Thermocouple Sensor and Its Preparation Method

Abstract

The present invention provides a thermocouple sensor and a preparation method thereof. An inner cavity structure and a blocking structure are arranged in a substrate of the thermocouple sensor. The blocking structure surrounds an opening end of the inner cavity structure, avoiding the formation of a back cavity by using a complex back process and effectively reducing the process cost; controlling the top opening range of the inner cavity structure through the blocking structure is beneficial to improving the integration degree.

Description

Technical Field

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

[0002] Traditional thermocouple sensors rely on a back process to form their back cavities. For example, the thermopile infrared detector disclosed in the Chinese patent application with the publication number CN112670397A involves backside lithography and backside etching through the substrate. The process integration scheme has very high resource requirements and requires a large number of equipment to be configured to achieve, resulting in a relatively high chip cost.

[0003] Therefore, it is necessary to develop a new type of thermocouple sensor to solve the above problems existing in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to provide a thermocouple sensor and a preparation method thereof realized by a front process to improve the integration degree and reduce the process cost.

[0005] To achieve the above purpose, the thermocouple sensor of the present invention includes:

[0006] A substrate, including a blocking structure and an inner cavity structure provided in the substrate, and a plurality of release channels provided on the top surface of the substrate;

[0007] The blocking structure surrounds the opening end of the inner cavity structure;

[0008] The inner cavity structure communicates with the outside through the plurality of release channels;

[0009] A thermocouple structure, provided on the top surface of the substrate, the thermocouple structure is correspondingly arranged with the inner cavity structure, and the plurality of release channels are exposed.

[0010] The beneficial effect of the thermocouple sensor of the present invention is that: an inner cavity structure and a blocking structure are provided in the substrate, and the blocking structure surrounds and is connected to the opening end of the inner cavity structure to enclose a top inner cavity structure, avoiding the use of a complex back process to form a back cavity, effectively reducing the process cost; by controlling the top opening range of the inner cavity structure through the blocking structure, it is beneficial to improve the integration degree.

[0011] Preferably, the inner cavity structure includes a bottom inner cavity structure, the blocking structure surrounds the opening end of the inner cavity structure to form a top cavity structure, and the bottom cavity structure communicates with the top inner cavity structure. Its beneficial effect is that: the space of the inner cavity structure is increased, enhancing its function as a resonant cavity.

[0012] Further preferably, the range of any radial cross-section of the area surrounded by the inner sidewall of the top inner cavity structure is smaller than the range of any radial cross-section of the area surrounded by the inner sidewall of the bottom inner cavity structure. The beneficial effect is that: the integration degree is improved and the function of the inner cavity structure as a resonant cavity is enhanced.

[0013] Further preferably, the substrate includes a base and an insulating structure disposed on the top surface of the base. The inner cavity structure is disposed within the base, and the blocking structure is disposed at the bottom of the insulating structure and is connected to the open end of the inner cavity structure to enclose the top inner cavity structure.

[0014] Further preferably, the etching selectivity ratio of the constituent material of the base to the constituent material of the insulating structure in the same etching environment is greater than or equal to 1000:1.

[0015] Further preferably, the etching selectivity ratio of the constituent material of the base to the constituent material of the blocking structure in the same etching environment is greater than or equal to 1000:1.

[0016] Further preferably, the etching selectivity ratio of the constituent material of the base to the constituent material of the thermocouple structure in the same etching environment is greater than or equal to 1000:1.

[0017] Preferably, the thermocouple structure includes a plurality of thermocouples disposed on the top surface of the substrate and connected in series. Each thermocouple is located between two adjacent release channels. The beneficial effect is that: the functions of the top inner cavity structure and the bottom outer cavity structure as resonant cavities are enhanced, and the output effect of the thermoelectromotive force signal is strengthened.

[0018] Further preferably, each thermocouple includes a first thermocouple part and a second thermocouple part with different constituent materials and connected to each other. Among two adjacent thermocouples, the first thermocouple part of one thermocouple is connected to the second thermocouple part of the other thermocouple.

[0019] Further preferably, the thermocouple structure further includes a plurality of conductive interconnect structures. Among two adjacent thermocouples, the first thermocouple part of one thermocouple and the second thermocouple part of the other thermocouple are connected to the same conductive interconnect structure.

[0020] Further preferably, the absolute value of the difference between the Seebeck coefficient of the constituent material of the first thermocouple part and the Seebeck coefficient of the constituent material of the second thermocouple part is greater than 1.

[0021] Preferably, each of the thermocouples further includes a thermocouple connection structure. The top parts of the thermocouple connection structure are respectively overlapped and connected with the first thermocouple part and the second thermocouple part, and the bottom parts of the thermocouple connection structure are respectively connected with the first thermocouple part and the second thermocouple part to realize the connection of the first thermocouple part and the second thermocouple part. The beneficial effect is as follows: the integration degree is improved.

[0022] Further preferably, the top of the thermocouple connection structure has the same composition material as the first thermocouple part or the second thermocouple part, and the bottom of the thermocouple connection structure has different composition materials from both the first thermocouple part and the second thermocouple part.

[0023] Further preferably, the first thermocouple part, the second thermocouple part and the thermocouple connection structure are of an integrated structure.

[0024] The preparation method of the thermocouple sensor of the present invention includes the following steps:

[0025] S1: Provide a substrate, and form a blocking structure connected end to end in the substrate. The area surrounded by the bottom of the blocking structure in the substrate is an enclosed structure;

[0026] S2: Form a thermocouple structure on the top surface of the substrate, make the thermocouple structure correspond to the enclosed structure, and expose a part of the top surface of the substrate;

[0027] S3: Etch from the exposed top surface of the substrate towards the bottom surface of the substrate to form a plurality of release channels, and expose a part of the top surface of the enclosed structure;

[0028] S4: Remove the enclosed structure through the plurality of release channels to form a cavity structure communicated with the plurality of release channels.

[0029] The beneficial effect of the preparation method of the thermocouple sensor of the present invention is as follows: By forming a blocking structure connected end to end in the substrate in step S1, it is convenient to control the range of the top opening of the cavity structure through step S5 subsequently, avoiding the use of complex backside processes to form a back cavity, effectively reducing the process cost, and being beneficial to improving the integration degree.

[0030] Preferably, in step S1, the step of forming a blocking structure connected end to end in the substrate includes:

[0031] S11: Provide a base, and deposit and form an initial insulating structure on the top surface of the base;

[0032] S12: Sequentially remove a part of the initial insulating structure and a part of the substrate in the direction from the top surface of the initial insulating structure to the bottom surface of the substrate, and then fill with a barrier material to form the barrier structure.

[0033] Preferably, in step S5, the inner cavity structure formed by removing the surrounding structure through the plurality of release channels is a top inner cavity structure. After step S5 is completed, further remove the part of the structure between the bottom surface of the barrier structure and the bottom surface of the substrate to form a bottom inner cavity structure communicating with the top inner cavity structure.

[0034] Preferably, in step S2, the step of forming the thermocouple structure on the top surface of the substrate includes:

[0035] S21: Use a semiconductor material to form a plurality of initial thermocouples on the top surface of the substrate, and expose the top surface of the substrate located between adjacent initial thermocouples;

[0036] S22: Perform a plurality of doping processes to sequentially dope donor impurities into one end of each initial thermocouple, acceptor impurities into the other end of each initial thermocouple, and either the donor impurities or the acceptor impurities into the middle of each initial thermocouple to form a thermocouple connection structure.

[0037] Through step S21 and step S22, the processing technology is simplified and the integration degree is improved. Description of the Drawings

[0038] Figure 1 is a schematic structural diagram of a thermocouple sensor according to an embodiment of the present invention;

[0039] Figure 2 is Figure 1 a top view of the thermocouple sensor shown;

[0040] Figure 3 is a top view of another thermocouple sensor according to an embodiment of the present invention;

[0041] Figure 4 is a schematic structural diagram of a thermocouple according to an embodiment of the present invention;

[0042] Figure 5 is a schematic structural diagram of another thermocouple according to an embodiment of the present invention;

[0043] Figure 6 is a schematic diagram of the structure obtained after forming the bottom insulating structure and the middle insulating structure on the substrate according to an embodiment of the present invention;

[0044] Figure 7 is at Figure 6Schematic diagram of the structure obtained after forming a blocking structure on the shown structure;

[0045] Figure 8 is Figure 7 Top view of the shown structure;

[0046] Figure 9 is after Figure 7 Schematic diagram of the structure obtained after forming a number of initial thermocouples on the top surface of the middle insulating structure on the shown structure;

[0047] Figure 10 is after Figure 9 Schematic diagram of the structure obtained after performing a number of doping processes on the shown structure;

[0048] Figure 11 is for Figure 9 Schematic diagram of the structure of the shown initial thermocouple;

[0049] Figure 12 is for Figure 11 Schematic diagram of the structure obtained after successively performing the first doping process and the second doping process on the shown initial thermocouple;

[0050] Figure 13 is after Figure 10 Schematic diagram of the structure obtained after forming a top insulating structure and a number of lead hole structures on the shown structure;

[0051] Figure 14 is after Figure 13 Schematic diagram of the structure obtained after forming a number of conductive interconnect structures on the shown structure;

[0052] Figure 15 is after Figure 14 Schematic diagram of the structure obtained after forming a number of release channels on the shown structure;

[0053] Figure 16 is after Figure 15 Schematic diagram of the structure obtained after removing part of the substrate on the shown structure. Detailed implementation manner

[0054] 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 described clearly and completely below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. The words such as "including" used herein are intended to mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0055] The embodiments of the present invention provide a thermocouple sensor implemented by a front process and a preparation method thereof to improve the integration degree and reduce the process cost.

[0056] The thermocouple sensor of the embodiments of the present invention includes a substrate and a thermocouple structure disposed on the front surface of the substrate.

[0057] Figure 1 It is a schematic structural diagram of a thermocouple sensor of the embodiments of the present invention. Figure 2 For Figure 1 The top view of the shown thermocouple sensor. Figure 3 It is the top view of another thermocouple sensor of the embodiments of the present invention.

[0058] In some embodiments, the substrate includes a blocking structure and a cavity structure disposed in the substrate. Refer to Figure 1 , Figure 1 In the shown thermocouple sensor, the blocking structure 16 disposed in the substrate 11 surrounds the opening end of the cavity structure 12 to form a top cavity structure 121 and forms a bottom cavity structure 122 communicating with the top cavity structure 121 along the direction from the top to the bottom of the substrate 11.

[0059] Since the blocking structure 16 defines the opening range of the top cavity structure 121, by setting the range surrounded by the blocking structure 16, the processing area of the thermocouple structure (not marked in the figure) disposed on the top surface of the substrate 11 can be controlled, which is beneficial to improving the integration degree and controlling the processing accuracy. Refer to Figure 1 and Figure 3 , by adjusting the size of the substrate 11 and the range of the area surrounded by the blocking structure 16 according to the process requirements, more of the thermocouples 14 can be extended in series on the top surface of the substrate 11.

[0060] In some embodiments, the inner cavity structure provided in the substrate 11 is the top inner cavity structure 121 surrounded by the blocking structure 16. The range of the top inner cavity structure 121 only needs to meet the requirements for the normal operation of the thermocouple structure.

[0061] In some embodiments, the substrate includes a base and an insulating structure provided on the top surface of the base, and the base and the insulating structure enclose the inner cavity structure. Refer to Figure 1 , the bottom insulating structure 112, the middle insulating structure 113, and the top insulating structure 114 stacked in sequence form an insulating structure covering the top surface of the base 111. The inner cavity structure 12 is provided in the base 111, and the blocking structure is provided at the bottom of the insulating structure formed by the bottom insulating structure 112, the middle insulating structure 113, and the top insulating structure 114, and surrounds the opening end of the inner cavity structure 12 to form the top inner cavity structure 121.

[0062] In some embodiments, the range of any radial cross-section of the region surrounded by the inner sidewall of the bottom inner cavity structure 122 is larger than the range of any radial cross-section of the region surrounded by the inner sidewall of the top inner cavity structure 121, so as to increase the range of the inner cavity structure 12 serving as the resonant cavity of the thermocouple structure and enhance its function. The so-called range of the radial cross-section refers to the range surrounded by the closed cross-sectional line formed by sectioning the top inner cavity structure 121 or the bottom inner cavity structure 122 along the Figure 1 A-A direction shown in the figure.

[0063] In some embodiments, the relationship between the range of any radial cross-section of the region surrounded by the inner sidewall of the top inner cavity structure 121 and the range of any radial cross-section of the region surrounded by the inner sidewall of the bottom inner cavity structure 122 can be flexibly adjusted according to actual needs.

[0064] In some embodiments, the etching rate ratio of the composition material of the base 111 to the composition material of the insulating structure in the same etching environment is greater than 1000:1, which is beneficial to the process of etching the base 111 during the preparation of the thermocouple sensor having less or no impact on the structural integrity of the insulating structure, and does not affect the insulating function of the insulating structure and the supporting function for the thermocouple structure.

[0065] Furthermore, the specific composition of the insulating structure is not limited to Figure 1As shown, it is composed of the bottom insulation structure 112, the middle insulation structure 113, and the top insulation structure 114. The specific composition can be flexibly adjusted according to actual process requirements to meet the requirement that the process of etching the substrate 111 during the preparation of the thermocouple sensor has little or no impact on the structural integrity of the insulation structure, and does not affect the insulation function of the insulation structure and the support function for the thermocouple structure. For example, the structural composition materials of the insulation structure may not be completely the same or may be different from each other. The insulation structure can also be an integral structure composed of the same composition material.

[0066] In some specific embodiments, the composition material of the substrate 111 is silicon.

[0067] In some specific embodiments, the composition material of the bottom insulation structure 112 is silicon oxide.

[0068] In some specific embodiments, the composition material of the top insulation structure 114 is silicon oxide.

[0069] In some specific embodiments, the composition material of the middle insulation structure 113 is silicon nitride.

[0070] In some embodiments, the etching rate ratio of the composition material of the substrate 111 to the composition material of the barrier structure 16 in the same etching environment is greater than 1000:1, which is beneficial to the process of etching the substrate 111 during the preparation of the thermocouple sensor having little or no impact on the structural integrity of the barrier structure 16.

[0071] In some embodiments, the barrier structure 16 can be an integral structure or a composite structure.

[0072] In some embodiments, a part of the barrier structure 16 penetrates the bottom of the insulation structure to be disposed in the insulation structure.

[0073] In some specific embodiments, referring to Figure 1 , the barrier structure 16 penetrates the middle insulation structure 113 and the bottom insulation structure 112, and the top surface is flush with the middle insulation structure 113.

[0074] In some specific embodiments, the barrier structure 16 is disposed at the bottom of the insulation structure.

[0075] In some specific embodiments, the composition material of the barrier structure 16 is silicon oxide and silicon nitride, and mainly silicon oxide. More specifically, the barrier structure 16 is a sandwich structure composed of a silicon oxide layer, a silicon nitride layer, and a silicon oxide layer.

[0076] In some embodiments, with reference to Figure 1 , a plurality of release channels 13 are provided on the top surface of the substrate 11. The top inner cavity structure 121 communicates with the outside through the plurality of release channels 13.

[0077] In some embodiments, the thermocouple structure is disposed on the top surface of the substrate and faces the cavity region of the top inner cavity structure 121. With reference to Figure 1 and Figure 2 , the thermocouple structure (not labeled in the figure) includes a plurality of thermocouples 14 connected in series. The plurality of thermocouples 14 are correspondingly disposed with the cavity region of the top inner cavity structure 121, and the plurality of release channels 13 are exposed. Each thermocouple 14 is located between two adjacent release channels 13.

[0078] In some embodiments, the arrangement of the thermocouples 14 can be flexibly adjusted according to process requirements to ensure that the hot end structure, that is, the middle part of the thermocouple 14 faces the cavity region of the top inner cavity structure 121, and the two ends may not face or not completely face the cavity region of the top inner cavity structure 121.

[0079] In some embodiments, with reference to Figure 2 , each thermocouple 14 includes a first thermocouple part 141 and a second thermocouple part 142 made of different materials and connected to each other. The first thermocouple part 141 and the second thermocouple part 142 are connected to form a hot end structure. The hot end structure receives heat as the measurement end. Since there is a temperature difference between the middle part and the two ends of each thermocouple 14, a thermoelectromotive force can be generated and output.

[0080] In some embodiments, the absolute value of the difference between the Seebeck coefficient of the material of the first thermocouple part 141 and the Seebeck coefficient of the material of the second thermocouple part 142 is greater than 1.

[0081] In some specific embodiments, the material of the first thermocouple part 141 is N-type polysilicon, and the material of the second thermocouple part 142 is P-type polysilicon.

[0082] In some embodiments, between two adjacent thermocouples 14, the first thermocouple part of one thermocouple is connected to the second thermocouple part of the other thermocouple.

[0083] In some embodiments, with reference to Figure 2 , the plurality of thermocouples 14 are connected in series through a plurality of conductive interconnect structures 15.

[0084] In some embodiments, between two adjacent thermocouples 14, the first thermocouple part of one thermocouple and the second thermocouple part of the other thermocouple are connected to the same conductive interconnect structure 15.

[0085] In some embodiments, the installation position of the conductive interconnect structure 15 can be flexibly adjusted according to process requirements, as long as the hot end structures of all the thermocouples 14 face the cavity region of the top inner cavity structure 121.

[0086] In some embodiments, referring to Figure 1 and Figure 2 , all the conductive interconnect structures 15 are correspondingly arranged with the cavity region of the top inner cavity structure 121.

[0087] In some embodiments, all the conductive interconnect structures 15 are not correspondingly arranged with the cavity region of the top inner cavity structure 121, that is: the projection plane formed by projecting all the conductive interconnect structures 15 along the Figure 1 direction B shown is not projected onto the bottom surface within the cavity structure 12.

[0088] In some embodiments, all the conductive interconnect structures 15 are not completely correspondingly arranged with the cavity region of the top inner cavity structure 121, that is: the projection plane formed by projecting a part of the conductive interconnect structures 15 among all the conductive interconnect structures 15 along the Figure 1 direction B shown is not projected onto the bottom surface within the cavity structure 12, and the projection plane formed by projecting another part of the conductive interconnect structures 15 along the Figure 1 direction B shown has an overlapping region with the bottom surface within the cavity structure 12.

[0089] In some specific embodiments, the constituent material of the conductive interconnect structure 15 is Ti / TiN / Al or Al.

[0090] Figure 4 FIG. Figure 5 FIG.

[0091] In some embodiments, each thermocouple further includes a thermocouple connection structure for connecting the first thermocouple portion and the second thermocouple portion.

[0092] In some embodiments, referring to Figure 4 and Figure 5, the thermocouple connection structure 41 includes a top connection structure 411 at the top and a bottom connection structure 412 at the bottom. Both ends of the top connection structure 411 are respectively overlapped and connected with the first thermocouple part 141 and the second thermocouple part 142, that is, one end of the top connection structure 411 and one end of the first thermocouple part 141 are overlapped and connected to form a first overlapping region 413, and the other end of the top connection structure 411 and one end of the second thermocouple part 142 are overlapped and connected to form a second overlapping region 414. Both ends of the bottom connection structure 412 are respectively connected to the first thermocouple part 141 and the second thermocouple part 142.

[0093] In some embodiments, referring to Figure 4 and Figure 5 , the top surfaces of the thermocouple connection structure 41, the first thermocouple part 141 and the second thermocouple part 142 are flush with each other, which is beneficial to improving the integration degree.

[0094] In some embodiments, referring to Figure 4 and Figure 5 , the bottom surfaces of the thermocouple connection structure 41, the first thermocouple part 141 and the second thermocouple part 142 are flush with each other, which is beneficial to improving the integration degree.

[0095] In some embodiments, referring to Figure 4 , at the top of the thermocouple connection structure 41, that is, the top connection structure 411 and the first thermocouple part 141 are made of the same composition material.

[0096] In some specific embodiments, the composition materials of the top connection structure 411 and the first thermocouple part 141 are both N-type polysilicon.

[0097] In some specific embodiments, the top connection structure 411 and the first thermocouple part 141 are both N-type polysilicon and have different doping concentrations, and the second thermocouple part 142 is P-type polysilicon. Specifically, referring to Figure 4 , when the doping concentration of the top connection structure 411 is lower than that of the first thermocouple part 141, the acceptor impurity doping concentration in the first overlapping region 413 is higher than that in the first thermocouple part 141, and both donor impurity doping and acceptor impurity doping exist in the second overlapping region 414.

[0098] In some embodiments, referring to Figure 4 , at the bottom of the thermocouple connection structure 41, that is, the bottom connection structure 412 is made of different composition materials from those of the first thermocouple part 141 and the second thermocouple part 142.

[0099] In some specific embodiments, the constituent material of the bottom connection structure 412 is undoped polysilicon.

[0100] In some embodiments, the first thermocouple part 141, the second thermocouple part 142 and the thermocouple connection structure 41 are an integrated structure.

[0101] The embodiment of the present invention also provides a preparation method of the thermocouple sensor, including the following steps:

[0102] S1: Provide a substrate, and form a blocking structure connected end to end in the substrate. The area surrounded by the bottom of the blocking structure in the substrate is an enclosed structure;

[0103] S2: Form a thermocouple structure on the top surface of the substrate, so that each thermocouple structure is correspondingly arranged with the enclosed structure, and part of the top surface of the substrate is exposed;

[0104] S3: Etch from the exposed top surface of the substrate towards the bottom surface of the substrate to form a plurality of release channels, and part of the top surface of the enclosed structure is exposed;

[0105] S4: Remove the enclosed structure through the plurality of release channels to form a top cavity structure communicating with the plurality of release channels.

[0106] In the step S5 of some embodiments, the cavity structure formed by removing the enclosed structure through the plurality of release channels is a top cavity structure.

[0107] In some embodiments, after the step S5 is completed, further remove the part of the structure between the bottom surface of the blocking structure and the bottom surface of the substrate to form a bottom cavity structure communicating with the top cavity structure.

[0108] In the step S2 of some embodiments, the step of forming a plurality of thermocouples on the top surface of the substrate includes:

[0109] S21: Use a semiconductor material to form a plurality of initial thermocouples on the top surface of the substrate, and expose the top surface of the substrate located between adjacent initial thermocouples;

[0110] S22: Perform a doping process to sequentially dope donor impurities to one end of each initial thermocouple, dope acceptor impurities to the other end of each initial thermocouple, and dope any one of the donor impurities and the acceptor impurities to the middle of each initial thermocouple to form a thermocouple connection structure.

[0111] The following is a Figures 6 to 16 detailed description of the preparation method of the thermocouple sensor according to the embodiment of the present invention.

[0112] Figure 6 This is a schematic diagram of the structure obtained after forming the bottom insulation structure and the middle insulation structure on the substrate in the embodiment of the present invention. Figure 7 After Figure 6 This is a schematic diagram of the structure obtained after forming the barrier structure on the basis of the structure shown. Figure 8 After Figure 7 This is a top view of the structure shown.

[0113] In the step S1 of some embodiments, with reference to Figures 6 to 8 , the step of removing a part of the substrate from the top surface of the substrate and then filling it with a barrier material to form a barrier structure connected end to end includes:

[0114] S11: Provide the substrate 111, and deposit and form an initial insulation structure (not marked in the figure) on the top surface of the substrate 111; specifically, the bottom insulation structure 112 and the middle insulation structure 113 sequentially deposited on the top surface of the substrate 111 constitute the initial insulation structure;

[0115] S12: Sequentially remove a part of the initial insulation structure (not marked in the figure) and a part of the substrate 111 in the direction from the top surface of the initial insulation structure (not marked in the figure) to the bottom surface of the substrate 111, and then fill it with a barrier material to form the barrier structure 16.

[0116] In the step S12 of some embodiments, a shallow trench isolation process is used to form the barrier structure 16 connected end to end, so that the barrier structure 16 penetrates through the bottom insulation structure 112 and the middle insulation structure 113, and penetrates through the top of the substrate 111.

[0117] In the step S1 of some embodiments, with reference to Figure 7 , the area surrounded by the bottom of the barrier structure 16 in the substrate 111 is the surrounding structure 71.

[0118] In the step S12 of some embodiments, the step of using a shallow trench isolation process to form the barrier structure 16 connected end to end includes:

[0119] S121: Etch from the top surface of the middle insulation structure 113 in the direction towards the bottom surface of the substrate 111 to form a trench structure connected end to end, so that the trench structure penetrates through the bottom insulation structure 112 and the middle insulation structure 113, and penetrates through the top of the substrate 111;

[0120] S122: Deposit an oxide layer on the inner wall of the trench structure by Furnace Liner - Ox;

[0121] S123: After depositing a nitride layer on the inner wall of the remaining trench structure, perform several depositions and fillings of an oxide layer to form an initial barrier structure that fills the trench structure and covers the top surface of the middle insulating structure 113;

[0122] S124: Remove a part of the initial barrier structure to form the barrier structure 16.

[0123] In the step S124 of some embodiments, a part of the initial barrier structure is removed by Chemical Mechanical Planarization (CMP).

[0124] Figure 9 For Figure 7 Schematic diagram of the structure obtained after forming several initial thermocouples on the top surface of the middle insulating structure based on the shown structure.

[0125] In the step S21 of some embodiments, referring to Figure 8 and Figure 9 , the setting of the barrier structure 16 encloses a process area 81 on the top surface of the middle insulating structure 113, and several initial thermocouples are formed within the range of the process area 81.

[0126] In the step S21 of some embodiments, referring to Figure 8 and Figure 9 , the steps of forming several initial thermocouples on the top surface of the substrate using a semiconductor material include: after depositing an intrinsic semiconductor material on the top surface of the middle insulating structure 113 to form an initial thermocouple layer (not labeled in the figure), patterning the initial thermocouple layer (not labeled in the figure) to form several initial thermocouples 91 disposed on the top surface of the process area 81.

[0127] Figure 10 For Figure 9 Schematic diagram of the structure obtained after doping process based on the shown structure. Figure 11 For Figure 9 Schematic diagram of the structure of the initial thermocouple shown. Figure 12 For Figure 11 Schematic diagram of the structure obtained after sequentially performing the first doping process and the second doping process on the initial thermocouple shown.

[0128] In the step S22 of some embodiments, the thermocouple 14 is formed by doping the same initial thermocouple 91, avoiding the use of complex patterning processes and stacked structures, thereby reducing the process cost and improving the processing accuracy.

[0129] Specifically, referring to Figure 4 and Figures 10 to 12 , the steps of performing the doping process include:

[0130] S221: Use a photoresist material to block the exposed top surface of the middle insulating structure 113, the exposed top surface of the blocking structure 16, and other structures of each of the initial thermocouples 91 except for the top surface of the first end portion 1101;

[0131] S222: Perform a first ion implantation process to implant donor impurities into the first end portion 1101 of each of the initial thermocouples 91 to form a number of initial first thermocouple portions 1201, and then remove the photoresist material;

[0132] S223: Use a photoresist material to block the exposed top surface of the middle insulating structure 113, the exposed top surface of the blocking structure 16, and other structures of each of the initial thermocouples 91 except for the top surface of the second end portion 1102;

[0133] S224: Perform a second ion implantation process to implant acceptor impurities into the second end portion 1102 of each of the initial thermocouples 91 to form a number of initial second thermocouple portions 1202, and then remove the photoresist material. A middle non-doped region 1203 is formed between the initial first thermocouple portion 1201 and the initial second thermocouple portion 1202;

[0134] S225: Use a photoresist material to block the exposed top surface of the middle insulating structure 113, the exposed top surface of the blocking structure 16, and partial structures of each of the initial thermocouples 91 obtained after the step S224, so that the top surface of the middle non-doped region 1203, the partial top surface of the initial first thermocouple portion 1201 that is in contact with the middle non-doped region 1203, and the partial top surface of the initial second thermocouple portion 1202 that is in contact with the middle non-doped region 1203 are exposed;

[0135] S226: Perform a third ion implantation process to implant donor impurities or acceptor impurities into the top of the middle non-doped region 1203, the partial region of the initial first thermocouple portion 1201 that is in contact with the middle non-doped region 1203, and the partial region of the initial second thermocouple portion 1202 that is in contact with the middle non-doped region 1203 to form an initial thermocouple connection structure (not labeled in the figure), and then remove the photoresist material;

[0136] S227: Perform a laser annealing process to activate the doping.

[0137] Figure 13 For Figure 10 A schematic diagram of the structure obtained after forming a top insulating structure and a number of lead hole structures on the basis of the structure shown. Figure 14 For Figure 13 A schematic diagram of the structure obtained after forming a number of conductive interconnect structures on the basis of the structure shown.

[0138] In step S3 of some embodiments, with reference to Figure 13 , the step of filling the region between adjacent thermocouples with an insulating material and exposing at least a part of the top surface of both ends of the thermocouple includes:

[0139] S31: Depositing an initial top insulating structure (not labeled in the figure) on the top surface of the middle insulating structure 113 using an insulating material, so that the initial top insulating structure (not labeled in the figure) embeds a plurality of the thermocouples 14;

[0140] S32: Removing a part of the initial top insulating structure (not labeled in the figure) to obtain the top insulating structure 114, forming lead hole structures 1301 at both ends of each thermocouple 14, and exposing the top surface of each thermocouple 14 located between the two lead hole structures 1301.

[0141] In step S32 of some embodiments, patterning the initial top insulating structure to remove a part of the initial top insulating structure (not labeled in the figure).

[0142] In step S3 of some embodiments, with reference to Figure 13 and Figure 14 , the step of covering the exposed top surfaces of both ends of the thermocouple with a conductive material and sequentially connecting two adjacent thermocouples includes:

[0143] S33: Depositing an initial conductive interconnect structure (not labeled in the figure) on the top insulating structure 114 using a conductive material to fill a plurality of the lead hole structures 1301, and covering a part of the top surface of the top insulating structure 114 and the exposed surfaces of each thermocouple 14;

[0144] S34: Removing a part of the initial conductive interconnect structure (not labeled in the figure) to form a plurality of conductive interconnect structures 15 that connect the thermocouples 14 in series, and exposing other surfaces of each thermocouple 14 except the surfaces covered by the conductive interconnect structures 15.

[0145] In step S34 of some embodiments, after using a photoresist material to block the areas that need to be protected, a wet etching process is used to form a plurality of conductive interconnect structures 15, and the surfaces of each thermocouple 14 covered by the conductive material are exposed.

[0146] Figure 15 Schematic diagram of the structure obtained after forming a plurality of release channels on the basis of the structure shown in Figure 14 .

[0147] In step S4 of some embodiments, with reference to Figure 14 andFigure 15 The step of etching the region between two adjacent ones of the thermocouples in a direction from the top surface of the substrate toward the bottom surface of the substrate to form a plurality of release channels includes:

[0148] After using a photoresist material to shield the regions where a plurality of the thermocouples 14 and a plurality of the conductive interconnect structures 15 are located, etching is performed on the region between two adjacent ones of the thermocouples 14 and the region between the thermocouple 14 and the blocking structure 16 in a direction from the top surface of the top insulating structure 114 toward the bottom surface of the substrate 111, to form a plurality of release channels 13. The release channels 13 penetrate through the top insulating structure 114, the middle insulating structure 113, and the bottom insulating structure 112, and expose the top surface of the surrounding structure 71.

[0149] In the step S4 of some embodiments, a dry etching process is used to etch the region between two adjacent ones of the thermocouples 14 and the region between the thermocouple 14 and the blocking structure 16 in a direction from the top surface of the top insulating structure 114 toward the bottom surface of the substrate 111.

[0150] In the step S4 of some embodiments, after a plurality of the release channels 13 are formed, the photoresist material is removed.

[0151] Figure 16 For Figure 15 a schematic diagram of the structure obtained after removing a part of the substrate on the basis of the shown structure.

[0152] In the step S5 of some embodiments, with reference to Figure 15 and Figure 16 the step of removing the surrounding structure through the plurality of release channels to form a top inner cavity structure communicating with the plurality of release channels includes:

[0153] Using a corrosive gas to corrode the substrate 111 through the plurality of release channels 13, and then removing the surrounding structure 71 surrounded by the blocking structure 16 to form the top inner cavity structure 121.

[0154] After the step S5 of some embodiments is completed, with reference to Figure 16 using a corrosive gas to further remove a part of the structure between the bottom surface of the blocking structure 16 and the bottom surface of the substrate 111 to form a bottom inner cavity structure 122 communicating with the top inner cavity structure 121.

[0155] In some embodiments, a corrosive gas used for corroding the substrate 111 is reasonably selected according to actual conditions, and the influence of this corrosive gas on the blocking structure 16 can be ignored, and the influence on the structure including the insulating structure and the thermocouple structure disposed on the top surface of the substrate 111 can be ignored.

[0156] In some specific embodiments, the etching gas used to etch the substrate 111 is XeF2 gas.

[0157] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A thermocouple sensor, characterized in that, Comprising: A substrate, including a barrier structure and an inner cavity structure disposed within the substrate, and a plurality of release channels disposed on the top surface of the substrate; The barrier structure surrounds the opening end of the inner cavity structure; The inner cavity structure communicates with the outside through the plurality of release channels; A thermocouple structure is disposed on the top surface of the substrate. The thermocouple structure is correspondingly disposed with the inner cavity structure and exposes the plurality of release channels; the inner cavity structure includes a top inner cavity structure and a bottom inner cavity structure. The barrier structure surrounds the opening end of the inner cavity structure to form the top inner cavity structure, and the bottom inner cavity structure communicates with the top inner cavity structure; the radial cross-sectional range of any region surrounded by the inner sidewall of the top inner cavity structure is smaller than the radial cross-sectional range of any region surrounded by the inner sidewall of the bottom inner cavity structure.

2. The thermocouple sensor according to claim 1, wherein, The substrate includes a base and an insulating structure disposed on the top surface of the base. The inner cavity structure is disposed within the base, and the barrier structure is disposed at the bottom of the insulating structure and surrounds the opening end of the inner cavity structure.

3. The thermocouple sensor according to claim 2, characterized in that, The etching selectivity ratio of the constituent material of the base to the constituent material of the insulating structure in the same etching environment is greater than or equal to 1000:1, and the etching selectivity ratio of the constituent material of the base to the constituent material of the barrier structure in the same etching environment is greater than or equal to 1000:

1.

4. The thermocouple sensor according to claim 1, characterized in that The thermocouple structure includes a plurality of thermocouples disposed on the top surface of the substrate and connected in series. Each thermocouple is located between two adjacent release channels.

5. The thermocouple sensor according to claim 4, characterized in that, Each thermocouple includes a first thermocouple portion and a second thermocouple portion with different constituent materials and connected to each other. Among two adjacent thermocouples, the first thermocouple portion of one thermocouple is connected to the second thermocouple portion of the other thermocouple.

6. The thermocouple sensor according to claim 5, wherein The thermocouple structure further includes a plurality of conductive interconnect structures. Among two adjacent thermocouples, the first thermocouple portion of one thermocouple and the second thermocouple portion of the other thermocouple are connected to the same conductive interconnect structure.

7. The thermocouple sensor according to claim 5, wherein Each thermocouple further includes a thermocouple connection structure. The top of the thermocouple connection structure overlaps and contacts the first thermocouple portion and the second thermocouple portion respectively, and the bottom of the thermocouple connection structure contacts the first thermocouple portion and the second thermocouple portion respectively to realize the connection of the first thermocouple portion and the second thermocouple portion.

8. The thermocouple sensor according to claim 7, characterized in that, The top of the thermocouple connection structure has the same constituent material as the first thermocouple portion or the second thermocouple portion, and the bottom of the thermocouple connection structure has different constituent materials from the first thermocouple portion and the second thermocouple portion.

9. The thermocouple sensor according to claim 7, characterized in that, The first thermocouple portion, the second thermocouple portion, and the thermocouple connection structure are an integrated structure.

10. The thermocouple sensor according to claim 5, characterized in that, The absolute value of the difference between the Seebeck coefficient of the constituent material of the first thermocouple portion and the Seebeck coefficient of the constituent material of the second thermocouple portion is greater than 1.

11. A method for preparing a thermocouple sensor, which is used to manufacture the thermocouple sensor according to any one of claims 1 to 10, characterized in that, Including the following steps: S1: Provide a substrate, and form a barrier structure that is connected end to end within the substrate. The region surrounded by the bottom of the barrier structure within the substrate is an enclosed structure; S2: Form a thermocouple structure on the top surface of the substrate, such that the thermocouple structure is arranged corresponding to the surrounding structure, and expose a part of the top surface of the substrate; S3: Etch in the direction from the exposed top surface of the substrate towards the bottom surface of the substrate to form a plurality of release channels, and expose a part of the top surface of the surrounding structure; S4: Remove the surrounding structure through the plurality of release channels to form a cavity structure communicating with the plurality of release channels.

12. The method for preparing the thermocouple sensor according to claim 11, wherein, In the step S1, the step of forming a blocking structure that is connected end to end in the substrate includes: S11: Provide a substrate, and deposit and form an initial insulating structure on the top surface of the substrate; S12: Sequentially remove a part of the initial insulating structure and a part of the substrate in the direction from the top surface of the initial insulating structure towards the bottom surface of the substrate, and then fill with a blocking material to form the blocking structure.

13. The method for preparing the thermocouple sensor according to claim 11, wherein, In the step S4, the cavity structure formed by removing the surrounding structure through the plurality of release channels is a top cavity structure. After the step S4 is completed, further remove the part of the structure between the bottom surface of the blocking structure and the bottom surface of the substrate to form a bottom cavity structure communicating with the top cavity structure.

14. The manufacturing method of the thermocouple sensor according to claim 11, characterized in that, In the step S2, the step of forming a thermocouple structure on the top surface of the substrate includes: S21: Use a semiconductor material to form a plurality of initial thermocouples on the top surface of the substrate, and expose the top surface of the substrate located between adjacent initial thermocouples; S22: Perform a doping process to sequentially dope donor impurities into one end of each initial thermocouple, dope acceptor impurities into the other end of each initial thermocouple, and dope either the donor impurities or the acceptor impurities into the middle of each initial thermocouple to form a thermocouple connection structure.

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