Parameter control method and exposure method

Abstract

The present invention provides a parameter control method and an exposure method, the parameter control method comprising: obtaining substrate surface shape data and mask surface shape data before scanning exposure; obtaining a workpiece stage adjustment amount and an objective lens adjustment amount based on the substrate surface shape data and the mask surface shape data, and forming a workpiece stage motion trajectory and an objective lens motion trajectory; smoothing the objective lens motion trajectory to obtain a smoothed objective lens adjustment amount, so that the objective lens motion time is not greater than the workpiece stage motion time or the exposure gear switching time; forming a first coefficient based on the workpiece stage adjustment amount, and forming a second coefficient based on the smoothed objective lens adjustment amount. In this configuration, by optimizing the objective lens motion trajectory, the objective lens motion time is matched with the workpiece stage motion time or the exposure gear switching time, and the exposure time is no longer limited by the objective lens motion time, which effectively improves the yield of the exposure equipment, and also avoids the overexposure or underexposure phenomenon of the exposure field caused by the exposure gear adjustment, thereby improving the yield of the product.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a parameter control method and an exposure method. Background Art

[0002] The essence of the photolithography process is to copy temporary circuit structures onto silicon wafers to be etched and ion implanted. These structures are first made on a mask in the form of a pattern, and then a light beam is used to transfer the pattern to a photosensitive film on the surface of the silicon wafer through the mask. The photolithography process is usually carried out as follows: after photolithography and development, the pattern appears on the silicon wafer, and then the thin film pattern is imaged on the silicon wafer by a chemical etching process, or ion implantation is used to complete the optional doping of the pattern on the silicon wafer. The photolithography process usually includes the following eight basic steps: vapor phase bottom mold formation, spin coating, soft baking, alignment and exposure, post-exposure baking, development, hard film baking, and development inspection.

[0003] In the alignment and exposure process, the pattern on the mask is projected onto the silicon wafer coated with photoresist through the light source and optical system; the optical system usually includes a mirror group, and during the exposure process, the movement of the mirror group can be controlled by a fitted polynomial trajectory to achieve exposure compensation for the material. However, the movement speed of the mirror group is usually lower than the movement speed of the workbench. When the surface shape of the material in the exposure field is poor, the fitted polynomial trajectory will cause the movement time of the mirror group to be too long, and the speed performance of the workbench cannot be fully utilized, resulting in reduced yield; and the movement time of the mirror group may be inconsistent in different exposure fields. For exposure equipment that does not support exposure field gear switching, it will cause overexposure or underexposure of the exposure field. Summary of the invention

[0004] The object of the present invention is to provide a parameter control method and an exposure method to solve the problem that the moving speed of the objective lens does not match the moving speed of the workpiece stage, resulting in reduced yield and prone to overexposure or underexposure of the exposure field.

[0005] In order to achieve the above object, the present invention provides a parameter control method, comprising: before scanning exposure, obtaining substrate surface shape data and mask surface shape data;

[0006] Based on the substrate surface shape data and the mask surface shape data, the workpiece stage adjustment amount and the objective lens adjustment amount are obtained, and the workpiece stage motion trajectory and the objective lens motion trajectory are formed;

[0007] Smoothing the objective lens motion trajectory to obtain a smoothed objective lens adjustment amount and forming a smoothed objective lens motion trajectory, so that the objective lens motion time is not greater than the workpiece stage motion time or the exposure gear switching time;

[0008] A first coefficient is formed based on the workpiece stage adjustment amount, and a second coefficient is formed based on the smoothed objective lens adjustment amount.

[0009] Optionally, smoothing the objective lens motion trajectory includes:

[0010] Based on the substrate surface shape data at any moment and the corresponding objective lens adjustment amount, a gradient value is obtained and compared with a gradient threshold value to determine whether to perform smoothing processing on the objective lens adjustment amount at that moment.

[0011] Optionally, the gradient value includes a first gradient value;

[0012] The first gradient value includes a ratio of the objective lens adjustment amount at two adjacent moments to the position data of the workpiece stage respectively corresponding thereto.

[0013] Optionally, the gradient threshold includes a first gradient threshold;

[0014] The first gradient threshold comprises a ratio of a maximum scanning speed of the objective lens to a maximum scanning speed of the workpiece stage.

[0015] Optionally, the gradient threshold includes a second gradient threshold;

[0016] The second gradient threshold is calculated by the minimum exposure time, the scanning length of the exposure field and the maximum scanning speed of the objective lens. The calculation formula of the second gradient threshold is:

[0017]

[0018] Where TH2 is the second gradient threshold; V max_PO is the maximum scanning speed of the objective lens; Y scan is the scanning length of the exposure field; T min_DC is the minimum exposure time.

[0019] Optionally, the gradient value also includes a second gradient value;

[0020] The second gradient value includes a ratio of the first gradient value at two adjacent moments to the position data of the workpiece stage respectively corresponding thereto.

[0021] Optionally, the gradient threshold includes a third gradient threshold;

[0022] The third gradient threshold is calculated by the maximum scanning speed of the objective lens, the maximum scanning speed of the workpiece stage, the maximum scanning acceleration of the objective lens, and the maximum scanning acceleration of the workpiece stage. The calculation formula of the third gradient threshold is:

[0023]

[0024] Where TH3 is the third gradient threshold; a max_PO V is the maximum scanning acceleration of the objective lens; max_WSis the maximum scanning speed of the workpiece stage; a max_WS V is the maximum scanning acceleration of the workpiece stage; max_PO is the maximum scanning speed of the objective lens.

[0025] Optionally, if the gradient value is greater than the gradient threshold, the objective lens adjustment amount at that moment is smoothed to obtain a smoothed objective lens adjustment amount, and then a smoothed gradient value is calculated based on the smoothed objective lens adjustment amount until the smoothed gradient value is less than or equal to the gradient threshold to obtain the smoothed objective lens adjustment amount;

[0026] If the gradient value is less than or equal to the gradient threshold, the objective lens adjustment amount at this moment is not processed.

[0027] Optionally, the smoothed objective lens adjustment amount includes an average of the objective lens adjustment amount at this moment and the objective lens adjustment amount at a previous moment.

[0028] Optionally, the smoothed objective lens adjustment amount is calculated by the objective lens adjustment amount at this moment and the objective lens adjustment amounts at multiple adjacent moments; the calculation formula for the smoothed objective lens adjustment amount is:

[0029] z new(i) =A2·z(i+2)+A1·z(i+1)+A0·z(i)+B1·z(i-1)+B2·z(i-2)

[0030] In the formula, z new(i) is the smoothed objective lens adjustment amount; z(i) is the objective lens adjustment amount at any moment; Ai and Bi are weight factors.

[0031] Optionally, an orthogonal polynomial fitting is performed based on the workpiece stage adjustment amount to form a first coefficient, and an orthogonal polynomial fitting is performed based on the smoothed objective lens adjustment amount to form a second coefficient.

[0032] Optionally, the substrate surface data and the mask surface data are slid by using the static field of view of the objective lens as a sliding window, and the surface data within a single sliding window sliding from the exposure start point of the exposure field to the exposure end point is plane fitted to obtain the workpiece stage adjustment amount and the objective lens adjustment amount.

[0033] Optionally, before obtaining the workpiece stage adjustment amount and the objective lens adjustment amount, the substrate surface shape data and the mask surface shape data are preprocessed.

[0034] In order to achieve the above object, the present invention also provides an exposure method, comprising using the parameter control method as described above;

[0035] and during scanning exposure, calculating the real-time workpiece stage adjustment amount based on the first coefficient, and calculating the real-time objective lens adjustment amount based on the second coefficient;

[0036] The position of the workpiece stage is adjusted based on the real-time workpiece stage adjustment amount, and the position of the objective lens is adjusted based on the real-time objective lens adjustment amount.

[0037] Compared with the existing exposure method, the parameter control method and exposure method provided by the present application have the following advantages:

[0038] By smoothing the objective lens adjustment amount before scanning exposure, it is ensured that the objective lens movement time is not greater than the workpiece stage movement time or the exposure gear switching time, so that the exposure time is no longer limited by the objective lens movement time, and the productivity of the exposure equipment is effectively improved; at the same time, because the scanning exposure time corresponding to the maximum movement time of the moving stage is not changed by the adjustment of the exposure gear, it also avoids overexposure or underexposure of the exposure field caused by the exposure gear adjustment, thereby improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a process of an exposure method provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of an exposure device provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of a sliding window traversing an exposure field provided by an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the fitting of the material surface shape provided by an embodiment of the present invention;

[0043] 1- workpiece stage; 2- substrate; 3- mask stage; 4- mask;

[0044] 5-optical unit; 51-light source; 52-mirror group; 521-objective mirror unit;

[0045] 6- measurement unit; 61- substrate measurement subunit; 62- mask measurement subunit;

[0046] 7-vertical monitoring unit; 71-mask stage vertical monitoring subunit; 72-workpiece stage vertical monitoring subunit;

[0047] 8- Sliding window;

[0048] A-Axial. DETAILED DESCRIPTION

[0049] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0050] As used in this specification, the singular forms "a", "an" and "the" include plural objects, the term "or" is generally used to include the meaning of "and / or", the term "several" is generally used to include the meaning of "at least one", and the term "at least two" is generally used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "the proximal end" and "the distal end" generally refer to two corresponding parts, which include not only the endpoints, and the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. In addition, as used in this specification, an element disposed on another element generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements may be direct or indirect through an intermediate element, and it cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element may be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. The terms "upper", "lower", "top" and "bottom" are generally relative position relationships arranged in the direction of gravity; the terms "vertical, vertical direction" generally refer to the direction of gravity, which is generally perpendicular to the ground, and "horizontal, horizontal plane direction" generally refers to the direction parallel to the ground; for ordinary technicians in this field, the specific meanings of the above terms in this specification can be understood according to specific circumstances.

[0051] The object of the present invention is to provide a parameter control method and an exposure method to solve the problem that the moving speed of the objective lens does not match the moving speed of the workpiece stage, resulting in reduced yield and prone to overexposure or underexposure of the exposure field.

[0052] Those skilled in the art can understand that the principle of the photolithography process is similar to the photographic function of a camera. A camera uses light and a lens to present the image of the object being photographed on a film, and then transfers the image on the film to photographic paper through development to form a photo; in the photolithography process, the pattern on the mask is the target to be photographed, and the pattern on the mask needs to be projected onto a silicon wafer coated with photoresist through an optical system and a light source, and then the pattern on the mask is formed into a permanent pattern on the surface of the silicon wafer through subsequent processes (such as etching or ion implantation). In the actual production process, the factors affecting the photolithography process generally include: the surface shape of the mask and / or substrate, the moving speed of the drive device, the resolution of the optical system (usually a lens group formed by a combination of multiple objective lenses), the type of light, and the focusing accuracy of the system, etc. This application focuses on the influence of the moving speed of the drive device on the accuracy of the photolithography process, and assumes that other influencing factors meet the accuracy requirements of the photolithography process. In the photolithography process, it is necessary to move the work stage to complete the photolithography of the patterns on different masks, and it is also necessary to move the lens group according to the surface shape of the mask and / or substrate to achieve different exposure compensations. At this time, the moving speed of the driving device becomes a key factor affecting the production rate and yield of the exposure equipment. In the prior art, the movement of the objective lens and / or the work stage is usually controlled by fitting the polynomial trajectory formed, and the objective lens driving device is limited by the strength and structure of the objective lens itself, and its maximum movement speed is lower than the maximum movement speed of the work stage driving device. Therefore, under the same circumstances, the movement time of the objective lens is greater than the movement time of the work stage, which makes the scanning exposure time of the exposure equipment depend on the movement time of the objective lens, which greatly reduces the production rate of the exposure equipment; at the same time, in the process of adjusting the exposure gear (i.e. adjusting the light intensity of the light source), due to the slow movement speed of the objective lens, when the light intensity of the light source changes, the objective lens is likely not in place, which causes overexposure or underexposure of the exposure field, thereby directly affecting the yield of the product. Based on this, the present application provides a motion component and an exposure device, which optimizes the motion trajectory of the objective lens so that the motion time of the objective lens matches the motion time of the workpiece stage. In this way, the scanning exposure time of the exposure device is no longer limited by the motion time of the objective lens, thereby improving the productivity of the exposure device; and because the scanning exposure time corresponding to the maximum motion speed of the workpiece stage does not change due to the adjustment of the exposure gear, it also avoids overexposure or underexposure of the exposure field caused by the adjustment of the exposure gear, thereby improving the yield of the product.

[0053] The following description is given with reference to the accompanying drawings.

[0054] Please refer to Figure 1The present application provides an exposure method, comprising: before scanning exposure, using a parameter control method to smooth the objective lens adjustment amount so that the objective lens movement time is not greater than the workpiece stage movement time or the exposure gear switching time; and during scanning exposure, calculating the real-time workpiece stage adjustment amount based on a first coefficient, and calculating the real-time objective lens adjustment amount based on a second coefficient; adjusting the position of the workpiece stage 1 based on the real-time workpiece stage adjustment amount, and adjusting the position of the objective lens based on the real-time objective lens adjustment amount.

[0055] Furthermore, the parameter control method includes: before scanning exposure, obtaining substrate surface shape data and mask surface shape data; based on the substrate surface shape data and the mask surface shape data, obtaining the workpiece stage adjustment amount and the objective lens adjustment amount, and forming the workpiece stage motion trajectory and the objective lens motion trajectory; smoothing the objective lens motion trajectory to obtain the smoothed objective lens adjustment amount, and forming the smoothed objective lens motion trajectory, so that; forming a first coefficient based on the workpiece stage adjustment amount, and forming a second coefficient based on the smoothed objective lens adjustment amount.

[0056] With such a configuration, by smoothing the objective lens adjustment amount before scanning exposure, it is ensured that the objective lens movement time is not greater than the workpiece stage movement time or the exposure gear switching time, so that the exposure time is no longer limited by the objective lens movement time, thereby effectively improving the productivity of the exposure equipment; at the same time, because the scanning exposure time corresponding to the maximum movement time of the moving stage is not affected by the adjustment of the exposure gear, it also avoids overexposure or underexposure of the exposure field caused by the exposure gear adjustment, thereby improving the product yield.

[0057] The following is a description of the working principle of an exposure device when using the above exposure method.

[0058] Please refer to Figure 2In an optional embodiment, the embodiment of the present invention further provides an exposure device, which includes: an optical unit 5, a vertical monitoring unit 7, a work stage 1, a mask stage 3, a driving unit, a measuring unit 6, a control unit and a computing unit. The optical unit 5 includes a lens group 52 composed of a plurality of objective lens groups 52 and a light source 51, the light source 51 can be an ultraviolet light source, and the objective lens can be a lens; the vertical monitoring unit 7 includes a work stage vertical monitoring subunit 72 and a mask stage vertical monitoring subunit 71, which can be a vertical sensor for detecting and controlling the vertical position of the work stage 1 and / or the mask stage 3 (in this embodiment, the vertical position is the projection of the work stage 1 and / or the mask stage 3 on the XOY plane); the work stage 1 is used to carry the substrate 2; the mask stage 3 is used to carry the mask 4; the driving unit (not shown in the figure) includes a work stage driving subunit and an objective lens driving subunit. The moving unit and the driving unit may include a moving platform and a motor, which can provide power through the motor to drive the moving platform to carry the workpiece table 1 and / or the objective lens to move; the measuring unit 6 includes a substrate measuring subunit 61 and a mask measuring subunit 62, the substrate measuring subunit 61 can be a substrate focusing and leveling system (FLS-P), which can measure the surface shape of the substrate 2, and the mask measuring subunit 62 can be a mask focusing and leveling system (FLS-R), which can measure the surface shape of the mask 4; the control unit and the computing unit (not shown in the figure) can be an application in a mobile terminal or a chip built into the exposure device. In some other embodiments, the exposure device may also include other different components with similar functions, and those skilled in the art may configure this according to actual conditions.

[0059] Furthermore, the work stage 1 and the mask stage 3 are arranged along the axial direction A of the exposure device, the light source 51 is arranged on the side of the mask stage 3 away from the work stage 1, and the lens group 52 is arranged between the work stage 1 and the mask stage 3 along the axial direction A of the exposure device. The lens group 52 is composed of two columns of objective lens units 521, and the objective lens unit 521 is composed of multiple objective lens groups 52. A single objective lens includes a first movable lens arranged close to the mask stage 3, and a second movable lens arranged close to the work stage 1. The first movable lens is used to compensate for the local surface high-order quantity of the mask 4, and the second movable lens is used to compensate for the local surface high-order quantity of the substrate 2. The measuring unit 6 is arranged between two columns of objective lens units 521, and the two columns of objective lens units 521 are arranged in a direction perpendicular to the axial direction A of the exposure device. The measuring unit 6 is located on the side walls of the two columns of objective lens units 521 close to each other, wherein a plurality of mask measuring subunits 62 and substrate measuring subunits 61 are provided, and the mask measuring subunits 62 are arranged close to the mask stage 3, and the substrate measuring subunits 61 are arranged close to the substrate 2, and the mask measuring subunits 62 and the substrate measuring subunits 61 are arranged one by one along the axial direction A of the exposure device (in Figure 1 In the embodiment, the mask measurement subunits 62 are arranged one-to-one above the substrate measurement subunits 61).

[0060] Furthermore, the control unit is configured to form a workpiece stage motion trajectory and / or an objective lens motion trajectory based on the surface data of the substrate 2 and / or the mask 4 before scanning exposure, and smooth the objective lens motion trajectory to form a smoothed objective lens motion trajectory, so that the objective lens motion time matches the workpiece stage motion time or the exposure gear switching time; during scanning exposure, based on the workpiece stage motion trajectory and / or the smoothed objective lens motion trajectory, send a motion instruction to the driving unit. The calculation unit is used to calculate the surface data measured by the measuring unit 6 in the process of the control unit smoothing the objective lens motion trajectory and generating the smoothed motion trajectory, so as to cooperate with the control unit to control the exposure device. The control unit is connected to the driving unit, the measuring unit 6, the vertical monitoring unit 7 and the calculation unit in communication to realize the interaction between data and instructions.

[0061] Please refer to Figure 1 In an optional embodiment, the exposure method may include the following steps:

[0062] Step S1: Before scanning exposure, the mask stage vertical monitoring subunit 71 controls the height and tilt of the mask stage 3 to remain unchanged, and uses the mask measurement subunit 62 to measure the mask surface data; the workpiece stage vertical monitoring subunit 72 controls the height and tilt of the workpiece stage 1 to remain unchanged, and uses the substrate measurement subunit 61 to measure the substrate surface data.

[0063] In an optional embodiment, before step S1, it is usually necessary to perform global leveling on the work stage 1 so that the upper surface of the substrate 2 is substantially coincident with the leveling target surface, that is, in step S1, the work stage vertical monitoring subunit 72 needs to control the height and inclination of the work stage 1 to be equal to the height and inclination after global leveling; at the same time, in step S1, the mask stage vertical monitoring subunit 71 needs to control the vertical position of the mask stage 3 to remain unchanged (in this embodiment, the vertical position is the projection of the mask stage 3 on the XOY plane, that is, the height and inclination of the projection of the mask stage 3 on the XOY plane are kept unchanged), and start scanning along the Y direction. Of course, in other embodiments, the scanning direction of the exposure device can also be set along the X direction, and those skilled in the art can configure this according to actual conditions.

[0064] Step S2: pre-processing the mask surface shape data and / or substrate surface shape data to form processed mask surface shape and / or substrate surface shape.

[0065] It should be noted that the preprocessing of the mask surface shape data and / or the substrate surface shape data generally includes filtering. As an alternative embodiment, the filtering may be performed in a polynomial cyclic progressive manner, generally including the following steps:

[0066] Step S21: removing invalid points, i.e. points in the mask surface shape data and / or substrate surface shape data that are equal to 0 or infinite;

[0067] Step S22: removing measurement points with duplicate positions;

[0068] Step S23: Fit all measurement points into an n-th order standard polynomial, calculate the residual and 3sigma value, and remove the measurement points with residuals greater than 3sigma;

[0069] Step S24: Repeat step S23 for the remaining points until the residuals of all points are less than the 3sigma value, and set the maximum number of cycles to make a termination decision.

[0070] Since the workpiece stage 1 and the objective lens are both in a moving state during the scanning exposure process, there is a one-to-one correspondence between the position of the measuring point and the time, that is, for the same measuring point, the position at different times is different.

[0071] In another optional embodiment, the preprocessing of the mask surface shape data and / or the substrate surface shape data may also include extrapolation processing to obtain the overall height and overall inclination of the mask 4 and / or the substrate 2. It should be noted that during the scanning exposure process, when entering and exiting the scanning field of view, the light spot of the measuring unit 6 may have been outside the mask 4 and / or the substrate 2, and the current measurement value cannot be obtained. At this time, it is necessary to extrapolate the mask surface shape and / or the substrate surface shape. In this embodiment, a plane can be fitted according to the existing surface shape data, and then the position of the extrapolation point is calculated, and finally the extrapolation point is brought in to obtain the extrapolated surface shape.

[0072] Step S3: Divide the mask surface shape and / or substrate surface shape according to the exposure position and the exposure field size, use the static field of view of the objective lens as the sliding window 8, and slide from the exposure start point of the exposure field to the exposure end point, perform plane fitting on the mask surface shape data and / or substrate surface shape data in a single sliding window 8 during the sliding process, use the overall fitting value as the workpiece stage adjustment amount, and use the fitting residual under a single objective lens as the objective lens adjustment amount of the objective lens.

[0073] In an alternative embodiment, please refer to Figure 3 to Figure 4 , during the sliding window 8 sliding process, the plane is fitted using the measurement points in the static field of view:

[0074] Z i =aX i +bY i +c

[0075] Where, X i , Y i , Z irepresents all the measurement points in the static field of view sliding; a, b, c are the plane coefficients of the six-spot measurement values ​​of the measurement unit 6 at different positions.

[0076] Thus, based on the result of plane fitting, the overall fitting value is used as the workpiece stage adjustment amount, and the fitting residual under a single objective lens is used as the objective lens adjustment amount of the objective lens. In some other examples, the workpiece stage adjustment amount and / or the objective lens adjustment amount can also be obtained by other means, and those skilled in the art can configure this according to actual conditions.

[0077] Step S4: Smoothing the objective lens adjustment amount so that the objective lens movement time is less than or equal to the last scanning exposure time in any two adjacent moments.

[0078] Furthermore, the smoothing process may include the following steps:

[0079] Step S41: Calculate the gradient value based on the position data of the workpiece stage 1 at two adjacent moments and the corresponding objective lens adjustment amount, and compare it with the gradient threshold.

[0080] As an optional embodiment, the gradient value includes a first gradient value, and the first gradient value is calculated by the position data of the workpiece stage 1 at two adjacent moments and the corresponding objective lens adjustment amount, and the calculation formula is:

[0081]

[0082] In the formula, is the first gradient value; z(i) is the objective lens adjustment amount at any moment; y(i) is the position data of the workpiece stage 1 corresponding to z(i).

[0083] Correspondingly, the gradient threshold includes a first gradient threshold, which is calculated by the maximum scanning speed of the objective lens and the maximum scanning speed of the workpiece stage, and the calculation formula is:

[0084] TH1=V max_PO / V max_WS

[0085] Where TH1 is the first gradient threshold; V max_PO V is the maximum scanning speed of the objective lens; max_WS It is the maximum scanning speed of the workpiece stage.

[0086] In another optional embodiment, the gradient threshold may further include a second gradient threshold, which is calculated by the maximum scanning speed of the objective lens, the scanning length of the exposure field, and the minimum exposure time, and the calculation formula is:

[0087]

[0088] Where TH2 is the second gradient threshold; V max_PO is the maximum scanning speed of the objective lens; Y scan is the scanning length of the exposure field; T min_DC is the minimum exposure time (i.e., the exposure time under maximum illumination), which can be calculated through the exposure field dose and illumination information of different exposure gears.

[0089] It should be noted that in the above embodiment, the first gradient value only needs to be compared with one of the first gradient threshold and the second gradient threshold. It can be understood by those skilled in the art that the scanning exposure time of the exposure device for each exposure field mainly depends on the time required for each exposure gear when scanning and exposing this exposure field, the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage, and the scanning exposure time corresponding to the maximum scanning speed of the objective lens. The actual scanning exposure time is the scanning time of a certain exposure gear, and the scanning time of the exposure gear is generally selected according to the following principles: select the exposure gear time with the smallest exposure time; the selected exposure gear time is greater than or equal to the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage; the selected exposure gear time is greater than or equal to the scanning exposure time corresponding to the maximum scanning speed of the objective lens. The main problem that currently limits the improvement of yield is that the scanning exposure time corresponding to the maximum scanning speed of the objective lens is much greater than the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage, and is greater than the ideal exposure gear time; and in different exposure fields, the scanning exposure time corresponding to the maximum scanning speed of the objective lens is inconsistent, resulting in inconsistent selected exposure gear time. Therefore, this embodiment compares the gradient value with the gradient threshold and, through a subsequent optimization scheme, makes the scanning exposure time corresponding to the maximum scanning speed of the objective lens less than or equal to the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage or less than or equal to the ideal exposure gear time. Therefore, the optimized scanning exposure time is no longer limited by the scanning exposure time corresponding to the maximum scanning speed of the objective lens, and the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage or the ideal exposure gear time does not change due to changes in the exposure field, which not only improves the productivity but also avoids overexposure or underexposure caused by exposure gear adjustment.

[0090] As a preferred embodiment, the gradient value also includes a second gradient value, and the second gradient value is calculated by the first gradient values ​​at two adjacent moments and the corresponding position data of the workpiece stage 1, and the calculation formula is:

[0091]

[0092] In the formula, is the second gradient value; is the first gradient value at any moment; y(i) is the corresponding position data of the workpiece stage 1.

[0093] Correspondingly, the gradient threshold also includes a third gradient threshold, which is calculated by the maximum scanning speed of the objective lens, the maximum scanning speed of the workpiece stage, the maximum scanning acceleration of the objective lens, and the maximum scanning acceleration of the workpiece stage, and the calculation formula is:

[0094]

[0095] Where TH3 is the third gradient threshold; a max_PO is the maximum scanning acceleration of the objective lens; a max_WS V is the maximum scanning acceleration of the workpiece stage; max_PO V is the maximum scanning speed of the objective lens; max_WS It is the maximum scanning speed of the workpiece stage.

[0096] It should be noted that the first gradient value is a first-order gradient, that is, the limitation of the maximum scanning speed of the objective lens on the scanning exposure time is considered; the second gradient value is a second-order gradient, that is, the limitation of the maximum scanning acceleration of the objective lens on the scanning exposure time is considered. Those skilled in the art can understand that when the objective lens moves in one direction at a certain moment, and needs to move in the opposite direction of the movement direction at the next moment, the maximum scanning acceleration of the objective lens may not meet the requirement of the scanning speed of the objective lens. Therefore, taking into account the limitation of the maximum scanning acceleration of the objective lens on the scanning exposure time can avoid the situation where the maximum scanning acceleration of the objective lens cannot meet the scanning speed of the objective lens, thereby ensuring that the scanning exposure time corresponding to the maximum scanning speed of the objective lens can be less than or equal to the scanning exposure time corresponding to the maximum scanning speed of the workpiece stage or less than or equal to the ideal exposure gear time.

[0097] Step S42: if the gradient value is greater than the gradient threshold, the objective lens adjustment amount at that moment is smoothed to obtain a smoothed objective lens adjustment amount, and then a smoothed gradient value is calculated based on the smoothed objective lens adjustment amount until the smoothed gradient value is less than or equal to the gradient threshold to obtain a smoothed objective lens adjustment amount;

[0098] If the gradient value is less than or equal to the gradient threshold, no processing is performed on the objective lens adjustment amount at that moment.

[0099] It should be noted that the smoothing process needs to traverse the objective lens adjustment amounts at all times from the exposure start point to the exposure end point of the exposure field, wherein the objective lens adjustment amount at any time corresponds to the corresponding position data of the workpiece stage 1 .

[0100] When the gradient value is greater than the gradient threshold, that is, in the aforementioned embodiment, or or As an alternative embodiment, the smoothed objective lens adjustment amount can be calculated from the objective lens adjustment amount at this moment and the objective lens adjustment amount at the previous moment, and the calculation formula is:

[0101]

[0102] In the formula, z new(i) is the smoothed objective lens adjustment amount; z(i) is the objective lens adjustment amount at any moment.

[0103] In another optional embodiment, the smoothed objective lens adjustment amount can be calculated from the objective lens adjustment amount at this moment and the objective lens adjustment amounts at multiple adjacent moments, and the calculation formula is:

[0104] z new(i) =A2·z(i+2)+A1·z(i+1)+A0·z(i)+B1·z(i-1)+B2·z(i-2)

[0105] In the formula, z new(i) is the objective lens adjustment amount after smoothing; z(i) is the objective lens adjustment amount at any moment; Ai and Bi are weight factors (which can be obtained according to experiments). In this embodiment, the sliding window 8 includes the objective lens adjustment amount at this moment and the objective lens adjustment amounts at the first two moments and the last two moments. By expanding the range of the sliding window 8 to cover more measurement points, the overall smoothing of the objective lens adjustment amount within this period of time can be achieved. In some other embodiments, the sliding window 8 can also include the objective lens adjustment amounts at more moments, and those skilled in the art can configure this according to actual conditions.

[0106] The smoothed objective lens adjustment amount can be obtained by smoothing through one of the above two formulas, and steps S41 and S42 are repeated until the gradient value is less than or equal to the gradient threshold, that is, or or When , the repetition ends, and the smoothed objective lens adjustment amount is output as the objective lens adjustment amount for fitting the second coefficient.

[0107] When the gradient value is less than or equal to the gradient threshold, that is or or When , the objective lens adjustment amount is directly output as the objective lens adjustment amount for fitting the second coefficient.

[0108] Step S5: forming a first coefficient based on the workpiece stage adjustment amount, and forming a second coefficient based on the smoothed objective lens adjustment amount.

[0109] It should be noted that, in this embodiment, the workpiece stage adjustment amount obtained in step S3 is fitted by Legendre or other orthogonal polynomials to obtain the first coefficient; the smoothed objective lens adjustment amount obtained in step S4 is fitted by Legendre or other orthogonal polynomials to obtain the second coefficient.

[0110] Step S6: During scanning exposure, the real-time workpiece stage adjustment amount is calculated based on the first coefficient, the real-time objective lens adjustment amount is calculated based on the second coefficient, and the movement of the workpiece stage driving subunit and the objective lens driving subunit are controlled accordingly.

[0111] As an alternative embodiment, the calculation formula of the real-time adjustment amount is as follows:

[0112] dz i (y) = C 0i ·f0(y)+C 1i f1(y)+C 2i f2(y)+…+C ni ·f n (y)

[0113] In the formula, dz i (y) is the real-time workpiece stage adjustment amount or the real-time objective lens adjustment amount; f i (y) is Legendre or other orthogonal polynomial basis function; C ji is the first coefficient or the second coefficient obtained by sequential fitting at different times.

[0114] In summary, in the parameter control method and exposure method provided by the embodiments of the present invention, the parameter control method includes: before scanning exposure, obtaining substrate surface shape data and mask surface shape data; based on the substrate surface shape data and the mask surface shape data, obtaining the workpiece stage adjustment amount and the objective lens adjustment amount, and forming the workpiece stage motion trajectory and the objective lens motion trajectory; smoothing the objective lens motion trajectory to obtain the smoothed objective lens adjustment amount, and forming the smoothed objective lens motion trajectory, so that the objective lens movement time is not greater than the workpiece stage movement time or the exposure gear switching time; forming a first coefficient based on the workpiece stage adjustment amount, and forming a second coefficient based on the smoothed objective lens adjustment amount.

[0115] With such a configuration, by smoothing the objective lens adjustment amount before scanning exposure, it is ensured that the objective lens movement time is not greater than the workpiece stage movement time or the exposure gear switching time, so that the exposure time is no longer limited by the objective lens movement time, thereby effectively improving the productivity of the exposure equipment; at the same time, because the scanning exposure time corresponding to the maximum movement time of the moving stage is not affected by the adjustment of the exposure gear, it also avoids overexposure or underexposure of the exposure field caused by the exposure gear adjustment, thereby improving the product yield.

[0116] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A parameter control method, characterized in that: include: Before scanning exposure, obtaining substrate surface shape data and mask surface shape data; Based on the substrate surface shape data and the mask surface shape data, the workpiece stage adjustment amount and the objective lens adjustment amount are obtained, and the workpiece stage motion trajectory and the objective lens motion trajectory are formed; Smoothing the objective lens motion trajectory to obtain a smoothed objective lens adjustment amount and forming a smoothed objective lens motion trajectory, so that the objective lens motion time is not greater than the workpiece stage motion time or the exposure gear switching time; A first coefficient is formed based on the workpiece stage adjustment amount, and a second coefficient is formed based on the smoothed objective lens adjustment amount.

2. The parameter control method according to claim 1, characterized in that: The smoothing process of the objective lens motion trajectory includes: Based on the substrate surface shape data at any moment and the corresponding objective lens adjustment amount, a gradient value is obtained and compared with a gradient threshold value to determine whether to perform smoothing processing on the objective lens adjustment amount at that moment.

3. The parameter control method according to claim 2, characterized in that: The gradient value includes a first gradient value; The first gradient value includes a ratio of the objective lens adjustment amount at two adjacent moments to the position data of the workpiece stage respectively corresponding thereto.

4. The parameter control method according to claim 3, characterized in that: The gradient threshold comprises a first gradient threshold; The first gradient threshold comprises a ratio of a maximum scanning speed of the objective lens to a maximum scanning speed of the workpiece stage.

5. The parameter control method according to claim 3, characterized in that: The gradient threshold comprises a second gradient threshold; The second gradient threshold is calculated by the minimum exposure time, the scanning length of the exposure field and the maximum scanning speed of the objective lens. The calculation formula of the second gradient threshold is: Where TH2 is the second gradient threshold; V max_PO is the maximum scanning speed of the objective lens; Y scan is the scanning length of the exposure field; T min_DC is the minimum exposure time.

6. The parameter control method according to claim 3, characterized in that: The gradient value also includes a second gradient value; The second gradient value includes a ratio of the first gradient value at two adjacent moments to the position data of the workpiece stage respectively corresponding thereto.

7. The parameter control method according to claim 6, characterized in that: The gradient threshold comprises a third gradient threshold; The third gradient threshold is calculated by the maximum scanning speed of the objective lens, the maximum scanning speed of the workpiece stage, the maximum scanning acceleration of the objective lens, and the maximum scanning acceleration of the workpiece stage. The calculation formula of the third gradient threshold is: Where TH3 is the third gradient threshold; a max_PO V is the maximum scanning acceleration of the objective lens; max_WS is the maximum scanning speed of the workpiece stage; a max_WS V is the maximum scanning acceleration of the workpiece stage; max_PO is the maximum scanning speed of the objective lens.

8. The parameter control method according to claim 4, 5 or 7, characterized in that: If the gradient value is greater than the gradient threshold, smoothing the objective lens adjustment amount at that moment to obtain a smoothed objective lens adjustment amount, and then calculating a smoothed gradient value based on the smoothed objective lens adjustment amount until the smoothed gradient value is less than or equal to the gradient threshold to obtain the smoothed objective lens adjustment amount; If the gradient value is less than or equal to the gradient threshold, the objective lens adjustment amount at this moment is not processed.

9. The parameter control method according to claim 8, characterized in that: The smoothed objective lens adjustment amount includes an average of the objective lens adjustment amount at this moment and the objective lens adjustment amount at a previous moment.

10. The parameter control method according to claim 8, characterized in that: The smoothed objective lens adjustment amount is calculated by the objective lens adjustment amount at this moment and the objective lens adjustment amounts at multiple adjacent moments; the calculation formula of the smoothed objective lens adjustment amount is: z new(i) =A2·z(i+2)+A1·z(i+1)+A0·z(i)+B1·z(i-1)+B2·z(i-2) In the formula, z new(i) is the smoothed objective lens adjustment amount; z(i) is the objective lens adjustment amount at any moment; Ai and Bi are weight factors.

11. The parameter control method according to claim 1, characterized in that: An orthogonal polynomial fitting is performed based on the workpiece stage adjustment amount to form a first coefficient, and an orthogonal polynomial fitting is performed based on the smoothed objective lens adjustment amount to form a second coefficient.

12. The parameter control method according to claim 1, characterized in that: The substrate surface data and the mask surface data are slid by using the static field of view of the objective lens as a sliding window, and the surface data within a single sliding window sliding from the exposure start point of the exposure field to the exposure end point is plane fitted to obtain the workpiece stage adjustment amount and the objective lens adjustment amount.

13. The parameter control method according to claim 1, characterized in that: Before obtaining the workpiece stage adjustment amount and the objective lens adjustment amount, the substrate surface shape data and the mask surface shape data are preprocessed.

14. An exposure method, characterized in that: Using the parameter control method as described in any one of claims 1 to 13; and during scanning exposure, calculating the real-time workpiece stage adjustment amount based on the first coefficient, and calculating the real-time objective lens adjustment amount based on the second coefficient; The position of the workpiece stage is adjusted based on the real-time workpiece stage adjustment amount, and the position of the objective lens is adjusted based on the real-time objective lens adjustment amount.

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