Bias Decoupled Phase Change RF Switch

Abstract

The present invention relates to a bias decoupling phase change radio frequency switch. It includes a heating element and a dielectric barrier layer stacked from bottom to top, and an electrode assembly and a phase change assembly are arranged on the upper surface of the dielectric barrier layer; the electrode assembly includes a ground electrode, a radio frequency electrode and a bias electrode; wherein, there are two radio frequency electrodes, symmetrically arranged on both sides of the phase change assembly; there are two bias electrodes, symmetrically arranged on the other two sides of the phase change assembly, and are connected to the heating element respectively; the ground electrode contacts one of the bias electrodes, and is isolated from the other bias electrode and the two radio frequency electrodes; the phase change assembly includes more than two phase change elements; each phase change element is arranged side by side and is located above the heating element; the two radio frequency electrodes are connected to the phase change element through a lap joint, and form more than two parallel phase change channels with the phase change element. The present invention can effectively reduce the influence of coupling capacitance on high-frequency radio frequency performance in the phase change radio frequency switch, reduce radio frequency insertion loss, and improve the high-frequency isolation of the switch.

Description

Technical Field

[0001] The invention relates to the technical field of microwave switch devices, and in particular to a bias decoupling phase change radio frequency switch. Background Art

[0002] As a reconfigurable front-end component used to control the on and off of microwave signals in wireless communication systems, RF switches are widely used in major fields such as radar systems and satellite communications. Currently, the more mature RF switches on the market are mainly divided into three categories: PIN diodes, field effect transistors FET, and micro-electromechanical systems. As a semiconductor switch, PIN diodes have advantages such as fast switching speed and high breakdown voltage, but the bias current provided to maintain its on state will produce large power loss. The advantages of FET are simple manufacturing process, low power consumption, easy integration, and high power handling capability, but its on-resistance is large, insertion loss is high, and breakdown voltage is small. MEMS can achieve extremely high isolation and linearity, but its disadvantages are large size, high driving voltage, complex manufacturing process, poor reliability, and low power capacity. In order to better meet the demand for reconfigurable switches in the RF front end, RF switch technology based on phase change materials has emerged. This switch has RF performance comparable to MEMS, and exhibits advantages such as high on-off resistance ratio, miniaturization, easy integration, and zero static power consumption.

[0003] However, affected by the transmission line structure and parasitic capacitance and inductance, the isolation of the phase change RF switch will gradually deteriorate at high frequencies. With the continuous development of modern wireless communication technologies such as 5G and 6G, the demand for high-isolation communication configurations in the RF front end is increasing, and people's expectations for wideband wireless communication systems are also increasing, which puts more stringent requirements on phase change RF switches. In particular, in millimeter wave communications, the isolation between signals is crucial to reducing interference and improving communication quality. In satellite communication systems, polarization isolation is an essential item in antenna network access testing. If the polarization isolation is unqualified, signal loss and leakage may occur. Summary of the invention

[0004] Based on this, it is necessary to provide a bias-decoupled phase-change RF switch that can improve the high-frequency isolation of the phase-change RF switch in order to address the above technical problems.

[0005] A bias decoupling phase change radio frequency switch comprises a heating element and a dielectric barrier layer stacked from bottom to top, wherein an electrode assembly and a phase change assembly are arranged on the upper surface of the dielectric barrier layer;

[0006] The electrode assembly includes a ground electrode, a radio frequency electrode and a bias electrode; wherein there are two radio frequency electrodes, which are symmetrically arranged on both sides of the phase change assembly; there are two bias electrodes, which are symmetrically arranged on the other two sides of the phase change assembly and are respectively connected to the heating element; the ground electrode is in contact with one of the bias electrodes and isolated from the other bias electrode and the two radio frequency electrodes;

[0007] The phase change assembly includes more than two phase change elements; each of the phase change elements is arranged side by side and is located above the heating element;

[0008] The two radio frequency electrodes are connected to the phase change element through a bridge piece, and form more than two parallel phase change channels with the phase change element.

[0009] In one embodiment, the heating element is an elongated structure; two radio frequency electrodes are arranged along the width direction of the heating element; and two bias electrodes are arranged along the length direction of the heating element.

[0010] In one of the embodiments, in the length direction of the heating element, two bias electrodes are located above two ends of the heating element, and the phase change component is located above the middle part of the heating element.

[0011] In one of the embodiments, conductive holes are respectively opened at the covering positions of the two bias electrodes on the dielectric barrier layer, and the bias electrodes are connected to the heating element through the conductive holes.

[0012] In one embodiment, the number of the overlapping elements disposed on each of the radio frequency electrodes is equal to the number of the phase change elements.

[0013] In one embodiment, the phase change elements are arranged side by side at equal intervals.

[0014] In one embodiment, the width of the middle portion of the heating element is greater than or equal to the length of the phase change channel.

[0015] In one embodiment, the length of the middle portion of the heating element is designed according to the number of the phase change channels, and the calculation expression is:

[0016] ;

[0017] In the formula, Indicates the middle length of the heating element; Indicates the number of phase change channels; represents the width of the phase change channel; Represents the distance between adjacent phase change channels.

[0018] In one embodiment, it further includes a substrate, a substrate isolation layer and a passivation layer; the substrate is located below the substrate isolation layer, the heating element is located above the substrate isolation layer, and the passivation layer covers the phase change component.

[0019] In one of the embodiments, the thickness of the substrate is 500um~600um; or the thickness of the substrate isolation layer is 50nm~200nm; or the thickness of the heating element is 80nm~120nm; or the thickness of the dielectric barrier layer is 100nm~200nm; or the thickness of the phase change element is 70nm~200nm; or the thickness of the electrode assembly is 300nm~600nm; or the thickness of the passivation layer is 100nm~200nm.

[0020] Compared with the prior art, the bias decoupling phase change RF switch provided by the present invention has the following effects:

[0021] 1. By making the ground electrode contact one of the bias electrodes and isolating it from the other bias electrode and the two RF electrodes, the influence of the bias electrode on the RF signal can be effectively reduced, the isolation of the phase change RF switch can be improved, and the overall performance of the switch can be improved.

[0022] 2. By connecting two or more phase change components in parallel to form multiple phase change channels, the on-resistance of the switch can be effectively reduced when the RF signal passes through the phase change material, thereby reducing the RF insertion loss. In addition, multi-channel parallel connection can also provide a certain degree of redundancy. When a phase change component fails, it will not cause the entire switch to fail, thereby improving the reliability of the switch.

[0023] 3. Through the combination of bias electrode and heating element, the phase change component is heated by external current and the temperature of the phase change material is controlled, so that the phase change state of the material can be changed quickly and accurately, thereby controlling the on and off of the RF signal, and the switch trigger is sensitive and the response speed is fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 A cross-sectional view of a bias decoupling phase change radio frequency switch provided in one embodiment;

[0026] Figure 2 A top view of a bias decoupling phase change radio frequency switch provided in one embodiment;

[0027] Figure 3 A partially enlarged schematic diagram of a phase change component provided in one embodiment;

[0028] Figure 4 A schematic diagram of the positions of an electrode assembly and a phase change assembly provided in one embodiment;

[0029] Figure 5 FIG. 1 is a schematic diagram of the size design of a bias decoupling phase change RF switch provided in an embodiment, wherein Figure 5 (a) is a schematic diagram of the size design of the phase change component. Figure 5 (b) is a schematic diagram of the design of the heating element dimensions. Figure 5 (c) Schematic diagram of electrode assembly size design;

[0030] Figure 6 A schematic diagram showing a comparison of isolation curves between a bias decoupling phase-change RF switch of the present invention and a conventional phase-change RF switch provided in an embodiment;

[0031] Figure 7 It is a schematic diagram comparing insertion loss curves of a bias decoupling phase change RF switch of the present invention and a traditional structure phase change RF switch provided in an embodiment.

[0032] Explanation of the accompanying drawings: substrate 1, substrate isolation 2, heating element 3, dielectric barrier layer 4, first grounding electrode 51, second grounding electrode 52, first RF electrode 53, second RF electrode 54, first bias electrode 55, second bias electrode 56, phase change element 57, bridging element 58, phase change channel 6, passivation layer 7.

[0033] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] It can be understood that the technical solutions between the various embodiments of the present invention 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 protection required by the present invention.

[0039] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0040] like Figures 1 to 5 As shown, a bias decoupled phase change RF switch is provided, including a substrate 1, a substrate isolation layer 2, a heating element 3 and a dielectric barrier layer 4 stacked from bottom to top, an electrode assembly and a phase change assembly are arranged on the upper surface of the dielectric barrier layer 4, and a passivation layer 7 is covered above the phase change assembly.

[0041] The electrode assembly includes a ground electrode, a radio frequency electrode and a bias electrode; wherein, there are two radio frequency electrodes, symmetrically arranged on both sides of the phase change assembly; there are two bias electrodes, symmetrically arranged on the other two sides of the phase change assembly, and are respectively connected to the heating element 3; the ground electrode is in contact with one of the bias electrodes, and is isolated from the other bias electrode and the two radio frequency electrodes; the phase change assembly includes more than two phase change elements 57; each phase change element 57 is arranged side by side and located above the heating element 3; the two radio frequency electrodes are connected to the phase change element 57 through a bridge 58, and form more than two parallel phase change channels 6 with the phase change element 57.

[0042] Specifically, the substrate 1 and the substrate isolation layer 2 are both plate-like structures with a certain thickness. The substrate 1 is usually made of semiconductor materials, such as high-resistance Si, sapphire, SiC, SiO2, GaN, GaAs, etc., and the thickness is preferably 500um~600um. The substrate isolation layer 2 is usually made of electrical insulating materials, such as SiO2, SiNx, AIN, Al2O3, etc., and the thickness is preferably 50nm~200nm.

[0043] The heating element 3 is an elongated structure, which may be an elongated rectangle, or a dumbbell shape as shown in this embodiment, or other shapes with a certain length.

[0044] When a dumbbell-shaped heating element 3 is used, its shape is as follows: Figure 5 As shown in (b), the larger cross-section parts at both ends of the dumbbell are called the ends, and the smaller cross-section part in the middle is called the middle part. The dimensions of the structure are designed, wherein the width of the ends of the heating element 3 is ,length Designed according to requirements. Width of the middle part of the heating element 3 Greater than or equal to the length of the phase change channel 6 . The length of the middle part of the heating element 3 According to the number of phase change channels 6, the calculation expression is:

[0045] ;

[0046] In the formula, Indicates the middle length of the heating element; Indicates the number of phase change channels; represents the width of the phase change channel; Represents the distance between adjacent phase change channels.

[0047] It can be understood that when the heating element 3 is rectangular, the middle one-third part can be called the middle part, and the two ends of the one-third part can be called the end part; then the width and length of the middle part can be determined according to the above method; and the width of the end part can be determined according to the width of the middle part, and the length of the end part can be designed according to the requirements. When it is other shapes, the method is similar and will not be repeated here.

[0048] The heating element 3 is usually made of metal material, such as W, NiCr, Mo, TiN, TiW, etc., and the thickness is preferably 80nm~120nm.

[0049] The dielectric barrier layer 4 is mainly used for electrical isolation, heat transfer and uniform electric field distribution. It is also a plate-like structure with a certain thickness and is usually made of dielectric materials such as AIN, SiNx, SiO2, etc. The thickness is preferably 100nm~200nm.

[0050] An electrode assembly and a phase change assembly are arranged on the dielectric barrier layer 4, wherein the electrode assembly includes a first ground electrode 51, a second ground electrode 52, a first RF electrode 53, a second RF electrode 54, a first bias electrode 55 and a second bias electrode 56; and the phase change assembly includes more than two phase change elements 57. Figure 5 (c), Width of two RF electrodes , the distance between the two RF electrodes and the first ground electrode 51 and the second ground electrode 52 The design is based on the impedance matching required, which is generally 50Ω impedance matching; the electrode length of the two RF electrodes overlapping the phase change channel 6 is Make adjustments based on actual conditions.

[0051] See also Figure 2 On the dielectric barrier layer 4, the phase change component is arranged in the middle, and the first bias electrode 55 and the second bias electrode 56 are symmetrically arranged on the left and right sides thereof, and the first RF electrode 53 and the second RF electrode 54 are symmetrically arranged on the upper and lower sides thereof. The first RF electrode 53, the second RF electrode 54, the first bias electrode 55 and the second bias electrode 56 are cone-shaped structures, and their cone tips are all facing the phase change component.

[0052] A first grounding electrode 51 is disposed on the left side of the first bias electrode 55, and the first grounding electrode 51 is in contact with the first bias electrode 55. A second grounding electrode 52 is disposed on the right side of the second bias electrode 56, and the second grounding electrode 52 is a groove-shaped structure, with its groove facing the second bias electrode 56 and having a certain interval with the second bias electrode 56; similarly, the first RF electrode 53 and the second RF electrode 54 are respectively spaced apart from the first grounding electrode 51 and the second grounding electrode 52, so that the two grounding electrodes are respectively isolated from the first RF electrode 53, the second RF electrode 54, and the second bias electrode 56.

[0053] On the dielectric barrier layer 4, conductive holes are respectively provided at the covering positions of the first bias electrode 55 and the second bias electrode 56. The conductive holes are through holes that vertically penetrate the dielectric barrier layer 4. The size and dimensions of the conductive holes are preferably such that the end of the heating element 3 can be completely exposed. For example, in this embodiment, the width of the end of the heating element 3 is , long , then the width of the conductive hole cannot be less than , the length cannot be less than When the first bias electrode 55 and the second bias electrode 56 cover the conductive hole, they are connected to the heater 3 through the conductive hole, so that voltage or current pulses can be applied to the two ends of the heater 3 through the two bias electrodes.

[0054] The specific number of phase change elements 57 is determined according to the requirements. Figure 3, is a partial enlarged schematic diagram of the phase change component provided in this embodiment. It can be seen that on the dielectric barrier layer 4, three phase change elements 57 are arranged side by side, and there is a certain interval between adjacent phase change elements 57. The interval can be equidistant or unequal, and it is designed according to the specific situation. Preferably, in this embodiment, each phase change element 57 is arranged side by side with equal intervals.

[0055] The phase change element 57 is in the shape of a long strip, and its two ends are respectively connected to the bridge pieces 58 of the first RF electrode 53 and the second RF electrode 54, so as to form three parallel phase change channels 6 in the middle of the three phase change elements 57. The two bias electrodes and the heating element 3 form a separate heating path to heat the phase change element 57, so as to control the resistance state of the phase change element 57, thereby controlling the conduction and disconnection of the phase change channel 6, and thus realizing the function of the phase change switch. The phase change element 57 is usually made of sulfur compounds, such as GeTe, Sb 2 Te 3 ,Ge 2 Sb 2 Te 5 The thickness is preferably 70nm~200nm.

[0056] Phase change component size design reference Figure 5 (a), which mainly designs the phase change channel 6. The length of each phase change channel 6 is ,Width , and the distance between adjacent phase change channels 6 Can be designed according to actual situation.

[0057] The first RF electrode 53 and the second RF electrode 54 are both provided with a bridge piece 58, and the number of bridge pieces 58 provided on each RF electrode is equal to the number of phase change elements 57. The shape of the bridge piece 58 is designed according to the actual situation, as long as the RF electrode can be connected to the phase change element 57. In this embodiment, the bridge piece 58 is in the shape of a long strip, one end of which is connected to the end of the RF electrode and is in the same horizontal plane; the other end extends toward the phase change element 57 and is raised one step so that the lower surface of the bridge piece 58 contacts the upper surface of the phase change element 57. The contact length between the bridge piece 58 and the phase change element 57 is the electrode length The first ground electrode 51, the second ground electrode 52, the first RF electrode 53, the second RF electrode 54, the first bias electrode 55, and the second bias electrode 56 are usually made of metal materials, such as Au, Pt, Cu, etc., and the thickness is preferably 300nm~600nm.

[0058] See also Figure 4, showing the relative position of the phase change element 57 and the heating element 3. It is worth noting that the dielectric barrier layer 4 is hidden for the sake of clarity. It can be seen that the first RF electrode 53 and the second RF electrode 54 are arranged along the width direction of the heating element 3; the first bias electrode 55 and the second bias electrode 56 are arranged along the length direction of the heating element 3. In the length direction of the heating element 3, the first bias electrode 55 and the second bias electrode 56 are respectively located above the two ends of the heating element 3, and the phase change element 57 arranged side by side and spaced apart is located above the middle part of the heating element 3.

[0059] The passivation layer 7 may completely cover the phase change element 57, or may only cover the phase change channel 6, to isolate the phase change element 57 from the outside. The passivation layer 7 is usually made of an electrically insulating material, such as SiNx, SiO 2 , AIN, etc., and the thickness is preferably 100nm~200nm.

[0060] When working, the radio frequency signal is transmitted through the coplanar waveguide transmission line structure; the first bias electrode 55 and the second bias electrode 56 form a separate heating path with the heating element 3 to heat the phase change element 57, and the resistance state of each phase change element 57 is regulated by applying voltage or current pulses to the two bias electrodes, and the signal is turned on and off according to the resistance state of each phase change element 57, thereby realizing the function of the phase change switch. The present invention realizes a bias decoupling structure through the contact between the first ground electrode 51 and the first bias electrode 55, and multiple phase change channels 6 in parallel, which can effectively reduce the influence of the coupling capacitor in the phase change radio frequency switch on the high-frequency radio frequency performance, reduce the radio frequency insertion loss, and improve the high-frequency isolation of the switch.

[0061] See also Figure 6 , which is a schematic diagram comparing the isolation curves of the bias-decoupled phase-change RF switch of the present invention and the phase-change RF switch of the traditional structure; it can be seen that the isolation of the bias-decoupled phase-change RF switch of the present invention in the frequency band of 0GHz~70GHz is greater than 32dB, and the isolation at 70GHz is improved by nearly 20dB compared with the traditional structure, indicating that the bias-decoupled phase-change RF switch of the present invention has good high-frequency isolation performance.

[0062] Figure 7 This is a schematic diagram comparing the insertion loss curves of the bias-decoupled phase-change RF switch of the present invention and the phase-change RF switch of the traditional structure; it can be seen that the insertion loss of the bias-decoupled phase-change RF switch of the present invention in the 0GHz~70GHz frequency band is not much different from that of the traditional structure, indicating that the bias-decoupled phase-change RF switch of the present invention can greatly improve the high-frequency isolation performance of the phase change switch while ensuring that the insertion loss is not much different from that of the traditional structure.

[0063] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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.

[0064] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A bias decoupling phase change radio frequency switch, characterized in that: It comprises a heating element and a dielectric barrier layer stacked from bottom to top, and an electrode assembly and a phase change assembly are arranged on the upper surface of the dielectric barrier layer; The electrode assembly includes a ground electrode, a radio frequency electrode and a bias electrode; wherein there are two radio frequency electrodes, which are symmetrically arranged on both sides of the phase change assembly; there are two bias electrodes, which are symmetrically arranged on the other two sides of the phase change assembly and are respectively connected to the heating element; the ground electrode is in contact with one of the bias electrodes and isolated from the other bias electrode and the two radio frequency electrodes; The phase change assembly includes more than two phase change elements; each of the phase change elements is arranged side by side and is located above the heating element; The two radio frequency electrodes are connected to the phase change element through a bridge piece, and form more than two parallel phase change channels with the phase change element.

2. The bias decoupling phase change RF switch according to claim 1, characterized in that: The heating element is an elongated structure; Two radio frequency electrodes are arranged along the width direction of the heating element; and two bias electrodes are arranged along the length direction of the heating element.

3. The bias decoupling phase change RF switch according to claim 2, characterized in that: In the length direction of the heating element, two bias electrodes are located above the two ends of the heating element, and the phase change component is located above the middle part of the heating element.

4. The bias decoupling phase change RF switch according to claim 3, characterized in that: On the dielectric barrier layer, conductive holes are respectively opened at the covering positions of the two bias electrodes, and the bias electrodes are connected to the heating element through the conductive holes.

5. The bias decoupling phase change RF switch according to any one of claims 1 to 4, characterized in that: The number of the overlapping parts arranged on each of the radio frequency electrodes is equal to the number of the phase change parts.

6. The bias decoupling phase change radio frequency switch according to claim 5, characterized in that: The phase change elements are arranged side by side at equal intervals.

7. The bias decoupling phase change RF switch according to claim 5, characterized in that: The width of the middle portion of the heating element is greater than or equal to the length of the phase change channel.

8. The bias decoupling phase change RF switch according to claim 5, characterized in that: The length of the middle portion of the heating element is designed according to the number of the phase change channels, and the calculation expression is: ； In the formula, Indicates the middle length of the heating element; Indicates the number of phase change channels; represents the width of the phase change channel; Represents the distance between adjacent phase change channels.

9. The bias decoupling phase change radio frequency switch according to claim 1, characterized in that: It also includes a substrate, a substrate isolation layer and a passivation layer; The substrate is located below the substrate isolation layer, the heating element is located above the substrate isolation layer, and the passivation layer covers the phase change component.

10. The bias decoupling phase change radio frequency switch according to claim 9, characterized in that: The thickness of the substrate is 500um~600um; or the thickness of the substrate isolation layer is 50nm~200nm; or the thickness of the heating element is 80nm~120nm; or the thickness of the dielectric barrier layer is 100nm~200nm; or the thickness of the phase change element is 70nm~200nm; or the thickness of the electrode assembly is 300nm~600nm; or the thickness of the passivation layer is 100nm~200nm.

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