JPH0886743A - Polarimetric analyzing device - Google Patents

Abstract

PURPOSE: To provide a polarimetric analyzing device which executes the polarimetric analysis of a sample properly and quickly with its light extinguishing action achieved in a short time. CONSTITUTION: A beam of light from a light source 1 is set in a predetermined polarized state through a polarizer 2 and radiated to a sample 9 at a predetermined incident angle, and the beam reflected from the sample 9 is incident on a photosensor 5 via a compensator 3, a beam splitter 6 and an analyzer 4, and part of the outgoing beam from the compensator 3 is diverted to a linearly polarized light detection means 7 by the beam splitter 6 provided between the compensator 3 and the analyzer 4, and the ellipticity of the diverted beam is measured, so that a state in which the beam is almost linearly polarized is detected. In accordance with a detection signal of the linearly polarized light detection means 7 a control means 8 sets the azimuth of the polarizer 2 to azimuth at which the beam is almost linearly polarized, and with the beam extinguished by the compensator 3 and the analyzer 4, a variation in the polarized state at the sample 9 is detected for measurements of the physical characteristics of the sample 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection analyzer for measuring physical properties of a sample from changes in the polarization state of a reflected light beam or a transmitted light beam from the sample.

■

2. Description of the Related Art A light beam from a light source is set in a predetermined polarization state through a polarizer and a compensator, a sample is irradiated with this light beam, and the azimuth angle of the compensator is fixed at a predetermined azimuth angle. By setting the extinction condition for the reflected light flux from the sample by changing the azimuth angle of, the ellipsometer that measures the physical properties such as the complex refractive index of the sample, the birefringence index, and the film thickness of the thin film sample has been It is widely used in university laboratories and corporate research departments. This kind of polarization analyzer is described in detail, for example, in an optical measurement handbook (Asakura Shoten, October 1, 1982).

In this type of ellipsometer, in order to determine the extinction condition, the polarizer and the analyzer are alternately rotated, and this rotation is repeated until a complete extinction state is achieved. Normally, the polarizer is first rotated over the range of 0 ° to 90 ° in azimuth, the position where the amount of light entering the detector is detected is detected and the polarizer is stopped at that position, and then the analyzer is set in azimuth. Rotate in the range 90 ° to 90 ° to stop the analyzer at the position where the amount of light entering the detector is minimal. And usually,
This operation is repeated 5 to 10 times to position and set the polarizer and the analyzer at the final extinction point position.

[0004]

In the conventional polarization analyzer, as described above, the polarizer and the analyzer are rotated 5 to 10 times to set the final extinction point position. The analyzer is an optical element that uses a prism. Since it has a large inertia and is mounted on a precise tilt mechanism for adjusting the optical axis and rotates, it cannot be rotated at high speed and the extinction operation takes time. There is a problem.

Further, in this type of ellipsometer, in order to correct the systematic error, it is necessary to obtain the extinction points of two or four different areas (zones) in one point measurement, and the measurement is made in the device design. It takes several tens of seconds to measure one point, although the technology for shortening the time is adopted.

In this type of polarization analyzer, after the extinction condition is obtained, an analytical calculation is performed based on the azimuth angle of each optical element to obtain the characteristic value of the sample, and the measurement is completed. With the recent improvement in computer performance, it can be executed instantly, and most of the required measurement time is spent on setting the extinction condition. Further, in order to obtain the extinction point more accurately in order to perform the measurement with higher accuracy, it is necessary to increase the number of times the extinction operation is repeated, which further increases the measurement time.

In this case, it is possible that the operator inputs the expected optical characteristics of the sample into the polarization analyzer in advance and moves the optical element to the expected extinction position.
Generally, it takes a considerable time to investigate and input the optical characteristics of the sample, and in many cases, the polarization analysis time is not substantially shortened. For this reason, this type of ellipsometer is widely and usefully used in the field of research and development, but has not yet been used for product inspection at the production site.

The present invention has been made in view of the current state of the above-described polarization analyzer of this type, and its purpose is to perform an extinction operation in a short time and to accurately and quickly perform polarization analysis of a sample. It is to provide an ellipsometer for executing the method.

[0009]

In order to achieve the above object, the invention according to claim 1 sets a light beam from a light source into a predetermined polarization state through a polarizer, and sets the light beam at a predetermined incident angle. By irradiating the sample, the reflected light or the transmitted light from the sample is extinguished by the compensator and the analyzer, and the light receiving sensor detects the change amount of the polarization state caused by the transmission or the reflection in the sample, In an ellipsometer for measuring physical properties of a sample, a beam splitter provided between the compensator and the analyzer, which splits a part of a light beam emitted from the compensator, and a light beam split by the beam splitter. The linear polarization detecting means for measuring the ellipticity of the light and detecting the state in which the light flux is substantially linearly polarized, and the polarization based on the detection signal of the linear polarization detecting means. The azimuth angle of the child, is characterized in that a control means for the light beam is set in an azimuth angle substantially linearly polarized light.

Similarly, in order to achieve the above object, the invention according to claim 2 sets a light beam from a light source into a predetermined polarization state through a polarizer and a compensator,
By irradiating the sample at a predetermined incident angle, the reflected or transmitted light from the sample is extinguished by an analyzer, and the light receiving sensor detects the amount of change in the polarization state caused by the transmission or reflection in the sample. In the ellipsometer for measuring the physical characteristics of the sample, a beam splitter provided between the sample and the analyzer, which splits a part of the light beam emitted from the compensator, and a beam splitter The linear polarization detecting means for measuring the ellipticity of the luminous flux and detecting the state in which the luminous flux becomes substantially linearly polarized light, and the azimuth angle of the polarizer based on the detection signal of the linearly polarized light detecting means. And a control means for setting the azimuth angle to be linearly polarized light.

Similarly, in order to achieve the above object, the invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the linearly polarized light detecting means is rotatably held.
A polarizer into which the light beam split by the beam splitter is incident, a driver that rotationally drives the polarizer, a light amount measuring device that measures the light amount of the emitted light of the polarizer, and a variation amount of the output signal of the light amount measuring device. And a modulation degree measuring device for measuring.

Similarly, in order to achieve the above-mentioned object, the invention according to claim 4 is the invention according to claim 1 or 2, wherein the linearly polarized light detecting means is rotatably held,
A half-wave plate on which the light beam split by the beam splitter is incident, a driver for rotationally driving the half-wave plate, and a polarizer arranged at a stage subsequent to the half-wave plate, It is characterized by comprising a light quantity measuring device for measuring the light quantity of the emitted light of the polarizer and a modulation degree measuring device for measuring the variation amount of the output signal of the light quantity measuring device.

[0013] Similarly, in order to achieve the above object, the invention according to claim 5 is the invention according to claim 1 or 2, wherein the linearly polarized light detecting means is provided with a reflecting mirror portion on an end face and is rotatable. The polarizer, which is held by the beam splitter and is incident by the light beam split by the beam splitter, a driver that rotationally drives the polarizer, a light amount measuring device that measures the light amount of the reflected light at the end face, and an output of the light amount measuring device. It is characterized by comprising a modulation degree measuring device for measuring a variation amount of a signal.

Similarly, in order to achieve the above-mentioned object, the invention according to claim 6 is the invention according to claim 1 or 2, wherein the linearly polarized light detecting means is provided with a reflecting mirror portion on an end face and is rotatable. Held by, the quarter-wave plate on which the light beam split by the beam splitter enters, a driver that rotationally drives the quarter-wave plate, and a polarizer that transmits reflected light at the end face, It is characterized by comprising a light amount measuring device for measuring the light amount of the emitted light of the polarizer and a modulation degree measuring device for measuring the variation amount of the output signal of the light amount measuring device.

Similarly, in order to achieve the above object, the invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the beam splitter changes the optical path by a total reflection prism. According to the control signal of the control means, the insertion means for inserting the beam splitter into the optical path when the linearly polarized light detecting means is activated is further provided.

[0016] Similarly, in order to achieve the above object, the invention according to claim 8 is the invention according to any one of claims 1 to 6, wherein the beam splitter changes the optical path by a total reflection mirror. In the operation of the linearly polarized light detection means, based on a control signal of the control means, insertion means for inserting the beam splitter into the optical path, and a wavelength plate arranged in the optical path branched by the total reflection mirror. Is further included.

Similarly, to achieve the above object, a ninth aspect of the invention is the invention according to any one of the first to eighth aspects, wherein the linearly polarized light detecting means has an azimuth angle of an optical element that rotates. And angle setting means for setting the azimuth angle of the analyzer to the extinction condition position based on the detection angle of the angle detection means.

[0018]

According to the invention described in claim 1, the light beam from the light source is set to a predetermined polarization state through the polarizer, and the light beam is applied to the sample at a predetermined incident angle, and reflected light or transmitted light from the sample is The light is incident on the light receiving sensor via the compensator and the analyzer. A part of the luminous flux emitted from the compensator is branched by a beam splitter provided between the compensator and the analyzer, and the ellipticity of the branched luminous flux is measured. Is detected to be almost linearly polarized light. Then, the control means sets the azimuth angle of the polarizer to an azimuth angle at which the light flux becomes substantially linearly polarized light based on the detection signal of the linearly polarized light detecting means, and the extinction by the compensator and the analyzer causes the light to pass through the sample or The physical properties of the sample are measured by detecting the amount of change in the polarization state caused by reflection.

According to the second aspect of the present invention, the light beam from the light source is set to a predetermined polarization state through the polarizer and the compensator, and the light beam is applied to the sample at a predetermined incident angle, and reflected light or transmitted light from the sample is transmitted. Is incident on the light receiving sensor via the analyzer. Further, a part of the light flux from the sample is branched by the beam splitter provided between the sample and the analyzer to the linear polarization detection means, the ellipticity of the branched light flux is measured, and the light flux is almost linear. The polarized state is detected. Then, the control means sets the azimuth angle of the polarizer to an azimuth angle at which the light flux becomes substantially linearly polarized light based on the detection signal of the linearly polarized light detecting means, and the extinction by the compensator and the analyzer causes the light to pass through the sample or The physical properties of the sample are measured by detecting the amount of change in the polarization state caused by reflection.

In the invention according to claim 7 or claim 8,
In addition to the action of the invention according to claim 1 or claim 2,
When the linearly polarized light detecting means is activated, the beam splitter is inserted into the optical path by the inserting means based on the control signal from the control means.

In the ninth aspect of the invention, in addition to the effect of the first or second aspect of the invention, the azimuth angle of the rotating optical element is detected by the linear polarization detecting means, and the detected azimuth angle is detected. Based on the above, the azimuth angle of the analyzer is set to the extinction condition position.

[0022]

【Example】

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. FIG. 1 is an explanatory diagram showing the overall configuration of this embodiment, and FIG. 2 is an explanatory diagram showing the configuration of the linearly polarized light detecting means of this embodiment.

In this embodiment, as shown in FIG.
The linearly polarized light that is incident on the light flux from and is rotatable at least in the angle range of 0 ° to 90 ° or the angle range of 0 ° to −90 ° in the plane perpendicular to the optical axis and whose azimuth angle continuously changes. There is provided a polarizer 2 that emits light. A sample 9 on which the light flux of the light source 1 is irradiated as a linearly polarized light flux through the polarizer 2 is arranged on the polarizer 2. The reflected light flux from the sample 9 becomes elliptically polarized light having a predetermined ellipticity, but this elliptically polarized light is transmitted, and a predetermined phase difference is set between the amplitude components of the elliptically polarized light which are orthogonal to each other to change the polarization state. 3 is provided for the sample 9.

Further, a beam splitter 6 which receives a light beam emitted from the compensator 3 and divides the emitted light beam into a transmitted light beam and a reflected light beam is arranged in a subsequent stage of the compensator 3. The beam splitter 6 is of a type in which a reflection layer made of a metal and a dielectric is deposited and formed on the inclined surface of a right-angle prism, and the inclined surface is opposed to another right-angle prism so as to face each other. An analyzer 4 which is incident on the transmitted light flux from the beam splitter 6 and is rotatable in a plane perpendicular to the optical axis, and which sets the extinction state by the rotation is arranged at the subsequent stage of the beam splitter 6, and the analyzer 4 The light receiving sensor 5 is arranged in the subsequent stage.

On the other hand, a linearly polarized light detecting means 7 on which the reflected light beam from the beam splitter 6 is incident is provided, and the linearly polarized light detecting means 7 rotates the polarizer 2 by a detection signal from the linearly polarized light detecting means 7. The control means 8 for controlling is connected, and the polarizer 2 is connected to the control means 8.

The linearly polarized light detecting means 7 of the present embodiment has a structure as shown in FIG. 2, and as the polarizer 11, a Glan-Thompson prism which is usually used as a polarizing element of a polarization analyzer is used. The polarizer 11 is rotatably held by a hollow shaft about an optical axis, the hollow shaft is connected to a rotating shaft 16 of a driver 12, and the polarizer 12 is rotated by the driver 12.

A light quantity measuring device 10 on which a reflected light beam from the beam splitter 6 which passes through the polarizer 11 is incident is provided at the subsequent stage of the polarizer 11. And
The light quantity measuring device 10 is connected to a modulation degree measuring device 17 for measuring the variation amount of the output signal of the light amount measuring device 10, and the modulation degree measuring device 17 is connected to the control means 8.

The polarization analysis operation of this embodiment having such a configuration will be described. The operator places a sample for measuring the complex refractive index, birefringence, etc., or a thin film sample for measuring the film thickness, complex refractive index, etc. at a predetermined position as the sample 9 so that the light flux from the light source 1 is emitted. Becomes a predetermined incident angle, and the tilt angle of the sample 9 is adjusted so that the light beam enters the light receiving sensor 5.

In this state, the normal extinction operation can be executed. In this embodiment, however, the rotation command from the control means 8 is input to the polarizer 2 before the normal extinction operation, and based on the rotation command. The polarizer 2 has at least an azimuth angle of 0 ° to 90 °.
Rotate an angle range including a region of 0 ° or 0 ° to −90 °. In this case, the polarizer 2 may be stopped after rotating so as to pass through the angular range, or may be continuously rotated in a region including the angular range until a stop command is issued from the control means 8. Good. The rotation direction is also clockwise.
It may be in any counterclockwise direction, and there is no limitation on the rotation start position, and normally the rotation is started from the previous stop position.

The light flux from the light source 1 which passes through the rotating polarizer 2 in this way is irradiated onto the sample 9 as linearly polarized light whose azimuth angle continuously changes, and the reflected light from the sample 9 is a predetermined ellipse. The light is incident on the compensator 3 as elliptically polarized light having a refractive index. A quarter-wave plate is usually used as the compensator 3, and the incident light flux is changed by the compensator 3.
A phase difference determined by the compensator 3 is added between the amplitude components orthogonal to each other along the two optical axes of the compensator 3 to change the polarization state.

A part of the transmitted light from the compensator 3 is branched by the beam splitter 6, and the branched light beam is incident on the linearly polarized light detecting means 7 as elliptically polarized light. In this case, the amount of light emitted from the polarizer 11 of the linearly polarized light detecting means 7 becomes maximum when the transmission axis direction thereof coincides with the major axis of the incident elliptically polarized light, and becomes minimum when the transmission axis direction thereof coincides with the minor axis thereof. A signal output that changes with time is input to the modulation degree measuring device 17.

Then, as the polarizer 2 rotates, the ellipticity of the elliptically polarized light changes, and near the azimuth angle in the extinction state, it becomes elliptically polarized light close to linear polarization, so that the transmission axis azimuth of the polarizer 11 is elliptically polarized. When it coincides with the short axis, the amount of emitted light becomes small, and the output signal of the modulation degree measuring device 17, which measures the temporal variation of the signal output, becomes maximum.

In the present embodiment, the modulation degree measuring device 17 extracts a frequency component synchronized with the rotation period of the polarizer 11 from the output signal of the light quantity measuring device 10, and outputs the amplified signal of the extracted component as the rotation angle of the polarizer 2. The point where the differential value is differentiated with respect to 0 and the differential value becomes 0 is detected by the control means 8 as the azimuth angle of the polarizer 2 in which the light beam split by the beam splitter 6 becomes linearly polarized light. The azimuth angle of the polarizer 2 in such a state is nothing but the azimuth angle of the polarizer 2 in the extinction state, and this state is 0 ° to 90 ° in the azimuth angle of the polarizer 2 from the principle of polarization analysis.
One exists in the range of 0, 0 ° to -90 °.

When the linearly polarized light detecting means 7 detects the azimuth angle in the extinction state, a signal indicating that the incident light beam has become linearly polarized light is input to the control means 8, and the control means 8 uses the signal to polarize the polarizer. Stop the rotation of 2. In this way, the polarizer 2 stops at a position where the azimuth angle of the polarizer is substantially equal to the azimuth angle in the extinction state.

After that, in this embodiment, the normal extinction operation is started, but as described above, since the azimuth angle of the polarizer 2 is set to be substantially equal to the azimuth angle at the time of extinction, the light enters the analyzer 4. The light flux to be emitted is almost linearly polarized light, and a substantially complete extinction state can be achieved by a simple operation of rotating the analyzer 4 and making it orthogonal to the azimuth angle of the incident linearly polarized light. Even when extremely accurate measurement is required to obtain a more complete extinction point, the rotation angles of the polarizer 2 and the analyzer 4 are small, and the extinction operation need not be repeated.

As described above, according to this embodiment, even when the characteristics of the sample are unknown, the rotation angle of the polarizer 2 is 90 ° or less,
Since the rotation angle of the analyzer 2 is 180 ° or less, it is not necessary to rotate the polarizer 2 and the analyzer 4 alternately, and a complete extinction state can be set by a simple operation. Can be significantly reduced.

Further, in the linearly polarized light detecting means 7 of this embodiment, the polarizer 11 only rotates steadily, an absolute orientation setting mechanism is unnecessary, and the driver 12 is simple and does not have a precise control mechanism. A variety of motors can be used, and the light quantity measuring device 10
Also, it is sufficient if it has stability within a short time, a silicon photodiode can be used, and the manufacturing cost can be reduced.

According to the actual measurement by the inventors, according to the present embodiment, when a silicon oxide film having a thickness of 7 nm on silicon was used as a sample and its thickness was measured, the measurement time by the conventional apparatus was about 30 seconds. On the other hand, it was confirmed that the measurement can be completed in 2 seconds and the measurement time can be significantly shortened.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the configuration of the linearly polarized light detecting means of this embodiment.

In this embodiment, the linear polarization detecting means 7A is
With the configuration shown in FIG. 3, the polarizer 11 is fixed, and the half-wave plate 13 provided in front of the polarizer 11 is used.
Is rotated by the driver 12.

Generally, it is carried out before the extinction operation,
It is desirable that the operation of setting the azimuth angle of the polarizer 2 to be substantially equal to the azimuth angle at the time of extinction should be completed in as short a time as possible.
For this purpose, it is necessary to shorten the response time of the linearly polarized light detecting means 7, and it is necessary to increase the number of rotations of the polarizer 11 per unit time.

However, since the polarizer 11 is a prism using crystals, it has a relatively small mechanical strength and is heavy. Therefore, when it is rotated at a high speed, the adhesive surface of the crystals peels off and breaks due to centrifugal force. There is a risk. Further, it is mounted on a precise tilting mechanism for adjusting the optical axis, and there is a limit to the increase in speed in terms of air resistance and driving force of the driver. For example, when an optimal Glan-Thompson prism is used for the polarizer 11, the upper limit of the number of rotations is about 600 rotations per minute, and if the high speed rotation is continued for a long time, peeling of the adhesive layer due to centrifugal force will occur. May occur.

By the way, in order to detect the linearly polarized state in the modulation degree measuring device 17, the pulsation of the light quantity due to the rotation of the polarizer 11 requires about 20 to 30 cycles.
In the linearly polarized light detecting means 7 of No. 1, this cycle corresponds to 1 to 2 seconds, which is the minimum response time.

In order to further shorten the response time, in this embodiment, as described above, the polarizer 11 is fixed and the half-wave plate 13 provided in the preceding stage is rotated. The configuration of the other parts of this embodiment is the same as that of the first embodiment which has already been described with reference to FIGS. 1 and 2, and will not be described again.

As described above, when the half-wave plate 13 is rotated, the elliptically polarized light and the linearly polarized light which are incident due to the principle of optics are rotated at twice the rotational speed in their directions. Therefore, the pulsation of the amount of light after passing through the polarizer 11 has a period twice that of the rotation speed of the half-wave plate 13, and the response time can be shortened. In addition, the half-wave plate 13 is lightweight, and since the adhesive surface of the sheath is perpendicular to the rotation axis,
It is not affected by centrifugal force and can withstand a long time rotation at an extremely high rotation speed.

According to this embodiment, the number of rotations of about 5000 rpm can be realized and the cycle can be doubled, and the response time can be shortened to 1/1000 or less of that of the first embodiment. Therefore, it is possible to significantly reduce the measurement time and perform highly accurate polarization analysis of the sample. The other operations and effects of this embodiment are the same as those of the first embodiment already described, and therefore a duplicate description will not be given.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is an explanatory diagram showing the configuration of the linearly polarized light detecting means of this embodiment.

In this embodiment, the linearly polarized light detecting means 7B is
The structure shown in FIG. 4 is adopted, and the reflecting mirror 15 is fixed to the end face of the polarizer 11, the rotary shaft 16 of the driver 12 is fixed to this reflecting mirror 15, and the polarizer 11 is rotated by the driver 12. taking it. This Polarizer 1
A light quantity measuring device 10 and a modulation degree measuring device 17 are arranged on the incident surface side of 1. The configuration of the other parts of this embodiment is
Since it is the same as the first embodiment already described, a duplicate description will not be given.

In the present embodiment, a linear polarization detecting means 7B is provided by providing a folding optical system in which the light quantity measuring device 10 and the modulation degree measuring device 17 are arranged on the incident surface side of the polarizer 11.
The overall length of the linearly polarized light detecting means 7B can be shortened without changing the optical path length, and downsizing can be realized. Further, the rotary shaft 16 can be fixed to the reflecting mirror 15 on the end face of the polarizer 11, a hollow rotary shaft and a connecting mechanism are not required, the structure of the linear polarization detecting means 7B is simplified, and the manufacturing cost can be reduced. .
The operation and other effects of this embodiment are the same as those of the first embodiment already described, and therefore a duplicate description will not be given.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is an explanatory diagram showing the configuration of the linearly polarized light detecting means of this embodiment.

In this embodiment, the linear polarization detecting means 7C is
The structure shown in FIG. 5 is adopted, and the reflecting mirror 15 is fixed to the end surface of the quarter-wave plate 14, and the driving unit 1 is attached to the reflecting mirror 15.
The second rotation shaft 16 is fixed, and the quarter wave plate 14 is rotated by the driver 12. A polarizer 11, a light quantity measuring device 10, and a modulation degree measuring device 17 are arranged on the incident surface side of the quarter-wave plate 14. The configuration of the other parts of the present embodiment is the same as that of the second embodiment already described, and therefore a duplicated description will not be given.

In this embodiment, the folding optical system is provided in which the polarizer 11, the light quantity measuring device 10 and the modulation degree measuring device 17 are arranged on the incident surface side of the quarter-wave plate 14.
Miniaturization is realized by shortening the total length of the linear polarization detecting means 7C without changing the optical path length of the linear polarization detecting means 7C. Since the operation and other effects of this embodiment are the same as those of the second embodiment already described, duplicate description will not be given.

[Fifth Embodiment] A fifth embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in that the beam splitter 6 is of a type in which the optical path is changed by a total reflection prism, and when the linear polarization means is activated, the beam is reflected based on the control signal from the control means 8. The insertion means for inserting the splitter 6 into the optical path is further provided. The configuration of the other parts of this embodiment is the same as that of the first embodiment already described, and therefore a duplicate description will not be given.

In general, the characteristics of the finished product of the beam splitter 6 are not always perfect due to variations in manufacturing and the like, and a slight change in polarization state may occur. It is necessary to select a beam splitter having characteristics suitable for the above and incorporate it into the ellipsometer. The imperfections of the beam splitter installed in this way are so small that they do not pose any problems for normal ellipsometry. However, when performing an analysis that requires the highest accuracy that can be achieved in principle, the change in the polarization state of the transmitted light due to the residual incompleteness of the beam splitter cannot be ignored.

This embodiment solves this problem.
A total reflection prism that does not change the polarization state of the branched light is used for the beam splitter, and when the extinction operation is performed after the azimuth angle of the polarizer 2 is set to be very close to the value in the extinction state, the beam splitter causes the beam path to pass through the optical path. Therefore, it is possible to perform high-precision polarization analysis of the sample without degrading the measurement accuracy due to the incompleteness of the beam splitter. The other operations and effects of this embodiment are the same as those of the first embodiment already described, and therefore a duplicate description will not be given.

[Sixth Embodiment] A sixth embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in that the beam splitter 6 is of a type in which the optical path is changed by a total reflection mirror, and the control means 8 is activated when the linear polarization means is activated.
The insertion means for inserting the beam splitter 6 into the optical path based on the control signal and the wave plate arranged in the optical path branched by the total reflection mirror are further provided.
The configuration of the other parts of the present embodiment is the same as the first embodiment already described.
Since it is the same as the embodiment of FIG.

In order to reduce the measurement time of this type of ellipsometer, it is advantageous to use a total reflection mirror that is lighter than the total reflection prism as the beam splitter.
The total reflection mirror has a large change in the polarization state at the time of reflection, and the reflected light branched even if linearly polarized light becomes elliptically polarized light. This embodiment solves this problem and sets the phase difference of the wave plate arranged in the branch optical path equal to the amount of change in the polarization state caused by the reflection by the total reflection mirror, so that the total reflection is light as a beam splitter. High precision measurement is possible even with a mirror.

Therefore, according to this embodiment, the measurement time can be further shortened as compared with the fifth embodiment, and highly accurate polarization analysis of the sample can be performed. The other operations and effects of this embodiment are the same as those of the fifth embodiment already described, and therefore, a duplicate description will not be given.

[Seventh Embodiment] A seventh embodiment of the present invention will be described. This embodiment is different from the above-described first embodiment in that the azimuth angle of the analyzer is detected based on the angle detection means for detecting the azimuth angle of the rotating optical element and the detection angle of the angle detection means. Angle setting means for setting the extinction condition position is further provided. The configuration of the other parts of this embodiment is the same as that of the first embodiment already described, and therefore a duplicate description will not be given.

In the first embodiment, after the azimuth angle of the polarizer 2 is set to a position substantially equal to the azimuth angle in the extinction state by the linear polarization detecting means 7, the analyzer 4 is set to 180 ° or less. An extinguishing operation to rotate by an angle is required.

In this embodiment, the time for this extinction operation is greatly shortened. For example, when the rotating optical element is a polarizer, the azimuth angle of the polarizer in the linearly polarized state is detected by the angle detecting means, and the angle setting is performed. By the means, the azimuth angle of the analyzer 4 is set to the extinction condition angle. Therefore, according to the present embodiment, the rotation start time of the analyzer 4 is advanced, the measurement required time is further shortened, and the polarization analysis of the sample can be performed. Other operations and effects of this embodiment are
Since it is the same as the first embodiment already described, a duplicate description will not be given.

In each of the examples, the case where the measurement was performed based on the reflected light from the sample was described, but the present invention is not limited to these examples, and when the sample is transparent, It is also possible to make measurements based on the transmitted light of. Further, in each of the embodiments, the case where the compensator is arranged between the sample and the beam splitter has been described, but the present invention is not limited to these embodiments, and the compensator is arranged between the polarizer and the sample. It is also possible to set. Then, in the fifth to seventh embodiments, the case where the linearly polarized light detecting means shown in FIG. 2 is provided has been described, but the present invention is not limited to each embodiment.
In the fifth to seventh embodiments, it is possible to adopt a configuration having the linearly polarized light detecting means shown in FIGS. 3 to 5.

[0063]

According to the invention described in any one of claims 1 to 3, the light beam from the light source set to a predetermined polarization state through the polarizer irradiates the sample and the reflected light from the sample or The transmitted light is incident on the light receiving sensor via the analyzer, and a part of the light flux from the sample is branched to the linear polarization detection means by the beam splitter provided in the front stage of the analyzer, and the ellipticity of the branched light flux is increased. Measured, based on the measurement, the azimuth angle of the polarizer is set to an azimuth angle at which the branched light flux becomes almost linearly polarized light, and the amount of change in the polarization state caused by the sample is set by a simple extinction state setting by the analyzer. Is detected, it becomes possible to perform an accurate measurement of the physical properties of the sample with a simple operation while shortening the measurement time. According to the invention as set forth in claim 4, in addition to the effect obtained by the invention as set forth in claim 1, the light beam split by the beam splitter is incident on the polarizer through the half-wave plate which is rotationally driven. Therefore, the half-wave plate can be rotated at a high speed while the influence of centrifugal force is small, and accurate measurement of the physical properties of the sample can be performed while further shortening the measurement time. According to the invention of claim 5 or 6, in addition to the effect obtained by the invention of claim 1, since the light flux branched by the beam splitter is incident on the polarizer having the reflecting mirror portion on the end face. The folding optical system is configured, and it is possible to significantly reduce the size of the entire device. According to the invention described in claim 7, in addition to the effect obtained by the invention described in any one of claims 1 to 6, since the beam splitter is removed from the optical system during the extinction operation, the characteristics of the beam splitter are improved. Based on this, there is no decrease in measurement accuracy, and more accurate measurement of physical properties of the sample can be performed. According to the invention of claim 8, in addition to the effect obtained by the invention of claim 7,
The weight of the beam splitter is reduced, and accurate measurement of the physical properties of the sample can be performed while further shortening the measurement time. According to the invention of claim 9, in addition to the effect obtained by the invention of any one of claims 1 to 8,
The azimuth angle of the rotating optical element is detected, and the azimuth angle of the analyzer is set to the extinction condition based on the detected angle. Therefore, the measurement time is further shortened and the physical characteristics of the sample are accurately measured. It will be possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of linearly polarized light detection means of the same embodiment.

FIG. 3 is an explanatory diagram showing a configuration of linearly polarized light detecting means according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of linearly polarized light detecting means according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a linearly polarized light detecting means according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 sample 2 polarizer 3 compensator 4 analyzer 5 light receiving sensor 6 beam splitter 7, 7A, 7B, 7C linear polarization detecting means 8 control means 10 light quantity measuring device 11 polarizer 12 driver 13 half wave plate 14 quarter Wave plate 15 Reflector 17 Modulation degree measuring instrument

Claims (9)

[Claims] 1. A light beam from a light source is set in a predetermined polarization state through a polarizer, and the light beam is applied to a sample at a predetermined incident angle, and reflected light or transmitted light from the sample is supplied to a compensator and an analyzer. The light is extinguished by and the light receiving sensor
In a polarization analyzer that measures the physical properties of the sample by detecting the amount of change in the polarization state caused by transmission or reflection in the sample, provided between the compensator and the analyzer, emitted from the compensator. A beam splitter for splitting a part of the luminous flux, a linear polarization detecting means for measuring the ellipticity of the luminous flux split by the beam splitter, and detecting a state where the luminous flux becomes substantially linear polarized light; A polarization analysis device, comprising: a control means for setting an azimuth angle of the polarizer to an azimuth angle at which the light flux becomes substantially linearly polarized light based on a detection signal of the means. 2. A light beam from a light source is set to a predetermined polarization state through a polarizer and a compensator, the sample is irradiated with the light beam at a predetermined incident angle, and reflected light or transmitted light from the sample is set. In the polarization analyzer for measuring the physical properties of the sample by detecting the amount of change in the polarization state caused by transmission or reflection in the sample by the light receiving sensor, quenching by the analyzer, the sample and the analyzer And a beam splitter that splits a part of the light beam emitted from the compensator, and the ellipticity of the light beam split by the beam splitter is measured to detect a state in which the light beam becomes substantially linearly polarized light. Linearly polarized light detection means, and control means for setting the azimuth angle of the polarizer to an azimuth angle at which the light flux becomes substantially linearly polarized light based on a detection signal of the linearly polarized light detection means. An ellipsometer comprising: 3. The linearly polarized light detecting means is rotatably held, a polarizer into which the light beam split by the beam splitter is incident, a driver for rotationally driving the polarizer, and a quantity of light emitted from the polarizer. 3. The polarization analyzer according to claim 1, further comprising a light quantity measuring device for measuring the light intensity and a modulation degree measuring device for measuring a variation amount of an output signal of the light quantity measuring device. 4. A half-wave plate in which the linearly polarized light detecting means is rotatably held and receives a light beam split by the beam splitter, and a driver for rotationally driving the half-wave plate. A polarizer disposed after the half-wave plate, a light amount measuring device for measuring the light amount of the emitted light of the polarizer, and a modulation degree measuring device for measuring the fluctuation amount of the output signal of the light amount measuring device. The polarization analyzer according to claim 1 or 2, comprising: 5. A polarizer for rotatably holding the linearly polarized light detecting means provided with a reflecting mirror portion on an end face thereof, into which the light beam split by the beam splitter is incident, and a driver for rotationally driving the polarizer. 3. The light amount measuring device for measuring the light amount of the reflected light at the end face, and the modulation degree measuring device for measuring the variation amount of the output signal of the light amount measuring device. Polarization analyzer. 6. A quarter-wave plate on which the linearly polarized light detecting means is provided with a reflecting mirror portion on an end face, is rotatably held, and on which the light beam split by the beam splitter is incident, and the quarter wave plate. A driver that rotationally drives a one-wave plate, a polarizer that transmits reflected light at the end face, a light amount measuring device that measures the light amount of the emitted light of the polarizer, and measures the fluctuation amount of the output signal of the light amount measuring device. The polarization analyzer according to claim 1 or 2, further comprising: 7. The beam splitter is of a type in which an optical path is changed by a total reflection prism, and when the linearly polarized light detecting means is activated, based on a control signal from the control means,
The polarization analyzer according to any one of claims 1 to 6, further comprising insertion means for inserting the beam splitter into an optical path. 8. The beam splitter is of a type in which the optical path is changed by a total reflection mirror, and the beam splitter is inserted into the optical path based on a control signal of the control means when the linear polarization detection means is activated. The polarization analyzer according to any one of claims 1 to 6, further comprising: means and a wave plate arranged in the optical path branched by the total reflection mirror. 9. The linearly polarized light detecting means detects an azimuth angle of a rotating optical element, and the azimuth angle of the analyzer is set to an extinction condition position based on the detected angle of the angle detecting means. 9. An ellipsometer according to claim 1, further comprising: an angle setting unit.