TWI880367B - Process monitoring system for plasma device - Google Patents

Abstract

A process monitoring system for plasma device includes an optical sensor array and a signal processor. The optical sensor array is configured to detect a transmission optical signal and a transmission background signal respectively from an emission optical signal and a background signal emitted from plasma. The signal processor is connected to the optical sensor array, and is configured to measure an intensity of a pure emission optical signal by removing the transmission background signal from the transmission optical signal.

Description

Process Monitoring Systems for Plasma Devices

The present invention relates to a process monitoring system for a plasma device, and more particularly, to a process monitoring system for a plasma device used in manufacturing a semiconductor or a display.

In the semiconductor or display manufacturing process, measuring process results using a scanning electron microscope (SEM) and an elliptical polarimeter is highly accurate, but requires a lot of cost and time. Therefore, there is an increasing demand for virtual measurement of process results using measurable information in the manufacturing process. In order to improve the accuracy of virtual measurement, it is necessary to select monitoring factors that are highly correlated with process results and to ensure a large amount of highly reliable sample data (training data) including the monitoring factors.

Optical emission spectroscopy (OES) can determine the state of a plasma by measuring the intensity of light signals emitted by radicals and ions generated during the plasma discharge process of a plasma device. Light signals emitted from radicals and ions appear as signals that expand by several nanometers (nm) at a specific wavelength, which depends on the energy level, temperature, and concentration of a single particle, and the intensity variation of a single signal that is discontinuous relative to the wavelength can be used to indirectly measure the concentration variation of radicals and ions that is highly correlated to process results. This optical emission spectrometer device includes a diffraction grating for separating the emitted light signal and a photodetector array for forming an image of the diffraction spectrum signal.

Since the wavelength resolution of a spectrometer is proportional to the distance between the diffraction grating and the photodetector inside the spectrometer, it is difficult to miniaturize a plasma monitoring spectrometer to be smaller than the feature size because plasma monitoring requires a wavelength resolution in the order of nm. Due to this miniaturization limitation, spectrometers including diffraction gratings are connected to semiconductor or display manufacturing equipment by using reflective optical fibers. Therefore, in process monitoring systems using optical emission spectroscopy (OES) including diffraction gratings, slits, optical fibers, etc., signal distortion such as center wavelength shift and sensitivity fluctuation of the measurement signal may occur due to vibrations inside semiconductor or display manufacturing facilities, degradation of high-temperature processes in plasma devices, or optical path misalignment due to temperature changes.

Therefore, optical emission spectroscopy including diffraction gratings has been used in limited areas, such as endpoint detection where trend change monitoring is required. However, in order to use optical emission spectroscopy to monitor quantitative values with errors within a few percent, such as virtual measurement of process results, it must be robust to vibration, degradation, misalignment, etc., and be able to correct signal distortion caused by alignment errors.

Variations in spectrometer measurement sensitivity over time degrade the accuracy of virtual measurements and can cause deviations between individual plasma devices and spectrometers in a manufacturing facility.

Furthermore, since the spectrum sensor including the diffraction grating causes the measured wavelength of each picture element to shift due to vibration, degradation, and quantitative failure, a continuous array type photodetector must be used for each wavelength.

In addition, the spacing between adjacent elements of a continuous array photodetector is very narrow, only tens of microns, and due to signal interference problems, it is difficult to amplify the signal by applying a high voltage, making it impossible to achieve a signal-to-noise ratio higher than a certain level.

The present invention provides a process monitoring system for plasma devices that can be miniaturized, minimize errors, and correct errors to achieve high reliability.

In addition, the present invention provides a process monitoring system for a plasma device, which can achieve a high signal-to-noise ratio by applying a high voltage for signal amplification and can increase the area of a photodetector for measuring heterogeneous wavelengths.

To achieve the above-mentioned purpose, the present invention provides a process monitoring system for plasma equipment, including an optical sensor array and a signal processor. The optical sensor array is configured to detect a transmitted optical signal and a transmitted background signal from an emitted optical signal and a background signal emitted by a plasma, respectively. The signal processor is connected to the optical sensor array and is configured to measure the intensity of a pure emitted optical signal by removing the transmitted background signal from the transmitted optical signal.

In implementation, the optical sensor array may include at least one first optical sensor and at least one second optical sensor, the first optical sensor is configured to detect a transmitted optical signal, and the second optical sensor is configured to detect a transmitted background signal.

In implementation, the first optical sensor may include an optical signal band transmission filter and a first optical detector, wherein the optical signal band transmission filter is configured to transmit a transmission optical signal from the transmission signal as a transmission optical signal in the transmission optical signal band, and the first optical detector is configured to detect the transmission optical signal transmitted through the optical signal band transmission filter.

In practice, the second optical sensor may include a background signal band transmission filter and a second optical detector, wherein the background signal band transmission filter is configured to transmit a transmitted background signal from the emission signal as a background signal in a background signal band, and the second optical detector is configured to detect the transmitted background signal, which passes through the background signal band transmission filter.

In implementation, the transmitted optical signal may include a first transmitted optical signal having a light quantity equal to or greater than a first reference value and a second transmitted optical signal having a light quantity less than the first reference value. The first optical sensor may include at least one first optical signal optical sensor and at least one second optical signal optical sensor, the first optical signal optical sensor being configured to detect a first transmitted optical signal from the first transmitted optical signal, and the second optical signal optical sensor being configured to detect a second transmitted optical signal from the second transmitted optical signal.

In implementation, the sensitivity of the second optical signal optical sensor may be greater than the sensitivity of the first optical signal optical sensor.

During implementation, the number of the second optical signal optical sensors may be greater than the number of the first optical signal optical sensors.

In implementation, the first optical signal optical sensor may include a first optical signal band transmission filter and a first optical signal detector, wherein the first optical signal band transmission filter is configured to transmit a first transmission optical signal from the transmission optical signal, and the first optical signal detector is configured to detect the first transmission optical signal transmitted through the first optical signal band transmission filter. The second optical signal optical sensor may include a second optical signal band transmission filter and a second optical signal detector, wherein the second optical signal band transmission filter is configured to transmit a second transmission optical signal from the transmission optical signal, and the second optical signal detector is configured to detect the second transmission optical signal transmitted through the second optical signal band transmission filter.

In practice, the gain of the second optical signal detector may be greater than that of the first optical signal detector.

In implementation, the background signal may include a first background signal whose light quantity is equal to or greater than a second reference value and a second background signal whose light quantity is less than the second reference value.

In implementation, the second optical sensor may include at least one first background signal optical sensor and at least one second background signal optical sensor, the first background signal optical sensor being configured to detect a first transmitted background signal from the first background signal, and the second background signal optical sensor being configured to detect a second transmitted background signal from the second background signal.

In practice, the sensitivity of the second background signal optical sensor may be greater than the sensitivity of the first background signal optical sensor.

In implementation, the number of the second background signal optical sensors may be greater than the number of the first background signal optical sensors.

In implementation, the first background signal optical sensor may include a first background signal band transmission filter and a first background signal detector, wherein the first background signal band transmission filter is configured to transmit the first background signal from the background signal, and the first background signal detector is configured to detect the first transmitted background signal transmitted through the first background signal band transmission filter. The second background signal optical sensor may include a second background signal band transmission filter and a second background signal detector, wherein the second background signal band transmission filter is configured to transmit the second background information from the background signal, and the second background signal detector is configured to detect the second transmitted background signal transmitted through the second background signal band transmission filter.

In practice, the gain of the second background signal detector may be greater than that of the first background signal detector.

In implementation, the signal processor may be configured to remove a transmission background signal measured together with the plasma emission signal at the first optical sensor by calculating the first optical sensor signal and the second optical sensor signal.

When implemented, the system may also include an infrared background signal detector, which is connected to the signal processor and configured to detect the infrared background signal emitted from the infrared heater.

In implementation, the signal processor can be configured to remove the infrared background signal detected by the infrared background signal detector from the transmitted optical signal.

When implemented, the system may also include a device module equipped with an optical sensor array and a signal processor.

In practice, the device module may have a cavity shape extending in one direction and having a slit, and the optical sensor array is selectively provided at the slit.

According to an exemplary embodiment of the present invention, a process monitoring system for a plasma device includes an optical sensor array and a signal processor. The optical sensor array includes a first optical sensor and a second optical sensor. The first optical sensor detects a transmitted optical signal emitted from the plasma device and transmitted through an optical signal bandpass transmission filter, and the second optical sensor detects a transmitted background signal through a background signal bandpass transmission filter. The signal processor removes the transmitted background signal from the transmitted optical signal and measures only the intensity of the pure emission optical signal. Therefore, only the intensity of the pure emission optical signal from which the infrared background signal that fluctuates instantaneously and the background signal including dark current noise are removed can be quantitatively measured.

Furthermore, unlike diffraction spectroscopy optical sensors that rely on the optical path, by using an optical sensor that utilizes wavelength dispersion in a transmission method, errors due to heat or vibration, fiber bending, misalignment within semiconductor or display manufacturing facilities can be minimized. As a result, long-term repeatable process monitoring is possible.

In addition, unlike diffraction spectroscopic sensors that rely on the optical path, by using an optical sensor that utilizes wavelength dispersion in a transmission method, it is advantageous to expand the sensor light receiving area and achieve a high signal-to-noise ratio.

Furthermore, unlike diffraction spectroscopic sensors, in which photodetectors for measuring a single wavelength must be placed serially, in optical sensors for wavelength dispersion using the transmission method, the photodetectors can be spaced apart so that there is no mutual interference in the electronic amplification process using a high voltage, and thus a high signal-to-noise ratio can be achieved.

In addition, the number of first optical signal optical sensors and second optical signal optical sensors for monitoring a plurality of plasma emission optical signals (λ1, λ1′) having different light amounts and the gain of the detectors can be adjusted. Therefore, the signal distortion of each wavelength can be corrected according to the sensitivity of the photodetector to each wavelength, and the same signal-to-noise ratio can be achieved for a plurality of plasma devices.

In addition, by including an infrared background signal detector connected to the signal processor and detecting the infrared background signal, the intensity of the emitted light signal can be more accurately measured by more completely removing the infrared background signal.

In addition, when calibrating the sensitivity of each wavelength to manufacture optical sensors with the same performance, the sensitivity of multiple wavelength measurement units in the diffraction type optical sensor varies due to the variation of the positions of the diffraction grating and the detector. In contrast, as in the exemplary embodiment of the present invention, by including an optical sensor array for detecting the transmitted optical signal and the transmitted background signal in the transmission method, it is possible to easily perform calibration based on the sensitivity test results of each wavelength.

Furthermore, by mass-producing optical sensors with the same sensitivity at every wavelength, the same algorithm can be used for process monitoring at multiple semiconductor or display manufacturing facilities.

Furthermore, since the optical sensor array can be easily mounted and removed from the mounting module, it can be used selectively, and can be mounted by slits to minimize mounting errors and improve ease of removal.

In order to further understand the present invention, the following preferred embodiments are given, and the specific components and effects of the present invention are described in detail with reference to the drawings and figure numbers.

The present invention will be described more fully below with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the exemplary embodiments described herein. Instead, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art.

The terms used herein are only used to describe specific exemplary embodiments and are not intended to limit the present invention. As used herein, unless the context clearly indicates otherwise, noun forms without quantity limitation should also include one or more.

It should be further understood that when the terms "include" and/or "comprising" are used in this specification, it specifies the existence of the described features, integers, steps, operations, elements and/or components, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted as an idealized or overly formal meaning unless expressly defined herein.

1 and 2 , a process monitoring system for a plasma device (hereinafter referred to as the system) includes an optical sensor array 100 and a signal processor 200.

The optical sensor array 100 detects a transmitted optical signal OS2 and a transmitted background signal BS2 from the transmitted signal OS emitted by the plasma device PS.

As shown in Fig. 3, the transmission signal OS includes the transmission optical signal OS1 and the background signal BS1. In addition, the background signal BS1 includes the infrared background signal IR and the dark current noise DCN.

3 shows the filter transmittance OF of the optical signal band transmission filter 111 and the filter transmittances BF1 and BF2 of the background signal band transmission filter 121. Using the optical signal band transmission filter 111, the transmitted optical signal OS2 is retained in the transmitted optical signal OS1, and using the background signal band transmission filter 121, the transmitted background signal BS2 is retained in the background signal BS1 (refer to FIG. 4).

The emission signal OS emitted from the plasma device PS passes through the collimator 50 to become parallel light, and then the parallel light is incident on the optical sensor array 100.

The optical sensor array 100 includes at least one first optical sensor 110 and at least one second optical sensor 120.

The first optical sensor 110 detects the transmitted optical signal OS2 in the transmitted signal OS.

The first optical sensor 110 includes an optical signal band transmission filter 111 and a first optical detector 112. The optical signal band transmission filter 111 transmits a transmitted optical signal OS2 as a transmission optical signal OS1 of a transmission optical signal band from the transmission signal OS. The first optical detector 112 detects the transmitted optical signal OS2 which transmits the optical signal band transmission filter 111.

As shown in FIG. 3 and FIG. 4 , the transmission signal OS transmits the optical signal band transmission filter 111 of the first optical sensor 110, and then the transmitted optical signal OS2 remains only in the transmission optical signal OS1.

The second optical sensor 120 detects the transmitted background signal BS2 in the transmitted signal OS.

The second optical sensor 120 includes a background signal band transmission filter 121 and a second optical detector 122. The background signal band transmission filter 121 transmits a transmission background signal BS2 as a background signal B1 of a background signal band from the transmission signal OS. The second optical detector 122 detects the transmission background signal BS2, which transmits the background signal band transmission filter 121.

As shown in FIG. 3 and FIG. 4 , the transmission signal OS transmits the background signal band transmission filter 121 of the second optical sensor 120, and then the transmitted background signal BS2 remains only in the background signal BS1.

As shown in FIG. 5 , the signal processor 200 removes the transmitted background signal BS2 from the transmitted optical signal OS2 in FIG. 4 , and then retains the pure transmitted optical signal OS3 from which the background signal BS1 is removed.

For example, the average values of the transmission background signals LBS2 and RBS2 at the minimum and maximum points of the wavelength band of the transmission optical signal OS2 are removed, and then the pure emission light signal OS3 from which the background signal BS1 is removed is retained.

The first transmission background signal LBS2 is located near the minimum point of the wavelength band of the transmission optical signal OS2, and the second transmission background signal RBS2 is located near the maximum point of the wavelength band of the transmission optical signal OS2. Here, the average values of the first transmission background signal LBS2 and the second transmission background signal RBS2 may overlap with the transmission optical signal OS2. Therefore, the average values of the first and second transmission background signals LBS2 and RBS2 that overlap with the transmission optical signal OS2 are removed, and then the intensity of the emission optical signal OS3 located in the same wavelength band as the transmission optical signal OS2 may be retained.

Therefore, a process monitoring system for a plasma device includes an optical sensor array and a signal processor. The optical sensor array includes a first optical sensor and a second optical sensor. The first optical sensor detects a transmitted optical signal emitted from the plasma device and transmitted through an optical signal bandpass transmission filter, and the second optical sensor detects a transmitted background signal through a background signal bandpass transmission filter. The signal processor removes the transmitted background signal from the transmitted optical signal and measures only the intensity of the pure emission optical signal. Therefore, it is possible to quantitatively measure only the intensity of the pure emission optical signal from which the infrared background signal that fluctuates instantaneously and the background signal including dark current noise are removed.

In addition, the first optical sensor and the second optical sensor of the optical sensor array include a transmission filter and an optical detector, and do not use a diffraction grating and divide the emission signal in a transmission method. Therefore, the optical path required to ensure the wavelength resolution of the nanometer level is shortened, making it possible to miniaturize the process monitoring system of the plasma device.

The system according to this example embodiment may further include an infrared background signal detector.

Hereinafter, with reference to FIG. 6 and FIG. 7 , a process monitoring system for a plasma device according to another exemplary embodiment of the present invention is explained in detail.

Except for the structure of the infrared background signal detector, the system according to the present example embodiment is basically the same as the system in the previous example embodiment, and the same figure labels are used for the same elements, and any repeated explanation will be omitted.

6 , the system according to the present exemplary embodiment includes an optical sensor 100, a signal processor 200, and an infrared background signal detector 300.

The infrared background signal detector 300 is connected to the signal processor 200. The infrared background signal detector 300 detects the infrared background signal IR emitted from the infrared heater IH and transmits the signal IR to the signal processor 200. The infrared heater IH may be provided at the plasma device PS to achieve a uniform temperature, so that the intensity of the background signal BS1 emitted from the plasma device PS may be changed due to the infrared background signal IR.

The signal processor 200 removes the transmission background signal BS2 partially overlapping with the transmission optical signal OS2 from the transmission optical signal band transmission filter 111, and further removes the infrared background signal IR detected by the infrared background detector 300.

As shown in Figure 7, the transmitted signal OS includes the infrared background signal IR emitted from the infrared heater IH, so the signal processor 200 of the system according to the present exemplary embodiment further uses an infrared background signal detector 300 that detects the infrared background signal IR to remove the infrared background signal, and then the intensity of the transmitted optical signal OS3 can be measured more accurately.

Therefore, the system according to the present example embodiment also includes an infrared background signal detector 300 connected to the signal processor 200 and detecting the infrared background signal IR, thereby removing the transmitted background signal BS2 from the transmitted optical signal OS2 and removing the infrared background signal IR emitted from the infrared heater IH, so that the intensity of the pure transmitted optical signal OS3 can be measured more accurately.

Due to the degree of contamination on the observation window surface, the transmittance of each wavelength band varies, so during the maintenance period of semiconductor or display manufacturing equipment, quantitative measurement errors of the transmitted optical signal will occur.

However, the system according to the present exemplary embodiment further includes an infrared background signal detector 300 for detecting the infrared background signal IR, so that the infrared background signal emitted under the same temperature condition of the infrared heater 1H can be converted into a standard light source. In other words, the plasma device is turned off during the maintenance period of the semiconductor or display manufacturing equipment, and the difference between the signals (infrared background signals) of the first and second optical sensors measured at different time points when the temperature of the infrared heater is the same is used, thereby correcting or compensating for the signal attenuation of each wavelength caused by the contamination of the observation window.

In one example, the first optical sensor of the optical sensor array may include a first optical signal optical sensor and a second optical signal optical sensor. The first optical signal optical sensor detects a first transmitted optical signal from a first transmitted optical signal having a light amount equal to or greater than a first reference value, and the second optical signal optical sensor detects the second transmitted optical signal from a second transmitted optical signal having a light amount less than the first reference value. The sensitivity of the second optical signal optical sensor may be greater than the sensitivity of the first optical signal optical sensor.

Hereinafter, with reference to FIG. 8 and FIG. 9 , a process monitoring system for a plasma device according to another exemplary embodiment of the present invention is explained in detail.

Except for the structure of the optical sensor array, the system according to the present example embodiment is substantially the same as the system in the previous example embodiment in FIGS. 1 to 5 , and the same figure numbers are used for the same elements and any repeated explanation will be omitted.

8 and 9 , the system according to the present exemplary embodiment includes an optical sensor array 100 and a signal processor 200.

The optical sensor array 100 includes a plurality of first optical sensors 110 and a plurality of second optical sensors 120.

The first optical sensor 110 detects the transmitted optical signal OS2 from the transmitted optical signal OS1 of the transmitted signal OS.

The transmitted optical signal OS1 includes a first transmitted optical signal OS1_1 having a light amount equal to or greater than a first reference value and a second transmitted optical signal OS1_2 having a light amount less than the first reference value.

The first optical sensor 110 includes at least one first optical signal optical sensor 110L and at least one second optical signal optical sensor 110H.

The first optical signal optical sensor 110L detects the first transmitted optical signal OS2_1 from the first transmitted optical signal OS1_1 having a sufficient light amount equal to or greater than the first reference value, and the second optical signal optical sensor 110H detects the second transmitted optical signal OS2_2 from the second transmitted optical signal OS1_2 having an insufficient light amount less than the first reference value. Here, the sensitivity of the second optical signal optical sensor 110H is greater than the sensitivity of the first optical signal optical sensor 110L.

The first optical signal optical sensor 110L includes a first optical signal band transmission filter 111L and a first optical signal detector 112L. The first optical signal band transmission filter only transmits the first transmitted optical signal OS1_1 of the frequency band λ2 from the transmitted optical signal OS1 having a sufficient amount of light equal to or greater than a first reference value. The first optical signal detector 112L detects the first transmitted optical signal OS2_1 that passes through the first optical signal band transmission filter 111L.

The second optical signal optical sensor 110H includes a second optical signal band transmission filter 111H and a second optical signal detector 112H. The second optical signal band transmission filter 111H only transmits the second transmitted optical signal OS1_2 from the transmitted optical signal OS1 in the wavelength band λ1 having insufficient light amount less than the first reference value. The second optical signal detector 112H detects the second transmitted optical signal OS2_2 that passes through the second optical signal band transmission filter 111H.

Here, the gain of the second optical signal detector 112H is greater than the gain of the first optical signal detector 112L, and the sensitivity of the second optical sensor 110H may be greater than the sensitivity of the first optical sensor 110L.

For example, the second optical signal detector 112H having a relatively large gain may include an avalanche photodiode (APD), a multi-pixel photo counter (MPPC), etc., and the first optical signal detector 112L having a relatively small gain may include a photodetector (PD), etc. However, the magnitude of the gain may be relative without being limited thereto.

In addition, the number of the second optical signal optical sensors 110H may be greater than the number of the first optical signal optical sensors 110L. Therefore, the number of the second optical signal optical sensors 110H detecting the second transmitted optical signal OS2_2 from the second transmitted optical signal OS1_2 having insufficient light is greater than the number of the first optical signal optical sensors 110L detecting the first transmitted optical signal OS2_1 from the first transmitted optical signal OS1_1 having sufficient light.

Therefore, according to the sensitivity of the first optical sensor 110 to each wavelength, the signal distortion of each wavelength can be corrected, and the same level of signal-to-noise ratio (SNR) can be achieved for multiple plasma devices.

Since the emission intensity (or light amount) of another transmitted optical signal itself and the sensitivity of the detector to the corresponding signal wavelength may be different, the number of second optical signal optical sensors 110H detecting the second transmitted optical signal with insufficient light amount is greater than the number of first optical signal optical sensors 110L detecting the first transmitted optical signal with sufficient light amount, thereby satisfying a similar signal-to-noise ratio of transmitted optical signals in multiple bands with different emission optical signal detector sensitivities and intensities.

Virtual measurement of process results in semiconductor or display manufacturing processes requires measuring signals in different wavelength bands depending on the gas used in the process. For example, in the case of silicon (Si) or hydroxide ions (OH), it is necessary to measure emission signals in a wavelength band of 300nm or less, and in the case of oxygen (O), it is necessary to measure emission signals in a wavelength band of 844nm or less. However, emission signals in the corresponding wavelength bands have different wavelength-specific sensitivities according to different transition probabilities and photodetectors.

Conventionally, in the case of a spectrometer including a diffraction grating, since the emission signal is detected by the signal intensity of each wavelength, correction is required after measurement to perform quantitative intensity analysis on each emission optical signal. However, in the present exemplary embodiment, taking into account the emission intensity between the respective emission optical signals, more optical sensors are installed to detect optical signals in wavelength bands having weak monitoring signal intensity for noise, compared to optical sensors detecting optical signals in wavelength bands having high signal intensity, so that signal distortion for each wavelength according to the sensitivity of the first optical sensor 110 to each wavelength can be corrected, and the same level of signal-to-noise ratio can be achieved for a plurality of plasma devices.

The plurality of second optical sensors 120 detect the transmitted background signal BS2 from the background signal BS1 of the transmitted signal OS.

The background signal BS1 includes a first background signal BS1_1 having a light amount equal to or greater than a second reference value and a second background signal BS2_2 having a light amount less than the second reference value.

The second optical sensor 120 includes at least one first background signal optical sensor 120L and at least one second background signal optical sensor 120H.

The first background signal optical sensor 120L detects a first transmission background signal BS2_ from a first background signal BS1_1 having a sufficient light amount equal to or greater than a second reference value, and the second background signal optical sensor 120H detects a second transmission background signal BS2_2 from a second background signal BS1_2 having an insufficient light amount less than the second reference value. Here, the sensitivity of the second background signal optical sensor 120H is greater than the sensitivity of the first background signal optical sensor 120L.

The first background signal optical sensor 120L includes a first background signal band transmission filter 121L and a first background signal detector 122L. The first background signal band transmission filter 121L only transmits the first background signal BS1_1 of the band λ2′ from the background signal BS1 with a sufficient amount of light equal to or greater than a second reference value. The first background signal detector 122L detects the first transmitted background signal BS2_1 that passes through the first background signal band transmission filter 121L.

The second background signal optical sensor 120H includes a second background signal band transmission filter 121H and a second background signal detector 122H. The second background signal band transmission filter 121H only transmits the second background signal BS1_2 in the band λ1′ from the background signal BS1 with insufficient light amount less than the second reference value. The second background signal detector 122H detects the second transmitting background signal BS2_2 that transmits the second background signal band transmission filter 121H.

Here, the gain of the second background signal detector 122H is greater than the gain of the first background signal detector 122, and the sensitivity of the second background optical sensor 120H can be greater than the sensitivity of the first background optical sensor 120L.

For example, the second background signal detector 122H having a relatively large gain may include an avalanche photodiode (APD), a multi-picture element photo counter (MPPC), etc., and the first background signal detector 122L having a relatively small gain may include a photodetector (PD), etc. However, the size of the gain may be relative without being limited thereto.

In addition, the number of the second background signal optical sensors 120H may be greater than the number of the first background signal optical sensors 120L. Therefore, the number of the second background signal optical sensors 120H detecting the second transmission background signal BS2_2 from the second background signal BS1_2 with insufficient light is greater than the number of the first background signal optical sensors 120L detecting the first transmission background signal BS2_1 from the first background signal BS1_1 with sufficient light.

Therefore, according to the sensitivity of the second optical sensor 120 to each wavelength, the signal distortion of each wavelength can be corrected, and the same level of signal-to-noise ratio (SNR) can be achieved for multiple plasma devices.

Referring to FIG. 10 , in the system of FIG. 1 , the optical sensor array 100 and the signal processor 200 may be fixed or equipped to the device module 400.

The device module 400 has a predetermined chamber shape extending in one direction, and the optical sensor array 100 and the signal processor 200 may be fixed or assembled at the device module 400.

Here, the condensing lens 500 may be additionally fixed at the device module 400. The condensing lens 500 is fixed to the front surface of the device module 400, and the condensing lens 500 condenses the incident light and provides the light to the optical sensor array 100 disposed at the rear side.

In the system according to the present exemplary embodiment, a light signal generated in a plasma-using process in a semiconductor or display manufacturing process is provided as an input signal, and the focusing lens 500 may be disposed toward the plasma device PS in which the plasma-using process is performed.

Here, although not shown in the figure, the focusing lens 500 may be disposed at a window formed at the plasma device PS, or an optical signal may be incident into the focusing lens 500 through an optical waveguide from the plasma device PS. Therefore, the position of the focusing lens 500 may be variously changed in consideration of the arrangement or structure of the plasma device PS or the equipment module 400.

Therefore, the emission signal OS emitted from the plasma device PS is provided into the internal space 401 of the device module 400 through the condensing lens 500, and is incident into the optical sensor array 100. In addition, the condensing lens 500 may be a convex lens.

The insulating portion 450 and the heat dissipating portion 460 may be disposed at the front side of the condensing lens 500.

Since the emission signal OS from the plasma device PS is provided to the condensing lens 500, relatively high heat energy can be provided in addition to the emission signal. Therefore, the insulating portion 450 can block the heat provided to the condensing lens 500, and the heat dissipation portion 460 can dissipate the heat provided to the condensing lens 500. Here, the heat dissipation portion 460 can be provided at the front side of the insulating portion 450.

Therefore, when the insulating portion 450 and the heat dissipation portion 460 are provided, the detection error of the optical sensor array 100 can be minimized by preventing the heat of the plasma process from being provided to the optical sensor array 100.

The optical sensor array 100 is selectively mounted on the rear side of the condensing lens 500. Considering the emission signal OS emitted from the plasma device PS, the optical sensor array 100 can be selected to transmit the optical signal in a predetermined frequency band based on the process conditions of the plasma process, and then the selected optical sensor array 100 can be assembled or fixed to the device module 400.

Here, as described above, the optical sensor array 100 includes the first optical sensor 110 having the optical signal band transmission filter 111 and the first optical detector 112, and the second optical sensor 120 having the background signal band transmission filter 121 and the second optical detector 122.

Therefore, the filter unit having the integrally formed wideband transmission filter 111 and the background signal band transmission filter 121 can be assembled or fixed at the first slit 410 on the front side of the device module 400. In addition, the optical detector having the integrally formed first optical detector 112 and the second optical detector 122 can be assembled or fixed at the second slit 420 provided on the rear side of the first slit 410.

Here, the first slit 410 and the second slit 420 are spaced apart from each other by a predetermined distance, and the distance may be variously changed.

In addition, the signal processor 200 may be additionally provided or fixed at a third slit 430 disposed at the rear side of the second slit 420 .

Therefore, the optical sensor array 100 is selectively equipped, and the signal processor 200 is fixed at the device module 400, and the optical sensor module suitable for the transmission signal OS generated from the plasma device PS can be selectively attached and detached as a single module structure.

According to an exemplary embodiment of the present invention, a process monitoring system for a plasma device includes an optical sensor array and a signal processor. The optical sensor array includes a first optical sensor and a second optical sensor. The first optical sensor detects a transmitted optical signal emitted from the plasma device and passing through an optical signal bandpass transmission filter, and the second optical sensor detects a transmitted background signal passing through a background signal bandpass transmission filter. The signal processor removes the transmitted background signal from the transmitted optical signal and measures only the intensity of the pure emission optical signal. Therefore, only the intensity of the pure emission optical signal from which the infrared background signal that fluctuates in real time and the background signal including dark current noise are removed can be quantitatively measured.

Furthermore, unlike diffraction spectroscopy optical sensors that rely on the optical path, by using an optical sensor that utilizes wavelength dispersion in a transmission method, errors caused by misalignment due to bending of optical fibers caused by heat or vibration inside semiconductor or display manufacturing facilities can be minimized. As a result, long-term repeatable process monitoring is possible.

In addition, unlike diffraction spectroscopic sensors that rely on the optical path, by using an optical sensor that utilizes wavelength dispersion in a transmission method, it is advantageous to expand the sensor light receiving area and achieve a high signal-to-noise ratio.

Furthermore, unlike a diffraction spectroscopic sensor in which photodetectors for measuring a single wavelength must be placed in series, in an optical sensor for wavelength dispersion using a transmission method, the photodetectors can be spaced apart so that there is no mutual interference in the electron amplification process using a high voltage, thereby achieving a high signal-to-noise ratio.

In addition, the number of first optical signal optical sensors and second optical signal optical sensors for monitoring a plurality of plasma emission optical signals (λ1, λ1′) having different light amounts and the gain of the detectors can be adjusted. Therefore, the signal distortion of each wavelength can be corrected according to the sensitivity of the photodetector to each wavelength, and the same signal-to-noise ratio can be achieved for a plurality of plasma devices.

In addition, by including an infrared background signal detector connected to the signal processor and detecting the infrared background signal, the intensity of the emitted light signal can be more accurately measured by more completely removing the infrared background signal.

In addition, when calibrating the sensitivity of each wavelength to manufacture optical sensors with the same performance, the sensitivity of multiple wavelength measurement units in the diffraction type optical sensor varies due to the positional variation of the diffraction grating and the detector. In contrast, as in the exemplary embodiment of the present invention, by including an optical sensor array for detecting a transmitted light signal and a transmitted background signal in the transmission method, calibration can be easily performed based on the sensitivity test results of each wavelength.

Furthermore, by mass-producing optical sensors with the same sensitivity at every wavelength, the same algorithm can be used for process monitoring at multiple semiconductor or display manufacturing facilities.

Furthermore, since the optical sensor array can be easily mounted and removed from the mounting module, it can be used selectively and can be slit mounted to minimize mounting errors and improve ease of removal.

The above are specific embodiments of the present invention and the technical means used. Many changes and modifications can be derived from the disclosure or teaching of this article, which can still be regarded as equivalent changes made to the concept of the present invention. The effects produced still do not exceed the essential spirit covered by the instructions and drawings, and should be regarded as within the technical scope of the present invention. It is appropriate to state in advance.

In summary, based on the content disclosed above, this invention can indeed achieve the intended purpose of the invention and provide a process monitoring system for plasma devices, which is extremely practical and valuable for industrial use. Therefore, an invention patent application is filed in accordance with the law.

100:Optical sensor array

110: First optical sensor

111: Optical signal band transmission filter

112: First optical detector

120: Second optical sensor

121: Background signal with transmission screening program

122: Second optical detector

200:Signal processor

PS: Plasma device

OS1: emits optical signals

OS2: Transmitted optical signal

BS1: Background signal

BS2: Transmitted background signal

FIG1 is a schematic diagram of a process monitoring system for plasma devices of the present invention; FIG2 is a schematic diagram of the optical sensor array of FIG1; FIG3 is a graph of the intensity of the emission signal and the filter transmittance according to the wavelength used in the optical sensor array of FIG1; FIG4 is a graph of a method for detecting a transmitted optical signal and a transmitted background signal using the optical sensor array of FIG1; FIG5 is a graph of a method for measuring only the intensity of a pure emission optical signal using the signal processing of FIG1; FIG6 is a schematic diagram of a process monitoring system for plasma devices according to another exemplary embodiment of the present invention; FIG7 is a graph showing a method for removing infrared background signals in FIG6; FIG8 is a schematic diagram of a process monitoring system for a plasma device according to another exemplary embodiment of the present invention; FIG9 is a schematic diagram of the optical sensor array of FIG8; FIG10 is a perspective view of the optical sensor array and signal processor of FIG1 equipped to a device module.

100:Optical sensor array

110: First optical sensor

111: Optical signal band transmission filter

112: First optical detector

120: Second optical sensor

121: Background signal with transmission screening program

122: Second optical detector

200:Signal processor

PS: Plasma device

OS1: emits optical signals

OS2: Transmitted optical signal

BS1: Background signal

BS2: Transmitted background signal

Claims (19)

A process monitoring system for a plasma device includes: an optical sensor array configured to detect a transmitted optical signal and a transmitted background signal from an emitted optical signal and a background signal emitted by a plasma, respectively; and a signal processor connected to the optical sensor array and configured to measure the intensity of a pure emitted optical signal by removing the transmitted background signal from the transmitted optical signal; wherein the transmitted optical signal is transmitted through an optical signal band transmission filter, and the transmitted background signal is transmitted through a background signal band transmission filter. A process monitoring system for a plasma device as described in claim 1, wherein the optical sensor array comprises: at least one first optical sensor configured to detect the transmitted optical signal; and at least one second optical sensor configured to detect the transmitted background signal. A process monitoring system for a plasma device as described in claim 2, wherein the first optical sensor comprises: the optical signal band transmission filter, configured to transmit the transmission optical signal from the emission signal, the transmission optical signal being the emission optical signal in the emission optical signal band; and a first optical detector, configured to detect the transmission optical signal, the transmission optical signal transmitting the optical signal band transmission filter. A process monitoring system for a plasma device as described in claim 2, wherein the second optical sensor comprises: the background signal band transmission filter, configured to transmit a transmission background signal as a background signal in a background signal band from the emission signal; and a second optical detector, configured to detect the transmission background signal, the transmission background signal transmitting the background signal band transmission filter. A process monitoring system for a plasma device as described in claim 2, wherein the emission optical signal includes a first emission optical signal having a light amount equal to or greater than a first reference value and a second emission optical signal having a light amount less than the first reference value, wherein the first optical sensor includes: at least one first optical signal optical sensor configured to detect a first transmitted optical signal from the first emission optical signal; and at least one second optical signal optical sensor configured to detect a second transmitted optical signal from the second emission optical signal. A process monitoring system for a plasma device as described in claim 5, wherein the sensitivity of the second optical signal optical sensor is greater than the sensitivity of the first optical signal optical sensor. A process monitoring system for a plasma device as described in claim 5, wherein the number of the second optical signal optical sensors is greater than the number of the first optical signal optical sensors. A process monitoring system for a plasma device as described in claim 5, wherein the first optical signal optical sensor comprises: a first optical signal band transmission filter configured to transmit a first emission optical signal from the emission optical signal; and a first optical signal detector configured to detect the first transmission optical signal transmitted through the first optical signal band transmission filter, wherein the second optical signal optical sensor comprises: a second optical signal band transmission filter configured to transmit a second emission optical signal from the emission optical signal; and a second optical signal detector configured to detect the second transmission optical signal transmitted through the second optical signal band transmission filter. A process monitoring system for a plasma device as described in claim 8, wherein the gain of the second optical signal detector is greater than that of the first optical signal detector. A process monitoring system for a plasma device as described in claim 2, wherein the background signal includes a first background signal having a light amount equal to or greater than a second reference value, and a second background signal having a light amount less than the second reference value, wherein the second optical sensor includes: at least one first background signal optical sensor configured to detect a first transmission background signal from the first background signal; and at least one second background signal optical sensor configured to detect a second transmission background signal from the second background signal. A process monitoring system for a plasma device as described in claim 10, wherein the sensitivity of the second background signal optical sensor is greater than the sensitivity of the first background signal optical sensor. A process monitoring system for a plasma device as described in claim 10, wherein the number of the second background signal optical sensors is greater than the number of the first background signal optical sensors. A process monitoring system for a plasma device as described in claim 10, wherein the first background signal optical sensor comprises: a first background signal band transmission filter configured to transmit the first background signal from the background signal; and a first background signal detector configured to detect the first transmission background signal transmitted through the first background signal band transmission filter, wherein the second background signal optical sensor comprises: a second background signal band transmission filter configured to transmit the second background signal from the background signal; and a second background signal detector configured to detect the second transmission background signal transmitted through the second background signal band transmission filter. A process monitoring system for a plasma device as described in claim 13, wherein the gain of the second background signal detector is greater than that of the first background signal detector. A process monitoring system for a plasma device as described in claim 1, wherein the signal processor is configured to remove a transmission background signal measured together with the plasma emission signal at the first optical sensor by calculating the first optical sensor signal and the second optical sensor signal. The process monitoring system for a plasma device as described in claim 15 further comprises: an infrared background signal detector connected to the signal processor and configured to detect an infrared background signal emitted from the infrared heater. A process monitoring system for a plasma device as described in claim 16, wherein the signal processor is configured to remove the infrared background signal detected by the infrared background signal detector from the transmitted optical signal. The process monitoring system for plasma devices as described in claim 1 further includes: an equipment module, in which the optical sensor array and the signal processor are equipped. A process monitoring system for a plasma device as described in claim 18, wherein the device module has a chamber shape extending in a certain direction and has a slit, and the optical sensor array is selectively mounted at the slit.