JPH0427120A - End-point detection method and device - Google Patents

Abstract

PURPOSE:To enable end-point judgment such as etching treatment and thin-film formation treatment to be performed objectively and accurately by registering an image information when treatment is completed as a reference image information previously and by comparing the reference image information and an image information of an object to be treated during treatment for determining end- point of the treatment. CONSTITUTION:An image of an object to be treated 10 at an end-point in etching under same conditions of the object to be treated 10 is taken. A reference image information for a registration memory 23 is set at an image-pocessing part 22. Actual etching treatment is started. An end-point detection device 20 reads an image (observed image information) of the object to be treated 10 into the image-processing part 22. It is written into a data memory 24 and a pattern comparison part 25 compares data within the registration memory 23 and that within the data memory 24, thus calculating agreement of both. If a signal output part 7 determines that agreement of both is lower than a threshold, end-point detection operation is repeated. When the threshold is exceeded, the end-point detection signal is output and etching regarding the object to be treated 10 is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to end point detection technology, and in particular, to end point detection technology that is effective when applied to end point detection of processes such as dry etching and thin film formation in the manufacture of semiconductor integrated circuit devices. Regarding technology.

[Conventional technology]

For example, in the field of manufacturing semiconductor integrated circuit devices, dry etching technology is often used in the process of forming fine circuit patterns.

That is, after a thin film made of a desired substance is deposited on the entire main surface of a semiconductor substrate, it is masked with a photoresist in a desired pattern, and the area exposed from this mask is exposed to excited active etching gas, ions, etc. The desired circuit structure is formed by selectively removing the substrate by exposing it to an etching species to allow an etching reaction to proceed.

By the way, in such dry etching technology, it is important to accurately grasp the point at which the etching of the target thin film is completed (end point) in order to completely remove the thin film and prevent damage to the underlying pattern. becomes important.

For this reason, conventional methods have focused on reaction products specific to the material to be etched, which occur during the etching reaction.
It is common practice to determine the end point of an etching process by observing changes in the intensity of the emission spectrum specific to the reaction product.

Regarding the general etching end point determination technology, for example, see "Very LSI Technology 4JP," published June 1, 1981.
It is described in the process evaluation items of 243-P245.

[Problem to be solved by the invention]

However, with the above-mentioned conventional technology, which observes the emission spectrum specific to the material to be etched, it is difficult to detect When the total area is small and the amount of reaction products generated is small, there is a problem that the detection level of the emission spectrum becomes low and becomes susceptible to noise and the like, reducing the accuracy of end point determination.

In addition, the above method cannot be used when the etching reaction process is unknown and the emission spectrum effective for end point detection is unknown, such as when etching a new substance at the testing/research stage. There is also the problem that it is impossible to objectively evaluate the etching process because it is necessary to rely on visual judgment.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an end point determination technique that can objectively and accurately determine the end point of etching processing, thin film forming processing, etc.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application! ! If you do this, you will see the following.

That is, in the end point detection method of the present invention, image information of the object to be processed at the time of completion of processing is registered in advance as reference image information, and this registered reference image information and image information of the object to be processed during processing are used. The end point of the process is determined by comparing the .

Further, the end point detection device according to the present invention includes a camera that detects image information of the object to be processed, an image processing unit that extracts desired feature information from the image information, and a first feature information that serves as a reference. a first memory in which feature information is stored; a second memory in which second feature information extracted from image information of the object being processed is stored; A matching unit that compares the first and second feature information in the data to determine the degree of matching between the two; and a determination section that determines the end point.

[Effect]

According to the above-described end point detection method of the present invention, the end point of the process is determined based on the image information of the actual object to be processed at the time of completion of the process. End point detection accuracy is not affected by the size of the etching area, unlike when using intensity changes in the emission spectrum of reaction products specific to a specific etching reaction, and the end point of a desired process can be detected with high precision. In addition, even if the reaction products specific to a particular treatment reaction are unknown, the end point of the treatment can be objectively detected.

In addition, in the case of thin film formation processing, the thickness of the film can be determined objectively based on changes in the appearance of the processed object as the thin film grows, and the thickness of the thin film reaches the desired value. It is possible to accurately and objectively detect the end point of the process to determine whether or not the process has been completed.

Further, according to the end point detection device according to the present invention, for example,
By storing the image information of the actual object to be processed at the time of completion of processing in the first memory as the first feature information serving as a reference, and determining the end point of the processing based on this, for example, The end point detection accuracy is not affected by the size of the etching area, as is the case when using changes in the intensity of the emission spectrum of reaction products. Even if the reaction products specific to the treatment reaction are unknown, the end point of the treatment can be objectively detected.

In addition, in the case of thin film formation processing, the thickness of the film can be determined objectively based on changes in the appearance of the processed object as the thin film grows, and the thickness of the thin film reaches the desired value. It is possible to accurately and objectively detect the end point of the process to determine whether or not the process has been completed.

[Embodiment 1] Hereinafter, an example of an end point detection device which is an embodiment of the present invention will be described in detail with reference to the drawings.

In this embodiment, as an example, a case will be described in which an end point detection device is attached to a dry etching device.

FIG. 1 is a sectional view schematically showing an example of a configuration in which an end point detection device according to an embodiment of the present invention is mounted on a dry etching device.

The dry etching apparatus in this embodiment includes a housing 1,
For example, it is made of quartz or the like and has a substantially hemispherical shape, and includes a Pelger 2 that forms a reaction chamber R by closely contacting the housing 1 via a flange portion 2a.

Inside the reaction chamber R composed of the Pelger 2 and the casing 1, a workpiece 10 made of, for example, a semiconductor wafer is placed, which is moved up and down by a drive mechanism (not shown) provided in the casing 1. A sample stage 3 is provided.

In addition, microwaves μ of a desired wavelength are applied to the reaction chamber R from a microwave source (not shown) at a position surrounding the Pelger 2.
A waveguide 4 that guides the inside of the reaction chamber R, and a coil 5 that forms a desired magnetic field inside the reaction chamber R are arranged.

Furthermore, inside the housing 1, a gate mechanism 6 that can be opened and closed is provided on a wall surrounding the sample stage 3.

Further, near the outside of this gate mechanism 6, a loader 7 and an unloader 8 are arranged at positions sandwiching the reaction chamber R, and when the sample stage 3 is lowered to the height of the gate mechanism 6, the gate mechanism 6, the workpiece 10 is carried into and out of the reaction chamber R.

A plurality of gas supply pipes 1a communicating with each of a plurality of gas supply holes 2b penetrated through the side wall of the Pelger 2 are provided in the part of the casing l where the Pelger 2 is in close contact with the outside. The structure is such that a reaction gas G having a desired composition and flow rate obtained from a gas source (not shown) is supplied into the reaction chamber R at any time.

In addition, an exhaust port 1b connected to a vacuum pump (not shown) is provided at the bottom of the casing 1 constituting the reaction chamber R. The structure is such that reaction products, waste gas, etc. generated in the etching process are discharged to the outside.

An observation window 4a is formed in the upper part of the waveguide 4 that guides the microwave μ into the reaction chamber R at a position where the object to be processed 10 inside the reaction chamber R can be seen. The state of the object to be processed 10 can be observed.

In this case, a camera 21, which is composed of, for example, an industrial television camera and constitutes a part of the end point detection device 20, is disposed outside the observation window 4a, and the camera 21 is arranged outside the observation window 4a. It is now possible to import images.

The end point detection device 20 includes the camera 21, an image processing section 22, a registration memory 23, a data memory 24, a pattern matching section 25, a monitor 26, and a signal output section 27.

The image processing unit 22 extracts desired characteristic information from the image of the object to be processed 10 obtained through the camera 21, and stores it in the registration memory 23, data memory 24, etc. as necessary. . For example, the registration memory 23 stores desired reference image information regarding the workpiece 10 at the end point of etching, and the data memory 24 stores the image of the workpiece 10 that changes from time to time during the etching process. Observation image information obtained by capturing at a sampling period is stored.

The pattern matching section 25 also matches the reference image information and observed image information stored in the registration memory 23 and the data memory 24, respectively, and sends the degree of matching between the two to the signal output section 27, and It performs operations such as outputting image information stored in the memory 23 and data memory 24 as is to the monitor 26 as visually visible information.

The signal output unit 27 determines the end point of etching of the object to be processed 10 by comparing the degree of coincidence between the reference image information obtained from the pattern matching unit 25 and the observed image information with a desired darkness value, etc. .

The workpiece 10 of this embodiment is, for example, a semiconductor substrate 10.
It has a structure in which an insulating layer 10b made of silicon oxide or the like, a wiring layer 10C, and an insulating layer 10d are alternately laminated on the uppermost insulating layer 10d. A thin metal film 10e is formed over the entire surface, and a photoresist 10f is further applied thereon to mask the thin metal film 10e into a predetermined pattern during etching.

The third example shows an example of such a state before etching.
Figures (a) to (C) show an example of a partial cross section, a partial plane, and the overall appearance of the object 10 to be processed, respectively.

Similarly, Figures 9J4 (a) to (C) show the workpiece 10
This shows a state in which etching of the metal thin film 10e has just been completed.

Further, FIGS. 5(a) to 5(C) show an overetching process in which the unnecessary metal thin film 10e remaining on the insulating layer 10d is completely removed by slightly etching the insulating layer 10d underlying the metal thin film 10e. This is the etching state, and this state is usually the end point of etching the metal thin film 10e.

Hereinafter, an example of the operation of the dry etching apparatus of this embodiment will be explained with reference to the flowchart of FIG. 2 and FIGS. 3 to 5.

First, the workpiece 10 is
At the end point of etching under the same conditions as (Fig. 5(a))
An image of the object to be processed 10 in the states shown in ~(C)) is captured via the camera 21, and the image processing unit 22 extracts, for example, color, interference fringes, and other external characteristic information, Store in registration memory 23 (step 10
0).

It goes without saying that the image data obtained through the camera 21 may be used as is as the reference image information stored in the registration memory 23.

After setting the reference image information in the registration memory 23 in this way, the actual etching process is started (step 101).

First, by lowering the sample stage 3 and bringing the loader 7 close to the sample stage 3, the loader 7 is
The unprocessed object 10 held in the sample table 3 is placed on the sample stage 3.

After that, the loader 7 is evacuated, and the gate mechanism 6
By closing, the reaction chamber R is brought into a sealed state.

Next, the inside of the reaction chamber R is evacuated to a desired degree of vacuum through the exhaust port 1b, and the desired composition and flow rate are The reaction gas G is transferred to the reaction chamber R.
to be introduced inside.

At the same time, a microwave μ of a desired wavelength is guided into the reaction chamber R through the waveguide 4, and the energy of the microwave μ causes a reaction gas to flow into the space above the object to be processed 10 placed on the sample stage 3. While forming G plasma, a magnetic field is applied inside the reaction chamber R by a coil 5 provided outside the Pelger 2. As a result, high-energy electrons are generated by electron cyclotron resonance (ECR) due to mutual substitution between the magnetic field and electrons in the plasma of the reaction gas G, and the etching species in the plasma of the reaction gas G are brought into a high-energy state. For example, the etching species promotes an anisotropic etching reaction in the depth direction that is faithful to the mask pattern of the photoresist 10f on the object 10 to be processed.

At this time, as the etching process progresses, the state of the appearance of the object 10 changes from the state shown in FIGS. 3(a) to 3(C) to the state shown in FIGS. 5(a) to 5(C). It changes from time to time.

For example, in the state shown in FIG. 3 before etching, the wiring layer 10c located under the transparent insulating layer 10d is not visible because it is blocked by the metal thin film 10e that is coated over the entire surface, and the entire surface is In the state shown in FIG. 4 in which the metal thin film 10e exhibits white color and has been just etched away (just etched), the thickness of the exposed underlying insulating layer 10d and the wiring layer located below it. 10
Depending on the pattern of C, etc., the color may appear blue, for example, and since there is a difference in the rate of progress of etching between the periphery and the center, the blue region in the periphery gradually spreads to the center. become.

In addition, in the etching completion state (overetching) shown in FIG. 5, the thickness of the underlying insulating layer 10d is smaller than in the just etching state, so that the overetched area will change depending on the degree of etching progress. For example, the color gradually changes from blue to red from the periphery to the center.

The end point detection device 20 of this embodiment detects the desired image (observation image information) of the workpiece 10, which characteristically changes from time to time in accordance with the degree of progress of etching, inside the reaction chamber R. The image is captured into the image processing unit 22 via the camera 21 at time intervals (step 102).

Then, the image processing section 22 writes the result of extracting the characteristic information of the observed image information or the observed image information as it is into the data memory 24 as needed, and the pattern matching section 25 extracts the characteristic information from the observed image information and writes it into the data memory 24. 24, the degree of coincidence between the two is calculated, and the result is output to the signal output section 27.

If the signal output unit 27 determines that the degree of coincidence between the two is still lower than the predetermined threshold, the process returns to step 102 to capture the image of the object to be processed 10, and perform the following steps as described above. Repeat the end point detection operation in each step.

Further, if the degree of coincidence between the two exceeds a predetermined threshold value, the signal output unit 27 outputs an end point detection signal to an external control device (not shown), etc. (step 105), and performs etching on the object to be processed 10. Complete (step 106
).

In this way, the object 1 to be processed has been subjected to the desired etching process.
0 is carried out to a subsequent predetermined process by the unloader 8 in a reverse procedure to the carrying-in operation described above.

In this way, in the end point detection device 20 of this embodiment,
The image of the workpiece 10 at the time of completion of etching is set in the registration memory 23 in advance as reference image information, and the observed images of the workpiece 10 that change from moment to moment during the actual etching process are captured at predetermined time intervals. is set in the data memory 24, and the end point of etching is detected based on the degree of coincidence between the two. Compared to the case of observing changes in the etching area, there is no detection error caused by the amount of reaction products generated depending on the etching area, and the end point can be detected with high accuracy.

Furthermore, even if the object to be processed 10 is in the testing/research stage and the reaction products in the etching process are unknown, the end point of etching can be automatically detected more objectively and accurately than by visual inspection or the like. I can do it.

[Embodiment 2] FIG. 6 is a sectional view showing an example in which an end point detection device according to another embodiment of the present invention is attached to a thin film forming apparatus.

That is, in the case of the second embodiment, inside the reaction chamber R of the thin film forming apparatus, a pair of flat electrodes 3a which also serve as a sample stage on which the object to be processed 10 is placed and which face each other in a vertically parallel posture are installed.
and a flat plate electrode 3b are provided, and by applying a desired high frequency power from a - high frequency power source 3C between the flat plate electrodes 3a and 3b, the upper part of the workpiece 10 located between the flat plate electrodes 3a and 3b is A plasma of a reactive gas G1 is formed in a space to form a thin film made of a desired substance on the object to be processed 10.

In this case, inside the upper flat plate electrode 3a, for example,
An optical fiber 28 is installed through the surface facing the lower flat plate electrode 3b so that one end thereof is exposed. It is configured to capture an image of the object 10 into a camera 21.

Then, an image of the object 10 on which a thin film of a desired substance has been deposited and formed to a desired thickness is set in the registration memory 23 as reference image information, and in the process of forming a thin film, the thin film is Observation image information such as interference fringes and colors on the object to be processed 10, which change from moment to moment as the thickness of the object increases, is captured at predetermined time intervals and set in the data memory 24, and by comparing the two, it is possible to Processed material 1
This is to determine the end point of the process of forming a thin film of a desired substance relative to 0.

In the case of this embodiment as well, since the final inspection is performed based on the image of the actual object to be processed 10, the end point of the thin film forming process can be detected by
It can be done objectively, accurately, and automatically.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the end point detection target is not limited to etching processing or thin film forming processing, but can be widely applied to processing in which the appearance of the object to be processed changes as the processing progresses.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, according to the end point detection method of the present invention, the image information of the object to be processed at the time of completion of processing is registered in advance as reference image information, and the registered reference image information and the object to be processed during processing are The end point of the process is determined by comparing it with image information, so the end point can be determined based on the size of the etching area, for example, when using intensity changes in the emission spectrum of reaction products specific to a specific etching reaction. The end point of the desired process can be detected with high accuracy without affecting the detection accuracy, and the end point of the process can be objectively detected even if the reaction product specific to a specific process reaction is unknown. be able to.

In addition, in the case of thin film formation processing, the thickness of the film can be determined objectively based on changes in the appearance of the processed object as the thin film grows, and the thickness of the thin film reaches the desired value. It is possible to accurately, objectively and automatically detect the end point of the process to determine whether or not the process has been completed.

Further, according to the end point detection device according to the present invention, a camera that detects image information of the object to be processed, an image processing section that extracts desired characteristic information from the image information, and a first point that serves as a reference. a first memory in which characteristic information is stored; a second memory in which second characteristic information extracted from the image information of the object to be processed is stored; and the first and second memories. said first and second stored in each of
a matching unit that checks the degree of matching between the two by matching the feature information of the two;
and a determination unit that determines the end point of the process based on the degree of coincidence of the first and second feature information obtained in the comparison unit. By storing the image information in the first memory as the first characteristic information serving as a reference and determining the end point of the process using this as a reference, for example, the intensity change of the emission spectrum of the reaction product specific to a specific etching reaction can be detected. The end point detection accuracy is not affected by the size of the etching area as is the case when using etching. Even if the end point of the process is unknown, it is possible to objectively detect the end point of the process.

In addition, in the case of thin film formation processing, the thickness of the film can be determined objectively based on changes in the appearance of the processed object as the thin film grows, and the thickness of the thin film reaches the desired value. It is possible to accurately and objectively detect the end point of the process to determine whether or not the process has been completed.

[Brief explanation of the drawing]

1st t! I is a cross-sectional view schematically showing an example of a dry etching device equipped with an end point detection device according to an embodiment of the present invention; 21st! 1 is a flowchart showing an example of the operation of the end point detection device which is an embodiment of the present invention; FIGS. 3(a) to (C) are diagrams showing an example of the state of the object to be processed; ) to (C) are diagrams similarly showing an example of the state of the object to be processed, FIGS. 5(a) to (C) are diagrams similarly showing an example of the state of the object to be processed, and FIG. FIG. 3 is a schematic cross-sectional view showing an example of a case where an end point detection device according to another embodiment of the present invention is attached to a thin film forming apparatus. DESCRIPTION OF SYMBOLS 1... Housing, 1a... Gas supply pipe, 1b... Exhaust port, 2... Perger 2a... Flange part, 2b
...Gas supply hole, 3...Sample stand, 3a, 3b...
Flat plate electrode, 3C... High frequency power supply, 4... Waveguide, 4
a... Observation window, 5... Coil, 6... Gate mechanism, 7... Loader, 8... Unloader, 10... Processing object, 10a... Semiconductor substrate, 10b...・Insulating layer, 10C...Wiring layer, 10d...Insulating layer, 10e・
...Metal thin film, 10f...Photoresist, 20...
End point detection device, 21... Camera, 22... Image processing section, 23... Registration memory, 24... Data memory, 25... Pattern matching section, 26... Monitor 2
7...Signal output section, 28...Optical fiber, 100~
106...Processing step showing an example of end point detection operation,
G. G1...Reaction gas, g...Waste gas, R...Reaction chamber, μ...Microwave. Figure Figure (a) (C)? Of n Fig. 4 (a) (b) Fig. 4 (a) (b) 0c

Claims (1)

[Claims] 1. Image information of the object to be processed at the time of completion of processing is registered in advance as reference image information, and this registered reference image information is compared with image information of the object to be processed during processing. An end point detection method characterized in that the end point of processing is determined by: 2. A camera that detects image information of the object to be processed, an image processing unit that extracts desired feature information from the image information, and a first memory that stores first feature information that serves as a reference. , a second memory in which second feature information extracted from the image information of the object being processed is stored; and the first and second features stored in each of the first and second memories. A collation unit that collates the second feature information to check the degree of coincidence between the two, and determines the end point of the process based on the magnitude of the degree of coincidence between the first and second characteristic information obtained in this collation unit. An end point detection device comprising: a determination section;