CN113108691B - Measuring device and measuring method - Google Patents

Abstract

The application provides a measuring device and a measuring method. The measuring device comprises a beam splitter and a reflecting system, wherein the beam splitter is used for splitting a light beam provided by a light source into a first light beam emitted to an imaging system and a second light beam emitted to a first surface of a wafer to be measured, and reflecting the second light beam reflected by the first surface to the reflecting system; the reflection system is used for reflecting the second light beam reflected by the first surface to a second surface of the wafer to be measured, wherein the second light beam is opposite to the first surface, and the second light beam reflected by the second surface is reflected to the beam splitter, so that the second light beam reflected by the second surface passes through the beam splitter and is emitted to the imaging system, and the imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface. The application provides a measuring device can reduce the vibration and to the measuring result influence, improves the degree of accuracy of measuring result.

Description

Measuring device and measuring method

Technical Field

The application relates to the technical field of precision measurement, in particular to a measuring device and a measuring method.

Background

The wafer refers to a silicon wafer, which is a base material for manufacturing a semiconductor device. The wafer may be made into chips through a series of processes of a semiconductor manufacturing process.

In a manufacturing process, it is usually necessary to measure relevant parameters of a wafer, such as thickness, flatness, or warp. One prior art technique employs an interferometer-based optical imaging system to measure parameters of interest of a wafer. However, since the optical imaging system is susceptible to vibration, the accuracy of the measurement result is difficult to ensure.

Disclosure of Invention

In view of the above, the present application provides a measurement apparatus and a measurement method to improve the accuracy of the measurement result.

In a first aspect, a measurement device is provided. The measuring device includes: the device comprises a beam splitter and a reflecting system, wherein the beam splitter is used for splitting a light beam provided by a light source into a first light beam emitted to an imaging system and a second light beam emitted to a first surface of a wafer to be measured, and reflecting the second light beam reflected by the first surface to the reflecting system; the reflection system is used for reflecting the second light beam reflected by the first surface to a second surface of the wafer to be measured, wherein the second light beam is opposite to the first surface, and the second light beam reflected by the second surface is reflected to the beam splitter, so that the second light beam reflected by the second surface passes through the beam splitter and is emitted to the imaging system, and the imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface.

With reference to the first aspect, in some embodiments, the beam splitter is a polarization beam splitter, and the measurement apparatus further includes a first quarter wave plate and a second quarter wave plate, wherein the first quarter wave plate is disposed in an optical path between the beam splitter and the first surface, wherein the second light beam passes through the first quarter wave plate during the second light beam is emitted from the beam splitter to the first surface, and wherein the second light beam passes through the first quarter wave plate during the second light beam is reflected from the first surface back to the beam splitter; the second quarter wave plate is arranged on an optical path between the beam splitter and the second surface, wherein the second light beam passes through the second quarter wave plate in the process of being emitted to the second surface from the beam splitter; the second beam passes through the second quarter wave plate during reflection of the second beam from the second surface back to the beam splitter.

With reference to the first aspect, in some embodiments, the measurement apparatus further comprises: the first lens is arranged on a light path between the light source and the beam splitter and used for diffusing the light beam; a second lens disposed on an optical path between the beam splitter and the first surface for collimating the second light beam emitted from the beam splitter toward the first surface and for converging the second light beam reflected from the first surface back to the beam splitter; a third lens disposed on an optical path between the beam splitter and the reflection system, for collimating the second light beam emitted from the beam splitter to the reflection system, and for diffusing the second light beam emitted from the reflection system to the beam splitter; a fourth lens disposed on an optical path between the reflection system and the second surface, for diffusing the second light beam emitted from the reflection system toward the second surface, and for collimating the second light beam reflected from the second surface back to the reflection system; a fifth lens disposed on an optical path between the reflection system and the second surface, for collimating the second light beam emitted from the reflection system toward the second surface, and for converging the second light beam reflected from the second surface back to the reflection system; and a sixth lens, disposed on an optical path between the beam splitter and the imaging system, for collimating the first and second light beams, wherein the second light beam sequentially passes through the fourth and fifth lenses in a process of being emitted from the reflection system to the second surface; the second light beam sequentially passes through the fifth lens and the fourth lens during reflection of the second light beam from the second surface back to the reflection system.

With reference to the first aspect, in some embodiments, the reflection system comprises a plurality of reflection units.

With reference to the first aspect, in some embodiments, the measurement apparatus further includes a hartmann sensor, wherein the plurality of reflection units includes a transflective unit, such that a portion of the second light beam is transmitted through the transflective unit toward the hartmann sensor.

With reference to the first aspect, in some embodiments, the first light beam is the portion of the light beam that is reflected by the beam splitter, the second light beam is the portion of the light beam that passes through the beam splitter, and the first light beam is perpendicular to the second light beam; an included angle between a reflection plane of the beam splitter, which reflects the second light beam to the reflection system, and the first surface is 45 degrees, the plurality of reflection units include a first reflection unit, a second reflection unit, and a third reflection unit, the reflection plane of the beam splitter, which reflects the second light beam to the reflection system, is perpendicular to the reflection plane of the first reflection unit, the reflection plane of the first reflection unit is perpendicular to the reflection plane of the second reflection unit, the reflection plane of the second reflection unit is perpendicular to the reflection plane of the third reflection unit, and the included angle between the reflection plane of the third reflection unit and the second surface is 45 degrees; the second light beam is emitted to the first surface along a direction perpendicular to the first surface and is emitted to the second surface along a direction perpendicular to the second surface.

In a second aspect, a method of measurement is provided. The measuring method comprises the following steps: splitting a light beam provided by a light source into a first light beam emitted to an imaging system and a second light beam emitted to a first surface of a wafer to be measured by using a beam splitter; reflecting the second light beam reflected back from the first surface to a reflection system by using the beam splitter; reflecting the second light beam reflected by the first surface to a second surface of the wafer to be measured, which is opposite to the first surface, by using the reflecting system; and reflecting the second light beam reflected by the second surface to the beam splitter by using the reflection system so that the second light beam reflected by the second surface passes through the beam splitter to be emitted to the imaging system, wherein the imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface.

In combination with the second aspect, in some embodiments, the second beam passes through a first quarter wave plate during its passage from the beam splitter to the first surface; the second beam passes through the first quarter wave plate during reflection of the second beam from the first surface back to the beam splitter; and the second beam passes through a second quarter wave plate during its passage from the beam splitter to the second surface; the second beam passes through the second quarter wave plate during reflection of the second beam from the second surface back to the beam splitter.

With reference to the second aspect, in some embodiments, the measurement method further comprises: diffusing the light beam with a first lens disposed on an optical path between the light source and the beam splitter; collimating said second beam of light directed from said beam splitter toward said first surface with a second lens disposed in the path of light between said beam splitter and said first surface and converging said second beam of light reflected back from said first surface to said beam splitter; collimating the second light beam directed from the beam splitter toward the reflection system with a third lens disposed on an optical path between the beam splitter and the reflection system, and diffusing the second light beam directed from the reflection system toward the beam splitter; diffusing the second light beam directed from the reflective system to the second surface with a fourth lens disposed in an optical path between the reflective system and the second surface and collimating the second light beam reflected from the second surface back to the reflective system; collimating the second light beam directed from the reflective system to the second surface with a fifth lens disposed in the optical path between the reflective system and the second surface and converging the second light beam directed from the second surface to the reflective system; and collimating the first and second light beams with a sixth lens disposed on an optical path between the beam splitter and the imaging system, wherein the second light beam sequentially passes through the fourth and fifth lenses as it is directed from the reflective system to the second surface; the second light beam sequentially passes through the fifth lens and the fourth lens during reflection of the second light beam from the second surface back to the reflection system.

In combination with the second aspect, in some embodiments, the reflective system includes a plurality of reflective units.

With reference to the second aspect, in some embodiments, the plurality of reflection units includes a transflective unit, such that a portion of the second light beam passes through the transflective unit towards the hartmann sensor.

With reference to the second aspect, in some embodiments, the first light beam is the portion of the light beam that is reflected by the beam splitter, the second light beam is the portion of the light beam that passes through the beam splitter, and the first light beam is perpendicular to the second light beam; an included angle between a reflection plane of the beam splitter, which reflects the second light beam to the reflection system, and the first surface is 45 degrees, the plurality of reflection units include a first reflection unit, a second reflection unit, and a third reflection unit, the reflection plane of the beam splitter, which reflects the second light beam to the reflection system, is perpendicular to the reflection plane of the first reflection unit, the reflection plane of the first reflection unit is perpendicular to the reflection plane of the second reflection unit, the reflection plane of the second reflection unit is perpendicular to the reflection plane of the third reflection unit, and the included angle between the reflection plane of the third reflection unit and the second surface is 45 degrees; the second light beam is emitted to the first surface along a direction perpendicular to the first surface and is emitted to the second surface along a direction perpendicular to the second surface.

The measuring device and the measuring method provided by the embodiment of the application can reduce the influence of vibration on the measuring result and improve the accuracy of the measuring result.

Drawings

Fig. 1 is a schematic structural diagram of a measurement apparatus according to an embodiment of the present application.

Fig. 2 is a schematic view of the measuring device in fig. 1.

Fig. 3 is a schematic structural diagram of a measurement apparatus according to another embodiment of the present application.

Fig. 4 is a schematic structural diagram of a measurement apparatus according to another embodiment of the present application.

Fig. 5 is a schematic structural diagram of a measurement apparatus according to another embodiment of the present application.

FIG. 6 is a schematic diagram of a measurement method according to an embodiment of the present application.

Detailed Description

Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather these embodiments are provided for a more complete and thorough understanding of the present application. It should be understood that the drawings and embodiments of the present application are for illustration purposes only and are not intended to limit the scope of the present application.

Fig. 1 is a schematic structural diagram of a measurement apparatus according to an embodiment of the present application. As shown in FIG. 1, in this embodiment, the measurement device includes a beam splitter 12 and a reflection system 141,142,143.

The beam splitter is an optical device capable of splitting a beam into two or more beams, and the implementation manner of the beam splitter is various, and the embodiment of the present application is not limited to the specific implementation manner of the beam splitter.

The beam splitter 12 may be used to split the light beam provided by the light source 11 into a first light beam and a second light beam. For example, in some embodiments, the first light beam may be the portion of the light beam provided by the light source 11 that is reflected by the beam splitter 12, and the second light beam may be the portion of the light beam provided by the light source 11 that passes through the beam splitter 12. For example, in some embodiments, the direction of propagation of the first light beam may be perpendicular to the direction of propagation of the second light beam.

The first beam may be directed toward the imaging system 13 and the second beam may be directed toward a first surface of the wafer 100 (i.e., the surface of the wafer 100 facing the beam splitter 12). For example, in some embodiments, the second beam may be directed toward the first surface of the wafer 100 to be tested in a direction perpendicular to the first surface of the wafer 100 to be tested.

The first surface of the wafer 100 to be tested reflects the second beam, which is reflected back to the beam splitter 12.

The beam splitter 12 may also be used to reflect the second light beam reflected off the first surface to a reflection system 141,142,143. The reflection systems 141,142,143 can be used to reflect the second light beam to a second surface of the wafer 100 to be tested opposite to the first surface (i.e., the surface of the wafer 100 to be tested facing away from the beam splitter 12). For example, in some embodiments, the second beam may be directed toward the second surface of the wafer 100 to be tested in a direction perpendicular to the second surface of the wafer 100 to be tested.

The second surface of the wafer 100 reflects the second beam of light, thereby reflecting the second beam of light back to the reflective system 141,142,143. The reflective system 141,142,143 can also be used to reflect the second beam reflected from the second surface to the beam splitter 12 so that the second beam passes through the beam splitter 12 towards the imaging system 13.

The imaging system 13 may obtain an interference image according to the first light beam and the second light beam, and the related person may analyze the thickness of the wafer according to the interference image, so as to measure the thickness of the wafer.

The measuring device provided by the embodiment can reduce the influence of vibration on the measuring result and improve the accuracy of the measuring result. For ease of understanding, the working principle of the measuring device is illustrated below with reference to fig. 2.

As shown in fig. 2, the portion of the light beam from the light source 11 reflected by the beam splitter 12 (i.e., the first light beam) directly enters the imaging system 13, and the portion of the light beam passing through the beam splitter 12 (i.e., the second light beam) needs to pass through a predetermined path and reach two opposite surfaces (i.e., the first surface and the second surface) of the wafer 100 to be measured, respectively, before entering the imaging system 13.

The path of the predetermined path (i.e., the sum of S1, S2, S3, S4 and S5) is only related to the thickness of the wafer 100 to be tested, and the displacement of the wafer 100 to be tested in the thickness direction (i.e., the Z-axis direction in fig. 2) does not cause the path of the predetermined path to change.

For example, if the wafer 100 to be tested moves toward the beam splitter 12, S1 decreases, S5 increases, and the sum of S1, S2, S3, S4, and S5 does not change. Conversely, if the wafer 100 to be tested moves away from the beam splitter 12, S1 increases and S5 decreases, and the sum of S1, S2, S3, S4 and S5 also does not change.

It can be seen that the optical path difference between the portion of the light beam from the light source 11 reflected by the beam splitter 12 and the portion passing through the beam splitter 12 when reaching the imaging system is only related to the thickness of the wafer 100 to be measured, and the displacement of the wafer 100 in the thickness direction does not cause the change of the optical path difference. Thus, it can be ensured that the interference image obtained based on the two partial light beams is only related to the thickness of the wafer 100 to be measured, and is not affected by the displacement of the wafer 100 to be measured in the thickness direction.

In general, when the thickness of a wafer is measured by using an optical system based on an interferometer, vibration may cause the wafer to be displaced in the thickness direction thereof, thereby affecting the accuracy of measurement. The measuring result of the measuring device provided by the embodiment of the application cannot be influenced by the displacement of the wafer in the thickness direction of the wafer, so that the measuring device provided by the embodiment of the application can reduce the influence of vibration on the measuring result and improve the accuracy of the measuring result.

In some embodiments, referring again to fig. 1, beam splitter 12 may be a polarizing beam splitter. The measurement apparatus may further include a first quarter wave plate 151 and a second quarter wave plate 152.

The first quarter wave plate 151 is disposed on an optical path between the beam splitter 12 and the first surface of the wafer 100 to be measured.

During its passage from the beam splitter 12 to the first surface of the wafer 100 to be tested, the second beam passes through the first quarter waveplate 151. And, in the course of the second light beam going from the first surface of the wafer 100 to be measured to the beam splitter 12, the second light beam passes through the first quarter wave plate 151 again.

The second quarter wave plate 151 is disposed on the optical path between the beam splitter 12 and the second surface of the wafer 100 to be measured.

During the passage of the second beam from the beam splitter 12 to the second surface of the wafer 100 to be measured, the second beam passes through the second quarter wave plate 152. And, in the course of the second beam going from the second surface of the wafer 100 to be measured to the beam splitter 12, the second beam also passes through the second quarter waveplate 152.

After the light beam passes through the quarter-wave plate, the polarization state changes. The second light beam passes through the first quarter-wave plate twice in the process of being emitted from the beam splitter 12 to the first surface of the wafer 100 to be measured and reflected back to the beam splitter 12 by the first surface of the wafer 100 to be measured, and the polarization direction is perpendicular to the incident direction. Thus, when the beam splitter 12 is a polarization beam splitter, the second light beam reflected by the first surface of the wafer 100 to be tested is totally reflected by the beam splitter 12 to the reflection systems 141,142, and 143, thereby preventing the second light beam from passing through the beam splitter 12 to the light source 11.

Similarly, the second light beam passes through the second quarter-wave plate twice in the process of being emitted from the beam splitter 12 to the second surface of the wafer 100 to be tested and reflected by the second surface of the wafer 100 to be tested back to the beam splitter 12. Thus, when the beam splitter 12 is a polarization beam splitter, the second light beam reflected by the second surface of the wafer 100 to be tested passes through the beam splitter 12 and is emitted to the imaging system 13, so as to prevent the second light beam reflected by the second surface of the wafer 100 to be tested from being reflected by the beam splitter 12 to the first surface of the wafer 100 to be tested.

Whether the second light beam reflected from the first surface of the wafer 100 to be tested passes through the beam splitter 12 and is emitted to the light source 11, or the second light beam reflected from the second surface of the wafer 100 to be tested is reflected from the beam splitter 12 to the first surface of the wafer 100 to be tested, the second light beam also causes the loss of the light beam and generates an interference signal.

Therefore, the polarization beam splitter, the first quarter wave plate and the second quarter wave plate are arranged, so that the loss of light beams and the generation of interference signals can be avoided, and the accuracy of measurement results is further improved.

The implementation manner of the reflection system may be various, and the embodiment of the present application is not particularly limited to the specific implementation manner of the reflection system. For example, in some embodiments, the reflective system may include a plurality of reflective elements. For example, the reflection unit may be a mirror.

For ease of understanding, the reflective system is described below by way of example with reference to the accompanying drawings.

Referring again to fig. 1, the reflection system 141,142,143 may include, for example, a first reflection unit 141, a second reflection unit 142, and a third reflection unit 143.

For example, the reflection plane of the beam splitter 12 that reflects the second light beam to the reflection systems 141,142, and 143 (i.e., the reflection plane of the side of the beam splitter 12 facing the wafer 100) may be at an angle of 45 degrees with respect to the first surface of the wafer 100. The reflection plane of the beam splitter 12, which reflects the second light beam to the reflection system 141,142,143, may be perpendicular to the reflection plane of the first reflection unit 141. The reflection plane of the first reflection unit 141 may be perpendicular to the reflection plane of the second reflection unit 142. The reflection plane of the second reflection unit 142 may be perpendicular to the reflection plane of the third reflection unit 143. An included angle between the reflection plane of the third reflection unit 143 and the second surface of the wafer 100 to be tested is 45 degrees.

In this way, the second light beam may be reflected by the first reflection unit 141, the second reflection unit 142, and the third reflection unit 143 in sequence, and finally reach the second surface of the wafer 100 to be measured. Likewise, the second light beam may be reflected by the third reflection unit 143, the second reflection unit 142, and the first reflection unit 141 in sequence, and finally pass through the beam splitter 12 and finally be directed to the imaging system 13.

It should be understood that although in the embodiment shown in fig. 1 the reflection system comprises only three reflection units, in other embodiments of the present application the reflection system may comprise more reflection units. As to the number of the reflection units included in the reflection system, the embodiment of the present application is not particularly limited as long as the functions of the reflection system in the foregoing embodiment can be implemented.

In some embodiments, referring again to fig. 1, the measurement apparatus may further comprise an expanded beam collimation system 161,162. The beam expanding and collimating systems 161 and 162 are used for expanding and collimating the light beams provided by the light source 11, so that the range of the second light beam can cover the first surface of the wafer 100 to be measured, and the second light beam is a collimated light beam.

Illustratively, the beam expanding collimation system 161,162 may include a first lens 161 and a second lens 162. The light beam provided by the light source 11 may sequentially pass through the first lens 161 and the second lens 162 to be directed to the beam splitter 12. The first lens 161 may be used to diffuse the light beam, and the second lens 162 may be used to collimate the light beam, for example, so that beam expansion and collimation of the light beam provided by the light source 11 may be achieved.

The first lens 161 may be, for example, a concave lens such that the light beam is directly diffused when passing therethrough. The first lens 161 may also be a convex lens, for example, so that the light beam spreads after passing through the focal point when passing therethrough. The second lens 162 may be, for example, a convex lens.

It should be appreciated that although in the embodiment shown in fig. 1, the measurement device may include an expanded beam collimation system, in other embodiments of the present application, the measurement device may not include an expanded beam collimation system. For example, a light source that provides a collimated beam of light whose extent covers the surface of the wafer may be used.

In some embodiments, referring again to FIG. 1, the measurement apparatus may further include beam-demagnifying collimation systems 163,164. The beam-reducing collimation system 163,164 is used to reduce and collimate the first and second beams so that the first and second beams are passed through beam-reducing and collimation and then enter the imaging system 13.

Illustratively, the beam-collapsing collimation system 163,164 may include a third lens 163 and a fourth lens 164. The first and second light beams may be sequentially incident on the imaging system 13 from the beam splitter 12 through the third lens 163 and the fourth lens 164. The third lens 163 may condense the first and second light beams, and the fourth lens 164 may collimate the first and second light beams, so that the first and second light beams may be condensed and collimated.

The third lens 163 may be, for example, a convex lens. The fourth lens 164 may be, for example, a convex lens, and may also be, for example, a concave lens.

In some embodiments, the measurement device of embodiments of the present application may further include a hartmann sensor. One of the plurality of reflection units may be a transflective unit. The Hartmann sensor is a Hartmann-shack wavefront sensor. The transflective unit may be, for example, a transflective mirror.

Thus, when the second light beam reflected by the first surface or the second light beam reflected by the second surface passes through the transflective unit, a part of the light beam passes through the transflective unit to be emitted to the Hartmann sensor. Based on the second light beam reflected by the first surface or the second light beam reflected by the second surface, the deformation of the first surface or the second surface of the wafer can be analyzed by using a Hartmann sensor. And the flatness and the warping degree of the wafer can be analyzed by combining the surface deformation of the wafer and the thickness of the wafer, so that the flatness and the warping degree of the wafer can be measured.

For the convenience of understanding, the technical scheme is illustrated in the following by combining the attached drawings.

Fig. 3 is a measurement apparatus provided according to another embodiment of the present application. The measuring apparatus shown in fig. 3 is similar to the measuring apparatus shown in fig. 1, and in order to avoid redundancy, the same parts are not repeated, and the differences are mainly described here.

As shown in fig. 3, in this embodiment, the third reflection unit 143 may be a transflective unit, and the measurement device may further include a hartmann sensor 18.

In this embodiment, when the second light beam reflected by the second surface of the wafer 100 to be measured reaches the third reflecting unit 143, a part of the second light beam is reflected to the second reflecting unit 142, and another part of the second light beam passes through the third reflecting unit 143 and enters the hartmann sensor 18.

Therefore, the deformation of the second surface of the wafer can be analyzed through the Hartmann sensor, and the flatness and the warping degree of the wafer can be further analyzed by combining the thickness of the wafer.

In some embodiments, referring again to FIG. 3, the measurement device may further include beam-demagnifying collimation systems 165,166. During the passage of the second light beam from the third reflection unit 143 to the hartmann sensor 18, the second light beam passes through the beam-demagnifying collimating system 165,166. Beam-reducing collimation systems 165,166 are used to reduce and collimate the second beam.

There are various implementations of the beam-reducing collimation system 165,166, and the embodiments of the present application are not limited in this respect. For example, the beam-collapsing collimation system 165,166 may include a fifth lens 165 and a sixth lens 166. The fifth lens 165 may be used to focus the second light beam, for example, and the sixth lens 166 may be used to collimate the second light beam, for example. The fifth lens 165 may be, for example, a convex lens. The sixth lens 166 may be, for example, a convex lens, or may be, for example, a concave lens.

Fig. 4 is a measurement device provided according to another embodiment of the present application. The measuring device shown in fig. 4 is similar to the measuring device shown in fig. 3, and for the sake of simplicity, the description of the same parts is omitted.

As shown in fig. 4, in this embodiment, when the second light beam reflected by the first surface of the wafer 100 to be measured reaches the third reflection unit 143, a part of the second light beam is reflected to the second surface of the wafer 100 to be measured, and another part of the second light beam passes through the third reflection unit 143 and enters the hartmann sensor 18.

Therefore, the deformation of the first surface of the wafer can be analyzed through the Hartmann sensor, and the flatness and the warping degree of the wafer can be further analyzed by combining the thickness of the wafer.

It should be understood that although in the embodiment shown in fig. 3 and 4, third unit 143 is a transflective unit. However, in other embodiments of the present application, the transflective unit may be the first reflecting unit 141 or the second reflecting unit 142.

FIG. 5 is a schematic diagram of a measurement device according to another embodiment of the present application.

The measuring apparatus shown in fig. 5 is similar to the measuring apparatus shown in fig. 1, and in order to avoid repetition, the same parts are not repeated, and the differences are mainly described here.

As shown in fig. 5, in this embodiment, the measuring device may include a first lens 261, a second lens 262, a third lens 263, a fourth lens 264, a fifth lens 265, and a sixth lens 266.

The first lens 261 is disposed on an optical path between the light source 21 and the beam splitter 22, and diffuses the light beam provided from the light source 21.

The second lens 262 is disposed on the optical path between the beam splitter 22 and the first surface of the wafer 200 to be tested, and is used for collimating the second light beam emitted from the beam splitter 22 to the first surface of the wafer 200 to be tested, and for converging the second light beam reflected from the first surface of the wafer 200 to be tested back to the beam splitter 22.

The third lens 263 is disposed in the optical path between the beam splitter 22 and the reflection system 241,242,243 for collimating the second light beam emitted from the beam splitter 22 toward the reflection system 241,242,243 and for diffusing the second light beam emitted from the reflection system 241,242,243 toward the beam splitter 22.

The fourth lens 264 is disposed in the optical path between the reflection systems 241,242,243 and the second surface for diffusing the second light beams emitted from the reflection systems 241,242,243 to the second surface of the wafer 200 to be measured and for collimating the second light beams reflected from the second surface of the wafer 200 to be measured back to the reflection systems 241,242,243.

The fifth lens 265 is disposed on the optical path between the reflection systems 241,242,243 and the second surface of the wafer 200 to be tested, and is used for collimating the second light beams emitted from the reflection systems 241,242,243 to the second surface of the wafer 200 to be tested, and for converging the second light beams reflected from the second surface of the wafer 200 to be tested back to the reflection systems 241,242,243.

During the process of the second light beam from the reflection systems 241,242,243 to the second surface of the wafer 200 to be measured, the second light beam passes through the fourth lens 264 and the fifth lens 265 in sequence. During the process of reflecting the second light beam from the second surface of the wafer 200 to be measured back to the reflection systems 241,242,243, the second light beam sequentially passes through the fifth lens 265 and the fourth lens 264.

A sixth lens 266 is disposed in the optical path between the beam splitter 22 and the imaging system 23 for collimating the first and second light beams.

Specifically, in the course of the light beam provided by the light source 21 going from the light source 21 to the beam splitter 22, the light beam passes through the first lens 261. The first lens 261 may be used to diffuse the light beam. The first lens 261 may be, for example, a convex lens, and may also be, for example, a concave lens.

The beam splitter 22 is used to split the light beam provided by the light source 21 into a first light beam and a second light beam. The first beam is directed to the imaging system 23 and the second beam is directed to the first surface of the wafer 200 to be measured.

During the passage of the second beam from the beam splitter 22 to the first surface of the wafer 200 to be tested, the second beam passes through the second lens 262. The second lens 262 may be used to collimate the second light beam. The second lens 262 may be, for example, a convex lens.

After the second beam reaches the first surface of the wafer 200, the first surface reflects the second beam back to the beam splitter 22.

During the reflection of the second beam from the first surface of the wafer 200 to be tested back to the beam splitter 22, the second beam passes through the second lens 262. The second lens may be for converging the second light beam.

After the second beam is reflected back to the beam splitter 22, the beam splitter reflects the second beam reflected back from the first surface to the reflection system 241,242,243.

During its passage from the beam splitter 22 to the reflection system 241,242,243, the second light beam passes through the third lens 263. The third lens 263 is used for collimating the second light beam. The third lens 263 may be, for example, a convex lens, and may also be, for example, a concave lens.

The reflection system 241,242,243 is used to reflect the second light beam to a second surface of the wafer 200 opposite to the first surface.

During the passage of the second beam from the reflection system 241,242,243 to the second surface of the wafer 200 to be measured, the second beam passes through the fourth lens 264 and the fifth lens 265 in sequence. The fourth lens 264 is used for diffusing the second light beam, and the fifth lens 265 is used for collimating the second light beam. The fourth lens 264 may be, for example, a convex lens, and may also be, for example, a concave lens. The fifth lens 265 may be, for example, a convex lens.

After the second light beam reaches the second surface of the wafer 200 to be measured, the second surface reflects the second light beam back to the reflection system 241,242,243.

The second light beam passes through the fifth lens 265 and the fourth lens 264 in sequence as it travels from the second surface to the reflective system 241,242,243. The fifth lens 265 is used for converging the second light beam, and the fourth lens 264 is used for collimating the second light beam.

After the second light beam reaches the reflection system 241,242,243, the reflection system 241,242,243 reflects the second light beam to the beam splitter 22.

During its passage from the reflection system 241,242,243 to the beam splitter 22, the second light beam again passes through the third lens 263. The third lens 263 is used for diffusing the second light beam.

The second beam passes through the beam splitter 22 and is directed to the imaging system 23. In the course of the first and second beams going from the beam splitter 22 to the imaging system 23, the first and second beams pass through the sixth lens 266. The sixth lens 266 is used to collimate the first and second beams.

By providing the first lens 261, the second lens 262, the third lens 263, the fourth lens 264, the fifth lens 265, and the sixth lens 266, the entire size of the measurement apparatus can be reduced.

Specifically, the lens assembly formed by the first lens 261 and the second lens 262 can expand and collimate the second light beam, so that the second light beam incident on the first surface is a collimated light beam, and the range of the second light beam can cover the first surface of the wafer 200 to be measured.

The lens assembly of the second lens 262 and the third lens 263 can collimate the second beam to reduce the extent of the second beam before it reaches the reflective system 241,242,243. In this way, a smaller size of the reflective system 241,242,243 can be used.

The lens group formed by the fourth lens 264 and the fifth lens 265 can expand and collimate the second light beam, so that the second light beam incident on the second surface is a collimated light beam, and the range of the second light beam can cover the second surface of the wafer 200 to be measured.

The lens assembly of the fifth lens 265 and the fourth lens 264 collimates the second light beam to reduce the extent of the second light beam before it reaches the reflective system 241,242,243.

The lens group consisting of the first lens 261 and the sixth lens 266 can expand and collimate the first light beam, so that the first light beam entering the imaging system is a collimated light beam.

The lens group formed by the third lens 263 and the sixth lens 266 can expand and collimate the second light beam, so that the second light beam entering the imaging system is a collimated light beam.

Also, in this embodiment, the beam splitter 22 may be smaller in size.

Therefore, the technical scheme provided by the embodiment can reduce the size of the measuring device and the components thereof, and reduce the cost of the measuring device.

In some embodiments, referring again to fig. 5, the beam splitter 22 may be a polarizing beam splitter. The measurement apparatus may further include a first quarter wave plate 251 and a second quarter wave plate 252.

During the process of the second beam from the beam splitter 22 to the first surface of the wafer 200 to be tested, the second beam passes through the first quarter wave plate 251. And, in the course of the second beam going from the first surface of the wafer 200 to be tested to the beam splitter 22, the second beam also passes through the first quarter waveplate 251.

During the passage of the second beam from the beam splitter 22 to the second surface of the wafer 200 to be tested, the second beam passes through the second quarter waveplate 252. And, in the course of the second light beam going from the second surface of the wafer 200 to be measured to the beam splitter 22, the second light beam passes through the second quarter waveplate 252.

The measuring device according to the embodiment of the present application is described in detail above with reference to fig. 1 to 5, and the measuring method according to the embodiment of the present application is described in detail below with reference to fig. 6. The descriptions of the method embodiments and the apparatus embodiments correspond to each other, and overlapping descriptions are appropriately omitted for the sake of brevity.

Fig. 6 is a flowchart illustrating a measurement method according to an embodiment of the present application.

The measurement method S100 may be performed by the aforementioned measurement apparatus. As shown in fig. 6, the measurement method S100 includes steps S110 to S140.

In step S110, a beam provided by a light source is split into a first beam directed to an imaging system and a second beam directed to a first surface of a wafer to be measured using a beam splitter.

In step S120, the second light beam reflected by the first surface of the wafer to be tested is reflected to the reflection system by the beam splitter.

In step S130, the second light beam reflected from the first surface of the wafer to be measured is reflected to a second surface of the wafer to be measured opposite to the first surface by using a reflection system.

In step S140, the second light beam reflected by the second surface of the wafer to be tested is reflected to the beam splitter by the reflection system, so that the second light beam reflected by the second surface passes through the beam splitter and is emitted to the imaging system.

The imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface.

The measuring method provided by the embodiment of the application can reduce the influence of vibration on the measuring result and improve the accuracy of the measuring result.

In some embodiments, the second beam passes through the first quarter wave plate during its passage from the beam splitter to the first surface of the wafer to be measured. And in the process that the second light beam is reflected back to the beam splitter from the first surface of the wafer to be measured, the second light beam passes through the first quarter wave plate.

And in the process that the second light beam is emitted to the second surface of the wafer to be measured from the beam splitter, the second light beam passes through the second quarter wave plate. And in the process that the second light beam is reflected back to the beam splitter from the second surface of the wafer to be measured, the second light beam passes through the second quarter wave plate.

In some embodiments, the measurement method S100 may further include the steps of: diffusing the light beam by using a first lens arranged on a light path between the light source and the beam splitter; collimating a second light beam emitted from the beam splitter to the first surface of the wafer to be detected by using a second lens arranged on a light path between the beam splitter and the first surface of the wafer to be detected, and converging the second light beam reflected back to the beam splitter from the first surface of the wafer to be detected; collimating a second light beam emitted from the beam splitter to the reflection system by using a third lens arranged on a light path between the beam splitter and the reflection system, and diffusing the second light beam emitted from the reflection system to the beam splitter; diffusing the second light beam emitted from the reflection system to the second surface of the wafer to be detected by using a fourth lens arranged on a light path between the reflection system and the second surface of the wafer to be detected, and collimating the second light beam reflected from the second surface of the wafer to be detected back to the reflection system; collimating the second light beam emitted from the reflection system to the second surface of the wafer to be detected by using a fifth lens arranged on a light path between the reflection system and the second surface of the wafer to be detected, and converging the second light beam emitted from the second surface of the wafer to be detected to the reflection system; and collimating the first and second beams with a sixth lens disposed in an optical path between the beam splitter and the imaging system.

In addition, in the process that the second light beam is emitted to the second surface of the wafer to be detected from the reflection system, the second light beam sequentially passes through the fourth lens and the fifth lens; and in the process that the second light beam is reflected back to the reflection system from the second surface of the wafer to be measured, the second light beam sequentially passes through the fifth lens and the fourth lens.

In some embodiments, the reflective system comprises a plurality of reflective units.

In some embodiments, the plurality of reflective elements includes a transflective element such that a portion of the second light beam passes through the transflective element toward the Hartmann sensor.

In some embodiments, the first beam is the portion of the beam that is reflected by the beam splitter and the second beam is the portion of the beam that passes through the beam splitter, the first beam being perpendicular to the second beam.

The included angle between the reflecting plane of the beam splitter, which reflects the second light beam to the reflecting system, and the first surface of the wafer to be measured is 45 degrees. The plurality of reflection units include a first reflection unit, a second reflection unit, and a third reflection unit. The reflection plane of the beam splitter, which reflects the second light beam to the reflection system, is perpendicular to the reflection plane of the first reflection unit. The reflection plane of the first reflection unit is perpendicular to the reflection plane of the second reflection unit. The reflection plane of the second reflection unit is perpendicular to the reflection plane of the third reflection unit. An included angle between the reflection plane of the third reflection unit and the second surface of the wafer to be tested is 45 degrees.

The second light beam is emitted to the first surface of the wafer to be detected along the direction vertical to the first surface of the wafer to be detected and is emitted to the second surface of the wafer to be detected along the direction vertical to the second surface of the wafer to be detected.

It will be appreciated that in some embodiments the light source may form part of the measuring device, i.e. the measuring device may comprise the light source. In some embodiments, the light source may also be an external light source that is independent of the measurement device, i.e., the measurement device may not include a light source.

Likewise, it should be understood that in certain embodiments, the imaging system may form part of the measurement device, i.e., the measurement device may include the imaging system. In some embodiments, the imaging system may also be an external imaging system that is independent of the measurement device, i.e., the measurement device may not include an imaging system.

It is to be understood that, as used herein, the terms "includes," including, "and variations thereof are intended to be open-ended, i.e.," including, but not limited to. The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment".

It should be understood that although the terms "first" or "second," etc. may be used herein to describe various elements (e.g., beams, surfaces of wafers, reflective elements, lenses, etc.), these elements are not limited by these terms, which are used only to distinguish one element from another.

The above description is only for the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can think of the changes or substitutions within the technical scope of the present application, and shall be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (12)

1. A measuring device, comprising: a beam splitter and a reflection system, wherein,

the beam splitter is used for splitting a light beam provided by the light source into a first light beam emitted to the imaging system and a second light beam emitted to the first surface of the wafer to be measured, and reflecting the second light beam reflected by the first surface to the reflecting system;

the reflection system is used for reflecting the second light beam reflected by the first surface to a second surface of the wafer to be measured, wherein the second light beam is opposite to the first surface, and the second light beam reflected by the second surface is reflected to the beam splitter, so that the second light beam reflected by the second surface passes through the beam splitter and is emitted to the imaging system, and the imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface.

2. The measurement device of claim 1, wherein the beam splitter is a polarizing beam splitter, the measurement device further comprising a first quarter wave plate and a second quarter wave plate, wherein,

the first quarter wave plate is arranged on an optical path between the beam splitter and the first surface, wherein the second light beam passes through the first quarter wave plate during the process of being emitted from the beam splitter to the first surface, and passes through the first quarter wave plate during the process of being reflected back to the beam splitter from the first surface;

the second quarter wave plate is arranged on an optical path between the beam splitter and the second surface, wherein the second light beam passes through the second quarter wave plate in the process of being emitted from the beam splitter to the second surface; the second beam passes through the second quarter wave plate during reflection of the second beam from the second surface back to the beam splitter.

3. The measurement device of claim 1, further comprising:

the first lens is arranged on a light path between the light source and the beam splitter and used for diffusing the light beam;

a second lens disposed on an optical path between the beam splitter and the first surface for collimating the second light beam emitted from the beam splitter toward the first surface and for converging the second light beam reflected from the first surface back to the beam splitter;

a third lens disposed on an optical path between the beam splitter and the reflection system, for collimating the second light beam emitted from the beam splitter to the reflection system, and for diffusing the second light beam emitted from the reflection system to the beam splitter;

a fourth lens disposed on an optical path between the reflection system and the second surface, for diffusing the second light beam emitted from the reflection system toward the second surface, and for collimating the second light beam reflected from the second surface back to the reflection system;

a fifth lens disposed on an optical path between the reflection system and the second surface, for collimating the second light beam emitted from the reflection system toward the second surface, and for converging the second light beam reflected from the second surface back to the reflection system; and

a sixth lens disposed on an optical path between the beam splitter and the imaging system to collimate the first and second light beams,

wherein the second light beam sequentially passes through the fourth lens and the fifth lens during the second light beam is emitted from the reflection system to the second surface; the second light beam sequentially passes through the fifth lens and the fourth lens during reflection of the second light beam from the second surface back to the reflection system.

4. A measuring device according to any one of claims 1 to 3, wherein the reflection system comprises a plurality of reflection units.

5. The measurement device of claim 4, further comprising a Hartmann sensor, wherein the plurality of reflection units comprises a transflective unit such that a portion of the second light beam passes through the transflective unit toward the Hartmann sensor.

6. The measurement device of claim 4, wherein the first beam is the portion of the beam that is reflected by the beam splitter, the second beam is the portion of the beam that passes through the beam splitter, and the first beam is perpendicular to the second beam;

an included angle between a reflection plane of the beam splitter, which reflects the second light beam to the reflection system, and the first surface is 45 degrees, the plurality of reflection units include a first reflection unit, a second reflection unit, and a third reflection unit, the reflection plane of the beam splitter, which reflects the second light beam to the reflection system, is perpendicular to the reflection plane of the first reflection unit, the reflection plane of the first reflection unit is perpendicular to the reflection plane of the second reflection unit, the reflection plane of the second reflection unit is perpendicular to the reflection plane of the third reflection unit, and the included angle between the reflection plane of the third reflection unit and the second surface is 45 degrees;

the second light beam is emitted to the first surface along a direction perpendicular to the first surface and is emitted to the second surface along a direction perpendicular to the second surface.

7. A method of measurement, comprising:

splitting a light beam provided by a light source into a first light beam emitted to an imaging system and a second light beam emitted to a first surface of a wafer to be measured by using a beam splitter;

reflecting the second light beam reflected back from the first surface to a reflection system using the beam splitter;

reflecting the second light beam reflected by the first surface to a second surface of the wafer to be measured, which is opposite to the first surface, by using the reflection system; and

and reflecting the second light beam reflected by the second surface to the beam splitter by using the reflecting system, so that the second light beam reflected by the second surface passes through the beam splitter to be emitted to the imaging system, wherein the imaging system is used for obtaining an interference image according to the first light beam and the second light beam reflected by the second surface.

8. The measurement method of claim 7, wherein the second beam passes through a first quarter wave plate during its passage from the beam splitter to the first surface; the second beam passes through the first quarter wave plate during reflection of the second beam from the first surface back to the beam splitter; and

passing the second beam through a second quarter wave plate during the passage of the second beam from the beam splitter to the second surface; the second beam passes through the second quarter wave plate during reflection of the second beam from the second surface back to the beam splitter.

9. The measurement method according to claim 7, further comprising:

diffusing the light beam with a first lens disposed on an optical path between the light source and the beam splitter;

collimating said second beam of light directed from said beam splitter toward said first surface with a second lens disposed in the path of light between said beam splitter and said first surface and converging said second beam of light reflected back from said first surface to said beam splitter;

collimating the second light beam directed from the beam splitter to the reflection system with a third lens disposed on an optical path between the beam splitter and the reflection system, and diffusing the second light beam directed from the reflection system to the beam splitter;

diffusing the second light beam directed from the reflective system toward the second surface with a fourth lens disposed in an optical path between the reflective system and the second surface and collimating the second light beam reflected from the second surface back to the reflective system;

collimating the second light beam directed from the reflective system to the second surface with a fifth lens disposed in the optical path between the reflective system and the second surface and converging the second light beam directed from the second surface to the reflective system; and

collimating the first and second light beams with a sixth lens disposed in an optical path between the beam splitter and the imaging system,

wherein the second light beam sequentially passes through the fourth lens and the fifth lens in a process in which the second light beam is emitted from the reflection system to the second surface; the second light beam sequentially passes through the fifth lens and the fourth lens during reflection of the second light beam from the second surface back to the reflection system.

10. The measurement method according to any one of claims 7 to 9, wherein the reflection system comprises a plurality of reflection units.

11. The method of claim 10, wherein the plurality of reflecting elements comprises a transflective element such that a portion of the second light beam passes through the transflective element toward the Hartmann sensor.

12. The measurement method of claim 10, wherein the first beam is a portion of the beam reflected by the beam splitter, the second beam is a portion of the beam passing through the beam splitter, and the first beam is perpendicular to the second beam;

an included angle between a reflection plane of the beam splitter, which reflects the second light beam to the reflection system, and the first surface is 45 degrees, the plurality of reflection units include a first reflection unit, a second reflection unit, and a third reflection unit, the reflection plane of the beam splitter, which reflects the second light beam to the reflection system, is perpendicular to the reflection plane of the first reflection unit, the reflection plane of the first reflection unit is perpendicular to the reflection plane of the second reflection unit, the reflection plane of the second reflection unit is perpendicular to the reflection plane of the third reflection unit, and the included angle between the reflection plane of the third reflection unit and the second surface is 45 degrees;

the second light beam is emitted to the first surface along a direction perpendicular to the first surface and is emitted to the second surface along a direction perpendicular to the second surface.

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