen 310 Sum.

In one embodiment, the sample stage 100 includes a stage and a two-dimensional motion mechanism, the stage is used to carry the sample to be measured, and the two-dimensional motion mechanism is used to drive the stage to move horizontally, and through the horizontal movement , the radius of curvature within the set range of the sample can be measured according to the preset measurement logic, so that only one parameter setting is required to automatically measure and obtain the measurement data of the radius of curvature of multiple points in the sample, and improve the accuracy of the radius of curvature measuring device. Maneuverability and flexibility.

The technical solution of the present invention also provides a method for measuring the radius of curvature, as shown in FIG. 4 , including:

S100: place the sample on the sample stage 100;

S200: emit a diffracted light array to the surface of the sample;

S300: Receive the reflected light array emitted by the sample;

S400: Acquire the single-point curvature radius of the sample according to the reflected light array.

In an embodiment, before the step of placing the sample on the sample stage 100, the step further includes S500: correcting the mechanical parameters of the curvature radius measuring device. According to the calculation formula of the radius of curvature, it is necessary to calculate the radius of curvature of the sample according to the inherent mechanical parameters H and S of the radius of curvature measuring device, but the mechanical parameters H and S will change due to external vibration and other factors, thus affecting the curvature Therefore, through the step of correcting the mechanical parameters, the accuracy of the curvature radius measuring device can be further improved.

In an example, as shown in FIG. 5 , the step of correcting the mechanical parameters of the curvature radius measuring device includes:

S510: place the first calibration sheet on the sample stage 100;

S520: Emit the diffracted light array to the surface of the first correction sheet;

S530: Receive the first reflected light array emitted by the first correction sheet;

S540: Replace the first correction sheet with the second correction sheet, and repeat the above steps of emitting the diffracted light array and receiving the reflected light array to obtain the second reflected light array;

S550: Acquire mechanical parameter correction data of the curvature radius measuring device according to the curvature radius of the first reflected light array, the second reflected light array, and the first correction sheet and the second correction sheet;

S560: Import the correction data into the analysis unit.

In this example, it is known that the radius of curvature of the first correction sheet is R1, and the radius of curvature of the second correction sheet is R2. By substituting R1 and R2 as known numbers into the calculation formula of the radius of curvature, the exact values of H and S can be solved. Correction data, the analysis unit can obtain the accurate sample curvature radius R according to the correction data.

In one embodiment, as shown in FIG. 6 , after the step of obtaining the single point curvature radius, the step further includes:

S610: Move the sample stage 100 according to the set direction and step size;

S620: emit a diffracted light array to the surface of the sample;

S630: Receive the reflected light array emitted by the sample;

S640: Acquire the single-point curvature radius of the current position of the sample according to the reflected light array;

S650: Determine whether the current position is the final position, if so, end the measurement and output the multi-point curvature radius of the sample; otherwise, repeat the above steps of moving the sample stage 100, transmitting the diffracted light array and receiving the reflected light array to obtain the next position of the sample the radius of curvature.

Through the multi-point measurement step in this embodiment, the radius of curvature within the set range of the sample can be measured according to the preset measurement logic, so that only one parameter setting is required to automatically measure and obtain the curvature of multiple points in the sample Radius measurement data, improve the operability and flexibility of curvature radius measurement. Specifically, the operator selects a measurement area on the sample surface, and sets the measurement step length, and the control component of the two-dimensional motion mechanism automatically plans the measurement path in the measurement area according to the measurement step length. The two-dimensional motion mechanism controls the sample to move according to the measurement path until the current position is the final position in the measurement path.

In an embodiment, after the step of acquiring the multi-point curvature radii of the sample, the method further includes: drawing a curvature radius distribution map of the sample according to the multi-point curvature radii. Through the curvature radius distribution map, the curvature radius distribution of the sample can be intuitively acquired and analyzed, and the process parameters of film deposition can be further adjusted or defective samples can be excluded, thereby improving the overall production yield of the device.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (11)

1. a curvature radius measuring device, is characterized in that, comprises: Sample stage, used to carry the sample to be measured; a diffracted light array generating module, used for generating and emitting a diffracted light array to the sample; The detection and analysis module is configured to receive the reflected light array emitted by the sample, and obtain the radius of curvature of the sample according to the size of the received reflected light array. 2. The curvature radius measuring device according to claim 1, wherein the detection and analysis module comprises: a sensor imaging screen, used for receiving the reflected light array emitted by the sample, and converting the light signal of the reflected light array into an electrical signal; The analysis unit is electrically connected to the sensor imaging screen, and is used for acquiring the curvature radius of the sample according to the electrical signal. 3. The curvature radius measuring device according to claim 2, wherein the emission direction of the diffracted light array is perpendicular to the sample stage, and the curvature radius of the sample is calculated according to the following formula:

in, R is the radius of curvature of the sample; S is the length of the first path of the diffracted light array from the diffracted light array generating module to the sample surface; H is the length of the second path of the reflected light array from the sample surface to the sensor imaging screen; β is the divergence angle of the diffracted light array; D is the distance between the actual landing point and the set landing point of the reflected light array on the detector. 4 . The curvature radius measuring device according to claim 2 , wherein the curvature radius measuring device further comprises a semi-reflection and semi-mirror sheet, and the semi-reflection and semi-mirror sheet is arranged on the diffractive light array generating module and the sample. 5 . Between the stages, the angle between the semi-reflective semi-lens sheet and the sample stage is 45°; The diffracted light array passes through the semi-reflection and semi-mirror sheet to reach the surface of the sample, and is then reflected by the sample surface and the semi-reflection and semi-mirror sheet, and is projected on a sensor imaging screen arranged perpendicular to the sample stage. 5. The curvature radius measuring device according to claim 1, wherein the sample stage comprises: table top, used to carry the sample to be measured; A two-dimensional motion mechanism is used to drive the table top to move horizontally. 6. The curvature radius measuring device according to claim 1, wherein the diffractive light array generating module comprises: a laser for emitting the initial probe beam; A diffractive optical lens is used to convert the initial probe beam into a diffractive light array. 7. A method for measuring a radius of curvature, comprising: Place the sample on the sample stage; emitting an array of diffracted light onto the surface of the sample; Receive the reflected light array emitted by the sample; According to the reflected light array, the single point curvature radius of the sample is obtained. 8 . The method for measuring the radius of curvature of claim 7 , wherein before the step of placing the sample on the sample stage, the method further comprises: correcting mechanical parameters of the radius of curvature measuring device. 9 . 9. The method for measuring radius of curvature according to claim 8, wherein the step of calibrating the mechanical parameters of the radius of curvature measuring device comprises: Place the first calibration sheet on the sample stage; transmitting the diffracted light array to the surface of the first correction plate; receiving the first reflected light array emitted by the first correction sheet; Replace the first calibration sheet with the second calibration sheet, and repeat the above steps of emitting the diffracted light array and receiving the reflected light array to obtain the second reflected light array; According to the curvature radius of the first reflected light array, the second reflected light array and the first correction sheet and the second correction sheet, obtain the mechanical parameter correction data of the curvature radius measuring device; Import the correction data into the analysis unit. 10. The method for measuring a radius of curvature according to claim 9, wherein after the step of obtaining the single-point radius of curvature, the method further comprises: Move the sample stage according to the set direction and step size; emitting an array of diffracted light onto the surface of the sample; Receive the reflected light array emitted by the sample; According to the reflected light array, obtain the single point curvature radius of the current position of the sample; Determine whether the current position is the final position, if so, end the measurement and output the multi-point curvature radius of the sample; otherwise, repeat the above steps of moving the sample stage, transmitting the diffracted light array and receiving the reflected light array to obtain the curvature radius of the next position of the sample . 11 . The method for measuring the radius of curvature of claim 10 , wherein after the step of acquiring the multi-point curvature radius of the sample, the method further comprises: drawing a curvature radius distribution map of the sample according to the multi-point curvature radius. 12 .

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