JP3519605B2 - Ellipsometry equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ellipsometry device for measuring the film thickness of a thin film and the optical constants of the thin film, that is, the refractive index and absorptance with respect to wavelength, based on the change in the polarization state due to the reflection of light.

[0002]

2. Description of the Related Art In the principle of this type of ellipsometry device, when a known arbitrary polarized light is applied to a sample, the polarization state of the reflected light reflected is the optical constant of the sample, the film thickness of the thin film on the sample surface, and the optical state. Uniquely determined by a constant. Therefore, by measuring the polarization state of the reflected light, the film thickness and the optical constant of the thin film on the sample surface are measured conversely. Many measuring devices have been developed for that purpose.

FIG. 6 is a diagram showing the principle of a conventional ellipsometry device. FIG. 6 shows a widely used photoelectric photometric ellipsometry device. This device comprises a light source 100, a polarizer 101, an analyzer 102 and a detector 103.

One of the conventional typical measuring methods using the above ellipsometry device is a rotary analyzer type, and in this method, the incident light is a linearly polarized light having an azimuth angle suitable for the sample to be measured. The azimuth angle P of the polarizer 101 is adjusted so that At that time, the analyzer 102 is rotated, the light intensity of the detector 103 with respect to the azimuth angle A of the rotated analyzer 102 is measured at a large number of points, and the polarization state of the reflected light is measured from the obtained waveform.

Then, the ratio of the complex reflectance of P-polarized light and the complex reflectance of S-polarized light, that is, the complex reflectance ratio ρ is calculated from the data obtained by the reflection polarization measurement in this way, and is calculated. Obtain the thickness and refractive index of the thin film.

Complex reflectance ratio ρ = P-polarized complex reflectance / S
Complex reflectance of polarized light (1) Alternatively, the azimuth A of the analyzer 102 is fixed, and the detector 103 is rotated while rotating the polarizer 101.
Measure the light intensity at.

[0007]

However, in the conventional ellipsometry device of FIG. 6, the rotating parts of the polarizer 101 and the analyzer 102 are indispensable. For this reason, there are problems that the measurement time is limited, a problem due to a rotating part is caused, and that the measuring part cannot be configured in a small size because it is necessary to configure the rotating part.

Therefore, the inventors of the present invention have proposed an ellipsometry device which can be constructed without a rotating portion.

FIG. 5 shows an improved ellipsometry device. In this ellipsometry device, the light from the light source 10 is guided to the incident optical system by the optical fiber 11. The light emitted from the optical fiber 11 is collimated by the collimator lens 20, and the polarizer 21 changes the polarization of the collimated light into linearly polarized light. This linearly polarized parallel light is condensed by the emission lens 22 on the measurement substrate 12 as a measurement target.

The reflected light reflected by the surface of the measurement substrate 12 is collimated by the incident lens 30, and a specific polarization component of the reflected light is reflected by the transparent plate 31 toward the matching lens 33. Further, the light transmitted through the transparent plate 31 is separated into two polarization components by the polarization beam splitter 32. The lights separated by the transparent plate 31 and the polarization beam splitter 32 are matched lenses 33, 34, 35, respectively.
Incident on the optical fibers 40, 41, 42, and the spectroscopes 50, 51,
Guided to 52.

The lights output from the spectroscopes 50, 51 and 52 are detected by photodetectors 60, 61 and 62, respectively. Photo detector 60,
The detection results of 61 and 62 are spectroscopes 50-52 and photodetectors 60-62.
Is input to the controller 70 that controls the. Controller 71
Processes the measurement data input from the controller 70 and controls the measurement by the controller 70.

FIG. 5 does not show a supporting device or the like for the measurement substrate 12 and optical components, but as the supporting device, a device such as a general optical stand by a general method is used.

However, according to the method of FIG.
Although the ellipsometry device can be configured without having a rotating part like the above, since the measurement substrate 12 also forms part of the measurement optical system, the substrate tilt (tilt) that occurs when the measurement substrate 12 is replaced Therefore, there is a possibility that the measurement accuracy may deteriorate or the measurement itself may become impossible.

The present invention has been made in consideration of such circumstances, and detects and corrects the optical axis shift due to sample tilt.
An object of the present invention is to provide an ellipsometry device that can automatically perform the above.

Further, according to the present invention, the reflection type beam splitter, which is one component of the light receiving optical system, is a concave mirror type beam splitter, so that the number of condenser lenses can be reduced and the configuration of the optical system can be simplified. An object is to provide a metrology device.

[0016]

SUMMARY OF THE INVENTION The present invention is an ellipsometry apparatus for measuring the state of a sample by measuring the polarization state of the reflected light from the sample, which has a polarizing means for guiding the light from a light source. The output optical system, the light receiving optical system that receives the reflected light that is polarized by the output optical system and reflected by the sample, the light receiving optical system support to which the light receiving optical system is fixed, and the light receiving optical system A compound that detects the intensity of light
Number detection means, measurement means for measuring the polarization state of the reflected light from the detection results of these detection means, and measurement data electrically connected to the measurement means and indicating the polarization state from the measurement means Then, a controller that measures the film thickness and optical constants of the thin film on the sample surface, and a manipulator that adjusts the mounting position of the entire light-receiving optical system support in a direction that corrects the deviation amount of the optical axis calculated by this controller. comprising the door, the light-receiving optical system further two light beams separated by the polarizing beam splitter and polarization beam splitter for separating the light reflected from the sample into two polarization components
It has two reflection type beam splitters, each of which is divided into two, and the light intensity of each light flux divided into two sets, a total of four sets, is detected by the detection means, and a difference in light intensity is obtained for each set. The ellipsometry device is characterized in that the direction of the deviation of the optical axis is determined by its sign and the magnitude of the deviation of the optical axis is determined by its absolute value.

In the present invention, the adjusting means may be a manipulator, and the installation location thereof may be a light receiving optical system (Example 1), an emitting optical system (Example 2), or a constituent element of the emitting optical system. An exit lens (Example 3) can be mentioned.

In the present invention, the light receiving optical system separates the light reflected from the sample into two polarization components, and a reflection type beam splitter which further separates the light beam separated by the polarization beam splitter. It is preferable that the reflective beam splitter is a concave mirror type beam splitter. As a result, the number of condenser lenses used in the light receiving optical system can be reduced and the configuration of the optical system can be simplified.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ellipsometry device according to an embodiment of the present invention will be described below with reference to the drawings.

Example 1 Reference is made to FIG. However, FIG.
The same members as those in 1 will be described using the same reference numerals. In this ellipsometry device, the light from the light source 10 is guided to the incident optical system by the optical fiber 11. The light emitted from the optical fiber 11 is collimated by the collimator lens 20, and the polarizer 21 changes the polarization of the collimated light into linearly polarized light. The linearly polarized parallel light is condensed by the emission lens 22 on the measurement substrate 12 as a measurement target.

The reflected light reflected by the surface of the measurement substrate 12 is collimated by the incident lens 30, and a specific polarized component of the reflected light is reflected by the transparent plate 31 toward the matching lens 33. Further, the light transmitted through the transparent plate 31 is separated into two polarization components by the polarization beam splitter 32. The light beams separated by the polarization beam splitter 32 are spatially separated into two by the reflective beam splitters 38 and 39.

The lights separated by the transparent plate 31, the polarization beam splitter 32, and the beam splitters 38, 39 are matched lenses 33, 34, 35, 36, 37 with optical fibers 40, 41, 42, respectively.
It is incident on 43, 44, and is separated by spectroscopes 50, 51, 52, 53, 54, 55. The transparent plate 31, the polarization beam splitter 3
2, beam splitters 38, 39, matching lenses 33, 34, 3
The entrance ends of the optical fibers 40, 41, 42, 43, and 44 of 5, 36, and 37 are fixed to the light receiving optical system support 14 by an appropriate method. The light receiving optical system support 14 is movably supported by the manipulator 13, and the manipulator
13 is electrically connected to and controlled by a controller 71 described later.

The lights output from the spectroscopes 50, 51, 52, 53 and 54 are detected by photodetectors 60, 61, 62, 63 and 64, respectively. The detection results of the photodetectors 60 to 64 are input to the spectroscopes 50 to 54 and the controller 70 that controls the photodetectors 60 to 64.
The controller 71 processes the measurement data input from the controller 70 and controls the measurement by the controller 70.

Although FIG. 1 does not show a supporting device or the like for the measurement substrate 12 and the optical components, a general optical stand or other general-purpose method is used as the supporting device.

As the light source 10, various ones such as high-intensity monochromatic light such as laser light, white light, and monochromatic light obtained by dispersing white light are used. The optical fibers 11 and 40 to 44 do not need to have a special function such as polarization preservation, and may be those suitable for the target measurement wavelength. The fiber diameter is preferably as small as possible, but is not particularly limited. When a single monochromatic light is used as the light source 10, the spectroscopes 50 to 54 are not particularly necessary.

The collimator lens 20 produces parallel light rays suitable for optical components used thereafter, and makes diffused light emitted from an optical fiber or the like into parallel light. Depending on the configuration of the measuring instrument, it is possible to directly emit diffused light or parallel light from the light source 10 without using the optical fiber 11 or the collimator lens 20.

The polarizer 21 may be a generally used one such as a polarizing prism. The exit lens 22 focuses parallel light on the surface of the measurement substrate 12, and determines the focal length according to the device configuration. If the luminous flux incident on the exit lens 22 is thin, the exit lens 22 may not be used. The incident lens 30 is a lens for making parallel when diffused light is reflected from the surface of the measurement substrate 12, and its focal length is determined according to the device configuration. If parallel light is used without using the exit lens 22, the entrance lens 30 need not be used.

The beam splitters 38 and 39 are for spatially separating the light beams separated by the polarization beam splitter 32, and are formed by laminating two optical plane mirrors. When the tangent line of the bonded portion of the two mirrors is the ridge line, the ridge line is arranged so as to be perpendicular to the optical axis of the reflected light as shown in FIG. 7 (A), and as shown in FIG. 7 (B). The angle formed by the ridgeline of the beam splitter 38 and the ridgeline of the beam splitter 39 need not be spatially parallel, and is preferably close to vertical.

The manipulator 13 adjusts the mounting position of the entire light-receiving optical system support base 14 in a direction to correct the amount of deviation of the optical axis calculated by the controller 71.
Although a piezo element or the like can be used, there is no particular designation as long as the mounting position of the light receiving optical system support 14 can be adjusted by remote control.

The transparent plate 31 makes parallel light incident at a Brewster angle determined by its refractive index. The reflected light from the transparent plate 31 is incident on the optical fiber 40 by the matching lens 33. The transmitted light of the transparent plate 31 is incident on the polarization beam splitter 32 having a different azimuth angle with respect to the azimuth angle of the transparent plate 31 at a prescribed angle. The two lights emitted from the polarization beam splitter 32 are further split into two by beam splitters 38 and 39, one of which is incident on optical fibers 41 and 42 by matching lenses 34 and 35, and the other of which is matched lens 3
It is incident on the optical fibers 43 and 44 by 6 and 37.

The light incident on the optical fibers 40, 41, 42, 43, 44 is incident on the spectroscopes 50, 51, 52, 53, 54, respectively, and is dispersed, and further the photodetectors 60, 61, 62, 63, 64. Each polarization intensity is measured by. The measurement results of the photodetectors 60, 61, 62, 63, 64 are input to the controller 70, and the controller 70 measures the polarization state of the reflected light from the measurement substrate 12 based on the measurement results. The controller 71 inputs the measurement data indicating the polarization state from the controller 70, and the measurement board 12
The film thickness and optical constants of the thin film on the surface are measured. The resolution of the spectroscopes 50 to 54 is set as needed. light source
When the light used for 10 is monochromatic light, the spectroscopes 50 to 54 are not necessary. As the photodetectors 60 to 64, suitable ones such as a photocurrent type and a photon counting type are used according to the light intensity.

As described above, in the first embodiment, the reflected light from the measurement substrate 12 passes through the polarization beam splitter 32, and then the beam splitter 38 separates the two light beams a and b.
And the light intensity Ia,
Measure Ib. For the measured light intensity, the intensity difference Id = Ia-Ib is calculated by the control computer. Intensity difference Id
Indicates the direction of deviation of the sign and the magnitude of deviation of the absolute value. That is, if the sign is positive, the optical axis is shifted to the a side, and if the sign is negative, the optical axis is shifted to the b side. Also, the same light intensity difference is calculated for the light flux separated by the beam splitter 39. Since these two beam splitters 38 and 39 are installed at azimuth angles that are not parallel to the optical axis, they can be calculated as two-dimensional information (for example, vertical deviation and lateral deviation) about the deviation of the optical axis. The correction amount is calculated based on this information, and the manipulator 13 is used to adjust the optical axis by adjusting the installation position and angle of the light receiving optical system support 14.

In the first embodiment, at the time of measurement, the same measurement as that of the conventional ellipsometry device can be performed by the following operation. That is, by calculating the sum Id = Ia + Ib of the light intensities separated by the beam splitter 38, the same light intensity as that detected by the photodetector 51 in FIG. 5 can be obtained, and the same operation is performed. 5 is also performed on the light intensity of the light separated by the beam splitter 39 in FIG. 1, it is possible to obtain the same light intensity as the light intensity detected by the photodetector 52 in FIG.

Example 2 Reference is made to FIG. Note that FIG.
The same members as and are denoted by the same reference numerals, and description thereof will be omitted. Example 2
Is characterized in that the manipulator 13 in the first embodiment is attached to the output optical system support 15.

In the second embodiment, the process until the deviation amount of the optical axis is derived is the same as that of the first embodiment, and therefore the description thereof is omitted.
According to the second embodiment, the manipulator 13 is attached to the emitting optical system support base 15, so that the calculated optical axis shift amount is converted as a correction amount of the emitting optical system support base 15, and the manipulator 13 is moved. The optical axis can be automatically adjusted by adjusting the installation position and angle of the output optical system. That is, in the second embodiment, the manipulator 13 is attached to the emitting optical system support base 15, so that the first embodiment
Compared with, the optical axis can be adjusted with a smaller movement amount.

(Embodiment 3) Referring to FIG. Note that FIG.
The same members as and are denoted by the same reference numerals, and description thereof will be omitted. Example 3
Is the manipulator 13 in the first embodiment, the injection lens 22
It is characterized by being attached to.

In the third embodiment, the process until the deviation amount of the optical axis is derived is the same as that of the first embodiment, and therefore the description thereof is omitted.
According to the third embodiment, the manipulator 13 is connected to the exit lens 22.
The optical axis is automatically adjusted by adjusting the installation position and angle of the exit lens 22 using the manipulator 13 by converting the calculated optical axis deviation amount as the correction amount of the exit lens 22 by using the configuration attached to the. Can be adjusted to.
That is, in the third embodiment, the manipulator 13 is connected to the exit lens 22.
The optical axis can be adjusted only by adjusting the position of the lens, as compared with the first and second embodiments.

(Embodiment 4) Referring to FIG. Note that FIG.
The same members as and are denoted by the same reference numerals, and description thereof will be omitted. Example 4
Is characterized in that the beam splitters 38 and 39 in the first embodiment are changed to those in which concave mirrors are laminated.

In the fourth embodiment, the beam splitter 38
The light beams separated by are incident on the optical fibers 41 and 42 installed at the respective focal positions and guided to the spectroscopes 51 and 52. or,
The light beams separated by the beam splitter 39 also enter the optical fibers 43 and 44 installed at the respective focal positions and enter the spectroscope 53,
Guided to 54. The other operations are the same as in the first embodiment. Furthermore, the process until the light reflected from the surface of the measurement sample 12 is split into two light beams by the polarization beam splitter 32 is the same as in the first embodiment.

According to the fourth embodiment, the beam splitter 38
The light reflected by is focused at the focal position of the concave mirror, and by irradiating this focal position with the optical fiber incident light, the condensing lens of the first embodiment (reference numerals 33 to 37 in FIG. 1) is unnecessary. You can That is, in the fourth embodiment, by using a concave mirror type beam splitter as the beam splitter, the number of condenser lenses can be reduced as compared with the first embodiment, and the configuration of the optical system can be simplified.

The present invention is not limited to the above-described embodiments, but can be modified and implemented as appropriate without departing from the scope of the invention.

[0042]

According to the present invention as described in detail above, trial
Automatically detects optical axis shift due to charge and corrects it
An ellipsometry device that can be used can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an ellipsometry device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an ellipsometry device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of an ellipsometry device according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of an ellipsometry device according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of an improved ellipsometry device.

FIG. 6 is a diagram showing the principle of a conventional ellipsometry device.

FIG. 7 is an explanatory diagram regarding a bonded state of two mirrors that form a beam splitter.

[Explanation of symbols]

10 ... light source, 11, 40 ~ 44 ... Optical fiber, 12 ... Measuring board, 13 ... manipulator, 14 ... Light receiving optical system support, 15 ... Outgoing optical system support, 20 ... Collimator lens, 21 ... polarizer, 22 ... Emitting lens, 30 ... Incident lens, 31 ... transparent plate, 32 ... Polarizing beam splitter, 33-37 ... Matching lens, 38, 39 ... Beam splitter, 50-54 ... Spectrometer, 60-64 ... Photodetector, 70 ... controller, 71 ... Controller.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-218916 (JP, A) JP 9-166553 (JP, A) JP 9-166552 (JP, A) JP 9- 166549 (JP, A) JP-A-7-294455 (JP, A) JP-A-3-269311 (JP, A) Jikho 57-52946 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01J 4/00-4/04 PATOLIS

Claims (5)

(57) [Claims] 1. An ellipsometry device for measuring the state of a sample by measuring the polarization state of reflected light from the sample, and an emission optical system having a polarization means, through which light from a light source is introduced, and an emission optical system. The light receiving optical system that receives the reflected light that is polarized by the optical system and reflected by the sample, the light receiving optical system support base to which the light receiving optical system is fixed, and the intensity of the light from the light receiving optical system are shown. A plurality of detecting means for detecting, a measuring means for measuring the polarization state of the reflected light from the detection results of these detecting means, and measurement data electrically connected to the measuring means and showing the polarization state from the measuring means. To adjust the film thickness and optical constants of the thin film on the sample surface, and adjust the mounting position of the entire light-receiving optical system support in the direction to correct the optical axis deviation calculated by this controller. Manipure Chromatography; and a motor, the light receiving optical system is separated into two more people each two light beams separated by the polarizing beam splitter and polarization beam splitter for separating the light reflected from the sample into two polarization components 2 With two reflective beam splitters,
The light intensity of each light flux separated into two sets, that is, four sets in total, is detected by the detection means to obtain the difference in light intensity for each set, and the direction of the deviation of the optical axis is determined by the sign, and the light is detected by the absolute value. An ellipsometry device, which is characterized by determining the magnitude of axis deviation. 2. The ellipsometry apparatus according to claim 1, wherein the adjusting means is installed in the light receiving optical system. 3. The ellipsometry apparatus according to claim 1, wherein the adjusting means is installed in the emission optical system. 4. The ellipsometry apparatus according to claim 1, wherein the exit optical system has an exit lens for irradiating the sample with polarized light, and the adjusting means is installed in the exit lens. . 5. The ellipsometry device according to claim 1, wherein the reflection type beam splitter is a concave mirror type beam splitter.