Ferroelectric film phase shifter working in K wave band

Abstract

The utility model provides a ferroelectric film phase shifter working in a K wave band. The ferroelectric film phase shifter comprises a first top layer transmission line electrode, a second top layer ground wire electrode, an HFO2 ferroelectric film layer, a third top layer interdigital capacitor electrode and a substrate layer. The HFO2 ferroelectric thin film layer is located on the substrate layer, second top layer ground wire electrodes are arranged on the two sides of the HFO2 ferroelectric thin film layer respectively, and a first top layer transmission line electrode is arranged between the two second top layer ground wire electrodes on the HFO2 ferroelectric thin film layer. Third top-layer interdigital capacitor electrodes are arranged between the two sides of the first top-layer transmission line electrode and the adjacent second top-layer ground wire electrode. According to the phase shifter, the HFO2 ferroelectric thin film is adopted, the tuning rate of the thin film is high, the thickness is smaller, the working frequency of the phase shifter ranges from 19 GHz to 22 GHz, when the dielectric constant of the HFO2 thin film is changed from 30 to 60, the phase shifter can achieve the 80-degree phase shifting effect at the 22 GHz frequency point, and the phase shifter has good prospects and is economical and practical in millimeter wave radars and phased arrays.

Description

Technical Field

[0001] The utility model belongs to the technical field of phase shifters, and in particular relates to a ferroelectric thin film phase shifter operating in a K band. Background Art

[0002] Phase shifters are the core components of phased array technology. Commonly used phase shifters include ferrite phase shifters, semiconductor PIN diode phase shifters, micro-electromechanical systems (MEMS) phase shifters and ferroelectric phase shifters. Ferrite phase shifters are complex in design and too large in size. PIN diode phase shifters consume too much power in the microwave frequency band. MEMS phase shifters have slow switching speeds and low phase sensitivity. High-precision, low-loss phase shifters can significantly improve the performance of phased arrays. Ferroelectric phase shifters mainly use the relationship between the dielectric constant of ferroelectric materials and the external electric field. Changes in the external electric field lead to changes in the dielectric constant of the medium. Changes in the dielectric constant will change the phase velocity of the microwave signal, thereby achieving the purpose of phase shifting.

[0003] Ferroelectric materials have a large dielectric constant, and under different voltage controls, the dielectric constant has a wide adjustment range. Devices made from them have excellent high-frequency characteristics, a wide frequency adjustment range, high power capacity, fast control speed, and low insertion loss, and are therefore very popular.

[0004] HFO2 is a ferroelectric material. Compared with traditional BST ferroelectric films, HFO2 can be made of nanometer-level thickness and has low power loss, which makes the phase shifter made of HFO2 ferroelectric material have a more compact structure.

[0005] The CPW type ferroelectric thin film phase shifter adds a ferroelectric thin film between the transmission line and the substrate, and adds a distributed interdigital capacitor structure between the signal line and the ground. When the microwave signal passes through the phase shifter, the electric field between the transmission line and the dielectric substrate is changed by the bias voltage, so that the dielectric constant of the ferroelectric thin film changes, thereby changing the phase velocity of the microwave signal and shifting the phase of the microwave signal.

[0006] Based on this, a ferroelectric thin film phase shifter working in the K band is proposed. Utility Model Content

[0007] The technical problem to be solved by the present invention is to provide a ferroelectric thin film phase shifter working in the K band in view of the deficiencies of the above-mentioned prior art, so as to solve the problems raised in the above-mentioned background technology.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is: a ferroelectric thin film phase shifter working in the K band, comprising a first top layer transmission line electrode, a second top layer ground line electrode, an HFO2 ferroelectric thin film layer, a third top layer interdigital capacitor electrode and a substrate layer;

[0009] The HFO2 ferroelectric film layer is located on the substrate layer, and second top-layer ground electrodes are respectively arranged on both sides of the HFO2 ferroelectric film layer. A first top-layer transmission line electrode is arranged between two second top-layer ground electrodes on the HFO2 ferroelectric film layer, and third top-layer interdigital capacitor electrodes are arranged between the two sides of the first top-layer transmission line electrode and the adjacent second top-layer ground electrodes.

[0010] As a further illustration of the present invention, the thickness of the HFO2 ferroelectric thin film layer h2 is 15 nm.

[0011] As a further illustration of the present invention, the substrate layer is made of high-resistance silicon with a dielectric constant of 11.9, and the thickness of the substrate layer is 300 um.

[0012] As a further illustration of the present invention, the interdigital width w1 of the third top interdigital capacitor electrode is 0.01 mm, the interdigital gap w2 is 0.02 mm, and the interdigital length l is 0.32 mm.

[0013] As a further description of the present invention, the thickness of the first top-layer transmission line electrode and the second top-layer ground line electrode are the same, and the thickness h3 is 6 um.

[0014] Compared with the prior art, the utility model has the following advantages:

[0015] The phase shifter in the utility model adopts HFO2 ferroelectric film, which has a high tuning rate and a thinner thickness. The required bias voltage is lower than that of the traditional BST ferroelectric film phase shifter. The entire phase shifter has a compact structure. The operating frequency of the phase shifter is 19GHz-22GHz. When the dielectric constant of the HFO2 film changes from 30 to 60, the phase shifter can achieve an 80-degree phase shift effect at a frequency of 22GHz. The phase shifter has good prospects in millimeter-wave radars and phased arrays and is economical and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a top view of the overall structure of the utility model;

[0017] Figure 2 It is a side view of the overall structure of the utility model;

[0018] Figure 3 This is a schematic diagram of the third top-layer interdigital capacitor electrode of the present invention;

[0019] Figure 4 This is a return loss diagram of the utility model under different dielectric constants;

[0020] Figure 5 It is a phase curve diagram of the utility model under different dielectric constants.

[0021] Description of reference numerals:

[0022] 1-first top layer transmission line electrode; 2-second top layer ground line electrode; 3-HFO2 ferroelectric thin film layer; 4-third top layer interdigital capacitor electrode; 5-substrate layer. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] like Figure 1-3 As shown, the utility model provides a technical solution: a ferroelectric thin film phase shifter working in the K band, comprising a first top layer transmission line electrode 1, a second top layer ground line electrode 2, an HFO2 ferroelectric thin film layer 3, a third top layer interdigital capacitor electrode 4 and a substrate layer 5;

[0025] The HFO2 ferroelectric thin film layer 3 is located on the substrate layer 5, and second top-level ground electrodes 2 are respectively arranged on both sides of the HFO2 ferroelectric thin film layer 3. A first top-level transmission line electrode 1 is arranged between two second top-level ground electrodes 2 on the HFO2 ferroelectric thin film layer 3, and third top-level interdigital capacitor electrodes 4 are arranged between the two sides of the first top-level transmission line electrode 1 and the adjacent second top-level ground electrodes 2.

[0026] The thickness h2 of the HFO2 ferroelectric thin film layer 3 is 15 nm.

[0027] The substrate layer 1 is made of high-resistance silicon with a dielectric constant of 11.9, and the thickness of the substrate layer 1 is 300 um.

[0028] The interdigital width w1 of the third top interdigital capacitor electrode 4 is 0.01 mm, the interdigital gap w2 is 0.02 mm, and the interdigital length l is 0.32 mm.

[0029] The first top-layer transmission line electrode 1 and the second top-layer ground line electrode 2 have the same thickness, and the thickness h3 is 6 um.

[0030] The process of the ferroelectric thin film phase shifter in this embodiment is as follows:

[0031] S1, select high-resistance silicon as substrate layer 1, with a thickness of 300um;

[0032] S2. The HFO2 ferroelectric thin film layer 3 is prepared on the substrate layer 1. The preparation method may be a chemical solution method, an atomic layer deposition method, a magnetron sputtering method, or the like.

[0033] S3, completing the preparation of the first top-layer transmission line electrode 1, the second top-layer ground line electrode 2 and the third top-layer interdigital capacitor electrode 4 on the HFO2 ferroelectric film.

[0034] A stripping process can be used, and the specific steps are: coating, pre-baking, pre-explosion, post-baking, post-explosion, development, electrode, and stripping.

[0035] The principle of the ferroelectric thin film phase shifter is as follows:

[0036] When a microwave signal is input from one port, a DC bias is added between the signal line and the ground. At this time, an electric field is formed between the signal line and the ground. Due to the characteristics of the ferroelectric film, the dielectric constant of the ferroelectric film changes, thereby changing the phase velocity of the electromagnetic wave and causing a phase shift.

[0037] The advantage of using a coplanar waveguide structure in the phase shifter is that when a bias is applied, the electric field is from the signal line to the ground, and the propagation direction of the electric field is not perpendicular to the ferroelectric film, which can prevent the electric field from directly breaking through the film. The introduction of an interdigital capacitor structure between the signal line and the ground makes the phase velocity more sensitive to changes in the dielectric constant. The phase velocity has a direct relationship with the phase of the signal, which also allows the phase to change over a wider range.

[0038] like Figure 4 As shown, the phase shifter is simulated. When a DC bias is applied to the signal line, the dielectric constant of the HFO2 film changes, ranging from 30 to 60.

[0039] By selecting three different dielectric constants within this range for simulation, we can see that S11 can basically reach below -10dB in the 19GHz-22GHz frequency band, that is, matching can be achieved.

[0040] like Figure 5 As shown, when the dielectric constant changes due to the applied bias, it can be seen that the phase shift effect is positively correlated with the change in the dielectric constant, and as the frequency increases, the phase shift also increases. When it reaches 22 GHz, the maximum phase shift reaches 80 degrees.

[0041] The phase shifter has a compact size and is easy to integrate. In addition, the bias voltage applied to change the dielectric constant of HFO2 from 30 to 60 only requires a few volts, making the film less likely to be broken down. The phase shifter has good prospects in millimeter-wave radar and phased array.

[0042] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ferroelectric thin film phase shifter operating in the K band, characterized in that: It comprises a first top-layer transmission line electrode (1), a second top-layer ground line electrode (2), an HFO2 ferroelectric thin film layer (3), a third top-layer interdigital capacitor electrode (4) and a substrate layer (5); The HFO2 ferroelectric thin film layer (3) is located on a substrate layer (5); second top-layer ground electrodes (2) are respectively arranged on both sides of the HFO2 ferroelectric thin film layer (3); a first top-layer transmission line electrode (1) is arranged between two second top-layer ground electrodes (2) on the HFO2 ferroelectric thin film layer (3); and third top-layer interdigital capacitor electrodes (4) are arranged between the two sides of the first top-layer transmission line electrode (1) and the adjacent second top-layer ground electrodes (2).

2. A ferroelectric thin film phase shifter operating in the K band according to claim 1, characterized in that: The thickness h2 of the HFO2 ferroelectric thin film layer (3) is 15 nm.

3. The ferroelectric thin film phase shifter operating in the K band according to claim 1, characterized in that: The substrate layer (5) is made of high-resistance silicon with a dielectric constant of 11.9, and the thickness of the substrate layer (5) is 300 um.

4. The ferroelectric thin film phase shifter operating in the K band according to claim 1, characterized in that: The interdigital width w1 of the third top interdigital capacitor electrode (4) is 0.01 mm, the interdigital gap w2 is 0.02 mm, and the interdigital length l is 0.32 mm.

5. The ferroelectric thin film phase shifter operating in the K band according to claim 1, characterized in that: The first top-layer transmission line electrode (1) and the second top-layer ground line electrode (2) have the same thickness, and the thickness h3 is 6 um.

Images