JP3343795B2 - Ellipsometer - Google Patents

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 characteristics of a sample from a change in the polarization state of a reflected light beam or a transmitted light beam from the sample.

[0002]

2. Description of the Related Art A light beam from a light source is set to a predetermined polarization state through a polarizer and a compensator, and this light beam is irradiated onto a sample, and the compensator is fixed at a predetermined azimuth angle. By changing the azimuth angle of the sample, the extinction condition is set for the reflected light flux from the sample, and the polarization analyzer that measures physical properties such as the complex refractive index, birefringence, and the film thickness of the thin film sample has been conventionally used. It is widely used in university laboratories and corporate research departments. The contents of this type of polarization analyzer are described in, for example, 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 an azimuth angle of 0 ° to 90 °, a position where the amount of light entering the detector is minimum is detected and the polarizer is stopped at that position, and then the analyzer is moved to an azimuth angle of −. Rotate in the range of 90 ° to 90 ° and stop the analyzer at the position where the amount of light entering the detector is at a minimum. And usually,
This operation is repeated 5 to 10 times, and the polarizer and the analyzer are positioned and set at the final extinction point position.

[0004]

As described above, in the conventional ellipsometer, the polarizer and the analyzer are rotated five to ten times to set the final extinction point position. The analyzer is an optical element using a prism, has a large inertia, and is mounted on a precise tilting mechanism for optical axis adjustment, and rotates. Therefore, high-speed rotation cannot be performed, and the quenching operation takes time. There is a problem.

In this type of ellipsometer, in order to correct systematic errors, it is necessary to determine extinction points in two to four different regions (zones) in one point measurement. It takes several tens of seconds to measure a single point, despite the use of time-saving techniques.

In this type of ellipsometer, after determining the extinction condition, an analysis operation is performed based on the azimuth of each optical element to obtain the characteristic value of the sample, and the measurement is completed. However, due to recent improvements in computer performance, it can be executed instantaneously, and most of the required measurement time is spent on setting extinction conditions. Further, if the extinction point is to be determined more accurately in order to perform higher-accuracy measurement, it is necessary to increase the number of repetitions of the extinction operation, and the measurement time becomes longer.

In this case, it is possible for the operator to input the expected optical characteristics of the sample to the ellipsometer in advance and to move the optical element to the expected extinction position.
In general, it takes a considerable amount of time to investigate and input the optical characteristics of a sample, and often does not substantially reduce the ellipsometry time. For this reason, this type of ellipsometer has been widely and effectively used in the field of research and development, but has not yet been used for product inspection at a production site.

The present invention has been made in view of the above-mentioned current state of the ellipsometer, and its object is to perform the quenching operation in a short time and to accurately and quickly analyze the ellipsometry of the sample. The present invention is to provide an ellipsometer to be executed.

[0009]

According to a first aspect of the present invention, a light beam from a light source is set to a predetermined polarization state through a polarizer, and the light beam is set at a predetermined incident angle. By irradiating the sample, the reflected light or transmitted light from the sample is quenched by a compensator and an analyzer, and the light receiving sensor detects the amount of change in the polarization state caused by transmission or reflection by the sample, thereby In a polarization analyzer for measuring physical properties of a sample, a beam splitter provided between the compensator and the analyzer and splitting a part of a beam emitted from the compensator, and a beam split by the beam splitter Linear polarization detecting means for measuring a state in which the light flux is substantially linearly polarized light, and 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.

[0010] Similarly, in order to achieve the above object, the invention according to claim 2 sets a light beam from a light source to a predetermined polarization state through a polarizer and a compensator, and
By irradiating the sample at a predetermined incident angle, quenching the reflected or transmitted light from the sample with an analyzer, and detecting the amount of change in the polarization state caused by transmission or reflection by the sample with a light receiving sensor. A polarization analyzer that measures the physical characteristics of the sample, a beam splitter that is provided between the sample and the analyzer and branches a part of a light beam emitted from the compensator, and is split by the beam splitter. Measuring the ellipticity of the luminous flux and detecting a state in which the luminous flux is substantially linearly polarized light, based on a detection signal of the linearly polarized light detection means, the azimuth of the polarizer, the luminous flux is substantially Control means for setting the azimuth to be linearly polarized light.

According to a third aspect of the present invention, the linear polarization detecting means is rotatably held, 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 driving device for rotating and driving the polarizer, a light amount measuring device for measuring a light amount of light emitted from the polarizer, and a variation amount of an output signal of the light amount measuring device And a modulation degree measuring device for measuring

According to a fourth aspect of the present invention, the linear polarization detecting means is rotatably held, wherein the linear polarization detecting means is rotatably held.
A half-wave plate on which the light beam split by the beam splitter is incident, a driver for rotating and driving the half-wave plate, and a polarizer disposed 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 light emitted from the polarizer, and a modulation degree measuring instrument for measuring the variation of the output signal of the light quantity measuring instrument.

According to a fifth aspect of the present invention, in order to achieve the above object, the linearly polarized light detecting means is provided with a reflecting mirror on an end face thereof and is rotatable. , A polarizer on which the light beam split by the beam splitter is incident, a driver for rotating and driving the polarizer, a light amount measuring device for measuring the amount of reflected light at the end face, and an output of the light amount measuring device. And a modulation degree measuring device for measuring a fluctuation amount of the signal.

According to a sixth aspect of the present invention, in order to achieve the above object, the linear polarized light detecting means is provided with a reflecting mirror on an end face thereof and is rotatable. A quarter-wave plate on which the light beam split by the beam splitter is incident, a driver that rotationally drives the quarter-wave plate, and a polarizer through which light reflected at the end face is transmitted, It is characterized by comprising a light amount measuring device for measuring the light amount of the light emitted from the polarizer, and a modulation degree measuring device for measuring a variation amount of an output signal of the light amount measuring device.

According to a seventh aspect of the present invention, the beam splitter may change the optical path by a total reflection prism according to any one of the first to sixth aspects. And an insertion unit for inserting the beam splitter into an optical path based on a control signal of the control unit when the linear polarization detection unit is operated.

According to another aspect of the present invention, in order to achieve the above object, the beam splitter according to any one of the first to sixth aspects, wherein the beam splitter changes an optical path by a total reflection mirror. When the linearly polarized light detecting means is operated, based on a control signal of the control means, an inserting means for inserting the beam splitter into an optical path, and a wave plate disposed in an optical path branched by the total reflection mirror, Is further provided.

According to a ninth aspect of the present invention, in order to achieve the above-mentioned object, the linear polarization detecting means may include an azimuth angle of a rotating optical element. And angle setting means for setting the azimuth of the analyzer to an extinction condition position based on the detection angle of the angle detection means.

[0018]

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

According to the second aspect of the present invention, a light beam from a light source is set to a predetermined polarization state through a polarizer and a compensator, and the light beam is irradiated on a 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. In addition, a beam splitter provided between the sample and the analyzer splits a part of the light beam from the sample to the linearly polarized light detector, measures the ellipticity of the split light beam, and determines that the light beam is substantially linear. The state of polarization is detected. Then, the azimuth of the polarizer is set to an azimuth at which the light flux becomes substantially linearly polarized light based on the detection signal of the linear polarization detection means by the control means, and the light is transmitted through the sample by quenching by the compensator and the analyzer. The amount of change in the polarization state caused by reflection is detected and the physical properties of the sample are measured.

[0020] In the invention according to claim 7 or claim 8,
In addition to the effect of the invention described in claim 1 or 2,
When the linearly polarized light detecting means operates, the beam splitter is inserted into the optical path by the inserting means based on the control signal of the control means.

According to the ninth aspect of the present invention, in addition to the operation of the first or second aspect, the azimuth of the rotating optical element is detected by the linearly polarized light detecting means, and the detected azimuth is detected. , The azimuth of the analyzer is set to the extinction condition position.

[0022]

【Example】

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

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

Further, a beam splitter 6 which receives the light beam emitted from the compensator 3 and divides the emitted light beam into a transmitted light beam and a reflected light beam is disposed downstream of the compensator 3. The beam splitter 6 is of a type in which a reflective layer made of a metal and a dielectric is deposited and formed on a slope of a right-angle prism, and the other right-angle prism is bonded to the slope with the slope facing the other. The transmitted light beam from the beam splitter 6 is incident thereon, and the analyzer 4 that is rotatable in a plane perpendicular to the optical axis and sets the extinction state by the rotation is disposed at the subsequent stage of the beam splitter 6. The light receiving sensor 5 is provided at the subsequent stage.

On the other hand, there is provided a linearly polarized light detecting means 7 into which the reflected light beam from the beam splitter 6 is incident. The linearly polarized light detecting means 7 controls the rotation of the polarizer 2 based on the detection signal of 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 this embodiment has a configuration as shown in FIG. 2. 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 about an optical axis by a hollow shaft. The hollow shaft is connected to a rotation shaft 16 of a driver 12, and the polarizer 11 is rotated by the driver 12.

At the subsequent stage of the polarizer 11, there is provided a light quantity measuring device 10 into which a reflected light beam from the beam splitter 6 passing through the polarizer 11 is incident. And
The light quantity measuring device 10 is connected to a modulation degree measuring device 17 for measuring the variation of the output signal of the light quantity 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 arranges a sample whose complex refractive index or birefringence is to be measured or a thin film sample whose thickness or complex refractive index is to be measured as a sample 9 at a predetermined position. Is adjusted to a predetermined angle of incidence, and the tilt angle of the sample 9 is adjusted so that the light beam enters the light receiving sensor 5.

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

The light beam from the light source 1 passing through the rotating polarizer 2 is applied to the sample 9 as linearly polarized light whose azimuth changes continuously, and the reflected light from the sample 9 is reflected by a predetermined ellipse. The light enters the compensator 3 as elliptically polarized light at a rate. A quarter-wave plate is usually used as the compensator 3, and the incident light beam is
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 split by the beam splitter 6, and the split light flux enters 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 coincides with the long axis of the incident elliptically polarized light, and becomes minimum when it coincides with the short axis. A signal output that fluctuates 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 in the vicinity of the azimuth in the extinction state, the elliptically polarized light becomes almost linearly polarized. When coincident with the short axis, the amount of emitted light decreases, and the output signal of the modulation degree measuring device 17 that measures the temporal variation of the signal output becomes the maximum.

In this embodiment, the modulation degree measuring device 17 extracts a frequency component synchronized with the rotation cycle of the polarizer 11 from the output signal of the light amount measuring device 10 and converts the amplified signal of the extracted component to the rotation angle of the polarizer 2. The point at which the differentiated value becomes 0 is detected by the control means 8 as the azimuth of the polarizer 2 at which the light split by the beam splitter 6 becomes linearly polarized light. The azimuth of the polarizer 2 in such a state is not limited to the azimuth of the polarizer 2 in the extinction state.
°, 0 ° to -90 ° one by one.

When the azimuthal angle in the extinction state is detected by the linearly polarized light detecting means 7, 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 generate a polarizer. Stop the rotation of 2. Thus, the polarizer 2 stops at a position where the azimuth of the polarizer is substantially equal to the azimuth in the extinction state.

Thereafter, in this embodiment, normal extinction operation is started. However, as described above, since the azimuth of the polarizer 2 is set substantially equal to the azimuth at the time of extinction, the light enters the analyzer 4. The luminous flux is almost linearly polarized light, and an almost complete extinction state can be achieved by a simple operation of rotating the analyzer 4 to make it orthogonal to the azimuth of the incident linearly polarized light. Even when extremely accurate measurement is required and a more complete extinction point needs to be obtained, 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.
The rotation angle of the analyzer 2 is 180 ° or less, and it is not necessary to rotate the polarizer 2 and the analyzer 4 alternately, a complete extinction state can be set by a simple operation, and the time required for the polarization analysis is required. Can be greatly reduced.

In the linearly polarized light detecting means 7 of this embodiment, the polarizer 11 rotates only steadily, no absolute azimuth setting mechanism is required, and the driver 12 has no precise control mechanism. Light motor 10
It is sufficient if the device has stability in a short time, and a silicon photodiode can be used, and the manufacturing cost can be reduced.

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

[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 linearly polarized light detecting means 7A is
3, the polarizer 11 is fixed, and the half-wave plate 13 provided in front of the polarizer 11 is provided.
Is rotated by the driver 12.

Generally, it is performed before the extinction operation is performed.
It is desirable that the operation of setting the azimuth of the polarizer 2 to be substantially equal to the azimuth at the time of extinction is completed as quickly 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 a crystal, the mechanical strength is relatively small and heavy. Therefore, when the polarizer 11 is rotated at a high speed, the bonding surface of the crystal is peeled and broken due to centrifugal force. There is a risk. In addition, since it is mounted on a precision tilt mechanism for adjusting the optical axis, there is a limit to speeding up 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 revolutions is approximately 600 revolutions per minute. May occur.

By the way, in order to detect the state of linear polarization in the modulation degree measuring device 17, about 20 to 30 pulsations of the light quantity due to the rotation of the polarizer 11 are required.
In the linearly polarized light detecting means 7, the period corresponds to 1 to 2 seconds, which is the minimum response time.

In order to further reduce the response time, in this embodiment, as described above, the polarizer 11 is fixed, and the half-wave plate 13 provided at the preceding stage is rotated. The configuration of the other parts of the present embodiment is the same as that of the first embodiment already 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 incident on the basis of the principle of optics are rotated at twice the rotation speed of the azimuth. Therefore, the pulsation of the amount of light after passing through the polarizer 11 has a period twice as long as the rotation speed of the half-wave plate 13, and the response time can be shortened. Also, the half-wave plate 13 is lightweight, and the adhesive surface is perpendicular to the rotation axis,
It is not affected by centrifugal force and can withstand a long rotation at an extremely high rotation speed.

According to this embodiment, a rotation speed of about 5,000 rotations per minute can be realized, and the cycle may be doubled, and the response time is reduced to 1/1000 or less of the first embodiment. Therefore, it is possible to significantly shorten the measurement time and perform highly accurate polarization analysis of the sample. Other operations and effects of the present embodiment are the same as those of the first embodiment already described, and therefore, will not be described repeatedly.

[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
4, the reflecting mirror 15 is fixed to the end face of the polarizer 11, the rotating shaft 16 of the driver 12 is fixed to the reflecting mirror 15, and the polarizer 11 is rotated by the driver 12. taking it. This Polarizer 1
The light amount measuring device 10 and the modulation degree measuring device 17 are provided on the side of the light incident surface of the light emitting device 1. The configuration of other parts of the present embodiment is as follows.
Since it is the same as the first embodiment already described, a duplicate description will not be made.

In this embodiment, by using a folded optical system in which the light quantity measuring device 10 and the modulation degree measuring device 17 are disposed on the incident surface side of the polarizer 11, the linear polarization detecting means 7B
The overall length of the linearly polarized light detection means 7B is shortened without changing the optical path length of the optical disk, thereby realizing the miniaturization. Further, the rotating shaft 16 can be fixed to the reflecting mirror 15 on the end face of the polarizer 11, so that a hollow rotating shaft and a connecting mechanism are not required, the configuration of the linearly polarized light detecting means 7B is simplified, and the manufacturing cost can be reduced. .
The operation and other effects of the present embodiment are the same as those of the first embodiment already described, and therefore, will not be described repeatedly.

[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 linearly polarized light detecting means 7C is
5, the reflecting mirror 15 is fixed to the end face of the quarter-wave plate 14, and the driving device 1
The second rotation shaft 16 is fixed, and the quarter wave plate 14 is rotated by the driver 12. A polarizer 11, a light amount measuring device 10, and a modulation degree measuring device 17 are arranged on the incident surface side of the quarter wavelength plate 14. The configuration of the other parts of the present embodiment is the same as that of the second embodiment already described, and the description will not be repeated.

In this embodiment, a folding optical system 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 is adopted.
The overall length of the linearly polarized light detecting means 7C is reduced without changing the optical path length of the linearly polarized light detecting means 7C, thereby realizing miniaturization. The operation and other effects of this embodiment are the same as those of the second embodiment already described, and therefore, will not be described repeatedly.

[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 has a form in which the optical path is changed by a total reflection prism. The configuration is such that an insertion unit for inserting the splitter 6 into the optical path is further provided. The other parts of the configuration of the present embodiment are the same as those of the first embodiment already described, and therefore, will not be described repeatedly.

In general, the characteristics of the finished product are not always perfect due to variations in the manufacture of the beam splitter 6, and a slight change in the state of polarization 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 incorporated in this way are so small that normal ellipsometry does not cause any problems. However, when performing an analysis that requires the highest accuracy achievable in principle, a change in the polarization state of transmitted light due to residual imperfections of the beam splitter cannot be ignored.

This embodiment is to solve this problem.
A total reflection prism that does not change the polarization state of the split light is used for the beam splitter, and at the time of the extinction operation after the azimuth of the polarizer 2 is set very close to the value at the time of the extinction state, the insertion means causes the beam splitter to change the optical path. , It is possible to perform highly accurate polarization analysis of the sample without lowering the measurement accuracy due to imperfections of the beam splitter. Other operations and effects of the present embodiment are the same as those of the first embodiment already described, and therefore, will not be described repeatedly.

[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 has a form in which the optical path is changed by a total reflection mirror.
Based on the control signal described above, an insertion means for inserting the beam splitter 6 into the optical path and a wave plate arranged in the optical path branched by the total reflection mirror are further provided.
The configuration of the other parts of this embodiment is the same as that of the first
Since the embodiment is the same as that of the first embodiment, the description will not be repeated.

In order to shorten the measurement time of this type of ellipsometer, it is advantageous to use a total reflection mirror which is lighter than a total reflection prism as a beam splitter.
The total reflection mirror has a large change in the polarization state upon reflection, and even if linearly polarized light is incident, the reflected light that is branched becomes elliptically polarized light. The present 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, thereby achieving a light total reflection as a beam splitter. Even if a mirror is used, highly accurate measurement is possible.

Therefore, according to the present 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. Other operations and effects of the present embodiment are the same as those of the fifth embodiment already described, and therefore, will not be described repeatedly.

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

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

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

In each of the embodiments, the case where the measurement is performed based on the reflected light from the sample has been described. However, the present invention is not limited to these embodiments. It is also possible to perform a measurement based on the transmitted light. Further, in each of the embodiments, the case where the compensator is arranged between the sample and the beam splitter has been described. However, 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 up. Then, in the fifth to seventh embodiments, the case where the linear polarization detecting unit shown in FIG. 2 is provided has been described. However, the present invention is not limited to each embodiment.
In the fifth to seventh embodiments, a configuration having the linearly polarized light detecting means shown in FIGS. 3 to 5 is also possible.

[0063]

According to the invention as set forth in any one of claims 1 to 3, a light beam from a light source set to a predetermined polarization state through a polarizer is applied to a sample, and reflected light from the sample or reflected light from the sample. The transmitted light is incident on the light receiving sensor via the analyzer, and a part of the light beam from the sample is branched by the beam splitter provided in front of the analyzer to the linearly polarized light detecting means, and the ellipticity of the branched light beam is reduced. Measured, based on the measurement, the azimuth angle of the polarizer is set to the azimuth angle at which the branched light beam becomes substantially linearly polarized light, and the amount of change in the polarization state caused by the sample is set by the simple extinction state setting by the analyzer. Is detected, so that accurate measurement of the physical properties of the sample can be performed with a simple operation and with a reduced measurement time. According to the invention described in claim 4, in addition to the effect obtained by the invention described in claim 1, the light beam split by the beam splitter is incident on the polarizer via the half-wave plate that is driven to rotate. Therefore, the half-wave plate can be rotated at a high speed with little influence of the centrifugal force, and the accurate measurement of the physical characteristics of the sample can be performed with a further reduced measurement time. According to the fifth or sixth aspect of the present invention, in addition to the effect obtained by the first aspect of the present invention, the light beam split by the beam splitter is incident on a polarizer having a reflecting mirror provided on an end face. A folding optical system is configured, and the entire apparatus can be significantly reduced in size. According to the seventh aspect of the present invention, in addition to the effects obtained by the first aspect of the present invention, the beam splitter is removed from the optical system during the extinction operation. As a result, a decrease in the measurement accuracy is eliminated, and more accurate measurement of the physical properties of the sample can be performed. According to the invention described in claim 8, in addition to the effect obtained by the invention described in claim 7,
The weight of the beam splitter is reduced, and accurate measurement of the physical properties of the sample can be performed with a further reduced measurement time. According to the ninth aspect of the present invention, in addition to the effects obtained by the invention according to any one of the first to eighth aspects,
The azimuth of the rotating optical element is detected, and based on the detected angle, the azimuth of the analyzer is set to the extinction condition, so that the measurement time is further shortened and the physical characteristics of the sample are accurately measured. It becomes possible.

[Brief description of the 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 a linearly polarized light detecting means of the embodiment.

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

FIG. 4 is an explanatory diagram showing a configuration of a 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]

 DESCRIPTION OF SYMBOLS 1 Sample 2 Polarizer 3 Compensator 4 Analyzer 5 Light-receiving sensor 6 Beam splitter 7, 7A, 7B, 7C Linear polarization detection means 8 Control means 10 Light quantity measuring device 11 Polarizer 12 Driver 13 1/2 wavelength plate 14 Quarter Wave plate 15 Reflector 17 Modulation degree measuring instrument

Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01J 4/00-4/04 Practical file (PATOLIS) Patent File (PATOLIS)

Claims (9)

(57) [Claims] 1. A light beam from a light source is set to a predetermined polarization state through a polarizer, and the light beam is irradiated on a sample at a predetermined incident angle, and reflected light or transmitted light from the sample is transmitted to a compensator and an analyzer. The light is extinguished by the
In a polarization analyzer for measuring a physical property of the sample by detecting an amount of change in a polarization state caused by transmission or reflection on the sample, the polarization analyzer is provided between the compensator and the analyzer and emitted from the compensator. A beam splitter for splitting a part of the light beam to be split, linear ellipse detection means for measuring an ellipticity of the light beam split by the beam splitter, and detecting a state in which the light beam becomes substantially linearly polarized light; And a control means for setting an azimuth of the polarizer to an azimuth 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, and the light beam is irradiated on a sample at a predetermined angle of incidence, and reflected light or transmitted light from the sample is reflected by the sample. A quenching by the analyzer, a light receiving sensor, by detecting the amount of change in the polarization state caused by transmission or reflection in the sample, in a polarization analyzer that measures the physical properties of the sample, the sample and the analyzer And a beam splitter that splits a part of the light beam emitted from the compensator, and measures an ellipticity of the light beam split by the beam splitter to detect a state in which the light beam becomes substantially linearly polarized light. Linear polarization detection means, and 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 linear polarization detection means. A polarization analyzer comprising: 3. A polarizer, wherein the linearly polarized light detecting means is rotatably held and into which a light beam split by the beam splitter is incident, a driver for rotating and driving the polarizer, and an amount of light emitted from the polarizer. 3. The polarization analyzer according to claim 1, comprising: a light quantity measuring device for measuring the amount of light; and a modulation degree measuring device for measuring a fluctuation amount of an output signal of the light quantity measuring device. 4. A half-wave plate, wherein said linearly polarized light detecting means is rotatably held, and receives a light beam split by said beam splitter, and a driver for rotating and driving said half-wave plate. A polarizer disposed at a stage subsequent to the half-wave plate, a light amount measuring device for measuring the amount of light emitted from the polarizer, and a modulation degree measuring device for measuring a fluctuation amount of an output signal of the light amount measuring device. 3. The polarization analyzer according to claim 1, wherein the polarization analyzer comprises: 5. A polarizer, wherein the linear polarization detecting means is provided with a reflecting mirror on an end face, is rotatably held, and receives a light beam split by the beam splitter, and a driving device for rotating the polarizer. 3. The apparatus according to claim 1, further comprising a light quantity measuring device for measuring a light quantity of the reflected light at the end face, and a modulation degree measuring instrument for measuring a variation amount of an output signal of the light quantity measuring instrument. Ellipsometer. 6. A quarter-wave plate, wherein said linearly polarized light detecting means is provided with a reflecting mirror portion on an end face, is rotatably held, and receives a light beam split by said beam splitter, and said quarter-wave plate. A driving device that rotationally drives the one-wavelength plate, a polarizer through which the light reflected by the end face is transmitted, a light amount measuring device that measures the amount of light emitted from the polarizer, and a variation amount of an output signal of the light amount measuring device. 3. The polarization analyzer according to claim 1, further comprising a modulation degree measuring device. 7. The beam splitter is of a type in which an optical path is changed by a total reflection prism, and based on a control signal of the control means when the linear polarization detection means is operated.
The polarization analyzer according to claim 1, further comprising an insertion unit configured to insert 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 operated. The polarization analyzer according to any one of claims 1 to 6, further comprising: means and a wave plate disposed in an optical path branched by the total reflection mirror. 9. An angle detecting means for detecting an azimuthal angle of a rotating optical element, wherein said linearly polarized light detecting means sets an azimuth angle of said analyzer to an extinction condition position based on a detection angle of said angle detecting means. The polarization analyzer according to any one of claims 1 to 8, further comprising an angle setting unit that performs the angle setting.