Thermocouple Sensor and its Fabrication Method

Abstract

This invention provides a thermocouple sensor, comprising a substrate, an isolation dielectric layer, a processing circuit, and a thermocouple structure. The processing circuit is disposed on the front side of the substrate and opposite to the cavity structure of the isolation dielectric layer. A portion of the thermocouple structure is disposed on the top surface of the isolation dielectric layer and spans the cavity structure, while another portion penetrates the isolation dielectric layer and makes electrical contact. This allows the thermocouple structure and the processing circuit to share the substrate area in terms of projected area, improving integration. The isolation dielectric layer has a cavity structure with an opening on its top surface to achieve a cavity structure on the front side of the substrate, avoiding the problems of high process complexity, low yield, and high cost caused by forming a back cavity on the back side of the substrate through deep silicon etching in the prior art. This invention also provides a method for fabricating the thermocouple sensor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing technology, and in particular to thermocouple sensors and their preparation methods. Background Technology

[0002] Traditional thermopile or thermocouple solutions involve manufacturing a separate thermopile chip and a processing circuit chip, which are then packaged together to form a product. Because the two chips are manufactured separately, the cost is relatively high. At the same time, in the traditional thermocouple structure, the hot and cold ends are made to contact on the front side of the silicon wafer, and the back cavity is formed on the back side of the silicon wafer through a deep silicon etching process. This process is highly complex, resulting in a low yield and high cost.

[0003] Utility model patent CN214121427U discloses a thermopile sensor system integrating CMOS circuitry, which forms the thermopile sensor and CMOS circuitry on a substrate using a process fully compatible with IC standard processes. However, the thermopile sensor formed by this utility model has low integration density.

[0004] Therefore, it is necessary to develop a new type of thermocouple sensor to solve the above-mentioned problems existing in the current technology. Summary of the Invention

[0005] The purpose of this invention is to provide a novel thermocouple sensor that can improve integration and avoid the problems of high process complexity, low yield and high cost caused by forming a back cavity on the back side of the substrate through deep silicon etching on the back side of the substrate in the prior art.

[0006] To achieve the above objectives, the thermocouple sensor of the present invention includes:

[0007] Substrate;

[0008] An isolation dielectric layer covers the front side of the substrate, and the isolation dielectric layer has a cavity structure with an opening on the top surface;

[0009] A processing circuit is disposed on the front side of the substrate, and the isolation dielectric layer covers the processing circuit.

[0010] The thermocouple structure has one part disposed on the top surface of the isolation medium layer and spanning the cavity structure, and the other part penetrating the isolation medium layer and making electrical contact with the processing circuit.

[0011] The beneficial effects of the thermocouple sensor of the present invention are as follows: the processing circuit is disposed on the front side of the substrate, a part of the thermocouple structure is disposed on the top surface of the isolation dielectric layer and spans the cavity structure, and the other part penetrates the isolation dielectric layer and makes electrical contact, so that the thermocouple structure and the processing circuit can share the substrate area in terms of projected area, thereby improving the integration density; the isolation dielectric layer is provided with a cavity structure with a top opening to realize the cavity structure on the front side of the substrate, avoiding the problems of high process complexity, low yield and high cost caused by forming a back cavity on the back side of the substrate through a back deep silicon etching process in the prior art.

[0012] Preferably, the thermocouple structure includes: a plurality of bridge structures arranged sequentially on the top surface of the insulating dielectric layer and spanning the cavity structure; each bridge structure includes a first thermocouple portion and a second thermocouple portion connected to each other to sense temperature and generate a thermoelectric potential; and a plurality of conductive interconnecting structures sequentially connecting adjacent bridge structures to achieve a series connection of the plurality of bridge structures, and electrically contacting the processing circuit after passing through the bridge structures and the insulating dielectric layer. Its beneficial effect is: improved integration.

[0013] More preferably, the absolute value of the difference between the Seebeck coefficient of the constituent material of the first thermocouple section and the Seebeck coefficient of the constituent material of the second thermocouple section is greater than 1.

[0014] More preferably, the plurality of conductive interconnect structures are connected in series with the plurality of bridge structures to form a serpentine interconnect structure.

[0015] More preferably, the plurality of conductive interconnect structures include a plurality of top conductive interconnect structures, which are sequentially connected to adjacent bridge structures to achieve a series connection of the plurality of bridge structures.

[0016] More preferably, the middle part of the bridge structure is a hot end structure, and the plurality of conductive interconnect structures further include a plurality of middle conductive interconnect structures. The plurality of middle conductive interconnect structures pass through both ends of the bridge structure and the isolation dielectric layer and then make electrical contact with the processing circuit.

[0017] More preferably, the top conductive interconnect structure covers the top of the middle conductive interconnect structure.

[0018] More preferably, the bridge structure further includes a hot-end connection structure, which connects the first thermocouple portion and the second thermocouple portion to form the hot-end structure.

[0019] More preferably, in two adjacent bridge structures, the first thermocouple portion of one bridge structure is connected to the second thermocouple portion of the other bridge structure via the same top conductive interconnect structure.

[0020] More preferably, the hot-end connection structure includes a top hot-end connection structure, which electrically contacts the top surface of the first thermocouple portion and the top surface of the second thermocouple portion.

[0021] More preferably, the hot-end connection structure further includes a middle hot-end connection structure disposed between the first thermocouple portion and the second thermocouple portion, and electrically contacting the top hot-end connection structure, so as to enhance the conductivity and connection between the first thermocouple portion and the second thermocouple portion.

[0022] More preferably, the top hot-end connection structure covers the top of the middle hot-end connection structure.

[0023] More preferably, the hot-end connection structure further includes a fill connection structure composed of undoped semiconductor material, the fill connection structure being disposed between the first thermocouple portion and the second thermocouple portion.

[0024] More preferably, at least a portion of the top surface of the filling connection structure and at least a portion of the bottom surface of the central hot end connection structure are in contact.

[0025] More preferably, the middle hot-end connection structure and the middle conductive interconnect structure have the same constituent material, and the top hot-end connection structure and the top conductive interconnect structure have the same constituent material.

[0026] The method for preparing the thermocouple sensor of the present invention includes the following steps:

[0027] S1: Provide a substrate, and arrange processing circuitry on the front side of the substrate;

[0028] S2: Form an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and expose the top surface of the release dielectric layer;

[0029] S3: A thermocouple structure is provided across the release medium layer on the top surface of the isolation medium layer, so that at least a portion of the top surface of the release medium layer is exposed, and the thermocouple structure makes electrical contact with the processing circuit after penetrating the isolation medium layer;

[0030] S4: Remove the release medium layer to form a cavity structure.

[0031] The beneficial effects of the method for fabricating the thermocouple sensor of the present invention are as follows: by setting a processing circuit on the front side of the substrate, then forming an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer and exposing the top surface of the release dielectric layer, and setting a thermocouple structure across the release dielectric layer on the top surface of the isolation dielectric layer, exposing at least a portion of the top surface of the release dielectric layer, and making the thermocouple structure electrically contact the processing circuit after penetrating the isolation dielectric layer, the thermocouple structure and the processing circuit can share the substrate area in terms of projected area, thereby improving the integration density; finally, in step S4, the release dielectric layer is removed to form a cavity structure, so that the cavity structure is formed on the front side of the substrate, avoiding the problems of high process complexity, low yield and high cost caused by forming a back cavity on the back side of the substrate through a back deep silicon etching process in the prior art.

[0032] Preferably, in step S1, the step of setting the processing circuit on the front side of the substrate includes forming a plurality of metal interconnect structures on the front side of the substrate and exposing the top surfaces of the plurality of metal interconnect structures. The advantage of this is that it facilitates subsequent electrical connection of the thermocouple structure.

[0033] More preferably, in step S2, the step of forming an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and exposing the top surface of the release dielectric layer, includes:

[0034] S21: An initial isolation layer covering the front side of the substrate and an inner release layer embedded within the initial isolation layer are formed using an isolation material and a release material;

[0035] S22: A groove structure with a top opening is etched from the top surface of the initial isolation layer with a portion of the top surface of the inner release layer as the stopping position. The groove structure is filled with the release material to form an outer release layer. The inner release layer and the outer release layer constitute the release medium layer.

[0036] More preferably, in step S3, the step of providing a thermocouple structure across the release medium layer on the top surface of the isolation medium layer, exposing a portion of the top surface of the release medium layer, and ensuring that the thermocouple structure penetrates the isolation medium layer and makes electrical contact with the processing circuit includes:

[0037] S31: Using a semiconductor material, a plurality of initial bridge structures are formed across the release dielectric layer on the top surface of the isolation dielectric layer. Then, an ion implantation process is performed to form a plurality of bridge structures and expose a portion of the top surface of the release dielectric layer. The bridge structure includes two thermocouple portions that are connected and composed of different materials.

[0038] S32: Form a plurality of central conductive interconnect structures and a plurality of central hot-end connection structures, such that the top of the plurality of central conductive interconnect structures is exposed, and after penetrating both ends of each bridge structure and the isolation dielectric layer, it makes electrical contact with the corresponding metal interconnect structure, and the central hot-end connection structure is connected to the middle of each bridge structure and the top is exposed.

[0039] S33: A top conductive interconnect structure is formed by using a top conductive material to cover the top of each of the central conductive interconnect structures and to connect several of the bridge structures in series, and a top hot end connection structure is formed to cover the top of each central hot end connection structure and to connect the first thermocouple portion and the second thermocouple portion of the same bridge structure.

[0040] More preferably, in step S4, the step of removing the release medium layer to form a cavity structure includes: etching the release medium layer with a release gas to remove the release medium layer. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the first thermocouple sensor according to an embodiment of the present invention;

[0042] Figure 2 for Figure 1 A top view of the thermocouple structure shown;

[0043] Figure 3 This is a schematic diagram of the structure of the second thermocouple sensor according to an embodiment of the present invention;

[0044] Figure 4 This is a flowchart illustrating the fabrication method of a thermocouple sensor according to an embodiment of the present invention.

[0045] Figure 5 These are schematic diagrams of the structures obtained after forming metal interconnect structures on a substrate according to some embodiments of the present invention;

[0046] Figure 6 In order to be in Figure 5 A schematic diagram of the structure obtained after depositing the first isolation layer and the first release layer on the basis of the structure shown;

[0047] Figure 7 In order to be in Figure 6 A schematic diagram of the structure obtained by removing part of the first release layer from the structure shown.

[0048] Figure 8 In order to be in Figure 7 A schematic diagram of the structure obtained after depositing a second isolation layer on the structure shown;

[0049] Figure 9 In order to be in Figure 8A schematic diagram of the structure obtained after forming an outer release layer on the basis of the structure shown;

[0050] Figure 10 In order to be in Figure 9 A schematic diagram of the structure obtained after forming an amorphous silicon patterned layer on the basis of the structure shown.

[0051] Figure 11 In order to be in Figure 10 A schematic diagram of the structure obtained after performing ion implantation and laser annealing processes on the structure shown.

[0052] Figure 12 In order to be in Figure 11 A schematic diagram of the structure obtained after forming several interconnecting through holes and trench structures on the basis of the structure shown;

[0053] Figure 13 In order to be in Figure 12 A schematic diagram of the structure obtained after forming a central conductive interconnect structure and a central hot-end connection structure based on the structure shown.

[0054] Figure 14 In order to be in Figure 13 A schematic diagram of the structure obtained after forming a top hot-end connection structure and a top conductive interconnect structure based on the structure shown. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0056] This invention provides a highly integrated thermocouple sensor, including a substrate, a processing circuit, and a thermocouple structure.

[0057] Figure 1 This is a schematic diagram of the structure of the first thermocouple sensor according to an embodiment of the present invention. Figure 2 for Figure 1 The top view of the thermocouple structure shown.

[0058] Reference Figure 1 , Figure 1The thermocouple sensor shown includes a substrate 11, a processing circuit (not shown) disposed on the substrate 11, and a thermocouple structure disposed on the front side of the substrate 11 and including an isolation dielectric layer 13, a plurality of bridge structures 15 and a plurality of conductive interconnect structures 14.

[0059] In this embodiment of the invention, the processing circuit is disposed on the front side of the substrate, the isolation dielectric layer covers the front side of the substrate and the processing circuit, a portion of the thermocouple structure is disposed on the top surface of the isolation dielectric layer and spans the cavity structure, and another portion penetrates the isolation dielectric layer and makes electrical contact with the processing circuit.

[0060] Reference Figure 1 The processing circuit (not shown in the figure) includes a plurality of metal interconnect structures 12 disposed on the substrate 11, the top surfaces of the plurality of metal interconnect structures 12 being exposed to the substrate 11 and electrically contacting the plurality of conductive interconnect structures 14.

[0061] Reference Figure 1 and Figure 2 The isolation dielectric layer 13 covers the top surface of the substrate 11 and a plurality of the metal interconnect structures 12, and is provided with a cavity structure 16 with an opening on the top surface; a plurality of bridge structures 15 are arranged sequentially on the top surface of the isolation dielectric layer 13 and span the cavity structure 16; a plurality of conductive interconnect structures 14 are connected in series with the plurality of bridge structures 15 and pass through the isolation dielectric layer 13 to make electrical contact with the plurality of metal interconnect structures 12, so as to realize electrical contact between the thermocouple structure and the processing circuit.

[0062] Since the isolation dielectric layer 13 is provided with the cavity structure 16 with the top opening, the problems of high process complexity, low yield and high cost caused by forming the back cavity on the back side of the substrate 11 through the back deep silicon etching process in the prior art are avoided.

[0063] The processing circuit, including a plurality of the metal interconnect structures 12, is disposed on the front side of the substrate 11 and located below the cavity structure 16, so that the thermocouple structure and the processing circuit can share the substrate area in terms of projected area, thereby improving the integration.

[0064] In some specific embodiments, the insulating dielectric layer 13 is composed of silicon nitride.

[0065] In some embodiments, the conductive interconnect structure 14 includes a top conductive interconnect structure and a middle conductive interconnect structure. (Refer to...) Figure 1 and Figure 2 The top conductive interconnect structure 142 makes electrical contact with two adjacent bridge structures 15 to achieve a series connection between the two adjacent bridge structures 15.

[0066] In some embodiments, reference is made to Figure 1 and Figure 2 Each of the bridge structures 15 includes a first thermocouple section 151 and a second thermocouple section 152. The first thermocouple section 151 and the second thermocouple section 152 are connected and made of different materials to form a hot end structure in the middle of each bridge structure 15.

[0067] Specifically, the first thermocouple section 151 and the second thermocouple section 152 are made of different materials. The hot end structure serves as the measuring end to receive heat. Due to the temperature difference between the two ends of each thermocouple section, a thermoelectric potential is generated. The measuring temperature is determined by measuring the magnitude of the thermoelectric potential and based on a certain proportional relationship between the magnitude of the thermoelectric potential and the measuring temperature.

[0068] In some embodiments, the absolute value of the difference between the Seebeck coefficient of the constituent material of the first thermocouple section 151 and the Seebeck coefficient of the constituent material of the second thermocouple section 152 is greater than 1.

[0069] In some embodiments, reference is made to Figure 1 and Figure 2 Several of the central conductive interconnect structures 141 penetrate both ends of the bridge structure 15 and the isolation dielectric layer 13 and then make electrical contact with the processing circuit (not shown in the figure).

[0070] Specifically, a portion of the central conductive interconnect structure 141 penetrates the end of each first thermocouple portion 151 away from the middle of the cavity structure 16 and the isolation medium layer 13, and electrically contacts the metal interconnect structures 12 corresponding to the plurality of first thermocouple portions 151. Another portion of the central conductive interconnect structure 141 penetrates the end of each second thermocouple portion 152 away from the middle of the cavity structure 16 and the isolation medium layer 13, and electrically contacts the metal interconnect structures 12 corresponding to the plurality of second thermocouple portions 152.

[0071] In some specific embodiments, the first thermocouple section 151 is made of N-type polycrystalline silicon, and the second thermocouple section 152 is made of P-type polycrystalline silicon.

[0072] In some specific embodiments, the first thermocouple portion 151 is made of aluminum, and the second thermocouple portion 152 is made of silicon.

[0073] In some embodiments, the central conductive interconnect structure 141 can form a silicide with the first thermocouple portion 151 to enhance the electrical contact performance and bonding strength with the first thermocouple portion 151.

[0074] In some specific embodiments, the central conductive interconnect structure 141 is composed of Ti, TiN, Al, or Al.

[0075] In some embodiments, reference is made to Figure 1 and Figure 2 The bridge structures 15 are arranged sequentially along direction A, and the top conductive interconnection structures 142 connect the bridge structures 15 end to end in sequence to realize the series connection of the bridge structures 15.

[0076] In some specific embodiments, reference is made to Figure 2 The two adjacent bridge structures 15 and the top conductive interconnect structure 142 connecting the two adjacent bridge structures 15 form a U-shaped structure.

[0077] In some specific embodiments, several of the bridge structures 15 are arranged in parallel to each other and are all parallel to the substrate 11.

[0078] In some specific embodiments, the bridge structures 15 are arranged in a three-dimensional series connection. Specifically, at least two of the bridge structures 15 have different vertical distances relative to the substrate 11, and the projections of different bridge structures 15 toward the substrate 11 do not overlap.

[0079] In some embodiments, the top conductive interconnect structure 142 covers the top of the middle conductive interconnect structure 141. (See also...) Figure 1 The central conductive interconnect structure 141 includes a first protruding conductive structure 143 that penetrates the bridge structure 15 and forms the top surface of the bridge structure 15. The first protruding conductive structure 143 protrudes from the top surface of the first thermocouple portion 151, and the top conductive interconnect structure 142 covers the surface of the first protruding conductive structure 143.

[0080] In some embodiments, in two adjacent bridge structures, the first thermocouple portion of one bridge structure is connected to the second thermocouple portion of the other bridge structure via the same top conductive interconnect structure.

[0081] In some embodiments, the top conductive interconnect structure 142 is composed of either Au or Pt.

[0082] Figure 3 This is a schematic diagram of the structure of a second thermocouple sensor according to an embodiment of the present invention.

[0083] In some embodiments, reference is made to Figure 2 The first thermocouple section 151 and the second thermocouple section 152 are connected by a hot-end connection structure 21.

[0084] In some embodiments, the middle portion of the plurality of bridge structures 15 faces the middle portion of the cavity structure 16. Specifically, the plurality of hot-end connection structures 21 are disposed facing the middle portion of the cavity structure 16.

[0085] Specifically, refer to Figure 2 and Figure 3 The hot-end connection structure 21 includes a top hot-end connection structure 31, which electrically contacts the top surface of the first thermocouple part 151 and the top surface of the second thermocouple part 152 to achieve electrical conductivity between the first thermocouple part 151 and the second thermocouple part 152 and strengthen the connection between the first thermocouple part 151 and the second thermocouple part 152.

[0086] In some embodiments, the top hot-end connection structure 31 and the top conductive interconnect structure 142 have the same constituent materials.

[0087] In some specific embodiments, the top hot end connection structure 31 is composed of either Au or Pt.

[0088] Specifically, refer to Figure 2 and Figure 3 The hot end connection structure 21 further includes a middle hot end connection structure 32 disposed between the first thermocouple part 151 and the second thermocouple part 152 and electrically contacting the top hot end connection structure 31, so as to enhance the conductivity and connection between the first thermocouple part 151 and the second thermocouple part 152.

[0089] Specifically, the top hot-end connection structure 31 covers the top of the middle hot-end connection structure 32. (See reference...) Figure 2 and Figure 3 The middle hot end connection structure 32 includes a second protruding conductive structure 34 protruding from the top surface of the first thermocouple part 151 and the top surface of the second thermocouple part 152, and the top hot end connection structure 31 covers the surface of the second protruding conductive structure 34.

[0090] In some embodiments, the central hot-end connection structure 32 and the central conductive interconnect structure 141 have the same constituent materials.

[0091] In some specific embodiments, the central hot-end connection structure 32 is composed of Ti, TiN, Al, or Al.

[0092] In some embodiments, reference is made to Figure 2 and Figure 3 The hot-end connection structure 21 further includes a filled connection structure 33 composed of undoped semiconductor material.

[0093] In some embodiments, reference is made to Figure 2 and Figure 3 The filling connection structure 33 is disposed between the first thermocouple part 151 and the second thermocouple part 152.

[0094] In some embodiments, reference is made to Figure 3 At least a portion of the top surface of the filling connection structure 33 and at least a portion of the bottom surface of the central hot end connection structure 32 are in contact.

[0095] In some specific embodiments, the filling connection structure 33 is composed of undoped polycrystalline silicon.

[0096] This invention also provides a method for preparing the thermocouple sensor, referring to... Figure 4 This includes the following steps:

[0097] S1: Provide a substrate, and arrange processing circuitry on the front side of the substrate;

[0098] S2: Form an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and expose the top surface of the release dielectric layer;

[0099] S3: A thermocouple structure is provided across the release medium layer on the top surface of the isolation medium layer, so that part of the top surface of the release medium layer is exposed, and the thermocouple structure makes electrical contact with the processing circuit after penetrating the isolation medium layer;

[0100] S4: Remove the release medium layer.

[0101] Figure 5 This is a schematic diagram of the structure obtained after forming a metal interconnect structure on the substrate in some embodiments of the present invention.

[0102] In step S1 of some embodiments, reference is made to Figure 5 The step of setting the processing circuit on the front side of the substrate 11 includes forming a plurality of the metal interconnect structures 12 on the front side of the substrate 11 and exposing the top surface of the plurality of the metal interconnect structures 12.

[0103] In some embodiments, the processing circuit in step S1 is a read circuit. In other embodiments, the processing circuit in step S1 is an application-specific integrated circuit (ASIC).

[0104] In some embodiments, step S2, the step of forming an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and exposing the top surface of the release dielectric layer, includes:

[0105] S21: An initial isolation layer covering the front side of the substrate and an inner release layer embedded within the initial isolation layer are formed using an isolation material and a release material;

[0106] S22: A groove structure with a top opening is etched from the top surface of the initial isolation layer with a portion of the top surface of the inner release layer as the stopping position. The groove structure is filled with the release material to form an outer release layer. The inner release layer and the outer release layer constitute the release medium layer.

[0107] Figure 6 In order to be in Figure 5 A schematic diagram of the structure obtained after depositing the first isolation layer and the first release layer on the basis of the structure shown. Figure 7 In order to be in Figure 6 A schematic diagram of the structure obtained by removing part of the first release layer from the structure shown. Figure 8 In order to be in Figure 7 A schematic diagram of the structure obtained after depositing a second isolation layer on the structure shown.

[0108] Reference Figures 6 to 8 In step S21, the step of forming an initial isolation layer covering the front side of the substrate and an inner release layer embedded within the initial isolation layer using an isolation material and a release material includes:

[0109] S211: A first isolation layer 61 and a first release layer 62 are sequentially deposited on the front side of the substrate 11 using a first isolation material and a first release material, respectively, to form a stacked first isolation layer 61 and a first release layer 62.

[0110] S212: Remove part of the first release layer 62 to obtain the inner release layer 71, and expose part of the top surface of the first isolation layer 61;

[0111] S213: A second isolation layer 81 is formed by depositing a second isolation material to encapsulate the inner release layer 71 and cover the exposed top surface of the first isolation layer 61. The second isolation layer 81 and the first isolation layer 61 constitute the initial isolation layer 82.

[0112] In some embodiments, step S212, the step of removing part of the first release layer 62 to obtain the inner release layer 71 includes: controlling the volume of the inner release layer 71 to be greater than the cavity volume of the preset cavity structure.

[0113] In some embodiments, the composition of either the first isolation material or the second isolation material differs from that of the first release material. Subsequent etching of the inner release layer 71 using the release gas does not affect the structure of the first isolation layer 61 and the second isolation layer 81.

[0114] In some embodiments, the first insulating material and the second insulating material are the same insulating material. In some specific embodiments, both the first insulating material and the second insulating material are silicon nitride.

[0115] In some embodiments, the first insulating material and the second insulating material are different insulating materials.

[0116] In some embodiments, the inner release layer 71 is composed of silicon oxide.

[0117] Figure 9 In order to be in Figure 8 A schematic diagram of the structure obtained after forming an outer release layer on the basis of the structure shown.

[0118] After step S213 is completed, step S22 is executed, referring to... Figure 8 and Figure 9 A groove structure with a top opening is etched from the top surface of the initial isolation layer 82, with a portion of the top surface of the inner release layer 71 as the stopping position. The groove structure (not shown in the figure) is filled with the release material to form an outer release layer 91. The inner release layer 71 and the outer release layer 91 constitute a release medium layer 92.

[0119] Furthermore, starting from the top surface of the initial isolation layer 82 and stopping at the top surface of the inner release layer 71, a portion of the second isolation layer 81 is removed, forming a third isolation layer 93 with its top surface flush with the top surface of the outer release layer 91. The first isolation layer 61 and the third isolation layer 93 together constitute the isolation medium layer 13.

[0120] In some embodiments, the release material used to fill the groove structure has the same composition as the first release material.

[0121] In some embodiments, the release material used to fill the groove structure has a different composition than the first release material, and the subsequent etching process of the inner release layer 71 and the outer release layer 91 with different release gases will not affect the structure of the first isolation layer 61 and the third isolation layer 93.

[0122] In some specific embodiments, the release material used to fill the groove structure is silicon dioxide.

[0123] In some embodiments, step S3, which involves providing a thermocouple structure across the release medium layer on the top surface of the isolation medium layer, exposing a portion of the top surface of the release medium layer, and ensuring that the thermocouple structure penetrates the isolation medium layer and makes electrical contact with the processing circuit, includes:

[0124] S31: Using a semiconductor material, a plurality of initial bridge structures are formed across the release dielectric layer on the top surface of the isolation dielectric layer. Then, an ion implantation process is performed to form a plurality of bridge structures and expose a portion of the top surface of the release dielectric layer. The bridge structure includes two thermocouple portions that are connected and composed of different materials.

[0125] S32: Form a plurality of central conductive interconnect structures and a plurality of central hot-end connection structures, such that the top of the plurality of central conductive interconnect structures is exposed, and after penetrating both ends of each bridge structure and the isolation dielectric layer, it makes electrical contact with the corresponding metal interconnect structure, and the central hot-end connection structure is connected to the middle of each bridge structure and the top is exposed.

[0126] S33: A top conductive interconnect structure is formed by using a top conductive material to cover the top of each of the central conductive interconnect structures and to connect several of the bridge structures in series, and a top hot end connection structure is formed to cover the top of each central hot end connection structure and to connect the first thermocouple portion and the second thermocouple portion of the same bridge structure.

[0127] Figure 10 In order to be in Figure 9 A schematic diagram of the structure obtained after forming an amorphous silicon patterned layer on the basis of the structure shown. Figure 11 In order to be in Figure 10 A schematic diagram of the structure obtained after performing ion implantation and laser annealing processes on the structure shown.

[0128] In step S31 of some embodiments, reference is made to Figure 10 and Figure 11 The steps of forming a plurality of initial bridge structures across the release dielectric layer on the top surface of the isolation dielectric layer using a semiconductor material, and then performing an ion implantation process to form a plurality of bridge structures include:

[0129] S311: An initial amorphous semiconductor layer (not shown in the figure) is formed by low-temperature deposition of semiconductor material covering the top surface of the outer release layer 91 and the top surface of the third isolation layer 93;

[0130] S312: The initial amorphous semiconductor layer (not shown in the figure) is patterned and etched to form a plurality of sequentially arranged initial bridge structures 101, and a portion of the top surface of the third isolation layer 93 and a portion of the top surface of the outer release layer 91 are exposed.

[0131] S313: Using ion implantation and laser annealing processes, each of the initial bridge structures 101 is formed into a bridge structure consisting of the first thermocouple portion 151 and the second thermocouple portion 152 connected to each other.

[0132] In some embodiments, the constituent material of the initial amorphous semiconductor layer formed in step S311 is amorphous silicon.

[0133] In step S313 of some embodiments, the first thermocouple portion 151 formed is made of N-type polycrystalline silicon through the ion implantation process and the laser annealing process, and the second thermocouple portion 152 is made of P-type polycrystalline silicon.

[0134] In step S313 of some embodiments, reference is made to Figure 11 During the process of ion implantation on the initial bridge structure 101, the initial filling connection structure 1101 composed of undoped polycrystalline silicon is maintained between the first thermocouple part 151 and the second thermocouple part 152 to strengthen the connection between the first thermocouple part 151 and the second thermocouple part 152.

[0135] Figure 12 In order to be in Figure 11 A schematic diagram of the structure obtained after forming several interconnecting through holes and trench structures on the basis of the structure shown. Figure 13 In order to be in Figure 12 A schematic diagram of the structure obtained after forming a central conductive interconnect structure and a central hot-end connection structure based on the structure shown.

[0136] In step S32 of some embodiments, reference is made to Figure 11 , Figure 12 and Figure 13 The steps for forming several central hot-end connection structures include:

[0137] S321: Starting from the top surface of each first thermocouple portion 151 and stopping at the top surface of each metal interconnect structure 12, a plurality of interconnect vias 1201 are etched, and a trench structure 1202 with a top surface opening is formed at the connection between the first thermocouple portion 151 and the second thermocouple portion 152 in the same bridge structure (not shown in the figure). The trench structure 1202 exposes at least a portion of the top surface of the initial filling connection structure 1101. Specifically, a portion of the plurality of interconnect vias 1201 penetrates the first thermocouple portion 151, and another portion penetrates the second thermocouple portion 152. The plurality of interconnect vias 1201 penetrate the isolation medium layer 13 composed of the first isolation layer 61 and the third isolation layer 93, and expose at least a portion of the top surface of each metal interconnect structure 12.

[0138] S322: A central conductive interconnect structure 141 is formed using a first conductive material to fill each of the interconnect vias 1201 and expose the top; a central hot-end connection structure 34 is formed using a second conductive material to fill each of the trench structures 1202 and expose the top surfaces of the first thermocouple portion 151 and the second thermocouple portion 152 of the same bridge structure.

[0139] In some embodiments, in step S322, the first conductive material and the second conductive material are the same conductive material, and the central conductive interconnect structure 141 and the central hot end connection structure 34 are formed synchronously using the same conductive material.

[0140] In some specific embodiments, each of the interconnect vias 1201 and the trench structure 1202 is filled and covered with the same conductive material. Figure 12 After the top surface of the structure shown is exposed, a portion of the same conductive material is etched after patterning. The portion filling the interconnect vias 1201 and exposed at the top is retained as the central conductive interconnect structure 141, and the portion filling the trench structure 1202 and exposed at the top surface of the first thermocouple portion 151 and the second thermocouple portion 152 is retained as the central hot-end connection structure 34. Specifically, Figure 12 The exposed top surfaces of the structure shown are the top surface of the first thermocouple section 151, the top surface of the second thermocouple section 152, the exposed top surface of the outer release layer 91, and the exposed top surface of the third isolation layer 93.

[0141] In some more specific embodiments, the same conductive material is Ti, TiN, or Al.

[0142] In some embodiments, in step S322, the first conductive material and the second conductive material are different types of conductive materials. The formation order of the central conductive interconnect structure 141 and the central hot-end connection structure 34 can be flexibly adjusted according to process conditions.

[0143] Figure 14 In order to be in Figure 13 A schematic diagram of the structure obtained after forming a top hot-end connection structure and a top conductive interconnect structure based on the structure shown.

[0144] In step S33 of some embodiments, reference is made to Figure 13 and Figure 14 The steps of forming a top conductive interconnect structure covering the top of each of the central conductive interconnect structures and connecting several of the bridge structures in series using a top conductive material, and forming a top hot-end connection structure covering the top of each central hot-end connection structure and connecting a first thermocouple portion and a second thermocouple portion of the same bridge structure, include:

[0145] A top conductive material is used to deposit a cover. Figure 13After the initial top conductive material layer (not shown in the figure) of the exposed surface of the structure is patterned, part of the initial top conductive material layer (not shown in the figure) is etched away, and the initial top material layer covering the top of the middle conductive interconnect structure 141 and connecting two adjacent bridge structures (not shown in the figure) is retained as the top conductive interconnect structure 142. The initial top material layer covering the top of the middle hot end connection structure 34 and connecting the first thermocouple part 151 and the second thermocouple part 152 of the same bridge structure is retained as the top hot end connection structure 31.

[0146] In step S4 of some embodiments, reference is made to Figure 1 and Figure 14 The step of removing the release medium layer includes: etching the release medium layer 92, which is composed of the inner release layer 71 and the outer release layer 91, using a release gas to remove the release medium layer 92, thereby forming the cavity structure 16 with a top opening. A suitable release gas is selected such that the etching process of the release medium layer 92 with the release gas does not damage the isolation medium layer 13, which is composed of the first isolation layer 61 and the third isolation layer 93.

[0147] In some specific embodiments, the first isolation layer 61 and the third isolation layer 93 are both made of silicon nitride, the inner release layer 71 and the outer release layer 91 are both made of silicon oxide, and the release gas used is hydrofluoric acid.

[0148] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A thermocouple sensor, characterized in that, include: Substrate; An isolation dielectric layer covers the front side of the substrate, and the isolation dielectric layer has a cavity structure with an opening on the top surface; A processing circuit is disposed on the front side of the substrate, and the isolation dielectric layer covers the processing circuit. Thermocouple structure includes several bridge structures and several conductive interconnect structures. The bridge structure includes a first thermocouple section and a second thermocouple section connected to each other to sense temperature and generate thermoelectric potential. The plurality of bridge structures are disposed on the top surface of the isolation medium layer and span the cavity structure. The plurality of conductive interconnect structures are sequentially connected to adjacent bridge structures to achieve a series connection of the plurality of bridge structures, and the plurality of conductive interconnect structures include a plurality of central conductive interconnect structures, wherein a portion of the central conductive interconnect structures penetrates the end of each first thermocouple portion away from the middle of the cavity structure and the isolation medium layer, and electrically contacts the processing circuit; another portion of the central conductive interconnect structures penetrates the end of each second thermocouple portion away from the middle of the cavity structure and the isolation medium layer, and electrically contacts the processing circuit.

2. The thermocouple sensor according to claim 1, characterized in that, The bridge structures are arranged sequentially on the top surface of the isolation medium layer and span the cavity structure.

3. The thermocouple sensor according to claim 2, characterized in that, The absolute value of the difference between the Seebeck coefficient of the constituent material of the first thermocouple section and the Seebeck coefficient of the constituent material of the second thermocouple section is greater than 1.

4. The thermocouple sensor according to claim 2, characterized in that, The plurality of conductive interconnect structures include a plurality of top conductive interconnect structures, which are sequentially connected to adjacent bridge structures to achieve a series connection of the plurality of bridge structures.

5. The thermocouple sensor according to claim 4, characterized in that, The middle part of the bridge structure is a hot-end structure, and the top conductive interconnect structure covers the top of the middle conductive interconnect structure.

6. The thermocouple sensor according to claim 5, characterized in that, The bridge structure further includes a hot-end connection structure, which connects the first thermocouple portion and the second thermocouple portion to form the hot-end structure.

7. The thermocouple sensor according to claim 6, characterized in that, In two adjacent bridge structures, the first thermocouple section of one bridge structure is connected to the second thermocouple section of the other bridge structure via the same top conductive interconnect structure.

8. The thermocouple sensor according to claim 6, characterized in that, The hot-end connection structure includes a top hot-end connection structure, which electrically contacts the top surface of the first thermocouple portion and the top surface of the second thermocouple portion.

9. The thermocouple sensor according to claim 8, characterized in that, The hot-end connection structure further includes a middle hot-end connection structure disposed between the first thermocouple portion and the second thermocouple portion, and electrically contacting the top hot-end connection structure, so as to enhance the conductivity and connection between the first thermocouple portion and the second thermocouple portion, and the top hot-end connection structure covers the top of the middle hot-end connection structure.

10. The thermocouple sensor according to claim 9, characterized in that, The middle hot-end connection structure and the middle conductive interconnect structure have the same constituent materials, and the top hot-end connection structure and the top conductive interconnect structure have the same constituent materials.

11. A method for fabricating a thermocouple sensor, characterized in that, Includes the following steps: S1: A substrate is provided, and a processing circuit including a plurality of metal interconnect structures is disposed on the front side of the substrate; S2: Form an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and expose the top surface of the release dielectric layer; S3: A thermocouple structure is provided across the release medium layer on the top surface of the isolation medium layer, exposing at least a portion of the top surface of the release medium layer, and the thermocouple structure makes electrical contact with the processing circuit after penetrating the isolation medium layer; including: S31: Using a semiconductor material, a plurality of initial bridge structures are formed across the release dielectric layer on the top surface of the isolation dielectric layer. Then, an ion implantation process is performed to form a plurality of bridge structures and expose a portion of the top surface of the release dielectric layer. The bridge structure includes two thermocouple portions that are connected and composed of different materials. S32: Form a plurality of central conductive interconnect structures and a plurality of central hot-end connection structures, such that the top of the plurality of central conductive interconnect structures is exposed, and after penetrating both ends of each bridge structure and the isolation dielectric layer, it makes electrical contact with the corresponding metal interconnect structure, and the central hot-end connection structure is connected to the middle of each bridge structure and the top is exposed. S33: A top conductive interconnect structure is formed by using a top conductive material to cover the top of each of the middle conductive interconnect structures and to connect several of the bridge structures in series, and a top hot end connection structure is formed to cover the top of each middle hot end connection structure and to connect the first thermocouple portion and the second thermocouple portion of the same bridge structure. S4: Remove the release medium layer to form a cavity structure.

12. The preparation method according to claim 11, characterized in that, In step S1, the step of setting the processing circuit on the front side of the substrate includes forming the plurality of metal interconnect structures on the front side of the substrate and exposing the top surface of the plurality of metal interconnect structures.

13. The preparation method according to claim 12, characterized in that, In step S2, the step of forming an isolation dielectric layer covering the front side of the substrate and a release dielectric layer embedded in the isolation dielectric layer, and exposing the top surface of the release dielectric layer, includes: S21: An initial isolation layer covering the front side of the substrate and an inner release layer embedded within the initial isolation layer are formed using an isolation material and a release material; S22: A groove structure with a top opening is etched from the top surface of the initial isolation layer with a portion of the top surface of the inner release layer as the stopping position. The groove structure is filled with the release material to form an outer release layer. The inner release layer and the outer release layer constitute the release medium layer.

14. The preparation method according to claim 11, characterized in that, In step S4, the step of removing the release medium layer to form the cavity structure includes: The release medium layer is removed by etching with a release gas.

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