Inspection method for radio wave reflection device

Abstract

This method for inspecting a radio wave reflection device is a method for inspecting a radio wave reflection device having a plurality of reflection elements arranged in a row direction and a column direction, each of the plurality of reflection elements having a patch electrode, a common electrode overlapping the rear surface side of the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode, a voltage (V1) is applied between each of the plurality of patch electrodes and the common electrode, and the quality of the reflective element is determined on the basis of a change in a frame-shaped region appearing on the outer periphery of the plurality of patch electrodes in plan view when the voltage is applied between the plurality of patch electrodes and the common electrode.

Description

Technical Field

[0001] The present invention relates to a method for inspecting an electric wave reflection device. Background Art

[0002] In a phased array antenna device, the amplitude and phase of the high-frequency signal applied to each of the plurality of antenna elements arranged in a planar shape are adjusted to control the directivity while the antenna is fixed. A phased array antenna device requires a phase shifter. A phased array antenna device using a phase shifter is disclosed, which utilizes the change in dielectric constant based on the orientation state of liquid crystal (for example, see Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 11-103201

[0006] Patent Document 2: Japanese Patent Application No. 2019-530387 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in radio wave reflection devices using liquid crystal, there is a problem that there is no method for observing a reflection element that cannot perform desired radio wave control to determine whether it is good or not.

[0009] Furthermore, unlike display devices that use transparent electrodes for pixel electrodes, radio wave reflection devices often use metal that blocks light for patch electrodes, so there is a problem that the area in which the inside of the radio wave reflection device can be directly observed without destruction is limited.

[0010] In view of such problems, one purpose of one embodiment of the present invention is to provide a method for inspecting whether a reflective element of a radio wave reflection device is good or not. Another purpose is to provide a method for inspecting whether a desired voltage is applied to a liquid crystal layer of a reflective element of a radio wave reflection device.

[0011] Means for solving problems

[0012] An embodiment of the present invention involves an inspection method for an electric wave reflection device, which is an inspection method for an electric wave reflection device having a plurality of reflection elements arranged in row and column directions, wherein the plurality of reflection elements respectively have a patch electrode, a common electrode overlapping the back side of the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode, a voltage V1 is respectively applied between the plurality of patch electrodes and the above-mentioned common electrode, and the quality of the reflection element is determined based on changes in a frame-shaped area that appears on the periphery of the plurality of patch electrodes when viewed from above when the voltage is applied between the plurality of patch electrodes and the above-mentioned common electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [ Figure 1A ] shows a top view of a reflecting element used in a radio wave reflecting device according to one embodiment of the present invention.

[0014] [ Figure 1B ] is a cross-sectional view of a reflecting element used in a radio wave reflecting device according to one embodiment of the present invention.

[0015] [ Figure 2A ] shows the state of the reflection element used in the radio wave reflection device involved in one embodiment of the present invention when it is in operation, and shows the state where no voltage is applied between the patch electrode and the common electrode.

[0016] [ Figure 2B ] shows the state of the reflection element used in the radio wave reflection device involved in one embodiment of the present invention when it is in operation, and shows the state of voltage applied between the patch electrode and the common electrode.

[0017] [ Figure 3 ] shows the structure of an electric wave reflecting device involved in one embodiment of the present invention.

[0018] [ Figure 4 ] schematically illustrates a situation in which the traveling direction of a reflected wave is changed by an electric wave reflecting device according to one embodiment of the present invention.

[0019] [ Figure 5 ] shows the structure of an electric wave reflecting device involved in one embodiment of the present invention.

[0020] [ Figure 6 ] shows a cross-sectional view of a reflecting element in a radio wave reflecting device according to one embodiment of the present invention.

[0021] [ Figure 7 ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0022] [ Fig. 8A ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0023] [ Figure 8B ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0024] [ Figure 8C ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0025] [ Fig. 9A ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0026] [ Fig. 9B ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0027] [ Fig. 9C ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0028] [ Fig. 10A ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0029] [ Fig. 10B ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0030] [ Fig. 10C ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0031] [ Fig.11A ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0032] [ Fig. 11B ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0033] [ Fig. 11C ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0034] [ Fig. 12A ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0035] [ Fig. 12B ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0036] [ Fig. 12C ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0037] [ Fig.13A ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0038] [ Fig. 13B ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0039] [ Fig. 13C ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0040] [ Fig.14A ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0041] [ Fig. 14B ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0042] [ Fig. 14C ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention.

[0043] [ Fig.15A ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0044] [ Fig. 15B ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0045] [ Fig. 15C ] is a cross-sectional view for illustrating a method for inspecting a radio wave reflection device according to an embodiment of the present invention.

[0046] [ Fig.16 ] is a top view for illustrating a method for inspecting a radio wave reflection device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0047] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings and the like. However, the present invention can be implemented in a variety of different ways and is not limited to the description of the embodiments illustrated below for explanation. In order to make the description clearer, the width, thickness, shape, etc. of each part are sometimes schematically indicated in the accompanying drawings compared with the actual method, but this is only an example and does not limit the explanation of the present invention. In addition, in this specification and the drawings, the same reference numerals (or reference numerals such as a, b are marked after the numbers) are used for the elements identical to the elements described above with respect to the figures that have appeared, and sometimes the detailed description is appropriately omitted. In addition, the texts marked as "the first" and "the second" for each element are convenient identifiers used to distinguish each element, and do not have more meanings unless otherwise specified.

[0048] In this specification, when a component or region is located "above (or below)" other components or regions, unless otherwise specified, it includes not only the case where it is located immediately above (or immediately below) other components or regions, but also the case where it is located above (or below) other components or regions, that is, it also includes the case where other components are included in the middle above (or below) other components or regions.

[0049] 1. Reflective element

[0050] Figure 1A and Figure 1B A reflecting element 102 used in a radio wave reflecting device 100 according to an embodiment of the present invention is shown. Figure 1A 1 is a top view of the reflective element 102 as viewed from above (the side where the radio wave is incident), Figure 1B It is a cross-sectional view between A1-A2 shown in a top view.

[0051] like Figure 1A and Figure 1BAs shown, the reflective element 102 includes a dielectric substrate 104, an opposing substrate 106, a patch electrode 108, a common electrode 110, a first orientation film 112a, a second orientation film 112b, and a liquid crystal layer 114. In the reflective element 102, the dielectric substrate 104 can also be regarded as a dielectric layer as a structure constituting one layer. The patch electrode 108 is provided on the dielectric substrate (dielectric layer) 104, and the common electrode 110 is provided on the opposing substrate 106. The common electrode 110 is arranged on the back side of the patch electrode 108. The first orientation film 112a is provided on the dielectric substrate (dielectric layer) 104 in a manner covering the patch electrode 108, and the second orientation film 112b is provided on the opposing substrate 106 in a manner covering the common electrode 110. The patch electrode 108 and the common electrode 110 are arranged in an opposing manner, and the liquid crystal layer 114 is provided between the two. The first orientation film 112 a is interposed between the patch electrode 108 and the liquid crystal layer 114 , and the second orientation film 112 b is interposed between the common electrode 110 and the liquid crystal layer 114 .

[0052] The patch electrode 108 preferably has a shape that is symmetrical with respect to the vertically polarized wave and the horizontally polarized wave of the incident radio wave, and has a square or circular shape in a plan view. Figure 1A Indicates a case where the patch electrode 108 is square when viewed from above. The shape of the common electrode 110 is not particularly limited, and has a shape that extends over substantially the entire surface of the opposing substrate 106 in a manner having a larger area than the patch electrode 108. The material forming the patch electrode 108 and the common electrode 110 is not limited, and is formed using a conductive metal or metal oxide. A first wiring 118 may also be provided on the dielectric substrate (dielectric layer) 104. The first wiring 118 is connected to the patch electrode 108. The first wiring 118 can be used when a control signal is applied to the patch electrode 108. In addition, when a plurality of reflective elements are arranged, the first wiring 118 can be used when connecting a patch electrode to a patch electrode adjacent thereto.

[0053] Although in Figure 1A and Figure 1BAlthough not shown in the figure, the dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together by a sealing material. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are arranged opposite to each other with a gap therebetween, and the liquid crystal layer 114 is arranged in the area surrounded by the sealing material. The liquid crystal layer 114 is arranged in a manner to fill the gap between the dielectric substrate (dielectric layer) 104 and the counter substrate 106. The interval between the dielectric substrate (dielectric layer) 104 and the counter substrate 106 is 20 to 100 μm, for example, 50 μm. The patch electrode 108, the common electrode 110, the first orientation film 112a, and the second orientation film 112b are arranged between the dielectric substrate (dielectric layer) 104 and the counter substrate 106, so to be precise, the interval between the first orientation film 112a and the second orientation film 112b respectively arranged on the dielectric substrate 104 and the counter substrate 106 becomes the thickness of the liquid crystal layer 114. It should be noted that although Figure 1B Although not shown in the figure, a spacer for maintaining a constant distance between the dielectric substrate (dielectric layer) 104 and the counter substrate 106 may be provided.

[0054] A control signal for controlling the orientation of the liquid crystal molecules of the liquid crystal layer 114 is applied to the patch electrode 108. The control signal is a DC voltage signal, or a polarity reversal signal in which a positive DC voltage and a negative DC voltage are alternately reversed. The common electrode 110 is grounded or a voltage of an intermediate level of the polarity reversal signal is applied. By applying a control signal to the patch electrode 108, the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114 changes. A liquid crystal material having dielectric anisotropy is used in the liquid crystal layer 114. For example, as the liquid crystal layer 114, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal can be used. The dielectric constant of the liquid crystal layer 114 having dielectric anisotropy changes according to the change in the orientation state of the liquid crystal molecules. The reflective element 102 can change the dielectric constant of the liquid crystal layer 114 by applying a control signal to the patch electrode 108, thereby being able to delay the phase of the reflected wave when reflecting the radio wave.

[0055] The frequency band of the radio wave reflected by the reflective element 102 is a very short wave (VHF: Very High Frequency) band, an ultra-short wave (UHF: Ultra-High Frequency) band, a microwave (SHF: Super High Frequency) band, a submillimeter wave (THF: Tremendously high frequency), and a millimeter wave (EHF: Extra High Frequency) band. The liquid crystal molecules of the liquid crystal layer 114 change their orientation in response to the control signal applied to the patch electrode 108, but hardly follow the frequency of the radio wave irradiated to the patch electrode 108. Therefore, the reflective element 102 can control the phase of the reflected radio wave without being affected by the radio wave.

[0056] Figure 2A This shows a state where no voltage is applied between the patch electrode 108 and the common electrode 110 (referred to as a “first state”). Figure 2A The first and second alignment films 112a and 112b are horizontal alignment films. In the first state, the long axes of the liquid crystal molecules 116 are aligned horizontally with respect to the surfaces of the patch electrode 108 and the common electrode 110 by the first and second alignment films 112a and 112b. Figure 2B The state (referred to as "second state") in which a control signal (voltage signal) is applied to the patch electrode 108 is shown. In the second state, the liquid crystal molecules 116 are acted upon by the electric field so that the long axis is oriented perpendicularly to the surface of the patch electrode 108 and the common electrode 110. The angle at which the long axis of the liquid crystal molecules 116 is oriented may be oriented in a direction intermediate between the horizontal direction and the vertical direction depending on the magnitude of the control signal applied to the patch electrode 108 (the magnitude of the voltage between the counter electrode and the patch electrode).

[0057] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant of the second state becomes larger than that of the first state. In addition, when the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant of the second state becomes smaller than that of the first state. The liquid crystal layer 114 having dielectric anisotropy can also be regarded as a variable dielectric layer. The reflective element 102 can be controlled in a manner that the phase of the reflected wave is delayed (or not delayed) by utilizing the dielectric anisotropy of the liquid crystal layer 114.

[0058] The reflective element 102 is used in a radio wave reflector that reflects radio waves in a predetermined direction. It is preferable that the reflective element 102 does not attenuate the amplitude of the reflected radio waves as much as possible. Figure 1BAs is clear from the structure shown, when the radio wave propagating in the air is reflected by the reflective element 102, the radio wave passes twice through the dielectric substrate (dielectric layer) 104. The dielectric substrate (dielectric layer) 104 is formed of a dielectric material such as glass or resin.

[0059] 2. Radio wave reflection device

[0060] Next, the structure of a radio wave reflection device in which reflection elements are integrated is shown.

[0061] 2-1. Radio wave reflection device A (single-axis reflection control)

[0062] Figure 3 FIG. 1 shows a configuration of a radio wave reflection device 100a according to an embodiment of the present invention. The radio wave reflection device 100 includes a radio wave reflection plate 120. The radio wave reflection plate 120 is composed of a plurality of reflection elements 102. The plurality of reflection elements 102 are arranged in a row direction ( Figure 3 The X-axis direction shown) and the row direction intersecting the column direction ( Figure 3 The reflective element 102 is arranged in a manner such that the patch electrode 108 faces the incident surface of the radio wave. The radio wave reflector 120 is in the shape of a flat plate, and a plurality of patch electrodes 108 are arranged in a matrix on the surface of the flat plate.

[0063] The radio wave reflection device 100a has a structure in which a plurality of reflection elements 102 are integrated on a dielectric substrate (dielectric layer) 104. Figure 3 As shown in FIG. 1 , the radio wave reflection device 100 has the following structure: a dielectric substrate (dielectric layer) 104 on which a plurality of patch electrodes 108 are arranged overlapped with a counter substrate 106 on which a common electrode 110 is provided, and a liquid crystal layer (not shown) is provided between the two substrates. The radio wave reflection plate 120 is formed in the area where the plurality of patch electrodes 108 overlap with the common electrode 110. The cross-sectional structure of the radio wave reflection plate 120 is similar to that of the conventional radio wave reflection plate 120 in terms of each patch electrode 108. Figure 1B The structure of the reflective element 102 shown is the same. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together via a sealant 128 , and a liquid crystal layer (not shown) is provided in a region inside the sealant 128 .

[0064] The dielectric substrate (dielectric layer) 104 has a peripheral region 122 that is extended outward from the opposing substrate 106 in addition to the region opposing the opposing substrate 106. The first drive circuit 124 and the terminal portion 126 are provided in the peripheral region 122. The first drive circuit 124 outputs a control signal to the patch electrode 108. The terminal portion 126 is a region for forming a connection with an external circuit, for example, for connection to a flexible printed circuit substrate not shown. A signal for controlling the first drive circuit 124 is input to the terminal portion 126.

[0065] As described above, on the dielectric substrate (dielectric layer) 104, a plurality of patch electrodes 108 are arranged in the column direction (X-axis direction) and the row direction (Y-axis direction). In addition, a plurality of first wirings 118 extending in the row direction (Y-axis direction) are provided on the dielectric substrate (dielectric layer) 104. Each of the plurality of first wirings 118 is electrically connected to the plurality of patch electrodes 108 arranged in the row direction (Y-axis direction). In other words, the plurality of patch electrodes 108 arranged in the row direction (Y-axis direction) are connected by the first wirings 118. The radio wave reflection plate 120 has a configuration in which a plurality of patch electrode arrays connected by the first wirings 118 are arranged in the column direction (X-axis direction).

[0066] The plurality of first wirings 118 disposed on the radio wave reflection plate 120 extend to the peripheral region 122 and are connected to the first driving circuit 124. The first driving circuit 124 can output control signals of different voltage levels to each of the plurality of first wirings 118. Thus, in the radio wave reflection plate 120, control signals are applied to the plurality of patch electrodes 108 arranged in the column direction (X-axis direction) and the row direction (Y-axis direction) on a column basis (on a row basis (Y-axis direction) of the patch electrodes 108).

[0067] The radio wave reflecting device 100a applies a control signal to each group of the plurality of patch electrodes 108 arranged in the row direction (Y-axis direction), thereby being able to control the reflection direction of the reflected wave of the radio wave incident on the radio wave reflecting plate 120. That is, the radio wave reflecting device 100a can control the traveling direction of the reflected wave in the left-right direction of the drawing with respect to the radio wave irradiated to the radio wave reflecting plate 120, centered around the reflection axis VR parallel to the row direction (Y-axis direction).

[0068] Figure 4 The following schematically shows how the traveling direction of the reflected wave changes due to the two reflecting elements 102. The following shows how, when the radio wave is incident on the first reflecting element 102a and the second reflecting element 102b with the same phase, since different control signals (V1≠V2) are applied to the first reflecting element 102a and the second reflecting element 102b, the phase change of the reflected wave generated by the second reflecting element 102b is greater than that of the first reflecting element 102a. As a result, the phase of the reflected wave R1 reflected by the first reflecting element 102a is different from the phase of the reflected wave R2 reflected by the second reflecting element 102b (in Figure 4 In the figure, the phase of the reflected wave R2 is ahead of the phase of the reflected wave R1), and apparently, the traveling direction of the reflected wave changes to an inclined direction.

[0069] Applying this principle to Figure 3The radio wave reflection device 100a shown can control the reflection direction to be a single-axis direction by controlling the phase change amount based on the reflection element for each column, for example.

[0070] 2-2. Radio wave reflection device B (dual-axis reflection control)

[0071] Figure 3 The reflection axis VR of the radio wave reflection device 100a shown is a single axis, so the reflection angle can be controlled in the direction of the reflection axis VR as the rotation axis. In contrast, this embodiment shows an example of a radio wave reflection device 100b capable of dual-axis reflection control. In the following description, the description is centered on the parts different from the radio wave reflection device 100a.

[0072] The radio wave reflection device 100b has a plurality of second wirings 132 extending in the column direction (X-axis direction). The plurality of first wirings 118 and the plurality of second wirings 132 are arranged in a manner of crossing each other with an insulating layer (not shown) interposed therebetween. The plurality of first wirings 118 are connected to the first driving circuit 124, and the plurality of second wirings 132 are connected to the second driving circuit 130. The second driving circuit 130 outputs a scanning signal.

[0073] Figure 5 The inset diagram shows an enlarged configuration of four patch electrodes 108 and two first wirings 118 and second wiring 132. A switch element 134 is provided at each of the four patch electrodes 108. The switching (on and off) of the switch element 134 is controlled by a scanning signal applied to the second wiring 132. The patch electrode 108 to which the switch element 134 is turned on is turned on by the first wiring 118 and a control signal is applied. The switch element 134 is formed of, for example, a thin film transistor. According to such a configuration, a plurality of patch electrodes 108 arranged in the column direction (X-axis direction) can be selected row by row, and control signals of different voltage levels can be applied to each row.

[0074] At once Figure 5 In the radio wave reflection device 100b shown, the traveling direction of the reflected wave irradiated to the radio wave reflection plate 120 can be controlled along the left-right direction of the drawing with the reflection axis VR parallel to the row direction (Y-axis direction) as the center, and in addition, the traveling direction of the reflected wave can be controlled along the up-down direction of the drawing with the reflection axis HR parallel to the column direction (X-axis direction) as the center. That is, the radio wave reflection device 100b has the reflection axis VR parallel to the row direction (Y-axis direction) and the reflection axis HR parallel to the column direction (X-axis direction), so the reflection angle can be controlled in the direction with the reflection axis VR as the rotation axis and the direction with the reflection axis HR as the rotation axis.

[0075] Applying this principle to Figure 5The radio wave reflection device 100b shown can control the reflection direction to be a uniaxial direction or a biaxial direction by controlling the phase change amount by the reflection element 102 independently in each of the columns and rows, for example.

[0076] Figure 6 An example of a cross-sectional structure of a reflective element 102 in which a switching element 134 is connected to a patch electrode 108 is shown. The switching element 134 is provided on a dielectric substrate (dielectric layer) 104. The switching element 134 is a transistor, and has a structure in which a first gate electrode 138, a first gate insulating layer 140, a semiconductor layer 142, a second gate insulating layer 146, and a second gate electrode 148 are stacked. A primer layer 136 may be provided between the first gate electrode 138 and the dielectric substrate (dielectric layer) 104. A first wiring 118 is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118 is provided so as to be in contact with the semiconductor layer 142. In addition, a first connecting wiring 144 is provided in the same layer as the conductive layer forming the first wiring 118. The first connecting wiring 144 is provided so as to be in contact with the semiconductor layer 142. The connection structure of the first wiring 118 and the first connection wiring 144 to the semiconductor layer 142 is shown as a structure in which one wiring is connected to the source of the transistor and the other wiring is connected to the drain.

[0077] The first interlayer insulating layer 150 is provided so as to cover the switching element 134. The second wiring 132 is provided on the first interlayer insulating layer 150. The second wiring 132 is connected to the second gate electrode 148 via a contact hole formed in the first interlayer insulating layer 150. It should be noted that, although not shown in the figure, the first gate electrode 138 and the second gate electrode 148 are electrically connected to each other in a region that does not overlap with the semiconductor layer 142. On the first interlayer insulating layer 150, a second connection wiring 152 is provided in the same conductive layer as the second wiring 132. The second connection wiring 152 is connected to the first connection wiring 144 via a contact hole formed in the first interlayer insulating layer 150.

[0078] The second interlayer insulating layer 154 is provided so as to cover the second wiring 132 and the second connection wiring 152. Furthermore, the planarizing layer 156 is provided so as to fill the step difference of the switching element 134. By providing the planarizing layer 156, the patch electrode 108 can be formed without being affected by the arrangement of the switching element 134. A passivation layer 158 is provided on the flat surface of the planarizing layer 156. The patch electrode 108 is provided on the passivation layer 158. The patch electrode 108 is connected to the second connection wiring 152 via a contact hole penetrating the passivation layer 158, the planarizing layer 156, and the second interlayer insulating layer 154. A first orientation film 112a is provided on the patch electrode 108.

[0079] The counter substrate 106 and Figure 1B The common electrode 110 and the second orientation film 112b are similarly provided. The surface of the dielectric substrate (dielectric layer) 104 provided with the switching element 134 and the patch electrode 108 is arranged in a manner opposite to the surface of the counter substrate provided with the common electrode 110, and the liquid crystal layer 114 is provided therebetween. The thickness T of the dielectric substrate (dielectric layer) 104 can be set to be the length from the surface of the patch electrode 108 on the liquid crystal layer 114 side to the surface of the dielectric substrate (dielectric layer) 104 on the opposite side to the surface provided with the patch electrode 108. In this case, the thickness of at least one insulating layer (primer layer 136, first gate insulating layer 140, second gate insulating layer 146, first interlayer insulating layer 150, second interlayer insulating layer 154, planarizing layer 156, passivation layer 158) between the patch electrode 108 and the dielectric substrate (dielectric layer) 104 can be taken into consideration.

[0080] Each layer formed on the dielectric substrate (dielectric layer) 104 is formed using the following materials. The base coat layer 136 is formed, for example, of a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed, for example, of a silicon oxide film, or a stacked structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed of a silicon semiconductor such as amorphous silicon and polycrystalline silicon, or an oxide semiconductor containing metal oxides such as indium oxide, zinc oxide, and gallium oxide. The first gate electrode 138 and the second gate electrode 148 can be formed, for example, of molybdenum (Mo), tungsten (W), or an alloy thereof. The first wiring 118, the second wiring 132, the first connecting wiring 144, and the second connecting wiring 152 are formed using metal materials such as titanium (Ti), aluminum (Al), and molybdenum (Mo). For example, it can also be composed of a stacked structure of titanium (Ti) / aluminum (Al) / titanium (Ti), or a stacked structure of molybdenum (Mo) / aluminum (Al) / molybdenum (Mo). The planarization layer 156 is formed of a resin material such as acrylic resin or polyimide. The passivation layer 158 is formed of, for example, a silicon nitride film. The patch electrode 108 and the common electrode 110 are formed of a metal film such as aluminum (Al) or copper (Cu) or a transparent conductive film such as indium tin oxide (ITO).

[0081] like Figure 6As shown, by connecting the second wiring 132 to the gate of the transistor used as the switching element 134, connecting the first wiring 118 to one of the source and drain of the transistor, and connecting the patch electrode 108 to the other of the source and drain, it is possible to select a predetermined patch electrode from the plurality of patch electrodes 108 arranged in a matrix and apply a control signal. Furthermore, by providing the switching element 134 to each patch electrode 108 in the radio wave reflection plate 120, it is possible to apply a control voltage to each patch electrode 108 arranged in a horizontal row along the first direction (X-axis direction) or to each patch electrode 108 arranged in a vertical row along the second direction (Y-axis direction). For example, when the radio wave reflection plate 120 is upright, the reflection direction of the reflected wave can be controlled in the left-right direction and the up-down direction.

[0082] 3. Inspection method

[0083] Next, refer to Figure 7 , Figure 8A to Figure 8C and Figures 9A to 9C A method of inspecting the radio wave reflection device 100 will be described.

[0084] First, the direction from which the patch electrode 108 can be observed is defined as the upper surface, and the radio wave reflection device 100 is set in the inspection device so that it can be observed from the upper surface. Figure 7 Like the reflective element 102 shown in FIG. 1 , the radio wave reflecting device 100 is provided with the patch electrode 108 as the upper surface and the common electrode 110 as the lower surface.

[0085] The inspection device may be any microscope capable of nondestructively observing the radio wave reflection device 100, for example, an optical microscope. When the radio wave reflection device 100 is observed using an optical microscope, since the radio wave reflection device 100 is often made of a conductive metal that does not penetrate the common electrode 110, the patch electrode 108 and its surroundings can be observed from the upper surface using reflected light.

[0086] In addition, it is preferable that the inspection device has an image capture function for capturing shape information of the reflection element 102 to be observed. Thus, when the radio wave reflection device 100 is a large area or the observation and inspection of the radio wave reflection device 100 are not performed at the same time, the shape information of the observed reflection element 102 can be batch processed as an image.

[0087] Next, the inspection device is adjusted in such a way that the width or the length in the vertical and horizontal directions of the patch electrode 108 of the reflective element 102 can be measured. For example, when the patch electrode 108 is rectangular, the inspection device is adjusted so that the size of about 1 / 20 relative to the long side or the short side can be measured. At this time, an optical filter such as a polarizing plate may not be provided in the inspection device. The observation of the radio wave reflection device 100 in this embodiment is different from the observation of the display device using liquid crystal, and can be performed without an optical filter.

[0088] Next, voltages V0 to V4 are applied between the patch electrode 108 and the common electrode 110, and the reflective element 102 is observed. In the present embodiment, voltage V0 represents a case where the voltage between the patch electrode 108 and the common electrode 110 is 0V, and the application of 0V is also included in the application of voltage. In addition, voltages V0 to V4 are different voltages from each other. In addition, the absolute values ​​of each of voltages V0 to V4 increase in the order of voltage V0 to voltage V4. These applied voltages are not limited to voltages V0 to V4, and can be appropriately set within the range in which the reflective element 102 can be set from a low phase difference to a high phase difference.

[0089] Finally, the quality of the reflective element 102 is determined based on changes in the frame-shaped region that appears on the periphery of the patch electrode 108 during application of the voltage (described later).

[0090] <Judgment Criteria>

[0091] First, refer to Figure 7 The reflective element 102 that applies a desired voltage to the liquid crystal layer will be described. The desired voltage corresponds to the voltage applied between the patch electrode 108 and the common electrode 110 .

[0092] A voltage V0 is applied between the patch electrode 108 and the common electrode 110, or no voltage is applied between the patch electrode 108 and the common electrode 110 of the reflective element 102. In this case, when the reflective element 102 is observed from the top surface, Figure 7 As in the reflective element 102 shown by the voltage V0, the frame-shaped region 160 does not appear on the periphery of the patch electrode 108.

[0093] A voltage V1 is applied between the patch electrode 108 and the common electrode 110. At this time, when the reflective element 102 is observed from the top surface, Figure 7As shown in the reflective element 102 shown by the voltage V1, a frame-shaped area 160 with a width L1a appears on the periphery of the patch electrode 108. The frame-shaped area 160 surrounds the patch electrode 108 in a plan view. In addition, the frame-shaped area 160 may appear with the same width along the first wiring 118 connected to the patch electrode 108. The width L1a is set to be a width that serves as a reference for determining whether the corresponding frame-shaped area 160 is good or not when the voltage V1 is normally applied between the patch electrode 108 and the common electrode 110.

[0094] A voltage V2 is applied between the patch electrode 108 and the common electrode 110. At this time, when the reflective element 102 is observed from the top surface, Figure 7 As shown in the reflective element 102 with the voltage V2, a frame-shaped area 160 with a width L2a appears on the periphery of the patch electrode 108. In addition, sometimes the frame-shaped area 160 appears with the same width along the first wiring 118 connected to the patch electrode 108. The width L2a is set to be a width that becomes a reference for judging whether the corresponding frame-shaped area 160 is good or not when the voltage V2 is normally applied between the patch electrode 108 and the common electrode 110. Similar to the relationship that the absolute value of the voltage V2 is greater than the absolute value of the voltage V1, the reference width L2a is greater than the reference width L1a. In addition, since the absolute value of the voltage V2 is greater than the absolute value of the voltage V1, the reflective element 102 can set a higher phase change amount than the phase change amount set for the reflective element 102 with the voltage V1 applied between the patch electrode 108 and the common electrode 110.

[0095] A voltage V3 is applied between the patch electrode 108 and the common electrode 110. At this time, when the reflective element 102 is observed from the top surface, Figure 7 As shown in the reflective element 102 with the voltage V3, a frame-shaped area 160 with a width L3a appears on the periphery of the patch electrode 108. In addition, sometimes the frame-shaped area 160 appears with the same width along the first wiring 118 connected to the patch electrode 108. The width L3a is set to be a width that serves as a reference for judging whether the frame-shaped area 160 is good or not when the voltage V3 is normally applied between the patch electrode 108 and the common electrode 110. Similar to the relationship that the absolute value of the voltage V3 is greater than the absolute value of the voltage V2, the reference width L3a is greater than the reference width L2a. In addition, since the absolute value of the voltage V3 is greater than the absolute value of the voltage V2, the reflective element 102 can set a higher phase change amount than the phase change amount set for the reflective element 102 with the voltage V2 applied between the patch electrode 108 and the common electrode 110.

[0096] A voltage V4 is applied between the patch electrode 108 and the common electrode 110. At this time, when the reflective element 102 is observed from the top surface, Figure 7As shown in the reflective element 102 with the voltage V4, a frame-shaped area 160 appears on the periphery of the patch electrode 108. In addition, sometimes the frame-shaped area 160 appears with the same width along the first wiring 118 connected to the patch electrode 108. When the width of the frame-shaped area 160 that appears is measured, the width of the frame-shaped area 160 is the width L4a. Here, the width L4a is set to be the width that serves as the reference for judging whether the frame-shaped area 160 is good or not when the voltage V4 is normally applied between the patch electrode 108 and the common electrode 110. Similar to the relationship that the absolute value of the voltage V4 is greater than the absolute value of the voltage V3, the reference width L4a is greater than the reference width L3a. In addition, since the absolute value of the voltage V4 is greater than the absolute value of the voltage V3, the reflective element 102 can set a higher phase change amount than the phase change amount set for the reflective element 102 with the voltage V3 applied between the patch electrode 108 and the common electrode 110.

[0097] The reference widths L1a to L4a can be determined by measuring the frame-shaped region 160 at each applied voltage according to the actually manufactured radio wave reflection device 100 as described above. In addition, the reference widths L1a to L4a can also be calculated and determined based on design criteria such as the size of the patch electrode 108 of the radio wave reflection device 100 and the physical property value of the cell thickness of the liquid crystal layer. The reference widths L1a to L4a can be determined without being particularly limited to the above-mentioned method.

[0098] Next, the details of determining the quality of the reflective element 102 based on the change in the frame-shaped region 160 will be described using the reference widths L1a to L4a. Here, determining the quality of the reflective element 102 means determining whether the desired voltage is normally applied to the liquid crystal layer 114 or whether the desired voltage is not normally applied to the liquid crystal layer 114.

[0099] Reference Figure 8A to Figure 8C An example in which it can be determined that the voltage V1 is normally applied to the liquid crystal layer 114 is described below. Fig. 8A FIG. 1 shows a top view of the reflective element 102 a - 1 in which a frame-shaped region 160 having a reference width L1 a appears. Figure 8B The reflective element 102a-2 is shown in which a frame-shaped region 160 having a width L12 that is larger than the reference width L1a by ΔL1 appears. Figure 8CThe reflective element 102a-3 is shown to have a frame-shaped area L13 that is smaller than the reference width L1a by ΔL1. In this way, if the difference between the width L12 or L13 of the frame-shaped area 160 and the reference width L1a is within ΔL1, it can be determined that the voltage V1 is applied to the liquid crystal layer 114. In other words, when the voltage V1 is applied between the patch electrode 108 and the common electrode 110, and the difference between the width of the frame-shaped area 160 and the reference width L1a is greater than ΔL1, the reflective element can determine that the voltage V1 is not normally applied to the liquid crystal layer. Figure 8A to Figure 8C , an example is shown in which the width increases or decreases without difference relative to the periphery of the patch electrode 108. However, the width L12 and the width L13 of the frame-shaped region 160 may not increase or decrease without difference, and if the difference between their widths and the reference width L1a is within ΔL1, it can be determined that the voltage V1 is normally applied to the liquid crystal layer.

[0100] The value of ΔL1 can be determined by measuring the frame-shaped region 160 at each applied voltage based on the actually manufactured radio wave reflection device 100, similarly to the reference width L1a. In addition, the value of the reference ΔL1 can also be calculated and determined based on design criteria such as the size of the patch electrode 108 of the radio wave reflection device 100 and the physical property value of the cell thickness of the liquid crystal layer. The method for determining ΔL1 is not limited to the above method, and the same is true for ΔL2 to ΔL4 described later.

[0101] Next, refer to Figures 9A to 9C right Figure 8A to Figure 8C The cross-sectional structure of the reflective element 102 shown is described. Fig. 9A Shows Fig. 8A The cross-sectional view of the reflective element 102a-1 is shown in FIG. Fig. 9A As shown, the frame-shaped region 160 is the upper surface of a portion of the liquid crystal layer 114. The portion of the liquid crystal layer 114 with the frame-shaped region 160 as the upper surface is a liquid crystal oriented by the oblique electric field (upper and lower arrows) formed between the patch electrode 108 and the common electrode 110 when the voltage V1 is applied between the patch electrode 108 and the common electrode 110. The oblique electric field indicated by the upper and lower arrows is an example and is not restrictive.

[0102] Specifically, a portion of the liquid crystal layer 114 with the frame-shaped region 160 as the upper surface shows the orientation of the liquid crystal caused by the leakage of the oblique electric field formed between the end of the patch electrode 108 or its periphery and the common electrode 110. The so-called leakage of the oblique electric field is Figures 9A to 9C As shown in FIG. 1 , it means that the electric field formed between the patch electrode 108 and the common electrode 110 is formed outside the width 108w of the patch electrode 108. Therefore, Figure 8A to Figure 8CAs shown, the orientation of the liquid crystal based on these electric fields can be visually identified as a frame-shaped area 160 appearing on the periphery of the patch electrode 108 when viewed from above, and the width of the frame-shaped area 160 that changes according to the voltage applied between the patch electrode 108 and the common electrode 110 can be measured.

[0103] In addition, if Figures 9A to 9C As shown, a portion of the liquid crystal layer 114 oriented by the electric field formed outside the width 108w is located between the patch electrode 108 and the common electrode 110 in a manner that sandwiches the liquid crystal layer 114 oriented by the electric field within the width 108w of the patch electrode 108.

[0104] Here, refer to Fig. 9B The cross-sectional view of Figure 8B 1. The reflective element 102a-2 shown in FIG. 1 is described. Similarly, the reflective element 102a-2 applies a voltage V1 between the patch electrode 108 and the common electrode 110, thereby forming an inclined electric field (up and down arrows) between the end of the patch electrode 108 and the common electrode 110. The inclined electric field formed thereby aligns a portion of the liquid crystal layer that does not overlap with the common electrode 110, and the oriented liquid crystal is visually recognized as a frame-shaped area 160 of width L12 when viewed from above. At this time, with respect to the reflective element 102a-2, the inclined electric field of the reflective element 102a-1 is significantly extended toward the common electrode 110 compared with the inclined electric field of the reflective element 102a-1, but the difference between the width L12 of the frame-shaped area 160 and the reference width L1a is within ΔL1, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0105] In addition, refer to Fig. 9C The cross-sectional view of Figure 8C 102a-3 is described below. Similarly, by applying voltage V1 between the patch electrode 108 and the common electrode 110, the reflective element 102a-3 forms an inclined electric field (up and down arrows) between the end of the patch electrode 108 and the common electrode 110. The inclined electric field formed thereby aligns a portion of the liquid crystal layer, and the oriented liquid crystal is visually recognized as a frame-shaped area 160 of width L13 when viewed from above. At this time, with respect to the reflective element 102a-3, the inclined electric field of the reflective element 102a-1 is narrower toward the common electrode 110 than the inclined electric field of the reflective element 102, but the difference between the width L12 of the frame-shaped area 160 and the reference width L1a is within ΔL1, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0106] Next, refer to Figure 10A to Figure 10C An example of the reflective element 102 in which it can be determined that the voltage V2 is normally applied to the liquid crystal layer 114 is described. Figure 8A to Figure 8C and Figures 9A to 9C The difference between the reflective element 102 shown in FIG. 1 is that the absolute value of the voltage applied between the patch electrode 108 and the common electrode 110 is greater than the absolute value of the voltage V1. Figure 8A to Figure 8C and Figures 9A to 9C The reflective elements 102 shown have the same or similar configurations, and description thereof may be omitted.

[0107] Fig. 10A FIG. 1 is a top view of the reflective element 102a-1 in which a voltage V2 is applied between the patch electrode 108 and the common electrode 110. Fig. 10A As shown, the reference width L2a when a voltage V2 different from the voltage V1 is applied between the patch electrode 108 and the common electrode 110 represents a width different from the reference width L1a when the voltage V1 is applied between the patch electrode 108 and the common electrode 110. In addition, since the absolute value of the voltage V2 is greater than the absolute value of the voltage V1, the reference width L2a is greater than the reference width L1a.

[0108] Fig. 10B and Fig. 10C The reflective elements 102 a - 2 and 102 a - 3 are shown in which the difference between the width of the frame-shaped region 160 and the reference width L2 a is ΔL2 . Fig. 10B The reflective element 102a-2 is shown in which a frame-shaped region 160 having a width L22 that is ΔL2 greater than the reference width L2a appears. Fig. 10C The reflective element 102a-3 is shown in which a frame-shaped area L23 smaller than the reference width L2a by ΔL2 appears. Thus, if the difference between the width L22 or L23 of the frame-shaped area 160 and the reference width L2a is within ΔL2, it can be determined that the voltage V2 is applied to the liquid crystal layer 114. In other words, when the voltage V1 is applied between the patch electrode 108 and the common electrode 110 and the difference between the width of the frame-shaped area 160 and the reference width L2a is greater than ΔL2, the reflective element can determine that the voltage V2 is not normally applied to the liquid crystal layer.

[0109] Next, refer to Figures 11A to 11C right Figure 10A to Figure 10C The cross-sectional structure of the reflective element 102 shown is described. Fig.11A Shows Fig. 10A As described above, since a voltage V2 greater than the voltage V1 is applied between the patch electrode 108 and the common electrode 110, the expansion of the oblique electric field (up and down arrows) between the patch electrode 108 and the common electrode 110 becomes larger than when the voltage V1 is applied. Therefore, the reference width L2a is greater than the reference width L1a.

[0110] Fig. 11B Shows Fig. 10BThe cross-sectional view of the reflective element 102a-2 is shown in FIG. Fig. 11B As shown, the oblique electric field of the reflective element 102a-2 extends toward the common electrode 110 significantly compared with the oblique electric field of the reflective element 102a-1, but the difference between the width L22 of the frame-shaped area 160 and the reference width L2a is within ΔL2, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0111] Fig. 11C Shows Fig. 10C The cross-sectional view of the reflective element 102a-3 is shown in FIG. Fig. 11C As shown, the oblique electric field of the reflective element 102a-3 extends toward the common electrode 110 less than the oblique electric field of the reflective element 102a-1, but the difference between the width L23 of the frame-shaped area 160 and the reference width L2a is within ΔL2, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0112] Next, refer to Figures 12A to 12C An example of the reflective element 102 in which it can be determined that the voltage V3 is normally applied to the liquid crystal layer 114 is described. Figure 10A to Figure 10C and Figures 11A to 11C The difference between the reflective element 102 shown in FIG. 1 is that the absolute value of the voltage applied between the patch electrode 108 and the common electrode 110 is greater than the absolute value of the voltage V2. Figure 10A to Figure 10C and Figures 11A to 11C The reflective elements 102 shown have the same or similar configurations, and description thereof may be omitted.

[0113] Fig. 12A FIG. 1 is a top view of the reflective element 102a-1 in which a voltage V2 is applied between the patch electrode 108 and the common electrode 110. Fig. 12A As shown, the reference width L3a when a voltage V3 different from the voltage V2 is applied between the patch electrode 108 and the common electrode 110 represents a width different from the reference width L2a when the voltage V2 is applied between the patch electrode 108 and the common electrode 110. In addition, since the absolute value of the voltage V3 is greater than the absolute value of the voltage V2, the reference width L3a is greater than the reference width L2a.

[0114] Fig. 12B and Fig. 12C The reflective elements 102 a - 2 and 102 a - 3 are shown in which the difference between the width of the frame-shaped region 160 and the reference width L3 a is ΔL3 . Fig. 12B The reflective element 102a-2 is shown in which a frame-shaped region 160 having a width L22 that is ΔL3 greater than the reference width L3a appears. Fig. 12CThe reflective element 102a-3 is shown in which a frame-shaped area L23 smaller than the reference width L3a by ΔL3 appears. Thus, if the difference between the width L22 or L23 of the frame-shaped area 160 and the reference width L3a is within ΔL3, it can be determined that the voltage V3 is applied to the liquid crystal layer 114. In other words, when the voltage V1 is applied between the patch electrode 108 and the common electrode 110 and the difference between the width of the frame-shaped area 160 and the reference width L3a is greater than ΔL3, the reflective element can determine that the voltage V3 is not normally applied to the liquid crystal layer.

[0115] Next, refer to Figures 13A to 13C right Figures 12A to 12C The cross-sectional structure of the reflective element 102 shown is described. Fig.13A Shows Fig. 12A As described above, since a voltage V3 greater than the voltage V2 is applied between the patch electrode 108 and the common electrode 110, the expansion of the oblique electric field (upper and lower arrows) between the patch electrode 108 and the common electrode 110 becomes larger than when the voltage V2 is applied. Therefore, the reference width L3a is greater than the reference width L2a.

[0116] Fig. 13B Shows Fig. 12B The cross-sectional view of the reflective element 102a-2 is shown in FIG. Fig. 13B As shown, with respect to the reflective element 102a-2, the inclined electric field of the reflective element 102a-1 extends significantly toward the common electrode 110 compared with the inclined electric field of the reflective element 102a-1, but the difference between the width L22 of the frame-shaped area 160 and the reference width L3a is within ΔL3, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0117] Fig. 13C Shows Fig. 12C The cross-sectional view of the reflective element 102a-3 is shown in FIG. Fig. 13C As shown, with respect to the reflective element 102a-3, the inclined electric field of the reflective element 102a-1 significantly extends toward the common electrode 110 compared with the inclined electric field of the reflective element 102a-1, but the difference between the width L23 of the frame-shaped area 160 and the reference width L3a is within ΔL3, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0118] Next, refer to Figures 14A to 14C An example in which it can be determined that the voltage V4 is normally applied to the liquid crystal layer 114 is described below. Figures 12A to 12C and Figures 13A to 13C The difference between the reflective element 102 shown in FIG. 1 is that the absolute value of the voltage V4 applied between the patch electrode 108 and the common electrode 110 is greater than the absolute value of the voltage V3. Figures 12A to 12C and Figures 13A to 13C The reflective elements 102 shown have the same or similar configurations, and description thereof may be omitted.

[0119] Fig.14A FIG. 4 shows a top view of the reflective element 102 a - 1 with a voltage V4 applied between the patch electrode 108 and the common electrode 110. Fig.14A As shown, the reference width L4a when a voltage V4 different from the voltage V3 is applied between the patch electrode 108 and the common electrode 110 represents a width different from the reference width L3a when the voltage V3 is applied between the patch electrode 108 and the common electrode 110. In addition, since the absolute value of the voltage V4 is greater than the absolute value of the voltage V3, the reference width L4a is greater than the reference width L3a.

[0120] Fig. 14B and Fig. 14C The reflective elements 102 a - 2 and 102 a - 3 are shown in which the difference between the width of the frame-shaped region 160 and the reference width L4 a is ΔL4 . Fig. 14B The reflective element 102a-2 is shown in which a frame-shaped region 160 having a width L22 that is ΔL4 greater than the reference width L4a appears. Fig. 14C The reflective element 102a-3 is shown in which a frame-shaped region L23 smaller than the reference width L4a by ΔL4 appears. Thus, if the difference between the width L22 or L23 of the frame-shaped region 160 and the reference width L4a is within ΔL4, it can be determined that the voltage V4 is applied to the liquid crystal layer 114. In other words, when the voltage V4 is applied between the patch electrode 108 and the common electrode 110 and the difference between the width of the frame-shaped region 160 and the reference width L4a is greater than ΔL4, the reflective element can determine that the voltage V4 is not normally applied to the liquid crystal layer.

[0121] Next, refer to Figures 15A to 15C right Figures 14A to 14C The cross-sectional structure of the reflective element 102 shown is described. Fig.15A Shows Fig.14A As described above, since a voltage V4 greater than the voltage V3 is applied between the patch electrode 108 and the common electrode 110, the expansion of the oblique electric field (upper and lower arrows) between the patch electrode 108 and the common electrode 110 becomes larger than when the voltage V3 is applied. Therefore, the reference width L4a is greater than the reference width L3a.

[0122] Fig. 15B Shows Fig. 14B The cross-sectional view of the reflective element 102a-2 is shown in FIG. Fig. 15BAs shown, the oblique electric field of the reflective element 102a-2 extends toward the common electrode 110 significantly compared with the oblique electric field of the reflective element 102a-1, but the difference between the width L22 of the frame-shaped area 160 and the reference width L4a is within ΔL4, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0123] Fig. 15C Shows Fig. 14C The cross-sectional view of the reflective element 102a-3 is shown in FIG. Fig. 15C As shown, the oblique electric field of the reflective element 102a-3 extends toward the common electrode 110 less than the oblique electric field of the reflective element 102a-1, but the difference between the width L23 of the frame area 160 and the reference width L4a is within ΔL4, so it can be determined that the voltage is normally applied to the liquid crystal layer 114.

[0124] As described above, the inspection method of the radio wave reflection device 100 according to one embodiment of the present invention can apply a desired voltage between the patch electrode 108 and the common electrode 110 of each of the plurality of reflection elements 102 of the radio wave reflection device 100, and can determine the quality of each reflection element 102 based on the change of the frame-shaped area 160 that appears on the periphery of the patch electrode 108 when viewed from above. Such quality determination can be performed on the radio wave reflection device 100 in a non-destructive manner, and can therefore be used for pre-shipment inspection of the radio wave reflection device 100. In addition, by measuring the width of the frame-shaped area 160 that appears on the periphery of the patch electrode 108 when viewed from above, it is possible to determine the defective mode of the reflection element 102. By determining the defective mode, it is possible to perform defect analysis in the manufacturing process of the radio wave reflection device 100, and it is possible to further improve the yield rate of the radio wave reflection device 100.

[0125] 4. Bad Patterns

[0126] Fig.16 The top view of the reflective element 102 when a desired voltage is not applied to the liquid crystal layer 114 is illustrated.

[0127] Fig.16 A shows an example of the reflective element 102 of the defective mode A. With respect to the frame-shaped area 160, if voltages V0 to V4 are applied between the patch electrode 108 and the common electrode 110, respectively, voltages V0 to V2 appear with a predetermined width, and disappear in the voltages V3 to V4, which are high potentials. The so-called predetermined width, for example, means a width within a difference ΔL1 from the reference width L1a relative to the voltage V1, and a width within a difference ΔL2 from the reference width L2a relative to the voltage V2. Under the condition of defective mode A, it is assumed that the electrical characteristics of the switch element 134 connected to the patch electrode 108 are defective.

[0128] Fig.16 B shows an example of the reflective element 102 of the defective mode B. Regarding the frame-shaped area 160, if voltages V0 to V4 are applied between the patch electrode 108 and the common electrode 110, respectively, voltages V0 to V2 do not appear, but appear with a specified width in the voltage V3 to V4 which are high potentials. The so-called specified width, for example, means a width within the difference ΔL3 from the reference width L3a relative to the voltage V3, and a width within the difference ΔL4 from the reference width L4a relative to the voltage V4. It can be seen that in the defective mode B, the voltage applied to the liquid crystal layer is insufficient. It is assumed that the reason for the insufficient voltage is that the electrical characteristics of the switching element connected to the patch electrode 108 are defective. In addition, although not shown in the figure, as described above, when the frame-shaped area appears even though there is no specified width at a high potential, it can also be regarded as insufficient voltage applied to the liquid crystal layer, assuming that the electrical characteristics of the switching element connected to the patch electrode 108 are defective.

[0129] Fig.16 FIG. C shows an example of the reflective element 102 in the defective mode C. The frame-shaped region 160 is applied between the patch electrode 108 and the common electrode 110 from the voltage V0 to the voltage V4, but no change is observed. Specifically, the frame-shaped region 160 does not appear regardless of the applied voltage. Therefore, in the defective mode C, it is assumed that the switch element connected to the patch electrode 108 has an open circuit defect, and the connection between the patch electrode 108 and the switch element is poor.

[0130] Fig.16 FIG. 1 shows an example of a reflective element 102 in a bad mode D. The frame-shaped region 160 is applied between the patch electrode 108 and the common electrode 110 from voltage V0 to voltage V4, respectively, but no change is observed. Specifically, the frame-shaped region 160 appears regardless of the applied voltage. Thus, in the bad mode D, considering the short circuit between the source and the drain, or the short circuit between the drain and the gate of the switching element, it is assumed that the voltage from the signal line connected to the source or the gate line connected to the gate electrode is always directly applied to the liquid crystal layer, and the frame-shaped region appears regardless of whether the switching element is turned on or off.

[0131] As described above, by observing the change in the frame-shaped region 160 due to the applied voltage, the reflective element 102 in which a desired voltage is not applied to the liquid crystal layer can be classified as a defective mode.

[0132] As the embodiments of the present invention, the embodiments described above can be implemented in appropriate combination as long as they are not contradictory. In addition, the solutions obtained by adding, deleting or changing the design of the components based on the embodiments, or the solutions obtained by adding, omitting or changing the conditions of the processes, which have the gist of the present invention, are also included in the scope of the present invention.

[0133] Even if there are other effects different from the effects brought about by the above-mentioned embodiments, it can be understood that the effects that are clearly described in this specification or the effects that can be easily predicted by those skilled in the art are brought about by the present invention.

[0134] Description of Reference Numerals

[0135] 100: radio wave reflection device, 100a: radio wave reflection device, 100b: radio wave reflection device, 102: reflection element, 102a: first reflection element, 102a-1: reflection element, 102a-2: reflection element, 102a-3: reflection element, 102b: second reflection element, 104: dielectric substrate (dielectric layer), 104: dielectric substrate, 106: counter substrate, 108: patch electrode, 108w: width, 110: common electrode, 110: common electrode, 112a: first orientation film, 112b: second orientation film, 114: liquid crystal layer, 116: liquid crystal molecules, 117: dielectric layer, 118: dielectric layer, 119: dielectric layer, 120: dielectric layer, 121: dielectric layer, 122: dielectric layer, 123: dielectric layer, 124: dielectric layer, 125: dielectric layer, 126: dielectric layer, 127: dielectric layer, 128: dielectric layer, 129: dielectric layer, 130: dielectric layer, 131: dielectric layer, 132: dielectric layer, 133: dielectric layer, 134: dielectric layer, 135: dielectric layer, 136: dielectric layer, 137: dielectric layer, 138: dielectric layer, 139: dielectric layer, 140: dielectric layer, 141: dielectric layer, 142: dielectric layer, 143: dielectric layer, 144: dielectric layer, 145: dielectric layer, 146: dielectric layer, 147: dielectric layer, 148: dielectric layer, 149: dielectric layer, 150: dielectric layer, 151: dielectric layer, 152: dielectric layer, 153: dielectric layer, 154: dielectric layer, 155: dielectric layer, 156: dielectric layer, 8: first wiring, 120: radio wave reflector, 122: peripheral region, 124: first drive circuit, 126: terminal portion, 128: sealing material, 130: second drive circuit, 132: second wiring, 134: switching element, 136: primer layer, 138: first gate electrode, 140: first gate insulating layer, 142: semiconductor layer, 144: first connection wiring, 146: second gate insulating layer, 148: second gate electrode, 150: first interlayer insulating layer, 152: second connection wiring, 154: second interlayer insulating layer, 156: planarization layer, 158: passivation layer, 160: frame region

Claims

1. A method for inspecting a radio wave reflection device, the method comprising inspecting a radio wave reflection device having a plurality of reflection elements arranged in a row direction and a column direction, The plurality of reflective elements each include a patch electrode, a common electrode overlapping the back side of the patch electrode, and a liquid crystal layer between the patch electrode and the common electrode. A voltage V1 is applied between the plurality of patch electrodes and the common electrode respectively. The quality of the reflective element is determined based on changes in frame-shaped regions that appear around the plurality of patch electrodes in a plan view when a voltage is applied between the plurality of patch electrodes and the common electrode.

2. The inspection method of the radio wave reflection device according to claim 1, wherein: The change in the frame-shaped region is a change in whether the frame-shaped region appears around the plurality of patch electrodes in a plan view when a voltage is applied between the plurality of patch electrodes and the common electrode.

3. The inspection method of the radio wave reflection device according to claim 1, wherein: It is determined whether the difference between the width L1 of the frame-shaped region when the voltage V1 is applied and the reference width L1a of the frame-shaped region corresponding to the voltage V1 is within ΔL1.

4. The inspection method of the radio wave reflection device according to claim 3, wherein: A voltage V2 different from the voltage V1 is applied between the plurality of patch electrodes and the common electrode, It is determined whether the width L1 when the voltage V1 is applied is different from the width L2 of the frame-shaped region when the voltage V2 is applied.

5. The inspection method of the radio wave reflection device according to claim 4, wherein: The absolute value of the voltage V2 is greater than the absolute value of the voltage V1, The reference width L2a of the frame-shaped region corresponding to the voltage V2 is larger than the reference width L1a.

6. The inspection method of the radio wave reflection device according to claim 3, wherein: A voltage V2 different from the voltage V1 is applied between the plurality of patch electrodes and the common electrode, It is determined whether the difference between the width L2 of the frame-shaped region when the voltage V2 is applied and the reference width L2a of the frame-shaped region corresponding to the voltage V2 is within ΔL2.

7. The inspection method of the radio wave reflection device according to claim 4, wherein: A voltage V3 is applied between the plurality of patch electrodes and the common electrode respectively. It is determined whether the width L2 is different from the width L3 of the frame-shaped region when the voltage V3 is applied.

8. The inspection method of the radio wave reflection device according to claim 7, wherein: The absolute value of the voltage V3 is greater than the absolute value of the voltage V2, The reference width L3a of the frame-shaped region corresponding to the voltage V3 is larger than the reference width L2a of the frame-shaped region corresponding to the voltage V2.

9. The method for inspecting a radio wave reflection device according to claim 6, wherein: A voltage V3 is applied between the plurality of patch electrodes and the common electrode respectively. It is determined whether the difference between the width L3 of the frame-shaped region when the voltage V3 is applied and the reference width L3a of the frame-shaped region corresponding to the voltage V3 is within ΔL3.

10. The inspection method of the radio wave reflection device according to claim 1, wherein: The frame-shaped area surrounds the patch electrode when viewed from above. The frame-shaped region is a portion of an upper surface of the liquid crystal layer.

11. The inspection method of the radio wave reflection device according to claim 10, wherein: A portion of the liquid crystal layer sandwiches the liquid crystal layer between the patch electrode and the common electrode in a cross-sectional view.

12. The inspection method of the radio wave reflection device according to claim 10, wherein: The portion of the liquid crystal layer is a portion of the liquid crystal layer aligned by an oblique electric field formed between the patch electrode and the common electrode.

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