阅读说明：本技术 一种在二维材料上加工光栅的方法 (Method for processing grating on two-dimensional material ) 是由 王磊 曲迪 陈帅 王俊 李宗宴 李文喆 刘新鹏 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种在二维材料上加工光栅的方法,属于半导体材料加工技术领域,其特征在于,包括如下步骤：S1、FIB加工套刻标记；S2、SEM拍照；S3、制作加工版图；S4、片源预处理；S5、涂胶；S6、EBL套刻；S7、显影；S8、RIE刻蚀；S9、去胶。本发明通过FIB在待加工位置周边直接刻蚀标记,然后将包括标记和待加工位置的SEM照片导入画图软件,根据SEM照片可以直观的判断出待加工位置的相对坐标和方向,然后通过EBL自动套刻的方式,将图形曝光在待加工区域。该方法可以实现加工位置误差小于500nm,角度误差小于0.1°；并且该方法工艺步骤较少,成本低,出错率低。(The invention discloses a method for processing a grating on a two-dimensional material, which belongs to the technical field of semiconductor material processing and is characterized by comprising the following steps of: s1, marking by FIB processing and alignment; s2, taking a picture by SEM; s3, manufacturing a processing layout; s4, preprocessing a film source; s5, gluing; s6, EBL alignment; s7, developing; s8, RIE etching; and S9, removing the photoresist. The method directly etches a mark on the periphery of the position to be processed through FIB, then introduces an SEM picture comprising the mark and the position to be processed into drawing software, can visually judge the relative coordinate and direction of the position to be processed according to the SEM picture, and then exposes a pattern in the area to be processed in an EBL automatic alignment mode. The method can realize that the error of the processing position is less than 500nm, and the angle error is less than 0.1 degree; the method has the advantages of fewer process steps, low cost and low error rate.)

1. A method of processing a grating on a two-dimensional material, comprising the steps of:

s1, marking by FIB processing alignment: etching 1 large cross mark and 4 small cross marks at a position 200 micrometers away from a to-be-processed area of the two-dimensional material by using FIB, wherein the etching depth is greater than 200nm, the period of the four small cross marks is 200 micrometers, the large cross mark is positioned at a position 300 micrometers above the left of the small cross mark, and when the marks are found in the subsequent EBL exposure, the large mark is found firstly;

s2, taking a picture by SEM: the direction of the 4 small cross marks is turned right, and the small cross marks and the area to be processed are moved to the same view field for photographing under a proper magnification;

s3, manufacturing a processing layout: firstly, drawing the 1 large cross mark and the 4 small cross marks in L-edge software, then guiding an SEM picture into the L-edge software, adjusting the size of a single pixel point of the SEM picture and the rotation angle of the picture, enabling each mark on the SEM picture to be overlapped with each corresponding mark in the layout, and drawing a graph needing to be processed at a position to be processed on the two-dimensional material in the SEM picture;

s4, preprocessing a film source: baking the sheet source on a hot plate at 180 ℃ for 5min, and then purging the sheet source by using a nitrogen gun to remove surface particle pollutants;

s5, gluing: spin-coating electron beam photoresist ZEP 520A by using a glue spreader, baking for 2min by using a hot plate at 180 ℃, and removing redundant solvent in the photoresist;

s6, EBL alignment: after a film source coated with photoresist is placed into EBL equipment, a large cross mark is firstly searched under a back scattering electron probe, then a small cross mark is found through the relative coordinates of the large cross mark and the small cross mark, and finally automatic alignment is carried out according to the relative coordinates of the small mark and the position to be processed;

s7, developing: development in ZEDN50 for 90S at room temperature followed by 30S fixation in IPA; baking at high temperature for 2min with a hot plate at 120 deg.C;

s8, RIE etching: RIE etching is carried out on the two-dimensional material with the photoresist pattern, Ar is used as gas, the flow is 25sccm, the bias power is 50W, and the time is 30s-1min, so that the photoresist pattern is transferred to the two-dimensional material;

s9, removing the photoresist: and (3) placing the film source into a degumming solution at 70 ℃ for static soaking for 10min-30min, and removing the photoresist on the surface.

2. The method of claim 1, wherein the two-dimensional material is molybdenum disulfide or tungsten diselenide.

3. A method for processing gratings on two-dimensional material according to claim 1 or 2, wherein the large cross marks have a size of 200 micrometers by 10 micrometers.

4. A method for processing gratings on two-dimensional material according to claim 1 or 2, wherein the small cross marks have a size of 100 micrometers by 5 micrometers.

Technical Field

The invention belongs to the technical field of semiconductor material processing, and particularly relates to a method for processing a grating on a two-dimensional material.

Background

As is known, transition metal sulfides in two-dimensional materials, such as molybdenum disulfide and tungsten diselenide, have excellent optical and electrical properties, and such materials have adjustable photonic band gap structures, and have become one of the research hotspots in the field of nano-optoelectronic material device research. The monolayer transition metal sulfide has a direct band gap, and the absorption of the monolayer molybdenum disulfide in free space is 10-20% in a visible light wave band. In recent years, research on photoelectric devices based on transition metal sulfide two-dimensional materials is rapidly developed, and important application values are shown in the fields of energy, photoelectric detection, biosensing and the like.

For the two-dimensional material prepared by the mechanical stripping method, because the two-dimensional material prepared by the mechanical stripping method is randomly distributed at a position and an angle on a sheet source and has a small size, a processing method with high positioning precision is needed for processing the two-dimensional material at a specific position and in a specific direction of the specific two-dimensional material.

Disclosure of Invention

The invention provides a method for processing a grating on a two-dimensional material, which aims to solve the technical problems in the prior art and comprises the steps of directly etching a mark on the periphery of a position to be processed through FIB, importing an SEM picture comprising the mark and the position to be processed into drawing software, judging the relative coordinate and direction of the position to be processed visually according to the SEM picture, and exposing a pattern in the area to be processed in an EBL automatic alignment mode. The method can realize that the error of the processing position is less than 500nm, and the angle error is less than 0.1 degree; the method has the advantages of fewer process steps, low cost and low error rate.

The invention aims to provide a method for processing a grating on a two-dimensional material, which comprises the following steps:

s1, marking by FIB processing alignment: etching 1 large cross mark and 4 small cross marks at a position 200 micrometers away from a to-be-processed area of the two-dimensional material by using FIB, wherein the etching depth is greater than 200nm, the period of the four small cross marks is 200 micrometers, the large cross mark is positioned at a position 300 micrometers above the left of the small cross mark, and when the marks are found in the subsequent EBL exposure, the large mark is found firstly;

s2, taking a picture by SEM: the direction of the 4 small cross marks is turned right, and the small cross marks and the area to be processed are moved to the same view field for photographing under a proper magnification;

s3, manufacturing a processing layout: firstly, drawing the 1 large cross mark and the 4 small cross marks in L-edge software, then guiding an SEM picture into the L-edge software, adjusting the size of a single pixel point of the SEM picture and the rotation angle of the picture, enabling each mark on the SEM picture to be overlapped with each corresponding mark in the layout, and drawing a graph needing to be processed at a position to be processed on the two-dimensional material in the SEM picture;

s4, preprocessing a film source: baking the sheet source on a hot plate at 180 ℃ for 5min, and then purging the sheet source by using a nitrogen gun to remove surface particle pollutants;

s5, gluing: spin-coating electron beam photoresist ZEP 520A by using a glue spreader, baking for 2min by using a hot plate at 180 ℃, and removing redundant solvent in the photoresist;

s6, EBL alignment: after a film source coated with photoresist is placed into EBL equipment, a large cross mark is firstly searched under a back scattering electron probe, then a small cross mark is found through the relative coordinates of the large cross mark and the small cross mark, and finally automatic alignment is carried out according to the relative coordinates of the small mark and the position to be processed;

s7, developing: development in ZEDN50 for 90S at room temperature followed by 30S fixation in IPA; baking at high temperature for 2min with a hot plate at 120 deg.C;

s8, RIE etching: RIE etching is carried out on the two-dimensional material with the photoresist pattern, Ar is used as gas, the flow is 25sccm, the bias power is 50W, and the time is 30s-1min, so that the photoresist pattern is transferred to the two-dimensional material;

s9, removing the photoresist: and (3) placing the film source into a degumming solution at 70 ℃ for static soaking for 10min-30min, and removing the photoresist on the surface.

Preferably, the two-dimensional material is molybdenum disulfide or tungsten diselenide.

Preferably, the large cross mark has a size of 200 micrometers by 10 micrometers.

Preferably, the small cross marks have a size of 100 micrometers by 5 micrometers.

The invention has the advantages and positive effects that:

the invention mainly aims at the two-dimensional material prepared by a mechanical stripping method, marks are directly etched on the periphery of a position to be processed by FIB, then SEM pictures including the marks and the position to be processed are led into drawing software, the relative coordinate and direction of the position to be processed can be visually judged according to the SEM pictures, and then a pattern is exposed in the area to be processed in an EBL automatic alignment mode. The method can realize that the error of the processing position is less than 500nm, and the angle error is less than 0.1 degree; the method has the advantages of fewer process steps, low cost and low error rate.

Drawings

FIG. 1 is a process flow diagram of a preferred embodiment of the present invention;

FIG. 2 is a schematic illustration of an overlay mark according to a preferred embodiment of the present invention;

wherein: 1. molybdenum disulfide; 2. a Si substrate; 3. overlaying a mark; 4. ZEP 520A; 5. exposing the pattern; 6. a grating; 7. marking a large cross; 8. small crosses are marked.

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:

as shown in fig. 1 and fig. 2, the technical solution of the present invention is:

a method for processing grating on two-dimensional material, the two-dimensional material is molybdenum disulfide or tungsten diselenide, take molybdenum disulfide as example here; the method comprises the following steps:

step one, FIB (Focused Ion Beam) processing alignment mark 3: 1 large cross mark 7(200 microns multiplied by 10 microns) and 4 small cross marks 8(100 microns multiplied by 5 microns) are etched at a position 200 microns away from a molybdenum disulfide 1 to-be-processed area on a silicon substrate 2 by using FIB, the etching depth cannot be too shallow, needs to be more than 200nm, and if the etching depth is too shallow, EBL (Electron Beam Lithography) cannot automatically detect the marks so as to influence the overlay accuracy. The processing process avoids the damage to the molybdenum disulfide caused by the sweeping of the ion beam. As shown in FIG. 2, the period of four small cross marks is 200 microns, so that the four small cross marks are processed in one writing field of FIB to ensure the accuracy of the period; the large cross mark is arranged at the position 300 microns above the small cross mark in the left direction, and when the mark is found in the subsequent EBL (100KV) exposure, the large cross mark is found first, so that the high-energy electron beam is prevented from scanning to the area to be exposed and damaging the pattern.

Step two, taking a picture by SEM (Scanning Electron Microscope): under SEM, 4 small cross marks are turned right as much as possible according to the direction shown in the attached figure 2, and the small cross marks and the area to be processed are moved to the same visual field to take a picture under a proper magnification.

Step three, manufacturing a processing layout: firstly, drawing 5 marks (1 large cross mark and 4 small cross marks) in the step 1 in L-edge software, then guiding an SEM picture into the L-edge software, adjusting the size of a single pixel point of the SEM picture and the rotation angle of the picture, enabling each mark on the SEM picture to be overlapped with each corresponding mark in a layout, and drawing a graph to be processed at a position to be processed on molybdenum disulfide in the SEM picture.

Step four, preprocessing a film source: and (3) baking the film source on a hot plate at 180 ℃ for 5min, and then blowing the film source by using a nitrogen gun to remove surface particle pollutants.

Step five, gluing: spin-coating electron beam photoresist ZEP 520A4 with a coater, and baking for 2min with a hot plate at 180 deg.C to enhance the stability and strength of the photoresist, and removing the excessive solvent in the photoresist.

Step six, EBL alignment: after a film source coated with photoresist is placed into EBL equipment, a large cross mark is searched under a back scattering electron probe, and the large cross mark is far away from a to-be-exposed area, so that high-energy electron beams can be prevented from scanning the to-be-exposed area to damage a pattern; then, the small cross mark is found through the relative coordinates of the large cross mark and the small cross mark, and finally, automatic overlay exposure is carried out according to the relative coordinates of the small cross mark and the position to be processed.

Step seven, developing: at room temperature, development was carried out for 90S in ZEDN50, followed by fixing for 30S in IPA, resulting in exposure pattern 5. In order to increase the etching resistance of the electron beam photoresist ZEP 520A and the stability of the overlay mark, high-temperature film hardening baking is carried out, and baking is carried out for 2min by using a hot plate at 120 ℃.

Step eight, RIE etching: and (3) RIE etching is carried out on the molybdenum disulfide with the photoresist pattern already made, the gas Ar is in a flow rate of 25sccm, the bias power is 50W, and the time is 30s-1min, so that the photoresist pattern is transferred onto the molybdenum disulfide, and the molybdenum disulfide grating 6 is obtained.

Step nine, removing the photoresist: and (3) placing the film source into a degumming solution at 70 ℃ for static soaking for 10min-30min, and removing the photoresist on the surface.

The method directly etches a mark on the periphery of the position to be processed through FIB, then introduces an SEM picture comprising the mark and the position to be processed into drawing software, can visually judge the relative coordinate and direction of the position to be processed according to the SEM picture, and then exposes a pattern in the area to be processed in an EBL automatic alignment mode. The method can realize that the error of the processing position is less than 500nm, and the angle error is less than 0.1 degree; the method has the advantages of fewer process steps, low cost and low error rate.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.