CN1991333B - zero-Abbe error measuring system and method thereof - Google Patents

Abstract

A zero-Abbe error measuring system comprises a mobile platform, a detection device, a first three-dimensional optical scale and a second three-dimensional optical scale. The movable platform is used for carrying a sample to be measured. The detection device is used for detecting the sample to be measured and measuring the vertical height of the point to be measured of the sample to be measured relative to the moving platform. The first three-dimensional optical ruler and the second three-dimensional optical ruler are respectively arranged on the moving platform and are opposite to each other through a sample to be measured, wherein the first three-dimensional optical ruler and the second three-dimensional optical ruler can be vertically arranged on the moving platform for fine adjustment of height, so that the vertical height of the first three-dimensional optical ruler and the vertical height of the second three-dimensional optical ruler relative to the moving platform are equal to the vertical height of the point to be measured, and the sample to be measured is measured.

Description

Zero Abbe Error Measuring System and Its Method

technical field

The invention relates to a measuring system and its method, and in particular to a measuring system and its method capable of eliminating Abbe errors.

Background technique

The architecture of traditional three-dimensional micro (nano) measurement systems, such as scanning probe microscopy (SPM), atomic force microscope (AFM) and coordinate measuring machine (coordinate measuring machine, CMM), is mainly based on the form It is composed of sub-systems such as appearance detection system and/or positioning platform. The main work of the shape detection system is to obtain the surface information of the object to be measured by means of probes and other methods. The positioning platform system is responsible for driving the probe carrier or mobile platform, so that the whole system can complete three-dimensional scanning and measurement actions. However, there is a certain degree of angular deviation between the placement position of the linear scale or the interferometer and the probe or the measuring end point in this positioning system because they are located in different positions. This deviation will increase as the distance between the two points increases, causing the measurement process to produce the so-called Abbe error (Abbe error). This Abbe error will affect the final actual measurement result and reduce the accuracy of the measurement.

In a three-dimensional measurement system, multiple groups of optical interferometers are generally used as a tool for platform positioning, and a measurement design with zero Abbe error is also added. However, when using an interferometer for positioning, there are often problems and shortcomings such as requiring more components, complicated alignment, long optical path, and air interference, so the accuracy and system performance are not easy to improve. In addition, an optical ruler is also used as a positioning device, which has the advantages of relatively short optical path and convenient alignment.

Figure 1 shows a known measurement system using an interferometer. The measurement system of FIG. 1 includes optical interferometers 106x, 106y, 106z in three coordinate directions. A sample 102 to be measured is placed on the mobile platform 100 . In addition, information such as the surface topography of the sample to be measured 102 is acquired using a probe of the detector 104 or the like. There is a small distance between the probe of the detector 104 and the displacement measurement position of the positioning table, which causes so-called Abbe error in the measurement process. FIG. 2 is a diagram illustrating a known interferometer measurement system with zero Abbe error design. Fig. 2 is to make the measurement beams of the three groups of optical interferometers 106x, 106y, 106z in Fig. 1 intersect at one point along the XYZ three axes, and use the Abbe error correction parts 108a, 108b to make the positioning point fall on the measurement point for positioning Work to minimize the Abbe error. However, the positioning of the interferometer will increase the complexity of the system, and will increase the system cost a lot.

Therefore, someone proposes a method of using an optical ruler. Fig. 3 is a schematic diagram of a three-dimensional optical positioning ruler measuring system. As shown in FIG. 3 , the optical scale includes a grating 120 and a light source 122 , and the light source emits a light beam to the grating for positioning. The grating 120 is disposed under the mobile platform 100 , and this kind of structure will also generate Abbe error because the positioning point and the actual measurement position are in different positions.

Therefore, how to improve the above problems and obtain a simple, low-cost measurement system that can eliminate the Abbe error is a part of the measurement technology to break through.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a zero-Abbe error measurement system, using a three-dimensional or two-dimensional optical scale as a positioning platform, adding a new design method, so that the measurement results can reach zero Abbe error, replacing the general interferometer measurement system and reduce system cost.

To achieve the above purpose, the present invention proposes a zero Abbe error measurement system, which includes a mobile platform, a detection device, and first and second three-dimensional optical scales. The mobile platform is used to load the samples to be measured. The detection device is used for detecting the sample to be measured, and measuring the vertical height of the point to be measured of the sample to be measured relative to the mobile platform. The first and second three-dimensional optical rulers are respectively arranged on the mobile platform and face each other across the sample to be measured, wherein the first and second three-dimensional optical rulers can be finely adjusted vertically to the mobile platform, so that the first and second three-dimensional optical rulers The vertical height relative to the mobile platform is equal to the vertical height of the point to be measured, so as to measure the sample to be measured.

According to an embodiment of the present invention, the first and second three-dimensional optical scales of the aforementioned zero-Abbe error measurement system further include a two-dimensional grating, a height trimmer, and a height detector, respectively. A two-dimensional grating is set on the mobile platform to position the mobile platform. The height fine-tuner is connected with the two-dimensional grating, and is used for fine-tuning the vertical height of the two-dimensional grating. The height detector is set approximately perpendicular to the top of the two-dimensional grating, and is used for emitting light beams to detect the vertical height of the two-dimensional grating.

According to an embodiment of the present invention, the aforementioned two-dimensional grating has an undulating surface. In addition, when the aforementioned undulating surface is permeable to light, the base of the two-dimensional grating also has a reflective surface. In addition, the two-dimensional grating may be, for example, a holographic two-dimensional grating.

According to an embodiment of the present invention, the aforementioned zero-Abbe error measurement system may further include a control circuit, which at least includes a comparator and a height fine-tuning controller. The comparator is used to receive the vertical heights output by the height detectors of the first and second three-dimensional optical scales and the vertical heights of the points to be measured output by the detection device, and output the difference between the two vertical heights. The height fine-tuning controller is connected to the output terminal of the comparator, receives the difference and controls the height fine-tuning device according to the difference to fine-tune the vertical height of the two-dimensional grating.

In addition, the present invention also proposes a zero Abbe error measurement system, which includes a mobile platform, a detection device, and first and second two-dimensional optical scales. The mobile platform is used to load the samples to be measured. The detection device is used for detecting the sample to be measured, and measuring the vertical height of the point to be measured of the sample to be measured relative to the mobile platform. The first and second two-dimensional optical rulers are respectively arranged on the mobile platform and face each other across the sample to be measured, wherein the first and second two-dimensional optical rulers can be finely adjusted vertically to the mobile platform, so that the first and second two-dimensional optical rulers The vertical height of the dimensional optical ruler relative to the mobile platform is equal to the vertical height of the point to be measured, so as to measure the sample to be measured.

According to an embodiment of the present invention, each of the aforementioned two-dimensional optical scales includes a grating, a height trimmer, a light source, and a height detector, respectively. The grating is set on the mobile platform to position the mobile platform. The height fine-tuner is connected with the grating for fine-tuning the vertical height of the grating. The light source is arranged approximately perpendicular to the bottom of the mobile platform, and is used to emit light beams to the grating for positioning the mobile platform. The height detector is set approximately perpendicular to the top of the two-dimensional grating for emitting light beams and detecting the vertical height of the grating. The aforementioned height detector can be, for example, an interferometer or a high-precision displacement measuring device.

In addition, the present invention also proposes a zero Abbe error measurement method for measuring the sample to be measured placed on the mobile platform. The first and second optical rulers are also arranged on the mobile platform. The zero Abbe error measurement method at least includes the following steps: detecting the surface of the sample to be measured, and measuring the first vertical height of the point to be measured of the sample to be measured relative to the mobile platform; detecting the first and second optical scales relative to the mobile platform and according to the difference between the first and second vertical heights, fine-tuning the vertical heights of the first and second two-dimensional optical scales, so that the first and second vertical heights are equal to measure the sample to be measured.

To sum up, the present invention places the XY plane of the grating of the optical scale on the same vertical height as the point to be measured, so that the positioning point and the measuring point are kept on the same plane, thereby eliminating the known problem of placing the grating under the sample. , the Abbe error caused by the difference between the measurement point and the actual positioning position.

In addition, since the present invention does not use the interferometer for platform positioning, or is only used for vertical height measurement, no additional Abbe error compensating device is needed, thereby reducing the cost and complexity of the system.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below and described in detail with accompanying drawings.

Description of drawings

Figure 1 shows a known measurement system using an interferometer.

Figure 2 shows a known interferometer measurement system with zero Abbe error design.

Fig. 3 is a schematic diagram of a three-dimensional optical positioning ruler measuring system.

FIG. 4 is a schematic diagram of a zero Abbe error measurement system according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of the control circuit of FIG. 4 .

FIG. 6 is a schematic diagram of a zero Abbe error measurement system according to another embodiment of the present invention.

Description of main component marking

100 mobile platforms

102 samples to be measured

104 detection device

106x, 106y, 106z interferometer

108a, 108b Abbe error correction unit

120 grating (optical scale)

122 light source (optical ruler)

200 mobile platforms

210 stage

212 samples to be measured

230, 240 measuring system (three-dimensional optical ruler)

232, 242 height detector

234, 244 two-dimensional grating

250 detection device

264 Comparator

266 controller

300, 310 measuring system (two-dimensional optical ruler)

302, 312 height detector

304, 314 light source

306, 316 grating

306a, 316a reflective surface

308, 318 height trimmer

Detailed ways

FIG. 4 is a schematic diagram of a zero Abbe error measurement system according to an embodiment of the present invention. In order to make the diagram simple and easy to read, the detailed mechanical structure of the system itself is omitted, and those skilled in the art can make appropriate designs according to the following description.

The zero Abbe error measurement system of the present invention mainly includes two parts, one part is the shape detection subsystem, and the other part is the platform positioning measurement subsystem. As shown in FIG. 4 , the morphology detection subsystem is mainly composed of a detection device 250 which has a probe and can detect the surface morphology of the sample to be measured (hereinafter referred to as the sample) 212 . The sample 212 to be measured is placed on a 3D moving table (3D moving table) 200 via a stage 210 . The mobile platform 200 can move along the XYZ axes shown in the figure, so that the detection device 250 can detect the surface topography or other physical and chemical properties of the sample 212 .

The platform positioning measurement subsystem is mainly composed of two sets of measurement systems 230 and 240 . The measurement systems 230 and 240 mainly use the three-dimensional optical ruler as the positioning of the platform, which are referred to as the first three-dimensional optical ruler 230 and the second three-dimensional optical ruler 240 below. As shown in FIG. 4 , the first three-dimensional optical ruler 230 and the second three-dimensional optical ruler 240 are respectively disposed on the mobile platform 200 and face each other through the sample 212 . The first three-dimensional optical ruler 230 and the second three-dimensional optical ruler 240 can vertically adjust the height (H) of the mobile platform, so that the vertical height of the first three-dimensional optical ruler 230 and the second three-dimensional optical ruler 240 relative to the mobile platform is the same as that to be The vertical heights of the measuring points are equal for the measurement of the sample 212 .

The first three-dimensional optical scale 230 includes a two-dimensional grating 234 , a height trimmer (not shown in the figure), and a height detector (Z-axis height) 232 . The two-dimensional grating 234 is disposed on the mobile platform 200 to position the mobile platform 200 . The height trimmer can be used to fine-tune the vertical height H of the two-dimensional grating 234 . The height detector 232 can mainly emit light beams such as laser light to detect the vertical height of the two-dimensional grating 234 relative to the mobile platform 200 .

Likewise, the second three-dimensional optical scale 240 includes a two-dimensional grating 244 , a height fine-tuner (not shown in the figure), and a height detector (Z-axis height) 242 . The two-dimensional grating 244 is disposed on the mobile platform 200 to position the mobile platform 200 . The height trimmer can be used to fine-tune the vertical height H of the two-dimensional grating 244 . The height detector 242 can mainly emit light beams such as laser light to detect the vertical height of the two-dimensional grating 244 relative to the mobile platform 200 .

As for the two-dimensional gratings 234, 244, a two-dimensional optical ruler with surface relief can be used for displacement measurement. In addition, if the above-mentioned surface undulations are permeable to light, a reflective layer can be made on the bottom surface of the two-dimensional grating substrate, so that the light beam emitted by the height detector 232 can be reflected back to detect the Z-axis height H. In addition, the two-dimensional gratings 234 and 244 can also use a holographic two-dimensional optical scale for displacement measurement. As long as the functions and purposes of the two-dimensional gratings 234 and 244 can be achieved, the specific implementation methods are not limited.

Next, the operation of the above measurement system will be described. When measuring, the mobile platform 200 will move, so that the detection device 250 can detect each point of the sample 212 to be measured. In addition, the detecting device 250 will also detect the vertical height of the point to be measured relative to the mobile platform 200 at the same time. At this time, the height detectors 232 , 242 of the two-dimensional optical rulers 230 , 240 detect the vertical heights of the XY planes of the two-dimensional gratings 234 , 244 relative to the mobile platform 200 . Then, the vertical heights of the height detectors 232 and 242 are compared with the vertical heights of the points to be measured. When the two vertical heights are different, the height fine-tuners of the two-dimensional optical rulers 230 and 240 will act to adjust the two-dimensional optical rulers 230 and 240. 240, so that the vertical heights of the XY planes of the two-dimensional gratings 234, 244 are the same as the vertical heights of the points to be measured. During the entire measurement process, the vertical height of the point to be measured will always change. According to this height change, the height fine-tuners of the two-dimensional optical scale 230, 240 will also constantly adjust the height along with the action, so that the vertical height of the XY plane of the two-dimensional grating 234, 244 can be equal to the vertical height of each point to be measured. same.

As mentioned above, since the vertical heights of the XY planes of the two-dimensional gratings 234 and 244 can be kept the same as the vertical heights of the points to be measured during the measurement process, the Abbe error can be eliminated and the goal of zero Abbe error can be achieved.

FIG. 5 is a schematic diagram of the control circuit of FIG. 4 . The control circuit shown in Fig. 5 is used to control the aforementioned measurement process. The control circuit includes a comparator 264 and a controller 266 .

The comparator 264 receives the vertical heights of the XY planes of the two-dimensional gratings 234 , 244 output by the height detectors 232 , 242 and the vertical heights of the points to be measured output by the detection device 250 . The comparator 264 then compares the difference between the two vertical heights and outputs it to the controller 266 . The controller 266 then controls the height fine-tuners of the two-dimensional gratings 234, 244 according to the difference, and fine-tunes the vertical heights of the XY planes of the two-dimensional gratings 234, 244 in the Z-axis direction so that the vertical heights are perpendicular to the point to be measured. The height is on the same height. During the entire measurement process, the above-mentioned negative feedback control is continuously operated, so that the vertical heights of the XY planes of the two-dimensional gratings 234, 244 are kept at the same height as the vertical heights of the points to be measured, thereby eliminating Abbe errors.

As mentioned above, the present invention can achieve the measurement goal of zero Abbe error by using a simple optical scale, and greatly reduce the cost of the system.

FIG. 6 is a schematic diagram of a zero Abbe error measurement system according to another embodiment of the present invention. This embodiment is mainly a variation example of FIG. 4 , the difference between the two is that FIG. 4 uses a three-dimensional optical ruler, and the system in FIG. 6 uses a two-dimensional optical ruler.

As shown in Figure 6, the zero-Abbe error measurement system is similar to the zero-Abbe error measurement system in Figure 4 except that the platform positioning measurement subsystem is different. Only the platform positioning measurement subsystem is described here.

The first two-dimensional optical scale 300 includes a grating 306 , a height trimmer 308 , a light source 304 and a height detector 302 . The grating 306 is disposed on the mobile platform 200 for positioning the mobile platform 200 . The height fine-tuner 308 is connected to the grating 306 for fine-tuning the vertical height H of the grating 306 . The light source is arranged substantially perpendicular to the bottom of the mobile platform 200 to emit light beams to the grating 306 for positioning the mobile platform 200 . The height detector 302 is arranged substantially vertically above the two-dimensional grating 306 for emitting light beams and detecting the vertical height of the grating 306 .

The second two-dimensional optical scale 310 includes a grating 316 , a height trimmer 318 , a light source 314 and a height detector 312 . The grating 316 is disposed on the mobile platform 200 for positioning the mobile platform 200 . The height fine-tuner 318 is connected to the grating 316 for fine-tuning the vertical height H of the grating 316 . The light source is arranged to be substantially perpendicular to the bottom of the mobile platform 200, and is used to emit light beams to the grating 316 for positioning the mobile platform 200. The height detector 312 is arranged substantially vertically above the two-dimensional grating 316 for emitting light beams and detecting the vertical height of the grating 316 .

When measuring, the principle of eliminating the Abbe error is the same as that of the system in Fig. 4, so it will not be described here. Taking the first two-dimensional optical ruler 300 as an illustration, in this embodiment, a general grating is used for positioning the platform, and the light source 304 is used for positioning. Vertical height fine-tuning of the XY surface of grating 306 is performed using height detector 302 . In order to cooperate with this structure, a reflective surface is provided on the surface 306 a of the grating 306 , so as to reflect the light beam emitted by the height detector 302 back to measure the vertical height of the XY surface of the grating 306 .

The height detectors 302 and 312 mentioned above may use interferometers or high-precision displacement measuring devices, for example. In addition, similar to the embodiment in FIG. 4 , the embodiment in FIG. 6 can also use the control circuit shown in FIG. 5 to fine-tune the vertical height of the grating, so no further description is given here.

To sum up, the present invention places the XY plane of the grating of the optical scale on the same vertical height as the point to be measured, so that the positioning point and the measuring point are kept on the same plane, thereby eliminating the known problem of placing the grating under the sample. , the Abbe error caused by the difference between the measurement point and the actual positioning position.

In addition, since the present invention does not use the interferometer for platform positioning, and if the interferometer is used, it is only used for height measurement, so no additional Abbe error compensation device is needed, so the cost and complexity of the system can be reduced.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (11)

1. A zero Abbe error measurement system is characterized in that it comprises: The mobile platform is used to load the sample to be measured; a detection device, used to detect the sample to be measured, and measure the vertical height of the point to be measured of the sample to be measured relative to the mobile platform; The first and second three-dimensional optical rulers are respectively arranged on the mobile platform and face each other across the sample to be measured, wherein the first and the second three-dimensional optical rulers can be finely adjusted vertically to the mobile platform, so that the first The vertical height of the second three-dimensional optical ruler relative to the mobile platform is equal to the vertical height of the point to be measured relative to the mobile platform, so as to measure the sample to be measured, Wherein the first and the second three-dimensional optical ruler respectively include: a two-dimensional grating arranged on the mobile platform to position the mobile platform; a height fine-tuner connected to the two-dimensional grating for fine-tuning the vertical height of the two-dimensional grating; and The height detector is arranged substantially perpendicular to the top of the two-dimensional grating, and is used to emit light beams to detect the vertical height of the two-dimensional grating. 2. The zero-Abbe error measurement system according to claim 1, wherein the two-dimensional grating has an undulating surface. 3. The zero Abbe error measuring system according to claim 2, wherein the undulating surface of the two-dimensional grating is light-transmissible, and the base of the two-dimensional grating has a reflective surface. 4. The zero Abbe error measuring system according to claim 1, wherein the two-dimensional grating is a holographic two-dimensional grating. 5. The zero Abbe error measurement system according to claim 1 is characterized in that it also includes a control circuit, and the control circuit also includes: a comparator for receiving the vertical heights output by the height detectors of the first and second three-dimensional optical rulers and the vertical height of the point to be measured output by the detection device, and outputting the difference between the two vertical heights; as well as The height fine-tuning controller is connected to the output terminal of the comparator, receives the difference, and controls the height fine-tuner according to the difference. 6. A zero Abbe error measuring system, characterized in that it comprises: The mobile platform is used to load the samples to be measured; a detection device, used to detect the sample to be measured, and measure the vertical height of the point to be measured of the sample to be measured relative to the mobile platform; The first and second two-dimensional optical rulers are respectively arranged on the mobile platform and face each other across the sample to be measured, wherein the first and the second two-dimensional optical rulers can be finely adjusted vertically to the mobile platform, so that the The vertical heights of the first and second two-dimensional optical rulers relative to the mobile platform are equal to the vertical heights of the point to be measured relative to the mobile platform, so as to measure the sample to be measured, Wherein the first and the second two-dimensional optical scales respectively include: a grating disposed on the mobile platform to position the mobile platform; a height fine-tuner connected to the grating for fine-tuning the vertical height of the grating; a light source, arranged substantially perpendicularly below the mobile platform, for emitting light beams to the grating for positioning the mobile platform; and The height detector is arranged substantially perpendicularly above the grating, and is used to emit light beams to detect the vertical height of the grating. 7. The zero Abbe error measurement system according to claim 6, wherein the height detector is an interferometer. 8. The zero Abbe error measuring system according to claim 6, wherein the height detector is a displacement measuring device. 9. The zero Abbe error measurement system according to claim 6, further comprising a control circuit, the control circuit further comprising: The comparator is used to receive the vertical height output by the height detector of each of the first and the second two-dimensional optical ruler and the vertical height of the point to be measured output by the detection device, and output the difference between the two vertical heights ;as well as The height fine-tuning controller is connected to the output terminal of the comparator, receives the difference, and controls the height fine-tuner according to the difference. 10. A zero-Abbe error measurement method for measuring a sample to be measured placed on a mobile platform, characterized in that the mobile platform is also provided with a first and second three-dimensional optical ruler, the zero-Abbe error measurement method include: Detecting the surface of the sample to be measured, and measuring the first vertical height of the point to be measured of the sample to be measured relative to the mobile platform; Detecting a second vertical height of the first and the second 3D optical ruler relative to the mobile platform; fine-tuning the vertical heights of the first and second three-dimensional optical scales according to the difference between the first and the second vertical heights, so that the first and the second vertical heights are equal to measure the sample to be measured, Wherein the first and the second three-dimensional optical ruler respectively include: a two-dimensional grating arranged on the mobile platform to position the mobile platform; a height fine-tuner connected to the two-dimensional grating for fine-tuning the vertical height of the two-dimensional grating; and The height detector is arranged substantially perpendicular to the top of the two-dimensional grating, and is used to emit light beams to detect the vertical height of the two-dimensional grating. 11. A zero-Abbe error measurement method for measuring a sample to be measured placed on a mobile platform, characterized in that the mobile platform is also provided with a first and second two-dimensional optical ruler, the zero-Abbe error measurement Methods include: Detecting the surface of the sample to be measured, and measuring the first vertical height of the point to be measured of the sample to be measured relative to the mobile platform; detecting a second vertical height of the first and the second two-dimensional optical ruler relative to the mobile platform; fine-tuning the vertical heights of the first and second two-dimensional optical scales according to the difference between the first and the second vertical heights, so that the first and the second vertical heights are equal to measure the sample to be measured, Wherein the first and the second two-dimensional optical scales respectively include: a grating disposed on the mobile platform to position the mobile platform; a height fine-tuner connected to the grating for fine-tuning the vertical height of the grating; a light source, arranged substantially perpendicularly below the mobile platform, for emitting light beams to the grating for positioning the mobile platform; and The height detector is arranged substantially perpendicularly above the grating, and is used to emit light beams to detect the vertical height of the grating.

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