WO2022261977A1 - 前照式图像传感器 - Google Patents

前照式图像传感器 Download PDF

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Publication number
WO2022261977A1
WO2022261977A1 PCT/CN2021/101073 CN2021101073W WO2022261977A1 WO 2022261977 A1 WO2022261977 A1 WO 2022261977A1 CN 2021101073 W CN2021101073 W CN 2021101073W WO 2022261977 A1 WO2022261977 A1 WO 2022261977A1
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Prior art keywords
photosensitive layer
photosensitive
image sensor
color filter
illuminated image
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PCT/CN2021/101073
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English (en)
French (fr)
Inventor
陈宇超
程凯
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苏州晶湛半导体有限公司
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Application filed by 苏州晶湛半导体有限公司 filed Critical 苏州晶湛半导体有限公司
Priority to PCT/CN2021/101073 priority Critical patent/WO2022261977A1/zh
Priority to CN202180099522.XA priority patent/CN117581372A/zh
Publication of WO2022261977A1 publication Critical patent/WO2022261977A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures

Definitions

  • the present application relates to the technical field of semiconductors, and in particular to a front-illuminated image sensor.
  • the image sensor uses the photoelectric conversion function of the photoelectric device to convert the light image on the photosensitive surface into an electrical signal proportional to the light image.
  • the image sensor is a functional device that divides the light image on its light-receiving surface into many small units and converts it into usable electrical signals.
  • Image sensors are divided into photoconductive camera tubes and solid-state image sensors. Compared with light-guided camera tubes, solid-state image sensors have the characteristics of small size, light weight, high integration, high resolution, low power consumption, long life, and low price, so they have been widely used in various industries.
  • the shortcomings of the back-illuminated image sensor are: 1. It is necessary to fabricate photodiodes for photoelectric conversion and electrical interconnection structures on the front of the silicon wafer, and fabricate light filtering structures and lenses on the back of the silicon wafer. The process is complex and the photodiodes on the front require Alignment with the back filter structure and lens will result in a lower yield rate of the back-illuminated image sensor; second, the photodiode occupies a larger area, which makes the space for the charge storage area (Charge Storage) and storage capacitor relatively limited. It increases the design difficulty for High-Dynamic Range (HDR) performance and global shutter (Global Shutter) capacitor design; 3. When the light propagates in the silicon chip to the photodiode, the crosstalk is large, and deep The trench isolation structure isolates light transmitted to adjacent photodiodes, and the process is complicated.
  • HDR High-Dynamic Range
  • Global Shutter global shutter
  • the purpose of the present invention is to provide a front-illuminated image sensor to solve the deficiencies in the related art.
  • the present invention provides a front-illuminated image sensor, comprising:
  • the photosensitive unit located above the substrate;
  • the photosensitive unit includes photosensitive layers of different colors, and one color photosensitive layer is electrically connected to one charge storage region;
  • the color filter unit located on a side of the photosensitive unit away from the substrate; the color filter unit includes color filter layers of different colors, and one color filter layer corresponds to the one color photosensitive layer;
  • the lens structure is located on a side of the color filter unit away from the base.
  • the photosensitive unit includes a red photosensitive layer, a green photosensitive layer and a blue photosensitive layer, and the material of the red photosensitive layer, the green photosensitive layer and the blue photosensitive layer is GaN containing In The base material, and wherein the composition of In is different in size, so as to generate or not generate photosensitive charges according to the wavelength of the received light and store them in the corresponding charge storage region.
  • composition of In in the red photosensitive layer ranges from 0.4 to 0.6;
  • composition of In in the green photosensitive layer ranges from 0.2 to 0.3;
  • composition range of In in the blue photosensitive layer is 0.01-0.1.
  • the source region or drain region of at least one transistor is the charge storage region; there is a metal interconnection layer between the substrate and the photosensitive unit, and the metal interconnection A layered metal interconnect structure is used to electrically connect the plurality of transistors.
  • a conductive plug is provided in the metal interconnection layer, a first end of the conductive plug is connected to the one color photosensitive layer, and a second end is electrically connected to the charge storage region.
  • the first end of the conductive plug is connected to the sidewall of the one color photosensitive layer.
  • first light-shielding structure between the photosensitive layers of different colors, and/or a second light-shielding structure between the color filter layers of different colors.
  • the material of the first light-shielding structure is metal molybdenum, an alloy of metal molybdenum, metal aluminum or an alloy of metal aluminum, and/or the second light-shielding structure is a black matrix.
  • first light-shielding structure between the photosensitive layers of different colors, and the first light-shielding structure is also located between the color filter layers of different colors.
  • the material of the first light-shielding structure is metal molybdenum, an alloy of metal molybdenum, metal aluminum, an alloy of metal aluminum, or a black matrix.
  • the photosensitive unit is located above the substrate, the color filter unit is located on the side of the photosensitive unit away from the substrate, and the lens structure is located on the side of the color filter unit away from the substrate.
  • the image sensor is a front-illuminated image sensor, avoiding making structures on the back of the substrate. Therefore, the alignment of the front structure and the back structure is avoided, the process is simple, and the yield rate is high;
  • the photosensitive unit is located above the substrate instead of spreading on the surface of the substrate, so the charge storage area and storage capacitor space can be designed large enough to obtain more Large full well capacity brings high dynamic range improvement, and naturally has the design conditions of global shutter; 3.
  • a color photosensitive layer is electrically connected to a charge storage area, which greatly reduces the crosstalk caused by the light propagation process.
  • FIG. 1 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a first embodiment of the present invention
  • FIG. 2 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a second embodiment of the present invention
  • FIG. 3 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a third embodiment of the present invention.
  • FIG. 4 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a fourth embodiment of the present invention.
  • the first shading structure 111 The second shading structure 121
  • FIG. 1 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a first embodiment of the present invention.
  • the front-illuminated image sensor 1 includes:
  • the substrate 10 has a plurality of charge storage regions 101;
  • the photosensitive unit 11 is located above the substrate 10; the photosensitive unit 11 includes photosensitive layers of different colors, and one color photosensitive layer is electrically connected to one charge storage region 101;
  • the color filter unit 12 is located on the side of the photosensitive unit 11 away from the substrate 10; the color filter unit 12 includes different color filter layers, and a color filter layer corresponds to a color photosensitive layer; and
  • the lens structure 13 is located on a side of the color filter unit 12 away from the substrate 10 .
  • the base 10 may be a single crystal silicon substrate.
  • the charge storage region 101 can be a floating diffusion region (Floating Diffusion, FD for short), for example, an n-type lightly doped region formed in a p-type well can be used as a floating diffusion region.
  • FD floating Diffusion
  • the photosensitive unit 11 includes a red photosensitive layer 11a, a green photosensitive layer 11b, and a blue photosensitive layer 11c, and the materials of the red photosensitive layer 11a, the green photosensitive layer 11b, and the blue photosensitive layer 11c are all GaN-based materials containing In, and wherein The components of In have different sizes, so as to generate or not generate photosensitive charges and store them in the corresponding charge storage region 101 according to the wavelength of the received light.
  • the In composition of the red photosensitive layer 11a may be larger than the In composition of the green photosensitive layer 11b, and the In composition of the green photosensitive layer 11b may be larger than the In composition of the blue photosensitive layer 11c.
  • the photosensitive unit 11 is formed above the substrate 10 .
  • a mask layer can be formed on the substrate 10 .
  • a plurality of first openings are first formed in the mask layer, corresponding to the red photosensitive layer 11 a of each photosensitive unit 11 ; and the red photosensitive layer 11 a is epitaxially grown in each first opening.
  • a plurality of second openings are then formed in the mask layer, corresponding to the green photosensitive layer 11b of each photosensitive unit 11; the green photosensitive layer 11b is epitaxially grown in each second opening.
  • a plurality of third openings are formed in the mask layer, corresponding to the blue photosensitive layer 11c of each photosensitive unit 11; the blue photosensitive layer 11c is epitaxially grown in each third opening.
  • the sizes of the first opening, the second opening and the third opening can be controlled, for example, they can all be the same size.
  • the composition of the In element can be different by controlling different process conditions.
  • the mask layer has three openings corresponding to one photosensitive unit 11 , and the red photosensitive layer 11 a , the green photosensitive layer 11 b and the blue photosensitive layer 11 c correspond to one opening respectively.
  • the opening corresponding to the red photosensitive layer 11a is smaller than the opening corresponding to the green photosensitive layer 11b
  • the opening corresponding to the green photosensitive layer 11b is smaller than the opening corresponding to the blue photosensitive layer 11c.
  • the size of the opening is different, and the flow rate of the reaction gas in each opening is different when growing the photosensitive layer, so that the incorporation rate of In element and Ga element is different, that is, the incorporation efficiency of In element is different, which makes the In element in the grown photosensitive layer
  • the proportions of the components are different.
  • the smaller the opening the faster the growth rate of GaN, the basic material of the photosensitive layer in the opening, the better the selectivity of the doping of the In element, and the greater the incorporation rate of the In element than the doping rate of the Ga element, therefore , the smaller the opening, the higher the composition of In element in the photosensitive layer InGaN.
  • composition range of In in the red photosensitive layer 11a may be 0.4-0.6, and the wavelength range of light required to generate photosensitive current may be 400nm-720nm.
  • the composition of In in the green photosensitive layer 11b may range from 0.2 to 0.3, and the wavelength range of light required to generate photosensitive current may range from 400nm to 600nm.
  • composition range of In in the blue photosensitive layer 11c may be 0.01-0.1, and the wavelength range of light required for generating photosensitive current may be 400nm-500nm.
  • the composition of In in the red photosensitive layer 11a refers to the percentage of the amount of In in the sum of the amounts of all positively charged elements in the red photosensitive layer 11a.
  • the material of the red photosensitive layer 11a is InGaN
  • the composition of In refers to: the percentage of the amount of In material to the sum of the amount of In material and the amount of Ga material
  • the material of the red light photosensitive layer 11a is InAlGaN
  • the composition of In refers to the percentage of the amount of In in the sum of the amount of In, the amount of Al, and the amount of Ga.
  • composition of In in the green photosensitive layer 11b refers to the percentage of the amount of In in the sum of the amounts of all positively charged elements in the green photosensitive layer 11b.
  • composition of In in the blue photosensitive layer 11c refers to the percentage of the amount of In in the sum of the amounts of all positively charged elements in the blue photosensitive layer 11c.
  • each numerical range includes the endpoint value.
  • a red color filter layer 12a is arranged above the red photosensitive layer 11a
  • a green color filter layer 12b is arranged above the green photosensitive layer 11b
  • a blue color filter layer 11c is arranged above the blue photosensitive layer 11c, therefore, if blue light is irradiated, Only the blue photosensitive layer 11c can generate photosensitive signals. If green light is irradiated, only the green photosensitive layer 11b can generate photosensitive signals. If red light is irradiated, only the red photosensitive layer 11a can generate a photosensitive signal.
  • the red photosensitive layer 11a, and/or the green photosensitive layer 11b, and/or the blue photosensitive layer 11c has a single-layer structure.
  • the red photosensitive layer 11a, and/or the green photosensitive layer 11b, and/or the blue photosensitive layer 11c can also be a stacked structure, such as a multi-quantum well layer, including two barrier layers and interposed The potential well layer in the two barrier layers.
  • the color filter unit 12 includes a red color filter layer 12a, a green color filter layer 12b and a blue color filter layer 11c.
  • the lens structure 13 includes a plurality of lenses, one lens is arranged above the color filter layer of each color.
  • first light-shielding structure 111 between the photosensitive layers of different colors
  • second light-shielding structure 121 between the color filter layers of different colors.
  • the material of the first light-shielding structure 111 may be metal molybdenum, alloy of metal molybdenum, metal aluminum or metal alloy of metal, and the second light-shielding structure 121 may be a black matrix.
  • insulating spacers may be provided on the sidewalls of the first light-shielding structure 111 .
  • the insulating spacer is made of, for example, silicon nitride or silicon dioxide.
  • the image sensor is a front-illuminated image sensor 1, which can avoid making structures on the back of the substrate 10, thus avoiding the alignment of the front structure and the back structure, with simple process and high yield;
  • second, one color photosensitive The layers are electrically connected to a charge storage region 101, which greatly reduces the crosstalk caused during light propagation.
  • FIG. 2 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a second embodiment of the present invention.
  • the front-illuminated image sensor 2 of the second embodiment is substantially the same as the front-illuminated image sensor 1 of the first embodiment, the only difference is that there are multiple transistors 102 on the substrate 10, and at least one transistor
  • the source region or drain region is the charge storage region 101 ; there is a metal interconnection layer 14 between the substrate 10 and the photosensitive unit 11 , and the metal interconnection structure 141 of the metal interconnection layer 14 is used to electrically connect a plurality of transistors 102 .
  • the transistor 102 may include: a transfer transistor, a reset transistor, a source follower transistor and a row selection transistor.
  • the source of the transfer transistor is electrically connected to a color photosensitive layer through the metal interconnection structure 141, and the drain is a floating diffusion region, so the transfer transistor is used to transfer photoelectric charges from a color photosensitive layer to the floating diffusion region.
  • the source of the reset transistor is the floating diffusion region, and the drain is electrically connected to the power supply voltage line through the metal interconnection structure 141 , thus the reset transistor is used to reset the floating diffusion region to the power supply voltage VDD.
  • the gate of the source follower transistor is electrically connected to the floating diffusion region, the source is electrically connected to the power supply voltage VDD, and the drain is electrically connected to the source of the row selection transistor.
  • the gate of the row selection transistor is electrically connected to the row scan line for outputting the drain voltage of the source follower transistor in response to an address signal.
  • the first end of the conductive plug 142 is connected to a color photosensitive layer, and the second end is electrically connected to the charge storage region 101 .
  • the first end of the conductive plug 142 is connected to the bottom wall of a color photosensitive layer.
  • the photosensitive unit 11 is located above the substrate 10 instead of being spread flat on the surface of the substrate 10. Therefore, a large design space can be provided for the charge storage region 101 and the storage capacitor, thereby obtaining a larger full-well capacity, with To improve the high dynamic range, and naturally have the design conditions of the global shutter.
  • FIG. 3 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a third embodiment of the present invention.
  • the front-illuminated image sensor 3 of the third embodiment is substantially the same as the front-illuminated image sensor 2 of the second embodiment, the only difference is that the first end of the conductive plug 142 is connected to a color The sidewall of the photosensitive layer. Studies have shown that the current flowing in the plane of the GaN-based photosensitive layer containing In is greater than the current flowing in the thickness direction. Therefore, the conductive plug 142 connected to the side wall of the photosensitive layer can increase the amount of photoelectric charges transferred.
  • the sidewall of the photosensitive layer to which the first end of the conductive plug 142 is connected is close to the first light shielding structure 111 .
  • FIG. 4 is a schematic cross-sectional structure diagram of a front-illuminated image sensor according to a fourth embodiment of the present invention.
  • the front-illuminated image sensor 4 of the fourth embodiment is substantially the same as the front-illuminated image sensors 1, 2, and 3 of the first, second, and third embodiments, and the only difference is That is: the first light shielding structure 111 is also located between the color filter layers of different colors.
  • the material of the first light-shielding structure 111 is metal molybdenum, metal molybdenum alloy, metal aluminum, metal aluminum alloy or black matrix.
  • the height of the first light shielding structure 111 may be relatively high. At this time, the fabrication of the second light shielding structure 121 can be omitted.

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Abstract

本申请提供了一种前照式图像传感器，包括：基底、感光单元、滤色单元与透镜结构；基底具有多个电荷存储区；感光单元位于基底上方，感光单元包括不同颜色感光层，一个颜色感光层电连接一个电荷存储区；滤色单元位于感光单元远离基底的一侧，滤色单元包括不同颜色滤色层，一个颜色滤色层对应一个颜色感光层；透镜结构位于滤色单元远离基底的一侧。本发明的前照式图像传感器，一、工艺简单、良率高；二、电荷存储区和存储电容空间可以设计足够大，从而获得更大满井容量，带来高动态范围提升，并天然具备全局快门设计条件；三、可以减少光线传播过程中引起的串扰。

Description

前照式图像传感器 技术领域
本申请涉及半导体技术领域，尤其涉及一种前照式图像传感器。
背景技术
图像传感器是利用光电器件的光电转换功能将感光面上的光像转换为与光像成相应比例关系的电信号。与光敏二极管、光敏三极管等“点”光源的光敏元件相比，图像传感器是将其受光面上的光像，分成许多小单元，将其转换成可用的电信号的一种功能器件。图像传感器分为光导摄像管和固态图像传感器。与光导摄像管相比，固态图像传感器具有体积小、重量轻、集成度高、分辨率高、功耗低、寿命长、价格低等特点，因此在各个行业得到了广泛应用。
目前的图像传感器多是采用背照式CMOS结构。背照式图像传感器的不足之处在于：一、需要在硅片的正面制作光电转换用光电二极管与电互连结构，在硅片背面制作滤光结构与透镜，工艺复杂且正面的光电二极管需与背面滤光结构、透镜对准，这会造成背照式图像传感器良率较低；二、光电二极管所占面积较大，这使得电荷存储区(Charge Storage)和存储电容的空间较为有限，为高动态范围(High-Dynamic Range，简称HDR)性能、全局快门(Global Shutter)的电容设计增加了设计难度；三、光线在硅片内传播至光电二极管过程中，串扰较大，需制作深沟槽隔离结构隔开传播至相邻光电二极管的光线，工艺复杂。
此外，光电二极管中，随着动态范围要求增高，全局快门应用普及，更大的满井容量与更大的存储电容要求越来越高。目前市面上解决方案主 要集中在光电二极管与存储电容重新设计并修改电路与之匹配，并未实质改变总存储空间，还增加了电路设计难度；背照式的要求也增加了工艺的难度。
发明内容
本发明的发明目的是提供一种前照式图像传感器，以解决相关技术中的不足。
为实现上述目的，本发明提供一种前照式图像传感器，包括：
基底，所述基底具有多个电荷存储区；
感光单元，位于所述基底上方；所述感光单元包括不同颜色感光层，一个颜色感光层电连接一个所述电荷存储区；
滤色单元，位于所述感光单元远离所述基底的一侧；所述滤色单元包括不同颜色滤色层，一个颜色滤色层对应所述一个颜色感光层；以及
透镜结构，位于所述滤色单元远离所述基底的一侧。
可选地，所述感光单元包括红光感光层、绿光感光层以及蓝光感光层，所述红光感光层、所述绿光感光层以及所述蓝光感光层的材料都为含In的GaN基材料，且其中In的组分大小不同，以根据接收到的光的波长不同产生或不产生感光电荷并存入对应的所述电荷存储区。
可选地，所述红光感光层中In的组分范围为0.4～0.6；
所述绿光感光层中In的组分范围为0.2～0.3；
所述蓝光感光层中In的组分范围为0.01～0.1。
可选地，所述基底上具有多个晶体管，至少一个晶体管的源区或漏区为所述电荷存储区；所述基底与所述感光单元之间具有金属互连层，所述金 属互连层的金属互连结构用于电连接所述多个晶体管。
可选地，所述金属互连层中具有导电插塞，所述导电插塞的第一端连接所述一个颜色感光层，第二端电连接所述电荷存储区。
可选地，所述导电插塞的第一端连接于所述一个颜色感光层的侧壁。
可选地，所述不同颜色感光层之间具有第一遮光结构，和/或所述不同颜色滤色层之间具有第二遮光结构。
可选地，所述第一遮光结构的材料为金属钼、金属钼的合金、金属铝或金属铝的合金，和/或所述第二遮光结构为黑矩阵。
可选地，所述不同颜色感光层之间具有第一遮光结构，所述第一遮光结构还位于所述不同颜色滤色层之间。
可选地，所述第一遮光结构的材料为金属钼、金属钼的合金、金属铝、金属铝的合金或为黑矩阵。
与现有技术相比，本发明的有益效果在于：
一、感光单元位于基底上方，滤色单元位于感光单元远离基底的一侧，透镜结构位于滤色单元远离基底的一侧，换言之，图像传感器为前照式图像传感器，避免在基底背面制作结构，因而避免了正面结构与背面结构对准，工艺简单、良率高；二、感光单元位于基底上方而不是平摊于基底的表面，因而电荷存储区和存储电容空间可以设计足够大，从而获得更大的满井容量，带来高动态范围的提升，并天然具备全局快门的设计条件；三、一个颜色感光层电连接一个电荷存储区，极大减少了光线传播过程中引起的串扰。
附图说明
图1是本发明第一实施例的前照式图像传感器的截面结构示意图；
图2是本发明第二实施例的前照式图像传感器的截面结构示意图；
图3是本发明第三实施例的前照式图像传感器的截面结构示意图；
图4是本发明第四实施例的前照式图像传感器的截面结构示意图。
为方便理解本发明，以下列出本发明中出现的所有附图标记：
前照式图像传感器1、2、3、4   基底10
电荷存储区101                感光单元11
红光感光层11a                绿光感光层11b
蓝光感光层11c                滤色单元12
红光滤色层12a                绿光滤色层12b
蓝光滤色层11c                透镜结构13
第一遮光结构111              第二遮光结构121
晶体管102                    金属互连层14
金属互连结构141              导电插塞142
具体实施方式
为使本发明的上述目的、特征和优点能够更为明显易懂，下面结合附图对本发明的具体实施例做详细的说明。
图1是本发明第一实施例的前照式图像传感器的截面结构示意图。
参照图1所示，前照式图像传感器1包括：
基底10，基底10具有多个电荷存储区101；
感光单元11，位于基底10上方；感光单元11包括不同颜色感光层，一个颜色感光层电连接一个电荷存储区101；
滤色单元12，位于感光单元11远离基底10的一侧；滤色单元12包括 不同颜色滤色层，一个颜色滤色层对应一个颜色感光层；以及
透镜结构13，位于滤色单元12远离基底10的一侧。
基底10可以为单晶硅衬底。电荷存储区101可以为浮动扩散区(Floating Diffusion，简称FD)，例如形成在p型阱内的n型轻掺杂区可作为浮动扩散区。
感光单元11包括红光感光层11a、绿光感光层11b以及蓝光感光层11c，红光感光层11a、绿光感光层11b以及蓝光感光层11c的材料都为含In的GaN基材料，且其中In的组分大小不同，以根据接收到的光的波长不同产生或不产生感光电荷并存入对应的电荷存储区101。
红光感光层11a的In的组分可以大于绿光感光层11b的In的组分，绿光感光层11b的In的组分可以大于蓝光感光层11c的In的组分。
本实施例中，参照图1所示，感光单元11形成在基底10的上方。红光感光层11a、绿光感光层11b以及蓝光感光层11c在外延生长前，可以在基底10上形成掩膜层。一个可选方案中，先在掩膜层内形成多个第一开口，对应各个感光单元11的红光感光层11a；在各个第一开口内外延生长红光感光层11a。再在掩膜层内形成多个第二开口，对应各个感光单元11的绿光感光层11b；在各个第二开口内外延生长绿光感光层11b。之后在掩膜层内形成多个第三开口，对应各个感光单元11的蓝光感光层11c；在各个第三开口内外延生长蓝光感光层11c。第一开口、第二开口以及第三开口的大小可以控制，例如可以大小都相同。分别外延生长红光感光层11a、绿光感光层11b以及蓝光感光层11c时，可通过控制工艺条件不同，使得In元素的组分各不相同。
另一个可选方案中，掩膜层具有对应一个感光单元11的三个开口，红光感光层11a、绿光感光层11b以及蓝光感光层11c分别对应一个开口。其中，对应红光感光层11a的开口小于对应绿光感光层11b的开口，对应绿光感光层11b的开口小于对应蓝光感光层11c的开口。开口的大小不同，生长感光层时 各开口内的反应气体的流速不同，从而In元素与Ga元素的掺入速率不同，即In元素的掺入效率不同，这使得生长的感光层中In元素的组分占比不同。具体地，开口越小，开口内感光层的基础材料GaN的生长速度会变快，In元素的掺杂具有更好的选择性，In元素的掺入速率越大于Ga元素的掺入速率，因此，开口越小，感光层InGaN中In元素的组分越高。
红光感光层11a中In的组分范围可以为0.4～0.6，产生感光电流所需的光的波长范围可以为400nm～720nm。
绿光感光层11b中In的组分范围可以为0.2～0.3，产生感光电流所需的光的波长范围可以为400nm～600nm。
蓝光感光层11c中In的组分范围可以为0.01～0.1，产生感光电流所需的光的波长范围可以为400nm～500nm。
需要说明的是，红光感光层11a中In的组分是指：In的物质的量占红光感光层11a中所有带正电荷的元素的物质的量之和的百分比。例如：红光感光层11a的材料为InGaN，In的组分是指：In的物质的量占In的物质的量与Ga的物质的量之和的百分比；红光感光层11a的材料为InAlGaN，In的组分是指：In的物质的量占In的物质的量、Al的物质的量与Ga的物质的量之和的百分比。
绿光感光层11b中In的组分是指：In的物质的量占绿光感光层11b中所有带正电荷的元素的物质的量之和的百分比。
蓝光感光层11c中In的组分是指：In的物质的量占蓝光感光层11c中所有带正电荷的元素的物质的量之和的百分比。
此外，本实施例中，各数值范围均包括端点值。
由于红光感光层11a上方设置有红光滤色层12a、绿光感光层11b上方设置有绿光滤色层12b，蓝光感光层11c上方设置有蓝光滤色层11c，因而，若蓝光照射，仅蓝光感光层11c能产生感光电信号。若绿光照射，仅绿光感光 层11b能产生感光电信号。若红光照射，仅红光感光层11a能产生感光电信号。
本实施例中，红光感光层11a、和/或绿光感光层11b、和/或蓝光感光层11c为单层结构。其它实施例中，红光感光层11a、和/或绿光感光层11b、和/或蓝光感光层11c也可以为叠层结构，例如为多量子阱层，包括两层势垒层以及夹设于两层势垒层中的势阱层。
本实施例中，对应地，滤色单元12包括红光滤色层12a、绿光滤色层12b以及蓝光滤色层11c。
透镜结构13包括多个透镜，每个颜色的滤色层上方设置一透镜。
此外，本实施例中，不同颜色感光层之间具有第一遮光结构111，不同颜色滤色层之间具有第二遮光结构121。在基底10上外延生长红光感光层11a、绿光感光层11b以及蓝光感光层11c之前，可以先在基底10上方形成多个第一遮光结构111。
第一遮光结构111的材料可以为金属钼、金属钼的合金、金属铝或金属铝的合金，第二遮光结构121可以为黑矩阵。为防止相邻感光层串扰，第一遮光结构111的侧壁可以设置绝缘侧墙(spacer)。绝缘侧墙的材质例如为氮化硅或二氧化硅。
本实施例中，一、图像传感器为前照式图像传感器1，可以避免在基底10的背面制作结构，因而避免了正面结构与背面结构对准，工艺简单、良率高；二、一个颜色感光层电连接一个电荷存储区101，极大减少了光线传播过程中引起的串扰。
图2是本发明第二实施例的前照式图像传感器的截面结构示意图。
参照图2与图1所示，本实施例二的前照式图像传感器2与实施例一的前照式图像传感器1大致相同，区别仅在于：基底10上具有多个晶体管102，至少一个晶体管的源区或漏区为电荷存储区101；基底10与感光单元11之间具有金属互连层14，金属互连层14的金属互连结构141用于电连接多个晶体 管102。
晶体管102可以包括：转移晶体管、复位晶体管、源跟随晶体管与行选择晶体管。转移晶体管的源极通过金属互连结构141电连接到一个颜色感光层，漏极为浮动扩散区，因而转移晶体管用于将光电电荷从一个颜色感光层转移到浮动扩散区。复位晶体管的源极为浮动扩散区，漏极通过金属互连结构141电连接到电源电压线，因而复位晶体管用于将浮动扩散区重设到电源电压VDD。通过金属互连结构141，源跟随晶体管的栅极电连接到浮动扩散区，源极电连接到电源电压VDD，漏极电连接到行选择晶体管的源极。通过金属互连结构141，行选择晶体管的栅极电连接到行扫描线，用于响应地址信号而将源跟随晶体管的漏极电压输出。上述源极与漏极可根据电流流向而交换。
此外，参照图2所示，金属互连层14中具有导电插塞142，导电插塞142的第一端连接一个颜色感光层，第二端电连接电荷存储区101。且，导电插塞142的第一端连接在一个颜色感光层的底壁。
本实施例二中，感光单元11位于基底10上方而不是平摊于基底10的表面，因而，可以为电荷存储区101和存储电容提供大的设计空间，从而获得更大的满井容量，带来高动态范围的提升，并天然具备全局快门的设计条件。
图3是本发明第三实施例的前照式图像传感器的截面结构示意图。
参照图2与图3所示，本实施例三的前照式图像传感器3与实施例二的前照式图像传感器2大致相同，区别仅在于：导电插塞142的第一端连接在一个颜色感光层的侧壁。研究表明，含In的GaN基材料感光层在平面内流动的电流大于在厚度方向流动的电流，因而，导电插塞142连接在感光层的侧壁可提高转移的光电电荷数量。
优选地，导电插塞142的第一端所连接的感光层侧壁靠近第一遮光结 构111。
图4是本发明第四实施例的前照式图像传感器的截面结构示意图。
参照图4、图3、图2与图1所示，本实施例四的前照式图像传感器4与实施例一、二、三的前照式图像传感器1、2、3大致相同，区别仅在于：第一遮光结构111还位于不同颜色滤色层之间。
第一遮光结构111的材料为金属钼、金属钼的合金、金属铝、金属铝的合金或为黑矩阵。
在基底10上外延生长红光感光层11a、绿光感光层11b以及蓝光感光层11c之前，第一遮光结构111的高度可以较高。此时，可省略第二遮光结构121的制作。
虽然本发明披露如上，但本发明并非限定于此。任何本领域技术人员，在不脱离本发明的精神和范围内，均可作各种更动与修改，因此本发明的保护范围应当以权利要求所限定的范围为准。

Claims (10)

  1. 一种前照式图像传感器，其特征在于，包括：
    基底(10)，所述基底(10)具有多个电荷存储区(101)；
    感光单元(11)，位于所述基底(10)上方；所述感光单元(11)包括不同颜色感光层，一个颜色感光层电连接一个所述电荷存储区(101)；
    滤色单元(12)，位于所述感光单元(11)远离所述基底(10)的一侧；所述滤色单元(12)包括不同颜色滤色层，一个颜色滤色层对应所述一个颜色感光层；以及
    透镜结构(13)，位于所述滤色单元(12)远离所述基底(10)的一侧。
  2. 根据权利要求1所述的前照式图像传感器，其特征在于，所述感光单元(11)包括红光感光层(11a)、绿光感光层(11b)以及蓝光感光层(11c)，所述红光感光层(11a)、所述绿光感光层(11b)以及所述蓝光感光层(11c)的材料都为含In的GaN基材料，且其中In的组分大小不同，以根据接收到的光的波长不同产生或不产生感光电荷并存入对应的所述电荷存储区(101)。
  3. 根据权利要求2所述的前照式图像传感器，其特征在于，所述红光感光层(11a)中In的组分范围为0.4～0.6；
    所述绿光感光层(11b)中In的组分范围为0.2～0.3；
    所述蓝光感光层(11c)中In的组分范围为0.01～0.1。
  4. 根据权利要求1至3任一项所述的前照式图像传感器，其特征在于，所述基底(10)上具有多个晶体管(102)，至少一个晶体管的源区或漏区为所述电荷存储区(101)；所述基底(10)与所述感光单元(11)之间具有金属互连层(14)，所述金属互连层(14)的金属互连结构(141)用于电连接所述多个晶体管(102)。
  5. 根据权利要求4所述的前照式图像传感器，其特征在于，所述金属互连层(14)中具有导电插塞(142)，所述导电插塞(142)的第一端连接所述一个颜色感光层，第二端电连接所述电荷存储区(101)。
  6. 根据权利要求5所述的前照式图像传感器，其特征在于，所述导电插塞(142)的第一端连接于所述一个颜色感光层的侧壁。
  7. 根据权利要求1至3任一项所述的前照式图像传感器，其特征在于，所述不同颜色感光层之间具有第一遮光结构(111)，和/或所述不同颜色滤色层之间具有第二遮光结构(121)。
  8. 根据权利要求7所述的前照式图像传感器，其特征在于，所述第一遮光结构(111)的材料为金属钼、金属钼的合金、金属铝或金属铝的合金，和/或所述第二遮光结构(121)为黑矩阵。
  9. 根据权利要求1至3任一项所述的前照式图像传感器，其特征在于，所述不同颜色感光层之间具有第一遮光结构(111)，所述第一遮光结构(111)还位于所述不同颜色滤色层之间。
  10. 根据权利要求9所述的前照式图像传感器，其特征在于，所述第一遮光结构(111)的材料为金属钼、金属钼的合金、金属铝、金属铝的合金或为黑矩阵。
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Publication number Priority date Publication date Assignee Title
CN102231384A (zh) * 2011-06-22 2011-11-02 格科微电子（上海）有限公司 图像传感器及其形成方法
CN109196848A (zh) * 2016-05-19 2019-01-11 三菱电机株式会社 固态摄像装置及图像传感器
CN112543998A (zh) * 2018-08-13 2021-03-23 索尼半导体解决方案公司 固体摄像装置和电子设备

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102231384A (zh) * 2011-06-22 2011-11-02 格科微电子（上海）有限公司 图像传感器及其形成方法
CN109196848A (zh) * 2016-05-19 2019-01-11 三菱电机株式会社 固态摄像装置及图像传感器
CN112543998A (zh) * 2018-08-13 2021-03-23 索尼半导体解决方案公司 固体摄像装置和电子设备

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