A high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors

Abstract

This invention discloses a high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors. The method includes the following steps: S1, cleaning a 6mm silicon ingot as a substrate; S2, magnetron sputtering metal deposition on the front side after cleaning; S3, uniform imprinting and nanoimprinting after metal deposition; S4, CD (cathode alignment) confirmation and IBE (insert-beam overlap) etching and resist removal. This invention precisely aligns the image to the center point of the silicon ingot, ensuring high stability of the pattern positioning, with an offset of less than 100µm, resulting in a complete and highly accurate pattern.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors. Background Technology

[0002] Currently, grating mirrors use ultra-thick silicon ingots as substrates for photolithography. However, current stepper lithography machines cannot perform photolithography on ultra-thick silicon ingots, and the area is too large, which would exceed the exposure field of view. At the same time, 1:1 lithography machines cannot guarantee the CD morphology requirements below 1 micrometer.

[0003] During the nanoimprinting process, it is impossible to accurately align with the center point of the silicon ingot, resulting in poor stability of pattern positioning. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-precision positioning and centering nanoimprint processing method for thick silicon-based grating mirrors, the processing method comprising the following steps: S1. Cleaning is performed using a 6mm silicon ingot as a substrate; S2. After cleaning, magnetron sputtering is performed on the front side to plate metal. S3. After metal plating is completed, uniform pressure printing and nano-imprinting are performed. S4, Imprint CD confirmation and base adhesive confirmation, IBE etching and adhesive removal.

[0006] As a further improvement of the present invention, the magnetron sputtering metal plating includes Cr and Au.

[0007] As a further improvement of the present invention, the Cr plating process parameters in S2 are as follows: Ar flow rate 79 sccm, pressure 0.4pa, time 50s, rotational acceleration 10rpm / s, target-substrate distance 105mm, power 800w, and discharge mode DC (direct current discharge).

[0008] As a further improvement of the present invention, the Au plating process parameters in S2 are as follows: Ar flow rate 110 sccm, pressure 0.4pa, time 480s, rotational acceleration 10rpm / s, target-substrate distance 115mm, power 400w, and discharge mode RF.

[0009] As a further improvement of the present invention, in S3, the substrate imprinting is coarsely aligned using the hard film alignment point used for nanoimprinting, and then a second alignment is performed by fixing a right-angle ruler on the platform. Subsequently, the electric motor is adjusted to move the 100X lens to capture the cross mark point on the hard film for focusing alignment. A total of two mark points are used, and the horizontal position is confirmed twice to ensure that the centering error of the pattern is less than 100um. Furthermore, the 8um CD is fabricated on a 6mm silicon ingot using nanoimprinting technology.

[0010] As a further improvement of the present invention, the cleaning step in S1 is specifically SC1 (ammonia hydroxide and hydrogen peroxide 1:1.5 mixture) + QDR (rapid drainage) cleaning.

[0011] As a further improvement of the present invention, after the nanoimprinting is completed, each step is checked and confirmed by a detection instrument to confirm whether there are any defects.

[0012] As a further improvement of the present invention, the inspection and confirmation includes: analyzing whether the defect is fatal, testing the depth after development and etching with a profilometer, and confirming the overall 3D depth by confocal microscopy.

[0013] As a further improvement of the present invention, the confocal microscopy scanning includes 50x interferometric lens scanning to measure the structural depth and 100x confocal microscopy scanning of the structural 3D morphology.

[0014] As a further improvement of the present invention, the detection instrument includes a microscope, a profilometer, and a confocal microscope for detection.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The present invention employs a four-in-one technical solution combining composite film design, nanoimprinting, precise process linkage, and full-process quality control to achieve high-precision processing of thick silicon-based grating mirrors. This ensures precise alignment to the center point of the silicon ingot, thereby guaranteeing high stability of pattern positioning with an offset of less than 100µm, complete pattern, and high accuracy. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method of the present invention; Figure 2 A flowchart for the traditional method; Figure 3 This is a schematic diagram of the alignment method of the present invention. Detailed Implementation

[0017] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0018] It should be noted that when an element is referred to as "fixed," "mounted," "connected," or "set" with another element, it can be directly on or indirectly on the other element. It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0019] As a further improvement of the present invention, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0020] Example 1 Please refer to 1-3. This invention provides a technical solution: a high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors. This processing method includes the following steps: S1. Using a 6mm silicon ingot as a substrate, cleaning is performed using SC1 (a 1:1.5 mixture of ammonium hydroxide and hydrogen peroxide) + QDR (rapid drainage) cleaning.

[0021] S2. After cleaning, magnetron sputtering is performed on the front side to plate Cr and Au metals. The Cr plating process parameters are: Ar flow rate 79 sccm, pressure 0.4pa, time 50s, rotation speed acceleration 10rpm / s, target distance 105mm, power 800w, and discharge mode DC (direct current discharge). The Au plating process parameters are as follows: Ar flow rate 110 sccm, pressure 0.4pa, time 480s, rotational acceleration 10rpm / s, target-substrate distance 115mm, power 400w, and discharge method RF (radio frequency discharge).

[0022] S3. After metal plating is completed, uniform pressure printing and nano-imprinting are performed. The substrate imprinting process involves coarse alignment using the hard film alignment points on the nanoimprinting substrate, followed by secondary alignment using a right-angle ruler fixed on a platform. Subsequently, the electric motor is adjusted to move the 100X lens to capture the cross mark points on the hard film for focusing alignment. A total of two mark points are used for alignment, confirming the horizontal position twice to ensure that the centering error of the pattern is less than 100um. Finally, the 8um CD is fabricated on a 6mm silicon ingot using nanoimprinting technology.

[0023] S4. Confirmation of CD imprint and base adhesive, IBE etching and adhesive removal. The etching process uses paraffin wax to fix the surface, making the temperature more uniform during etching and avoiding edge color difference problems caused by tape fixation.

[0024] After the nanoimprinting process is completed, each step is inspected using testing instruments to confirm the presence of defects. The inspection and confirmation include: analyzing whether the defects are fatal, testing the depth after development and etching using a profilometer, and confirming the overall 3D depth using a confocal microscope. The confocal microscope scanning includes measuring the structural depth using a 50x interferometer lens and scanning the 3D morphology of the structure using a 100x confocal microscope. The testing instruments include a microscope, a profilometer, and a confocal microscope for inspection.

[0025] The hard film is fabricated by mirroring the pattern required by photolithography and etching. Imprinting and other processes are then performed on the hard film, overcoming the limitations of stepper lithography in fabricating 6mm substrates. Nanoimprinting also solves the problem of 1:1 lithography machines being unable to achieve 8µm linewidth CDs. Substrate imprinting requires adding mechanical position adjustment functions in the X and Y directions (1µm accuracy, 10mm travel) to the imprinting platform, and adding positioning bars to the platform to ensure the wafer is always centered and in the same position. Then, coarse alignment is performed using hard film alignment points, followed by secondary alignment using a right-angle ruler fixed to the platform. Finally, the electric motor moves the 100X lens to capture the crosshair mark on the hard film for focused alignment, using two mark points in total, confirming the horizontal position twice. This ensures the pattern centering error is less than 100µm. Furthermore, 8µm CDs are fabricated on 6mm silicon ingots using nanoimprinting technology. Currently, the centering accuracy has been achieved within 100µm. Comparative example: Previous processes involved laser direct writing onto silicon ingots, which was time-consuming, requiring 20 hours of continuous writing. Furthermore, laser direct writing could only expose points according to coordinates, resulting in slight pits on the sidewalls of the metal lines after the process.

[0026] Table 1 As shown in Table 1, the method of the present invention achieves high-precision processing of thick silicon-based grating mirrors, accurately aligning them to the center point of the silicon ingot, thereby ensuring high stability of pattern positioning, with an offset of less than 100µm, complete pattern, and high accuracy.

[0027] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision positioning and centering nanoimprinting method for thick silicon-based grating mirrors, characterized in that, This processing method includes the following steps: S1. Cleaning is performed using a 5-10mm silicon ingot as a substrate; S2. After cleaning, magnetron sputtering is performed on the front side to deposit metal, wherein the magnetron sputtering metal includes Cr and Au; S3. After metal plating is completed, uniform pressure printing and nano-imprinting are performed. S4. Confirmation of imprint line width and base adhesive, IBE etching and adhesive removal; In the S3 process, the substrate imprinting is coarsely aligned using the hard film alignment points used in nanoimprinting, and then a second alignment is performed using a right-angle ruler fixed on the platform. Subsequently, the electric motor is adjusted to move the 100X lens to capture the cross mark points on the hard film for focusing alignment. A total of two mark points are used for alignment twice to confirm the horizontal position, ensuring that the centering error of the pattern is less than 100um. Furthermore, an 8um linewidth pattern is formed on a 6mm silicon ingot using nanoimprinting technology.

2. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 1, characterized in that: The Cr plating process parameters in S2 are as follows: Ar flow rate 79 sccm, pressure 0.4 Pa, time 50 s, rotational acceleration 10 rpm / s, target-substrate distance 105 mm, power 800 W, and discharge method DC discharge.

3. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 1, characterized in that: The Au plating process parameters in S2 are as follows: Ar flow rate 110 sccm, pressure 0.4 Pa, time 480 s, rotational acceleration 10 rpm / s, target-substrate distance 115 mm, power 400 W, and discharge method: radio frequency discharge.

4. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 1, characterized in that: The cleaning step in S1 is specifically SC1+QDR cleaning, where SC1 is a 1:1.5 mixture of ammonium hydroxide and hydrogen peroxide, and QDR is rapid drainage.

5. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 1, characterized in that: After the nanoimprinting is completed, each step is checked with a testing instrument to confirm whether there are any defects.

6. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 5, characterized in that: The inspection and confirmation include: analyzing whether the defect is fatal, testing the depth after development and etching with a profilometer, and confirming the overall 3D depth by confocal microscopy.

7. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 6, characterized in that: The confocal microscopy scanning includes 50x interferometric lens scanning to measure structural depth and 100x confocal microscopy scanning of structural 3D morphology.

8. The high-precision positioning and centering nanoimprinting method for a thick silicon-based grating mirror according to claim 5, characterized in that: The testing instruments include microscopes, profilometers, and confocal microscopes for testing.

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