Method for constructing three-dimensional damage degree model, damage degree evaluation method and system

Abstract

The present application relates to the technical field of semiconductor, in particular to a method for constructing a three-dimensional damage degree model, a damage degree evaluation method and system, comprising: selecting a standard part, defining at least three concentric circular regions on the XY plane of the standard part, setting a plurality of measurement points in each circular region, measuring and recording the standard wetting angle of the measurement points; selecting a plurality of samples, the samples being wafers processed by a predetermined process, setting measurement points on the wafers on the surface of the low dielectric material layer of the wafers, and measuring the surface wetting angle of each measurement point on the wafers; calculating the damage degree of the measurement points based on the standard wetting angle and the surface wetting angle; slicing each measurement point, measuring the cross-sectional wetting angle of each slice, and calculating the damage depth of each measurement point; and constructing a three-dimensional damage degree model based on the damage degree, the damage depth, and the surface wetting angle. The present application can accurately quantify the damage degree of low dielectric material caused by plasma etching, and clearly identify the damage source.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to a method for constructing a three-dimensional damage level model, a damage level evaluation method, and a system. Background Technology

[0002] With the rapid development of semiconductor technology and the continuous emergence of new process nodes, the integration density of chips has been significantly improved. This improvement not only brings higher performance but also places more stringent requirements on chip manufacturing processes. At more advanced process nodes, the spacing between interconnects and wires is significantly reduced, which directly leads to an increase in resistance (R) and parasitic capacitance (C), thus making the RC signal delay problem increasingly prominent. The speed of integrated circuits is largely limited by RC delay; therefore, effectively reducing RC delay has become the key to improving chip performance.

[0003] In the Damascus trench etching process, plasma etching is a core step that has a crucial impact on the final performance of the chip. However, with the widespread use of low-dielectric materials in advanced processes, the damage caused by plasma etching to these materials has gradually come to the forefront. The selection of low-dielectric materials aims to reduce parasitic capacitance, thereby reducing RC delay. However, damage that may occur during some processes (such as plasma etching, cleaning, and barrier layer pretreatment) can compromise the dielectric properties of the material, leading to an increase in RC values ​​and ultimately affecting the overall performance of the chip.

[0004] Currently, the main method for assessing the damage caused by plasma etching to low-dielectric materials relies on RC testing after all process steps have been completed. However, this method has several drawbacks: First, the testing cycle is long, which is not conducive to rapid iteration and process optimization; second, the RC test results cannot truly reflect the three-dimensional extent of plasma etching damage, i.e., key information such as the depth of damage cannot be obtained; finally, even if the RC results are abnormal, it is impossible to quantitatively distinguish whether the damage to the low-dielectric material is caused by the etching step, the cleaning step, or the barrier layer pretreatment step.

[0005] Therefore, it is necessary to develop a new method for constructing a three-dimensional damage level model, a damage level evaluation method, and a system. Summary of the Invention

[0006] The purpose of this invention is to provide a method for constructing a three-dimensional damage level model, a damage level evaluation method and system, which can accurately quantify the damage level of plasma etching to low dielectric materials and identify the source of damage, thereby providing strong support for optimizing process parameters and improving chip performance.

[0007] In a first aspect, the method for constructing a three-dimensional damage level model according to the present invention includes the following steps:

[0008] Select a standard part and define at least three concentric circular regions on the XY plane of the standard part. Set multiple measurement points in each circular region, measure and record the standard wetting angle of each measurement point;

[0009] Multiple samples are selected, which are wafers processed by a preset process. For each wafer, measurement points are set on the surface of the low-dielectric material layer of the wafer according to the method of setting measurement points on the standard part, and the surface wetting angle of each measurement point on the wafer is measured. The damage degree of the measurement point is calculated based on the standard wetting angle and the surface wetting angle of the measurement point. Each measurement point is sliced, and the cross-sectional wetting angle of each slice is measured, and the damage depth of each measurement point is calculated.

[0010] Based on the damage level, damage depth, and surface wetting angle, a three-dimensional damage level model is constructed.

[0011] Optionally, the measurement of the wetting angle of each slice section specifically involves:

[0012] The slice to be tested is placed on a rotating platform, and the low dielectric material layer is divided into n equal parts along the thickness direction of the low dielectric material layer, and the parts are marked sequentially from the side of the low dielectric material layer away from the silicon layer as the 1st division line to the nth division line.

[0013] Measure the wetting angle of the cross section at the 1st bisector and calculate the difference between the standard wetting angle and the cross section wetting angle; if the difference is greater than a preset angle value, rotate the slice by a preset rotation angle; and repeat the above measurement and difference calculation operation until the difference is less than or equal to the preset angle value, or the number of rotations reaches the preset number of rotations;

[0014] If the number of rotations reaches the preset number of rotations and the difference is still greater than the preset angle value, then the wetting angle of the cross section is measured sequentially at the 2nd to nth bisectors until the difference is less than or equal to the preset angle value, or all bisectors have been measured.

[0015] Optionally, the calculation of the damage depth at each measurement point specifically involves:

[0016] ;

[0017] in: This represents the damage depth at the i-th measurement point on the wafer;

[0018] q represents the number of equal divisions performed during the measurement process when the difference between the measured standard wetting angle and the cross-sectional wetting angle is less than or equal to the preset angle value;

[0019] h represents the total thickness of the low-dielectric material layer;

[0020] d represents the size of the droplet on the slice surface;

[0021] m represents the number of rotations in a clockwise direction;

[0022] γ represents the preset rotation angle. The formula calculates the damage level at each measurement point on the wafer into a specific damage depth, providing intuitive data support for damage assessment. The formula considers multiple factors, including the number of divisions, the total thickness of the material layer, the droplet size, the number of rotations, and the rotation angle, ensuring the accuracy and comprehensiveness of the calculation results.

[0023] Optionally, at least three concentric circular regions are defined on the XY plane of the standard part, specifically:

[0024] On the XY plane of the standard part, at least one circular region is provided near the center, one circular region near the edge, and one circular region in between. At least three measurement points are set in each circular region, and these measurement points are evenly distributed around the circumference. By setting at least three concentric circular regions on the XY plane of the standard part, and setting multiple measurement points in each region, the comprehensiveness and representativeness of the measurement can be ensured. The evenly distributed circumference of the measurement points simplifies the measurement process and improves measurement efficiency.

[0025] Optionally, the calculation of the damage degree at each measurement point specifically involves:

[0026] Di = (αi - βi) / αi;

[0027] Where Di represents the degree of damage at the i-th measurement point on the wafer after the preset process;

[0028] αi represents the standard wetting angle at the i-th measurement point on the standard part;

[0029] βi represents the surface wetting angle at the i-th measurement point on the wafer after the preset process. Calculation using the formula can intuitively reflect the degree of damage at each measurement point on the wafer, providing strong data support for damage assessment. The parameters in the formula are easy to obtain and measure, making the calculation process simple and feasible.

[0030] Optionally, the construction of a three-dimensional damage degree model based on the damage degree, damage depth, and surface wetting angle specifically involves:

[0031] Based on the data from each sample, a formula for the degree of three-dimensional damage to wafers was established.

[0032] A three-dimensional damage degree model is established based on the three-dimensional damage degree relationship of the wafer and the surface wetting angle.

[0033] The three-dimensional damage level model is a formula relating wafer damage depth to surface wetting angle. Based on data from various samples, a three-dimensional damage level formula is established, and a three-dimensional damage level model is constructed, providing a scientific basis for damage assessment and prediction. The constructed three-dimensional damage level model can be applied to different types of wafers and process conditions, exhibiting broad applicability.

[0034] Secondly, the method for evaluating the degree of damage to low-dielectric materials according to the present invention includes the following steps:

[0035] Select a standard part and define at least three concentric circular regions on the XY plane of the standard part. Set multiple measurement points in each circular region, measure and record the standard wetting angle of each measurement point;

[0036] Select the test piece, which is a wafer processed by a preset process. On the surface of the low dielectric material layer of the wafer, set measurement points according to the method of setting measurement points on the standard part, and measure the surface wetting angle of each measurement point on the wafer.

[0037] The degree of damage at the measurement point is calculated based on the standard wetting angle and the surface wetting angle at the measurement point.

[0038] Based on the surface wetting angle of the component under test and the degree of damage, the damage depth and its distribution are evaluated using a three-dimensional damage degree model.

[0039] The three-dimensional damage level model is obtained using the method for constructing a three-dimensional damage level model as described in this invention.

[0040] Optionally, at least three concentric circular regions are defined on the XY plane of the standard part, specifically:

[0041] On the XY plane of the standard part, at least one circular region is provided near the center, one circular region near the edge, and one circular region in between. At least three measurement points are set in each circular region, and these measurement points are evenly distributed around the circumference. By setting at least three concentric circular regions on the XY plane of the standard part, and setting multiple measurement points in each region, the comprehensiveness and representativeness of the measurement can be ensured. The evenly distributed circumference of the measurement points simplifies the measurement process and improves measurement efficiency.

[0042] Optionally, the calculation of the damage degree at the measurement point specifically includes:

[0043] Di = (αi - βi) / αi;

[0044] Where Di represents the degree of damage at the i-th measurement point on the wafer after the preset process;

[0045] αi represents the standard wetting angle at the i-th measurement point on the standard part;

[0046] βi represents the surface wetting angle at the i-th measurement point on the wafer after the preset process. Calculation using the formula can intuitively reflect the degree of damage at each measurement point on the wafer, providing strong data support for damage assessment. The parameters in the formula are easy to obtain and measure, making the calculation process simple and feasible.

[0047] Thirdly, the low-dielectric material damage assessment system of the present invention includes:

[0048] The standard part data acquisition module is used to define at least three concentric circular regions on the XY plane of the standard part, set multiple measurement points in each circular region, and measure and record the standard wetting angle of each measurement point;

[0049] The test piece data acquisition module is used to select the wafer after the preset process as the test piece, select the measurement points using the same method as the standard part data acquisition module, and measure the surface wetting angle of each measurement point;

[0050] The damage degree calculation module calculates the damage degree of each measurement point on the wafer based on the standard wetting angle obtained by the standard part data acquisition module and the surface wetting angle obtained by the test part data acquisition module.

[0051] The low dielectric material damage assessment module is used to assess the damage depth and distribution of the test piece based on the surface wetting angle and the damage degree of the test piece using a three-dimensional damage degree model.

[0052] The three-dimensional damage level model is obtained using the method for constructing a three-dimensional damage level model as described in this invention.

[0053] The unexpected beneficial effects of this invention are as follows:

[0054] 1. Significantly shortens the testing cycle:

[0055] By constructing a three-dimensional damage level model, this invention can assess the damage of multiple test pieces in a short time, without waiting for complete RC test results. This significantly shortens the testing cycle and accelerates process iteration and optimization.

[0056] 2. Precisely quantify the degree of three-dimensional damage:

[0057] This invention, by measuring the surface wetting angle and cross-sectional wetting angle, can accurately quantify the three-dimensional damage (including damage depth) of low-dielectric materials caused by different processes through a three-dimensional damage degree model. This overcomes the limitations of RC testing in reflecting three-dimensional damage.

[0058] 3. Identify the source of damage and guide process optimization:

[0059] This invention can quantitatively distinguish the damage contribution of different process steps to low-dielectric materials. This helps technicians accurately identify the main sources of damage and make targeted process adjustments to improve chip performance and process stability.

[0060] 4. Improve the accuracy of process parameter optimization:

[0061] The three-dimensional damage level model provided by this invention offers strong support for optimizing process parameters. By predicting the damage level under different process parameters using the model, technicians can more accurately adjust the parameters to reduce unnecessary damage and improve product yield and performance.

[0062] 5. Enhance the monitoring and control capabilities for damage in low-dielectric materials:

[0063] The evaluation method and system of this invention are not only applicable to post-process damage assessment, but also to real-time monitoring and control of damage during the process. This helps to promptly identify and correct process deviations, ensuring the consistency and stability of product quality.

[0064] In summary, this invention can accurately quantify the damage caused by plasma etching to low-dielectric materials and identify the source of damage, thereby providing strong support for optimizing process parameters and improving chip performance. Attached Figure Description

[0065] Figure 1 This is a flowchart of the method for constructing a three-dimensional damage level model in the embodiments of this application;

[0066] Figure 2 This is a flowchart illustrating the measurement of the wetting angle of the cross section of the slice in this embodiment of the application;

[0067] Figure 3 This is a schematic diagram of the wafer structure in the embodiments of the application;

[0068] Figure 4 This is a schematic diagram of the internal structure of the wafer in the embodiment of the application;

[0069] Figure 5 This is a schematic diagram showing the distribution of measurement points in one embodiment of this application;

[0070] Figure 6 This is a diagram showing the correspondence between wetting angle and damage degree in the embodiments of this application;

[0071] Figure 7 This is a schematic diagram illustrating one method of slicing each measurement point in an embodiment of this application;

[0072] Figure 8This is a schematic diagram of the dividing lines in the embodiments of this application;

[0073] Figure 9 This is a flowchart of the method for evaluating the damage level of low-dielectric materials in the embodiments of this application;

[0074] Figure 10 This is a schematic diagram of the low-dielectric material damage assessment system in the embodiments of this application;

[0075] In the diagram: 1-wafer, 11-low dielectric material layer, 12-silicon layer, 13-measurement point, 2-cutting line, 3-dividing line. Detailed Implementation

[0076] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0077] like Figure 1 As shown in the embodiments of this application, a method for constructing a three-dimensional damage level model includes the following steps:

[0078] Select standard parts, in standard parts (see Figure 3 Define at least three concentric circular regions on the XY plane, set multiple measurement points in each circular region, and measure and record the standard wetting angle of each measurement point.

[0079] Multiple samples were selected, and the samples were wafers 1 after being processed by a preset process (see [reference]). Figure 4 For each wafer 1 (comprising a low-dielectric material layer 11 and a silicon layer 12), measurement points are set on the surface of the low-dielectric material layer 11 using a method similar to setting measurement points on a standard component, ensuring that each measurement point on wafer 1 corresponds one-to-one with each measurement point on the standard component. The surface wetting angle of each measurement point on wafer 1 is measured. The degree of damage at each measurement point is calculated based on the standard wetting angle and the surface wetting angle. Each measurement point is sliced, and the cross-sectional wetting angle of each slice is measured, as well as the damage depth at each measurement point is calculated.

[0080] A three-dimensional damage level model is constructed based on the degree of damage, the depth of damage, and the surface wetting angle.

[0081] The three-dimensional damage level model provided in this application provides strong support for the optimization of process parameters. The three-dimensional damage level model can predict the damage level under different process parameters.

[0082] In one possible embodiment, each measurement point is sliced ​​separately, such as... Figure 7 Cutting line 2 in the diagram is just an example; other cutting methods can also be used, as long as all measurement points are cut.

[0083] like Figure 2 As shown, in one possible embodiment, the wetting angle of each slice is measured, specifically:

[0084] The slice to be tested is placed on a rotating platform, and the low dielectric material layer is divided into n equal parts along the thickness direction of the low dielectric material layer. The parts are marked sequentially from the side of the low dielectric material layer away from the silicon layer as the 1st division line to the nth division line.

[0085] Measure the wetting angle of the cross section at the 1st bisector and calculate the difference between the standard wetting angle and the cross section wetting angle. If the difference is greater than the preset angle value, rotate the slice according to the preset rotation angle. Repeat the above measurement and difference calculation operation until any of the following conditions are met: the difference is less than or equal to the preset angle value; the number of rotations reaches the preset number of rotations. If the number of rotations reaches the preset number of rotations and the difference is still greater than the preset angle value, measure the wetting angle of the cross section sequentially at the 2nd bisector to the nth bisector until the difference is less than or equal to the preset angle value, or all bisectors have been measured.

[0086] For example, the example scenario is set up as follows:

[0087] 1. Slicing:

[0088] like Figure 8 As shown, the low dielectric material layer 11 is divided into 10 equal parts (n=10) along the thickness direction, and the dividing lines 3 are successively divided into 1 to 10 equal parts.

[0089] 2. Standard wetting angle:

[0090] Assume the standard wetting angle is 129°.

[0091] 3. Preset angle value:

[0092] Assuming the preset angle value is 5°, the measurement will stop when the difference between the wetting angle of the measured section and the standard wetting angle is ≤5°.

[0093] 4. Rotation parameters:

[0094] The preset rotation angle is 10°, and the preset number of rotations is 18 (i.e., a 180° rotation). Specific steps are shown below:

[0095] Slice Placement and Division: Place the slice to be tested on a rotating platform. Divide the slice into ten equal parts along the thickness direction of the low dielectric material layer, and mark them as the 1st to 10th division lines.

[0096] Measurement at the 1st bisector: Measure the wetting angle of the cross section at the 1st bisector. Assuming the measured wetting angle of the cross section is 115°, calculate the difference between the standard wetting angle and the cross section wetting angle: 129° - 115° = 14°. Since 14° > 5°, proceed with rotation and repeat the measurement.

[0097] Rotate and repeat the measurement: Rotate the slice clockwise according to the preset rotation angle (e.g., 10°). After rotation, the angle is 10°. Measure the wetting angle of the cross section again. Assuming the measured wetting angle of the cross section is 120°, calculate the difference between the standard wetting angle and the cross section wetting angle: 129° - 120° = 9°. Since 9° > 5°, continue rotating.

[0098] Repeat the above steps and record the measurement results after each rotation:

[0099] Assuming that the measured wetting angle of the cross section is 126° after the third rotation, calculate the difference between the standard wetting angle and the cross section wetting angle: 129° - 126° = 3°. Since 3° < 5°, the stopping condition is met.

[0100] Stop the measurement and record the final result as follows: at the bisector line, when rotated 30°, the wetting angle of the cross section is 126°.

[0101] If, at the first bisector, after rotating 18 times (180°), the difference between the standard wetting angle and the cross-sectional wetting angle is still greater than 5°, then switch to the second bisector. If the condition is still not met at the second bisector, continue switching to the third bisector, until all bisectors have been measured.

[0102] In one possible embodiment, the damage depth at the measurement point is calculated as follows:

[0103] ;

[0104] in: γ represents the damage depth at the i-th measurement point on the wafer. q represents the number of equal divisions performed during the measurement process when the difference between the measured standard wetting angle and the cross-sectional wetting angle is less than or equal to a preset angle value. h represents the total thickness of the low-dielectric material layer. n represents the total thickness of the low-dielectric material layer divided by the preset thickness. d represents the size of the droplet on the slice surface. m represents the number of clockwise rotations. γ represents the preset rotation angle. This is a correction term. Through formula calculation, the degree of damage at each measurement point on the wafer can be quantified into a specific damage depth, providing intuitive data support for damage assessment. The formula considers multiple factors such as the number of equal divisions, the total thickness of the material layer, the droplet size, the number of rotations, and the rotation angle, ensuring the accuracy and comprehensiveness of the calculation results.

[0105] In this embodiment, the purpose of rotating the slice is to evaluate the wetting behavior of the material under different directions or angles. Due to possible microstructural differences within the material (such as grain orientation, porosity distribution, etc.), these differences may affect the size of the wetting angle. By rotating the slice and measuring the wetting angle at different angles, more comprehensive information on the wetting behavior can be obtained, thereby more accurately assessing the degree of damage to the material.

[0106] For example: If the difference between the standard wetting angle measured after rotating 3 times on the bisector line and the wetting angle of the cross section is less than or equal to the preset angle value, then q=2 and m=3.

[0107] Assume: γ = 10°, n = 10, m = 3, q ​​= 2, then:

[0108] ;

[0109] Then, based on h and d, it can be calculated that The value of .

[0110] In one possible embodiment, at least three concentric circular regions are defined on the XY plane of the standard part. Specifically, at least one circular region near the center, one circular region near the edge, and one circular region in between are provided on the XY plane of the standard part. At least three measurement points are set on each circular region, and the measurement points are evenly distributed around the circumference. By setting at least three concentric circular regions on the XY plane of the standard part, and setting multiple measurement points in each region, the comprehensiveness and representativeness of the measurement can be ensured. The even distribution of the measurement points around the circumference simplifies the measurement process and improves measurement efficiency.

[0111] like Figure 5 As shown, in one example, three annular regions are set on the XY plane of the standard part, and four measurement points are set in each annular region in a circularly distributed manner.

[0112] In one possible embodiment, the degree of damage at the measurement point is calculated as follows:

[0113] Di = (αi - βi) / αi;

[0114] Where Di represents the damage level at the i-th measurement point on the wafer after the preset process. αi represents the standard wetting angle at the i-th measurement point on the standard part. βi represents the surface wetting angle at the i-th measurement point on the wafer after the preset process. The formula calculation can intuitively reflect the damage level at each measurement point on the wafer, providing strong data support for damage assessment. The parameters in the formula are easy to obtain and measure, making the calculation process simple and feasible.

[0115] A smaller measured surface wetting angle indicates more severe damage to the low-dielectric material. For example: Figure 6 The damage was greatest in (c).

[0116] In one possible embodiment, a three-dimensional damage level model is constructed based on the damage degree, damage depth, and surface wetting angle, specifically as follows:

[0117] Based on the data from each sample, a relationship formula for the degree of three-dimensional damage to wafers is established. The specific formula for the degree of three-dimensional damage to wafers is: Gi(Di, ),in, Let represent the damage depth of the i-th measurement point on the wafer, and let Di represent the damage level of the i-th measurement point on the wafer after the preset process.

[0118] A three-dimensional damage degree model is established based on the relationship between the wafer's three-dimensional damage degree and the surface wetting angle; the three-dimensional damage degree model is the correspondence between the wafer damage depth and the surface wetting angle. If 12 measurement points are set (see...),... Figure 5 If i = 1, 2, ..., 12, then i = 1, 2, ..., 12. Based on the data of each sample, a three-dimensional damage degree relationship for the wafer is established, and a three-dimensional damage degree model is constructed, providing a scientific basis for damage assessment and prediction. The constructed three-dimensional damage degree model can be applied to different types of wafers and process conditions, and has wide applicability.

[0119] like Figure 9 As shown in the embodiments of this application, a method for evaluating the degree of damage to low-dielectric materials includes the following steps:

[0120] Select a standard part and define at least three concentric circular regions on the XY plane of the standard part. Set multiple measurement points in each circular region, measure and record the standard wetting angle of each measurement point.

[0121] Select the component to be tested, which is a wafer processed by a preset process. On the surface of the low dielectric material layer of the wafer, set the measurement points according to the method of setting measurement points on the standard component, and measure the surface wetting angle of each measurement point on the wafer.

[0122] The degree of damage at the measurement point is calculated based on the standard wetting angle and the surface wetting angle.

[0123] Based on the surface wetting angle of the component under test and the degree of damage, the damage depth and its distribution are evaluated using a three-dimensional damage degree model.

[0124] The three-dimensional damage level model is obtained using the method described in the embodiments of this application for constructing a three-dimensional damage level model.

[0125] After establishing a three-dimensional damage level model, when evaluating the damage level of a wafer, it is only necessary to measure the wetting angle of the wafer surface to calculate the damage depth, thus simplifying the testing procedure (i.e., no slicing is required to confirm the damage depth).

[0126] The evaluation method proposed in this application can assess the damage of multiple test pieces in a short time by constructing a three-dimensional damage degree model, without waiting for complete RC test results. This significantly shortens the testing cycle and accelerates the process iteration and optimization.

[0127] The evaluation method of this application measures the surface wetting angle and the cross-sectional wetting angle, and through a three-dimensional damage degree model, it can accurately quantify the three-dimensional damage degree (including damage depth) of low dielectric materials by different processes, which overcomes the limitations of RC testing in reflecting three-dimensional damage.

[0128] The three-dimensional damage level model in the evaluation method of this application provides strong support for the optimization of process parameters. By predicting the damage level under different process parameters through the model, technicians can adjust the parameters more accurately to reduce unnecessary damage and improve product yield and performance.

[0129] The evaluation method presented in this application can quantitatively distinguish the damage contribution of different process steps to low-dielectric materials. This helps technicians accurately identify the main sources of damage and make targeted process adjustments to improve chip performance and process stability.

[0130] The evaluation method described in this application is applicable not only to post-process damage assessment but also to real-time monitoring and control of damage during the process. This helps to promptly identify and correct process deviations, ensuring the consistency and stability of product quality.

[0131] In summary, the evaluation method described in this application can accurately quantify the damage caused by plasma etching to low-dielectric materials and identify the source of damage, thereby providing strong support for optimizing process parameters and improving chip performance.

[0132] like Figure 4 As shown, taking plasma etching as an example, after the wafer is subjected to plasma etching, the damage depth of the low dielectric material layer 11 is t. The assessment and analysis of this damage depth can be carried out by the low dielectric material damage degree evaluation method.

[0133] In one possible embodiment, a method for evaluating the damage level of a low-dielectric material defines at least three concentric circular regions on the XY plane of a standard component, specifically:

[0134] On the XY plane of the standard part, at least one circular region is provided near the center, one circular region near the edge, and one circular region in between. At least three measurement points are set in each circular region, and these measurement points are evenly distributed around the circumference. By setting at least three concentric circular regions on the XY plane of the standard part, and setting multiple measurement points in each region, the comprehensiveness and representativeness of the measurement can be ensured. The evenly distributed circumference of the measurement points simplifies the measurement process and improves measurement efficiency.

[0135] In one possible embodiment, a method for evaluating the degree of damage to low-dielectric materials involves calculating the degree of damage at measurement points, specifically as follows:

[0136] Di = (αi - βi) / αi;

[0137] Where Di represents the damage level at the i-th measurement point on the wafer after the preset process; αi represents the standard wetting angle at the i-th measurement point on the standard part; and βi represents the surface wetting angle at the i-th measurement point on the wafer after the preset process. The formula calculation can intuitively reflect the damage level at each measurement point on the wafer, providing strong data support for damage assessment. The parameters in the formula are easy to obtain and measure, making the calculation process simple and feasible.

[0138] In this embodiment, it is necessary to periodically confirm the standard wetting angle of the standard part because the wetting angle of the low-dielectric material is affected by the size and distribution of pores during the CVD (chemical vapor deposition) preparation process. Therefore, the determination of the standard wetting angle is crucial for process evaluation of damage to the low-dielectric material. When measuring the damage depth, the entire droplet must cover the entire thickness of the low-dielectric material layer 11.

[0139] In low dielectric constant material layers (such as ELK materials), the presence of -CH3 (methyl) functional groups imparts hydrophobicity, resulting in a high wetting angle (i.e., a large contact angle of the liquid on the material surface). However, during plasma etching, -CH3 functional groups may be destroyed, forming -OH (hydroxyl) functional groups. -OH functional groups are hydrophilic, leading to a decrease in the hydrophobicity of the material surface and a reduced wetting angle.

[0140] In plasma etching, bias power is one of the key parameters affecting the damage level of ELK materials. As bias power increases, the ion energy and bombardment intensity in the plasma increase, leading to more severe damage to the -CH3 functional groups on the ELK material surface and the formation of more -OH functional groups. This change in chemical properties can be characterized by wetting angle detection.

[0141] like Figure 10As shown in the embodiments of this application, a low-dielectric material damage assessment system includes a standard component data acquisition module, a test component data acquisition module, a damage degree calculation module, and a low-dielectric material damage degree evaluation module. The standard component data acquisition module defines at least three concentric circular regions on the XY plane of the standard component, sets multiple measurement points within each circular region, and measures and records the standard wetting angle of each measurement point. The test component data acquisition module selects a wafer processed by a preset process as the test component, selects measurement points using the same method as the standard component data acquisition module, and measures the surface wetting angle of each measurement point. The damage degree calculation module calculates the damage degree of each measurement point on the wafer based on the standard wetting angle obtained by the standard component data acquisition module and the surface wetting angle obtained by the test component data acquisition module. The low-dielectric material damage degree evaluation module evaluates the damage depth and its distribution of the test component based on the surface wetting angle and damage degree of the test component using a three-dimensional damage degree model. The three-dimensional damage degree model is obtained using the method for constructing a three-dimensional damage degree model as described in the embodiments of this application.

[0142] The damage degree and distribution of each processing step on the low-dielectric material layer 11 were evaluated using the same method described above. Based on the damage degree and distribution, the impact of each processing step on RC delay was assessed. According to the evaluation results, the key process steps leading to a significant increase in RC delay were identified. Specific optimization measures or improvement schemes were proposed for the identified key processes to reduce RC delay, thereby improving wafer performance and reliability.

[0143] From the perspective of efficiency improvement, the evaluation system of this application, based on a three-dimensional damage degree model, can complete the damage assessment process of multiple test pieces in a short time without waiting for complete RC test results. This fundamentally shortens the traditional testing cycle, provides key support for accelerating the pace of process iteration and promoting the optimization process, and effectively solves the pain point of low efficiency in traditional evaluation methods.

[0144] In terms of evaluation accuracy, the evaluation system of this application, through precise measurement of surface wetting angle and cross-sectional wetting angle, combined with a three-dimensional damage degree model, can achieve quantitative analysis of the three-dimensional damage degree of low-dielectric materials under different processes, and can even accurately capture key indicators such as damage depth. It successfully overcomes the limitations of RC testing in reflecting three-dimensional damage, enabling damage assessment to move from qualitative judgment to quantitative analysis, and providing accurate data for subsequent process optimization.

[0145] From the perspective of process optimization support, the evaluation system of this application can predict the degree of damage under different process parameters through a three-dimensional damage degree model. Based on this, technicians can adjust the parameter settings more accurately, reduce unnecessary material damage, and thus improve product yield and core performance, providing a scientific and efficient technical path for the optimization of process parameters.

[0146] Furthermore, the evaluation system of this application can quantitatively distinguish the contribution of damage in different process steps, which can help technicians quickly locate the main sources of damage and carry out targeted process adjustments to reduce damage factors from the source, which is of great significance for improving chip performance stability and process reliability.

[0147] It is worth noting that the application scenarios of the evaluation system in this application are not limited to post-process damage assessment, but can also be extended to real-time monitoring and control during the process. By tracking damage in real time, technicians can promptly identify and correct process deviations, ensuring the consistency and stability of product quality for each batch, further expanding the practical value of the system.

[0148] In summary, the evaluation system proposed in this application provides comprehensive technical support for process parameter optimization and chip performance improvement by accurately quantifying the damage caused by plasma etching to low-dielectric materials and identifying the source of damage. It has significant technical advantages and application value.

[0149] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for constructing a three-dimensional damage degree model, characterized in that, Includes the following steps: Select a standard part and define at least three concentric circular regions on the XY plane of the standard part. Set multiple measurement points in each circular region, measure and record the standard wetting angle of each measurement point; Multiple samples are selected, which are wafers processed by a preset process. For each wafer, measurement points are set on the surface of the low-dielectric material layer of the wafer according to the method of setting measurement points on the standard part, and the surface wetting angle of each measurement point on the wafer is measured. The damage degree of the measurement point is calculated based on the standard wetting angle and the surface wetting angle of the measurement point. Each measurement point is sliced, and the cross-sectional wetting angle of each slice is measured, and the damage depth of each measurement point is calculated. A three-dimensional damage level model is constructed based on the damage degree, damage depth, and surface wetting angle.

2. The method for constructing a three-dimensional damage degree model according to claim 1, characterized in that, The measurement of the wetting angle of each slice is specifically as follows: The slice to be tested is placed on a rotating platform, and the low dielectric material layer is divided into n equal parts along the thickness direction of the low dielectric material layer, and the parts are marked sequentially from the side of the low dielectric material layer away from the silicon layer as the 1st division line to the nth division line. Measure the wetting angle of the cross section at the 1st bisector and calculate the difference between the standard wetting angle and the cross section wetting angle; if the difference is greater than a preset angle value, rotate the slice by a preset rotation angle; and repeat the above measurement and difference calculation operation until the difference is less than or equal to the preset angle value, or the number of rotations reaches the preset number of rotations; If the number of rotations reaches the preset number of rotations and the difference is still greater than the preset angle value, then the wetting angle of the cross section is measured sequentially at the 2nd to nth bisectors until the difference is less than or equal to the preset angle value, or all bisectors have been measured.

3. The method for constructing a three-dimensional damage level model according to claim 2, characterized in that, The calculation of the damage depth at each measurement point is specifically as follows: ； in: This represents the damage depth at the i-th measurement point on the wafer; q represents the number of equal divisions performed during the measurement process when the difference between the measured standard wetting angle and the cross-sectional wetting angle is less than or equal to the preset angle value; h represents the total thickness of the low-dielectric material layer; d represents the size of the droplet on the slice surface; m represents the number of rotations in a clockwise direction; γ represents the preset rotation angle.

4. The method for constructing a three-dimensional damage level model according to claim 1, characterized in that, At least three concentric circular regions are defined on the XY plane of the standard part, specifically: On the XY plane of the standard part, there is at least one circular area near the center, one circular area near the edge, and one circular area in between; at least three measuring points are set on each circular area, and the measuring points are evenly distributed around the circumference.

5. The method for constructing a three-dimensional damage level model according to claim 1, characterized in that, The calculation of the damage level at each measurement point is specifically as follows: Di = (αi - βi) / αi; Where Di represents the degree of damage at the i-th measurement point on the wafer after the preset process; αi represents the standard wetting angle at the i-th measurement point on the standard part; βi represents the surface wetting angle of the i-th measurement point on the wafer after the preset process.

6. The method for constructing a three-dimensional damage level model according to claim 1, characterized in that, The three-dimensional damage level model is constructed based on the damage degree, damage depth, and surface wetting angle, specifically as follows: Based on the data from each sample, including the degree of damage, damage depth, and surface wetting angle at each measurement point, a three-dimensional damage degree relationship for the wafer is established. A three-dimensional damage degree model is established based on the three-dimensional damage degree relationship of the wafer and the surface wetting angle; The three-dimensional damage level model is a formula relating wafer damage depth to surface wetting angle.

7. A method for evaluating the degree of damage to low-dielectric materials, characterized in that, Includes the following steps: Select a standard part and define at least three concentric circular regions on the XY plane of the standard part. Set multiple measurement points in each circular region, measure and record the standard wetting angle of each measurement point; Select the test piece, which is a wafer processed by a preset process. On the surface of the low dielectric material layer of the wafer, set measurement points according to the method of setting measurement points on the standard part, and measure the surface wetting angle of each measurement point on the wafer. The degree of damage at the measurement point is calculated based on the standard wetting angle and the surface wetting angle at the measurement point. Based on the surface wetting angle of the component under test and the degree of damage, the damage depth and its distribution are evaluated using a three-dimensional damage degree model. The three-dimensional damage level model is obtained by the method of constructing a three-dimensional damage level model as described in any one of claims 1 to 6.

8. The method for evaluating the degree of damage to low-dielectric materials according to claim 7, characterized in that, At least three concentric circular regions are defined on the XY plane of the standard part, specifically: On the XY plane of the standard part, there is at least one circular area near the center, one circular area near the edge, and one circular area in between; at least three measuring points are set on each circular area, and the measuring points are evenly distributed around the circumference.

9. The method for evaluating the degree of damage to low-dielectric materials according to claim 7, characterized in that, The degree of damage at the measurement points is calculated as follows: Di = (αi - βi) / αi; Where Di represents the degree of damage at the i-th measurement point on the wafer after the preset process; αi represents the standard wetting angle at the i-th measurement point on the standard part; βi represents the surface wetting angle of the i-th measurement point on the wafer after the preset process.

10. A damage assessment system for low-dielectric materials, characterized in that, include: The standard part data acquisition module is used to define at least three concentric circular regions on the XY plane of the standard part, set multiple measurement points in each circular region, and measure and record the standard wetting angle of each measurement point; The test piece data acquisition module is used to select the wafer after the preset process as the test piece, select the measurement points using the same method as the standard part data acquisition module, and measure the surface wetting angle of each measurement point; The damage degree calculation module calculates the damage degree of each measurement point on the wafer based on the standard wetting angle obtained by the standard part data acquisition module and the surface wetting angle obtained by the test part data acquisition module. The low dielectric material damage assessment module is used to assess the damage depth and distribution of the test piece based on the surface wetting angle and the damage degree of the test piece using a three-dimensional damage degree model. The three-dimensional damage level model is obtained by the method for constructing a three-dimensional damage level model as described in any one of claims 1 to 6.

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