Semiconductor gas sensor based on ceramic via vertical interconnect and method of making same

Abstract

The application provides a semiconductor gas sensor based on ceramic via vertical interconnection and a preparation method thereof, which comprises the following steps: preparing a via on a ceramic substrate, grooving the ceramic substrate according to the size of a gas sensitive element; preparing a conductive metal column in the via by adopting a screen printing technology, the conductive metal column penetrating through a first surface and a second surface of the ceramic substrate; respectively preparing a sensing electrode, a heating electrode and an insulating layer on the first surface of the ceramic substrate; respectively preparing a sensing electrode pad and a heating electrode pad on the second surface of the ceramic substrate opposite to the first surface; preparing a gas sensitive layer on the sensing electrode; splitting the ceramic substrate with the prepared gas sensitive layer into single gas sensitive elements along the groove by using a splitter; and fixing the sensing electrode pad and the heating electrode pad on the gas sensitive element to a base pad by using organic gold paste or thick film silver paste and sintering and bonding, so as to reduce the volume of the sensor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a semiconductor gas sensor based on vertical interconnection of ceramic vias and its fabrication method. Background Technology

[0002] Since their introduction, semiconductor gas sensors have been widely used in environmental monitoring, industrial safety, medical diagnostics and other fields due to their advantages such as high sensitivity, fast response speed and low cost.

[0003] If semiconductor gas sensors are classified according to the structure of their gas-sensitive elements, they can be divided into ceramic tube type semiconductor gas sensors, MEMS (Micro-Electro-Mechanical System) type semiconductor gas sensors, and planar type semiconductor gas sensors.

[0004] Among them, ceramic tube-type semiconductor gas sensors use plastic or metal encapsulation for their probes, resulting in large size and correspondingly high power consumption. While MEMS-type semiconductor gas sensors have small probes and low power consumption, their gas-sensitive layers are fabricated using a dispensing method, which leads to poor consistency and consequently, lower accuracy. Planar semiconductor gas sensors typically use TO-5 packaging technology, but this still results in excessively large probes with low heat dissipation efficiency. Furthermore, the TO-5 packaging process, involving wire bonding and red adhesive application, requires sufficient clearance on the substrate, making it difficult to accommodate miniaturized sensing elements. To address these issues, it is necessary to provide a semiconductor gas sensor with a miniaturized physical structure and a wire-bonded packaging method, along with its fabrication method. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a semiconductor gas sensor based on vertical interconnection of ceramic through-holes and its fabrication method, thereby solving the technical problem of miniaturization of semiconductor gas sensors.

[0006] In a first aspect, this application provides a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, comprising: Through holes are prepared on a ceramic substrate, and grooves are cut into the ceramic substrate according to the size of the gas-sensitive element; A conductive metal pillar is fabricated in the through-hole using screen printing technology, and the conductive metal pillar extends to the first and second surfaces of the ceramic substrate. On the first surface of the ceramic substrate, a sensing electrode, a heating electrode, and an insulating layer are fabricated using screen printing technology. On the second surface of the ceramic substrate opposite to the first surface, sensing electrode pads and heating electrode pads are respectively prepared by screen printing technology; a gas-sensitive layer is prepared on the sensing electrode by screen printing technology. The ceramic substrate with the prepared gas-sensitive layer is split into individual gas-sensitive elements by a splitting machine along the groove; By using a sintering and die bonding process, the sensing electrode pads and heating electrode pads on the gas-sensitive element are fixed to the base pads and sintered together using organic gold paste or thick film silver paste.

[0007] In one embodiment, the preparation method further includes: A gas-sensitive cap is welded to the top of the first side of the ceramic substrate using laser welding, wherein the gas-sensitive cap has vent holes.

[0008] In one embodiment, a through-hole is fabricated on a ceramic substrate, including: four through-holes fabricated on the ceramic substrate; The conductive metal pillars are prepared in the through holes by: injecting electrode paste into the four through holes through a hole pattern on a steel mesh using screen printing technology, and sintering the four conductive metal pillars at a sintering temperature of 850-1000℃ after leveling the four through holes.

[0009] In one embodiment, screen printing technology is used to fabricate the sensing electrode, the heating electrode, and the insulating layer, including: The sensing electrode paste is printed onto the first side of the ceramic substrate using screen printing and then sintered at high temperature, so that the first ends of the first conductive metal pillars of the four conductive metal pillars are electrically connected to the sensing electrode. The heating electrode paste is printed onto the first side of the ceramic substrate using screen printing and then sintered at high temperature, so that the first ends of two of the four conductive metal pillars are electrically connected to the heating electrode. The insulating layer dielectric paste is printed onto the heating electrode using screen printing technology, and then sintered to form the insulating layer.

[0010] In one embodiment, the method further includes: The gas-sensitive element is placed in an open cuboid base, on which four base pads are prepared, and the four base pads pass through the cuboid base. The process of fixing and sintering the sensing electrode pads and heating electrode pads on the gas-sensitive element to the base pads using organic gold paste or thick-film silver paste includes: Using organic gold paste or thick film silver paste, the sensing electrode pads and the heating electrode pads are fixed one-to-one with the four base pads and sintered together. The sintering temperature is 300-600℃. There are two sensing electrode pads and two heating electrode pads.

[0011] Secondly, this application provides a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, comprising: A ceramic substrate having through holes, grooves, heating electrodes, and sensing electrodes, wherein the through holes contain conductive metal pillars, and the grooves are formed according to the size of the gas-sensitive element; The first end of the conductive metal pillar extends from the first surface of the ceramic substrate and is electrically connected to the sensing electrode and the heating electrode. The second end of the conductive metal pillar extends from the second surface of the ceramic substrate and is sintered and bonded to the sensing electrode pad and the heating electrode pad.

[0012] In one embodiment, an insulating layer is formed above the heating electrode.

[0013] In one embodiment, a gas-sensitive layer is formed above the sensing electrode, wherein the ceramic substrate on which the gas-sensitive layer is located is cleaved along the groove by a cleaving machine to prepare a single gas-sensitive element, and the conductive metal pillar, the heating electrode, the sensing electrode, the sensing electrode pad and the heating electrode pad are sintered and bonded by gold paste or platinum paste.

[0014] In one embodiment, the semiconductor gas sensor further includes an open cuboid base; The gas-sensitive element is placed in an open cuboid base. Four base pads are prepared on the cuboid base. The four base pads pass through the cuboid base. The sensing electrode pad and the heating electrode pad are respectively fixed to the four base pads one by one by organic gold paste or thick film silver paste and sintered and bonded.

[0015] In one embodiment, the semiconductor gas sensor further includes: A gas-sensitive cap is welded to the top of the first side of the ceramic substrate, wherein the gas-sensitive cap has vent holes.

[0016] This application provides a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes. Through-holes are fabricated on a ceramic substrate, and conductive metal pillars penetrating the ceramic substrate are fabricated within these through-holes. Sensing electrodes, heating electrodes, an insulating layer, and a gas-sensitive layer are fabricated on a first surface of the ceramic substrate using screen printing technology. Sensing electrode pads and heating electrode pads are fabricated on a second surface of the ceramic substrate. The conductive metal pillars penetrating the through-holes are electrically connected to the heating and sensing electrodes, achieving vertical interconnection between the pads and electrodes. Finally, a sintering and die-bonding process is used to electrically connect the gas-sensitive element, including the sensing and heating electrodes, to the base pads. This application, through vertical electrode interconnection and sintering and die-bonding of the sensing element, replaces traditional wire bonding and dispensing processes, enabling miniaturization of the semiconductor gas sensor, shortening the signal transmission path, and reducing the response time of the semiconductor gas sensor. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a semiconductor gas sensor based on vertical interconnection of ceramic through holes, provided in an embodiment of this application; Figure 2 A schematic diagram of the internal structure of a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, provided in an embodiment of this application; Figure 3 A schematic diagram of the base and gas-sensitive cap in a semiconductor gas sensor based on vertical interconnection of ceramic through holes, provided for an embodiment of this application; Figure 4 A schematic diagram of the combined structure of the base and ceramic substrate in a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, provided in an embodiment of this application; Figure 5 A schematic diagram of the combined structure of the base, ceramic substrate and gas-sensitive cap in a semiconductor gas sensor based on vertical interconnection of ceramic through holes provided in an embodiment of this application; Figure 6 A flowchart illustrating a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, as provided in an embodiment of this application; Figure 7 A flowchart illustrating another method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic vias, as provided in an embodiment of this application. Detailed Implementation

[0019] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0021] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0022] This application provides a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes. This method enables vertical interconnection of the sensing electrode, heating electrode, and base pads using through-holes and conductive metal pillars, avoiding the wire bonding and red glue application processes required in TO-5 packaging technology. This reduces the packaging volume of the gas-sensitive element and achieves sensor miniaturization. The method may include: Step 1: Prepare through holes on the ceramic substrate and groove the ceramic substrate according to the size of the gas-sensitive element.

[0023] Step 2: Using screen printing technology, conductive metal pillars are prepared in the through holes, and the conductive metal pillars penetrate to the first and second surfaces of the ceramic substrate; Step 3: On the first surface of the ceramic substrate, the sensing electrode, heating electrode and insulating layer are fabricated using screen printing technology. Step 4: On the second side of the ceramic substrate, opposite to the first side, the sensing electrode pads and heating electrode pads are fabricated using screen printing technology. Step 5: Use screen printing technology to prepare a gas-sensitive layer on the sensing electrode.

[0024] Since the gas-sensitive layer material may contain sensitive materials, in the screen printing technology of step five, the gas-sensitive layer pattern can be printed through the mesh first, dried, and then sintered to form the gas-sensitive layer.

[0025] Step 6: Using a dicing machine, the ceramic substrate with the prepared gas-sensitive layer is diced into individual gas-sensitive elements along the groove.

[0026] Step 7: Using a sintering and die bonding process, the sensing electrode pads and heating electrode pads on the gas-sensitive element are fixed to the base pads and sintered together with organic gold paste or thick film silver paste.

[0027] In some optional embodiments of this application, the conductive metal pillar in step two can be obtained by screen printing gold or platinum paste into the through-hole followed by high-temperature sintering. The high-temperature sintering temperature in the screen printing technology can be 850-1000℃. The sintering temperature of the organic gold paste or / and thick-film silver paste in step seven is 300-600℃. For example, the thick-film silver paste can be a high-temperature silver paste with a sintering temperature of 500-600℃. The organic gold paste can be a low-temperature gold paste with a sintering temperature of 530-600℃.

[0028] This application employs a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes. It utilizes conductive metal pillars penetrating a ceramic substrate within the through-holes. Sensing electrodes, heating electrodes, an insulating layer, and a gas-sensitive layer are fabricated on the first surface of the ceramic substrate using screen printing technology. Sensing electrode pads and heating electrode pads are fabricated on the second surface of the ceramic substrate. This electrically connects the conductive metal pillars penetrating the through-holes to the heating and sensing electrodes, achieving a vertical electrical connection between the pads and electrodes. Furthermore, a sintering and die-bonding process is used to achieve vertical interconnection between the sensing electrodes and heating electrodes on the gas-sensitive element and the base pads. This application can replace traditional wire bonding and dispensing processes, enabling miniaturization of the semiconductor gas sensor and shortening the transmission path of the sensing signal, thereby reducing the response time of the semiconductor gas sensor.

[0029] See Figure 1 As shown, the semiconductor gas sensor based on vertical interconnection of ceramic through holes prepared in this application embodiment may include: a gas-sensitive cap 1, a gas-sensitive element 2, and a base 3.

[0030] Figure 2 This is a schematic diagram of the internal structure of a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, provided in an embodiment of this application. The gas-sensitive element includes: a ceramic substrate 21, a conductive metal pillar 22, a sensing electrode 23, a heating electrode 24, an insulating layer 25, a gas-sensitive layer 26, and sensing electrode pads 27 and heating electrode pads 28.

[0031] See Figure 2As shown in (a), four through holes 211 are formed on the ceramic substrate 21.

[0032] See Figure 2 As shown in (b), a conductive metal pillar 22 is formed in each through hole 211.

[0033] The first end of the conductive metal pillar 22 protrudes from the first surface of the ceramic substrate 21.

[0034] See Figure 2 As shown in (c) and (d) in the figure, the conductive metal pillar 22 includes a first conductive metal pillar and a second conductive metal pillar.

[0035] See Figure 2 As shown in (d), the first end of the first conductive metal pillar (not shown) protrudes from the first surface of the ceramic substrate 21 and is electrically connected to the sensing electrode 23, and the second end protrudes from the second surface of the ceramic substrate 21 and is connected to the sensing electrode pad 27.

[0036] The first end of the second conductive metal pillar (not shown) extends out from the first surface of the ceramic substrate 21 and is electrically connected to the heating electrode 24, while the second end extends out from the second surface of the ceramic substrate 21 and is connected to the heating electrode pad 28.

[0037] The conductive metal pillar 22 may include two first conductive metal pillars and two second conductive metal pillars. The two first conductive metal pillars are respectively connected to the two ends of the sensing electrode 23, and the two second conductive metal pillars are connected to the two ends of the heating electrode 24.

[0038] See Figure 2 As shown in (e), an insulating layer 25 is formed above the heating electrode 24.

[0039] See Figure 2 As shown in (f), a gas-sensitive layer 26 is formed above the sensing electrode 23.

[0040] In some embodiments of this application, the gas-sensitive layer 26 can be a thick film gas-sensitive layer.

[0041] Figure 3 A schematic diagram of the base and gas-sensitive cap in a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, provided for embodiments of this application. See also... Figure 3 As shown, base 3 can be Figure 4 (a) shows a rectangular base 31 with an opening. The base 3 has four base pads 32, each of which extends through the base 3 to the other side of the base 3. The four base pads 32 are sintered and bonded to the sensing electrode pads 27 and heating electrode pads 28 on the ceramic substrate 21, respectively.

[0042] In some embodiments of this application, the gas-sensitive cap 1 has a micro-vent hole so that the gas that the semiconductor gas sensor needs to detect can enter the cavity.

[0043] Figure 4 A schematic diagram of the combined structure of the base and ceramic substrate in a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, provided in an embodiment of this application. See also... Figure 4 As shown in (a) of this application, in some embodiments, the gas-sensitive element 2 is placed in the base 3. See also Figure 4 As shown in (b), the base 3 is an open cuboid, and the gas-sensitive element 2 is composed of a ceramic substrate 21, a conductive metal pillar 22, a sensing electrode 23, a heating electrode 24, an insulating layer 25, a gas-sensitive layer 26, and sensing electrode pads 27 and heating electrode pads 28. The gas-sensitive element 2 is placed inside the base 3.

[0044] Figure 5 This is a schematic diagram of the combined structure of the base, ceramic substrate, and gas-sensitive cap in a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, as provided in an embodiment of this application. See also... Figure 5 (a) and Figure 5 As shown in (b) of this application, in some embodiments, the gas-sensitive cap 1 has a vent hole, and the gas-sensitive cap 1 is placed above the opening of the base 3, with the size of the gas-sensitive cap matching the opening of the base 3. The gas-sensitive element is placed inside the base 3. The gas-sensitive element is composed of a ceramic substrate 21, a conductive metal pillar 22, a sensing electrode 23, a heating electrode 24, an insulating layer 25, a gas-sensitive layer 26, and sensing electrode pads 27 and heating electrode pads 28.

[0045] For example, this application also provides a method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, see [link to relevant documentation]. Figure 6 As shown, it includes: Step 601: Prepare through holes on the ceramic substrate and groove the ceramic substrate according to the size of the gas-sensitive element.

[0046] Step 602: Using screen printing technology, conductive metal pillars are prepared in the through holes, and the conductive metal pillars penetrate to the first and second surfaces of the ceramic substrate.

[0047] Conductive metal pillars can be obtained by injecting gold or platinum paste into the through holes and then sintering at high temperature. The high-temperature sintering temperature can be from 850℃ to 1000℃.

[0048] Step 603: On the first surface of the ceramic substrate, a sensing electrode, a heating electrode, and an insulating layer are fabricated using screen printing technology.

[0049] Step 604: On the second side of the ceramic substrate opposite to the first side, the sensing electrode pads and heating electrode pads are fabricated using screen printing technology.

[0050] Step 605: A gas-sensitive layer is prepared on the sensing electrode using screen printing technology.

[0051] Since the gas-sensitive layer material may contain sensitive materials, in the screen printing technology of the sensing electrode, the gas-sensitive layer pattern can be printed through the mesh first, dried, and then sintered to form the gas-sensitive layer.

[0052] Step 606: Using a dicing machine, the ceramic substrate with the prepared gas-sensitive layer is diced into individual gas-sensitive elements along the groove.

[0053] Step 607: Using a sintering and die bonding process, the sensing electrode pads and heating electrode pads on the gas-sensitive element are fixed to the base pads and sintered together with organic gold paste or thick film silver paste.

[0054] Organic gold paste or thick film silver paste can be sintered at a low temperature of 300-500℃.

[0055] Step 608: Create a vent hole on the gas-sensitive cap.

[0056] The vent holes on the gas-sensitive cap can be miniature vent holes, so that the gas detected by the semiconductor gas sensor can enter the semiconductor gas sensor.

[0057] Step 609: Use laser welding to weld the gas-sensitive cap to the top of the base.

[0058] In some alternative embodiments of this application, the semiconductor gas sensor based on ceramic through-hole vertical interconnect may further include an open cuboid base in which the gas-sensitive element is placed, and four base pads are formed on the cuboid base, the four base pads passing through the cuboid base.

[0059] The sensing electrode pads and the heating electrode pads are respectively fixed to the four base pads one by one by organic gold paste or thick film silver paste, and then sintered and bonded.

[0060] In this case, the gas-sensitive cap can be welded to the opening of the cuboid base.

[0061] See Figure 6 and Figure 3 As shown, the base can be a one-piece molded box-shaped metal (such as stainless steel), and the gas-sensitive cap is welded to the box-shaped opening of the base, with its size matching the box-shaped opening.

[0062] See Figure 7 As shown in some embodiments of this application, another method for fabricating a semiconductor gas sensor based on vertical interconnects of ceramic through-holes may include: Step 701: Prepare four through holes on the ceramic substrate.

[0063] Step 702: Groove the ceramic substrate according to the size of the gas-sensitive element.

[0064] Step 703: Using screen printing technology, the electrode paste is injected into four through holes through the perforated pattern on the steel mesh. After the four through holes are leveled, four conductive metal pillars are sintered at a sintering temperature of 850-1000℃.

[0065] Steps 701 and 702 can be performed simultaneously or in batches. For example, step 701 can be performed before step 703, and step 702 can be performed after step 703. Performing steps 701 and 702 simultaneously can save the preparation time of the entire process and improve the preparation efficiency.

[0066] Step 704: The sensing electrode paste is printed onto the first side of the ceramic substrate using screen printing and then sintered at high temperature, so that the first ends of the two first conductive metal pillars of the four conductive metal pillars are electrically connected to the two ends of the sensing electrode respectively.

[0067] Step 705: The heating electrode paste is printed onto the first side of the ceramic substrate using screen printing and then sintered at high temperature, so that the first ends of the two second conductive metal pillars of the four conductive metal pillars are electrically connected to the two ends of the heating electrode respectively.

[0068] Step 706: The insulating layer dielectric paste is printed onto the heating electrode using screen printing and then sintered at high temperature to prepare the insulating layer.

[0069] Step 707: Using screen printing, solder pad paste is printed on the second side of the ceramic substrate at the position close to the second end of the first conductive metal pillar, and then sintered at high temperature to prepare two sensing electrode solder pads.

[0070] Step 708: Using screen printing, solder pad paste is printed on the second side of the ceramic substrate at the position close to the second end of the second conductive metal pillar, and then sintered at high temperature to prepare two heating electrode solder pads.

[0071] Step 709: A thick film gas-sensitive layer is prepared on the sensing electrode using screen printing technology.

[0072] Since the gas-sensitive layer material may contain sensitive materials, in the screen printing technology of the sensing electrode, the gas-sensitive layer pattern can be printed through the mesh first, dried, and then sintered to form the gas-sensitive layer.

[0073] Step 710: Using a dicing machine, along the grooves made in step 702, the ceramic substrate with the prepared gas-sensitive layer is diced into individual gas-sensitive elements.

[0074] For example, see Figure 2As shown in (g), in step 710, a gas-sensitive element is cleaved out. The gas-sensitive element includes a pair of sensing electrodes and a heating electrode, a ceramic substrate, four conductive metal pillars, an insulating layer, two sensing electrode pads, and two heating electrode pads. For example, the sensing electrodes are a pair of interdigitated electrodes.

[0075] Step 711: Prepare 4 base pads on the cuboid base.

[0076] For example, four base pads can be located on the base plate that runs through the cuboid base, and their positions correspond to the sensing electrode pads and heating electrode pads.

[0077] For example, the base can be made of stainless steel or ceramic. The base pads can be copper-plated nickel or a copper-nickel alloy, prepared using an electroplating process.

[0078] Step 712: Using a sintering and die bonding process, the sensing electrode pads and heating electrode pads on the gas-sensitive element are fixed to the base pads and sintered together with organic gold paste or thick film silver paste.

[0079] For example, organic gold paste or thick film silver paste is used to fix two sensing electrode pads and two heating electrode pads to four base pads respectively, and then sinter them together.

[0080] Step 713: Use laser welding to weld the gas-sensitive cap to the top of the opening of the cuboid base.

[0081] For example, when the gas-sensitive cap is made of silicon, deep reactive ion etching (DRIE) or wet etching can be used to create vent holes. When the gas-sensitive cap is made of ceramic or metal, laser drilling can be used to create vent holes.

[0082] In some optional embodiments of this application, the vent holes of the gas-sensitive cap can be fabricated using femtosecond laser or laser-electrolysis composite processes to achieve the fabrication of micro-vent holes. The minimum diameter of the micro-vent holes can reach 0.015 mm, and the depth-to-diameter ratio can reach 20:1, thereby further increasing the range in which the sensor volume can be reduced.

[0083] In some optional embodiments of this application, the ceramic substrate can be made of alumina or aluminum nitride, with a thickness ranging from 0.15 to 0.25 mm and a length and width ranging from 40 to 150 mm. For example, the ceramic substrate can be a cuboid with dimensions of 1.2 mm × 1.2 mm × 0.1 mm.

[0084] In some optional embodiments of this application, the diameter of the through hole can be between 0.1 mm and 0.2 mm.

[0085] In some optional embodiments of this application, the conductive metal pillar is an Au pillar or a Pt pillar. After the gold paste or platinum paste is filled into the through hole by screen printing technology, the high-temperature sintering temperature can be 850-1000℃, and the sintering holding time can be 10-20min.

[0086] In some optional embodiments of this application, the sensing electrode material is Pt, the high-temperature sintering temperature can be 850-1000℃, and the sintering holding time can be 10-20 min. The thickness of the sensing electrode obtained by high-temperature sintering ranges from 100-500 nm, and the resistance ranges from 0.01-1 Ω.

[0087] In some optional embodiments of this application, the heating electrode material includes at least one of Pt, AgPt, AgPd, and RuO2, the resistance of the heating electrode can be in the range of 30-100Ω, after screen printing, the temperature of high-temperature sintering of the heating electrode material can be 850-1000℃, the sintering holding time can be 10-20min, and the thickness of the obtained heating electrode can be in the range of 50-500 nm and the width can be in the range of 0.001-0.05 mm.

[0088] In some optional embodiments of this application, the insulating layer dielectric slurry is a glass glaze, the high-temperature sintering temperature of the insulating layer dielectric slurry is 800-850℃, the sintering holding time is 10-15min, and the thickness of the insulating layer can be 50-150 nm.

[0089] In some optional embodiments of this application, the sensing electrode pads and heating electrode pads are made of Pt or Au, with a thickness ranging from 100-500 nm and a resistance ranging from 0.01-1 Ω. The high-temperature sintering temperature is 850-1000℃, and the sintering holding time is 10-20 min.

[0090] In some optional embodiments of this application, the gas-sensitive element can be made of SnO2-based composite material. Different compositions can be used for the gas-sensitive element in semiconductor gas sensors that detect different gases.

[0091] For example, for semiconductor gas sensors that detect flammable gases, the gas-sensitive element can be SnO2 with added sensitizers such as Pd and Pt; for example, for semiconductor gas sensors that detect volatile gases such as alcohol, the gas-sensitive element can be SnO2 with added sensitizers such as La2O3 and components such as antimony oxide to adjust the resistance.

[0092] In some optional embodiments of this application, in order to avoid edge chipping and microcracks in the cleaving process of the gas-sensitive layer, the side of the ceramic substrate (alumina sheet or aluminum nitride sheet) with the solder pads can be attached to the blue film, that is, the side facing down can be attached to the blue film. In this way, the blue film can be used to buffer and support the stress, and avoid the solder pads from peeling off or the ceramic substrate from microcracks caused by the cutting vibration of the cleaving machine.

[0093] In some optional embodiments of this application, organic gold paste or thick film silver paste is used to fix the ceramic substrate pads to the base pads. The electrical connection between the pads on the ceramic substrate (including sensing electrode pads and heating electrode pads) and the base pads is achieved by low-temperature sintering technology. The sintering temperature of the low-temperature sintering technology is 300-600℃.

[0094] Some alternative embodiments of this application provide a semiconductor gas sensor, which may include: A ceramic substrate 21 is provided with through holes 211, grooves, heating electrodes 24 and sensing electrodes 23. The through holes contain conductive metal pillars 22, and the grooves are prepared according to the size of the gas-sensitive element. The first end of the conductive metal pillar 22 extends out from the first surface of the ceramic substrate 21 and is electrically connected to the sensing electrode 23 and the heating electrode 24. The second end of the conductive metal pillar 22 extends out from the second surface of the ceramic substrate 21 and is sintered and bonded to the sensing electrode pad 27 and the heating electrode pad 28.

[0095] In some embodiments of this application, an insulating layer is formed above the heating electrode 24.

[0096] In some embodiments of this application, a gas-sensitive layer is formed above the sensing electrode 23.

[0097] In some embodiments of this application, the ceramic substrate containing the gas-sensitive layer 26 is diced along the groove by a dicing machine to prepare a single gas-sensitive element, conductive metal pillar 22, heating electrode 24, sensing electrode 23, sensing electrode pad 27 and heating electrode pad 28, which are then bonded by sintering with gold paste or platinum paste.

[0098] In some embodiments of this application, the semiconductor gas sensor further includes an open cuboid base 31, in which a gas-sensitive element is placed. At least two base pads 32 are prepared on the cuboid base 31, and the at least two base pads 32 pass through the cuboid base 31.

[0099] For example, the first base pad passes through the cuboid base 31 and is bonded to the sensing electrode pad 27, and the second base pad passes through the cuboid base 31 and is bonded to the heating electrode pad 28. See also Figure 3As shown, the sensing electrode pads 27 and heating electrode pads 28 can be distributed at the four ends of the first surface of the ceramic substrate 21. There can be two sensing electrode pads 27, located at the two ends of the first surface of the ceramic substrate 21, and there can be two heating electrode pads 28, located at the two ends of the first surface of the ceramic substrate 21.

[0100] Thick film silver paste can be high-temperature silver paste with a sintering temperature above 500℃, for example, high-temperature silver paste with a sintering temperature of 500-600℃.

[0101] In some embodiments of this application, the semiconductor gas sensor further includes a gas-sensitive cap 1, which is welded to the top of the first surface of the ceramic substrate 21, wherein the gas-sensitive cap 1 has a vent hole.

[0102] If the semiconductor gas sensor is an n-type semiconductor, after the base pad 32 is connected to the external power supply, the heating electrode 24 is turned on and releases heat, causing the temperature of the gas-sensitive element to rise rapidly to the temperature required for the gas-sensitive reaction. At this time, the gas-sensitive element material is in a high-resistance state. When the gas to be detected enters the semiconductor gas sensor through the vent in the gas-sensitive cap 1 and reacts with the gas-sensitive element material, the gas-sensitive element material changes to a low-resistance state. Through the reaction of the gas-sensitive element material, the high and low resistance states of the gas-sensitive element are switched. The high and low resistance states correspond to the high and low voltages in the semiconductor gas sensor circuit, respectively, thereby realizing the semiconductor gas sensor's sensing of the gas.

[0103] In some optional embodiments of this application, the ceramic substrate can be made of alumina or aluminum nitride, with a thickness ranging from 0.15 to 0.25 mm and a length and width ranging from 40 to 150 mm. For example, the ceramic substrate can be a cuboid with dimensions of 1.2 mm × 1.2 mm × 0.1 mm.

[0104] In some optional embodiments of this application, the diameter of the through hole can be between 0.1 mm and 0.2 mm.

[0105] In some optional embodiments of this application, the conductive metal pillar is an Au pillar or a Pt pillar.

[0106] In some optional embodiments of this application, the heating electrode material includes at least one of Pt, AgPt, AgPd, and RuO2, and the heating electrode resistance can be in the range of 30-100Ω.

[0107] In some optional embodiments of this application, the sensing electrode is an interdigitated electrode, the number of electrode pairs of the sensing electrode ranges from 1 to 50, and the sensing electrode material may include at least one of Au, Pt, AgPt, and AgPd.

[0108] In some alternative embodiments of this application, the insulating layer is silicon oxide or silicon nitride.

[0109] In some optional embodiments of this application, the sensing electrode pads and heating electrode pads are Pt or Au, with a thickness ranging from 100 to 500 nm and a resistance ranging from 0.01 to 1 Ω.

[0110] In some optional embodiments of this application, the base pad is a copper-nickel alloy or a copper-nickel plated composite material.

[0111] In some optional embodiments of this application, the gas-sensitive cap is made of stainless steel (304 / 316L) or an iron-nickel alloy.

[0112] In some optional embodiments of this application, the base is made of any one of aluminum oxide, aluminum nitride, stainless steel, or iron-nickel alloy.

[0113] The semiconductor gas sensor provided in this application embodiment has through-holes fabricated on a ceramic substrate, and conductive metal pillars penetrating the ceramic substrate are fabricated in the through-holes. Sensing electrodes, heating electrodes, insulating layers, and gas-sensitive layers are fabricated on the first surface of the ceramic substrate using screen printing technology. Sensing electrode pads and heating electrode pads are fabricated on the second surface of the ceramic substrate. The conductive metal pillars penetrating the through-holes of the ceramic substrate are electrically connected to the heating electrodes and sensing electrodes, realizing the vertical interconnection of the pads and electrodes. Then, through a sintering and die bonding process, the gas-sensitive elements, including the sensing electrodes and heating electrodes, are electrically connected to the base pads. This application embodiment replaces the traditional wire bonding and dispensing processes with vertical electrode interconnection and sintering and die bonding technology for the sensing elements, which can realize the miniaturization of the semiconductor gas sensor, shorten the transmission path of the sensing signal, and reduce the response time of the semiconductor gas sensor.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for fabricating a semiconductor gas sensor based on vertical interconnection of ceramic through-holes, characterized in that, include: Through holes are prepared on a ceramic substrate, and grooves are cut into the ceramic substrate according to the size of the gas-sensitive element; A conductive metal pillar is fabricated in the through-hole using screen printing technology, and the conductive metal pillar extends to the first and second surfaces of the ceramic substrate. On the first surface of the ceramic substrate, a sensing electrode, a heating electrode, and an insulating layer are fabricated using screen printing technology. On the second surface of the ceramic substrate opposite to the first surface, sensing electrode pads and heating electrode pads are respectively prepared by screen printing technology; a gas-sensitive layer is prepared on the sensing electrode by screen printing technology. The ceramic substrate with the prepared gas-sensitive layer is split into individual gas-sensitive elements by a splitting machine along the groove; By using a sintering and die bonding process, the sensing electrode pads and heating electrode pads on the gas-sensitive element are fixed to the base pads and sintered together using organic gold paste or thick film silver paste, wherein the sintering temperature is 300 to 600°C.

2. The preparation method according to claim 1, characterized in that, The preparation method further includes: A gas-sensitive cap is welded to the top of the first side of the ceramic substrate using laser welding, wherein the gas-sensitive cap has vent holes.

3. The preparation method according to claim 1, characterized in that, Fabricating through holes on a ceramic substrate, including: fabricating 4 through holes on a ceramic substrate; The conductive metal pillars are prepared in the through holes by: injecting electrode paste into the four through holes through a hole pattern on a steel mesh using screen printing technology, and sintering the four conductive metal pillars at a sintering temperature of 850-1000℃ after leveling the four through holes.

4. The preparation method according to claim 3, characterized in that, Using screen printing technology, sensing electrodes, heating electrodes, and insulating layers were fabricated, including: The sensing electrode paste is printed onto the first side of the ceramic substrate using screen printing, and sintered at a sintering temperature of 850-1000℃, so that the first ends of the first conductive metal pillars of the four conductive metal pillars are electrically connected to the sensing electrode. The heating electrode paste is printed onto the first side of the ceramic substrate using screen printing. A sintering temperature of 850-1000℃ is used to electrically connect the first ends of two of the four conductive metal pillars to the heating electrode. The insulating layer dielectric paste is printed onto the heating electrode using screen printing technology, and then sintered to form the insulating layer.

5. The preparation method according to claim 1, characterized in that, The method further includes: The gas-sensitive element is placed in an open cuboid base, on which four base pads are prepared, and the four base pads pass through the cuboid base. The process of fixing and sintering the sensing electrode pads and heating electrode pads on the gas-sensitive element to the base pads using organic gold paste or thick-film silver paste includes: Using organic gold paste or thick film silver paste, the sensing electrode pads and the heating electrode pads are fixed one-to-one with the four base pads and sintered together. There are two sensing electrode pads and two heating electrode pads.

6. A semiconductor gas sensor based on vertical interconnection of ceramic through-holes, characterized in that, The semiconductor gas sensor, prepared by the method described in any one of claims 1 to 5, comprises: A ceramic substrate having through holes, grooves, heating electrodes, and sensing electrodes, wherein the through holes contain conductive metal pillars, and the grooves are formed according to the size of the gas-sensitive element; The first end of a portion of the conductive metal pillar extends out from the first surface of the ceramic substrate and is electrically connected to the sensing electrode; The first end of a portion of the conductive metal pillar extends from the first surface of the ceramic substrate and is electrically connected to the heating electrode; The second end of the conductive metal pillar extends from the second surface of the ceramic substrate and is sintered and bonded to the corresponding sensing electrode pad and heating electrode pad, respectively.

7. The semiconductor gas sensor according to claim 6, characterized in that, An insulating layer is formed above the heating electrode.

8. The semiconductor gas sensor according to claim 6, characterized in that, A gas-sensitive layer is formed above the sensing electrode, wherein the ceramic substrate on which the gas-sensitive layer is located is cleaved along the groove by a cleaving machine to prepare a single gas-sensitive element.

9. The semiconductor gas sensor according to claim 6, characterized in that, The semiconductor gas sensor also includes an open cuboid base. The gas-sensitive element is placed in an open cuboid base. Four base pads are prepared on the cuboid base. The four base pads pass through the cuboid base. The sensing electrode pad and the heating electrode pad are respectively fixed to the four base pads one by one by organic gold paste or thick film silver paste and sintered and bonded.

10. The semiconductor gas sensor according to claim 6, characterized in that, The semiconductor gas sensor further includes: A gas-sensitive cap is welded to the top of the first side of the ceramic substrate, wherein the gas-sensitive cap has vent holes.

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