WO2020057017A1

WO2020057017A1 - Silicon-based monolithic infrared pixel sensor

Info

Publication number: WO2020057017A1
Application number: PCT/CN2019/070515
Authority: WO
Inventors: 汪巍; 方青; 涂芝娟; 曾友宏; 蔡艳; 王庆; 王书晓; 余明斌
Original assignee: 中国科学院上海微系统与信息技术研究所; 上海新微科技服务有限公司
Priority date: 2018-09-21
Filing date: 2019-01-05
Publication date: 2020-03-26
Also published as: CN208923139U

Abstract

Provided is a silicon-based monolithic infrared pixel sensor, the silicon-based monolithic infrared pixel sensor comprises: a silicon-based substrate; a buffer layer located on the silicon-based substrate; an infrared detector and a transistor located on the buffer layer, wherein the infrared detector uses germanium tin (GeSn) material, the thickness of the buffer layer is 0.5-2 microns, and a protective layer that also serves as an anti-reflection layer, so as to promote absorption of infrared light by the infrared detector. According to the present application, the infrared detector is is made of the germanium tin (GeSn) material, so that the photoelectric detector and the transistor can be integrated in one silicon substrate to form the monolithic infrared pixel sensor by combining the high response characteristic of the germanium tin (GeSn) material in an infrared band under a standard CMOS process.

Description

Silicon-based single-chip infrared pixel sensor

Technical field

The present application relates to the field of semiconductor technology, and in particular, to a silicon-based monolithic infrared pixel sensor.

Background technique

Infrared image sensors have important applications in military, defense, medical, and automatic imaging. Currently, semiconductor materials used for infrared image sensors include III-V group materials InGaAs, GaInAsSb, InGaSb, etc., II-VI materials HgCdTe, and IV group materials Ge, GeSn, and the like. The III-V detectors have excellent performance in the near-infrared band, while the II-VI detectors are mainly used in the mid-far infrared band.

The basic unit of a complementary metal oxide semiconductor (CMOS) image sensor is a pixel sensor. Pixel sensors are divided into passive pixel sensors and active pixel sensors, which are composed of a photodetector and one or more transistors.

It should be noted that the above description of the technical background is merely for the convenience of a clear and complete description of the technical solution of the present application, and for the understanding of those skilled in the art. The above technical solutions should not be considered to be well known to those skilled in the art just because these solutions are explained in the background section of this application.

Summary of the Invention

In the prior art, regardless of III-V or II-VI materials, the manufacturing cost is very high, and it will cause environmental problems; in addition, it is incompatible with silicon (Si) -based CMOS technology, making it difficult to integrate photodetectors and transistors Integrated in one substrate.

Embodiments of the present application provide a silicon-based monolithic infrared pixel sensor and a method for manufacturing the same. An infrared detector made of a germanium tin (GeSn) material is formed on a silicon-based substrate.

GeSn GeSn material has a large absorption coefficient in the short-wave infrared to mid-infrared band, which can be used to prepare infrared detectors; and GeSn materials have higher carrier migration than germanium (Ge) materials and silicon (Si) materials Rate can also be used to prepare high-speed transistors.

In the silicon-based monolithic infrared pixel sensor of the present application, since the infrared detector is made of germanium tin (GeSn) material, the high response characteristics of the germanium tin (GeSn) material of the infrared detector in the infrared band can be realized.

According to an aspect of the embodiments of the present application, a silicon-based single-chip infrared pixel sensor is provided, including:

A silicon-based substrate; a buffer layer on the silicon-based substrate; and an infrared detector and a transistor on the buffer layer, wherein, in the infrared detector, the buffer layer has a thickness of 0.5 to 2 microns, and It includes a protective layer that doubles as an anti-reflection layer to promote absorption of infrared light by the infrared detector.

In other embodiments, the transistor may also be made of germanium tin (GeSn) material. Therefore, the high response characteristics of the germanium tin (GeSn) material in the infrared band and the high mobility characteristics of the germanium tin (GeSn) material transistor can be combined; In addition, since the preparation process of germanium tin (GeSn) material is compatible with the standard CMOS process, the photodetector and the transistor can be integrated in a silicon substrate to form a monolithic infrared pixel sensor under the standard CMOS process. High integration and low cost of monolithic infrared pixel sensor. According to another aspect of the embodiments of the present application, a material of the silicon-based substrate is silicon or silicon on an insulator, and a material of the buffer layer is germanium or silicon germanium (SiGe).

According to another aspect of the embodiments of the present application, wherein the infrared detector includes: an n-type contact layer, an infrared light absorption layer, and a p-type contact layer in order from the side close to the buffer layer and away from the buffer layer side, The material of the n-type contact layer and the p-type contact layer is germanium (Ge) or germanium tin (GeSn), and the material of the infrared light absorption layer is germanium tin (GeSn).

According to another aspect of the embodiments of the present application, wherein the infrared detector and the transistor are electrically connected through a conductive material.

According to another aspect of the embodiments of the present application, wherein the anti-protective layer is SiO ₂ .

According to another aspect of the embodiments of the present application, wherein the buffer layer has a thickness of 1 micron.

This application also provides a method for manufacturing a silicon-based monolithic infrared pixel sensor, including:

Forming a buffer layer on a silicon-based substrate; forming an infrared detector and a transistor on the buffer layer, wherein:

The infrared detector uses germanium tin (GeSn) material.

According to another aspect of the embodiments of the present application, forming an infrared detector and a transistor on the buffer layer includes:

Forming an n-type contact layer of the infrared detector on the buffer layer;

Forming a germanium tin (GeSn) material layer on the n-type contact layer;

Forming a p-type contact layer of the infrared detector on the germanium tin (GeSn) material layer;

The layer of germanium tin (GeSn) material between the infrared detector and the transistor is etched away.

According to another aspect of the embodiments of the present application, forming an infrared detector and a transistor on the buffer layer further includes:

Forming a protective layer for protecting the infrared detector and the transistor; and

A contact electrode is formed on the surface of the protective layer to make electrical contact with the p-type contact layer, the n-type contact layer, the source, the drain, and the gate stack of the transistor, respectively.

The beneficial effect of the present application is that in the case of a silicon-based monolithic infrared pixel sensor, when the infrared detector is made of germanium tin (GeSn) material, the high response of the germanium tin (GeSn) material of the infrared detector in the infrared band can be achieved. characteristic. In a standard CMOS process, a photodetector and a transistor are integrated in a silicon substrate to form a monolithic infrared pixel sensor.

With reference to the following description and drawings, specific embodiments of the present application are disclosed in detail, and the manner in which the principles of the present application can be adopted is indicated. It should be understood that the embodiments of the present application are not limited in scope. Within the spirit and terms of the appended claims, the embodiments of this application include many changes, modifications, and equivalents.

Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or in place of features in other embodiments .

It should be emphasized that the term "including / comprising" as used herein refers to the presence of a feature, whole, step or component, but does not exclude the presence or addition of one or more other features, whole, steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the description, for illustrating the embodiments of the present application, and to explain the principles of the present application together with the text description. Obviously, the drawings in the following description are just some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts. In the drawings:

FIG. 1 is a schematic diagram of a silicon-based single-chip infrared pixel sensor according to Embodiment 1 of the present application; FIG.

2 is an equivalent circuit diagram of a silicon-based infrared pixel sensor according to Embodiment 1 of the present application;

3 is a schematic diagram of a method for manufacturing a silicon-based monolithic infrared pixel sensor according to Embodiment 2 of the present application;

FIG. 4 is a schematic diagram of step 302 of FIG. 3;

5 is a cross-sectional view of a device corresponding to each step in an example of Embodiment 2 of the present application.

detailed description

The foregoing and other features of the present application will become apparent from the following description with reference to the accompanying drawings. In the description and the drawings, specific embodiments of the present application are specifically disclosed, which show some of the embodiments in which the principles of the present application can be applied. It should be understood that the present application is not limited to the described embodiments. Instead, the present application The application includes all modifications, variations, and equivalents falling within the scope of the appended claims.

In the description of the embodiments of the present application, for convenience of description, a direction parallel to the main surface of the silicon-based substrate is referred to as “lateral”, and a direction perpendicular to the main surface of the silicon-based substrate is referred to as “longitudinal”.

Example 1

An embodiment of the present application provides a silicon-based single-chip infrared pixel sensor.

FIG. 1 is a schematic diagram of a silicon-based monolithic infrared pixel sensor according to this embodiment. As shown in FIG. 1, the silicon-based monolithic infrared pixel sensor 1 includes:

The silicon-based substrate 11; the buffer layer 12 on the silicon-based substrate 11; and the infrared detector 13 and the transistor 14 on the buffer layer 12, wherein the infrared detector 13 is made of germanium tin (GeSn) material.

In the silicon-based monolithic infrared pixel sensor of this embodiment, since the infrared detector is made of germanium tin (GeSn) material, it is possible to realize the use of germanium-tin (GeSn) material in the silicon-based monolithic infrared pixel sensor in the infrared band High response characteristics.

In another embodiment, the transistor can also be made of germanium tin (GeSn) material. Using the high mobility characteristics of the germanium tin (GeSn) material transistor, the preparation process of the germanium tin (GeSn) material is compatible with the standard CMOS process. Therefore, The photodetector and the transistor can be integrated in a silicon substrate to form a monolithic infrared pixel sensor under a standard CMOS process, thereby realizing the high integration and low cost of the monolithic infrared pixel sensor.

In this embodiment, the material of the silicon-based substrate 11 is silicon (Si) or silicon on insulator (SOI).

In this embodiment, the material of the buffer layer 12 is germanium (Ge) or silicon germanium (SiGe).

In this embodiment, as shown in FIG. 1, in the infrared detector 13, from the side closer to the buffer layer 12 to the side farther away from the buffer layer 12: n-type contact layer 131, infrared light absorption layer 132, and p-type contact. Layer 133.

In this embodiment, the material of the n-type contact layer 131 may be n-type germanium (Ge) or n-type germanium tin (GeSn); the material of the p-type contact layer 133 may be p-type germanium (Ge) or p Type germanium tin (GeSn).

The material of the infrared light absorbing layer 132 is germanium tin (GeSn), for example, intrinsic germanium tin (GeSn). Therefore, the infrared light absorbing layer 132 has a higher absorption efficiency for the infrared light band.

In this embodiment, as shown in FIG. 1, the transistor 14 includes a source region 142 and a drain region 143, and a gate stack 144.

In another embodiment, the transistor 14 includes a source region 142 and a drain region 143 formed in a germanium tin (GeSn) material layer 141, and a gate stack 144 formed on a surface of the germanium tin (GeSn) material layer 141. .

In this embodiment, the source region 142 and the drain region 143 may be n-type, and the region between the source region 142 and the drain region 143 corresponding to the gate stack 144 may be p-type, thereby forming n Field effect transistor (FET); or, the source region 142 and the drain region 143 may be p-type, and the region between the source region 142 and the drain region 143 corresponding to the gate stack 144 may be an n-type. As a result, a p-type field effect transistor (FET) is formed.

In this embodiment, the gate stack 144 may include a stacked high-k dielectric material layer 1441 and a metal layer 1442. The material of the high-k dielectric material layer is, for example, hafnium oxide (HfO ₂ ). The material of the metal layer is, for example, HfO ₂ . It is titanium nitride (TaN). In addition, this embodiment may not be limited to this. The high-k dielectric material layer 1441 and the metal layer 1442 may also be other materials.

As shown in FIG. 1, the infrared detector 13 and the transistor 14 can be protected by a protective layer 15. In addition, the protective layer 15 can also serve as an anti-reflection layer to promote the absorption of infrared light by the infrared detector 13.

In this embodiment, contact electrodes 16 may be formed on the surface of the protective layer 15, and each contact electrode 16 may be respectively connected to the p-type contact layer, the n-type contact layer of the infrared detector 13 through the connecting material 17 passing through the protective layer 15. The source, drain, and gate stacks of the transistor 14 are in electrical contact.

In this embodiment, the infrared detector 13 and the transistor 14 may be electrically connected through a conductive material (not shown). For example, the n-pole of the infrared detector 13 and the drain 142 of the transistor 14 are electrically connected, thereby forming a passive type. Infrared pixel sensor or active infrared pixel sensor.

FIG. 2 is an equivalent circuit diagram of the silicon-based infrared pixel sensor of this embodiment. As shown in FIG. 2, in the silicon-based infrared pixel sensor 1, the infrared detector 13 generates a photocurrent in response to external infrared light, and the photocurrent is output through the source 142 of the transistor 14.

According to this embodiment, a silicon-based monolithic infrared pixel sensor can combine the high response characteristics of germanium-tin (GeSn) materials in the infrared band. Under a standard CMOS process, a photodetector and a transistor are integrated in a silicon substrate to form a single unit. -Chip infrared pixel sensor, achieving high integration and low cost of a single-chip infrared pixel sensor.

Example 2

Embodiment 2 provides a method for manufacturing a silicon-based monolithic infrared pixel sensor, which is used to manufacture the silicon-based monolithic infrared pixel sensor described in Embodiment 1.

FIG. 3 is a schematic diagram of a method for manufacturing a silicon-based monolithic infrared pixel sensor according to this embodiment. As shown in FIG. 3, in this embodiment, the method for manufacturing the silicon-based monolithic infrared pixel sensor may include:

Step 301: Form a buffer layer 12 on a silicon-based substrate 11.

Step 302: An infrared detector 13 and a transistor 14 are formed on the buffer layer 12, wherein the infrared detector 13 is made of germanium tin (GeSn) material.

FIG. 4 is a schematic diagram of step 302 of FIG. 3. As shown in FIG. 4, step 302 may include the following steps:

Step 3021, forming an n-type contact layer of the infrared detector on the buffer layer 12;

Step 3022, forming a germanium tin (GeSn) material layer 132a on the n-type contact layer 131;

Step 3023: forming a p-type contact layer of the infrared detector on the germanium tin (GeSn) material layer 132a;

Step 3024: forming a source stack 142 and a drain electrode 143 of the transistor 14 to form a gate stack 144 of the transistor, wherein the gate stack 144 includes a stacked high-k dielectric material layer 1441 and a metal layer 1442; and

In step 3025, the germanium tin (GeSn) material layer 132a between the infrared detector 13 and the transistor 14 is etched away. Thus, the germanium tin (GeSn) material layer remaining in the infrared detector 13 is the infrared light absorbing layer 132.

In another embodiment, the transistor 14 is also made of germanium tin (GeSn) material. In step 3024, a source 142 and a drain electrode 143 of the transistor 14 are formed on the germanium tin (GeSn) material layer 132a. A GeSn) material layer 132a forms a gate stack 144 of the transistor.

In addition, in this embodiment, as shown in FIG. 4, step 302 may further include after step 3025:

Step 3026: forming a protective layer 15 for protecting the infrared detector 13 and the transistor 14; and

In step 3027, a contact electrode 16 is formed on the surface of the protective layer 15 to make electrical contact with the p-type contact layer, the n-type contact layer, the source, the drain, and the gate stack of the transistor 14 respectively.

Hereinafter, a method for manufacturing the silicon-based monolithic infrared pixel sensor of the present application will be described with a specific example.

FIG. 5 is a cross-sectional view of the device corresponding to each step in this example. As shown in FIG. 5, in this example, a method for manufacturing a silicon-based monolithic infrared pixel sensor includes the following steps:

Step 1. As shown in FIG. 5 (a):

A Ge buffer layer 12 with a thickness of 0.5 to 2 micrometers is epitaxially grown by chemical vapor deposition; an n-type Ge contact layer is grown in situ as a n-type contact layer 131 by a chemical vapor deposition method with a doping concentration greater than 2 * 10 ¹⁹ cm ^-3 ; An intrinsic GeSn layer is grown by a chemical vapor deposition method as a germanium tin (GeSn) material layer 132a with a thickness of 300 nm; a p-type Ge contact layer is grown in situ as a n-type contact layer 131 by a chemical vapor deposition method.

Preferably, the buffer layer has a thickness of about 1 micron.

Step 2. As shown in FIG. 5 (b):

The transistor region is defined by photolithography, and the p-type Ge contact layer 133 is etched to expose the intrinsic GeSn layer; the source region and drain region of the transistor 14 are defined by photolithography; 143. If phosphorus ions can be implanted, the energy is 20 keV, the dose is 1 * 10 ¹⁵ cm ^-2 , and annealing is performed at 400 ° C. for 5 minutes. TaN), or other high-k dielectric layers and metal layers; the gate stack 144 is formed by photolithography and etching.

In another embodiment, the intrinsic GeSn layer of the region of the transistor 14 can be completely etched to form a conventional CMOS transistor on the rail base.

Step 3. As shown in FIG. 5 (c):

The mesa of the GeSn infrared detector 13 is prepared by photolithography and etching processes, and is etched to an n-type Ge contact layer, so as to form an infrared light absorption layer 132 and a germanium tin (GeSn) material layer 141; a SiO ₂ protective layer 15 is deposited, It can also function as an anti-reflection layer; chemical mechanical polishing is used to planarize the surface of the SiO ₂ protective layer 15.

Step 4. As shown in (d) of FIG. 5:

The contact area is defined by photolithography and etching; the metal is deposited, and the metal surface is planarized by chemical mechanical polishing; and the contact electrode 16 is formed by photolithography and etching.

According to this embodiment, a silicon-based monolithic infrared pixel sensor can combine the high response characteristics of a germanium tin (GeSn) material in the infrared band and the high mobility characteristics of a germanium tin (GeSn) material transistor; and, in a standard CMOS process, The photodetector and the transistor are integrated in a silicon substrate to form a monolithic infrared pixel sensor, which achieves a high degree of integration and low cost of the monolithic infrared pixel sensor.

The present application has been described with reference to specific implementations, but it should be clear to those skilled in the art that these descriptions are exemplary and do not limit the scope of protection of the present application. Those skilled in the art can make various variations and modifications to this application according to the spirit and principles of this application, and these variations and modifications are also within the scope of this application.

Claims

A silicon-based monolithic infrared pixel sensor including:

Silicon-based substrate

A buffer layer on the silicon-based substrate; and

An infrared detector and a transistor on the buffer layer,

among them,

The infrared detector uses germanium tin (GeSn) material,

The buffer layer has a thickness of 0.5 to 2 microns, and further includes:

The protective layer doubles as an anti-reflection layer to promote absorption of infrared light by the infrared detector.
The silicon-based infrared pixel sensor according to claim 1, wherein:

The material of the silicon-based substrate is silicon or silicon on an insulator,

The buffer layer is made of germanium or silicon germanium (SiGe).
The silicon-based infrared pixel sensor according to claim 1, wherein:

The infrared detector includes: an n-type contact layer, an infrared light absorption layer, and a p-type contact layer in order from the side close to the buffer layer and away from the buffer layer side,

The material of the n-type contact layer and the p-type contact layer is germanium (Ge) or germanium tin (GeSn), and the material of the infrared light absorption layer is germanium tin (GeSn).
The silicon-based infrared pixel sensor according to claim 1, wherein:

The infrared detector and the transistor are electrically connected through a conductive material.
The silicon-based infrared pixel sensor according to claim 1, wherein:

The protective layer is SiO 2 .
The silicon-based infrared pixel sensor according to claim 1, wherein:

The buffer layer has a thickness of 1 micron.