RU2532684C2 - Switch and commutator switch - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to a switch or a commutator switch having at least one said switch, which comprises a MEMS-based bistable element, switching means and a switching node. The switching node used is a MIS transistor, the movable gate of which is a movable spring-loaded diaphragm with at least one conducting element over the channel region of the MIS transistor and with an inclusion of magnetic material. The magnetic inclusion on the diaphragm can be made of magnetically soft or magnetically hard material. To move the diaphragm from one stable state to another, the magnetic inclusion on the diaphragm is exposed to external or switch-integrated one or more magnetic field sources.

EFFECT: high-reliability, easy to manufacture and universal MEMS switch with fixed states, while maintaining the state without power, which does not require high switching voltages and does not have magnetic contacts.

9 cl, 2 dwg

Description

The invention relates to electronic switches and switches, and in particular to microelectromechanical switches (MEMS switches) with fixed states, as well as to switches constructed using them.

MEMS switches are known that comprise elastic elements made according to planar technology and capable of closing electrical contacts using various means for moving movable elements: electrostatic [US 5578976, US 6744338 (resonance)], magnetic [US 20090302981], electromagnetic [US 20120013423 ], bimetallic [US 7619289], piezoelectric [US 8022599] and other drives (actuators).

The disadvantage of MEMS switches with an electrostatic drive is also the need to use relatively high voltages, both to start switching and when maintaining in a switched state. The disadvantage of MEMS switches with a piezoelectric drive is also the need for high voltages and, in addition, the degradation of the material of the piezoelectric. The disadvantage of permanent magnet MEMS switches is the need.

A common drawback of these MEMS switches is the need to preserve the switching effect and the corresponding energy consumption to maintain the state of the switch (on or off).

Known MEMS switch, which for moving the elastic element to the switched state and vice versa contains an electromagnetic drive, and for holding in one of these states contains a permanent magnet [US 7420447]. The disadvantage of this MEMS switch is the use of additional elements to ensure fixation in one of the states, as well as the associated manufacturing complexity and low reliability.

Known MEMS switch containing bistable flexible elements [US 6303885] and an electrostatic comb drive. Its disadvantage is the need for a large voltage application and a large drive area.

Another disadvantage of these switches is the presence of electromechanical contacts.

Known electronic MEMS valves based on MOS transistors with a movable gate, driven by thermosensitive elements and / or an electrostatic drive [http://center.gipress.ru/demo_ren_result_vah.html, http://center.gipress.ru/demo_ren_result_sensor .html]. Their disadvantage is the need for heating and / or the use of high voltage and the need to maintain this effect to maintain state.

The objective of the invention is the creation of a MEMS switch with fixed states, maintaining the state in the absence of power, not requiring high voltage for switching, without mechanical contacts, with high isolation of control and controlled circuits, with high reliability, easy to manufacture and universal in use .

To solve the problem, the switch (or a switch that includes at least one such switch or a plurality of such switches) contains a MEMS-style bistable element, switching means and a switching unit, the bistable element being made in the form of a flat conductive membrane or a membrane with or without a conductive part electrically conductive parts suspended above the surface of the substrate on elastic elements (or on one elastic element enclosing the membrane) compressing it in an unstable position equilibrium, with the possibility of translating it in both directions from the position of unstable equilibrium and with the possibility of applying to the electrically conductive part of the membrane electric displacement or the same or other displacements to different electrically conductive parts of the membrane, the switching means are made in the form of a magnetic layer on the membrane and the source or sources magnetic field outside the membrane, and the switching unit is made in the form of at least one MOS transistor for which (which) the gate is (are) an electrically conductive part st (electrically conductive parts) of the described movable membrane.

The presence or absence of conductivity between the drain and source regions of the MIS structure, i.e., the state of the switch, depends on the position of the membrane relative to the MIS structure, when a certain electrical bias is applied to the electrically conductive part of the membrane. Methods for calculating control voltages depending on the parameters of the MIS structures are well known. Mechanical electrical contacts in the proposed device are absent, and the role of the valve is played by a MIS transistor with the described movable gate.

In an embodiment of the invention, the movable gate may be common to two or more MOS transistors of the switch. In this case, several electrical circuits can be switched simultaneously, including electrically isolated from each other or isolated from each other. Capacitive coupling between individual circuits through a common gate can also be eliminated by designing a membrane with several separate, electrically unconnected, conducting areas serving as movable closures for individual switching nodes - MIS valves that are identical or different from each other.

The proposed switch may contain as switching nodes complementary MIS valves with a common bistable element with one or more conductive parts.

In an embodiment of the invention, the magnetic layer on the membrane is made of soft magnetic material, and the source of the magnetic field can be made in the form of one or more electro- or permanent magnets with the possibility of positioning it (or them) on opposite sides of the membrane as part of the switch or outside it. When a magnetic field source acts on the magnetic layer of a bistable element, the latter shifts from the side of this source and occupies one of the fixed positions, and when the magnetic field source acts on the other side, it occupies the second of possible fixed positions, thus transferring the switch from one state to another. In this case, the sources of the magnetic field can be either permanent magnets or electromagnets formed as part of the switch or located outside the switch, as well as their combinations. In particular, one of the variants of the invention provides for the presence of two electromagnets in the switch formed on different sides of the membrane beyond its possible displacements.

An embodiment of the invention is the described switch, in which the magnetic layer on the membrane is made of hard magnetic material (permanent magnet), and the source of the alternating magnetic field is an external or made electromagnet integral with the switch. This electromagnet can be made in the form of a flat or multilayer spiral deposited around a MIS structure (or MIS structures), the movable shutter of which (of which) is this membrane. To increase the efficiency of the electromagnet, the switch may contain a layer of soft magnetic material located either inside the spiral, or under the spiral, or above the spiral, acting as a core. Moreover, to prevent sticking, the membrane or layer of soft magnetic material contains structural elements that specify the distance of their maximum convergence.

The elastic elements of the proposed switch can be made integral with the membrane from the same material as the membrane, or from another material wavy or arched in the direction from the membrane (diverging) and coated with one or both sides of the coating or coatings of materials providing internal stresses at the interface: contracting - on the convex sides, tensile - on the concave. The surface stresses arising in multilayer structures consisting of various materials and formed in various modes are well studied and ensure, during manufacture, the reproducibility of the properties of such structures.

Figure 1 and figure 2 is a sectional view (schematically, without indicating well-known auxiliary layers and elements and with a symbol of electrical connections) in two fixed states, a variant of the proposed switch with a magnetically hard layer on the membrane and an integrated electromagnet. The numbers indicate:

1 - semiconductor substrate,

2 - membrane

3 - conductive layer

4 - layer of hard magnetic material,

5 - a flat spiral of an electromagnet,

6 - flat core,

7 - the source of the MOS transistor,

8 - drain MOS transistor,

9 - dielectric,

10 - elastic elements.

An example of a specific implementation is a switch based on a silicon MIS structure of size 5 × 15 μm with dielectric layers of silicon oxide, a membrane made of silicon with a thickness of 0.5 μm, rectangular in size 5 × 10 μm, located at a distance from the surface of the MIS structure 2 μm, with elastic elements in the form of four silicon arcs 0.5 μm thick and 2 μm wide, curved from the surface structure. A layer of solid magnetic material made of cobalt and rare earth elements with a thickness of 0.5 μm on the membrane is made over its entire surface, a flat coil is made in the form of a single-layer spiral rectangular plan of 5 turns of aluminum 1.0 μm thick and 1.0 μm wide, located under the membrane and partially protruding from beneath it, with a permalloy core in the form of a layer with a thickness of 1.0 μm over the entire surface of a flat coil with an intermediate dielectric layer of aluminum oxide.

The proposed switch does not require power to maintain a given state, the matrix of such switches are capable of operating as high-speed switches with state preservation (for example, as part of information boards or logic circuits, performing, in particular, the functions of long-term memory), the switch provides electrical isolation of circuits (as controls from both controlled and switched from each other), the design of the switch is simple and reliable, and the technology for manufacturing such structures is widely known stna and well mastered.

Claims (9)

1. A switch or switch comprising at least one switch containing a bistable element in MEMS design, switching means and a switching unit, characterized in that the bistable element is made in the form of a flat conductive or with conductive parts of the membrane suspended above the surface of the substrate on elastic elements (or on one elastic element enclosing the membrane), compressing it in an unstable equilibrium position, with the possibility of translating it in both directions from the unstable position active equilibrium and with the possibility of applying electric bias to the electrically conductive part of the membrane or the same or different biases to different electrically conductive parts of the membrane, the switching means are made in the form of a magnetic layer on the membrane and a source or sources of magnetic field outside the membrane, and the switching unit is made in the form of at least at least one MIS structure, for which (which) the gate is (are) the electrically conductive part (electrically conductive parts) of the described movable membrane. 2. The switch according to claim 1, characterized in that the switching node contains complementary MIS structures. 3. The switch according to claim 1, characterized in that the magnetic layer on the membrane is made of soft magnetic material, and the magnetic field source is made in the form of one or more electro- and / or permanent magnets with the possibility of positioning it (or them) on opposite sides of the membrane in or out of a switch. 4. The switch according to claim 1, characterized in that the magnetic layer on the membrane is made of soft magnetic material, and the source of the magnetic field are electromagnets made integrally with the switch on both sides of the membrane outside the range of its possible movements. 5. The switch according to claim 1, characterized in that the magnetic layer on the membrane is made of hard magnetic material (permanent magnet), and the source of the alternating magnetic field is an external or made electromagnet integral with the switch. 6. The switch according to claim 5, characterized in that the electromagnet is made in the form of a flat or multilayer spiral deposited around a MIS structure (or MIS structures). 7. The switch according to claim 6, characterized in that the switch comprises a layer of magnetically soft material located either inside the spiral, or under the spiral, or above the spiral. 8. The switch according to claim 7, characterized in that the membrane or layer of soft magnetic material contain structural elements that specify the distance of their maximum convergence. 9. The switch according to claim 1, characterized in that the elastic elements are made integral with the membrane of the same material or of a different material, wavy or arched diverging in the direction from the membrane and coated on one or both sides with a coating or coatings of materials that provide internal stresses at the interface: tensile - on the convex sides, tensile - on the concave.

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