CN117923767A - Stacked hot pressing method and stacked hot pressing device - Google Patents

Abstract

The invention belongs to the technical field of glass hot pressing, and particularly relates to a stacked hot pressing method and a stacked hot pressing device. The stacked hot pressing method comprises the following steps: heating, namely placing the lower die holder on a heating structure, sequentially stacking a plurality of templates along the vertical direction, and arranging a glass wafer between any two adjacent templates; heating each glass wafer to a preset temperature in a vacuum environment or an inert gas environment by a heating structure; hot pressing, wherein the upper die head is pressed against the templates towards the lower die base by using the driving structure so as to copy the micro-nano structure on each glass wafer; cooling, cooling the temperature of each glass wafer at a predetermined cooling rate; and demolding and taking out each glass wafer formed by hot pressing. The invention can improve the hot pressing efficiency of the glass wafer.

Description

Stacked hot pressing method and stacked hot pressing device

Technical Field

The invention belongs to the technical field of glass hot pressing, and in particular relates to a stacked hot pressing method and a stacked hot pressing device.

Background technique

Glass micro-nano structure devices such as micro-nano optical elements, micro-opto-electromechanical systems (MOEMS), and microfluidic chips have the advantages of miniaturization, integration, high sensitivity, and low power consumption, and are widely used in the fields of new generation optical systems, information communication, mechanical electronics, biochemistry, etc. In recent years, with the development of society and the iteration of technology, glass micro-nano structure devices not only have higher and higher shape accuracy requirements, but also have an increasing demand. Breakthroughs in the high-precision, high-efficiency, and low-cost manufacturing technology of glass micro-nano structures have become a major demand in the field of micro-nano manufacturing.

At present, the manufacturing methods of glass micro-nano structure devices include micro-milling technology, ultra-precision grinding technology, laser direct writing technology, ultraviolet lithography technology, ion beam lithography technology, electron beam lithography technology and hot embossing technology. Among them, hot embossing technology has the advantages of cross-micro-nano scale manufacturing, high surface replication fidelity, high manufacturing efficiency, flexible process, low carbon and environmental protection. Moreover, combined with ultra-precision mold processing technology, hot embossing technology is expected to become an effective way to solve the high-efficiency and low-cost manufacturing of high-quality glass micro-nano structure devices.

However, the current transmission hot pressing method is generally single-device forming, and only one glass wafer can be hot pressed at a time, resulting in low manufacturing efficiency.

Summary of the invention

The purpose of the embodiments of the present application is to provide a stacked hot pressing method, aiming to solve the problem of how to improve the efficiency of glass wafer molding.

To achieve the above purpose, the technical solution adopted in this application is:

In a first aspect, a stacking hot pressing method is provided for hot pressing a glass wafer, the stacking hot pressing method comprising the following steps:

Prepare a lower die base, an upper die head located above the lower die base, and a template having a micro-nano structure and located on the lower die base;

Heating, placing the lower mold base on the heating structure, multiple templates are stacked in sequence along the vertical direction, and a glass wafer is arranged between any two adjacent templates; the heating structure heats each glass wafer to a predetermined temperature in a vacuum environment or an inert gas environment;

Hot pressing, using a driving structure to make the upper die head press each of the templates toward the lower die base, so that each of the glass wafers replicates the micro-nano structure;

Cooling, cooling the temperature of each of the glass wafers at a predetermined cooling rate;

The mold is released to take out each of the glass wafers formed by heat pressing.

In some embodiments, the micro-nano structure includes a micro-structure having a size on the micrometer scale and/or a nano-structure having a size on the nanometer scale.

In some embodiments, the size of the micro-nano structures on each of the templates decreases from bottom to top.

In some embodiments, the micro-nano structure is located on the surface of the template facing upward.

In some embodiments, a positioning sleeve having a forming cavity is prepared, the upper die head is adapted to the forming cavity and is partially slidably disposed in the forming cavity, and each of the templates is placed in the forming cavity.

In some embodiments, the driving structure includes a force-applying component and a lifting platform located below the force-applying component and connected to the heating structure, the force-applying component includes a first-stage gravity unit slidably arranged in a vertical direction and connected to the upper die head, and a second-stage gravity unit slidably arranged in a vertical direction and located above the first-stage gravity unit; the hot pressing step includes the following steps:

S21: the lifting platform drives the lower die base to move upward by a first distance, and the upper die head abuts against the first-stage gravity unit, so that the first-stage gravity unit is loaded on the upper die head;

S22: The lifting platform drives the lower die base to continue to move upward by a second distance, so that the first-stage gravity unit and the second-stage gravity unit are both loaded on the upper die head.

The demoulding step comprises the following steps:

S31: the lifting platform drives the lower mold base to move downward by the second distance, so that the lower mold base unloads the stamping force of the second-stage gravity unit while retaining the stamping force of the first-stage gravity unit;

S32: the lifting platform drives the lower mold base to continue to move downward by the first distance, so that the lower mold base unloads the stamping force of the first-stage gravity unit.

In some embodiments, the stacked hot pressing method is characterized in that: in the step S31, the upper mold head and each glass wafer are cooled at a first cooling rate; in the step S32, the upper mold head and each glass wafer are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate.

In some embodiments, the force-applying assembly further includes a support frame, and the first-stage gravity unit and the second-stage gravity unit are both slidably connected to the support frame.

In a second aspect, a stacked hot pressing device is provided, which is used to implement the stacked hot pressing method.

The beneficial effect of the present application is that the stacked hot pressing method arranges multiple templates in layers, and a glass wafer is arranged between any two adjacent templates, so that multiple glass wafers are stacked, and then the upper mold head is pressed against the lower mold base by a driving structure. The glass wafer is at the glass transition temperature, so that the micro-nano structure on the template can be replicated, and multiple glass wafers can be formed by one hot pressing, thereby improving the hot pressing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or exemplary technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a flow chart of a stacked hot pressing method provided in an embodiment of the present application;

FIG2 is a schematic diagram of a curve showing changes in temperature, pressure and displacement of a glass wafer in the stacked hot pressing method of FIG1 ;

FIG3 is a schematic diagram of the three-dimensional structure of a stacked hot pressing device provided in another embodiment of the present application;

FIG4 is a schematic diagram of the three-dimensional structure of an upper die head and a positioning sleeve provided in another embodiment of the present application;

FIG5 is a schematic cross-sectional view of FIG4 ;

FIG. 6 is a schematic structural diagram of the force applying assembly of FIG. 3 .

Among them, the reference numerals in the figure are:

100, stacked hot pressing device; 101, hot pressing box; 111, vacuum chamber; 200, driving structure; 201, force application component; 202, lifting platform; 300, heating structure; 2011, first-stage gravity unit; 2012, second-stage gravity unit; 2013, guide column; 2014, pressure ball; 401, positioning sleeve; 402, upper die head; 403, template; 404, glass wafer; 405, lower die base; 406, concave cavity; 211, first slide plate; 210, first weight; 221, second slide plate; 220, second weight;

Detailed ways

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present application.

It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of description, and does 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 cannot be understood as a limitation on the present application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "first" and "second" are only used for the purpose of convenience of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

Please refer to Figures 1 to 3. An embodiment of the present application provides a stacked hot pressing method and a stacked hot pressing device for implementing the same. The stacked hot pressing method is used to hot press a glass wafer 404. The glass wafer 404 is an optical glass wafer 404, which has excellent optical transparency and thermal stability and is widely used in optical device manufacturing and optoelectronics fields, such as lasers, fiber optic communication devices, etc.

Referring to FIG. 1 and FIG. 2 , the stacking hot pressing method includes the following steps:

Please refer to Figures 1 and 2, prepare a lower mold base 405, an upper mold head 402 located above the lower mold base 405, and a template 403 with a micro-nano structure and located on the lower mold base 405; place the lower mold base 405, the upper mold head 402 and the template 403 in a vacuum environment or an inert gas environment, for example, prepare a hot press box 101, the hot press box 101 has a vacuum chamber 111, the vacuum chamber 111 can be evacuated or filled with inert gas, and then the lower mold base 405, the upper mold head 402 and the template 403 are placed in the vacuum chamber 111.

S1: Heating, placing the lower mold base 405 on the heating structure 300, multiple templates 403 are stacked in sequence along the vertical direction, and a glass wafer 404 is arranged between any two adjacent templates 403, so that multiple glass wafers 404 are stacked; the heating structure 300 heats each glass wafer 404 to a predetermined temperature in a vacuum environment or an inert gas environment, and keeps the temperature constant so that the temperature of each glass wafer 404 is uniform; the predetermined temperature is the TG temperature of the glass wafer 404, that is, the glass transition temperature. The glass transition temperature refers to the temperature at which the glass material changes from a brittle state to a tough state. For example, the glass transition temperature of BK7 is about 550 degrees.

It can be understood that the heating structure 300 heats each of the glass wafers 404 , the template 403 and the lower mold base 405 to the glass transition temperature.

S2: Hot pressing, using the driving structure 200 to make the upper mold head 402 press each of the templates 403 toward the lower mold base 405, so that each of the glass wafers 404 replicates the micro-nano structure of the corresponding template 403; the driving structure 200 makes the upper mold head 402 and the lower mold base 405 press in both directions, so that compressive stress is applied to each glass wafer 404.

S3: Cooling, cooling the temperature of each of the glass wafers 404 at a predetermined cooling rate, so that the glass wafer 404 with the microstructure replicated thereon is annealed. The temperature of the glass wafer 404 can be slowly reduced by reducing the heating power of the heating structure 300. The cooling rate can be 20 degrees/minute or 50 degrees/minute, which can be selected according to actual conditions and is not limited here. Cooling gas can also be used to cool the hot-pressed glass wafer 404 to room temperature.

S4: Demolding, taking out each of the glass wafers 404 formed by heat pressing. It can be understood that the driving structure 200 withdraws the imprinting force on each glass wafer 404 so as to take out each of the hot pressed glass wafers 404. At this time, the micro-nano structure on the template 403 has been replicated on the glass wafer 404.

Please refer to Figures 1 and 2. The stacking hot pressing method provided in the embodiment of the present application is achieved by stacking multiple templates 403, and a glass wafer 404 is arranged between any two adjacent templates 403, so that multiple glass wafers 404 are stacked, and then the upper mold head 402 is pressed against the lower mold base 405 by the driving structure 200. The glass wafer 404 is at the glass transition temperature, so that the micro-nano structure on the template 403 can be replicated, and multiple glass wafers 404 can be formed by one hot pressing, thereby improving the hot pressing efficiency.

Optionally, the stacked hot stamping method proposed in this embodiment abandons the single device forming manufacturing mode and simultaneously forms hundreds of micro-nano structure devices on multiple glass wafers 404, thereby further significantly improving the manufacturing efficiency.

Please refer to FIG. 3 to FIG. 5 . In some embodiments, a positioning sleeve 401 having a forming cavity is prepared. The upper die head 402 is adapted to the forming cavity and is partially slidably disposed in the forming cavity. Each of the templates 403 is placed in the forming cavity.

Please refer to Figures 3 to 5. Optionally, the positioning sleeve 401 is arranged in the vertical direction, and the lower template 403 and each template 403 are all set in the forming cavity. The template 403 can be positioned through the forming cavity to avoid the movement of the template 403 during the hot pressing process. The lower end of the upper die head 402 is located in the forming cavity to press each template 403 downward.

In some embodiments, the micro-nano structure includes a micro-structure having a size on the micrometer scale and/or a nano-structure having a size on the nanometer scale.

Referring to FIG. 3 to FIG. 5 , it can be understood that the micro-nano structure is a cavity 406 opened on the template 403, and the cavity 406 is arranged in a plurality of arrays. The size of the cavity 406 includes the depth of the cavity 406 and the size of the cross-sectional area. The size can be micrometer-level and/or nanometer-level. The imprinting force presses the softened glass wafer 404 into each cavity 406, and the glass wafer 404 fills the cavity 406, so that the glass wafer 404 replicates the micro-nano structure on the template 403.

In some embodiments, the size of the micro-nano structures on each of the templates 403 decreases from bottom to top.

Please refer to Figures 3 to 5. It can be understood that the side surface of the template 403 is in contact with the inner wall of the forming cavity, so that the forming cavity can position each template 403, and friction will be generated between each template 403 and the inner wall of the forming cavity. As the height decreases, the friction increases, that is, the stamping force borne by the template 403 located at the lower end of the positioning sleeve 401 is lower than the stamping force of the template 403 located at the upper end of the positioning sleeve 401, that is, the stamping force applied to the upper die head 402 decreases from top to bottom, so that the ability of the stamping force to drive the glass wafer 404 to fill the cavity 406 is reduced, and the size of the cavity 406 is appropriately increased. As the size of the cavity 406 increases, the glass wafer 404 is easier to fill the "dead corner" in the cavity 406, so that the stamping force can drive the glass wafer 404 to fill the cavity 406, thereby ensuring the accuracy and reliability of hot pressing.

3 to 5 , in some embodiments, the micro-nano structure is located on the upwardly disposed surface of the template 403. It is understandable that the glass wafer 404 can fill the cavity 406 from top to bottom under the dual effects of gravity and the imprinting force, and in the subsequent pressure holding process, the glass wafer 404 material can continue to flow and fill the cavity 406 under the effect of gravity without shrinking.

It is understandable that the micro-nano structure may also be opened on the lower surface of the template 403 .

Please refer to FIG. 6 . In some embodiments, the driving structure 200 includes a force-applying component 201 and a lifting platform 202 located below the force-applying component 201 and connected to the heating structure 300. The force-applying component 201 includes a first-stage gravity unit 2011 slidably arranged in a vertical direction and connected to the upper die head 402 and a second-stage gravity unit 2012 slidably arranged in a vertical direction and located above the first-stage gravity unit 2011. The hot pressing step includes the following steps:

S21: the lifting platform 202 drives the lower die base 405 to move upward by a first distance, and the upper die head 402 abuts against the first-stage gravity unit 2011, so that the first-stage gravity unit 2011 is loaded on the upper die head 402;

S22: the lifting platform 202 drives the lower die base 405 to continue to move upward by a second distance, so that the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are both loaded on the upper die head 402;

S23: Preset pressure holding time, such as 0.5 minutes, 2 minutes or 5 minutes, which is not limited here and can be selected according to actual conditions.

Optionally, at the end of the hot pressing step, such as during the pressure holding process of S23, due to the contact between the upper mold head 402 and the force-applying component 201, heat is lost, and the power of the heating structure is appropriately increased to compensate for the heat loss, so that the glass wafer 404 fully fills each cavity 406.

Please refer to Figures 4 to 6. It can be understood that the first-level gravity unit 2011 and the second-level gravity unit 2012 both apply the imprinting force to the glass wafer 404 through their own gravity, without the need for an additional driver, and the force application process is stable and reliable. The first-level gravity unit 2011 and the second-level gravity unit 2012 have similar structures and both include weights. The imprinting force and the holding force can be accurately controlled by adjusting the gravity of the weights. With F1-level weights, the theoretical error can be controlled within 1mN. The movement resolution of the lifting platform 202 can reach 50nm, and the accuracy of the linear encoder can reach 5nm. The fuzzy PID control algorithm is used to achieve precise loading of vertical displacement, thereby completing actions such as hot pressing, holding pressure, and demolding.

Please refer to FIG. 4 to FIG. 6 , in some embodiments, the force-applying assembly 201 further includes a support frame, and the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are both slidably connected to the support frame.

Please refer to Figures 4 to 6. Optionally, the support frame includes a plurality of guide columns 2013 arranged in a vertical direction, the first-level gravity unit 2011 includes a first slide 211 and a first weight 210 connected to the first slide 211, the second-level gravity unit 2012 includes a second slide 221 and a second weight 220 connected to the second slide 221, the first slide 211 and the second slide 221 are both slidably connected to each guide column 2013, and the second slide 221 is located above the first slide 211.

Please refer to Figures 4 to 6. Optionally, pressure balls 2014 are provided at the lower ends of the first weight 210 and the second weight 220, so that the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are kept in point-to-face contact through the pressure ball 2014, and the first-stage gravity unit 2011 and the upper mold head 402 are kept in point-to-face contact, which is beneficial to make the imprinting force of the first-stage gravity unit 2011 and the imprinting force of the second-stage gravity unit 2012 collinear in the vertical direction, thereby improving the hot pressing accuracy of the glass wafer 404.

Please refer to Figures 4 to 6. It can be understood that the lifting platform 202 drives the heating structure 300 to move upward, and the lower mold base 405, each template 403 and the upper mold head 402 move upward together until the upper mold head 402 abuts against the pressure ball 2014 of the first-level gravity unit 2011, and the first-level gravity unit 2011 slides upward along each guide column 2013, so that the gravity of the first-level gravity unit 2011 is completely applied to each glass wafer 404, and the lifting platform 202 continues to drive the heating structure 300 to rise until the first slide plate 211 abuts against the pressure ball 2014 on the second weight 220 and lifts the second-level gravity unit 2012 upward, and the second-level gravity unit 2012 slides upward along each guide column 2013, so that the imprinting force (gravity) of the first-level gravity unit 2011 and the second-level gravity unit 2012 are completely applied to each glass wafer 404.

Please refer to FIG. 4 to FIG. 6 , in some embodiments, the demoulding step includes the following steps:

S31: The lifting platform 202 drives the lower mold base 405 to move downward by the second distance, so that the lower mold base 405 unloads the imprinting force of the second-level gravity unit 2012 while retaining the imprinting force of the first-level gravity unit 2011, so that the imprinting force of F3 is applied to the surface of the glass wafer 404 to prevent the microstructure of the glass wafer 404 from relaxing under the low viscosity state, thereby causing deformation and damage to the surface of the glass wafer 404 with the micro-nano structure replicated. It is understandable that after the upper mold head 402 and the lower mold base 405 are molded for a period of time, the heating power of the heating structure 300 and the flow rate of the cooling nitrogen gas filled into the vacuum chamber 111 are adjusted to slowly reduce its temperature, and each glass wafer 404 is cooled and annealed. And during the annealing process, the lifting platform 202 drives the heating structure to move downward to achieve the unloading of the second-level gravity unit 2012;

S32: The lifting platform 202 drives the lower mold base 405 to continue to move downward by the first distance, so that the lower mold base 405 can unload the imprint force of the first-level gravity unit 2011. When the temperature of the glass wafer 404 reaches TF, the lifting platform 202 drives the heating structure 300 to continue to move downward to achieve the unloading of the first-level gravity unit 2011, and the imprint force between the upper mold head 402 and the lower mold base 405 drops to 0N, but the upper mold head 402 with a certain gravity is located on the uppermost template 403, so that the microstructure of each glass wafer 404 maintains the same shape. At the same time, the heating power of the ceramic heating plate of the heating structure 300 is further reduced and the flow rate of the cooling nitrogen is increased to increase its cooling speed, so that the temperature of each glass wafer 404 is cooled to T4.

S33: Each glass wafer 404 is cooled to room temperature T0, and each printed glass wafer 404 is taken out and cleaned.

Referring to FIG. 4 to FIG. 6 , in some embodiments, in the step S31, the upper die head 402 and the glass wafer 404 are cooled at a first cooling rate; in the step S32, the upper die head 402 and the glass wafer 404 are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate. The first cooling rate mainly puts the glass wafer 404 in an annealing state, and the second cooling rate mainly achieves rapid cooling of the glass wafer 404.

In some embodiments, in the S1 heating step, the upper die head 402 and the lower die base 405 are kept at the predetermined temperature for a predetermined time, and the predetermined time can be 1 min, 3 min or 5 min, which is selected according to actual conditions and is not limited here.

3 to 5, after the glass wafers 404 are formed, nitrogen is introduced into the vacuum chamber 111, and the heating power of the heating structure 300 is further reduced and the flow rate of the cooling nitrogen is increased to accelerate the cooling of each glass wafer 404. When the temperature of each glass wafer 404 drops to 200°C, the vacuum chamber 111 is opened and each glass wafer 404 is taken out for quality inspection.

It can be seen that the stacked hot pressing method can shorten the molding cycle by batch hot pressing, reducing the insulation, contact and pressure holding time, accelerating the heating and cooling rates, increasing the demolding temperature and avoiding multiple taking/placing of the glass wafer 404, thereby improving manufacturing efficiency.

Please refer to FIG. 2 . During the hot pressing process of the glass wafer, at time t _B , the temperature of the upper die head 402 or the lower die holder 405 is heated to _TB , i.e., Tg temperature. The temperature is kept from t _B to t _2. At time t _D , the imprint force is gradually increased until the first-stage gravity unit 2011 and the second-stage gravity unit 2012 are fully loaded. During the time period from t _E to t ₃ , the pressure is kept. From t ₃ to t _F , annealing is performed, and at the same time, the second-stage gravity unit 2012 is unloaded. The temperature of the upper die head 402 and the lower die holder 405 is reduced to _TF . From t _F to t 4 , the first-stage gravity unit is unloaded and rapidly cooled to T ₀ .

Please refer to Figure 3. The present invention further proposes a stacking hot pressing device 100, which is used to implement the above-mentioned stacking hot pressing method. Please refer to the above-mentioned embodiment for the specific implementation steps of the method. Since the stacking hot pressing device 100 adopts all the technical solutions of all the above-mentioned embodiments, it also has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

Please refer to Figures 3 to 6. In some embodiments, the stacked hot pressing device 100 includes: a lower mold base 405, a template 403 and an upper mold head 402, a heating structure 300 and a driving structure 200. The driving structure 200 includes a lifting platform 202 with a linear encoder, a displacement platform 203 for driving the lifting platform 202 to move horizontally, and a force-applying component 201 for applying an imprinting force to the upper mold head 402. The displacement platform 203 has a displacement sensor with an accuracy of up to 0.1 μm. The lower mold base 405 is placed on the heating structure 300. The displacement platform 203 is used to drive the lifting platform 202 to be located below the force-applying component 201. The lifting platform 202 can drive the heating structure 300 to move in the vertical direction. The accuracy resolution of the linear encoder can reach 0.2 μm.

The heating structure 300 includes two silicon nitride ceramic heating plates, a copper plate, a tungsten plate and a fused quartz plate. The silicon nitride ceramic heating plate has excellent high-temperature oxidation resistance, high durability, and high heating power, but there is a problem of uneven surface temperature distribution. Since copper has high thermal conductivity, heat can be quickly transferred from the ceramic heating plate to the copper plate, and finally a uniform temperature distribution is obtained on the surface of the copper plate. Moreover, placing a fused quartz plate with extremely low thermal conductivity under the copper plate for insulation can reduce heat loss. On the other hand, a high-strength tungsten plate is used to cover the copper plate to prevent it from bending and deforming under the action of concentrated force.

The above are only optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims (10)

1. A stacking hot pressing method for hot pressing glass wafers, characterized in that the stacking hot pressing method comprises the following steps: Prepare a lower die base, an upper die head located above the lower die base, and a template having a micro-nano structure and located on the lower die base; Heating, placing the lower mold base on the heating structure, multiple templates are stacked in sequence along the vertical direction, and a glass wafer is arranged between any two adjacent templates; the heating structure heats each glass wafer to a predetermined temperature in a vacuum environment or an inert gas environment; Hot pressing, using a driving structure to make the upper die head press each of the templates toward the lower die base, so that each of the glass wafers replicates the micro-nano structure; Cooling, cooling the temperature of each of the glass wafers at a predetermined cooling rate; The mold is released to take out each of the glass wafers formed by heat pressing. 2. The stacking hot pressing method according to claim 1 is characterized in that: the micro-nano structure comprises a micro-structure with a size of micrometer level and/or a nano-structure with a size of nanometer level. 3. The stacked hot pressing method according to claim 1 is characterized in that the size of the micro-nano structure on each of the templates decreases from bottom to top. 4. The stacking hot pressing method according to claim 1, wherein the micro-nano structure is located on the surface of the template facing upward. 5. The stacked hot pressing method as described in claim 1 is characterized in that: a positioning sleeve with a forming cavity is prepared, the upper die head is adapted to the forming cavity and is partially slidably arranged in the forming cavity, and each of the templates is placed in the forming cavity. 6. The stacked hot pressing method according to any one of claims 1 to 5, characterized in that: the driving structure comprises a force-applying component and a lifting platform located below the force-applying component and connected to the heating structure, the force-applying component comprises a first-stage gravity unit slidably arranged in a vertical direction and connected to the upper die head, and a second-stage gravity unit slidably arranged in a vertical direction and located above the first-stage gravity unit; the hot pressing step comprises the following steps: S21: the lifting platform drives the lower die base to move upward by a first distance, and the upper die head abuts against the first-stage gravity unit, so that the first-stage gravity unit is loaded on the upper die head; S22: The lifting platform drives the lower die base to continue to move upward by a second distance, so that the first-stage gravity unit and the second-stage gravity unit are both loaded on the upper die head. 7. The stacked hot pressing method according to claim 6, wherein the demoulding step comprises the following steps: S31: the lifting platform drives the lower mold base to move downward by the second distance, so that the lower mold base unloads the stamping force of the second-stage gravity unit while retaining the stamping force of the first-stage gravity unit; S32: the lifting platform drives the lower mold base to continue to move downward by the first distance, so that the lower mold base unloads the stamping force of the first-stage gravity unit. 8. The stacked hot pressing method as described in claim 7 is characterized in that: in the step S31, the upper mold head and each of the glass wafers are cooled at a first cooling rate; in the step S32, the upper mold head and each of the glass wafers are cooled at a second cooling rate, and the second cooling rate is greater than the first cooling rate. 9 . The stacked hot pressing method according to claim 6 , wherein the force-applying assembly further comprises a support frame, and the first-stage gravity unit and the second-stage gravity unit are both slidably connected to the support frame. 10. A stacking hot pressing device, characterized in that it is used to implement the stacking hot pressing method according to any one of claims 1 to 9.