CN1641901A - Structure and manufacturing method of miniature thermoelectric cooling device - Google Patents

Abstract

The present invention discloses a structure and manufacturing method of a micro thermoelectric cooling device, and the manufacturing steps include: providing a substrate and depositing a barrier layer on the substrate; etching and patterning the barrier layer to form a plurality of openings; using the barrier layer as a mask, etching to form a plurality of grooves; using ion plasma etching (RIE) to remove the barrier layer and rounding the corners of each groove; then depositing a metal wire layer; using surface mounting technology (SMT) to coat an adhesive layer in each groove; placing a plurality of thermoelectric materials in each groove respectively; repeating the aforementioned steps of making a substrate to complete another substrate processing; and aligning and bonding the two substrates.

Description

Structure and manufacturing method of miniature thermoelectric cooling device

technical field

The invention relates to a structure and manufacturing method of a miniature thermoelectric cooling device, in particular to an embedded thermoelectric cooling device structure, in which N-type and P-type semiconductor materials are placed in a high thermal conductivity substrate with a groove structure, which can increase The contact area of the thermoelectric cooling device increases the thermoelectric effect of the thermoelectric cooling device and reduces the contact resistance effect, so as to improve the performance of the thermoelectric cooling device.

Background technique

A thermoelectric cooling device is an active component that can provide cooling and heating effects. Its physical phenomena are summarized as follows: two wires made of different thermoelectric materials are welded together to form a continuous loop. When the temperature is different, the circuit will form a small voltage difference. This phenomenon of thermoelectricity is called the Seebeck effect. On the contrary, if the above-mentioned circuit provides power and generates electric cooling, it is called the Peliter effect, which will cause heat to be absorbed at one end and generated at the other end. This Seebeck and Peliter effect is thermoelectricity Fundamentals of cooling devices.

The thermoelectric material used in the thermoelectric cooling device has three characteristics. The first is that the electromotive force per degree of temperature difference between the component contacts is high, which is called the thermoelectric power of the material; the second is that the thermal conductivity is low. This is because if the heat transfer is too fast, the temperature difference that is too large or too small will not be easily sensed; the third characteristic is high electrical conductivity. Thermoelectric materials are divided into N-type and P-type, which are defined as follows: A thermoelectric device made according to the Seebeck effect, when the current flows from the thermoelectric material to other parts at the cold terminal point, this kind of thermoelectric material is called N-type thermoelectric material, And the current on the cold junction is flowing in, it is called a P-type material. Composed of P-type and N-type materials is called a couple.

In order to increase the thermoelectric conversion efficiency, it is very important to select and manufacture thermoelectric materials. Common thermoelectric materials such as bismuth-selenide alloy and antimony telluride have high thermoelectric conversion efficiency and have been used in large quantities. Applied to thermoelectric modules. Alloys of thermoelectric materials with higher efficiency and more complex compositions are also being developed. On the other hand, factors such as material bonding strength and stability in the manufacturing process will also affect the efficiency and reliability of the thermoelectric module, so it is necessary to choose a stable manufacturing method.

At present, thermoelectric cooling devices are mostly manufactured by hand, as disclosed in U.S. Patents US4907060, US4946511, and US5006178. First, the N-type and P-type thermoelectric material ingots are cut into cubes of about 1 mm cubic, and then the manufacturing fixtures are used to cut them into cubes. The cube is placed between two ceramic plates previously soldered, and the composition is heated to adhere the cube between the ceramic plates.

Another example is disclosed in U.S. Patent No. 4,493,939 as a method for automatically assembling thermoelectric cooling devices. It mainly uses vacuum chucks to first install N-type and P-type materials in porous containers, then place them on the substrate, and then remove them. Remove the porous container and attach it to the substrate using reflow soldering.

US Patent No. 4,902,648 discloses a method of manufacturing a thermoelectric cooling device to improve the yield rate. It mainly manufactures the electrode part first, and then puts N-type and P-type semiconductors at one time, and then connects the two parts.

US Pat. No. 6,232,542 discloses another method of manufacturing a thermoelectric cooling device, which is formed by forming grooves on two pieces of thermoelectric materials by means of exposure, etc., and then combining them.

U.S. Patent No. 5,837,929 discloses another technology for manufacturing thermoelectric cooling devices. It first places P-type thermoelectric materials on semiconductor wafers, and then implants N-type thermoelectric materials into P-type semiconductors by diffusion to form interleaved thermoelectric cooling devices. Material pairs, and then isolate the P and N-type semiconductors by etching, and finally manufacture electrodes by metal deposition.

U.S. Patent No. 5,064,476 discloses another method of manufacturing a thermoelectric cooling device. Conductive bumps are made on the substrate by means of pasting, etc., and then thermoelectric materials are installed on the two substrates with a structure such as a frame.

U.S. Patent No. 5,856,210 discloses another method of manufacturing a thermoelectric cooling device. Put N and P type thermoelectric materials into a pre-prepared spacer and make metal electrodes on both sides, and then remove the spacer. The spacer As an insulator, the purpose is to prevent short circuit and easy to install thermoelectric components.

In view of the above, the structure and manufacturing method of conventional thermoelectric cooling devices have at least the following disadvantages:

1. All thermoelectric materials have only one surface contact with the substrate, so the heat transfer effect is not good.

Second, the reverse heat transfer generated by the contact resistance between the thermoelectric material and the base material is too high, which affects the heat transfer effect.

3. No matter which manufacturing method is used, an auxiliary frame is needed to fix the thermoelectric material, which increases the difficulty of manufacturing and increases the cost of manufacturing.

4. During the manufacturing process, thermoelectric materials must go through an alignment process, and a slight discrepancy will easily affect the reliability of the module, thereby reducing the stability of the module manufacturing process.

Contents of the invention

The main purpose of the present invention is to provide a structure and manufacturing method of a miniature thermoelectric cooling device. The miniature thermoelectric cooling device adopts an embedded structure, which can increase the contact area between the thermoelectric material and the substrate, so as to increase the heat transfer effect of the miniature thermoelectric cooling device. .

The secondary purpose of the present invention is to provide a structure and manufacturing method of a micro thermoelectric cooling device, which can reduce the reverse heat transfer generated by the contact resistance between the thermoelectric material and the base material, thereby increasing the heat transfer effect of the micro thermoelectric cooling device.

Another object of the present invention is to provide a structure and manufacturing method of a miniature thermoelectric cooling device, which can use the flip-chip packaging process technology to manufacture a miniature thermoelectric cooling device to simplify the process steps, and can do automatic assembly and production to reduce the manufacturing process. time, reduce costs, and increase yield.

Another object of the present invention is to provide a structure and manufacturing method of a miniature thermoelectric cooling device, which can facilitate alignment, increase the reliability of components, and further improve the stability of the component manufacturing process.

Another object of the present invention is to provide a structure and manufacturing method of a miniature thermoelectric cooling device, to manufacture a miniature thermoelectric cooling device that can provide high heat density IC packaging and optoelectronic system packaging, such as: chip stack packaging, optical transceivers (transceiver), array planar optical waveguide (AWG), and biochips, etc.

In order to achieve the above purpose, the present invention provides a structure and manufacturing method of a micro thermoelectric cooling device, the structure comprising: a first substrate having a first surface, and the first surface is provided with several first grooves; a first A metal wire layer is arranged on the first surface; a second substrate has a second surface corresponding to the first surface, and the second surface is provided with a number corresponding to each of the first grooves. a second groove; a second metal wire layer, disposed on the second surface; a plurality of adhesive layers, disposed on the first metal wire layer and the second metal wire layer; several thermoelectric materials, each of the The thermoelectric material is respectively embedded in each of the first grooves and each of the second grooves. Wherein, the manufactured first grooves and the second grooves can be columnar, spherical or in any shape, and the thermoelectric materials respectively embedded in the grooves are shaped corresponding to the grooves.

In order to facilitate a further understanding of the features, purposes and functions of the present invention, the present invention will be described in detail below with specific examples in conjunction with the accompanying drawings.

Description of drawings

1A to 1H are schematic diagrams of implementation steps of the first preferred embodiment of the present invention;

2 is a schematic diagram of a three-dimensional structure of a substrate in a first preferred embodiment of the present invention;

Fig. 3 is a schematic diagram of the three-dimensional structure of the columnar thermoelectric material embedded in the first preferred embodiment of the present invention;

Fig. 4 is a three-dimensional structural schematic view of the first preferred embodiment of the present invention;

5A to 5H are schematic diagrams of implementation steps of the second preferred embodiment of the present invention;

6 is a schematic diagram of a three-dimensional structure of a substrate in a second preferred embodiment of the present invention;

Fig. 7 is a schematic perspective view of the embedded spherical thermoelectric material in the second preferred embodiment of the present invention.

Explanation of reference signs: 1, 7-first substrate; 10, 70-first surface; 2, 8-barrier layer; 20, 80-opening hole; 11, 71-first groove; 111, 711-corner ; 3,9-first metal wire layer; 4,15-adhesive layer; 5,16-thermoelectric material; 6,17-second substrate; 60,170-second surface; 30,90-second metal wire layer ; 61, 171 - second groove.

Detailed ways

Please refer to the schematic diagrams of the implementation steps of the first preferred embodiment of the present invention shown in Figures 1A to 1H:

(a) As shown in Figure 1A, a first substrate 1 is provided, the first substrate 1 can be made of silicon wafer, glass, plastic or other etchable materials, and then low-pressure chemical vapor deposition (LPCVD) is used to deposit Silicon nitride (Si ₃ N ₄ ) with a thickness of about 3000 Å is deposited on the first substrate 1 as a barrier layer 2 , and the barrier layer 2 is an etching barrier layer required for anisotropic etching.

(b) As shown in FIG. 1B , etching and patterning the barrier layer 2 by ion plasma etching (RIE) to form a plurality of openings 20 .

(c) As shown in FIG. 1C, using bulk-micromachine (Bulk-micromachine), using the barrier layer 2 as a mask (mask), and using potassium hydroxide (KOH) as an etchant, the anisotropy of the first substrate 1 is carried out. The atropic etching, the etched out a plurality of columnar first grooves 11 will be used to place the thermoelectric material.

(d) As shown in FIG. 1D , the barrier layer 2 is removed by ion plasma etching (RIE), and the corner 111 of the columnar first groove 11 can be rounded at the same time to avoid the tip effect.

(e) As shown in FIG. 1E, two different methods can be used to deposit a first metal wire layer 3 for turning on the power supply. Method 1: use sputtering (sputter) to deposit an aluminum metal wire, Then use electroless plating to plate a nickel layer on the aluminum metal wire, and finally plate a gold layer (an anti-oxidation layer to prevent the oxidation of the nickel layer) on the nickel layer to form the first metal wire layer 3 . Method 2: Deposit an aluminum metal wire by sputtering only to form the first metal wire layer 3 .

(f) As shown in FIG. 1F , use surface mount technology (SMT) to spin tin or silver glue in the columnar first groove 11 to form an adhesive layer 4 for fixing the bonding object during bonding.

(g) As shown in Figure 1G, put several columnar thermoelectric materials 5 into the first columnar grooves 11, wherein the arrangement of columnar thermoelectric materials 5 can be N-type and P-type staggered, N-type and N-type P-type opposite or other various arrangements.

(h) As shown in FIG. 1H, repeat the steps of FIG. 1A to FIG. 1G to complete the second substrate 6, and use flip-chip method (Flip-Chip bonder) to bond the two substrates 1 and 6 in position, and overheat the furnace ( reflow), to complete the micro thermoelectric cooling device, its structure includes: a first substrate 1 with a first surface 10, and the first surface 10 is provided with a plurality of first grooves 11; a first metal wiring layer 3 , set on the first surface 10; a second substrate 6 has a second surface 60 corresponding to the first surface 10, and the second surface 60 is provided with grooves corresponding to the first grooves 11 A plurality of second grooves 61; a second metal wire layer 30, disposed on the second surface 60; a plurality of adhesive layers 4, disposed in the first groove 11 and the first metal wire in the second groove 61 Layer 3 and the second metal wire layer 30; several thermoelectric materials 5, each thermoelectric material 5 is respectively embedded in the first groove 11 and the second groove 61, and the thermoelectric materials 5 and the first groove 11, the second The grooves 61 are all columnar.

Please refer to Fig. 2, Fig. 3 and Fig. 4, wherein the first substrate 1 has a columnar first groove 11, and the second substrate 6 has a columnar second groove 61, because the columnar first groove 11 and the columnar second groove The slots 61 have four more surfaces than the planar structure. The influence of the structure is shown by the following formula. The ratio of the contact area A _C of the pins of the columnar thermoelectric material 5 to the cross-sectional area A of the columnar thermoelectric material 5 is decisive for heat transmission. The larger the ratio, the higher the heat flux of the module. The heat transfer formula of embedded thermoelectric components is as follows:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; \&alpha;I</span>}\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; kA</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; ]</span>$

The first item is the heat transfer generated by the thermoelectric effect, which mainly occurs at the contact surface of different interfaces. The second item is Joule heat, which is the heat generated by the current flowing through the conductor. In addition to the resistance of the conductor, it also includes the contact resistance. The heat generated, the third item is conduction heat, which is mainly due to the heat transfer effect caused by temperature difference. Therefore, the structural design of the miniature thermoelectric cooling device of the present invention can increase the contact area A _C of the pins, increase the first thermoelectric heat transfer, and reduce the reverse heat transfer caused by the second contact resistance, so that the overall heat transfer Effect increases.

Please refer to the schematic diagrams of the implementation steps of the second preferred embodiment of the present invention shown in FIGS. 5A to 5H :

(a) As shown in Figure 5A, a first substrate 7 is provided, the first substrate 7 can be made of silicon wafer, glass, plastic or other etchable materials, and then low pressure chemical vapor deposition (LPCVD) is used to deposit Silicon nitride (Si ₃ N ₄ ) with a thickness of about 3000 Å is deposited on the first substrate 7 as a barrier layer 8 , and the barrier layer 8 is used as an etching barrier layer required for isotropic etching.

(b) As shown in FIG. 5B , etching and patterning the barrier layer 8 by ion plasma etching (RIE) to form a plurality of openings 80 .

(c) As shown in FIG. 5C, the bulk micromachining (Bulk-micromachine) is used, the barrier layer 8 is used as a mask (mask), and the hydrofluoric acid plus nitric acid isotropic wet etching system (HNA) is used to perform the first step. An isotropic etching of the substrate 7, a plurality of spherical first grooves 71 etched out will be used to place thermoelectric materials.

(d) As shown in FIG. 5D , the barrier layer 8 is removed by ion plasma etching (RIE), and the corner 711 of the spherical first groove 71 can be rounded at the same time to avoid the tip effect.

(e) As shown in FIG. 5E, two different methods can be used to deposit a first metal wire layer 9 for conducting power supply. Method 1: use sputtering (sputter) to deposit an aluminum metal wire, Then use electroless plating to plate a nickel layer on the aluminum metal wire, and finally plate a gold layer (an anti-oxidation layer to prevent the oxidation of the nickel layer) on the nickel layer to form the first metal wire layer 9 . Method 2: Deposit an aluminum metal wire only by sputtering to form the first metal wire layer 9 .

(f) As shown in FIG. 5F , use surface mount technology (SMT) to spread tin or silver glue in the spherical first groove 71 to form an adhesive layer 15 for fixing the bonding object during bonding.

(g) As shown in Figure 5G, put several spherical thermoelectric materials 16 into the first spherical groove 71 respectively, wherein the arrangement of the spherical thermoelectric materials 16 can be N-type and P-type staggered, N-type and P-type P-type opposite or other various arrangements.

(h) As shown in FIG. 5H, repeat the steps in FIG. 5A to FIG. 5G to complete the second substrate 17, and use flip chip method (Flip-Chip bonder) to align the two substrates 7 and 17, and overheat the furnace ( reflow) to complete the overall assembly.

6 and 7, it uses isotropic etching to form a spherical first groove 71 and a spherical first groove 171 on the first substrate 7 and the second substrate 17 respectively, so that the miniature thermoelectric device of the present invention The cooling device still forms an embedded structure, and the contact area A _C of the 16 pins of the spherical thermoelectric material will also be larger than that of the plane, so the thermoelectric effect is also greatly improved. The principle has been explained above, and it will be described here I won't go into details.

To sum up, the structure and manufacturing method of the miniature thermoelectric cooling device of the present invention can increase the contact area between the thermoelectric material and the substrate, so as to increase the heat transfer effect of the miniature thermoelectric cooling device, and can utilize the existing flip-chip packaging process Technology to produce, to simplify the process steps, to automate assembly and production, to reduce process time, reduce costs, and increase yield, thereby improving the stability of the component process. The above description is only a preferred embodiment of the present invention, when the scope of the present invention cannot be limited in this way, it is easy to associate, such as: the method of digging grooves is changed to micro-electromechanical processing, semiconductor processing, precision machining, or Other processing and manufacturing methods that can produce the desired shape; or use other methods to assemble; or use other conductive metal materials and other bonding materials, etc., those skilled in the art can think of changes after understanding the spirit of the present invention. That is, all equivalent changes and modifications made according to the claims of the present invention will still not lose the gist of the present invention, nor depart from the spirit and scope of the present invention, and all should be regarded as further implementations of the present invention.

Claims (11)

1. A structure of a miniature thermoelectric cooling device, comprising: A first substrate having a first surface, and the first surface is provided with a plurality of first grooves; a first metal wire layer, disposed on the first surface and each of the first grooves; A second substrate, having a second surface corresponding to the first surface, and the second surface is provided with a plurality of second grooves corresponding to each of the first grooves; a second metal wire layer, disposed on the second surface and each of the second grooves; Several adhesive layers are arranged in each of the first grooves and each of the second grooves; A plurality of thermoelectric materials, each of the thermoelectric materials is embedded in each of the first grooves and each of the second grooves. 2. The structure of a miniature thermoelectric cooling device according to claim 1, wherein each of the first grooves and each of the second grooves is columnar. 3. The structure of a miniature thermoelectric cooling device according to claim 1, wherein each of the first grooves and each of the second grooves is spherical. 4. A method for manufacturing a miniature thermoelectric cooling device, the steps comprising: (a) providing a substrate and depositing a barrier layer on said substrate; (b) etching and patterning the barrier layer to form a plurality of openings; (c) performing anisotropic etching using the barrier layer as a mask to form several grooves; (d) using ion plasma etching (RIE) to remove the barrier layer while rounding the corners of each of the grooves; (e) depositing a metal wire layer again; (f) coating an adhesive layer in each of the grooves using surface mount technology (SMT); (g) putting several thermoelectric materials into the grooves respectively; (h) repeating steps (a) to (f) to complete another substrate treatment; (i) The two substrates are bonded in alignment. 5. A method for manufacturing a miniature thermoelectric cooling device as claimed in claim 4, wherein the method for forming the metal wire layer in step (e) comprises: (e1) Depositing an aluminum metal wire by sputtering; (e2) plating a nickel layer on the aluminum metal wire by electroless plating; (e3) Finally, a gold layer is plated on the nickel layer to form the metal wire layer. 6. A method for manufacturing a miniature thermoelectric cooling device as claimed in claim 4, wherein in the method for forming the metal wire layer in step (e), an aluminum metal wire can be deposited by sputtering to form the metal wire layer. wire layer. 7. The manufacturing method of a miniature thermoelectric cooling device as claimed in claim 4, wherein each of the thermoelectric materials is columnar. 8. A method for manufacturing a miniature thermoelectric cooling device, the steps comprising: (a) providing a substrate and depositing a barrier layer on said substrate; (b) etching and patterning the barrier layer to form a plurality of openings; (c) performing isotropic etching using the barrier layer as a mask to form a plurality of grooves; (d) using ion plasma etching (RIE) to remove the barrier layer while rounding the corners of each of the grooves; (e) depositing a metal wire layer again; (f) coating an adhesive layer in each of the grooves using surface mount technology (SMT); (g) putting several thermoelectric materials into the grooves respectively; (h) repeating steps (a) to (f) to complete another substrate treatment; (i) The two substrates are bonded in alignment. 9. A method for manufacturing a miniature thermoelectric cooling device as claimed in claim 8, wherein the method for forming the metal wire layer in step (e) includes: (e1) Depositing an aluminum metal wire by sputtering; (e2) plating a nickel layer on the aluminum metal wire by electroless plating; (e3) Finally, a gold layer is plated on the nickel layer to form the metal wire layer. 10. A method for manufacturing a miniature thermoelectric cooling device as claimed in claim 8, wherein in the method for forming the metal wire layer in step (e), an aluminum metal wire can be deposited by sputtering to form the metal wire layer. wire layer. 11. A method of manufacturing a miniature thermoelectric cooling device as claimed in claim 8, wherein each of said thermoelectric materials is spherical.

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