TW201836161A - Image sensor and method for forming the same - Google Patents

Abstract

An image sensor is provided. The image sensor includes an infrared receiving portion and a visible light receiving portion. The infrared receiving portion is configured to receive infrared. The visible light receiving portion is configured to receive a visible light. The visible light receiving portion includes an infrared cutoff filter grid configured to purify the visible light.

Description

 Image sensor and method of forming same  

The present invention relates to an image sensor, and more particularly to an image sensor having an infrared light sensing function.

With the development of access control systems and security systems, biometric techniques that use human features to confirm personal identity are gaining popularity. The highly reliable iris recognition technology is one of the popular biometric technologies. When the iris recognition technology is applied to an electronic device, such as a smart phone, the smart phone needs an image sensor capable of receiving visible light and infrared light, respectively, to realize the iris recognition function. Conventional image sensors have two distinct parts to receive visible and infrared light, respectively.

The invention provides an image sensor comprising an infrared light receiving portion and a visible light receiving portion. The infrared light receiving unit is configured to receive infrared light, and the visible light receiving unit is configured to receive visible light. The visible light receiving portion includes an infrared light cut filter grid, and the infrared light cut filter grid is used to purify visible light.

According to an embodiment of the invention, the visible light receiving portion further includes a visible light diode, an infrared light blocking filter layer, and a color filter layer. The infrared light cut filter layer is disposed on the visible light photodiode. The color filter layer is filled in the infrared light cut filter grid. The infrared light cut filter grid is disposed on the infrared light cut filter layer, and the visible light passes through the color filter layer, the infrared light cut filter grid, and the infrared light cut filter layer, and is received by the visible light photodiode.

According to an embodiment of the invention, the infrared light receiving portion includes an infrared light photodiode, a first filter layer, and a second filter layer. The first filter layer is disposed on the infrared light photodiode. The second filter layer is disposed on the first filter layer. The infrared light passes through the second filter layer and the first filter layer and is received by the infrared light photodiode.

According to an embodiment of the invention, one of the first filter layer and the second filter layer is an infrared light penetrating filter layer, and the other of the first filter layer and the second filter layer is A white filter or infrared light penetrates the filter layer.

According to an embodiment of the invention, the image sensor further includes a wafer layer on the infrared light diode and the visible light diode, wherein the first portion of the wafer layer is located in the visible light receiving portion, and the wafer layer The second part is located in the infrared light receiving portion.

According to an embodiment of the invention, the first portion of the wafer layer is between the infrared light-cut filter layer and the visible light diode.

According to an embodiment of the invention, the second portion of the wafer layer is between the first filter layer and the infrared light diode.

According to an embodiment of the invention, the color filter layer comprises a red filter unit, a green filter unit, and a blue filter unit.

According to an embodiment of the invention, the red filter unit, the green filter unit and the blue filter unit are each filled in the infrared light cut filter grid.

According to an embodiment of the invention, the image sensor further includes a microlens layer for collecting visible light and infrared light.

According to an embodiment of the invention, the microlens layer is located at the uppermost layer of the image sensor.

According to an embodiment of the invention, the microlens layer is located in the visible light receiving portion and the infrared light receiving portion.

According to an embodiment of the invention, the image sensor further includes a spacer layer for providing a flat surface, wherein the microlens layer is disposed on the flat surface.

According to an embodiment of the invention, the spacer layer is located in the visible light receiving portion and the infrared light receiving portion.

The invention also provides a method for forming an image sensor, comprising: providing a first component, the first component comprising a visible light receiving portion and an infrared light receiving portion, wherein the first component comprises a wafer layer and a first filter layer, the wafer The layer is located in the visible light receiving portion and the infrared light receiving portion, the first filter layer is located on the wafer layer, wherein the first filter layer is located in the infrared light receiving portion; and the first infrared light cut filter layer is coated on the first component, The first infrared light cut-off filter layer is located in the visible light receiving portion and the infrared light receiving portion; the plurality of photoresists are patterned on the first infrared light cut filter layer located in the visible light receiving portion to form the second component; The component is exposed until the first filter layer is formed to form an infrared light cut filter layer and an infrared light cut filter grid located in the visible light receiving portion, wherein the infrared light cut filter grid is located on the infrared light cut filter layer; The light layer is disposed in the infrared light cut filter grid, and a second filter layer is formed on the first filter layer; and the spacer layer and the microlens layer are sequentially disposed on the color filter layer and On the two filter layers, the spacer layer and the microlens layer are located in the visible light receiving portion and the infrared light receiving portion.

According to an embodiment of the invention, the first component further comprises a visible light photodiode and an infrared light photodiode. The visible light diode is located in the visible light receiving portion. The infrared light diode is located in the infrared light receiving portion. The wafer layer is located on the infrared light dipole and the visible light diode.

According to an embodiment of the invention, one of the first filter layer and the second filter layer is an infrared light penetrating filter layer, and the other of the first filter layer and the second filter layer is A white filter or infrared light penetrates the filter layer.

According to an embodiment of the invention, the color filter layer comprises a red filter unit, a green filter unit, and a blue filter unit.

According to an embodiment of the invention, the red filter unit, the green filter unit and the blue filter unit are each filled in the infrared light cut filter grid.

According to an embodiment of the invention, the infrared light cut filter layer and the infrared light cut filter grid are integrally formed.

100‧‧‧Image sensor

100A‧‧‧ first component

100B‧‧‧ second component

1000‧‧‧ method

110, 110A‧‧‧ Visible light receiving department

1100~1600‧‧‧Steps

112‧‧‧ Visible light sensing layer

114‧‧‧Infrared light cut-off filter

114E‧‧‧First infrared light cut-off filter

116‧‧‧Infrared light cut filter grid

118‧‧‧Color filter layer

118a‧‧‧Red Filter Unit

118b‧‧‧Blue filter unit

118c‧‧‧Green Filter Unit

120‧‧‧Infrared light receiving department

122‧‧‧Infrared light sensing layer

124‧‧‧First filter layer

126‧‧‧second filter layer

ML‧‧‧microlens layer

PR‧‧‧Light resistance

SP‧‧‧ spacer

WA‧‧‧ wafer layer

A better understanding of the aspects of the present disclosure can be obtained from the following detailed description taken in conjunction with the drawings. It should be noted that, according to industry standard practices, the features are not drawn to scale. In fact, in order to make the discussion clearer, the dimensions of each feature can be arbitrarily increased or decreased.

1 is a cross-sectional view showing an image sensor according to an embodiment of the present invention.

2 is a cross-sectional view showing a schematic light passing image sensor in accordance with an embodiment of the present invention.

FIG. 3 is a flow chart showing a method of forming an image sensor according to an embodiment of the present invention.

[Fig. 4a] to [Fig. 4g] are cross-sectional views of an image sensor corresponding to the steps of a method of forming an image sensor according to an embodiment of the present invention.

The disclosure provides many different embodiments or examples for implementing the various features disclosed herein. In order to simplify the disclosure, specific examples of components and layouts are described below. Of course, these are merely examples and are not intended to limit the disclosure. For example, if it is mentioned in the following description that the first feature is formed on the second feature, this may include an embodiment in which the first feature is in direct contact with the second feature; this may also include between the first feature and the second feature. Embodiments of other features are formed that make the first feature not in direct contact with the second feature. Moreover, the disclosure may repeat the symbols and/or text in various examples. This repetition is for the purpose of brevity and clarity, but does not in itself determine the relationship between the various embodiments and/or arrangements discussed.

Furthermore, spatially relative terms such as "lower", "lower", """"""""""" These spatially relative terms, in addition to the directions depicted in the figures, also cover different orientations of the device in use or operation. These devices can also be rotated (e.g., rotated 90 degrees or rotated to other directions), and the spatially relative descriptions used herein can also be interpreted accordingly.

1 is a cross-sectional view of an image sensor 100 in accordance with an embodiment of the present invention. As shown in FIG. 1 , the image sensor 100 includes a visible light receiving unit 110 and an infrared light receiving unit 120 . The visible light receiving unit 110 is configured to receive visible light, and the infrared light receiving unit 120 is configured to receive infrared light.

As shown in FIG. 1 , the visible light receiving unit 110 includes a visible light sensing layer 112 , an infrared light cutoff (IR Cut) filter layer 114 , an infrared light cut filter grid ( Grid ) 116 , and a color filter layer 118 . The color filter layer 118 is disposed on the infrared light cut filter layer 114, and the infrared light cut filter layer 114 is disposed on the visible light sensing layer 112 to provide colored light to the visible light sensing layer 112. The visible light sensing layer 112 is configured to receive visible light to generate a main image signal accordingly. In this embodiment, the visible light sensing layer 112 includes at least one photodiode to sense colored light. The photodiode can be a complementary metal oxide semiconductor (CMOS) diode. However, embodiments of the invention are not limited thereto.

A color filter layer 118 is filled in the infrared light cut filter grid 116 to provide colored light. In the present embodiment, the color filter layer 118 includes a red filter unit 118a, a blue filter unit 118b, and a green filter unit 118c, but embodiments of the present invention are not limited thereto.

The infrared light cut filter layer 114 is used to cut off infrared light. In other words, when light passes through the infrared light cut filter layer 114, the infrared light cut filter layer 114 blocks the transmission of infrared light. In the present embodiment, the infrared light cut filter layer 114 blocks light having a wavelength of more than 850 nm, but embodiments of the present invention are not limited thereto.

As shown in FIG. 1 , the infrared light receiving unit 120 includes an infrared light sensing layer 122 , a first filter layer 124 , and a second filter layer 126 . The second filter layer 126 is disposed on the first filter layer 124 , and the first filter layer 124 is disposed on the infrared light sensing layer 122 to provide infrared light to the infrared light sensing layer 122 . The infrared light sensing layer 122 is configured to receive infrared light to generate an auxiliary image signal accordingly. In this embodiment, the infrared light sensing layer 122 includes at least one photodiode to sense infrared light. The photodiode can be a complementary MOS diode. However, embodiments of the invention are not limited thereto.

In this embodiment, one of the first filter layer 124 and the second filter layer 126 is an infrared light penetrating (IR Pass) filter layer, and the first filter layer 124 and the second filter layer 126 The other is a white filter layer or an infrared light penetrating filter layer. Infrared light penetrates the filter layer to intercept visible light. In other words, when light passes through the infrared light through the filter layer, the infrared light penetrates the filter layer to block the transmission of visible light. In the present embodiment, the infrared light penetrating the filter layer blocks light having a wavelength of less than 850 nm, but embodiments of the present invention are not limited thereto. A white filter layer is used to pass infrared light. In the present embodiment, the white filter layer is a white photoresist, but embodiments of the present invention are not limited thereto.

As shown in FIG. 1, an infrared light cut filter grid 116 is disposed on the infrared light cut filter layer 114 for purifying visible light. 2 is a cross-sectional view of a schematic light passing image sensor 100 in accordance with an embodiment of the present invention. As shown in FIG. 2, the light passing through the color filter unit (such as the green filter unit 118c) passes through the color filter unit longitudinally, and laterally enters the adjacent color filter unit or the adjacent second filter. Light layer 126. The infrared light cut filter grid 116 is used to block infrared light that passes through the color filter layer 118 laterally, thereby purifying the visible light received by the image sensor 100. Therefore, the visible light received by the image sensor 100 has less noise.

As shown in FIG. 1, the visible light receiving unit 110 and the infrared light receiving unit 120 further include a wafer layer WA, a spacer layer SP, and a microlens layer ML. The wafer layer WA is used to provide a substrate on which the infrared light cut filter layer 114 and the first filter layer 124 are formed. In the present embodiment, the wafer layer WA is a glass wafer, but embodiments of the present invention are not limited thereto.

The spacer layer SP is located on the color filter layer 118 and the second filter layer 126 to provide a flat surface on which the microlens layer ML is disposed. It should be noted that, in this embodiment, the sum of the thickness of the infrared light cut filter layer 114 and the thickness of the infrared light cut filter grid 116 and the color filter layer 118 is substantially equal to the thickness of the first filter layer 124. The sum of the thicknesses of the second filter layer 126. The microlens layer ML is used to collect infrared light and visible light. Specifically, when the image sensor 100 is used to sense an object such as an iris, the object is focused through the microlens layer ML. Furthermore, the focus of the image sensor 100 can be adjusted by changing the thickness of the microlens layer ML.

It should be noted that the material of the microlens layer ML may be epoxy resin, optical glue, polymethylmethacrylates (PMMAs), polyurethane plastics (PUs), polydimethylsiloxane (PDMS) or other thermosetting. Or a light-hardened light-transmitting material, but embodiments of the invention are not limited thereto.

Compared to the conventional image sensor, since the infrared light cut filter grid 116 provides a suitable structure to fill the color filter layer 118 therein, the image sensor 100 does not require a flat layer, thereby reducing the image sensor. 100 received light path of visible light and infrared light. Therefore, the visible light and the infrared light received by the image sensor 100 have a small loss of light intensity. In addition, compared to the conventional image sensor, since the infrared light cut filter grid 116 is used to purify visible light, the visible light received by the image sensor 100 has less noise.

Please refer to FIG. 3 and FIG. 4a to FIG. 4g. FIG. 3 is a flow chart showing a method 1000 of forming an image sensor 100 according to an embodiment of the invention. 4a-4g are cross-sectional views of image sensor 100 corresponding to steps 1100-1600 of method 1000 of forming image sensor 100, in accordance with an embodiment of the present invention. Method 1000 begins at step 1100. In step 1100, the first component 100A as shown in FIG. 4a includes a visible light sensing layer 112, an infrared light sensing layer 122, a wafer layer WA, and a first filter layer 124.

As shown in FIG. 4b, in step 1200 of method 1000, a first infrared light-cut filter layer 114E is applied over the first component 100A. Next, as shown in FIG. 4c, in step 1300 of the method 1000, a plurality of photoresists PR are patterned on the first infrared light-cut filter layer 114E located in the visible light receiving portion 110A to form the second element 100B.

As shown in FIG. 4d, in step 1400 of method 1000, second element 100B is etched through an etch process until first filter layer 124 is exposed. Specifically, the plurality of photoresists PR are etched such that the remaining first infrared light-cut filter layers 114E have substantially the same upper surface as the outer shape of the plurality of photoresists PR, thereby forming the same as shown in FIG. 4e. The infrared light cut filter grid 116 and the infrared light cut filter layer 114. It should be noted that the infrared light cut filter grating 116 and the infrared light cut filter layer 114 are formed by etching the first infrared light cut filter layer 114E, so the infrared light cut filter grid 116 and the infrared light cut filter layer The 114 series is integrally formed.

As shown in FIG. 4f, in step 1500 of method 1000, a plurality of photoresists PR are removed. Next, as shown in FIG. 4g, in step 1600 of method 1000, color filter layer 118 is filled in infrared light-cut filter grid 116, and second filter layer 126 is formed on first filter layer 124. Finally, the spacer layer SP and the microlens layer ML are sequentially disposed to form the image sensor 100 as shown in FIG.

It can be seen from the above that the structure of the image sensor of the present invention comprises an infrared light cut filter grid to purify visible light and provide a color filter layer, so that the visible light received by the image sensor of the present invention has less noise. In addition, the structure of the image sensor of the present invention does not require a flat layer, so that the visible light and infrared light received by the image sensor of the present invention have a small loss of light intensity.

The features of several embodiments are summarized above, and those skilled in the art will be able to understand the aspects of the disclosure. Those skilled in the art will appreciate that the present disclosure can be readily utilized as a basis for designing or modifying other processes and structures, thereby achieving the same objectives and/or achieving the same advantages as the embodiments described herein. . It should be understood by those skilled in the art that the invention may be made without departing from the spirit and scope of the disclosure.

Claims (20)

 An image sensor includes: an infrared light receiving portion for receiving an infrared light; and a visible light receiving portion for receiving a visible light, wherein the visible light receiving portion includes an infrared light cut filter grid (Grid), The infrared light cut filter grid is used to purify the visible light.    The image sensor of claim 1, wherein the visible light receiving portion further comprises: a visible light diode; an infrared light blocking filter layer disposed on the visible light diode; and a color filter The light layer is filled in the infrared light cut filter grid; wherein the infrared light cut filter grid is disposed on the infrared light cut filter layer, the visible light passes through the color filter layer, and the infrared light cut filter grid And the infrared light cut-off filter layer is received by the visible light diode.    The image sensor of claim 2, wherein the infrared light receiving portion comprises: an infrared light photodiode; a first filter layer disposed on the infrared light photodiode; and a first The second filter layer is disposed on the first filter layer; wherein the infrared light passes through the second filter layer and the first filter layer and is received by the infrared photodiode.    The image sensor of claim 3, wherein one of the first filter layer and the second filter layer is an infrared light penetrating filter layer, the first filter layer and The other of the second filter layers is a white filter layer or the infrared light penetrating filter layer.    The image sensor of claim 3, further comprising a wafer layer disposed on the infrared light diode and the visible light diode, wherein a first portion of the wafer layer is located The visible light receiving portion has a second portion of the wafer layer located in the infrared light receiving portion.    The image sensor of claim 5, wherein the first portion of the wafer layer is between the infrared light-cut filter layer and the visible light diode.    The image sensor of claim 5, wherein the second portion of the wafer layer is between the first filter layer and the infrared light diode.    The image sensor of claim 2, wherein the color filter layer comprises a red filter unit, a green filter unit, and a blue filter unit.    The image sensor of claim 8, wherein the red filter unit, the green filter unit, and the blue filter unit are each filled in the infrared light cut filter grid.    The image sensor of claim 1, further comprising a microlens layer for collecting the visible light and the infrared light.    The image sensor of claim 10, wherein the microlens layer is located at an uppermost layer of the image sensor.    The image sensor of claim 10, wherein the microlens layer is located in the visible light receiving portion and the infrared light receiving portion.    The image sensor of claim 10, further comprising a spacer layer for providing a flat surface, wherein the microlens layer is disposed on the flat surface.    The image sensor of claim 13, wherein the spacer layer is located in the visible light receiving portion and the infrared light receiving portion.    A method of forming an image sensor, comprising: providing a first component, the first component comprising a visible light receiving portion and an infrared light receiving portion, wherein the first component comprises: a wafer layer located at the visible light receiving portion And the first light filter layer is located on the wafer layer, wherein the first filter layer is located in the infrared light receiving portion; and a first infrared light cut filter layer is coated on the first An element, wherein the first infrared light-cut filter layer is located in the visible light receiving portion and the infrared light receiving portion; and patterning a plurality of photoresists on the first infrared light-cut filter layer in the visible light receiving portion, Forming a second component; etching the second component until the first filter layer is exposed to form an infrared light cut filter layer and an infrared light cut filter grid located in the visible light receiving portion, wherein the infrared light cutoff a filter grid is disposed on the infrared light cut filter layer; a color filter layer is filled in the infrared light cut filter grid, and a second filter layer is formed on the first filter layer; A spacer layer and a microlens layer are disposed on the color filter layer and the second filter layer, wherein the spacer layer and the microlens layer are located in the visible light receiving portion and the infrared light receiving portion.    The method of claim 15, wherein the first component further comprises: a visible light photodiode disposed in the visible light receiving portion; and an infrared light photodiode disposed in the infrared light receiving portion; wherein the crystal A circular layer is located on the infrared light dipole and the visible light diode.    The method of claim 15, wherein one of the first filter layer and the second filter layer is an infrared light penetrating filter layer, the first filter layer and the second The other of the filter layers is a white filter layer or the infrared light penetrates the filter layer.    The method of claim 15, wherein the color filter layer comprises a red filter unit, a green filter unit, and a blue filter unit.    The method of claim 18, wherein the red filter unit, the green filter unit, and the blue filter unit are each filled in the infrared light cut filter grid.    The method of claim 15, wherein the infrared light cut filter layer is integrally formed with the infrared light cut filter grid.