KR20080098811A - Surface measurement apparatus - Google Patents

Abstract

The precision is improved even when measuring the large area to be the superhigh speed. The surface measurement apparatus in which the measurement of three dimensional shape is possible can be provided. The light source is for irradiating the laser beam(L). A rotating reflection mirror is for irradiating the laser beam on one-way. The first optical system(214) receives the laser beam from the rotating reflection mirror and scan the measurement object. The beam(Ls) is reflected to the rotating reflection mirror. The second optical system(215) have the fixed beam path. One or more reflected beam detection unit detects the beam reflected with the rotating reflection mirror.

Description

SURFACE MEASUREMENT APPARATUS

1 is a schematic view for explaining a surface measuring apparatus according to the prior art.

2 is a schematic view showing a surface measuring apparatus according to an embodiment of the present invention.

3 is a schematic view showing a surface measuring apparatus having a configuration in which an ftheta lens is added in the embodiment of FIG. 2.

4 is a schematic diagram illustrating a surface measuring apparatus having two reflection beam detection units in the embodiment of FIG. 3.

5 is a schematic view showing a surface measuring apparatus according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

201: galvano mirror 501: polygon mirror

202,205: Relay lens group 203,204: Reflective mirror

206: wafer 207: scattering beam detection unit

208: condenser lens 209: reflected beam detector

210a and 210b: first and second f-theta lenses 211: beam splitter

214, 215: first and second optical system 212: position signal detector

213: reflected light amount detector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface measuring apparatus for measuring foreign matters on the surface of a wafer, and more particularly, to a surface measuring apparatus having improved measurement speed and precision by using a beam scan method.

In general, semiconductor integrated circuits are manufactured by forming circuits on a wafer in accordance with photolithography processes or the like. In this case, a plurality of identical integrated circuits are arranged on the wafer, and the individual integrated circuit chips are manufactured by separating them.

If foreign matters or the like exist on the wafer in such a semiconductor integrated circuit, defects are likely to occur in the circuit pattern formed in the portion where the foreign matters and the like exist, and thus, the use of the integrated circuit may become impossible. As a result, the number of integrated circuits that can be obtained from a single wafer is reduced and yield is lowered.

In addition to semiconductor integrated circuits, advanced materials for which micrometer-sized foreign substances or defects cause defects include glass for display and substrate circuit materials.

Therefore, there is a need for equipment capable of measuring and inspecting such foreign objects or defects.

In general, as a method of measuring a foreign material or a defect on a wafer, a laser is focused on the wafer surface, a scattered light scattered from the light collecting point, and a foreign material or the like is detected from the signal.

1 is a schematic view for explaining a surface measuring apparatus according to the prior art.

Referring to FIG. 1, the surface measuring apparatus 10 according to the related art includes a measurement object 11, such as a light source and a wafer that emit a laser beam L, and first and second beam detectors 12 and 13. It is configured by.

In this case, the first beam detector 12 detects the scattered beam Ls from the wafer 11. That is, the light scattered from the light collecting point on the wafer 11 is collected by the first beam detector 12 corresponding to the photoelectric converter using a lens. The first beam detector which collects the scattered light outputs a pulse-shaped signal according to the intensity of the beam scattered by the laser beam L by the foreign material, and determines the size of the foreign object according to the magnitude of the signal output. Can be.

In addition, the second beam detector 13 detects the beam Lr reflected by the wafer 11.

As described above, the surface measuring apparatus 10 detects both signals by the scattering beam and the reflection beam, thereby measuring the presence or absence of foreign matter on the wafer 11 and the size of the foreign matter, and further measuring the angle of the reflected beam. Three-dimensional shape can be measured.

However, in general, the surface measuring apparatus 10 is a method in which optical components such as the first and second beam detectors 12 and 13 are fixed and a stage (not shown) in which the wafer 11 is disposed is transferred. to be.

This stage transfer method can be pointed out as a disadvantage that the measurement speed is very slow, and furthermore, because the path of the scattered and reflected beam changes as the stage moves, there is a problem that the beam detector must move in the same manner.

The present invention has been made to solve the above problems, and an object of the present invention is to measure a large area at a high speed by using a beam scan method, while improving accuracy, and furthermore, a surface measuring apparatus capable of measuring a three-dimensional shape. To provide.

In order to achieve the above object, the present invention,

A light source for emitting a laser beam, a rotating reflection mirror that scans the laser beam in one direction, a first optical system that receives the laser beam scanned by the rotating reflection mirror, and scans the laser beam to a measurement object; A second optical system and a second optical system configured to provide a beam reflected by the measurement object to the rotating reflection mirror, and the beam provided on the rotating reflection mirror is reflected by the rotating reflection mirror to have a constant beam path The present invention provides a surface measuring apparatus including at least one reflected beam detector for detecting a beam reflected by the rotating reflection mirror.

Additionally, the reflected beam detector includes first and second reflected beam detectors, and splits a beam reflected from the rotating reflection mirror toward the reflective beam detector and provides the beams to the first and second reflected beam detectors, respectively. It may further include a splitter. In this case, the first reflected beam detector is a position signal detector, and the second reflected beam detector is a reflected light amount detector.

In addition, the beam splitter may have a beam transmittance of 50%.

Preferably, the first and second optical systems may include a relay lens group and a reflection mirror, respectively.

The rotation reflecting mirror may have a first reflecting surface through which the laser beam is incident and a second reflecting surface through which the beam returned through the second optical system is incident.

Specifically, the rotation reflecting mirror may be a galvano mirror, and may also be a polygon mirror.

For the two-dimensional beam scanning effect, the laser beam may further include a stage for moving the measurement object in a direction different from the direction in which it is scanned to the measurement object, more preferably, the moving direction of the stage is the laser The beam may be perpendicular to the direction in which the beam is scanned onto the measurement object.

As an additional component, the surface measuring apparatus may include a first f-theta lens disposed on a beam path between the first optical system and a measurement object and a second f disposed on a beam path between the measurement object and the second optical system. Theta lens may further include.

On the other hand, disposed on the measurement object, may further include a scattering beam detector for detecting the scattered beam from the measurement object, in this case, additionally, by condensing the beam scattered from the measurement object to the scattering beam detector It may further include a condenser lens provided in.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

2 is a schematic view showing a surface measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the surface measuring apparatus according to the present embodiment includes a light source for emitting a laser beam L, a galvano mirror 201, first and second optical systems 214 and 215, and first and second devices. F-theta lenses 210a and 210b, scattered beam detector 207, and reflected beam detector 209 are provided.

In this case, a measurement object such as a wafer 206 to be subjected to surface measurement is disposed on a movable stage not shown.

Hereinafter, the components of the surface measuring apparatus will be described in detail.

The galvano mirror 201 includes a rotating unit 201a and a reflecting unit 201b, and performs a function of scanning the laser beam L emitted from the light source along one direction. That is, in the galvano mirror 201, the reflection path of the laser beam L incident on the reflection part 201b is changed by rotating the reflection part 201b along the rotation axis by the rotation part 201a such as a motor. . Specifically, as shown in FIG. 2, as the reflector 201b rotates, the laser beam L changes its reflection path from L1 to L2 and again from L2 to L3. In addition, since the path change is continuous, there are countless beams not shown between the reflected beams L1, L2, and L3. Therefore, in the present embodiment, the reflection beams L1, L2, and L3 are described with reference to the behavior of the scanned beam, but this behavior can be applied to other beams not shown.

In the present embodiment, a galvano mirror is employed as the beam scanning means. However, according to the embodiment, as described later, a rotation reflecting mirror of another structure such as a polygon mirror may be employed.

The laser beams L1, L2, and L3 scanned by the galvano mirror 201 are adjusted to a beam path by the first optical system 214 and are scanned onto the wafer 206.

The first optical system 214 has a structure including a relay lens group 202 and a reflection mirror 203. In this case, the relay lens group 202 causes the focal point of the beams reflected by the galvano mirror 201 to form a predetermined straight line on the reflection surface of the reflection mirror 203, as shown in FIG. 2. Likewise, two or three or more lenses may be combined.

The reflection mirror 203 reflects the beam passing through the relay lens group 202 to scan the wafer 206.

However, if the first optical system 214 can receive the beam from the galvano mirror 201 and scan the wafer 206, the first optical system 214 may have a form in which optical elements are adopted and arranged differently from the present embodiment.

Subsequently, the beam passing through the first optical system 214 is scanned onto the wafer 206 and scattered or reflected depending on the shape of the surface of the wafer 206.

First, the beam Ls scattered from the surface of the wafer 206 is incident on the scattering beam detector 207. In the present embodiment, the scattering beam detection unit 207 is disposed on the wafer 206, and the position of the wafer 206 can be determined by converting an optical signal into a current signal and analyzing it, which will be described later. It may be used to correct the output of the reflected beam detector 209. That is, the scattering beam detector 207 is for detecting the noise signal Ls diffusely reflected by the beam scattered from the wafer 206, that is, foreign matter present on the surface. When there is no foreign material or scratches in the process of scanning the beam on the wafer 206 surface, most of the beam is reflected without being scattered and received by the reflective beam detector 209 which will be described later. As a result, the intensity of the scattering beam Ls is increased, and the signal and the reflected beam may be analyzed together to determine the location of the foreign material or the size of the foreign material.

In addition, as in the present embodiment, a condenser lens 208 is disposed between the scattered beam detector 207 and the wafer 206 so as to focus the scattered beam Ls to be detected and provide the scattered beam detector 207. Can be.

On the other hand, as described above, the wafer 206 is disposed on the movable stage, it can be seen that the beam is scanned in two dimensions. That is, in the surface measuring apparatus according to the prior art, the method of fixing the laser beam and moving the wafer from side to side, but the surface measuring apparatus according to the present embodiment, the laser beam (L) incident at a fixed point (0 dimension) ) Can be scanned in one dimension by the galvano mirror 201, and furthermore, the wafer 206 is moved in a direction different from the direction in which the beam is scanned, thereby making it easier to see the two-dimensional beam scanning effect. It is.

In this case, as shown in FIG. 2, the wafer 206 is most preferably moved in a direction perpendicular to the direction in which the laser beam is scanned. However, the present invention is not limited thereto. Another direction of movement may be chosen which may have an injection effect.

As described above, the scattering beam detection unit 207 measures the signal of the beam Ls scattered from the wafer 206, and the surface measuring apparatus according to the present embodiment uses the wafer 206. Detects the reflected beam.

To this end, the beam reflected from the wafer 206 of the scanning beam travels toward the second optical system 215. The second optical system 215 has a symmetrical structure with the first optical system 214 and includes a reflection mirror 204 and a relay lens group 205 like the first optical system 214.

Non-scattered and reflected beams at the wafer 206 are focused to form a constant straight line on the reflective surface of the reflective mirror 204. Accordingly, the reflected beams are provided to the relay lens group 205 by the reflection mirror 204 and returned to the galvano mirror 201 by the relay lens group 205. Accordingly, the relay lens group 205 may have the same structure as that of the relay lens group 202 included in the first optical system and perform the same function.

Meanwhile, it is possible to adjust the arrangement of the first optical system 214 and the reflecting mirror 204 to form a constant straight line of the reflecting mirror 204 with the focal position of the beams reflected from the wafer 206. Can be.

The beam returned to the galvano mirror 201 through the second optical system 215 is reflected by the reflecting unit 201b and is incident to the reflecting beam detector 209. Specifically, the beam returned to the galvano mirror 201 is incident on the surface opposite to the incident surface of the laser beam (L). In this case, the beam Lr reflected by the reflector 201b has a constant beam path despite the passage of time. That is, the beams L1, L2, and L3 scanned on the wafer 206 having different beam paths and returned to the reflector 201b are reflected by the reflector 201b to reflect the beams in the same path. The detector 209 may be incident to the detector 209 by adjusting the arrangement of the second optical system 215.

As described above, in the surface measuring apparatus, the galvano mirror 201 is rotated so that the beam path is continuously changed. Accordingly, the surface measuring apparatus is incident again to the galvano mirror 201 through the wafer 206. The path of the beam also changes continuously.

However, as the galvano mirror 201 is rotated to change the incident angle of the laser beam L, the incident angle of the beam returned to the opposite reflective surface is also changed by the same amount in the opposite direction. Therefore, the path of the beam Lr reflected again by the galvano mirror 201 may be kept constant. Accordingly, according to this embodiment, since the path of the reflection beam to be used for detection can be kept constant, there is no need to move the reflection beam detection unit 209. In addition, as will be described in the embodiment shown in FIG. 4, if the path of the reflection beam to be used for detection is constant, various signals can be analyzed through the plurality of detection units by dividing them. Accordingly, if a plurality of detection units are properly disposed, more accurate surface state can be measured, and further, three-dimensional three-dimensional information can be obtained. More details on this will be described later.

Meanwhile, the reflected beam detector 209 detecting the beam Lr converts an optical signal into an electrical signal like the scattered beam detector 207 and analyzes it. As described above, the surface of the reflective beam detector 209 and the scattered beam detector 207 may be analyzed together.

In this embodiment, the galvano mirror 201 has two reflective surfaces, and the incident surface of the beam returned to the galvano mirror 201 is the opposite surface to the surface where the laser beam L is first incident. The case was explained. In most cases, the structure will be the same as that of the present embodiment, but depending on the embodiment, the beam returned to the galvano mirror 201 may be the same surface as the first incident surface. That is, if necessary, the structure of the second optical system 215 can be adjusted to make the incident surface of the first incident beam and the returned beam the same. In this case, the galvano mirror 201 has one The surface measuring function can be performed similarly to this embodiment only by having a reflective surface. Furthermore, the light source emitting the laser beam L and the reflected beam detector 209 may be disposed on the same side.

Next, with reference to FIG. 3, 2nd Embodiment of this invention is described.

The surface measuring apparatus shown in FIG. 3 has a structure in which first and second F-Theta lenses 210a and 210b are added to the surface measuring apparatus of FIG. 2. Therefore, the components denoted by the same numerals may be understood to be the same as in the case of FIG.

However, unlike the embodiment of FIG. 2, the beams passing through the first relay lens group 202 and the beams reflected from the wafer 206 are adjusted by adjusting the arrangement of the first and second optical systems 214 and 215. These focal points can be positioned in a constant area of the two reflecting mirrors 204 and 205, respectively.

The first f-theta lens 210a is disposed on a beam path between the first optical system 214 and the wafer 206, and the second first-f-theta lens 201b is formed of the wafer 206 and the first. It is disposed on the beam path between the two optical system (215).

As the first and second f-theta lenses 210a and 210b, lenses having the same structure may be employed, and the first and second f-theta lenses 210a and 210b may have a function of maintaining a constant beam scanning direction and incident angle and focusing the reflected scan beam. A function of positioning a predetermined area on the reflective mirror 204 of the second optical system may be performed.

Therefore, as the first and second f-theta lenses 210a and 210b are employed, the surface can be measured more precisely than in the embodiment of FIG. 2.

4 is a schematic diagram illustrating a surface measuring apparatus having two reflection beam detection units in the embodiment of FIG. 3.

In the surface measuring apparatus of FIG. 4, the beam splitter 211 is added to the surface measuring apparatus of FIG. 3, and two reflection beam detectors 212 and 213 are employed. Therefore, the components denoted by the same numerals may be understood to be the same as in the case of FIG.

The surface measuring apparatus according to the present embodiment is characterized by being split by the beam splitter 211 after the beam returned to the galvano mirror 201 is reflected. In this case, the light transmittance of the beam splitter 11 may be 50%, and the light transmittance may be appropriately adjusted according to the required beam intensity of each detector.

The divided beams are received by the position signal detector 212 and the reflected light amount detector 213, respectively. In this case, the positions of the two detectors 212 and 213 may be interchanged.

The change in the reflected beam angle may be measured using the position signal detector PSD, and a three-dimensional shape may be measured by a triangulation method based on the measured values.

Accordingly, the three-dimensional shape according to the change in morphology can be measured. In addition, the reflected light amount detector 213 may be understood to perform the same function as the reflected beam detector 209 described in the embodiment of FIG. 2.

In the present embodiment, one beam splitter 211 and two beam detectors 212 and 213 have been described. However, the plurality of beam splitters are divided into a larger number of beams by arranging a plurality of beam splitters according to the number required for detection. This can be detected.

5 is a schematic diagram which shows the surface measuring apparatus which concerns on other embodiment of this invention.

In the embodiment of FIG. 4, the surface measuring apparatus according to the present embodiment is a form in which a galvano mirror is replaced with a polygon mirror 501 consisting of a hexagonal body.

That is, in the present embodiment, the polygon mirror 501 is used as the beam scanning means, and the light source emitting the laser beam L, the first and second optical systems 514 and 515, and the first as in the embodiment of FIG. 4. And the second f-theta lenses 510a and 510b, the scattering beam detector 507, the beam splitter 511, the position signal detector 512 and the reflected light amount detector 513.

As in the previous embodiment, the first and second optical systems 514 and 515 have relay lens groups 502 and 505 and reflecting mirrors 503 and 504, respectively.

The arrangement structure and function of each element constituting the surface measuring apparatus are as described above, and only the polygon mirror 501 will be described below.

Similar to the galvano mirror, the polygon mirror 501 is connected to a motor (not shown) to rotate about a rotation axis, and rotates as described above to scan the laser beam L incident in a predetermined direction in one direction. . The beam scanned in one direction and passed through the first optical system 514 and the first f-theta lens 510a is reflected by the wafer 506. Thereafter, the beam reflected from the wafer 506 is returned to the polygon mirror 501 via the second f-theta lens 510b and the second optical system 515, and the polygon is the same as in the previous embodiment. The beam reflected back from the mirror 501 can be detected with a constant beam path regardless of the passage of time.

However, in addition to the case where the polygon mirror 501 is a hexahedron like the present embodiment, in another embodiment, a polygon mirror made of a tetrahedron or a polyhedron having a different number of surfaces may be employed.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

As described above, according to the present invention, it is possible to provide a surface measuring apparatus capable of measuring a large area at an extremely high speed while improving accuracy, and further capable of measuring a three-dimensional shape.

Claims (13)

A light source for emitting a laser beam; A rotation reflection mirror which scans the laser beam in one direction; A first optical system that receives the laser beam scanned by the rotation reflecting mirror and scans the laser beam to a measurement object; A second optical system configured to provide a beam reflected by the measurement object among the scanned laser beams to the rotation reflecting mirror, wherein the beam provided on the rotation reflecting mirror is reflected by the rotation reflecting mirror to have a constant beam path; And And at least one reflected beam detector for detecting a beam provided from the second optical system and reflected by the rotating reflection mirror. The method of claim 1, The reflected beam detector includes first and second reflected beam detectors, And a beam splitter which splits the beam reflected from the rotation reflecting mirror toward the reflection beam detector and provides the beam splitter to the first and second reflection beam detectors, respectively. The method of claim 2, And the first reflected beam detector is a position signal detector, and the second reflected beam detector is a reflected light amount detector. The method of claim 2, The beam splitter has a surface transmittance of 50%. The method of claim 1, And the first and second optical systems each comprise a relay lens group and a reflection mirror. The method of claim 1, The rotating reflection mirror has a first reflecting surface to which the laser beam is incident and a second reflecting surface to which the beam returned through the second optical system is incident. The method of claim 1, The rotating reflection mirror is a surface measuring device, characterized in that the galvano mirror. The method of claim 1, The rotating reflection mirror is a surface measuring device, characterized in that the polygon mirror. The method of claim 1, And a stage for moving the measurement object in a direction different from the direction in which the laser beam is scanned onto the measurement object. The method of claim 9, The moving direction of the stage is a surface measuring apparatus, characterized in that the perpendicular to the direction in which the laser beam is scanned to the measurement object. The method of claim 1, And a first f-theta lens disposed on the beam path between the first optical system and the measurement object and a second f-theta lens disposed on the beam path between the measurement object and the second optical system. Measuring device. The method of claim 1, It is disposed on the measurement object, the surface measuring apparatus further comprises a scattering beam detector for detecting the scattered beam from the measurement object. The method of claim 12, And a condenser lens for condensing the beam scattered from the measurement object and providing the scattered beam detector to the scattering beam detector.

Images