Tail gas particle sensor and manufacturing method
By using gallium nitride transistor devices and heating parts in automotive exhaust particle sensors, the existing sensors are solved inadequate sensitivity and high energy consumption in low concentration environments, achieving higher detection accuracy and longer service life.
Patent Information
- Application Number
- CN202411344438.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-31
AI Technical Summary
Existing automotive exhaust particle sensors are insufficient in low concentration environments, and complex structures and high energy consumption limit their application. The cumulative sensors have problems with initial response dead zones and high voltage requirements.
Using a gallium nitride transistor device, the ohmic contact electrode is arranged on the top semiconductor surface, and a detection window is arranged in pairs to form a direct contact with the medium to be detected, and combined with the heating element for regeneration, simplifying the structure and reducing energy consumption.
Improves sensor detection sensitivity and accuracy, is suitable for low voltage operations, extends service life and simplifies maintenance processes.
Smart Images
Figure CN119223822A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of sensor technology, and more specifically, to an exhaust gas particle sensor and a manufacturing method thereof. Background Art
[0002] With the increasing awareness of environmental protection, countries have implemented stricter regulatory standards on the amount of particulate matter in the exhaust emissions of internal combustion engine vehicles, aiming to significantly reduce air pollution and protect human health and the ecological environment. In this context, particulate filters and supporting on-board monitoring systems have become indispensable key components.
[0003] At present, the automobile exhaust particle sensors on the market are mainly divided into two categories: real-time response type and accumulation type. Real-time response type sensors can instantly capture the changes of particulate matter in exhaust gas. However, when faced with low-concentration particulate matter environments, such sensors often show insufficient sensitivity, affecting the accuracy and effectiveness of monitoring. In addition, their complex structural design and high energy consumption requirements (usually requiring high-voltage power supply support at the kilovolt level) not only increase the manufacturing cost, but also pose challenges to the long-term stability and reliability of the sensor, thereby limiting its popularity in market applications.
[0004] Although the accumulation type particulate matter sensor makes up for the lack of sensitivity of the real-time response type sensor in low concentration environment to a certain extent, and realizes measurement by accumulating particle mass, its inherent initial response dead zone or blind spot problem has become a technical bottleneck. This means that at the beginning of vehicle startup or the beginning of emission condition change, the sensor may not be able to provide effective data immediately, affecting the immediacy and accuracy of emission monitoring. At the same time, in order to shorten the blind spot time or perform the sensor's own regeneration processing, the accumulation type sensor also needs to consume higher voltage and power, further increasing the complexity and energy consumption of the system. Summary of the invention
[0005] The purpose of the embodiments of the present application is to provide an exhaust gas particle sensor and a manufacturing method to solve the technical problem of difficulty in detecting the content of automobile exhaust particles in the prior art.
[0006] To achieve the above purpose, the technical solution adopted in this application is: Provided is an exhaust gas particle sensor, comprising a gallium nitride transistor device, wherein an ohmic contact electrode of the gallium nitride transistor device is arranged on the surface of a top semiconductor, the ohmic contact electrodes are arranged in pairs, and a detection window is formed between the ohmic contact electrodes arranged in pairs, and the detection window is in direct contact with a medium to be detected; A heating element is also provided on the surface of the top semiconductor layer of the gallium nitride transistor device, and the heating element is used to regenerate the detection window.
[0007] As a further improvement of the above technical solution: Optionally, the gallium nitride transistor device includes a base layer, a buffer layer, a barrier layer and a cap layer stacked in sequence from bottom to top, a two-dimensional electron gas is formed on the interface between the buffer layer and the barrier layer, and the ohmic contact electrode, the detection window and the heating element are all arranged on the surface of the cap layer.
[0008] Optionally, the material of the base layer includes any one of silicon, sapphire, and silicon carbide; the buffer layer is a gallium nitride buffer layer; the barrier layer is an aluminum gallium nitride barrier layer; the cap layer is a gallium nitride cap layer; and the top semiconductor of the gallium nitride transistor device is a gallium nitride cap layer.
[0009] Optionally, the barrier layer has a thickness ranging from 5 nm to 25 nm, and the cap layer has a thickness ranging from 0 nm to 2 nm.
[0010] Optionally, a passivation layer is further included, and the passivation layer covers the surfaces of the top semiconductor, the heating element and the ohmic contact electrode.
[0011] Optionally, the passivation layer is a silicon oxide passivation layer or a silicon nitride passivation layer, and the thickness of the passivation layer is in the range of 50 nm-250 nm.
[0012] Optionally, the ohmic contact electrode is composed of one or more materials selected from the group consisting of Ti, Al, Ni, Mo, Pt, Cr, and Au.
[0013] Optionally, the width of the detection window ranges from 2 μm to 200 μm.
[0014] Optionally, the heating temperature range of the heating element is 25°C-450°C.
[0015] The present application also provides a method for manufacturing the exhaust gas particle sensor, comprising the following steps: Obtaining gallium nitride transistor epitaxial materials; Using a plasma etching method, a boss structure is formed on the gallium nitride transistor epitaxial material; On the surface of the top semiconductor of the boss structure, an ohmic contact electrode is generated by metal deposition and annealing; A heating element is added on the surface of the top semiconductor of the boss structure by using a deposition and patterning process; A passivation layer is added on the surface of the boss structure, the surface of the ohmic contact electrode and the surface of the heating element, and a detection window is opened between the ohmic contact electrodes.
[0016] The exhaust gas particulate sensor and manufacturing method provided by the present application have the following beneficial effects: The exhaust particle sensor provided by the present application includes a gallium nitride transistor device, wherein the ohmic contact electrode of the gallium nitride transistor device is arranged on the surface of the top semiconductor, the ohmic contact electrodes are arranged in pairs, and a detection window is formed between the ohmic contact electrodes arranged in pairs, and the detection window is in direct contact with the medium to be detected. The surface of the top semiconductor of the gallium nitride transistor device has a high concentration of positive charge surface states. When the detection window contacts the medium to be detected, according to the charge neutrality principle, the charge state of the particles in the automobile exhaust will directly affect the surface charge of the top semiconductor, and then affect the current between the ohmic contact electrodes. Specifically, the accumulation of positively charged particles will increase the surface charge of the top semiconductor, thereby enhancing the current between the ohmic contact electrodes; while the accumulation of negatively charged particles will neutralize the surface charge of the top semiconductor, resulting in a decrease in conductivity between the ohmic contact electrodes and a decrease in current. By measuring the change in the current between the ohmic contact electrodes, the main charge polarity and concentration of the particles in the automobile exhaust can be accurately determined. A heating element is also provided on the surface of the top semiconductor of the gallium nitride transistor device. When the sensor signal reaches the saturation state, the heating element heats up and causes the particles attached to the detection window to expand and fall off, thereby regenerating the detection window. This not only increases the service life of the exhaust particle sensor, but also simplifies its maintenance process. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0018] Figure 1 A schematic cross-sectional view of the exhaust gas particle sensor provided in this application; Figure 2 A schematic cross-sectional structural diagram of the first step of the manufacturing method of the exhaust gas particulate sensor provided by the present application; Figure 3 A schematic cross-sectional structural diagram of the second step of the method for manufacturing the exhaust particulate sensor provided by the present application; Figure 4 A schematic cross-sectional structural diagram of the third step of the method for manufacturing an exhaust gas particulate sensor provided in the present application; Figure 5 This is a schematic cross-sectional structural diagram of the fourth step of the method for manufacturing the exhaust particulate sensor provided in the present application.
[0019] Among them, the reference numerals in the figure are: 1. Base layer; 2. Buffer layer; 3. Barrier layer; 4. Cap layer; 5. Two-dimensional electron gas; 6. Ohmic contact electrode; 7. Detection window; 8. Heating element; 9. Passivation layer. DETAILED DESCRIPTION
[0020] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.
[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.
[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0023] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0024] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0025] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of the present invention.
[0026] In the following description, suffixes such as "module", "component", "assembly" or "unit" are used only to facilitate the description of the present invention and have no specific meanings. Therefore, they can be used in combination.
[0027] The present invention will be further described in detail below through specific implementation modes in conjunction with the accompanying drawings.
[0028] like Figure 1 As shown, the present application provides an exhaust gas particle sensor, including a gallium nitride transistor device, such as an aluminum gallium nitride / gallium nitride high molecular mobility transistor (AlGaN / GaN HEMT) device. The use of the gallium nitride transistor device can reduce the volume of the sensor, and is also beneficial to improving the detection sensitivity of the sensor, and can also be suitable for low voltage operation.
[0029] Among them, the ohmic contact electrode 6 of the gallium nitride transistor device is arranged on the surface of the top semiconductor. Ohmic contact refers to the contact between metal and semiconductor. The ohmic contact electrodes 6 are arranged in pairs, serving as the source electrode and the drain electrode of the transistor respectively. A detection window 7 is formed between the ohmic contact electrodes 6 arranged in pairs, and the detection window 7 is in direct contact with the medium to be detected. The surface of the top semiconductor of the gallium nitride transistor device has a high concentration of positive charge surface states. When the detection window 7 contacts the medium to be detected, according to the charge neutrality principle, the charge state of the particles in the automobile exhaust will directly affect the surface charge of the top semiconductor, and then affect the current between the ohmic contact electrodes 6. Specifically, the accumulation of positively charged particles will increase the surface charge of the top semiconductor, thereby enhancing the current between the ohmic contact electrodes 6; while the accumulation of negatively charged particles will neutralize the surface charge of the top semiconductor, resulting in a decrease in conductivity between the ohmic contact electrodes 6 and a decrease in current. By measuring the change in the current between the ohmic contact electrodes 6, the main charge polarity and concentration of the particles in the automobile exhaust can be accurately determined.
[0030] In addition, a heating element 8 is provided on the surface of the top semiconductor of the gallium nitride transistor device. When the sensor signal reaches a saturated state, the heating element 8 heats up and causes the particles attached to the detection window 7 to expand and fall off, thereby regenerating the detection window 7, which not only increases the service life of the exhaust particle sensor, but also simplifies its maintenance process.
[0031] like Figure 1 As shown, in one embodiment of the present application, the gallium nitride transistor device includes a base layer 1, a buffer layer 2, a barrier layer 3 and a cap layer 4 stacked in sequence from bottom to top. Among them, the material of the base layer 1 is generally any one of silicon, sapphire and silicon carbide. The buffer layer 2 plays the role of reducing stress, reducing defect density and electrical insulation. The buffer layer 2 serves as a current channel, and its component can specifically be gallium nitride. The component of the barrier layer 3 can specifically be aluminum gallium nitrogen. A two-dimensional electron gas 5 is formed on the interface between the buffer layer 2 and the barrier layer 3. The two-dimensional electron gas 5 refers to the phenomenon that the electron gas can move freely in the two-dimensional direction but is restricted in the third dimension. It is the basis for the operation of many field effect devices. The cap layer 4 interacts with the barrier layer 5, and the ohmic contact electrode 6, the detection window 7 and the heating element 8 are all arranged on the surface of the cap layer 4. The cap layer 4 can be doped or use intrinsic materials, such as gallium nitride. By setting the cap layer 4, the surface flatness of the top semiconductor of the exhaust particle sensor can be improved and the ohmic contact resistance can be reduced.
[0032] In one embodiment of the present application, the thickness of the barrier layer 3 is in the range of 5 nm-25 nm, and the thickness of the cap layer 4 is in the range of 0 nm-2 nm. The specific values can be selected according to the actual needs of the product.
[0033] like Figure 1As shown, in one embodiment of the present application, the exhaust gas particle sensor further includes a passivation layer 9. The passivation layer 9 covers the surface of the top semiconductor, the heating element 8 and the ohmic contact electrode 6. The function of the passivation layer 9 is to prevent the medium to be detected from contacting the part outside the detection window 7, so as to avoid short circuit of the source electrode and the drain electrode or affect the accuracy of the sensor.
[0034] In one embodiment of the present application, the passivation layer 9 is made of silicon oxide or silicon nitride. In other embodiments, the passivation layer 9 may also be made of other oxides, polymers, or other organic or inorganic materials. The thickness of the passivation layer 9 is in the range of 50 nm to 250 nm, and the specific value of the thickness of the passivation layer 9 may be selected according to the actual needs of the product.
[0035] In one embodiment of the present application, the ohmic contact electrode 6 is stacked by one or more metal materials selected from Ti, Al, Ni, Mo, Pt, Cr, and Au. The ohmic contact electrode 6 is made by metal deposition and forming, and high temperature annealing technology.
[0036] In one embodiment of the present application, the width of the detection window 7 ranges from 2 μm to 200 μm, and the specific value of the width of the detection window 7 can be selected according to actual product requirements.
[0037] In one embodiment of the present application, the heating temperature range of the heating element 8 is 25°C-450°C.
[0038] The present application also provides a method for manufacturing the exhaust gas particle sensor in the above embodiment, which specifically includes the following steps: like Figure 2 As shown, a gallium nitride transistor epitaxial material is obtained in advance. The gallium nitride transistor epitaxial material specifically includes a base layer 1, a buffer layer 2, a barrier layer 3 and a cap layer 4 stacked in sequence from bottom to top. A two-dimensional electron gas 5 is formed on the interface between the buffer layer 2 and the barrier layer 3.
[0039] like Figure 3 As shown, a plasma etching method is used to dry-etch the sample using chlorine gas and boron trichloride gas to form a boss structure on the gallium nitride transistor epitaxial material; like Figure 4 As shown, on the surface of the top semiconductor of the boss structure, metal deposition and annealing are used. First, a physical vapor deposition device is used to deposit metal stacks such as Ti, Al, Ni, Mo, Pt, Cr, Au, etc. that can form an ohmic contact on the sample surface, and then the sample is heated to 750°C-870°C and maintained for 25 seconds-50 seconds by a rapid annealing method. An ohmic contact electrode 6 is generated; like Figure 5As shown, on the surface of the top semiconductor of the boss structure, a deposition and patterning process is used to deposit Pt and other metals that can be used for heating on the sample surface by physical vapor deposition, and then the deposited film is patterned by photolithography, so as to finally achieve the effect of adding a heating element 8; like Figure 1 As shown, a passivation layer 9 is added to the surface of the entire device, and a plasma enhanced chemical vapor deposition device is used to deposit silicon oxide or silicon nitride on the sample at 300-350° C. Finally, the sample is patterned by photolithography, and then the sample is dry-etched using sulfur hexafluoride or trifluoromethane gas in a plasma etching device to achieve the effect of opening a detection window 7.
[0040] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims
1. An exhaust gas particle sensor, characterized in that: Comprising a gallium nitride transistor device, wherein an ohmic contact electrode (6) of the gallium nitride transistor device is arranged on the surface of a top semiconductor, the ohmic contact electrodes (6) are arranged in pairs, and a detection window (7) is formed between the ohmic contact electrodes (6) arranged in pairs, and the detection window (7) is in direct contact with a medium to be detected; A heating element (8) is also provided on the surface of the top semiconductor of the gallium nitride transistor device, and the heating element (8) is used to regenerate the detection window (7).
2. The exhaust gas particle sensor according to claim 1, characterized in that: The gallium nitride transistor device comprises a base layer (1), a buffer layer (2), a barrier layer (3) and a cap layer (4) which are stacked in sequence from bottom to top; a two-dimensional electron gas (5) is formed on the interface between the buffer layer (2) and the barrier layer (3); and the ohmic contact electrode (6), the detection window (7) and the heating element (8) are all arranged on the surface of the cap layer (4).
3. The exhaust gas particle sensor according to claim 2, characterized in that: The material of the base layer (1) includes any one of silicon, sapphire and silicon carbide; the buffer layer (2) is a gallium nitride buffer layer; the barrier layer (3) is an aluminum gallium nitride barrier layer; the cap layer (4) is a gallium nitride cap layer; and the top semiconductor of the gallium nitride transistor device is a gallium nitride cap layer.
4. The exhaust gas particle sensor according to claim 3, characterized in that: The thickness of the barrier layer (3) is in the range of 5 nm to 25 nm, and the thickness of the cap layer (4) is in the range of 0 nm to 2 nm.
5. The exhaust gas particle sensor according to claim 2, characterized in that: It also comprises a passivation layer (9), wherein the passivation layer (9) covers the surfaces of the top semiconductor, the heating element (8) and the ohmic contact electrode (6).
6. The exhaust gas particle sensor according to claim 5, characterized in that: The passivation layer (9) is a silicon oxide passivation layer or a silicon nitride passivation layer, and the thickness of the passivation layer (9) is in the range of 50 nm to 250 nm.
7. The exhaust gas particle sensor according to any one of claims 1 to 6, characterized in that: The ohmic contact electrode (6) is made of one or more materials selected from the group consisting of Ti, Al, Ni, Mo, Pt, Cr, and Au.
8. The exhaust gas particle sensor according to any one of claims 1 to 6, characterized in that: The width of the detection window (7) ranges from 2 μm to 200 μm.
9. The exhaust gas particle sensor according to any one of claims 1 to 6, characterized in that: The heating temperature range of the heating element (8) is 25°C-450°C.
10. The method for manufacturing the exhaust gas particle sensor according to any one of claims 1 to 9, characterized in that: The steps include: Obtaining gallium nitride transistor epitaxial materials; Using a plasma etching method, a boss structure is formed on the gallium nitride transistor epitaxial material; On the surface of the top semiconductor of the boss structure, an ohmic contact electrode (6) is formed by metal deposition and annealing; On the surface of the top semiconductor of the boss structure, a heating element (8) is added by using a deposition and patterning process; A passivation layer (9) is added to the surface of the boss structure, the surface of the ohmic contact electrode (6) and the surface of the heating element (8), and a detection window (7) is opened between the ohmic contact electrodes (6).