Method and device for improving exposure effect

Abstract

The present invention discloses a method for improving exposure effect, comprising: placing a silicon wafer on a chuck table, the chuck table having an air channel and the lower surface of the silicon wafer covering the air channel, wherein a mask is placed above the chuck table and does not contact the silicon wafer; vacuuming the air channel so that the silicon wafer is adsorbed on the chuck table; leveling and aligning the silicon wafer and the mask; moving the chuck table upwards by a vertical motion component until the nominal gap between the silicon wafer and the mask is close to or equal to 0, and the value of the nominal gap depends on the accuracy of the vertical motion component; releasing the vacuum of the air channel so that the silicon wafer and the mask fit more closely, wherein vacuuming the air channel and releasing the vacuum of the air channel are both controlled by a single electromagnetic valve; exposing the silicon wafer and the mask; vacuuming the air channel after the exposure is completed and waiting for a preset time period; and moving the chuck table downwards by a vertical motion component to separate the silicon wafer and the mask. Also disclosed is an associated device for improving exposure effect.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method and a device for improving exposure effect. Background Art

[0002] Line width resolution and consistency are important indicators of lithography machines. When a lithography machine exposes a mask and a silicon wafer, it is expected that the line width (i.e., line width) obtained by exposure has good resolution and consistency. The thinner the line width, the higher the resolution, the more lines can be integrated in the same area, and the higher the performance of the lithography equipment. At the same time, it is expected that the consistency of the line width is high enough, that is, the line widths obtained by exposure at different positions on the same silicon wafer are equal, so that the reliability of the lithography equipment is also higher.

[0003] The gap between the mask and the silicon wafer in a near-contact lithography machine affects the resolution and consistency of the exposure line width. From theoretical analysis, it can be seen that the larger the gap between the mask and the silicon wafer, the wider the exposed line, that is, the lower the line width resolution. In addition, if the gap consistency between the silicon wafer and the mask is poor (the gap at different positions is inconsistent), the line width after exposure will be unequal. In order to ensure good line width resolution and consistency, it is expected that the silicon wafer and the mask fit tightly during exposure so that there is no gap between the two at different positions (or the gap is small enough) to improve the line width resolution and consistency, thereby improving the exposure effect.

[0004] In the conventional exposure process, the silicon wafer remains adsorbed on the chuck table during exposure, which causes the silicon wafer and the mask to not fit tightly enough, thus affecting the line width resolution and consistency, and further affecting the exposure effect.

[0005] In view of this, it is desirable to provide a method and device for improving exposure effect. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or decisive elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a preface to a more detailed description given later. The scope of the present invention is defined by the attached claims and their equivalent technical solutions.

[0007] The present invention provides a method for improving exposure effect, comprising: placing a silicon wafer on a chuck table, wherein the chuck table has an air channel and the lower surface of the silicon wafer covers the air channel, and wherein a mask plate is placed above the chuck table and does not contact the silicon wafer; evacuating the air channel so that the silicon wafer is adsorbed on the chuck table; leveling and aligning the silicon wafer and the mask plate; moving the chuck table upwards by a vertical motion component until a nominal gap between the silicon wafer and the mask plate is close to or equal to 0, and the value of the nominal gap depends on the accuracy of the vertical motion component; releasing the vacuum of the air channel so that the silicon wafer and the mask plate fit more closely, wherein evacuating the air channel and releasing the vacuum of the air channel are both controlled by a single electromagnetic valve; exposing the silicon wafer and the mask plate; evacuating the air channel after the exposure is completed and waiting for a preset time period; and moving the chuck table downwards by the vertical motion component to separate the silicon wafer and the mask plate.

[0008] In some embodiments, leveling the silicon wafer and the mask is achieved by a passive leveling component or an active leveling component.

[0009] In some embodiments, when the nominal gap between the silicon wafer and the mask is 0, the actual gap between at least a portion of the silicon wafer and the mask is greater than 0.

[0010] In some embodiments, leveling and aligning the silicon wafer and the mask further includes: raising the chuck table until the silicon wafer and the mask are in contact; leveling the silicon wafer and the mask; lowering the chuck table by a preset distance so that the silicon wafer and the mask are no longer in contact; and aligning the silicon wafer and the mask.

[0011] In some embodiments, the method further includes: after releasing the vacuum of the gas channel, filling the gas into the gas channel so that the gas flows from the gas channel to the lower surface of the silicon wafer.

[0012] In some embodiments, the gas includes air, nitrogen, or other inert gases.

[0013] In some embodiments, insufflation of gas into the airway is controlled by a single solenoid valve.

[0014] In some embodiments, the method further comprises: controlling the pressure and flow rate of the gas when inflating the airway with the gas so that the pressure is within a preset pressure range and the flow rate is within a preset flow rate range.

[0015] The present invention also provides a device for improving exposure effect, comprising: a chuck stage, the chuck stage having an air channel, wherein a silicon wafer is placed on the chuck stage and the lower surface of the silicon wafer covers the air channel, and wherein a mask is placed above the chuck stage and does not contact the silicon wafer; a single solenoid valve, which is used to evacuate the air channel of the chuck stage, release the vacuum of the air channel, or fill the air channel with gas; a leveling and alignment unit, which is used to level and align the silicon wafer and the mask; a Z-axis assembly, which is used to drive the chuck stage to move up and down; and a control unit, which is configured to: control the single solenoid valve to evacuate the air channel, release the vacuum of the air channel, or fill the air channel with gas. The control unit is configured to: vacuum the airway to allow the silicon wafer to be adsorbed on the chuck table; control the leveling and alignment unit to level and align the silicon wafer and the mask; control the Z-axis assembly to move upward so that the nominal gap between the silicon wafer and the mask is close to or equal to 0, and the value of the nominal gap depends on the accuracy of the Z-axis assembly; control a single solenoid valve to release the vacuum of the airway to allow the silicon wafer and the mask to fit more closely; and an exposure unit, which is used to expose the silicon wafer and the mask; wherein the control unit is further configured to: control the single solenoid valve to vacuum the airway after the exposure is completed and wait for a preset time period; and control the Z-axis assembly to move downward to separate the silicon wafer and the mask.

[0016] In some embodiments, the leveling and alignment unit includes an adaptive passive leveling component, which includes a locking member and a sensor. The leveling and alignment unit is further configured to: enable the Z-axis component to drive the chuck table to rise so that the gap between the silicon wafer and the mask plate continues to decrease until they are in contact; enable the Z-axis component to drive the chuck table to continue to rise, and the adaptive passive leveling component is compressed downward until the sensor is triggered, the Z-axis component stops moving and the locking member locks the adaptive passive leveling component to complete the leveling of the silicon wafer and the mask plate; enable the Z-axis component to drive the chuck table to descend; and when it is detected that the chuck table has descended a preset distance and the silicon wafer and the mask plate are no longer in contact, align the silicon wafer and the mask plate.

[0017] In some embodiments, when the chuck table rises until the silicon wafer and the mask plate are in contact, the adaptive passive leveling component levels the silicon wafer and the mask plate through compression and posture change; and when the sensor detects that the adaptive passive leveling component has been compressed to a preset degree, the Z-axis assembly stops moving, and the locking member is controlled to lock the adaptive passive leveling component so that the adaptive passive leveling component maintains the current posture.

[0018] In some embodiments, the adaptive passive leveling assembly further includes a decoupling ball, a guide post, and a gravity compensation spring, wherein the guide post is disposed under the chuck table and is capable of compressing the adaptive passive leveling assembly by moving up and down; and wherein the decoupling ball is disposed between the guide post and the upper chuck table to prevent the adaptive passive leveling assembly from getting stuck when the posture changes, and wherein the gravity compensation spring has a preset adaptive leveling force to prevent damage to the silicon wafer due to leveling or exposure.

[0019] In some embodiments, the leveling and alignment unit comprises an active leveling assembly.

[0020] In some embodiments, when the nominal gap between the silicon wafer and the mask is 0, the actual gap between at least a portion of the silicon wafer and the mask is greater than 0.

[0021] In some embodiments, the control unit is further configured to: after releasing the vacuum of the air channel, control the single solenoid valve to fill the air channel with gas so that the gas flows from the air channel to the lower surface of the silicon wafer.

[0022] In some embodiments, the gas includes air, nitrogen, or other inert gases.

[0023] In some embodiments, the device further includes a pressure regulating valve and a throttle valve, wherein the pressure regulating valve is used to control the pressure of the gas when the gas is filled into the airway so that the pressure is within a preset pressure range, and the throttle valve is used to control the flow rate of the gas when the gas is filled into the airway so that the flow rate is within a preset flow range.

[0024] The technical solution of the present invention firstly levels the silicon wafer and the mask plate through a leveling component, and then releases the vacuum of the chuck stage airway to prevent the silicon wafer from being adsorbed on the chuck stage, thereby making the silicon wafer and the mask plate fit more closely, thereby improving the exposure effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The features, nature and advantages of the present invention will become more apparent when the detailed description set forth below is understood in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals are always used for corresponding identification. It should be noted that the drawings described are only schematic and non-limiting. In the drawings, the sizes of some components may be exaggerated and are not drawn to scale for illustrative purposes.

[0026] Figure 1 A schematic diagram showing the exposure principle of a photolithography device is shown.

[0027] Figure 2 A method for improving exposure effect according to an embodiment of the present invention is shown.

[0028] Figure 3 A schematic diagram showing the parallelism of the silicon wafer and the mask under microscopic conditions.

[0029] Figure 4 A schematic structural diagram of an adaptive passive leveling assembly according to an embodiment of the present invention is shown.

[0030] Figure 5 An exemplary process for improving exposure effect according to an embodiment of the present invention is shown.

[0031] Figure 6 A schematic block diagram of a device for improving exposure effect according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. In the following detailed description, many specific details are set forth to provide a thorough understanding of the described exemplary embodiments. However, it is obvious to those skilled in the art that the described embodiments can be practiced without some or all of these specific details. In other exemplary embodiments, well-known structures are not described in detail to avoid unnecessarily obscuring the concepts of the present disclosure. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. At the same time, in the absence of conflict, the various aspects described in the embodiments can be combined arbitrarily.

[0033] Figure 1 A schematic diagram showing the exposure principle of a photolithography device is shown.

[0034] like Figure 1 As shown, the mask is placed above the silicon wafer, and the exposure light source of the lithography equipment is placed above the mask.

[0035] During exposure, the exposure light source emits light (eg, ultraviolet light), which is projected onto the photoresist on the surface of the silicon wafer through the pattern on the mask, thereby transferring the pattern on the mask to the silicon wafer.

[0036] As shown in the figure, there is a certain gap (also called exposure gap) between the lower surface of the mask and the upper surface of the silicon wafer. As mentioned above, the existence of this gap will affect the exposure effect.

[0037] Specifically, the size of the gap affects the line width resolution after exposure. The larger the gap, the lower the line width resolution, and the smaller the gap, the higher the line width resolution. At the same time, the consistency of the gap at different positions will affect the line width consistency. The higher the gap consistency at different positions (the smaller the gap difference), the higher the line width consistency, and the lower the gap consistency (the larger the gap difference), the lower the line width consistency. In order to improve the exposure effect, it is hoped to improve the line width resolution and line width consistency. Therefore, it is expected that the silicon wafer and the mask template are closely fitted to eliminate or reduce the gap, and at the same time it is expected to reduce the gap difference at different positions.

[0038] Figure 2 A method 200 for improving exposure effect according to an embodiment of the present invention is shown.

[0039] like Figure 2 As shown, the method 200 starts at step 205. At step 205, a silicon wafer is placed on a chuck stage, the chuck stage has an air channel and the lower surface of the silicon wafer covers the air channel, and wherein a mask is placed above the chuck stage and does not contact the silicon wafer.

[0040] The chuck table is an important component used in the fields of semiconductor manufacturing, etc. In the semiconductor field, the chuck table is used to transfer and fix silicon wafers to ensure stability during the working process.

[0041] In some embodiments, the chuck has one or more air channels and the silicon wafer can cover all of the air channels. Each of the air channels is interconnected.

[0042] The air passages can be evenly distributed or unevenly distributed on the chuck table. One end opening of the air passage can be arranged on the upper surface of the chuck table, and the other end opening of the air passage can be connected to an external air, positive pressure or vacuum air source.

[0043] In step 210, the airway is evacuated to allow the silicon wafer to be attached to the chuck.

[0044] In some embodiments, the airway may be evacuated via a single solenoid valve.

[0045] Since the air channels of the chuck table are interconnected, any of the air channels can be connected to a single solenoid valve to evacuate the air channel through the single solenoid valve. In this way, all the air channels covered by the silicon wafer can be quickly placed in a vacuum state by controlling a single solenoid valve.

[0046] By vacuuming, a vacuum environment can be formed between the lower surface of the silicon wafer and the upper surface of the chuck table, so that the silicon wafer is tightly adsorbed on the chuck table.

[0047] In step 215, the silicon wafer and the mask are leveled and aligned.

[0048] In some embodiments, leveling and aligning the silicon wafer and the mask may include first leveling the silicon wafer and the mask when the silicon wafer and the mask are in contact, and then aligning the silicon wafer and the mask when the silicon wafer and the mask are no longer in contact.

[0049] Specifically, the chuck stage can first be raised until the silicon wafer and the mask are in contact, then the chuck stage can be further raised to level the silicon wafer and the mask, after leveling the chuck stage can be lowered a preset distance so that the silicon wafer and the mask are no longer in contact, and then the silicon wafer and the mask are aligned.

[0050] For example, the following combination Figure 4 The Z-axis assembly shown is used to drive the chuck stage to move up and down. By moving the Z-axis assembly upward, the chuck stage can be driven to rise, so that the silicon wafer continues to approach the mask plate until it contacts the mask plate. By moving the Z-axis assembly downward, the chuck can be driven to descend until the silicon wafer and the mask plate are no longer in contact.

[0051] When the silicon wafer and the mask are in contact, the silicon wafer and the mask can be leveled. In a specific implementation, the leveling of the silicon wafer and the mask can be achieved by a passive leveling component or an active leveling component.

[0052] After the leveling is completed, the silicon wafer and the mask can be aligned. Before executing the alignment process, the chuck table can be lowered by a preset distance so that the silicon wafer and the mask are no longer in contact, and the silicon wafer and the mask are aligned without contact. In this way, damage to the silicon wafer and the mask during the alignment process can be avoided. In a specific implementation, any appropriate alignment technology (for example, geometric imaging alignment technology, interference light intensity alignment technology, moiré fringe alignment technology, coaxial alignment technology, etc.) can be used to achieve alignment between the silicon wafer and the mask.

[0053] After completing the leveling and alignment of the silicon wafer and the mask, the method 200 proceeds to step 220. In step 220, the chuck stage is moved upward by the vertical motion assembly until the nominal gap between the silicon wafer and the mask is close to or equal to 0, and the value of the nominal gap depends on the accuracy of the vertical motion assembly.

[0054] In some embodiments, the vertical motion assembly can be a combination of the following Figure 4 Z-axis assembly as described.

[0055] Ideally, the vertical motion assembly has high enough precision to move the chuck stage upward by a specific upward distance until the nominal gap between the wafer and the mask is equal to 0, and the wafer and the mask are macroscopically aligned.

[0056] However, in practice, the accuracy of the vertical motion component may not be high enough, resulting in a certain error in the moving distance. In such cases, when the vertical motion component moves the chuck stage upward until the nominal gap between the silicon wafer and the mask is equal to 0, the silicon wafer and the mask are not yet macroscopically attached. To this end, the vertical motion component can be moved upward for a certain distance (for example, 2um) so that the nominal gap between the silicon wafer and the mask is equal to -2 um. In this way, the error caused by the accuracy of the vertical motion component can be offset, so that the silicon wafer and the mask are macroscopically attached. In a specific implementation, the value of the nominal gap between the silicon wafer and the mask can be determined according to the accuracy of the vertical motion component. For example, if the accuracy of the vertical motion component is high enough, the value of the nominal gap can be 0. If the accuracy of the vertical motion component is not high enough, the value of the nominal gap can be close to but less than 0 (for example, -1 um, -2 um, etc.). By raising the silicon wafer until it contacts the mask, the exposure gap can be reduced compared to the situation where the two are not in contact. However, due to the surface flatness error of the silicon wafer and the mask, although the silicon wafer and the mask are nominally fitted on a macroscopic level, there is still a gap between them on a microscopic level. Therefore, when the nominal gap between the silicon wafer and the mask is 0, the actual gap between the two is not 0. Specifically, if the accuracy of the vertical motion component is high enough, then when the nominal gap between the silicon wafer and the mask is 0, the actual gap between a portion of the silicon wafer and the mask is 0 and the actual gap in the remaining areas is greater than 0. In other words, at this time, a portion of the area between the two is tightly fitted, while other areas are not yet tightly fitted. If the accuracy of the vertical motion component is not high enough, then when the nominal gap between the silicon wafer and the mask is 0, the silicon wafer and the mask are not yet fitted on a macroscopic level, and the actual gaps in all areas between the silicon wafer and the mask are greater than 0.

[0057] For ease of explanation, Figure 3 A schematic diagram of the parallelism of the silicon wafer and the mask at a microscopic level is shown. For simplicity, it is assumed that the accuracy of the vertical motion component is high enough. That is, when the nominal gap between the silicon wafer and the mask is 0, the two fit together at a macroscopic level.

[0058] In practice, both the silicon wafer and the mask have flatness errors, so that the surfaces of the silicon wafer and the mask are not completely flat. Figure 3 As shown in the upper part, both the silicon wafer and the mask have a certain degree of warping under the microscopic view.

[0059] Therefore, when the nominal gap between the silicon wafer and the mask is 0, since the surfaces of the silicon wafer and the mask are not completely flat, the silicon wafer and the mask are not tightly fitted at the microscopic level, and there is still a gap between the two.

[0060] like Figure 3As shown in the middle of the figure, when the nominal gap between the silicon wafer and the mask is 0, a part of the area between the silicon wafer and the mask is tightly fitted without gap (that is, the actual gap is 0), while the rest of the area is not tightly fitted, but has a certain gap (that is, the actual gap is greater than 0). The existence of areas with actual gaps greater than 0 and the inconsistency of actual gaps in different areas will affect the exposure line width resolution and consistency, thereby affecting the exposure effect.

[0061] return Figure 2 In step 225, the vacuum of the air channel is released to make the silicon wafer and the mask plate fit more closely, wherein the vacuuming of the air channel and the release of the vacuum of the air channel are both controlled by a single solenoid valve.

[0062] After the vacuum in the chuck airway is released, the vacuum environment between the lower surface of the silicon wafer and the upper surface of the chuck is destroyed, and the silicon wafer changes from being attached to the chuck to being free, resulting in a certain degree of upward warping. As a result, the silicon wafer and the mask will fit more closely.

[0063] Combination Figure 3 As shown in the lower part of , after the vacuum of the airway is released, gas exists between the upper surface of the chuck table and the lower surface of the silicon wafer, the lower surface of the silicon wafer is no longer tightly adsorbed on the chuck table, and the silicon wafer warps upward, thereby fitting closely with the mask.

[0064] In the most ideal case, after the vacuum of the airway is released, the actual gap between the silicon wafer and the mask in all areas is 0, that is, all areas between the two are tightly fitted and there is no gap, such as Figure 3 As shown in the lower part of . Under normal (non-ideal) conditions, after releasing the vacuum in the airway, there are still some areas between the silicon wafer and the mask where the actual gap is greater than 0, but the area with the actual gap greater than 0 is reduced compared to the area without releasing the vacuum, and the actual gap size is smaller than that without releasing the vacuum. It can be seen that releasing the vacuum in the airway can eliminate or reduce the actual gap and improve the consistency of the gap at different positions.

[0065] In some embodiments, in order to further improve the degree of adhesion between the silicon wafer and the mask, after releasing the vacuum, gas can be filled into the air channel to make the gas flow from the air channel to the lower surface of the silicon wafer. In such a case, the silicon wafer is subjected to upward gas pressure, so that the silicon wafer and the mask are more closely attached.

[0066] In some examples, air can be filled into the airway. In other examples, nitrogen can be filled into the airway. Nitrogen is an inert gas, which is not easy to react and does not easily affect the exposure results. At the same time, nitrogen has a high content in the atmosphere, is easy to obtain, and is cost-effective. In other examples, other inert gases besides nitrogen can be filled into the airway. In specific implementations, those skilled in the art can select a suitable gas to be filled into the airway according to actual conditions.

[0067] In some embodiments, evacuating the airway, releasing the vacuum of the airway, and filling the airway with gas can all be controlled by a single solenoid valve. In this way, all airways can be controlled by a single solenoid valve, thereby simplifying the control process and improving exposure efficiency.

[0068] When the airway is inflated with gas, the pressure and flow rate of the gas may also be controlled so that the pressure is within a preset pressure range and the flow rate is within a preset flow rate range.

[0069] If the gas pressure and flow rate are too small, the exposure effect may be limited. If the gas pressure and flow rate are too large, it may cause microscopic silicon wafer slippage, which will have an adverse effect on overlay (another indicator of exposure). Therefore, it is necessary to control the gas pressure and flow rate to keep them within a suitable range. In specific implementations, those skilled in the art can set a suitable pressure range and flow rate range according to actual conditions.

[0070] In some embodiments, the pressure of the gas can be controlled by a pressure regulating valve so as to be within a preset pressure range. At the same time, the flow rate of the gas can be controlled by a throttle valve so as to be within a preset flow rate range. In this way, the silicon wafer and the mask can be more closely attached to improve the exposure effect, while preventing the silicon wafer from slipping.

[0071] In step 230, the silicon wafer and the mask are exposed.

[0072] Through the above steps 205-225, the silicon wafer and the mask have been leveled and aligned, and the two are closely attached. In this case, exposing the silicon wafer and the mask can effectively improve the resolution and consistency of the exposure line width, thereby improving the exposure effect.

[0073] When leveling the silicon wafer and the mask, passive leveling or active leveling can be used. For example, the silicon wafer and the mask can be leveled by a passive leveling component or an active leveling component. Active leveling components usually use a large number of sensors and drive transmission devices, and the structure is relatively large and expensive. Therefore, the use of active leveling components will increase the cost of the lithography machine. In view of this, the present invention proposes an adaptive passive leveling component.

[0074] Accordingly, Figure 4A schematic structural diagram of an adaptive passive leveling assembly according to an embodiment of the present invention is shown.

[0075] As shown in the figure, the adaptive passive leveling assembly includes a decoupling ball, a guide column, a locking member, a proximity sensor, and a gravity compensation spring. For ease of understanding, Figure 4 Also shown in the figure are a mask, a silicon wafer, a chuck stage, and a Z-axis assembly associated with an adaptive passive leveling assembly. The mask is placed above the silicon wafer and does not contact the silicon wafer. The silicon wafer is placed on a chuck stage, which has multiple air channels.

[0076] Figure 4 A single solenoid valve connected to the airway is shown in FIG. In addition, the solenoid valve can be further connected to a PLC (Programmable Logic Controller). The PLC can control the opening and closing of the solenoid valve, thereby controlling the air usage of the airway.

[0077] The adaptive passive leveling assembly is arranged under the chuck table and mechanically connected to the chuck table, and the Z-axis assembly is arranged under the adaptive passive leveling assembly and mechanically connected to the adaptive passive leveling assembly. When the Z-axis assembly moves up and down, the adaptive passive leveling assembly and the chuck table can be driven to move up and down together with the Z-axis assembly.

[0078] The decoupling ball is disposed between the guide post and the chuck stage. In some examples, the decoupling ball can be pivotally connected to the chuck stage and the guide post. The decoupling ball is used to prevent the adaptive passive leveling assembly from getting stuck when the posture changes. In alternative implementations, other structures (e.g., flexible members) can also be used to prevent the adaptive passive leveling assembly from getting stuck.

[0079] The guide post is disposed below the chuck table. In some embodiments, the guide post can compress the height of the adaptive passive leveling assembly by moving up and down. By way of example and not limitation, Figure 4 Three guide posts and three decoupling balls are shown in FIG. As shown in the figure, when the silicon wafer and the mask are leveled, each guide post can move up and down, thereby compressing the adaptive passive leveling component. At the same time, different guide posts can move different distances, thereby causing the adaptive passive leveling component to change its posture.

[0080] The gravity compensation spring has a preset adaptive leveling force to prevent damage to the silicon wafer caused by leveling or exposure. In some embodiments, the adaptive leveling force of the gravity compensation spring is about 8N. In a specific implementation, those skilled in the art can set the adaptive leveling force of the gravity compensation spring according to actual conditions.

[0081] Before leveling, the silicon wafer is not in contact with the mask. When the Z-axis assembly moves upward, the chuck stage rises, causing the silicon wafer adsorbed on the chuck stage to rise together and approach the mask. When the chuck stage rises until the silicon wafer contacts the mask, the adaptive passive leveling assembly is triggered to level the silicon wafer and the mask.

[0082] Specifically, when the silicon wafer just contacts the mask, the contact area between the silicon wafer and the mask is small because the silicon wafer and the mask are not parallel (for example, the chuck stage is not parallel to the mask). As the Z-axis assembly continues to rise, the adaptive passive leveling assembly begins to compress and the attitude pitch changes. Finally, the silicon wafer and the mask are fully in contact and adjusted to be parallel.

[0083] When the adaptive passive leveling assembly is compressed, the proximity sensor can detect the degree of compression (e.g., the distance compressed). When it is detected that the adaptive passive leveling assembly has been compressed to a preset degree (e.g., when compressed to 1 mm), the Z-axis assembly can be stopped. At the same time, the cylinder or motor ( Figure 4 (not shown) to drive the locking member to lock the adaptive passive leveling assembly so that the adaptive passive leveling assembly maintains the current parallel posture. Figure 4 Three locking members are shown, each of which is connected to a guide post. When the locking member is not driven, the guide post can move up and down to change the compression degree and posture of the adaptive passive leveling assembly. When the locking member is driven, the guide post is locked, so that the adaptive passive leveling assembly is no longer compressed and maintains the current posture. At this point, the adaptive leveling of the silicon wafer and the mask is completed.

[0084] It should be noted that the above combination Figure 4 The adaptive passive leveling assembly described is only exemplary and not restrictive. In actual implementation, those skilled in the art may use other methods to implement the adaptive passive leveling assembly. For example, in some examples, gravity compensation members other than gravity compensation springs may be used to achieve gravity compensation. In other examples, compression of the adaptive passive leveling assembly may be achieved by methods other than guide posts. In addition, if the budget and space are sufficient, those skilled in the art may also use active leveling assemblies to achieve leveling of the silicon wafer and the mask.

[0085] return Figure 2 After the exposure is completed, the silicon wafer and the mask need to be separated. Specifically, in step 235, the airway is evacuated after the exposure is completed and a preset time period is waited. After the preset time period has passed, in step 240, the chuck stage is moved downward by the vertical motion assembly to separate the silicon wafer and the mask.

[0086] During the exposure process, the mask and the silicon wafer are closely attached, and both the mask and the silicon wafer are relatively smooth, so intermolecular forces will be formed after the attachment. After the exposure is completed, the chuck stage changes from releasing the vacuum or blowing nitrogen to opening the vacuum, adsorbing the silicon wafer, and driving the silicon wafer downward to separate the silicon wafer and the mask, and lowering it to a certain height.

[0087] However, due to the intermolecular forces between the mask and the silicon wafer, the adsorption is relatively tight. If the chuck stage moves downward immediately after the vacuum is turned on, the "sticking plate" phenomenon is likely to occur (that is, the silicon wafer sticks to the mask), resulting in the chuck stage being unable to adsorb the silicon wafer when it moves downward. For this reason, after the exposure is completed, the chuck stage can first turn off the nitrogen (if nitrogen was blown previously) and turn on the vacuum, and wait for a certain period of time (i.e., delay) in the vacuum state, so that the silicon wafer fits the chuck stage more closely and the intermolecular forces between the mask and the silicon wafer are destroyed, and then the vertical moving component moves downward again. In this way, the "sticking plate" phenomenon can be effectively avoided, and the silicon wafer and the mask can be successfully separated.

[0088] Figure 5 An exemplary process 500 for improving exposure results according to one embodiment of the present invention is shown.

[0089] As shown in the figure, process 500 begins by placing a silicon wafer on a chuck table and turning on vacuum adsorption. For example, a single solenoid valve can be used to evacuate the air passage of the chuck table to turn on vacuum adsorption, so that the silicon wafer is tightly adsorbed on the chuck table.

[0090] Next, the Z-axis assembly rises to drive the passive leveling assembly (e.g. Figure 4 The adaptive passive leveling assembly) and the chuck stage move upward until the silicon wafer contacts the mask. For the sake of explanation, it is assumed that the accuracy of the Z-axis assembly is high enough.

[0091] Subsequently, the Z-axis assembly continues to rise to passively level the silicon wafer and the mask. Specifically, as the Z-axis assembly rises, the passive leveling assembly compresses and changes its posture in pitch to adjust the silicon wafer and the mask to be parallel. When the passive leveling assembly compresses to a preset degree, the proximity sensor triggers and stops the Z-axis assembly from moving, and the passive leveling assembly stops compressing. At the same time, the passive leveling assembly is locked by the locking member to keep its current posture. At this point, the passive leveling of the silicon wafer and the mask is completed.

[0092] After the passive leveling of the silicon wafer and the mask is completed, the Z-axis assembly is lowered so that the silicon wafer and the mask are no longer in contact. Specifically, the Z-axis assembly can be lowered by a preset distance so that the silicon wafer and the mask are no longer in contact.

[0093] Next, the alignment process of the silicon wafer and the mask can be carried out.

[0094] After alignment is completed, the Z-axis assembly rises again until the nominal gap between the silicon wafer and the mask is 0. As mentioned above, when the nominal gap between the silicon wafer and the mask is 0, due to the flatness error of the mask and the silicon wafer, the actual gap between the two is 0 in some areas (i.e., tightly fitted), while the actual gap in some areas is greater than 0 (i.e., not tightly fitted).

[0095] After the Z-axis assembly rises to a nominal gap between the silicon wafer and the mask plate of 0, the air channel of the chuck stage can be released from vacuum. For example, a single solenoid valve can be used to control the air channel of the chuck stage to switch from vacuum adsorption of the silicon wafer to vacuum release. After the vacuum is released, the silicon wafer changes from a state of being attached to the chuck stage to a free state, with a certain range of upward warping, so that the silicon wafer and the mask plate will fit more closely.

[0096] Optionally, after releasing the vacuum, gas (eg, nitrogen) may be charged into the gas channel through a single solenoid valve. When the gas is charged into the gas channel, the silicon wafer is subjected to upward gas pressure, thereby further bonding the silicon wafer and the mask compared to only releasing the vacuum.

[0097] Finally, the silicon wafer and the mask plate can be exposed to transfer the pattern on the mask plate to the silicon wafer. Through process 500, the line width obtained after exposure has high resolution and consistency.

[0098] Figure 6 A schematic block diagram of a device 600 for improving exposure effect according to an embodiment of the present invention is shown.

[0099] See also Figure 6 , showing that the device 600 includes a chuck stage, a single solenoid valve, a leveling and alignment unit, a Z-axis assembly, a control unit, an exposure unit, a pressure regulating valve, and a throttle valve.

[0100] The chuck stage has an air channel, and when a silicon wafer is placed, the silicon wafer is placed on the chuck stage and the lower surface of the silicon wafer covers the air channel of the chuck stage. Meanwhile, a mask is placed above the chuck stage.

[0101] A single solenoid valve is used to evacuate, release, or inflate the chuck station's airway.

[0102] In some embodiments, a single solenoid valve can be connected to the airway of the chuck station to evacuate, release the vacuum, or fill the airway with gas. When filling the airway with gas, the single solenoid valve can also be connected to a gas source.

[0103] The leveling and alignment unit is used to level and align the silicon wafer and the mask.

[0104] In some embodiments, the leveling and alignment unit includes an adaptive passive leveling component, the adaptive passive leveling component includes a locking member and a sensor, and the leveling and alignment unit is further configured to: enable the Z-axis component to drive the chuck table to rise so that the gap between the silicon wafer and the mask plate continues to decrease until they are in contact; enable the Z-axis component to drive the chuck table to continue to rise, the adaptive passive leveling component is compressed downward until the sensor is triggered, the Z-axis component stops moving and the locking member locks the adaptive passive leveling component to complete the leveling of the silicon wafer and the mask plate; enable the Z-axis component to drive the chuck table to descend; and when it is detected that the chuck table has descended a preset distance and the silicon wafer and the mask plate are no longer in contact, align the silicon wafer and the mask plate.

[0105] In some embodiments, the leveling and alignment unit comprises an active leveling assembly.

[0106] The Z-axis assembly is used to drive the chuck table to move up and down.

[0107] The control unit is configured to: control a single solenoid valve to evacuate the airway so that the silicon wafer is adsorbed on the chuck table; control the leveling and alignment unit to level and align the silicon wafer and the mask; control the Z-axis assembly to move upward so that the nominal gap between the silicon wafer and the mask is close to or equal to 0, and the value of the nominal gap depends on the accuracy of the Z-axis assembly; control the single solenoid valve to release the vacuum of the airway so that the silicon wafer and the mask fit more closely.

[0108] In some embodiments, the control unit is further configured to: after releasing the vacuum of the gas channel, control the single solenoid valve to fill the gas into the gas channel so that the gas flows from the gas channel to the lower surface of the silicon wafer.

[0109] The exposure unit is used to expose the silicon wafer and the mask.

[0110] In some embodiments, the control unit is further configured to: control a single solenoid valve to evacuate the airway and wait for a preset period of time after exposure is completed; and control the Z-axis assembly to move downward to separate the silicon wafer and the mask.

[0111] The pressure regulating valve is used to control the pressure of the gas when the gas is charged into the airway so that the pressure is within a preset pressure range, and the throttle valve is used to control the flow of the gas when the gas is charged into the airway so that the flow is within a preset flow range. In a specific implementation, the solenoid valve can be connected in series with the pressure regulating valve and the throttle valve, such as Figure 6 In this way, when the gas is charged into the airway through the solenoid valve, when the gas passes through the solenoid valve and flows through the pressure regulating valve and the throttle valve, the pressure and flow of the gas can be controlled so that the pressure and flow of the gas flowing into the airway are within a preset range.

[0112] Figure 6The interaction between various units / components is shown. For example, the Z-axis assembly interacts with the chuck table to drive the chuck table to move up and down, a single solenoid valve controls the airway of the chuck table, the throttle valve and the pressure regulating valve control the flow and pressure of the gas in the airway, and the control unit controls the operation of various units / components such as the solenoid valve, the Z-axis assembly, the leveling and alignment unit, etc. It should be noted that Figure 6 The interactions shown in are exemplary only and are not intended to be limiting.

[0113] In addition, although Figure 6 Specific units / components of the device 600 for improving exposure effects are shown in FIG. 6 , but it should be understood that these units / components are exemplary and non-limiting. In different implementations, one or more of these units / components may be combined, split, removed, or additional units / components may be added. For example, in some implementations, the pressure regulating valve, the throttle valve, and the control unit may be combined into a single unit. In other implementations, the leveling and alignment unit may be split into a leveling unit and an alignment unit.

[0114] The technical solution of the present invention first ensures that the silicon wafer and the mask are parallel as a whole by leveling, and then releases the vacuum of the chuck table airway or inflates the airway to make the silicon wafer and the mask fit more closely, thereby reducing the actual gap between the silicon wafer and the mask under the microscopic level, thereby improving the resolution and consistency of the exposure line width and improving the exposure effect. At the same time, by controlling the gas use of all airways with a single solenoid valve, the control process can be simplified and the exposure efficiency can be improved. In addition, after the exposure is completed, the silicon wafer and the mask are separated after turning on the vacuum and waiting for a preset time period, which can effectively avoid the "sticky plate" phenomenon. In addition, the present invention proposes an adaptive passive leveling component to achieve the leveling of the silicon wafer and the mask, which simplifies the structure and has a high cost performance compared to the active leveling component.

[0115] The detailed description described above in conjunction with the accompanying drawings describes examples and does not represent all examples that can be implemented or fall within the scope of the claims. The terms "example" and "exemplary" when used in this specification mean "used as an example, instance or illustration" and do not mean "better or better than other examples".

[0116] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, use of these phrases may refer to more than just one embodiment. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0117] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the universal principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but should be granted the full scope consistent with the claims in language, wherein the singular reference to the elements is not intended to mean "there is and only one", but "one or more", unless otherwise specifically stated. Unless otherwise specifically stated, the term "some" refers to one or more. The elements of the various aspects described throughout the present invention are all structurally and functionally equivalent schemes currently or hereafter known to those of ordinary skill in the art and are expressly incorporated herein by reference, and are intended to be covered by the claims.

[0118] It should also be noted that these embodiments may be described as a process depicted as a flow chart, flow diagram, structure diagram, or block diagram. Although the flow chart may describe the operations as sequential processes, many of these operations can be performed in parallel or concurrently. In addition, the order of these operations can be rearranged.

[0119] Although various embodiments have been illustrated and described, it should be understood that the embodiments are not limited to the precise configuration and components described above. Various modifications, substitutions and improvements obvious to those skilled in the art may be made in the arrangement, operation and details of the devices disclosed herein without departing from the scope of the claims.

Claims

1. A method for improving exposure effect, comprising: placing a silicon wafer on a chuck stage, wherein the chuck stage has an air channel and the lower surface of the silicon wafer covers the air channel, and wherein a mask is placed above the chuck stage and does not contact the silicon wafer; evacuating the airway to allow the silicon wafer to adhere to the chuck table; Leveling and aligning the silicon wafer and the mask; After completing the leveling and alignment of the silicon wafer and the mask, the chuck stage is moved upward by a vertical motion component until a nominal gap between the silicon wafer and the mask is close to but not more than 0, wherein the value of the nominal gap depends on the accuracy of the vertical motion component, wherein the higher the accuracy of the vertical motion component, the closer the value of the nominal gap is to 0, and wherein the lower the accuracy of the vertical motion component, the smaller the value of the nominal gap is; Releasing the vacuum of the air channel to make the silicon wafer and the mask plate more closely attached, wherein the vacuuming of the air channel and the release of the vacuum of the air channel are both controlled by a single identical solenoid valve; exposing the silicon wafer and the mask; After the exposure is completed, evacuate the airway and wait for a preset period of time; and The chuck stage is moved downward by the vertical motion assembly to separate the silicon wafer from the mask.

2. The method according to claim 1, wherein: The silicon wafer and the mask are leveled by a passive leveling component or an active leveling component.

3. The method according to claim 1, wherein: When the nominal gap between the silicon wafer and the mask is 0, the actual gap between at least a portion of the silicon wafer and the mask is greater than 0.

4. The method according to claim 1, wherein: Leveling and aligning the silicon wafer and the mask further comprises: Raising the chuck stage until the silicon wafer contacts the mask; Leveling the silicon wafer and the mask; Lowering the chuck stage by a preset distance so that the silicon wafer and the mask are no longer in contact; and The silicon wafer and the mask are aligned.

5. The method according to claim 1, further comprising: After the vacuum of the gas channel is released, gas is filled into the gas channel to make the gas flow from the gas channel to the lower surface of the silicon wafer.

6. The method according to claim 5, wherein: The gas includes air, nitrogen or an inert gas.

7. The method according to claim 5, wherein: Insufflation of the airway with gas is controlled by the single identical solenoid valve.

8. The method according to claim 5, further comprising: When the gas is inflated into the airway, the pressure and flow rate of the gas are controlled so that the pressure is within a preset pressure range and the flow rate is within a preset flow rate range.

9. A device for improving exposure effect, comprising: a chuck stage having an air channel, wherein a silicon wafer is placed on the chuck stage and a lower surface of the silicon wafer covers the air channel, and wherein a mask is placed above the chuck stage and does not contact the silicon wafer; a single solenoid valve for evacuating, releasing, or filling the airway of the chuck station with a vacuum; A leveling and alignment unit, used for leveling and aligning the silicon wafer and the mask; A Z-axis assembly, which is used to drive the chuck table to move up and down; A control unit configured to: Controlling the single solenoid valve to evacuate the airway so that the silicon wafer is adsorbed on the chuck table; Controlling the leveling and alignment unit to level and align the silicon wafer and the mask; After completing the leveling and alignment of the silicon wafer and the mask, controlling the Z-axis assembly to move upward so that the nominal gap between the silicon wafer and the mask is close to but not more than 0, the value of the nominal gap depends on the accuracy of the Z-axis assembly, wherein the higher the accuracy of the Z-axis assembly, the closer the value of the nominal gap is to 0, and wherein the lower the accuracy of the Z-axis assembly, the smaller the value of the nominal gap is; Controlling the single solenoid valve to release the vacuum of the air channel so that the silicon wafer and the mask plate can be more closely attached; and An exposure unit, used for exposing the silicon wafer and the mask; The control unit is further configured to: After the exposure is completed, the single solenoid valve is controlled to evacuate the airway and wait for a preset period of time; and The Z-axis assembly is controlled to move downward to separate the silicon wafer from the mask.

10. The device according to claim 9, wherein: The leveling and alignment unit comprises an adaptive passive leveling assembly, the adaptive passive leveling assembly comprises a locking member and a sensor, and the leveling and alignment unit is further configured to: The Z-axis assembly drives the chuck stage to rise so that the gap between the silicon wafer and the mask plate is continuously reduced until they are in contact; The Z-axis assembly drives the chuck stage to continue to rise, the adaptive passive leveling assembly is compressed downward until the sensor is triggered, the Z-axis assembly stops moving and the locking member locks the adaptive passive leveling assembly, thereby completing the leveling of the silicon wafer and the mask; The Z-axis assembly drives the chuck table to descend; as well as When it is detected that the chuck stage has descended a preset distance and the silicon wafer and the mask are no longer in contact, the silicon wafer and the mask are aligned.

11. The device according to claim 10, wherein: When the chuck stage rises until the silicon wafer and the mask plate are in contact, the adaptive passive leveling component level the silicon wafer and the mask plate through compression and posture change; and When the sensor detects that the adaptive passive leveling assembly has been compressed to a preset degree, the Z-axis assembly stops moving, and the locking member is controlled to lock the adaptive passive leveling assembly so that the adaptive passive leveling assembly maintains a current posture.

12. The device according to claim 11, wherein The adaptive passive leveling assembly further comprises a decoupling ball, a guide post and a gravity compensation spring, wherein the guide column is disposed below the chuck table and is capable of compressing the adaptive passive leveling assembly by moving up and down; and The decoupling ball is arranged between the guide column and the chuck platform to prevent the adaptive passive leveling component from getting stuck when the posture changes, and The gravity compensation spring has a preset adaptive leveling force to prevent the silicon wafer from being damaged by leveling or exposure.

13. The device according to claim 9, wherein: The leveling and alignment unit comprises an active leveling assembly.

14. The device according to claim 9, wherein: When the nominal gap between the silicon wafer and the mask is 0, the actual gap between at least a portion of the silicon wafer and the mask is greater than 0.

15. The device according to claim 9, wherein: The control unit is further configured to: After the vacuum of the gas channel is released, the single solenoid valve is controlled to fill the gas into the gas channel so that the gas flows from the gas channel to the lower surface of the silicon wafer.

16. The device according to claim 15, wherein: The gas includes air, nitrogen or an inert gas.

17. The device according to claim 15, further comprising a pressure regulating valve and a throttle valve, wherein: The pressure regulating valve is used to control the pressure of the gas when the gas is filled into the airway so that the pressure is within a preset pressure range, and the throttle valve is used to control the flow of the gas when the gas is filled into the airway so that the flow is within a preset flow range.

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