JP3804561B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus used for depositing a thin film on the surface of a substrate to be processed using plasma or etching the surface of the substrate to be processed, and more particularly to a monitoring mechanism and substrate for deposits deposited on the inner wall of the processing apparatus. The present invention relates to a mechanism for monitoring the quality of a film deposited on a surface.
[0002]
In the film forming process using plasma, ions and active species present in the plasma reach the surface of the processing substrate and deposit as a desired thin film. In the etching process using plasma, ions and active species that have flowed out of the plasma are adsorbed on the surface of the processing substrate, and the reaction between the adsorbed film and the processing substrate surface is promoted by ion irradiation, so that etching proceeds.
[0003]
As described above, plasma processing steps such as etching and film formation using plasma proceed as ions or active species in the plasma are adsorbed or deposited on the surface of the substrate to be processed. Therefore, it is extremely important to know the quality of the adsorbed or deposited film in order to control the etching characteristics and film forming characteristics.
On the other hand, ions and active species that flow out of the plasma reach a place other than the surface of the substrate to be processed, for example, the inner wall surface of the chamber of the plasma processing apparatus, and are adsorbed or deposited to a place other than the surface of the substrate to be processed. Also form deposits. In this way, the deposits deposited in places other than the surface of the substrate to be processed are peeled off as the film thickness increases, and become dust generation sources. Further, when the plasma is excited in the chamber, the deposit releases an unintended substance in the chamber due to a temperature rise or reaction with ions or active species flowing out of the plasma. As a result, the composition of the plasma excited in the chamber is changed, which in turn makes the etching characteristics or the physical properties of the deposited film formed unstable. Therefore, in order to suppress the fluctuation of the plasma composition within a certain limit, it is necessary to monitor the deposited film on the inner wall surface of the chamber, and when the deposition exceeds the limit, it is necessary to clean the chamber and remove the deposited film. .
[0004]
[Prior art]
Conventionally, a dummy wafer has been used to monitor the film quality adsorbed or deposited on the surface of the substrate to be processed when plasma is excited in the plasma processing apparatus. The dummy wafer is placed instead of the substrate to be processed or close to the substrate to be processed, and undergoes the same processing as the substrate to be processed. After the processing step is completed, the dummy wafer is taken out from the chamber, and the surface state of the dummy wafer, for example, the thickness and film quality of the deposited film, the etching state, or dust attached to the surface is inspected. If the result of this inspection deviates from a given range, it is assumed that the plasma conditions have fluctuated beyond the allowable range, and the chamber is cleaned and the plasma generation conditions are reset. Thereby, the processing conditions of the substrate to be processed are restored to the same conditions as the initial setting.
[0005]
However, the plasma processing apparatus cannot be used during the inspection of the dummy wafer. For this reason, the operating rate of a plasma processing apparatus will fall. In order to keep track of the process conditions, it is desirable to perform inspections frequently, but frequent inspections increasingly reduce availability. In addition, frequent inspection leads to large consumption of dummy wafers. Today, dummy wafers are becoming larger in diameter, and large consumption of dummy wafers leads to an increase in process costs that cannot be ignored. On the other hand, if the inspection interval is extended in order to suppress a decrease in the operating rate, the process conditions change over time until the next inspection is large, and it is difficult to ensure that the process conditions remain within an appropriate range.
[0006]
Another problem with the inspection method using dummy wafers is that the target of inspection is the cumulative result of all processes performed during successive inspections, and does not directly observe individual process conditions. It is in. The inspection is usually performed by using a deposited film deposited on a dummy wafer after a plurality of processes as an inspection target. Since this deposited film is a film accumulated through a plurality of processes, it represents an average value of all these processes. For this reason, when the process variation includes a change of a plurality of conditions, it is difficult to specify the changed condition. This makes it impossible to elucidate the cause of process variation, identify the changed conditions, and perform appropriate resetting. Therefore, in the inspection method using a dummy wafer, it is only possible to confirm the current status of the process result, and it is not possible to optimally maintain each process condition.
[0007]
In order to avoid the inspection defect using the dummy wafer described above, a method for optically observing the deposited film deposited on the monitor substrate in the chamber of the plasma processing apparatus is disclosed in Japanese Patent Application Laid-Open No. 7-268628. Is disclosed. In this method, the plasma conditions are monitored by spectral analysis of the reflected light from the deposited film deposited on the monitor substrate.
[0008]
Japanese Patent Application Laid-Open No. 8-49074 discloses a method of monitoring plasma by mass spectrometry of particles emitted from the surface of a processing substrate in ion-assisted deposition. As described above, in plasma monitoring, it is desirable to directly observe physical properties such as the composition, hardness, and deposition amount (film thickness) of deposits flowing out from the plasma and depositing. From this viewpoint, the combination of the ion beam and the mass spectrometer is excellent.
[0009]
In the above-described method using the spectroscopic analysis or mass spectrometry, the deposited film on the monitor substrate can be observed in situ. Therefore, plasma can be constantly monitored without using a dummy wafer.
However, the above-described method using spectroscopic analysis requires a mechanism for entering and exiting light from the chamber wall to the monitor substrate inside the chamber, and the processing apparatus becomes complicated and expensive. Further, a method combining ion-assisted vapor deposition and a mass spectrometer cannot be applied as it is to a general plasma processing apparatus other than the ion-assisted method. Even if the combination of an ion beam and a mass spectrometer is applied to another plasma processing apparatus, for example, a parallel plate type plasma processing apparatus, an ion beam source must be newly introduced into the plasma processing apparatus. Becomes expensive. As described above, the plasma monitoring apparatus that can observe without in-situ observation or unloading and loading of the wafer into the chamber has been complicated and expensive.
[0010]
[Problems to be solved by the invention]
As described above, a dummy wafer has been conventionally used as a method for monitoring the plasma excited in the chamber. However, this method has a problem that a large amount of expensive dummy wafer is consumed when the monitoring time interval is shortened. In addition, since an average value of a plurality of processes is observed, there is a problem in that plasma fluctuations cannot be monitored by being classified into changes for each condition.
[0011]
Furthermore, in the method of optically observing the deposit on the monitor substrate in situ using the monitor substrate, or the method of etching the deposit on the monitor substrate with an ion beam and mass analyzing the emitted particles, the plasma processing apparatus is complicated and expensive. There is a problem of becoming.
Even if the deposit deposited on the monitor substrate due to the plasma excited in the chamber is frequently observed in situ or frequently at short time intervals, the operation rate of the plasma processing apparatus is reduced and the structure is reduced. Is intended to provide a simple and inexpensive plasma processing apparatus.
[0012]
[Means for Solving the Problems]
FIG. 1 is a sectional view of a first embodiment of the present invention, showing a parallel plate type plasma processing apparatus.
In the first configuration of the present invention for solving the above problem, referring to FIG. 1, a monitor substrate 3 to which an etching voltage can be applied is provided in a chamber 1 of a plasma processing apparatus. The etching voltage may be a voltage that draws ions from the plasma 6 and collides with deposits on the surface of the monitor substrate 3 to give the ions energy sufficient to etch the deposits on the monitor substrate 3. A necessary voltage and its positive / negative polarity can be selected according to desired etching conditions. During the plasma processing step (hereinafter referred to as “plasma processing step”) for performing the surface processing of the substrate 2 to be processed, deposits generated with the generation of the plasma 6 are deposited on the surface of the monitor substrate 3. On the other hand, during a step of analyzing deposits deposited on the surface of the monitor substrate 3 (hereinafter referred to as “analysis step”), an etching voltage is applied to the monitor substrate 3 and the deposits on the surface of the monitor substrate 3 are etched. The etched deposit is scattered from the surface of the monitor substrate 3 into the chamber 1 and analyzed by the analyzer 5. Thus, the deposit deposited on the surface of the monitor substrate 3 during the plasma processing is analyzed.
[0013]
In the first configuration, the deposit deposited on the surface of the monitor substrate 3 is ion-etched and analyzed by applying an etching voltage to the monitor substrate 3. That is, the deposit deposited on the surface of the monitor substrate 3 is etched and removed in the analysis process. Therefore, by continuing the analysis process until the deposit is completely removed, the state of the monitor substrate 3 is initialized and can be used again as the monitor substrate 3 for the next plasma processing. As described above, this configuration is economical because a dummy wafer consumed for each inspection is not used. Moreover, since the deposit can be analyzed without carrying out and carrying in the dummy wafer from the chamber 1, the deposit can be analyzed in a very short time. For this reason, even if the analysis is repeated frequently, the decrease in the apparatus operation rate is small. Further, since the analysis of the deposit can be performed simultaneously with the plasma processing step or in the middle of the plasma processing step, in-situ observation or observation for each plasma processing or during the plasma processing is easy. As described above, plasma can be monitored constantly or frequently without lowering the apparatus operation rate and increasing the purchase cost of dummy wafers, so that it is easy to take appropriate measures at the optimum time.
[0014]
The plasma processing of the substrate 2 to be processed having the first configuration may be a processing in which a substance flowing out from the plasma 6 is deposited on the surface of the substrate 2 to be processed or somewhere in the exposed portion in the chamber 1. Plasma CVD is included.
In the first configuration, the analysis process can be continued after the plasma treatment process. At this time, the plasma used in the plasma processing step and the analysis step may be plasmas of different gases.
[0015]
For example, after performing etching or film formation by RIE (reactive ion etching) using a reactive gas or plasma CVD using a raw material gas as a plasma treatment, what is a reactive gas or a raw material gas in the plasma processing step? Different gases can be used to excite the plasma and deposits deposited on the monitor substrate during the plasma treatment process can be etched and analyzed. By generating plasma for the plasma treatment process and the analysis process from different gases in this way, the background of the component analysis of the deposit can be reduced, and the sensitivity can be improved by increasing the ion etching rate in the analysis process. it can. Of course, the plasma in the analysis step subsequent to the plasma processing step may be generated from a gas having the same composition as the plasma processing gas.
[0016]
In the first configuration, the plasma processing step and the analysis step can be performed simultaneously. Specifically, analysis can be performed by applying an etching voltage to the monitor substrate 3 during plasma processing of the substrate 2 to be processed. This analysis step may be in-situ observation that continues during the plasma treatment period, or may be divided into a plurality of analysis steps. However, in the analysis process, the deposit on the monitor substrate 3 is removed by etching. For this reason, if the analysis is continued continuously, the etching rate must be slowed to meet the deposition rate, limiting sensitivity. Therefore, it is preferable from the viewpoint of sensitivity to divide the analysis process to ensure a sufficient deposit film thickness during the analysis stop period.
[0017]
The etching voltage in the first configuration can be a pulse voltage. The type and amount of the substance released from the deposit on the monitor substrate 3 changes following the etching voltage. On the other hand, ions, active species, and neutral particles in the atmosphere in the chamber 1 including plasma do not change much in composition and density even when an etching voltage is applied to the monitor substrate 3. Therefore, the influence of particles in the atmosphere in the chamber 1 can be separated from the analysis result by applying a pulsed etching voltage. Accordingly, analysis noise can be reduced.
[0018]
A bias voltage can also be applied to the monitor substrate 3 of the first configuration during the plasma processing. By applying a bias voltage to the monitor substrate 3, deposits on the monitor substrate 3 can be controlled. For example, a bias voltage can be selected to select and analyze deposits that are sensitive to specific conditions of the plasma. Further, by setting the potential of the monitor substrate 3 to the same potential as the substrate 2 to be processed, the deposit deposited on the monitor substrate 3 can be made to be the same quality as the deposit deposited on the surface of the substrate 2 to be processed. This bias voltage can have positive and negative polarities as necessary, and may be in a floating state.
[0019]
In the first configuration described above, the ion etching of the deposit on the monitor substrate 3 is performed by applying a voltage to the monitor substrate 3, and no other special mechanism is required. The analyzer 5 can use an analyzer mounted on a normal plasma processing apparatus, such as a mass analyzer or an ion gauge, and it is not necessary to prepare a special mechanism or a special analyzer. . Thus, since no special mechanism or apparatus is required to apply the present invention, the plasma processing apparatus of this configuration is not complicated and can be manufactured at low cost.
[0020]
The second configuration of the present invention relates to a plasma processing apparatus provided with a plurality of monitor substrates of the first configuration.
The second configuration includes a monitor substrate selection mechanism that moves a monitor substrate arbitrarily selected from a plurality of monitor substrates to the vicinity of the sample suction port of the analyzer. This monitor substrate selection mechanism can apply an etching voltage only to the selected monitor substrate. Therefore, an arbitrary monitor substrate can be selected from the plurality of monitor substrates, and only the deposit deposited thereon can be analyzed.
[0021]
As described above, since the deposit on the monitor substrate to be analyzed is etched and removed in the analysis process, the monitor substrate is initialized for each analysis process. Therefore, when only one monitor substrate is provided, when a plurality of plasma processing steps are continuously performed, if the analysis step is inserted for each plasma processing step, the monitor substrate is always initialized immediately before each plasma step. Therefore, a single plasma processing process is always analyzed. This makes it impossible to analyze the deposited film accumulated according to the number of plasma treatments and clarify the relationship between the accumulated number of treatments and the deposited film. The second configuration makes it possible to analyze the accumulated deposited film.
[0022]
In this configuration, the deposit can be analyzed by selecting an arbitrary monitor substrate from among the plurality of monitor substrates. With this configuration, it is possible to evaluate a deposit deposited through a plurality of plasma treatment steps. For example, the 1st to Nth monitor boards are respectively connected to M₁~ M_NCorresponding as a monitor substrate for accumulating the number of plasma processing steps. Here, deposits are deposited on all monitor substrates during the plasma processing step. The analysis process is performed for each of the 1st to Nth monitor substrates.₁Times-M_NThe analysis process is performed every time the plasma treatment process is performed. That is, the first monitor board is M₁It is analyzed every time (for example, once). The Nth (for example, sixth) monitor board is M_NAnalysis is performed every time (for example, 60 times). Therefore, the analysis result of the first monitor board is M₁Deposits deposited during the plasma treatment, i.e. M₁It represents the cumulative result of the plasma treatment for the first time. Similarly, the analysis result of the Nth monitor board is M_NIt represents the cumulative result of the plasma treatment for the first time. In this way, cumulative results of multiple plasma treatments can be analyzed and evaluated.
[0023]
In this example, the deposit is always deposited on all the monitor substrates when the plasma processing is performed. However, a bias voltage is applied to a specific monitor substrate during a specific plasma processing period, so that the specific It is also possible to stop the deposition in the plasma processing step and eliminate the influence. Thereby, the influence of a specific plasma process can be clarified. Further, instead of stopping the deposition, it is also possible to deposit a deposit having different physical properties by applying a bias voltage different from that of the substrate to be processed or another monitor substrate. Thereby, the influence regarding the specific conditions of plasma processing can be clarified.
[0024]
FIG. 3 is a perspective view of a second embodiment of the present invention, showing a monitor substrate selection mechanism. The monitor substrate selection mechanism having the second configuration can be realized by a mechanism in which the monitor substrates are arranged in an impeller shape. Referring to FIG. 3, two monitor boards 3-1a and 3-1b are bonded together to form one flat blade, and the flat blade is radially formed on the rotating shaft 31 so as to form an impeller shape. Install. The rotating shaft 31 is attached to the chamber inner wall surface 1a, for example, vertically. A sample suction port 4 of the analyzer 5 is opened on the inner wall surface 1a of the chamber. The sample inlet 4 has monitor inlets, for example, monitor boards 3-2a, 3-, which are opposed to each other as V-shaped inner surfaces with the sample inlet central axis 4a being parallel to the rotary shaft 31 and having the rotary shaft 31 as a vertex. It arrange | positions so that it may pass between 3b. Further, in the analysis step, an etching voltage is applied only to the two monitor substrates 3-2a and 3-3b facing each other across the sample suction port 4, and the two monitor substrates 3-2a and 3-3b are applied. The top deposit is analyzed.
[0025]
The monitor substrate selection mechanism of this configuration selects an arbitrary set of the two monitor substrates facing each other as the V-shaped inner surface by rotating the rotating shaft 31 and moves it near the sample inlet 4. This set of monitor boards can be analyzed. Instead of the two monitor substrates facing each other as the V-shaped inner surface, one monitor substrate or a monitor substrate constituting both surfaces of the bonded blades is selected, moved to the vicinity of the sample inlet 4 and analyzed. There is no problem.
[0026]
FIG. 5 is a side view of the fourth embodiment of the present invention, and FIG. 6 is a front view of the fourth embodiment of the present invention, showing a monitor substrate selection mechanism. The monitor substrate selection mechanism of the second configuration can be realized by the mechanism of the fourth embodiment in which monitor substrates are further stacked and moved linearly in the stacked direction. With reference to FIGS. 5 and 6, a plurality of monitor substrates 3-1 to 3-4 are mounted on a mechanism (support bar 33) that moves in parallel with the chamber inner wall surface 1 a in a moving direction. By using this moving mechanism, an arbitrary monitor substrate 3-2 is moved to the vicinity of the sample inlet 4 of the analyzer 5 provided on the chamber wall surface, and an etching voltage is applied only to the monitor substrate 3-2. Any monitor board 3-2 can be identified and analyzed. In this configuration, the etching voltage can be applied only to one side (the lower surface in FIG. 5) of the monitor substrate 3-2 closest to the sample suction port 4. Further, the etching voltage may be applied only to the two opposing surfaces of the substrates 3-2 and 3-3 that are opposed to each other with the sample inlet 4 interposed therebetween.
[0027]
FIG. 4 is a perspective view of a third embodiment of the present invention, showing a monitor substrate selection mechanism having a grid. You may provide the grid 32 to which the same voltage as the monitor board | substrates 3-1a-3-6b is applied to the monitor board | substrates 3-1a-3-6b mentioned above. Since the grid 32 is at the same potential as the monitor substrates 3-1a to 3-6b, the same deposit as the monitor substrates 3-1a to 3-6b is always deposited, and this deposit is the monitor substrates 3-1a to 3-6. It is analyzed simultaneously with the analysis of the deposit on 6b. Since the grid 32 has a surface area larger than that of the flat plate, a large amount of deposits are deposited, so that analysis sensitivity is improved. Even if the grid 32 is arranged in the vicinity of the monitor substrates 3-1a to 3-6b, most of the deposited particles in the atmosphere pass through the grid 32 without being disturbed. The amount and quality of the deposits on 1a-3-6b hardly change.
[0028]
Furthermore, this grid is also applied to the above-described second configuration in which a plurality of monitor boards are arranged. For example, with reference to FIG. 3, the grid 32 is attached to the tip of the monitor substrate selection mechanism in which the monitor substrates 3-1a to 3-6b are attached in an impeller shape. In addition, referring to FIGS. 5 and 6, it can be arranged at the front end (the right end in FIG. 5) of the monitor selection mechanism in which the monitor substrates are arranged in an overlapping manner.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to an embodiment in which the present invention is applied to a parallel plate type plasma processing apparatus.
The first embodiment of the present invention is an example in which one monitor substrate is arranged in a parallel plate type plasma processing apparatus. Referring to FIG. 1, the plasma processing apparatus includes a chamber 1 in which plasma processing is performed, and an analyzer 5 having a sample inlet 4 on the inner wall surface of the chamber 1.
[0030]
An upper electrode 11 having a large number of gas introduction holes 15 is provided on the upper portion of the chamber 1. A gas used for plasma processing (hereinafter referred to as “plasma processing gas”) is introduced into the upper electrode 11 from the gas introduction pipe 14, flows into the chamber 1 through the gas introduction hole 15, and is opened in the lower portion of the chamber 1. It is evacuated from the exhaust port 13. A substrate holder 12 also serving as a lower electrode is provided at the lower portion of the chamber 1, and a substrate 2 to be processed, for example, a silicon wafer is placed on the upper surface thereof. A bias voltage is applied to the substrate holder 12 in order to control the characteristics of the plasma processing. The analyzer 5 is a quadrupole mass spectrometer, for example, and is conventionally provided for monitoring the composition of the atmosphere in the chamber 1. The inside of the analyzer 5 is evacuated from the exhaust port 5 c and differentially evacuated from the chamber 1. As a result, the substance is sucked from the atmosphere in the chamber 1, and the substance ionized by the ionizer 5a is analyzed by the analysis unit 5b. These structures described above are the same as the conventional plasma processing apparatus.
[0031]
In this embodiment, the monitor substrate 3 is provided on the wall of the chamber 1 near the sample inlet 4. The monitor substrate 3 is preferably provided almost horizontally so that a substance that separates from the surface is efficiently sucked and captured by the sample inlet 4. If necessary, it can be provided in other states, for example, perpendicularly or perpendicularly to the wall surface of the chamber. When the monitor substrate 3 is placed away from the wall surface of the chamber 1, the sample inlet 4 of the analyzer 5 is formed in a tubular shape and monitored. It can also extend near the substrate 3. Thereby, the monitor substrate 3 can be installed near the substrate 2 to be processed placed in the center of the chamber 1.
[0032]
The monitor substrate 3 is made of a conductive material to which a voltage can be applied, for example, stainless steel. If necessary, an insulating film may be coated on the surface, or a silicon substrate may be placed to prevent the conductive material from being etched and contaminating the plasma. The power source 7 applies an etching voltage and a bias voltage to the monitor substrate 3. The etching voltage is usually several kV and the bias voltage is usually several hundred V or less. These voltages are adjusted to appropriate values as necessary. Note that the polarity can be positive or negative depending on the target ion species, plasma processing conditions, and the like.
[0033]
FIG. 2 is an explanatory view of the analysis result of the first embodiment of the present invention, and shows the analysis result when the silicon wafer is etched using the plasma processing apparatus of the first embodiment described above. That is, the plasma processing step is a case of plasma etching of a silicon wafer.
C as plasma processing gas₂F₆The silicon wafer surface was exposed to the generated plasma 6 and etched. A silicon substrate (not shown) was placed on the monitor substrate 3, and the deposit deposited on the surface of the silicon substrate by exposure to plasma during the etching process was analyzed. In the analysis, Ar gas is introduced in place of the plasma processing gas to generate Ar plasma 6, and then an etching voltage of 3 kV is applied to the monitor substrate 3 and emitted from the surface of the silicon substrate placed on the monitor substrate 3. The resulting material was analyzed by a quadrupole mass spectrometer 5. The electron collision energy when ionizing by mass spectrometry was 20 eV.
[0034]
FIGS. 2A and 2B show the analysis results when the processing times of the plasma processing steps are different. In each case, when the film thickness of the deposit deposited on the silicon substrate on the monitor substrate 3 was measured using an ellipsometer, it was 500 nm in FIG. 2A and 20 nm in FIG. 2B. In all cases, the refractive index was calculated as 1.5. The horizontal axis of FIG. 2 represents Ar irradiated to the monitor substrate 3 during the analysis process.⁺The cumulative dose per unit area of ions. The vertical axis represents the number of particles per hour of various ions counted by the analyzer. Ar⁺The ion irradiation intensity is kept constant during the analysis process.
[0035]
Referring to FIG. 2, in both cases where the film thickness of the deposit is 500 nm and 20 nm, CF⁺, CF₂ ⁺And CF_Three ⁺Ions were observed. This is C₂F₆This shows that ions and active species flowing out from the plasma reach the silicon substrate surface on the monitor substrate 3 to form a fluorocarbon deposited film.
Comparing FIGS. 2A and 2B, the cumulative dose amount is 1 × 10.¹⁶cm^-2The initial change of ionic strength is settled when exceeding. CF at this point_Three ⁺The ionic strength is about 5 times larger in the case of (a) having a film thickness of 500 nm than in the case of (b) having a film thickness of 20 nm. This is due to the difference in film thickness. Therefore, the film thickness of the deposit can be observed by measuring the ionic strength. In FIGS. 2A and 2B, CF₂ ⁺And CF_Three ⁺And the ionic strength ratio is different. This indicates that the composition, chemical bond or hardness of the deposit is different, and the film quality of the deposit can be analyzed from the ionic species and the ionic strength ratio.
[0036]
Referring to FIG. 2, in the initial stage of analysis with a small cumulative dose, the ionic strength decreases rapidly. This is Ar⁺In the initial stage where the ion dose is low, Ar⁺While there is little alteration of the deposit due to ion irradiation, the physical properties of the deposited state are reflected as they are, whereas Ar⁺This is because when the amount of ion irradiation is large, the deposit is greatly altered and the original physical properties change. Therefore, the initial stage of the analysis more reflects the physical properties of the deposited state. The initial stage of (a) and (b) in FIG._Three ⁺When the ionic strength is approximated by an exponential function with the cumulative dose as a variable, 2.5 × 10 5 is obtained in (a).^-16, (B) is 3.5 × 10^-16Thus, the smaller the film thickness, the greater the decrease in ionic strength. This suggests that the thin film has a soft film quality and a high etching rate. In addition, the initial CF₂ ⁺Ion and CF_Three ⁺The ion intensity ratio of ions differs between (a) and (b). This indicates that the composition differs depending on the difference in film thickness.
[0037]
In this embodiment, the example in which etching is used as the plasma processing step has been described.₂F₆The same analysis can be performed with respect to plasma CVD using a gas containing hydrogen. In addition, the etching voltage applied to the monitor substrate in the analysis step can be changed to a pulse to improve the S / N ratio of the analysis.
Furthermore, instead of Ar plasma in the analysis process, the same C as in the plasma processing process₂F₆A gas plasma containing can be used in the analysis step. At this time, in-situ observation in which the analysis step and the plasma treatment step are performed simultaneously can be performed.
[0038]
The second embodiment of the present invention relates to a plasma processing apparatus having a monitor substrate selection mechanism in which the monitor substrate of the first embodiment is provided in a shape of a plurality of impellers.
Referring to FIG. 3, in this monitor substrate selection mechanism, flat plates are radially attached to a rotating shaft 31 installed perpendicularly to the inner wall surface 1a of the impeller. Stainless steel monitor substrates 3-1a to 3-6b that are insulated from each other are attached to both surfaces of the flat plate. A sample suction port 4 having a sample suction port central axis 4 a parallel to the rotation shaft 31 is opened on the inner wall surface 1 a of the chamber near the rotation shaft 31.
[0039]
At the time of analysis, the rotary shaft 31 is rotated, and an arbitrary blade-like flat plate is moved onto the sample inlet central axis 4a. Next, an etching-like voltage is applied only to the monitor substrates 3-3a and 3-3b attached to both surfaces of the flat plate. As a result, the analysis is performed on the monitor substrates 3-3a and 3-3b attached to both surfaces of the flat plate. In the second analysis step that follows, the rotating shaft 31 is rotated to move other monitor substrates, for example, the monitor substrates 3-4a and 3-4b, onto the sample inlet central axis 4a, and an etching voltage is applied. analyse. In the second analysis step, a deposit accumulated and accumulated in the plasma processing step analyzed first and the plasma processing step analyzed second time is used as an analysis target. Similarly, it is possible to analyze deposits having different accumulation times by the number of blades. Note that the first analysis and the second analysis are performed each time the plasma treatment process reaches a given cumulative number, so that the relationship between the cumulative number and the change in deposits can be monitored.
[0040]
In the second embodiment, the two monitor substrates 3-2a and 3-3b facing in a V shape are moved so as to sandwich the sample suction port central axis 4a, and the two monitor substrates 3-2a and 3b are moved. It is also possible to analyze by applying an etching voltage only to -3b. Of course, the monitor voltage may be applied only to one monitor board.
The third embodiment of the present invention relates to an example in which a grid is provided at the tip of the monitor substrate selection mechanism of the second embodiment.
[0041]
Referring to FIG. 4, two monitor substrates facing in a V-shape, for example, a grid 32-2 at the same potential as monitor substrates 3-2 a and 3-3 b, a monitor substrate closer to the center of chamber 1. Place near the tip of the selection mechanism. Since the same voltage as that of the monitor substrate to be analyzed is applied to the grid 32, the same deposit is deposited and analyzed simultaneously. Accordingly, since the surface area of the monitor substrate is substantially increased, the analysis sensitivity is increased.
[0042]
The fourth embodiment of the present invention relates to a monitor substrate selection mechanism that moves linearly.
Referring to FIGS. 5 and 6, the monitor substrate selection mechanism according to the present embodiment includes two support bars 33 that linearly move in parallel with the chamber inner wall surface 1a. The monitor boards 3-1 to 3-4 are arranged so that both ends are sandwiched between the support bars 33 and stacked in the moving direction 33a. In the analysis step, an arbitrary monitor substrate, for example, the monitor substrate 3-2 is moved near the sample inlet 4 provided on the inner wall surface 1a of the chamber, and an etching voltage is applied only to the monitor substrate 3-2. Alternatively, the etching voltage can be applied only to the opposing surfaces of the two monitor substrates that overlap vertically, for example, the lower surface of the monitor substrate 3-2 and the upper surface of the monitor substrate 3-3. At this time, the support bar 33 is moved so that the sample suction port 4 is positioned in the middle of the monitor substrates 3-2 and 3-3 that overlap vertically. Furthermore, a grid at the same potential as the monitor substrate may be provided on the front surface of the monitor substrate, and the etching voltage may be a pulse.
[0043]
The inventions disclosed in the present specification described above include the inventions described in the following supplementary notes.
(Additional remark 1) In the plasma processing apparatus which performs the surface treatment of the to-be-processed substrate set | placed in this chamber using the plasma generated in the chamber,
A monitor substrate provided in the chamber and on which deposits are deposited during the surface treatment; and a power supply for applying an etching voltage to the monitor substrate to plasma etch the deposits on the monitor substrate;
A plasma processing apparatus, comprising: an analyzer that analyzes a substance that is detached from the surface of the monitor substrate during the plasma etching.
[0044]
(Supplementary note 2) The plasma processing apparatus according to supplementary note 1, wherein the etching voltage is a pulse voltage.
(Supplementary note 3) The plasma processing apparatus according to supplementary note 1 or 2, wherein the power source applies a bias voltage for controlling physical properties of the deposit to the monitor substrate during the surface treatment.
[0045]
(Supplementary Note 4) A monitor substrate arbitrarily selected from the plurality of monitor substrates movably disposed is moved to the vicinity of the sample inlet of the analyzer, and the selected monitor substrate is used for the etching. 4. The plasma processing apparatus according to appendix 1, 2, or 3, further comprising a monitor substrate selection mechanism for applying a voltage.
(Supplementary Note 5) A plurality of the monitor boards are provided so as to constitute the blades in the shape of an impeller in which flat blades are radially attached to the rotation shaft,
Monitor substrate selection that moves any monitor substrate to the vicinity of the sample inlet of the analyzer by rotation of the monitor substrate about the rotation axis, and applies the etching voltage to the selected monitor substrate The plasma processing apparatus according to appendix 1, 2, or 3, characterized by having a mechanism.
[0046]
(Supplementary Note 6) A plurality of the monitor boards are arranged on the linear movement mechanism that linearly moves, with a space between each other and in the linear movement direction.
And a monitor substrate selection mechanism for moving the selected monitor substrate in the vicinity of the sample inlet of the analyzer by the linear movement and applying the etching voltage to the selected monitor substrate. The plasma processing apparatus according to appendix 1, 2, or 3.
[0047]
(Supplementary note 7) The plasma processing apparatus according to supplementary note 5 or 6, wherein a grid having substantially the same potential as each monitor substrate is provided in the vicinity of the tips of the plurality of monitor substrates.
[0048]
【The invention's effect】
In the plasma processing apparatus according to the present invention, deposits deposited on the monitor substrate when plasma is generated in the plasma processing step can be directly analyzed, so that each factor of plasma fluctuation can be analyzed and appropriately dealt with. it can. In addition, since the time required for analysis can be significantly shortened, plasma processing conditions and the like can be corrected at an optimal time. Furthermore, since an expensive dummy wafer and an expensive mechanism are not required, the cost required for the apparatus and the process is low. Therefore, it greatly contributes to the improvement of the manufacturing yield of the semiconductor device.
[Brief description of the drawings]
FIG. 1 is a sectional view of a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of analysis results of the first embodiment of the present invention.
FIG. 3 is a perspective view of a second embodiment of the present invention.
FIG. 4 is a perspective view of a third embodiment of the present invention.
FIG. 5 is a side view of a fourth embodiment of the present invention.
FIG. 6 is a front view of a fourth embodiment of the present invention.
[Explanation of symbols]
1 chamber
1a Chamber inner wall
2 Substrate
3 Monitor board
3-1a, 3-1b to 3-6a, 3-6b Monitor board
4 Sample inlet
4a Sample inlet central axis
5 Analyzer
5a Ionizer
5b Analysis unit
5c Exhaust port
6 Plasma
7 Power supply
11 Upper electrode
12 Substrate holder
13 Exhaust port
14 Gas introduction pipe
14a Gas inlet
31 Rotating shaft
32, 32-1 to 32-6 grid
33 Support rod
33a Movement direction

Claims (4)

Using a plasma generated in the chamber, the plasma processing apparatus for the surface treatment of the substrate placed in the chamber,
A plurality of monitor substrates provided in the chamber on which deposits are deposited during the surface treatment;
A power source for applying the deposit on the monitor substrate selected in the plurality of monitors in the substrate etching voltage for plasma etching, to the selected monitor substrate,
An analyzer having a sample inlet on the inner wall of the chamber , the analyzer for sucking in and analyzing from the sample inlet a substance that detaches from the selected monitor substrate surface during the plasma etching;
A plasma processing apparatus, comprising: a monitor substrate selection mechanism that moves the selected monitor substrate to the vicinity of a sample inlet of the analyzer. The plasma processing apparatus according to claim 1,
The monitor board selection mechanism is provided so that the plurality of monitor boards constitute the blades having an impeller shape in which flat blades are radially attached to a rotation shaft, and the plurality of monitors having the rotation shaft as an axis. A plasma processing apparatus, wherein the selected monitor substrate is moved in the vicinity of a sample inlet of the analyzer by rotation of the substrate. A plasma processing method for performing surface treatment of a substrate to be processed placed in the chamber using plasma generated in the chamber,
The sample of the analyzer having a sample suction port on the inner wall of the chamber by depositing a deposit reflecting the inner wall of the chamber or deposit deposited on the processed substrate by plasma processing for processing the substrate to be processed Moving to the vicinity of the inlet;
Plasma etching the monitor substrate ;
Inhale a substance released from the monitor substrate surface during the plasma etching from the sample suction port seen including a step of analyzing in the analyzer,
The plasma processing method , wherein the monitor substrate is a monitor substrate arbitrarily selected from a plurality of monitor substrates . The plasma processing method according to claim 3,
In the plasma etching step, a pulsed etching voltage is applied to the monitor substrate.

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