阅读说明：本技术 Ge光电探测器及其制备方法 (Ge photoelectric detector and preparation method thereof ) 是由 方青 张馨丹 邵瑶 胡鹤鸣 顾苗苗 陈华 张志群 陈晓峰 于 2020-07-23 设计创作，主要内容包括：本发明提供一种Ge光电探测器及其制备方法,其中,Ge光电探测器包括热源层,进一步的还包括导热层；从而通过具有高阻值的热源层作为热源,以升高Ge吸收层的温度,使得Ge吸收层的禁带宽度降低,从而使得能量低于原Ge吸收层禁带宽度的光子被吸收,以增大Ge吸收层的吸收系数,实现Ge光电探测器探测范围的延伸,以扩大应用范围,以及通过位于Ge吸收层与热源层之间的具有较高热导率的导热层,有效地将热源层产生的热源传递到Ge吸收层,从而有效调整Ge光电探测器的响应度；因此,本发明可提供一种制备工艺简单,且可有效提高Ge光电探测器在长波长条件下的吸收系数,以扩大Ge光电探测器的探测范围及应用范围。(The invention provides a Ge photoelectric detector and a preparation method thereof, wherein the Ge photoelectric detector comprises a heat source layer and further comprises a heat conduction layer; the Ge photoelectric detector is characterized in that a heat source layer with high resistance is used as a heat source to raise the temperature of the Ge absorption layer, so that the forbidden bandwidth of the Ge absorption layer is reduced, photons with energy lower than that of the forbidden bandwidth of the original Ge absorption layer are absorbed to increase the absorption coefficient of the Ge absorption layer, the detection range of the Ge photoelectric detector is extended to enlarge the application range, and a heat source generated by the heat source layer is effectively transmitted to the Ge absorption layer through a heat conduction layer with high heat conductivity between the Ge absorption layer and the heat source layer, so that the responsivity of the Ge photoelectric detector is effectively adjusted; therefore, the invention can provide a method which has simple preparation process and can effectively improve the absorption coefficient of the Ge photoelectric detector under the long wavelength condition so as to expand the detection range and the application range of the Ge photoelectric detector.)

1. A Ge photodetector, comprising:

the Si waveguide comprises a bottom Si layer, an oxygen burying layer and a top Si layer which are sequentially overlapped; the top Si layer comprises a P-type doped contact region, an I-type region and an N-type doped contact region which are sequentially arranged in the horizontal direction;

a Ge absorbing layer on the I-type region;

the passivation layer covers the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

a heat source layer located above the Ge absorbing layer;

and the metal electrode penetrates through the passivation layer and is in contact with the P-type doped contact region and the N-type doped contact region.

2. The Ge photodetector of claim 1, wherein: the range of the thickness D of the passivation layer between the heat source layer and the Ge absorption layer comprises that D is more than or equal to 0.5 mu m.

3. The Ge photodetector of claim 1, wherein: the heat source layer includes one or a combination of a TiN layer and a TaN layer.

4. The Ge photodetector of claim 1, wherein: the heat source layer is located between the Ge absorption layer and the heat source layer, and the heat conduction layer is larger than the passivation layer in heat conductivity.

5. The Ge photodetector of claim 4, wherein: and two opposite surfaces of the heat conduction layer are respectively contacted with the Ge absorption layer and the heat source layer, wherein the heat conduction layer comprises an AlN layer.

6. A preparation method of a Ge photoelectric detector is characterized by comprising the following steps:

providing an SOI substrate;

carrying out photoetching to form a Si waveguide, wherein the Si waveguide comprises a bottom Si layer, an oxygen burying layer and a top Si layer which are sequentially superposed; forming a P-type doped contact region and an N-type doped contact region in the top Si layer respectively by ion implantation so as to form the P-type doped contact region, the I-type region and the N-type doped contact region which are sequentially arranged in the horizontal direction in the top Si layer;

forming a Ge absorption layer on the I-type region;

forming a passivation layer, wherein the passivation layer covers the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

forming a heat source layer, the heat source layer being located above the Ge absorbing layer;

and forming a metal electrode, wherein the metal electrode penetrates through the passivation layer and is in contact with the P-type doped contact region and the N-type doped contact region.

7. The method of fabricating a Ge photodetector as claimed in claim 6, characterized by: after forming the Ge absorbing layer and before forming the metal electrode, the method comprises the following steps:

forming a first passivation layer to cover the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

forming a heat source layer over the Ge absorbing layer;

forming a second passivation layer covering the heat source layer;

and forming a groove penetrating through the second passivation layer and the first passivation layer, and filling the groove to form a metal electrode in contact with the P-type doped contact region and the N-type doped contact region.

8. The method of fabricating a Ge photodetector as claimed in claim 7, characterized by: the range of the thickness D of the first passivation layer between the heat source layer and the Ge absorption layer comprises that D is more than or equal to 0.5 mu m, wherein the heat source layer comprises one or a combination of a TiN layer and a TaN layer; the first passivation layer comprises SiO₂A layer; the second passivation layer comprises SiO₂And (3) a layer.

9. The method of fabricating a Ge photodetector as claimed in claim 6, characterized by: after forming the Ge absorbing layer and before forming the metal electrode, the method comprises the following steps:

forming a first passivation layer to cover the P-type doped contact region, the N-type doped contact region and the Ge absorption layer, and flattening to expose the Ge absorption layer;

forming a heat conduction layer and a heat source layer above the Ge absorption layer in sequence;

forming a second passivation layer wrapping the heat source layer and the heat conduction layer;

and forming a groove penetrating through the second passivation layer and the first passivation layer, and filling the groove to form a metal electrode in contact with the P-type doped contact region and the N-type doped contact region.

10. The method of fabricating a Ge photodetector as claimed in claim 9, characterized by: the two opposite surfaces of the heat conduction layer are respectively contacted with the Ge absorption layer and the heat source layer, the thickness H of the heat conduction layer is more than or equal to 0.5 mu m, and the heat source layer comprises one or a combination of a TiN layer and a TaN layer; the thermally conductive layer includes an AlN layer; the first passivation layer comprises SiO₂A layer; the second passivation layer comprises SiO₂And (3) a layer.

Technical Field

The invention belongs to the technical field of photoelectrons, and relates to a Ge photoelectric detector and a preparation method thereof.

Background

The photoelectric detector has wide application in various fields of military and national economy. The silicon-based Ge photoelectric detector is compatible with a CMOS (complementary metal oxide semiconductor) process and convenient to integrate, and has wide application in the fields of optical communication, optical interconnection, optical sensing and the like. Compared with a surface incidence type photoelectric detector, the waveguide type photoelectric detector can avoid the problem that the speed and the quantum efficiency of the photoelectric detector are mutually restricted, can be integrated with a waveguide optical circuit, is easier to realize high speed and high responsivity, and is one of core devices for realizing high speed optical communication and optical interconnection chips. However, the absorption coefficient of the Ge material drops sharply at wavelengths longer than 1.55 μm, which makes the Ge photodetector unable to meet the application requirements of the L-band (long-wavelength band, wavelength range 1.56 μm to 1.63 μm) or even the U-band (ultra-long-wavelength band, wavelength range 1.63 μm to 1.68 μm).

In order to solve the problem that the Ge material has a low absorption coefficient at a long wavelength, in the prior art, a Sn material is usually introduced into the Ge material to extend the detection range of the Ge photodetector, however, the introduction of the Sn material increases the difficulty of the process, and at the same time, the introduction of the Sn material also reduces the thermal stability of the Ge material, thereby limiting the practical application.

Therefore, it is necessary to provide a novel Ge photodetector and a method for manufacturing the same.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a Ge photodetector and a method for manufacturing the same, which are used to solve the problem of low absorption coefficient of the Ge photodetector in the prior art under a long wavelength condition.

To achieve the above and other related objects, the present invention provides a Ge photodetector including:

the Si waveguide comprises a bottom Si layer, an oxygen burying layer and a top Si layer which are sequentially overlapped; the top Si layer comprises a P-type doped contact region, an I-type region and an N-type doped contact region which are sequentially arranged in the horizontal direction;

a Ge absorbing layer on the I-type region;

the passivation layer covers the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

a heat source layer located above the Ge absorbing layer;

and the metal electrode penetrates through the passivation layer and is in contact with the P-type doped contact region and the N-type doped contact region.

Optionally, the thickness D of the passivation layer between the heat source layer and the Ge absorption layer ranges from D ≧ 0.5 μm.

Optionally, the thermal source layer comprises one or a combination of a TiN layer and a TaN layer.

Optionally, a thermally conductive layer is further included between the Ge absorbing layer and the heat source layer, and the thermally conductive layer has a thermal conductivity greater than the passivation layer.

Optionally, opposite sides of the thermally conductive layer are in contact with the Ge absorption layer and the heat source layer, respectively, wherein the thermally conductive layer comprises an AlN layer.

The invention also provides a preparation method of the Ge photoelectric detector, which comprises the following steps:

providing an SOI substrate;

carrying out photoetching to form a Si waveguide, wherein the Si waveguide comprises a bottom Si layer, an oxygen burying layer and a top Si layer which are sequentially superposed;

forming a P-type doped contact region and an N-type doped contact region in the top Si layer respectively by ion implantation so as to form the P-type doped contact region, the I-type region and the N-type doped contact region which are sequentially arranged in the horizontal direction in the top Si layer;

forming a Ge absorption layer on the I-type region;

forming a passivation layer, wherein the passivation layer covers the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

forming a heat source layer, the heat source layer being located above the Ge absorbing layer;

and forming a metal electrode, wherein the metal electrode penetrates through the passivation layer and is in contact with the P-type doped contact region and the N-type doped contact region.

Optionally, after forming the Ge-absorbing layer and before forming the metal electrode, the method comprises the steps of:

forming a first passivation layer to cover the P-type doped contact region, the N-type doped contact region and the Ge absorption layer;

forming a heat source layer over the Ge absorbing layer;

forming a second passivation layer covering the heat source layer;

and forming a groove penetrating through the second passivation layer and the first passivation layer, and filling the groove to form a metal electrode in contact with the P-type doped contact region and the N-type doped contact region.

Optionally, the thickness D of the first passivation layer between the heat source layer and the Ge absorption layer ranges from D to 0.5 μm, wherein the heat source layer comprises one or a combination of a TiN layer and a TaN layer; the first passivation layer comprises SiO₂A layer; the second passivation layer comprises SiO₂And (3) a layer.

Optionally, after forming the Ge-absorbing layer and before forming the metal electrode, the method comprises the steps of:

forming a first passivation layer to cover the P-type doped contact region, the N-type doped contact region and the Ge absorption layer, and flattening to expose the Ge absorption layer;

forming a heat conduction layer and a heat source layer above the Ge absorption layer in sequence;

forming a second passivation layer wrapping the heat source layer and the heat conduction layer;

and forming a groove penetrating through the second passivation layer and the first passivation layer, and filling the groove to form a metal electrode in contact with the P-type doped contact region and the N-type doped contact region.

Optionally, two opposite surfaces of the heat conduction layer are respectively in contact with the Ge absorption layer and the heat source layer, the range of the thickness H of the heat conduction layer includes that H is greater than or equal to 0.5 μm, wherein the heat source layer includes one or a combination of a TiN layer and a TaN layer; the thermally conductive layer includes an AlN layer; the first passivation layer comprises SiO₂A layer; the second passivation layer comprises SiO₂And (3) a layer.

As described above, according to the Ge photodetector and the preparation method thereof of the present invention, the heat source layer with high resistance is used as the heat source to raise the temperature of the Ge absorption layer, so as to reduce the forbidden bandwidth of the Ge absorption layer, thereby enabling photons with energy lower than that of the forbidden bandwidth of the original Ge absorption layer to be absorbed, so as to increase the absorption coefficient of the Ge absorption layer, and extend the detection range of the Ge photodetector, so as to expand the application range; furthermore, the heat source generated by the heat source layer can be effectively transferred to the Ge absorption layer through the heat conduction layer with higher heat conductivity between the Ge absorption layer and the heat source layer, so that the responsivity of the Ge photoelectric detector is effectively adjusted; therefore, the invention can provide a method which has simple preparation process and can effectively improve the absorption coefficient of the Ge photoelectric detector under the long wavelength condition so as to expand the detection range and the application range of the Ge photoelectric detector.

Drawings

Fig. 1 shows a schematic process flow diagram for fabricating a Ge photodetector according to the present invention.

Fig. 2 to 5 are schematic structural views showing steps of fabricating a Ge photodetector according to the first embodiment.

Fig. 6 to 9 show schematic structural views of steps of manufacturing another Ge photodetector according to the second embodiment.

Description of the element reference numerals

110. 210 Si waveguide

111. 211 bottom Si layer

112. 212 buried oxide layer

113. 213 top Si layer

1131. 2131P type doped contact region

1132. 2132 type I region

1133. 2133N type doped contact region

120. 220 Ge absorbing layer

130. 230 first passivation layer

140. 240 heat source layer

150. 250 second passivation layer

160. 260 metal electrode

300 Heat conducting layer

D. H thickness

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 1 to 9. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.