TWI614885B - Photo sensing unit and photo sensitive array structure having the same - Google Patents

Abstract

A light sensing unit includes a first electrode, a second electrode, a third electrode, a photosensitive dielectric layer, a bridge electrode, and a flat layer. The second electrode is located above the first electrode. The third electrode is located above the second electrode. A photosensitive dielectric layer is located between the second electrode and the third electrode. The bridge electrode is located at the edge of the photosensitive dielectric layer and between the photosensitive dielectric layer and the third electrode. The flat layer covers the third electrode.

Description

Light sensing unit and optical sensing array structure

The invention relates to a light sensing technology, in particular to a light sensing unit and an optical sensing array structure.

With the development of technology, electronic systems such as mobile phones, personal notebook computers or tablets have become essential tools in life. In order to avoid the loss or misappropriation of important information, it is becoming a trend to use fingerprint recognition in electronic systems. The current electronic system has gradually widely used light sensing technology to realize the fingerprint identification function.

The light-sensing fingerprint reader is mainly a light-sensing unit configured in an array on a glass substrate, and the reflected light is received by the light-sensing unit for identification after the finger is illuminated by a light source. When the peaks and valleys of the fingerprint touch the fingerprint reader, the reflectance will be different due to the air gap between the direct contact of the peaks of the fingerprint and the valleys of the fingerprint, resulting in reflected light with different light intensities. The photosensitive dielectric layer in the photo-sensing unit generates a photocurrent due to different received light intensities. The generated photocurrent is transmitted to an external circuit through a transparent electrode layer in contact with the photosensitive dielectric layer for signal analysis to generate a corresponding operation instruction.

Here, the photosensitive dielectric layer is usually a semiconductor material, and the transparent electrode layer is a transparent conductive material. Due to the lattice mismatch between the semiconductor material and the transparent conductive material, it is difficult for the electrons generated from the photosensitive dielectric layer to be conducted to the external circuit through the transparent electrode layer, which affects the results of subsequent signal analysis and reduces the accuracy of fingerprint identification.

In one embodiment, an optical sensing array structure includes a plurality of data lines, a plurality of scanning lines, a plurality of light sensing units, and a plurality of active elements. The scanning lines and the data lines are alternately arranged to define a plurality of sensing areas. The active components are respectively located in the sensing areas and correspond to the light sensing units. The light sensing units are respectively located in the sensing areas, and each light sensing unit includes a first electrode, a second electrode, a third electrode, a photosensitive dielectric layer, a bridge electrode, and a flat layer. The second electrode is located above the first electrode. The third electrode is located above the second electrode. A photosensitive dielectric layer is located between the second electrode and the third electrode. The bridge electrode is located at the edge of the photosensitive dielectric layer and between the photosensitive dielectric layer and the third electrode. The flat layer covers the third electrode. Each active element is coupled to one of the scan lines, one of the data lines, and the second electrode of the corresponding light sensing unit.

In one embodiment, a light sensing unit includes a first electrode, a second electrode, a third electrode, a photosensitive dielectric layer, a bridge electrode, and a flat layer. The second electrode is located above the first electrode. The third electrode is located above the second electrode. A photosensitive dielectric layer is located between the second electrode and the third electrode. The bridge electrode is located at the edge of the photosensitive dielectric layer and between the photosensitive dielectric layer and the third electrode. The flat layer covers the third electrode.

In summary, according to the light sensing unit and the optical sensing array structure according to the embodiments of the present invention, a bridging electrode is used to bridge the photosensitive dielectric layer and the third electrode to facilitate exporting electrons generated by the photosensitive dielectric layer to the third electrode , Thereby improving the accuracy of fingerprint recognition. In some embodiments, the light sensing unit and the optical sensing array structure according to the embodiments of the present invention further use a patterned protective layer to cover at least the interface between the bridge electrode and the photosensitive dielectric layer, thereby reducing the reflection of the bridge electrode. The probability that the light is totally reflected back to the photosensitive dielectric layer in the third electrode, thereby improving the fingerprint contrast and reducing the halo around the fingerprint pattern, thereby further improving the accuracy of fingerprint identification.

FIG. 1 is a schematic top view of an optical sensing array structure according to an embodiment of the present invention. Referring to FIG. 1, the optical sensing array structure 100 includes a plurality of data lines DL, a plurality of scanning lines GL, a plurality of light sensing units 110 and a plurality of active devices 120. The data lines DL extend in a first direction and are spaced from each other, and the scan lines GL extend in a second direction and are spaced from each other. The first direction and the second direction may be substantially perpendicular. Here, the data lines DL and the scan lines GL are arranged alternately with each other. Each active element 120 corresponds to each light sensing unit 110, and each active element 120 is coupled to one of the scanning lines G1, one of the data lines DL, and the corresponding light sensing unit 110.

The optical sensing array structure 100 has a plurality of sensing regions N1. For ease of description, only a part of the sensing area N1 is shown in FIG. 1. These light sensing units 110 are respectively located in the sensing area N1. These active elements 120 are also located in the sensing area N1 and are respectively coupled to the corresponding light sensing units 110. That is, a light sensing unit 110 and an active element 120 coupled to the light sensing unit 110 are disposed in a sensing area N1.

FIG. 2 is a schematic cross-sectional view of an exemplary light sensing unit 110 corresponding to the A-A section line in FIG. 1. Please refer to FIG. 1 and FIG. 2, the light sensing unit 110 and the active device 120 are disposed on the substrate B1. In addition, the data lines DL and the scan lines GL are alternately arranged on a substrate B1 (not shown). In some embodiments, the material of the substrate B1 may be, but is not limited to, a silicon substrate, a glass substrate, a quartz substrate, or a polymer substrate.

Each light sensing unit 110 includes a first electrode 111, a second electrode 112, a photosensitive dielectric layer 114, a third electrode 113, a bridge electrode 115, and a flat layer 116. The first electrode 111, the second electrode 112, the photosensitive dielectric layer 114, the third electrode 113, the bridge electrode 115, and the flat layer 116 are sequentially disposed on the substrate B1. That is, the first electrode 111 is located on the substrate B1. The second electrode 112 is located on the first electrode 111 and is spaced from the first electrode 111. The third electrode 113 is located on the second electrode 112. The photosensitive dielectric layer 114 is located between the second electrode 112 and the third electrode 113 and is in contact with the second electrode 112 and the third electrode 113. The bridge electrode 115 is located at an edge of the photosensitive dielectric layer 114 and between the photosensitive dielectric layer 114 and the third electrode 113. The bridge electrode 115 is in contact with the photosensitive dielectric layer 114 and the third electrode 113 at the same time, and is not electrically connected to the second electrode 112. Moreover, the bridge electrode 115 is located at the edge of the photosensitive dielectric layer 114 to avoid affecting the effect of receiving light by the photosensitive dielectric layer 114. The edge of the photosensitive dielectric layer 114 may be, but is not limited to, a region near the boundary between the upper surface and the side surface of the photosensitive dielectric layer 114. In addition, the bridge electrode 115 is not limited to cover each edge of the photosensitive dielectric layer 114, in other words, the bridge electrode 115 may cover only a part or all of the edges of the photosensitive dielectric layer 114. Here, the bridge electrode 115 is electrically connected to the photosensitive dielectric layer 114 and the third electrode 113 at the same time, so as to bridge the photosensitive dielectric layer 114 and the third electrode 113 through the bridge electrode 115, which is beneficial to the generation of the photosensitive dielectric layer 114. The electrons are exported to the third electrode 113. The flat layer 116 covers the third electrode 113 to increase the surface flatness of the light sensing unit 110.

In this embodiment, the first electrode 111 of the light sensing unit 110 can receive a fixed potential V _bias . In some embodiments, the first electrode 111 and the scan line GL may belong to the same conductive layer, and the first electrode 111 and the scan line GL are not electrically connected. Therefore, the first electrode 111 and the scanning line GL can jointly form an island-shaped or line-shaped conductive pattern that is not directly connected (discontinuous) through the same process. In some embodiments, the material of the first electrode 111 may be a single metal material, such as copper (Cu), aluminum (Al), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), Chromium (Cr) and / or niobium (Nd). Alternatively, the material of the first electrode 111 may be an alloy material, such as an aluminum-molybdenum alloy and / or an aluminum-niobium alloy.

In some embodiments, the second electrode 112 and the data line DL may belong to the same conductive layer, and the second electrode 112 is electrically connected to the data line DL. Therefore, they can jointly form an island-shaped or line-shaped conductive pattern directly or indirectly connected (continuous or discontinuous) through the same process. In some embodiments, the material of the second electrode 112 may be a single metal material, such as copper (Cu), aluminum (Al), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), Chromium (Cr) and / or niobium (Nd). Alternatively, the material of the second electrode 112 may be an alloy material, such as an aluminum-molybdenum alloy and / or an aluminum-niobium alloy.

In some embodiments, each light sensing unit 110 may further include an insulating layer 117. The insulating layer 117 is located between the first electrode 111 and the second electrode 112 and is used to isolate the first electrode 111 and the second electrode 112. That is, the insulating layer 117 covers the first electrode 111 and the substrate B1. Here, the insulating layer 117 has a thickness capable of forming a capacitive coupling between the first electrode 111 and the second electrode 112. In some embodiments, the material of the insulating layer 117 may be, but is not limited to, materials such as silicon oxide (SiO _x ), silicon nitride (SiN _x ), and / or silicon oxynitride (SiON).

In some embodiments, the photosensitive dielectric layer 114 may be a silicon rich dielectric layer. The silicon-rich dielectric layer is, for example, but not limited to, a silicon-rich oxide layer (SiO _x ), a silicon-rich nitride layer (SiN _x ), a silicon-rich oxynitride layer (SiO _x N _y ), and a silicon-rich carbon oxide Layer (SiO _x C _y ), silicon-rich carbide layer (SiC _x ), or other suitable material layers.

In some embodiments, the third electrode 113 covers the upper surface of the photosensitive dielectric layer 114 and the upper surface of the bridge electrode 115. Here, the photosensitive dielectric layer 114, the third electrode 113, and the second electrode 112 form a capacitor. In some embodiments, the material of the third electrode 113 may be a transparent conductive film, such as, but not limited to, Indium-Zinc Oxide (IZO), Indium-Tin Oxide (ITO), and the like.

In some embodiments, the bridge electrode 115 may cover only at least a portion of a side surface of the photosensitive dielectric layer 114, or only cover at least a portion of an upper surface of the photosensitive dielectric layer 114, or cover a side of the photosensitive dielectric layer 114. Surface and more to the local upper surface. In some embodiments, the material of the bridge electrode 115 may be a single metal material, such as copper (Cu), aluminum (Al), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), chromium (Cr) and / or niobium (Nd). Alternatively, the material of the bridge electrode 115 may be an alloy material, such as an aluminum-molybdenum alloy and / or an aluminum-niobium alloy.

In some embodiments, the material of the flat layer 116 may be a coating material such as acrylic resin, epoxy resin, or a mixture of acrylic resin and epoxy resin.

FIG. 3 is a schematic cross-sectional view of a light sensing unit 110 according to another exemplary example corresponding to the A-A section line in FIG. 1. Please refer to FIG. 1 and FIG. 3. In some embodiments, each light sensing unit 110 may further include a patterned protective layer 130. The patterned protective layer 130 is located between the photosensitive dielectric layer 114, the third electrode 113, and the bridge electrode 115 of each light sensing unit 110. The refractive index of the patterned protective layer 130 is smaller than that of the third electrodes 113 of the light sensing units 110. Here, in each light sensing unit 110, the patterned protective layer 130 covers at least a portion of the photosensitive dielectric layer 114 and at least a portion of the bridge electrode 115.

In some embodiments, the patterned protective layer 130 covers at least the boundary between the bridge electrode 115 and the photosensitive dielectric layer 114 of each light sensing unit 110. Specifically, the patterned protective layer 130 covers the side surface LS of the bridge electrode 115 of each photo-sensing unit 110, and covers the boundary between the side surface LS of the bridge electrode 115 of each photo-sensing unit 110 and the photosensitive dielectric layer 114. .

In some examples, the patterned protective layer 130 further covers the edge S1 of the upper surface TS adjacent to the side surface LS of the bridge electrode 115 of each light sensing unit 110, the side surface LS of the bridge electrode 115 of each light sensing unit 110, And the boundary between the side surface LS of the bridge electrode 115 of each photo-sensing unit 110 and the photosensitive dielectric layer 114.

In some embodiments, the patterned protective layer 130 may cover the photosensitive dielectric layer 114 and the bridge electrode 115 of each light sensing unit 110. Here, the patterned protective layer 130 may have a plurality of first contact windows W1 and a plurality of second contact windows W2.

The first contact windows W1 respectively correspond to the bridge electrodes 115 of the light sensing units 110. Here, each first contact window W1 is located on the corresponding bridge electrode 115, and the upper surface of the bridge electrode 115 is exposed. In other words, each of the first contact windows W1 is an opening through the patterned protective layer 130. The bridge electrode 115 may be connected to the third electrode 113 through the first contact window W1.

The second contact windows W2 respectively correspond to the photosensitive dielectric layers 114 of the photo-sensing units 110. Here, each of the second contact windows W2 is located on the corresponding photosensitive dielectric layer 114, and the upper surface of the photosensitive dielectric layer 114 is exposed. In other words, each of the second contact windows W2 is another opening penetrating the patterned protective layer 130. The third electrode 113 may be connected to the photosensitive dielectric layer 114 through the second contact window W2.

Moreover, in each light sensing unit 110, the third electrode 113 is covered on the patterned protective layer 130, and is in direct contact with the bridge electrode 115 via the first contact window W1, and the photosensitive dielectric layer 114 via the second contact window W2. direct contact. In other words, the third electrode 113 extends from the upper surface of the patterned protective layer 130 along the sidewall of the first contact window W1 to the bottom of the first contact window W1 and contacts the bridge electrode 115 at the bottom of the first contact window W1. Similarly, the third electrode 113 extends from the upper surface of the patterned protective layer 130 along the side wall of the second contact window W2 to the bottom of the second contact window W2 and contacts the photosensitive dielectric layer at the bottom of the second contact window W2. 114.

In an embodiment, the opening size of each of the first contact windows W1 of the patterned protective layer 130 is substantially equal to the size of the upper surface TS of the corresponding bridge electrode 115. That is, each first contact window W1 exposes the entire upper surface of the corresponding bridge electrode 115.

In another embodiment, the opening size of each of the first contact windows W1 of the patterned protective layer 130 is smaller than the size of the upper surface TS of the corresponding bridge electrode 115. Accordingly, each of the first contact windows W1 exposes a part of the upper surface of the corresponding bridge electrode 115. In addition, when the opening size of each first contact window W1 is smaller than the size of the upper surface TS of the corresponding bridge electrode 115, each first contact window W1 may be located in the middle of the corresponding bridge electrode 115, that is, each first contact window W1 is not An edge region of the upper surface of the bridge electrode 115 adjacent to the photosensitive dielectric layer 114 may be exposed.

FIG. 4 is a partially enlarged view of a region C in FIG. 3. Referring to FIGS. 3 and 4, since the refractive index of the patterned protective layer 130 is smaller than that of each of the third electrodes 113, the reflected light L1 from the finger enters the third electrode 113 and then touches the bridge electrode 115 and the patterned protective layer 130. A part of the large-angle reflected light L1 passing through the third electrode 113 will cause total reflection at the interface between the third electrode 113 and the patterned protective layer 130 to avoid internal reflection to the photosensitive dielectric layer 114 and affect the sensing result.

Please refer back to FIG. 1. In this embodiment, each of the active devices 120 is electrically connected to a corresponding one of the scan lines GL and is connected to a corresponding one of the data lines DL. The second electrode 112 of the unit 110 is electrically connected. In other words, the second electrode 112 of each light sensing unit 110 is electrically connected to the corresponding data line DL through the corresponding active device 120.

Here, the photosensitive dielectric layer 114 of the photo-sensing unit 110 will leak electricity when irradiated with light. The scanning lines GL and the data lines DL can pass through the corresponding active element 120 to the two coupling capacitances of the corresponding light sensing unit 110 (the capacitance formed between the first electrode 111 and the second electrode 112 and the third electrode 113 and the second The capacitance formed between the electrodes 112) is charged, and the magnitude of the light leakage of the photosensitive dielectric layer 114 in the corresponding light sensing unit 110 is returned after charging, and the touch event is sensed and identified based on the size of the light leakage. . In other words, when the finger is located above the light sensing unit 110, the reflected light L1 caused by the finger will irradiate through the third electrode 113 to the photosensitive dielectric layer 114, so that the impedance of the photosensitive dielectric layer 114 decreases. The degree of the decrease in the impedance of the photosensitive dielectric layer 114 varies depending on the intensity of the reflected light L1 reflected by the peaks and valleys of the fingerprint of the finger. The active element 120 can be used as a switch of the corresponding light sensing unit 110 so as to charge the light sensing unit 110. According to this, the fingerprint pattern of the finger can be obtained according to the charge amount of the light sensing unit 110.

FIG. 5 is a schematic cross-sectional view of the light sensing unit 110 and the active device 120 according to an example of the B-B section line in FIG. 1. FIG. 6 is a schematic cross-sectional view of the light sensing unit 110 and the active device 120 according to another example of the B-B section line in FIG. 1.

In an embodiment, please refer to FIG. 1, FIG. 5, and FIG. 6. The active device 120 may be a bottom-gate thin film transistor, which includes a gate electrode 121, a channel layer 122, a source electrode 123, and a drain electrode. 124. The gate electrode 121, the channel layer 122, the source electrode 123, and the drain electrode 124 are sequentially formed on the substrate B1. That is, the gate electrode 121 is located on the substrate B1, the channel layer 122 is located above the gate electrode 121, and the source electrode 123 and the drain electrode 124 are located above the channel layer 122. The drain electrode 124 is electrically connected to the second electrode 112. In some embodiments, the gate electrode 121, the first electrode 111 of the photo-sensing unit 110, and the scan line GL all belong to the same conductive layer, so they can be formed together through the same process. Therefore, the material of the gate electrode 121 may be the same as that of the first electrode 111, such as, but not limited to, a single metal material or an alloy material. In some embodiments, the source electrode 123, the drain electrode 124, and the second electrode 112 may be conductive layers belonging to the same layer, so they are formed together through the same process. Therefore, the material of the source electrode 123 and the drain electrode 124 may be the same as that of the second electrode 112, such as but not limited to a single material or an alloy material. The active device 120 further includes a gate insulating layer 117, and the gate insulating layer 117 is disposed between the gate electrode 121 and the channel layer 122.

In an embodiment, referring to FIG. 6, the third electrode 113 of the light sensing unit 110 may further extend to cover the fourth electrode 125 above the active device 120 to prevent the fourth electrode 125 from being in a floating state. Coupling with other circuits (not shown) results in leakage of the active device 120.

In another embodiment, the active device 120 may also be a top-gate thin-film transistor, which includes a source electrode, a drain electrode, a channel layer, and a gate electrode. The source electrode, the drain electrode, the channel layer, and the gate electrode are sequentially formed on the substrate. That is, the channel layer is located above the source electrode and the drain electrode, and the gate electrode is located above the channel layer. The drain electrode is electrically connected to the second electrode.

However, the type of the active device 120 is not limited by the present invention, and it can be selected according to the electrical connection design or process requirements.

In summary, according to the light sensing unit and the optical sensing array structure according to the embodiments of the present invention, a bridging electrode is used to bridge the photosensitive dielectric layer and the third electrode to facilitate exporting electrons generated by the photosensitive dielectric layer to the third electrode , Thereby improving the accuracy of fingerprint recognition. In some embodiments, the light sensing unit and the optical sensing array structure according to the embodiments of the present invention further use a patterned protective layer to cover at least the interface between the bridge electrode and the photosensitive dielectric layer, thereby reducing the reflection of the bridge electrode. The probability that the light is totally reflected back to the photosensitive dielectric layer in the third electrode, thereby improving the fingerprint contrast and reducing the halo around the fingerprint pattern, thereby further improving the accuracy of fingerprint identification.

Although the technical content of the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art and making some changes and retouching without departing from the spirit of the present invention should be covered by the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

100‧‧‧ optical sensing array structure
110‧‧‧light sensing unit
111‧‧‧first electrode
112‧‧‧Second electrode
113‧‧‧Third electrode
114‧‧‧photosensitive dielectric layer
115‧‧‧bridge electrode
116‧‧‧ flat layer
117‧‧‧ Insulation
120‧‧‧active element
121‧‧‧Gate electrode
122‧‧‧Channel layer
123‧‧‧Source electrode
124‧‧‧ Drain electrode
125‧‧‧ Fourth electrode
130‧‧‧ patterned protective layer
B1‧‧‧ substrate
DL‧‧‧Data Line
GL‧‧‧scan line
N1‧‧‧sensing area
L1‧‧‧Reflected light
LS‧‧‧Side surface
TS‧‧‧ Top surface
V _bias ‧‧‧ fixed potential
W1‧‧‧The first contact window
W2‧‧‧Second contact window
W3‧‧‧Third contact window

FIG. 1 is a schematic top view of an optical sensing array structure according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an exemplary light sensing unit corresponding to the A-A section line in FIG. 1. FIG. 3 is a schematic cross-sectional view of a light sensing unit 110 according to another exemplary example corresponding to the A-A section line in FIG. 1. FIG. 4 is a partially enlarged view of a region C in FIG. 3. 5 is a schematic cross-sectional view of a light sensing unit and an active device according to an example of the B-B section line in FIG. 1. FIG. 6 is a schematic cross-sectional view of the light sensing unit 110 and the active device 120 according to another example of the B-B section line in FIG. 1.

100‧‧‧ optical sensing array structure

110‧‧‧light sensing unit

111‧‧‧first electrode

112‧‧‧Second electrode

113‧‧‧Third electrode

114‧‧‧photosensitive dielectric layer

115‧‧‧bridge electrode

116‧‧‧ flat layer

117‧‧‧ Insulation

B1‧‧‧ substrate

GL‧‧‧scan line

L1‧‧‧Reflected light

Claims (18)

An optical sensing array structure includes: a plurality of data lines; a plurality of scanning lines, the scanning lines and the data lines are interlaced with each other; a plurality of sensing areas; a plurality of light sensing units respectively located on the sensing Area, each of the light sensing units includes: a first electrode; a second electrode located above the first electrode; a third electrode located above the second electrode; a photosensitive dielectric layer located at the second electrode And the third electrode; a bridge electrode located at the edge of the photosensitive dielectric layer and between the photosensitive dielectric layer and the third electrode; and a flat layer covering the third electrode; and a plurality of active electrodes Components are respectively located in the sensing areas and respectively correspond to the light sensing units, and each of the active components is coupled to one of the scanning lines, one of the data lines and a corresponding one of the light sensing units The second electrode. The optical sensing array structure according to claim 1, wherein the third electrode of each of the light sensing units covers the photosensitive dielectric layer and the bridge electrode. The optical sensing array structure according to claim 1, wherein each of the light sensing units further comprises: a patterned protective layer, the photosensitive dielectric layer, the third electrode, and the bridge located in each of the light sensing units. Between the electrodes, the refractive index of the patterned protective layer is smaller than each of the third electrodes. The optical sensing array structure according to claim 3, wherein the patterned protective layer covers a side surface of the bridge electrode of each of the light sensing units and the side surface of the bridge electrode of each of the light sensing units and the Junction of photosensitive dielectric layer. The optical sensing array structure according to claim 4, wherein the patterned protective layer further covers an edge of an upper surface of the bridge electrode adjacent to the side surface of each of the light sensing units. The optical sensing array structure according to claim 1, wherein each of the light sensing units further comprises: a patterned protective layer covering the photosensitive dielectric layer and the bridge electrode of each of the light sensing units, wherein the pattern The refractive index of the patterned protective layer is smaller than each of the third electrodes. The patterned protective layer has a plurality of first contact windows respectively on the bridge electrodes and a plurality of second contact windows respectively on the photosensitive dielectric layers. And in each of the light sensing units, the third electrode is in direct contact with the bridge electrode via the first contact window, and the third electrode is in direct contact with the photosensitive dielectric layer via the second contact window. The optical sensing array structure according to claim 6, wherein an opening of each of the first contact windows is smaller than a corresponding upper surface of the bridge electrode. The optical sensing array structure according to claim 6, wherein each of the first contact windows is located in the middle of the corresponding bridge electrode. The optical sensing array structure according to claim 6, wherein each of the second contact windows is spaced from the adjacent bridge electrode. A light sensing unit includes a first electrode, a second electrode located above the first electrode, a third electrode located above the second electrode, and a photosensitive dielectric layer located between the second electrode and the first electrode. Between three electrodes; a bridge electrode located at the edge of the photosensitive dielectric layer and between the photosensitive dielectric layer and the third electrode; and a flat layer covering the third electrode. The light sensing unit according to claim 10, wherein the third electrode of each of the light sensing units covers the photosensitive dielectric layer and the bridge electrode. The light sensing unit according to claim 10, further comprising: a patterned protective layer located between the photosensitive dielectric layer, the third electrode, and the bridge electrode of each of the light sensing units, wherein the patterning The protective layer has a refractive index smaller than each of the third electrodes. The photo-sensing unit according to claim 12, wherein the patterned protective layer covers a side surface of the bridge electrode of each of the photo-sensing units and a boundary between the side surface of the bridge electrode and the photosensitive dielectric layer. The light sensing unit according to claim 13, wherein the patterned protective layer further covers an edge of an upper surface of the bridge electrode of each of the light sensing units adjacent to the side surface and the bridge of each of the light sensing units. The side surface of the electrode. The light sensing unit according to claim 10, further comprising: a patterned protective layer covering the photosensitive dielectric layer and the bridge electrode of each of the light sensing units, wherein a refractive index of the patterned protective layer is less than For each of the third electrodes, the patterned protective layer has a plurality of first contact windows respectively on the bridge electrodes and a plurality of second contact windows respectively on the photosensitive dielectric layers, and each of the light sensors In the measurement unit, the third electrode is in direct contact with the bridge electrode through the first contact window, and the third electrode is in direct contact with the photosensitive dielectric layer through the second contact window. The light sensing unit according to claim 15, wherein an opening of each of the first contact windows is smaller than a corresponding upper surface of the bridge electrode. The light sensing unit according to claim 15, wherein each of the first contact windows is located in the middle of the corresponding bridge electrode. The light sensing unit according to claim 15, wherein each of the second contact windows is spaced from the adjacent bridge electrode.