Optical glass wafer microwave heating device and heating method

Abstract

The present invention relates to an optical glass wafer microwave heating device and a heating method, wherein the optical glass wafer microwave heating device comprises: a microwave generator for outputting microwave energy; a diffusion cavity connected to the microwave generator; a plurality of waveguides connected to the diffusion cavity for transmitting the microwave energy of the microwave generator; a wafer carrier comprising a mold and a heating plate arranged below the mold; the mold is used to carry the optical glass wafer; wherein the waveguide is arranged on the top surface and / or side surface of the optical wafer carrier. The present invention can heat the optical glass wafer by using a plurality of waveguide output modes, disperse the energy of the microwave generator to the input ports of the plurality of waveguides through the diffusion cavity, and then transmit the energy to the outside by the waveguide, and radiate the energy uniformly above the optical glass wafer, thereby achieving uniform heating of the optical glass wafer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an optical glass wafer microwave heating device and a heating method. Background Art

[0002] Precision molding is an efficient process widely used in the manufacture of high-precision optical glass components, including the surface structure replication molding of optical glass wafers. In precision molding, the glass wafer needs to be heated to its viscoelastic temperature range (400℃-600℃) to obtain good plasticity.

[0003] At present, the commonly used heating methods in the glass precision molding industry are infrared radiation heating or resistive contact heat transfer. These heating methods are all from the outside to the inside. Affected by the thermal conductivity of the mold and the blank, the heating rate of the glass wafer is low and temperature gradients are prone to occur (i.e., the temperature at different locations on the glass wafer is inconsistent).

[0004] If a temperature gradient occurs, the glass wafer will have the following effects:

[0005] 1. Thermal stress and uneven thermal expansion: Glass wafer materials have different thermal expansion coefficients at different temperatures. The temperature gradient will cause mismatched thermal expansion in different areas of the wafer, thereby generating internal stress and causing the wafer to bend or crack.

[0006] 2. Thermal deformation: Due to inconsistent thermal expansion in different areas, uneven deformation will occur on the surface of the glass wafer, affecting the flatness of the glass wafer and the accuracy of subsequent processes.

[0007] In addition, microwave heating utilizes the dielectric loss effect of the glass material itself to achieve efficient heating of glass wafers in medium and high temperature zones. However, in traditional single-waveguide microwave heating systems, microwaves reflect and interfere with the waveguide wall to form standing waves, resulting in uneven spatial distribution of microwave field intensity. At the peak of the standing wave, the field intensity is higher, and at the valley of the standing wave, the field intensity is lower. Since the glass wafer is in the shape of a disc, affected by this non-uniform microwave field, there are differences in the heating effects of different parts of the glass wafer, resulting in insufficient temperature uniformity of the glass wafer. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention discloses an optical glass wafer microwave heating device and a heating method.

[0009] The technical solution adopted by the present invention is as follows:

[0010] In a first aspect, an optical glass wafer microwave heating device is provided, comprising:

[0011] A microwave generator, used for outputting microwave energy;

[0012] A diffusion cavity connected to the microwave generator;

[0013] A plurality of waveguides connected to the diffusion cavity for transmitting microwave energy of the microwave generator;

[0014] A wafer carrier, comprising a mold and a heating plate disposed below the mold; the mold is used to carry an optical glass wafer;

[0015] Wherein, the waveguide is arranged on the top surface and / or the side surface of the wafer carrier.

[0016] In one embodiment of the present invention, the diffusion cavity comprises an upper diffusion cavity cover and a lower diffusion cavity cover which are interlocked with each other; a cavity is formed between the upper diffusion cavity cover and the lower diffusion cavity cover; the upper diffusion cavity cover is provided with a connecting channel for connecting the microwave generator; the lower diffusion cavity cover is provided with a plurality of channels for installing a plurality of the waveguides.

[0017] In one embodiment of the present invention, the shape of the waveguide is a tapered structure with an opening at one end gradually expanding to an opening at the other end, wherein the open end of the waveguide has a rectangular cross section or a circular cross section to concentrate and directionally transmit electromagnetic waves.

[0018] In one embodiment of the present invention, the distance between the other end opening of the waveguide and the optical glass wafer is adjustable.

[0019] In one embodiment of the present invention, the plurality of waveguide tubes are arranged in an M×N matrix, where M≥1 and N≥1.

[0020] In one embodiment of the present invention, the microwave generator is a microwave magnetron or a solid-state microwave source.

[0021] In one embodiment of the present invention, the material of the mold is one of carbon-based materials, metal semiconductor oxide / carbon-based nanocomposites, ceramic / carbon-based nanocomposites, multi-walled carbon nanotube / graphene foam composites, CeO2-RGO composites and MOF-derived absorbing materials.

[0022] In one embodiment of the present invention, it also includes a closed cavity; the diffusion cavity, the plurality of waveguides and the wafer carrier are arranged in the closed cavity.

[0023] In one embodiment of the present invention, the sealed cavity is provided with an air inlet and an air outlet.

[0024] In a second aspect, a heating method is provided, using the optical glass wafer microwave heating device described in the first aspect, comprising the following steps:

[0025] When the optical glass wafer is lower than a preset temperature, the heating plate heats the optical glass wafer and the mold to raise the temperature of the optical glass wafer to the preset temperature;

[0026] When the temperature of the optical glass wafer rises to a preset temperature, the microwave generator heats the optical glass wafer and the mold; wherein the waveguide amplifies the microwave energy action area of ​​the microwave generator and completely covers the surface of the optical glass wafer, thereby achieving uniform heating of the optical glass wafer;

[0027] When the temperature of the optical glass wafer is higher than the preset temperature, the microwave generator and the heating plate heat the optical glass wafer and the mold at the same time, rapidly raising the temperature of the optical glass wafer to the molding temperature.

[0028] The above technical solution of the present invention has the following advantages compared with the prior art:

[0029] The waveguides in the optical glass wafer microwave heating device of the present invention form a matrix that can evenly cover the entire wafer surface, so that the glass wafer evenly receives microwave energy and generates heat, achieving rapid heating of the glass wafer while ensuring the uniformity of its temperature distribution.

[0030] The advantages of microwave heating in the optical glass wafer microwave heating device described in the present invention are high sensitivity, high immediacy, low inertia, and low material selectivity. Microwave mixed heating can reduce the temperature lag and preheating effect of the entire molding process, improve temperature control accuracy, and reduce heat-affected area and thermal power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0032] Figure 1 It is an exploded view of the optical glass wafer microwave heating device of the present invention.

[0033] Figure 2 It is a top view of the optical glass wafer microwave heating device of the present invention.

[0034] Figure 3 yes Figure 2 Cross-section view at AA in the middle.

[0035] Figure 4 It is a test result diagram of test example 1 in the present invention.

[0036] Figure 5 It is a test result diagram of test example 2 in the present invention.

[0037] Explanation of the reference numerals in the specification: 10, diffusion cavity upper cover; 20, diffusion cavity lower cover; 30, waveguide tube; 40, mold; 50, heating plate; 60, optical glass wafer; 70, microwave generator. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0039] The above and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the embodiments with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention. In addition, in all embodiments, the same reference numerals represent the same elements. Embodiment 1

[0040] Combination Figures 1 to 3 , an optical glass wafer microwave heating device, comprising:

[0041] A microwave generator 70, for outputting microwave energy;

[0042] A diffusion cavity connected to a microwave generator 70;

[0043] A plurality of waveguides 30 are connected to the diffusion cavity to transmit microwave energy from the microwave generator 70;

[0044] The wafer carrier includes a mold 40 and a heating plate 50 disposed below the mold 40; the mold 40 is used to carry the optical glass wafer 60;

[0045] The waveguide 30 is disposed on the top surface and / or the side surface of the wafer carrier.

[0046] This embodiment provides a microwave heating device for optical glass wafers. On the basis of a heating plate, a microwave heating device for optical glass wafers is added, which acts on the wafers at the same time to complete the heating process during the wafer molding process.

[0047] In this embodiment, the diffusion cavity includes a diffusion cavity upper cover 10 and a diffusion cavity lower cover 20 that are interlocked with each other; a cavity is formed between the diffusion cavity upper cover 10 and the diffusion cavity lower cover 20; the diffusion cavity upper cover 10 is provided with a connecting channel for connecting the microwave generator 70; the diffusion cavity lower cover 20 has multiple channels for installing multiple waveguide tubes 30.

[0048] In this embodiment, the shape of the waveguide tube 30 is a tapered structure with an opening at one end gradually expanding to an opening at the other end, wherein the open end of the waveguide tube 30 has a rectangular cross section or a circular cross section to concentrate and directionally transmit electromagnetic waves.

[0049] It is understandable that the shape of the waveguide 30 is a horn shape, which achieves effective impedance matching between the waveguide port and the free space, thereby reducing energy reflection and transmission loss. The horn-shaped waveguide helps to effectively radiate the microwave energy transmitted in the waveguide 30, and has the characteristics of high gain and high directivity. In addition, the design of the horn-shaped waveguide 30 can optimize its gain and directivity by adjusting the aperture and axial length of the horn to meet specific application requirements. For example, the wider the flare at the other end of the waveguide 30, the wider the beam width, the lower the directivity and gain, which allows the waveguide 30 to be precisely adjusted as needed.

[0050] In this embodiment, the plurality of waveguide tubes 30 are arranged in a matrix of M×N, where M≥1 and N≥1. Figure 1 As shown, there are twelve waveguides 30 arranged in a matrix of 4×3. The twelve waveguides 30 can be used to form a beam in a specific direction to improve the directional transmission effect of microwave energy of the microwave generator 70.

[0051] In this embodiment, the microwave generator 70 is a microwave magnetron or a solid-state microwave source. Among them, the magnetron is small in size and low in cost, but has simple functions and fixed power. Compared with the magnetron, the solid-state microwave source has the advantages of adjustable power, stable output, and long service life.

[0052] In this embodiment, the material of the mold 40 is one of carbon-based materials, metal semiconductor oxide / carbon-based nanocomposites, ceramic / carbon-based nanocomposites, multi-walled carbon nanotube / graphene foam composites, CeO2-RGO composites, and MOF-derived absorbing materials. Obviously, the material of the mold 40 is a microwave absorbing material with high dielectric loss, which can effectively convert incident microwave energy into heat energy, thereby reducing microwave reflection and transmission and improving the absorption efficiency of the material.

[0053] The working principle of this embodiment is as follows:

[0054] When the optical glass wafer 60 is lower than a preset temperature (the preset temperature is 300° C.), the heating plate 50 heats the optical glass wafer 60 and the mold 40 to raise the temperature of the optical glass wafer 60 to the preset temperature;

[0055] When the temperature of the optical glass wafer 60 rises to a preset temperature, the microwave generator 70 heats the optical glass wafer 60 and the mold 40; wherein the waveguide 30 amplifies the microwave energy action area of ​​the microwave generator 70 and completely covers the surface of the optical glass wafer 60, thereby achieving uniform heating of the optical glass wafer 60;

[0056] When the temperature of the optical glass wafer 60 is higher than the preset temperature, the microwave generator 70 and the heating plate 50 heat the optical glass wafer 60 and the mold 40 at the same time, and the temperature of the optical glass wafer 60 is quickly raised to the molding temperature.

[0057] As can be seen from the above, based on the evolution mechanism of microwave dielectric loss of optical glass, a new method of high-efficiency and high-uniform heating of glass wafers by resistive contact and microwave selective hybrid is proposed. Specifically: 1. In the low temperature zone, a heating plate 50 such as a resistive ceramic heater is used to realize contact heat transfer from the inside to the outside of the mold 40 and the optical glass wafer 60, so that the optical glass wafer 60 is quickly preheated and reaches a dielectric activation state (taking L-BSL7 glass as an example, the dielectric loss is significantly increased when the temperature exceeds 300°C); 2. Through the array-arranged waveguide 30, the activated optical glass wafer 60 is quickly heated by dielectric loss microwaves to achieve rapid and efficient heating of the optical glass wafer 60 in the medium and high temperature zones; 3. The unique advantages of microwave heating such as high penetration, timeliness, and material selectivity are used to reduce temperature hysteresis and residual heat effects, and together with the hybrid thermal effect of resistive contact heat transfer from the inner layer to the outer layer, the internal and external temperature gradients are reduced to achieve targeted, highly uniform and precise heating of the optical glass wafer 60. Embodiment 2

[0058] The optical glass wafer microwave heating device is basically the same as the first embodiment, but different from the first embodiment in that the optical glass wafer microwave heating device also includes a closed cavity; the diffusion cavity, multiple waveguides 30 and the wafer carrier are arranged in the closed cavity, which can effectively control the temperature of the optical glass wafer 60 during the heating process, and heat radiation heating is performed through the waveguide 30 to ensure that the optical glass wafer 60 is heated evenly to avoid local overheating or uneven temperature. Among them, the closed cavity can adopt a cylindrical structure made of transparent glass. Preferably. The inner wall of the closed cavity can be plated with a metal layer to shield microwaves.

[0059] Furthermore, the sealed cavity is provided with an air inlet and an air outlet.

[0060] It should be noted that the closed chamber can also be evacuated to a vacuum state, or nitrogen or other inert gases can be introduced to prevent the wafer from oxidizing or reacting adversely with other gases. The closed chamber can ensure that nitrogen or other inert gases remain in the closed chamber during the heating process, forming a stable processing environment.

[0061] Test Example 1

[0062] Under the conditions specified in Example 2, the transmission characteristics of microwave energy in multiple waveguides 30 were tested. Figure 4 As shown, under the conditions of a microwave frequency of 2.4 GHz and a microwave power input of 400 W, microwave energy can be transmitted to the optical glass wafer 60 and the mold 40 via a plurality of waveguides 30 to perform microwave heating on the optical glass wafer 60 and the mold 40 .

[0063] Test Example 2

[0064] Under the conditions specified in Example 2, the uniformity of the electric field intensity distribution of the optical glass wafer 60 is analyzed. Figure 5 As shown, under the conditions of a microwave frequency of 2.4 GHz and a microwave power input of 400 W, the electric field intensity distribution of the optical glass wafer 60 is uniform, and a uniform thermal effect can be generated under the action of microwaves.

[0065] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A heating method, characterized in that: An optical glass wafer microwave heating device is used for heating, wherein the optical glass wafer microwave heating device comprises: a microwave generator (70) for outputting microwave energy; a diffusion cavity connected to the microwave generator (70); a plurality of waveguides (30) connected to the diffusion cavity for transmitting the microwave energy of the microwave generator (70); a wafer carrier comprising a mold (40) and a heating plate (50) disposed below the mold (40); the mold (40) being used to carry the optical glass wafer (60); wherein the waveguide (30) is disposed on the top surface and / or the side surface of the wafer carrier, and comprises the following steps: When the temperature of the optical glass wafer (60) is lower than a preset temperature, the heating plate (50) heats the optical glass wafer (60) and the mold (40) so that the temperature of the optical glass wafer (60) is raised to the preset temperature; When the temperature of the optical glass wafer (60) rises to a preset temperature, the microwave generator (70) heats the optical glass wafer (60) and the mold (40); wherein the waveguide (30) amplifies the microwave energy action area of ​​the microwave generator (70) to completely cover the surface of the optical glass wafer (60), thereby achieving uniform heating of the optical glass wafer (60); When the temperature of the optical glass wafer (60) is higher than a preset temperature, the microwave generator (70) and the heating plate (50) heat the optical glass wafer (60) and the mold (40) simultaneously, thereby rapidly raising the temperature of the optical glass wafer (60) to a molding temperature.

2. The heating method according to claim 1, characterized in that: The diffusion cavity comprises a diffusion cavity upper cover (10) and a diffusion cavity lower cover (20) which are interlocked; a cavity is formed between the diffusion cavity upper cover (10) and the diffusion cavity lower cover (20); the diffusion cavity upper cover (10) is provided with a connection channel for connecting the microwave generator (70); and the diffusion cavity lower cover (20) is provided with a plurality of channels for installing a plurality of the waveguides (30).

3. The heating method according to claim 1, characterized in that: The shape of the waveguide tube (30) is a conical structure with an opening at one end gradually expanding to an opening at the other end, wherein the opening end of the waveguide tube (30) has a rectangular cross section or a circular cross section to concentrate and directionally transmit electromagnetic waves.

4. The heating method according to claim 3, characterized in that: The distance between the other end opening of the waveguide tube (30) and the optical glass wafer (60) is adjustable.

5. The heating method according to claim 1, characterized in that: The plurality of waveguide tubes (30) are arranged in an M×N matrix form, where M≥1 and N≥1.

6. The heating method according to claim 1, characterized in that: The microwave generator (70) is a microwave magnetron or a solid-state microwave source.

7. The heating method according to claim 1, characterized in that: The material of the mold (40) is one of a carbon-based material, a metal semiconductor oxide / carbon-based nanocomposite material, a ceramic / carbon-based nanocomposite material, a multi-walled carbon nanotube / graphene foam composite material, a CeO2-RGO composite material, and a MOF-derived absorbing material.

8. The heating method according to claim 1, characterized in that: It also comprises a sealed cavity; the diffusion cavity, the plurality of waveguide tubes (30) and the wafer carrier are arranged in the sealed cavity.

9. The heating method according to claim 8, characterized in that: The sealed cavity is provided with an air inlet and an air outlet.

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