Inclination detection method for plasma airflow direction
By forming etching grooves and polymer film layers on the test wafer, and detecting the inclination angle of the plasma air flow direction by scanning electron microscope and failure analysis lens, the problem of inclination of the plasma air flow direction during dry etching is solved, achieving accurate detection and cost savings.
Patent Information
- Application Number
- CN202510622028.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-08-01
AI Technical Summary
In the prior art, the inclination of the plasma gas flow direction during dry etching leads to the inclination of the cross section after etching and the damage to the side wall, and there is a lack of effective online detection methods, resulting in product waste and increased costs.
By forming an etching groove and a polymer film layer on the test wafer, the dry etching device emits plasma for etching with specified process parameters, the edge width value of the etching groove is obtained, and the inclination angle of the plasma air flow direction is detected in combination with a scanning electron microscope and a failure analysis lens.
It realizes accurate inclination detection of plasma airflow direction, saves wafer products, reduces costs, eliminates the influence of other process factors, and improves product yield.
Smart Images
Figure CN120413458A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for detecting the inclination of the plasma gas flow direction. Background Art
[0002] In related technologies, dry etching can achieve anisotropic etching because the directionality of charged particles is controllable. However, due to reasons such as chamber design, process parameter settings (Child's law, plasma density, and ion energy affect the height of the plasma sheath), and component loss, especially at the wafer edge, the direction of the plasma gas flow is likely to change. The inclination of the plasma gas flow direction will cause the etched profile to be inclined, the sidewalls to be damaged, or energy loss due to plasma scattering, resulting in under-etching.
[0003] Among them, Child's law describes the relationship between the plasma sheath and the plasma, and the motion law of ions can be deduced. And ions have directionality under a certain bias voltage. The consumption of the edge ring (ring parts) of the etching equipment causes the change of the plasma gas flow direction at the wafer edge, which will have a negative impact on the process.
[0004] For some processes, such as punch etch, it is impossible to effectively evaluate the inclination of the plasma gas flow direction on the product. For some processes, although it is possible to monitor whether the plasma gas flow direction is inclined by slicing or SEMCD (Scanning Electron Microscope Critical Dimension, which refers to the measurement of the critical dimension (Critical Dimension, abbreviated as CD) using a scanning electron microscope (SEM)), it still requires testing the product, wasting the product, and cannot decouple the influence of the wafer itself.
[0005] In related technologies, there is no off-line detection. For some processes, it can be observed by slicing the product or SEMCD. For some processes, on-line detection cannot be performed, and only a large number of product WAT (Wafer Acceptance Test) or CP (Chip Probe) can be used for analysis, which is not direct data support. Summary of the Invention
[0006] The purpose of the present application is to provide a method for detecting the inclination of the plasma gas flow direction, which can accurately detect the inclination of the plasma gas flow direction used in the dry etching process through an off-line detection method, is direct and effective, can realize the detection of the inclination of the plasma gas flow direction based on a test wafer, can save wafer products, and thus can save costs. It can also decouple the influence of the wafer itself. When detecting, the process parameters of a specified process can be used to control the dry etching equipment to emit plasma, and thus the influence of other process factors can be excluded.
[0007] According to the first aspect of the embodiments of the present application, a method for detecting the inclination of the plasma gas flow direction is provided, including: Providing a test wafer; the test wafer includes a wafer and an etched film layer, and the etched film layer covers the wafer; Using the process parameters of the target process to control the dry etching equipment to emit plasma to perform dry etching on the etched film layer to obtain an etched film layer; the etched film layer includes a first etching groove; the first etching groove includes a first side wall, a second side wall, a first notch, and a first bottom surface. The first side wall, the first bottom surface, and the second side wall are connected in sequence. The first side wall and the second side wall are opposite in position. The first bottom surface and the first notch are opposite. The first bottom surface is located on the surface of the wafer facing the etched film layer; Forming a first polymer film layer on the side of the etched film layer away from the wafer; the first polymer film layer includes a first mask portion and a second mask portion. The first mask portion covers a part of the first side wall close to the first notch, and the second mask portion covers a part of the second side wall close to the first notch. The first mask portion and the second mask portion are symmetrical; Using the process parameters to control the dry etching equipment to emit plasma to perform dry etching on the wafer located at the bottom of the first etching groove to obtain an object to be measured. The object to be measured includes an etched wafer. The etched wafer includes a second etching groove, and the second notch of the second etching groove is located on the first bottom surface of the first etching groove; Obtaining a first edge width value and a second edge width value; the first edge width value is the distance value between the bottom end of the first side wall on the first bottom surface and the second notch, and the second edge width value is the distance value between the bottom end of the second side wall on the first bottom surface and the second notch; Based on at least one of the first edge width value and the second edge width value, determining whether the inclination angle of the plasma gas flow direction meets the specified process requirements.
[0008] In one embodiment, controlling the process parameters of a target process technology to cause a dry etching apparatus to emit plasma to dry-etch the film layer to be etched to obtain an etched film layer includes: Forming a first photoresist layer on a side of the film layer to be etched away from the wafer; Patterning the first photoresist layer to obtain a second photoresist layer; the second photoresist layer includes a first shielding portion and an opening, and the opening is used to expose a patterned surface of the film layer to be etched that is not covered by the first shielding portion; Controlling the dry etching apparatus to emit plasma toward the patterned surface according to the process parameters to dry-etch the film layer to be etched to obtain the etched film layer and a second shielding portion; the first shielding portion is dry-etched to obtain the second shielding portion; Removing the second shielding portion.
[0009] In one embodiment, forming a first polymer film layer on a side of the etched film layer away from the wafer includes: Performing chemical vapor deposition using a first gas and a second gas in a specified ratio and a pulsed deposition process to obtain a second polymer film layer; at least carbon ions and fluorine ions are generated after dissociation of the first gas and the second gas, and the material of the second polymer film layer includes carbon and fluorine elements.
[0010] In one embodiment, the first gas is C4F6 and the second gas is CH3F.
[0011] In one embodiment, hydrogen ions are further generated after dissociation of the first gas and the second gas, and the material of the second polymer film layer further includes hydrogen.
[0012] In one embodiment, obtaining a first edge width value and a second edge width value includes: Scanning the object to be measured in a first direction using a critical dimension scanning electron microscope to obtain a scanning electron microscope image; the first direction points from the etched film layer to the etched wafer; Obtaining the first edge width value and the second edge width value based on the scanning electron microscope image.
[0013] In one embodiment, obtaining a first edge width value and a second edge width value includes: Slicing the object to be measured to obtain a sliced object to be measured; Scanning a cross-section of the sliced object to be measured using a failure analysis lens to obtain a cross-sectional view; Obtaining the first edge width value and the second edge width value based on the cross-sectional view.
[0014] In one embodiment, the obtaining of the first edge width value and the second edge width value includes: Determine N chips on the object to be measured as measurement positions, and the N chips are evenly distributed on the edge of the etched wafer; N is an integer greater than 1; For each test position, obtain a pair of the first edge width value and the second edge width value, and obtain N first edge width values and N second edge width values; The determining whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Obtain the average value of the N first edge width values to obtain a first average edge width value; Obtain the average value of the N second edge width values to obtain a second average edge width value; Determine whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first average edge width value and the second average edge width value.
[0015] In one embodiment, N is an even number, or N is 4.
[0016] In one embodiment, the determining whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Determine the minimum value of the first edge width value and the second edge width value; When the minimum value approaches zero, determine that the inclination angle of the plasma gas flow direction does not meet the specified process requirements.
[0017] In one embodiment, the determining whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Obtain a reference absolute value, where the reference absolute value is the absolute value of the difference between the first edge width value and the second edge width value when the yield rate of the wafer product is lower than a specified threshold; Obtain the absolute value of the difference between the first edge width value and the second edge width value as a measurement absolute value; Obtain the difference between the reference absolute value and the measurement absolute value as a target difference; When the target difference is greater than a specified difference, determine that the inclination angle of the plasma gas flow direction does not meet the specified process requirements.
[0018] In one embodiment, the material of the film layer to be etched is a carbon-based polymer, silicon oxide, or silicon nitride.
[0019] Compared with the prior art, the beneficial effects of the present application are as follows: By controlling the process parameters of the target process to control the dry etching equipment to emit plasma to dry-etch the film layer to be etched on the test wafer, an etched film layer is obtained. The etched film layer includes a first etching groove for exposing the wafer. The first etching groove includes a first side wall, a second side wall, a first notch, and a first bottom surface. The first side wall, the first bottom surface, and the second side wall are connected in sequence. The first side wall and the second side wall are opposite in position. The first bottom surface and the first notch are opposite. The first bottom surface is located on the surface of the wafer facing the etched film layer. Then, a first polymer film layer is formed on the side of the etched film layer away from the wafer. The first polymer film layer includes a first mask portion and a second mask portion. The first mask portion covers a part of the first side wall close to the first notch, and the second mask portion covers a part of the second side wall close to the first notch. The first mask portion and the second mask portion are symmetrical. Then, by controlling the process parameters of the target process to control the dry etching equipment to emit plasma to dry-etch the wafer located at the bottom of the first etching groove, a measurement object to be measured is obtained. The measurement object to be measured includes an etched wafer. The etched wafer includes a second etching groove. The second notch of the second etching groove is located on the first bottom surface of the first etching groove. Then, a first edge width value of the edge of the second etching groove close to the first side wall and a second edge width value of the edge close to the second side wall are obtained. The first edge width value is the distance value between the bottom end of the first side wall on the first bottom surface and the second notch, and the second edge width value is the distance value between the bottom end of the second side wall on the first bottom surface and the second notch. Then, based on at least one of the first edge width value and the second edge width value, it is determined whether the inclination angle of the plasma gas flow direction meets the specified process requirements. In this way, the inclination detection of the plasma gas flow direction used in the dry etching process can be performed by an offline detection method, and the inclination detection of the plasma gas flow direction can be realized based on the test wafer, which can save wafer products, thereby saving costs, and can also decouple the influence of the wafer itself. Moreover, through the above etching-depositing the first polymer film layer-etching method, the first edge width value and the second edge width value that are easy to measure can be formed, which is direct and effective, and can achieve accurate inclination detection. When detecting, the process parameters of the specified process are used to control the dry etching equipment to emit plasma to etch the test wafer that has not undergone other process processes, which can exclude the influence of other process factors. Description of the Drawings
[0020] Figure 1 is a schematic diagram showing the influence of the edge ring on the plasma gas flow direction shown according to the related art.
[0021] Figure 2It is a flowchart of a method for detecting the tilt of a plasma gas flow direction shown according to an exemplary embodiment.
[0022] Figure 3 It is a schematic structural diagram of a test wafer shown according to an exemplary embodiment.
[0023] Figure 4 It is a schematic structural diagram of a test wafer after the first etching shown according to an exemplary embodiment.
[0024] Figure 5 It is a flowchart of a method for detecting the tilt of a plasma gas flow direction shown according to another exemplary embodiment.
[0025] Figures 6 - 8 It is a schematic diagram of an intermediate structure generated during the first etching of the test wafer.
[0026] Figure 9 It is a schematic structural diagram generated in step S203.
[0027] Figure 10 It is a schematic structural diagram generated in step S204.
[0028] Figure 11 It is to use a critical dimension scanning electron microscope for Figure 10 A schematic diagram of a scanning electron microscope image obtained by scanning the structure shown.
[0029] Figure 12 It is a flowchart of a method for detecting the tilt of a plasma gas flow direction shown according to another exemplary embodiment.
[0030] Figure 13 It is a schematic diagram of 4 measurement positions on a test wafer shown according to another exemplary embodiment.
[0031] Figure 14 It is a flowchart of a method for detecting the tilt of a plasma gas flow direction shown according to another exemplary embodiment. Detailed implementation manners
[0032] Unless otherwise defined, the technical terms or scientific terms used in this specification and claims shall have the ordinary meanings understood by those of ordinary skill in the technical field to which the present invention belongs. The following will describe the specific implementation manners of the present invention in conjunction with the drawings. It should be noted that during the specific description of these implementation manners, for the sake of brevity, this specification cannot describe all the features of the actual implementation manners in detail. Without departing from the spirit and scope of the present invention, those skilled in the art can modify and replace the implementation manners of the present invention, and the obtained implementation manners are also within the protection scope of the present invention.
[0033] In the related art, as Figure 1 shown, when dry etching the wafer 11 to be etched, the wafer 11 to be etched is placed on an electrostatic chuck (ESC) 13 in a chamber 12 of an etching device. An edge ring 14 surrounds the electrostatic chuck 13 and the wafer 11 to be etched. The height of the edge of the edge ring 14 is higher than that of the wafer 11 to be etched. A transformer-coupled plasma window (TCP Window) 15 is provided at the top of the chamber 12. As Figure 1 can be seen, with different heights of the edge ring 14, the tilting behavior of the plasma 16 is different. The tilting of the plasma 16 in the gas flow direction will cause the etched profile to tilt, damage the sidewalls, or result in energy loss due to the scattering of the plasma 16, causing under-etching.
[0034] In some processes, it is necessary to test the product to detect the tilting of the plasma gas flow direction, which wastes the product. In some processes, on-line detection cannot be performed, and only a large number of product WAT or CP can be used for analysis, rather than direct data support.
[0035] To solve the above technical problems, the present application proposes a method for detecting the tilting of the plasma gas flow direction, which can accurately detect the tilting of the plasma gas flow direction used in the dry etching process through an off-line detection method. It is direct and effective. It can detect the tilting of the plasma gas flow direction based on a test wafer, can save wafer products, and thus can save costs. It can also decouple the influence of the wafer itself and exclude the influence of other process factors.
[0036] An embodiment of the present application provides a method for detecting the tilting of the plasma gas flow direction. This method for detecting the tilting of the plasma gas flow direction can be used to off-line detect whether the tilting angle of the plasma gas flow direction used in the dry etching process meets the specified process requirements. As Figure 2 shown, this method for detecting the tilting of the plasma gas flow direction may include the following steps S201 to S206: Step S201: Provide a test wafer; the test wafer includes a wafer and a film layer to be etched, and the film layer to be etched covers the wafer.
[0037] In one embodiment, as Figure 3 shown, a film layer with a certain thickness can be deposited on the wafer 311 as the film layer 312 to be etched in this article to obtain a test wafer 31. The wafer 311 is a blank wafer, which refers to a wafer on which an integrated circuit has not been processed on the surface.
[0038] In one embodiment, the material of the film layer to be etched can be a carbon-based polymer.
[0039] In another embodiment, the material of the film layer to be etched may be silicon oxide.
[0040] In another embodiment, the material of the film layer to be etched may be silicon nitride.
[0041] Step S202: Control the dry etching equipment to emit plasma to dry-etch the film layer to be etched with the process parameters of the target process to obtain an etched film layer; the etched film layer includes a first etched groove; the first etched groove includes a first side wall, a second side wall, a first notch and a first bottom surface, the first side wall, the first bottom surface, and the second side wall are connected in sequence, the first side wall and the second side wall are opposite in position, the first bottom surface and the first notch are opposite, and the first bottom surface is located on the surface of the wafer facing the film layer to be etched.
[0042] If it is necessary to detect whether the tilt angle of the plasma gas flow direction emitted by the dry etching equipment in a certain process meets the specified process requirements, then this process is the target process.
[0043] In one embodiment, as Figure 4 shown, the process parameters of the target process can be used to control the dry etching equipment to emit plasma to dry-etch the film layer to be etched to obtain an etched film layer 41. Among them, the etched film layer 41 includes a first etched groove 411 for exposing the wafer 311. The first etched groove 411 includes a first side wall 4111, a second side wall 4112, a first notch 4113 and a first bottom surface 4114. The first side wall 4111, the first bottom surface 4114, and the second side wall 4112 are connected in sequence. The first side wall 4111 and the second side wall 4112 are opposite in position. The first bottom surface 4114 and the first notch 4113 are opposite, and the first bottom surface 4114 is located on the surface of the wafer facing the film layer to be etched.
[0044] In one embodiment, as Figure 5 shown, step S202 may include the following steps: Step S2021: Form a first photoresist layer on the side of the film layer to be etched away from the wafer.
[0045] As Figure 6 shown, a first photoresist layer 61 is formed on the side of the film layer to be etched 312 away from the wafer 311.
[0046] In one embodiment, the material of the first photoresist layer 61 may be a positive photoresist, but is not limited thereto.
[0047] Step S2022: Pattern the first photoresist layer to obtain a second photoresist layer; the second photoresist layer includes a first shielding portion and an opening, and the opening is used to expose the patterned surface of the film layer to be etched that is not covered by the first shielding portion.
[0048] As Figure 7As shown, the first photoresist layer 61 is patterned to obtain the second photoresist layer 62; the second photoresist layer 62 includes a first shielding portion 621 and an opening 622, and the opening 622 is used to expose the patterned surface on the to-be-etched film layer 312 that is not covered by the first shielding portion 621.
[0049] In step S2023, the dry etching equipment is controlled by the process parameters of the target process to emit plasma toward the patterned surface to perform dry etching on the to-be-etched film layer, obtaining an etched film layer and a second shielding portion; the first shielding portion is obtained as the second shielding portion after dry etching.
[0050] As Figure 8 shown, the dry etching equipment is controlled by the process parameters of the target process to emit plasma toward the patterned surface to perform dry etching on the to-be-etched film layer, obtaining an etched film layer 41 and a second shielding portion 623, wherein the first shielding portion 621 is obtained as the second shielding portion 623 after dry etching.
[0051] As Figure 8 shown, if there is consumption in the edge ring resulting in the inclination of the plasma gas flow direction, it will cause the non-perpendicular opening, and the first sidewall 4111 and the second sidewall 4112 of the first etching groove 411 are inclined. Moreover, the heights of the second shielding portions 623 on both sides of the first notch 4113 are not the same, presenting an asymmetric situation.
[0052] In step S2024, the second shielding portion is removed.
[0053] In this step, the second shielding portion 623 can be removed by ashing (ASH) technology to obtain an intermediate structure as Figure 4 shown. For example, the second shielding portion 623 can be removed by using oxygen plasma.
[0054] In step S203, a first polymer film layer is formed on the side of the etched film layer away from the wafer; the first polymer film layer includes a first masking portion and a second masking portion, the first masking portion covers the part of the first sidewall close to the first notch, the second masking portion covers the part of the second sidewall close to the first notch, and the first masking portion and the second masking portion are symmetric.
[0055] As Figure 9 shown, in this step, a first polymer film layer 91 is formed on the side of the etched film layer away from the wafer. The first polymer film layer 91 includes a first masking portion 911 and a second masking portion 912. The first masking portion 911 covers the part of the first sidewall 4111 close to the first notch 4113, the second masking portion covers the part of the second sidewall 4112 close to the first notch 4113, and the first masking portion and the second masking portion are symmetric.
[0056] In this step, chemical vapor deposition can be carried out using the first gas and the second gas in a specified ratio and a pulsed deposition process to obtain the second polymer film layer, so as to ensure that the polymer is mainly deposited on the first sidewall 4111 and the second sidewall 4112, and will not accumulate too much at the bottom of the first etching groove 411.
[0057] Among them, at least carbon ions and fluorine ions are generated after the dissociation of the first gas and the second gas, and the material of the second polymer film layer includes carbon element and fluorine element. For example, in one embodiment, the first gas is C4F6, the second gas is CH3F, and the material of the second polymer film layer includes carbon element and fluorine element.
[0058] In another embodiment, carbon ions, fluorine ions and hydrogen ions are generated after the dissociation of the first gas and the second gas, and the material of the second polymer film layer is carbon element, fluorine element and hydrogen element. Since hydrogen ions are also generated after the dissociation of the first gas and the second gas, the second polymer film layer can be made more polymerized, increasing the viscosity of the second polymer film layer, so that it is easier to deposit on the first sidewall 4111 and the second sidewall 4112 of the first etching groove 411 and the surface of the etching film layer 41.
[0059] Step S204, controlling the dry etching equipment to emit plasma to dry-etch the wafer located at the bottom of the first etching groove by using the process parameters of the target process to obtain the object to be measured, and the object to be measured includes the etched wafer; the etched wafer includes a second etching groove, and the second notch of the second etching groove is located on the first bottom surface of the first etching groove.
[0060] In this step, the dry etching equipment is again controlled to emit plasma to dry-etch the wafer located at the bottom of the first etching groove 411 by using the process parameters of the target process to obtain Figure 10 the object to be measured as shown, and the object to be measured includes the etched wafer 313, and the etched wafer 313 includes a second etching groove 421, and the second notch 4211 of the second etching groove is located on the first bottom surface 4114 of the first etching groove 411.
[0061] As Figure 10 shown, if there is consumption of the edge ring resulting in the inclination of the plasma gas flow direction, it will cause the inability to vertically open, and there will be asymmetric etching of the first mask portion 911 and the second mask portion 912, and further cause the widths of the remaining parts of the first bottom surface 4114 of the first etching groove 411 on both sides of the second notch 4211 to be different. That is, the first edge width value n1 is different from the second edge width value n2, where the first edge width value n1 is the distance value between the bottom end of the first sidewall 4111 on the first bottom surface 4114 and the second notch, and the second edge width value n2 is the distance value between the bottom end of the second sidewall 4112 on the first bottom surface 4114 and the second notch.
[0062] Step S205, obtain a first edge width value and a second edge width value; the first edge width value is the distance value between the bottom end of the first side wall on the first bottom surface and the second notch, and the second edge width value is the distance value between the bottom end of the second side wall on the first bottom surface and the second notch.
[0063] In one embodiment, a critical dimension scanning electron microscope can be used to scan the object to be measured in the first direction to obtain a Figure 11 scanning electron microscope image as shown. The first direction points from the etched film layer to the etched wafer. Then, based on the scanning electron microscope image, the first edge width value n1 and the second edge width value n2 are obtained.
[0064] That is, a critical dimension scanning electron microscope can be used to scan the object to be measured from top to bottom to obtain a Figure 11 first top view as shown (the scanning electron microscope image is the first top view). Then, the first top view is processed and measured to obtain the first edge width value n1 and the second edge width value n2, instead of measuring the first edge width value n1 and the second edge width value n2 by slicing.
[0065] In another embodiment, step S205 may include: First, the object to be measured can be sliced to obtain the sliced object to be measured. Then, an FA (Failure Analysis) lens can be used to scan the cross-section of the sliced object to be measured to obtain a cross-sectional view. Then, based on the cross-sectional view, the first edge width value n1 and the second edge width value n2 are obtained.
[0066] Step S206, determine whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first edge width value and the second edge width value.
[0067] In one embodiment, the minimum value of the first edge width value and the second edge width value can be determined. For example, when the first edge width value n1 is greater than the second edge width value n2, the minimum value is the second edge width value n2. Then, when it is determined that the above minimum value tends to zero, it is determined that the inclination angle of the plasma gas flow direction does not meet the specified process requirements. When the above minimum value tends to zero, it means that the inclination angle of the plasma gas flow direction is relatively large and does not meet the specified process requirements. Among them, when the above minimum value is less than the specified value, it can be determined that the above minimum value tends to zero, and the specified value can be a value close to 0.
[0068] In another embodiment, it can be determined whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on the first edge width value and the second edge width value. The specific method is as follows: First, obtain a reference absolute value, which can be the absolute value of the difference between a first edge width value n1 and a second edge width value n2 when the yield of the wafer product is lower than a specified threshold. Then, obtain the absolute value of the difference between the first edge width value and the second edge width value as a measured absolute value. Then, obtain the difference between the reference absolute value and the measured absolute value as a target difference. Then, when the target difference is greater than a specified difference, it is determined that the tilt angle of the plasma gas flow direction does not meet the specified process requirements. That is, when the absolute value of the difference between the first edge width value and the second edge width value is relatively large, it indicates that the tilt angle of the plasma gas flow direction is relatively large and does not meet the specified process requirements.
[0069] In an embodiment of the present application, the tilt of the plasma gas flow direction used in the dry etching process can be detected offline, and the tilt detection of the plasma gas flow direction can be realized based on a test wafer, which can save wafer products, thereby saving costs. At the same time, the influence of other process factors can be excluded. Moreover, through the above etching-depositing the first polymer film layer-etching method, the first edge width value and the second edge width value that are easy to measure can be formed, which is direct and effective, and accurate tilt detection can be achieved. When detecting, the process parameters of the specified process are used to control the dry etching equipment to emit plasma to etch a test wafer that has not undergone other process steps, which can exclude the influence of other process factors.
[0070] The technical solution provided by the embodiment of the present application can use a test wafer to detect offline whether the tilt degree of the plasma gas flow direction meets the specified process requirements. When it does not meet the specified process requirements, it can be prevented in advance and the edge ring can be replaced, which is beneficial to improving the product yield.
[0071] The above introduced the tilt detection method of the plasma gas flow direction taking a single chip on the test wafer as the measurement object. Next, the tilt detection method of the plasma gas flow direction will be introduced taking multiple chips on the test wafer as the measurement object.
[0072] Another embodiment of the present application provides a method for detecting the tilt of the plasma gas flow direction. Please refer to Figure 12 , the above step S205 may include the following steps S2051 to S2052: Step S2051, determine N chips on the object to be measured as measurement positions, and the N chips are evenly distributed on the edge of the etched wafer; N is an integer greater than 1.
[0073] In this step, as Figure 13As shown, N chips 314 on the object to be measured are determined as N measurement positions, and the N chips 314 are evenly distributed on the edge of the etched wafer; N is an integer greater than 1. For example, N is an even number. For another example, N is 4. Among the 4 chips 314, the center lines 315 of the chips with opposite positions are symmetric about the center of the test wafer. Of course, N can also be an even number such as 2, 6, 8, etc.
[0074] Step S2052, for each test position, obtain a pair of first edge width values and second edge width values, and obtain N first edge width values and N second edge width values.
[0075] In this step, for each chip 314, obtain a pair of first edge width values and second edge width values, and obtain N first edge width values and N second edge width values.
[0076] Please refer to Figure 14 The above step S206 may include the following steps S2061 to S2063: Step S2061, obtain the average value of the N first edge width values to obtain the first average edge width value.
[0077] Step S2062, obtain the average value of the N second edge width values to obtain the second average edge width value.
[0078] Step S2063, determine whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first average edge width value and the second average edge width value.
[0079] In this embodiment, the average value of the N first edge width values can be obtained to obtain the first average edge width value, and the average value of the N second edge width values can be obtained to obtain the second average edge width value. Then, determine whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on at least one of the first average edge width value and the second average edge width value.
[0080] In one embodiment, the minimum value of the first average edge width value and the second average edge width value can be determined. For example, when the first average edge width value is greater than the second average edge width value, the minimum value is the second average edge width value. Then, when it is determined that the above minimum value tends to zero, it is determined that the inclination angle of the plasma gas flow direction does not meet the specified process requirements. When the above minimum value tends to zero, it means that the inclination angle of the plasma gas flow direction is relatively large and does not meet the specified process requirements.
[0081] In another embodiment, it can be determined whether the inclination angle of the plasma gas flow direction meets the specified process requirements based on the first average edge width value and the second average edge width value. The specific method is as follows: First, obtain a reference absolute value, which can be the absolute value of the difference between a first average edge width value and a second average edge width value when the yield of the wafer product is lower than a specified threshold. Then, obtain the absolute value of the difference between the first average edge width value and the second average edge width value as a measured absolute value. Then, obtain the difference between the reference absolute value and the measured absolute value as a target difference. Then, when the target difference is greater than a specified difference, it is determined that the tilt angle of the gas flow direction of the plasma does not meet the specified process requirements. That is, when the absolute value of the difference between the first average edge width value and the second average edge width value is relatively large, it indicates that the tilt angle of the gas flow direction of the plasma is relatively large and does not meet the specified process requirements.
[0082] In the embodiment of the present application, after the wafer is prepared, an overlapping pattern is formed by the above-mentioned etching-depositing the first polymer film layer-etching method, and measurement can be performed by slicing or SEMCD. If only one etching is used for testing, due to the thickness limitation of the photoresist, if the aspect ratio of the formed pattern is not large enough, the effect is not significant. By the above-mentioned etching-depositing the first polymer film layer-etching method, the profile tilt degree can be enhanced, and then more accurate measurement can be performed.
[0083] In the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless otherwise clearly defined.
[0084] The above description of the embodiments is to enable those of ordinary skill in the art to understand and apply the present application. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present application is not limited to the embodiments herein, and the improvements and modifications made by those skilled in the art without departing from the scope and spirit of the present application are within the scope of the present application.
Claims
1. A method for detecting the inclination of the plasma gas flow direction, characterized in that Including: Providing a test wafer; the test wafer includes a wafer and an etching target film layer, and the etching target film layer covers the wafer; Controlling a dry etching apparatus to emit plasma according to process parameters of a target process to perform dry etching on the etching target film layer, so as to obtain an etched film layer; the etched film layer includes a first etching groove; the first etching groove includes a first sidewall, a second sidewall, a first notch, and a first bottom surface, the first sidewall, the first bottom surface, and the second sidewall are connected in sequence, the first sidewall and the second sidewall are opposite in position, the first bottom surface and the first notch are opposite, and the first bottom surface is located on the surface of the wafer facing the etched film layer; Forming a first polymer film layer on a side of the etched film layer away from the wafer; the first polymer film layer includes a first mask portion and a second mask portion, the first mask portion covers a part of the first sidewall close to the first notch, the second mask portion covers a part of the second sidewall close to the first notch, and the first mask portion and the second mask portion are symmetrical; Controlling the dry etching apparatus to emit plasma according to the process parameters to perform dry etching on the wafer located at the bottom of the first etching groove, so as to obtain an object to be measured, the object to be measured includes an etched wafer; the etched wafer includes a second etching groove, and a second notch of the second etching groove is located on the first bottom surface of the first etching groove; Obtaining a first edge width value and a second edge width value; the first edge width value is a distance value between a bottom end of the first sidewall on the first bottom surface and the second notch, and the second edge width value is a distance value between a bottom end of the second sidewall on the first bottom surface and the second notch; Determining whether an inclination angle of an air flow direction of the plasma meets a specified process requirement based on at least one of the first edge width value and the second edge width value.
2. The method for detecting the inclination of the plasma gas flow direction according to claim 1, characterized in that The controlling the dry etching apparatus to emit plasma according to the process parameters of the target process to perform dry etching on the etching target film layer to obtain an etched film layer includes: Forming a first photoresist layer on a side of the etching target film layer away from the wafer; Patterning the first photoresist layer to obtain a second photoresist layer; the second photoresist layer includes a first shielding portion and an opening, and the opening is used to expose a patterned surface of the etching target film layer that is not covered by the first shielding portion; Controlling the dry etching apparatus to emit plasma toward the patterned surface according to the process parameters to perform dry etching on the etching target film layer, so as to obtain the etched film layer and a second shielding portion; the first shielding portion is obtained as the second shielding portion after dry etching; Removing the second shielding portion.
3. The method for detecting the inclination of the plasma gas flow direction according to claim 1, wherein The forming the first polymer film layer on a side of the etched film layer away from the wafer includes: Performing chemical vapor deposition by using a first gas and a second gas with a specified ratio and a pulsed deposition process to obtain a second polymer film layer; at least carbon ions and fluorine ions are generated after dissociation of the first gas and the second gas, and the material of the second polymer film layer includes carbon element and fluorine element.
4. The method for detecting the inclination of the plasma gas flow direction according to claim 3, characterized in that, The first gas is C4F6, and the second gas is CH3F.
5. The method for detecting the inclination of the plasma gas flow direction according to claim 3, wherein After the dissociation of the first gas and the second gas, hydrogen ions are also generated, and the material of the second polymer film layer further includes hydrogen element.
6. The method for detecting the inclination of the plasma gas flow direction according to claim 1, characterized in that The obtaining of the first edge width value and the second edge width value includes: Scanning the object to be measured in a first direction by using a critical dimension scanning electron microscope to obtain a scanning electron microscope image; the first direction points from the etched film layer to the etched wafer. Obtaining the first edge width value and the second edge width value based on the scanning electron microscope image.
7. The method for detecting the inclination of the plasma gas flow direction according to claim 1, wherein The obtaining of the first edge width value and the second edge width value includes: Slicing the object to be measured to obtain the sliced object to be measured. Scanning the cross-section of the sliced object to be measured by using a failure analysis lens to obtain a cross-sectional view. Obtaining the first edge width value and the second edge width value based on the cross-sectional view.
8. The method for detecting the inclination of the plasma gas flow direction according to claim 1, characterized in that, The obtaining of the first edge width value and the second edge width value includes: Determining N chips on the object to be measured as measurement positions, and the N chips are evenly distributed on the edge of the etched wafer; N is an integer greater than 1. For each test position, obtaining a pair of the first edge width value and the second edge width value to obtain N first edge width values and N second edge width values. The determining whether the inclination angle of the gas flow direction of the plasma meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Obtaining the average value of the N first edge width values to obtain a first average edge width value. Obtaining the average value of the N second edge width values to obtain a second average edge width value. Determining whether the inclination angle of the gas flow direction of the plasma meets the specified process requirements based on at least one of the first average edge width value and the second average edge width value.
9. The method for detecting the inclination of the plasma gas flow direction according to claim 8, characterized in that N is an even number, or N is 4.
10. The method for detecting the inclination of the plasma gas flow direction according to claim 1, wherein The determining whether the inclination angle of the gas flow direction of the plasma meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Determining the minimum value among the first edge width value and the second edge width value. When the minimum value approaches zero, determining that the inclination angle of the gas flow direction of the plasma does not meet the specified process requirements.
11. The method for detecting the inclination of the plasma gas flow direction according to claim 1, characterized in that The determining whether the inclination angle of the gas flow direction of the plasma meets the specified process requirements based on at least one of the first edge width value and the second edge width value includes: Obtaining a reference absolute value, where the reference absolute value is the absolute value of the difference between the first edge width value and the second edge width value when the yield rate of the wafer product is lower than the specified threshold. Obtaining the absolute value of the difference between the first edge width value and the second edge width value as a measurement absolute value. Obtaining the difference between the reference absolute value and the measurement absolute value as a target difference. When the target difference is greater than the specified difference, determining that the inclination angle of the gas flow direction of the plasma does not meet the specified process requirements.
12. The method for detecting the inclination of the plasma gas flow direction according to claim 1, characterized in that The material of the film layer to be etched is a carbon-based polymer, silicon oxide or silicon nitride.