JP5301770B2 - Thin film semiconductor crystallinity measuring apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure an index value for evaluating the crystallinity of the extremely fine region of a thin-film sample comprising a semiconductor such as polysilicon or the like in a non-destructive and non-contact state with high precision in a short time. <P>SOLUTION: The thin-film sample 6 comprising the semiconductor is irradiated with a microwave and exciting light of energy with the band gap of the sample 6 or above is modulated in its intensity at a predetermined cycle by a modulator 14 and condensed by a lens 9 to irradiate the thin-film sample 6. The intensity of the reflected microwave from the sample 6 changed by irradiation with the exciting light is detected by a microwave detector 10 and the cyclic component synchronized to the intensity modulation of the exciting light is extracted from the detected intensity by a lock-in amplifier 15. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a thin-film semiconductor crystallinity measuring apparatus and method for measuring a crystallinity of a thin-film sample made of a semiconductor such as polysilicon or single crystal silicon.

In the technical field of flat panel displays such as liquid crystal display devices, SOG (System On Glass) technology for forming TFT elements with a thickness of several tens of nanometers on a glass substrate has attracted attention.
Conventionally, TFT elements formed on a glass panel of a liquid crystal display device are mainly composed of an amorphous silicon (a-Si) thin film. However, in recent years, in order to cope with high definition, high image quality, large screen, and improvement in response speed of the display image of the liquid crystal display device, the field effect mobility is applied to the glass panel (on the glass substrate) of the liquid crystal display device. A technique for forming a TFT element composed of a high polysilicon (p-Si) thin film has been developed.
Methods for forming a p-Si thin film on a glass substrate are roughly classified into a high temperature process method and a low temperature process method.
Since the high-temperature process method has a high-temperature processing step of about 1000 ° C., it is necessary to employ quartz glass having high heat resistance as a material for the glass substrate. However, high heat-resistant quartz glass and the like are expensive and difficult to adopt in terms of cost.
On the other hand, in the low temperature process method, the a-Si member is crystallized by laser annealing that irradiates the a-Si member with a pulsed laser to produce a p-Si thin film. For this reason, cheap glass with relatively low heat resistance can be adopted as the material of the glass substrate.
However, the p-Si thin film obtained by crystallization with laser annealing is likely to vary in crystallinity due to fluctuations in conditions such as laser light intensity and irradiation time. The term “crystallinity” as used herein refers to the amount of defects (defect existence degree) and crystal grain size in the sample due to dangling bonds. This variation in crystallinity has a significant adverse effect on the performance of the TFT element on the glass substrate. For this reason, it is important to evaluate the crystallinity of the p-Si thin film. Moreover, in order to evaluate the crystallinity of the p-Si thin film in the product inspection process of the glass panel on which the p-Si thin film (TFT element) is formed, the crystallinity evaluation is performed in a non-contact and non-destructive manner in a short time. Need to do.
Furthermore, in recent years, in order to suppress the variation in crystallinity of each TFT element on the glass substrate, development of a technique for locally crystallizing only a region where the TFT element is formed has been active. For this reason, in evaluating the crystallinity of a p-Si thin film, it is very important to evaluate the crystallinity of a local (small) region.
On the other hand, as a conventional method for evaluating crystallinity of a thin film sample, crystallinity evaluation by Raman spectroscopy, X-ray diffraction method, Rutherford backscattering method, transmission electron diffraction method, and crystallinity evaluation using a scanning electron microscope, etc. It has been known.
For example, Patent Document 1 discloses a technique for evaluating the crystallization process of a thin film sample by measuring the Raman shift of amorphous crystalline silicon by Raman spectroscopy.
JP 2002-176209 A

However, crystallinity evaluation by Raman spectroscopy, crystallinity evaluation by X-ray analysis method, Rutherford backscattering method and transmission electron diffraction method are all expensive because the measuring equipment is expensive and the time required for measurement is long. There was a problem that it was unsuitable for application to product inspection in the process.
In addition, crystallinity evaluation using a scanning electron microscope is not suitable for application to product inspection in a production process because this is essentially a destructive test and also requires a long measurement time. There was a problem.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide an index value for evaluating the crystallinity of a very small region of a thin film sample made of a semiconductor such as polysilicon and the like, and nondestructively Another object of the present invention is to provide a thin film semiconductor crystallinity measuring apparatus and method capable of measuring in a non-contact manner in a short time and with high accuracy.

In order to achieve the above object, the present invention is configured as a thin film semiconductor crystallinity measuring apparatus that performs measurement for crystallinity evaluation of a thin film sample formed of a surface silicon layer of silicon or single crystal silicon formed on a substrate. It is characterized by comprising each means shown in the following (1) to (5).
(1) microwave irradiation means for irradiating the microwaves the thin film sample to.
(2) Excitation light intensity modulation means for intensity-modulating excitation light having energy equal to or higher than the band cap of the thin film sample in a predetermined cycle.
(3) Excitation light irradiation means for condensing and irradiating the thin film sample with the excitation light whose intensity has been modulated by the excitation light intensity modulation means in order to limit it to a local region smaller than the wavelength of the microwave .
(4) Microwave intensity detection means for detecting the intensity of the reflected wave of the microwave from the thin film sample, which changes due to the irradiation of the excitation light.
To remove (5) noise, the detection intensity of the microwave intensity detecting means, the periodic component synchronous with the intensity modulation of the excitation light (which may be referred to as a same frequency component as the intensity modulation frequency of the excitation light) Modulation period component extraction means for extracting.
(6) The crystallinity evaluation index value of the thin film sample is calculated based on the intensity value in the change component of the intensity of the reflected wave of the microwave obtained based on the periodic component extracted by the modulation periodic component extracting means. Calculation means for calculating.
Here, the microwave irradiation means, it is conceivable that includes a waveguide antenna. In this case, at the end adjacent to the thin film sample of the waveguide antenna, it captures the reflected wave of the microwave while emitting the microwaves into the thin film sample.
Further, it is conceivable that the excitation light irradiation means irradiates the thin film sample with the excitation light through an end portion of the waveguide antenna close to the thin film sample.
Preferably, the silicon formed on the substrate is polysilicon formed on a glass substrate, and the surface silicon layer of the single crystal silicon is a surface silicon layer in an epi wafer or a surface silicon layer in an SOI wafer. is there. More preferably, the thickness of the silicon formed on the substrate is several nanometers to several tens of nanometers, and the thickness of the surface silicon layer of the single crystal silicon is several micrometers or less.

When a semiconductor sample is irradiated with an electromagnetic wave, free electrons in the semiconductor sample move (move) by the electric field of the electromagnetic wave, but the movement state is affected by the presence of impurities, defects, and the like in the sample. For this reason, the intensity of the reflected wave of the electromagnetic wave irradiated to the semiconductor sample (change with respect to the intensity of the irradiated wave) is an index of the crystallinity of the sample. In addition, the detection (measurement) of the intensity of the reflected wave is nondestructive and noncontact, and can be performed in a very short time.
However, since the wavelength of electromagnetic waves (microwaves) is as long as several millimeters or more, the crystallinity of a minute region in a thin film sample cannot be evaluated. Further, when the semiconductor sample is thin (thin film sample), as in the case where the semiconductor sample is polysilicon of several nm to several tens of nm, single crystal silicon of several μm or less, etc., The change in the intensity of the reflected wave with respect to the irradiated wave (the change in the intensity of the reflected wave due to the crystallinity of the semiconductor sample) is extremely small, and sufficient measurement sensitivity cannot be obtained, so that sufficient measurement accuracy cannot be ensured. In addition, if the intensity of the excitation light is increased too much in order to increase the measurement sensitivity, the sample may be damaged, and further, the cost of the excitation light source may be increased.
On the other hand, as in the present invention, when the thin film sample is condensed with excitation light having an energy higher than the band cap and irradiated to the minute region, photoexcited carriers are generated in the minute region in the sample, and the optical excitation is performed. The carrier moves by the electromagnetic field. Therefore, if the intensity of the reflected wave that changes due to the irradiation of the excitation light is detected, the detected intensity becomes an index that represents the crystallinity of a minute region (excitation light irradiation region) of the sample.
Here, since the irradiation region of the excitation light is a minute region, the intensity change of the reflected wave is small, and the measurement is easily affected by noise.
On the other hand, as in the present invention, the sample is irradiated with excitation light whose intensity is modulated at a predetermined period, and a component synchronized with the intensity modulation of excitation height is extracted from the intensity of the reflected light. The frequency component (noise) is removed.

According to the present invention, the excitation light is condensed and irradiated to a micro area of the sample, and the intensity of the reflected electromagnetic wave that changes due to the irradiation of the excitation light is detected. Although it is difficult to be affected by areas other than the irradiation area, it is not completely free of influence.
Therefore, an electromagnetic wave shielding part that shields electromagnetic waves is formed at an end portion of the waveguide antenna provided in the electromagnetic wave irradiation means that is close to the thin film sample, and the electromagnetic waves are radiated to the thin film sample at the electromagnetic wave shielding part. At the same time, it is conceivable that a minute opening for capturing the reflected wave of the electromagnetic wave is formed.
Thereby, the irradiation region of the electromagnetic wave on the sample can be limited to a relatively small region, and the influence of the state of the region around the excitation light irradiation region on the sample on the measured value (the intensity of the reflected wave) can be minimized. it can.
On the other hand, the electromagnetic wave irradiation means includes a cavity resonator that resonates the electromagnetic wave therein, and the electromagnetic wave is applied to the thin film sample at a minute opening formed at an end portion of the cavity resonator close to the thin film sample. One that radiates and captures the reflected wave of the electromagnetic wave can be considered.
Even with such a configuration, the influence of the state of the region around the excitation light irradiation region in the sample on the measurement value (the intensity of the reflected wave) can be minimized. Furthermore, even if the power of the electromagnetic wave supplied to the cavity resonator is small, the sample can be efficiently irradiated with the electromagnetic wave while suppressing power loss.
Note that the present invention can also be understood as a method for measuring the crystallinity of a thin film semiconductor in which the above-described thin film semiconductor crystallinity measuring apparatus is used for measuring the crystallinity of a thin film sample made of a semiconductor.

According to the present invention, with respect to a thin film sample made of a semiconductor such as polysilicon, a measured value (intensity of reflected electromagnetic wave) as an index for crystallinity evaluation is obtained with high spatial resolution (very small area), nondestructive and non-destructive. It can be measured in contact, in a short time and with high accuracy.
In particular, at a position close to the sample, an electromagnetic wave is radiated to the sample through a minute opening from the electromagnetic wave shielding unit provided at the end of the waveguide antenna or the end of the cavity resonator that resonates the electromagnetic wave inside. By providing, the influence of the state of the region around the excitation light irradiation region in the sample on the measurement value (the intensity of the reflected wave) can be minimized. As a result, it is possible to perform highly accurate measurement with higher spatial resolution.

Embodiments of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: It is not the thing of the character which limits the technical scope of this invention.
FIG. 1 is a diagram showing a schematic configuration of the thin film semiconductor crystallinity measuring apparatus X1 according to the first embodiment of the present invention, FIG. 2 is a flowchart showing a measurement procedure by the thin film semiconductor crystallinity measuring apparatus X1, and FIG. FIG. 4 is a diagram showing changes in the intensity of excitation light and reflected microwave in the thin film semiconductor crystallinity measuring apparatus X1, and FIG. 4 is an outline of the characteristic part of the thin film semiconductor crystallinity measuring apparatus X2 according to the second embodiment of the present invention. FIG. 5 is a diagram showing a schematic configuration of a characteristic part of a crystallinity measuring apparatus X3 for a thin film semiconductor according to a third embodiment of the present invention.

[First Embodiment]
First, a thin film semiconductor crystallinity measuring apparatus X1 (hereinafter referred to as crystallinity measuring apparatus X1) according to a first embodiment of the present invention will be described with reference to the schematic configuration diagram shown in FIG.
The crystallinity measuring apparatus X1 is an apparatus for acquiring measurement values used for crystallinity evaluation of a thin film sample 6 (hereinafter referred to as a sample 6) made of a semiconductor. Here, examples of the sample 6 include polysilicon (p-Si) formed on a substrate made of glass or the like and having a thickness of several nanometers to several tens of nanometers, or a surface silicon layer in an epi wafer or SOI wafer. .
As shown in FIG. 1, the crystallinity measuring apparatus X1 includes a microwave oscillator 1, a circulator 2, a waveguide 3, an E-H tuner 4, a waveguide antenna 5, a sample stage 7, a mirror 8, a lens 9, and a micro A wave detector 10, an amplifier 11, an excitation laser light source 12, an oscillator 13, a modulator 14, a lock-in amplifier 15, and a computer 16 are provided.

The excitation laser light source 12 is a light source that outputs excitation light that irradiates the sample 6, and is, for example, a semiconductor laser that emits excitation light having a wavelength of 375 nm and a power of 20 mW. The output light (excitation light) of the excitation laser light source 12 has energy higher than the band cap of the sample 6. Here, the fact that the excitation light has energy higher than the band cap of the sample 6 is a condition for changing the conductivity of the sample 6.
The excitation light emitted from the excitation laser light source 12 is intensity-modulated at a constant period (a constant frequency) by a modulator 14 (an example of excitation light intensity modulation means) constituted by an acousto-optic modulator or a chopper. The frequency of this intensity modulation is controlled by a synchronization signal output from the oscillator 13 with a constant period (a constant frequency: for example, about 1 kHz to several MHz). Further, the synchronization signal of the oscillator 13 (that is, the signal synchronized with the intensity modulation by the modulator 14) is also transmitted to the lock-in amplifier 15.
Further, the excitation light that has been intensity-modulated by the modulator 14 is reflected by the mirror 8, condensed by the lens 9 (condensing means), and passes through the minute aperture 3 a provided in the waveguide 3. Then, a minute measurement site (for example, a spot having a diameter of about 5 to 10 μm) on the surface of the sample 6 placed on the sample table 7 through the end (opening) of the waveguide antenna 5 close to the sample 6. ). Thereby, excitation carriers are generated in a minute excitation light irradiation region (measurement site) in the sample 6.
The optical device (mirror 8 and lens 9) that collects the excitation light output from the excitation laser light source 12 and guides it to the sample 6 is an example of the excitation light irradiation means.

The microwave oscillator 1 outputs a microwave that is an electromagnetic wave applied to the sample 6 excited by excitation light. For the microwave oscillator 1, for example, a Gunn diode having a frequency of 26 GHz can be employed.
As shown in FIG. 1, the waveguide antenna 5 has an end (opening) disposed close to the sample 6 and transmits microwaves. The waveguide antenna 5 guides the microwave (electromagnetic wave) passing through the waveguide 3 to the sample 6 side, and transmits the microwave to the sample 6 at an end portion (opening portion) close to the sample 6. While radiating, the microwave reflected on the sample 6 (hereinafter referred to as reflected microwave) is captured and guided again to the waveguide 3.
Microwaves emitted from the microwave oscillator 1 are transmitted to the waveguide 3 by the circulator 2 and further communicated with the waveguide 3 via the EH tuner 4 provided in the middle of the waveguide 3. The sample 6 excited by the excitation light is irradiated through the waveguide antenna 5.
The microwave oscillator 1, the circulator 2, the waveguide 3, and the waveguide antenna 5 are examples of electromagnetic wave irradiation means for irradiating the sample 6 with microwaves (electromagnetic waves).
Then, the reflected microwave captured by the waveguide antenna 5 reaches the circulator 2 from the waveguide antenna 5 through the EH tuner 4 and is further transmitted to the microwave detector 10 by the circulator 2. Is done.
The microwave detector 10 is a detector that receives a reflected microwave and generates and outputs an electric signal (current or voltage) corresponding to the intensity of the reflected microwave (an example of a microwave intensity detecting means). The intensity of the reflected microwave detected by the microwave detector 10 changes as the sample 6 is irradiated with excitation light, as will be described later.

The lock-in amplifier 15 (an example of a modulation period component extracting unit) detects the microwave detector 10 amplified by the amplifier 11 based on the synchronization signal obtained from the oscillator 13 (a signal synchronized with the intensity modulation of the excitation light). A component synchronized with the intensity modulation of the excitation light is extracted from the signal (intensity signal of the reflected microwave), and the extracted signal is transmitted to the computer 16.
FIG. 3 is a diagram schematically showing changes in the intensity of the excitation light and the reflected microwave in the crystallinity measuring apparatus X1.
As shown in FIG. 3, when the excitation light applied to the sample 6 has been subjected to intensity modulation at a constant period, the intensity of the reflected microwave detected by the microwave detector 10 is also the same as that of the excitation light. It changes in synchronism with the intensity modulation (with the same period).
Here, the periodic signal used by the intensity modulation of the excitation light (output from the oscillator 13) is output from the intensity of the reflected microwave (detection intensity of the microwave detector 10) changed by the irradiation of the excitation light by the lock- in amplifier 15. If a periodic component synchronized with the signal (periodic component synchronized with the intensity modulation of the excitation light) is extracted on the basis of the signal having a constant period, a component that changes the intensity of the reflected microwave due to the excitation light can be obtained. With this lock-in amplifier 15, for example, when the intensity modulation frequency of the excitation light is about 1 MHz, the intensity of the reflected microwave (the intensity of the excitation light) in the measurement frequency band of about 10 Hz (that is, the band of about 1 MHz ± 5 Hz). Periodic component synchronized with modulation) can be measured. Thereby, unnecessary noise components such as power supply noise (about 50 Hz or about 60 Hz) can be removed and measured. FIG. 3 shows an example of excitation light that has been intensity-modulated in a sine wave shape, but it is also conceivable that the sample 6 is irradiated with excitation light that has been intensity-modulated in a square wave shape (ON / OFF). It is done.

Here, the excitation light is pulsed light, and the intensity of the reflected microwave that changes due to the irradiation of the excitation light (pulsed light), the peak value, and the time (attenuation time) from when the peak occurs until attenuation is reached. This is an index value for evaluating the crystallinity of the sample 6.
However, when pulsed excitation light (for example, pulse width 10 ns) is irradiated, the time constant of the intensity change of the reflected microwave may be 1 μs or less. For this reason, in order to detect the peak value and the decay time of the intensity of such reflected microwaves, the microwave detector 10 and the device that captures the detection signal need to be measured in a measurement frequency band of 10 MHz or more. Become.
On the other hand, as described above, the crystallinity measuring apparatus X1 can perform measurement in a measurement frequency band of about 10 Hz, for example.
In general, noise is proportional to the square root of the measurement frequency band. Therefore, according to the crystallinity measuring apparatus X1, the S / N ratio is 1000 times or more ((10 × 10 ⁶ / 10) More than ^1/2 ). As a result, even if the irradiation spot of the excitation light on the sample 6 is made very small by the lens 9, the intensity of the reflected microwave that changes due to the irradiation of the excitation light can be measured with sufficient sensitivity (with low noise).
The computer 16 includes a CPU, a storage unit, an input / output signal interface, and the like. When the CPU executes a predetermined program, the output signal of the lock-in amplifier 15 (the signal of the excitation light modulation period component of the intensity of the reflected microwave) is obtained. ) And the control of the microwave oscillator 1, the excitation laser light source 12, the oscillator 13, the modulator 14, the sample stage 7, and the like.
The output signal of the lock-in amplifier 15 is taken into the computer 16 and stored in a storage unit provided in the computer 16.
The sample stage 7 is constituted by, for example, an XY stage or the like, and performs positioning of the sample 6 in a two-dimensional direction. The sample stage 7 positions the measurement site (excitation light irradiation position) in the sample 6.

Next, the measurement procedure of the sample 6 by the crystallinity measuring apparatus X1 will be described with reference to the flowchart shown in FIG. Hereinafter, steps S1, S2,... Represent identification codes of processing procedures (steps). Further, the processing executed by the computer 16 is realized by the CPU (processor) of the computer 16 executing a predetermined program.
First, the computer 16 sets the measurement position (excitation light irradiation position) of the sample 6 by controlling the sample stage 7 (S1).
Next, the calculator 16 operates the microwave oscillator 1 to irradiate the sample 6 with microwaves (S2, an example of an electromagnetic wave irradiation procedure).
Next, the calculator 16 operates the excitation laser light source 12, the oscillator 13, and the modulator 14 to modulate the intensity of the excitation light at a predetermined period by the modulator 14, and the intensity-modulated excitation light is applied to the sample 6. At the same time, the detection signal of the lock-in amplifier 15 (a signal obtained by extracting a component synchronized with the excitation light intensity modulation from the intensity signal of the reflected microwave detected by the microwave detector 10) is captured and the signal value is stored. (S3, an example of an excitation light intensity modulation procedure, an excitation light irradiation procedure, an electromagnetic wave intensity detection procedure, and a modulation period component extraction procedure).
Next, the computer 16 determines whether or not the measurement of the measurement site of the sample 6 has been completed for all the predetermined measurement positions (S4).

Thereafter, the computer 16 repeats the processes of steps S1 to S4 described above until it is determined that the measurement has been completed for all measurement positions.
When the calculator 16 determines that the measurement has been completed for all measurement positions, the calculator 16 determines the sample 6 based on the intensity value of the reflected microwave obtained in step S3 (periodic component synchronized with excitation light intensity modulation). A crystallinity evaluation index value is calculated, and the calculation result is recorded in the storage unit of the computer 16 and is output to a predetermined external device (for example, a display device) (S5), and the measurement process is terminated.
Here, as the crystallinity evaluation index value, for example, the maximum value or the average value of the intensity value of the reflected microwave at each measurement position obtained in step S3 can be considered.
Thus, according to the crystallinity measuring apparatus X1, the measured value (intensity of the reflected electromagnetic wave) serving as an index for evaluating the crystallinity of the sample 6 made of a semiconductor (for example, polysilicon having a film thickness of about 50 nm) is obtained. It can measure with high spatial resolution (very small area), non-destructive and non-contact, and in a short time and with high accuracy.

[Second Embodiment]
Next, a thin film semiconductor crystallinity measuring apparatus X2 (referred to as a crystallinity measuring apparatus X2) according to a second embodiment of the present invention will be described with reference to the schematic configuration diagram shown in FIG.
FIG. 4 is a diagram showing a configuration of a waveguide antenna 5 ′ that is a characteristic part of the crystallinity measuring apparatus X2. The crystallinity measuring apparatus X2 is obtained by replacing the portion of the waveguide antenna 5 in the crystallinity measuring apparatus X1 described above with the portion of the waveguide antenna 5 ′ shown in FIG. The content of the processing is the same as that of the crystallinity measuring apparatus X1. Of the constituent elements of the crystallinity measuring apparatus X2 shown in FIG. 4, the same reference numerals as those in FIG.
In the crystallinity measuring apparatus X2, a shield portion 5′c (an example of an electromagnetic wave shield portion) made of a conductor that shields microwaves is provided at an end portion of the waveguide antenna 5 ′ communicating with the waveguide 3 in the vicinity of the sample 6. ) Is formed, and in the shielding portion 5′c, a microscopic aperture 5′b that radiates the microwave to the sample 6 and captures the reflected wave (reflected microwave) of the microwave is formed.
Further, the excitation light is condensed by the first lens 9 a and the second lens 9 b and is irradiated on a minute region of the sample 6. The first lens 9 a is a lens that collects the excitation light so as to pass through the minute opening 3 a provided in the waveguide 3.
The second lens 9b is provided in the waveguide antenna 5 ′, and allows excitation light to pass through the minute opening 5′b provided in the shielding part 5′c. It is a lens that collects light to irradiate a part. Note that the second lens 9b has a thickness of about 2 to 3 mm, and does not significantly affect the reflection and absorption of the microwave.
Thereby, the microwave irradiation area | region with respect to the said sample 6 can be restrict | limited to a comparatively minute area | region, and the influence of the state of the area | region around the excitation light irradiation area | region in the said sample 6 has on the measured value (intensity of a reflected microwave). It can be made as small as possible. As a result, it is possible to perform highly accurate measurement with higher spatial resolution.
Here, the size of the minute opening 5′b is, for example, about 1 mm (vertical) × 2 mm (horizontal).

[Third Embodiment]
Next, a thin film semiconductor crystallinity measuring apparatus X3 (hereinafter referred to as a crystallinity measuring apparatus X3) according to a third embodiment of the present invention will be described with reference to the schematic configuration diagram shown in FIG.
FIG. 5 is a diagram showing the configuration of the cavity resonator 50 that is a characteristic part of the crystallinity measuring apparatus X3. The crystallinity measuring device X3 is obtained by replacing the portion of the waveguide antenna 5 in the above-described crystallinity measuring device X1 with the portion of the cavity resonator 50 shown in FIG. The content is the same as that of the crystallinity measuring apparatus X1. Of the constituent elements of the crystallinity measuring apparatus X3 shown in FIG. 5, the same components as those of the crystallinity evaluation apparatuses X1 and X2 described above are denoted by the same reference numerals as those in FIGS.
The cavity resonator 50 resonates (exists) only a microwave having a specific frequency that satisfies a predetermined resonance condition.
In the crystallinity measuring apparatus X 3, the microwave is transmitted from the circulator 2 (see FIG. 1) to the cavity resonator 50 through the coaxial cable 30, and through the coupler 60 that couples the coaxial cable 30 and the cavity resonator 50. Incident into the vessel 50.
Micro openings 51 and 52 are provided at both ends of the cavity resonator 50 (the microwave incident side and the side close to the sample 6), respectively. Then, the microwave in the cavity 50 is radiated to the sample 6 through a minute opening 52 provided at the end of the cavity 50 close to the sample 6. The reflected wave (reflected microwave) is captured by the same minute opening 52 and enters the cavity resonator 50, enters the coaxial cable 30 through the coupler 60, and is transmitted to the circulator 2 (see FIG. 1).
On the other hand, the excitation light is condensed by the first lens 9a and the second lens 9b and irradiated onto a minute region of the sample 6 as in the crystallinity measuring apparatus X2 (FIG. 4). The first lens 9 a is a lens that condenses the excitation light so as to pass through a minute opening 51 provided at one end of the cavity resonator 50.
The second lens 9b is provided in the cavity resonator 50, and allows excitation light to pass through a minute opening 52 provided at an end portion on the side close to the sample 6, and a minute region of the sample 6 ( It is a lens that collects light to irradiate the measurement site.
Even with such a configuration, the microwave irradiation area on the sample 6 can be limited to a relatively small area, and high-precision measurement can be performed with higher spatial resolution.
In addition, by using the cavity resonator 50 as the microwave irradiation means for the sample 6, even if the microwave power output from the microwave oscillator 1 is small, the microwave is efficiently transmitted while suppressing power loss. The sample 6 can be irradiated.

  The present invention can be used in a measuring apparatus for evaluating the crystallinity of a thin film sample made of a semiconductor such as polysilicon or single crystal silicon.

The figure showing schematic structure of the crystallinity measuring apparatus X1 of the thin film semiconductor which concerns on 1st Embodiment of this invention. The flowchart showing the measurement procedure by the crystallinity measuring apparatus X1 of a thin film semiconductor. The figure showing the change of each intensity | strength of the excitation light and reflected microwave in the crystallinity measuring apparatus X1 of a thin film semiconductor. The figure showing schematic structure of the characteristic part of the crystallinity measuring apparatus X2 of the thin film semiconductor which concerns on 2nd Embodiment of this invention. The figure showing schematic structure of the characteristic part of the crystallinity measuring apparatus X3 of the thin film semiconductor which concerns on 3rd Embodiment of this invention.

Explanation of symbols

X1, X2, X3 ... Thin film semiconductor crystallinity measuring apparatus 1 ... Microwave oscillator 2 ... Circulator 3 ... Waveguide 4 ... E-H tuner 5, 5 '... Waveguide antenna 5'c ... Shielding part 6 ... Thin film Sample 7 ... Sample stand 8 ... Mirror 9, 9a, 9b ... Lens 10 ... Microwave detector 11 ... Amplifier 12 ... Excitation laser light source 13 ... Oscillator 14 ... Modulator 15 ... Lock-on amplifier 16 ... Computer 30 ... Coaxial cable 50 ... Cavity resonator 60... Couplers S1, S2,... Processing procedure (step)

Claims (7)

A thin film semiconductor crystallinity measuring apparatus for measuring a crystallinity of a thin film sample formed of a surface silicon layer of silicon or single crystal silicon formed on a substrate,
Microwave irradiating means for irradiating microwave to said thin film sample,
Excitation light intensity modulating means for modulating the intensity of excitation light having energy equal to or higher than the band cap of the thin film sample at a predetermined period;
Excitation light irradiation means for condensing and irradiating the thin film sample with the excitation light intensity-modulated by the excitation light intensity modulation means in order to limit it to a local region smaller than the wavelength of the microwave ;
A microwave intensity detecting means for detecting the intensity of the reflected wave of the microwave from the thin film sample, which is changed by irradiation of the excitation light;
To remove the noise, the detection intensity of the microwave intensity detecting means, a modulation period component extracting means for extracting the synchronous with periodic components in the intensity modulation of the excitation light,
Calculation for calculating the evaluation index value of the crystallinity of the thin film sample based on the intensity value in the intensity changing component of the reflected wave intensity of the microwave obtained based on the periodic component extracted by the modulation periodic component extracting means Means,
Equipped with,
The thickness of silicon formed on the substrate is several nm to several tens of nm,
The thin-film semiconductor crystallinity measuring device, wherein the surface silicon layer of the single crystal silicon has a thickness of several micrometers or less . The microwave irradiation means comprises a waveguide antenna at the end adjacent to the thin film sample of the waveguide antenna captures the reflected wave of the microwave while emitting the microwaves into the thin film sample Do Te Ri,
The lens included in the excitation light irradiation unit is provided inside the waveguide antenna, and the excitation light is collected by the lens and irradiated to the thin film sample. For measuring crystallinity of thin film semiconductors. The crystallinity measuring apparatus for a thin film semiconductor according to claim 2, wherein the excitation light irradiation means irradiates the thin film sample with the excitation light through an end portion of the waveguide antenna adjacent to the thin film sample and the lens. . Its end proximate to the thin film sample of the waveguide antenna, is formed a microwave shielding section for shielding microwaves of the microwave with the microwave into the microwave shielding section radiates the thin film sample 4. The thin film semiconductor crystallinity measuring apparatus according to claim 2, wherein an opening for capturing the reflected wave is formed. The microwave irradiation means comprises a cavity resonator for resonating the microwaves inside, at an opening formed in the end proximate the thin-film specimen of the cavity resonator, the microwaves into the thin film sample The thin-film semiconductor crystallinity measuring device according to claim 1, wherein the thin-film semiconductor crystallinity measuring device is configured to radiate and capture a reflected wave of the microwave . The silicon formed on the substrate is polysilicon formed on a glass substrate,
The crystallinity measurement of a thin film semiconductor according to any one of claims 1 to 5, wherein the surface silicon layer of the single crystal silicon is a surface silicon layer in an epi wafer or a surface silicon layer in an SOI wafer. apparatus. A method for measuring the crystallinity of a thin film semiconductor for measuring the crystallinity of a thin film sample comprising a surface silicon layer of silicon or single crystal silicon formed on a substrate,
A microwave irradiation procedure to irradiation with microwaves to said thin film sample,
An excitation light intensity modulation procedure for intensity-modulating excitation light having an energy equal to or higher than the band cap of the thin film sample at a predetermined period;
Excitation light irradiation procedure for condensing and irradiating the thin film sample with the excitation light intensity-modulated by the excitation light intensity modulation procedure in order to limit it to a local region smaller than the wavelength of the microwave ,
A microwave intensity detection procedure for detecting an intensity of a reflected wave of the microwave from the thin film sample, which is changed by irradiation of the excitation light;
To remove the noise, the detection intensity of the microwave intensity detection procedure, the modulation period component extracting procedure for extracting the synchronous with periodic components in the intensity modulation of the excitation light,
Calculation for calculating the evaluation index value of the crystallinity of the thin film sample based on the intensity value in the intensity changing component of the reflected wave intensity of the microwave obtained based on the periodic component extracted by the modulation periodic component extraction procedure Procedure and
I have a,
The thickness of silicon formed on the substrate is several nm to several tens of nm,
The method for measuring the crystallinity of a thin film semiconductor, wherein the thickness of the surface silicon layer of the single crystal silicon is several micrometers or less .

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