WO2021031106A1

WO2021031106A1 - Manufacturing method for surface relief grating structure

Info

Publication number: WO2021031106A1
Application number: PCT/CN2019/101517
Authority: WO
Inventors: 王晶
Original assignee: 诚瑞光学(常州)股份有限公司
Priority date: 2019-08-16
Filing date: 2019-08-20
Publication date: 2021-02-25
Also published as: CN110609344A; CN110609344B

Abstract

The present invention provides a manufacturing method for a surface relief grating structure. The method comprises processes of substrate glue-coating, motherboard imprinting, imprinting glue film-coating, imprinting glue removal and substrate etching. By directly imprinting a first grating structure on a motherboard to obtain a second grating structure, exposure and development processes in a manufacturing process of the grating structure are avoided, thereby simplifying production technology of the grating structure; and multiple daughterboards are successively produced by the one motherboard, multiple daughterboards can be simultaneously produced by multiple motherboards, and a mass production process of grating structures can be implemented. The imprinting glue film-coating process is additionally provided, a first metal film of an etching rate different from that of the substrate is selected, and when the substrate etching process is performed, power of an ion beam can be controlled to achieve an effect of accurately controlling substrate etching depth; and at the same time, an included angle of an emission line of the ion beam and a substrate surface is not a right angle, so that etching groove surfaces form inclined groove surfaces to obtain a target grating structure of which the substrate surface forms trapezoidal gaps.

Description

Manufacturing method of surface relief grating structure

Technical field

The invention relates to the field of grating production, in particular to a method for producing a surface relief grating structure.

Background technique

Gratings are important components of various types of spectral analysis instruments, and are increasingly used in emerging fields such as metrology, imaging, information processing, inherited optics and optical communications. In recent years, with the rapid development of semiconductor technology, a new type of optical application products has also developed, which is AR (augmented reality) products. AR is the enhancement of reality, the fusion of virtual images and real images. At present, most of the head-mounted AR devices on the market adopt the principle of optical projection, that is, realizing the fusion of real scenes and virtual scenes through lenses installed in front of the eyes. Among them, the Hololens product launched by Microsoft is currently on the market with the best experience. It uses a three-layer waveguide surface relief grating scheme, specifically through the design of three areas (incident area, expansion area, exit area). The incident area is coupled into the grating, and the light that has been collimated by the collimating lens is coupled into the waveguide to achieve total reflection. The higher the refractive index of the grating and the waveguide, the better; the expansion area is the function of the deflection grating, which changes the transmission direction of the light. To achieve the pupil expansion in the x direction, the efficiency does not need to be very high, but the efficiency needs to be designed higher as it propagates; the exit area realizes the pupil expansion in the y direction and couples the light out of the waveguide, which also increases with propagation.

The blazed grating shifts from the zero-order spectrum with no dispersion to the diffraction orders with other dispersions because the position of the maximum diffraction value is transferred. The efficiency is very high, and it is widely used in the incident area; tilted gratings are also often used in the incident and exit areas. . Due to the requirements of the grating in the extended area, the cross-section of the groove grating required can be designed as an asymmetric trapezoid. Due to the wide application of oblique gratings and blazed gratings, general patents involve their processing, but groove gratings with asymmetrical trapezoidal cross-sections have few applications and there is little research.

Grooved gratings have a wide range of uses. According to the cross-sectional shape, they are classified into steric gratings, blazed gratings, and echelon gratings. For the trapezoidal surface relief grating with asymmetrical cross-section, the traditional method is to first write directly by laser, then develop, and finally etch. Laser direct writing is to use a variable intensity laser beam to expose the variable amount of the resist material coated on the surface of the substrate, and form the desired relief contour on the surface of the resist layer after development. Because of its one-time molding and no discretization approximation, the manufacturing accuracy and diffraction efficiency of the device are greatly improved compared to devices made by traditional semiconductor technology.

However, the biggest problem of laser direct writing is that the contour depth cannot be precisely controlled. The contour depth of the processing is related to various factors such as exposure intensity, scanning speed, resist material, developing formula, ambient temperature and developing temperature. The influence of any one factor will cause contour depth errors. At present, it can only rely on the experience and Constant working conditions to control the depth error, low working efficiency and low controllability.

technical problem

The purpose of the present invention is to provide a method for manufacturing a surface relief grating structure with high efficiency and high controllability.

Technical solutions

The technical scheme of the present invention is as follows:

A method for manufacturing a surface relief grating structure includes the following steps:

Substrate coating: providing a substrate for manufacturing the grating structure, and coating an embossed adhesive layer on the surface of the substrate to obtain a substrate;

Motherboard embossing: provide a grating mother board, the grating mother board has a number of rectangular strip-shaped grating structures, the grating mother board is pressed into the embossing adhesive layer of the substrate by nano-imprinting, so that the The grating mother board is separated from the embossed adhesive layer to form a first grating structure, and a part of the embossed adhesive layer is etched to obtain a second grating structure with rectangular gaps;

Embossing glue coating: a metal film is plated on the surface of the second grating structure so that the metal film includes a first metal film plated on the surface of the remaining embossing glue layer and plated in the rectangular gap and located in the The second metal film layer on the substrate to obtain the third grating structure;

Imprinting glue removal: removing the first metal film layer and the remaining imprinting glue layer to obtain a fourth grating structure with a second metal film layer;

Etching the substrate: the second metal film layer on the fourth grating structure and the substrate are etched by an ion beam to obtain a target grating structure with trapezoidal gaps formed on the surface of the substrate, wherein the emission line of the ion beam The angle with the surface of the substrate is not a right angle.

Preferably, the step of gluing the substrate further includes the following processes:

Place the glued substrate on a heating plate to heat to remove excess solvent, and measure the thickness with a film thickness meter. If the thickness does not meet the specified requirements, continue to repeat the mother board glueing process until the measured thickness reaches the target thickness.

Preferably, in the mother board embossing step, the rectangular grating mother board needs to be subjected to an anti-sticking process before being pressed into the embossing adhesive layer.

Preferably, the following process is also included in the mother board imprinting step:

Removal of residual glue: the residual glue in the first grating structure is removed by an inductive coupling device, so that the bottom of the rectangular gap of the first grating structure is directly exposed to the substrate to obtain the second grating structure.

Preferably, in the step of embossing adhesive film coating, the etching rate of the metal film is different from the etching rate of the substrate.

Preferably, the step of removing the embossing glue specifically includes the following processes:

The remaining embossed adhesive layer is used as a sacrificial layer, and acetone or water is used to ultrasonically remove the remaining embossed adhesive layer and the first metal film layer plated on the surface of the remaining embossed adhesive layer.

Preferably, after the step of etching the substrate, the following process is also required:

Substrate cleaning: cleaning the second metal film layer that has not been etched away with an acid solution to form a grating structure with asymmetric trapezoidal gaps.

Preferably, the bottom width of the trapezoidal slit is 80-120 nm.

Preferably, the rectangular grating mother board is made of silicon or plastic.

Beneficial effect

The beneficial effects of the present invention are:

In the manufacturing process of the grating structure of the present invention, the first grating structure is obtained by directly imprinting the substrate on the mother board, which avoids the process of exposure and development during the manufacturing process of the grating structure, thereby simplifying the production process of the grating structure; Multiple daughter boards are produced successively, and multiple mother boards can produce multiple daughter boards at the same time, which can realize the mass production process of the grating structure. Adding the embossing rubber coating process, selecting the first metal film with a different etching rate from the substrate, during the substrate etching process, the power of the ion beam can be controlled to achieve the effect of accurately controlling the etching depth of the substrate; at the same time, the ion beam The angle between the emission line and the surface of the substrate is not right, so that the etched groove surface forms an inclined groove surface, so as to obtain a target grating structure with trapezoidal slits formed on the surface of the substrate. The ion beam etching efficiency of the present invention is high, is suitable for large-area processing and mass production use, is widely used, and has many equipment resources. Compared with the laser direct writing method, the pre-confirmed ion beam etching parameters are set, one-time molding, high efficiency and high controllability, the target grating structure can better meet the size requirements, and the operation is simpler.

Description of the drawings

Fig. 1 is a schematic flow chart of a method for manufacturing a surface relief grating structure according to the present invention;

2 is a schematic diagram of the target grating structure produced by the present invention;

3 is a partial enlarged schematic diagram of the substrate indicated by circle A in FIG. 2 of the present invention;

4 is a partial enlarged schematic diagram of the first grating structure indicated by circle B in FIG. 2 of the present invention;

5 is a partial enlarged schematic diagram of the second grating structure indicated by circle C in FIG. 2 of the present invention;

6 is a partial enlarged schematic diagram of the third grating structure indicated by circle D in FIG. 2 of the present invention;

7 is a partial enlarged schematic diagram of the fourth grating structure indicated by circle E in FIG. 2 of the present invention;

8 is a partial enlarged schematic diagram of the fifth grating structure indicated by circle F in FIG. 2 of the present invention;

9 is a partial enlarged schematic diagram of the target grating structure indicated by circle G in FIG. 2 of the present invention;

Figure 10 is a front view of the grating structure of the present invention;

Fig. 11 is a schematic diagram of the principle of ion beam etching of the present invention.

Embodiments of the invention

The present invention will be further described below with reference to the drawings and embodiments.

Please refer to Figures 1-2. The present invention discloses a method for manufacturing a surface relief grating structure, which includes the following steps:

Before applying the embossing layer, the substrate must be placed in the cleaning equipment, soaked in absolute ethanol and acetone to remove residual organic matter, and then rinsed and dried with a large amount of deionized water; the material of the substrate is generally Glass material.

S1. Substrate coating: Please refer to FIG. 3 further to provide a substrate 101 for making the grating structure. Coat the surface of the substrate 101 with an embossed adhesive layer 102 to obtain the substrate 11; coat a layer on the substrate 101 For embossing glue, when the glue concentration and spin-coating rate remain unchanged, the thickness of a single spin coating will not change. Therefore, it needs to be spin-coated multiple times to achieve a specific thickness; when the photoresist concentration is constant, the required film thickness The thicker, the faster the spin coating rate is required.

Place the glued substrate 101 on a heating plate to heat to remove excess solvent, and measure the thickness with a film thickness meter. If the thickness does not meet the specified requirements, continue to repeat the substrate 101 coating process until the measured thickness meets the specified requirements; The thermal baking process is mainly to achieve the uniformity of the thickness during the glue coating process.

S2. Motherboard imprinting: Please refer to Figure 4-5. Through precise alignment, complete the transfer of the motherboard graphics at the designated position of the substrate 101, and provide a grating mother board. The grating mother board has a number of rectangular strip-shaped grating structures. The grating mother board is pressed into the embossing adhesive layer 102 of the substrate 11 by nano-imprinting, so that the grating mother board is separated from the embossing adhesive layer 102 to obtain the first grating structure 12, and the first grating structure 12 needs to be removed by an inductive coupling device The residual glue in the first grating structure 12 directly exposes the bottom of the rectangular slit of the first grating structure 12 to the substrate 101 to obtain the second grating structure 13 with rectangular slits;

The embossing adhesive layer 102 is made of ultraviolet adhesive, which is anaerobic. Nitrogen must be introduced to drive off oxygen before embossing, and nitrogen must be continuously introduced to maintain a nitrogen atmosphere during exposure.

The demolding process after embossing is very important for embossing graphics. In order to facilitate the demolding of the grating mother board, the grating mother board generally needs to be treated with anti-sticking.

The anti-adhesion treatment process includes two methods: one is ozone treatment for 30 minutes to hydroxylate the surface of the grating mother board; the other is immersion in perfluorodecyltrichlorosilane for 24 hours.

S3. Imprinting adhesive coating: Please refer to FIG. 6 further. A metal film 103 with a different etching rate from that of the substrate 101 is vapor-deposited on the surface of the second grating structure 13 so that the metal film 103 is plated on the surface of the remaining imprinting adhesive layer 102 The first metal film layer 1031 and the second metal film layer 1032 plated in the rectangular gap and located on the substrate 101 to obtain the third grating structure 14;

Specifically, the first metal film layer 1031 is a metal chromium layer on the substrate base material by using a magnetron sputtering or an evaporation machine to prepare for etching. The etching rate of different materials is different. The etching rate ratio of the substrate 101 and the mask is called the selection ratio. The larger the selection ratio, the more favorable the etching of the substrate. Since the etching selection ratio between the substrate and the photoresist is too small, the pattern can not be transferred on the substrate 101, so a metal chromium layer needs to be evaporated.

S4. Imprinting glue removal: Please refer to FIG. 7 further to remove the first metal film layer 1031 and the remaining embossing glue layer 102 to obtain a fourth grating structure 15 with a second metal film layer 1032; to use the remaining embossing glue layer 102 As the sacrificial layer, acetone or water is used to ultrasonically remove the remaining embossed adhesive layer 102 and the first metal film layer 1031 plated on the surface of the remaining embossed adhesive layer 102. Specifically, after ultrasonic treatment, the embossed adhesive layer 102 and the first The metal film layer 1031 is separated from the substrate 101 and can be removed after further cleaning. In this way, the second metal film layer 1032 becomes a mask for the substrate 101.

S5. Etching the substrate 101: Please further refer to Figs. 8-10, the second metal film layer 1032 on the fourth grating structure 15 and the substrate 101 are etched by ion beam to obtain the fifth grating structure 16, which is cleaned with an acid solution The second metal film layer 1032 that has not been etched away obtains a target grating structure with trapezoidal slits formed on the surface of the substrate 101, wherein the angle between the emission line of the ion beam and the surface of the substrate 101 is not right.

According to the etching rate of the substrate 101 and the etching rate of the second metal film layer 1032, the corresponding power is controlled, and the fourth grating structure 15 is etched using inductively coupled reactive ion etching equipment. At this time, it is in the second metal film layer 1032. The part of the substrate 101 that is not covered by the second metal film layer 1032 is simultaneously etched to obtain the fifth grating structure 16 until the substrate 101 reaches the target etching depth to obtain the target grating structure.

The gas type and power of the inductively coupled reactive ion etching equipment can be precisely controlled. As long as the selection ratio between the substrate 101 and the second metal film layer 1032 can be confirmed, the optimal control power can be calculated to achieve The etching depth of the target ultimately controls the etching depth and transfers the complete grating structure.

In an embodiment of the present invention, in the step of etching the substrate 101, the process of realizing the non-right angle between the emission line of the ion beam and the surface of the developed substrate 101 includes: fixing the substrate 101 and controlling the ion The beam is rotated by a preset angle, so that the emission line of the ion beam is irradiated into the surface of the substrate 101 obliquely.

In another embodiment of the present invention, in the step of etching the substrate 101, the process of realizing the non-right angle between the emission line of the ion beam and the surface of the substrate 101 includes: fixing the ion beam and controlling the rotation of the substrate 101 The preset angle makes the emission line of the ion beam irradiate the surface of the substrate 101 obliquely.

In this embodiment, by controlling the inclination angle of the emission line of the ion beam and the etching line width of the metal film layer, the width of the bottom of the trapezoidal gap can reach the accuracy requirement between 80-120nm, and the controllability is high. The quality of the target grating structure completed by etching is better.

Please further refer to FIG. 11, the emission line of the ion beam is irradiated obliquely into the surface of the substrate 101, the second metal film layer 1032 on the surface of the substrate 101 is a rectangular film layer, and the substrate 101 that is not blocked by the second metal film layer 1032 corresponds to The ion beam etching rate at the position is the same and the deepest, forming the bottom of the etching gap; the emission line irradiated on the sidewall of the second metal film layer 1032, due to the gradual change in the thickness of the second metal film layer 1032 etched by the ion beam, in the first The surface of the substrate 101 after the etching of the second metal film layer 1032 is etched to form a first oblique angle of the slit sidewall; part of the emission line irradiates the surface of the second metal film layer 1032 and penetrates the sidewall of the second metal film layer 1032, Since the thickness of the second metal film layer 1032 etched by the ion beam is gradually changed and the etching efficiency is different from that of directly irradiating the sidewall of the second metal film layer 1032, the surface of the substrate 101 after the second metal film layer 1032 is etched Etching forms the sidewall of the gap with the second inclined angle. The first oblique angle of the slit side wall, the second oblique angle of the slit side wall and the bottom of the slit form a complete asymmetric trapezoidal slit.

In the manufacturing process of the grating structure of the present invention, the first grating structure 12 is obtained by directly imprinting the substrate 11 on the mother board, which avoids the exposure and development process in the manufacturing process of the grating structure, thereby simplifying the production process of the grating structure; The mother board produces multiple daughter boards successively, and multiple mother boards can produce multiple daughter boards at the same time, which can realize the mass production process of the grating structure. Adding the imprinting glue coating process, selecting the first metal film with a different etching rate from the substrate 101, during the substrate 101 etching process, the power of the ion beam can be controlled to achieve the effect of accurately controlling the etching depth of the substrate 101 ; At the same time, the angle between the emission line of the ion beam and the surface of the substrate 101 is not right, so that the etching groove surface forms an inclined groove surface, so as to obtain a target grating structure with trapezoidal gaps formed on the surface of the substrate 101. The ion beam etching efficiency of the present invention is high, is suitable for large-area processing and mass production use, is widely used, and has many equipment resources. Compared with the laser direct writing method, the pre-confirmed ion beam etching parameters are set, one-time molding, high efficiency and high controllability, the target grating structure can better meet the size requirements, and the operation is simpler.

The above are only the embodiments of the present invention. It should be pointed out here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present invention, but these are all protected by the present invention. range.

Claims

A method for manufacturing a surface relief grating structure is characterized in that it comprises the following steps:

Substrate coating: providing a substrate for manufacturing the grating structure, and coating an embossed adhesive layer on the surface of the substrate to obtain a substrate;

Motherboard embossing: provide a grating mother board, the grating mother board has a number of rectangular strip-shaped grating structures, the grating mother board is pressed into the embossing adhesive layer of the substrate by nano-imprinting, so that the The grating master is separated from the embossed adhesive layer to form a first grating structure, and a part of the embossed adhesive layer is etched to obtain a second grating structure with rectangular gaps;

Embossing glue coating: a metal film is plated on the surface of the second grating structure so that the metal film includes a first metal film plated on the surface of the remaining embossing glue layer and plated in the rectangular gap and located in the The second metal film layer on the substrate to obtain the third grating structure;

Imprinting glue removal: removing the first metal film layer and the remaining imprinting glue layer to obtain a fourth grating structure with a second metal film layer;

Etching the substrate: the second metal film layer on the fourth grating structure and the substrate are etched by an ion beam to obtain a target grating structure with trapezoidal gaps formed on the surface of the substrate, wherein the emission line of the ion beam The angle with the surface of the substrate is not a right angle.
The method for manufacturing a surface relief grating structure according to claim 1, wherein the step of applying glue to the substrate further comprises the following process:

Place the glued substrate on a heating plate to heat to remove excess solvent, and measure the thickness with a film thickness meter. If the thickness does not meet the specified requirements, continue to repeat the mother board glueing process until the measured thickness reaches the target thickness.
The method for manufacturing a surface relief grating structure according to claim 1, wherein in the mother board embossing step, an anti-sticking treatment process is required before the rectangular grating mother board is pressed into the embossing adhesive layer.
The method for manufacturing a surface relief grating structure according to claim 1, wherein the step of embossing the mother board further comprises the following process:

Removal of residual glue: the residual glue in the first grating structure is removed by an inductive coupling device, so that the bottom of the rectangular gap of the first grating structure is directly exposed to the substrate to obtain the second grating structure.
2. The method for manufacturing a surface relief grating structure according to claim 1, wherein in the step of embossing the film, the etching rate of the metal film is different from the etching rate of the substrate.
The method for manufacturing a surface relief grating structure according to claim 1, wherein the step of removing the embossing glue specifically includes the following processes:

The remaining embossed adhesive layer is used as a sacrificial layer, and acetone or water is used to ultrasonically remove the remaining embossed adhesive layer and the first metal film layer plated on the surface of the remaining embossed adhesive layer.
The method for manufacturing a surface relief grating structure according to claim 1, wherein after the step of etching the substrate, the following process is also required:

Substrate cleaning: cleaning the second metal film layer that has not been etched away with an acid solution to form a grating structure with asymmetric trapezoidal gaps.
The method for manufacturing a surface relief grating structure according to claim 1, wherein the bottom width of the trapezoidal slit is 80-120 nm.
The method for manufacturing a surface relief grating structure according to claim 1, wherein the material of the rectangular grating mother board is silicon wafer or plastic sheet, and the material of the substrate is glass sheet.