Low-return-loss detector chip

Abstract

The invention discloses a low return loss detector chip, and relates to the technical field of optical communication, the low return loss detector chip comprises a substrate, an epitaxial layer, a metal electrode and a reflection groove, the substrate is made of IV group, III-V group, II-VI group and other semiconductor materials, and the reflection groove is formed in the back substrate through corrosion, so that light incident to the substrate cannot return to a light source along an original path, and the reflection groove is formed in the back substrate. Therefore, the purpose of reducing the return loss of the detector is achieved, and the method is suitable for applications with high return loss requirements.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a low return loss detector chip. Background Art

[0002] In recent years, with the vigorous development of 5G networks, optical communication systems have been driven to develop in the direction of higher speed, larger volume, higher performance and lower cost. Among them, semiconductor photodetectors, as receivers of optical signals, are one of the indispensable devices in optical communication systems, and their performance and constraints affect the operation of the entire optical communication system. The main technical indicators for evaluating semiconductor photodetectors are: responsiveness, bandwidth, sensitivity, return loss, etc. In addition, there are factors such as whether the manufacturing process is mature, production cost, and whether it is easy to package and couple.

[0003] High-speed communication systems place higher demands on the performance of optical devices. An important technical indicator of high-speed photodetectors is low return loss. Therefore, in the application of higher-speed photodetectors, how to reduce return loss is an issue that needs to be considered. For existing photodetectors, the incident light is reflected by the substrate surface, and a large part of the reflected light will still return to the light source along the original path, causing a large return loss problem.

[0004] In order to overcome the above problems, the present invention proposes a photodetector chip with a reflection groove. After the incident light passes through the absorption layer, the unabsorbed light is reflected by the reflection surface of the substrate and then emitted from the side of the chip. Therefore, while ensuring a certain responsiveness and response rate, the return loss caused by the return of the light along the original path can be effectively reduced. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a low return loss detector chip, in which a reflective groove is etched on the back substrate to reduce the light returning along the original path, thereby reducing the return loss.

[0006] To achieve the above objectives, the present invention provides the following technical solutions: a low return loss detector chip, comprising a substrate, an epitaxial layer, a metal electrode, and a reflection groove, wherein the substrate is a semiconductor material of group IV, group III-V, group II-VI, etc.

[0007] Preferably, the epitaxial layer is grown on a substrate, and its structure is a detector active region.

[0008] Preferably, the metal electrodes are respectively made on the epitaxial layer or the substrate.

[0009] Preferably, the reflective groove is made on the back side of the substrate, and the angle formed with the substrate is 30°-60°.

[0010] Preferably, the back side is a corroded reflective groove.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention etches a reflective groove on the back substrate so that the light incident on the substrate cannot return to the light source along the original path, thereby achieving the purpose of reducing the return loss of the detector. The invention is suitable for applications with high requirements on return loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the chip structure of the present invention;

[0014] Figure 2 This is a schematic diagram of the epitaxial structure of the chip of the present invention;

[0015] Figure 3 This is a schematic diagram of the chip structure after dielectric deposition, hole opening, diffusion, P metallization and other processes of the present invention;

[0016] Figure 4 The schematic diagram of the chip structure after the processes of mesa etching, passivation, N metallization, sputtering and electroplating of the present invention;

[0017] Figure 5 This is a schematic diagram of the chip structure after thinning, etching and grooving processes of the present invention. DETAILED DESCRIPTION

[0018] See also Figure 1-5 The present invention provides a technical solution: a low return loss detector chip, including a substrate, an epitaxial layer, a metal electrode, and a reflection groove. The substrate is a semiconductor material of group IV, group III-V, group II-VI, etc. The epitaxial layer is grown on the substrate, and its structure is a detector active area. The metal electrodes are respectively made on the epitaxial layer or the substrate. The reflection groove is made on the back side of the substrate, and the angle formed with the substrate is 30°-60°. The back side is an etched reflection groove. By etching the reflection groove on the back substrate, the light incident on the substrate cannot return to the light source along the original path, thereby achieving the purpose of reducing the return loss of the detector. It is suitable for applications with high requirements for return loss.

[0019] Process flow: First, an epitaxial layer is grown on the substrate. The epitaxial layer is the active area of ​​the detector. The figure shows an example of an epitaxial layer structure. A diffusion mask is made through deposition, photolithography, etching and other processes to obtain the desired diffusion window. Then, diffusion is used for doping to form a P-type semiconductor. Then, a P electrode is made through an evaporation process. A mesa structure is formed through wet etching to expose the N-type semiconductor. Then, silicon nitride and silicon oxide are deposited as a passivation film to protect the semiconductor surface. Finally, the N electrode is made and the electrode is thickened through sputtering and electroplating processes. The front process is completed. After the back of the substrate is thinned and polished, a reflective groove is made on the back of the substrate through photolithography, etching and other processes.

Claims

1. A low return loss detector chip, comprising a substrate, an epitaxial layer, a metal electrode, and a reflective groove, characterized in that: The substrate is a semiconductor material of group IV, group III-V, group II-VI or the like.

2. The low return loss detector chip according to claim 1, characterized in that: The epitaxial layer is grown on a substrate, and its structure is a detector active region.

3. The low return loss detector chip according to claim 1, characterized in that: The metal electrodes are respectively made on the epitaxial layer or the substrate.

4. The low return loss detector chip according to claim 1, characterized in that: The reflection groove is made on the back side of the substrate, and the angle formed with the substrate is 30°-60°.

5. The low return loss detector chip according to claim 1, characterized in that: The back side is a corroded reflective groove.

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