A method and system for compensating overlay errors

Abstract

This invention provides a method and system for compensating overlay errors. The method includes: STEP 1: acquiring the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each exposure field center mark on the target silicon wafer; STEP 2: acquiring the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each mark on the target silicon wafer; STEP 3: calculating a set of intra-field parameters and inter-field parameters based on all the data from STEP 2; STEP 4: calculating a set of inter-field parameter drift based on the data from STEP 1 and STEP 2; STEP 5: correcting the inter-field parameters of STEP 3 based on the inter-field parameter drift of STEP 4; STEP 6: using the intra-field parameters of STEP 3 and the inter-field parameters of STEP 5 as overlay error compensation parameters for the lithography machine. This invention solves the problem that existing compensation methods for overlay errors caused by linear parameters suffer from poor compensation performance due to the influence of measurement result drift from the silicon wafer alignment subsystem.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and more specifically, relates to a method and system for overlay error compensation. Background Technology

[0002] Overlay error refers to the coordinate deviation of two exposed patterns in the horizontal plane (XY plane) of a lithography machine. Overlay error can be contributed by linear parameters and higher-order aberrations of the projection lens, among which linear parameters contribute relatively more. Linear parameters are divided into intra-exposure parameters and inter-exposure parameters, arising from the differences between two alignment mechanisms: wafer alignment (WA) and reticle alignment (RA). Current methods for compensating for overlay error of linear parameters involve measuring relevant exposure marks using the wafer alignment subsystem, performing model calculations, and finally incorporating the calculation results into the corresponding machine constants.

[0003] For silicon wafer alignment subsystems, the more measurement markers used, the more accurate the model's calculation results and the higher the compensation precision for overlay errors. However, with the increase in measurement markers, the measurement time also increases accordingly. Nevertheless, due to factors such as the subsystem's own measurement stability and the surrounding measurement environment, the measurement results of the silicon wafer alignment subsystem will drift significantly with increasing measurement time, thus increasing the inaccuracy of the measurement results. Once the measurement error increases, the calculated compensation (especially inter-field parameters) will also be inaccurate, resulting in substandard overlay performance. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that existing compensation methods for overlay errors caused by linear parameters have poor compensation effects due to the drift of measurement results from the silicon wafer alignment subsystem.

[0005] According to a first aspect of the present invention, a method for compensating overlay error is provided, the method comprising the following steps:

[0006] STEP 1: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each exposure field center mark of the target silicon wafer;

[0007] STEP2: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each mark on the target silicon wafer;

[0008] The X-axis overlay error of each of the above marks is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark.

[0009] The Y-axis overlay error of each of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark.

[0010] STEP3: Calculate a set of intra-field parameters and inter-field parameters based on all the data from STEP2 above;

[0011] STEP4: Based on all the data from STEP1 above, and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift amounts;

[0012] STEP5: Correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4;

[0013] STEP6: Use the in-field parameters of STEP3 and the inter-field parameters of STEP5 as lithography machine overlay error compensation parameters;

[0014] The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation between fields. Translation does not distinguish between in-field and between-field fields.

[0015] Alternatively, STEP3 determines the in-field and inter-field parameters based on the following formula:

[0016] DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2;

[0017] DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2;

[0018] In the above formula, DX_2 is the X-axis overlay error of the target mark, which is the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value;

[0019] DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark;

[0020] The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark.

[0021] The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the exposure field center mark corresponding to the target mark.

[0022] Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively.

[0023] Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0024] Alternatively, STEP4 determines the inter-field parameter drift based on the following formula:

[0025] DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3;

[0026] DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3;

[0027] 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.

[0028] 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.

[0029] Tx_3 and Ty_3 are the translational drift in the X direction and the translational drift in the Y direction, respectively;

[0030] Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively;

[0031] Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

[0032] Alternatively, STEP5, which involves correcting the inter-field parameters based on the inter-field parameter drift, is implemented using the following formula:

[0033] Tx_4 = Tx_2 - Tx_3;

[0034] Ty_4 = Ty_2 - Ty_3;

[0035] Mwx_4 = Mwx_2 - Mwx_3;

[0036] Mwy_4 = Mwy_2 - Mwy_3;

[0037] Rwx_4 = Rwx_2 - Rwx_3;

[0038] Rwy_4 = Rwy_2 - Rwy_3;

[0039] In the above formula, Tx_4 and Ty_4 are the corrected X-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0040] Optionally, STEP 6 uses the intra-field parameters and the corrected inter-field parameters as lithography machine overlay error compensation parameters as follows:

[0041] Save the in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation of STEP3, the corrected X-axis translation and Y-axis translation of STEP5, 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 to the corresponding machine constants of the lithography machine.

[0042] According to a second aspect of the present invention, an overlay error compensation system is provided, the system comprising the following functional modules:

[0043] The center marker parameter acquisition module is used to perform STEP1: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of the center marker of each exposure field of the target silicon wafer;

[0044] The module for acquiring all marking parameters is used to perform STEP2: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each mark on the target silicon wafer;

[0045] The X-axis overlay error of each of the above marks is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark.

[0046] The Y-axis overlay error of each of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark.

[0047] The on-field and off-field parameter acquisition module is used to execute STEP3: calculate a set of on-field and off-field parameters based on all the data from STEP2 above;

[0048] The inter-field parameter drift acquisition module is used to perform STEP4: based on all the data in STEP1 above, as well as the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift values;

[0049] The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4;

[0050] The overlay error compensation parameter acquisition module is used to execute STEP6: take the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine.

[0051] The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation between fields. Translation does not distinguish between in-field and between-field fields.

[0052] Optionally, the in-field and out-of-field parameter acquisition module determines the in-field parameters and the out-of-field parameters based on the following formula:

[0053] DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2;

[0054] DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2;

[0055] In the above formula, DX_2 is the X-axis overlay error of the target mark, which is the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value;

[0056] DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark;

[0057] The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark.

[0058] The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the exposure field center mark corresponding to the target mark.

[0059] Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively.

[0060] Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0061] Optionally, the inter-field parameter drift acquisition module determines the inter-field parameter drift based on the following formula:

[0062] DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3;

[0063] DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3;

[0064] 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.

[0065] 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.

[0066] Tx_3 and Ty_3 are the translational drift in the X direction and the translational drift in the Y direction, respectively;

[0067] Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively;

[0068] Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

[0069] Optionally, the inter-field parameter correction module corrects the inter-field parameters based on the following formula:

[0070] Tx_4 = Tx_2 - Tx_3;

[0071] Ty_4 = Ty_2 - Ty_3;

[0072] Mwx_4 = Mwx_2 - Mwx_3;

[0073] Mwy_4 = Mwy_2 - Mwy_3;

[0074] Rwx_4 = Rwx_2 - Rwx_3;

[0075] Rwy_4 = Rwy_2 - Rwy_3;

[0076] In the above formula, Tx_4 and Ty_4 are the corrected X-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0077] Optionally, the overlay error compensation parameter acquisition module is further used for:

[0078] The in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation, the corrected X-axis translation and Y-axis translation, 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.

[0079] The beneficial effects of this invention are as follows:

[0080] The overlay error compensation method of this invention determines intra-field parameters, inter-field parameters, and the amount of inter-field parameter drift based on the relevant parameters of each exposure field center mark on the target silicon wafer and the relevant parameters of each mark on the target silicon wafer. After correcting the inter-field parameters using the amount of inter-field parameter drift, the corrected inter-field parameters, together with the acquired intra-field parameters, are used as overlay error compensation parameters for the lithography machine to achieve overlay error compensation. This invention's overlay error compensation method effectively solves the problem of poor compensation performance in existing methods for compensating overlay errors caused by linear parameters due to the influence of drift in the measurement results of the silicon wafer alignment subsystem, because it corrects the drift of the inter-field parameters.

[0081] The overprinting error compensation system of the present invention and the overprinting error compensation method described above belong to the same general inventive concept and have at least the same beneficial effects as the overprinting error compensation method described above, the beneficial effects of which will not be repeated here.

[0082] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0083] The present invention can 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 denote the same or similar parts.

[0084] Figure 1A flowchart illustrating the implementation of an overlay error compensation method according to an embodiment of the present invention is shown.

[0085] Figure 2 A schematic diagram illustrating the measurement principle of a single exposure field center marker according to an embodiment of the present invention is shown;

[0086] Figure 3 A schematic diagram showing the distribution of exposure field center markers on a silicon wafer according to an embodiment of the present invention is shown;

[0087] Figure 4 A schematic diagram of the measurement path for the center mark of the exposure field on a silicon wafer according to an embodiment of the present invention is shown;

[0088] Figure 5 A schematic diagram showing the distribution of markers on a silicon wafer that can be detected by exposure field energy according to an embodiment of the present invention is illustrated.

[0089] Figure 6 A schematic diagram of an overlay error compensation system according to an embodiment of the present invention is shown. Detailed Implementation

[0090] To enable those skilled in the art to more fully understand the technical solutions of the present invention, exemplary embodiments of the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings. Obviously, the one or more embodiments of the present invention described below are merely one or more specific ways to implement the technical solutions 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 solutions of the present invention, and should not be limited to the embodiments described exemplary. Based on one or more embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0091] Example: Figure 1 A flowchart illustrating the implementation of the overlay error compensation method according to an embodiment of the present invention is shown. (Refer to...) Figure 1 The overlay error compensation method of this invention includes the following steps:

[0092] STEP 1: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each exposure field center mark of the target silicon wafer;

[0093] STEP2: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each mark on the target silicon wafer;

[0094] The X-axis overlay error of each of the above marks is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark.

[0095] The Y-axis overlay error of each of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark.

[0096] STEP3: Calculate a set of intra-field parameters and inter-field parameters based on all the data from STEP2 above;

[0097] STEP4: Based on all the data from STEP1 above, and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift amounts;

[0098] STEP5: Correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4;

[0099] STEP6: Use the in-field parameters of STEP3 and the inter-field parameters of STEP5 as lithography machine overlay error compensation parameters;

[0100] The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation between fields. Translation does not distinguish between in-field and between-field fields.

[0101] Furthermore, in STEP3 of this embodiment, the intra-field parameters and inter-field parameters are determined based on the following formula:

[0102] DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2;

[0103] DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2;

[0104] In the above formula, DX_2 is the X-axis overlay error of the target mark, which is the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value;

[0105] DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark;

[0106] The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark.

[0107] The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the exposure field center mark corresponding to the target mark.

[0108] Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively.

[0109] Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0110] Furthermore, in STEP4 of this embodiment, the inter-field parameter drift is determined based on the following formula:

[0111] DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3;

[0112] DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3;

[0113] 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.

[0114] 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.

[0115] Tx_3 and Ty_3 are the translational drift in the X direction and the translational drift in the Y direction, respectively;

[0116] Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively;

[0117] Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

[0118] Furthermore, in STEP5 of this embodiment, the correction of the inter-field parameters based on the inter-field parameter drift is achieved using the following formula:

[0119] Tx_4 = Tx_2 - Tx_3;

[0120] Ty_4 = Ty_2 - Ty_3;

[0121] Mwx_4 = Mwx_2 - Mwx_3;

[0122] Mwy_4 = Mwy_2 - Mwy_3;

[0123] Rwx_4 = Rwx_2 - Rwx_3;

[0124] Rwy_4 = Rwy_2 - Rwy_3;

[0125] In the above formula, Tx_4 and Ty_4 are the corrected X-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0126] Furthermore, in STEP 6 of this embodiment, the step of using the intra-field parameters and the corrected inter-field parameters as lithography machine overlay error compensation parameters specifically includes:

[0127] Save the in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation of STEP3, the corrected X-axis translation and Y-axis translation of STEP5, 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 to the corresponding machine constants of the lithography machine.

[0128] Specifically, in this embodiment of the invention, STEP1 measures the relevant parameters of each exposure field center mark on the target silicon wafer. Taking a single silicon wafer as an example, only each exposure field center mark is measured, and the measurement data includes: the X-axis coordinate setting value, the Y-axis coordinate setting value, the X-axis overlay error, and the Y-axis overlay error for each exposure field center mark.

[0129] Single exposure field such as Figure 2 As shown, the X-axis overlay error of the exposure field center mark is the measured value of the X-axis coordinate of the exposure field center mark by the WA subsystem minus the X-axis coordinate setting value; the Y-axis overlay error of the exposure field center mark is the measured value of the Y-axis coordinate of the exposure field center mark by the WA subsystem minus the Y-axis coordinate setting value; the exposure field center mark is not limited to... Figure 2 The cross mark shown.

[0130] 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 shown along the y-direction can also be set to an s-shaped measurement along the x-direction.

[0131] The relationship between measurement data and field parameters is established as follows:

[0132] DX_1=Tx_1+Pos_x*Mwx_1-Pos_y*Rwx_1;

[0133] DY_1=Ty_1+Pos_y*Mwy_1+Pos_x*Rwy_1;

[0134] Wherein, DX_1 and DY_1 are the X and Y axis overlay errors of the center mark; Pos_x and Pos_y are the X and Y axis coordinate settings of the center mark in the silicon wafer coordinate system; Tx_1 and Ty_1 are the X and Y axis translations between fields; Mwx_1 and Mwy_1 are the X and Y axis magnifications between fields; and Rwx_1 and Rwy_1 are the X and Y axis rotations between fields.

[0135] Specifically, in this embodiment of the invention, STEP2 measures all marks within each exposure field on the target silicon wafer. Taking a single silicon wafer as an example, the measurement data of STEP2 includes: the X-axis coordinate setting value and Y-axis coordinate setting value for each exposure field mark, as well as the X-axis overlay error and the Y-axis overlay error.

[0136] The X-axis overlay error of the exposure field mark is the measured value of the X-axis coordinate of the exposure field mark by the WA subsystem minus the X-axis coordinate setting value. The Y-axis overlay error of the exposure field mark is the measured value of the Y-axis coordinate of the exposure field mark by the WA subsystem minus the Y-axis coordinate setting value.

[0137] 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 s-shaped measurement along the x-direction.

[0138] according to Figure 5 Measurement data for all markers within each exposure field are used to determine the in-field and inter-field parameters according to the following steps:

[0139] 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 largest to smallest by taking the absolute value, and eliminate the 3 largest measurement values ​​and the 3 smallest measurement values.

[0140] Step 2: The formulas for calculating the in-field parameters and inter-field parameters are as follows:

[0141] 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;

[0142] Wherein, DX_2 and DY_2 are the X and Y axis overlay errors of the measurement marks; pos_x and pos_y are the X and Y axis coordinate settings of the measurement marks in the exposure field coordinate system; Tx_2 and Ty_2 are the X and Y axis translations between fields; Mx_1 and My_1 are the X and Y axis magnifications within the field; Rx_1 and Ry_1 are the X and Y axis rotations within the field; Pos_x and Pos_y are the X and Y axis coordinate settings of the exposure field center mark in the wafer coordinate system; Mwx_2 and Mwy_2 are the X and Y axis magnifications between fields; Rwx_2 and Rwy_2 are the X and Y axis rotations between fields.

[0143] The formula for calculating the inter-field parameter drift is as follows:

[0144] DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3;

[0145] DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3;

[0146] Wherein, DX_drift=DX_2-DX_1 and DY_drift=DY_2-DY_1 are the overlay error drift amounts in the X and Y directions of the exposure field center mark; Pos_x and Pos_y are the X and Y coordinate settings of the exposure field center mark in the wafer coordinate system; Tx_3 and Ty_3 are the translational drift amounts in the X and Y directions between fields; Mwx_3 and Mwy_3 are the magnification drift amounts in the X and Y directions between fields; and Rwx_3 and Rwy_3 are the rotational drift amounts in the X and Y directions between fields.

[0147] Therefore, the field parameters after drift correction are:

[0148] Tx_4=Tx_2-Tx_3; Ty_4=Ty_2-Ty_3;

[0149] Mwx_4=Mwx_2-Mwx_3; Mwy_4=Mwy_2-Mwy_3;

[0150] Rwx_4=Rwx_2-Rwx_3; Rwy_4=Rwy_2-Rwy_3;

[0151] Where Tx_4 and Ty_4 are the X and Y translations between fields; Mwx_4 and Mwy_4 are the X and Y magnifications between fields; and Rwx_4 and Rwy_4 are the X and Y rotations between fields.

[0152] The overlay error compensation method of this invention performs a rapid measurement before measuring all marks on the silicon wafer, measuring only the center mark of each exposure field, which is time-saving; when correcting the drift of inter-field parameters, only linear drift is considered, without cumbersome calculations.

[0153] Accordingly, based on the overprinting error compensation method of the present invention, the present invention also proposes an overprinting error compensation system.

[0154] Figure 6 A schematic block diagram of the overlay error compensation system according to an embodiment of the present invention is shown. (Refer to...) Figure 6 The overlay error compensation system of this invention includes the following functional modules:

[0155] The center marker parameter acquisition module is used to perform STEP1: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of the center marker of each exposure field of the target silicon wafer;

[0156] The module for acquiring all marking parameters is used to perform STEP2: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each mark on the target silicon wafer;

[0157] The X-axis overlay error of each of the above marks is obtained by subtracting the X-axis coordinate setting value of the mark from the X-axis coordinate measurement value of the mark.

[0158] The Y-axis overlay error of each of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark.

[0159] The on-field and off-field parameter acquisition module is used to execute STEP3: calculate a set of on-field and off-field parameters based on all the data from STEP2 above;

[0160] The inter-field parameter drift acquisition module is used to perform STEP4: based on all the data in STEP1 above, as well as the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift values;

[0161] The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4;

[0162] The overlay error compensation parameter acquisition module is used to execute STEP6: take the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine.

[0163] The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation between fields. Translation does not distinguish between in-field and between-field fields.

[0164] Furthermore, in this embodiment of the invention, the field-inside-field parameter acquisition module determines the field-inside parameters and field-outside parameters based on the following formula:

[0165] DX_2=Tx_2+pos_x*Mx_1-pos_y*Rx_1+Pos_x*Mwx_2-Pos_y*Rwx_2;

[0166] DY_2=Ty_2+pos_y*My_1+pos_x*Ry_1+Pos_y*Mwy_2+Pos_x*Rwy_2;

[0167] In the above formula, DX_2 is the X-axis overlay error of the target mark, which is the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value;

[0168] DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark;

[0169] The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark.

[0170] The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the exposure field center mark corresponding to the target mark.

[0171] Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively.

[0172] Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0173] Furthermore, in this embodiment of the invention, the inter-field parameter drift acquisition module determines the inter-field parameter drift based on the following formula:

[0174] DX_drift=Tx_3+Pos_x*Mwx_3-Pos_y*Rwx_3;

[0175] DY_drift=Ty_3+Pos_y*Mwy_3+Pos_x*Rwy_3;

[0176] 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.

[0177] 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.

[0178] Tx_3 and Ty_3 are the translational drift in the X direction and the translational drift in the Y direction, respectively;

[0179] Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively;

[0180] Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

[0181] Furthermore, in this embodiment of the invention, the inter-field parameter correction module corrects the inter-field parameters based on the following formula:

[0182] Tx_4 = Tx_2 - Tx_3;

[0183] Ty_4 = Ty_2 - Ty_3;

[0184] Mwx_4 = Mwx_2 - Mwx_3;

[0185] Mwy_4 = Mwy_2 - Mwy_3;

[0186] Rwx_4 = Rwx_2 - Rwx_3;

[0187] Rwy_4 = Rwy_2 - Rwy_3;

[0188] In the above formula, Tx_4 and Ty_4 are the corrected X-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

[0189] Furthermore, in this embodiment of the invention, the overlay error compensation parameter acquisition module is further used for:

[0190] The in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation, the corrected X-axis translation and Y-axis translation, 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.

[0191] While one or more embodiments of the present invention have been described above, those skilled in the art will recognize 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 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 for each exposure field center mark of the target silicon wafer; STEP2: Obtain the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error, and Y-axis overlay error for each mark on the target silicon wafer; The X-axis overlay error of each of the above marks 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 of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark. STEP3: Calculate a set of intra-field parameters and inter-field parameters based on all the data from STEP2 above; STEP4: Based on all the data from STEP1 above, and the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift amounts; STEP5: Correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4; STEP6: Use the in-field parameters of STEP3 and the inter-field parameters of STEP5 as lithography machine overlay error compensation parameters; The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation. Translation does not distinguish between in-field and out-of-field. STEP3 determines the in-field and inter-field parameters based on the following formulas: 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 the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value; DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark; The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark. The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark. Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively. Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

2. The overlay error compensation method according to claim 1, characterized in that, 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 translational drift in the X direction and the translational drift in the Y direction, respectively; Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively; Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

3. The overlay error compensation method according to claim 1, characterized in that, STEP5, the step of correcting the inter-field parameters based on 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-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

4. The overlay error compensation method according to claim 1, characterized in that, STEP6, the step of using the intra-field parameters and the corrected inter-field parameters as lithography machine overlay error compensation parameters, specifically involves: Save the in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation of STEP3, the corrected X-axis translation and Y-axis translation of STEP5, 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 to the corresponding machine constants of the lithography machine.

5. A system for compensating overlay errors, characterized in that, include: The center marker parameter acquisition module is used to perform STEP1: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of the center marker of each exposure field of the target silicon wafer; The module for acquiring all marking parameters is used to perform STEP2: acquire the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each mark on the target silicon wafer; The X-axis overlay error of each of the above marks 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 of the above marks is obtained by subtracting the set value of the Y-axis coordinate of the mark from the measured value of the Y-axis coordinate of the mark. The on-field and off-field parameter acquisition module is used to execute STEP3: calculate a set of on-field and off-field parameters based on all the data from STEP2 above; The inter-field parameter drift acquisition module is used to perform STEP4: based on all the data in STEP1 above, as well as the X-axis coordinate setting value, Y-axis coordinate setting value, X-axis overlay error and Y-axis overlay error of each exposure field center mark in STEP2, calculate a set of inter-field parameter drift values; The inter-field parameter correction module is used to execute STEP5: correct the inter-field parameters of STEP3 based on the inter-field parameter drift of STEP4; The overlay error compensation parameter acquisition module is used to execute STEP6: take the intra-field parameters of STEP3 and the inter-field parameters of STEP5 as the overlay error compensation parameters of the lithography machine. The parameters within the field include the in-field X-axis magnification, the in-field Y-axis magnification, and the in-field X-axis rotation and the in-field Y-axis rotation. The parameters between fields include X-axis translation, Y-axis translation, X-axis magnification, Y-axis magnification, X-axis rotation, and Y-axis rotation. Translation does not distinguish between in-field and out-of-field. The in-field and out-of-field parameter acquisition module determines the in-field parameters and the out-of-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 the target mark X-axis coordinate measurement value minus the target mark X-axis coordinate setting value; DY_2 is the Y-axis overlay error of the target mark, which is the difference between the measured Y-axis coordinate value of the target mark and the set Y-axis coordinate value of the target mark; The in-field X-axis coordinate setting value of the target mark is pos_x = POS_x - Pos_x, where POS_x is the X-axis coordinate setting value of the target mark and Pos_x is the X-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark. The in-field Y-axis coordinate setting value of the target mark is pos_y = POS_y - Pos_y, where POS_y is the Y-axis coordinate setting value of the target mark and Pos_y is the Y-axis coordinate setting value of the center mark of the exposure field corresponding to the target mark. Mx_1 and My_1 are the in-field X-axis magnification and in-field Y-axis magnification, respectively; Rx_1 and Ry_1 are the in-field X-axis rotation and in-field Y-axis rotation, respectively. Tx_2 and Ty_2 represent X-axis translation and Y-axis translation, respectively; Mwx_2 and Mwy_2 represent inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_2 and Rwy_2 represent inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

6. The overlay error compensation system according to claim 5, characterized in that, 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 translational drift in the X direction and the translational drift in the Y direction, respectively; Mwx_3 and Mwy_3 are the inter-field X-axis magnification drift and inter-field Y-axis magnification drift, respectively; Rwx_3 and Rwy_3 represent the inter-field X-axis rotational drift and inter-field Y-axis rotational drift, respectively.

7. The overlay error compensation system according to claim 5, characterized in that, 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-axis translation and Y-axis translation, respectively; Mwx_4 and Mwy_4 are the corrected inter-field X-axis magnification and inter-field Y-axis magnification, respectively; and Rwx_4 and Rwy_4 are the corrected inter-field X-axis rotation and inter-field Y-axis rotation, respectively.

8. The overlay error compensation system according to claim 6, characterized in that, The overlay error compensation parameter acquisition module is further used for: The in-field X-axis magnification and in-field Y-axis magnification, in-field X-axis rotation and in-field Y-axis rotation, the corrected X-axis translation and Y-axis translation, 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.

Images