Miniature ionization vacuum sensor and vacuum gauge

Abstract

The invention relates to the technical field of ionization vacuum sensors, and discloses a miniature ionization vacuum sensor and a vacuum gauge, the sensor comprises at least one sensor unit, each sensor unit comprises a doped semiconductor substrate, one side surface of the doped semiconductor substrate is provided with at least one groove; the insulating dielectric layer is positioned on the surface of one side of the doped semiconductor substrate and in an area outside the groove; the electrode layer is located on the surface of one side, away from the semiconductor substrate, of the insulating dielectric layer; two-dimensional electron gas is distributed on the interface of the doped semiconductor substrate and the insulating dielectric layer and serves as a field emission electron source; a nanometer air channel is formed between the bottom of the groove and the target surface, and the target surface is the surface where the surface of the side, away from the insulating dielectric layer, of the electrode layer is located. By introducing the nano air channel, the interelectrode distance is reduced, so that the working voltage is reduced. In addition, the coulomb repulsive force effect between electrons in the two-dimensional electron gas can further reduce the working voltage.

Description

Technical Field

[0001] This application relates to the field of ionization vacuum sensor technology, and in particular to a miniature ionization vacuum sensor and vacuum gauge. Background Technology

[0002] Miniature ionization vacuum sensors are a type of miniature vacuum sensor that measures vacuum levels using the principle of gas molecule ionization. They hold promise for measuring vacuum levels of 1E-3 Pa and even higher, and have crucial applications in pressure detection within small spaces and special environments. While miniature vacuum sensors offer advantages in high and ultra-high vacuum monitoring compared to other types (such as miniature Pirani vacuum sensors and miniature thin-film vacuum sensors), their application and development are still constrained by high-voltage electronic source technology and the requirements for ultra-high initial vacuum.

[0003] The functional part of the micro ionization vacuum sensor based on field emission cold cathode consists of a field emission cold cathode, an anode, and an ion collecting electrode. It uses a field emission cold cathode as the electron source and has gone through the development of Spindt cathode, diamond and diamond-like thin film cathode, carbon nanotube cathode, and MIM (Metal-Insulator-Metal) cathode. Compared with traditional thermionic vacuum sensors, although it has solved the problems of high operating temperature, thermal and light radiation, and long response time, the problem of high operating voltage still exists. Since the distance between the cathode and anode is on the micrometer scale, field emission requires a strong electric field on the order of 1V / nm, so the operating voltage is high, usually from several hundred volts to thousands of volts.

[0004] Therefore, how to solve the above-mentioned technical problems should be a key focus for those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a miniature ionization vacuum sensor and vacuum gauge to reduce operating voltage and power consumption.

[0006] To address the aforementioned technical problems, this application provides a miniature ionization vacuum sensor, comprising at least one sensor unit. Each sensor unit includes: a doped semiconductor substrate, wherein at least one groove is provided on one side surface of the doped semiconductor substrate; an insulating dielectric layer located on one side surface of the doped semiconductor substrate and in the region outside the groove; an electrode layer located on the side surface of the insulating dielectric layer opposite to the semiconductor substrate; a two-dimensional electron gas distributed at the interface between the doped semiconductor substrate and the insulating dielectric layer, the two-dimensional electron gas serving as a field emission electron source; and a nano-air channel formed from the bottom of the groove to a target surface, the target surface being the surface on the side surface of the electrode layer opposite to the insulating dielectric layer.

[0007] Optionally, the number of sensor units is one.

[0008] Optionally, the number of sensor units is at least two, and adjacent sensor units are isolated by an insulating isolator, which is located on one side surface of the doped semiconductor substrate.

[0009] Optionally, the lengths of the nano-air channels in one of the sensor units are equal, while the lengths of the nano-air channels in the micro ionization vacuum sensor are at least two different.

[0010] Optionally, the electrode layers in different sensor units have the same area.

[0011] Optionally, the electrode layer comprises any one or any combination of the following metal layers:

[0012] Au layer, Pt layer, Ni layer, Cr layer, Ti layer, Mo layer, W layer.

[0013] Optionally, in each of the sensor units, the doped semiconductor substrate has at least two of the grooves, and all the grooves are of the same size.

[0014] Optionally, the diameter of the groove ranges from 10 nm to 10 μm.

[0015] Optionally, the shortest length of the nano-air channel is less than the mean free path of electrons in air.

[0016] This application also provides a vacuum gauge, including any of the miniature ionization vacuum sensors described above.

[0017] The miniature ionized vacuum sensor provided in this application includes at least one sensor unit. Each sensor unit incorporates a nanometer-sized air channel. A two-dimensional electron gas at the interface between the doped semiconductor substrate and the insulating dielectric layer serves as a field emission electron source. Since the length of the nanometer-sized air channel (i.e., the inter-electrode distance) is on the nanometer scale, according to the relationship between voltage and electric field strength, when the same electric field strength is required, the required operating voltage is reduced due to the reduced length of the nanometer-sized air channel. Furthermore, the use of a two-dimensional electron gas as the electron source in this application further reduces the electron emission threshold due to the Coulomb repulsion between electrons in the two-dimensional electron gas, resulting in a further reduction in the operating voltage. Therefore, the operating voltage of the miniature ionized vacuum sensor in this application is reduced, thereby also reducing power consumption; the operating voltage can be reduced to below 100V. In addition, by reducing the inter-electrode distance, this application can significantly reduce the electron transport time, further improving the response speed of the miniature ionized vacuum sensor.

[0018] In addition, this application also provides a vacuum gauge with the above-mentioned advantages. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0020] Figure 1 A top view of a miniature ionization vacuum sensor provided in an embodiment of this application;

[0021] Figure 2 A cross-sectional schematic diagram of a miniature ionization vacuum sensor provided in an embodiment of this application;

[0022] In the figure, 100 is the sensor unit, 1 is the doped semiconductor substrate, 2 is the insulating dielectric layer, 3 is the electrode layer, 4 is the nano-air channel, and 5 is the insulating isolator. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] As described in the background section, the operating voltage of existing miniature ionization vacuum sensors is typically in the range of several hundred volts to several thousand volts, or at least one or two hundred volts, which limits the development of miniature ionization vacuum sensors.

[0026] In view of this, this application provides a miniature ionization vacuum sensor, please refer to... Figure 1 and Figure 2 The miniature ionization vacuum sensor includes at least one sensor unit 100, and each sensor unit 100 includes:

[0027] A doped semiconductor substrate 1, wherein at least one groove is provided on one side surface of the doped semiconductor substrate 1;

[0028] An insulating dielectric layer 2 located on one side surface of the doped semiconductor substrate 1, and in the region outside the groove;

[0029] Electrode layer 3 located on the surface of the insulating dielectric layer 2 facing away from the semiconductor substrate;

[0030] Two-dimensional electron gas (2DEG) is distributed at the interface between the doped semiconductor substrate 1 and the insulating dielectric layer 2. The two-dimensional electron gas (2DEG) serves as a field emission electron source. A nano-air channel 4 is formed from the bottom of the groove to the target surface, which is the surface of the electrode layer 3 facing away from the insulating dielectric layer 2.

[0031] The length of the nano-air channel 4 is on the scale of tens of nanometers.

[0032] This application applies the principles of nano-air channel electronics to a micro ionization vacuum sensor, solving the problem of high operating voltage in existing micro ionization vacuum sensors. This provides a new technical route for the development of micro ionization vacuum sensors and can promote their development.

[0033] It should be noted that this application does not limit the number of sensor units 100 included in the miniature ionization vacuum sensor.

[0034] In one possible implementation, the number of sensor units 100 is one.

[0035] As another possible implementation, the number of sensor units 100 is at least two, and adjacent sensor units 100 are isolated by an insulating isolator 5, and the insulating isolator 5 is located on one side surface of the doped semiconductor substrate 1.

[0036] The insulating insulator 5 can be made of the same material as the insulating dielectric layer 2.

[0037] like Figure 1 and Figure 2 As shown, the example is a sensor unit 100 with 3 units.

[0038] It should be noted that this application does not limit the doping type of the doped semiconductor substrate 1; it depends on the specific circumstances. For example, the doped semiconductor substrate 1 can be an n-type semiconductor substrate or a p-type semiconductor substrate.

[0039] Doped semiconductor substrate 1 is a heavily doped semiconductor substrate with a doping concentration ≥ 1 × 10⁻⁶. 14 cm -3 .

[0040] The doped semiconductor substrate 1 is compatible with CMOS (Complementary Metal Oxide Semiconductor) processes, which facilitates the subsequent integration of miniature ionized vacuum sensors with other semiconductor electronic devices on the same substrate, enabling the integration of different types of devices.

[0041] This application does not limit the type of doped semiconductor substrate 1, and the type can be selected at will. For example, the doped semiconductor substrate 1 can be any of the following: doped silicon substrate, doped SOI (silicon on insulator) substrate, or doped compound semiconductor substrate. The doped compound semiconductor substrate can be a doped GaN substrate, a doped GaAs substrate, or a doped SiC substrate, etc.

[0042] It should be noted that the number of grooves in the doped semiconductor substrate 1 in each sensor unit 100 is not limited in this application, but depends on the situation.

[0043] As one possible implementation, the number of grooves in the doped semiconductor substrate 1 of each sensor unit 100 can be one.

[0044] As another possible implementation, in each of the sensor units 100, the doped semiconductor substrate 1 has at least two of the grooves, and all the grooves are the same size, which can simplify the manufacturing process.

[0045] The number of grooves in different sensor units 100 may be the same or different, and both are within the protection scope of this application.

[0046] It should be noted that the shape of the groove is not limited in this application and depends on the circumstances. For example, the shape of the groove can be circular, rectangular, square, elliptical, or trapezoidal, etc. It can be understood that the shape of the groove is also the shape of the nano-air channel 4.

[0047] The size of the groove affects the operating current of the miniature ionization vacuum sensor. This application does not limit the size of the groove; it depends on the specific circumstances.

[0048] In one embodiment of this application, when the groove is circular, the diameter of the groove can range from 10 nm to 10 μm. For example, the diameter of the groove can be 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, 5 μm, 7 μm, 10 μm, etc.

[0049] The smaller the size of the groove, the more conducive it is to the miniaturization of the micro ionization vacuum sensor.

[0050] The electrode layer 3 is made of metal. The doped semiconductor substrate 1, the insulating dielectric layer 2 and the electrode layer 3 form a MIS (Metal-Insulator-Semiconductor) structure. Under the condition of applying an external electric field, a two-dimensional electron gas is formed at the interface between the doped semiconductor substrate 1 and the insulating dielectric layer 2.

[0051] In each sensor unit 100, a two-dimensional electron gas serves as a field-induced electron emission source. The effective emission area of ​​the two-dimensional electron gas is related to the total perimeter of the nano-air channel 4 on the target surface. The two-dimensional electron gas emits electrons, ionizing the air in the nano-air channel 4 to generate ions.

[0052] The operating current of the miniature ionized vacuum sensor is adjusted by the effective emission area of ​​the two-dimensional electron gas.

[0053] According to the field emission theory formula:

[0054] ; (1)

[0055] Where I is the operating current, A = 1.541434 × 10 -6 A·eV·V -2 B=6.830890 eV -3 / 2 ·V·nm -1 v(f) and t(f) are functions of the image force: t 2 (f)≈1.1, v(f)≈0.95-f, f≈c 2 E / φ 2 c 2 ≈1.44 eV 2 (V / nm) -1 φ is the work function of the emitter material, E is the electric field strength on the emitter surface, and α is the effective emission area.

[0056] In each sensor unit 100, the total perimeter of the nano-air channels 4 on the target surface is adjusted (e.g., the number of nano-air channels 4 and the size of the nano-air channels 4 are adjusted) to control the effective emission area, thereby controlling the operating current of the micro ionization vacuum sensor.

[0057] This application does not specify the material of electrode layer 3; it can be selected by the applicant.

[0058] As one possible implementation, the electrode layer 3 includes, but is not limited to, any one or any combination of the following metal layers: Au layer, Pt layer, Ni layer, Cr layer, Ti layer, Mo layer, and W layer. Au, Pt, Ni, Cr, Ti, Mo, and W are all refractory metals, which can enhance the electrode layer 3's resistance to ion damage and extend its service life.

[0059] The thickness of electrode layer 3 is not limited in this application and can be set by the user. For example, the thickness of electrode layer 3 can range from 10nm to 500nm. For example, the thickness of electrode layer 3 can be 10nm, 50nm, 100nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc.

[0060] The type of insulating dielectric layer 2 is not limited in this application and can be set by the user. For example, the insulating dielectric layer 2 includes, but is not limited to, any one or any combination of silicon oxide layer, silicon nitride layer, aluminum oxide layer, hafnium oxide layer, zirconium oxide layer, and tantalum oxide layer.

[0061] The insulating dielectric layer 2 and the electrode layer 3 are sequentially stacked on the non-groove region of the doped semiconductor substrate 1. The region where the groove is located extends vertically upward to form a pore, which is the nano-air channel 4. The length of the nano-air channel 4 is the distance from the bottom of the groove to the surface of the electrode layer 3 on the side opposite to the insulating dielectric layer 2.

[0062] Within the same sensor unit 100, the length of the nano-air channel 4 is the same. In different sensor units 100, the length of the nano-air channel 4 may be the same or different.

[0063] The length of the nano-air channel 4 affects the response range of the miniature ionization vacuum sensor.

[0064] In one embodiment of this application, the shortest length of the nano-air channel 4 is less than the mean free path of electrons in air.

[0065] When there are two or more lengths of nano-air channels 4, this application does not limit the length of the longest nano-air channel 4, but determines it as appropriate. For example, the length of the longest nano-air channel 4 is greater than 60 nm.

[0066] The response range of existing ionization vacuum sensors is severely limited by the initial working pressure of the cathode electron source, because the cathode electron source often requires an initial high vacuum of better than 1E-3 ~ 1E-5 Pa to work stably, resulting in a narrow response range of the ionization vacuum sensor, which can only cover ultra-high vacuum above 1E-3 Pa.

[0067] Mean free path refers to the average distance a gas molecule travels between two consecutive collisions with other molecules. In air at normal pressure, the mean free path of an electron in air is 60 nm.

[0068] In this embodiment, the length of the smallest nano-air channel 4 is set to be less than the mean free path of electrons in air. This means that electrons, during their journey from the two-dimensional electron gas to the electrode layer 3, are highly unlikely to collide with any air molecules. Even if the surrounding area is filled with air, the environment for electrons flying this extremely short distance is functionally equivalent to a "vacuum." Therefore, the electron source can operate in an atmospheric environment, i.e., the initial vacuum requirement for electron emission is reduced to atmospheric pressure, greatly reducing the initial vacuum requirement of the electron source and thus broadening the response range of the ionization vacuum sensor. In this embodiment, the miniature ionization vacuum sensor has a wide range of 1E3 to 1E-5 Pa.

[0069] In one embodiment of this application, when the number of sensor units 100 is at least two, the lengths of the nano-air channels 4 in one sensor unit 100 are equal, and the lengths of the nano-air channels 4 in the micro ionization vacuum sensor are at least two different.

[0070] Assuming the number of sensor units 100 is M (M≥2), then the length of the nano air channel 4 can have N (2≤N≤M) possible lengths.

[0071] like Figure 2 As shown, taking three sensor units 100 as an example, the lengths of the nano air channels 4 in different sensor units 100 are different, with the lengths of the nano air channels 4 being L1, L2, and L3, respectively.

[0072] By setting up nano-air channels of various lengths 4, the sensitivity of vacuum detection can be improved.

[0073] Electrons collide with the gas in the nano-air channel 4 under the influence of an electric field, generating ions that form an ion flow I. i Ion flow I i The relationship between the density of gas molecules per unit volume N and the density of gas molecules per unit volume is as follows:

[0074] ; (2)

[0075] Among them, I i For ion flow, I e Where N is the current generated by electrons, N is the gas molecule density, and L is the length of the nanometer air channel. is the electron ionization cross section for a given gas type, k is the Boltzmann constant, T is the gas temperature, and P is the gas pressure.

[0076] The sensitivity S of the miniature ionization vacuum sensor is:

[0077] (3)

[0078] The sensitivity S is a constant, depending on the electrode structure of the miniature ionization vacuum sensor, the size of the nano-air channel 4, the gas type, the gas temperature, the electrode voltage, etc.

[0079] As can be seen from formula (3), the sensitivity S is proportional to the length L of the nano air channel 4. Since the length L of the nano air channel 4 in this application is at the nanometer level, when there is only one type of length L of the nano air channel 4, the sensitivity decreases because the length L of the nano air channel 4 is very small.

[0080] By setting the length L of the nano-air channel 4 to two or more lengths, and connecting multiple nano-air channels 4 of different lengths in parallel, the electron path length of the overall ionization space is increased, thereby improving the sensitivity of the micro ionization vacuum sensor.

[0081] The size of the electrode layer 3 in each sensor unit 100 affects the current density of the sensor unit 100. The relationship between the size of the electrode layer 3 in each sensor unit 100 is not limited in this application and depends on the situation.

[0082] In one embodiment of this application, when the number of sensor units 100 is at least two, the area of ​​the electrode layer 3 in the different sensor units 100 is the same. In this case, the current density of the different sensor units 100 is the same, making it convenient to obtain the desired current density by adjusting the number of sensor units 100.

[0083] In other embodiments of this application, when the number of sensor units 100 is at least two, the area of ​​the electrode layer 3 in different sensor units 100 is different. In this case, the current density of different sensor units 100 is different, and the current density can be adjusted without adjusting the number of sensor units 100.

[0084] The miniature ionization vacuum sensor provided in this embodiment includes at least one sensor unit 100. Each sensor unit 100 incorporates a nanometer-sized air channel 4. A two-dimensional electron gas at the interface between the doped semiconductor substrate 1 and the insulating dielectric layer 2 serves as a field emission electron source. Since the length of the nanometer-sized air channel 4 (i.e., the inter-electrode distance) is on the nanometer scale, according to the relationship between voltage and electric field strength, when the same electric field strength is required, the required operating voltage is reduced due to the reduced length of the nanometer-sized air channel 4. Furthermore, this embodiment uses a two-dimensional electron gas as the electron source. The Coulomb repulsion between electrons in the two-dimensional electron gas further reduces the electron emission threshold, resulting in a further reduction in the operating voltage. Therefore, the operating voltage of the miniature ionization vacuum sensor in this embodiment is reduced, which in turn reduces power consumption, with the operating voltage potentially dropping below 100V. In addition, by reducing the inter-electrode distance, this application can significantly reduce the electron transport time, further improving the response speed of the miniature ionization vacuum sensor.

[0085] This application also provides a vacuum gauge, including the miniature ionization vacuum sensor described in any of the above embodiments.

[0086] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0087] The miniature ionization vacuum sensor and vacuum gauge provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the solution and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A micro ionization vacuum sensor, characterized by, The sensor unit comprises at least one sensor unit, each of which comprises: a doped semiconductor substrate, one side surface of which is provided with at least one groove; an insulating medium layer located on one side surface of the doped semiconductor substrate and outside the groove; an electrode layer located on the side surface of the insulating medium layer away from the semiconductor substrate; a two-dimensional electron gas distributed at the interface between the doped semiconductor substrate and the insulating medium layer, which serves as a field emission electron source; and a nanometer air channel formed between the bottom of the groove and a target surface, which is the surface where the side surface of the electrode layer away from the insulating medium layer is located.

2. The micro ionization vacuum sensor of claim 1, wherein, The number of the sensor units is one.

3. The micro ionization vacuum sensor of claim 1, wherein, The number of the sensor units is at least two, and adjacent sensor units are separated by an insulating separator located on one side surface of the doped semiconductor substrate.

4. The micro ionization vacuum sensor of claim 3, wherein, The lengths of the nanometer air channels in one sensor unit are equal, and the lengths of the nanometer air channels in the micro ionization vacuum sensor are at least two.

5. The micro ionization vacuum sensor of claim 3, wherein, The areas of the electrode layers in different sensor units are the same.

6. The micro ionization vacuum sensor of claim 1, wherein, The electrode layer comprises any one of the following metal layers or any combination of the metal layers: Au layer, Pt layer, Ni layer, Cr layer, Ti layer, Mo layer, and W layer.

7. The micro ionization vacuum sensor of claim 1, wherein, In each sensor unit, the doped semiconductor substrate has at least two grooves, and the sizes of all the grooves are the same.

8. The micro ionization vacuum sensor of claim 1, wherein, The diameter of the groove ranges from 10 nm to 10 μm.

9. The micro ionization vacuum sensor according to any one of claims 1 to 8, characterized in that The length of the shortest nanometer air channel is less than the average free path of electrons in air.

10. A vacuum gauge characterized by The micro ionization vacuum sensor comprises any one of the sensor units according to claims 1 to 9.

Images