WO2023123422A1

WO2023123422A1 - Image sensor, method for preparing same and particle detector

Info

Publication number: WO2023123422A1
Application number: PCT/CN2021/143845
Authority: WO
Inventors: 李泠霏; 黄柳冰; 吴颖; 许俊豪
Original assignee: 华为技术有限公司
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-07-06
Also published as: CN116724400A

Abstract

The embodiments of the present disclosure provide an image sensor, a method for preparing same and a particle detector. The image sensor comprises a substrate; a photosensitive layer, which comprises a photosensitive array unit, the photosensitive array unit being used for receiving high-energy particles incident from a first surface of the photosensitive layer and converting the high-energy particles into electric signals; a wiring layer, which is arranged between the photosensitive layer and the substrate and is attached to a second surface, opposite to the first surface, in the photosensitive layer; and a negative charge medium layer, which is deposited on the first surface of the photosensitive layer. According to the image sensor provided in the embodiments of the present disclosure, dark currents can be effectively suppressed. Meanwhile, since the negative charge medium layer is only used to be in direct contact with the back surface of the photosensitive layer, excellent radiation resistance can be achieved, so that the image sensor can be applied to the fields of high-energy particle detection and the like.

Description

图像传感器、制备图像传感器的方法和粒子探测器Image sensor, method of manufacturing image sensor and particle detector

技术领域technical field

本公开涉及图像传感器领域，并且具体地涉及一种图像传感器、制备方法以及使用图像传感器的粒子探测器。The present disclosure relates to the field of image sensors, and in particular, to an image sensor, a manufacturing method, and a particle detector using the image sensor.

背景技术Background technique

图像传感器是一种将光学图像转换成电子信号的设备，它被广泛地应用在数码相机和其他电子光学设备中。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。An image sensor is a device that converts an optical image into an electronic signal, and it is widely used in digital cameras and other electro-optical devices. Compared with photosensitive elements of "point" light sources such as photodiodes and phototransistors, 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.

图像传感器一般分为电荷耦合器件(Charge-coupled Device,CCD)图像传感器和互补式金属氧化物半导体(Complementary Metal-Oxided-Semiconductor,CMOS)图像传感器。CMOS图像传感器通常由感光阵列单元和由诸如行驱动器、列驱动器、时序控制逻辑等布线层组成，这几部分通常都被集成在同一块硅片上。Image sensors are generally divided into Charge-coupled Device (CCD) image sensors and Complementary Metal-Oxided-Semiconductor (CMOS) image sensors. CMOS image sensors are usually composed of photosensitive array units and wiring layers such as row drivers, column drivers, and timing control logic. These parts are usually integrated on the same silicon chip.

图像传感器根据光线入射方向的不同分为前照式图像传感器和背照式图像传感器。前照式图像传感器是较为传统的图像传感器。在这两类传统的图像传感器中，一般布线层布置在或形成在感光阵列单元的正面。对于前照式图像传感器而言，在探测时，入射光线是经由微透镜、滤光片以及布线层后入射到感光阵列单元的正面来使得感光阵列单元将光线转换成电信号。由于布线层通常包括多层金属线，且金属不透光并且还反光，因此，由于布线层的阻挡和反射，到达前照式图像传感器的感光阵列单元的入射光线只有初始入射光线的7成或更少，从而降低了图像传感器的性能。Image sensors are classified into front-illuminated image sensors and back-illuminated image sensors according to different incident directions of light. Front-illuminated image sensors are more traditional image sensors. In these two types of conventional image sensors, generally, the wiring layer is arranged or formed on the front surface of the photosensitive array unit. For the front-illuminated image sensor, when detecting, the incident light is incident on the front of the photosensitive array unit after passing through the microlens, filter and wiring layer, so that the photosensitive array unit converts the light into an electrical signal. Since the wiring layer usually includes multiple layers of metal wires, and the metal is opaque and reflective, the incident light reaching the photosensitive array unit of the front-illuminated image sensor is only 70% or more of the initial incident light due to the blocking and reflection of the wiring layer. less, thereby degrading the performance of the image sensor.

为了改进前照式图像传感器的各种问题，背照式图像传感器应运而生。与前照式图像传感器相反，光线从感光阵列单元的背面入射。也就是说，光线在入射到感光阵列单元上前不会在经过布线层而被布线层阻挡和反射。以此方式，能够提高背照式传感器的成像质量和性能。然而，背照式图像传感器中存在着暗电流问题，影响着成像质量。特别是在在高能粒子辐射探测领域所使用的背照式图像传感器，高能粒子辐射会进一步诱发界面态，从而进一步引起暗电流问题，并最终可能导致器件的性能退化并最终失效。In order to improve various problems of the front-illuminated image sensor, a back-illuminated image sensor has emerged. In contrast to front-illuminated image sensors, light enters from the back of the photosensitive array unit. That is to say, the light will not be blocked and reflected by the wiring layer after passing through the wiring layer before being incident on the photosensitive array unit. In this way, the imaging quality and performance of the back-illuminated sensor can be improved. However, there is a dark current problem in the back-illuminated image sensor, which affects the image quality. Especially in the back-illuminated image sensor used in the field of high-energy particle radiation detection, high-energy particle radiation will further induce interface states, which will further cause dark current problems, and may eventually lead to device performance degradation and eventual failure.

发明内容Contents of the invention

本公开涉及关于图像传感器的技术方案，并且具体提供了一种图像传感器、制备方法以及使用图像传感器的粒子探测器。The present disclosure relates to a technical solution for an image sensor, and specifically provides an image sensor, a preparation method, and a particle detector using the image sensor.

在本公开的第一方面，提供了一种图像传感器。该图像传感器包括衬底；感光层，包括感光阵列单元，感光阵列单元用于接收由所述感光层的第一面入射的高能粒子并将所述高能粒子转换成电信号；布线层，布置在所述所述感光层与所述衬底之间，且与感光层中与所述第一面相对的第二面贴合；以及负电荷介质层，沉积在所述感光层的所述第一面之上。从上面的描述可以看出，根据本公开实施例的图像传感器是一种背照式图像传感器。根据本公开实施例的图像传感器不同于传统的背照式图像传感器的特征在于仅采用了通过沉积的方式生长在感光层背面的负电荷介质层，这意味着负电荷介质层与感光层的背面直接接触，并且在感光层背面除负电荷介质层外不再有其他介质材料层。一方面，这能够使界面处的负电荷密度在预定阈值以上。由于采用多介质叠层的传统方案负电荷介质层中的固定负电荷会和其他绝缘层以及介质界面中的正电荷存在抵消作用，因此，根据本公开实施例的图像传感器相比于传统的方案，在负电荷介质层中的界面处的有效固定负电荷密度更高。这不但能够使得界面的能带向上弯曲，费米能级向价带移动，从而产生空穴的富集，禁带中的界面态和陷阱能级被填充的几率减小，而且还形成了较大的电子势垒，产生对电子的排斥场，阻止了自由电子向界面处移动，从而达到有效抑制暗电流的目的。另一方面，也是更重要的是，由于只采用负电荷介质层与感光层的背面直接接触，从而有效地减少了传统的多介质叠层的方案中的介质界面数，减弱了高能粒子辐照导致的的介质界面附近和介质内部的电荷累积，并由此能够起到优异的抗辐照性能，使得图像传感器能够应用于高能粒子探测等领域。In a first aspect of the present disclosure, an image sensor is provided. The image sensor includes a substrate; a photosensitive layer including a photosensitive array unit for receiving high-energy particles incident from a first surface of the photosensitive layer and converting the high-energy particles into electrical signals; a wiring layer arranged on between the photosensitive layer and the substrate, and bonded to the second surface of the photosensitive layer opposite to the first surface; and a negative charge medium layer deposited on the first surface of the photosensitive layer surface. As can be seen from the above description, the image sensor according to the embodiment of the present disclosure is a back-illuminated image sensor. The image sensor according to the embodiment of the present disclosure is different from the traditional back-illuminated image sensor in that it only uses the negatively charged medium layer grown on the backside of the photosensitive layer by deposition, which means that the negatively charged medium layer and the backside of the photosensitive layer Direct contact, and there is no other dielectric material layer on the back of the photosensitive layer except the negatively charged dielectric layer. On the one hand, this enables the negative charge density at the interface to be above a predetermined threshold. Since the fixed negative charges in the negatively charged dielectric layer in the traditional solution of multi-dielectric stacking will offset the positive charges in other insulating layers and dielectric interfaces, the image sensor according to the embodiment of the present disclosure is compared with the traditional solution , the effective fixed negative charge density at the interface in the negatively charged dielectric layer is higher. This can not only make the energy band of the interface bend upward, and the Fermi level move to the valence band, resulting in the enrichment of holes, the probability of filling the interface state and trap energy level in the forbidden band is reduced, but also forms a relatively The large electronic potential barrier generates a repelling field for electrons, preventing free electrons from moving to the interface, thereby achieving the purpose of effectively suppressing dark current. On the other hand, and more importantly, since only the negative charge dielectric layer is used to directly contact the back of the photosensitive layer, the number of dielectric interfaces in the traditional multi-dielectric stacking scheme is effectively reduced, and the irradiation of high-energy particles is weakened. The resulting charge accumulation near the interface of the medium and inside the medium can provide excellent anti-irradiation performance, so that the image sensor can be used in high-energy particle detection and other fields.

在一些实现方式中，负电荷介质层为单介质层。以此方式，能够有效地提高抗辐照性能并提高界面处的有效固定负电荷密度，从而有效地抑制暗电流。In some implementations, the negatively charged dielectric layer is a single dielectric layer. In this way, the anti-irradiation performance and the effective fixed negative charge density at the interface can be effectively improved, thereby effectively suppressing the dark current.

在一种实现方式中，负电荷介质层包括高介电常数材料。以此方式，负电荷介质层能够以简单且有效的方式实现。In one implementation, the negatively charged dielectric layer includes a high dielectric constant material. In this way, negatively charged dielectric layers can be realized in a simple and efficient manner.

在一种实现方式中，负电荷介质层中与所述感光层的界面处的固定负电荷的密度高于预定阈值。In an implementation manner, the density of fixed negative charges at the interface between the negatively charged medium layer and the photosensitive layer is higher than a predetermined threshold.

在一些实现方式中，预定阈值被选择为用于抑制界面处的暗电流的产生。以此方式，进一步确保了根据本公开实施例的图像传感器能够有效地抑制暗电流。In some implementations, the predetermined threshold is selected to suppress the generation of dark current at the interface. In this way, it is further ensured that the image sensor according to the embodiments of the present disclosure can effectively suppress dark current.

在一种实现方式中，负电荷介质层用于使得所述感光层中与所述负电荷介质层的界面处的费米能级大致位于价带之下。以此方式，通过使费米能级向价带移动并大致位于价带之下，能够产生空穴的富集并形成较强的内建电场，来由此减少界面处的电子浓度从而达到场效应钝化的效果，并由此有效地降低暗电流。In one implementation manner, the negatively charged medium layer is used to make the Fermi level at the interface between the photosensitive layer and the negatively charged medium layer be substantially below the valence band. In this way, by shifting the Fermi level towards and roughly below the valence band, an enrichment of holes and a stronger built-in electric field can be produced, thereby reducing the electron concentration at the interface to achieve the field The effect of passivation, and thus effectively reduce the dark current.

在一些实现方式中，负电荷介质层中与所述感光层的界面处的所述固定负电荷的密度在10 ¹²/cm ²～10 ¹³/cm ²之间。以此方式，能够在界面处产生一个较大的内建电场和电子势垒，从而有效地抑制暗电流。 In some implementation manners, the density of the fixed negative charges at the interface between the negative charge medium layer and the photosensitive layer is between 10 ¹² /cm ² and 10 ¹³ /cm ² . In this way, a large built-in electric field and electron barrier can be generated at the interface, thereby effectively suppressing the dark current.

在一些实现方式中，负电荷介质层包括金属氧化物或氮化物。以此方式，负电荷介质层能够以成本有效的方式实现。In some implementations, the negatively charged dielectric layer includes a metal oxide or nitride. In this way, negatively charged dielectric layers can be realized in a cost-effective manner.

在一种实现方式中，负电荷介质层包括能够至少在与所述感光层的界面处提供预定密度的负电荷的材料。In one implementation manner, the negatively charged medium layer includes a material capable of providing a predetermined density of negative charges at least at an interface with the photosensitive layer.

在一些实现方式中，负电荷介质层包括以下中的一种：氧化铝、氧化铪、氧化镓、氧化钽、氧化镧、氧化釔、氧化锆或者氮化硅。以此方式，使得负电荷介质层的选择更加灵活。In some implementations, the negative charge dielectric layer includes one of aluminum oxide, hafnium oxide, gallium oxide, tantalum oxide, lanthanum oxide, yttrium oxide, zirconium oxide, or silicon nitride. In this way, the selection of the negative charge dielectric layer is more flexible.

在一些实现方式中，负电荷介质层的厚度在2nm～8nm之间。通过使用具有较薄厚度的负电荷介质层，更加有利于在高能粒子辐射下介质层中非期望的聚集电荷的输运和释放，从而进一步提高抗辐照性。In some implementations, the thickness of the negatively charged dielectric layer is between 2nm and 8nm. By using a negatively charged dielectric layer with a thinner thickness, it is more conducive to the transport and release of undesired accumulated charges in the dielectric layer under high-energy particle radiation, thereby further improving the radiation resistance.

在一些实现方式中，负电荷介质层通过原子层沉积的方式形成在所述感光层的所述第一面。以此方式，能够提高界面质量，从而更稳定且可靠地实现负电荷介质层中与感光层的界面处的固定负电荷密度，从而保证图像传感器的抑制暗电流性能和抗辐照性能。In some implementations, the negatively charged dielectric layer is formed on the first surface of the photosensitive layer by atomic layer deposition. In this way, the interface quality can be improved, so that the fixed negative charge density at the interface between the negative charge medium layer and the photosensitive layer can be realized more stably and reliably, thereby ensuring the dark current suppression performance and radiation resistance performance of the image sensor.

在一些实现方式中，感光层的至少第一面部分是经掺杂的p型硅。In some implementations, at least the first face portion of the photosensitive layer is doped p-type silicon.

在一些实现方式中，感光层的所述第一面被处理，以使得所述界面处不存在或者仅存在厚度小于1nm的所述感光层的自然氧化层。通过尽可能地避免负电荷介质层和感光层之间的自然氧化层或其他任何氧化层，能够进一步确保图像传感器的抑制暗电流性能和抗辐照性能。In some implementations, the first surface of the photosensitive layer is processed such that there is no or only a native oxide layer of the photosensitive layer with a thickness of less than 1 nm at the interface. By avoiding the natural oxide layer or any other oxide layer between the negatively charged medium layer and the photosensitive layer as much as possible, the dark current suppression performance and radiation resistance performance of the image sensor can be further ensured.

在一些实现方式中，固定负电荷通过以下中的任一种而产生：所述负电荷介质层的生长过程、和所述负电荷介质层与所述感光层的界面的晶格匹配。固定负电荷可以通过多种方式形成，从而使得图像传感器能够以多种方式制造而不会影响抗辐照性和抑制暗电流性能。In some implementations, the fixed negative charge is generated by any of: a growth process of the negatively charged medium layer, and lattice matching of an interface of the negatively charged medium layer with the photosensitive layer. Fixed negative charges can be formed in a variety of ways, allowing image sensors to be fabricated in a variety of ways without compromising radiation resistance and dark current suppression performance.

根据本公开的第二方面，提供了一种制备图像传感器的方法。所述方法包括提供衬底；形成包括感光阵列单元的感光层并在所述感光层的第二面形成布线层，所述感光阵列单元用于接收由所述感光层的第一面入射的高能粒子并将所述高能粒子转换成电信号，所述第一面和所述第二面相对；将所述感光层经由所述布线层耦合至所述衬底；以及在所述感光层的所述第一面之上沉积负电荷介质层。以此方式制造的图像传感器采用了负电荷介质层和感光层的背面直接接触的方式，从而能够有效地抑制暗电流的同时有效地提高抗辐照性能。According to a second aspect of the present disclosure, a method of manufacturing an image sensor is provided. The method includes providing a substrate; forming a photosensitive layer including a photosensitive array unit and forming a wiring layer on a second surface of the photosensitive layer, and the photosensitive array unit is used to receive high energy incident from the first surface of the photosensitive layer particles and convert the high-energy particles into electrical signals, the first surface and the second surface are opposite; the photosensitive layer is coupled to the substrate via the wiring layer; and the photosensitive layer is coupled to the substrate; A negatively charged dielectric layer is deposited on the first surface. The image sensor manufactured in this way adopts the way that the negatively charged dielectric layer is in direct contact with the back of the photosensitive layer, so that the dark current can be effectively suppressed and the anti-radiation performance can be improved effectively.

在一些实现方式中，方法在将所述感光层经由所述布线层耦合至所述衬底还包括处理所述所述感光层的所述第一面以减薄所述感光层的厚度；以及对减薄后的感光层的所述第一面进行处理以去除自然氧化层，使得所述高介电常数材料层和所述感光层的界面处不存在自然氧化层或者仅存在厚度小于1nm的自然氧化层。通过尽可能地避免负电荷介质层和感光层之间的自然氧化层或其他任何氧化层，能够进一步确保图像传感器的抑制暗电流性能和抗辐照性能。In some implementations, the method of coupling the photosensitive layer to the substrate via the wiring layer further includes processing the first side of the photosensitive layer to reduce the thickness of the photosensitive layer; and Treating the first surface of the thinned photosensitive layer to remove the natural oxide layer, so that there is no natural oxide layer at the interface between the high dielectric constant material layer and the photosensitive layer or only a layer with a thickness of less than 1 nm exists. natural oxide layer. By avoiding the natural oxide layer or any other oxide layer between the negatively charged medium layer and the photosensitive layer as much as possible, the dark current suppression performance and radiation resistance performance of the image sensor can be further ensured.

根据本公开的第三方面还提供一种粒子探测器。该粒子探测器包括前文中第一方面所提到的图像传感器，所述图像传感器感测高能粒子并基于由高能粒子入射而转换的电信号提供数据；以及存储器，用于存储由图像传感器所提供的数据。According to a third aspect of the present disclosure, there is also provided a particle detector. The particle detector includes the image sensor mentioned in the first aspect above, which senses high-energy particles and provides data based on electrical signals converted by the incident high-energy particles; The data.

应当理解，发明内容部分中所描述的内容并非旨在限定本公开的关键或重要特征，亦非用于限制本公开的范围。本公开的其他特征通过以下的描述将变得容易理解。It should be understood that what is described in the Summary of the Invention is not intended to identify key or important features of the disclosure, nor is it intended to limit the scope of the disclosure. Other features of the present disclosure will become easily understood through the following description.

附图说明Description of drawings

通过参考附图阅读下文的详细描述，本公开的实施例的上述以及其他目的、特征和优点将变得容易理解。在附图中，以示例性而非限制性的方式示出了本公开的若干实施例。The above and other objects, features and advantages of embodiments of the present disclosure will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the present disclosure are shown by way of illustration and not limitation.

图1示出了传统方案中的图像传感器的局部简化剖面示意图；Fig. 1 shows a partial simplified cross-sectional schematic diagram of an image sensor in a conventional solution;

图2示出了传统方案中的另一种图像传感器的局部简化剖面示意图；Fig. 2 shows a partial simplified cross-sectional schematic diagram of another image sensor in a conventional solution;

图3示出了根据本公开实施例的图像传感器的简化侧视示意图；FIG. 3 shows a simplified schematic side view of an image sensor according to an embodiment of the disclosure;

图4示出了传统的图像传感器的界面处的内建电场和根据本公开实施例的图像传感器的界面处所形成内建电场的比较；4 shows a comparison of a built-in electric field at an interface of a conventional image sensor and a built-in electric field formed at an interface of an image sensor according to an embodiment of the present disclosure;

图5示出了介质叠层结构的电容-电压曲线和根据本公开实施例的单介质层结构的电容-电压曲线的比较；5 shows a comparison of the capacitance-voltage curve of the dielectric stack structure and the capacitance-voltage curve of the single dielectric layer structure according to an embodiment of the present disclosure;

图6示出了根据本公开的实施例的制备图像传感器的方法的主要步骤的流程图；以及6 shows a flow chart of the main steps of a method of manufacturing an image sensor according to an embodiment of the present disclosure; and

图7示出了根据本公开的实施例的制备图像传感器的过程中图像传感器的简化剖面示意图。FIG. 7 shows a simplified schematic cross-sectional view of an image sensor during the process of fabricating the image sensor according to an embodiment of the present disclosure.

贯穿所有附图，相同或者相似的参考标号被用来表示相同或者相似的组件。Throughout the drawings, the same or similar reference numerals are used to designate the same or similar components.

具体实施方式Detailed ways

下文将参考附图中示出的若干示例性实施例来描述本公开的原理和精神。应当理解，描述这些具体的实施例仅是为了使本领域的技术人员能够更好地理解并实现本公开，而并非以任何方式限制本公开的范围。在以下描述和权利要求中，除非另有定义，否则本文中使用的所有技术和科学术语具有与所属领域的普通技术人员通常所理解的含义。Hereinafter, the principle and spirit of the present disclosure will be described with reference to several exemplary embodiments shown in the accompanying drawings. It should be understood that these specific embodiments are described only to enable those skilled in the art to better understand and realize the present disclosure, rather than to limit the scope of the present disclosure in any way. In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

如本文所使用的，术语“包括”及其类似用语应当理解为开放性包含，即“包括但不限于”。术语“基于”应当理解为“至少部分地基于”。术语“一个实施例”或“该实施例”应当理解为“至少一个实施例”。术语“第一”、“第二”等等可以指代不同的或相同的对象，并且仅用于区分所指代的对象，而不暗示所指代的对象的特定空间顺序、时间顺序、重要性顺序，等等。As used herein, the term "comprising" and its analogs should be interpreted as an open inclusion, ie "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be read as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same objects, and are used only to distinguish the referred objects without implying a specific spatial order, temporal order, important sexual order, and so on.

本文使用的术语“电路”是指以下的一项或多项：(a)仅硬件电路实现方式(诸如仅模拟和/或数字电路的实现方式)；以及(b)硬件电路和软件的组合，诸如(如果适用)：(i)模拟和/或数字硬件电路与软件/固件的组合，以及(ii)硬件处理器的任何部分与软件(包括一起工作以使装置，诸如通信设备或其他电子设备等，执行各种功能的数字信号处理器、软件和存储器)；以及(c)硬件电路和/或处理器，诸如微处理器或者微处理器的一部分，其要求软件(例如固件)用于操作，但是在不需要软件用于操作时可以没有软件。电路的定义适用于此术语在本申请中(包括权利要求中)的所有使用场景。作为另一示例，在此使用的术语“电路”也覆盖仅硬件电路或处理器(或多个处理器)、或者硬件电路或处理器的一部分、或者随附软件或固件的实现方式。例如，如果适用于特定权利要求元素，术语“电路”还覆盖基带集成电路或处理器集成电路、网络设备、终端设备或其他设备中的类似集成电路。As used herein, the term "circuitry" refers to one or more of: (a) hardware circuit implementations only (such as analog and/or digital circuit implementations only); and (b) a combination of hardware circuits and software, Such as (if applicable): (i) combinations of analog and/or digital hardware circuits and software/firmware, and (ii) any part of a hardware processor and software (including etc., digital signal processors, software, and memory that perform various functions); and (c) hardware circuits and/or processors, such as microprocessors or parts of microprocessors, that require software (e.g., firmware) to operate , but can be without software when it is not required for operation. The definition of electrical circuit applies to all uses of this term in this application, including in the claims. As a further example, the term 'circuitry' as used herein also covers an implementation of merely a hardware circuit or processor (or multiple processors), or a portion thereof, or accompanying software or firmware. For example, if applicable to a particular claim element, the term "circuitry" also covers baseband integrated circuits or similar integrated circuits in processor integrated circuits, network equipment, terminal equipment, or other devices.

前文中提到的背照式图像传感器是将布线层放到了感光阵列单元的背面(下文中也被称为第一面)，这样，光线就能直接照到光电二极管上，光线几乎没有阻挡和干扰地就入射到感光阵列单元，从而使得背照式图像传感器对光线的利用率极高。因此背照式图像传感器能更好地利用照射入的光线，在低照度环境下成像质量也就更好。The back-illuminated image sensor mentioned above puts the wiring layer on the back of the photosensitive array unit (hereinafter also referred to as the first side), so that the light can directly shine on the photodiode, and the light is almost unobstructed and The interference ground is incident on the photosensitive array unit, so that the back-illuminated image sensor has a very high utilization rate of light. Therefore, the back-illuminated image sensor can make better use of the incoming light, and the image quality is better in low-light environments.

背照式图像传感器能够具有更高的光线利用效率，这样，在低照度环境下，就具有更高的灵敏度。同时，由于布线层不会影响感光阵列单元接收光线，因此，布线层可以做得更厚，这样就能放置更多的处理电路，这有助于提高信号的处理速度。The back-illuminated image sensor can have higher light utilization efficiency, thus, it has higher sensitivity in low-light environment. At the same time, since the wiring layer will not affect the photosensitive array unit to receive light, the wiring layer can be made thicker, so that more processing circuits can be placed, which helps to improve the signal processing speed.

正是由于背照式图像传感器出色的成像质量以及处理速度等优势，其被广泛应用于生活和工作的各个领域。例如，在生活中我们所使用的手机、相机等用到图像传感器的地方通常都用到了背照式图像传感器。不仅如此，背照式图像传感器在空间成像领域以及高能粒子辐射探测等领域也应用广泛。It is precisely because of the excellent imaging quality and processing speed of the back-illuminated image sensor that it is widely used in various fields of life and work. For example, back-illuminated image sensors are usually used in places where image sensors are used in mobile phones and cameras that we use in our daily life. Not only that, back-illuminated image sensors are also widely used in the fields of space imaging and high-energy particle radiation detection.

然而，半导体等物理器件不可能是完全理想的而没有任何缺陷。背照式图像传感器，特别是在高能粒子辐射探测领域所使用的背照式图像传感器，不可避免的一个问题就是抗辐照问题。当高能粒子穿过构成器件的材料层尤其是介质材料层时，高能粒子通过产生电子-空穴对而损失大部分能量。这种在高能粒子辐照下产生的过量的电荷载流子可以通过诱发总电离剂量(Total Ionizing Dose,TID)效应来干扰或损坏半导体器件，特别是感光阵列单元。TID效应是大量的辐射粒子进入半导体器件的材料内部，与材料的原子核外电子发生电离作用产生额外的电荷，这些电荷在器件内尤其是介质层中堆积、或者在界面处诱发界面态，导致器件性能逐步退化、乃至最终丧失的现象。辐照产生的过量电荷的不断累积会诱发暗电流。暗电流与光照产生的电荷很难在读出电路处进行区分。暗电流在感光阵列单元各处也不完全相同，它会导致固定图形噪声。对于含有积分功能的像素单元来说，暗电流所造成的固定图形噪声与积分时间成正比。暗电流的存在对感光阵列单元的成像造成了不利影响。TID导致的暗电流还会随着辐照总剂量的增加而增加，从而影响到了图像传感器的寿命。However, physical devices such as semiconductors cannot be completely ideal without any defects. One of the unavoidable problems of back-illuminated image sensors, especially those used in the field of high-energy particle radiation detection, is radiation resistance. When high-energy particles pass through the material layers constituting the device, especially the dielectric material layer, the high-energy particles lose most of their energy by generating electron-hole pairs. The excess charge carriers generated under high-energy particle irradiation can interfere or damage semiconductor devices, especially photosensitive array units, by inducing the Total Ionizing Dose (TID) effect. The TID effect is that a large number of radiation particles enter the material of the semiconductor device, and ionize with the electrons outside the nucleus of the material to generate additional charges. These charges accumulate in the device, especially in the dielectric layer, or induce interface states at the interface, resulting in device The gradual degradation and eventual loss of performance. Dark current is induced by the continuous accumulation of excess charge generated by irradiation. Dark current and light-generated charges are difficult to distinguish at the readout circuit. Dark current is also not exactly the same across photosensitive array elements, which causes constant pattern noise. For the pixel unit with integration function, the fixed pattern noise caused by dark current is proportional to the integration time. The existence of dark current has an adverse effect on the imaging of the photosensitive array unit. The dark current caused by TID will also increase with the increase of the total irradiation dose, thus affecting the life of the image sensor.

暗电流的产生一方面是由于感光阵列单元的背部入射面的界面态所引起的。界面态是指在异质结构中，不同材料的交界面处由于晶格失配而导致的能值位于半导体禁带中的一些分立或者连续的电子能级或能带。因此，目前传统的抑制暗电流的方案大多围绕如何实现较为理想的界面从而降低界面态这一思路开展的。这些方案包括提高界面薄膜生长质量以降低界面缺陷、采用氧化层/高介电常数材料层/氧化层叠层结构实现暗电流的抑制等。On the one hand, the generation of dark current is caused by the interface state of the back incident surface of the photosensitive array unit. Interface states refer to some discrete or continuous electronic energy levels or energy bands in the semiconductor forbidden band due to lattice mismatch at the interface of different materials in a heterostructure. Therefore, most of the current traditional dark current suppression schemes focus on how to achieve a more ideal interface to reduce the interface state. These solutions include improving the growth quality of the interface film to reduce interface defects, and using the oxide layer/high dielectric constant material layer/oxide layer stack structure to suppress dark current, etc.

例如，传统的解决方案中有一种解决方案为了抑制暗电流，提出了一种减少背照式图像传感器暗电流的方法。该方法主要包括以下步骤：第一步、以晶圆片501为基底，在所述晶圆片501的第一面生成绝缘层503；第二步、在所述绝缘层503上生长高介电常数材料层502，作为背照式图像传感器背表面的钝化层；第三步、用紫外线照射背照式图像传感器背表面的钝化层。For example, one of the conventional solutions proposes a method for reducing the dark current of a back-illuminated image sensor in order to suppress the dark current. The method mainly includes the following steps: the first step is to use the wafer 501 as a base to form an insulating layer 503 on the first surface of the wafer 501; the second step is to grow a high dielectric layer on the insulating layer 503. The constant material layer 502 is used as a passivation layer on the back surface of the back-illuminated image sensor; the third step is to irradiate the passivation layer on the back surface of the back-illuminated image sensor with ultraviolet rays.

通过该传统的解决方案所形成的图像传感器的剖面示意图如图1所示。从图1可以看出，其至少有布置在感光阵列单元背部的两层材料制成，即，采用多介质叠层的方式，包括形成在背部的诸如二氧化硅的绝缘层503以及形成在绝缘层503之上的高介电常数材料层502。该方案采用多介质叠层实现了感光阵列单元的背面的界面改善，并由此通过降低界面的表面态和界面场钝化来抑制暗电流。A schematic cross-sectional view of an image sensor formed by this traditional solution is shown in FIG. 1 . It can be seen from FIG. 1 that it is made of at least two layers of materials arranged on the back of the photosensitive array unit, that is, it adopts the method of multi-media lamination, including an insulating layer 503 such as silicon dioxide formed on the back and an insulating layer 503 formed on the insulating layer. Layer 502 of high dielectric constant material over layer 503 . In this solution, the interface of the back surface of the photosensitive array unit is improved by using a multi-media stack, and thus the dark current is suppressed by reducing the surface state of the interface and passivating the interface field.

传统的解决方案中还有一种增强背照式图像传感器对抗暗电流的方法。该方法主要包括以下步骤：提供基底508，基底508上表面具有自然氧化层；去除基底508上的所述自然氧化层；利用解耦等离子体氧化法在基底508上表面生长一层薄膜氧化层504；该解耦等离子体氧化法在氧化过程中的温度为200～500℃；该解耦等离子氧化法利用连续脉冲的模式，并以氧气为解离气体；在薄膜氧化层504上生长一层氧化铝薄膜505；在氧化铝薄膜505上生长一层氧化钽薄膜506；在氧化钽薄膜506上生长一层氧化物层507。Another traditional solution is to enhance the back-illuminated image sensor against dark current. The method mainly includes the following steps: providing a substrate 508 with a natural oxide layer on the upper surface of the substrate 508; removing the natural oxide layer on the substrate 508; growing a thin film oxide layer 504 on the upper surface of the substrate 508 by using a decoupled plasma oxidation method The temperature in the oxidation process of the decoupling plasma oxidation method is 200-500° C.; the decoupling plasma oxidation method uses a continuous pulse mode, and uses oxygen as the dissociated gas; An aluminum film 505 ; a tantalum oxide film 506 is grown on the aluminum oxide film 505 ; an oxide layer 507 is grown on the tantalum oxide film 506 .

以该解决方案形成的背照式图像传感器也在感光阵列单元(即，基底508)的背部形成了从下至上包括薄膜氧化层504、氧化铝薄膜505、氧化钽薄膜506和氧化物层507的多介质叠层，如图2所示。该方案通过采用四层介质叠层的方式实现了感光阵列单元的背部入射面的界面态的降低和界面场钝化，从而实现了对暗电流的抑制。The back-illuminated image sensor formed with this solution also forms a thin film oxide layer 504, an aluminum oxide film 505, a tantalum oxide film 506, and an oxide layer 507 from bottom to top on the back of the photosensitive array unit (i.e., the substrate 508). The multi-media stack is shown in Figure 2. This solution realizes the reduction of the interface state and the passivation of the interface field on the back incident surface of the photosensitive array unit by adopting a four-layer dielectric lamination method, thereby realizing the suppression of the dark current.

然而，传统的方案中虽然通过化学钝化和场钝化的协同作用，能够在某种程度上实现对暗电流的抑制，但是由于多介质叠层的引入使得所形成的背照式图像传感器的抗辐照性较差。抗辐照性是指器件在诸如高能粒子的辐照下可以保持器件的性能稳定的能力。如前文中所提到的，高能粒子的辐照会导致总电离剂量效应，导致暗电流的增加，并对传感器中的介质材料和界面带来损伤和破坏。总电离剂量效应是指大量的辐射粒子进入半导体器件材料内部，与材料的原子核外电子发生电离作用产生额外的电荷，这些电荷在器件内的氧化层堆积、或者在半导体/绝缘层交界面诱发界面态，导致器件性能逐步退化、乃至最终丧失的现象。However, although the traditional solution can suppress the dark current to some extent through the synergistic effect of chemical passivation and field passivation, the introduction of the multi-media stack makes the formed back-illuminated image sensor Radiation resistance is poor. Radiation resistance refers to the ability of a device to maintain stable performance of the device under irradiation such as high-energy particles. As mentioned above, the irradiation of high-energy particles will cause the total ionization dose effect, lead to the increase of dark current, and bring damage and destruction to the dielectric material and interface in the sensor. The total ionizing dose effect means that a large number of radiation particles enter the interior of the semiconductor device material, and ionize with the electrons outside the nucleus of the material to generate additional charges. State, leading to the gradual degradation of device performance, and even the eventual loss of the phenomenon.

本文中所提到的高能粒子200包括高能电子、X射线、宇宙射线、α粒子、高能离子等，其能量范围在keV～MeV量级。高能粒子200对传统的背照式图像传感器的影响主要包括：电荷随着辐射总剂量的持续积累，暗电流随辐射总剂量的增加，探测灵敏度的降低以及白像素的产生等问题，这将导致器件的性能降低乃至功能失效。The high-energy particles 200 mentioned herein include high-energy electrons, X-rays, cosmic rays, alpha particles, high-energy ions, etc., and their energy ranges from keV to MeV. The impact of high-energy particles 200 on traditional back-illuminated image sensors mainly includes: the continuous accumulation of charge with the total radiation dose, the increase of dark current with the total radiation dose, the reduction of detection sensitivity and the generation of white pixels, etc., which will lead to The performance of the device is reduced or even the function fails.

因此，传统中的采用多介质叠层来优化界面态的技术方案由于引入了多个介质界面，从而导致介质叠层中辐照产生的电荷富集难以释放。当这些传感器应用于扫描电子显微镜的二次电子和背散射电子探测器、X射线探测器、用于航空航天的抗辐照图像传感器、粒子碰撞的辐射探测器等会受到高能粒子200辐照的领域时，多介质叠层的使用会导致器件更加容易在辐照下受到总电离剂量效应的影响从而一方面导致界面态的恶化，另一方面介质叠层中的电荷富集也会导致额外的不期望的场效应，从而改变原本的界面处的电势分布，这将导致暗电流的增加乃至器件失效。另外，对于图1中所示出的方案而言，由于负电荷介质层中靠近其与绝缘层界面处存在固定负电荷，从而会在绝缘层中感应出正电荷，从而削弱了负电荷介质层的场钝化效果，并由此暗电流的抑制受到不利影响。此外，多介质叠层的设计和制造也提高了图像传感器的制造难度和实现成本。Therefore, the traditional technical solution of using a multi-dielectric stack to optimize the interface state introduces multiple dielectric interfaces, which makes it difficult to release the charge enrichment generated by irradiation in the dielectric stack. When these sensors are used in secondary electron and backscattered electron detectors of scanning electron microscopes, X-ray detectors, radiation-resistant image sensors for aerospace, radiation detectors for particle collisions, etc., which will be irradiated by high-energy particles 200 In the field of multi-dielectric stack, the use of multi-dielectric stack will make the device more susceptible to the effect of total ionization dose under irradiation, which will lead to the deterioration of the interface state on the one hand, and the charge enrichment in the dielectric stack will also lead to additional The undesired field effect will change the potential distribution at the original interface, which will lead to the increase of dark current and even the failure of the device. In addition, for the solution shown in Figure 1, due to the presence of fixed negative charges in the negatively charged dielectric layer near its interface with the insulating layer, positive charges will be induced in the insulating layer, thus weakening the negatively charged dielectric layer. The field passivation effect, and thus the suppression of dark current, is adversely affected. In addition, the design and manufacture of the multi-media stack also increases the manufacturing difficulty and implementation cost of the image sensor.

由此可见，抗辐照性能优化对于提高用于高能粒子200探测的图像传感器的探测精度和寿命至关重要。为了提高背照式图像传感器的抗辐照性能的同时抑制暗电流，使其能够应用于空间成像领域以及高能粒子200辐射探测等领域，以用于扫描电子显微镜的二次电子和背散射电子探测器、X射线探测器、用于航空航天的抗辐照图像传感器、粒子碰撞的辐射探测器等，本公开的实施例提供了一种用于图像传感器，特别是背照式图像传感器的制造方法以及所制造的图像传感器。It can be seen that the optimization of anti-irradiation performance is very important to improve the detection accuracy and lifespan of the image sensor used for the detection of high-energy particles 200 . In order to improve the anti-irradiation performance of the back-illuminated image sensor and suppress the dark current at the same time, it can be used in the field of space imaging and the detection of high-energy particle 200 radiation, which is used for the detection of secondary electrons and backscattered electrons in scanning electron microscopes detectors, X-ray detectors, radiation-resistant image sensors for aerospace, radiation detectors for particle collisions, etc., embodiments of the present disclosure provide a manufacturing method for image sensors, especially back-illuminated image sensors and the manufactured image sensor.

在本公开实施例的第一方面，提供了一种图像传感器。图3示出了该图像传感器的侧视示意图。如图3所示，根据本公开实施例的图像传感器包括衬底102、感光层101、布线层103和负电荷介质层104。衬底102可以包括任意适当的衬底，例如可以包括有源芯片单元和/或无源衬底等。In a first aspect of embodiments of the present disclosure, an image sensor is provided. FIG. 3 shows a schematic side view of the image sensor. As shown in FIG. 3 , an image sensor according to an embodiment of the present disclosure includes a substrate 102 , a photosensitive layer 101 , a wiring layer 103 and a negative charge dielectric layer 104 . The substrate 102 may include any suitable substrate, for example, may include an active chip unit and/or a passive substrate and the like.

布线层103位于衬底102和感光层101之间，在感光层中，背离布线层103的第一面为背面，贴近布线层103的第二面为正面。感光层101是半导体层，包括感光阵列单元。感光阵列单元用于接收由在感光层101的第一面入射的高能粒子200并将高能粒子200转换成对应的电信号。由此可知，根据本公开实施例的图像传感器能够应用于扫描电子显微镜的二次电子和背散射电子探测器、X射线探测器、用于航空航天的抗辐照图像传感器、粒子碰撞的辐射探测器等各种设备中，以探测各种高能粒子。The wiring layer 103 is located between the substrate 102 and the photosensitive layer 101. In the photosensitive layer, the first surface away from the wiring layer 103 is the back side, and the second side close to the wiring layer 103 is the front side. The photosensitive layer 101 is a semiconductor layer, including a photosensitive array unit. The photosensitive array unit is used to receive the high-energy particles 200 incident on the first surface of the photosensitive layer 101 and convert the high-energy particles 200 into corresponding electrical signals. It can be seen that the image sensor according to the embodiment of the present disclosure can be applied to secondary electron and backscattered electron detectors of scanning electron microscopes, X-ray detectors, radiation-resistant image sensors for aerospace, and radiation detection of particle collisions. In various devices such as detectors to detect various high-energy particles.

布线层103布置在感光层101的正面(下文中也被称为第二面)。也就是说，布线层103在所形成的图像传感器中位于衬底102和感光层101之间。布线层103中通常包括多层金属线，并且包括用于处理由感光阵列单元所产生的电信号的放大电路、模数转换电路和其他相关的处理电路等。由高能粒子入射在感光层101的第一面而使得感光阵列单元所产生的电信号经过布线层103中的电路处理后形成数据以提供给其他电子设备来使用。感光层101经由布线层103而耦合至衬底102。因此，所形成的图像传感器为背照式图像传感器。The wiring layer 103 is arranged on the front side (hereinafter also referred to as the second side) of the photosensitive layer 101 . That is, the wiring layer 103 is located between the substrate 102 and the photosensitive layer 101 in the formed image sensor. The wiring layer 103 generally includes multiple layers of metal wires, and includes an amplification circuit, an analog-to-digital conversion circuit, and other related processing circuits for processing electrical signals generated by the photosensitive array unit. The electrical signals generated by the photosensitive array units are processed by the circuits in the wiring layer 103 and then formed into data for use by other electronic devices due to the high-energy particles incident on the first surface of the photosensitive layer 101 . The photosensitive layer 101 is coupled to the substrate 102 via the wiring layer 103 . Therefore, the formed image sensor is a back-illuminated image sensor.

在一些实施例中，感光层101和布线层103可以由一片半导体材料分别经由前道工序和后道工序制造而成。具体而言，集成电路是依靠所谓的平面工艺一层一层制备起来的。对于逻辑器件，简单地说，首先是在硅底上划分制备晶体管的区域，然后是离子注入实现N型和P型区域，其次是做栅极，随后又是离子注入，完成每一个晶体管的源极和漏极。这部分工艺流程是为了在硅衬底102上实现场效应晶体管从而形成感光阵列单元，又被称为前道(front end of line,FEOL)工艺或工序。与之相对应的是后道(back end of line,BEOL)工艺或工序，后道工序实际上就是建立若干层的导电金属线，不同层金属线之间由柱状金属相连，从而形成布线层103。布线层103目前大多选用铜作为导电金属，因此后道工序又被称为铜互联。这些铜线负责把晶体管按设计的要求连接起来，实现特定的功能，并且能够将感光阵列单元耦合至衬底102。In some embodiments, the photosensitive layer 101 and the wiring layer 103 can be manufactured from a piece of semiconductor material through a front-end process and a back-end process, respectively. Specifically, integrated circuits are fabricated layer by layer by means of a so-called planar process. For logic devices, in simple terms, the first is to divide the area for preparing transistors on the silicon substrate, and then perform ion implantation to realize N-type and P-type areas, followed by making gates, and then ion implantation to complete the source of each transistor. pole and drain. This part of the process flow is to implement a field effect transistor on the silicon substrate 102 to form a photosensitive array unit, which is also called a front end of line (FEOL) process or process. Corresponding to it is the back end of line (BEOL) process or process. The latter process is actually to establish several layers of conductive metal lines, and the metal lines of different layers are connected by columnar metals to form a wiring layer 103 . Copper is mostly used as the conductive metal for the wiring layer 103 at present, so the subsequent process is also called copper interconnection. These copper wires are responsible for connecting the transistors according to design requirements to achieve specific functions, and can couple the photosensitive array units to the substrate 102 .

当然，在一些实施例中，感光层101和布线层103也可以通过不同的硅片制成并以堆叠式结构组装在一起。采用堆叠式结构能够在布线层103中集成更多的晶体管，从而实现更快的处理速度以及更多的功能。Of course, in some embodiments, the photosensitive layer 101 and the wiring layer 103 can also be made of different silicon chips and assembled together in a stacked structure. Using a stacked structure can integrate more transistors in the wiring layer 103 , thereby achieving faster processing speed and more functions.

在一些实施例中，感光层101的至少第一面或者邻近所述第一面的部分是经掺杂的p型硅。p型硅是一种空穴型半导体，通常是在在纯净的硅晶体中掺入三价元素(如硼)，使之取代晶格中硅原子的位置而形成的。在p型半导体中，空穴为多子，自由电子为少子。由于p型半导体中正电荷量与负电荷量相等，故p型半导体呈电中性。空穴主要由杂质原子提供，自由电子由热激发形成。In some embodiments, at least the first surface of the photosensitive layer 101 or a portion adjacent to the first surface is doped p-type silicon. P-type silicon is a hole-type semiconductor, which is usually formed by doping trivalent elements (such as boron) in pure silicon crystals to replace the positions of silicon atoms in the crystal lattice. In p-type semiconductors, holes are many and free electrons are few. Since the amount of positive and negative charges in a p-type semiconductor is equal, the p-type semiconductor is electrically neutral. Holes are mainly provided by impurity atoms, and free electrons are formed by thermal excitation.

不同于传统的技术方案，根据本公开实施例的负电荷介质层104包括能够至少在与所述感光层的界面处提供预定密度的负电荷的材料，该层为单层负电荷介质层，并且单层负电荷介质层104与感光层的第一面直接接触。该单层负电荷介质层104沉积感光层的第一面，即，背面之上。这里单层是指仅有一种介质材料层而非多种介质材料形成的叠层。这意味着负电荷介质层104被设置在感光层101的第一面并与第一面直接接触，从而使得负电荷介质层104中与感光层101的界面处的固定负电荷密度高于预定阈值，例如，在有些实施例中，固定负电荷密度在10 ¹²/cm ²～10 ¹³/cm ²之间。固定负电荷即为固定地存在于介质材料中的负电荷，当介质材料与半导体材料相接触时，固定负电荷的分布主要富集在其与半导体的界面附近。这里的“固定负电荷密度”主要表示介质材料中靠近界面的预定范围(例如，从界面处到介质材料厚度的1/3或1/2的范围)内的区域的固定负电荷面密度。例如，负电荷介质层104中与感光层101的界面处的固定负电荷密度表示负电荷介质层104中在从界面处到负电荷介质层104的厚度的1/3处的固定负电荷密度。当然，应当理解的是，这里所提到的介质材料厚度的1/3或1/2只是用来表示介质材料层中靠近界面处的一个范围，而不旨在限制本公开的保护范围。靠近界面处的范围表示从界面处到介质材料厚度的从0到1的其他比例值也是可能的。 Different from traditional technical solutions, the negative charge medium layer 104 according to the embodiment of the present disclosure includes a material capable of providing a predetermined density of negative charges at least at the interface with the photosensitive layer, the layer is a single negative charge medium layer, and The single-layer negatively charged medium layer 104 is in direct contact with the first surface of the photosensitive layer. The single-layer negatively charged dielectric layer 104 is deposited on the first side of the photosensitive layer, ie, the back side. Here, a single layer refers to a layer of only one dielectric material rather than a laminate formed of multiple dielectric materials. This means that the negatively charged medium layer 104 is disposed on the first surface of the photosensitive layer 101 and is in direct contact with the first surface, so that the fixed negative charge density at the interface between the negatively charged medium layer 104 and the photosensitive layer 101 is higher than a predetermined threshold For example, in some embodiments, the fixed negative charge density is between 10 ¹² /cm ² and 10 ¹³ /cm ² . The fixed negative charge is the negative charge fixedly present in the dielectric material. When the dielectric material is in contact with the semiconductor material, the distribution of the fixed negative charge is mainly concentrated near the interface with the semiconductor. The "fixed negative charge density" here mainly refers to the fixed negative charge surface density of the area within the predetermined range (for example, from the interface to 1/3 or 1/2 of the thickness of the dielectric material) near the interface in the dielectric material. For example, the fixed negative charge density at the interface with the photosensitive layer 101 in the negative charge medium layer 104 means the fixed negative charge density in the negative charge medium layer 104 at 1/3 of the thickness from the interface to the negative charge medium layer 104 . Of course, it should be understood that the 1/3 or 1/2 of the thickness of the dielectric material mentioned here is only used to indicate a range near the interface in the dielectric material layer, and is not intended to limit the protection scope of the present disclosure. Other scaling values from 0 to 1 are possible with the range near the interface representing the thickness of the dielectric material from the interface.

本公开考虑靠近界面的预定范围内的区域的固定负电荷面密度主要是出于以下几点原因：一是界面附近的固定负电荷对半导体侧(即，感光层侧)的表面电势的影响更大，对暗电流抑制以及抗辐照性能提高的贡献也更为突出；二是介质材料中固定负电荷的分布也是不均匀的，靠近与半导体材料的界面处的固定负电荷分布更多。因此，本文中所讨论的固定负电荷密度主要表示介质材料中靠近其与半导体材料界面的预定范围内的区域的固定负电荷面密度。The present disclosure considers the area density of fixed negative charges within a predetermined range close to the interface mainly for the following reasons: First, the influence of fixed negative charges near the interface on the surface potential of the semiconductor side (that is, the photosensitive layer side) is greater The contribution to the suppression of dark current and the improvement of radiation resistance is also more prominent; the second is that the distribution of fixed negative charges in the dielectric material is also uneven, and the distribution of fixed negative charges near the interface with the semiconductor material is more. Therefore, the fixed negative charge density discussed in this paper mainly refers to the fixed negative charge areal density of a region within a predetermined range close to the interface between the dielectric material and the semiconductor material.

负电荷介质层104与感光层101的背面直接接触表示感光层101的背面被处理为使得界面处不存在或者仅存在不可避免的厚度小于1nm的感光层101的自然氧化层，并且不具有任何其他氧化层或介质层。不存在自然氧化层可以是指完全没有自然氧化层，例如，这可以通过在无氧环境中操作或者其他任意适当的方式来实现。本文中所提到的不存在自然氧化层也可以是指自然氧化层的厚度小于1nm就可以被认定为不存在自然氧化层。这是由于在常规的操作中，半导体材料制成的感光层101会不可避免地形成自然氧化层。The direct contact of the negative charge medium layer 104 with the back of the photosensitive layer 101 means that the back of the photosensitive layer 101 is processed so that there is no or only the inevitable natural oxide layer of the photosensitive layer 101 with a thickness less than 1 nm at the interface, and does not have any other oxide layer or dielectric layer. Absence of native oxide may mean complete absence of native oxide, for example, by operating in an oxygen-free environment or by any other suitable means. The non-existence of the natural oxide layer mentioned herein may also mean that the thickness of the natural oxide layer is less than 1 nm, which can be considered as the absence of the natural oxide layer. This is because in normal operation, the photosensitive layer 101 made of semiconductor material will inevitably form a natural oxide layer.

为了消除自然氧化层对负电荷介质层104与感光层101的背面直接接触的影响，在形成负电荷介质层104之前，可以对感光层101的背面进行适当的处理。处理方式可以包括通过稀释氢氟酸的湿法刻蚀实现或者通过等离子体处理来实现。这些处理可以在对感光层101减薄之后进行。上述两种处理方式一方面可以去除自然氧化层，从而确保负电荷介质层104与感光层101的背面直接接触。另一方面可以提高感光层的背面的表面质量，从而实现化学钝化的效果。In order to eliminate the influence of the natural oxide layer on the direct contact between the negatively charged medium layer 104 and the backside of the photosensitive layer 101 , the backside of the photosensitive layer 101 may be properly treated before forming the negatively charged medium layer 104 . Treatment may include wet etching with dilute hydrofluoric acid or plasma treatment. These treatments may be performed after thinning the photosensitive layer 101 . The above two treatment methods can remove the natural oxide layer on the one hand, so as to ensure that the negatively charged dielectric layer 104 is in direct contact with the back of the photosensitive layer 101 . On the other hand, the surface quality of the back side of the photosensitive layer can be improved, thereby achieving the effect of chemical passivation.

根据本公开实施例的图像传感器由于引入了与感光层101的第一面直接接触的负电荷介质层104，能够在单层负电荷介质层104中与半导体层(即，感光层101)的界面处形成有密度高于预定阈值的固定负电荷，从而使得界面处的能带向上弯曲，费米能级向价带移动，产生空穴的富集并形成较强的内建电场，来由此减少界面处的电子浓度从而达到场效应钝化的效果，并由此有效地降低暗电流。在一些实施例中，界面处的费米能级大致处于价带Ev之下。The image sensor according to the embodiment of the present disclosure introduces the negatively charged dielectric layer 104 in direct contact with the first surface of the photosensitive layer 101, and can achieve a single-layer negatively charged dielectric layer 104 at the interface with the semiconductor layer (that is, the photosensitive layer 101). There is a fixed negative charge with a density higher than the predetermined threshold, so that the energy band at the interface bends upward, and the Fermi level moves to the valence band, resulting in the enrichment of holes and the formation of a strong built-in electric field, thereby Reduce the electron concentration at the interface to achieve the effect of field effect passivation, and thus effectively reduce the dark current. In some embodiments, the Fermi level at the interface is approximately below the valence band Ev.

具体而言，如图4所示，其中(a)部分示出了无固定负电荷的单介质层与半导体材料的界面处的内建电场和电子势垒的示意图；(b)示出了多介质叠层与半导体材料的界面处的内建电场和电子势垒的示意图，(c)示出了采用单负电荷介质层104与半导体材料层(即，感光层101)直接接触的情况下，单负电荷介质层104与半导体材料的界面处的内建电场和电子势垒的示意图。在图4中，ψ _bi为内建电势，Ec和Ev是分别对应于半导体能带中的导带和价带而言的。导带是由自由电子形成的能量空间，即，固体结构内***的电子所具有的能量范围。价带，又被称为价电带，通常是指半导体或绝缘体中，在0K时能被电子占满的最高能带。导带的底能级表示为Ec，价带的顶能级表示为Ev，Ec与Ev之间的能量间隔称为禁带Eg。图4中的EF表示费米能级。从图4中可以很明显地看出，利用负电荷介质层104和半导体材料(即，感光层101)之间的强电偶极子作用，负电荷介质层104中的固定负电荷的存在使得介质层/半导体的界面处产生一个较大的内建电场和电子势垒，表现为电容-电压(Capacitance-Voltage,C-V)曲线上平带电压VFB(Flat-Band Voltage)的正向增大，如图5所示。 Specifically, as shown in Figure 4, wherein part (a) shows a schematic view of the built-in electric field and the electronic potential barrier at the interface between a single dielectric layer without a fixed negative charge and a semiconductor material; (b) shows multiple A schematic diagram of the built-in electric field and electron potential barrier at the interface between the dielectric stack and the semiconductor material, (c) shows the case where the single negatively charged dielectric layer 104 is in direct contact with the semiconductor material layer (i.e., the photosensitive layer 101), A schematic diagram of the built-in electric field and electron potential barrier at the interface between the single negatively charged dielectric layer 104 and the semiconductor material. In Figure 4, ψ _bi is the built-in potential, and Ec and Ev correspond to the conduction band and valence band in the semiconductor energy band, respectively. The conduction band is the energy space formed by free electrons, ie, the range of energies possessed by freely moving electrons within solid structures. The valence band, also known as the valence band, usually refers to the highest energy band that can be occupied by electrons at 0K in semiconductors or insulators. The bottom energy level of the conduction band is expressed as Ec, the top energy level of the valence band is expressed as Ev, and the energy interval between Ec and Ev is called the forbidden band Eg. EF in FIG. 4 represents the Fermi level. As can be clearly seen from FIG. 4, the presence of fixed negative charges in the negatively charged dielectric layer 104 makes A large built-in electric field and electronic barrier is generated at the interface of the dielectric layer/semiconductor, which is manifested as a positive increase of the flat-band voltage VFB (Flat-Band Voltage) on the capacitance-voltage (Capacitance-Voltage, CV) curve, As shown in Figure 5.

平带电压是指在金属-氧化物-半导体(Metal Oxide Semiconductor,MOS)***中，使半导体表面能带拉平(呈平带状态)所需要外加的电压。平带状态一般是指理想MOS***中各个区域的能带都是拉平的一种状态。对于实际的MOS***，由于金属-半导体功函数差φms和半导体与氧化物界面附近及氧化物内部固定电荷的影响，在外加栅极电压为0时，半导体表面的能带即发生了弯曲，从而这时需要另外再加上一定的电压才能使能带拉平，这个额外所加的电压就称为平带电压。The flat band voltage refers to the external voltage required to flatten the energy band of the semiconductor surface (in a flat band state) in a metal-oxide-semiconductor (Metal Oxide Semiconductor, MOS) system. The flat-band state generally refers to a state in which the energy bands of each region in an ideal MOS system are flattened. For the actual MOS system, due to the metal-semiconductor work function difference φms and the influence of fixed charges near the interface between the semiconductor and the oxide and inside the oxide, when the external gate voltage is 0, the energy band on the semiconductor surface is bent, thus At this time, a certain voltage needs to be added to enable the band to be leveled. This additional voltage is called the flat band voltage.

在单层负电荷介质层104和半导体层(即，感光层101)的界面处的平带电压的增大一方面说明界面处能带向上弯曲，费米能级向价带移动，从而产生空穴富集，使得禁带中的界面态和陷阱能级能够被填充的概率变小。另一方面，界面附近的能带弯曲能够形成对电子的排斥场，从而阻止了自由电子向界面处的运动，从而达到了抑制暗电流的目的。此外，大的平带电压说明了在负电荷介质层中靠近界面处存在着足够多的固定负电荷，使得半导体层表面电子势垒增大，从而能够更有效地抑制电子的运动和界面态对暗电流的影响，并由此有效地抑制暗电流。负电荷介质层的界面处的固定负电荷的产生可以源自多种因素，这些因素包括但不限于：来自介质层的生长过程或者工艺处理过程、或者来自介质层与半导体的界面晶格的匹配或者两者的组合。以此方式，在一些实施例中，负电荷介质层104中的固定负电荷数量，特别是界面处的固定负电荷密度，可以通过调制工艺条件等方式来进行优化和调节，从而实现对平带电压的调节。当然，应当理解的是，上述固定负电荷的两种产生因素只是示例性的，只要是能够达到所需的固定负电荷密度，任意适当的产生方式都是可能的。On the one hand, the increase of the flat-band voltage at the interface of the single-layer negative charge dielectric layer 104 and the semiconductor layer (i.e., the photosensitive layer 101) shows that the energy band at the interface is bent upward, and the Fermi level moves to the valence band, thereby creating a void The enrichment of holes makes the interface state and trap energy level in the forbidden band less likely to be filled. On the other hand, the band bending near the interface can form a repulsive field for electrons, thereby preventing the movement of free electrons to the interface, thereby achieving the purpose of suppressing dark current. In addition, the large flat-band voltage indicates that there are enough fixed negative charges near the interface in the negatively charged dielectric layer, which increases the electronic potential barrier on the surface of the semiconductor layer, which can more effectively inhibit the movement of electrons and the interface state on the surface of the semiconductor layer. The effect of dark current, and thus effectively suppress the dark current. The generation of fixed negative charges at the interface of the negatively charged dielectric layer can originate from a variety of factors, including but not limited to: from the growth process or process of the dielectric layer, or from the interface lattice matching of the dielectric layer and the semiconductor or a combination of both. In this way, in some embodiments, the amount of fixed negative charges in the negative charge dielectric layer 104, especially the density of fixed negative charges at the interface, can be optimized and adjusted by modulating process conditions, etc., so as to achieve flat band voltage regulation. Of course, it should be understood that the above two factors for generating the fixed negative charges are only exemplary, and any appropriate generation method is possible as long as the desired fixed negative charge density can be achieved.

同时，前文中提到了由于传统的抑制暗电流的手段中都采用了多介质叠层，从而使得总电离剂量效应容易在各个介质层以及介质层与半导体层之间产生电荷富集并诱发界面态，从而存在抗辐照性较差的问题。相比之下，根据本公开实施例的图像传感器只使用了单层负电荷介质层104与感光层101直接接触，与传统方案中采用多介质叠层的方案相比，在高能粒子200的辐照下，能够有效地减少或避免多介质叠层由于总电离剂量效应带来的抗辐照性较差的问题，从而有效地提高了图像传感器的抗辐照性。At the same time, as mentioned above, because the traditional means of suppressing dark current use multi-dielectric stacks, the total ionization dose effect is easy to generate charge enrichment and induce interface states in each dielectric layer and between the dielectric layer and the semiconductor layer. , so there is a problem of poor radiation resistance. In contrast, the image sensor according to the embodiment of the present disclosure only uses a single layer of negatively charged dielectric layer 104 in direct contact with the photosensitive layer 101. Under the irradiation, the problem of poor radiation resistance caused by the total ionizing dose effect of the multi-media stack can be effectively reduced or avoided, thereby effectively improving the radiation resistance of the image sensor.

在一些实施例中，负电荷介质层104为单介质层。相比于多介质叠层而言，单层负电荷介质层104能够提供更高的有效固定负电荷密度。对于多介质叠层而言，负电荷介质层中的固定负电荷会和其他介质层中以及介质界面中的正电荷存在抵消作用，导致有效固定负电荷密度减少。有效固定负电荷密度被定义为考虑多介质叠层之间的电荷抵消作用后的介质叠层结构的总的电荷密度。与多介质叠层结构相比，单负电荷介质层结构一方面能够提供更强的电偶极子作用和场钝化效果，从而能够提供更强地对抗高能粒子200辐照的能力。另一方面，作为单介质层的负电荷介质层104与半导体的界面处能够提供更快的介电弛豫过程。介电弛豫又称介电松弛，是指电介质在外电场作用(或移去)后，从瞬时建立的极化状态达到新的极化平衡态的过程。较快的介电弛豫过程使得界面处的电偶极子层的极性即使在高能粒子200辐照下被改变也能够快速恢复，并且使得高能粒子辐照产生的额外电荷可以快速的被输运和释放以保持原本的电势分布不被改变，从而能够更好地对抗高能粒子200辐照。由此可见，与传统的多介质叠层的方案相比，根据本公开实施例所采用的单层负电荷介质层104不但能够有效地提高抗辐照性能，而且较多的有效固定负电荷还能够提供更强的内建电场和更大的电子势垒，从而有效地抑制暗电流的产生。In some embodiments, the negative charge dielectric layer 104 is a single dielectric layer. Compared with the multi-dielectric stack, the single-layer negative charge dielectric layer 104 can provide a higher effective fixed negative charge density. For a multi-dielectric stack, the fixed negative charges in the negatively charged dielectric layer will offset the positive charges in other dielectric layers and the dielectric interface, resulting in a decrease in the effective fixed negative charge density. The effective fixed negative charge density is defined as the total charge density of the dielectric stack structure after considering the charge cancellation effect between the multi-dielectric stacks. Compared with the multi-layered dielectric structure, the single negatively charged dielectric layer structure can provide a stronger electric dipole effect and field passivation effect on the one hand, thereby providing a stronger ability to resist the irradiation of high-energy particles 200 . On the other hand, the interface between the negatively charged dielectric layer 104 and the semiconductor as a single dielectric layer can provide a faster dielectric relaxation process. Dielectric relaxation, also known as dielectric relaxation, refers to the process in which a dielectric reaches a new polarization equilibrium state from an instantaneously established polarization state after an external electric field is applied (or removed). The faster dielectric relaxation process enables the polarity of the electric dipole layer at the interface to be quickly restored even if it is changed under the irradiation of high-energy particles 200, and the extra charge generated by the high-energy particle irradiation can be quickly transported This and release can keep the original potential distribution unchanged, so as to be able to resist the irradiation of high-energy particles 200 better. It can be seen that, compared with the traditional multi-dielectric lamination scheme, the single-layer negatively charged dielectric layer 104 adopted in the embodiment of the present disclosure can not only effectively improve the radiation resistance performance, but also effectively fix more negative charges. It can provide a stronger built-in electric field and a larger electronic potential barrier, thereby effectively suppressing the generation of dark current.

在一些实施例中，负电荷介质层104可以包括高介电常数材料。例如，在一些实施例中，负电荷介质层104可以包括金属氧化物或者氮化物。金属氧化物例如可以包括以下中的一种：氧化铝、氧化铪、氧化镓、氧化钽、氧化镧、氧化釔、氧化锆或者氮化硅。当然，应当理解的是，上述这些材料只是负电荷介质层104的示例，并不旨在限制本公开的保护范围。只要能够在与半导体材料的界面处形成密度高于预定阈值，例如在10 ¹²/cm ²～10 ¹³/cm ²范围内的固定负电荷，任意适当的材料都是可能的。例如，在一些实施例中，负电荷介质层104的材料可以为氮化硅。 In some embodiments, the negative charge dielectric layer 104 may include a high dielectric constant material. For example, in some embodiments, the negative charge dielectric layer 104 may include metal oxide or nitride. The metal oxide may include, for example, one of aluminum oxide, hafnium oxide, gallium oxide, tantalum oxide, lanthanum oxide, yttrium oxide, zirconium oxide, or silicon nitride. Of course, it should be understood that the above-mentioned materials are only examples of the negative charge dielectric layer 104, and are not intended to limit the protection scope of the present disclosure. Any suitable material is possible as long as it can form fixed negative charges at the interface with the semiconductor material at a density higher than a predetermined threshold, for example, in the range of 10 ¹² /cm ² to 10 ¹³ /cm ² . For example, in some embodiments, the material of the negative charge dielectric layer 104 may be silicon nitride.

为了进一步提高抑制暗电流的效果，在一些实施例中，负电荷介质层104采用较薄的厚度，例如，厚度仅在2nm～8nm之间。通过采用单介质薄层，能够更加有利于在高能粒子200辐照下累积电荷的输送和释放。例如，对于传统的多介质叠层的方案，特别是在负电荷介质层104和半导体层之间包括绝缘层的方案，由于高能粒子200辐射产生的累积在各介质层界面处的电荷较难被转移，从而可能会导致暗电流的增加乃至器件的失效。相比之下，根据本公开实施例的技术方案通过采用单介质薄层，即使在高能粒子200辐射下有电荷的累积，由于负电荷介质层104的厚度较薄，所累积的电荷也能够通过界面处进行转移，从而达到释放累积电荷维持界面电势的目的。以此方式，能够进一步抑制暗电流并同时提高抗辐照性能。In order to further improve the effect of suppressing dark current, in some embodiments, the negative charge dielectric layer 104 adopts a relatively thin thickness, for example, the thickness is only between 2 nm˜8 nm. By adopting a single dielectric thin layer, it can be more conducive to the transportation and release of accumulated charges under the irradiation of high-energy particles 200. For example, for the traditional multi-dielectric stacking scheme, especially the scheme including an insulating layer between the negatively charged dielectric layer 104 and the semiconductor layer, the charge accumulated at the interface of each dielectric layer due to the radiation of high-energy particles 200 is difficult to be dissipated. Transfer, which may lead to the increase of dark current and even the failure of the device. In contrast, the technical solution according to the embodiments of the present disclosure adopts a single thin dielectric layer, even if there is charge accumulation under the radiation of high-energy particles 200, the accumulated charges can pass through due to the thinner negative charge dielectric layer 104. Transfer at the interface, so as to achieve the purpose of releasing the accumulated charge and maintaining the interface potential. In this way, dark current can be further suppressed while improving radiation resistance.

在一些实施例中，负电荷介质层104可以通过原子层沉积(Atomic Layer Deposition,ALD)的方式直接在感光层101的背面形成，沉积温度可以在150℃～300℃之间。原子层沉积是一种可以将物质以单原子膜形式一层一层的镀在基底表面的方法。原子层沉积与普通的化学沉积有相似之处。但在原子层沉积过程中，新一层原子膜的化学反应是直接与之前一层相关联的，这种方式使每次反应只沉积一层原子。以此方式形成的负电荷介质层104能够具备较好的介质层质量和较高的固定负电荷密度。In some embodiments, the negatively charged dielectric layer 104 can be directly formed on the back of the photosensitive layer 101 by atomic layer deposition (Atomic Layer Deposition, ALD), and the deposition temperature can be between 150°C and 300°C. Atomic layer deposition is a method that can coat substances layer by layer on the surface of a substrate in the form of a single atomic film. Atomic layer deposition is similar to ordinary chemical deposition. But in ALD, the chemical reaction of a new atomic film is directly linked to the previous one, in such a way that only one layer of atoms is deposited per reaction. The negative charge dielectric layer 104 formed in this way can have better dielectric layer quality and higher fixed negative charge density.

当然，应当理解的是，上文中提到的关于通过原子层沉积形成负电荷介质层104的实施例只是示意性的，并不旨在限制本公开的保护范围。其他任意适当的沉积方式也是可能的。例如，在一些替代的实施例中，负电荷介质层104也可以通过等离子增强化学气相沉积法(Plasma Enhanced Chemical Vapor Deposition,PECVD)、循环化学气相沉积法(Cycle Chemical Vapor Deposition,Cycle-CVD)、溶胶凝胶法(Sol-Gel)或者物理气相沉积(Physical Vapor Deposition，PVD)的溅射法来形成。Of course, it should be understood that the above-mentioned embodiment of forming the negatively charged dielectric layer 104 by atomic layer deposition is only illustrative, and is not intended to limit the protection scope of the present disclosure. Any other suitable deposition method is also possible. For example, in some alternative embodiments, the negatively charged dielectric layer 104 can also be deposited by plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD), cycle chemical vapor deposition (Cycle Chemical Vapor Deposition, Cycle-CVD), Sol-Gel method (Sol-Gel) or Physical Vapor Deposition (Physical Vapor Deposition, PVD) sputtering method to form.

根据本公开的另一方面还提供了一种制备图像传感器的方法。图6示出了该方法的流程图。如图6所示，在框410中，提供衬底102。在框420，在硅片上形成感光层101，并在感光层101的正面形成布线层103。感光层中的感光阵列单元能够接收由背面入射的高能粒子200并将高能粒子200转换成电信号。在框430，将感光层101经由布线层103而耦合至衬底102。According to another aspect of the present disclosure, a method of manufacturing an image sensor is also provided. Fig. 6 shows a flowchart of the method. As shown in FIG. 6, in block 410, a substrate 102 is provided. At block 420 , a photosensitive layer 101 is formed on the silicon wafer, and a wiring layer 103 is formed on the front side of the photosensitive layer 101 . The photosensitive array unit in the photosensitive layer can receive the high-energy particles 200 incident from the back and convert the high-energy particles 200 into electrical signals. At block 430 , the photosensitive layer 101 is coupled to the substrate 102 via the wiring layer 103 .

在一些实施例中，在感光层101的背面设置或生长负电荷介质层104之前，该方法还包括对感光层101的厚度减薄的步骤。厚度减薄能够有利于高能粒子200从背部的入射和有效收集。在对感光层101的厚度减薄之后，还对背面进行进一步处理以消除感光层101表面的自然氧化层。如前文中所提到的，处理方式可以包括通过稀释氢氟酸的湿法刻蚀实现或者通过等离子体处理等。这些处理可以在对感光层101减薄之后进行。上述两种处理方式一方面可以去除自然氧化层，从而确保负电荷介质层104与感光层101的背面直接接触。另一方面可以提高背面的表面质量，从而实现化学钝化的效果。In some embodiments, before disposing or growing the negatively charged medium layer 104 on the backside of the photosensitive layer 101 , the method further includes a step of reducing the thickness of the photosensitive layer 101 . Thinning can facilitate the incidence and effective collection of high-energy particles 200 from the back. After reducing the thickness of the photosensitive layer 101 , the backside is further processed to eliminate the natural oxide layer on the surface of the photosensitive layer 101 . As mentioned above, the treatment may include wet etching with dilute hydrofluoric acid or plasma treatment. These treatments may be performed after thinning the photosensitive layer 101 . The above two treatment methods can remove the natural oxide layer on the one hand, so as to ensure that the negatively charged dielectric layer 104 is in direct contact with the back of the photosensitive layer 101 . On the other hand, it can improve the surface quality of the back, so as to achieve the effect of chemical passivation.

在经过厚度减薄以及表面处理之后，在框440，在感光层101的背面设置负电荷介质层104，并使得负电荷介质层104直接接触，来最终使得负电荷介质层104中与感光层101的背面的界面处的固定负电荷密度在10 ¹²/cm ²～10 ¹³/cm ²之间。以此方式形成的用于图像传感器的电子设备，如前文中所提到的，能够有效抑制暗电流的同时还具有优异的抗辐照性能，从而使得所制备的图像传感器能够应用于扫描电子显微镜的二次电子和背散射电子探测器、X射线探测器、用于航空航天的抗辐照图像传感器、粒子碰撞的辐射探测器等。 After thickness reduction and surface treatment, in block 440, the negatively charged medium layer 104 is provided on the back of the photosensitive layer 101, and the negatively charged medium layer 104 is directly contacted, so that the negatively charged medium layer 104 and the photosensitive layer 101 are finally formed. The fixed negative charge density at the interface on the back side is between 10 ¹² /cm ² and 10 ¹³ /cm ² . Electronic devices for image sensors formed in this way, as mentioned above, can effectively suppress dark current and have excellent radiation resistance, so that the prepared image sensors can be applied to scanning electron microscopes Secondary electron and backscattered electron detectors, X-ray detectors, radiation-resistant image sensors for aerospace, radiation detectors for particle collisions, etc.

另外，尽管上述步骤以特定顺序被描绘，但这并不应该理解为要求这些步骤以示出的特定顺序或以相继顺序完成，或者执行所有图示的操作以获取期望结果。在某些情况下，多任务或并行处理会是有益的。同样地，尽管上述论述包含了某些特定的实施细节，但这并不应解释为限制任何发明或权利要求的范围，而应解释为对可以针对特定发明的特定实施例的描述。本说明书中在分离的实施例的上下文中描述的某些特征也可以整合实施在单个实施例中。反之，在单个实施例的上下文中描述的各种特征也可以分离地在多个实施例或在任何合适的子组合中实施。In addition, while the above steps are depicted in a particular order, this should not be understood as requiring that the steps be performed in the particular order shown, or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing can be beneficial. Likewise, while the above discussion contains certain specific implementation details, these should not be construed as limitations on the scope of any invention or claims, but rather as a description of particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

本公开实施例还提供了一种粒子探测器。该粒子探测器使用了前文中所提到的图像传感器以及用于存储该图像传感器所获取的数据的存储器。得益于该图像传感器优异的抗辐照性能和抑制暗电流性能，使得该粒子探测器能够作为可靠地和精确地用于扫描电子显微镜的二次电子和背散射电子探测器、X射线探测器、用于航空航天的抗辐照图像传感器、粒子碰撞的辐射探测器等来使用。The embodiment of the present disclosure also provides a particle detector. The particle detector uses the aforementioned image sensor and a memory for storing data acquired by the image sensor. Thanks to the excellent anti-irradiation performance and dark current suppression performance of the image sensor, the particle detector can be used as a secondary electron and backscattered electron detector and X-ray detector for scanning electron microscopes reliably and accurately. , radiation-resistant image sensors for aerospace, radiation detectors for particle collisions, etc.

尽管已经以特定于结构特征和/或方法动作的语言描述了主题，但是应当理解，所附权利要求中限定的主题并不限于上文描述的特定特征或动作。相反，上文描述的特定特征和动作是作为实现权利要求的示例形式而被公开的。Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

一种图像传感器，其特征在于，包括：An image sensor, characterized in that, comprising:

衬底；Substrate;

感光层，包括感光阵列单元，所述感光阵列单元用于接收由所述感光层的第一面入射的高能粒子并将所述高能粒子转换成电信号；The photosensitive layer includes a photosensitive array unit, the photosensitive array unit is used to receive high-energy particles incident from the first surface of the photosensitive layer and convert the high-energy particles into electrical signals;

布线层，布置在所述所述感光层与所述衬底之间，且与所述感光层中与所述第一面相对的第二面贴合；以及a wiring layer arranged between the photosensitive layer and the substrate, and attached to a second surface of the photosensitive layer opposite to the first surface; and

负电荷介质层，沉积在所述感光层的所述第一面之上。A negative charge medium layer is deposited on the first surface of the photosensitive layer.
根据权利要求1所述的图像传感器，其特征在于，所述负电荷介质层为单介质层。The image sensor according to claim 1, wherein the negatively charged dielectric layer is a single dielectric layer.
根据权利要求1所述的图像传感器，其特征在于，所述负电荷介质层包括高介电常数材料。The image sensor according to claim 1, wherein the negative charge dielectric layer comprises a high dielectric constant material.
根据权利要求1-3中任一项所述的图像传感器，其特征在于，所述负电荷介质层中与所述感光层的界面处的固定负电荷的密度高于预定阈值。The image sensor according to any one of claims 1-3, characterized in that the density of fixed negative charges at the interface between the negative charge medium layer and the photosensitive layer is higher than a predetermined threshold.
根据权利要求4所述的图像传感器，其特征在于，所述预定阈值被选择为用于抑制界面处的暗电流的产生。The image sensor according to claim 4, wherein the predetermined threshold is selected to suppress generation of dark current at the interface.
根据权利要求1-5中任一项所述的图像传感器，其特征在于，所述负电荷介质层用于使得所述感光层中与所述负电荷介质层的界面处的费米能级大致位于价带之下。The image sensor according to any one of claims 1-5, wherein the negative charge medium layer is used to make the Fermi energy level at the interface between the photosensitive layer and the negative charge medium layer approximately below the price band.
根据权利要求1-6中任一项所述的图像传感器，其特征在于，所述负电荷介质层中与所述感光层的界面处的所述固定负电荷的密度在10 ¹²/cm ²～10 ¹³/cm ²之间。 The image sensor according to any one of claims 1-6, characterized in that the density of the fixed negative charges at the interface between the negative charge medium layer and the photosensitive layer is between 10 ¹² /cm ² and Between 10 ¹³ /cm ² .
根据权利要求1-7中任一项所述的图像传感器，其特征在于，所述负电荷介质层包括金属氧化物或氮化物。The image sensor according to any one of claims 1-7, characterized in that the negatively charged medium layer comprises metal oxide or nitride.
根据权利要求1-8中任一项所述的图像传感器，其特征在于，所述负电荷介质层包括能够至少在与所述感光层的界面处提供预定密度的负电荷的材料。The image sensor according to any one of claims 1-8, wherein the negative charge medium layer comprises a material capable of providing a predetermined density of negative charges at least at an interface with the photosensitive layer.
根据权利要求9所述的图像传感器，其特征在于，所述负电荷介质层包括以下中的一种：氧化铝、氧化铪、氧化镓、氧化钽、氧化镧、氧化釔、氧化锆或者氮化硅。The image sensor according to claim 9, wherein the negative charge dielectric layer comprises one of the following: aluminum oxide, hafnium oxide, gallium oxide, tantalum oxide, lanthanum oxide, yttrium oxide, zirconium oxide or nitride silicon.
根据权利要求1-10中的任一项所述的图像传感器，其特征在于，所述负电荷介质层的厚度在2nm～8nm之间。The image sensor according to any one of claims 1-10, characterized in that the thickness of the negatively charged medium layer is between 2nm and 8nm.
根据权利要求1-11中的任一项所述的图像传感器，其特征在于，所述负电荷介质层通过原子层沉积的方式形成在所述感光阵列单元的所述第一面。The image sensor according to any one of claims 1-11, wherein the negatively charged dielectric layer is formed on the first surface of the photosensitive array unit by means of atomic layer deposition.
根据权利要求1-12中的任一项所述的图像传感器，其特征在于，所述感光阵列单元的至少第一面部分是经掺杂的p型硅。The image sensor according to any one of claims 1-12, characterized in that at least the first surface portion of the photosensitive array unit is doped p-type silicon.
根据权利要求1-13中任一项所述的图像传感器，其特征在于，所述感光层的所述第一面被处理，以使得所述界面处不存在或者仅存在厚度小于1nm的所述感光阵列单元的自然氧化层。The image sensor according to any one of claims 1-13, characterized in that, the first surface of the photosensitive layer is processed so that there is no or only the layer with a thickness less than 1 nm at the interface. The natural oxide layer of the photosensitive array unit.
根据权利要求1-14中任一项所述的图像传感器，其中所述固定负电荷通过以下中的任一种而产生：所述负电荷介质层的生长过程、和所述负电荷介质层与所述感光阵列单元的界面的晶格匹配。The image sensor according to any one of claims 1-14, wherein the fixed negative charges are generated by any of the following: the growth process of the negatively charged dielectric layer, and the interaction of the negatively charged dielectric layer with The lattice matching of the interface of the photosensitive array unit.
一种制备图像传感器的方法，其特征在于，包括：A method for preparing an image sensor, comprising:

提供衬底；provide the substrate;

形成包括感光阵列单元的感光层并在所述感光层的第二面形成布线层，所述感光阵列单元用于接收由所述感光层的第一面入射的高能粒子并将所述高能粒子转换成电信号，所述第一面和所述第二面相对；forming a photosensitive layer including a photosensitive array unit and forming a wiring layer on the second surface of the photosensitive layer, the photosensitive array unit is used for receiving high-energy particles incident from the first surface of the photosensitive layer and converting the high-energy particles forming an electrical signal, the first surface is opposite to the second surface;

将所述感光层经由所述布线层耦合至所述衬底；以及coupling the photosensitive layer to the substrate via the wiring layer; and

在所述感光层的所述第一面之上沉积负电荷介质层。A negatively charged dielectric layer is deposited over the first side of the photosensitive layer.
根据权利要求14所述的方法，其特征在于，在将所述感光层经由所述布线层耦合至所述衬底还包括：The method according to claim 14, wherein coupling the photosensitive layer to the substrate via the wiring layer further comprises:

处理所述所述感光层的所述第一面以减薄所述感光层的厚度；以及treating the first side of the photosensitive layer to reduce the thickness of the photosensitive layer; and

对减薄后的感光层的所述第一面进行处理以去除自然氧化层，使得所述高介电常数材料层和所述感光层的界面处不存在自然氧化层或者仅存在厚度小于1nm的自然氧化层。Treating the first surface of the thinned photosensitive layer to remove the natural oxide layer, so that there is no natural oxide layer at the interface between the high dielectric constant material layer and the photosensitive layer or only a layer with a thickness of less than 1 nm exists. natural oxide layer.
一种粒子探测器，其特征在于，包括：A particle detector, characterized in that it comprises:

根据权利要求1-13中任一项所述的图像传感器，所述图像传感器感测高能粒子并基于由高能粒子入射而转换的电信号提供数据；以及An image sensor according to any one of claims 1-13, which senses energetic particles and provides data based on electrical signals converted from incident energetic particles; and

存储器，用于存储由所述图像传感器所提供的数据。a memory for storing data provided by the image sensor.