JP2004253516A - Dry etching method and apparatus for test sample - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable for processing method of a low dielectric constant film used for dual-damascene. <P>SOLUTION: Etching is continued while a process recipe is controlled with a signal processing of reflected interference light on the wafer surface and an increase in roughness on the wafer surface during the etching is suppressed. Namely, the dry etching method for the dry etching apparatus comprising a means for processing a test sample by generating plasma within a vacuum processing chamber and a monitor means for monitoring the reflected interference light of the test sample to be processed. This dry etching process comprises the steps of detecting the reflection interference light spectrum at the surface of the test sample to be processed, obtaining a remaining difference in curve fitting for a logical value forecasted with a reflection model of the film at the wafer surface, and determining whether the remaining difference in curve fitting is within the predetermined range or not. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing method and a dry etching apparatus for a sample such as a semiconductor integrated circuit, and more particularly to a dry etching method and a dry etching apparatus suitable for processing an insulating film material having a low dielectric constant.
[0002]
[Prior art]
In a semiconductor integrated device, the capacitance between adjacent wirings becomes relatively large in a wiring portion with miniaturization. If a conventional silicon oxide film is used as an insulating material between the wirings, the speed of the transistor obtained by the miniaturization can be increased. Will not be able to enjoy the benefits of For this reason, a material having a low dielectric constant (k value) is used as an inter-wire insulating material.
[0003]
Since these materials are mainly used in combination with copper as a wiring material and are formed by a dual damascene method, a process of etching an insulating film is required. The dual damascene formation step includes, for example, a step of processing and transferring a groove shape to a porous insulating film using a hard mask on a sample whose hole shape has been processed in the previous step to obtain a predetermined shape. Such a technique is disclosed in Patent Document 1, for example.
[0004]
Conventionally, when a process with a small margin (margin) due to miniaturization is applied, a method of periodically performing cleaning and cleaning processing of a chamber using a QC method to obtain a reproduction stability of the processing is adopted. . Further, a method of monitoring a process state and controlling the process is also employed.
[0005]
As a method of monitoring the process state and controlling the process, there is known a method disclosed in Patent Document 2 in which reflected interference light from a processing wafer is monitored and the etching process is stopped.
[0006]
However, the process conditions required for normal processing are not only becoming more severe with miniaturization, but are becoming even more severe with the following specific phenomenon accompanying porous formation. The introduction of materials having a low dielectric constant (k value) is progressing with miniaturization, and in order to further lower the dielectric constant, a material called a porous insulating film in which holes are introduced in a material called a porous insulating film is also used.
[0007]
Further, in the related art, after the etching is completed, the mask material is removed using another vacuum container or another device in the same device. For example, Patent Document 3 discloses a technique for removing an etching residue, a resist surface hardened layer, and the like by wet processing.
[0008]
[Patent Document 1]
JP-A-9-115878
[Patent Document 2]
USP 5,658,418
[Patent Document 3]
JP 2000-352827 A
[0009]
[Problems to be solved by the invention]
A process having a small margin is susceptible to the influence of the surface state of the chamber, the area to be etched of the processing wafer, and the like.
[0010]
In particular, in the etching of an insulating film having a hole in a material, the effect of the geometric structure of the hole appears even though it is minute. The difference between the case with and without holes will be conceptually compared using FIG. When there is no vacancy in the material, as shown in FIG. 12A, the angle α formed by the etched surface 122 of the material 120 with respect to ions having a certain incident angle is, of course, different on a horizontal plane. At positions S1 and S2, they are all the same, for example, 90 degrees. On the other hand, when there is a hole 124 in the material 120, the angle α formed by the etched surface 122 with respect to the ions at different positions S1 and S2 on the horizontal plane is different as shown in FIG. A case occurs. On the other hand, the etching rate shows different values for ions having different incident angles. As a result, for the material having the holes 124, the effect of the holes is emphasized.
[0011]
Looking at the scale of the pattern to be processed, as shown in FIG. 13, when the groove shape is etched in the porous insulating film 120 on the base film 134 using the hard mask 130, the surface of the groove shape is roughened during the etching. 132 occurs and it grows. Then, finally, a plurality of residues 140 as shown in FIG. 14 remain on the bottom surface of the etched groove.
[0012]
Since the residue 140 causes a defective embedding in the metal deposition in the next step and cannot be removed by washing, it is necessary to completely remove the residue 140 in the etching step. As a countermeasure in the etching process, it is possible to reduce the amount to some extent by increasing the over-etching time. However, as the over-etching time increases, the shoulder of the hard mask is more likely to be scraped, which causes a reduction in yield such as a short circuit between wirings. An increase in the over-etching time also causes penetration of the base film 134, an error in the processing dimension, and the like, and a countermeasure in the etching process is required.
[0013]
In order to achieve both residue-free processing and high-accuracy pattern transfer, the neutral radical deposition component and the etch component are balanced. However, the external controllability of neutral radicals is not sufficient to a required level, and a QC method must be introduced. That is, it is necessary to have a method of statistically grasping the influence of the influence and actually processing and confirming the test wafer at a cycle in which the safety factor is expected.
[0014]
However, with the further reduction of the margin accompanying the miniaturization, the frequency of management has increased, the number of confirmed wafers has also increased, and a rise in cost has been a problem.
[0015]
An object of the present invention is to provide a dry etching method and a dry etching apparatus for a sample, which can provide stable processing when etching a sample, particularly a low dielectric constant film used in a dual damascene, and do not increase the cost. Is to do.
[0016]
It is another object of the present invention to provide a dry etching method and a dry etching apparatus for a sample, which can provide stable processing when etching a sample, particularly a porous insulating film, and do not increase the cost. .
[0017]
[Means for Solving the Problems]
The present invention is characterized in that a process recipe is controlled by performing signal processing on reflected interference light on a wafer surface, and etching is advanced while suppressing an increase in roughness of the wafer surface during etching.
[0018]
A more specific feature of the present invention is that a dry etching apparatus including a means for generating plasma in a vacuum processing chamber to process a sample and a monitor means for monitoring reflected interference light of the sample to be processed is provided. Detecting a reflected interference light spectrum at a surface of the sample to be processed, and calculating a curve fitting residual of the reflected interference light spectrum with respect to a theoretical value predicted by a reflection model of a film on a wafer surface. A dry etching method for a sample includes a step of determining and a step of determining whether the curve fitting residual is within a predetermined range.
[0019]
Another more specific feature of the present invention is a dry etching apparatus including a means for generating a plasma in a vacuum processing chamber to process a sample, and a monitor for monitoring reflected interference light of the sample to be processed. Means for detecting a reflection interference light spectrum on the surface of the sample to be processed, and means for obtaining a curve fitting residual of the reflection interference light spectrum with respect to a theoretical value predicted by a reflection model of a film on the sample surface. And a means for determining whether the curve fitting residual is within a predetermined range.
[0020]
According to the present invention, the interference reflected light intensity spectrum from the wafer surface is monitored for a fitting residual when comparing the interference reflected light intensity spectrum expected from the film structure of the wafer surface, and its value, or time-dependent, Change the processing method according to the fluctuation.
[0021]
In order to suppress surface roughness during etching, the dependence of the etching rate on the incident angle of the ion, which is the cause, may be reduced. However, this is to increase the etching rate of ions obliquely incident on the surface to be processed vertically, which tends to lead to processing defects such as side etching.
[0022]
In the present invention, a neutral and non-directional depot radical and a plurality of process recipes in which etch radicals are balanced are constructed in advance, and the applied recipe is changed while auditing the state of the wafer surface, thereby eliminating residues. A good processed shape could be obtained. Thereby, the etching process of the low dielectric constant insulating film can be stably performed with low production quality control cost.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention will be disclosed below with an example using a UHF-ECR type vacuum processing apparatus. FIG. 1 shows a schematic sectional view of a vacuum processing apparatus to which an embodiment of the present invention is applied. The vacuum processing apparatus 100 includes a plurality of vacuum processing chambers (plasma processing chambers) 1, a vacuum transfer chamber, and a pair of lock chambers. The vacuum processing apparatus 100 is an ECR type vacuum processing apparatus that emits electromagnetic waves from an antenna and generates plasma by interaction with a magnetic field. An antenna 6 made of AL and a quartz window 2 are provided at an upper portion of each vacuum processing chamber 1 to allow a UHF electromagnetic field to pass into the vacuum processing chamber 1. A UHF power supply 9 for generating a UHF electromagnetic wave having a frequency of, for example, 450 MHz is connected to the antenna 6 via a coaxial waveguide and a matching device. A solenoid coil 7 for forming a magnetic field in the vacuum processing chamber 1 is wound around the outer periphery of the vacuum processing chamber 1.
[0024]
In the vacuum processing chamber 1, a lower electrode 3 for mounting a wafer 4 as a sample having a semiconductor integrated circuit is provided. The quartz window 2 and the lower electrode 3 are adjusted so as to have an interval of about 30 mm to 100 mm. This space between the quartz window 2 and the lower electrode 3 becomes a processing space, and plasma is generated in this processing space.
[0025]
The lower electrode 3 is connected to a high frequency bias power supply 5 for giving the ions in the plasma incident energy to the wafer 4 and an ESC power supply (not shown) for electrostatically attracting the wafer 4 to the lower electrode 3. ing. The frequency of the high-frequency bias power supply 5 is not particularly limited, but is usually in the range of 200 kHz to 20 MHz. An exhaust port is provided in the lower part of the vacuum processing chamber 1, and an exhaust device not shown is connected.
[0026]
Reference numeral 10 denotes a reflected light intensity monitoring device, which monitors a temporal change in reflected light intensity of plasma light on the surface of the wafer 4 in a wavelength range from 300 nm to 800 nm. Reference numeral 11 denotes a plasma light monitoring device that monitors plasma light while avoiding reflected light on the wafer surface. The outputs of the monitor devices 10 and 11 are processed by the arithmetic processing unit 12 by a predetermined method. The arithmetic processing unit 12 controls a series of processes for processing a wafer in the vacuum processing apparatus. Reference numeral 14 denotes a controller of a gas supply device that supplies a processing gas into the vacuum processing chamber 1. The gas supplied from the mass flow controller 14 according to the etching recipe is uniformly introduced into the vacuum processing chamber 1 through the gas dispersion plate 8. The recipe selection control unit 13 controls the output power of the UHF power supply 9 and the flow rate of the mass flow controller 14 according to a predetermined recipe. The control device including the arithmetic processing unit 12 performs arithmetic processing necessary for the recipe selection determination, and outputs the result to the recipe selection control unit 13.
[0027]
At the lock chamber side of the vacuum processing apparatus 100, an atmospheric transfer device having a transfer robot is disposed, and further, a cassette table on which a plurality of cassettes can be disposed is disposed. In addition, an inspection device is provided in the atmosphere transfer device and the vacuum processing device 1. The measurement result of the inspection device is taken into the control device, and the processing condition of the wafer in the vacuum processing chamber is adjusted by the etching condition adjusting unit of the control device based on the measurement result.
[0028]
The control device includes, for example, a computer including a CPU, a memory, a program, an external storage device, and input / output means, and controls the vacuum processing device 100. In the inspection device, the thickness (CD gain) from the design value of the processing line width is measured by the length measurement SEM. This measurement is performed for each wafer or for each predetermined number as necessary, and the data is stored in a storage device in the control device. The CD gain has a predetermined allowable value, and the initial etching conditions, that is, the etching processing conditions at the start of the lot processing, are set so that the CD gain falls within the allowable value. Here, when a number of wafers are continuously processed, and the CD gain exceeds the allowable value, the data signal is sent to an etching condition adjusting unit in the control device, and the CD gain is set to the allowable value by the etching condition adjusting unit. The conditions are automatically adjusted to be within the range, and the control apparatus changes and adjusts the etching processing conditions in the processing chamber of the vacuum processing apparatus. The inspection device also inspects the status of the residue on each of the processed wafers one by one, and determines the quality of the wafer. As a result of the inspection, rejected wafers having large residues are rejected and are not sent to the next processing step. On the other hand, the inspection information is also reflected in the next processing step for a wafer that has passed the inspection result. For example, for a wafer that passes the inspection but has a relatively large residue, a correction process is performed in the next step in consideration of the residue.
[0029]
The input / output means of the control device includes a display unit, and displays the status of the residue for each wafer, the pass / fail of the inspection, the current operation recipe, and the like.
[0030]
Next, the processing contents of the arithmetic processing unit 12 and the recipe selection control unit 13 will be described with reference to FIGS.
[0031]
FIG. 2 is a functional block diagram of the arithmetic processing unit 12 and the recipe selection control unit 13. In FIG. 2, first, the arithmetic processing unit 12 obtains standard recipe data for vacuum processing chamber operation from the recipe selection control unit 13 and controls a series of processes for wafer processing in the vacuum processing chamber 1. . The wafer 4 is etched in the vacuum processing chamber 1 using plasma by a standard recipe. Plasma light and reflected light accompanying the processing of the wafer 4 are monitored and sent to the plasma light arithmetic processing unit 12. In the plasma light arithmetic processing unit 12, the reflectance spectrum calculation unit 21 normalizes the signal of the reflected light intensity monitor 10 with the signal of the plasma light intensity monitor 11, and converts the reflectance spectrum actually measured for a plurality of wavelengths. calculate. On the other hand, the model prediction spectrum calculation unit 22 calculates a predicted model prediction spectrum from a known model of the film structure of the wafer.
[0032]
FIG. 3 shows an example of the relationship between the normalized reflectance of the actually measured reflectance spectrum and the normalized reflectance of the model predicted spectrum predicted from the film structure model on the wafer.
[0033]
Next, in the fitting processing unit 23, fitting processing is performed so that the actually measured reflectance spectrum is likely to match the model predicted spectrum.
[0034]
The error between the spectra (fitting residual D) at the place where fitting is performed so as to match is output to the recipe selection control unit 13, and its absolute value or temporal variation value is compared with the set value by the comparison determination unit 24. Is done. Based on this result, it is determined whether or not the recipe selection should be changed. That is, the state of the chamber such as the wall surface of the vacuum processing chamber 1 is estimated from the absolute value or the temporal variation value, and a comparison is made to determine whether the variation is within an allowable range.
[0035]
FIG. 4 shows an example of a time chart of the fitting residual and the applied recipe. First, as shown in FIG. 4A, the fitting residual D and the surface roughness of the processed sample are substantially inversely proportional.
[0036]
Next, FIG. 4B shows that, when the fitting residual D is equal to or less than the first allowable value DL1, the operation is performed with the “standard recipe”, and the fitting residual D exceeds the first allowable value DL1 and the second residual value DL1 exceeds the first allowable value DL1. Indicates that the operation is performed in the “recovery recipe 1”. When the fitting residual D exceeds the second allowable value DL2, "cleaning" of the vacuum processing chamber is performed, and thereafter, the operation is restarted with the "standard recipe".
[0037]
FIG. 4C shows that, in the range where the fitting residual D is equal to or less than the first allowable value DL1, the operation is performed using the “standard recipe”, and the fitting residual D exceeds the first allowable value DL1 and the second allowable value DL1. In the range of DL2 or less, it is indicated that the operation is performed in the “recovery recipe 2”. “Recovery recipe 2” is an operation recipe that also has a function of “cleaning” the vacuum processing chamber.
[0038]
As described above, when the absolute value or the fluctuation value of the fitting residual D exceeds the allowable range DL, an appropriate recipe held in the recipe selection unit 25 is selected, and the wafer in the vacuum processing chamber 1 is selected. The process conditions for the processing are changed from the standard recipe to the recovery recipe 1 or 2.
[0039]
Next, examples of a plurality of recipes stored in the recipe selection unit 25 will be described.
(A) Standard recipe 1: H2 / N2 = 100/300
Power for generating plasma (UHF) = 800 W
(B) Recovery recipe 1: Increase the flow rate of H2 by 20%
(C) Recovery recipe 2: 25% increase in power (UHF)
The recovery recipes 1 and 2 increase the isotropic etching rate, and have a tendency of side etching with respect to the standard recipe 1. In this way, a process in which neutral and non-directional depot radicals and etch radicals are slightly balanced is constructed.
[0040]
The process of processing the wafer 4 is likely to shift under the influence of the surface condition of the vacuum processing chamber 1 or the effect of the area to be etched of the processed wafer, so that careful management of the process reproducibility is required.
[0041]
FIG. 5 shows an example of a correlation between the processed state of the sample and three different recipes applied to the two states of the vacuum processing chamber 1.
[0042]
Generally, for the chamber state 1 which is a relatively clean state after the vacuum processing chamber 1 is cleaned, the processing can be performed in a normal shape without any residue by applying the standard recipe 1. In other words, when the vacuum processing chamber 1 is processed under the “standard recipe” in a “state 1”, for example, in a state in which no foreign matter is adhered to the inner wall surface, for example, immediately after the cleaning, and the operation is performed under the normal conditions, the groove shape on the sample surface is obtained. Becomes a regular shape.
[0043]
Further, when a plurality of samples are processed and in the “state 2” in which foreign matter adheres to the inner wall of the vacuum processing chamber 1 and the processing is performed according to the “standard recipe”, a residue remains in the groove shape on the sample surface. However, if the operation is performed in the “recovery recipe 1” or the “recovery recipe 2” in the vacuum processing chamber 1 or the “state 2”, the residue is removed and the groove shape on the sample surface becomes a regular shape.
[0044]
However, when the recovery recipe 1 or the recovery recipe 2 is applied to the chamber state 1, although there is no residue, side etching is observed in the processed shape, and this is likely to cause a defect by embedding in the next step.
[0045]
On the other hand, in the chamber state 2 in which the processing is repeated for a while after the cleaning, a residue is generated if the standard recipe is used, but normal processing can be performed by applying the recovery recipe 1 or 2.
If the residual is out of the predetermined range and the effect of residue reduction is not recognized even if the recovery recipe 1 or the recovery recipe 2 is continuously applied, the wafer is removed for safety. It is preferable to stop the process 4 and perform cleaning.
[0046]
FIG. 6 shows a flowchart of the process in the embodiment of the present invention. First, an operation recipe having contents corresponding to the processing process of the wafer 4 is appropriately set (602). Then, after the processing wafer is carried into the processing chamber (604), etching is started by the standard recipe (606 to 608). During the etching, the fitting residual is monitored and output from the arithmetic processing unit 12 as needed, and the residual D is determined (610 to 614).
[0047]
If it is determined that the surface of the wafer is rough and the fitting residual is large, it is determined that the chamber state has changed, and a recovery recipe 1 or 2 is selected (616), and processing is performed until the etching end point. After processing, the wafer is unloaded. For the next wafer, the etching is started by the standard recipe, and when the fitting residual becomes large, the recovery recipe 1 or 2 is selected and the processing is performed until the etching end point (618). Hereinafter, the same processing for each wafer is repeated until the processing of the wafer to be processed by the process under the same conditions is completed (604 to 624).
[0048]
Next, FIG. 7 illustrates a part of a dual damascene forming process targeted by the present invention. As described above, introduction of a material having a low dielectric constant (k value) as an inter-wiring insulating material is progressing, and in order to further lower the dielectric constant, a material having pores introduced in a material called a porous insulating film is also used. Have been. These materials are mainly used in combination with copper as a wiring material, and are formed by a dual damascene method, so that a process of etching an insulating film is required. That is, as shown in FIG. 7A, a groove shape 708 is process-transferred to a porous insulating film 706 using a hard mask 704 on a sample 700 having a hole shape 702 processed in a previous step. 701 is a base insulating film.
[0049]
In the etching of the insulating film having holes, the influence of the geometrical structure of the holes appears even though they are fine, and as shown in FIG. 7B, the surface is roughened 730 during the etching. . Therefore, it is necessary to proceed with etching while suppressing an increase in surface roughness during etching. In order to suppress the surface roughness 730 during the etching, the dependency of the etching rate on the incident angle of the ion, which is the cause, may be reduced. The recovery recipes 1 and 2 increase the isotropic etching rate due to radicals and tend to be side-etched. In this way, a process in which neutral and non-directional depot radicals and etch radicals are balanced is constructed.
[0050]
Therefore, when it is determined that the fitting residual is large corresponding to the roughness of the wafer surface, the recovery recipe 1 or 2 is selected and the processing is performed up to the etching end point.
[0051]
In this manner, a good groove processed shape 740 having no residue as shown in FIG. 7C was obtained.
According to the present invention, even in the processing of a porous insulating film having a small process margin, it is possible to detect a rough surface leading to a residue in order to prevent a residue defect and to control a recipe change by the same, thereby achieving vacuum processing. Control of the state change of the room becomes possible. As a result, there is an effect that a semiconductor integrated circuit can be manufactured at low cost.
[0052]
An embodiment of the present invention will be described with reference to FIGS.
[0053]
<Example 1>
First, as one embodiment of the present invention, using the UHF-ECR type vacuum processing apparatus described in FIG. 1, 50 wafers having the same mask pattern with an organic insulating film having holes and a relative dielectric constant of 2.2 are used. Was continuously etched. When the processed wafers were inspected, the first to 27th wafers passed the residue defect inspection, but the 28th and subsequent wafers failed.
[0054]
The data continuously collected and recorded by the monitor devices 10 and 11 were processed and analyzed by 12 signal processing units. As a result of the analysis, as shown in FIG. 8, the fitting coefficient with respect to the predicted value of the film thickness model starts to change in the latter half of the etching processing of the 25th wafer, and the fluctuation gradually increases in subsequent wafers, and further processing is repeated. Was repeated in a state where the fluctuation range was saturated.
[0055]
<Example 2>
Next, as another embodiment of the present invention, when a deviation of the fitting value is detected, control using a recovery recipe 1 in which an etching gas flow rate is increased by a predetermined amount is performed with respect to a standard recipe. 50 samples of the same sample were continuously processed in the same manner. As a result, as shown in FIG. 9, the recovery control did not work for the first to 24th wafers. However, the recovery control was activated from the 25th sheet, and the etching process was performed with the recipe in which the gas flow rate was increased. For the 25th and subsequent wafers, the fitting coefficient D gradually returned after the recovery control worked, and returned to a value less than the allowable range DL before the start of etching at the end point of the etching.
[0056]
Residual defect inspection was performed on 50 wafers in this continuous process, and all passed with a residual amount equal to or less than the specified value DL.
[0057]
<Example 3>
Next, as another example of the present invention, an etching process was performed on 50 samples having different mask patterns from those described above using the control method and the recovery recipe 1 of the present invention. In this case, as shown in FIG. 10, the application of the recovery recipe started from the 35th wafer and continued until the last 50th wafer. Residues and dimensional inspection were performed on 50 wafers after processing, and all the wafers met the criteria and passed.
[0058]
Next, as a recovery recipe, recovery recipe 2 for increasing UHF power, which is plasma generation power, from a standard recipe was applied. Using this and the control of the present invention, continuous processing was performed on the first 50 samples. At this time, as shown in FIG. 10, the control was periodically performed on the twelfth, twenty-fourth, thirty-sixth, and forty-eighth sheets. Similarly, when 50 samples of this sample were inspected for residue and dimensions, all passed. It is considered that the reason why the control occurred intermittently, unlike the previous embodiment, was that the recovery recipe 2 in which the UHF power was increased returned to the initial state after cleaning not only to the wafer surface but also to the chamber state. .
[0059]
As is apparent from these examples, according to the present invention, it is possible to produce fine semiconductor integrated circuits with high yield without the need for QC work which requires a lot of cost.
[0060]
In the embodiment of the present invention, the reflected light of the plasma light is used as the reflected light on the wafer. However, the reflected light may be used by using a plurality of different light sources. Is within. Further, the vacuum processing apparatus is not limited to the UHF-ECR type, and can be applied to vacuum processing apparatuses of other types.
[0061]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, plasma processing of a sample, especially a low dielectric constant insulating film can be performed stably with low production quality control cost.
[Brief description of the drawings]
FIG. 1 is a sectional structural view of a vacuum processing apparatus used in an embodiment of the present invention.
FIG. 2 is a diagram showing a block diagram for extracting a fitting residual and a recipe selection control diagram in the embodiment of FIG. 1;
FIG. 3 is a diagram showing a relationship between a measured spectrum and a predicted spectrum of a reflectance spectrum in the embodiment of FIG. 1;
FIG. 4 is a diagram showing an example of a relationship between a fitting residual and a surface roughness and a relationship between a fitting residual and an applied recipe time chart in the embodiment of FIG. 1;
FIG. 5 is a diagram showing a chamber state and a processing result of an applied recipe in the embodiment of FIG. 1;
FIG. 6 is a flowchart of process control in the embodiment of FIG.
FIG. 7 is a view for explaining a sample processing step in the embodiment of FIG. 1;
FIG. 8 is a diagram showing a change in fitting residual when a residue defect occurs.
FIG. 9 is a diagram for explaining the effect of the first embodiment of the present invention by using a change in fitting residual;
FIG. 10 is a diagram for explaining the effect of the second embodiment of the present invention by a change in fitting residual;
FIG. 11 is a diagram for explaining the effect of the third embodiment of the present invention using a change in fitting residual;
FIG. 12 is a diagram illustrating a difference in etching depending on the presence or absence of a hole.
FIG. 13 is a diagram illustrating surface roughness during etching.
FIG. 14 is a diagram illustrating generation of residues after etching.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vacuum processing chamber, 2 ... Quartz window, 3 ... Lower electrode, 4 ... Wafer, 5 ... High frequency bias power supply, 6 ... Antenna, 7 ... Solenoid coil, 8 ... Gas dispersion plate, 9 ... UHF power supply, 10 ... Reflected light Intensity monitoring device, 11: Plasma light monitoring device, 12: Operation processing unit, 13: Recipe selection control unit, 14: Mass flow controller, 21: Reflectance spectrum calculation unit, 22: Model prediction spectrum calculation unit, 23: Fitting processing unit , 24... Comparison / decision unit, 25... Recipe selection unit, 100.

Claims (15)

A dry etching method in a dry etching apparatus including means for processing a sample by generating plasma in a vacuum processing chamber, and monitoring means for monitoring reflected interference light of the sample to be processed,
Detecting a reflected interference light spectrum at the surface of the sample to be processed, and determining a curve fitting residual of the reflected interference light spectrum with respect to a theoretical value predicted by a reflection model of a film on the sample surface;
Determining whether the curve fitting residual is within a predetermined range. 2. The dry etching method according to claim 1, wherein when the residual deviates from a predetermined range, a processing method of the sample is changed. 3. The dry etching method according to claim 2, wherein the change in the method for processing the sample includes a change in power for generating the plasma. 3. The dry etching method according to claim 2, wherein changing the method of processing the sample includes changing a flow rate of a processing gas for generating the plasma. 2. The dry etching method according to claim 1, wherein the processing of the sample is stopped when the residual is out of a predetermined range. Monitor the fitting residual when comparing the interference reflection light intensity spectrum on the sample surface with the interference reflection light intensity spectrum expected from the film structure on the sample surface,
The monitor value or the reflected interference light is signal-processed by the temporal change of the monitor value, and the processing method of the sample is changed during etching based on the result of the signal processing, thereby increasing the roughness of the sample surface. Suppress, dry etching method. 7. The dry etching method according to claim 1, wherein a neutral and non-directional deposition radical and an etching radical are balanced to control the surface roughness of the sample so as to fall within a predetermined range. 7. The dry etching method according to claim 1, further comprising the step of displaying whether or not the surface roughness of the sample is within a predetermined range and displaying a change in the processing method of the sample on a display unit. 7. The dry etching method according to claim 1, wherein when the residual is within a predetermined range, a process of correcting the residue in a next dry etching apparatus step using information on the residue. 7. The dry etching method according to claim 1, wherein the processing of the sample is etching of an insulating film having holes in the material. A dry etching apparatus comprising: means for processing a sample by generating plasma in a vacuum processing chamber; andmonitor means for monitoring reflected interference light of the sample to be processed,
Means for detecting the reflected interference light spectrum at the surface of the sample to be processed;
Means for determining a curve fitting residual for the theoretical value predicted by a reflection model of the film on the sample surface of the reflected interference light spectrum,
Means for determining whether the curve fitting residual is within a predetermined range. 12. The dry etching apparatus according to claim 11, further comprising means for changing a processing method of the sample when the residual is out of a predetermined range. 13. The dry etching apparatus according to claim 12, wherein the means for changing the processing method of the sample includes information on a plurality of operation recipes having different etching processing conditions and a means for outputting any one of the operation recipes. The means for obtaining a curve fitting residual of the reflected interference light spectrum with respect to a theoretical value predicted by a reflection model of a film on a sample surface according to claim 11,
Means for normalizing the signal of the reflected light intensity monitor with the signal of the plasma light intensity monitor and calculating a reflectance spectrum actually measured for a plurality of wavelengths;
Means for performing a fitting process so that the actually measured reflectance spectrum matches the model predicted spectrum. 12. The dry etching apparatus according to claim 11, further comprising: a display unit that displays a result of determining whether the curve fitting residual is within a predetermined range and a change in a method of processing the sample.

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