An infrared sensor and a manufacturing method thereof

Abstract

The present invention discloses an infrared sensor and a manufacturing method thereof. The manufacturing method of the infrared sensor includes: providing a temporary substrate; forming a thermoelectric structure on the temporary substrate, the thermoelectric structure including at least one set of thermocouple pairs; providing a first substrate having a circuit therein; forming a bonding layer on the first substrate or on the thermoelectric structure; forming a cavity and a first through hole in the bonding layer, the cavity and the first through hole penetrating through the bonding layer; bonding the first substrate and the thermoelectric structure through the bonding layer, the first through hole exposing a part of the surface of the thermocouple pairs; removing the temporary substrate; forming a second through hole in the first substrate, the second through hole penetrating through the first substrate and communicating with the first through hole; and forming an electrical connection structure in the first through hole and the second through hole, the electrical connection structure connecting the thermocouple pairs and an external circuit.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and particularly to an infrared sensor and a manufacturing method thereof. Background Art

[0002] With the continuous development of MEMS sensing technology, infrared sensors with thermopiles as the core components have been widely used in fields such as infrared temperature measurement, infrared detection, infrared alarm, infrared imaging, and infrared guidance. The basic principle of an infrared sensor is based on the Seebeck effect of thermoelectric materials. Generally, multiple pairs of thermocouples are connected into a "pile" to convert the externally absorbed infrared radiation signal into an electrical signal to achieve temperature measurement. Among the two ends, the end that absorbs infrared is called the hot zone, and the substrate end is called the cold zone. The main thermopile products on the market are closed thin-film structures, mainly including a support layer, a thermocouple layer, and an absorption layer. The general process flow is as follows: grow SiO2 and SiN with thicknesses of 400 nm and 800 nm on a silicon wafer as the support layer, then grow thermoelectric strips, mostly choosing P-polysilicon material, and then grow a barrier layer TEOS SiO2, continue to grow another thermoelectric strip, mostly choosing thin-film Al or N-polysilicon, and finally use deep silicon etching to etch out a cavity on the back for heat insulation to prevent the heat absorbed by the hot zone from dissipating from the silicon substrate.

[0003] However, according to the existing technology, in the process of manufacturing and packaging an infrared sensor, the front-end process of the thermopile and the cavity process are carried out successively, and several cavity etching processes need to be completed. The etching process is likely to have an adverse effect on the chip, resulting in problems such as low packaging efficiency, low reliability, and low yield.

[0004] Therefore, how to improve the manufacturing method of an infrared sensor and improve the quality, reliability, yield, and packaging efficiency of the sensor is the problem faced currently. Summary of the Invention

[0005] The purpose of the present invention is to provide an infrared sensor and a manufacturing method thereof, which can solve the problems of low quality, reliability, yield, and packaging efficiency of the sensor.

[0006] To achieve the above purpose, the present invention provides a manufacturing method of an infrared sensor, including:

[0007] Providing a temporary substrate;

[0008] Forming a thermoelectric structure on the temporary substrate, the thermoelectric structure including at least one group of thermocouple pairs;

[0009] Providing a first substrate, the first substrate having a circuit therein;

[0010] Forming a bonding layer on the first substrate or on the thermoelectric structure;

[0011] A cavity and a first through-hole are formed within the bonding layer, and the cavity and the first through-hole penetrate through the bonding layer;

[0012] The first substrate and the thermoelectric structure are bonded through the bonding layer, and part of the surface of the thermocouple pair is exposed by the first through-hole;

[0013] The temporary substrate is removed;

[0014] A second through-hole is formed on the first substrate, and the second through-hole penetrates through the first substrate and communicates with the first through-hole;

[0015] An electrical connection structure is formed within the first through-hole and the second through-hole, and the electrical connection structure connects the thermocouple pair and an external circuit.

[0016] The present invention further provides an infrared sensor, comprising:

[0017] A first substrate having a circuit therein;

[0018] A bonding layer disposed on the first substrate, the bonding layer enclosing a cavity that penetrates through the bonding layer;

[0019] A thermoelectric structure located above the bonding layer and covering the cavity, the thermoelectric structure including at least one group of thermocouple pairs;

[0020] An electrical connection structure disposed outside the cavity, the electrical connection structure penetrating through the bonding layer and the first substrate, and the electrical connection structure connecting the thermocouple pair and an external circuit.

[0021] The beneficial effects of the present invention are as follows:

[0022] By providing a bonding layer and using a bonding process to bond the first substrate and the thermoelectric structure, the process of forming the thermoelectric structure can be separated from the process of forming the first substrate and the process of forming the cavity and through-holes on the bonding layer, thereby improving the packaging efficiency.

[0023] Furthermore, forming the cavity and through-holes on the bonding layer can be completed in the same process step, further improving the packaging efficiency.

[0024] Furthermore, since the through-holes in the support layer and the cavity and through-holes in the bonding layer are formed independently, the process difficulty is reduced, the risk of chip breakage caused by forming the cavity and through-holes is avoided, and the quality, reliability and yield of the sensor are improved.

[0025] Furthermore, the material of the bonding layer can be selected as a photolithographic material. By means of a photolithography process, a cavity and a first through-hole are formed, thereby avoiding the damage to the bonding layer, the first substrate or the support layer caused by the process of forming the bonding layer and the etching process, reducing the influence on the bonding strength of the bonding layer, being beneficial to improving the quality, reliability and yield of the infrared sensor. At the same time, due to the saving of the etching process steps, the manufacturing cycle is shortened and the packaging efficiency is improved. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0027] Figures 1 to 14 The structural schematic diagrams corresponding to different steps in the manufacturing method of the infrared sensor according to Embodiment 1 of the present invention are shown.

[0028] Description of the Reference Numerals:

[0029] 10 - Temporary substrate; 11 - Absorbing layer; 21 - First thermoelectric strip; 211 - First groove; 212 - First electrical connection structure; 22 - Barrier layer; 221 - Second groove; 23 - Second thermoelectric strip; 231 - Third groove; 232 - Second electrical connection structure; 24 - Electrical connection structure; 25 - Support layer; 26 - Bonding layer; 27 - Cavity; 28 - First through-hole; 281 - First sub-through-hole; 282 - Second sub-through-hole; 29 - Third through-hole; 30 - First substrate; 31 - Second through-hole; 311 - Third sub-through-hole; 312 - Fourth sub-through-hole. Detailed Embodiments

[0030] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in various different forms and is not limited to the specific embodiments described herein. The drawings are all in very simplified forms and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0031] In the specification and claims, the terms "first", "second", etc. are used to distinguish between similar elements and are not necessarily used to describe a specific order or chronological sequence. It is to be understood that, where appropriate, these terms so used may be interchanged, for example, such that the embodiments of the present invention described herein can be operated in an order different from that described or shown herein. Similarly, if the method described herein includes a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps can be omitted and / or some other steps not described herein can be added to the method. If the components in a certain drawing are the same as those in other drawings, although these components can be easily recognized in all the drawings, for the sake of clearer illustration of the drawings, the present specification will not label the reference numerals of all the same components in each drawing.

[0032] Example 1

[0033] Embodiment 1 of the present invention provides a method for manufacturing an infrared sensor. The method for manufacturing the infrared sensor includes:

[0034] S01: Provide a temporary substrate, and form a thermoelectric structure on the temporary substrate. The thermoelectric structure includes at least one set of thermocouple pairs;

[0035] S02: Provide a first substrate having a circuit therein, and form a bonding layer on the first substrate or on the thermoelectric structure;

[0036] S03: Form a cavity and a first through hole in the bonding layer, and the cavity and the first through hole penetrate the bonding layer;

[0037] S04: Bond the first substrate and the thermoelectric structure through the bonding layer, and the first through hole exposes a part of the surface of the thermocouple pair;

[0038] S05: Remove the temporary substrate;

[0039] S06: Form a second through hole in the first substrate, and the second through hole penetrates the first substrate and communicates with the first through hole;

[0040] S07: Form an electrical connection structure in the first through hole and the second through hole, and the electrical connection structure connects the thermocouple pair and the external circuit.

[0041] It should be noted that the above steps S0N do not represent a sequential order.

[0042] Next, please refer to Figures 1 to 14 to elaborate on the method for manufacturing the infrared sensor. Figures 1 to 14 It is a schematic structural diagram corresponding to different steps in an embodiment of the method for manufacturing the infrared sensor of the present invention.

[0043] Refer to Figures 1 to 4, perform step S01: Provide a temporary substrate 10, and form a thermoelectric structure on the temporary substrate 10. The thermoelectric structure includes at least one set of thermocouple pairs.

[0044] Reference Figure 1 , provide a temporary substrate 10. The material of the temporary substrate 10 includes semiconductor materials such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors. It can also be a double-sided polished wafer (DSP), or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0045] In this embodiment, after forming the temporary substrate 10 and before forming the thermoelectric structure, it further includes forming an absorption layer 11 to cover the temporary substrate 10. The material of the absorption layer 11 includes single-layer or laminated insulating films such as silicon nitride, silicon dioxide, phosphosilicate glass, borophosphosilicate glass, or polyimide film. The function of forming the absorption layer 11 is to absorb infrared rays and effectively transfer the heat generated by absorbing infrared rays to the thermoelectric structure, thereby improving the device performance. The absorption layer 11 can be formed by methods such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, laser ablation deposition, or molecular beam deposition.

[0046] In this embodiment, the thermocouple pair includes a first thermoelectric strip 21 and a second thermoelectric strip 23 that are in contact with each other. The thermocouple pair utilizes the principle of the "Seebeck effect" to manufacture a circuit with the first thermoelectric strip 21 and the second thermoelectric strip 23, and generate a thermoelectromotive force by generating a temperature difference, thereby measuring the amount of infrared rays incident on the infrared sensor. And in this embodiment, by setting a plurality of thermocouple pairs in series, the high sensitivity of the infrared sensor is achieved, and the quality and reliability of the sensor are improved. Among them, the first thermoelectric strip 21 and the second thermoelectric strip 23 can be arranged side by side on the same horizontal plane, or stacked in a direction perpendicular to the temporary substrate 10. In this embodiment, the first thermoelectric strip 21 and the second thermoelectric strip 23 are stacked.

[0047] In this embodiment, the method for forming a thermoelectric structure includes: forming a first thermoelectric strip material layer on a temporary substrate 10; patterning the first thermoelectric strip material layer to form a plurality of discrete first thermoelectric strips 21, with a first trench 211 between adjacent first thermoelectric strips 21; forming a barrier layer 22 on the temporary substrate 10 and the first thermoelectric strips 21, the barrier layer 22 covering the first thermoelectric strips 21 and filling the first trench 211; patterning the barrier layer 22 to form a second trench 221, the second trench 221 exposing a part of the surface of the first thermoelectric strips 21; forming a second thermoelectric strip material layer in the second trench 221 and on the barrier layer 22; patterning the second thermoelectric strip material layer to form a plurality of discrete second thermoelectric strips 23, with a third trench 231 between adjacent second thermoelectric strips 23, the second thermoelectric strips 23 filling the second trench 221; electrically connecting the first thermoelectric strips 21 and the second thermoelectric strips 23 of adjacent thermocouple pairs to form multiple groups of thermocouple pairs, and the electrical connection mode between the thermocouple pairs is in series.

[0048] Specifically, referring to Figure 2 , deposit a first thermoelectric strip material layer on the absorption layer 11. The first thermoelectric strip material layer can be polysilicon with n-type impurities or a metal, or polysilicon with p-type impurities. The metal includes aluminum, titanium, nickel, gold, etc. The first thermoelectric strip material layer can be formed by physical vapor deposition such as magnetron sputtering and evaporation, or chemical vapor deposition. After forming the first thermoelectric strip material layer, pattern the first thermoelectric strip material layer. In this embodiment, a dry etching process is used to pattern the first thermoelectric strip material layer. The dry etching process includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. Through the etching process, a first trench 211 is formed in the first thermoelectric strip material layer, and the first trench 211 penetrates the first thermoelectric strip material layer. After patterning, a plurality of discrete first thermoelectric strips 21 are formed, with a first trench 211 between adjacent first thermoelectric strips 21.

[0049] Referring to Figure 3, a barrier material layer is formed on the first thermoelectric strip 21, covering the first thermoelectric strip 21 and filling the first trench 211. The material of the barrier material layer includes dielectric materials such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). When the barrier material layer is silicon dioxide (SiO2), silicon nitride (Si3N4), or aluminum oxide (Al2O3), it can be formed by a deposition process. After the barrier material layer is formed, the barrier material layer is patterned to form a barrier layer 22, and the barrier layer 22 is provided with a second trench 221. The formation method of the second trench 221 refers to the formation method of the first trench 211. The second trench 221 penetrates the barrier layer 22 and is arranged staggered with the first trench 211, so that a part of the surface of the first thermoelectric strip 21 can be exposed. In this embodiment, the number of the second trenches 221 is equal to the number of the first thermoelectric strips 21, that is, each first thermoelectric strip 21 has a corresponding second trench 221 exposing its surface.

[0050] Reference Figure 4 , a second thermoelectric strip material layer is deposited on the barrier layer 22, covering the barrier layer and filling the second trench 221 completely. The second thermoelectric strip material layer can be polysilicon with n-type impurities or metal, or polysilicon with p-type impurities. The metal includes aluminum, titanium, nickel, gold, etc. When the first thermoelectric strip material layer is polysilicon with n-type impurities or metal, the second thermoelectric strip material layer is polysilicon with p-type impurities, and vice versa. The deposition method refers to the deposition method of the first thermoelectric strip material layer. Through an etching process, a third trench 231 is formed in the second thermoelectric strip material layer, and the third trench 231 penetrates the second thermoelectric strip material layer. After patterning, a plurality of discrete second thermoelectric strips 23 are formed, and there is a third trench 231 between adjacent second thermoelectric strips 23. In this embodiment, the number of the third trenches 231 is equal to the number of the first trenches 211, that is, the number of the first thermoelectric strips 21 is equal to the number of the second thermoelectric strips 23. The positions of the third trench 231 and the first trench 211 are relatively arranged, and the second thermoelectric strip 23 is electrically connected to the first thermoelectric strip 21 through the second trench 221 to form a thermocouple pair. The electrical connection mode between the thermocouple pairs is in series.

[0051] Reference Figures 6 to 7 , perform step S02: Provide a first substrate 30, the first substrate 30 has a circuit therein, and a bonding layer 26 is formed on the first substrate 30 or on the thermoelectric structure.

[0052] The material of the first substrate 30 includes semiconductor materials such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, and can also be double-side polished wafers (DSP), etc. A signal processing circuit is formed in the first substrate 30, which is used to drive the thermoelectric structure and process the detection signal generated by the thermoelectric structure during the use of the infrared sensor.

[0053] The material of the bonding layer 26 includes dry film, silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. In this embodiment, the bonding layer 26 is a photolithographic material, such as dry film. By bonding the first substrate 30 and the thermoelectric structure through a bonding process, the process of forming the thermoelectric structure can be separated from the subsequent process of forming the cavity 27, thereby improving the packaging efficiency.

[0054] In this embodiment, the bonding layer 26 is a film-shaped dry film, which makes the process of forming the bonding layer 26 simpler. The film-shaped dry film is a sticky photoresist film used in semiconductor chip packaging or printed circuit board manufacturing. The film-shaped dry film is manufactured by coating a solvent-free photoresist on a polyester film substrate and then covering it with a polyethylene film; during use, the polyethylene film is peeled off, and the solvent-free photoresist is pressed onto the substrate, and after exposure and development, a pattern can be formed in the dry film.

[0055] In this embodiment, the bonding layer 26 is formed by a lamination process. The lamination process is carried out in a vacuum environment. By selecting the lamination process, the adhesion and bonding strength between the bonding layer 26 and the first substrate 30 and the thermoelectric structure are significantly improved.

[0056] Reference Figure 5 , in this embodiment, it further includes that after forming the thermoelectric structure and before forming the bonding layer 26 on the thermoelectric structure, a support layer 25 is formed on the surface of the thermoelectric structure. The material of the support layer 25 includes silicon oxynitride or silicon carbonitride. The support layer 25 has a heat insulation effect, preventing the thermoelectric structure from exchanging heat with the outside in the direction close to the support layer 25, improving the sensitivity and accuracy of the sensor, and ensuring the quality and reliability of the sensor. After forming the support layer 25, a third through hole 29 penetrating the support layer 25 is formed in the support layer 25. The method of forming the third through hole 29 can be through a dry etching process, and the dry etching process includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting.

[0057] Reference Figure 6, the bonding layer 26 can be formed on the first substrate 30, or refer to Figure 7 , the bonding layer 26 is formed on the support layer 25. Since a lithography - applicable material is selected to form the bonding layer 26, the process of forming the bonding layer 26 is prevented from having an adverse effect on the first substrate 30 or the support layer 25, which is beneficial to improving the quality, reliability, and yield of the infrared sensor. In this embodiment, the bonding layer 26 is formed on the first substrate 30. Subsequently, the processes of forming the cavity 27 and the first through - hole 28 on the bonding layer 26 and the process of forming the third through - hole 29 on the support layer 25 are completed independently, avoiding the risk of chip breakage during the formation of the cavity and the through - hole, and improving the quality, reliability, and yield of the sensor.

[0058] In other embodiments, the material selected for the bonding layer 26 can also be a liquid dry film. Here, the liquid dry film means that the components in the film - like dry film exist in a liquid form. Correspondingly, the bonding layer 26 can be formed by a spin - coating process; after forming the bonding layer 26, a drying step is also included to cure it. And the cured liquid dry film is also a photosensitive material and can be patterned by a lithography process.

[0059] Refer to Figure 8 and Figure 9 , perform step S03: form a cavity 27 and a first through - hole 28 in the bonding layer 26, and the cavity 27 and the first through - hole 28 penetrate the bonding layer 26. In this embodiment, the formation of the cavity 27 and the first through - hole 28 is completed in the same process step, thus improving the packaging efficiency of the sensor. When the material of the bonding layer 26 is a non - lithography material, the cavity 27 can be formed by an etching process (the etching process includes two processes: lithography and etching). In this embodiment, the material of the bonding layer 26 is a lithography - applicable material, and the cavity 27 and the first through - hole 28 can be formed by a lithography process, eliminating the etching process after the lithography process. Thus, the process of forming the bonding layer 26 and the etching process are prevented from damaging the first substrate 30 or the support layer 25, reducing the impact on the bonding strength of the bonding layer 26, which is beneficial to improving the quality, reliability, and yield of the infrared sensor. At the same time, the etching process steps are saved, the manufacturing cycle is shortened, and the packaging efficiency is improved. The method of forming the cavity 27 by a lithography process is: provide a mask plate, and expose and develop the bonding layer 26 through the mask plate to form the cavity 27 in the bonding layer 26. Further, since the third through - hole 29 of the support layer 25 and the cavity 27 and the first through - hole 28 of the bonding layer 26 are formed independently, the process difficulty is reduced, the risk of chip breakage during the formation of the cavity and the through - hole is avoided, and the quality, reliability, and yield of the sensor are improved.

[0060] Specifically, refer to Figure 8, when forming the bonding layer 26 on the first substrate 30, the bonding layer 26 is patterned by a photolithography process, and the cavity 27 and the first through hole 28 are formed in the same process step. The cavity 27 and the first through hole 28 penetrate through the bonding layer 26, and the first through hole 28 is located outside the cavity 27. The function of the cavity 27 is heat insulation, which cooperates with the support layer 25 to prevent the thermoelectric structure from exchanging temperature with the outside in the direction close to the support layer 25, ensuring the quality and reliability of the sensor. In this embodiment, by photolithographing the bonding layer 26, the damage that may be caused to the circuit in the first substrate 30 during the process of etching the bonding layer 26 by an etching process is avoided, the influence on the bonding strength of the bonding layer 26 is reduced, which is beneficial to improving the quality, reliability and yield of the sensor. At the same time, since the process of photolithographing the bonding layer 26 and the process of etching the support layer 25 are completed independently, the process difficulty is reduced, the risk of fragmentation caused when forming the cavity and the through hole is avoided, and the quality, reliability and yield of the sensor are improved.

[0061] In other embodiments, refer to Figure 9 , the bonding layer 26 is formed on the support layer 25. Referring to the foregoing embodiment, the bonding layer 26 is patterned by a photolithography process to form the cavity 27 and the first through hole 28. Since there is a third through hole 29 on the support layer 25, during the process of forming the bonding layer 26, it is necessary to prevent the bonding layer 26 material from entering the third through hole 29. Therefore, when using a liquid dry film, attention should be paid to the matching between the viscosity of the dry film and the size of the third through hole 29 to avoid contaminating the cavity with the liquid dry film material. It is recommended to use a film laminating process.

[0062] Refer to Figure 10 , perform step S04: Bond the first substrate 30 and the thermoelectric structure through the bonding layer 26, and the first through hole 28 exposes part of the surface of the thermocouple pair. By providing the bonding layer 26 and using a bonding process to bond the first substrate 30 and the thermoelectric structure, the process of forming the thermoelectric structure can be separated from the process of forming the first substrate 30 and the process of forming the cavity 27 and the first through hole 28 on the bonding layer 26, thereby improving the packaging efficiency.

[0063] In this embodiment, the first through-hole 28 includes a first sub-through-hole 281 and a second sub-through-hole 282. The first sub-through-hole 281 and the second sub-through-hole 282 are located outside the cavity 27. The third through-hole 29 also includes two sub-through-holes and communicates with the first sub-through-hole 281 and the second sub-through-hole 282 respectively. The first sub-through-hole 281 and the sub-through-hole of the third through-hole 29 communicating therewith expose a part of the surface of the second thermoelectric strip 23. The second sub-through-hole 282 and the sub-through-hole of the third through-hole 29 communicating therewith expose a part of the surface of the second thermoelectric strip 23. In other embodiments, the first sub-through-hole 281 and the sub-through-hole of the third through-hole 29 communicating therewith expose a part of the surface of the first thermoelectric strip 21. The second sub-through-hole 282 and the sub-through-hole of the third through-hole 29 communicating therewith expose a part of the surface of the second thermoelectric strip 23, and the through-holes exposing the first thermoelectric strip 21 and the second thermoelectric strip 23 can be interchanged.

[0064] In this embodiment, the first through-hole 28 communicates with the third through-hole 29 penetrating the support layer 25. The opening size of the third through-hole 29 is smaller than that of the first through-hole 28, and the projection of the third through-hole 29 on the thermoelectric structure is included in the projection of the first through-hole 28 on the thermoelectric structure. The shapes of the third through-hole 29 and the first through-hole 28 are not limited and can be circular through-holes or strip-shaped through-holes. Similarly, the shape of the cavity 27 is not limited either. Since the function of the cavity 27 is heat insulation, it should be understood that the heat insulation effect is the best when the projection of the cavity 27 on the thermoelectric structure covers the thermocouple pair.

[0065] Reference Figure 11 , perform step S05: Remove the temporary substrate 10 to expose the absorption layer 11. In this embodiment, the temporary substrate 10 is removed by etching or mechanical grinding. In other embodiments, an isolation layer is further provided between the temporary substrate 10 and the absorption layer 11. The isolation layer serves as a stop layer for the grinding process to prevent excessive grinding. In other examples, the temporary substrate 10 can be removed by etching the isolation layer, which helps to quickly peel off the temporary substrate 10 and improve the process manufacturing efficiency. In another example, the position of the isolation layer can be replaced with a thermal expansion tape, and the temporary substrate 10 is peeled off by heating to make the thermal expansion tape lose its adhesiveness.

[0066] Reference Figure 12 , perform step S06: Form a second through-hole 31 in the first substrate 30. The second through-hole 31 penetrates the first substrate 30 and communicates with the first through-hole 28.

[0067] In this embodiment, the second through-hole 31 is formed by an etching process. The opening size of the first through-hole 28 is smaller than that of the second through-hole 31, and the projection of the first through-hole 28 on the thermoelectric structure is included in the projection of the second through-hole 31 on the thermoelectric structure. The shape of the second through-hole 31 is not limited and can be a circular through-hole or a strip through-hole. In other embodiments, it is sufficient that there is an overlapping part between the projection of the first through-hole 28 on the thermoelectric structure and the projection of the second through-hole 31 on the thermoelectric structure. In this embodiment, the second through-hole 31 includes a third sub-through-hole 311 and a fourth sub-through-hole 312, which communicate with the first sub-through-hole 281 and the second sub-through-hole 282 respectively.

[0068] Reference Figure 13 , in other embodiments, after forming the bonding layer 26 on the first substrate 30 and lithographing the cavity 27 and the first through-hole 28, before bonding the first substrate 30 and the support layer 25, the first substrate 30 is etched to form the second through-hole 31. The forming method, position, and shape refer to the above embodiments. After completing the etching process, the first substrate 30 and the support layer 25 are bonded.

[0069] Reference Figure 14 , step S07 is performed: an electrical connection structure 24 is formed in the first through-hole 28 and the second through-hole 31, and the electrical connection structure 24 connects the thermocouple pair and the external circuit.

[0070] In this embodiment, the electrical connection structure 24 includes a first electrical connection structure 212 and a second electrical connection structure 232. The method for forming the first electrical connection structure 212 includes: after bonding the first substrate 30 and the support layer 25 and forming the second through-hole 31, a first conductive material is formed in the third sub-through-hole 311, the first sub-through-hole 281, and the sub-through-hole of the third through-hole 29 communicating with the first sub-through-hole 281. The forming process includes: chemical vapor deposition, electroplating, evaporation plating, or electroless plating. The second electrical connection structure 232 is formed in the fourth sub-through-hole 312, the second sub-through-hole 282, and the sub-through-hole of the third through-hole 29 communicating with the second sub-through-hole 282. The forming method refers to the forming method of the first electrical connection structure 212. The first conductive material and the second conductive material for forming the second electrical connection structure 232 can be made of one of metals such as aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), etc. or a laminate formed by the above metals.

[0071] In this embodiment, the first electrical connection structure 212 is electrically connected to the second thermoelectric bar 23 and extends to the surface of the first substrate 30 away from the cavity 27; the second electrical connection structure 232 is electrically connected to the second thermoelectric bar 23 and extends to the surface of the first substrate 30 away from the cavity 27, so as to facilitate input and output of electrical signals. In other embodiments, the first electrical connection structure 212 is electrically connected to the first thermoelectric bar 21 and extends to the surface of the first substrate 30 away from the cavity 27; the second electrical connection structure 232 is electrically connected to the second thermoelectric bar 23 and extends to the surface of the first substrate 30 away from the cavity 27

[0072] Example 2

[0073] Embodiment 2 of the present invention provides an infrared sensor. Please refer to Figure 14 , the infrared sensor includes:

[0074] A first substrate 30, in which a circuit is provided;

[0075] A bonding layer 26 is disposed on the first substrate 30. The bonding layer 26 encloses a cavity 27, and the cavity 27 penetrates through the bonding layer 26;

[0076] A thermoelectric structure is located above the bonding layer 26 and covers the cavity 27. The thermoelectric structure includes at least one set of thermocouple pairs;

[0077] An electrical connection structure is disposed outside the cavity 27. The electrical connection structure penetrates through the bonding layer 26 and the first substrate 30, and the electrical connection structure connects the thermocouple pairs and an external circuit.

[0078] In this embodiment, the material of the bonding layer 26 is a lithography material. The lithography material includes a dry film. By providing the bonding layer 26 and using a bonding process to bond the first substrate 30 and the thermoelectric structure, the process of forming the thermoelectric structure can be separated from the process of forming the first substrate 30 and forming the cavity 27 on the bonding layer 26, thereby improving the packaging efficiency.

[0079] In this embodiment, an absorption layer 11 is further included. The absorption layer 11 is disposed on the thermoelectric structure. The function of forming the absorption layer 11 is to absorb infrared rays and effectively transfer the heat generated by absorbing infrared rays to the thermoelectric structure, thereby improving the device performance.

[0080] In this embodiment, a support layer 25 is further included. The support layer 25 is disposed between the thermoelectric structure and the cavity 27, and the electrical connection structure 24 also penetrates through the support layer 25. The support layer 25 has a heat insulation effect, preventing the thermoelectric structure from exchanging heat with the outside in the direction close to the support layer 25, and ensuring the quality and reliability of the sensor.

[0081] In this embodiment, part of the thermocouple pair is located above the cavity 27. The thermocouple pair includes a second thermoelectric strip 23 and a first thermoelectric strip 21 that are in contact with each other, and the second thermoelectric strip 23 and the first thermoelectric strip 21 are stacked. The thermocouple pair utilizes the principle of the "Seebeck effect" to manufacture a circuit with the first thermoelectric strip 21 and the second thermoelectric strip 23, and generates a thermoelectromotive force by generating a temperature difference, thereby measuring the amount of infrared rays incident on the infrared sensor. Among them, the first thermoelectric strip 21 and the second thermoelectric strip 23 can be arranged side by side on the same horizontal plane, or stacked in a direction perpendicular to the temporary substrate 10. In this embodiment, the first thermoelectric strip 21 and the second thermoelectric strip 23 are stacked.

[0082] In this embodiment, the high sensitivity of the infrared sensor is achieved by arranging a plurality of thermocouple pairs, and the quality and reliability of the sensor are improved. The electrical connection method between the thermocouple pairs is in series.

[0083] Regarding the materials, structures, and positional relationships of the first substrate 30, the bonding layer 26, the support layer 25, the first thermoelectric strip 21, the second thermoelectric strip 23, the barrier layer 22, and the absorption layer 11, refer to the corresponding parts of the previous method embodiments. Regarding the structure of the cavity 25, also refer to the corresponding parts of the previous method embodiments, and details will not be elaborated here.

[0084] By providing a bonding layer and using a bonding process to bond the first substrate and the thermoelectric structure, the present invention enables the process of forming the thermoelectric structure to be separated from the processes of forming the first substrate and forming the cavity and through holes on the bonding layer, thereby improving the packaging efficiency.

[0085] Furthermore, forming the cavity and the through holes on the bonding layer can be completed in the same process step, further improving the packaging efficiency.

[0086] Furthermore, since the through holes in the support layer and the cavity and through holes in the bonding layer are formed independently, the process difficulty is reduced, the risk of fragmentation caused by forming the cavity and through holes is avoided, and the quality, reliability, and yield of the sensor are improved.

[0087] Furthermore, the material of the bonding layer can be selected as a lithography material, and the cavity and the first through hole are formed by a lithography process, thereby avoiding damage to the bonding layer, the first substrate, or the support layer caused by the process of forming the bonding layer and the etching process, reducing the impact on the bonding strength of the bonding layer, being beneficial to improving the quality, reliability, and yield of the infrared sensor. At the same time, since the etching process steps are saved, the manufacturing cycle is shortened, and the packaging efficiency is improved.

[0088] It should be noted that each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the related parts, reference can be made to the partial description of the method embodiments.

[0089] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure are within the scope of protection of the claims.

Claims

1. A manufacturing method of an infrared sensor, characterized in that, Including: Providing a temporary substrate; Forming a thermoelectric structure on the temporary substrate, the thermoelectric structure including at least one set of thermocouple pairs; Providing a first substrate having a circuit therein; Forming a bonding layer on the first substrate or on the thermoelectric structure; Forming a cavity and a first through hole in the bonding layer, the cavity and the first through hole penetrating the bonding layer; Bonding the first substrate and the thermoelectric structure through the bonding layer, the first through hole exposing a part of the surface of the thermocouple pair; Removing the temporary substrate; Forming a second through hole in the first substrate, the second through hole penetrating the first substrate and communicating with the first through hole; Forming an electrical connection structure in the first through hole and the second through hole, the electrical connection structure connecting the thermocouple pair and an external circuit; The cavity and the first through hole are formed in the same process step; After forming the thermoelectric structure and before forming the bonding layer on the thermoelectric structure, further including: forming a support layer on the surface of the thermoelectric structure; The support layer has a third through hole penetrating the support layer, the first through hole communicating with the third through hole; the electrical connection structure fills the third through hole; The material of the bonding layer is a photolithographic material, the photolithographic material includes a dry film, and the cavity and the first through hole are formed in the bonding layer by a photolithography process.

2. The manufacturing method of the infrared sensor according to claim 1, characterized in that, Part of the thermocouple pair is located above the cavity, the thermocouple pair includes a second thermoelectric strip and a first thermoelectric strip in contact with each other, wherein the second thermoelectric strip and the first thermoelectric strip are stacked or arranged side by side.

3. The manufacturing method of the infrared sensor according to claim 1, wherein, The size of the first through hole is less than or equal to the size of the second through hole.

4. The manufacturing method of the infrared sensor according to claim 1, characterized in that The size of the third through hole is less than or equal to the size of the first through hole.

5. The manufacturing method of the infrared sensor according to claim 1, characterized in that, After forming the temporary substrate and before forming the thermoelectric structure, further including: forming an absorption layer covering the temporary substrate.

6. The manufacturing method of the infrared sensor according to claim 2, characterized in that, The first through hole includes a first sub-through hole and a second sub-through hole, the first sub-through hole and the second sub-through hole are located outside the cavity, the first sub-through hole exposes a part of the surface of the first thermoelectric strip, the second sub-through hole exposes a part of the surface of the second thermoelectric strip; the second through hole includes a third sub-through hole and a fourth sub-through hole, the third sub-through hole and the fourth sub-through hole communicate with the first sub-through hole and the second sub-through hole respectively.

7. The manufacturing method of the infrared sensor according to claim 6, characterized in that, The electrical connection structure includes a first electrical connection structure and a second electrical connection structure, the first electrical connection structure fills the first sub-through hole and the third sub-through hole, the first electrical connection structure connects the first thermoelectric strip and an external circuit, the second electrical connection structure fills the second sub-through hole and the fourth sub-through hole, the second electrical connection structure connects the second thermoelectric strip and an external circuit.

8. The manufacturing method of the infrared sensor according to claim 1, characterized in that, The method for forming the electrical connection structure includes: chemical vapor deposition, electroplating, evaporation plating or electroless plating.

9. The manufacturing method of the infrared sensor according to claim 2, characterized in that, There are multiple sets of the thermocouple pairs, and forming the thermoelectric structure includes: Forming a first thermoelectric strip material layer on the temporary substrate; patterning the first thermoelectric strip material layer to form a plurality of discrete first thermoelectric strips, and having a first groove between adjacent first thermoelectric strips; A barrier layer is formed on the temporary substrate and the first thermoelectric strip. The barrier layer covers the first thermoelectric strip and fills the first trench; the barrier layer is patterned to form a second trench, and the second trench exposes a part of the surface of the first thermoelectric strip. A second thermoelectric strip material layer is formed in the second trench and on the barrier layer; the second thermoelectric strip material layer is patterned to form a plurality of discrete second thermoelectric strips, with a third trench between adjacent second thermoelectric strips, and the second thermoelectric strips fill the second trench. The first thermoelectric strips and the second thermoelectric strips of adjacent thermocouple pairs are electrically connected to each other to form a plurality of groups of thermocouple pairs, and the electrical connection mode between the thermocouple pairs is in series.

10. The manufacturing method of the infrared sensor according to claim 9, characterized in that, One of the first thermoelectric strip and the second thermoelectric strip is made of a semiconductor material or a metal, and the other is a semiconductor material.

11. The manufacturing method of the infrared sensor according to claim 9, characterized in that, The material of the barrier layer includes: silicon dioxide, silicon nitride or aluminum oxide.

12. An infrared sensor, characterized in that, Comprising: A first substrate having a circuit therein. A bonding layer disposed on the first substrate. The bonding layer encloses a cavity that penetrates the bonding layer. A thermoelectric structure located above the bonding layer and covering the cavity. The thermoelectric structure includes at least one group of thermocouple pairs. An electrical connection structure disposed outside the cavity. The electrical connection structure penetrates the bonding layer and the first substrate, and the electrical connection structure connects the thermocouple pairs and an external circuit. The material of the bonding layer is a photolithographic material, and the photolithographic material includes a dry film. Further comprising a support layer disposed between the thermoelectric structure and the cavity, and the electrical connection structure also penetrates the support layer.

13. The infrared sensor according to claim 12, characterized in that, Further comprising an absorption layer disposed on the thermoelectric structure.

14. The infrared sensor according to claim 12, characterized in that, Part of the thermocouple pair is located above the cavity. The thermocouple pair includes a second thermoelectric strip and a first thermoelectric strip in contact with each other, wherein the second thermoelectric strip and the first thermoelectric strip are stacked or arranged side by side.

15. The infrared sensor according to claim 14, characterized in that, There are multiple groups of the thermocouple pairs, including: A plurality of the first thermoelectric strips, with a first trench provided between adjacent first thermoelectric strips to make the first thermoelectric strips discrete from each other. A barrier layer located above the second thermoelectric strip and filling the first trench. The barrier layer is provided with a second trench that penetrates the barrier layer. A plurality of the second thermoelectric strips, with a third trench provided between adjacent second thermoelectric strips to make the second thermoelectric strips discrete from each other. The second thermoelectric strips fill the second trench and are electrically connected to adjacent first thermoelectric strips to form a plurality of groups of thermocouple pairs, and the electrical connection mode between the thermocouple pairs is in series.

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