Sensing cell array device and method of forming the same

Abstract

The invention relates to a sensing cell array device and a forming method thereof. The sensing unit array device comprises at least two heat insulation cavities formed between a substrate and an insulating layer, at least two gas sensing units which are respectively formed corresponding to the heat insulation cavities and are arranged in an array, and an interconnection structure, the interconnection structure comprises a plurality of metal interconnection lines and a plurality of shared connection pads which are respectively connected with the metal interconnection lines, each metal interconnection line connects the first heating terminals, the second heating terminals, the first test terminals or the second test terminals in the at least two gas sensing units to the corresponding shared connection pads, so that the circuit can be simplified, the number of the connection pads can be reduced, the structure of the sensing unit array device can be optimized, and the manufacturing cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a sensing unit array device and a method for forming a sensor sensing unit array device. Background Art

[0002] Gas sensors can be used in areas such as air quality monitoring, chemical production, and home safety. Currently, commercial gas sensors are mainly ceramic tube and ceramic sheet types, which are large in size and difficult to integrate.

[0003] In recent years, MEMS gas sensors combined with MEMS technology have been widely studied, which have the advantages of small size, low power consumption and easy integration with CMOS circuits.

[0004] MEMS gas sensors are usually provided with multiple gas sensing units, each of which usually includes a heater formed on a heat-insulating cavity, a gas detection electrode and a gas-sensitive material layer. The heating electrode is used to heat the gas-sensitive material layer to an operating temperature, and the gas detection electrode is used to detect the resistance value of the gas-sensitive material layer at the operating temperature. The resistance value of the gas-sensitive material layer is related to the gas substance it contacts, so that a specific gas component can be detected.

[0005] However, the integration technology of existing MEMS gas sensors is still not mature enough. Since the terminals of the heater and gas detection electrode in each gas sensing unit need to be connected to the corresponding connection pads through traces to apply electrical signals to each heater and each gas detection electrode, the leads in the device are complicated, the number of connection pads is large, and the production cost is high. Summary of the invention

[0006] In order to optimize the structure of a MEMS gas sensor and reduce the manufacturing cost, the present invention provides a sensing unit array device and also provides a method for forming the sensing unit array device.

[0007] In one aspect, the present invention provides a sensing unit array device, the sensing unit array device comprising:

[0008] substrate;

[0009] An insulating layer is formed on the substrate, and at least two heat-insulating cavities are formed between the insulating layer and the substrate and surrounded by the substrate and the insulating layer;

[0010] at least two gas sensing units arranged in an array corresponding to each of the insulation cavities, each of the gas sensing units comprising a heater located directly above the corresponding insulation cavity, a gas detection electrode, and a gas sensitive material layer covering the heater and the gas detection electrode, and further comprising a first heating terminal and a second heating terminal located at the periphery of the insulation cavity and connected to the heater, and a first test terminal and a second test terminal connected to the gas detection electrode; and

[0011] An interconnection structure, the interconnection structure comprising a plurality of metal interconnection lines and a plurality of shared connection pads respectively connected to each of the metal interconnection lines, wherein each of the metal interconnection lines connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units to a corresponding shared connection pad.

[0012] Optionally, the gas-sensitive material layers in at least two of the gas sensing units comprise different materials.

[0013] Optionally, the cross-sectional areas or cross-sectional shapes of the insulation cavities corresponding to at least two of the gas sensing units are different.

[0014] Optionally, the sensing unit array device further includes:

[0015] At least one temperature sensor unit and / or at least one humidity sensor unit.

[0016] Optionally, the temperature sensor unit includes a thermal resistor formed on the substrate, wherein the temperature value is acquired by detecting the resistance of the thermal resistor and utilizing the corresponding relationship between the resistance of the thermal resistor and the temperature.

[0017] Optionally, the humidity sensor unit includes a humidity detection electrode formed on the substrate and a humidity sensitive material layer covering the humidity detection electrode, wherein the resistance of the humidity sensitive material layer is detected by the humidity detection electrode, and the humidity value is obtained by utilizing the correspondence between the resistance of the humidity sensitive material layer and the humidity.

[0018] Optionally, the interconnect structure includes at least two metal wiring layers stacked on the substrate and isolated by an insulating material.

[0019] Optionally, the at least two gas sensing units are arranged on the substrate in M ​​rows and N columns, where M and N are positive integers; and the interconnection structure comprises:

[0020] M first heating wires, each of the first heating wires being connected to the first heating terminals in the gas sensing units in the same row;

[0021] M first shared heating pads, respectively connected to the first heating wires;

[0022] N second heating wires, each of the second heating wires being connected to the second heating terminals in the gas sensing units in the same column;

[0023] N second shared heating pads, connected to the second heating wires respectively;

[0024] M first test lines, each of which is connected to the first test terminals in the gas sensing units in the same row;

[0025] M first shared test pads, respectively connected to the first test lines;

[0026] N second test lines, each of which is connected to the second test terminals of the gas sensing units in the same column; and

[0027] N second shared test pads are respectively connected to the second test lines.

[0028] Optionally, the at least two gas sensing units are arranged on the substrate in M ​​rows and N columns, where M and N are positive integers; and the interconnection structure comprises:

[0029] M first heating wires, each of the first heating wires being connected to the first heating terminals in the gas sensing units in the same row;

[0030] M first shared heating pads, respectively connected to the first heating wires;

[0031] M second heating wires, each of the second heating wires being connected to the second heating terminals in the gas sensing units in the same row;

[0032] M second shared heating pads, respectively connected to the second heating lines;

[0033] N first test lines, each of which is connected to the first test terminals in the same column of the gas sensing units;

[0034] N first shared test pads, respectively connected to the first test lines;

[0035] N second test lines, each of which is connected to the second test terminals of the gas sensing units in the same column; and

[0036] N second shared test pads are respectively connected to the second test lines.

[0037] Optionally, the insulating layer has a through hole connecting each of the thermal insulation cavities with the outside of the thermal insulation cavity.

[0038] Optionally, the high temperature resistance of the materials of the heater and the gas detection electrode is stronger than that of the material of the interconnecting metal wire, and the material impedance of the heater and the gas detection electrode is greater than the material impedance of the interconnecting metal wire.

[0039] In another aspect, the present invention provides a method for forming the above-mentioned sensing unit array device, the method comprising:

[0040] forming an insulating layer on a substrate, and forming at least two sacrificial layer structures between the insulating layer and the substrate for defining the range of the thermal insulation cavity;

[0041] At least two gas sensing units are formed on the insulating layer in regions corresponding to the sacrificial layer structures, each of the gas sensing units comprising a heater located directly above the corresponding sacrificial layer structure, a gas detection electrode, and a gas-sensitive material layer covering the heater and the gas detection electrode, and further comprising a first heating terminal and a second heating terminal located at the periphery of the sacrificial layer structure and connected to the heater, and a first test terminal and a second test terminal connected to the gas detection electrode;

[0042] forming an interconnection structure, the interconnection structure comprising a plurality of metal interconnection lines and a plurality of shared connection pads respectively connected to the metal interconnection lines, wherein each of the metal interconnection lines connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units to a corresponding shared connection pad; and

[0043] A release hole is formed to expose the sacrificial layer structure, and the sacrificial layer structure is removed by etching through the release hole, so as to form a heat-insulating cavity in the region of the sacrificial layer structure.

[0044] The sensing unit array device provided by the present invention includes at least two insulation cavities formed between a substrate and an insulating layer, at least two gas sensing units arranged in an array corresponding to each of the insulation cavities, and an interconnection structure, wherein the interconnection structure includes a plurality of metal interconnections and a plurality of shared connection pads respectively connected to each of the metal interconnections, wherein each of the metal interconnections connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units to a corresponding shared connection pad, that is, at least two first heating terminals, at least two second heating terminals, at least two first test terminals or at least two second test terminals are connected through corresponding metal interconnections and connected to a shared connection pad through corresponding metal interconnections, which helps to simplify the circuit, reduce the number of connection pads, optimize the structure of the sensing unit array device, and facilitate reducing the manufacturing cost.

[0045] The above-mentioned sensing unit array device can be obtained by using the method for forming the sensing unit array device provided by the present invention, which is helpful to optimize the structure of the sensing unit array device and reduce the manufacturing cost.

[0046] In addition, in the formation method, at least two sacrificial layer structures for limiting the range of the thermal insulation cavity are first formed between the insulating layer and the substrate. After the gas sensing unit and the interconnection structure are formed, a release hole exposing the sacrificial layer structure is formed, and the sacrificial layer structure is etched away through the release hole to form a thermal insulation cavity in the area of ​​the sacrificial layer structure. The shape and size of the isolation cavity are defined before the gas sensing unit is formed. Compared with the method of etching the material between the substrate and the insulating layer to form the isolation cavity after the gas sensing unit is formed, the manufacturing accuracy of the thermal insulation cavity can be improved, which helps to reduce the size of the gas sensing unit and thus improve the integration density, and reduce the size of the sensing unit array device. Moreover, since the smaller gas sensing unit has a smaller heat capacity, by increasing the integration density of the gas sensing unit, it is beneficial to reduce power consumption and increase the heating rate of the sensing unit array device. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1A and Figure 1B 4 is a cross-sectional schematic diagram of a gas sensing unit formed corresponding to the thermal insulation cavity in the sensing unit array device according to an embodiment of the present invention.

[0048] Figure 2A Schematic diagram of interconnection of multiple gas sensing units arranged in an array according to an embodiment of the present invention.

[0049] Figure 2B yes Figure 2A Detailed schematic diagram of the gas sensing unit area in FIG.

[0050] Figure 3 FIG. 4 is a schematic diagram of interconnection of a plurality of gas sensing units arranged in an array in another embodiment of the present invention.

[0051] Figure 4 FIG. 4 is a flow chart of a method for forming a sensing unit array device according to an embodiment of the present invention.

[0052] FIG. 5A to FIG. 5E FIG. 4 is a cross-sectional schematic diagram of a method for forming a sensing unit array device according to an embodiment of the present invention before forming an interconnection structure.

[0053] FIG. 6A to FIG. 6E FIG. 4 is a cross-sectional schematic diagram of a method for forming a sensing unit array device according to another embodiment of the present invention before forming an interconnection structure. DETAILED DESCRIPTION

[0054] The sensing unit array device and the method for forming the same of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the drawings in the specification are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the structure in the drawing is inverted or positioned in other different ways (such as rotated), the exemplary term "on..." may also include "under..." and other orientation relationships.

[0055] Sensing unit array device

[0056] The sensing unit array device of the embodiment of the present invention includes a substrate, an insulating layer formed on the substrate, a gas sensing unit and an interconnection structure. Figures 1A to 3 The sensing unit array device is described in detail.

[0057] Figure 1A and Figure 1B The partial cross-sectional structure of the sensing unit array device is shown. Figure 1A and Figure 1B The substrate 100 may be a semiconductor substrate, a ceramic substrate, a glass substrate or other suitable substrates. As an example, in this embodiment, the substrate 100 includes a semiconductor substrate 10 and a dielectric layer 101 formed on the surface of the semiconductor substrate 10. The semiconductor substrate 10 may include silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, indium antimonide or other semiconductor materials, and the dielectric layer 101 may include one or a combination of dielectric materials such as silicon oxide, silicon nitride, silicon oxynitride and NDC (Nitrogen doped Silicon Carbide).

[0058] The insulating layer 120 is formed on the substrate 100. The insulating layer 120 is formed, for example, by an oxide deposition process based on tetraethoxysilane (TEOS). Figure 1A and Figure 1B As shown, in the sensing unit array device, there are at least two heat-insulating cavities 100a between the insulating layer 120 and the substrate 100 (only one heat-insulating cavity 100a is shown in the figure). The heat-insulating cavity 100a is surrounded by the substrate 100 and the insulating layer 120. Figure 1A In one embodiment, the dielectric layer 101 forms the side wall and the bottom wall of the heat-insulating cavity 100a, and the insulating layer 120 forms the top wall of the heat-insulating cavity 100a; Figure 1BIn another embodiment, the dielectric layer 101 constitutes the bottom wall of the insulation cavity 100a, and the insulating layer 120 constitutes the side wall and the top wall of the insulation cavity 100a. The distance between the bottom wall and the top wall of the insulation cavity 100a is, for example, less than or equal to 10μm (for example, 0.1μm, 0.5μm, 1μm, 3μm, 4μm, 4.5μm, 5μm, 5.5μm or 10μm). However, the present invention is not limited thereto. For example, in other embodiments, the depth of the insulation cavity 100a is greater than or equal to 10μm and less than or equal to 100μm, for example, it can be 10μm, 15μm or 20μm, etc. The opening shape and size of the insulation cavity 100a can be set as required.

[0059] Optionally, the insulating layer 120 has through holes 20 respectively connecting each of the insulation cavities 110a with the outside of the insulation cavity 110a. The through holes 20 can be used as release holes for removing the sacrificial layer structure occupying the insulation cavity 110a when manufacturing the sensing unit array device.

[0060] In the sensing unit array device, at least two gas sensing units SU are respectively arranged corresponding to each of the thermal insulation cavities 100a, and the at least two gas sensing units SU are arranged in an array in a two-dimensional plane parallel to the upper surface of the substrate 100. Optionally, the cross-sectional areas or cross-sectional shapes of the thermal insulation cavities 100a corresponding to at least two of the gas sensing units SU are different.

[0061] Reference Figure 1A and Figure 1B as well as Figure 2B Each of the gas sensing units SU includes a heater E1 located directly above the corresponding insulation cavity 100a, a gas detection electrode E2, and a gas-sensitive material layer 130 covering the heater E1 and the gas detection electrode E2 (here, "covering" may include various covering methods such as contact-type direct covering and non-contact-type indirect covering), and also includes a first heating terminal 120a and a second heating terminal 120a' located outside the insulation cavity 100a and connected to the heater E1 (refer to Figure 2B ) and a first test terminal 120b and a second test terminal 120b′ (see Figure 2B The first heating terminal 120a and the second heating terminal 120a' are used to apply an electrical signal to the heater E1, and the first test terminal 120b and the second test terminal 120b' are used to apply an electrical signal to the gas detection electrode E2. The heat-insulating cavity 100a has a cantilever beam 21 located around the through hole 20 (see Figure 2B), the connection lines between the first heating terminal 120a and the second heating terminal 120a′ and the heater E1 pass through the corresponding cantilever beam 21, and the connection lines between the first test terminal 120b and the second test terminal 120b′ and the gas detection electrode E2 pass through the corresponding cantilever beam 21.

[0062] like Figure 1A As shown, in some embodiments, the insulating layer 120 may include a first insulating layer 121 formed on the substrate 100 and a second insulating layer 122 formed on the first insulating layer 121, the heater E1, the first heating terminal 120a and the second heating terminal 120a' are formed on the surface of the first insulating layer 121, and the gas detection electrode E2, the first test terminal 120b and the second test terminal 120b' are formed on the surface of the second insulating layer 122. Optionally, the first heating terminal 120a and the second heating terminal 120a' may be exposed through a through hole in the second insulating layer 122, and the contact layer 120c may cover the inner surface of the through hole (so as to connect the first heating terminal 120 or the second heating terminal 120a' exposed by the corresponding through hole) and part of the surface of the second insulating layer 122 outside the through hole. When manufacturing the gas detection electrode E2, the first test terminal 120b and the second test terminal 120b', a metal material is formed along the surface of the second insulating layer 122 and the inner surface of the through hole, and the metal material is patterned to form the gas detection electrode E2, the first test terminal 120b, the second test terminal 120b' and the contact layer 120c.

[0063] In some embodiments, the heater E1 and the gas detection electrode E2 may also be formed by the same metal layer and thus be located at the same height plane on the insulating layer 120. Specifically, Figure 1B As shown, the insulating layer 120 is formed on the substrate 100 , and the heater E1 , the gas detection electrode E2 , the first heating terminal 120 a , the second heating terminal 120 b , the first test terminal 120 b and the second test terminal are all formed on the surface of the insulating layer 120 .

[0064] The heater E1, the gas detection electrode E2, the first heating terminal 120a, the second heating terminal, the first test terminal 120b and the second test terminal all include a high-temperature metal layer formed of a high-temperature resistant metal, which can be used when the ambient temperature of the area is high and can meet the temperature resistance requirements of the heater E1 and the gas detection electrode E2. The high-temperature metal layer includes, for example, at least one of Au, Pt, and Cr.

[0065] The gas-sensitive material layer 130 may include one or a combination of gas-sensitive materials such as SnO2, V2O5, WO3, ZnO, TeO2, TiO2, CuO, CeO2, Al2O3, ZrO2, V2O3, Fe2O3, Mo2O3, Nd2O3, La2O3, Nb2O5, Ta2O5, In2O3, GeO2 and ITO. Optionally, the gas-sensitive material layer 130 in at least two of the gas sensing units SU contains different materials to detect gases of different components.

[0066] The interconnection structure may be formed on one side of the insulating layer 120 or on the side of the substrate 100 away from the insulating layer 120, and the interconnection structure includes a plurality of metal interconnections and a plurality of shared connection pads respectively connected to each of the metal interconnections, wherein each of the metal interconnections connects the first heating terminal 120a, the second heating terminal, the first test terminal 120b or the second test terminal in at least two of the gas sensing units SU to the corresponding shared connection pad. The metal interconnection may be isolated from the heater E1, the gas detection electrode E2, the first heating terminal 120a, the second heating terminal, the first test terminal 120b and the second test terminal by a dielectric material, and the metal interconnection may be electrically connected to the first heating terminal 120a, the second heating terminal, the first test terminal 120b or the second test terminal to be connected by a contact plug formed in the dielectric material.

[0067] Figure 2A A schematic diagram of connecting a plurality of gas sensing units using the above interconnection structure in one embodiment is shown. Figure 2B yes Figure 2A Detailed schematic diagram of the gas sensing unit SU area in FIG. Figure 2A and Figure 2B Each metal interconnection line in the interconnection structure is connected to the first heating terminal 120a, the second heating terminal 120a', the first test terminal 120b or the second test terminal 120b' in the gas sensing unit SU. Since high-temperature metals such as Au, Pt and Cr are expensive and have large resistance (increasing thickness will increase the difficulty of patterning), the metal interconnection line can be made of a low-impedance material with lower impedance than the material of the heater E1 and the gas detection electrode E2 to reduce the resistance of the interconnection structure. The metal interconnection line, for example, is made of a non-high-temperature metal material, and the non-high-temperature metal material, for example, includes at least one of Al, W, Ni, Fe, Cu, Ti, TiN, Ta and TaN.

[0068] Reference Figure 2A In one embodiment, at least two gas sensing units SU formed on the substrate 100 are arranged in M ​​rows and N columns on the substrate 100, where M and N are positive integers ( Figure 2A In the example shown, M=N=3). The plurality of metal interconnects in the interconnect structure include M first heating lines L1, N second heating lines L2, M first test lines L3, and N second test lines L4, and the plurality of shared connection pads in the interconnect structure include M first shared heating pads P1 respectively connected to each of the first heating lines L1, N second shared heating pads P2 respectively connected to each of the second heating lines L2, M first shared test pads P3 respectively connected to each of the first test lines L3, and N second shared test pads P4 respectively connected to each of the second test lines L4, wherein each of the first heating lines L1 is connected to the same row of the gas sensing lines. All the first heating terminals 120a in the unit SU are connected to the corresponding first shared heating pad P1, each of the second heating lines L2 is connected to all the second heating terminals 120a' in the gas sensing units SU in the same column and is connected to the corresponding second shared heating pad P2, each of the first test lines L3 is connected to all the first test terminals 120b in the gas sensing units SU in the same row and is connected to the corresponding first shared test pad P3, and each of the second test lines L4 is connected to all the second test terminals 120b' in the gas sensing units SU in the same column and is connected to the corresponding second shared test pad P4.

[0069] In order to conveniently accommodate the metal interconnection lines and shared connection pads in the interconnection structure and avoid the metal interconnection lines in different extension directions from overlapping and short-circuiting, the interconnection structure may include at least two metal wiring layers stacked on the substrate 100 and isolated by insulating materials, and the multiple metal interconnection lines in the interconnection structure are arranged in the at least two metal wiring layers. Specifically, the two metal interconnection lines whose extension paths intersect can be respectively set in two metal wiring layers; or, one of the two metal interconnection lines whose extension paths intersect can be set in a metal wiring layer (referred to as metal wiring layer M1), and a part of the other metal interconnection line is also set in the metal wiring layer M1, and the other metal interconnection line is extended to another metal wiring layer (referred to as metal wiring layer M2) in the intersection area using the conductive hole between the metal wiring layers, and after passing through the intersection area, it can be extended back to the metal wiring layer M1 using another conductive hole between the metal wiring layers. Both of the above methods can avoid overlapping and short-circuiting of metal interconnection lines, and the circuit occupies a small area.

[0070] As an example, the M first heating lines L1 and the M first test lines L3 are located in the same metal wiring layer, and the N second heating lines L2 and the N second test lines L4 are located in another metal wiring layer. Figure 2AAs shown, the M first heating lines L1 and the M first test lines L3 extend, for example, along the row direction of the gas sensing unit array, and the N second heating lines L2 and the N second test lines L4 extend, for example, along the column direction of the gas sensing unit array, so that the metal interconnection lines in the same direction can be arranged in the same metal wiring layer.

[0071] But not limited to this, the interconnect structure may include more than two layers of the metal wiring layer. For example, in another embodiment, the interconnect structure includes three layers of the metal wiring layer, wherein the M first heating lines L1 and the M first test lines L3 are located in the same metal wiring layer, and the N second heating lines L2 and the N second test lines L4 are respectively located in the other two metal wiring layers; or, the M first heating lines L1 and the M first test lines L3 are respectively located in two metal wiring layers, and the N second heating lines L2 and the N second test lines L4 are located in another metal wiring layer. In another embodiment, the interconnect structure includes four layers of the metal wiring layer, wherein the first heating line L1, the second heating line L2, the first test line L3 and the second test line L4 are respectively located in different metal wiring layers.

[0072] In the interconnect structure, the arrangement of metal interconnect lines is not limited to Figure 2A As an example, Figure 3 As shown, in another embodiment, the at least two gas sensing units are arranged on the substrate in M ​​rows and N columns, where M and N are positive integers ( Figure 3In the example shown, M=N=3); the plurality of metal interconnects in the interconnect structure include M first heating lines L1', M second heating lines L2', N first test lines L3' and N second test lines L4', and the plurality of shared connection pads in the interconnect structure include M first shared heating pads P1' respectively connected to each of the first heating lines L1', M second shared heating pads P2' respectively connected to each of the second heating lines L2', N first shared test pads P3' respectively connected to each of the first test lines L3' and N second shared test pads P4' respectively connected to each of the second test lines L4', wherein each of the first heating lines L1' is connected to All the first heating terminals 120a in the same row of the gas sensing units SU are connected to the corresponding first shared heating pad P1', each of the second heating lines L2' is connected to all the second heating terminals 120a' in the same row of the gas sensing units SU and is connected to the corresponding second shared heating pad P2', each of the first test lines L3' is connected to all the first test terminals 120b in the same column of the gas sensing units SU and is connected to the corresponding first shared test pad P3', each of the second test lines L4' is connected to all the second test terminals 120b' in the same column of the gas sensing units SU and is connected to the corresponding second shared test pad P4'. The M first heating lines L1', the M second heating lines L2', the N first test lines L3' and the N second test lines L4' can be dispersedly arranged in at least two layers of the metal wiring layer.

[0073] In some embodiments, the sensing unit array device may further include at least one temperature sensor unit and / or at least one humidity sensor unit. The temperature sensor unit and the humidity sensor unit are used to detect temperature and humidity, respectively. Integrating the temperature sensor unit and the humidity sensor unit with the above-mentioned gas sensing unit in the sensing unit array device can improve the performance of the sensing unit array device.

[0074] As an example, the temperature sensor unit includes a thermal resistor formed on the substrate 100 (e.g., the surface of the insulating layer 120), and the resistance of the thermal resistor has a linear relationship with the temperature. By detecting the resistance of the thermal resistor and using the corresponding relationship between the resistance of the thermal resistor and the temperature, the temperature value can be obtained. Optionally, the thermal resistor can be made of a material (such as platinum (Pt)) used to make the heater E1. The interconnection structure can also include a metal interconnection line connected to the thermal resistor in the temperature sensor unit and a corresponding connection pad. The temperature sensor unit can be set in an area outside the gas sensing unit array, and the temperature sensor unit can be made at the same time when the gas sensing unit array is made. The present invention is not limited to this, and the specified gas sensing unit can also be reused as the temperature sensor unit. When the specified gas sensing unit is used to measure the temperature, the heater E1 is used as the thermal resistor, and the temperature value of the heater E1 is measured by detecting the resistance of the heater E1 and using the corresponding relationship between the resistance of the heater E1 and the temperature.

[0075] In some embodiments, the humidity sensor unit includes a humidity detection electrode formed on the substrate 100 (e.g., the surface of the insulating layer 120) and a humidity sensitive material layer covering the humidity detection electrode, wherein the resistance of the humidity sensitive material layer is detected by the humidity detection electrode, and the humidity value is obtained by using the corresponding relationship between the resistance of the humidity sensitive material layer and the humidity. Optionally, the humidity sensitive material layer and the gas sensitive material layer 130 in at least one of the gas sensing units SU include the same metal oxide, such as zinc oxide, tin oxide, or indium oxide.

[0076] The humidity sensor unit may be arranged in an area outside the gas sensing unit array, and the humidity sensor unit may be manufactured at the same time when the gas sensing unit array is manufactured. A heat-insulating cavity may or may not be formed under the humidity detection electrode of the humidity sensor unit, and a heater and a heating terminal may not be formed at the position of the humidity sensor unit. In some cases, the designated gas sensing unit may also be reused as a humidity sensor unit. When the designated gas sensing unit is used to measure humidity, the heater E1 is not started for heating, that is, the gas-sensitive material layer is kept below the gas-sensitive operating temperature, and the humidity-sensitive function of the gas-sensitive material layer is used to detect the resistance of the gas-sensitive material layer, and the corresponding relationship between the resistance of the gas-sensitive material layer that has not reached the gas-sensitive operating temperature range and the humidity is used to obtain the humidity value.

[0077] The sensing unit array device described in the above embodiment includes at least two insulation cavities 100a formed between a substrate 100 and an insulating layer 120, at least two gas sensing units SU arranged in an array respectively formed corresponding to each of the insulation cavities 100a, and an interconnection structure, wherein the interconnection structure includes a plurality of metal interconnections and a plurality of shared connection pads respectively connected to each of the metal interconnections, wherein each of the metal interconnections connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units SU to a corresponding shared connection pad, that is, at least two first heating terminals, at least two second heating terminals, at least two first test terminals or at least two second test terminals are connected through corresponding metal interconnections and connected to a shared connection pad through the metal interconnections, which helps to simplify the circuit and reduce the number of connection pads, thereby optimizing the structure of the sensing unit array device and facilitating reducing the manufacturing cost.

[0078] Method for forming a sensing unit array device

[0079] An embodiment of the present invention further relates to a method for forming a sensing unit array device, and the method can be used to manufacture the sensing unit array device in the above embodiment.

[0080] Reference Figures 1A to 4 In an embodiment of the present invention, a method for forming a sensing unit array device includes the following process.

[0081] First, step S1 is performed to form an insulating layer 120 on the substrate 100, and at least two sacrificial layer structures for defining the scope of the above-mentioned thermal insulation cavity 100a are formed between the insulating layer 120 and the substrate 100. As an example, a groove of the size of the thermal insulation cavity 100a may be formed in the substrate 100, and a sacrificial material may be filled in the groove to form a sacrificial layer structure, and then the insulating layer 120 is formed on the substrate 100 and the sacrificial layer structure. In another example, the substrate 100 may not be etched, but a sacrificial layer may be deposited on the surface of the substrate 100, and the sacrificial layer may be etched so that the remaining sacrificial layer forms a plurality of structures of the size of the thermal insulation cavity 100a, and then the insulating layer 120 is covered on the patterned sacrificial layer structure and the substrate 100.

[0082] Next, step S2 is performed to form at least two gas sensing units SU on the insulating layer 120 in areas corresponding to each of the sacrificial layer structures, each of the gas sensing units SU including a heater E1 located directly above the corresponding sacrificial layer structure, a gas detection electrode E2, and a gas-sensitive material layer 130 covering the heater E1 and the gas detection electrode E2, the gas sensing unit SU also including a first heating terminal 120a and a second heating terminal 120a' located on the periphery of the sacrificial layer structure and connected to the heater E1, and a first test terminal 120b and a second test terminal 120b' located on the periphery of the sacrificial layer structure and connected to the gas detection electrode E2.

[0083] Then, step S3 is performed to form an interconnection structure, which includes a plurality of metal interconnections and a plurality of shared connection pads respectively connected to the metal interconnections, wherein each of the metal interconnections connects the first heating terminal, the second heating terminal, the first test terminal or the second test terminal in at least two of the gas sensing units to the corresponding shared connection pad.

[0084] Afterwards, step S4 is performed to form a release hole exposing the sacrificial layer structure, and the sacrificial layer structure is removed by etching through the release hole, thereby forming a heat-insulating cavity 100 a in the region of the sacrificial layer structure.

[0085] The interconnection structure may be formed on one side of the insulating layer 120 or on the side of the substrate 100 away from the insulating layer 120. Before forming the interconnection structure, a dielectric material may be covered on the insulating layer 120 and the gas sensing unit SU for protection.

[0086] In one embodiment, after the interconnect structure is formed, the dielectric material on the insulating layer 120 and the insulating layer 120 are etched to form the release hole, but it is not limited thereto. After the gas sensing unit SU is formed, the insulating layer 120 is first etched to form a through hole exposing the sacrificial layer structure, but the sacrificial layer structure is not removed at this time. Instead, the interconnect structure is then manufactured. After the interconnect structure is manufactured, the dielectric material on the insulating layer 120 is etched corresponding to the position of the through hole to form a release hole exposing the sacrificial layer structure, and the sacrificial layer structure is etched away through the release hole.

[0087] FIG. 5A to FIG. 5E FIG. 1 is a cross-sectional schematic diagram of a method for forming a sensing unit array device according to an embodiment of the present invention before forming an interconnection structure. FIG. 5A to FIG. 5E In one embodiment, a method for forming a sensing unit array device includes the following steps:

[0088] like Figure 5AAs shown, a substrate 100 is provided. As an example, in this embodiment, the substrate 100 includes a semiconductor substrate 10 and a dielectric layer 101 formed on the surface of the semiconductor substrate 10. The dielectric layer 101 formed on the surface of the semiconductor substrate 10 can be used to construct a heat-insulating cavity, so that the semiconductor substrate 10 does not need to be etched, and the problems of being restricted by crystal orientation and substrate thickness when etching the semiconductor substrate 10 can be avoided;

[0089] like Figure 5B As shown, at least two cavities 100a are formed in the substrate 100 (the cavities are subsequently used as the above-mentioned insulation cavities 100a, and therefore the same reference numerals are used). In this embodiment, the cavities 100a are formed by etching the dielectric layer 101 in the substrate 100. For example, the cavities 100a are formed by etching the dielectric layer 101 using an anisotropic dry etching process. The etching direction is, for example, perpendicular to the top surface of the substrate 100. This can effectively control the amount of lateral etching, which helps to accurately control the width of the cavity 100a and the dihedral angle between the side wall and the bottom wall of the cavity, and reduce the influence of the etching depth and etching time on the area of ​​the substrate 100 occupied by the cavity 100a. The longitudinal section of the cavity 100a is, for example, a rectangle or an inverted trapezoid, and the dihedral angle between the side wall and the bottom wall of the cavity 100a is, for example, greater than or equal to 90 degrees and less than or equal to 120 degrees;

[0090] like Figure 5C As shown, a sacrificial material is deposited in the cavity 100a to form a sacrificial layer structure 110. The sacrificial layer structure 110 preferably has a good etching selectivity with the dielectric layer 101 and the insulating layer 120, so that the shape and size of the cavity 100a are not substantially affected when the sacrificial layer structure 110 is subsequently removed. As an example, the sacrificial material is amorphous silicon;

[0091] like Figure 5D As shown, an insulating layer 120 is formed, and at least two gas sensing units SU are formed on the insulating layer 120 corresponding to the regions of each sacrificial layer structure (the composition of the gas sensing unit SU can refer to the above content);

[0092] like Figure 5E As shown, a plurality of through holes 20 penetrating the insulating layer 120 are formed, and the through holes 20 expose the sacrificial layer structure 110 in each cavity 100a to the outside. The through holes 20 can be formed by dry or wet etching the insulating layer 120. In another embodiment, the plurality of through holes 20 penetrating the insulating layer 120 can be made after forming the interconnect structure.

[0093] exist Figure 5EOn the basis of the above, the interconnection structure can be further formed on the front side (i.e., the side where the gas sensing unit SU is formed) or the back side of the substrate 100 by using a known metal wiring process. After the metal wiring process is completed, a release hole is formed corresponding to the through hole 20 to expose the sacrificial layer structure 110, and the sacrificial layer structure 110 is removed by etching through the release hole, and a heat insulation cavity 100a is formed in the area of ​​the sacrificial layer structure 110, as shown in FIG. Figure 1A shown.

[0094] FIG. 6A to FIG. 6E FIG. 1 is a cross-sectional schematic diagram of a method for forming a sensing unit array device according to an embodiment of the present invention before forming an interconnection structure. FIG. 6A to FIG. 6E In another embodiment, a method for forming a sensing unit array device includes the following steps:

[0095] like Fig. 6A As shown, a substrate 100 is provided, and a sacrificial material layer 140 is formed on the substrate 100. The substrate 100 includes a semiconductor substrate 10 and a dielectric layer 101 formed on the surface of the semiconductor substrate 10. The sacrificial material layer 140 preferably has a better etching selectivity with the dielectric layer 101 and the insulating layer 120, so that the shape and size of the heat insulation cavity to be manufactured are not substantially affected during the subsequent etching and removal of the sacrificial material layer 140. As an example, the sacrificial material layer 140 is, for example, amorphous silicon, which can be formed on the surface of the substrate 100 by an epitaxial process;

[0096] like Figure 6B As shown, the sacrificial material layer 140 is etched to form an isolation trench 30 exposing the surface of the substrate 100 and at least one sacrificial layer structure 110 surrounded by the isolation trench 30. The sacrificial layer structure 110 can be set according to the shape and size of the isolation cavity to be manufactured;

[0097] like Figure 6C As shown, an insulating layer 120 is first formed on the substrate 100, and the insulating layer 120 fills the isolation trench 30 and covers each sacrificial layer structure 110. Optionally, the insulating layer 120 is formed by an oxide deposition process based on tetraethoxysilane (TEOS), wherein the leveling property of tetraethoxysilane (TEOS) liquid is utilized to form the upper surface flatness of the formed insulating layer 120; then, a metal layer is deposited on the insulating layer 120 and the metal layer is etched to form a heater E1, a first heating terminal 120, a second heating terminal 120a', a test electrode E2, a first test terminal 120b and a second test terminal 120b';

[0098] like Fig.6DAs shown, a gas-sensitive material layer 130 is formed on the portion of the insulating layer 120 located above the sacrificial layer structure 110 , and the gas-sensitive material layer 130 covers the heater E1 and the test electrode E2 , thereby forming the gas sensing unit SU;

[0099] like Fig. 6E As shown, a plurality of through holes 20 are formed through the insulating layer 120, and the through holes 20 expose the sacrificial layer structures 110. In another embodiment, the plurality of through holes 20 that penetrate the insulating layer 120 can be fabricated after the interconnection structure is formed.

[0100] exist Fig. 6E On the basis of the above, the interconnection structure can be further formed on the front side (i.e., the side where the gas sensing unit SU is formed) or the back side of the substrate 100 by using a known metal wiring process. After the metal wiring process is completed, a release hole is formed corresponding to the through hole 20 to expose the sacrificial layer structure 110, and the sacrificial layer structure 110 is removed by etching through the release hole, and a heat insulation cavity 100a is formed in the area of ​​the sacrificial layer structure 110, as shown in FIG. Figure 1B shown.

[0101] The sensing unit array device described above can be obtained by using the method for forming the sensing unit array device described above, which is helpful to optimize the structure of the MEMS gas sensor and facilitate reducing the manufacturing cost.

[0102] In addition, in the formation method, at least two sacrificial layer structures for limiting the range of the thermal insulation cavity 100a are first formed between the substrate 100 and the insulating layer 120. After the gas sensing unit SU is formed, the sacrificial layer structure is removed by using the release hole to form the isolation cavity 100a. That is, the shape and size of the isolation cavity 100a are defined before the gas sensing unit SU is formed. Compared with the method of etching the material between the substrate 100 and the insulating layer 120 to form the isolation cavity 100a after the gas sensing unit is formed, the manufacturing accuracy of the thermal insulation cavity 100a can be improved, which helps to reduce the size of the gas sensing unit SU and thus improve the integration density, and reduce the size of the sensing unit array device. Moreover, since the smaller gas sensing unit SU has a smaller heat capacity, by increasing the integration density of the gas sensing unit SU, it is beneficial to reduce power consumption and increase the heating rate of the sensing unit array device.

[0103] It should be noted that the embodiments in this specification are described in a progressive manner, and the forming method of the sensing unit array device in the embodiments corresponds to the sensing unit array device, and the relevant parts can be understood by reference.

[0104] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A sensing unit array device, characterized in that: include: substrate; An insulating layer is formed on the substrate, and at least two heat-insulating cavities are formed between the insulating layer and the substrate and surrounded by the substrate and the insulating layer; at least two gas sensing units arranged in an array corresponding to each of the thermal insulation cavities, each of the gas sensing units comprising a heater located directly above the corresponding thermal insulation cavity, a gas detection electrode, and a gas sensitive material layer covering the heater and the gas detection electrode, and further comprising a first heating terminal and a second heating terminal located at the periphery of the thermal insulation cavity and connected to the heater, and a first test terminal and a second test terminal connected to the gas detection electrode; as well as An interconnection structure, the interconnection structure comprising a plurality of metal interconnection lines and a plurality of shared connection pads respectively connected to each of the metal interconnection lines, wherein each of the metal interconnection lines connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units to a corresponding shared connection pad.

2. The sensing unit array device according to claim 1, wherein: The gas-sensitive material layers in at least two of the gas sensing units include different materials.

3. The sensing unit array device according to claim 1, wherein: The cross-sectional areas or cross-sectional shapes of the thermal insulation cavities corresponding to at least two of the gas sensing units are different.

4. The sensing unit array device according to claim 1, wherein: Also includes: At least one temperature sensor unit and / or at least one humidity sensor unit.

5. The sensing unit array device according to claim 4, characterized in that: The temperature sensor unit includes a thermal resistor formed on the substrate, wherein the temperature value is acquired by detecting the resistance of the thermal resistor and using the corresponding relationship between the resistance of the thermal resistor and the temperature.

6. The sensing unit array device according to claim 4, characterized in that: The humidity sensor unit includes a humidity detection electrode formed on the substrate and a humidity sensitive material layer covering the humidity detection electrode, wherein the resistance of the humidity sensitive material layer is detected by the humidity detection electrode, and the humidity value is obtained by using the corresponding relationship between the resistance of the humidity sensitive material layer and the humidity.

7. The sensing unit array device according to claim 1, wherein: The interconnect structure includes at least two metal wiring layers stacked on the substrate and separated by insulating material.

8. The sensing unit array device according to claim 1, wherein: The at least two gas sensing units are arranged on the substrate in M ​​rows and N columns, where M and N are positive integers; the interconnection structure comprises: M first heating wires, each of the first heating wires being connected to the first heating terminals in the gas sensing units in the same row; M first shared heating pads, respectively connected to the first heating wires; N second heating wires, each of the second heating wires being connected to the second heating terminals in the gas sensing units in the same column; N second shared heating pads, connected to the second heating wires respectively; M first test lines, each of which is connected to the first test terminals in the gas sensing units in the same row; M first shared test pads, respectively connected to the first test lines; N second test lines, each of which is connected to the second test terminals of the gas sensing units in the same column; and N second shared test pads are respectively connected to the second test lines.

9. The sensing unit array device according to claim 1, wherein: The at least two gas sensing units are arranged on the substrate in M ​​rows and N columns, where M and N are positive integers; the interconnection structure comprises: M first heating wires, each of the first heating wires being connected to the first heating terminals in the gas sensing units in the same row; M first shared heating pads, respectively connected to the first heating wires; M second heating wires, each of the second heating wires being connected to the second heating terminals in the gas sensing units in the same row; M second shared heating pads, respectively connected to the second heating lines; N first test lines, each of which is connected to the first test terminals in the same column of the gas sensing units; N first shared test pads, respectively connected to the first test lines; N second test lines, each of which is connected to the second test terminals of the gas sensing units in the same column; and N second shared test pads are respectively connected to the second test lines.

10. The sensing unit array device according to claim 1, wherein: The insulating layer has a through hole connecting each of the heat insulation cavities with the outside of the heat insulation cavity.

11. The sensing unit array device according to claim 1, wherein: The high temperature resistance of the heater and the gas detection electrode is stronger than that of the interconnection metal line, and the material impedance of the heater and the gas detection electrode is greater than the material impedance of the interconnection metal line.

12. A method for forming a sensing unit array device according to any one of claims 1 to 11, characterized in that: The forming method comprises: forming an insulating layer on a substrate, and forming at least two sacrificial layer structures between the insulating layer and the substrate for defining the range of the thermal insulation cavity; At least two gas sensing units are formed on the insulating layer in regions corresponding to the sacrificial layer structures, each of the gas sensing units comprising a heater located directly above the corresponding sacrificial layer structure, a gas detection electrode, and a gas-sensitive material layer covering the heater and the gas detection electrode, and further comprising a first heating terminal and a second heating terminal located at the periphery of the sacrificial layer structure and connected to the heater, and a first test terminal and a second test terminal connected to the gas detection electrode; forming an interconnection structure, the interconnection structure comprising a plurality of metal interconnection lines and a plurality of shared connection pads respectively connected to the metal interconnection lines, wherein each of the metal interconnection lines connects a first heating terminal, a second heating terminal, a first test terminal or a second test terminal in at least two of the gas sensing units to a corresponding shared connection pad; and A release hole is formed to expose the sacrificial layer structure, and the sacrificial layer structure is removed by etching through the release hole, so as to form a heat-insulating cavity in the region of the sacrificial layer structure.

Images