Exposure equipment

Abstract

The present invention provides an exposure apparatus, comprising: a workpiece stage, a mask stage, an optical unit including a light source and a mirror group; a driving unit for driving the objective lens and / or the workpiece stage to move; a measuring unit for measuring the surface shape data of the substrate and / or the mask; and a control unit configured to, before scanning exposure, form the movement trajectory of the workpiece stage and / or the movement trajectory of the objective lens, and perform smoothing processing on the movement trajectory of the objective lens to form a smoothed movement trajectory of the objective lens; during scanning exposure, based on the movement trajectory of the workpiece stage and / or the smoothed movement trajectory of the objective lens, send a movement instruction to the driving unit. With such a configuration, by optimizing the movement trajectory of the objective lens, the movement time of the objective lens is made to match the movement time of the workpiece stage or the exposure gear switching time, the exposure time is no longer limited by the movement time of the objective lens, the productivity of the exposure apparatus is effectively improved, and the overexposure or underexposure phenomena of the exposure field caused by the adjustment of the exposure gear are avoided, and the yield of the product is improved.

Description

Technical Field

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

[0002] The essence of the lithography process is to copy the temporary circuit structure onto the silicon wafer to be etched and ion-implanted. These structures are first made in the form of patterns on the mask, and then the patterns are transferred to the photosensitive film on the surface of the silicon wafer by using a light beam passing through the mask. The lithography process is usually carried out as follows: after lithography and development, the pattern appears on the silicon wafer, and then the film pattern is imaged on the silicon wafer by chemical etching process, or the selective doping in the pattern on the silicon wafer is completed by ion implantation. The lithography process usually includes the following eight basic steps: vapor bottom coating, spin coating, soft baking, alignment and exposure, post-exposure baking, development, hard 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 a light source and an optical system; among them, the optical system usually includes a lens group. During the exposure process, the movement of the lens group can be controlled by a fitted polynomial trajectory to achieve exposure compensation for the material. However, usually the movement speed of the lens group is lower than that 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 lens group to be too long, and the speed performance of the workbench cannot be fully utilized, resulting in a reduction in productivity; moreover, in different exposure fields, the movement time of the lens group may be inconsistent. For exposure devices that do not support exposure field gear switching, it will cause overexposure or underexposure of the exposure field. Summary of the Invention

[0004] The purpose of the present invention is to provide an exposure device to solve the problem that the movement speed of the objective lens does not match the movement speed of the worktable, resulting in a reduction in productivity and prone to overexposure or underexposure of the exposure field.

[0005] To achieve the above purpose, the present invention provides an exposure device, including:

[0006] A worktable for carrying a substrate;

[0007] A mask table for carrying a mask;

[0008] An optical unit including a light source and a lens group. The light source is arranged on the side of the mask table away from the worktable; the lens group is composed of a plurality of objective lenses and is arranged between the mask table and the worktable for compensating the exposure of the substrate and / or the mask;

[0009] A driving unit for driving the movement of the objective lens and / or the worktable;

[0010] A measuring unit for measuring the surface shape data of the substrate and / or the mask;

[0011] A control unit, communicatively connected to the measurement unit and the driving unit;

[0012] The control unit is configured to, before the scanning exposure, based on the surface shape data of the substrate and / or the mask, form a stage movement trajectory and / or an objective lens movement trajectory, and smooth the objective lens movement trajectory to form a smoothed objective lens movement trajectory, so that the movement time of the objective lens matches the movement time of the stage or the exposure gear switching time; during the scanning exposure, based on the stage movement trajectory and / or the smoothed objective lens movement trajectory, send a movement instruction to the driving unit.

[0013] Optionally, the control unit is further configured to generate a stage adjustment amount and an objective lens adjustment amount based on the surface shape data of the substrate and / or the mask, so as to form the stage movement trajectory and / or the objective lens movement trajectory.

[0014] Optionally, the exposure device further includes:

[0015] A calculation unit, communicatively connected to the control unit;

[0016] The calculation unit is configured to, when smoothing the objective lens movement trajectory, calculate a gradient value based on the surface shape data of the substrate at any moment measured by the measurement unit and the corresponding objective lens adjustment amount, and compare it with a gradient threshold to determine whether to adjust the objective lens adjustment amount at this moment.

[0017] Optionally, if the gradient value is greater than the gradient threshold, the calculation unit smooths the objective lens adjustment amount, then calculates 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, and outputs the smoothed objective lens adjustment amount;

[0018] If the gradient value is less than or equal to the gradient threshold, the calculation unit outputs the objective lens adjustment amount.

[0019] Optionally, the control unit is further configured to smooth the objective lens movement trajectory based on the objective lens adjustment amount to generate a smoothed objective lens adjustment amount, and generate a smoothed objective lens movement trajectory based on the smoothed objective lens adjustment amount;

[0020] Meanwhile, generate a first coefficient based on the stage adjustment amount and a second coefficient based on the smoothed objective lens adjustment amount.

[0021] Optionally, the exposure device further includes:

[0022] A calculation unit, communicatively connected to the control unit;

[0023] The calculation unit is configured to calculate a real-time workpiece stage adjustment amount based on the first coefficient and calculate a real-time objective lens adjustment amount based on the second coefficient during scanning exposure.

[0024] Optionally, the driving unit includes:

[0025] A workpiece stage driving sub-unit for driving the workpiece stage to drive the substrate to move;

[0026] An objective lens driving sub-unit for driving the objective lens to move;

[0027] The motion instruction includes a substrate motion instruction and an objective lens motion instruction;

[0028] The control unit is further configured to send the substrate motion instruction to the workpiece stage driving sub-unit based on the real-time workpiece stage adjustment amount; and send the objective lens motion instruction to the objective lens driving sub-unit based on the real-time objective lens adjustment amount.

[0029] Optionally, the exposure device further includes:

[0030] A calculation unit communicatively connected to the control unit;

[0031] The calculation unit is configured to perform plane fitting on the surface shape data within a single sliding window that slides from the exposure start time to the exposure end time in the self-exposure field with the objective lens static field of view as the sliding window based on the surface shape data of the substrate and / or the mask, and respectively form the workpiece stage adjustment amount and the objective lens adjustment amount.

[0032] Optionally, the control unit is further configured to preprocess the surface shape data of the substrate and / or the mask before generating the workpiece stage adjustment amount and the objective lens adjustment amount.

[0033] Optionally, the objective lens includes:

[0034] A first movable lens disposed close to the mask stage for compensating for the high-order amount of the local surface shape of the mask;

[0035] A second movable lens disposed close to the workpiece stage for compensating for the high-order amount of the local surface shape of the substrate.

[0036] Optionally, the lens group is composed of two columns of objective lens sub-units, the objective lens sub-unit includes a plurality of the objective lenses, and the measurement unit is disposed between the two columns of the objective lens sub-units; wherein, the measurement unit includes:

[0037] A mask measurement sub-unit disposed close to the mask stage for measuring the surface shape data of the mask;

[0038] A substrate measurement subunit, which is disposed close to the worktable and arranged axially along the exposure device with the template measurement subunit, is configured to measure the surface shape data of the substrate.

[0039] Optionally, the exposure device further includes:

[0040] A vertical monitoring unit, which is configured to monitor the vertical positions of the mask table and / or the worktable.

[0041] Compared with the existing exposure device, the exposure device provided by the present application has the following advantages:

[0042] In the present application, the control unit and the calculation unit optimize the movement trajectory of the objective lens based on the measured surface shape data, so that the movement time of the objective lens matches the movement time of the worktable. In this way, the scanning exposure time of the exposure device is no longer limited by the movement time of the objective lens, thereby improving the productivity of the exposure device; and since the scanning exposure time corresponding to the maximum movement speed of the worktable does not change due to the adjustment of the exposure level, the overexposure or underexposure of the exposure field caused by the adjustment of the exposure level is also avoided, improving the yield of the product. Description of the Drawings

[0043] Figure 1 It is a schematic structural diagram of the exposure device provided by an embodiment of the present invention;

[0044] Figure 2 It is a schematic flowchart of the exposure method provided by an embodiment of the present invention;

[0045] Figure 3 It is a schematic diagram of traversing the exposure field by a sliding window provided by an embodiment of the present invention;

[0046] Figure 4 It is a fitting schematic diagram of the material surface shape provided by an embodiment of the present invention;

[0047] 1 - Worktable; 2 - Substrate; 3 - Mask table; 4 - Mask;

[0048] 5 - Optical unit; 51 - Light source; 52 - Mirror group; 521 - Objective lens subunit;

[0049] 6 - Measurement unit; 61 - Substrate measurement subunit; 62 - Mask measurement subunit;

[0050] 7 - Vertical monitoring unit; 71 - Mask table vertical monitoring subunit; 72 - Worktable vertical monitoring subunit;

[0051] 8 - Sliding window;

[0052] A - Axis. Detailed Embodiments

[0053] To make the objectives, advantages and features of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in a very simplified form and not drawn to scale, and are only used to conveniently and clearly assist in explaining the objectives of the embodiments of the present invention. In addition, the structures shown in the accompanying drawings are often part of the actual structures. In particular, the accompanying drawings need to show different focuses at different times, and sometimes different scales are used.

[0054] As used in this specification, the singular forms "a", "an" and "the" include plural objects. The term "or" is generally used in the sense of including "and / or". The term "several" is generally used in the sense of including "at least one". The term "at least two" is generally used in the sense of including "two or more". In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third" may explicitly or implicitly include one or at least two of such features. "One end" and "the other end", as well as "proximal end" and "distal end" generally refer to corresponding two parts, which not only include the end time. The terms "mounted", "connected", "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected, or indirectly connected through an intermediate medium. It may be the internal communication of two components or the interaction relationship between two components. In addition, as used in this specification, when an element is provided on another element, it generally only means that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the two elements may be directly or indirectly connected, coupled, cooperated or transmitted through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, an element may be inside, outside, above, below or on one side of another element, etc. in any orientation, unless otherwise clearly specified in the content. The terms "upper", "lower", "top", "bottom" are generally relative position relationships arranged in the direction of gravity; the terms "vertical, vertical direction" generally refer to the direction along the gravity direction, which is generally perpendicular to the ground, and the "horizontal, horizontal plane direction" is generally along the direction parallel to the ground; for those of ordinary skill in the art, the specific meanings of the above terms in this specification can be understood according to specific circumstances.

[0055] The objective of the present invention is to provide an exposure device to solve the problem that the moving speed of the objective lens does not match the moving speed of the workpiece stage, resulting in a reduction in productivity and easy overexposure or underexposure of the exposure field.

[0056] Those skilled in the art can understand that the principle of the lithography process is similar to that of the photography function of a camera. A camera uses light and lenses to project the image of the object to be photographed onto a negative, and then transfers the image on the negative to photo paper through development to form a photo. In the lithography process, the pattern on the mask is the target to be photographed. 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 lithography process usually include: the surface shape of the mask and / or the substrate, the moving speed of the driving 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 impact of the moving speed of the driving device on the accuracy of the lithography process, and defaults that other influencing factors meet the accuracy requirements of the lithography process. During the lithography process, it is necessary to move the workpiece stage to complete the lithography of the patterns on different masks, and at the same time, it is also necessary to move the lens group according to the surface shape of the mask and / or the substrate to achieve different exposure compensations. At this time, the moving speed of the driving device becomes the key factor affecting the productivity and yield of the exposure equipment. In the prior art, the movement of the objective lens and / or the workpiece stage is usually controlled by a polynomial trajectory formed by fitting. However, due to the limitations of the strength and structure of the objective lens itself, the maximum movement speed of the objective lens driving device is lower than that of the workpiece stage driving device. Therefore, under the same conditions, the movement time of the objective lens is longer than that of the workpiece stage, which makes the scanning exposure time of the exposure equipment depend on the movement time of the objective lens, greatly reducing the productivity of the exposure equipment. At the same time, during the adjustment of the exposure level (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 may not have reached the position yet, resulting in overexposure or underexposure of the exposure field, directly affecting the yield of the product. Based on this, this application provides an exposure equipment, which optimizes the movement trajectory of the objective lens so that the movement time of the objective lens matches that of the workpiece stage. In this way, the scanning exposure time of the exposure equipment is no longer limited by the movement time of the objective lens, thus improving the productivity of the exposure equipment. Also, since the scanning exposure time corresponding to the maximum movement speed of the workpiece stage does not change due to the adjustment of the exposure level, the overexposure or underexposure phenomenon of the exposure field caused by the adjustment of the exposure level is also avoided, improving the yield of the product.

[0057] The following is an illustration with reference to the accompanying drawings.

[0058] As an alternative embodiment, please refer to Figure 1, an embodiment of the present invention provides an exposure device, which includes: an optical unit 5, a vertical monitoring unit 7, a workpiece stage 1, a mask stage 3, a driving unit, a measuring unit 6, a control unit, and a computing unit. Among them, 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 51, and the objective lens can be a lens; the vertical monitoring unit 7 includes a workpiece stage vertical monitoring subunit 72 and a mask stage vertical monitoring subunit 71, which can be vertical sensors for detecting and controlling the vertical positions of the workpiece stage 1 and / or the mask stage 3 (in this embodiment, the vertical position is the projection of the workpiece stage 1 and / or the mask stage 3 on the XOY plane); the workpiece 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 workpiece stage 1 driving subunit and an objective lens driving subunit. The driving unit can include a moving platform and a motor, which can provide power through the motor to drive the moving platform to carry the workpiece stage 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. 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 program in a mobile terminal or a chip built into the exposure device. In some other embodiments, the exposure device may further include other different components with similar functions, and those skilled in the art can configure them according to the actual situation.

[0059] Further, the workpiece 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 workpiece stage 1. The lens group 52 is arranged between the workpiece 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 sub-units 521. The objective lens sub-unit 521 is composed of a plurality of 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 workpiece stage 1. The first movable lens is used to compensate the high-order amount of the local surface shape of the mask 4, and the second movable lens is used to compensate the high-order amount of the local surface shape of the substrate 2. The measuring unit 6 is arranged between the two columns of objective lens sub-units 521. The two columns of objective lens sub-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 sub-units 521 close to each other. Among them, a plurality of mask measuring subunits 62 and substrate measuring subunits 61 are both provided. 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. The mask measuring subunits 62 and the substrate measuring subunits 61 are arranged in one-to-one correspondence along the axial direction A of the exposure device (in Figure 1 which, the mask measuring subunits 62 are arranged directly above the substrate measuring subunits 61 in one-to-one correspondence).

[0060] Further, the control unit is configured to, before the scanning exposure, form a stage movement trajectory and / or an objective lens movement trajectory based on the surface shape data of the substrate 2 and / or the mask 4, and smooth the objective lens movement trajectory to form a smoothed objective lens movement trajectory, so that the movement time of the objective lens matches the movement time of the stage or the exposure gear switching time; during the scanning exposure, based on the stage movement trajectory and / or the smoothed objective lens movement trajectory, send a movement instruction to the drive unit. The calculation unit is used to calculate the surface shape data measured by the measurement unit 6 during the process that the control unit smooths the objective lens movement trajectory and generates a smoothed movement trajectory, so as to cooperate with the control unit to control the exposure device. The control unit is communicatively connected to the drive unit, the measurement unit 6, the vertical monitoring unit 7, and the calculation unit to realize the interaction between data and instructions.

[0061] With such a configuration, the control unit and the calculation unit optimize the movement trajectory of the objective lens based on the measured surface shape data, so that the movement time of the objective lens matches the movement time of the stage 1. In this way, the scanning exposure time of the exposure device is no longer limited by the movement time of the objective lens, thereby improving the productivity of the exposure device; and because the scanning exposure time corresponding to the maximum movement speed of the stage 1 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, improving the yield of the product.

[0062] Next, in combination with the steps in the scanning exposure process of the exposure device, the exposure device and the working principle of the exposure device will be further described.

[0063] Please refer to Figure 2 , in an optional embodiment, the exposure method may include the following steps:

[0064] Step S1: Before the scanning exposure, the vertical monitoring subunit 71 of the mask stage 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 shape data; the vertical monitoring subunit 72 of the stage controls the height and tilt of the stage 1 to remain unchanged, and uses the substrate measurement subunit 61 to measure the substrate surface shape data.

[0065] In an alternative embodiment, before step S1, it is usually necessary to globally level the workpiece table 1 so that the upper surface of the substrate 2 substantially coincides with the leveling target surface. That is, in step S1, the vertical monitoring subunit 72 of the workpiece table needs to control the height and inclination of the workpiece table 1 to be equal to the height and inclination after global leveling. At the same time, in step S1, the vertical monitoring subunit 71 of the mask table needs to control the vertical position of the mask table 3 to remain unchanged (in this embodiment, the vertical position is the projection of the mask table 3 on the XOY plane, that is, the height and inclination of the projection of the mask table 3 on the XOY plane remain unchanged), and start scanning along the Y direction. Of course, in some 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 it according to the actual situation.

[0066] Step S2: Preprocess the mask surface shape data and / or the substrate surface shape data to form the processed mask surface shape and / or substrate surface shape.

[0067] It should be noted that preprocessing the mask surface shape data and / or the substrate surface shape data usually includes filtering. As an alternative embodiment, filtering can be performed in a polynomial cyclic progression manner, which generally includes the following steps:

[0068] Step S21: Remove invalid points, that is, the points equal to 0 or infinity in the mask surface shape data and / or the substrate surface shape data;

[0069] Step S22: Remove the measurement points with repeated positions;

[0070] Step S23: Fit all the measurement points into an nth-order standard polynomial, calculate the residual sum and the 3sigma value, and remove the measurement points with residuals greater than 3sigma;

[0071] Step S24: Repeat step S23 for the remaining points until the residuals of all points are less than the 3sigma value, and set a maximum number of cycles for termination determination.

[0072] Since both the workpiece table 1 and the objective lens are in a moving state during the scanning exposure process, there is a one-to-one correspondence between the position of the measurement point and the time. That is, for the same measurement point, the positions at different times are different.

[0073] In another alternative embodiment, preprocessing the mask surface shape data and / or the substrate surface shape data may further include extrapolation processing to obtain the overall height and overall tilt 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 exited outside the mask 4 and / or the substrate 2, and the current measurement value cannot be obtained. At this time, extrapolation of the mask surface shape and / or the substrate surface shape is required. In this embodiment, a plane can be fitted based on the existing surface shape data, then the position of the extrapolation point is calculated, and finally the extrapolation point is brought in to obtain the extrapolated surface shape.

[0074] In step S2, the judgments in step S21, step S22, and step S24 are performed by the control unit traversing all the surface shape data and filtering; step S23 and the extrapolation processing are calculated by the calculation unit based on the measured surface shape data.

[0075] Step S3: Divide the mask surface shape and / or the 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 to the exposure end point of the exposure field. Fit a plane to the mask surface shape data and / or the substrate surface shape data within 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 for that objective lens.

[0076] In an alternative embodiment, please refer to Figures 3 to 4 , during the sliding process of the sliding window 8, use the measurement points within the static field of view to fit a plane:

[0077] Z i = aX i + bY i + c

[0078] In the formula, X i , Y i , Z i represent all the measurement points during the sliding of the static field of view; a, b, and c are the plane coefficients fitted by the six-light-spot measurement values of the measuring unit 6 at different positions.

[0079] In this way, based on the result of the plane fitting, 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 for that objective lens. In some other exemplary embodiments, 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 the actual situation.

[0080] In step S3, the workpiece stage adjustment amount and the objective lens adjustment amount are calculated by the calculation unit; the operation instruction to traverse the entire exposure field through the sliding window 8 is issued by the control unit.

[0081] Step S4: Smooth the objective lens adjustment amount so that within any two adjacent moments, the movement time of the objective lens is less than or equal to the final scanning exposure time.

[0082] Further, the smoothing process may include the following steps:

[0083] Step S41: Calculate the gradient value based on the position data of the stage 1 at two adjacent moments and the corresponding objective lens adjustment amount, and compare it with the gradient threshold.

[0084] As an optional embodiment, the gradient value includes a first gradient value, which is calculated from the position data of the stage 1 at two adjacent moments and the corresponding objective lens adjustment amount. The calculation formula is:

[0085]

[0086] 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 stage 1 corresponding to z(i).

[0087] Correspondingly, the gradient threshold includes a first gradient threshold, which is calculated from the maximum scanning speed of the objective lens and the maximum scanning speed of the stage. The calculation formula is:

[0088] TH1 = V max_PO / V max_WS

[0089] In the formula, TH1 is the first gradient threshold; V max_PO is the maximum scanning speed of the objective lens; V max_WS is the maximum scanning speed of the stage.

[0090] In another optional embodiment, the gradient threshold may further include a second gradient threshold, which is calculated from the maximum scanning speed of the objective lens, the scanning length of the exposure field, and the minimum exposure time. The calculation formula is:

[0091]

[0092] In the formula, 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 at the maximum illuminance), which can be calculated from the exposure field dose and the illuminance information of different exposure levels.

[0093] It should be noted that in the above embodiments, the first gradient value only needs to be compared with one of the first gradient threshold and the second gradient threshold. Those skilled in the art can understand that the scanning exposure time of the exposure device for each exposure field mainly depends on the time required for each exposure level when scanning and exposing this exposure field, the scanning exposure time corresponding to the maximum scanning speed of the workpiece table, 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 level, and the general selection principle of the scanning time of the exposure level is as follows: select the exposure time of the exposure level with the smallest exposure time; the selected exposure level time is greater than or equal to the scanning exposure time corresponding to the maximum scanning speed of the workpiece table; the selected exposure level time is greater than or equal to the scanning exposure time corresponding to the maximum scanning speed of the objective lens. The main problem currently restricting the yield improvement 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 table, and is greater than the ideal exposure level time; moreover, 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 level times. Therefore, in this embodiment, by comparing the gradient value with the gradient threshold and through subsequent optimization schemes, the scanning exposure time corresponding to the maximum scanning speed of the objective lens is made less than or equal to the scanning exposure time corresponding to the maximum scanning speed of the workpiece table or less than or equal to the ideal exposure level 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 table or the ideal exposure level time does not change due to the change of the exposure field, which not only improves the yield but also avoids overexposure or underexposure phenomena caused by the adjustment of the exposure level.

[0094] As a preferred embodiment, the gradient value further includes a second gradient value, which is calculated from the first gradient values at two adjacent moments and the corresponding position data of the workpiece table 1. The calculation formula is:

[0095]

[0096] 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 table 1.

[0097] Correspondingly, the gradient threshold further includes a third gradient threshold, which is calculated from the maximum scanning speed of the objective lens, the maximum scanning speed of the workpiece table, the maximum scanning acceleration of the objective lens, and the maximum scanning acceleration of the workpiece table. The calculation formula is:

[0098]

[0099] In the formula, TH3 is the third gradient threshold; amax_PO is the maximum scanning acceleration of the objective lens; a max_WS is the maximum scanning acceleration of the worktable; V max_PO is the maximum scanning speed of the objective lens; V max_WS is the maximum scanning speed of the worktable.

[0100] It should be noted that the first gradient value is the primary gradient, that is, it considers the limitation of the maximum scanning speed of the objective lens on the scanning exposure time; the second gradient value is the secondary gradient, that is, it considers the limitation of the maximum scanning acceleration of the objective lens on the scanning exposure time. 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 requirements of the scanning speed of the objective lens. Therefore, considering 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, so as to ensure that the scanning exposure time corresponding to the maximum scanning speed of the objective lens is less than or equal to the scanning exposure time corresponding to the maximum scanning speed of the worktable or less than or equal to the ideal exposure gear time.

[0101] Step S42: If the gradient value is greater than the gradient threshold, smooth the objective lens adjustment amount at this moment to obtain the smoothed objective lens adjustment amount, and then calculate the 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;

[0102] If the gradient value is less than or equal to the gradient threshold, do not process the objective lens adjustment amount at this moment.

[0103] It should be noted that the smoothing process needs to traverse the objective lens adjustment amounts at all moments from the exposure start point to the exposure end point of the exposure field. Among them, the objective lens adjustment amount at any moment corresponds to the position data of the corresponding worktable 1.

[0104] When the gradient value is greater than the gradient threshold, that is, in the foregoing embodiment, or or at this time, 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. The calculation formula is:

[0105]

[0106] In the formula, z new(i) is the smoothed objective lens adjustment amount; z(i) is the objective lens adjustment amount at any moment.

[0107] In another 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 amounts at multiple adjacent moments. The calculation formula is as follows:

[0108] z new(i) = A2·z(i + 2)+A1·z(i + 1)+A0·z(i)+B1·z(i - 1)+B2·z(i - 2)

[0109] 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 weighting factors (which can be obtained through experiments). In this embodiment, the sliding window 8 includes the objective lens adjustment amount at this moment, as well as the objective lens adjustment amounts at the two previous moments and the two subsequent moments. By expanding the range of the sliding window 8 to cover more measurement points, the overall smoothing of the objective lens adjustment amount during this period 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 it according to the actual situation.

[0110] The smoothed objective lens adjustment amount can be smoothed by one of the above two formulas, and then steps S41 and S42 are repeated until the gradient value is less than or equal to the gradient threshold, that is or or At this time, the repetition ends, and the smoothed objective lens adjustment amount is output as the objective lens adjustment amount for fitting the second coefficient.

[0111] When the gradient value is less than or equal to the gradient threshold, that is or or At this time, the objective lens adjustment amount is directly output as the objective lens adjustment amount for fitting the second coefficient.

[0112] In step S4, the gradient value and the gradient threshold are calculated by the calculation unit; comparing the gradient value and the gradient threshold, and outputting the objective lens adjustment amount are performed by the control unit.

[0113] Step S5: Fit the first coefficient based on the stage adjustment amount, and fit the second coefficient based on the smoothed objective lens adjustment amount.

[0114] It should be noted that in this embodiment, the stage adjustment amount obtained in step S3 is fitted to obtain the first coefficient through Legendre or other orthogonal polynomials; the smoothed objective lens adjustment amount obtained in step S4 is fitted to obtain the second coefficient through Legendre or other orthogonal polynomials.

[0115] In step S5, fitting the first coefficient and the second coefficient are calculated by the calculation unit.

[0116] Step S6: During scanning exposure, calculate the real-time workpiece stage adjustment amount based on the first coefficient, calculate the real-time objective lens adjustment amount based on the second coefficient, and respectively control the movement of the workpiece stage drive subunit and the objective lens drive subunit accordingly.

[0117] As an alternative embodiment, the calculation formula for the real-time adjustment amount is as follows:

[0118] dz i (y) = C 0i ·f 0 (y) + C 1i ·f 1 (y) + C 2i ·f 2 (y) + … + C ni ·f n (y)

[0119] 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 the Legendre or other orthogonal polynomial basis function; C ji is the first coefficient or the second coefficient successively fitted at different times.

[0120] In step S6, the real-time workpiece stage adjustment amount and the real-time objective lens adjustment amount are calculated by the calculation unit; the instruction to control the movement of the drive unit based on the real-time adjustment amount is issued by the control unit.

[0121] In summary, in the exposure device provided in the embodiment of the present invention, it includes: a workpiece stage for carrying a substrate; a mask stage for carrying a mask; an optical unit including a light source and a lens group, the light source is arranged on the side of the mask stage away from the workpiece stage; the lens group is composed of multiple objective lenses and is arranged between the mask stage and the workpiece stage along the axis of the exposure device for performing exposure compensation on the substrate and / or the mask; a drive unit for driving the objective lens and / or the workpiece stage to move; a measurement unit for measuring the surface shape data of the substrate and / or the mask; a control unit communicatively connected to the measurement unit and the drive unit; the control unit is configured to, before scanning exposure, based on the surface shape data of the substrate and / or the mask, form a workpiece stage movement trajectory and / or an objective lens movement trajectory, and perform smoothing processing on the objective lens movement trajectory to form a smoothed objective lens movement trajectory, so that the objective lens movement time matches the workpiece stage movement time or the exposure gear switching time; during scanning exposure, based on the workpiece stage movement trajectory and / or the smoothed objective lens movement trajectory, send a movement instruction to the drive unit.

[0122] With such a configuration, the control unit and the calculation unit optimize the movement trajectory of the objective lens based on the measured surface shape data, so that the movement time of the objective lens matches the movement time of the worktable. In this way, the scanning exposure time of the exposure device is no longer limited by the movement time of the objective lens, thereby improving the productivity of the exposure device; also, since the scanning exposure time corresponding to the maximum movement speed of the worktable does not change due to the adjustment of the exposure level, it also avoids overexposure or underexposure of the exposure field caused by the adjustment of the exposure level, improving the yield of the product.

[0123] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. An exposure device, characterized in that: include: A workpiece table, used for carrying a substrate; A mask stage, used for carrying a mask; Optical unit, including light source and mirror assembly, The light source is arranged on a side of the mask stage away from the workpiece stage; The lens group is composed of a plurality of objective lenses, and is disposed between the mask stage and the workpiece stage, and is used to compensate for the exposure of the substrate and / or the mask; A driving unit, used for driving the objective lens and / or the workpiece stage to move; A measuring unit, used for measuring surface data of the substrate and / or the mask; A control unit, connected in communication with the measuring unit and the driving unit; The control unit is configured to, before scanning exposure, generate a workpiece stage adjustment amount and an objective lens adjustment amount based on the surface data of the substrate and / or the mask to form a workpiece stage motion trajectory and / or an objective lens motion trajectory, 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, send a motion instruction to the drive unit based on the workpiece stage motion trajectory and / or the smoothed objective lens motion trajectory.

2. The exposure device according to claim 1, characterized in that The exposure device also includes: A computing unit, communicatively connected to the control unit; The calculation unit is configured to, when smoothing the objective lens motion trajectory, calculate a gradient value based on the surface shape data of the substrate at any moment measured by the measurement unit and the corresponding objective lens adjustment amount, and compare it with a gradient threshold to determine whether to adjust the objective lens adjustment amount at that moment.

3. The exposure device according to claim 2, characterized in that If the gradient value is greater than the gradient threshold, the calculation unit performs smoothing on the objective lens adjustment amount, calculates 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, and outputs the smoothed objective lens adjustment amount; If the gradient value is less than or equal to the gradient threshold, the calculation unit outputs the objective lens adjustment amount.

4. The exposure device according to claim 1, characterized in that The control unit is further configured to, based on the objective lens adjustment amount, perform smoothing processing on the objective lens motion trajectory to generate a smoothed objective lens adjustment amount, and based on the smoothed objective lens adjustment amount, generate a smoothed objective lens motion trajectory; At the same time, a first coefficient is generated based on the workpiece stage adjustment amount, and a second coefficient is generated based on the smoothed objective lens adjustment amount.

5. The exposure device according to claim 4, characterized in that The exposure device also includes: A computing unit, communicatively connected to the control unit; The calculation unit is configured to calculate the real-time workpiece stage adjustment amount based on the first coefficient and calculate the real-time objective lens adjustment amount based on the second coefficient during scanning exposure.

6. The exposure device according to claim 5, characterized in that The driving unit comprises: A workpiece stage driving subunit, used for driving the workpiece stage to drive the substrate to move; An objective lens driving subunit, used for driving the objective lens to move; The motion instructions include substrate motion instructions and objective lens motion instructions; The control unit is further configured to send the substrate movement instruction to the workpiece stage driving subunit based on the real-time workpiece stage adjustment amount; and send the objective lens movement instruction to the objective lens driving subunit based on the real-time objective lens adjustment amount.

7. The exposure device according to claim 1, characterized in that The exposure device also includes: A computing unit, communicatively connected to the control unit; The calculation unit is configured to, based on the surface data of the substrate and / or the mask, use the static field of view of the objective lens as a sliding window, perform plane fitting on the surface data within a single sliding window that slides from the exposure start moment to the exposure end moment in the exposure field, and respectively form the workpiece stage adjustment amount and the objective lens adjustment amount.

8. The exposure device according to claim 1, characterized in that The control unit is further configured to pre-process the surface shape data of the substrate and / or the mask before generating the workpiece stage adjustment amount and the objective lens adjustment amount.

9. The exposure device according to claim 1, characterized in that The objective lens comprises: A first movable lens is arranged close to the mask stage and is used to compensate for the local surface high-order quantity of the mask; The second movable lens is arranged close to the workpiece stage and is used to compensate for the local surface high-order quantity of the substrate.

10. The exposure device according to claim 1, characterized in that The lens group is composed of two columns of objective lens units, each of which includes a plurality of objective lenses, and the measuring unit is arranged between the two columns of objective lens units; wherein the measuring unit includes: A mask measurement subunit, disposed close to the mask stage and used for measuring surface data of the mask; The substrate measurement subunit is disposed close to the workpiece stage and arranged along the axial direction of the exposure device together with the mask measurement subunit, and is used for measuring the surface data of the substrate.

11. The exposure device according to claim 1, characterized in that The exposure device also includes: A vertical monitoring unit is used to monitor the vertical position of the mask stage and / or the workpiece stage.

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