Synchrotron radiation X-ray interference lithography adaptive exposure device and method

Abstract

The present invention provides a synchrotron radiation X-ray interference lithography adaptive exposure device, comprising an offline distance adjustment component and an online adaptive exposure component detachably mounted together; the offline distance adjustment component comprises a grating bracket, a mask grating mounted thereon, a distance adjustment rod inserted therein, and a locking screw for locking the distance adjustment rod on the grating bracket; the online adaptive exposure component comprises a sample to be tested that is squeezed and matched with one end of the distance adjustment rod facing the mask grating, and a force sensor connected to the side of the offline distance adjustment component away from the mask grating, the sample to be tested is mounted on the sample bracket, and the force sensor measures the pressure on the sample to be tested in a direction perpendicular to the plane where the sample to be tested is located. The present invention also provides a corresponding adaptive exposure method. The adaptive exposure device of the present invention can avoid relative displacement between the grating and the sample during exposure, and ensure that the distance between the grating and the sample meets the requirements when adjusting the exposure area.

Description

Technical Field

[0001] The present invention relates to an exposure device, and more specifically to a synchrotron radiation X-ray interference lithography adaptive exposure device and method. Background Art

[0002] As the next generation of lithography technology, extreme ultraviolet lithography has been entrusted by the semiconductor industry with the mission of saving Moore's Law. Extreme ultraviolet photoresist is a key material for manufacturing integrated circuits, and its performance directly affects the performance of integrated circuit chips. The core exposure performance of extreme ultraviolet photoresist mainly includes three aspects: sensitivity, resolution and edge roughness. The characterization of these exposure performances is a necessary condition for the development of extreme ultraviolet photoresist and an important link in optimizing the formulation of extreme ultraviolet photoresist. X-ray interference lithography (XIL) is a new advanced micro-nano processing technology that uses the interference fringes of two or more coherent X-ray beams to expose photoresist, and can carry out nanostructure processing of dozens or even dozens of nanometer periods. The principle of interference lithography is to use a mask grating to divide a beam of light into multiple coherent beams, and generate interference fringes at the photoresist to expose the photoresist, and the exposure pattern can be recorded. The performance of the photoresist can be characterized by detecting the quality of the exposure pattern. At present, interference lithography is the only experimental technology that can simultaneously detect three exposure properties of photoresist in one exposure.

[0003] The schematic diagram of the existing interference lithography technology is as follows Figure 1 As shown, assuming that the period of the mask grating is d, the wavelength of the incident light is λ, and the diffraction angle of the light beam is θ, then according to the grating equation:

[0004] d*sinθ=N*λ (1)

[0005] Where N is the diffraction order.

[0006] Assuming that the width of the mask grating is D, and the center distance between the two mask gratings is 2D, then the width of the interference area of ​​the ±1st order diffraction light of the two gratings is D, and the vertical working distance L from the position where the interference fringes are generated to the mask grating is:

[0007] L=D / tanθ (2)

[0008] From equations (1) and (2), we can see that

[0009]

[0010] Where N is the diffraction order, D is the width of the mask grating, λ is the wavelength of the incident light, and d is the period of the mask grating.

[0011] For extreme ultraviolet light, its wavelength is 13.5nm. If the width of the mask grating is 200μm and the period is 80nm, then for the ±1st order diffraction of the grating, the vertical distance L between the position where the interference fringes are generated and the mask grating is 1.17mm. Considering the difficulty of processing small-period mask gratings, if the width of the mask grating is reduced to 100μm, the vertical distance L between the position where the interference fringes are generated and the mask grating is correspondingly reduced to 0.58mm.

[0012] With the development of technology, higher requirements are put forward for the period of mask grating, and the grating period is usually required to be less than 100nm. According to the above calculation, the vertical distance between the position where the interference fringes are generated and the mask grating is about several hundred microns. Due to the propagation characteristics of extreme ultraviolet light, the entire exposure system needs to be placed in a high vacuum environment, which puts higher requirements on distance measurement and the stability of the entire exposure system.

[0013] In the existing exposure system, the mask grating and the sample are respectively located on their own adjustment mechanisms. The mask grating moves in one dimension to adjust the distance between it and the sample, and the sample moves in two dimensions to change the exposure position of the mask grating on the sample. The movement direction of the sample grating is perpendicular to the running direction of the sample. Although the existing system can meet the requirement of a vertical distance of several hundred microns, it has two disadvantages: the first disadvantage is poor stability, which is mainly reflected in the relative displacement between the mask grating and the sample. If the mask grating and the sample are not relatively static during exposure, the exposure quality will be affected. This is because in the existing exposure system, the grating and the sample are not hard-connected. In other words, there is no contact between the two. The overall stability of the system is relied on to minimize the relative displacement between the two. If the overall stability of the system is good, the relative displacement is small. If the overall stability of the system is poor, the relative displacement is large. The second disadvantage is that it is difficult to ensure that the trajectory of the sample movement is completely perpendicular to the mask grating. Therefore, when the exposure area on the sample is changed, it is equivalent to changing the distance between the sample and the mask grating, which cannot fully meet the requirements of formula (3) above. Summary of the invention

[0014] The object of the present invention is to provide a synchrotron radiation X-ray interference lithography adaptive exposure device and method to avoid relative displacement between the grating and the sample during exposure and to ensure that the distance between the grating and the sample meets the requirements when adjusting the exposure area.

[0015] In order to achieve the above-mentioned purpose, the present invention provides a synchrotron radiation X-ray interference lithography adaptive exposure device, comprising an offline distance adjustment component and an online adaptive exposure component which are detachably mounted together; the offline distance adjustment component comprises a grating bracket, a mask grating mounted on the grating bracket, a distance adjustment rod inserted in the grating bracket, and a locking screw for locking the distance adjustment rod on the grating bracket; the online adaptive exposure component comprises a sample to be tested which is squeezed and matched with one end of the distance adjustment rod facing the mask grating and a force sensor detachably connected to a side of the offline distance adjustment component which is away from the mask grating, the sample to be tested is mounted on the sample bracket, and the force sensor is configured to measure the pressure on the sample to be tested in a direction perpendicular to the plane where the sample to be tested is located.

[0016] The extending direction of the distance adjustment rod is perpendicular to the plane where the mask grating is located, and both ends of the adjustment rod pass through the grating bracket.

[0017] The extending direction of the locking screw is parallel to the plane where the mask grating is located.

[0018] The periphery of the grating bracket is provided with three screw holes for the distance adjustment rod to pass through, and the distance adjustment rod is a screw rod matched with the screw holes.

[0019] A light-through hole is arranged at the center of the grating support, and a mask grating substrate is arranged at a position corresponding to the light-through hole on one end surface, and the mask grating is prepared on the mask grating substrate.

[0020] The sample holder is connected to a sample driving motor, and the sample driving motor is configured to drive the sample holder to move along a two-dimensional direction parallel to the plane where the sample to be tested is located.

[0021] The side of the force sensor away from the offline distance adjustment component is connected to the grating drive motor through a connecting fixed block, and the grating drive motor is configured to drive the grating bracket of the offline distance adjustment component to move in a direction perpendicular to the plane where the sample to be tested is located through the force sensor.

[0022] The sample to be tested is prepared on a sample substrate, and the sample substrate is fixed on a sample fixing plate. A plurality of springs are installed on a side of the sample fixing plate away from the sample to be tested, and the side is connected to the sample support through the springs.

[0023] The number of the springs is 3, and the 3 springs are evenly distributed on the sample fixing plate.

[0024] In another aspect, the present invention provides a synchrotron radiation X-ray interference lithography adaptive exposure method, comprising:

[0025] S0: providing the above-mentioned synchrotron radiation X-ray interference lithography adaptive exposure device;

[0026] S1: installing the offline distance adjustment component of the synchrotron radiation X-ray interference lithography adaptive exposure device on a fixed fixture, and using the offline distance adjustment component to perform offline distance adjustment and position locking;

[0027] S2: installing the off-line distance adjustment component and the on-line adaptive exposure component of the synchrotron radiation X-ray interference lithography adaptive exposure device together and placing them in a vacuum chamber;

[0028] S3: driving the grating support to move towards the sample to be tested until all three distance adjustment rods are in contact with the sample to be tested, at which time the grating support is stopped and online exposure of the sample to be tested is performed;

[0029] S4: After the exposure is completed, the grating support is driven to move away from the sample to be measured, the sample support is driven to change position, and the process returns to step S3 until the measurement of the sample to be measured is completed.

[0030] The synchrotron radiation X-ray interference lithography adaptive exposure device of the present invention realizes the cooperation between the mask grating and the sample to be tested by squeezing and matching the three distance adjustment rods with the sample to be tested during exposure, and controls the relative displacement between the two by friction force. It can almost be considered that the two are relatively static during exposure, and are very little affected by the overall stability of the system. In addition, the synchrotron radiation X-ray interference lithography adaptive exposure device of the present invention adjusts the distance between the grating and the sample through the three distance adjustment rods, and even if the track of the sample movement is not parallel to the mask grating, the distance between the grating and the sample can be guaranteed to meet the requirements during exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the existing interference lithography technology.

[0032] Figure 2 It is a schematic diagram of the overall structure of a synchrotron radiation X-ray interference lithography adaptive exposure device according to an embodiment of the present invention.

[0033] Figure 3 and Figure 4 is a schematic structural diagram of an offline distance adjustment component of a synchrotron radiation X-ray interferometer lithography adaptive exposure device according to an embodiment of the present invention, wherein: Figure 3 A front view of the off-line distance adjustment assembly is shown, Figure 4 A side cross-sectional view of an off-line distance adjustment assembly is shown. DETAILED DESCRIPTION

[0034] like Figure 2-Figure 4The figure shows a synchrotron radiation X-ray interference lithography adaptive exposure device according to an embodiment of the present invention, which includes an offline distance adjustment component and an online adaptive exposure component that are detachably mounted together.

[0035] like Figure 3 and Figure 4 As shown, the offline distance adjustment component is used to perform offline distance adjustment between the mask grating 2 and the sample to be tested, and includes a grating bracket 1, a mask grating 2 mounted on the grating bracket 1, a distance adjustment rod 3 inserted in the grating bracket 1, and a locking screw 4 for locking the distance adjustment rod 3 to the grating bracket 1.

[0036] The extending direction of the distance adjustment rod 3 is perpendicular to the plane where the mask grating 2 is located, and both ends of the adjustment rod 3 pass through the grating bracket 1. The extending direction of the locking screw 4 is parallel to the plane where the mask grating 2 is located.

[0037] The mask grating 2 is fixed at the center of the grating bracket 1. The periphery of the grating bracket 1 is provided with three screw holes for the distance adjustment rod 3 to pass through. The three screw holes are evenly distributed on the periphery of the mask grating 2. The distance adjustment rod 3 is a screw rod that matches the screw hole of the grating bracket 1. After the length is adjusted, it is locked and fixed on the grating bracket by the locking screw 4.

[0038] A light hole 11 is provided at the center of the grating support 1, and a mask grating substrate 21 is provided at a position corresponding to the light hole on one end surface, and the mask grating 2 is prepared on the mask grating substrate 21. The mask grating substrate 21 is preferably a SiN substrate, and the mask grating is prepared on the SiN substrate. A through hole needs to be opened at the center of the grating support 1 to ensure that the upstream EUV light can irradiate the mask grating. The position of the grating support 1 to fix the mask grating needs to be grooved, and the groove depth is the same as the thickness of the mask grating substrate 21. Finally, the mask grating substrate 21 is attached to the support by glue.

[0039] There is no special requirement for the overall shape of the grating support 1. The mask grating 2 can be square, but in this embodiment, considering the installation of three adjustment rods, the overall shape of the grating support 1 is circular, so as to reserve the installation position of the distance adjustment rod 3.

[0040] In this embodiment, the end face of one side of the grating support 1 on which the mask grating 2 is mounted is defined as the front face, therefore, the zero scale of the distance adjustment rod 3 is set at the plane where the mask grating 2 is located, and the distance adjustment rod 3 passes through the grating support 1 from the back face of the grating support 1, and the distance that the distance adjustment rod 3 exceeds the front face of the grating support 1 is the vertical working distance of the mask grating (i.e., the vertical working distance L calculated by the above formula (3)). Moreover, the distance that each distance adjustment rod 3 exceeds the front face of the grating support 1 needs to be adjusted to the vertical working distance of the mask grating, so that a plane can be defined by using the endpoints of the three distance adjustment rods 3, and the defined plane is the plane where the sample is located during exposure.

[0041] Therefore, during offline distance adjustment, a micrometer (or vernier caliper) can be used to measure in real time the distance that the distance adjustment rod 3 exceeds the front of the grating bracket 1 until the distance is the vertical working distance of the mask grating. At this time, the adjustment is completed, and the position of the distance adjustment rod 3 is locked by the locking screw 4 next to the distance adjustment rod 3. The micrometer (or vernier caliper) is not fixed on the synchrotron radiation X-ray interference lithography adaptive exposure device of the present invention.

[0042] After the offline distance adjustment is completed, the offline distance adjustment component can be installed together with the online adaptive exposure component and placed in the vacuum chamber for subsequent online exposure.

[0043] See also Figure 2 The online adaptive exposure assembly includes a sample 6 to be tested which is pressed and matched with one end of the distance adjustment rod 3 facing the mask grating 2 and a force sensor 8 which is detachably connected to the side of the offline distance adjustment assembly which is away from the mask grating 2. The sample 6 to be tested is mounted on a sample holder 5. The sample holder 5 is connected to a sample driving motor (not shown), which is configured to drive the sample holder 5 to move in a two-dimensional direction parallel to the plane where the sample 6 to be tested is located.

[0044] The synchrotron radiation device is very large, and the light emitted by the light source is transmitted parallel to the ground. In order to ensure the efficiency of the light beam, the light path is generally not designed to irradiate the sample vertically downward, or to irradiate the sample at an angle. Normally, the light is incident on the sample horizontally. Therefore, the sample 6 to be tested is normally set vertically.

[0045] Wherein, the sample to be tested 6 is a photoresist, which is prepared on a sample substrate 61. The photoresist is a thin film of several tens of nanometers. Without a substrate, this thin film is difficult to support itself, so a layer of sample substrate 6 is needed for support. In addition, the sample substrate 61 is fixed on a sample fixing plate 71. A plurality of springs 72 are installed on the side of the sample fixing plate 71 away from the sample to be tested 6, and are connected to the sample holder 5 through the springs 72. In the present embodiment, the number of the springs 72 is 3, and the 3 springs 72 are evenly distributed on the sample fixing plate 71 (near the outer edge, the angles between the three springs are 120 °). The strength of the spring 72 can not crush the sample substrate 61 while meeting the adjustment requirements.

[0046] The side of the force sensor 8 away from the offline distance adjustment component is connected to the grating drive motor 9 through the connection fixing block 10. The connection fixing block 10 may have a counterweight function, and the grating drive motor 9 is configured to drive the grating bracket 1 of the offline distance adjustment component to move in a direction perpendicular to the plane where the sample 6 to be tested is located through the force sensor 8, and the force sensor 8 is configured to measure the pressure on the sample 6 to be tested in the direction perpendicular to the plane where the sample 6 to be tested is located. Thus, the grating bracket 1 is driven by the grating drive motor 9 to move in a direction close to the sample 6 to be tested until all three distance adjustment rods 3 contact the sample substrate 61 coated with the sample 6 to be tested (i.e., contact the sample 6 to be tested), at which time the grating drive motor 9 stops working and the online exposure of the sample 6 to be tested is performed. When the value on the force sensor 8 reaches a predetermined threshold, it is determined that the distance adjustment rods 3 are all in contact with the sample substrate 61, at which time the grating drive motor 9 stops working and exposure begins.

[0047] The force sensor 8 measures the sum of the pressures of the three distance adjustment rods 3 on the sample 6 to be tested. During the equipment debugging, the predetermined threshold of the force sensor can be determined by observing the deformation of the three springs 72. The predetermined threshold is related to the parameters such as the strength of the springs and needs to be determined by the specific value during the equipment debugging. In the process of the motor driving the mask grating close to the sample fixing plate, the grating drive motor 9 stops driving after the three springs 72 have obvious deformation. At this time, the value measured by the force sensor 8 can be set as the predetermined threshold of the force sensor 8 during normal exposure.

[0048] After the exposure is completed, the grating drive motor 9 is used to drive the grating support 1 to move away from the sample 6 to be tested, and the sample drive motor is used to drive the sample support 5 to change position. The grating drive motor 9 and the sample drive motor are not the same group of motors. The movement direction of the mask grating 2 is perpendicular to the movement direction of the sample 6 to be tested. Therefore, the grating drive motor 9 is a one-dimensional motor, and its movement direction is close to or away from the sample 6 to be tested. The sample drive motor includes two one-dimensional motors perpendicular to each other, which make two-dimensional movements parallel to the plane where the sample 6 to be tested is located, so as to change the exposure position on the sample 6 to be tested, thereby changing the exposure area of ​​the photoresist on the substrate for the next exposure. When the sample to be tested 6 is exposed, the sample substrate 61 coated with the sample to be tested 6 can be pressed onto the three distance adjusting rods 3 by means of three springs 72. This has two advantages: first, the sample substrate 61 coated with the sample to be tested 6 is pressed onto the three distance adjusting rods 3, and the relative vibration between the mask grating 2 and the sample to be tested 6 can be minimized to the greatest extent by means of friction, which is beneficial to improving the stability of the exposure system and obtaining high-quality exposure patterns; second, when a certain pressure is applied, the three springs 72 can adaptively adjust the deformation of each spring, so that the sample substrate 61 coated with the sample to be tested 6 is completely close to the three distance adjusting rods 3, which means that the sample to be tested 6 is in the plane defined by the three distance adjusting rods 3, thereby ensuring the parallelism between the photoresist plane to be tested and the mask grating.

[0049] Based on the above-mentioned synchrotron radiation X-ray interference lithography adaptive exposure device, the synchrotron radiation X-ray interference lithography adaptive exposure method implemented includes:

[0050] Step S0: providing the above-mentioned synchrotron radiation X-ray interference lithography adaptive exposure device;

[0051] Step S1: installing the offline distance adjustment component on a fixed fixture, and using the offline distance adjustment component to adjust the offline distance and lock the position;

[0052] The specific structure of the offline distance adjustment component is as described above.

[0053] In step S1, when performing offline distance adjustment, a micrometer (or vernier caliper) is used to measure in real time the distance that the distance adjustment rod 3 exceeds the front of the grating bracket 1, until the distance that the distance adjustment rod 3 exceeds the front of the grating bracket 1 is the vertical working distance of the mask grating. At this time, the adjustment is completed, and the position of the distance adjustment rod 3 is locked using the locking screw 4 next to the distance adjustment rod 3.

[0054] Step S2: installing the offline distance adjustment component and the online adaptive exposure component together and placing them in a vacuum chamber;

[0055] The specific structure of the online adaptive exposure component is as described above.

[0056] Step S3: Use the grating drive motor 9 to drive the grating bracket 1 to move towards the direction close to the sample 6 to be tested until all three distance adjustment rods 3 contact the sample 6 to be tested. At this time, stop driving the grating bracket 1 (that is, the grating drive motor 9 stops working) and perform online exposure of the sample 6 to be tested.

[0057] When the value on the force sensor 8 reaches a predetermined threshold, it is determined that the distance adjustment rod 3 is completely in contact with the sample substrate 61 .

[0058] Step S4: After the exposure is completed, the grating drive motor 9 is used to drive the grating support 1 to move away from the sample 6 to be tested, and the sample drive motor is used to drive the sample support 5 to change position, and the process returns to step S3 until the measurement of the sample 6 to be tested is completed.

[0059] The grating drive motor 9 is a one-dimensional motor, and its movement direction is close to or away from the sample to be tested 6. The sample drive motor includes two one-dimensional motors perpendicular to each other, which make two-dimensional movements parallel to the plane where the sample to be tested 6 is located to change the exposure position on the sample to be tested 6, thereby changing the exposure area of ​​the sample to be tested 6 on the substrate for the next exposure.

Claims

1. A synchrotron radiation X-ray interference lithography adaptive exposure device, characterized in that: It includes an offline distance adjustment component and an online adaptive exposure component which are detachably mounted together; The offline distance adjustment assembly includes a grating bracket, a mask grating mounted on the grating bracket, three distance adjustment rods inserted in the grating bracket, and locking screws for locking the distance adjustment rods on the grating bracket; The online adaptive exposure assembly includes a sample to be tested that is pressed and matched with one end of the distance adjustment rod facing the mask grating, and a force sensor that is detachably connected to the side of the offline distance adjustment assembly that is away from the mask grating, the sample to be tested is mounted on a sample holder, and the force sensor is configured to measure the pressure on the sample to be tested in a direction perpendicular to the plane where the sample to be tested is located; The extension direction of the distance adjustment rod is perpendicular to the plane where the mask grating is located, and the two ends of the adjustment rod pass through the grating bracket; the distance that each distance adjustment rod exceeds the front of the grating bracket is adjusted to the vertical working distance of the mask grating, so that a plane is defined by the end points of the three distance adjustment rods, and the defined plane is the plane where the sample is exposed; the force sensor measures the sum of the pressures of the three distance adjustment rods on the sample to be tested.

2. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: The extending direction of the locking screw is parallel to the plane where the mask grating is located.

3. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: The periphery of the grating bracket is provided with three screw holes for the distance adjustment rod to pass through, and the distance adjustment rod is a screw rod matched with the screw holes.

4. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: A light-through hole is arranged at the center of the grating support, and a mask grating substrate is arranged at a position corresponding to the light-through hole on one end surface, and the mask grating is prepared on the mask grating substrate.

5. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: The sample holder is connected to a sample driving motor, and the sample driving motor is configured to drive the sample holder to move along a two-dimensional direction parallel to the plane where the sample to be tested is located.

6. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: The side of the force sensor away from the offline distance adjustment component is connected to the grating drive motor through a connecting fixed block, and the grating drive motor is configured to drive the grating bracket of the offline distance adjustment component to move in a direction perpendicular to the plane where the sample to be tested is located through the force sensor.

7. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 1, characterized in that: The sample to be tested is prepared on a sample substrate, and the sample substrate is fixed on a sample fixing plate. A plurality of springs are installed on a side of the sample fixing plate away from the sample to be tested, and the side is connected to the sample support through the springs.

8. The synchrotron radiation X-ray interference lithography adaptive exposure device according to claim 7, characterized in that: The number of the springs is 3, and the 3 springs are evenly distributed on the sample fixing plate.

9. A synchrotron radiation X-ray interference lithography adaptive exposure method, characterized in that: include: Step S0: providing a synchrotron radiation X-ray interference lithography adaptive exposure device according to any one of claims 1 to 8; Step S1: installing the offline distance adjustment component of the synchrotron radiation X-ray interference lithography adaptive exposure device on a fixed fixture, and using the offline distance adjustment component to perform offline distance adjustment and position locking; Step S2: installing the off-line distance adjustment component and the on-line adaptive exposure component of the synchrotron radiation X-ray interference lithography adaptive exposure device together and placing them in a vacuum chamber; Step S3: driving the grating support to move towards the sample to be tested until all three distance adjustment rods are in contact with the sample to be tested, at which time the driving of the grating support is stopped, and online exposure of the sample to be tested is performed; Step S4: After the exposure is completed, the grating support is driven to move away from the sample to be measured, the sample support is driven to change position, and the process returns to step S3 until the measurement of the sample to be measured is completed.

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