Overlay error compensation method and system

Abstract

The invention provides an overlay error compensation method and system. The method comprises the following steps: STEP1: obtaining an X-direction coordinate set value, a Y-direction coordinate set value, an X-direction overlay error and a Y-direction overlay error of each exposure field center mark of a target silicon wafer; sTEP2, acquiring an X-direction coordinate set value, a Y-direction coordinate set value, an X-direction overlay error and a Y-direction overlay error of each mark of the target silicon wafer; sTEP 3: calculating a group of intra-field parameters and inter-field parameters according to all the data of the STEP 2; sTEP 4: according to the data of the STEP 1 and the STEP 2, calculating a group of inter-field parameter drift distance; 5, the inter-field parameters of the STEP3 are corrected according to the inter-field parameter drift distance of the STEP4; and STEP6: taking the in-field parameters of the STEP3 and the inter-field parameters of the STEP5 as alignment error compensation parameters of the photoetching machine. According to the invention, the problem that the existing compensation method for overlay errors caused by linear parameters is poor in compensation effect due to the influence of drift of measurement results of a silicon wafer alignment subsystem can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and more particularly, relates to an overlay error compensation method and system. Background Art

[0002] Overlay error refers to the coordinate deviation between two layers of patterns exposed by a lithography machine on the horizontal (XY) plane. Contributions to overlay error can come from linear parameters and higher-order aberrations of the projection objective, among other factors. Linear parameters contribute significantly to overlay error. Linear parameters are divided into intra-exposure field parameters and inter-exposure field parameters. These parameters arise from differences between the two alignment mechanisms: wafer alignment (WA) and reticle alignment (RA). The current method for compensating for overlay error with linear parameters involves measuring the relevant exposure marks using the wafer alignment subsystem, performing model calculations, and then compensating the results with the corresponding machine constants.

[0003] For the wafer alignment subsystem, the more measurement marks it uses, the more accurate the model calculation results and the higher the accuracy of overlay error compensation. However, as the number of measurement marks increases, the measurement time also increases accordingly. However, due to factors such as the measurement stability of the wafer alignment subsystem itself and the surrounding measurement environment, the measurement results of the wafer alignment subsystem can drift significantly over time, further increasing the inaccuracy of the measurement results. Once the measurement error increases, the calculated compensation (especially the inter-field parameters) will also be inaccurate, resulting in substandard overlay performance. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the existing compensation method for overlay error caused by linear parameters is poor in compensation effect due to the influence of the drift of the measurement result of the silicon wafer alignment subsystem.

[0005] According to a first aspect of the present invention, there is provided a method for compensating for overlay errors, the method comprising the following steps: STEP 1: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; STEP 2: Obtain an X-axis coordinate setting value, a Y-axis coordinate setting value, an X-axis overlay error, and a Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; STEP 3: Calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; STEP 4: Calculate a set of inter-field parameter drift values ​​based on all the data from STEP 1 above, as well as the X-coordinate setting value, Y-coordinate setting value, X-overlay error, and Y-overlay error of the center mark of each exposure field in STEP 2; STEP5: Modify the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; STEP6: Use the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

[0006] Optionally, STEP 3 determines the intra-field parameters and inter-field parameters based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0007] Optionally, STEP 4 determines the inter-field parameter drift based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

[0008] Optionally, STEP 5 of correcting the inter-field parameters according to the inter-field parameter drift is implemented based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0009] Optionally, the step of using the intra-field parameters and the corrected inter-field parameters as the lithography machine overlay error compensation parameters in STEP 6 is specifically as follows: The intra-field X-axis magnification and intra-field Y-axis magnification, intra-field X-axis rotation and intra-field Y-axis rotation of STEP 3, the corrected X-axis translation and Y-axis translation of STEP 5, the corrected inter-field X-axis magnification and inter-field Y-axis magnification, and the corrected inter-field X-axis rotation and inter-field Y-axis rotation are saved to the corresponding machine constants of the lithography machine.

[0010] According to a second aspect of the present invention, there is provided an overlay error compensation system, the system comprising the following functional modules: The center mark parameter acquisition module is used to execute STEP 1: obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; All marking parameter acquisition modules are used to execute STEP 2: obtaining the X-axis coordinate setting value, the Y-axis coordinate setting value, the X-axis overlay error and the Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; The intra-field and inter-field parameter acquisition module is used to execute STEP 3: calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; The inter-field parameter drift acquisition module is used to execute STEP 4: calculate a set of inter-field parameter drifts based on all the data in STEP 1 and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field in STEP 2; The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; The overlay error compensation parameter acquisition module is used to execute STEP6: using the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

[0011] Optionally, the intra-field and inter-field parameter acquisition module determines the intra-field parameter and the inter-field parameter based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0012] Optionally, the inter-field parameter drift obtaining module determines the inter-field parameter drift based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

[0013] Optionally, the inter-field parameter correction module corrects the inter-field parameter based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0014] Optionally, the overlay error compensation parameter acquisition module is further configured to: The intra-field X-direction magnification and intra-field Y-direction magnification, the intra-field X-direction rotation and intra-field Y-direction rotation, the corrected X-direction translation and Y-direction translation, the corrected inter-field X-direction magnification and inter-field Y-direction magnification, and the corrected inter-field X-direction rotation and inter-field Y-direction rotation are saved in the corresponding machine constants of the lithography machine.

[0015] The beneficial effects of the present invention are: The overlay error compensation method of the present invention determines intra-field parameters, inter-field parameters, and inter-field parameter drift based on acquired parameters related to the center mark of each exposure field on a target silicon wafer and acquired parameters related to each mark on the target silicon wafer. After drift correction is performed on the inter-field parameters using the inter-field parameter drift, the corrected inter-field parameters are used together with the acquired intra-field parameters as overlay error compensation parameters for a photolithography machine to achieve overlay error compensation. By performing drift correction on the inter-field parameters, the overlay error compensation method of the present invention can effectively address the problem of poor compensation effectiveness in existing compensation methods for overlay errors caused by linear parameters, which are affected by drift in measurement results of a silicon wafer alignment subsystem.

[0016] The overlay error compensation system of the present invention and the above-mentioned overlay error compensation method belong to a general inventive concept, and have at least the same beneficial effects as the above-mentioned overlay error compensation method, and its beneficial effects are not repeated here.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to designate the same or similar parts.

[0019] Figure 1 FIG2 shows a flow chart of an implementation method of an overlay error compensation method according to an embodiment of the present invention; Figure 2 A schematic diagram showing the measurement principle of a single exposure field center mark according to an embodiment of the present invention is shown; Figure 3 A schematic diagram showing the distribution of exposure field center marks on a silicon wafer according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of a measurement path for an exposure field center mark on a silicon wafer according to an embodiment of the present invention is shown; Figure 5 A schematic diagram showing the distribution of detectable marks on a silicon wafer according to an embodiment of the exposure field of the present invention is shown; Figure 6 A principle block diagram of an overlay error compensation system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to more fully understand the technical solution of the present invention, the exemplary embodiments of the present invention will be described in more comprehensive and detailed in conjunction with the accompanying drawings below. Obviously, the one or more embodiments of the present invention described below are only one or more of the specific ways of implementing the technical solution of the present invention, and are not exhaustive. It should be understood that other ways belonging to a general inventive concept can be used to implement the technical solution of the present invention, and should not be limited by the exemplary embodiments described. Based on one or more embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0021] Example: Figure 1 FIG1 shows a flow chart of an implementation of an overlay error compensation method according to an embodiment of the present invention. Figure 1 The overlay error compensation method of the embodiment of the present invention includes the following steps: STEP 1: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; STEP 2: Obtain an X-axis coordinate setting value, a Y-axis coordinate setting value, an X-axis overlay error, and a Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; STEP 3: Calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; STEP 4: Calculate a set of inter-field parameter drift values ​​based on all the data from STEP 1 above, as well as the X-coordinate setting value, Y-coordinate setting value, X-overlay error, and Y-overlay error of the center mark of each exposure field in STEP 2; STEP5: Modify the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; STEP6: Use the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

[0022] Furthermore, in STEP 3 of the embodiment of the present invention, the intra-field parameters and the inter-field parameters are determined based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0023] Furthermore, in STEP 4 of the embodiment of the present invention, the inter-field parameter drift is determined based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

[0024] Furthermore, in STEP 5 of the embodiment of the present invention, the inter-field parameter is corrected according to the inter-field parameter drift based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0025] Furthermore, in STEP 6 of the embodiment of the present invention, the step of using the intra-field parameter and the corrected inter-field parameter as the lithography machine overlay error compensation parameter is specifically as follows: The intra-field X-axis magnification and intra-field Y-axis magnification, intra-field X-axis rotation and intra-field Y-axis rotation of STEP 3, the corrected X-axis translation and Y-axis translation of STEP 5, the corrected inter-field X-axis magnification and inter-field Y-axis magnification, and the corrected inter-field X-axis rotation and inter-field Y-axis rotation are saved to the corresponding machine constants of the lithography machine.

[0026] Specifically, in this embodiment of the present invention, STEP 1 measures parameters related to the center mark of each exposure field on the target silicon wafer. Taking a single silicon wafer as an example, only the center mark of each exposure field is measured. The measurement data includes the X- and Y-coordinate set values ​​of each exposure field center mark, as well as the X- and Y-overlay errors.

[0027] A single exposure field such as Figure 2 As shown in the figure, the X-axis overlay error of the center mark of the exposure field is the measurement value of the X-axis coordinate of the center mark of the exposure field by the WA subsystem minus the X-axis coordinate setting value, and the Y-axis overlay error of the center mark of the exposure field is the measurement value of the Y-axis coordinate of the center mark of the exposure field by the WA subsystem minus the Y-axis coordinate setting value; the center mark of the exposure field is not limited to Figure 2 Cross mark shown.

[0028] The distribution of exposure fields on the silicon wafer is as follows Figure 3 As shown, only the center mark of the exposure field within the silicon wafer can be detected; the measurement path can be set to Figure 4 The S-shaped measurement along the y-direction shown can also be set to S-shaped measurement along the x-direction.

[0029] The relationship between the measured data and the inter-field parameters is established as follows: DX_1=Tx_1+Pos_x*Mwx_1-Pos_y*Rwx_1; DY_1=Ty_1+Pos_y*Mwy_1+Pos_x*Rwy_1; Among them, DX_1 and DY_1 are the X- and Y-direction overlay errors of the center mark; Pos_x and Pos_y are the X- and Y-direction coordinate settings of the center mark in the silicon wafer coordinate system; Tx_1 and Ty_1 are the X- and Y-direction translations between fields; Mwx_1 and Mwy_1 are the X- and Y-direction magnifications between fields; Rwx_1 and Rwy_1 are the X- and Y-direction rotations between fields.

[0030] Specifically, in this embodiment of the present invention, all marks within each exposure field on the target silicon wafer are measured in STEP 2. Taking a single silicon wafer as an example, the measurement data in STEP 2 includes: the X- and Y-coordinate set values ​​of each exposure field mark, as well as the X- and Y-overlay errors.

[0031] The X-direction overlay error of the exposure field mark is the measured value of the X-direction coordinate of the exposure field mark by the WA subsystem minus the X-direction coordinate set value, and the Y-direction overlay error of the exposure field mark is the measured value of the Y-direction coordinate of the exposure field mark by the WA subsystem minus the Y-direction coordinate set value.

[0032] The distribution of exposure fields on the silicon wafer is as follows Figure 5 As shown, only the exposure field marks within the silicon wafer can be detected; the inter-exposure field measurement path and the intra-exposure field measurement path can be set to S-shaped measurement along the y direction or to S-shaped measurement along the x direction.

[0033] according to Figure 5 The measurement data of all markers in each exposure field are used to determine the intra-field parameters and inter-field parameters according to the following steps: Step 1: Eliminate some data according to the 99.7% principle. For example, if there are 1000 measurement data in total, the number of measurement data to be eliminated is 2*1000*(1-0.997)=6. The elimination method is to sort the measurement values ​​from the largest to the smallest by their absolute values, and eliminate the largest 3 and smallest 3 measurement values. Step 2: The calculation formulas for intra-field parameters and inter-field parameters are as follows: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; Among them, DX_2 and DY_2 are the X-direction and Y-direction overlay errors of the measurement mark; pos_x and pos_y are the X-direction and Y-direction coordinate settings of the measurement mark in the exposure field coordinate system; Tx_2 and Ty_2 are the X-direction and Y-direction translations between fields; Mx_1 and My_1 are the X-direction and Y-direction magnifications within a field; Rx_1 and Ry_1 are the X-direction and Y-direction rotations within a field; Pos_x and Pos_y are the X-direction and Y-direction coordinate settings of the exposure field center mark in the wafer coordinate system; Mwx_2 and Mwy_2 are the X-direction and Y-direction magnifications between fields; Rwx_2 and Rwy_2 are the X-direction and Y-direction rotations between fields; The formula for calculating the inter-field parameter drift is as follows: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; Among them, DX_drift = DX_2-DX_1, DY_drift = DY_2-DY_1 are the X-direction and Y-direction overlay error drift of the exposure field center mark; Pos_x and Pos_y are the X-direction and Y-direction coordinate settings of the exposure field center mark in the wafer coordinate system; Tx_3 and Ty_3 are the X-direction and Y-direction translation drift between fields; Mwx_3 and Mwy_3 are the X-direction and Y-direction magnification drift between fields; Rwx_3 and Rwy_3 are the X-direction and Y-direction rotation drift between fields; Therefore, the inter-field parameters after drift correction are: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; Among them, Tx_4 and Ty_4 are the inter-field X-direction and Y-direction translations; Mwx_4 and Mwy_4 are the inter-field X-direction and Y-direction magnifications; Rwx_4 and Rwy_4 are the inter-field X-direction and Y-direction rotations.

[0034] By using the overlay error compensation method of the embodiment of the present invention, a quick measurement is performed before the normal measurement of all marks on the silicon wafer, and only the center mark of each exposure field is measured, which saves time; when correcting the inter-field parameter drift, only the linear drift is considered, without tedious calculations.

[0035] Accordingly, based on the overlay error compensation method of the embodiment of the present invention, the embodiment of the present invention further proposes an overlay error compensation system.

[0036] Figure 6 FIG. 1 shows a principle block diagram of an overlay error compensation system according to an embodiment of the present invention. Figure 6 The overlay error compensation system of the embodiment of the present invention includes the following functional modules: The center mark parameter acquisition module is used to execute STEP 1: obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; All marking parameter acquisition modules are used to execute STEP 2: obtaining the X-axis coordinate setting value, the Y-axis coordinate setting value, the X-axis overlay error and the Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; The intra-field and inter-field parameter acquisition module is used to execute STEP 3: calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; The inter-field parameter drift acquisition module is used to execute STEP 4: calculate a set of inter-field parameter drifts based on all the data in STEP 1 and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field in STEP 2; The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; The overlay error compensation parameter acquisition module is used to execute STEP6: using the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

[0037] Furthermore, in the embodiment of the present invention, the intra-field and inter-field parameter acquisition module determines the intra-field parameters and the inter-field parameters based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0038] Furthermore, in an embodiment of the present invention, the inter-field parameter drift amount acquisition module determines the inter-field parameter drift amount based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

[0039] Furthermore, in an embodiment of the present invention, the inter-field parameter correction module corrects the inter-field parameter based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

[0040] Furthermore, in an embodiment of the present invention, the overlay error compensation parameter acquisition module is further configured to: The intra-field X-direction magnification and intra-field Y-direction magnification, the intra-field X-direction rotation and intra-field Y-direction rotation, the corrected X-direction translation and Y-direction translation, the corrected inter-field X-direction magnification and inter-field Y-direction magnification, and the corrected inter-field X-direction rotation and inter-field Y-direction rotation are saved in the corresponding machine constants of the lithography machine.

[0041] Although one or more embodiments of the present invention have been described above, it should be understood by those skilled in the art that the present invention can be implemented in any other form without departing from its spirit and scope. Therefore, the embodiments described above are illustrative and not restrictive, and many modifications and substitutions will be apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for compensating overlay error, characterized in that: include: STEP 1: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; STEP 2: Obtaining an X-axis coordinate setting value, a Y-axis coordinate setting value, an X-axis overlay error, and a Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; STEP 3: Calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; STEP 4: Calculate a set of inter-field parameter drift values ​​based on all the data from STEP 1 above, as well as the X-coordinate setting value, Y-coordinate setting value, X-overlay error, and Y-overlay error of the center mark of each exposure field in STEP 2; STEP5: Modify the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; STEP6: Use the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

2. The overlay error compensation method according to claim 1, wherein: STEP 3 determines the intra-field parameters and inter-field parameters based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

3. The overlay error compensation method according to claim 1, wherein: STEP4 determines the inter-field parameter drift based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

4. The overlay error compensation method according to claim 1, wherein: STEP 5: The step of correcting the inter-field parameters according to the inter-field parameter drift is based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

5. The overlay error compensation method according to claim 1, wherein: STEP 6: Using the intra-field parameters and the corrected inter-field parameters as the overlay error compensation parameters of the lithography machine is specifically as follows: The intra-field X-axis magnification and intra-field Y-axis magnification, intra-field X-axis rotation and intra-field Y-axis rotation of STEP 3, the corrected X-axis translation and Y-axis translation of STEP 5, the corrected inter-field X-axis magnification and inter-field Y-axis magnification, and the corrected inter-field X-axis rotation and inter-field Y-axis rotation are saved to the corresponding machine constants of the lithography machine.

6. An overlay error compensation system, characterized in that: include: The center mark parameter acquisition module is used to execute STEP 1: obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field of the target silicon wafer; All marking parameter acquisition modules are used to execute STEP 2: obtaining the X-axis coordinate setting value, the Y-axis coordinate setting value, the X-axis overlay error and the Y-axis overlay error of each mark of the target silicon wafer; The X-axis overlay error of each mark is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark; The Y-axis overlay error of each mark is obtained by subtracting the Y-axis coordinate setting value of the mark from the Y-axis coordinate measurement value of the mark; The intra-field and inter-field parameter acquisition module is used to execute STEP 3: calculate a set of intra-field parameters and inter-field parameters based on all the data in STEP 2 above; The inter-field parameter drift acquisition module is used to execute STEP 4: calculate a set of inter-field parameter drifts based on all the data in STEP 1 and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error of the center mark of each exposure field in STEP 2; The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 according to the inter-field parameter drift of STEP4; The overlay error compensation parameter acquisition module is used to execute STEP6: using the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine; The intra-field parameters include intra-field X-direction magnification, intra-field Y-direction magnification, intra-field X-direction rotation, and intra-field Y-direction rotation; the inter-field parameters include X-direction translation, Y-direction translation, inter-field X-direction magnification, inter-field Y-direction magnification, inter-field X-direction rotation, and inter-field Y-direction rotation; translation does not distinguish between intra-field and inter-field.

7. The overlay error compensation system according to claim 6, wherein: The intra-field and inter-field parameter acquisition module determines the intra-field parameter and the inter-field parameter based on the following formula: DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2; DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2; In the above formula, DX_2 is the X-axis overlay error of the target mark, which is obtained by subtracting the X-axis coordinate setting value of the target mark from the X-axis coordinate measurement value of the target mark; DY_2 is the Y-axis overlay error of the target mark, which is obtained by subtracting the Y-axis coordinate setting value of the target mark from the Y-axis coordinate measurement value of the target mark; The target mark's in-field X-coordinate setting value pos_x=POS_x-Pos_x, where POS_x is the target mark's X-coordinate setting value, and Pos_x is the target mark's corresponding X-coordinate setting value of the exposure field center mark. The Y-coordinate setting value of the target mark in the field is pos_y=POS_y-Pos_y, where POS_y is the Y-coordinate setting value of the target mark, and Pos_y is the Y-coordinate setting value of the center mark of the exposure field corresponding to the target mark; Mx_1 and My_1 are the magnification in the X direction and the magnification in the Y direction, respectively; Rx_1 and Ry_1 are the rotation in the X direction and the rotation in the Y direction, respectively; Tx_2 and Ty_2 are the X-direction translation and Y-direction translation respectively, Mwx_2 and Mwy_2 are the inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_2 and Rwy_2 are the inter-field X-direction rotation and inter-field Y-direction rotation respectively.

8. The overlay error compensation system according to claim 6, wherein: The inter-field parameter drift acquisition module determines the inter-field parameter drift based on the following formula: DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3; DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3; In the above formula, DX_drif is the X-direction overlay error drift of the center mark of the exposure field, DX_drift=DX_21-DX_1, DX_1 is the X-direction overlay error of the center mark of the exposure field in STEP1, and DX_21 is the X-direction overlay error of the center mark of the exposure field in STEP2; DY_drift is the Y-direction overlay error drift of the center mark of the exposure field. DY_drift = DY_21 - DY_1, where DY_1 is the Y-direction overlay error of the center mark of the exposure field in STEP1, and DY_21 is the X-direction overlay error of the center mark of the exposure field in STEP2. Tx_3 and Ty_3 are the X-axis translation drift and Y-axis translation drift respectively; Mwx_3 and Mwy_3 are the inter-field X-direction magnification drift and inter-field Y-direction magnification drift respectively; Rwx_3 and Rwy_3 are the inter-field X-axis rotation drift and inter-field Y-axis rotation drift respectively.

9. The overlay error compensation system according to claim 6, wherein: The inter-field parameter correction module corrects the inter-field parameters based on the following formula: Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3; Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3; Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3; In the above formula, Tx_4 and Ty_4 are the corrected X-direction translation and Y-direction translation respectively, Mwx_4 and Mwy_4 are the corrected inter-field X-direction magnification and inter-field Y-direction magnification respectively, Rwx_4 and Rwy_4 are the corrected inter-field X-direction rotation and inter-field Y-direction rotation respectively.

10. The overlay error compensation system according to claim 6, wherein: The overlay error compensation parameter acquisition module is further used for: The intra-field X-direction magnification and intra-field Y-direction magnification, the intra-field X-direction rotation and intra-field Y-direction rotation, the corrected X-direction translation and Y-direction translation, the corrected inter-field X-direction magnification and inter-field Y-direction magnification, and the corrected inter-field X-direction rotation and inter-field Y-direction rotation are saved in the corresponding machine constants of the lithography machine.

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