TWI317539B - End point detection in time division multiplexed etch process - Google Patents

Description

1317539 发明, DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates generally to the field of semiconductor manufacturing. More particularly, the present invention is directed to an improved method of detecting the end of an etch and deposition process for a time-sharing division _1 tiplexed). Cross-reference to the relevant application This application is related to the US-issued US Provisional Patent Application No. 6〇/447, 594 proposed by Us Lu Zhishan Dingyue in February 2003 and sovereignty, titled: Time-sharing In the multiplexed etching process, the zebra gamma & endpoint detection, this provisional patent application is incorporated herein by reference. [Prior Art] During the production of many _s devices, the material of the etch-layer is required to complete the layer that stops at the bottom (for example, the insulator on the silicon chip (s〇i si 1 iC〇n-〇n-insulator) That is, it removes the KSi) layer which stops at the lower layer of the dioxide layer. Allowing the engraving process to proceed beyond the time when the first layer has been removed will result in a reduction in the thickness of the underlying stop layer, or a degradation of the characteristic profile (profUe) (needle_s〇I application is based on this technique) Called "notching"). One method commonly used to detect the end of electrical destruction process is optical specptical emission spectrometry. 〇 0ES analyzes the light emitted by an electrical source to induce its effects on the chemical and physical states of the electrical destruction process. In semiconductor processing, this technique is commonly used to integrate the material interface during the electro-acoustic process. One of the themes discussed in the optical precision technology of plasma processing, is proposed - excellent! 317539 Yue commented on the principle and application of plasma emission spectroscopy technology. The OES technology involves monitoring the radiation emitted by the plasma, typically in the uv/m(10)(10) to 11 GGnm portion of the spectrum. Figure 1 shows a schematic diagram of a typical GES architecture. The composition of the electrode (and especially the presence of reactive etching species or etching by-products) is determined by the spectrum of the radiation emitted (i.e., intensity versus wavelength). During the course of an etching process (and especially for a material transition), the composition of the electrode changes and causes a change in one of the radiation spectra. By continuously monitoring plasma emissions, a 终点es endpoint system may detect a change in one of the emission spectra and use it to determine when the film has been completely removed. In practice, most of the information about the endpoint is typically contained within a few wavelengths that correspond to the reactants consumed during the remainder or the resulting by-products of the etch. One common method for developing an OES endpoint strategy is to collect multiple spectra of plasma radiation during the conditions before and after the endpoint. These light schemes can be used to identify wavelength regions for candidates for the process. The candidate region contains wavelengths that exhibit significant intensity changes as the process reaches a transition between two related materials. The endpoint wavelength candidate region can be determined using a variety of methods. Spectral regions for endpoint detection can be selected by statistical methods, such as factor analysis or principal component analysis (see U.S. Patent No. 5,658,423 to Angell et al.). Another strategy for determining the candidate for the endpoint is to construct a difference between the spectra before the end (primary etch) and after the end point (over etched). Once the candidate regions have been selected, the designation of similar chemical species can be made for the candidate regions (i.e., 1317539 species, or surname products) from the reactants of the free gas leader. The seven-plate Pe bottle and other people's "spectral line graph" ', the identification of the knife spectrum, the multiple references, the knowledge related to the process chemicals are similar to the species identifier. Needle oblique production ^Uine; ^ in one of the eight bismuth sulphur (SF6) plasma, Shi Xi (Si) surname engraving process similar to the end of 687 ... 〇 3nm of fluorine (F: choose one of the examples will be The cesium fluoride (SiF) band at 440 nm. Once these areas are secondary, the subsequent parts can be processed using the same OES strategy. Although these OES methods are quite suitable for single use. The process of stepping is either a process with a finite number of discrete etching steps (such as an etch start followed by a major etch), recording the OES to a fast and periodic plasma disturbance. The process is difficult. The examples of such processes are those that are time-multiplexed, as disclosed in U.S. Patent No. 4,985,114, issued to U.S. Pat. This %• author reveals a TDM system is, ra.. I private, using an alternating set of etching and deposition steps to name the high aspect ratio to Si. The 2a-e diagram shows the schematic representation of the TDM etching process Figure τ (10) etching process is typically implemented in a reactor, the composition of which is typically One is to apply one of the high-density electro-convergence sources of ICP (Inductively Coupled Plasma) and is related to the substrate electrode of RF (10), radio freQuency. For Si, the most common process gas system used in the engraving process is Stan (Sf6) and octafluoride (carbon). The typical use of % is the gas of the surname, while the c4f8 is typically used as the deposition gas. During the engraving step, the SF6 system contributes to the spontaneous and isotropic nature of the dream (4) (Fig. 1317539); in the deposition step, the c, 8 system contributes to the deposition of protective polymers in the structure of the surname. Side wall and bottom (Fig. 2(c)). The process system = between the surname and the deposition process step, so that a high aspect ratio of ^ can be defined in the - behind the mask. In high energy and directional bombardment (which is present in the etching step) 'the polymer film system at the bottom of the structure etched by the previous deposition step will be removed to expose the 1 surface for the step-by-step (4) 2 (4) Figure). The poly-materials on the sidewalls = = hold 'because they are not subjected to direct ion bombardment to prohibit lateral use. The TDM theory allows high aspect ratios to be characterized by a high rate of (iv) substrate. The f 2(e) diagram shows a transverse W electron microscope (SEM, scannlng electr〇n micr〇sc〇pe) image of the 矽 structure. = Significantly different from the electron emission spectrum of the deposition step, due to the different battery conditions in the deposition and engraving steps (see 3: ε = body type, pressure, RF power, etc.). Should; = period (figure 4). The Zhou Shixi re-environment creates a trajectory of the end point, which is what Zhou expects to be the etch segment of the majority of the information. Take -=: wide (the method of the end point information of the plasma radiation of the US patent ^^ = two TM process. One line to == two in the supply trigger (which is typically the self-(four) step, history only view During the etching step, the second of the electric f-= (for the ~ and typically the fluorine or the two, using a trigger and connected to a sample and hold circuit, the radiation observed in the subsequent etching step of 1317539) The strengths can be combined to obtain a non-periodic-radio signal. The radiation intensity values are maintained at the last known value during the subsequent deposition step for each etching step. The sexual radio signal is converted to a curve similar to the step function, which can be applied to the process end point decision. The limitation of this theory is the need for an external supply (4). In addition, it is necessary to trigger and obtain each moment. A user input delay between the radiological data during the step. : erde et al. (U.S. Patent No. 4,491,499), the effort to improve the sensitivity of the 〇ES method reveals that measuring one of the narrow bands of the radio spectrum and simultaneously measuring its center The strength of the wider background band around one of the narrow bands. In this way, the signal can be subtracted from the end signal to cause a more accurate value of the narrowband signal. The frequency component of the plasma emission spectrum. Buck et al. (U.S. Patent No. 6,1,4, 487, the illusion describes the use of digital signal processing techniques such as Fast Fourier Transform (FFT) to obtain plasma emission spectra. Frequency components. Buck reveals that these separations provide information about changes in plasma conditions and can be used to detect changes in substrate material while allowing etch endpoint detection. Buck reveals that it drops to 10 The frequency outside the Hz audio. Buck considers that the frequency of the monitoring will change for different processes; however, it only considers the steady-state (single-step) process, and the application is related to its periodicity and repetitiveness. The FFT optical radiation system of the time division multiplexing (TDM) process is not disclosed.

Kornblit et al. (U.S. Patent No. 6, 〇 21, 215) also describes the use of the Fu π ± Deli transform coupled to the first-class radioactivity spectrum of 1317539. The Kornblit system reveals the simultaneous use of all frequency eight θ optical radiation m. However, D: Vld〇W et al. (U.S. Patent No. 6,455,437), which is not disclosed for the windowing process, also describes the frequency of the county that produces plasma radiation. a J head sheep knife and monitor the amplitude of the signal as time passes. Although Davidow 俜田万田 recognizes & 死, 夕 ° center and the multi-step process used to etch multilayer stacks, for TDM He Xi Xi Yueyue. * ^ Wang Zhiguan connected to the FFT optical radiation system is not revealed . In other words, by paying attention to which frequencies appear during the process to describe the Raytheon, instead of examining the characteristic frequencies imposed by the TDM loop properties on the process. 〇'NeUl et al. (US Patent No. 5, 308, 414) describes its application

The signal demodulation becomes an optical radiation preparation n, M element to the radiation system. The 〇NeUl system monitors the spectral region of one of its associated ''objects' and it will be used as a background correction - a wider spectral band. 〇'Nei i i also revealed that it is demodulated by the frequency of the signal using a lock-type amplifier. Lock-in amplifiers require an external synchronization signal. Hey, NeUi does not consider the = or TDM process. &

Sawm et al. (U.S. Patent No. 5,450,205) describes a system for determining the end of a process using an optical radiation interference technique (〇 . . pilcal emission mterferometry) associated with FFT. Relative to its optical emission spectroscopy (0ES), which analyzes plasma radiation, the radiation interference technique 2 is based on the plasma radiation reflected from the surface of the wafer to determine the film thickness on the wafer. Unlike OES, the 0EI technology department requires an imaging detector to have a clear line of sight on one of the recognizable circular surfaces. 〇Ε I Technology Department does not apply to Peng Cheng, 11 1317539 “There are repetitive deposition and etching steps due to the cyclic addition and removal of a passivation film with etch. 仃之疋' exists for TDM One of the end-point strategies of the pulping process: an external trigger to make the plasma radiology; the process steps are synchronized., I am [invention] A preferred embodiment of the present invention is directed to The second method of establishing an end point during the process of the anisotropic electric (four) engraving process is to use a concavity structure provided on the lateral boundary of the substrate by a photopolymer and through a (four) photomask. According to the method: a subsequent In the middle of the process, by contact with the reaction surface: : In addition to the material that violates the surface of the substrate and provides an exposed surface. The surface of Lu Xuan = is purified in a deposition step, which is exposed to The horizontal and vertical surface systems of the previous (four) steps are covered by a layer of purified PasS1Vatlon. The steps of the engraving and the purification steps are alternately repeated. The electrical destruction radiology is monitored in a specific wavelength or wavelength region and is a feature. Frequency 'its The nature of the TD" alternation is applied. The specific wavelength region is preferably based on one of the materials used during the process: the emission spectrum is determined. In another embodiment, the electrical stimulation is applied to two or more regions of the heart. The ratio (or other mathematical operation) of the size of the first wavelength region to the second or more wavelength regions is calculated. In this embodiment, - or a plurality of wavelength regions are selectable to represent Background signal. The applied characteristic process frequency is determined based on the sum of the duration of the surname step and the duration of the purification step. For a typical TDM process, the frequency of the process 12 1317539 is less than one time.

Hz. The process is interrupted because it depends on the monitoring step

The other month of the month is a method of implementing the life cycle of T> According to this kind of spectrum, a first meta-analysis of the spectrum is obtained... x 転 転 - plasma discharge λ long area identification. The sheep system applied by the (10)fj#-characteristic process frequency 仫·^ 4 M I耘 is also identified, and the plasma radiation long region is monitored for the first wave M h of the characteristic D process frequency. This feature is found in the continuation of the sum of the etching and deposition steps in the continuation of the 匍 匍 and the mountain. The identified Boxian+/ 疋 ❹ 系 is monitored during this process, : / 13⁄4 end. A second, regional system of the emission spectrum is also monitored.哕TDM _ " The number of wavelengths (1) (4) The end point is determined based on the wavelength regions of thousands, Q ^ such as: addition, subtraction or division. A fast 兮 兮 = = or a corresponding digital signal processing technology is used to resolve the oral system, the spectrum of the radio spectrum is eight denier. The end point of the 5 Hai I process is typically based on /, which occurs in the name of the music, I am a day, p q + ,, p 』B one material transformation. In this case, the wavelength region identified by the spectrum is based on a known spectral property of a material used in the TDM process. Yet another embodiment of the present invention is directed to a method of detecting a transition between different materials of a τ 跗 。. According to this method, the characteristic frequency of the process is recognized. The characteristic frequency of the process is based on the sum of the duration of the process of performing a part of the TDM process and the duration of the deposition process. The process-spectral radiation-area is monitored by the characteristic frequency to determine the transition between different materials. The transition occurs at one of the end points of the buttoning step in which one of the parties performing the TDM system is contending 13 !317539 depending on the TDM process. The area of the spectral emission monitored by the characteristic frequency is the known spectral characteristic of the material. [Embodiment] A preferred embodiment of the present invention is a multiplexed (TD Μ) avoidance τ r pair detection in a time division, by the transformation between the materials, the knife corresponding to the TDM At least one wavelength component of the electromagnetic radiation of the process. Collection of materials ::: The nature of the periodicity and repetition of the process, which is broad and has multiple characteristic frequencies associated with it. As an example, a two-step TM stone etch process is followed by a repeating multi-under two-four-second rhyme step and a six-second deposition 2 as shown in Table 1 below. |颂Λ颂Λ表1 sf6流4—- seem deposition 0.5 Ί Inscribed Too~~ A,; Fen County~~~~~--- seem —70 05 m -h —---- seem 40 40 — /7 RF ---- mtorr 22 23 ~~~~~ AVI Jyj Lift TPP r.-h Φ ------ 瓦"~~ 1 12 1000 1000 Steps "^ ~~- ——— - ____ 1 * h seconds ____ 4 6 ~~ -----^

The main idea is that the chemistry of the entanglement step is different from the chemistry of the etch step, the RF bias power = I force, resulting in a significantly different emission spectrum. Due to the tdm system, the complex nature and the duration of the deposition and etching steps, the process of the example of Table 1 has i. One of the cycles repeats the time and is therefore 14 1317539 II: the expected feature frequency. The sampling rate of the spectrum must be determined to accurately capture the plasma radiation (ai iQo; x ~ w don't be a no-mix)

Uliasmg). Therefore, the sampling frequency, B, is not required to be Nyquist and is preferably 1 times the expected characteristic frequency. For the purpose of: the first embodiment of the present invention ^ TD, good 〇 ES technology. In step 500, a system has at least __ characteristic frequencies, which are dependent on the duration of the system. The characteristic frequency system of the TDM process is typically less than 5 L1: the "at least one wavelength region of the emission spectrum (for electrical d is 200-1 1 00 nm) is identified for process endpoint prediction. In step 502, the spectral region The system is monitored during the process of the button engraving process. Since the radio signal used for the fixed TDM process is periodic and the repeated radio signal is resolved into a frequency component. In step 5〇4, at least two: the frequency component is in the process. The characteristic frequency is obtained. The method of obtaining the frequencies is based on the application of Fast Fourier Transform (FFT), although other digital signal processing (DSP) techniques can be used. If in step 5〇6 = Detect To determine a material transition, the method proceeds to step 5:8, wherein the method proceeds to the next process step or TDM sequence. If a material transition is not detected in step 5〇6, the method is Returning to the step wherein the plasma intensity of at least one of the spectral regions is monitored until a material is converted to detection. Relative to the prior disclosure of the OES by the FFT, monitoring the characteristic frequency of a TDM process The size of the radio signal, rather than being constant less than 5 Η?), provides a reliable method for detecting interlayer transitions during a TDM etch process. 15 1317539 Another embodiment of the present invention uses From the radioactive material, the long component of the material is used to improve the sensitivity of the final (four) measurement. At least one of the 2 / knife sets is one of the characteristic wavelengths of the TDM process. The other wavelength components are the signal. The second or the guest is the eight-eighth-eight-month method. It is a mathematical combination of the L-knife set (such as: addition, subtraction or division, eight; ', 1 application of greater sensitivity. J idea, the theory of the invention is not limited to a two-step cycle process. In general, the process is generally further divided: ^, further division into multiple sub-steps only results in additional characteristic frequencies applied by the process. It is also important to point out that 'in an etching step and a step Each repetitive process back to the L-step % parameter system does not need to be a maintenance = same cycle. For example, during the TM# engraving, the general = I process progresses and gradually changes the efficiency of the deposition or surname step to maintain the contour control (This technique is called process pattern ((10) in a morphological process, small parameters are changed to g)) process parameters between the steps. This # # Μ ; (5) _ or deposition step / number of 4 series including Limited to ··

Bias power, process pressure, minus eight ',, RF ^ 戍 source power (ICP' inducti source P〇wer, etc. These changes may also include: the duration of the various process steps within If the process is carried out: the time variation of the heliosphere is greater than the frequency resolution of the transformation, and the sum of the adjacent frequency components is monitored to correct the displacement. The process frequency applied by the processor is not a The preferred embodiment is the depth of the process of sf6/c4f8. Si is based on the preferred embodiment of the present invention. 16 1317539 can be utilized * regardless of the chemical, assuming a time-sharing multiple Ji (TDM) process is used. The method is also particularly useful for (iv) material conversion of other materials, such as: dielectric materials and metals, wherein a repetitive time division multiplexing (TDM) process system is utilized. To demonstrate one embodiment of the present invention Utilities, a TDM scheme utilizes wafers that are etched-on-insulator wafers (10). The program series is shown in Table 2 below. The following examples apply one embodiment of the present invention to a 3-step TDM crucible etch process. Table 2 Deposition of the surname A as engraved B at 6 flow rate seem 1 50 100 〇 ^ 8 flow rate seek 70 1 1 Ar flow rate seek 40 40 40 pressure millitorn 22 23 23 RF bias power watt 1 12 12 ICP power Step time watts 1500 1500 1500 seconds 6 3 7 shai and other inspection systems are executed in a commercial Unaxis Shuttlelock series of DSE (Deep Si 1 icon Etch) tools. The emission spectroscopy was collected at a frequency of 1 Hz using a commercial Unaxis Spectraworks radioactivity spectrometer. To determine the relevant wavelength region, a test wafer is etched and the plasma emission spectra in the deposition and etching steps are analyzed before and after the germanium layer has been removed (custom end point). Figure 6 is a graph showing the intensity versus wavelength of the plasma emission spectrum for the test wafer. The deposition spectrum 600 before the end point of the process, the deposition spectrum 600 after the end of the process, the deposition light 602 after the end of the process, the (four) (four) _ before the end of the process, and the rice-cut spectrum 606 after the end of the process are shown in the 6th M detector. The saturated 6() 8 is represented by the line at the top of the graph. Since a small amount of (4) is expected to be deposited in the process, the 7th figure is directed to the emission spectra 700 and 7〇2 before and after the fragmentation has been removed from the (4) step. Note that some 45 〇 (10) is close to the slight difference 704 of the etched spectrum. To determine the endpoint candidate, a point-by-p〇int differential spectroscopy is established. /Synthetic spectroscopy 8GG is shown in Section 8®. Candidates for the final speculation occurred at 440 nm and 686 nm. The 440 nm peak can be assigned to the fluorite (SiF) radiation (the surname product - reduced with Si removal), while the coffee (10) peak can be assigned to fluorine (F) radiation (reactant _ with si for removal) And increase). An endpoint strategy was established based on a 440 nm emission peak. Fig. 9 shows an enlarged view of the etched emission spectrum 9G2 before the end point and the etched emission spectrum 9G2 after the end point, which is closer to the 44 () nm peak. In order to reduce the associated noise, the two spectral regions 9〇4 〇9〇6 are monitored for background correction 'ie: a narrow @ 440 rnn peak (SlF radiation) compared to one centered around 445 nm Wide spectral area. ^ Figure 10 depicts the values for the two regions of time. Although there is a slight decrease in peak-to-peak value of the oscillation signal as the etching progresses, it is difficult to determine a process end point. The 帛11 image is displayed in the first 〇 of the total I insect time in the range of 3〇〇 to 400 seconds. J ^ ^ / 思思, 汛 〈 <440 η 1100 and background (445 nm) 1102 regional system In the higher-strength deposition step 18 1317539 〇 4 and properly tracked each other, but close to the end of the 11 μ μ etching step and divergence to establish the ratio of the 440 nm signal to the 445 nm background, resulting in Figure 12 'where' in the button and deposition The large radiological changes between the steps have been eliminated and the resulting signal system is more representative of its progress. Note the nature of the periodicity and repetitiveness of the ratio signal 12〇〇 as shown in Figure 12. The thirteenth line is shown in the last name "The ratio signal (44 〇 (10) 8 趟 5 nm background) 13 〇〇 β Note, as shown in Figure i3, the decrease in the continuous peak height of nearly 600 seconds. The characteristic frequency of the trajectory shown in Fig. 13 is G.G6Hz. This scheme applies a frequency corresponding to "seconds, which is the sum of the time of the individual process steps of the cyclic process of Table 2. 〃Using - Fast Fourier Transform (FFT) to convert from time domain to frequency domain to Figure 13 The signal is caused by the power spectrum shown in the figure. The FFT calculation is based on a 128-element array, which is added to form an OES signal-expanding window as the process progresses. The frequency emphasized by the dot-shaped block is attributed to The periodicity and repetitive nature of the TDM process scheme is expected. The nth graph shows the amplitude of the FFT power spectrum at two points in the process. Note that the 0.06 Hz component has a large amplitude before the end point, and After the &amp; layer has been cleared, it is reduced to close to zero. The size of 八 八 eight times plotted in time is the end point trajectory of the process shown in Figure 16. The actual end time is determined by the curve. It is made in a variety of ways, including, but not limited to, simple thresholding or differential (4). The technology is well known to those skilled in the art. The embodiments discussed above allow the end of a TDM process to be accurate. 19 1317539 j: The depositional step and the emission spectrum of the etch are monitored at the privileged-characteristic frequency. The ability to accurately determine an end point of the process is such that the likelihood of = over-desired features is minimized or eliminated, and thus the "thickness of the layer" is reduced. Further, this technique is known as "cutting two temples: contours Downgrades are also minimized. Furthermore, the present invention is quite applicable to any plasma process of ":", "short-speed" and periodic plasma disturbances. The present invention is therefore a substantial improvement over the prior art. The present disclosure is included in the accompanying patent application. The knives included in the scope, as well as the above-mentioned instructors. Although the present invention is a preferred form of the degree of specificity, it should be understood that M, the preferred form = 2 shows that the content is merely for example and is constructed Details and parts, and S and configuration of many changes 4 Di and Fan Bshou. K匕 is taken without departing from the spirit of the present invention [Simple description] Figure 1 is a typical OES architecture Schematic; Figures 2(a) through 2(e) show a representative diagram of a TDM etch process. Figure 3 is a plot of deposition and etched emission spectra for an example of a dicing process; Figure 4 is for a An end point trace of an exemplary TM process; Figure 5 is an overview of one embodiment of the present invention, a modified OES technique for a needle TDM process; and Figure 6 shows a plot of intensity versus wavelength for which Confirming an embodiment of the present invention A test wafer; Figure 7 shows the etched 20 1317539 spectrum before and after the end of a cutting process; Figure 8 shows the difference spectrum of the etched spectrum for the 7. The etched emission spectrum before and after the winter point is shown in the figure;

Figure 10 shows the plot of the spectral intensity values versus time in the two spectral regions identified by the Q y diagram; the eleventh graph of the sec-second range is shown in the 蛐6 丨 six gentlemen~ 300 times of the time Figure 4 is a magnified view of the figure; Figure 12 is a plot of the ratio of the 440 nm signal to the number 443 in Figure 11; Figure 13; Figure 13 is the ratio signal shown in Figure 12 In the period of money engraving, Figure 14 is a diagram of the signal from the 13th to the frequency domain; Figure 15 is a plot of the frequency domain signal of Figure 14 before and after the end of the process; and &amp; Figure 16 of the frequency of the quantity is based on the 〇〇6 Ηζ part of the figure shown in Figure 15. [Main component symbol description] 6〇〇Precipitation spectrum before the end of the process 602 Deposition spectrum after the end of the process 604 Etched spectrum before the end of the process 606 Etched spectrum after the end of the process 508 Accumulator saturation 1317539 700 Etched emission spectrum before the end point 702 Etched emission spectrum after the end point 704 Difference in etching spectrum 800 Synthetic spectrum

900 Etched emission spectrum before endpoint 902 Etched emission spectrum after endpoint 904 Narrow spectral region (at 440 nm) 906 Wide spectral region (at 445 nm) 1100 Signal (440 nm) 1102 Background (445 nm) 1104 Deposition step 1106 Etch Step 1 200 ' 1 300 Ratio Signal (440 nm SiF/445 nm Background)

twenty two

Claims (1)

1317539 Picking up and applying for a patent: This method is used to establish a plasma etching process. The method includes the following steps: 4: placing a substrate in a vacuum chamber; etching by a plasma a material from the substrate, a passivation layer is deposited on the substrate by a plasma; 'execution of repeating the etching step and the deposition step is performed to - the etching step or sink corresponding to the process loop step The characteristic frequency of the foot is set to monitor a change in the plasma radiation intensity. The process circuit step is interrupted based on the monitoring step; and the substrate is removed from the vacuum chamber. 2. The method of claiming a patent, wherein the characteristic frequency is determined based on a sum of an etching step of the process loop step and a duration of the deposition step. 3. The method of claim 1, wherein the process application frequency is less than about 5 Hz. 4. The method of claim 2, wherein the process loop further comprises: a plurality of etching steps for each process loop. 5. The method of claim 1, wherein the process circuit further comprises: a plurality of deposition steps of each process loop. 6 The method of claim 1, wherein the monitoring step further comprises: monitoring the plasma radiation intensity in the plurality of wavelength regions. 7. The method of claim 6, wherein the step of monitoring the plurality of wavelength regions further comprises: performing a mathematical operation to obtain a plurality of 23 1317539 frequency knives S and knowing at least one characteristic frequency . The mathematical operation, the wavelengths, the mathematical points 8. The method of claim 7, wherein the fast Fourier transform is used. In the 'sho monitoring complex number' to correct a background. 9. As in the method of claim 7, the steps of the wavelength region further include performing a mathematical operation on plasma radiation. 10. The method of claim 6, wherein the region is selected by the mathematical analysis of the radiation spectrum of the 5th plasma, and the method is as described in claim 10, wherein the main components are analyzed. 12' method for detecting transition between different materials in a time division multiplexing process, the method comprising the steps of: placing a substrate in a vacuum chamber; performing the time division multiplexing process; Monitoring the change in the radiation intensity of a plasma corresponding to the characteristic frequency of the repetition rate of the etching step or the deposition step of the process loop step; The time division multiplex process is interrupted based on the monitoring step; and the substrate is removed from the vacuum chamber. 13. The method of claim 12, wherein the characteristic frequency is determined based on a sum of durations of the steps of the time division multiplexing process. 14. The method of claim a, wherein the feature The frequency system is less than about 5 Hz. 15. The method of claim 12, wherein the monitoring step 24 1317539 is further included: monitoring the plasma radiation intensity in the plurality of wavelength regions. 16. The method of claim 15, wherein the step of monitoring the plurality of wavelength regions further comprises: performing a mathematical operation to obtain a plurality of frequency components to obtain at least one characteristic frequency. 17. The method of claim 6, wherein the mathematical operation is a fast Fourier transform. 18. The method of claim 16, wherein the step of monitoring the plurality of wavelength regions further comprises: performing a mathematical operation to correct a background plasma radiation. 19. The method of claim 15, wherein the wavelength regions are selected by mathematical analysis of the plasma emission spectrum. 20. The method of claim 12, wherein the mathematical analysis is a primary component analysis. Pick up, circle: as the next page. Lu 25