TWI633575B - Plasma processing device for monitoring technology process and monitoring plasma treatment Technical process approach - Google Patents

Abstract

The invention discloses a plasma processing device for monitoring technology process and a method for monitoring plasma processing technology. The apparatus includes a plasma reaction chamber for processing a substrate and a monitoring device for monitoring the substrate processing process, the monitoring device including an incident light source for emitting a pulsed optical signal to the surface of the substrate in the plasma processing apparatus; And acquiring, by the second pulse frequency, the optical signal emitted in the reaction cavity; the second pulse frequency is greater than or equal to twice the frequency of the first pulse, so that the spectrometer collects at least two in an incident pulse optical signal period. The data processing device is connected to the spectrometer for calculating the optical signal collected by the spectrometer to eliminate the influence of the background light signal generated by the plasma in the reaction chamber on the reflected optical signal.

Description

Plasma processing device for monitoring technology process and monitoring plasma treatment Technical process approach

The present invention relates to the field of plasma technology processing technologies, and in particular, to a technical field for monitoring a plasma processing process.

Plasma processing technology is widely used in semiconductor fabrication technology. In the process of depositing or etching a semiconductor substrate, the technical process needs to be closely monitored to ensure that the deposition technique or etching technique results are well controlled. One commonly used etching technique control method is optical emission spectroscopy (OES). After an atom or molecule in the plasma is excited by an electron to an excited state, a specific wavelength of light is emitted during the return to another energy state. The wavelengths of light waves excited by different atoms or molecules are different, and the change of light intensity of light waves reflects the change of atomic or molecular concentration in the plasma. OES is a characteristic line (OES characteristic line) of a plasma that is capable of reflecting changes in the plasma etching process and closely related to the chemical composition of the plasma, and instantly detects the change in the intensity of the characteristic line signal. Providing information on the reaction conditions in the plasma etching technique, the limitation of this method is that only the state after the completion of the thin film etching can be monitored, and only when an etched target layer is etched, the plasma is etched to the lower side. When a target layer is present, the characteristic line of the corresponding plasma will change significantly, so this method can only be used for the end point monitoring of the etching technology.

With the increasing density and complexity of device integration in integrated circuits, strict control of semiconductor technology processes is particularly important. For sub-deep-micron polysilicon gate etching technology, since the thickness of the gate oxide layer has become very thin, how to accurately control the plasma etching process is a technical challenge. High-density plasma etching machines currently used in the semiconductor industry, such as inductively coupled plasma (ICP) sources, capacitively coupled plasma (CCP) sources, and electron spin resonance plasma (ECR) sources. The plasma generated by the plasma has a high etching rate. If the technical control is unreasonable, excessive etching may easily cause damage to the next layer of material, thereby causing device failure. Therefore, some parameters in the etching process, such as chemical gases for etching, etching time, etching rate, and etching selectivity, must be strictly controlled. In addition, subtle changes in the state of the etch machine, such as gas flow rate in the reaction chamber, temperature, gas reflow status, or differences between wafers between batches and batches, can affect the control of the etch parameters. Therefore, it is necessary to monitor the variation of various parameters during the etching process to ensure the uniformity of etching during the etching process. The Interferometric Endpoint Method (IEP) is designed to achieve instant monitoring of the etching process.

The interference end point method (IEP) is to incident an optical signal to the surface of the semiconductor substrate. After the incident optical signal is emitted by the semiconductor substrate, the information of the thickness variation of the substrate film is carried, and the wavelength of the reflected optical signal is measured, and according to the measurement. As a result of the analysis and calculation, the actual etching rate can be obtained, and the etching process of the substrate film can be monitored in real time. However, in the process of spectrum monitoring, the specific wavelength of the light emitted by the atoms or molecules in the plasma after being excited by the electrons to the excited state always exists, and the intensity is large, and sometimes even the intensity of the light signal emitted by the plasma exceeds The intensity of the incident light signal, the interference of the reading of the reflected incident light signal makes it difficult to measure the incident light signal.

In order to solve the above technical problems, the present invention provides a plasma processing apparatus for monitoring a process, comprising a reaction chamber for processing a substrate and a monitoring device for monitoring a substrate processing process, the monitoring device comprising: an incident light source, a pulse frequency emits incident pulse light to a surface of the substrate in the reaction chamber; a spectrometer acquires an optical signal emitted from the reaction chamber at a second pulse frequency; the second pulse frequency is greater than or equal to the first pulse frequency 2 times, the spectrometer collects at least two sets of optical signals during an incident pulse optical signal period, wherein one set of optical signals includes reflected light signals of incident light on the surface of the substrate and background light signals generated by plasma in the reaction chamber. And a set of optical signals only have a background light signal generated by the plasma in the reaction chamber; a data processing device for calculating the optical signal collected by the spectrometer to eliminate the background light signal pair generated by the plasma in the reaction chamber The effect of the reflected light signal; the data processing device uses the reflected light signal after the background light signal is removed as a meter Based on the calculation, the processing end point of the substrate is obtained.

Preferably, the second pulse frequency is 2 times the nth power of the first pulse frequency, and the n is greater than or equal to 1.

Preferably, the incident pulse light emitted by the incident light source is a full spectrum.

Preferably, the incident light source is a flash lamp.

Preferably, the pulse period of the incident pulse light is variable in size.

Preferably, the spectrometer is used to collect the wavelength and intensity of the optical signal in the plasma reaction chamber, and the spectrometer is a CCD image controller.

Preferably, the spectrometer emits a pulse signal to the incident light source to control a period during which the incident light source transmits an incident pulse optical signal.

Further, the present invention also discloses a method for monitoring a plasma processing technology process, the method being carried out in a plasma processing apparatus, the method comprising the steps of: placing a substrate in a reaction chamber of a plasma processing apparatus Internally, performing plasma processing on the substrate; transmitting a pulsed incident optical signal to the substrate, the incident optical signal is reflected on the substrate, and the pulse periodic frequency of the pulsed incident optical signal is a pulse frequency; collecting, by a spectrometer, a light signal emitted from the reaction chamber at a second pulse frequency, wherein the light signal comprises a reflected light signal of the incident light on the surface of the substrate and a background light signal generated by the plasma in the reaction chamber; Setting the second pulse frequency to be greater than or equal to twice the frequency of the first pulse; in a first pulse frequency cycle, the spectrometer acquires a sum of a set of reflected light signals and a background light signal generated by the plasma and at least a set of background light signals generated only by the plasma; the spectrometer transmits the collected optical signals to a data processing device, The data processing device subtracts the sum of the reflected light signal collected by the spectrometer and the background light signal generated by the plasma with a set of background light signals generated only by the plasma to obtain an undisturbed reflected light signal, and the data processing The device calculates the processing end point of the substrate based on the obtained undisturbed reflected light signal.

Preferably, the high potential of the spectrometer to collect the reflected light signal is different from the rising edge position of the incident light signal emitted by the incident light source.

Preferably, the spectrometer collects the optical signal at a frequency twice the frequency of the incident optical signal. During an incident optical pulse period, the spectrometer includes two collected optical signal periods, wherein the reflected light is collected in the first period. Signal and background light signal generated by the plasma And the second period only collects the background light signal generated by the plasma, and the optical signal collected in the first period and the optical signal collected in the second period are subtracted to eliminate the background light signal to the reflected light signal. interference.

Preferably, when the frequency of the optical signal collected by the spectrometer exceeds twice the frequency of the incident optical signal pulse, the spectrometer collects a plurality of sets of background light signals generated by the plasma only during an incident optical pulse period. The data processing device selects one of the background optical signals and the sum of the reflected optical signals collected by the spectrometer and the background optical signals generated by the plasma to perform subtraction to eliminate the interference of the background optical signals on the reflected optical signals.

Preferably, the incident light signal is a full spectrum signal.

Preferably, the spectrometer selects an optical signal having a preset wavelength for signal acquisition.

Preferably, the incident source emits a high energy pulse of microsecond duration.

Preferably, the data processing device is a computer system.

The invention has the advantages that: selecting an incident light source that continuously emits pulsed light as an active light source to emit pulsed incident light of a first frequency to a surface of the substrate in the reaction cavity, and setting a frequency of collecting the optical signal in the reaction cavity by the spectrometer is greater than or equal to the first Double the frequency. That is, in a pulsed incident light illumination period, the spectrometer collects at least two optical signals, one of which collects the sum of the reflected light signal and the background light signal, and the rest only collects the background light signal, and the collected reflected light signal and the background light are collected in each cycle. The sum of the signals minus the background light signals collected can obtain the reflected light signals after the interference is removed. The invention adopts the flash lamp with continuous emission pulse type optical signal as the incident light source to avoid frequent mechanical switching of the incident light source and reduce the mechanical damage of the incident light source; meanwhile, since the flash emits incident light for less than one pulse period per pulse period The time that the incident light source controlled by the mechanical switch emits incident light in one cycle can prolong the effective illumination time of the incident light source and improve the service life of the incident light source. In addition, the present invention uses a flash lamp as the incident light source to provide full-spectrum incident light, and the full-spectrum incident light allows the user of the plasma processing apparatus to have more wavelength range options. At the same time, the flash can emit a high-energy optical signal with a short duration according to a certain period, which can ensure that the intensity of the reflected light signal received by the spectrometer is large enough, and the continuous illumination time of the incident light source can prolong the service life of the light source and reduce the spectrometer. The time for integrating the collected optical signals improves the computational efficiency. The optical signals collected by the spectrometer can process operations in real time, improving accuracy and efficiency.

100‧‧‧ Plasma processing unit

10‧‧‧ substrates

102‧‧‧ incident light source

103‧‧‧Light signal entrance

104‧‧‧ Spectrometer

111‧‧‧ Plasma

114‧‧‧Data processing device

1 is a schematic structural view of a plasma processing apparatus in which an interference end point monitoring device is provided; FIG. 2 is a view showing an operation pulse signal of an incident light source and a spectrometer; and FIG. 3 is another plasma processing apparatus in which an interference end point monitoring device is provided. Schematic.

In order to make the content of the present invention clearer and easier to understand, the contents of the present invention will be further described below in conjunction with the accompanying drawings. Of course, the invention is not limited to the specific embodiment, and general replacements well known to those skilled in the art are also encompassed within the scope of the invention. need It is noted that the drawings are in a very simplified form, using a non-precise scale, and are only used to facilitate the purpose of assisting the description of the embodiment.

1 is a schematic view showing the structure of a plasma processing apparatus in which an interference end point monitoring device is provided. In FIG. 1, a semiconductor substrate 10 is placed inside a plasma processing apparatus 100, and a reaction gas introduced into a reaction chamber of the plasma processing apparatus 100 is dissociated into a plasma 111 by a radio frequency power applied to the plasma processing apparatus 100. The plasma 111 etches the substrate 10. The substrate 10 usually includes a plurality of layers to be etched, and different reactive gases and etching parameters are required to etch different films. The plasma 111 emits light signals of different wavelengths during the etching of different films. These optical signals are used as background light signals and continue to exist during the etching process.

In the apparatus and method for monitoring the plasma processing process by the Interference End Point Method (IEP) disclosed herein, an interference end point monitoring device is provided for performing end point monitoring of the plasma processing apparatus 100. The interference end point monitoring device includes an incident light source 102 and a spectrometer 104. An optical signal inlet and outlet 103 is disposed on the top wall of the plasma processing apparatus 100 for allowing the optical signal emitted by the incident light source 102 to enter the plasma processing apparatus. The surface of the substrate is allowed to enter the spectrometer 104 disposed outside the plasma processing apparatus 100. The specific working principle is that after the incident light source 102 emits the incident light signal to the surface of the etched film, the light reflected from the upper surface of the film interferes with the light reflected by the lower layer material after penetrating the film. Since the film thickness determines the optical path difference of the two lights that interfere with each other, different optical path differences form alternating interference fringes. Therefore, as the etching process progresses, the film is continuously etched and thinned, and the interference enhancement can be obtained under the condition that Δd satisfies the following formula: Δd=λ/2n

Where λ is the wavelength of the incident light signal, n is the refractive index of the film material, and Δd is the change in the thickness of the film being monitored. Each time a change in Δd occurs, a maximum intensity of light is shown on the spectrometer 104. . As the thickness of the film continues to decrease, a number of sinusoidal signal curves are formed. Under the premise that the wavelength and refractive index of the incident light signal are known, the thickness variation Δd of the film to be monitored can be calculated. According to the sine wave signal curve received by the spectrometer, a period of interference enhancement can be obtained, and the monitoring is performed. The actual etch rate in the etching technique can be calculated by varying the thickness Δd of the film and a period in which the thickness variation occurs. The time required to reach the end of the etch can be calculated on the premise that the overall thickness of the etched film is known.

During the monitoring process, the intensity of the background light signal emitted by the plasma in the reaction chamber is large, and sometimes even exceeds the intensity of the light signal reflected by the incident light on the substrate film. Since the incident light and the background light signal are full spectrum light. Signal, when the spectrometer is set to collect the optical signal of a certain wavelength, the optical signal collected by the spectrometer 104 is the sum of the reflected optical signal and the background optical signal of the wavelength, and the etching rate cannot be calculated as described above, in order to avoid the spectrometer When receiving the film 10 to reflect the optical signal, the substrate 10 is affected by the background light signal emitted by the plasma 111 to ensure that the spectrometer 104 can accurately read the incident light signal. The present invention needs to eliminate the interference of the background light signal.

2 is a graph showing the working pulse signal of the incident light source 102 and the spectrometer 104, wherein the first graph shows the light intensity of the reflected light signal and the background light signal emitted in the plasma reaction chamber of the present invention, and the second graph A schematic diagram of the pulse period of the optical signal collected by the spectrometer 104 in the reaction chamber is shown. The present invention selectively sets the incident light source 102 to be a light source that emits a short-lived high-energy light pulse. For example, a flash lamp having a full spectrum, the flash lamp emits light in each pulse period for a very short time, usually in the order of microseconds. In the first graph, by The duration of the reflected light signal in each period is extremely short, and the transient optical signal can be transmitted at a time point. Therefore, the intensity of the reflected light signal in each period is expressed as a vertical line segment with a certain interval, and the vertical straight line segment The length of the pulse reflects the intensity of the pulsed light signal, and the interval between the two segments represents the period of the pulsed incident light signal. The background light signal emitted by the plasma persists throughout the plasma technology, and the range of light intensity changes is small, which is expressed as a roughly smooth curve. For convenience of description, the pulse frequency of the incident light source 102 is referred to as a first pulse frequency. During the pulse period of each incident light source 102, there is only a very short time in the reaction cavity for the reflected light signal, and only the background light is available for the rest of the period. The signal exists. The second graph of FIG. 2 shows a schematic diagram of a pulse period in which the spectrometer 104 collects the optical signals in the reaction chamber. When the pulse signal is at a high potential, the spectrometer 104 collects the optical signals in the reaction chamber and transmits the collected optical signals to the data. The data processing is performed in the processing device 114. For convenience of presentation, the frequency at which the spectrometer 104 collects the optical signal is referred to as the second pulse frequency. In order to achieve the object of the present invention, the second pulse frequency is greater than or equal to twice the frequency of the first pulse, that is, during an incident light pulse period, the spectrometer 104 performs at least two signal acquisitions on the optical signals in the reaction chamber, one of which is collected. The incoming optical signal includes the sum of the reflected optical signal and the background optical signal, and the other collected optical signals only have the background optical signal. The spectrometer 104 transmits the acquired optical signal intensity to the data processing device 114 connected thereto, and the data processing device 114 calculates the sum of the reflected optical signal and the background optical signal collected by the spectrometer 104 in each incident optical period and the background optical signal. The difference is further obtained as the intensity of the reflected light signal reflected by the incident light on the substrate 10 during each incident photoperiod. To eliminate the influence of the background light signal on the calculation of the substrate etch rate.

In the present invention, the incident light source 102 is connected to a device for controlling the light-emitting frequency of the incident light source 102, and the pulse-trigger device for controlling the light-emitting frequency of the incident light source 102, the pulse touch The transmitting device can control the pulse frequency of the incident light source 102. The period in which the pulse incident light source 102 emits the incident light signal can be set in various manners. For example, the flash lamp used in the present invention can periodically emit the incident light signal for more flexibility. For adjusting the period of the incident light signal, as shown in FIG. 3, the spectrometer 104 transmits a pulse signal to trigger the illumination period of the incident light source while collecting the optical signal in the reaction cavity. In the embodiment shown in FIG. 3, the illumination frequency of the incident light source 102 and the frequency of the collected optical signal are both controlled by the spectrometer 104, thereby enabling more accurate control of the spectrometer 104 in the reaction chamber during an incident light pulse period. The optical signal is collected at least twice.

In the present invention, the acquisition frequency of the spectrometer 104 is at least twice the frequency of the incident optical period to acquire both the sum of the reflected optical signal and the background optical signal in one incident optical period, and the non-reflected optical signal only has the background optical signal. Light intensity. 2 shows the case where the acquisition frequency of the spectrometer 104 is exactly twice the periodic frequency of the incident light. In another embodiment, the acquisition frequency of the spectrometer 104 can be 2 times the power of the incident optical cycle frequency. The spectrometer 104 can collect more than one set of background light signals only during an incident light pulse period, and select any group and the collected background light signal intensity and the spectrometer to collect the reflected light signal intensity and the background light signal. The sum of the light intensities is subtracted to obtain the intensity of the reflected light signal. Since the incident optical signal is close to the transient pulse at a certain time point, in order to prevent the signal acquisition of the optical signal from the spectrometer 104 from being at the rising edge, the signal acquisition is unstable. Preferably, the incident optical signal and the spectrometer 104 collect the optical signal. The potentials have different rising edges.

Compared with the periodic opening and closing of the incident light source to enable the spectrometer 104 to acquire the pulsed reflected light signal, the present invention uses the flash lamp that continuously emits the pulsed optical signal as the incident light source to avoid frequent mechanical switching of the incident light source. Reduce incidence The mechanical damage of the light source; at the same time, since the time during which the flash emits the incident light in each pulse period is shorter than the time when the incident light source controlled by the mechanical switch emits the incident light in one cycle, the effective illumination time of the incident light source can be prolonged, and the incident light source can be improved. The service life. In addition, the present invention uses a flash lamp as the incident light source to provide full-spectrum incident light, and the full-spectrum incident light allows the user of the plasma processing apparatus to have more wavelength range options. At the same time, the flash can emit a high-energy optical signal with a short duration according to a certain period, which can ensure that the intensity of the reflected light signal received by the spectrometer is large enough, and the continuous illumination time of the incident light source can prolong the service life of the light source and reduce the spectrometer. The time for integrating the collected optical signals improves the computational efficiency. The optical signals collected by the spectrometer can process operations in real time, improving accuracy and efficiency.

The spectrometer 104 transmits the sum of the reflected light signal intensity and the background light signal intensity collected by each incident light signal period and the background light signal intensity to the data processing device connected thereto, and is passed through the data processing device 114. The subtraction operation is performed to obtain a reflected light signal after the incident light source 102 is reflected on the film of the substrate 10. By setting the incident light source 102 to continuously emit the pulsed incident light signal, the background light signal can be removed, leaving only the reflected light signal on the substrate film useful for monitoring the etching technique, by reading the wavelength of the reflected light signal and According to the formula described above, the actual etching rate of the film of the substrate 10 inside the plasma processing apparatus 100 can be obtained, thereby accurately monitoring the etching process of the substrate film. The data processing device is a computer system.

The period in which the pulse incident light source 102 of the present invention emits an incident light signal can be set in various manners. For example, the flash lamp used in the present invention can periodically emit an incident light signal, and the cycle of the incident light signal can be adjusted more flexibly. As shown in Figure 3, The spectrometer 104 delivers a pulse signal that triggers the illumination period of the incident source. The triggering of the incident light source 102 in the manner shown in FIG. 3 can effectively control the relationship between the reflected light signal period and the period of the optical signal collected by the spectrometer, thereby realizing accurate collection of the optical signal by the spectrometer.

The IEP of the present invention can monitor the deposition process in addition to the etching technique. Unlike the etching technique, the deposition technique is a process in which the thickness of the film is continuously increased, by projecting into the deposition reaction chamber. The incident light signal, according to the above description, can be used to calculate the deposition rate of the deposition technique, and the end point of the deposition technique can be accurately known based on the accurate deposition rate and the thickness of the film to be deposited.

The present invention has been disclosed in the above preferred embodiments, and is not intended to limit the scope of the invention, and it is possible to make possible changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the scope defined by the scope of the invention.

Claims (15)

A plasma processing apparatus for monitoring a process, comprising a reaction chamber for processing a substrate and a monitoring device for monitoring a substrate processing process, wherein the monitoring device comprises: an incident light source, the first pulse frequency is directed into the reaction chamber The surface of the substrate emits incident pulsed light; a spectrometer acquires an optical signal emitted from the reaction chamber at a second pulse frequency; the second pulse frequency is greater than or equal to twice the frequency of the first pulse, so that the spectrometer is at an incident pulse At least two sets of optical signals are collected during the optical signal period, wherein one set of optical signals includes the sum of the reflected light signals of the incident pulse light on the surface of the substrate and the background light signals generated by the plasma in the reaction chamber, and the set of optical signals only has the reaction. a background light signal generated by the intracavity plasma; the incident light signal of the incident light source has a different rising edge from the high potential of the optical signal collected by the spectrometer; the spectrometer transmits a pulse signal to trigger the illumination period of the incident light source; Processing device for calculating the optical signal collected by the spectrometer to eliminate the plasmon in the reaction chamber The influence of the background light signal generated by the daughter on the reflected light signal; the data processing device uses the reflected light signal after the background light signal is removed as a calculation basis to obtain the processing end point of the substrate. The plasma processing apparatus of the monitoring technology process of claim 1, wherein the second pulse frequency is 2 times the nth power of the first pulse frequency, and n is greater than or equal to 1. The plasma processing apparatus of the monitoring technology process of claim 1, wherein: the incident pulse light emitted by the incident light source is a full spectrum. The plasma processing apparatus of the monitoring technology process of claim 1, wherein the incident light source is a flash lamp. The plasma processing apparatus of the monitoring technology process of claim 1, wherein the pulse period of the incident pulse light is variable. The plasma processing apparatus of the monitoring technology process of claim 1, wherein the spectrometer is configured to collect the wavelength and intensity of the optical signal in the plasma reaction chamber, and the spectrometer is a CCD image controller. The plasma processing apparatus of the monitoring technology process of claim 1, wherein the spectrometer emits a pulse signal to the incident light source to control a period during which the incident light source transmits the incident pulse optical signal. A method of monitoring a plasma processing technique, the method being carried out in a plasma processing apparatus, wherein the method comprises the steps of: placing a substrate in a reaction chamber of the plasma processing apparatus, the substrate Performing a plasma technology process; an incident light source emits a pulsed incident light signal to the substrate, the incident light signal is reflected on the substrate, and the pulse periodic frequency of the pulsed incident light signal is a first pulse frequency; The spectrometer collects the optical signal emitted from the reaction chamber at a second pulse frequency, and the optical signal includes a reflected light signal of the incident light on the surface of the substrate and a background light signal generated by the plasma in the reaction chamber; the incident light of the incident light source Signal and the The high potential of the optical signal collected by the spectrometer has different rising edges; the spectrometer transmits a pulse signal to trigger the illumination period of the incident light source; and the second pulse frequency is set to be greater than or equal to twice the frequency of the first pulse; During a pulse frequency period, the spectrometer acquires a sum of a set of reflected light signals and a background light signal generated by the plasma and at least one set of background light signals generated only by the plasma; the spectrometer transmits the collected optical signals to a data. a processing device that subtracts a sum of a set of reflected light signals collected by the spectrometer from a background light signal generated by the plasma with a set of background light signals generated only by the plasma to obtain an undisturbed reflected light signal And the data processing device calculates the processing end point of the substrate according to the obtained undisturbed reflected light signal. The method for monitoring a plasma processing technology process according to claim 8 , wherein the high level of the reflected light signal of the spectrometer is different from the rising edge position of the incident light signal emitted by the incident light source. The method for monitoring a plasma processing technology according to claim 8 , wherein: the spectrometer collects the optical signal at a frequency twice the frequency of the incident optical signal, and the spectrometer includes two in an incident optical pulse period. Collecting the optical signal period, in which the sum of the reflected light signal and the background light signal generated by the plasma is collected in the first period, and the background light signal generated by the plasma is collected only in the second period, and the light collected in the first period is collected. The signal and the optical signal collected in the second period are subtracted to eliminate the interference of the background optical signal on the reflected optical signal. The method for monitoring a plasma processing technology according to claim 8, wherein: the spectrometer collects the optical signal at a frequency exceeding twice the frequency of the incident optical signal, and the spectrometer is in an incident optical pulse period. Collecting a complex array only has a background light signal generated by the plasma, and the data processing device selects a set of background light signals and a sum of the reflected light signals collected by the spectrometer and the background light signals generated by the plasma to perform subtraction to eliminate the background light. The interference of the signal on the reflected light signal. The method of monitoring plasma processing technology according to claim 8 , wherein the incident light signal is a full spectrum signal. The method for monitoring plasma processing technology according to claim 8 , wherein the spectrometer selects an optical signal having a preset wavelength for signal acquisition. A method of monitoring a plasma processing technique as described in claim 8 wherein: the incident source emits a high energy pulse of a microsecond duration. The method for monitoring a plasma processing technology process according to claim 8, wherein the data processing device is a computer system.