JP2004023102A - Detection method of etching end point in dry semiconductor etching step - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection method of an etching end point in the dry semiconductor etching step, while can easily and accurately detect the etching end point. <P>SOLUTION: The detection method of the etching end point in the dry semiconductor etching step is to search for the etching end point from the surfaces of a semiconductor substrate and of a film selected from among multilayer films on the substrate, while spectrally analyzing the beam, in terms of etching time, which is emitted in the course of a plasma etching step onto the semiconductor substrate introduced into the processing chamber. At this time, the spectral analysis involves introduction of a semiconductor substrate into the process chamber, dry etching of the semiconductor substrate with a plasma, detection of the beam emitted from a viewpoint during dry etching, and turning of the beam into a spectrum, as well as sampling the spectrum per dry etching time zone, and aquisition of more than one specific wave strength. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting an etching end point in a semiconductor dry etching process, and more particularly, to a method of detecting an etching end point using light generated during an etching process in a process chamber of a semiconductor dry etching apparatus. The present invention relates to a method for detecting an etching end point in a semiconductor dry etching process for detecting a point (method for detecting an end point in a dry etching process).
[0002]
[Prior art]
2. Description of the Related Art Recently, as a semiconductor device is highly integrated in a 512 mega DRAM (Dynamic Random Access Memory) and a 1 Giga DRAM, an etching of a dry etching apparatus used to form a fine pattern with a small line width on a semiconductor substrate. The importance to the function is further increasing.
[0003]
The dry etching (etching) apparatus provides a user with a multilayer film on a semiconductor substrate such as a high-density DRAM (Dynamic RAM), an ultra-high-speed SRAM (Static RAM) and a highly integrated MRAM (Magnetic RAM). During the dry etching of the deposited semiconductor device, a detection method is always presented so that a user can search for an etching end point on a selected one of the films. The detection method largely uses an optical filter or a monochromator. In the detection method, the semiconductor dry etching apparatus detects light generated in a process chamber due to a reaction between a semiconductor substrate on which a lower film and a film to be etched are sequentially formed and plasma, and converts the light into a spectrum to search for an etching end point. . However, in the detection method, in order to detect a single wavelength and use one specific wave in the light projected from a process chamber of a dry etching apparatus, the entire multilayer film is etched or the quality of the film is deteriorated. The user does not know exactly the etching end point at which the etching is performed to a specific film quality. This is because the one specific wave does not represent the situation in the process chamber of the semiconductor dry etching apparatus in detail in real time.
[0004]
In addition, in the detection method, after main etching (Main etch) of a film to be etched is performed, a lower film below the layer is excessively etched (Over etch), so that ions or radicals forming a plasma are formed. (Radical) light to form one specific wave and search for the intensity of the specific wave at a predetermined etching time elapsed while searching for the etching end point. At this time, the detection method cannot find the etching end point when the thickness of the thin film on which the lower material layer is deposited is not constant.
[0005]
The semiconductor dry etching apparatus has a view port installed on the wall of the process chamber. The viewport is a window through which light generated by ions or radicals constituting the plasma is projected out of the process chamber. The viewport may accumulate polymer during repeated dry etching processes if the cleaning cycle of the process chamber is extended due to production line conditions. Therefore, it is not easy for the semiconductor dry etching apparatus to detect light generated by the plasma from the process chamber due to the viewport in which the polymer is accumulated, or the magnitude of a specific wave due to the light is weak. Therefore, a user cannot find an etching end point using the semiconductor dry etching apparatus.
[0006]
Since the light generated by the plasma is proportional to the etching area on the semiconductor substrate, the intensity of the light is further reduced due to the high integration and high density of the semiconductor element, and a new etching end point is detected. There is a need for method development.
[0007]
[Problems to be solved by the invention]
The technical problem to be solved by the present invention is to set an etching end point on the semiconductor substrate or on a selected film on the substrate during dry etching with a multilayer film covering the semiconductor substrate. An object of the present invention is to provide a method for detecting an etching end point in a semiconductor dry etching process, which can be accurately and easily detected.
[0008]
Means for Solving the Invention
To achieve the above technical object, the present invention provides a method for detecting an etching end point in a semiconductor dry etching process.
[0009]
The detection method includes loading a semiconductor substrate into a process chamber and performing a dry etching process using plasma on the loaded semiconductor substrate. Subsequently, light generated by the plasma during the dry etching process is detected outside the process chamber, and the detected light is converted into a spectrum in the semiconductor dry etching apparatus in real time (real time). Then, one or more specific waves are formed using the spectrum, and the one or more specific waves are sequentially normalized and differentiated after the normalization. At this time, the user counts (counts) one or more inflection points of the differentiated specific wave after normalization, and obtains an etching end point based on the number of counted inflection points.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 is a schematic configuration diagram of a semiconductor dry etching apparatus on which a semiconductor substrate is mounted according to the present invention, and FIG. 2 illustrates a method of detecting an etching end point using the semiconductor dry etching apparatus of FIG. It is a process flowchart.
[0012]
Referring to FIGS. 1 and 2, the semiconductor dry etching apparatus 5 includes a process chamber 10, a detector 32, a detector 34, and a main controller 36. The process chamber 10 includes a lower electrode 12 also serving as a stage on which a semiconductor substrate 16 is mounted on the bottom, an upper electrode 14 installed on a ceiling, and a view port 30 (View port) disposed on a wall of the process chamber 10. ). The lower and upper electrodes 12 and 14 serve to generate a process gas (not shown in the drawings) supplied into the process chamber 10 using plasma. The viewport 30 serves as a window for projecting light generated by a reaction between a deposited film on the semiconductor substrate 16 and ions or radicals forming plasma outside the process chamber 10. The detection unit 32 detects or catches light projected from the process chamber 10 at a predetermined distance from the viewport 30. The detector 34 connected to the detection unit 32 converts the light into a spectrum and generates one or more specific waves using the spectrum. The one or more specific waves are obtained by subdividing the spectrum by a locus having one or more wavelengths by the dry etching. A power supply 28 is input to each of the lower and upper electrodes 12, 14, and the lower and upper electrodes 12, 14 are grounded at the same point. At this time, a method of detecting an etching end point in the semiconductor dry etching process may be described with reference to FIGS.
[0013]
In the detection method, first, the step S2 of FIG. 2 is performed in which the semiconductor substrate 16 is mounted on the lower electrode 12 in the process chamber 10, and a process gas is supplied into the process chamber 10 and the lower and upper electrodes 12, 14 are supplied. And performing a dry etching of a film formed on the semiconductor substrate 16 by inputting a power supply 28 to the semiconductor substrate 16 in step S4 of FIG. The film formed on the semiconductor substrate 16 is at least one film. At this time, a plasma of a process gas is formed on the semiconductor substrate 16 in the process chamber 10, and a film on the semiconductor substrate 16 is dry-etched by the plasma. Light is generated in the process chamber 10 due to the reaction between the plasma and the film on the semiconductor substrate 16, and the light is projected out of the process chamber 10 through a view port 30 installed on the wall of the chamber 10. Then, the step S6 of FIG. The detection unit 32 is arranged at a predetermined distance in front of the viewport 30 and is connected to a detector 34. Subsequently, the detected light is converted into a spectrum in real time from the detector 34 during the dry etching, and is stored in the semiconductor dry etching apparatus 5. The step S8 of FIG. Is changed to one or more specific waves according to the dry etching time for each wavelength band, followed by step S10 of FIG. In addition, step S12 of FIG. 2 for dividing the remaining wavelength by the selected wavelength in the one or more specific waves and normalizing the one or more specific waves, and differentiating the standardized one or more specific waves by a dry etching time. Operation S14 of FIG. 2 is performed. The differentiation operation may be performed on at least one of the normalized specific waves at least once. After normalization, the user counts (counts) inflection points due to the dry etching time through one or more differentiated specific waves, and performs step S16 of FIG. At this time, counting the inflection point means that the inflection point value having a differential value of “0” passes through an inflection band in which a predetermined ± tolerance range, that is, a tolerance range of 0 to 0.15 is included. This is achieved by counting the numbers to be performed. Counting the inflection point means that the value is changed from the (+) value to the (−) value, the (−) value is changed to the (+) value, or the “0” value is changed to (+) or (−). ) Counting the number that changes to the value
Holds. After the normalization, before counting the number of inflection points having a “0” differential value in one or more differentiated specific waves, the counting proceeds after a predetermined initial dry etching time has elapsed. Therefore, the value of the inflection point which cannot substitute for the dry etching state of the selected film on the semiconductor substrate is excluded from the counting. Through this, the user performs step S18 of FIG. 2 in which a predetermined etching time is determined, and an inflection point satisfying the number of inflection points after the time is determined. Preferably, the number of inflection points counted is in the range of 1 to 1,000. The satisfied inflection point is an etching end point at a predetermined dry etching time of the detection method. The etching end point is a point that is greater than or less than a slope value selected by one or more specific waves differentiated after normalization after counting the inflection point.
[0014]
FIG. 3 is a cross-sectional view showing a photoresist and a multilayer film sequentially covered on the semiconductor substrate of FIG. 1. FIG. 4 shows two semiconductor substrates in a process chamber of the semiconductor dry etching apparatus of FIG. 6 is a graph showing light projected during dry etching as being transformed into the same specific wave. FIG. 5 is a graph showing a normalized (normalized) version of the specific wave of FIG. 4. FIG. 6 is different from FIG. It is a graph changed and shown as a differentiated specific wave.
[0015]
Referring to FIGS. 3 to 6, the semiconductor substrate 16 is covered with a photoresist 26 and first to fourth films 18, 20, 22, and 24, which are sequentially deposited. The photoresist 26 is applied on the fourth film 24. The first to fourth films 18, 20, 22, and 24 are preferably insulating films or conductive films. Alternatively, the first to fourth films 18, 20, 22, and 24 can be stacked on the semiconductor substrate 16 while replacing the insulating film and the conductive film to form a desired pattern. An opening 27 is formed in a predetermined region of the photoresist 26 on the semiconductor substrate 16 by using a conventionally known photo process. Subsequently, an etching process is performed on the fourth film 24 by using the photoresist 26 as a mask and using the third film 22 as an etching buffer film (etching buffer film). The etching process is performed in a semiconductor dry etching apparatus 5 of FIG. 1 as a known technique. In this case, each of the third and fourth films 22 and 24 is preferably an insulating film and a conductive film, or a conductive film and an insulating film. The apparatus 5 converts light generated by ions or radicals constituting the plasma into a spectrum, and causes the detector 34 to generate a specific wave having only one wavelength due to the dry etching time.
[0016]
Here, a method of detecting the etching end point from the two-layer film covered on the semiconductor substrate 16, that is, the third film 22 when the third and fourth films 22 and 24 are dry-etched will be described. I will do it. FIG. 4 shows the same dry etching apparatus 5 having the same atmosphere in the process chamber 10 and changing the cumulative number of etched semiconductor substrates having the third and fourth films 22 and 24 within one cleaning cycle. 3 is a diagram illustrating the specific wave shown. For example, one of the specific waves W1 and W2 is data obtained by performing a dry etching process on the semiconductor substrate 16 at the 100th when the cumulative number is 99, and W2 is the 1,000th data obtained by performing the dry etching process on the semiconductor substrate 16 when the accumulated number is 999. That is, FIG. 4 shows that the strength of the specific waves W1 and W2 decreases in the same dry etching time as the cumulative number increases. This is because the detection unit 32 cannot accurately detect the light projected from the process chamber 10 due to the polymer due to the long dry etching process on the viewport 30 on the wall of the process chamber 10 in FIG. is there. In such a case, the user first selects one of the specific waves W1 and W2, and also normalizes the remaining wavelengths of the specific waves W1 and W2 by the selected wavelength. it can. Here, the selected wavelength is referred to as a reference value, and the reference value may be a maximum peak value among wavelengths of the specific waves W1 and W2, or may be a value smaller than the maximum peak value. FIG. 5 illustrates the normalized specific waves W3 and W4. Although there is a large difference between the wavelength intensities of the specific waves W1 and W2 in the same dry etching time of FIG. , W4, the difference is significantly reduced at the corresponding time. Normalizing the specific waves W1 and W2 is particularly necessary when the third and fourth films 22 and 24 in FIG. 3 are thin and a fine pattern is formed using the fourth film 24. is there. This is because the user does not attack the second film 20 under the third film 22 in the dry etching process, and realizes the size of the fine pattern. This is because the standardized specific waves W3 and W4, which can always obtain a constant etching end point despite the influence of the above, are desired. Even if the polymer is deposited on the viewport 30 and the intensity of the light detected by the detection unit 32 changes, the standardized specific waves W3 and W4 also change in conjunction with each other. There is no inconvenience in detecting the etching end point using the semiconductor dry etching apparatus 5.
[0017]
Next, the standardized specific waves W3 and W4 are differentiated by the dry etching time, which is generated by a reaction between the plasma and the semiconductor substrate having the third and fourth films 22 and 24 during the dry etching. This is an operation for the user to easily search for a specialized (specified) portion in the obtained light. Here, the specific portion is called an inflection point, and the inflection point has “0” as a differential value. At this time, if the situation of the process chamber 10 and the situation of the dry etching performed on the semiconductor substrate 16 are not accurately predicted from the normalized specific waves W3 and W4, the user differentiates after the normalization. The situation on the process chamber and the semiconductor substrate can be accurately predicted using the inflection point through the specified wave. This is because it is sometimes difficult to distinguish a specialized portion of the normalized specific wave after a predetermined dry etching time, but a differentiated specific wave after the normalization is distinguished. Specialized parts that are difficult to make can be easily distinguished during the dry etching time. After the normalization, the differentiated specific wave can be differentiated again by a dry etching time in order to easily find a specialized portion invisible. That is, the standardized specific wave can be differentiated at least once by the dry etching time. FIG. 6 differs from FIGS. 4 and 5 in that one or more specific waves (not shown in the drawings) having a single wavelength secured in real time are standardized during a long dry etching time. 5 is a graph illustrating specific waves W5 and W6 differentiated thereafter. As already described, after the normalization, the differentiated specific wave W6 surely indicates an inflection point from the normalized specific wave W5. This allows the user to quickly check the status of the process chamber 10 and the status of etching on the semiconductor substrate 16. Therefore, the present invention is also applied to one specific wave having the single wavelength, and normalizes the specific wave, and after the normalization, inflection points indicating the status of the process chamber 10 through differentiation are easily provided to the user. And the inflection point is recognized as an etching end point in the dry etching process.
[0018]
FIG. 7 is a diagram illustrating an example of an etching end point that satisfies a condition where light emitted from the process chamber of FIG. 1 according to the present invention is subdivided by one or more specific waves and all the specific waves appear during a predetermined dry etching time. 5 is a graph for explaining a detection method of recognizing. FIG. 8 illustrates a method of searching for an etching end point by using the detection method of FIG. 7 after a part of one or more specific waves satisfy a necessary condition for a predetermined dry etching time. FIG.
[0019]
FIGS. 9 and 10 show one selected one or more specific waves monitored by the atmosphere of the process chamber using the detection method of FIG. 7 and a predetermined dry etching time. 9 is a graph showing searching for an etching end point.
[0020]
Referring to FIGS. 7 and 10, a contact hole or a wiring (not shown) is formed on the semiconductor substrate of FIG. 3 having the photoresist 26 and the first to fourth films 18, 20, 22, and 24. I do. The contact holes are formed on the semiconductor substrate 16 by dry-etching the first to fourth films 18, 20, 22, and 24 in sequence through the opening 27 of the photoresist 26 using the semiconductor dry etching apparatus 5 of FIG. The first to fourth films 18, 20, 22, and 24 are dry-etched sequentially through the opening 27 using the photoresist 26 as a mask and the remaining first to fourth films 18, 20, 22, and 24 are formed. Let it form. At this time, a detection method for determining an etching end point during a dry etching process using a plasma generated in a process chamber and a light generated by a reaction between a semiconductor substrate having first to fourth films 18, 20, 22, and 24 is proposed. It shall be. First, light generated during dry etching of the first to fourth films 18, 20, 22, 24 is changed to one or more specific waves by the detector 34 of FIG. At this time, if at least one point P1, P2, P3, P4 where one or more specific waves intersect appears on the guide line A in FIG. There is an algorithm (Algorizm) that sends a signal to the user or the semiconductor dry etching apparatus, which is the end point of the etching in the dry etching time. If the one or more specific waves do not satisfy the algorithm, the detection method allows the user to recognize that the dry etching process has not been completed yet. Also, when the strength of the one or more specific waves is weak, the detection method may include one or more specific waves in which one or more specific waves are standardized and one or more specific waves differentiated after normalization. The present invention can be applied even after the change to the specific wave. In addition, the detection method may include selecting one of the one or more specific waves as shown in FIGS. 4 to 6, and then changing to a normalized specific wave and a differentiated specific wave. Can also be applied. The one specific wave may well explain a dry state on the semiconductor substrate 16 during the dry etching process in the one or more specific waves. The algorithm described with reference to FIG. 7 differs from FIGS. 4 to 6 in that one or more specific waves generated by the detector 34 can be freely selected, thereby improving the production line process. Can respond well to change.
[0021]
Next, the semiconductor dry etching apparatus 5 can etch the semiconductor substrate 16 by creating an algorithm different from that of FIG. 7 in the above-described detection method. In other words, the algorithm may include one or more of the specific waves W8, W9, W10 shown in FIG. 8 during the dry etching of the first to fourth films 18, 20, 22, 24 of FIG. First, the remaining specific waves W9 and W10 excluding the specific wave W8 are monitored. Subsequently, as shown in FIG. 8, all points P9 and P10 where the specific waves intersect appear on the guide line B having a predetermined dry etching time, and thereafter, the guide line B having another predetermined dry etching time. Then, a signal indicating that the point P8 where the one specific wave W8 intersects appears on the 'is an etching end point is sent to the user or the semiconductor dry etching apparatus. That is, the detection method employs an algorithm that performs a procedure of dry-etching the first film 18 after satisfying, for example, a necessary condition that all of the second to fourth films 20, 22, and 24 are removed from the first film 18. Prepare. Accordingly, the user can form a contact hole or a wiring on the semiconductor substrate 16 using the algorithm. In addition, even when the strength of the one or more specific waves W8, W9, and W10 is weak, the algorithm differentiates one or more specific waves into one or more specific waves and normalization. It can also be applied after changing to one or more specific waves.
[0022]
Finally, the process chamber 10 of the semiconductor dry etching apparatus 5 changes its atmosphere by changing the atmosphere of the process chamber 10 by one cycle of cleaning, or changes the process gas injected into the same process chamber 10. A detection method having another algorithm capable of coping with a case where a different dry etching process is performed and the atmosphere of the process chamber 10 is changed will be described. FIG. 9 is a graph after the atmosphere of the process chamber 10 is changed, and FIG. 10 is a graph after the atmosphere of the process chamber 10 is stabilized. In this case, the semiconductor dry etching apparatus 5 may detect two specific waves corresponding to the process chamber 10 after the process chamber 10 atmosphere is changed and after the process chamber 10 atmosphere is stabilized. To be stored. After the atmosphere of the process chamber 10 is changed, the algorithm determines one of two intersections P11 and P12 of two specific waves on the guide line C displayed at a predetermined dry etching time in FIG. The user is made aware that the time when it appears is the etching end point. Also, after the atmosphere of the process chamber 10 is stabilized, the above algorithm is applied to the guide line D displayed at a predetermined dry etching time in FIG. 10 at the intersection of two specific waves having waveforms different from those in FIG. When the selected one of P13 and P14 appears, the user is made aware of the end point of the etching. The selection of one of the two specific waves in the atmosphere of each process chamber 10 allows a user to handle freely in consideration of the etching condition of the semiconductor dry etching apparatus.
[0023]
Accordingly, the present invention provides a method of performing dry etching on the semiconductor substrate 16 having a multi-layered film using one or more specific waves in response to a real-time etching situation or a process chamber 10 atmosphere change. The user can easily find the etching end point.
[0024]
FIG. 11 shows that the photoresist opening of FIG. 4 is projected from a process chamber of a semiconductor dry etching apparatus while an etching process is performed on a semiconductor substrate having a plurality of patterns as a pattern forming a contact hole. 5 is a graph illustrating the transformed light into one or more specific waves. Also, FIG. 12 illustrates that the main factors secured through the operation of checking the mutual alternation of the specific waves of FIG. 11 and the other operations are performed on the wavelength of the specific wave, and that the discrimination power by the dry etching time is good. FIG.
[0025]
Referring to FIGS. 11 and 12, a contact hole (not shown) is formed on the semiconductor substrate of FIG. 3 having a photoresist 26 and first to fourth films 18, 20, 22, and 24. The contact holes are formed by sequentially etching the first to fourth films 18, 20, 22, 24 using a known dry etching technique using the photoresist 26 as a mask. The semiconductor substrate 16 is exposed through a contact hole. At this time, the first to fourth films 18, 20, 22, and 24 react with the plasma during the dry etching and generate light having different wavelengths in the process chamber 10 as shown in FIG. The light passes through the viewport 30 installed on the wall of the process chamber 10 and is detected by the detection unit 32. The light is again spectrum-converted by the detector 34 connected to the detection unit 32, and is subjected to one or more specific light. Can be separated by waves. The one or more specific waves are obtained by subdividing the spectrum by a locus having one or more wavelengths according to the dry etching time. FIG. 11 is a graph illustrating one or more specific waves W11, W12, W13, and W14 in the semiconductor dry etching apparatus 5 by spectrum analysis of the light. However, the above graph is inconvenient for the user of the semiconductor dry etching apparatus 5 to search for the etching end point from the locus of one or more specific waves W11, W12, W13, and W14 in a predetermined dry etching time. This is because the user cannot search for one or more specific waves W11, W12, W13, and W14 from a specific portion according to the dry etching time as shown in FIGS. Therefore, in order to search for an etching end point using the one or more specific waves W11, W12, W13, and W14, the one or more specific waves W11, W12, W13, and W14 need to be standardized or after standardization. It must be changed with the differentiated specific wave. If the one or more specific waves W11, W12, W13, and W14 are data obtained through a long dry etching process, the user may use one or more specific waves W11 using normalization and differentiation. , W12, W13, and W14 are not easily analyzed even if a long time is consumed and one or more modified specific waves are formed at the same time.
[0026]
In order to solve such a difficulty, the user may change the one or more specific waves W11, W12, W13, W14 to another method without using the normalization and differentiation operation. Also, a detection method will be described so that the user can more easily find the etching end point through one or more specific waves W11, W12, W13, and W14. As shown in FIG. 11, when one or more wavelengths of the specific waves W11, W12, W13, and W14 are stored in the detector 34 of FIG. A reference value is selected from each of the specific waves W11, W12, W13, and W14, and standardization is performed by dividing the remaining wavelengths forming one or more specific waves W11, W12, W13, and W14 by the reference value. Next, in order to check an alternating relationship between one or more specific waves W11, W12, W13, and W14, a dispersion (Variation) and a covariance (Covariation) are performed at a standardized wavelength. At this time, the values extracted through the variance and covariance operations become elements of the respective variance-covariance matrices (Variation & Covariance Matrix). An eigenvalue is obtained by calculating the matrix, and an eigenvector is obtained using the eigenvalue. The eigenvector is a main factor in which the alternating relationship between the wavelengths of one or more specific waves W11, W12, W13, and W14 is listed in the order of contribution. Finally, the user substitutes the eigenvector and the normalized wavelength into a known equation to obtain one or more modified correlation lines. The one or more correlation lines are obtained by the number of the eigenvectors, and the user can select one correlation line created with the eigenvector having the largest main factor contribution. The remaining correlation lines may be excluded from consideration.
[0027]
FIG. 12 shows the one correlation line W15 according to the dry etching time. Since the one correlation line W15 is created with the eigenvector having the largest main factor contribution order, it provides a good representation of the atmosphere in the process chamber 10 and the etching state of the semiconductor substrate 16 during dry etching. With this, the user can easily find the etching end point in the dry etching time through the one correlation line W15.
[0028]
【The invention's effect】
As described above, the present invention provides a method of detecting an etching end point using light generated by ions or radicals forming plasma during dry etching of a semiconductor substrate having a multilayer film. . That is, in the detection method, the light is spectrumd by a detector of a semiconductor dry etching apparatus and one or more specific waves are formed by the spectrum, so that an etching end point can be determined in accordance with a process chamber atmosphere in various cases. Has algorithms that make it easy to find. Thereby, the semiconductor dry etching apparatus can easily finish the etching process on the selected film on the semiconductor substrate, assure the reliability of the semiconductor device, and improve the yield of the semiconductor device on the semiconductor substrate. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a semiconductor dry etching apparatus on which a semiconductor substrate is seated according to the present invention.
FIG. 2 is a process flow chart illustrating a method for detecting an etching end point using the semiconductor dry etching apparatus of FIG. 1;
FIG. 3 is a sectional view showing a photoresist and a multilayer film sequentially covering the photoresist on the semiconductor substrate of FIG. 1;
FIG. 4 is a graph showing each of light beams emitted during dry etching of two semiconductor substrates in the process chamber of the semiconductor dry etching apparatus of FIG.
FIG. 5 is a graph showing the specific wave of FIG. 4 as normalized (Normalized).
FIG. 6 is a graph different from FIG. 4 in which one specific wave is changed as a specific wave normalized and a specific wave differentiated after normalization.
7 divides the light projected from the process chamber of FIG. 1 into one or more specific waves according to the present invention, and satisfies an etching end point when all the specific waves appear during a predetermined dry etching time. 7 is a graph for explaining a detection method for recognizing as "".
FIG. 8 is a diagram illustrating a method of searching for an etching end point in a specific dry wave after a part of at least one specific wave satisfies a required condition for a predetermined dry etching time using the detection method of FIG. 7; A graph showing.
FIG. 9 is a flowchart for searching for an etching end point from a predetermined dry etching time in one or more specific waves monitored by an atmosphere of a process chamber using the detection method of FIG. 7; A graph showing.
FIG. 10 is a flowchart for searching for an etching end point from a predetermined dry etching time using one of one or more specific waves monitored by an atmosphere of a process chamber using the detection method of FIG. 7; A graph showing.
FIG. 11 is a view showing a pattern in which openings of the photoresist of FIG. 4 are formed as contact-hole patterns from a process chamber of a semiconductor dry etching apparatus during an etching process performed on a semiconductor substrate having a plurality of the patterns. FIG. 4 is a graph showing that the changed light is changed into one or more specific waves.
FIG. 12 is a diagram showing another operation performed on the factor of the main factor and the wavelength of the specific wave through the operation of checking the mutual alternation of the specific waves of FIG. 11, and the discrimination power by dry etching time is good. The graph which shows a correlation line.
[Explanation of symbols]
5 Semiconductor dry etching equipment
10 Process chamber
12 lower electrode
14 Upper electrode
16 Semiconductor substrate
18 First film
20 Second film
22 Third film
24 4th film
26 Photoresist
27 Opening
30 viewports
32 detector
34 detector
36 Main control unit

Claims (19)

Perform a plasma etching process on the semiconductor substrate put in the process chamber,
Detecting one or more specific waves generated during the plasma etching process,
Normalizing the one or more specific waves with a reference value,
Differentiating one or more of the normalized specific waves,
After the normalization, counting one or more differentiated specific waves, inflection points each having a “0” differential value,
A method of detecting an etching end point in a semiconductor dry etching process, comprising: checking an etching end point based on the counted number of inflection points. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Detecting the one or more specific waves,
The light projected from the process chamber is spectralized in real time during dry etching,
A method for detecting an etching end point in a semiconductor dry etching process, comprising subdividing the spectrum by a locus having one or more wavelengths by the dry etching. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the reference value is a maximum peak value of the at least one specific wave or a value smaller than the maximum peak value. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Counting the inflection point includes counting the number of inflection points having an inflection point value having a differential value of “0” and including an inflection band within a predetermined ± allowable range. A method for detecting an etching end point in an etching process. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
The counting of the inflection points includes counting the number of inflection points passing through the “0” differential value and the number of continuous inflection points that are inflected and are not inflected again. A method for detecting an etching end point in a semiconductor dry etching process. A method for detecting an etching end point in a semiconductor dry etching step according to claim 4,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the allowable range is 0 to 0.15. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the number of counted inflection points is 1 to 1,000. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
After the normalization, counting of an inflection point having a differential value of “0” for each of one or more differentiated specific waves is performed after a predetermined elapsed time. A method for detecting an etching end point in an etching process. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the differentiation of one or more specific waves is performed at least once. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Checking the etching end point may include stopping the etching at a point greater than or less than a slope value selected from one or more specific waves differentiated after normalization after counting the inflection point. A method for detecting an etching end point in a semiconductor dry etching process. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the checking of the etching end point is performed at a predetermined dry etching time by detecting one or more specific waves having a single wavelength from the light. . The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Check of the etching end point,
After forming all of the one or more specific waves from the light,
A method for detecting an etching end point in a semiconductor dry etching process, wherein the method is established when all of the one or more specific waves appear and are satisfied for a predetermined dry etching time. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Check of the etching end point,
After forming all of the one or more specific waves from the light,
A method for detecting an etching end point in a semiconductor dry etching process, wherein one of the one or more specific waves is selected and a predetermined dry etching time is satisfied. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Check of the etching end point,
Among the one or more specific waves, after excluding one specific wave, the remaining specific waves may be obtained in a predetermined dry etching time, and after all the necessary conditions for appearing are satisfied,
A method of detecting an etching end point in a semiconductor dry etching process, wherein the one or more specific waves are satisfied for another predetermined dry etching time last satisfied. The method of detecting an etching end point in a semiconductor dry etching process according to claim 1,
Check of the etching end point,
Managing the one or more specific waves correspondingly appearing after the atmosphere in the process chamber is changed and after the atmosphere in the process chamber is stabilized;
A method for detecting an etching end point in a semiconductor dry etching process, wherein the predetermined dry etching process is performed using one selected from the one or more specific waves according to an atmosphere in the process chamber. . Perform a plasma etching process on the semiconductor substrate put in the process chamber,
Detecting one or more specific waves generated during the plasma etching process,
Normalizing the one or more specific waves with a reference value,
Forming a dispersion covariance matrix for each of the one or more specific wave wavelengths,
Find eigenvalues for the variance-covariance matrix,
Determining an eigenvector using the eigenvalues;
Selecting one or more major factors from the eigenvectors,
The one or more main factors and the wavelength of the one or more specific waves are each substituted into a known formula to determine a correlation line,
A method of detecting an etching end point in a semiconductor dry etching process, comprising: checking an etching end point at a predetermined dry etching time using one of the correlation lines. A method for detecting an etching end point in a semiconductor dry etching step according to claim 16,
Detecting the one or more specific waves,
The spectrum projected in real time during dry etching of the light projected from the process chamber,
A method of detecting an etching end point in a semiconductor dry etching process, comprising subdividing the spectrum by a locus having one or more wavelengths by the dry etching. A method for detecting an etching end point in a semiconductor dry etching step according to claim 16,
The method of detecting an etching end point in a semiconductor dry etching process, wherein the one or more main factors are sequentially arranged with the eigenvectors according to the contribution having an alternating relationship from the one or more specific waves. A method for detecting an etching end point in a semiconductor dry etching step according to claim 16,
Checking the etching end point is performed by a predetermined dry etching time using the one correlation line created by the eigenvector having the largest alternating relationship among the correlation lines, wherein the semiconductor dry etching is performed. A method for detecting an etching end point in a process.

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