TW201321663A - Even-heat distribution structure and heat-dissipation module incorporating the structure - Google Patents

Abstract

The invention proposes an even-heat distribution structure and a heat-dissipation module incorporating said structure, the even-heat distribution structure comprising a first recess groove and a first lid body, a second recess groove and a second lid body, and a supporting body interposingly disposed between the first and second recess grooves and lid bodies, wherein the bottom surfaces of the first and second recess grooves have a plurality of microstructures formed thereon and the interior of the supporting body is formed with a plurality of through holes. The first and second recess grooves of the first and second lid bodies are disposed to face the supporting body such that the supporting body can be interposingly disposed between the two lid bodies and thus a cavity chamber is constituted between the first lid body, the supporting body and the second lid body, wherein a work fluid is contained and flows within the cavity chamber by the capillary attraction of the microstructures of the first and second recess grooves and the through holes in the supporting body, thereby providing an even-heat distribution structure.

Description

Soaking structure and its preparation method and heat dissipation module having the same

The invention relates to a soaking structure and a manufacturing method thereof, and a heat dissipating module having the soaking structure, in particular to a soaking structure which can be used for improving the soaking effect, a manufacturing method thereof and a heat dissipating module having the soaking structure.

The general light-emitting diode element has the advantages of low power consumption, fast reaction speed, small volume, etc., and has gradually replaced the traditional incandescent lamp or fluorescent lamp into the mainstream of illumination in recent years. However, about half of the input power of the LED during the illuminating process is converted into thermal energy. Although it is only a few watts, the heat density is quite high because of its small size, resulting in extremely high temperature at the wafer bonding. Hot spot, which causes the performance of the LED to be reduced or the service life to be shortened.

In order to avoid overheating of the LED chip, conventional techniques are used to dispose the LED chip on a heat dissipating substrate, such as a copper foil printed circuit board, a metal based printed circuit board or a ceramic substrate. However, the copper foil printed circuit board has a heat transfer coefficient of about 0.36 W/mk, and its heat transfer performance is poor, which tends to cause the temperature of the light-emitting diode wafer to be too high. For the use of the metal-based printed circuit board, reference is made to FIG. 1. In the heat dissipation module 1, the light-emitting diode chip 11 is fixed on the substrate 13 with an adhesive 12, and the substrate 13 is provided with a dielectric layer 14 and a metal. The heat dissipation substrate and the heat dissipation structure 17 are adhered to the heat dissipation substrate of the layer 15 by a thermal interface material (TIM) 16.

In FIG. 1, the thermal energy of the LED wafer 11 (shown by the arrow) is sequentially propagated through the substrate 13, the dielectric layer 14, and the metal layer 15 to the heat dissipation structure 17, during which at least three layers of diffusion are required. Spreading resistance. Further, it is difficult for the dielectric layer 14 to uniformly distribute the point heat source generated at the bonding place of the light emitting diode wafer 11 to the horizontal plane of the metal layer 15. Moreover, the dielectric layer is usually made of an epoxy resin having poor thermal conductivity, so the dielectric layer often becomes a heat dissipation bottleneck of the heat dissipation module, so that the overall heat transfer coefficient is only about 1 to 12 W/mk. In addition, there are related technologies that use ceramic substrates as heat-dissipating substrates. Although they have better dielectric properties and a lower coefficient of thermal expansion, they also have good thermal conductivity (thermal conductivity of about 170 W/mk), but ceramic substrates are still not available. Solve the hot problems faced by high-power LEDs. Or, even if a high thermal conductive material such as a diamond like carbon is used, although the thermal conductivity in the horizontal direction can be as high as 200 to 600 W/mK, the heat transfer rate in the vertical direction is lower than that. 10 W/mK is also not enough to solve the hot spot problem faced by high-power chips.

Secondly, U.S. Patent Nos. 6,274,924, U.S. Patent No. 6,943,343, U.S. Patent No. 7,361,940 and U.S. Patent No. 7,207,772, and U.S. Patent Application Publication No. 2006/0086945 and U.S. Patent Application Publication No. 2005/0269587, the entire disclosure of which is incorporated herein by reference. The thermal conductivity of the metal material itself in the heat sink block. Further, U.S. Patent Nos. 6,671, 246, 6, 689, 810, and U.S. Patent Application Publication No. 2006/0243425, each of which uses a flat-plate heat pipe, which utilizes phase change heat transfer of a working fluid inside a heat pipe, by two-phase change and flow of a working fluid. Heat, its thermal diffusion capacity is also better than the same size of the metal plate, the temperature distribution is more uniform. However, the material used in the current flat heat pipe is usually copper, which is difficult to integrate with the wafer process.

In view of the above various prior art, the present invention provides a soaking structure, a method for manufacturing the same, and a heat dissipating module having the same, which can achieve a good soaking effect, so that the wafer disposed in the heat dissipating module can increase its Use performance.

The uniform heat structure of the present invention comprises a first cover body and a second cover body, the first cover system has a first groove and the second cover system has a second groove, and the first groove and the second cover The bottom surface of the groove is respectively formed with a plurality of microstructures; the support body has a plurality of through holes for being sandwiched by the first cover body and the second cover body, wherein the first groove and the first groove The two grooves are facing the support body to form a chamber between the first cover body, the support body and the second cover body, and a working fluid is disposed in the cavity to be A plurality of microstructures and the plurality of through holes are free to flow in the chamber.

In the above chamber, the sidewall of the first groove, the sidewall of the second groove, or the sidewall of the first groove and the second groove may also be formed with a plurality of microstructures.

In one embodiment, the material of the first cover and the second cover may be 矽. The material of the support may be glass. The working fluid can be water.

The soaking structure of the present invention can be bonded to the heat dissipating structure by a thermal interface material, and becomes a heat dissipating module for heat dissipation of the wafer. The heat dissipation module includes: a heat dissipation structure; the thermal interface material is coated on the heat dissipation structure; and the heat equalization structure of the present invention is disposed on the heat dissipation structure with the heat interface material interposed therebetween, wherein the heat absorption structure The surface of the structure away from the thermal interface material has an insulating layer; the metal layer is formed on the insulating layer of the soaking structure; and the wafer is disposed on the metal layer.

The method for manufacturing the soaking structure of the present invention comprises the following steps: (1) forming a plurality of microstructures on a bottom surface of a first recess of a first cover and a second recess of a second cover, respectively a guiding hole is formed in the first cover body or the second cover body, and a plurality of through holes are formed in the supporting body; (2) the first cover body and the second cover body are the first groove and The second groove is disposed between the first cover body and the second cover body to face the support body, so that the first cover body, the support body and the second cover body are formed. a chamber; and (3) introducing a working fluid into the chamber through the guiding hole, and then closing the guiding hole, so that the working fluid flows in the chamber by the plurality of microstructures and the plurality of through holes .

Compared with the prior art, the soaking structure and the manufacturing method thereof of the present invention pass through the capillary phenomenon generated by the working fluid in a plurality of microstructures and through holes, so that the working fluid flowing in the chamber of the soaking structure can uniformly disperse the heat energy. So solve the hot issue. In addition, the heat dissipation module with the soaking structure of the present invention can avoid multiple thermal resistances of the conventional heat dissipation module, improve the heat dissipation efficiency of the heat dissipation module, and thereby stabilize the performance of the light emitting diode chip.

The embodiments of the present invention are described in the following specific embodiments, and those skilled in the art can easily understand other advantages and functions of the present invention by the disclosure of the present disclosure, and may also use other different embodiments. State to implement or apply.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered. In the meantime, the terms "upper", "lower", "first" and "second" are used to describe the scope of the invention, and are not intended to limit the scope of the invention. Changes or adjustments in the relative relationship are considered to be within the scope of the present invention.

Hereinafter, the soaking structure and the manufacturing method thereof and the heat dissipating module having the soaking structure disclosed in the present invention will be described in detail with reference to the accompanying drawings.

Please refer to Fig. 2, which is a cross-sectional view of the soaking structure of the present invention. The heat equalizing structure 20 includes a first cover 21, a support 22, a second cover 23, and a working fluid 25.

The first cover 21 has a first recess 210, and a plurality of microstructures 211a are formed on the bottom surface 211 of the first recess 210. The second cover 23 has a second recess 230, and a plurality of microstructures 231a are formed on the bottom surface 231 of the second recess 230. The microstructures 211a and 231a may be formed on the bottom surface 211 of the first recess 210 and the bottom surface 231 of the second recess 230, respectively, using, for example, etching or other techniques. As shown in FIG. 2, the microstructures 211a and 231a may be protrusions protruding from the bottom surfaces 211 and 231. It should be noted that the first cover 21 and the second cover 23 are in principle the same member, and the extension directions of the plurality of microstructures 211a, 231a are substantially parallel to each other, but the same normal line is not limited. In addition, the material of the first cover 21 and the second cover 23 is 矽, which is made of a lithography process material.

The support 22 has a plurality of through holes 220, and the through holes 220 can be formed into the support 22 using, for example, laser or other techniques, wherein the plurality of through holes 220 extend substantially parallel to each other. The support body 22 is sandwiched between the first cover body 21 and the second cover body 23, and the first groove 210 of the first cover body 21 and the second groove 230 of the second cover body 23 are separated by the support body. 22, facing each other, wherein the first cover 21, the second cover 23 and the support 22 can be integrated into one body using a high temperature and high pressure anode process. In addition, as shown in FIG. 2 , the first cover 21 and the second cover 23 sandwich the support 22 between the first cover 21 and the second cover 23 , and are supported by the first cover 21 and the second cover 21 . A chamber 24 is formed between the body 22 and the second cover 23, and the chamber 24 is in an approximately vacuum state, about 10 ^-3 Torr. Further, the material of the support 22 is glass or glass containing 4% Na ₂ O.

The working fluid 25 is housed in a chamber 24, and the working fluid 25 can flow in the chamber 24 by a plurality of microstructures 211a and 231a and a plurality of through holes 220. Working fluid 25 can be, for example, water. In detail, an introduction hole (not shown) may be formed in the first cover body 21 or the second cover body 23 to introduce the working fluid 25 into the chamber 24 and introduce the working fluid 25 into the chamber 24. After that, the introduction hole is closed again.

It should be noted that the plurality of microstructures 211a and 231a and the through holes 220 in the chamber 24 extend substantially in parallel, and the microstructures 211a and 231a and the through holes 220 are used to cause the working fluid to generate capillary phenomenon in the chamber 24. The working fluid 25 is allowed to flow in the chamber 24 by the capillary action of the microstructures 211a and 231a and the through holes 220. It should be noted that the present invention does not limit the dimensions of the microstructures 211a and 231a, the through holes 220 or the introduction chamber 24 The amount of fluid in the working fluid 25. As shown in Fig. 2, the amount of fluid of the working fluid 25 does not completely cover the plurality of microstructures 231a. In addition, the working fluid 25 can flow in the chamber 24, so that when the soaking structure 20 is turned over, the working fluid 25 is in a state of covering a plurality of microstructures 211a due to gravity.

In a specific embodiment, if the spot heat source generated by the wafer is below the second cover 23 of FIG. 2, the heat source can be uniformly dispersed by the following process: the working fluid 25 is generated at the plurality of microstructures 231a. The puncturing action disperses the point heat source into a planar shape, and then the plurality of through holes 220 absorb the working fluid 25 to the plurality of microstructures 211a due to capillary action, and are dispersed in the first groove through the plurality of microstructures 211a. In 210, the last working fluid 25 is again lowered to the second recess 230, thus completing the cycle. During the circulation of the working fluid 25 in the chamber 24, the working fluid 25 is heated to change from a liquid phase to a gaseous state, and the flow to the unheated side is changed from a gaseous phase to a liquid state, thereby achieving a heat dissipation effect.

Secondly, a plurality of microstructures 212 may be formed on the sidewall 241 of the chamber 24 (including the sidewall of the first recess 210, the sidewall of the second recess 230, or the sidewalls of the first recess 210 and the second recess 230). , 232, thereby increasing the capillary action within the chamber 24 to enhance the flow of the working fluid 25 in the chamber 24.

It can be seen from Fig. 2 that the soaking structure of the present invention penetrates the microstructure and the through hole in the chamber, so that the working fluid in the chamber passes through the microstructures and the through holes to generate capillary phenomenon to uniformly disperse the heat energy on the soaking structure. In order to avoid the hot spots generated when the wafer is set, the wafer performance is enhanced. In addition, the soaking structure made of tantalum and glass also facilitates the placement of the wafer.

Please refer to FIG. 3, which is a flow chart of the method for manufacturing the soaking structure of the present invention. First, a support body, a first cover body, and a second cover body are provided. The material of the first cover or the second cover may be, for example, ruthenium, and the material of the support may be glass or glass containing 4% Na ₂ O.

In step S31, a first recess is formed in the first cover and a second recess is formed on the second cover to form a plurality of micro on the bottom surfaces of the first recess and the second recess, respectively. a structure, and a guiding hole is formed in the first cover or the second cover; and a plurality of through holes are formed in the support body. Then it proceeds to step S32.

In detail, the first recess and the second recess are respectively formed on the first cover and the second cover by using an etching technique, and are respectively formed on the bottom surfaces of the first recess and the second recess. A plurality of microstructures. In addition, a guiding hole may be opened at any position of the first cover body or the second cover body for introducing a working fluid. Furthermore, a plurality of through holes can be formed in the support body by laser technology. It should be noted that the steps of forming a plurality of microstructures on the bottom surface of the first groove, forming a plurality of microstructures on the bottom surface of the second groove, and forming a plurality of through holes in the support body of the present invention are not limited in sequence or in sequence.

In the step S32, the first cover body, the support body and the second cover body are placed on the support body in such a manner that the first groove and the second groove face the support body. A chamber is formed between the first cover, the support and the second cover between the cover and the second cover. Then it proceeds to step S33.

In detail, the material of the first and second covers is usually 矽, the material of the support is usually glass or glass containing 4% Na ₂ O, and the combination of glass and ruthenium can utilize high temperature (for example: about 300) ~500 ° C) high pressure (such as: about 500 ~ 1000V) combined to make the O ₂ ^- in the glass and Si ₄ ⁺ in the bismuth to form SiO ₂ covalently together, the strength of the combined bismuth and glass can be Up to 20~50Mpa. The first cover and the support and the second cover and the support can be combined according to this method. In addition, the first cover and the second cover with 矽 as the main material can be easily combined with the process of the wafer. In addition, in the chamber formed by the combination of the first cover body, the support body and the second cover body, a plurality of microstructures of the bottom surface of the first groove and a plurality of microstructures of the bottom surface of the second groove And extending directions of the plurality of through holes of the support are substantially parallel.

In step S33, a fluid (for example, water) is introduced into the chamber through the guiding hole, and the guiding hole is closed. The fluid can thus flow through the chamber through the plurality of microstructures and through holes. The chamber is brought to a vacuum state, about 10 ^-3 Torr, before closing the guide hole.

As can be seen from FIG. 3, through the method of the soaking structure of the present invention, a closed chamber can be formed in the soaking structure, and the bottom surface of the first groove and the second groove constituting the chamber has a plurality of microstructures. The support body between the first groove and the second groove has a plurality of through holes in the chamber, so that the working fluid in the chamber can be in the first groove, the second groove and the through hole Flow to achieve soaking effect.

Please refer to FIG. 4, which is a cross-sectional view of a heat dissipation module to which the soaking structure of the present invention is applied. Fig. 4 is a view showing the heat equalizing structure 20 shown in Fig. 2 or the heat equalizing structure produced in accordance with the steps shown in Fig. 3 applied to the heat dissipating module 3 carrying the wafer.

The heat dissipation module 3 includes a wafer 31, a metal layer 32, an insulating layer 33, a heat equalizing structure 30, a thermal interface material 34, and a heat dissipation structure 35.

The heat dissipation structure 35 can be a heat sink, a thermal interface material (TIM) 34 is applied to the heat dissipation structure 35, and the heat dissipation structure 30 is disposed on the heat dissipation structure 35 with the thermal interface material 34 interposed therebetween. . The thermal interface material 34 fills the joint gap between the soaking structure 30 and the heat dissipating structure 35 to expand the heat dissipating area between the soaking structure 30 and the heat dissipating structure 35.

The soaking structure 30 has all of the features of the soaking structure 20 shown in Fig. 2, and the side walls 301 of the chamber 300 of the soaking structure 30 also have a plurality of microstructures 301a. In addition, the surface 302 of the soaking structure 30 remote from the thermal interface material 34 may have an insulating layer 33 as a layer of ruthenium dioxide.

The metal layer 32 is formed on the insulating layer 33 of the heat equalizing structure 30, and a metal (e.g., copper) may be formed on the insulating layer 33 of the heat equalizing structure 30 by a technique such as sputtering or plating to serve as a wiring layer. The wafer 31 is disposed on the metal layer 32, and is exemplified by a light-emitting diode wafer, and is adhered to the metal layer 32 through eutectic alloys.

Therefore, in FIG. 4, the soaking structure 30 can evenly disperse the point heat source generated by the wafer 31 into a planar heat source, and then combine the heat interface material 34 with the heat dissipation structure 35, so that contact with a large area can assist the heat. The conduction, and finally the thermal energy is dissipated by the heat dissipation structure 35.

Next, as shown in FIGS. 5A and 5B, the temperature test results of the conventional heat dissipation module and the heat dissipation module of the present invention are respectively shown. The heat-dissipating module carrying the light-emitting diode chip is mainly compared with the conventional heat-dissipating module carrying the light-emitting diode chip shown in FIG. 1 of the prior art.

Please refer to FIGS. 5A and 5B . The conventional technology requires at least three diffusion heat resistances from the substrate, the dielectric layer and the metal layer from the wafer to the heat dissipation structure. In contrast, the heat dissipation module of the present invention only needs to pass through the insulation layer and the heat dissipation structure. Reducing the thermal resistance of diffusion increases the heat transfer efficiency. Secondly, the conventional technology generally uses an epoxy resin as a dielectric layer, and the heat transfer performance is not good enough to uniformize the hot spot heat energy generated by the wafer, resulting in the heat dissipation structure of the heat dissipation structure of FIG. 5A to the wafer is lower than that of the 5B diagram. The temperature difference from structure to wafer is quite large, indicating that the thermal energy of the prior art is still concentrated on the wafer itself and the die bond, which will generate hot spots, resulting in a reduction in the lifetime of the light-emitting diode and a decrease in efficiency. In addition, the conventional technology relies on the heat transfer property of the metal itself to conduct heat. As shown in FIG. 5A, the temperature difference between the metal layer and the heat dissipation structure is also large, that is, the heat energy cannot be transmitted to the heat dissipation structure; The structure, because of the phase change and convection of the working fluid in the soaking structure, can uniformly disperse the point-like heat source generated by the wafer, thereby allowing the heat to be well conducted to the heat dissipation structure.

In summary, the soaking structure of the present invention or the soaking structure produced by the soaking structure method of the present invention has a good soaking effect. The heat dissipation module adopting the soaking structure of the invention can reduce the thermal resistance, avoid the hot spot problem and is convenient to be combined with the wafer, and can be applied to the LED chip to improve the performance thereof, and can be applied to other point heat sources. To provide better heat transfer performance.

The above-described embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Modifications and variations of the above-described embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

1, 3. . . Thermal module

11. . . Light-emitting diode chip

12. . . Adhesive

13. . . Substrate

14. . . Dielectric layer

15. . . Metal layer

16. . . Thermal interface material

17. . . Heat dissipation structure

20. . . Soaking structure

twenty one. . . First cover

210. . . First groove

211, 231. . . Bottom

211a, 212, 231a, 232. . . microstructure

twenty two. . . Support

220. . . Through hole

twenty three. . . Second cover

230. . . Second groove

twenty four. . . Chamber

241. . . Side wall

25. . . Working fluid

30. . . Soaking structure

300. . . Chamber

301. . . Side wall

301a. . . microstructure

302. . . one side

31. . . Wafer

32. . . Metal layer

33. . . Insulation

34. . . Thermal interface material

35. . . Heat dissipation structure

S31~S33. . . step

Figure 1 is a schematic view of a conventional heat dissipation module;

Figure 2 is a schematic view of the soaking structure of the present invention;

Figure 3 is a flow chart of the method for manufacturing the soaking structure of the present invention;

4 is a schematic view of a heat dissipation module using a soaking structure of the present invention;

Figures 5A and 5B show the temperature test results of the conventional heat dissipation module and the heat dissipation module of the present invention, respectively.

20. . . Soaking structure

twenty one. . . First cover

210. . . First groove

211, 231. . . Bottom

211a, 212, 231a, 232. . . microstructure

twenty two. . . Support

220. . . Through hole

twenty three. . . Second cover

230. . . Second groove

twenty four. . . Chamber

241. . . Side wall

25. . . Working fluid

Claims (18)

A soaking structure includes: a first cover body having a first recess and a second cover body having a second recess; and the bottom surfaces of the first recess and the second recess are respectively formed with a plurality of a micro-structure; the support body has a plurality of through holes for being sandwiched by the first cover body and the second cover body, wherein the first groove and the second groove body face the support body, Forming a chamber between the first cover body, the support body and the second cover body; and a working fluid is disposed in the chamber to cover the plurality of microstructures and the plurality of through holes Free flowing in the chamber. The heat equalizing structure according to claim 1, wherein the sidewall of the first groove, the sidewall of the second groove, or the sidewall of the first groove and the second groove are formed with a plurality of Microstructure. The soaking structure according to claim 1, wherein the chamber is in a vacuum state. The soaking structure according to claim 1, wherein the material forming the first cover and the second cover is 矽. The soaking structure according to claim 1, wherein the material forming the support is glass. The soaking structure of claim 1, wherein the working fluid is water. The soaking structure according to claim 1, wherein the plurality of microstructures of the first groove and the second groove are convex portions. The soaking structure according to claim 1, wherein the first cover body, the second cover body and the support system are integrated into one body using a high temperature and high pressure anode process. The method for manufacturing a soaking structure comprises the following steps: (1) forming a plurality of microstructures on a bottom surface of a first recess of a first cover and a second recess of a second cover, respectively, and at the first a guiding hole is formed in the cover body or the second cover body, and a plurality of through holes are formed in a support body; (2) the first cover body and the second cover body are the first groove and the first cover The support body is sandwiched between the first cover body and the second cover body to form a chamber between the first cover body, the support body and the second cover body. And (3) introducing a working fluid into the chamber through the guiding hole, and then closing the guiding hole, so that the working fluid flows in the chamber by the plurality of microstructures and the plurality of through holes. The method for manufacturing a soaking structure according to claim 9, wherein the step (1) is further included in a sidewall of the first groove, a sidewall of the second groove, or the first groove and the first The sidewalls of the two grooves form a plurality of microstructures. The method for manufacturing a soaking structure according to claim 9, wherein the plurality of microstructures are formed on the bottom surfaces of the first groove and the second groove by an etching technique. The method for producing a soaking structure according to claim 9, wherein the plurality of through holes are formed in the support by laser technology. The method for manufacturing a soaking structure according to claim 9, wherein the step (2) comprises: sandwiching the first cover and the second cover with high temperature and high pressure and bonding the support. The method for manufacturing a soaking structure according to claim 9, wherein the step of vacuuming the chamber is performed before the step (3) is closed to close the guiding hole. The method of manufacturing a soaking structure according to claim 9, wherein the first cover and the second cover system are made of a lithographic process material. A heat dissipation module is applied to heat dissipation of a chip, the heat dissipation module includes: a heat dissipation structure; a thermal interface material is coated on the heat dissipation structure; and a heat dissipation structure is disposed on the heat dissipation structure with the heat interface material interposed therebetween And the surface of the heat-repellent structure having an insulating layer away from the surface of the thermal interface material, wherein the heat-receiving structure comprises: a first cover body having a first groove and a second cover body having a second groove, and the The bottom surface of the first groove and the second groove are respectively formed with a plurality of microstructures; the support body has a plurality of through holes for being sandwiched by the first cover body and the second cover body, wherein The first groove and the second groove face the support body, and a cavity is formed between the first cover body, the support body and the second cover body; and a working fluid is disposed in the cavity And flowing through the chamber by the plurality of microstructures and the plurality of through holes; a metal layer is formed on the insulating layer of the soaking structure; and a wafer is disposed on the metal layer. The heat dissipation module of claim 16, wherein the wafer is a light emitting diode chip. The heat dissipation module of claim 16, wherein the insulating layer is a ceria layer.