KR100938679B1 - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

The present invention provides a plasma processing apparatus which monitors the unevenness of the processing result due to the change in the apparatus state, and detects the recovery state when the apparatus state changes, thereby making it possible to determine whether or not to process.

In the plasma processing apparatus having a control chamber 10 and a processing chamber 1 for performing plasma processing on the wafer 2, the plasma state in which the processing chamber 1 detects a processing state inside the processing chamber and outputs a plurality of output signals. A function (13) having detection means (8, 9), wherein the control unit (10) stores information on past wafer processing results, plasma state detection data during past wafer processing, and a relational expression for correlating both; A function 11 for calculating a process chamber state detection result from the plasma state detecting means 8 and 9 and a predicted value of the process result from the relational expression, and a function 12 for evaluating the process chamber state based on the calculated predicted value of the process result. After the wafer processing, the predicted value of the processing result is calculated from the correlation equation, thereby monitoring the state of the processing chamber.

Description

Plasma processing apparatus and plasma processing method {PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD}

1 is a schematic diagram of a plasma processing apparatus having a device state monitoring system for explaining a first embodiment of the present invention;

2 is a flowchart of an operation for explaining a first embodiment of the present invention;

3 is a calculation result display example for explaining a first embodiment of the present invention;

4 is a flowchart of an operation for explaining a second embodiment of the present invention;

5 is a calculation result display example for explaining a second embodiment of the present invention;

6 is a flowchart of an operation for explaining a third embodiment of the present invention;

7 is a calculation result display example for explaining a third embodiment of the present invention;

8 is a view for explaining a form of product processing using a plurality of processing apparatuses according to the present invention;

9 is a schematic sectional view of a semiconductor substrate for explaining a fourth embodiment of the present invention;

10 is a flowchart of an operation for explaining a fourth embodiment of the present invention;

11 is a calculation result display example for explaining the fourth embodiment of the present invention.

※ Explanation of symbols for main parts of drawing

1: process chamber 2: substrate                 

3: plasma 4: sample stand

5 electrode for plasma generation 6 gas supply means

7 gas exhaust means 9 plasma state detection means

10: plasma processing unit control unit 11: signal processing unit

12: device status monitoring unit 13: database unit

14, 17: threshold 21: Si substrate

22: gate oxide film 23: polysilicon

24: photoresist 25: substrate chipping

The present invention belongs to the manufacturing technology of semiconductors. In particular, the present invention relates to a plasma processing apparatus which realizes reproducibility of processing results when performing plasma processing of a wafer in a semiconductor manufacturing apparatus, and a plasma processing method in the plasma processing apparatus.

In recent years, with the high integration of semiconductor devices, circuit patterns are becoming more miniaturized, and the required processing dimension precision is becoming increasingly strict. For example, even a nonuniformity of the machining dimension of about 1 Onm or less may cause a defect of the apparatus. In such a situation, the reproducibility of the processing state in the plasma processing becomes important.

That is, in the case where deposit reaction products adhere to and remain on the inner wall of the processing chamber of the plasma processing apparatus, the wafer processing state may change and affect the processing result, and thus the reproducibility of the processing state cannot be maintained. Therefore, when the amount of residual reaction product in the processing chamber is uneven for each treatment, the processing result is also uneven. In particular, when the reaction product is removed, such as after maintenance, the processing result is greatly shifted compared to before maintenance. There is a case.

As a method of coping with the nonuniformity of the plasma treatment result, a study on the recovery of the treatment chamber state by the so-called seasoning treatment has been conducted. This method is a method of first cleaning the inside of a process chamber by plasma, and then etching the dummy wafer under conditions close to the etching of the product, thereby bringing the state of the inner wall of the process chamber closer to the state of continuous processing (for example, a patent). See Document 1)

In addition, a method of detecting a shift in the processing state of the plasma processing apparatus by detecting various variations of monitor values by installing various detectors in the plasma processing chamber of the plasma processing apparatus has been studied. In the method for monitoring the processing state in such a plasma processing apparatus, an example in which multivariate analysis is used to correspond to detection data from many detectors is also disclosed (see Patent Document 2, for example).

(Patent Document 1)

Japanese Patent Application Laid-Open No. 2002-110642

(Patent Document 2)

Japanese Patent Application Laid-Open No. 2002-25981

However, in the example disclosed in Patent Document 1, it is not considered at what point in time of the seasoning process that the recovery of the processing chamber state by the seasoning process has been achieved, i.e., detecting the end point of the seasoning. If the seasoning time is short, the reaction product is insufficient, on the contrary, if it is too long, the reaction product is excessively attached, so that a desired processing result cannot be obtained. As a result, the seasoning conditions are variously tested to determine the seasoning conditions by a tri-and-error which performs actual product processing, and there is a problem that a wafer and a large amount of time are required for the conditional decision until the conditional decision is made. If the conditions determined in this way are different from the state of the device in which the seasoning conditions are determined, for example, after replacement of a given part, they may not be accepted. Therefore, the conditions must be corrected again. There is also.

Next, in the example disclosed in Patent Literature 2, studies have been made to detect a large number of monitor values and then monitor the variation of the apparatus state by using multivariate analysis. However, it is not considered how it affects the processing result. In other words, there is a detection value that affects and a detection value that does not affect, and when a change in the device state is detected, it does not necessarily affect the processing result. Even if it affects, it is necessary to consider how much the processing result will be shifted if there is a deviation in the detected value.

In view of the above problems, an object of the present invention is to monitor the nonuniformity of the processing result due to the change in the state of the apparatus in the plasma processing apparatus, and to recover the apparatus in the case of large fluctuations in the apparatus state such as after maintenance. The present invention provides a plasma processing apparatus and a processing method capable of detecting a state and judging whether or not it is processed.

The above object is a plasma state detection means in a processing chamber of a plasma processing apparatus, and the control unit of the processing apparatus has a relational expression for correlating past wafer processing result information with plasma state detection data during the wafer processing and both as a database. The prediction value of the processing result is calculated from the plasma state detection data during the wafer processing and the correlation accumulated in the database, and the processing chamber state is monitored by the calculated value of the processing result.

In addition, the present invention has a relational expression for correlating the plasma state detection data and the product processing result information during product substrate processing, and not only calculates the predicted value of the product processing result from the plasma state detection data and the correlation after product processing. The relational expression for correlating the product processing result performed at the same time as the plasma state detection data at the time of the dummy substrate processing is used as a database. The predicted value of the processing result can be calculated.

As described above, in the present invention, the predicted value of the processing result when the product is processed can be calculated, so that the product can be judged whether or not the device is in the state of the device capable of obtaining the desired shape.

In addition, the database can be achieved more effectively by having a product type to be processed in the apparatus.                     

According to the present invention, when the calculated value of the calculated result exceeds the preset value, it is notified that the failure can be prevented due to the device abnormality.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described in detail with reference to drawings.

1 to 3, a first embodiment of the present invention is shown. 1 shows a plasma processing apparatus having an apparatus condition monitoring system. The plasma processing apparatus according to the present invention comprises a processing chamber 1, a gas supply means 6, a gas exhaust means 7, and an apparatus control unit 10. The processing chamber 1 is provided with a sample stage 4, a plasma generating means 5, and plasma state detecting means 8 and 9, and the device control unit 10 monitors the signal operation unit 11 and the device state. The unit 12 and the database unit 13 are provided.

The process chamber 1 is provided with a gas supply means 6 for supplying a process gas and a gas exhaust means 7 having a function of exhausting the process gas to control the pressure in the process chamber. In the processing chamber, a sample stage 4 supporting the sample 2 to be processed is provided, and plasma generating means 5 for generating the plasma 3 is provided in the processing chamber. In the semiconductor manufacturing apparatus, the sample 2 is a wafer, for example, in the LCD manufacturing apparatus, the sample 2 is a glass substrate.

The plasma state detecting means 8, 9 may be, for example, a current detector or a voltage detector installed in a path for applying power to the plasma generating means 6, or a current voltage phase difference detector or a traveling wave detector or a reflected wave detector or an impedance monitor of electric power. to be. It is a spectroscope which detects light emission from the plasma generated by the plasma generating means 6 in the processing chamber 1. The emission spectrometer may be a detector that draws out a single wavelength of light, such as a monochromator, but is most suitably a detector that outputs a plurality of signals, such as a spectrometer that outputs a wavelength resolved emission spectrum. The plasma state detecting means 8 and 9 may be means other than this, for example, a gas flow meter provided in the gas supply means 6, a mass analyzer provided in the processing chamber, or the like. These state detection means output a signal indicative of the state of the apparatus at predetermined intervals or at some set sampling times.

The apparatus control unit 10 of the plasma processing includes a signal operating unit 11 for processing a signal sent from the plasma state detecting means 8 and 9, an apparatus state monitoring unit 12 for notifying the state of the apparatus to the outside, and the apparatus. Plasma state detection data, plasma processing result, for example, processing size, etching rate, etc., plasma state data of the past plasma processing result, plasma processing of the wafer corresponding to the processing result for each device structure of the product to be implemented in The database unit 13 is provided which stores a correlation expression indicating a relationship with the.

The signals sent from the plasma state detection means 8, 9 often rise to a large number of signals. For example, in the case of a spectroscope which outputs the wavelength-resolved emission spectrum as described above, the state signals of the device to be output for each sampling time are 1000 to 2000. In order to express a large number of signals in the correlation with the processing result in this way, it is preferable to filter the signal and make it a small signal by multivariate analysis such as principal component analysis.

Hereinafter, a monitoring example of CD dimensions (representative micro dimensions) will be described with reference to FIGS. 2 to 3. Fig. 2 shows a flow of calculation performed in this embodiment, and Fig. 3 shows a display example of the calculation result. The database unit 13 has a correlation between the plasma state detection data during etching in a certain period of time and the CD dimension value and amount data as the processing result for all kinds of products to be processed in the processing chamber 1 ( Model expression). When a product (hereinafter referred to as product A) has been started, a plasma expression state is called when the etching operation currently being processed is finished by invoking the relationship between the plasma state detection data and the CD dimension value as a result of the processing by calling the signal operation unit 11. CD dimensions are calculated by the plasma state detection data and model equations sent from the detection means 8 and 9.

For example, the electrode processing of the gate wiring requires precise dimension management because the size of the wiring width directly affects the operation speed of the apparatus. CD dimensions are usually inspected by a scanning electron microscope (CD-SEM) for measurement after etching. In the case of conducting inspection on a CD-SEM, it is impossible to inspect all the processed wafers considering the time required for processing per CD-SEM, so it is generally inspected at a rate of one sheet per few lots. to be. For example, if something changes in the plasma state of the device immediately after the inspection by CD-SEM, which is carried out at intervals of several lots, and an abnormality occurs in the CD dimension, the abnormality is not known until the next dimension measurement inspection. The product is processed to produce a defective product. In particular, in the case of large-diameter hardening and wafer prices soaring, the damage caused by such defects is enormous.

According to the present invention, as shown in Fig. 3, the CD dimensions can be predicted by calculation immediately after wafer processing, and the value can be displayed. For example, a predetermined threshold 14 is provided in the CD dimension, and a warning is issued when the thresholds 14 are exceeded (15, 16), thereby minimizing damage due to poor manufacturing. In addition, the maintenance may be performed at an appropriate time by the alarm. The output form of the warning may be an alarm such as a buzzer, a display on the operation panel, a display on the personal computer of the device operator, or the like.

It is also effective to classify the warning level several times in succession, or to accumulate the warning by the integration count of the warning. Even if it is out of the threshold once, if it is returned within the threshold tolerance during the next wafer processing, the construction starts with a light warning, but if it is out of the threshold for 3 consecutive times, it is prohibited to start the construction. Application in device operation may be performed, for example, by performing maintenance or performing an integration count exceeding a predetermined set value when a threshold value is out of a threshold value. In addition, it is preferable to update the correlation in the database by using a predetermined period of time by using a new data.

Next, a second embodiment of the present invention will be described with reference to Figs. In the etching apparatus, as the number of processed sheets increases, the reaction product generated during etching processing adheres to the inner wall of the apparatus and gradually increases the deposition amount. When the amount of deposition increases and reaches a certain film thickness, the adhesion is peeled off and falls on the wafer, causing a pattern short circuit. In order to cope with such a situation, a cleaning operation called so-called wet cleaning is performed, in which the apparatus is regularly opened to the atmosphere to remove deposits by water or an organic solvent. After the wet cleaning, water molecules are adsorbed on the surface of the inner wall of the device or as a result of completely removing the deposits, the surface state of the wall of the device is in an active state. As a result, the release of water molecules into the atmosphere of the treatment chamber and the adsorption and desorption of deposits may become remarkable, and immediately after wet cleaning, CD dimensions and etching rates may change depending on the number of treated sheets. If the machining dimensions are fine, these variance factors will have a significant effect. The present invention is effective for monitoring the fluctuating state, and can be used for the judgment of the start of construction after wet cleaning. This embodiment demonstrates the case where it applies to the monitoring example of an etching rate. Fig. 4 shows the flow of the calculation performed in this embodiment, and Fig. 5 shows the display of the calculation results.

The database unit 13 stores the relational expression (model equation) obtained from the plasma state detection data during etching of the dummy substrate for etching rate measurement in the past, and the value and amount data of the etching rate as the processing result.

After the wet cleaning, the etching of the dummy substrate for etching rate measurement is performed to confirm the etching performance. Here, the signal processing unit 11 calls the relational expression between the plasma state detection data of the dummy substrate and the etching rate to perform the etching process of the dummy substrate. At the end, the etching rate is calculated based on the data sent from the plasma state detecting means 8 and 9 and the model equation. Usually, the etching rate measurement is calculated by measuring the etching residual film with a film thickness meter after etching.

Since the rate measuring wafers are expensive even in the case of dummy wafers, it is common to process the rate measuring wafers at a ratio of one sheet per lot, and to process bare wafers of Si in between. The rate measurement is performed by inserting a rate measuring dummy wafer at several pitches of the Si bare wafer to perform rate measurement, but the product cannot be processed until the result of the rate measurement is confirmed and the recovery of performance is confirmed. As a result of the inspection, if the rate is not the desired value, the lot of the Si bare wafer into which the dummy wafer for rate measurement is inserted is again processed, and remeasurement is performed.

The rate measurement requires a lot of time, such as the time required for conveyance of the wafer to the film thickness inspection apparatus and inspection. In order to perform such inspection, the decrease in productivity by stopping the apparatus is very large. According to the present invention, as shown in Fig. 5, the calculated value of the etching rate can be displayed immediately after the end of etching. In FIG. 5, the figure shows the prediction result which calculated the rate, and the part shown by the arrow 18 between them is the part which etched the Si bare substrate. For example, it is possible to realize efficient production by setting the value 17 of the predetermined etching rate at which the product processing is possible, and notifying the information that can be started when the value falls within the range of the set value 17. As described above, the method of notifying the startable information may be a sound such as a buzzer, a display on the operation panel, a display on the personal computer of the apparatus operator, or the like.

Such a method for monitoring variation in etching rate is also effective for monitoring performance variation due to long-term use of the apparatus. Since etching rate dummy wafers can be etched without performing film thickness inspection, the rate measurement dummy wafer is processed at a predetermined time interval, for example, four times a day. It is possible to determine the device performance and determine whether or not to start drilling. When the etching rate of a desired value is not obtained, maintenance can also be performed immediately, and a means of knowing an appropriate maintenance time may be sufficient.

Next, a third embodiment of the present invention will be described with reference to Figs. As described in the second embodiment, after the wet cleaning, since the deposits on the wall surface in the processing chamber are completely removed, the surface state of the wall surface is active, and the adsorption and desorption of the product by etching is remarkable. As a result, the CD dimensions are often thickly finished immediately after the wet cleaning, and may tend to be slightly changed and stabilized as the number of treated sheets increases. Electrode processing of gate wiring requires accurate dimension management because the dimensions of the wiring width directly affect the operation speed of the device, and the product becomes defective if it cannot be processed to the desired CD dimensions. For this reason, after wet cleaning, a test operation called seasoning for etching a predetermined number of predetermined number of dummy substrates is performed.

After a predetermined number of seasoning treatments, one product is etched and subjected to dimensional inspection by CD-SEM. If the product is within the specified dimensions, the product can be started, but if it is outside the specified dimensions, the product is seasoned again, i.e., a certain number of dummy substrates are processed, and the product is etched and inspected until the specified value is entered. Continue. A large amount of time is used because the next task cannot be performed until the test results are available. Also, if you do not fit in the dimensions of the regulations at once, you will waste the product.

In the present embodiment, it is effective for the start of construction based on the monitoring and monitoring results of such CD dimensions. In this embodiment, an example applied to the start determination by CD monitoring will be described. Fig. 6 shows a flow of calculation performed in this embodiment, and Fig. 7 shows a display example of the calculation result. The dummy substrate is subjected to a condition close to that of the product A at a time close to the time when the product wafer for which the size of the CD is monitored (for example, the product A) is etched with respect to a number of product wafers for a predetermined period of time. The relational expressions (model equations) are generated from the plasma state detection data of the dummy substrate etched at a time close to the CD dimension of the product wafer process, and stored in the database unit 13. In the near term, continuous processing is preferable, but there is no problem if the deviation is several hours.

After the wet cleaning, the dummy substrate is etched, i.e., seasoned, but here, the signal computation unit 11 is etched at a time close to the CD dimension of the product in the past, and the time when the product is etched. When the etching process is completed for each wafer subjected to the seasoning process by calling the relational expression with the plasma state detection data of the wafer, the data sent from the plasma state detecting means 8 and 9 is calculated using the model formula to calculate the CD dimensions. Do it.

Etching is performed on a dummy substrate or a CD dimension of a product etched at about the same time as a dummy substrate that detects a plasma state. Therefore, the calculated value is calculated as a result of processing the product at that time. The predicted value of is calculated. The dummy substrate is preferably the same film material as that of the product. However, in the case of etching polysilicon such as a gate electrode, since the bare Si is a similar material, the plasma state detection data is very similar and can be sufficiently calculated.

That is, according to the present embodiment, even if the product is not etched, for example, the prediction of the CD value when the product A is etched now can be displayed as shown in FIG. 7 by using a dummy substrate. In other words, it is possible to determine whether or not to start the construction even if the inspection by the CD-SEM is not performed by the prediction of the machining result. For example, the predetermined CD dimension value 20 which enables product processing is set, and when it becomes in the range of the set value 20, it can be notified that 19 can be started. As described above, it is possible to realize an extremely efficient production compared to the above-described determination of the groundbreaking by seasoning and CD inspection.

Such a method of monitoring the CD dimension variation can be performed not only after wet cleaning but also when a product having a large etching area is started after starting a product having a different device structure, for example, a product having a small etching area. It is likely to occur because the amount of reaction product changes suddenly. Even in such a case, the method is effective, and as described above, the result of processing in the case of etching the product of the other device structure by etching the bare Si dummy, that is, the CD size can be predicted to determine whether or not to start the construction. As described above, the method of determining whether or not the hole is started by etching the dummy substrate without actually etching the product is very advantageous in terms of time and cost.

This method of monitoring the CD dimension variations is also effective for monitoring performance variations due to long-term use of the apparatus. Etching the dummy wafer makes it possible to estimate the CD dimensions. Therefore, if the dummy wafer is processed at a predetermined time interval, for example, four times a day, the device performance judgment and the start of construction can be determined at that time. .

As the products are processed one after another, deposits adhere to the walls of the apparatus, or the parts are consumed, the plasma state changes, and as a result, the treatment result also changes. Therefore, as in the third embodiment, it is necessary to predict the result of the product wafer from the plasma state in the dummy substrate processing. A large time elapses, i.e., an increase in deposition of sediment on the wall and the progress of component consumption. Therefore, the prediction time of the product wafer processing and the dummy substrate processing should be as close as possible. In the present invention, since data is intentionally collected as a database in advance, it is preferable to perform dummy processing immediately after or immediately before product processing.

However, it is not necessarily just before or immediately after product processing, and the time difference allowed depends on the required precision of the product.

What is important is how much the wall condition and parts consumption have progressed by etching per wafer, and how sensitive the device is to the change. Insensitive products, i.e., products that do not cause problems even if the electrical characteristics change due to a change in the shape shift, and a time when the problem becomes different are different.

In fact, in the case of 0.18 탆 wide polysilicon etching, even if it is empty for several hours to several ten hours, it can be predicted with high precision.

In this embodiment, in the case of polysilicon etching having a width of 0.18 mu m, it could be predicted in the range of ± 5 nm even if the time was left for about 10 hours from the product wafer processing to the dummy substrate processing. This affects how much the wall condition and parts consumption progress by etching per wafer, and how sensitive the device is to the change. You need to collect the database in an hour.

Moreover, such a monitoring method of the CD dimension fluctuation is effective when mixing a small quantity of various kinds of products. For example, when the products A, B, and C having different dimensional precisions are processed by the same apparatus as shown in Fig. 8, the products A and C can be grounded, but the product B exceeds the allowable range of precision and is poor if processed. This situation may occur. In order to avoid the occurrence of such defects, the apparatus state monitoring of whether or not work can be started is usually carried out by performing the above-described etching rate inspection or CD dimension inspection at predetermined intervals. However, such an inspection requires the use of an expensive inspection wafer and a long time required for inspection, thereby lowering the productivity. Will be implemented. In other words, if the product has not passed the inspection, the products A and C may still be produced, but the apparatus is stopped and maintenance is performed. If the work of the product A, C is small, there is no problem, but if there is a lot of work of the product A, C, the production capacity of the entire production line will be reduced.

In such a case, the production management can be carried out efficiently by performing line operation by judging whether or not construction starts according to the present invention. If the database has relations between the plasma state detection data of the dummy substrate and the CD dimension value as a result of the processing for the products A, B, and C, the dummy substrate is etched at that time to determine which product can be grounded. Can be. If the product B cannot be started, only the product B is prohibited to start, the product B is turned to another device, and the products A and C need to continue production. For example, if there is a device 1, a device 2, a device 3 capable of the same processing in the production line, and the processing states of the device 1 and the device 3 are shifted and it is determined that the product B cannot be processed, the device 1 and the device 3 If both stops and enter maintenance, at this point, the entire product will be concentrated on device 2, which significantly reduces production capacity. In such a case, the products A and C which are still groundable in the apparatus 1 and the apparatus 3 are first sent to the apparatus 1 and the apparatus 3, and the product B is processed using the apparatus 2, thereby avoiding stagnation of production. The maintenance of the device 1 and the device 3 may be performed at a stage in which the work capacity of the product is reduced and the device capacity is increased. In this way, it is possible to make appropriate device selection and production line operation according to the performance at that time without inspecting the result of the product processing and without making any defects.

In addition, although the application example to the processing result of a product was demonstrated here, it is effective also about the processing result of the dummy wafer for performance evaluation. As described in the description of the second embodiment, the wafer for etching rate measurement is expensive even if it is a dummy wafer because a film having the same film quality as the product is formed on the Si substrate. At a time close to the time when the number of etch rate measuring wafers were etched for a certain period of time, at a lower cost, for example, when the bare Si wafer was processed to be close to the etch rate measured from the etch rate measuring wafer. Both relational expressions (model equations) are generated from the plasma state detection data of the bare Si subjected to the etching process and stored in the database unit 13. By preparing such a model formula, it becomes possible to determine the performance by a more inexpensive bare Si processing without using an expensive rate measurement dummy substrate. That is, the same effect as in the second embodiment can be obtained with a more inexpensive dummy substrate.

Next, a fourth embodiment of the present invention will be described with reference to Figs. This embodiment describes an example applied to monitoring variation in etching rate, and is particularly effective for monitoring an underlying oxide film etching rate variation during gate electrode processing. 9 is a schematic cross-sectional view of the gate electrode processing for explaining the present embodiment. Here, an example of forming a gate electrode with a polysilicon single layer film will be described. In FIG. 9, 21 is a silicon substrate, 23 is a polysilicon film formed by CVD (Chemical Vapor Deposition), etc. on the board | substrate 1, and becomes a gate electrode. 22 is a gate oxide film, and 24 is a photoresist that opens a region to be processed by etching.

In general, the etching of the gate electrode is not performed by etching polysilicon 23 at once under the same conditions, but first, 1) a step called main etching in which the polysilicon is etched at high speed until several tens of nm is left, and 2) polysilicon ( 23) is a step of completely etching, and the etching rate of the underlying gate oxide film 22 is lower than that of the main etching step, that is, just etching, in which the gate oxide film is hard to be etched even after the etching of the polysilicon is completed. The etching of the steps or residues is also performed at a step called overetching with a low etching rate of the underlying gate oxide film 22.

In the above conditions 2) and 3), although the etching rate of the oxide film is very small, the target gate oxide film 22 is very thin, for example, several nm to 1 nm, so that the etching rate fluctuates even though the rate is small. If so, the gate oxide film 22 is locally etched away, so that a phenomenon called soaking occurs in which a through hole is drilled through the underlying Si substrate. In the above conditions 2) and 3), since the etching rate is low for the gate oxide film but the rate is high for Si, when the gate oxide film is removed, the Si substrate 21 positioned below the gate oxide film 22 is shown. This shaving device does not work normally and becomes defective.

In order to prevent such defects caused by the omission of the gate oxide film, it is common to conduct a rate inspection of the oxide film, such as one sheet per day at a predetermined interval. The rate inspection is performed by actually etching the silicon oxide film using the rate measurement substrate in which the film thickness on the Si substrate is deposited. For example, if something changes in the plasma state of the device between the rate test and the rate test and the rate rises, the abnormality of the gate oxide film is removed until the next rate test. Product processing is performed. The result is bad products, and the damage is huge. In addition, since the rate inspection board | substrate needs to form a silicon oxide film on a Si substrate, it is expensive as a test | inspection wafer. That is, if the variation in the etching rate of the gate oxide film can be monitored by the information from the plasma state detection data during the product processing without performing such a rate inspection, it is possible to eliminate the production of defective products without consuming an expensive rate measurement substrate. Etc., a great effect can be obtained.

That is, the gate oxide film 22 is chipped as a result of the complete etching of the polysilicon 23 provided thereon, resulting in local pitting in the form of pinholes. ), But it is very difficult to actually measure at the rate in the actual product in order to detect the defect by such omission. According to the present invention, by using the etching rate of the dummy substrate as an index for the determination of the start or absence, it is possible to judge the occurrence of the pinhole without actually measuring it.

The characteristics of this embodiment are effective when the specific amount of quantitative values such as the etching amount and the etching rate cannot be evaluated as described above, and the etching amount and the etching rate of the dummy must be evaluated as an index. It is a separate effect.

Such an application is effective not only for the gate oxide film but also for the rate prediction of the film located above and below the film for processing, such as the rate prediction of the resist mask and the rate prediction of the hard mask.

While the etching target film is being etched, it is obvious that the mask and the mask are also etched. The resist, hard mask material and the etching target film are set so that the selectivity is taken to some extent, that is, the etching rate of the mask <the rate of the target film, but it is difficult to set the etching rate of the mask to zero. Here, when the etching rate fluctuates and the rate rises, the mask is shaved, and the finished shape is contracted and the edge is shaved, and the edge shaping of polysilicon occurs, which adversely affects the device characteristics, resulting in a defect. In this case as well, the etching of the mask is not the purpose, and as a result, the mask is cut, and the index of the etching amount of the mask is that the etching rate will be what if the etching rate wafer of the current mask material is etched now. It is necessary to judge the grounding by using the etching amount and the etching rate as an index.

In the case of the single layer film as described above, the layer of W (tungsten) / polysilicon is more complicated. That is, since the conditions for etching tungsten and the conditions for etching polysilicon are different, the etching rate in each is different, and in the ordinary inspection process, the rate inspection of the mask is constant under the etching conditions (tungsten ⇒ polysilicon both etching). Although the interval pitch or the like is performed once a day, when a rate abnormality occurs, there is a drawback that either condition is not known. In the case of the present invention, the tungsten and polysilicon are etched and the rate measurement results and the plasma state can be used to predict the rate when the rate measurement dummy is etched for each of them, so that the abnormality can be corrected quickly. do. Thus, according to this embodiment, other effects can also be expected.

FIG. 10 shows an example of the operation flow performed in the present embodiment, and FIG. 11 shows an example of the result of the operation result. Treatment of a rate measuring substrate in which a film of the same material as that of the gate oxide film is formed under conditions close to the just etch step or the over etch step of the product A near the time when the wafer of the product, for example, product A is etched. Then, the etching rate is measured. As described in the description of the above embodiment, the close time is preferably continuous processing, but there is no problem if the deviation is about several hours. In addition, it is not necessarily the same as the just etch step or the over etch process, and the result of etching the dummy substrate under a condition that the oxide film rate is increased to some extent so as to amplify the rate variation of the oxide film, or to increase the time. It is easy to calculate the rate at which one starts later. This is because the etching rate of the oxide film in the just etch stage or over etch stage which is a problem is very small, so that the variation is hardly seen.

The database unit 13 stores the relational expression (model expression) of both from the above-described data of the etching rate during the rate measurement dummy substrate etching, the plasma state detection data of the product wafer processing, and the amount data. The plasma state detection data of the product wafer is a plasma when the gate oxide film is etched after the polysilicon has been etched. Thus, in the just etch step, data after the etching of the polysilicon is finished, that is, data before the end of the just etch step. Create a model expression using the, or over-etch data. When the product A is grounded, the plasma state detection means (8, 9) when the etching process of the product A is finished by invoking the relational expression between the plasma state detection data and the data of the etching rate at the time of dummy substrate etching from the database unit to the signal calculation unit. The data sent from the datasheet is calculated using the relational formula called from the database unit to the signal computation unit to calculate the etching rate. The value calculated here is, for example, an etching rate when the dummy substrate on which the film of the same material as that of the gate oxide film is formed is etched under conditions similar to the just etch step or over etch treatment of the product A.

As described above, according to the present invention, even if the dummy substrate is not etched, as shown in FIG. 11, the value can be displayed by calculating the etching rate in the case where the rate measurement of the dummy substrate is performed at that time, for example. For example, an upper limit is provided in the calculated value of the etching rate of the dummy substrate, and a warning can be issued when the deviation is out of the range of the set value 24, thereby minimizing the damage caused by creating a defect and maintaining it. It is also possible to carry out at an appropriate time. Similarly to the first embodiment, it is also effective to classify the warning level by how many times the threshold value is exceeded or by the integration frequency of the warning. For example, if it escapes from the threshold once and then returns (27), the construction starts as a light warning, but if it is out of the threshold three times consecutively (28), the construction is prohibited and maintenance is performed. When the number of times of integration in which the threshold value is out of the threshold exceeds a predetermined set value, it is possible to apply maintenance or the like.

As described above, according to the present invention, the processing result is derived from the plasma state detection data completed by the current processing after the wafer processing and the correlation using the relational expression that correlates the past wafer processing result information with the plasma state detection data during the wafer processing. Since the predicted value of can be calculated, the defect caused by the change in the processing state can be checked quickly, and the damage caused by the defect manufacturing caused without knowing the change in the processing state can be minimized. In addition, the effect that maintenance can be performed at an appropriate time is also obtained.

In addition, according to the present invention, since the predicted value of the processing result when the product is processed, for example, can now be calculated from the plasma state detection data due to the dummy substrate discharge, whether or not the desired processing result is obtained without processing and inspecting the product. Can be judged. Thereby, the effect that the waiting time by the inspection time, the labor of the inspection and the time can be omitted without wasting the product.

Claims (10)

delete delete delete A plasma processing apparatus having a control chamber and a processing chamber for performing plasma processing on a wafer, The processing chamber is provided with plasma state detecting means for detecting a processing state inside the processing chamber and outputting a plurality of output signals, The control section stores a function of correlating information of past wafer processing results with plasma state detection data during past wafer processing and both of them, from the processing chamber state detection results from the plasma state detecting means and the relational expressions. A function of calculating a predicted value of the processing result, and a function of evaluating a processing chamber state based on the calculated predicted value of the processing result, The dummy substrate is processed under conditions close to the product processing at a time close to the time when the product wafer processing is performed. The control unit of the processing apparatus stores the relational expression for correlating the information of the dummy substrate processing result with the plasma state detection data during product wafer processing, and both. From the plasma state detection data from the plasma state detection means at the time of product processing, the predicted value of the result when the dummy substrate is processed at that time is calculated from the relational expression, and the process room state is evaluated from the calculated predicted value of the processed result. Plasma processing apparatus characterized by. delete delete delete delete In the plasma processing method of the plasma processing apparatus of claim 4, 12. A plasma processing method characterized in that a dummy substrate is processed under conditions close to product processing, and a subsequent product wafer is not processed when the calculated processing predicted value is equal to or larger than a preset threshold. A plasma processing apparatus having a control chamber and a processing chamber for performing plasma processing on a wafer, The processing chamber is provided with plasma state detecting means for detecting a processing state inside the processing chamber and outputting a plurality of output signals, The control section stores a function of correlating information of past wafer processing results with plasma state detection data during past wafer processing and both of them, from the processing chamber state detection results from the plasma state detecting means and the relational expressions. A function of calculating a predicted value of the processing result, and a function of evaluating a processing chamber state based on the calculated predicted value of the processing result, The dummy substrate is processed, The control unit stores the information of the dummy substrate processing result based on the past approximation condition and the plasma state detection data and the relational expression which correlate both at the same time as the past dummy substrate processing, And a predicted value of the processing result from the plasma state detection data from the plasma state detecting means at the time of dummy substrate processing and the relational expression, and evaluating the processing chamber state from the calculated predicted value of the processing result.

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