阅读说明：本技术 基于扫描原子光刻技术的大面积自溯源光栅制备方法 (Large-area self-tracing grating preparation method based on scanning atomic lithography technology ) 是由 邓晓 程鑫彬 谭文 唐朝辉 林子超 李同保 于 2021-08-30 设计创作，主要内容包括：本发明涉及一种基于扫描原子光刻技术的大面积自溯源光栅制备方法,其特征在于,包括以下步骤：基于原子光刻技术,采用原子束和激光会聚驻波场的相互作用,在基板上进行局部自溯源光栅结构制备；使用道威棱镜控制所述激光会聚驻波场沿垂直于光栅沟槽方向扫描沉积区域,逐步实现沉积区域自溯源光栅全局覆盖,形成大面积自溯源光栅。与现有技术相比,本发明克服了由于汇聚能量密度降低导致的光栅边缘粗化等问题,具备操作简便,光栅面积扩展空间大的优点。(The invention relates to a method for preparing a large-area self-tracing grating based on a scanning atomic lithography technology, which is characterized by comprising the following steps of: based on an atomic photoetching technology, the local self-tracing grating structure is prepared on a substrate by adopting the interaction of an atomic beam and a laser convergence standing wave field; and controlling the laser convergence standing wave field to scan the deposition area along the direction vertical to the grating groove by using the dove prism, and gradually realizing the global coverage of the self-tracing grating of the deposition area to form the large-area self-tracing grating. Compared with the prior art, the invention overcomes the problems of grating edge coarsening and the like caused by the reduction of the concentration energy density, and has the advantages of simple and convenient operation and large grating area expansion space.)

1. A large-area self-tracing grating preparation method based on a scanning atomic lithography technology is characterized by comprising the following steps:

based on an atomic photoetching technology, the local self-tracing grating structure is prepared on a substrate by adopting the interaction of an atomic beam and a laser convergence standing wave field;

and controlling the laser convergence standing wave field to scan the deposition area along the direction vertical to the grating groove by using the dove prism, and gradually realizing the global coverage of the self-tracing grating of the deposition area to form the large-area self-tracing grating.

2. The method for preparing the large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1, wherein the process of preparing the local self-tracing grating structure comprises:

heating metal powder to a sublimation state in a vacuum environment, leading out an atomic beam in a leakage flow mode, and collimating the atomic beam;

and carrying out space periodic distribution regulation and control on the collimated atomic beams through a laser convergence standing wave field, and depositing periodically arranged atoms on the substrate to form a local self-tracing grating structure, wherein the atomic beam propagation direction is vertical to the laser standing wave field propagation direction.

3. The method for preparing a large-area self-tracing grating based on scanning atomic lithography as claimed in claim 2, wherein the atomic beam is ejected through a slit or a transverse laser optical field to achieve collimation of the atomic beam.

4. The method for preparing a large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein the atomic beam element is any one of chromium, iron, sodium, aluminum and ytterbium.

5. The method for preparing a large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein said substrate comprises single crystal silicon, glass ceramics or indium phosphide material.

6. The method for preparing the large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein the laser convergence standing wave field is formed by overlapping incident light passing through the dove prism and reflected light returning along the original path after passing through the reflector, and during the scanning process, the node of the laser convergence standing wave field is always on the mirror surface of the reflector.

7. The method for preparing the large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein the atomic beam furnace temperature, the total power of the convergent light, the frequency detuning amount of the convergent light, the light cutting ratio of the convergent light to the substrate, and the atomic beam transverse cooling effect are all kept consistent in the preparation process.

8. The method for preparing a large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 7, wherein the ratio of the convergent light to the substrate light-cutting is 10% -50%.

9. The method for preparing the large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein the dove prism is arranged on a displacement table with a vertical micro-displacement adjusting function.

10. The method for preparing the large-area self-tracing grating based on the scanning atomic lithography technology as claimed in claim 1 or 2, wherein the moving range of the dove prism is more than 50% of the width of the atomic beam deposition area.

Technical Field

The invention relates to the technical field of atomic lithography, in particular to a method for preparing a large-area self-tracing grating based on a scanning atomic lithography technology.

Background

The physicochemical, transfer and multiplexing processes of the natural constants can effectively improve the accuracy and precision of the advanced manufacturing process. In 2019, the major change of international unit system requires that all basic units are changed into natural constant definitions, so that the accuracy of magnitude tracing is effectively improved, and magnitude transmission flattening is realized. In the field of nano manufacturing, the nano grating plays an important role in the aspects of precision displacement measurement, instrument calibration and the like, and is one of the basic supports for nano-scale precision measurement. The self-tracing grating refers to a grating in which some key parameters of the grating can be directly traced to a natural reference. The grating can complete tracing, so that the method has extremely high accuracy, uniformity and consistency. At present, the main preparation methods of the self-tracing grating include an atomic lithography technology, a hydrogen passivation type silicon surface STM lithography technology and the like.

The atomic lithography technology mainly utilizes the dipole force of the laser standing wave field to the atoms to control the atom movement, so that the cooled atom beams form a periodic grating structure on the substrate after passing through the laser standing wave field. According to the difference of the frequency detuning quantity of the standing wave field of the laser, the atom beams which are pre-collimated converge towards the wave crest (corresponding to negative detuning) or the wave trough (corresponding to positive detuning) of the standing wave to form the phenomenon of channeling of the atom beams. According to different light field distributions of the laser standing wave field, a one-dimensional nano grating and a two-dimensional lattice structure can be respectively deposited. Because the period of the grating is directly determined by the laser wavelength locked by the atomic energy level transition frequency, the natural constant can be directly traced, the method has the characteristic of self-tracing, and the accuracy and the consistency are extremely high. Taking a chromium atom lithography grating as an example, the one-dimensional self-tracing chromium grating with the period of 212.8nm is verified to have the accuracy and consistency of 0.001 nm. The extremely high accuracy is of great significance to the calibration and displacement measurement of precision instruments.

However, the small area of the atomic lithography grating structure limits the convenience of application in the critical field to some extent. Also taking a chromium self-tracing grating as an example, the grating area is generally about 2mm × 0.25mm (wherein 0.25mm is the gaussian area). The area is mainly determined by laser standing wave field beam parameters, and as atom convergence needs a certain energy density threshold, the energy density is reduced by a method of expanding beams under the condition of certain laser power, and further the line edge roughness of the grating is coarsened, so that the accuracy of the grating is reduced. Meanwhile, a large number of atoms along the gaussian direction fail to interact with the laser beam during deposition, resulting in a large waste of atomic flux in the deposition area. The small area of the self-tracing grating causes the wide application of the self-tracing grating to be limited. For example, when a two-dimensional self-tracing grating structure is developed by using step-by-step deposition atomic lithography, the overlapping difficulty is extremely high and the yield is low due to the small width of the Gaussian direction; for another example, in the process of developing a grating interferometer by using a self-tracing grating, the small area will cause the interference phenomenon to have low signal-to-noise ratio, and it is difficult to improve the signal purity and accuracy.

Based on the current situation, the existing method is difficult to meet the preparation requirement of the large-area self-tracing grating, so that the development of the preparation method of the large-area self-tracing grating (especially the width in the Gaussian direction) is extremely necessary.

Disclosure of Invention

The invention aims to provide a large-area self-tracing grating preparation method based on a scanning atomic lithography technology, which is simple and convenient to operate and large in grating area expansion space, and aims to solve the problem that the accuracy is reduced due to the existing self-tracing grating area expansion method.

The purpose of the invention can be realized by the following technical scheme:

a large-area self-tracing grating preparation method based on a scanning atomic lithography technology comprises the following steps:

based on an atomic photoetching technology, the local self-tracing grating structure is prepared on a substrate by adopting the interaction of an atomic beam and a laser convergence standing wave field;

and controlling the laser convergence standing wave field to scan the deposition area along the direction vertical to the grating groove by using the dove prism, and gradually realizing the global coverage of the self-tracing grating of the deposition area to form the large-area self-tracing grating.

Further, the process of preparing the local self-tracing grating structure comprises:

heating metal powder to a sublimation state in a vacuum environment, leading out an atomic beam in a leakage flow mode, and collimating the atomic beam;

and carrying out space periodic distribution regulation and control on the collimated atomic beams through a laser convergence standing wave field, and depositing periodically arranged atoms on the substrate to form a local self-tracing grating structure, wherein the atomic beam propagation direction is vertical to the laser standing wave field propagation direction.

Further, the atom beam is ejected through a slit or a transverse laser light field to achieve collimation of the atom beam.

Further, the atomic beam element is any one of chromium, iron, sodium, aluminum, and ytterbium.

Further, the substrate comprises monocrystalline silicon, microcrystalline glass or an indium phosphide material.

Furthermore, the laser convergence standing wave field is formed by superposing incident light passing through the dove prism and reflected light returning according to an original path after passing through the reflector, and a wave node of the laser convergence standing wave field is always on the mirror surface of the reflector in the scanning process.

Further, the atomic beam furnace temperature, the total power of the convergent light, the frequency detuning amount of the convergent light, the light cutting ratio of the convergent light and the substrate, and the atomic beam transverse cooling effect are kept consistent in the preparation process.

Further, the ratio of the convergent light to the cut light of the substrate is 10% to 50%.

Furthermore, the dove prism is arranged on a displacement table with a vertical micro-displacement adjusting function.

Further, the dove prism moving range is larger than 50% of the width of the atomic beam deposition area.

Compared with the prior art, the invention has the following beneficial effects:

1. on the basis of the atomic lithography technology, the laser convergence standing wave field is controlled by using the dove prism to scan the deposition area along the direction vertical to the grating groove, the continuity of each grating and the parallelism between the gratings can be ensured while the area expansion of the self-tracing grating is realized, the grating edge is smooth, the atomic flux of all the deposition areas is fully utilized, and the grating with the expanded area has extremely small uncertainty.

2. In the preparation process, only the laser convergence standing wave field is controlled to move along the direction vertical to the grating groove, other parameters are unchanged, the energy density of the laser convergence standing wave field is not reduced, and the overall accuracy of the grating structure area is ensured.

3. On the basis of ensuring the cooling quality, the dimension of the self-tracing grating obtained by the preparation method is expected to be expanded to the centimeter magnitude.

Drawings

FIG. 1 is a schematic view of an implementation of the preparation process of the present invention;

FIG. 2 is a schematic diagram illustrating a principle of manufacturing a local self-tracing grating structure;

FIG. 3 is a schematic diagram of grating parallelism in a scanning atomic lithography process;

FIG. 4 is a typical image (AFM image) of the local structure of the large-area self-tracing grating obtained by the present invention;

FIG. 5 is a peak-to-valley height distribution diagram of the large-area self-tracing grating obtained by the present invention along the Gaussian direction;

in the figure, 1, a convergent light, 2, a reflector, 3, an atomic beam, 4, a substrate, 5, a node position, 6, a dove prism, 7, a moving direction, 8, a grating line, 9, a one-dimensional atomic photoetching grating, 10 and a laser convergent standing wave field.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

In the process of developing the self-tracing grating by atomic lithography, the nodes of the standing wave field are always on the mirror surface of the main reflector, and the characteristic can be kept even in the process of moving up and down, so that a technical foundation is laid for realizing the development of the large-area self-tracing grating by a scanning method. The present invention has been made based on this finding.

The invention provides a large-area self-tracing grating preparation method based on a scanning atomic lithography technology, which comprises a local grating generation step and a global large-area grating scanning formation step, and specifically comprises the following steps:

based on an atomic photoetching technology, the local self-tracing grating structure is prepared on a substrate by adopting the interaction of an atomic beam and a laser convergence standing wave field;

and the dove prism is used for controlling the laser convergence standing wave field to slowly scan the deposition area along the direction vertical to the grating groove, the laser frequency and the light cutting proportion are kept stable in the process of scanning the laser standing wave field, the overall coverage of the self-tracing grating in the deposition area is gradually realized, and the large-area self-tracing grating is formed.

The preparation method is realized by the principle schematic diagram shown in fig. 1, a convergent light 1 (i.e. incident light) passing through a dove prism 6 and reflected light returning according to an original path after passing through a reflector 2 are superposed to form a laser convergent stationary wave field 10, the plane of the reflector is the position 5 of a wave node of the stationary wave field, and the wave node of the laser convergent stationary wave field is always on the mirror surface of the reflector in the scanning process. Based on the atomic lithography technology, the interaction of the atomic beam 3 and the laser convergence standing wave field 10 is adopted to form a local self-tracing grating structure on the substrate 4, the dove prism 6 moves up and down along the moving direction 7, and the height of the laser convergence standing wave field 10 changes along with the movement, so that the self-tracing grating global coverage in the deposition area is realized, and the large-area self-tracing grating is formed. Because the dove prism only changes the height of the standing wave field without changing other conditions, the position of the formed grating can be changed along with the change of the height of the convergent light, and the grating lines 8 before and after the change are completely continuous and parallel. By scanning the height of the standing wave field, the scanning area is larger than or equal to the slit area, so that the grating covers the substrate with the whole slit area.

As shown in fig. 2, the process of preparing the local self-tracing grating structure specifically includes:

(1) heating metal powder to a sublimation state in a vacuum environment and leading out an atomic beam 3 in a leakage manner;

(2) spraying an atom beam through a slit or a transverse laser light field to realize the collimation of the atom beam, namely the limitation of transverse speed;

(3) the collimated atomic beams are subjected to space periodic distribution regulation and control through a laser convergent standing wave field, periodically distributed atoms are deposited on a substrate to form a local self-tracing grating structure which is a one-dimensional atomic photoetching grating 9, the atomic beam propagation direction is perpendicular to the laser standing wave field propagation direction, and the laser convergent standing wave field is formed by overlapping two convergent light beams 1.

In the preparation process, the furnace temperature of the atomic beam, the total power of the convergent light, the frequency detuning amount of the convergent light, the light cutting proportion of the convergent light and the substrate and the transverse cooling effect of the atomic beam are kept consistent, wherein the light cutting proportion of the convergent light and the substrate is 10-50%.

Fig. 3 is a schematic diagram showing the parallelism of the grating in the above-mentioned manufacturing process. The convergent light 1 has a phase difference of pi after being reflected by the reflector 2, the reflected light and the original light field are interfered and superposed to form a standing wave field at the mirror surface, and the plane where 5 is located in fig. 3 is a node position. Because the wave node is always positioned on the mirror surface when the standing wave field moves up and down, the grating lines 8 formed by scanning the standing wave field up and down can be ensured to be continuous and completely parallel.

In the above preparation method, the atomic beam element is any one of chromium, iron, sodium, aluminum, and ytterbium. Substrates include, but are not limited to, single crystal silicon, microcrystalline glass, or indium phosphide materials.

In the preparation method, the dove prism is arranged on a displacement table with a vertical micro-displacement adjusting function, and the height of the laser emitted by the dove prism is changed by controlling the movement of the displacement table in the vertical direction, so that the scanning of a laser standing wave field in the direction vertical to the grating groove is realized. Optionally, the dove prism movement range is greater than 50% of the width of the atomic beam deposition region.

Examples

The metal atomic beam adopted by the embodiment is chromium (Cr), and the preparation method of the large-area self-tracing grating adopting chromium comprises the following steps:

(1) heating the crucible filled with the chromium powder to 1550-1650 ℃ in a vacuum environment to enable the crucible to reach a sublimation state, and forming a metal atom beam.

(2) The Cr atomic beam is collimated, i.e. limited in lateral velocity.

In this example, the atomic beam emitted from the high temperature atomic furnace was collimated by a small hole having a radius of 5mm and a slit having a size of 3mm × 1.5mm, and the size was also 3mm × 1.5 mm.

(3) The collimated Cr atomic beam is interacted with a laser convergence standing wave field orthogonal to the collimated Cr atomic beam, an atomic deposition substrate 4 is placed at a proper position away from the laser standing wave field, and is deposited on the substrate 4 under the action of a dipole force, and an atomic lithography grating with the pitch of 212.8nm, namely a one-dimensional deposition grating structure, is formed on the substrate 4, as shown in FIG. 2.

The wavelength of the converged laser is 425.6nm, and the resonance transition energy level corresponding to Cr atoms isThe focused laser frequency is tuned to a positive detuning (+250MHz) or negative detuning (-250MHz) position of the resonance level corresponding to the center frequency. Therefore, the period of the formed one-dimensional chromium (Cr) atomic photoetching grating structure is half of the wavelength of the used laser and is 212.8 nm. In addition, during the preparation process, the convergent laser is limited within 50% by the cutting proportion of the template. The substrate is typically silicon or indium phosphide material.

(4) And moving the dove prism 6 up and down to change the height of the standing wave field, controlling the laser convergence standing wave field to scan the deposition area along the direction vertical to the grating groove, and gradually realizing the global coverage of the self-tracing grating of the deposition area to form the large-area self-tracing grating.

FIG. 4 is a typical image (AFM image) of the local structure of a large-area self-tracing grating, in which the grating is strictly parallel, continuous and smooth, and the grating extends over a 3mm × 1.5mm area, and the image clearly reflects that the large-area self-tracing grating structure developed by using the scanning atomic lithography method has good uniformity.

Fig. 5 is a peak-to-valley height profile along the gaussian direction for a large area self-tracing grating developed based on scanning atomic lithography. As can be seen, the grating extends to 1500 microns in gaussian area, which is 6 times larger than the original 250 micron beam waist area. Moreover, the grating peak-to-valley heights are all over 10nm over a 1500 micron span.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.