Pyroelectricity-based non-magnetic low-voltage MEMS (Micro Electro Mechanical System) sputtering ion pump

Abstract

The invention relates to a non-magnetic low-voltage MEMS (Micro Electro Mechanical System) sputtering ion pump based on pyroelectricity. The device comprises an electron emission layer, a first spacing layer, an electron acceleration layer, a second spacing layer and an ion adsorption layer, the thinned pyroelectric crystal in the electron emission layer can generate a pyroelectric effect after the surface temperature changes, so that potential is accumulated on the surface of the crystal and electrons are released. Different from traditional electron emission of a hot cathode and a cold cathode, the electron emission structure is stable in electron emission, low in working temperature, low in working voltage and low in requirement for the vacuum degree of a working environment. Therefore, the MEMS pyroelectric sputtering ion pump based on the pyroelectric principle provided by the invention has the advantages of low working temperature, low working voltage, no need of a magnetic field and the like, and a relatively reliable vacuum pump is provided for obtaining a vacuum environment of an MEMS type vacuum device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ion pumps, and particularly relates to a MEMS pyroelectric sputtering ion pump. BACKGROUND

[0002] With the development of micro-nano processing and micro-electro-mechanical system (MEMS) technology, vacuum electronic devices are developed towards miniaturization, on-chip and integration, and many good results have been achieved. However, these micro vacuum electronic devices usually need an external vacuum pump or vacuum pump set to obtain and maintain a vacuum environment to work normally, and the traditional vacuum pump (vacuum pump set) is not only heavy, but also has high energy consumption and high price. In recent years, people tend to use vacuum packaging technology to help micro vacuum devices maintain vacuum, that is, device assembly is carried out in vacuum, and then vacuum packaging technology is used to isolate external air to maintain vacuum degree. Although the overall volume of the system can be effectively reduced, the current micro-cavity vacuum packaging technology cannot well meet the vacuum degree needs of these micro vacuum devices.

[0003] The sputtering ion pump in the gas adsorption pump has more researches in miniaturization. The main adsorption principle of the sputtering ion pump is to push the ionized charged gas ions to the adsorbent material by an electric field. On the one hand, these particles will be shot into the adsorbent material and buried. On the other hand, in the process of the particles being shot into the adsorbent material, some adsorbent materials will be sputtered. These sputtered particles will adsorb gas molecules and deposit in the pump to fix the gas molecules, so as to achieve the adsorption effect. However, the existing micro sputtering ion pump is mostly based on field emission principle, needs an external high voltage to obtain initial electrons and an external magnetic field to prolong the electron motion trajectory and increase the ionization probability, and is not suitable for micro vacuum systems requiring low pressure and magnetic-free environment. SUMMARY

[0004] The purpose of the application is to provide a MEMS pyroelectric sputtering ion pump suitable for low pressure and magnetic-free environment to solve the above problems.

[0005] The application achieves the above purpose by the following technical scheme: A MEMS pyroelectric sputtering ion pump, comprising an electron emission layer, an electron acceleration layer and an ion adsorption layer, wherein the ion adsorption layer comprises a first substrate and an ion adsorbent arranged on the surface of the first substrate, and a first pyroelectric component and a first temperature adjusting component for adjusting the temperature of the first pyroelectric component are further arranged on the first substrate, and the first pyroelectric component is used to form an electric field on the ion adsorption layer to prolong the motion trajectory of the electrons by repulsive force.

[0006] As a further optimization scheme of the present application, the electron acceleration layer comprises a second substrate, and a plurality of through holes formed on the second substrate, the second substrate is provided with a second pyroelectric component for accelerating the electrons passing through the through holes, and a second temperature regulating component for regulating the temperature of the second pyroelectric component, in this scheme, the electron acceleration layer is realized by providing the second pyroelectric component on the second substrate, and the acceleration electric field is formed by controlling the temperature of the second pyroelectric component.

[0007] As a further optimization scheme of the present application, the electron emission layer comprises a third substrate, a third pyroelectric component provided on the third substrate, and a third temperature regulating component for regulating the temperature of the third pyroelectric component, the electron emission layer also uses the pyroelectric component to form the electron emission structure.

[0008] As a further optimization scheme of the present application, a first spacing layer is arranged between the third substrate and the second substrate to form a first cavity, and a second spacing layer is arranged between the first substrate and the second substrate to form a second cavity, the first cavity, the through hole, and the second cavity constitute an ion pump ionization region.

[0009] As a further optimization scheme of the present application, the third pyroelectric component is a pyroelectric, the first pyroelectric component and the second pyroelectric component are pyroelectric crystals, and the material of the pyroelectric component is one of lithium tantalate, lithium niobate, lead zirconate, lead titanate, tris glycine sulfate, and lead zirconium titanate.

[0010] As a further optimization scheme of the present application, the third substrate is provided with a fixing member for fixing the third pyroelectric component, the fixing member is matched with the third pyroelectric component through a groove, and the fixing member is made of glass.

[0011] As a further optimization scheme of the present application, the ion adsorbent comprises at least one of titanium, tantalum, and aluminum.

[0012] As a further optimization scheme of the present application, the first temperature regulating component, the second temperature regulating component, and the third temperature regulating component are all Peltier.

[0013] As a further optimization scheme of the present application, the first substrate, the second substrate, and the third substrate are all silicon layers.

[0014] As a further optimization scheme of the present application, the first spacing layer and the second spacing layer are both glass layers.

[0015] The present application has the following beneficial effects: The MEMS pyroelectric sputtering ion pump provided by the present invention can be placed in a microcavity to improve and maintain the vacuum degree in the cavity. At the same time, the voltage required for the heating element is usually a few volts, which is suitable for many occasions where high voltage cannot be applied. By adding additional pyroelectric crystals to the ion adsorption layer to provide an additional electric field to extend the electron motion trajectory, it is suitable for low voltage, low operating temperature, and non-magnetic working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic cross-sectional structure diagram of the present invention; Figure 3 is a schematic cross-sectional view of a fixing member of the present invention; Figure 4 is a schematic diagram of a second substrate of the present invention; Figure 5 It is a schematic diagram of the electron trajectory simulation of the present invention; In the figure: 1. first temperature-regulating component; 2. first substrate; 3. fixing member; 4. first pyroelectric component; 5. first spacer; 6. first chamber; 7. second pyroelectric component; 8. second temperature-regulating component; 9. second substrate; 10. through hole; 11. third temperature-regulating component; 12. third pyroelectric component; 13. third substrate; 14. ion adsorbent; 15. second spacer; 16. second chamber. DETAILED DESCRIPTION

[0017] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0018] Example 1 like Figures 1-4 As shown, a MEMS pyroelectric sputtering ion pump includes an electron emission layer, an electron acceleration layer and an ion adsorption layer, wherein the ion adsorption layer includes a first substrate 2 and an ion adsorbent 14 arranged on the surface of the first substrate 2. The first substrate 2 is also provided with a first pyroelectric component 4 and a first temperature adjustment component 1 for adjusting the temperature of the first pyroelectric component 4. The first pyroelectric component 4 is used to form an electric field on the ion adsorption layer to extend the movement trajectory of electrons through repulsion.

[0019] The MEMS pyroelectric sputtering ion pump can be placed in a microcavity to improve and maintain the environmental vacuum degree, and the voltage required by the heating element is usually several volts, which is suitable for many occasions where high voltage cannot be applied, and the additional pyroelectric crystal or pyroelectricity is added to the ion adsorption layer to prolong the electron motion trajectory, which is suitable for low voltage, low working temperature and non-magnetic working environment.

[0020] The electron acceleration layer comprises a second substrate 9 and a plurality of through holes 10 formed in the second substrate 9, and the second substrate 9 is provided with a second pyroelectric component 7 for accelerating electrons passing through the through holes 10 and a second temperature regulating component 8 for regulating the temperature of the second pyroelectric component 7.

[0021] The electron emission layer comprises a third substrate 13, a third pyroelectric component 12 arranged on the third substrate 13, and a third temperature regulating component 11 for regulating the temperature of the third pyroelectric component 12.

[0022] The first spacing layer 5 is arranged between the third substrate 13 and the second substrate 9 to form a first cavity 6, and the second spacing layer 15 is arranged between the first substrate 2 and the second substrate 9 to form a second cavity 16, and the first cavity 6, the through hole 10 and the second cavity 16 constitute an ion pump ionization region.

[0023] The ion adsorbent 14 is arranged on one side of the first substrate 2 close to the ionization region, and the first pyroelectric component 4 and the first temperature regulating component 1 are arranged on the other side of the first substrate 2; the second pyroelectric component 7 and the second temperature regulating component 8 are arranged on one end of the second substrate 9 away from the ionization region; the third substrate 13 is provided with a fixing member 3 for fixing the third pyroelectric component 12, the fixing member 3 is made of glass, the fixing member 3 and the third pyroelectric component 12 are matched through a groove, and the fixing member 3 is arranged on one end of the third substrate 13 close to the ionization region, while the third temperature regulating component 11 is arranged on the other side of the third substrate 13, the fixing member 3 has one groove and one through slot, the area of the groove is the same as that of the first pyroelectric component 4, and the first pyroelectric component 4 is inlaid in the groove, and the area of the through slot is smaller, so that the emitted electrons can reach the ionization region.

[0024] The third pyroelectric component 12 is a thinned pyroelectric crystal, the first pyroelectric component 4 and the second pyroelectric component 7 are pyroelectric crystals, and the material of the pyroelectric component is one of lithium tantalate, lithium niobate, lead zirconate, lead titanate, tris glycine sulfate and lead zirconium titanate.

[0025] Pyroelectric material is a material that can convert the fluctuation of temperature with time (dT / dt, where t is time and T is temperature) into electric energy. The pyroelectric material has no symmetry center in the internal structure of the crystal, has spontaneous polarization, and the change in temperature causes internal strain, which causes the relative displacement of the positive and negative charge centers, thus causing the change in polarization of the pyroelectric material, and generates pyroelectric charge on the surface perpendicular to the direction of the polarization intensity. The thickness of the pyroelectric crystal is generally micron level, which can be integrated in the MEMS sputtering ion pump as an electron source, and the response speed of the crystal polarization to the change in temperature is very fast. The free charge attracted from the outside cannot compensate for the pyroelectric charge in time, so as to generate a voltage or emit a current on the surface of the crystal, and the energy of the electrons released by it under vacuum conditions is enough to ionize gas molecules. The generated pyroelectric current is shown in the following formula: (1) The surface potential accumulated by the pyroelectric effect is: (2) In formula (1) and formula (2), p is the pyroelectric coefficient, A is the surface area of the pyroelectric crystal, h is the thickness of the crystal, Q is the charge quantity, is the dielectric constant, is the space dielectric constant, T is the temperature, is the temperature difference.

[0026] The ion adsorbent 14 includes at least one of titanium, tantalum, and aluminum, and the ion adsorbent 14 has a certain activity and can adsorb or chemically combine with most gas ions that may exist in the vacuum.

[0027] The first temperature adjusting component 1, the second temperature adjusting component 8, and the third temperature adjusting component 11 are all Peltier. The first substrate 2, the second substrate 9, and the third substrate 13 are all silicon layers. The first spacing layer 5 and the second spacing layer 15 are both glass layers.

[0028] The basic principle and process of realizing pumping by the ion pump are as follows. The change in the temperature of the third temperature adjusting component 11 causes the change in the polarity of the electron emission layer thin pyroelectric crystal, so as to cause the accumulation of potential on the surface of the pyroelectric crystal and electron emission. The electrons enter the first chamber 6 and are accelerated by the electron acceleration layer. After being accelerated by the electron acceleration layer, the electrons enter the second chamber 16, and are decelerated by the voltage generated by the ion adsorption layer in the second chamber 16, so as to change the electron trajectory, thereby realizing the extension of the electron trajectory. The electron trajectory is shown in Figure 5 , the ionization probability is increased, and the gas ions are generated by the collision between the electrons and the air molecules in the process of movement. Under the comprehensive action of the electric field of the electron acceleration layer and the ion adsorption layer, the gas ions bombard the ion adsorbent 14 on the ion adsorption layer, sputter and form an adsorption layer film, so as to achieve the pumping effect.

[0029] The ion pump is suitable for low-voltage non-magnetic condition, only needs to provide 5V heating voltage for the pyroelectric crystal, and the temperature change can accumulate potential on the surface of the crystal, realizes the emission of electrons and the accumulation of surface potential, thins the pyroelectric crystal at the electron source to emit electrons, and the crystal of the adsorption layer and the acceleration layer provides a composite electric field instead of a magnetic field to change the electron motion trajectory.

[0030] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A MEMS pyroelectric sputtering ion pump, characterized in that: The invention comprises an electron emission layer, an electron acceleration layer and an ion adsorption layer, wherein the ion adsorption layer comprises a first substrate (2) and an ion adsorbent (14) arranged on the surface of the first substrate (2); the first substrate (2) is further provided with a first pyroelectric component (4) and a first temperature adjustment component (1) for adjusting the temperature of the first pyroelectric component (4); the first pyroelectric component (4) is used to form an electric field on the ion adsorption layer to extend the movement trajectory of electrons through repulsion.

2. The MEMS pyroelectric sputtering ion pump according to claim 1, wherein: The electron acceleration layer comprises a second substrate (9) and a plurality of through holes (10) provided on the second substrate (9); a second pyroelectric component (7) for accelerating electrons passing through the through holes (10) and a second temperature regulating component (8) for regulating the temperature of the second pyroelectric component (7) are provided on the second substrate (9).

3. The MEMS pyroelectric sputtering ion pump according to claim 2, wherein: The electron emission layer includes a third substrate (13), a third pyroelectric component (12) arranged on the third substrate (13), and a third temperature adjustment component (11) for adjusting the temperature of the third pyroelectric component (12).

4. The MEMS pyroelectric sputtering ion pump according to claim 3, wherein: A first spacer layer (5) is provided between the third substrate (13) and the second substrate (9) to enclose a first chamber (6); a second spacer layer (15) is provided between the first substrate (2) and the second substrate (9) to enclose a second chamber (16); the first chamber (6), the through hole (10) and the second chamber (16) constitute an ion pump ionization region.

5. The MEMS pyroelectric sputtering ion pump according to claim 3, wherein: The third pyroelectric component (12) is a thinned pyroelectric crystal, the first pyroelectric component (4) and the second pyroelectric component (7) are pyroelectric crystals, and the material of the pyroelectric component is one of lithium tantalate, lithium niobate, lead zirconate, lead titanate, triglycine sulfate, and lead zirconate titanate.

6. The MEMS pyroelectric sputtering ion pump according to claim 5, characterized in that: A fixing piece (3) for fixing the third pyroelectric component (12) is provided on the third substrate (13); the fixing piece (3) and the third pyroelectric component (12) are engaged with each other via a groove; the fixing piece (3) is made of glass.

7. The MEMS pyroelectric sputtering ion pump according to claim 1, wherein: The ion adsorbent (14) includes at least one of titanium, tantalum, and aluminum.

8. The MEMS pyroelectric sputtering ion pump according to claim 3, wherein: The first temperature control component (1), the second temperature control component (8) and the third temperature control component (11) are all Peltiers.

9. The MEMS pyroelectric sputtering ion pump according to claim 3, wherein: The first substrate (2), the second substrate (9) and the third substrate (13) are all silicon layers.

10. The MEMS pyroelectric sputtering ion pump according to claim 4, characterized in that: The first spacer layer (5) and the second spacer layer (15) are both glass layers.

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