JP2003232678A - Light intensity measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light intensity measuring device capable of reducing the size, and capable of measuring light intensity with always stable high accuracy. <P>SOLUTION: The light from a light source part 16 having a Xe flash lamp is irradiated to an etching object base board 5 via an irradiation optical system 9. The reflected light from this etching object base board 5 is detected as a light intensity changing signal via a spectroscope 21 and an integrating circuit 23 of a sensor part 15, and the signal is processed. Afterwards, a prescribed arithmetic operation is performed by a computing element 11. The light source part 16 having the Xe flash lamp and the sensor part 15 are integrally constituted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light intensity measuring device for irradiating a sample with light and measuring a change in intensity of a received light amount of reflected light from the sample.

[0002]

2. Description of the Related Art Conventionally, a film thickness measuring device for a thin film formed on a substrate such as a semiconductor substrate or a glass substrate for a liquid crystal panel, or film formation, etching or flattening in a manufacturing process of a semiconductor substrate or a glass substrate for a liquid crystal panel. The real-time film thickness monitor, which is applied to the end point detector of the chemical conversion process and monitors the film thickness in real time, measures the light intensity by irradiating the sample with light and measuring the intensity change of the amount of light received from the sample. The device is being used.

FIG. 8 shows an etching apparatus having an etching process monitor disclosed in Japanese Patent Laid-Open No. 2001-244254, to which such a light intensity measuring apparatus is applied. In the figure, 1 is an etching chamber, and an etching gas is supplied to the inside of the etching chamber 1. In the etching chamber 1, the upper electrode 2 and the lower electrode 3 are arranged in the vertical direction.
Are arranged facing each other. The upper electrode 2 is grounded, and the lower electrode 3 is connected to a high frequency power supply 4.
Further, the etching target substrate 5 is placed at a position of the lower electrode 3 facing the upper electrode 2. Then, in order to etch the substrate 5 to be etched, the inside of the etching chamber 1 is evacuated and then an etching gas is supplied. next,
When a high-frequency electric field is applied from the high-frequency power source 4 between the upper electrode 2 and the lower electrode 3, plasma is generated in the etching chamber 1, and when the plasma reaches the surface of the substrate 5 to be etched, ions in the plasma flow are generated. The surface reaction is caused by the radical particles, and the substrate 5 to be etched is etched.

On the other hand, above the etching chamber 1,
An observation window 6 is provided, and an irradiation optical system 9 forming a light intensity measuring device is arranged in the observation window 6. In the light intensity measuring device, a light source 7 and a spectroscope 10 are connected to an irradiation optical system 9 via an optical fiber 8. A calculator 11 is connected to the spectroscope 10, and a high frequency power source 4 is connected to the calculator 11.

In such a structure, the light emitted from the light source 7 is transmitted to the irradiation optical system 9 through the optical fiber 8 and is irradiated onto the substrate 5 to be etched by the irradiation optical system 9. The reflected light from the substrate 5 to be etched is transmitted from the irradiation optical system 9 through the optical fiber 8 to the spectroscope 1
Light is received at 0. The spectroscope 10 disperses the reflected light and outputs an electric signal corresponding to the received light intensity of the designated wavelength. This electric signal is sent to the calculator 11. The calculator 11 performs a predetermined calculation from the electric signal indicating the intensity of the reflected light of the specified wavelength, and when the etching end point is detected, the power supply from the high frequency power source 4 is stopped.

Here, FIG. 9 shows a reflected light waveform from the substrate 5 to be etched. From the peak interval of the reflected light waveform, the time t0 for advancing one cycle of the waveform is obtained, and the elapsed time up to the present is t. Then, the current cycle m is calculated by t / t0.

FIG. 10 shows a typical sectional view of the substrate 5 to be etched. In the drawing, 700 is an etching start point, 704 is a mask SiO2 thin film, and 705 is Si.
The board is shown. Further, when the light 1 is irradiated from the upper surface of the substrate 5 to be etched, the reflecting surfaces are 701, 702, 70
Although there are three surfaces, the interference light between the 702 surface and the 703 surface is dominant, and the change amount Δ (ΔS) of the optical path length difference (ΔS).
Is Δ (ΔS) = 2 (d1 + Δd2) -2 (n1 · d1) =
It is represented by mλ. Here, d1 is the film thickness of the mask portion 704,
It does not change even if it is etched. Further, d2 is the etching depth, Δd2 is the etching depth change amount, and n1
Is the refractive index of the mask portion 704, and λ is the wavelength of the light dispersed by the spectroscope 10. As a result, the etching depth change amount Δd2 is calculated by obtaining the current period m of the reflected light waveform.
Can be calculated, and when the etching depth d2 reaches the etching end point, the power supply by the high frequency power source 4 is stopped and the etching is finished.

By the way, recently, with further miniaturization of etching, it is required to minimize the etching depth change amount Δd2, and the time t for advancing one cycle of the reflected light waveform shown in FIG. 9 is required.
It is also required to make 0 smaller. That is,
With the minimization of the etching depth change amount Δd2, the wavelength of the light source 7 has been shortened. Therefore, in the past, as the light source 7, a mercury lamp, a deuterium lamp, an Xe lamp was used.
A UV light source such as a (xenon) lamp is used.

[0009]

By the way, the etching apparatus equipped with such a light intensity measuring apparatus is required to be small in size because the installation space is greatly limited.

However, since UV (ultraviolet) light sources such as mercury lamps, deuterium lamps, and Xe lamps generate a large amount of heat, a large lamp house having an air cooling function is required, and the installation place is greatly limited. There is a problem that it will be done.

Further, since these UV light sources do not have a dimming function, the light amount of the light source decreases during use, and if the optical fiber further deteriorates, the light amount for irradiating the substrate 5 to be etched is increased. Also decreases, and stable light intensity measurement cannot be performed.

Further, these light source 7 and optical fiber 8
Is a replacement part to be replaced due to deterioration, but there is no standard for the replacement time of these parts, and it is difficult to always maintain stable light intensity measurement performance.

Therefore, recently, an Xe flash lamp has been attracting attention as a small UV light source which generates little heat. However, since the Xe flash lamp is intermittently lit and cannot be lit continuously, the amount of light that can be captured on the light receiving side is small. For this reason, there is a problem that it is easily affected by ambient light, the S / N of the reflected light from the substrate to be etched cannot be obtained satisfactorily, and stable light intensity measurement is difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light intensity measuring device which can be miniaturized and can always realize stable and highly accurate light intensity measurement. .

[0015]

The invention according to claim 1 is
At least one intermittent lighting light source, light irradiation means for irradiating the subject, a photodetector for measuring reflected light from the subject, and a signal for processing a light intensity change signal detected by the photodetector It is characterized in that it comprises a processing means and a calculation means for calculating the signal processed by the signal processing means, and at least one of the intermittent lighting light source and the photodetector is integrally configured.

According to a second aspect of the present invention, in the first aspect of the present invention, the signal processing means has an integration circuit means, and the integration time of the integration circuit means is synchronized with the light emission time of the intermittent lighting light source. It is characterized by

A third aspect of the invention is characterized in that, in the first aspect of the invention, the signal processing means includes a peak hold circuit means.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, at least one of the intermittent lighting light sources adjusts the light intensity of the light emitted from the intermittent lighting light source. It is characterized by having an adjusting means.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, at least one of the intermittent lighting light sources includes a replacement timing sensing means for sensing a replacement timing of the intermittent lighting light source, It is characterized in that it is provided with a replacement timing notifying means for notifying the replacement timing of the intermittent lighting light source.

According to a sixth aspect of the invention, in the invention according to any one of the first to fifth aspects, the intermittent lighting light source is
It is characterized by being a xenon flash lamp.

As a result, according to the present invention, since the intermittent lighting light source and the photodetector are integrated, the size can be reduced and the installation with a degree of freedom can be realized.

Further, since a small heat generating and small Xe flash lamp is used as the intermittent lighting light source, further miniaturization can be realized.

Further, since an integrating circuit is used as the signal processing means and the integration time in this integrating circuit is synchronized with the light emission pulse signal of the Xe flash lamp 18, S
It is possible to perform highly accurate light intensity measurement with excellent / N.

Further, since the peak hold circuit means is used as the signal processing means, the intensity of the reflected light from the object is small even when the light source for intermittent lighting has a short emission time and a large emission peak value. The measurement can be performed accurately.

Furthermore, since the intensity of the light emitted from the intermittently lit light source can be adjusted, it is possible to constantly irradiate the subject with a constant amount of light, and it is possible to realize stable and highly accurate light intensity measurement. It is possible to accurately notify the replacement time of the intermittent lighting light source or the like.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a schematic structure of an etching apparatus equipped with an etching process monitor to which the light intensity measuring apparatus of the present invention is applied.
The same reference numerals are given to the same portions as.

In this case, the etching gas is supplied into the etching chamber 1, and the upper electrode 2 and the lower electrode 3 are arranged to face each other along the vertical direction. A high frequency power source 4 is connected to the lower electrode 3, and a substrate 5 to be etched is placed as a subject at a position facing the upper electrode 2 of the lower electrode 3. Upper electrode 2
Is grounded and has an unillustrated hole or glass portion for transmitting the light irradiated on the substrate to be etched 5.

An observation window 6 in which quartz glass is fitted is provided in the upper portion of the etching chamber 1, and the observation window 6 is provided.
The irradiation optical system 9 is arranged as a light irradiation means which constitutes a part of the light intensity measuring device of the present invention. The irradiation optical system 9 irradiates the substrate 5 to be etched with light from the light source unit 16 and is removable from the condenser lens 12 that condenses the reflected light from the substrate 5 to be etched.
It has a reflecting mirror 13 of Al (aluminum) coating which has an excellent reflectance of ultraviolet light.

A process sensor 14 is connected to the irradiation optical system 9 via an optical fiber 8. The process sensor 14 has a sensor unit 15, a light source unit 16 and a control unit 17, which are integrally configured.

FIG. 2 shows such a process sensor 14
Shows a schematic configuration of.

In this case, the light source section 16 has an Xe (xenon) flash lamp 18 as an intermittent lighting light source, a light projecting optical system 19 and a small power source device 20. Xe
The flash lamp 18 has, for example, a maximum lighting frequency of 10
0 Hertz and 1 pulse generate pulsed light of several microseconds, and the pulsed light of several microseconds at this time has a large instantaneous light amount, and disturbance light such as plasma can be ignored. Such Xe flash lamp 18
Is intermittently lit by the small power supply device 20, and the pulsed light generated by the intermittent lighting is incident on the incident end of the optical fiber 8 through the light projecting optical system 19.

The sensor section 15 has a spectroscope (monochromator) 21 as a photodetector, a photomultiplier tube 22, and an integrating circuit 23 as a signal processing means. Spectroscope 21
Is the substrate 5 to be etched which is emitted from the optical fiber 8.
The reflected light from is dispersed and the intensity of light of a predetermined wavelength is extracted. The photomultiplier tube 22 includes the spectroscope 2
It is arranged at the focal position of 1 and outputs an electric signal corresponding to the intensity of light of a predetermined wavelength extracted by the spectroscope 21 as a light intensity change signal. Then, the integrating circuit 23
Is for integrating the light intensity change signal output from the photomultiplier tube 22.

The controller 17 controls the Xe flash lamp 18
The light source control unit 2 that generates an applied voltage control signal for controlling the light emission amount of the light source and generates a light emission pulse signal that is given to the reset unit of the small power supply device 20 and the integration circuit 23.
4 and further has a replacement time sensing means 27 for sensing the replacement time of the Xe flash lamp 18 or the optical fiber 8.
And Xe flash lamp 18 or optical fiber 8 replacement time notification means 28 for notifying the replacement time.
In addition, it has an A / D conversion unit for converting the output (analog signal) from the integration circuit 23 (not shown) into a digital signal, an interface unit with the arithmetic unit 11, and the like.

Although not shown, the etching chamber 1 is provided with a GUI unit, and the operator can control it arbitrarily.
It is possible to set parameters.

Next, the operation of the embodiment thus configured will be described.

Now, when a light emission pulse signal is generated from the light source control section 24 of the process sensor 14 and is input to the small power supply device 20, the Xe flash lamp 18 is intermittently turned on in synchronization with this light emission pulse signal, and the lighting frequency. Up to 100
Hertz and one pulse generate pulsed light of several microseconds. In this case, the pulsed light from the Xe flash lamp 18 has a large instantaneous light quantity, and ambient light such as plasma can be ignored.

The pulsed light from the Xe flash lamp 18 is condensed on the end face of the optical fiber 8 through the light projecting optical system 19 and is deflected by the reflecting mirror 13 of the irradiation optical system 9 through the optical fiber 8 and the condensing lens 12 The substrate 5 to be etched is irradiated through the observation window 6. In this case, when the distance between the condenser lens 12 and the substrate 5 to be etched is variable, it is desirable that the light from the condenser lens 12 be parallel light. When the distance between them is fixed, it is desirable that the light from the condenser lens 12 is condensed on the substrate 5 to be etched.

The light reflected by the substrate 5 to be etched enters the condenser lens 12 of the irradiation optical system 9 through the observation window 6, is deflected by the reflecting mirror 13 and is condensed on the end face of the optical fiber 8. Process sensor 14 through 8
Is incident on the sensor unit 15. In the sensor unit 15, the spectroscope 21 disperses the reflected light to extract the intensity of the light of the predetermined wavelength, and outputs the electric signal according to the intensity of the light of the predetermined wavelength extracted by the photomultiplier tube 22. , To the integrator circuit 23.

The operation up to this point will be described in more detail with reference to the timing chart of FIG. 3. The light emission pulse signal from the light source controller 24 is T as shown in FIG.
It is output at intervals of 0, and a trigger is applied at the rising timing of this light emission pulse signal, and the Xe flash lamp 18 generates pulsed light having a waveform 301 as shown in FIG. In this case, the emission time of one pulse of the pulsed light depends on the capacitance of the capacitor in the small power supply device 20, so if the capacitance of this capacitor is fixed,
The emission time T1 of the Xe flash lamp 18 is stable.

The light emission pulse signal is input to the small power supply device 20 and also to the integration circuit 23 at the same time. In the integrating circuit 23, at the same time when the light emission pulse signal rises,
As shown in (d) of the same figure, charging is started, and charging is performed for a charging period a that is arbitrarily set in advance. Then, the electric signal shown in (e) of the figure is output, and thereafter, when the charging period a elapses, the output from the integration circuit 23 is taken into the control section 17, and the discharge signal shown in (c) of FIG. At the rising timing, the integration circuit 23 performs the discharging operation during the discharging period b set in advance as shown in FIG. The above series of operations is performed at every time interval T0 of the light emission pulse signal.

The output from the integration circuit 23 fetched by the control unit 17 is converted into a digital signal by an A / D conversion unit (not shown) and sent to the arithmetic unit 11.

In the arithmetic unit 11, in the same manner as described above,
A predetermined calculation is performed from the electric signal indicating the intensity of the reflected light, the etching process is monitored, and the etching end point is detected. Then, when the etching end point is detected, an end signal is sent to the high frequency power source 4 to stop the power supply.

By the way, when the etching process is monitored for a long period of time, the light amount of the Xe flash lamp 18 is decreased, and the UV irradiation for a long period of time causes a decrease in the transmittance of the optical fiber 8.

Therefore, the Xe flash lamp 18 is previously prepared.
When the product is new, the Xe flash lamp 18 is turned on without turning on the plasma light, and the spectroscope 21 sets the wavelength required for measurement with respect to the reflected light from the substrate 5 to be etched. The output of the double tube 22 is measured, and this output is stored as the light intensity measurement value V0 in the initial state. After that, every time the light intensity is measured or periodically, Xe
The flash lamp 18 is turned on to turn the substrate 5 to be etched.
The output of the photomultiplier tube 22 is measured according to the reflected light from the. Then, the measured value V1 and the previously stored measured value V0
When the result is below a predetermined threshold value, the control unit 1
7, the applied voltage control signal to the Xe flash lamp 18 is changed to dimming the Xe flash lamp 18 to increase the light emission amount so that the relationship between V1 and V0 is always equal to or greater than a predetermined threshold value. After that, when the applied voltage control signal of the control unit 17 reaches the rated value of the Xe flash lamp 18, the replacement timing detection means 27 senses the replacement timing of the Xe flash lamp 18 or the optical fiber 8 and the replacement timing notification means 28. Sends a signal to a GUI unit (not shown) to notify the operator that it is time to replace the Xe flash lamp 18 or the optical fiber 8.

Therefore, in this case, the light source section 16 having the Xe flash lamp 18, the spectroscope (monochromator) 21, the photomultiplier tube 22, and the sensor section 15 having the integrating circuit 23 are integrated. Therefore, the size can be reduced and the installation can be realized with a high degree of freedom.

Further, since the Xe flash lamp 18 of low heat generation and small size is used as the light source, further downsizing can be realized.

Further, the light intensity of the Xe flash lamp 18 is adjusted on the basis of the light intensity measured in the initial state, and it is possible to irradiate the substrate 5 to be etched with a constant light amount at all times. High light intensity measurement can be realized.

Furthermore, the integration circuit 23 serves as a signal processing means.
Since the integration time in the integration circuit 23 is synchronized with the light emission pulse signal of the Xe flash lamp 18 by using, it is possible to measure the light intensity with excellent S / N and high accuracy.

Furthermore, since it is possible to notify the replacement time of the Xe flash lamp 18 or the optical fiber 8 from the dimming state of the Xe flash lamp 18, these X
e The decrease in the accuracy of the light intensity measurement due to the deterioration of the flash lamp 18 or the optical fiber 8 can be taken as a stick.

(Second Embodiment) Next, a second embodiment will be described. In this case, the etching device equipped with the light intensity measuring device is the same as that shown in FIG.

FIG. 4 shows a schematic structure of the process sensor 14 applied to such an etching apparatus.
The same parts as those in FIG. 2 are designated by the same reference numerals.

In this case, the sensor unit 15 includes the integration circuit 2
In place of 3, the peak hold circuit 25 is replaced by the photomultiplier tube 22.
Electrically connected to.

Further, the light source control section 24 of the control section 17 controls the X
e Generates an applied voltage control signal for controlling the light emission amount of the flash lamp 18, and also generates a light emission pulse signal to be given to the trigger unit of the small power supply device 20 and the peak hold circuit 25.

The operation of such a configuration will be described in detail with reference to the timing chart shown in FIG. 5. The light source control unit 24 outputs light emission pulse signals at intervals of T0 as shown in FIG. A trigger is applied at the rising timing of the light emission pulse signal, and the Xe flash lamp 18 generates pulsed light having a waveform 301 as shown in FIG.

The light emission pulse signal is input to the small power supply device 20 and at the same time, to the trigger section of the peak hold circuit 25. In the peak hold circuit 25, at the same time as the rising of the light emission pulse signal, as shown in FIG.
It is held when the electric signal corresponding to the reflected light from the substrate 5 to be etched shown in FIG. Then, when the operation time c has elapsed, the value held by the peak hold circuit 25 is taken into the control unit 17, and at the rising timing of the reset signal shown in FIG. As shown in FIG. 3D, the reset operation is performed during a reset period d that is arbitrarily set in advance. The above series of operations is
It is performed at every time interval T0 of the light emission pulse signal.

Therefore, even in this case, the same effect as that of the first embodiment can be obtained, and even when the Xe flash lamp 18 having a short emission time and a large emission peak value is used, It is possible to accurately measure the intensity of the reflected light from the etched substrate 5.

(Third Embodiment) Next, a third embodiment will be described. In this case, regarding the etching device and the process sensor 14 equipped with the light intensity measuring device,
Since these are similar to FIGS. 1 and 2, these figures are incorporated herein by reference.

Here, the control unit 17 of the process sensor 14 is adapted to apply the reference capture signal r shown by the broken line in FIG. 2 to the reset unit of the integrating circuit 23 together with the light emission pulse signal.

The operation of such a configuration will be described in detail with reference to the timing chart shown in FIG. 6. The light source control section 24 outputs light emission pulse signals at intervals of T0 as shown in FIG. A trigger is applied at the rising timing of the light emission pulse signal, and the Xe flash lamp 18 emits pulsed light having a waveform indicated by reference numeral 301 as shown in FIG.

The light emission pulse signal is input to the small power supply device 20 and at the same time, to the reset portion of the integrating circuit 23. Then, in the integrating circuit 23, at the same time as the rising of the light emission pulse signal, the charging period a1 shown in FIG. 7E comes and the photomultiplier tube 22 outputs the substrate 5 to be etched shown in FIG. The electric signal corresponding to the reflected light of is charged. After that, when the light emission time T1 of the Xe flash lamp 18 elapses, the output from the integration circuit 23 is captured by the control unit 17, and the integration circuit 23 changes at the rising timing of the discharge signal shown in FIG. The discharge period b1 shown in (e) of the figure is started and the discharge is performed. At this time, the output from the integration circuit 23 taken into the control unit 17 is set to V1.

Thereafter, the reference take-in signal r is input to the reset section of the integrating circuit 23 at the timing shown in FIG. Then, the charging period a2 shown in (e) of the figure is reached, and the electric signal from the photomultiplier tube 22 is charged. After that, when the time T1 elapses, the output from the integration circuit 23 is taken into the control unit 17, and the integration circuit 23 changes at the rising timing of the discharge signal shown in FIG.
Is discharged. At this time, the output from the integration circuit 23 taken in by the control unit 17 is set to V2. In this case, the output V2 of the integrating circuit 23 originally has a value close to 0. However, if ambient light or the like is large in addition to plasma light, as shown in FIG. Since the corresponding electric signal includes the DC component, this DC component is
3 output V2.

The control unit 17 calculates (V1−V2), subtracts the DC component from the output, converts it into a digital signal by an A / D conversion unit (not shown), and outputs it to the arithmetic unit 11.
Similarly to the above, a predetermined calculation is performed, the etching process is monitored, and the etching end point is detected. The above series of operations is performed at every time interval T0 of the light emission pulse signal.

Therefore, even in this case, the same effect as that of the first embodiment can be obtained, and further, for example, even when disturbance light or the like is included in addition to the plasma light, the influence of the disturbance light is effective. Therefore, it is possible to always perform accurate light intensity measurement.

(Fourth Embodiment) Next, a fourth embodiment will be described. In this case, the etching device equipped with the light intensity measuring device is the same as that shown in FIG.

FIG. 7 shows a schematic structure of the process sensor 14 applied to such an etching apparatus.
The same parts as those in FIG. 2 are designated by the same reference numerals.

In this case, the Xe flash lamp 18 of the light source unit 16 and the light projecting optical system 19 are integrally formed, and the light intensity is adjusted so that the flash lamp 18 and the light projecting optical system 19 can be moved in the optical axis direction. Slide mechanism 26 as means
The focus position f of the projection optical system 19 is moved and adjusted in the optical axis direction of the arrow with respect to the incident end face 8a of the optical fiber 8 by sliding operation of the slide mechanism 26.
The intensity of the light emitted from the e-flash lamp 18 can be adjusted. Further, the control unit 17 detects the replacement timing of the Xe flash lamp 18 and the optical fiber 8 and the replacement timing notification means 27 that notifies the replacement timing of the Xe flash lamp 18 or the optical fiber 8.
Have eight.

In this case, when the flash lamp 18 is new, the focus position f of the projection optical system 19 is intentionally shifted from the incident end face 8a of the optical fiber 8 by sliding operation of the slide mechanism 26 as shown in the figure. . That is,
If you are monitoring the etching process for a long time,
The amount of light emitted from the Xe flash lamp 18 decreases, and the transmittance of the optical fiber 8 also decreases due to long-term UV irradiation. Therefore, when the Xe flash lamp 18 is new, the focal position f of the projection optical system 19 is intentionally shifted from the incident end face 8a of the optical fiber 8 and the Xe flash lamp 18 is turned on without turning on the plasma light. Let Then, the reflected light from the substrate 5 to be etched is set to a wavelength required for measurement by the spectroscope 21, and the photomultiplier tube 22 is set.
Is measured and this output is stored as V0.
After that, the Xe flash lamp 18 is turned on for each measurement or periodically, and the output of the photomultiplier tube 22 according to the reflected light from the substrate 5 to be etched is measured. And
This measured value V1 is compared with V0 stored in advance, and when this result falls below a predetermined threshold value, the focus position f of the projection optical system 19 is brought closer to the incident end face 8a of the optical fiber 8 by the slide operation of the slide mechanism 26. Xe flash lamp 1
The light emission amount of No. 8 is increased and adjusted so that the relationship between V1 and V0 becomes equal to or more than a predetermined threshold value. After that, the slide mechanism 26
If the relationship between V1 and V0 does not exceed the predetermined threshold value even if the focal position f of the projection optical system 19 is brought closer to the incident end face 8a of the optical fiber 8 by the operation of, the replacement time sensing means 27 causes the Xe flash lamp. It is detected that the replacement time of 18 or the optical fiber 8 is reached, and the replacement time notification means 28 notifies that fact.

Therefore, even in this case, the same effect as that of the first embodiment can be obtained, and further, when measuring the light intensity,
Since the amount of light emitted from the Xe flash lamp 18 can be adjusted, a constant amount of light is always applied to the substrate 5 to be etched.
It is possible to irradiate the surface with the light and realize stable and highly accurate light intensity measurement. Further, since it is possible to notify the replacement time of the Xe flash lamp 18 or the optical fiber 8, the deterioration of the accuracy of the light intensity measurement due to the deterioration of the Xe flash lamp 18 or the optical fiber 8 can be a stick.

The present invention is not limited to the above-described embodiment, and can be variously modified at the stage of carrying out the invention without departing from the spirit of the invention.

For example, an example in which the present invention is applied to an etching apparatus equipped with an etching process monitor has been shown.
It may be a light intensity measuring device that measures reflected light from a semiconductor substrate, a glass substrate for a liquid crystal panel, or the like.

Further, the Xe flash lamp 18 is not limited to one, and a plurality of Xe flash lamps may be installed to increase the light quantity and a multi-branched optical fiber may be used.

Further, the spectroscope 21 is not limited to a monochromator, but may be a polychromator capable of simultaneously measuring from the ultraviolet region to the visible region. Further, it may be a wide / narrow band interference filter, or may be one that disperses light.

Further, although the photomultiplier tube 22 is used as the light receiving element, a photodiode, a line sensor camera, a CC
It may be a light receiving element capable of converting light into an electric signal, such as a D camera.

Further, in the fourth embodiment, as the light intensity adjusting means for adjusting the light intensity, the focus position f of the projection optical system 19 can be moved and adjusted in the optical axis direction with respect to the incident end face 8a of the optical fiber 8. Although the slide mechanism 26 described above is used, the optical fiber 8 may be moved on the incident end face 8a side. Further, a light reducing means such as an ND filter or a diaphragm can be used as the light intensity adjusting means.

Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and it is described in the section of the effect of the invention. In the case where the effect described above is obtained, a configuration in which this constituent element is deleted can be extracted as an invention.

[0077]

As described above, according to the present invention, it is possible to provide a light intensity measuring device which can be miniaturized and can always realize stable and highly accurate light intensity measurement.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a process sensor used in the first embodiment.

FIG. 3 is a diagram showing a timing chart for explaining the first embodiment.

FIG. 4 is a diagram showing a schematic configuration of a process sensor used in a second embodiment of the present invention.

FIG. 5 is a diagram showing a timing chart for explaining a second embodiment.

FIG. 6 is a diagram showing a timing chart for explaining a third embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of a process sensor used in a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a schematic configuration of an example of an etching apparatus including a conventional etching process monitor.

FIG. 9 is a diagram showing a reflected light waveform from the substrate to be etched.

FIG. 10 is a view showing a typical cross section of a substrate to be etched.

[Explanation of symbols]

1 ... Etching chamber 2 ... Upper electrode 3 ... Lower electrode 4 ... High frequency power supply 5 ... Substrate to be etched 6 ... Observation window 7 ... Light source 8 ... Optical fiber 8a ... Incident end face 9 ... Irradiation optical system 10 ... Spectrometer 11 ... arithmetic unit 12 ... Condensing lens 13 ... Reflector 14 ... Process sensor 15 ... Sensor part 16 ... Light source 17 ... Control unit 18 ... Xe flash lamp 19 ... Projection optical system 20 ... Small power supply 21 ... Spectrometer 22 ... Photomultiplier tube 23 ... Integrating circuit 24 ... Light source control unit 25 ... Peak hold circuit 26 ... Slide mechanism 27 ... Replacement time sensing means 28 ... Replacement time notification means

Continued front page    F term (reference) 2F065 AA30 BB17 CC17 FF41 GG03                       HH03 LL02 LL12 LL68 QQ02                       QQ03                 2G065 AA04 AB17 BA18 BB02 BB25                       BC08 DA15                 5F004 AA01 BA04 BB18 CB02

Claims (6)

[Claims] 1. At least one intermittent lighting light source, light irradiation means for irradiating a subject, a photodetector for measuring reflected light from the subject, and a change in light intensity detected by the photodetector. A signal processing means for processing a signal and a computing means for computing the signal processed by the signal processing means are provided, and at least one of the intermittent lighting light source and the photodetector is integrally configured. And a light intensity measuring device. 2. The light intensity measurement according to claim 1, wherein the signal processing means has an integration circuit means, and an integration time of the integration circuit means is synchronized with a light emission time of the intermittent lighting light source. apparatus. 3. The light intensity measuring device according to claim 1, wherein the signal processing means includes a peak hold circuit means. 4. At least one of the intermittent lighting light sources,
The light intensity measuring device according to any one of claims 1 to 3, further comprising a light intensity adjusting unit that adjusts the light intensity of the light emitted from the intermittent lighting light source. 5. At least one of the intermittent lighting light sources,
5. The light according to claim 1, further comprising: a replacement timing sensing unit that senses a replacement timing of the intermittent lighting light source, and a replacement timing notification unit that notifies a replacement timing of the intermittent lighting light source. Strength measuring device. 6. The light intensity measuring device according to claim 1, wherein the intermittent lighting light source is a xenon flash lamp.