Blazed grating contour correction method based on electron beam gray photoetching manufacturing

Abstract

The invention relates to a blazed grating contour correction method based on electron beam gray photoetching manufacturing. According to the invention, the electron beam gray photolithography technology is adopted for manufacturing, a function relationship between the grating surface contour of the blazed grating and exposure dose distribution is given according to a test result of an atomic force microscope, and dose distribution correction is carried out according to the function, so that correction of the grating surface contour is realized. Compared with the prior art, the method has the advantages that through the microscopic test result under the pre-experiment, the dose distribution is corrected through the fitting function to realize the correction of the grating contour, the problem of diffraction efficiency reduction caused by grating surface bending can be avoided, and the performance of the blazed grating manufactured by electron beam gray scale photoetching is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a blazed grating profile correction method based on electron beam grayscale lithography. Background Art

[0002] Spectral imaging helps us obtain rich spatial and spectral information of the target by acquiring continuous imaging data within a certain spectral band. It has become an important and indispensable technology in the fields of atmospheric measurement, agricultural prevention and control, geological identification, etc. In order to achieve continuous spectral imaging, blazed gratings with linear dispersion characteristics have been widely used. In order to manufacture blazed gratings, methods such as ion etching, electron beam grayscale lithography, and mechanical characterization have been proposed. Among them, the blazed grating manufactured by electron beam grayscale lithography has the advantages of low roughness and small wave phase difference. However, since the development rate and exposure dose are not linearly related in actual processing, the conventional linear exposure dose change often causes the grating surface to bend, causing the diffraction efficiency to decrease. In order to achieve a linear grating surface profile to improve the diffraction efficiency, commercial electron beam lithography calculation software such as BEAMER is often used for simulation calculations to correct the exposure dose to achieve a linear grating surface. However, this method is time-consuming and complicated to operate, and there are differences between simulation and experiment, which affects the practical application of blazed gratings manufactured by electron beam grayscale lithography manufacturing technology. The commercial software correction method requires measuring the contrast curve to obtain development data, and then using the software to simulate to obtain the dose distribution. However, the contrast measurement results deviate from the actual development process and there are differences between the substrate material and the simulation. The dose distribution finally calculated cannot guarantee the expected grating profile. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] The present invention provides a method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography, comprising the following steps:

[0006] The blazed grating is processed under a linear dose gradient using electron beam grayscale lithography technology, and the surface profile of the blazed grating is measured using a microscope to obtain the position data of the blazed grating and the height data corresponding to its position;

[0007] In one grating period, the measured data is fitted with the linear dose gradient data to obtain the profile-dose function of the blazed grating profile height and dose;

[0008] The dose distribution when the profile is a straight line is calculated according to the profile-dose function. The calculated dose distribution is used to process the blazed grating under the calculated dose distribution gradient using electron beam grayscale lithography technology.

[0009] Furthermore, the blazed grating is processed under a linear dose gradient using electron beam grayscale lithography, specifically comprising: spin coating a 1.5 μm thick PMMA photoresist on a substrate, exposing a pattern evenly divided into 20 layers within a 9.1 μm period, with a dose coefficient difference of 0.06 between each layer, using a 100 keV electron beam at 30 nA for exposure, and then in IPA:H 2 Develop in a solution of O=2:1 for 4 minutes.

[0010] Furthermore, the microscope is an atomic force microscope.

[0011] Furthermore, the position data is the length data of the blazed grating profile in the horizontal direction, in μm.

[0012] Furthermore, the height data is the height data of the blazed grating profile in a vertical direction, and the unit is nm.

[0013] Furthermore, the linear dose gradient data includes position data and dose data corresponding to the position.

[0014] Furthermore, one grating period is 9.1 μm.

[0015] Furthermore, the data obtained from the measurement are fitted with the linear dose gradient data, specifically comprising: fitting the position data of the blazed grating and the height data corresponding to its position using a fitting function to obtain a spatial function of the position data of the blazed grating and the height data corresponding to its position, and replacing the position data of the spatial function with the dose data according to the linear dose gradient data to obtain a contour-dose function.

[0016] Furthermore, the fitting function is a nonlinear function, including: a polynomial function, an exponential function, and a logarithmic function.

[0017] Furthermore, the calculated dose distribution is a nonlinear dose distribution.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The present invention adopts electron beam grayscale lithography technology to manufacture blazed gratings, and uses the functional relationship between the grating surface profile and the exposure dose distribution to correct the dose distribution, thereby realizing the correction of the grating surface profile, and can effectively correct the grating surface shape of the blazed grating prepared by electron beam grayscale lithography.

[0020] (2) Compared with the prior art, the present invention can quickly and effectively realize linear blazed grating surface processing, avoid the performance degradation caused by grating profile bending, and achieve higher diffraction efficiency.

[0021] (3) The present invention performs fitting correction based on experiments, is simple to operate, and can better ensure the accuracy of the contour actually obtained. Compared with the commercial software correction method, the present method performs correction based on experiments, can avoid the difference between simulation and reality, and can accurately correct the grating contour in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of processing a blazed grating by the electron beam grayscale lithography process of the present invention;

[0023] Figure 2 A three-dimensional profile image of the blazed grating processed with a linear dose coefficient by an atomic force microscope scan of the present invention;

[0024] Figure 3 The atomic force microscope scanning height curve, fitting curve and ideal height curve diagram of the blazed grating processed before and after dose coefficient correction within one cycle of the present invention;

[0025] Figure 4 This is a three-dimensional profile image of the blazed grating processed with the corrected dose factor by atomic force microscope scanning of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] This embodiment provides a blazed grating profile correction method based on electron beam grayscale lithography manufacturing technology, which is used for profile correction of grating surface in electron beam lithography manufacturing technology, and includes the following steps:

[0028] Blazed grating processing: Blazed gratings are processed under linear dose gradient using electron beam grayscale lithography.

[0029] Blazed grating measurement: Atomic force microscopy is used to measure the blazed grating surface profile.

[0030] Blazed grating surface profile fitting: The measured blazed grating surface profile is fitted within one grating period to obtain the spatial function of the grating surface. The dose distribution during electron beam grayscale lithography exposure is used to convert the spatial function into a profile-dose function.

[0031] Blazed grating dose distribution correction: Use the contour-dose function to calculate the dose distribution corresponding to the target contour.

[0032] Corrected blazed grating processing: Using the corrected dose distribution, blazed gratings are processed using electron beam grayscale lithography under corrected dose gradient.

[0033] Furthermore, the electron beam grayscale lithography technology utilizes the periodic and continuous change of the charge dose distribution in the exposure pattern to realize the blazed grating processing.

[0034] Furthermore, the photoresist used in the electron beam grayscale lithography manufacturing technology is a positive photoresist represented by PMMA.

[0035] Furthermore, the blazed grating surface profile fitting function is a nonlinear function such as a polynomial function, an exponential function, a logarithmic function, etc.

[0036] Furthermore, the profile-dose function is obtained by utilizing the spatial distribution of the dose through the spatial distribution of the grating surface.

[0037] Furthermore, the correction method is to use the profile-dose function to correct the dose distribution into a nonlinear distribution, thereby realizing the correction of the grating surface profile.

[0038] According to the electronic grayscale lithography process, this embodiment provides a blazed grating profile correction method based on the electron beam grayscale lithography manufacturing technology, wherein the processed structure is a blazed grating with a period of 9.1 μm and a blazed angle of 4°. Figure 1 Shown is a schematic diagram of a blazed grating profile correction method of electron beam grayscale lithography manufacturing technology. The electron beam grayscale lithography technology of the blazed grating forms a blazed grating by exposing different doses within a grating period to achieve different residual heights of the photoresist. The profile correction method is to achieve profile correction by adjusting the exposure dose coefficient corresponding to different grating areas during the exposure process through measurement feedback.

[0039] Next, a method embodiment of the present invention is given, which is a blazed grating profile correction method based on electron beam grayscale lithography manufacturing technology, and the method comprises the following steps:

[0040] Blazed grating processing: Electron beam grayscale lithography technology is used to process blazed gratings under linear dose gradient. The specific processing process is as follows:

[0041] A 1.5 μm thick PMMA photoresist was spin-coated on the substrate. The exposure pattern was evenly divided into 20 layers within a 9.1 μm period. The dose coefficient difference between each layer was 0.06. A 100 keV electron beam was used for exposure at 30 nA. 2 Develop in O=2:1 solution for 4 minutes.

[0042] Blazed grating measurement: Atomic force microscopy is used to measure the profile of the blazed grating surface. The results are as follows: Figure 2 As shown, the grating surface exhibits a significant curvature.

[0043] Blazed grating surface profile fitting: The measured blazed grating surface profile is fitted within one grating period to obtain a function of the grating profile. The function used in this embodiment is a quadratic function (h = ax 2 +bx+c), the function obtained in this embodiment is: height = -4.52×position 2 -61.05×position+97.33, the unit of position is μm, the unit of height is nm. And according to the dose distribution during exposure, it is converted into a profile-dose function (h=dz 2 +ez+f). The function obtained in this embodiment is: height = -177.7 × dose coefficient 2 +102.8×dose factor+288.2, height unit is nm.

[0044] Blazed grating dose distribution correction: Use the profile-dose function to calculate the dose distribution when the profile is a straight line, and correct the dose distribution to a nonlinear distribution to achieve a linear grating surface profile.

[0045] Corrected blazed grating processing: Using the corrected dose distribution, electron beam grayscale lithography technology is used to process the blazed grating under the corrected dose gradient. The specific processing process is as follows:

[0046] A 1.5 μm thick PMMA photoresist was spin-coated on the substrate. The exposure pattern was evenly divided into 20 layers within a 9.1 μm period. The dose coefficient of each layer was calculated in the previous step. A 100 keV electron beam was used for exposure at 30 nA. 2 Develop in O=2:1 solution for 4 minutes.

[0047] The results are as follows Figure 4 As shown, the grating surface has been corrected and has good linearity.

[0048] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography. It is characterized in that The following steps are involved: The blazed grating is processed under a linear dose gradient using electron beam grayscale lithography technology, and the surface profile of the blazed grating is measured using a microscope to obtain the position data of the blazed grating and the height data corresponding to its position; In one grating period, the measured data is fitted with the linear dose gradient data to obtain the profile-dose function of the blazed grating profile height and dose; The dose distribution when the profile is a straight line is calculated according to the profile-dose function. The calculated dose distribution is used to process the blazed grating under the calculated dose distribution gradient using electron beam grayscale lithography technology.

2. According to the method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography in claim 1, It is characterized in that The method of processing the blazed grating under a linear dose gradient by using electron beam grayscale lithography technology specifically includes: spin coating a 1.5 μm thick PMMA photoresist on a substrate, evenly dividing the exposure pattern into 20 layers within a 9.1 μm period, with a dose coefficient difference of 0.06 between each layer, using a 100 keV electron beam at 30 nA for exposure, and then in IPA:H 2 Develop in a solution of O=2:1 for 4 minutes.

3. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The microscope is an atomic force microscope.

4. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The position data is the length data of the blazed grating profile in the horizontal direction, and the unit is μm.

5. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The height data is the height data of the blazed grating profile in the vertical direction, and the unit is nm.

6. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The linear dose gradient data includes position data and dose data corresponding to the position.

7. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The one grating period is 9.1 μm.

8. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The fitting of the measured data with the linear dose gradient data specifically includes: fitting the position data of the blazed grating and the height data corresponding to its position using a fitting function to obtain a spatial function of the position data of the blazed grating and the height data corresponding to its position, and replacing the position data of the spatial function with the dose data according to the linear dose gradient data to obtain a profile-dose function.

9. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 8, It is characterized in that The fitting function is a nonlinear function, including: a polynomial function, an exponential function, and a logarithmic function.

10. The method for correcting the profile of a blazed grating manufactured based on electron beam grayscale lithography according to claim 1, It is characterized in that The calculated dose distribution is a nonlinear dose distribution.

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