TWI859007B - Image sensor structure - Google Patents

Abstract

An image sensor structure including a substrate, a photodetector, and a transparent capacitor is provided. The photodetector is located in the substrate. The transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface.

Description

Image sensor structure

The present invention relates to an image sensor structure, and more particularly to an image sensor structure including a capacitor.

Image sensors are widely used in many modern electronic devices (such as smart phones or digital cameras). However, how to further improve the electrical performance of image sensors is a goal that is being continuously worked on.

The present invention provides an image sensor structure which has better electrical performance.

The present invention provides an image sensor structure, including a substrate, a photodetector and a transparent capacitor. The photodetector is located in the substrate. The transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface.

According to an embodiment of the present invention, in the image sensor structure, the light detector is, for example, a photodiode.

According to an embodiment of the present invention, the image sensor structure may further include a first dielectric structure and a second dielectric structure. The first dielectric structure is located between the transparent capacitor and the substrate. The first dielectric structure may have an opening. The opening may be located directly above the photodetector. The transparent capacitor is located in the opening and on the top surface of the first dielectric structure. The second dielectric structure is located on the transparent capacitor and the first dielectric structure.

According to an embodiment of the present invention, in the above-mentioned image sensor structure, the transparent capacitor may include a first transparent electrode layer, a transparent dielectric layer, and a second transparent electrode layer sequentially stacked on a first dielectric structure.

According to an embodiment of the present invention, in the above-mentioned image sensor structure, the first transparent electrode layer can be conformally positioned in the opening and on the top surface of the first dielectric structure. The transparent dielectric layer can be conformally positioned on the first transparent electrode layer. The second transparent electrode layer can be conformally positioned on the transparent dielectric layer.

According to an embodiment of the present invention, in the above-mentioned image sensor structure, the light transmittance of the first transparent electrode layer may be 80% to 95%, the light transmittance of the transparent dielectric layer may be 80% to 95%, and the light transmittance of the second transparent electrode layer may be 80% to 95%.

According to an embodiment of the present invention, in the above-mentioned image sensor structure, the light transmittance of the first transparent electrode layer may be 85% to 90%, the light transmittance of the transparent dielectric layer may be 90% to 95%, and the light transmittance of the second transparent electrode layer may be 85% to 90%.

According to an embodiment of the present invention, the image sensor structure may further include a first internal connection structure and a second internal connection structure. The first internal connection structure is located in the first dielectric structure. The first internal connection structure can be electrically connected to the first transparent electrode layer. The second internal connection structure is located in the second dielectric structure. The second internal connection structure can be electrically connected to the second transparent electrode layer.

According to an embodiment of the present invention, in the above-mentioned image sensor structure, the first interconnect structure can be connected to the portion of the first transparent electrode layer located directly above the top surface of the first dielectric structure. The second interconnect structure can be connected to the portion of the second transparent electrode layer located directly above the top surface of the first dielectric structure.

According to an embodiment of the present invention, the image sensor structure may further include a color filter layer and a micro lens. The color filter layer is located on the second dielectric structure. The micro lens is located on the color filter layer.

Based on the above, in the image sensor structure proposed in the present invention, the transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface. Therefore, the transparent capacitor can have a larger capacitance value, thereby reducing thermal noise (KTC noise). In addition, since the transparent capacitor located directly above the photodetector can have the function of a light pipe, it can reflect oblique light to the photodetector, thereby improving quantum efficiency (QE). Since the image sensor structure proposed in the present invention can reduce thermal noise and improve quantum efficiency, the image sensor structure proposed in the present invention can have better electrical performance.

In order to make the above features and advantages of the present invention more clearly understood, embodiments are specifically cited below and described in detail with reference to the accompanying drawings.

The following examples are listed and illustrated in detail, but the examples provided are not intended to limit the scope of the present invention. For ease of understanding, the same components will be indicated by the same symbols in the following description. In addition, the drawings are for illustrative purposes only and are not drawn according to the original size. In fact, the size of various features can be arbitrarily increased or decreased for the sake of clarity.

1A to 1H are cross-sectional views of the manufacturing process of an image sensor structure according to some embodiments of the present invention.

Referring to FIG. 1A , a substrate 100 is provided. In some embodiments, the substrate 100 may be a semiconductor substrate, such as a silicon substrate. In addition, a photodetector 102 may be formed in the substrate 100. In some embodiments, the photodetector 102 is, for example, a photodiode. In addition, although not shown in the figure, the substrate 100 may have other required components (such as a doped region and/or an isolation structure), and their description is omitted here.

In some embodiments, a transistor 104 may be formed. In some embodiments, the transistor 104 may be a transfer transistor. The transistor 104 may include a gate 106 and a gate dielectric layer 108. The gate 106 is located on the substrate 100. In some embodiments, the material of the gate 106 is, for example, doped polysilicon. The gate dielectric layer 108 is located between the gate 106 and the substrate 100. In some embodiments, the material of the gate dielectric layer 108 is, for example, silicon oxide. In addition, although not shown in the figure, the transistor 104 may further include other required components (e.g., doped regions), and their description is omitted here.

In some embodiments, a transistor 110 may be formed. The transistor 110 may include a gate 112 and a gate dielectric layer 114. The gate 112 is located on the substrate 100. In some embodiments, the material of the gate 112 is, for example, doped polysilicon. The gate dielectric layer 114 is located between the gate 112 and the substrate 100. In some embodiments, the material of the gate dielectric layer 114 is, for example, silicon oxide. In addition, although not shown in the figure, the transistor 110 may further include other components (e.g., doped regions) as required, and their description is omitted here.

In some embodiments, a dielectric structure 116 may be formed on the substrate 100. The dielectric structure 116 may cover the transistor 104 and the transistor 110. In some embodiments, the dielectric structure 116 may be a multi-layer structure. In some embodiments, the dielectric structure 116 may be a silicon oxide layer, a silicon nitride layer, or a combination thereof.

In some embodiments, an interconnect structure 118 may be formed in the dielectric structure 116. In some embodiments, the interconnect structure 118 may be a multi-layer structure. In some embodiments, the interconnect structure 118 may include a contact, a via, a wire, or a combination thereof. In some embodiments, the material of the interconnect structure 118 is, for example, aluminum, tungsten, copper, titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof. In some embodiments, the interconnect structure 118 may be formed by an interconnect process.

In some embodiments, an interconnect structure 120 may be formed in the dielectric structure 116. In some embodiments, the interconnect structure 120 may be a multi-layer structure. In some embodiments, the interconnect structure 120 may include a contact window, a through hole, a wire, or a combination thereof. In some embodiments, the material of the interconnect structure 120 is, for example, aluminum, tungsten, copper, titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof. In some embodiments, the interconnect structure 120 may be formed by an interconnect process.

1B , a patterned photoresist layer 122 may be formed on the dielectric structure 116. In some embodiments, the patterned photoresist layer 122 may be formed by a lithography process. Then, the patterned photoresist layer 122 may be used as a mask to remove a portion of the dielectric structure 116 to form an opening OP1. Thus, an opening OP1 may be formed in the dielectric structure 116. The opening OP1 may be located directly above the photodetector 102. In some embodiments, the removal method of a portion of the dielectric structure 116 is, for example, dry etching.

1C , the patterned photoresist layer 122 may be removed. In some embodiments, the patterned photoresist layer 122 may be removed by, for example, dry stripping or wet stripping.

Then, a transparent electrode material layer 124 may be conformally formed in the opening OP1 and on the top surface S1 of the dielectric structure 116. The transparent electrode material layer 124 may be electrically connected to the interconnect structure 120. In some embodiments, the material of the transparent electrode material layer 124 is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO). In some embodiments, the transparent electrode material layer 124 is formed by, for example, chemical vapor deposition.

Then, a transparent dielectric material layer 126 may be conformally formed on the transparent electrode material layer 124. In some embodiments, the material of the transparent dielectric material layer 126 is, for example, silicon oxide. In some embodiments, the transparent dielectric material layer 126 is formed by, for example, atomic layer deposition (ALD).

Next, a transparent electrode material layer 128 may be conformally formed on the transparent dielectric material layer 126. In some embodiments, the material of the transparent electrode material layer 128 is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO). In some embodiments, the transparent electrode material layer 128 is formed by, for example, chemical vapor deposition.

1D, the transparent electrode material layer 128, the transparent dielectric material layer 126, and the transparent electrode material layer 124 may be patterned to form a transparent electrode layer 128a, a transparent dielectric layer 126a, and a transparent electrode layer 124a. Thus, a transparent capacitor 130 may be formed directly above the photodetector 102. The transparent capacitor 130 may include a transparent electrode layer 124a, a transparent dielectric layer 126a, and a transparent electrode layer 128a sequentially stacked on the dielectric structure 116. In some embodiments, the transparent electrode material layer 128, the transparent dielectric material layer 126, and the transparent electrode material layer 124 may be patterned by a lithography process and an etching process.

In some embodiments, the light transmittance of the transparent electrode layer 124a may be 80% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 124a may be 85% to 90%. In some embodiments, the light transmittance of the transparent dielectric layer 126a may be 80% to 95%. In some embodiments, the light transmittance of the transparent dielectric layer 126a may be 90% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 128a may be 80% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 128a may be 85% to 90%. In some embodiments, the material of the transparent electrode layer 124a is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO). In some embodiments, the material of the transparent dielectric layer 126a is, for example, silicon oxide. In some embodiments, the material of the transparent electrode layer 128a is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO).

1E, a dielectric layer 132 may be formed on the transparent capacitor 130 and the dielectric structure 116. The dielectric layer 132 may fill the opening OP1. In some embodiments, the material of the dielectric layer 132 is, for example, silicon oxide. In some embodiments, the dielectric layer 132 may be formed by, for example, chemical vapor deposition.

1F, a portion of the dielectric layer 132 may be removed. In some embodiments, a method of removing a portion of the dielectric layer 132 is, for example, chemical mechanical polishing.

Then, a through hole 134 may be formed in the dielectric layer 132. The through hole 134 may be electrically connected to the transparent electrode layer 128a. In some embodiments, the material of the through hole 134 is, for example, tungsten, titanium, titanium nitride, or a combination thereof. In some embodiments, the through hole 134 may be formed by an interconnection process.

1G, a wire 136 may be formed on the dielectric layer 132. The wire 136 may be electrically connected to the through hole 134. Thereby, an internal connection structure 138 may be formed. In the present embodiment, the internal connection structure 138 may be a multi-layer structure. For example, the internal connection structure 138 may include a through hole 134 and a wire 136. The through hole 134 is located in the dielectric layer 132. The wire 136 is located on the through hole 134 and the dielectric layer 132. In addition, a wire 140 may be formed on the dielectric layer 132. In some embodiments, the material of the wire 136 and the wire 140 is, for example, aluminum, tungsten, titanium, titanium nitride or a combination thereof. In some embodiments, the wire 136 and the wire 140 may be formed by an internal connection process.

1H, a dielectric layer 142 may be formed on the dielectric layer 132, the wire 136, and the wire 140. Thus, a dielectric structure 144 may be formed on the transparent capacitor 130 and the dielectric structure 116. In some embodiments, the dielectric structure 144 may be a multi-layer structure. For example, the dielectric structure 144 may include the dielectric layer 132 and the dielectric layer 142. The dielectric layer 132 is located on the transparent capacitor 130 and the dielectric structure 116. The dielectric layer 142 is located on the dielectric layer 132. In some embodiments, the material of the dielectric layer 142 is, for example, silicon oxide. In some embodiments, the method of forming the dielectric layer 142 is, for example, chemical vapor deposition.

Next, a color filter layer 146 may be formed on the dielectric structure 144. In some embodiments, the color filter layer 146 may be a red filter layer, a green filter layer, or a blue filter layer. Then, a microlens 148 may be formed on the color filter layer 146.

1H is used to illustrate the image sensor structure 10 of the above embodiment. In addition, although the method of forming the image sensor structure 10 is described using the above method as an example, the present invention is not limited thereto.

1H, the image sensor structure 10 includes a substrate 100, a photodetector 102, and a transparent capacitor 130. The photodetector 102 is located in the substrate 100. The transparent capacitor 130 is located directly above the photodetector 102. The transparent capacitor 130 has an upper surface S2 and an upper surface S3. The upper surface S3 is higher than the upper surface S2.

The image sensor structure 10 may further include a dielectric structure 116 and a dielectric structure 144. The dielectric structure 116 is located between the transparent capacitor 130 and the substrate 100. The dielectric structure 116 may have an opening OP1. The opening OP1 may be located directly above the photodetector 102. The transparent capacitor 130 is located in the opening OP1 and on the top surface S1 of the dielectric structure 116. The dielectric structure 144 is located on the transparent capacitor 130 and the dielectric structure 116.

The transparent capacitor 130 may include a transparent electrode layer 124a, a transparent dielectric layer 126a, and a transparent electrode layer 128a sequentially stacked on the dielectric structure 116. The transparent electrode layer 124a may be conformally disposed in the opening OP1 and on the top surface S1 of the dielectric structure 116. The transparent dielectric layer 126a may be conformally disposed on the transparent electrode layer 124a. The transparent electrode layer 128a may be conformally disposed on the transparent dielectric layer 126a.

The image sensor structure 10 may further include an internal connection structure 120 and an internal connection structure 138. The internal connection structure 120 is located in the dielectric structure 116. The internal connection structure 120 may be electrically connected to the transparent electrode layer 124a. In some embodiments, the internal connection structure 120 may be connected to the portion of the transparent electrode layer 124a located directly above the top surface S1 of the dielectric structure 116. The internal connection structure 138 is located in the dielectric structure 144. The internal connection structure 138 may be electrically connected to the transparent electrode layer 128a. In some embodiments, the internal connection structure 138 may be connected to the portion of the transparent electrode layer 128a located directly above the top surface S1 of the dielectric structure 116.

The image sensor structure 10 may further include a color filter layer 146 and a micro lens 148. The color filter layer 146 is located on the dielectric structure 144. The micro lens 148 is located on the color filter layer 146. In addition, the image sensor structure 10 may further include a transistor 104 and a transistor 110. The transistor 104 and the transistor 110 may be located on the substrate 100. Although not shown in the figure, the transparent electrode layer 124a may be electrically connected to the source (not shown) of the transistor 110 through a conductive component such as an internal connection structure 120.

In addition, the details of each component in the image sensor structure 10 (eg, materials and formation methods, etc.) have been described in detail in the above embodiments and will not be described again here.

Based on the above embodiments, it can be known that in the image sensor structure 10, the transparent capacitor 130 is located directly above the photodetector 102. The transparent capacitor 130 has an upper surface S2 and an upper surface S3. The upper surface S3 is higher than the upper surface S2. Therefore, the transparent capacitor 130 can have a larger capacitance value, thereby reducing thermal noise. In addition, since the transparent capacitor 130 located directly above the photodetector 102 can have the function of a light pipe, it can reflect oblique light to the photodetector 102, thereby improving quantum efficiency (QE). Since the image sensor structure 10 can reduce thermal noise and improve quantum efficiency, the image sensor structure 10 can have better electrical performance.

In summary, in the image sensor structure of the above embodiment, the transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface. Therefore, the transparent capacitor can have a larger capacitance value, thereby reducing thermal noise. In addition, since the transparent capacitor located directly above the photodetector can have the function of a light pipe, it can reflect oblique light to the photodetector, thereby improving quantum efficiency. Since the image sensor structure of the above embodiment can reduce thermal noise and improve quantum efficiency, the image sensor structure of the above embodiment can have better electrical performance.

Although the present invention has been disclosed as above by the embodiments, they are not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the attached patent application.

10: Image sensor structure

100: Base

102: Photodetector

104,110: Transistor

106,112: Gate

108,114: Gate dielectric layer

116,144: Dielectric structure

118,120,138:Internal connection structure

122: Patterned photoresist layer

124,128: Transparent electrode material layer

124a, 128a: transparent electrode layer

126: Transparent dielectric material layer

126a: transparent dielectric layer

130: Transparent capacitor

132,142: Dielectric layer

134:Through hole

136,140: Conductor

146: Color filter

148:Microlens

OP1: Opening

S1: Top

S2, S3: upper surface

1A to 1H are cross-sectional views of the manufacturing process of an image sensor structure according to some embodiments of the present invention.

10: Image sensor structure

100: Base

102: Photodetector

104,110: Transistor

106,112: Gate

108,114: Gate dielectric layer

116,144: Dielectric structure

118,120,138:Internal connection structure

124a, 128a: Transparent electrode layer

126a: Transparent dielectric layer

130: Transparent capacitor

132,142: Dielectric layer

134:Through hole

136,140: Conductor wire

146: Color filter layer

148: Micro lens

OP1: Open mouth

S1: Top surface

S2, S3: upper surface

Claims (7)

An image sensor structure includes: a substrate; a photodetector located in the substrate; a transparent capacitor located directly above the photodetector, wherein the transparent capacitor has a first upper surface and a second upper surface, and the second upper surface is higher than the first upper surface; a first dielectric structure located between the transparent capacitor and the substrate, wherein the first dielectric structure has an opening, the opening is located directly above the photodetector, and the transparent capacitor is located in the opening and the first dielectric structure is The transparent capacitor comprises a first transparent electrode layer, a transparent dielectric layer and a second transparent electrode layer sequentially stacked on the first dielectric structure; the first transparent electrode layer is conformally located in the opening and on the top surface of the first dielectric structure; and a second dielectric structure is located on the transparent capacitor and the first dielectric structure, wherein the transparent capacitor comprises a first transparent electrode layer, a transparent dielectric layer and a second transparent electrode layer sequentially stacked on the first dielectric structure, the first transparent electrode layer is conformally located in the opening and on the top surface of the first dielectric structure, the transparent dielectric layer is conformally located on the first transparent electrode layer, and the second transparent electrode layer is conformally located on the transparent dielectric layer. An image sensor structure as described in claim 1, wherein the photodetector includes a photodiode. The image sensor structure as described in claim 1, wherein the transmittance of the first transparent electrode layer is 80% to 95%, the transmittance of the transparent dielectric layer is 80% to 95%, and the transmittance of the second transparent electrode layer is 80% to 95%. An image sensor structure as described in claim 1, wherein the transmittance of the first transparent electrode layer is 85% to 90%, the transmittance of the transparent dielectric layer is 90% to 95%, and the transmittance of the second transparent electrode layer is 85% to 90%. The image sensor structure as described in claim 1 further includes: a first internal connection structure located in the first dielectric structure and electrically connected to the first transparent electrode layer; and a second internal connection structure located in the second dielectric structure and electrically connected to the second transparent electrode layer. An image sensor structure as described in claim 5, wherein the first internal connection structure is connected to a portion of the first transparent electrode layer located directly above the top surface of the first dielectric structure, and the second internal connection structure is connected to a portion of the second transparent electrode layer located directly above the top surface of the first dielectric structure. The image sensor structure as described in claim 1 further includes: a color filter layer located on the second dielectric structure; and a microlens located on the color filter layer.

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