阅读说明：本技术 一种高量子效率ccd结构 (High quantum efficiency CCD structure ) 是由 杨洪 白雪平 姜华男 袁世顺 翁雪涛 于 2019-10-10 设计创作，主要内容包括：本发明涉及电荷耦合器件技术领域,具体涉及一种高量子效率CCD结构,包括：第一垂直分组、第二垂直分组、第三垂直分组、第四垂直分组,每个垂直分组包括垂直CCD多晶硅栅、第一蓝光窗口和第二蓝光窗口,所述垂直CCD多晶硅栅包括至少四根多晶硅条,且每根多晶硅条上设置有接触孔；两个蓝光窗口分别位于垂直CCD多晶硅栅的左、右两侧形成双蓝光窗口像元架构；两个蓝光窗口各自按照左右分割的方式均匀分成三个面积等大的区域；不同垂直分组之间通过金属引线连接接触孔实现电学互联。本发明可解决大尺寸像元信号收集问题,可改善大尺寸帧转移CCD以及TDICCD量子效率,同时保证CCD满阱容量、动态范围、转移效率等特性不会退化。(The invention relates to the technical field of charge coupled devices, in particular to a high quantum efficiency CCD structure, which comprises: the device comprises a first vertical group, a second vertical group, a third vertical group and a fourth vertical group, wherein each vertical group comprises a vertical CCD (charge coupled device) polysilicon gate, a first blue light window and a second blue light window, the vertical CCD polysilicon gate comprises at least four polysilicon strips, and each polysilicon strip is provided with a contact hole; the two blue light windows are respectively positioned at the left side and the right side of the vertical CCD polysilicon gate to form a double blue light window pixel framework; the two blue light windows are respectively and uniformly divided into three regions with equal areas in a left-right dividing mode; and different vertical groups are connected with the contact holes through metal leads to realize electrical interconnection. The invention can solve the problem of collecting large-size pixel signals, improve the quantum efficiency of large-size frame transfer CCD and TDICCD, and simultaneously ensure that the characteristics of the CCD, such as full-well capacity, dynamic range, transfer efficiency and the like, are not degraded.)

1. A high quantum efficiency CCD structure comprising: the device comprises a first vertical group, a second vertical group, a third vertical group and a fourth vertical group, wherein each vertical group comprises a vertical CCD polysilicon gate, a first blue light window and a second blue light window, and the device is characterized in that the vertical CCD polysilicon gate comprises at least four polysilicon strips, namely a first polysilicon strip, a second polysilicon strip, a third polysilicon strip and a fourth polysilicon strip from top to bottom, and each polysilicon strip is provided with 2 contact holes; the first blue light window and the second blue light window are respectively positioned at the left side and the right side of the vertical CCD polysilicon gate, so that a double blue light window pixel framework is formed; the first blue light window and the second blue light window are respectively and uniformly divided into three regions with equal areas according to a left-right division mode, wherein the three regions are a partition 1, a partition 2 and a partition 3; and different vertical groups are connected with the contact holes through metal leads to realize electrical interconnection.

2. The CCD structure of claim 1, wherein the first vertical group, the second vertical group, the third vertical group and the fourth vertical group are sequentially connected from top to bottom, and the four groups have the same structure.

3. The high quantum efficiency CCD structure of claim 1, wherein the contact holes on each polysilicon stripe are arranged in a manner comprising: and each polycrystalline silicon strip is provided with two contact holes which are rectangular in structure, and the positions of the contact holes on the four grouped vertical CCD polycrystalline silicon gates are the same.

4. The high quantum efficiency CCD structure of claim 1, wherein the electrical interconnection between different groups comprises: the contact holes of the first polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the second polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the third polycrystalline silicon strips in each vertical grouping are connected through metal leads, and the contact holes of the fourth polycrystalline silicon strips in each vertical grouping are connected through metal leads, so that electrical interconnection is realized.

5. The CCD structure of claim 1, wherein different concentration gradients of phosphorus ions are injected into three regions of the blue light window to form potential gradients.

6. The CCD structure of claim 5, wherein the concentrations of phosphorus ions injected into partition 1, partition 2 and partition 3 are 2.5e12cm respectively^-2、3.0e12cm^-2、3.5e12cm^-2。

7. The CCD structure of claim 6, wherein the phosphorus ion implantation in three zones is realized by an ion implanter with an implantation energy value of 250 keV.

Technical Field

The invention relates to the technical field of Charge Coupled Devices (CCD), in particular to a high quantum efficiency CCD structure.

Background

The CCD image sensor has the characteristics of small fixed image noise, small dark current, light weight, high photoresponse sensitivity, high dynamic range, wide spectral response range, high geometric stability, good response linearity and the like, and is widely applied to the fields of aerospace remote sensing, ground photoelectric equipment, civil camera shooting and the like. The CCD developed by special design can meet the imaging requirements of ultrahigh frame frequency, high quantum efficiency and wide dynamic range. The quantum efficiency is defined as the ratio of the number of electrons generated and collected by incident light in a pixel of a device to the number of incident photons of a CCD chip under a certain wavelength. It characterizes the degree of response of the CCD chip to incident light as a function of wavelength. The quantum efficiency is influenced by a plurality of factors, wherein the factors such as the geometric structure, the distribution condition of the photosensitive surface, the material and the like of the CCD chip directly influence the quantum efficiency of the device. The quantum efficiency is a microscopic description of the imaging quality of the CCD chip and is one of the most important parameters for describing the performance of the CCD chip.

The existing aerospace CCD hopes that the quantum efficiency and the full-well capacity are high, and is generally realized by opening a single blue light window by adopting a large-size pixel, but the problem that the signal collection is difficult to control exists in the single blue light window large-size pixel, and the overall performance of a device is influenced.

Disclosure of Invention

Based on the problems mentioned in the background above, the present invention provides a high quantum efficiency CCD structure.

A high quantum efficiency CCD structure comprising: the device comprises a first vertical group, a second vertical group, a third vertical group and a fourth vertical group, wherein each vertical group comprises a vertical CCD (charge coupled device) polysilicon gate, a first blue light window and a second blue light window, the vertical CCD polysilicon gate comprises at least four polysilicon strips, the first polysilicon strip, the second polysilicon strip, the third polysilicon strip and the fourth polysilicon strip are respectively arranged from top to bottom, and each polysilicon strip is provided with 2 contact holes; the first blue light window and the second blue light window are respectively positioned at the left side and the right side of the vertical CCD polysilicon gate, so that a double blue light window pixel framework is formed; the first blue light window and the second blue light window are respectively and uniformly divided into three regions with equal areas according to a left-right division mode, wherein the three regions are a partition 1, a partition 2 and a partition 3; and different vertical groups are connected with the contact holes through metal leads to realize electrical interconnection.

Furthermore, the first vertical group, the second vertical group, the third vertical group and the fourth vertical group are sequentially connected from top to bottom, and the four groups have the same structure.

Further, the contact hole on each polysilicon strip is arranged in a manner that: and each polycrystalline silicon strip is provided with two contact holes which are rectangular in structure, and the positions of the contact holes on the four grouped vertical CCD polycrystalline silicon gates are the same.

Further, the electrical interconnection mode between different groups includes: the contact holes of the first polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the second polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the third polycrystalline silicon strips in each vertical grouping are connected through metal leads, and the contact holes of the fourth polycrystalline silicon strips in each vertical grouping are connected through metal leads, so that electrical interconnection is realized.

Furthermore, phosphorus ions with different concentration gradients are respectively injected into the three subareas of the blue light window to form potential gradients, so that signals in the blue light window are accelerated to enter the vertical CCD, the signal collection efficiency is improved, and the quantum efficiency characteristic of the CCD is improved.

Further, the concentrations of phosphorus ions injected into the partition 1, the partition 2 and the partition 3 were 2.5e12cm, respectively^-2、3.0e12cm^-2、3.5e12cm^-2。

Further, the phosphorus ion implantation of three zones is realized by adopting an ion implanter, and the implantation energy value of the ion implanter is set to be 250 keV.

The invention has the beneficial effects that:

the invention provides a high quantum efficiency CCD structure, wherein two blue light windows are respectively positioned at the left side and the right side of a vertical CCD, and a non-uniform double blue light window pixel framework is formed by subarea injection, so that the effective collection of blue light signals is realized; on the other hand, the vertical CCD polycrystalline silicon gate electrode realizes electrical interconnection through a metal lead, and the effective transfer of an electric signal in a channel is realized. The invention can solve the problem of large-size pixel signal collection and improve the quantum efficiency of large-size frame transfer CCD and TDICCD; and simultaneously, the characteristics of the full-well capacity, the dynamic range, the transfer efficiency and the like of the CCD are ensured not to be degraded.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural diagram of a high quantum efficiency CCD according to an embodiment of the present invention.

FIG. 2 is a plot of quantum efficiency of a Fairchild orthographic projection TDICCD device;

fig. 3 is a CCD quantum efficiency curve of an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A high quantum efficiency CCD structure comprising: the device comprises a first vertical group, a second vertical group, a third vertical group and a fourth vertical group, wherein each vertical group comprises a vertical CCD (charge coupled device) polysilicon gate, a first blue light window and a second blue light window, the vertical CCD polysilicon gate comprises at least four polysilicon strips, the first polysilicon strip, the second polysilicon strip, the third polysilicon strip and the fourth polysilicon strip are respectively arranged from top to bottom, and each polysilicon strip is provided with 2 contact holes; the first blue light window and the second blue light window are respectively positioned at the left side and the right side of the vertical CCD polysilicon gate, so that a double blue light window pixel framework is formed; the first blue light window and the second blue light window are respectively and uniformly divided into three regions with equal areas according to a left-right division mode, wherein the three regions are a partition 1, a partition 2 and a partition 3; and different vertical groups are connected with the contact holes through metal leads to realize electrical interconnection.

Furthermore, the first vertical group, the second vertical group, the third vertical group and the fourth vertical group are sequentially connected from top to bottom, and the four groups have the same structure.

Further, the contact hole on each polysilicon strip is arranged in a manner that: and each polycrystalline silicon strip is provided with two contact holes which are rectangular in structure, and the positions of the contact holes on the four grouped vertical CCD polycrystalline silicon gates are the same.

Further, the electrical interconnection mode between different groups includes: the contact holes of the first polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the second polycrystalline silicon strips in each vertical grouping are connected through metal leads, the contact holes of the third polycrystalline silicon strips in each vertical grouping are connected through metal leads, and the contact holes of the fourth polycrystalline silicon strips in each vertical grouping are connected through metal leads, so that electrical interconnection is realized.

Furthermore, phosphorus ions with different concentration gradients are respectively injected into 3 regions of the two blue light windows to form potential gradients, so that signals in the blue light windows are accelerated to enter the vertical CCD, the signal collection efficiency is improved, and the quantum efficiency characteristic of the CCD is improved.

Furthermore, phosphorus ions are respectively injected into 3 subareas of the two blue light windows, so that on one hand, the deep junction pn junction is favorably formed, the depth of an incident light absorption area is increased, and the collection of optical signals is more favorably realized; on the other hand, based on the formed potential gradient, the signal in the blue light window is accelerated to enter the vertical CCD, the signal collection efficiency is improved, and the CCD quantum efficiency characteristic is improved.

Further, the concentrations of phosphorus ions implanted into the three regions of the blue window were 2.5e12cm, respectively^-2、3.0e12cm^-2、3.5e12cm^-2. The concentration injection is beneficial to forming an effective space charge region on one hand; and on the other hand, the region is ensured not to be broken down because of over-high phosphorus injection concentration, so that the normal operation of the device is not influenced.

Furthermore, an ion implanter is adopted to realize phosphorus ion implantation of the three subareas, the implantation energy value of the ion implanter is set to be 250keV, phosphorus ion implantation is carried out on 3 areas of the two blue light windows by the ion implanter with the medium implantation energy of 250keV, the depth of a pn junction is controlled to be about 0.5 mu m, absorption of incident light of a blue light waveband is facilitated, and the quantum efficiency of the CCD is improved.

Further, the pitch between the 2 contact holes is 2 μm.

Further, the metal of the metal lead is preferably aluminum.

As can be seen from fig. 1, the vertical CCD structure has 16 polysilicon strips in total, and each four polysilicon strips, such as CI1_1B, CI2_1B, CI3_1B, CI4_1B in fig. 1, form one group, and there are four groups, i.e., a first vertical group, a second vertical group, a third vertical group, and a fourth vertical group.

When the device works, incident light from the outside is received in a pixel area, a blue light window area and a non-blue light area covered by polycrystalline silicon, and the polycrystalline silicon can absorb the incident light of a blue light wave band, so that most of the incident light of the wave band can not enter a silicon substrate to generate photoelectrons, and the quantum efficiency characteristic is influenced.

According to the CCD with the non-uniform injection double blue light windows, when incident light irradiates, the blue light windows absorb the incident light of a blue light wave band, photoelectrons are generated in the blue light windows, and then the photoelectrons enter the vertical CCD. The design of the non-uniform injection double blue light windows reduces the route path of photoelectrons generated in the blue light windows by half on one hand, and is beneficial to the photoelectrons entering the vertical CCD; on the other hand, a concentration gradient formed by non-uniformly injecting phosphorus ions generates a potential gradient, so that generated photoelectrons are further ensured to effectively and quickly enter the vertical CCD, then enter the horizontal CCD through the transfer of the vertical CCD and finally read out through the output amplifier, and the integral quantum efficiency of the device is effectively improved.

Compared with the design of a single blue light window, the CCD with the non-uniform double blue light windows designed by the invention has the advantages of two aspects: firstly, the design of double blue light windows enables the route path of photoelectrons to be halved, and the generated photoelectrons are effectively collected within limited integration time, so that the quantum efficiency is improved; secondly, the concentration is formed by non-uniform injection, so that a potential gradient is generated, the collection of photoelectrons is accelerated within limited integration time, the photoelectron collection efficiency is further improved, and the CCD quantum efficiency is improved.

The quantum efficiency can be measured by the method of CCD GJB 7951-2012.

The test results are shown in fig. 2 and 3: FIG. 2 is a quantum efficiency curve of a foreign Fairchild orthographic projection TDICCD device, wherein the mean quantum efficiency of the foreign Fairchild orthographic projection TDICCD device in a blue light waveband is 7%; FIG. 3 shows that the self-developed quantum efficiency of 210 μm × 210 μmCCD of the present invention has an average quantum efficiency of 60% in the blue light band (400 nm-500 nm); the comparison result shows that the non-uniform double blue light window CCD can effectively improve the quantum efficiency.

In the description of the present invention, it is to be understood that the terms "one end", "top", "middle", "upper", "one side", "inner", "outer", "left", "front", "center", "both ends", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "disposed," "connected," "fixed," "rotated," and the like are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; the term "connected" refers to a direct connection or an indirect connection through an intermediate, and refers to a connection between two elements or an interaction relationship between two elements, and unless otherwise specifically defined, the term "connected" refers to a connection between two elements or an interaction relationship between two elements.

The above-mentioned embodiments, which further illustrate the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.