JP4409744B2 - Etching process progress display method and etching process monitoring apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides an etching process for accurately measuring and displaying the progress of an etching process for patterning a thin film formed on a substrate, such as when creating a photomask for manufacturing a semiconductor device (device). The present invention relates to a progress measurement display method and apparatus.
[0002]
[Prior art]
Conventionally, for example, in the manufacturing process of a semiconductor device, etching is performed to pattern various thin films on a semiconductor substrate, and used to pattern a photoresist (photosensitive resin) prior to the etching process. Etching is also performed in the process of creating the photomask.
Etching in the process of creating a photomask for manufacturing a semiconductor device is performed for the purpose of transmitting light by forming a pattern of through holes in a metal thin film coated on a glass substrate.
[0003]
Therefore, for example, as shown in FIG. 13, a metal (for example, chromium: Cr) thin film 101 is formed on the entire surface of the glass substrate 100, a photoresist 102 is applied thereon, and exposure and exposure are performed using electron beam lithography or photolithography. Development is performed to form through holes 102a having a required pattern shape.
As a result, the portion to be removed of the metal thin film 101 is exposed, and the other portion is covered with the photoresist 102.
[0004]
Accordingly, when the exposed portion of the metal thin film 101 is peeled and dissolved by immersing it in an acid reactive with the metal thin film 101 which is a material to be processed, or by irradiating reactive ions in the same manner, a desired pattern is formed on the metal thin film 101. Through holes are formed. FIG. 13 shows a state where the exposed portion of the metal thin film 101 is being etched by the etching gas 103.
Of course, the photoresist 102 has no reactivity with the above-mentioned acid or ions, or even if it is a little compared with the metal thin film 101 to be processed.
[0005]
[Problems to be solved by the invention]
In order to know the progress of such an etching process, conventionally, the type of a substance that is peeled and dissolved by etching is specified, and the amount and light transmittance are measured. In other words, the situation where etching is almost completed and the amount of processed material is reduced, the moment when a new material is peeled and dissolved, and the situation where there is a slight hole (breakthrough point) at the beginning and the light transmittance varies greatly. Etc. were obtained by spectroscopic measurement or chemical concentration measurement.
[0006]
For example, in the case of the etching process shown in FIG. 13, when the metal thin film 101 is peeled up to the surface of the glass substrate 100, the transmittance of light entering from the upper surface side increases rapidly. The situation just before the end can be predicted, and other situations can be estimated. This method is generally called endpoint detection because it is performed by detecting an endpoint where the light transmittance rapidly increases.
[0007]
Further, when the pattern shape is to be controlled, it is performed according to an empirically determined etching time. This etching processing time is empirically determined from the type and amount of the substance to be removed, the etching gas, etc., so the etching time is slightly corrected according to the empirical rule at the time of endpoint measurement. The end point is determined, and the shape of the pattern formed thereby is controlled.
[0008]
For example, in the case of using an ionized gas by plasma at the time of etching with a photomask, the fluctuation of light transmittance due to the plasma emission is measured.
That is, as shown in FIG. 14A, since the light emitted by the plasma emission 104 in the etching gas 103 is blocked only by the metal thin film 101 that is the etching target film, the optical sensor 106 is provided below the glass substrate 100. Is arranged to measure the intensity of light leaking through the hole 101a formed in the metal thin film 101, and to control the pattern shape from the change.
[0009]
At this time, the time when the first small hole is formed is the breakthrough point tp shown in FIG. 14B, and the time when the hole having almost the same size as the photoresist 102 is formed is the end point te. It is.
Therefore, in order to observe the progress of the etching process, conventionally, it has been necessary to rely on a method of capturing breakthrough points and end points and correcting them based on empirical rules.
[0010]
Therefore, in the conventional method, it is only possible to grasp the first and last situations, it is difficult to accurately grasp the situation in the middle, and it is difficult to quantitatively control the etching process.
As described above, it is not easy to observe the progress of the etching process, and there is a problem that it is particularly difficult to accurately grasp the progress of plasma etching used for fine processing.
[0011]
The semiconductor device has a tendency that the line width gradually becomes finer, and as the miniaturization progresses, the allowable error becomes smaller. For this reason, there is an urgent need to precisely control the pattern dimensions by accurately grasping the progress of the etching process, and there are devices and equipment that can finely control the etching process while observing (monitoring) the entire etching process. A method is desired.
[0012]
The present invention has been made in order to meet such a demand, and allows fine processing of a semiconductor device to be easily performed by finely controlling the progress while observing the progress of the entire etching process. With the goal.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an etching process progress display method and an etching process monitoring apparatus as described below.
An etching process progress display method according to the present invention is a method for displaying the progress of an etching process for forming a pattern on a metal thin film formed on a substrate, wherein the elapsed time of the etching process is a variable, and the metal Light is applied to the non-etched portion and the etched portion of the thin film, and the intensity of reflected light that interferes with each other from both portions is detected.
[0014]
Then, based on the detected intensity of the reflected light, using the elapsed time of the etching process as a variable, the depth at which the etched portion is etched is calculated, and based on the calculated etched depth, At each etching depth The peeling dissolution rate in the film thickness direction of the etched portion of the metal thin film is calculated.
In this way Calculate the etched depth and the film thickness direction. Peeling dissolution rate and Based on a given rate of separation and dissolution in the width direction of the etched portion of the metal thin film and an ion distribution density of an etching gas obtained by processing a function indicating the shape of the etched portion with a given low-pass filter. , By calculating to what part of the above metal thin film has been peeled and dissolved at each time point, the calculation results Based on the above, the process in which the etched portion of the metal thin film is dissolved momentarily is displayed on the display.
[0015]
Fluctuation value of the intensity of reflected light detected using the elapsed time of the etching process as a variable, and the depth at which the etched portion calculated using the elapsed time of the etching process as a variable is etched. And the above for each etching depth calculated based on the etched depth Peeling dissolution rate in the film thickness direction And information on etching conditions Is edited into a predetermined format and stored as a database, and the etched depth , Peel dissolution rate And etching condition information Based on the above, the process of dissolving the etched portion of the metal thin film from moment to moment may be continuously displayed on the display.
[0016]
An etching process monitoring apparatus according to the present invention is an apparatus for monitoring the progress of an etching process for forming a pattern on a metal thin film formed on a substrate, and using the elapsed time of the etching process as a variable, Reflected light intensity detecting means for irradiating the etching part and the etching part with light and detecting the intensity of the reflected light that interferes with each other from both parts.
[0017]
Then, based on the intensity of the reflected light detected by the reflected light intensity detecting means, an etching depth calculating means for calculating the etching depth of the etched portion using the elapsed time of the etching process as a variable, and the means Based on the calculated etched depth, At each etching depth A peeling dissolution rate calculating means for calculating a peeling dissolution rate in the film thickness direction of the etched portion of the metal thin film.
[0018]
Further, the etching depth calculating means and the peeling dissolution rate calculating means Calculated by the above Etching depth And in the film thickness direction Peeling dissolution rate and Based on a given rate of separation and dissolution in the width direction of the etched portion of the metal thin film and an ion distribution density of an etching gas obtained by processing a function indicating the shape of the etched portion with a given low-pass filter. , By calculating to what part of the above metal thin film has been peeled and dissolved at each time point, the calculation results And an etching process display means for continuously displaying on the display a process in which the etched portion of the metal thin film is dissolved every moment.
[0019]
Further, the etching process monitor device includes the reflected light intensity fluctuation value detected by the reflected light intensity detection means as a variable, and the etching depth calculation. By means Calculate time of etching process as a variable did Depth at which the etched part was etched And the above-mentioned at each etching depth calculated by the peeling dissolution rate calculating means based on the etched depth Peeling dissolution rate in the film thickness direction And information on etching conditions It is preferable to provide a database creation means for editing the data into a predetermined format and storing it as a database.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The method and apparatus for displaying the progress of the etching process according to the present invention is a method and apparatus for measuring and displaying the situation in which a material to be processed is removed by etching, and displaying it. A phenomenon is used in which the intensity of light reflected from a material to be changed changes according to the progress of the etching process.
[0021]
Here, as shown in FIG. 1, the metal thin film 2 formed on the upper surface of the glass substrate 1 is coated with a photoresist 3 on the upper surface to form a desired pattern, and then the photoresist 3 is used as a mask. Consider the case where the metal thin film 2 is etched to form the same pattern as the photoresist 3 by performing the etching process.
[0022]
Attention is focused on the reflected light when monochromatic light enters from the upper surface side of the glass substrate 1 through the etching gas 103 and the photoresist 3. In this case, the phase of the incident light 4 as well as the reflected light 5 from the portion (non-etched portion) 2a that is not removed by the etching of the metal thin film 2 is substantially constant throughout the entire etching process.
However, the phase of the reflected light 6 from the portion (etching portion) 2b, which is removed by etching of the metal thin film 2 and the film thickness changes every moment (etching portion) 2b, changes depending on the progress of etching. Change.
[0023]
Therefore, when the reflected light 5 and the reflected light 6 are collected by the lens 7 as shown in FIG. 2 and the intensity thereof is measured by the sensor 8, the reflected light 5 and the reflected light 6 interfere with each other because they have a phase shift. In addition, the intensity of light output from the lens 7 changes due to weakening or strengthening as the etching depth d of the etching portion 2b of the metal thin film 2 changes. The intensity change of the light is detected by converting it into an electric signal by the sensor 8 using a photoelectric conversion element such as a photodiode.
[0024]
Then, based on the electrical signal corresponding to the light intensity, the thickness of the etching portion 2b of the metal thin film 2 that changes every moment and the etching rate (the thickness of the metal thin film 2 that is peeled and dissolved per unit time; hereinafter “peeling” The dissolution rate can be calculated, and the etching process can be simulated or the result can be visualized and displayed based on the peeling dissolution rate.
[0025]
Incidentally, the etching depth of the metal thin film 2 is d, the thickness of the photoresist 3 is Δ, and the refractive index is n. ₁ And the refractive index of the etching gas (or etching solution) is n ₂ Assuming that the wavelength of the incident light is λ, the phase difference θ between the reflected light 5 and the reflected light 6 is approximated by ignoring multiple reflections.
θ = 4π {(Δ + d) n ₂ -N ₁ Δ} / λ
Given in. In this phase difference θ, since items other than d are constant values during the etching process, the phase difference θ is a function of the etching depth d, and a change in the phase difference θ indicates a change in the etching depth d. It will be.
[0026]
The intensity of the reflected light is cos ² It is empirically known to change in proportion to θ. Therefore, if the phase difference θ changes, the intensity of the reflected light also changes, but the intensity of the reflected light (hereinafter referred to as “reflection intensity”) changes as shown in FIG. 3 according to the etching depth d. Therefore, the etching depth d can be obtained by measuring the reflection intensity.
[0027]
This etching depth d does not change (decrease) at a constant rate in the entire etching process. If the etching depth d changes at a constant rate, the etching depth d can be obtained only by the processing time from the start of etching, and thus the etching process can be easily controlled.
[0028]
However, in the actual etching process, for example, in the case of dry etching, the peeling dissolution rate fluctuates from moment to moment due to various factors such as high frequency output, temperature and etching gas concentration. The rate of change of the etching depth d also varies from moment to moment. Therefore, the actual measurement value of the reflection intensity is given as a fluctuation value (rate of fluctuation) of the reflection intensity with respect to a certain time.
[0029]
FIG. 4 shows an example of measurement data of the reflection intensity actually obtained. From the relationship between the reflection intensity and the etching depth d shown in FIG. 3 and the relationship between the elapsed time of the etching process and the reflection intensity shown in FIG. 4, the etching depth d at a certain time can be grasped.
[0030]
For example, the reflection intensity at time t (about 45 seconds in the figure) in FIG. 4 is about 0.8. Then, in FIG. 3, when the film thickness at which the reflection intensity is 0.8 at the second time is obtained, it is about 0.188 (micron). Thus, the etching depth d in every moment during the etching process is grasped, and the change can be known by repeatedly obtaining the etching depth d.
[0031]
FIG. 5 shows the change in the etching depth d obtained in this way. As shown in this figure, the etching depth d does not show a linear change with respect to time. The etching depth d is a constant value that does not change after the time point tp. 5 and 4 is referred to as a breakthrough point as described above, and is the time when the metal thin film 2 as the etching target film shown in FIG. 2 is first etched to the surface of the glass substrate 1. It represents.
[0032]
If the metal thin film 2 is etched up to the surface of the glass substrate 1, the etching depth d will not be deeper than the original metal thin film 2, so that the fluctuation of the light intensity due to interference stops. This tp can be used as an important parameter for controlling the etching process.
[0033]
Next, since the etching depth d is obtained every moment as described above, the peeling dissolution rate of the metal thin film 2 at a certain time in the etching process (the film of the metal thin film 2 removed by etching per unit time) Thickness) Vt can be obtained. That is, Vt is
Vt = (Z ₂ -Z ₁ ) / (T ₂ -T ₁ )
Can be obtained as Here, t ₁ , T ₂ Are different times in the immediate vicinity with time t in between, Z ₁ , Z ₂ Is the time t ₁ , T ₂ Is the measured etching depth.
[0034]
Further, since the etching depth d at a certain time is obtained from FIG. 5, the peeling dissolution rate Vz at the certain etching depth d is also obtained. However, in this case, as shown in FIG. 6, with respect to the glass substrate 1, the depth direction is the Z direction, the width direction perpendicular thereto is the X direction, and the position of the metal thin film 2 at the start of etching is the origin in the Z direction. The Z-direction peeling dissolution rate Vz is a peeling dissolution rate in the etching depth of the metal thin film 2 (depth measured from the surface of the metal thin film 2 toward the surface of the glass substrate 1).
[0035]
Now, when the peeling dissolution rate Vz is measured in this way, the progress of the etching process is grasped, so that the progress can be displayed to simulate the etching process. Therefore, a simulation method for the etching process will be described below.
According to this simulation method, it is possible to display the state in real time while actually performing the etching.
[0036]
FIG. 7 shows the situation at one time point of the simulation by the progress status display method of the etching process according to the present invention.
Note that the display of FIG. 7 is shown with the vertical and horizontal dimension ratios changed for easy viewing, and in particular, the thickness of the chromium (Cr) film that is the metal thin film 2 described above is enlarged.
[0037]
In order to be able to perform such a simulation, the etching rate Vz in the depth direction must be given in advance for all etching depths. Therefore, in the following description, it is assumed that the etching rate Vz is obtained for all the etching depths d of the metal thin film 2 according to the method described above.
[0038]
First, as shown in FIG. 8, the entire metal thin film 2 as an etching film is divided into lattice-like minute regions (hereinafter referred to as “cells”), the coordinates of each region are determined, and the depth z for each cell. The peeling dissolution rate (etching rate) Vz is given accordingly. Next, the ion distribution density D (x) of the etching gas is given for each cell. The ion distribution density D (x) is a function that takes a value from 0 to 1 as shown in the upper side of FIG. 8, and is almost “1” at the opening of the photoresist 3. This is a function that is almost “0” in the covered portion.
[0039]
Ideally, the rectangular function is “1” at the opening and “0” at the covering, but actually the opening is smaller than 1 near the wall surface of the photoresist 3. Yes. Accordingly, it is assumed that the actual ion distribution density D (x) can be obtained from this ideal rectangular function through a low-pass filter, and the parameters of the low-pass filter are determined from experiments.
[0040]
As a result, the effective etching speed V (x, z) at the position (x, z) is
V (x, z) = D (x) · Vz
As required. However, the etching rate V (x, z) is a peeling dissolution rate in the Z direction.
[0041]
When etching is started, the surface of the metal thin film 2, that is, the coordinate x in the width direction (X-axis direction) at z = 1. ₁ In the cell, the etching rate (thickness of the metal thin film 2 removed by etching per unit time) is V (x ₁ , 1), it is dissolved in a minute time Δt determined by the following equation.
Δt = Δz / V (x ₁ , 1)
Here, Δz is the thickness (length) in the Z direction in each cell of the metal thin film 2.
If the thickness of the metal thin film 2 is L and the number of cells divided in the Z direction is N, Δz is expressed by the following equation.
Δz = L / N
[0042]
The position coordinates of each cell of the metal thin film 2 can be generally expressed as P (x, z). However, when the contact surface with the etching gas is considered for the cell at the coordinate position P (x, z), the progress of etching Thus, three forms as shown in FIGS. 9A, 9B and 9C can be considered. Among these, (A) shows a case where only one surface of the cell at the coordinate position P is in contact with the etching gas G, (B) shows a case where two surfaces of the upper surface and one side surface are in contact with the etching gas G, and (C) shows This is a case where the top surface and both sides of the cell are in contact with the etching gas G. When the etching further proceeds from the state (C), the four surfaces of the cell come into contact with the etching gas G, and the cell is released. Note that the front and back surfaces of the cell in the figure also come into contact with the etching gas as the etching progresses, but the illustration is omitted here.
[0043]
On the other hand, the etching rate in the vertical (depth) direction is given by V (x, z) as described above, but the etching rate in the horizontal (width) direction is the same for all the cells and given by Ux. And This Ux is determined by the etching apparatus, its arrangement, the substance to be etched, the etching gas, etc., and is determined experimentally. In general, the value of Ux is smaller than Vz, and particularly close to zero in the case of anisotropic etching. Further, in terms of the effective value of the etching rate, in FIG. 9, in the case of (A), it is Vz, but in the case of (B), it becomes the combined rate of Vz and Ux, and in the case of (C) Becomes the combined speed of Vz and 2Ux.
[0044]
In this way, the cell of the metal thin film 2 that peels and dissolves every minute time can be obtained by calculation, and the progress of etching can be displayed while removing the cell. This calculation technique is called the “cell removal method”, but other methods can also be used. For example, there is a “ray trace method”.
[0045]
In this way, the process of peeling and dissolving the metal thin film 2 from time to time is displayed continuously, the progress of etching is displayed as a movie, and the progress of etching is actually seen with the eyes. Can be displayed. At the same time, the simulation result itself can be controlled by feeding back the simulation result to the etching apparatus.
[0046]
In the course of etching, the photoresist 3 and the glass substrate 1 may be slightly dissolved and peeled off. In order to perform the simulation of the process, it is assumed that the photoresist 3 and the glass substrate 1 also have the peeling dissolution rate (etching rate) in the vertical (depth) direction and the horizontal (width) direction, similarly to the metal thin film 2. Calculate it.
[0047]
Measurement data, etching conditions, simulation results, and the like in the course of such etching can be saved as a database by editing and recording them in a predetermined format.
Therefore, if the stored database is used, the etching process under the same conditions as the contents has repeatability that allows the simulation to be repeated any number of times and reproducibility that can be performed again. Further, in the case of new etching conditions different from the previous conditions, it is sufficient to select and use a similar etching condition from the past etching processes. Then, a new simulation can be performed by performing an interpolation operation or an interpolation operation.
[0048]
Measurement data and the like based on the actual progress of etching can be sequentially added to this database, so that the contents of the database can be made more precise. As described above, according to the etching progress display method according to the present invention, the entire process from the beginning to the end of the etching process can be observed in a pseudo manner, and the etching process can be precisely controlled. Become.
[0049]
Next, an etching system for carrying out the etching progress process display method according to the present invention described above will be described.
FIG. 10 is a block diagram showing an example of an etching system provided with an etching monitor device according to the present invention.
This system includes a plasma etching device 20, an etching process monitoring device 30, and a PC control device. A probe 22 is attached to the lower part of the process chamber 21 of the plasma etching apparatus 20 and is connected to the etching process monitoring apparatus 30 by an optical fiber 23.
[0050]
Further, a pipe provided with a pressure control valve 25 from a vacuum pump 24 is connected to the process chamber 21. Further, a pipe from the gas box 26 is also connected. The vacuum pump 24, the pressure control valve 25, and the gas box 26 are connected to the PC control device 40 by a signal line 51, and the etching process monitor device 30 and the PC control device 40 are also connected by an interface cable 52. .
[0051]
The etching process monitoring device 30 is provided with a lamp power supply unit 31, a light detection unit 32, a calculation control unit 33, a monitor display 34, a database creation unit 35, and the like.
The PC controller 40 includes a process recipe monitor, a simulation I / O, a sequence I / O, an MFC that is a flow rate controller that automatically supplies gas, and an APC that is a controller that controls the pressure in the process chamber 21. In addition, a high frequency control device for plasma generation and RF as a power supply device, a vacuum pump remote controller, and the like are provided.
[0052]
An RF electrode 27 for ionizing an etching gas is provided in the process chamber 21, and an RF power source 29 is connected to the RF electrode 27 via an RF matching capacitor 28. High frequency power is applied to the electrode 27.
In the process chamber 21, a photomask 10, which is a thin metal plate to be etched, is disposed close to and parallel to the RF electrode 27.
And as shown in FIG. 11, the probe 22 for phase difference measurement is arrange | positioned so that the process surface 10a of the photomask 10 formed in the glass substrate 1 may be opposed.
[0053]
The probe 22 is provided to irradiate the processing surface 10a of the photomask 10 with light, detect the reflected light, and measure the processing depth based on the intensity thereof.
FIG. 12 shows the configuration of the probe 22 and related parts in the etching process monitoring apparatus 30 shown in FIG.
[0054]
A projection objective lens 220 is provided in the probe 22, and a lamp 221 that is a light source, a collimator lens 222, and a beam splitter are provided in an etching process monitoring device 30 connected to the probe 22 via an optical fiber 23. 224, optical fibers 233a and 233b, an interference filter 226, and an optical sensor 227 are provided. The lamp 221 is controlled to be turned on by the lamp power supply unit 31, and the optical sensor 227 is operated by the light detection unit 32 and the detection signal is processed.
[0055]
The light emitted by the lamp 221 is converted into a parallel light beam by the collimator lens 222, enters the optical fiber 23 from the beam splitter 224 through the optical fiber 223a, is guided to the probe 22 by the optical fiber 23, and is projected into the projection objective lens 220. By this, the processed surface of the photomask 10 being processed is irradiated.
[0056]
The reflected light from the processed surface 10a enters the optical fiber 23 from the same projection objective lens 220 of the probe 22, is guided to the etching process monitoring device 30 by the optical fiber 23, and is an interference filter from the beam splitter 224 by the optical fiber 223b. It is guided to H.226 and is thereby monochromatized to irradiate the photosensor 227. The optical sensor 227 outputs an electrical signal corresponding to the intensity of the irradiated light.
[0057]
As described above with reference to FIG. 2, the interference between the reflected light from the portion that is coated with the photoresist 3 on the processed surface 10a of the photomask 10 and is not etched and the reflected light from the portion that is not coated and etched. The intensity of the reflected light changes, which depends on the processing depth. Accordingly, a signal corresponding to the machining depth of the machining surface 10a is output from the optical sensor 227.
[0058]
The output signal of the optical sensor 227 is amplified by the light detection unit 32, then A / D converted to digital data, the data is taken into the arithmetic control unit 33, and data collection, analysis, simulation, etc. are performed. The progress of the etching process from moment to moment is displayed as a moving image on the monitor display 34.
Further, the data can be sent to the PC controller 40 to automatically control the etching process.
Further, the input data of the etching conditions and the simulation data of the actual etching process can be registered as a database by the database creation unit 35.
[0059]
That is, the database creation unit 35 calculates the fluctuation value of the intensity of the reflected light detected by the probe 22 that is the reflected light intensity detection means and the light detection unit 32 during the etching process, the etching depth calculation means, and the peeling dissolution rate calculation. The arithmetic control unit 33 also serving as a means edits data such as an etching depth and a peeling dissolution rate in the film thickness direction calculated using the elapsed time name of the etching process as a variable into a predetermined format and stores it as a database. As the memory, a hard disk or a magneto-optical disk having a large storage capacity is used.
[0060]
Accordingly, if the etching process is the same as the previously registered etching condition, it is possible to perform simulation using the registered data.
The present invention functions effectively for almost all etching processes, is used in semiconductor manufacturing processes and other fine etching processes, and is effective regardless of the type of etching such as dry etching or wet etching. Is something.
[0061]
【The invention's effect】
As described above, according to the present invention, the progress of the etching process that changes from moment to moment can be displayed as a movie, and the progress of the etching is displayed as if it were actually seen. Simulation can be realized. Further, the etching process can be automatically controlled using the data.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining an etching process as an object of the present invention.
FIG. 2 is an explanatory diagram of a method for detecting an etching depth according to the present invention.
FIG. 3 is a diagram showing the relationship between the etching depth of a metal thin film and the intensity of reflected light.
FIG. 4 is a diagram showing measured values of the relationship between the elapsed time of the etching process and the reflected light intensity.
FIG. 5 is a diagram showing a relationship between an elapsed time of an etching process and a metal thin film etching depth.
FIG. 6 is a cross-sectional view for explaining a direction in which a metal thin film is peeled and dissolved.
FIG. 7 is a cross-sectional view showing a display example of temporary points by a method for displaying the progress of an etching process according to the present invention.
FIG. 8 is a diagram showing an ion distribution density for a metal thin film to be etched and an etching rate for each of the regions obtained by dividing the metal thin film into lattice-like minute regions (cells).
FIG. 9 is a diagram schematically showing a state of a contact surface with an etching gas in each region of the metal thin film.
FIG. 10 is a block diagram showing an example of an etching system provided with an etching process monitoring device according to the present invention.
11 is a diagram showing the relationship between the photomask shown in FIG. 10 and a probe.
12 is a diagram showing details of the relationship between the photomask and the probe shown in FIG. 10 and a configuration example of reflection intensity detection means.
FIG. 13 is a cross-sectional view showing a state in the middle of an etching process for creating a photomask.
FIG. 14 is a diagram for explaining an example of a conventional method for detecting an etching state.
[Explanation of symbols]
1: Glass substrate 2: Metal thin film
2a: non-etched part 2b: etched part
3: Photoresist 4: Incident light
5, 6: Reflected light 7: Lens
8: Sensor 10: Photomask
20: Plasma etching apparatus
21: Process chamber 22: Probe
23: Optical fiber 24: Vacuum pump
25: Pressure control valve 26: Gas box
27: RF electrode
28: Capacitor for RF matching
29: RF power supply 30: Etching process monitoring device
31: Lamp power supply unit 32: Light detection unit
33: Calculation control unit 34: Monitor display
35: Database creation department
40: PC controller 51: Signal line
52: Interface cable
113, G: Etching gas
220: Projection objective 221: Lamp
222: Collimating lens
223a, 223b: optical fiber
224: Beam splitter
226: Interference filter 227: Optical sensor

Claims (4)

A method of displaying the progress of an etching process for forming a pattern on a metal thin film formed on a substrate,
Using the elapsed time of the etching process as a variable, irradiating the non-etched part and the etched part of the metal thin film with light, and detecting the intensity of reflected light that interferes with each other from both parts,
Based on the intensity of the detected reflected light, using the elapsed time of the etching process as a variable, the depth at which the etched portion is etched is calculated,
Based on the calculated etched depth , calculate the peeling dissolution rate in the film thickness direction of the etched portion of the metal thin film at each etching depth ,
Given the calculated depth and rate of stripping dissolution in the film thickness direction , the given stripping dissolution rate in the width direction of the etched portion of the metal thin film, and a function indicating the shape of the etched portion Based on the ion distribution density of the etching gas obtained by processing with a low-pass filter, it is obtained by calculation to which part of the metal thin film has been peeled and dissolved at each time point, and based on the calculation result , A method of displaying the progress of an etching process, characterized by continuously displaying on the display a process in which the etching part dissolves momentarily. A method of displaying the progress of the etching process according to claim 1,
A variation value of the intensity of the reflected light detected using the elapsed time of the etching process as a variable, a depth at which the etched portion calculated using the elapsed time of the etching process as a variable , and the etched depth The peeling dissolution rate in the film thickness direction at each etching depth calculated based on the information and the etching condition information are edited into a predetermined format and stored as a database, and the etched depth , peeling dissolution rate, and A process for displaying the progress of an etching process, characterized in that, on the basis of information on etching conditions, a process in which the etched portion of the metal thin film is dissolved every moment is continuously displayed on a display. An apparatus for monitoring the progress of an etching process for forming a pattern on a metal thin film formed on a substrate,
Reflected light intensity detecting means for irradiating light to the non-etched part and the etched part of the metal thin film, using the elapsed time of the etching process as a variable, and detecting the intensity of reflected light that interferes with each other,
Based on the intensity of the reflected light detected by the means, the etching depth calculating means for calculating the etching depth of the etched portion using the elapsed time of the etching process as a variable;
A peeling dissolution rate calculating means for calculating a peeling dissolution rate in the film thickness direction of the etched portion of the metal thin film at each etching depth based on the etched depth calculated by the means;
The etching depth and the peeling dissolution rate in the film thickness direction calculated by the etching depth calculation means and the peeling dissolution rate calculation means , and the peeling dissolution rate in the width direction of the etched portion of the metal thin film, Based on the ion distribution density of the etching gas obtained by processing the function indicating the shape of the etched portion with a given low-pass filter, to which part of the metal thin film is peeled and dissolved at each time point is calculated. And an etching process display means for continuously displaying, on the display, a process in which the etching portion of the metal thin film dissolves momentarily on the basis of the calculation result . An etching process monitoring device according to claim 3 ,
The reflected light intensity fluctuation value detected by the reflected light intensity detection means as a variable and the etching portion calculated by the etching depth calculation means by using the etching process time as a variable were etched. The film thickness direction peeling dissolution rate at each etching depth calculated by the peeling dissolution rate calculation means based on the etched depth and the information on the etching conditions are edited in a predetermined format. An etching process monitoring apparatus characterized by comprising database creating means for storing as a database.

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