Single photon avalanche diode detector and preparation method thereof

Abstract

The invention relates to a single photon avalanche diode detector and a preparation method thereof. The method comprises the following steps: after a deep groove between every two adjacent single-photon avalanche diode units of the single-photon avalanche diode unit array is etched, sequentially growing a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer and an adhesion layer on the surface of the deep groove; and filling the deep trench with a metal layer for surface planarization to obtain the single-photon avalanche diode detector. According to the invention, the ion concentration of metal ions diffused to the working area of the device can be effectively reduced, the possibility of wrong time and distance information feedback of pixels caused by ion pollution is improved, and the imaging quality and the production and manufacturing yield are further effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a single-photon avalanche diode detector and a preparation method thereof. BACKGROUND

[0002] With the rapid development of automatic driving technology, intelligent transportation system and high-precision imaging demand, optical detectors based on single-photon avalanche diode (SPAD) are increasingly important in providing accurate and real-time environmental perception. As an arrayed single-photon avalanche diode technology, it provides high photon detection efficiency and low noise characteristics, and has obvious advantages over traditional CIS detectors in dark light and extreme weather. SPAD devices have a wide range of application prospects.

[0003] In related technologies, the detection part of the laser radar chip is mainly composed of a single SPAD device (i.e. a single-photon avalanche diode unit). In order to improve the influence of electrical crosstalk on imaging quality, a deep trench isolation process is usually performed between adjacent pixels. This can effectively avoid the influence of secondary light emission on adjacent SPAD devices when the SPAD device is working. When filling the deep trench, materials such as silicon oxide or tungsten metal are usually selected. Metal tungsten filling is more effective in solving electrical crosstalk, but in the current production and manufacturing process of SPAD detectors, metal ions such as tungsten and nickel are easily introduced. These ions entering the SPAD pixel area will increase the dark current, causing the noise of the contaminated pixels to be larger when the SPAD detector pixel array is imaged, so that accurate time distance information cannot be provided, and the completeness of the area array information is reduced to a certain extent, resulting in low imaging quality and low production and manufacturing yield. SUMMARY

[0004] Therefore, it is necessary to provide a single-photon avalanche diode detector and a preparation method thereof in view of the above technical problems.

[0005] A preparation method of a single-photon avalanche diode detector, the method comprising: After etching a deep trench between each adjacent single-photon avalanche diode unit of the single-photon avalanche diode unit array, a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, and an adhesion layer are sequentially grown on the surface of the deep trench, and then a metal layer is filled in the deep trench to perform surface planarization, thereby obtaining a single-photon avalanche diode detector.

[0006] In one embodiment, the adhesion layer includes a first adhesion layer and a second adhesion layer. The first adhesion layer is located on the surface of the second buffer layer, and the second adhesion layer is located on the surface of the first adhesion layer.

[0007] In one of the embodiments, the material of the first adhesion layer is titanium.

[0008] In one of the embodiments, the material of the second adhesion layer is titanium nitride.

[0009] In one of the embodiments, the material of the tantalum oxide layer is tantalum pentoxide.

[0010] In one of the embodiments, the thickness of the tantalum oxide layer is 500Å ~ 600Å.

[0011] In one of the embodiments, the material of the first buffer layer is silicon oxide.

[0012] In one of the embodiments, the material of the second buffer layer is silicon oxide.

[0013] In one of the embodiments, the material of the metal layer is tungsten.

[0014] A single photon avalanche diode detector is prepared by the preparation method of the single photon avalanche diode detector as described above, and the single photon avalanche diode detector comprises a single photon avalanche diode unit array composed of a plurality of single photon avalanche diode units, each single photon avalanche diode unit is isolated by a deep trench, and the surface of the deep trench is sequentially grown with a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, an adhesion layer and a metal layer.

[0015] Compared with the prior art, the single photon avalanche diode detector has the following beneficial effects: By sequentially growing the first buffer layer, the hafnium oxide layer, the aluminum oxide layer, the tantalum oxide layer, the second buffer layer, the adhesion layer and the metal layer on the surface of the deep trench of the single photon avalanche diode detector, the ion concentration of metal ions diffusing to the working area of the device can be effectively reduced, the possibility of time and distance information of pixel feedback error caused by ion contamination can be improved, and the imaging quality and production yield can be effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a cross-sectional view of a deep trench of a single photon avalanche diode detector in one embodiment; Figure 2 FIG. 2 is a cross-sectional view of a single photon avalanche diode detector in one embodiment. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0018] In one embodiment, asFigure 1 As shown, a preparation method of a single photon avalanche diode detector is provided, comprising the following steps: After etching the deep trench between each adjacent single photon avalanche diode unit of the single photon avalanche diode unit array, a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, and an adhesion layer are sequentially grown on the surface of the deep trench, and then a metal layer is filled in the deep trench to perform surface planarization, thereby obtaining a single photon avalanche diode detector.

[0019] The single photon avalanche diode unit array can be a single photon avalanche diode unit array prepared by using an existing single photon avalanche diode detector preparation method. Figure 2 As shown in the cross-sectional view of the single photon avalanche diode detector, the avalanche region 2 of each single photon avalanche diode unit is surrounded by a deep trench 1, and the ion concentration of metal ions diffusing into the working area of the device is reduced by the deep trench 1 isolation technology.

[0020] The material of the hafnium oxide layer is hafnium oxide.

[0021] The material of the aluminum oxide layer is aluminum oxide.

[0022] It should be understood that when the first buffer layer, the hafnium oxide layer, the aluminum oxide layer, the tantalum oxide layer, the second buffer layer, and the adhesion layer are sequentially grown on the surface of the deep trench, and the metal layer is filled in the deep trench, the first buffer layer, the hafnium oxide layer, the aluminum oxide layer, the tantalum oxide layer, the second buffer layer, and the adhesion layer can be sequentially grown on the upper surface of the entire single photon avalanche diode unit array, and the metal layer can be sequentially formed in the deep trench.

[0023] It should be understood that the present application can better effectively reduce the ion concentration of metal ions diffusing into the working area of the device by selecting different thin film combinations to grow between the tungsten metal filled in the deep trench 1 and the wafer substrate, thereby improving the dark current increase caused by ion contamination, reducing the possibility of pixel feedback error of time and distance information, and effectively improving the imaging quality and production yield.

[0024] In one embodiment, the adhesion layer comprises a first adhesion layer and a second adhesion layer; the first adhesion layer is located on the surface of the second buffer layer, and the second adhesion layer is located on the surface of the first adhesion layer.

[0025] In one embodiment, the material of the first adhesion layer is titanium.

[0026] In one embodiment, the material of the second adhesion layer is titanium nitride.

[0027] In one embodiment, the material of the tantalum oxide layer is tantalum pentoxide.

[0028] In one embodiment, the thickness of the tantalum oxide layer is 500 Å to 600 Å.

[0029] In one embodiment, the material of the first buffer layer is silicon oxide.

[0030] In one embodiment, the material of the second buffer layer is silicon oxide.

[0031] In one embodiment, the metal layer is made of tungsten.

[0032] The process involves first growing a buffer layer of silicon oxide on the surface of the deep trench, followed by the growth of hafnium oxide and aluminum oxide. This helps to create a P-type distribution on the surface, reducing the impact of the trench surface on the device's working area. Then, a tantalum oxide layer of a certain thickness, typically between 500 Å and 600 Å, is grown to effectively physically isolate the diffusion of metal ions. Next, a buffer layer of silicon oxide is grown, followed by an adhesion layer (Ti and TiN). Finally, the trench is filled with tungsten metal for surface planarization, thus forming the deep trench isolation process. This effectively reduces the ion concentration of metal ions diffused into the device's working area, mitigating the possibility of increased dark current due to ion contamination, which could lead to incorrect timing and distance information in pixel feedback. This effectively improves imaging quality and manufacturing yield, while reducing product application and manufacturing costs.

[0033] The fabrication method of the single-photon avalanche diode detector in this application mainly improves the deep trench filling process between adjacent single-photon avalanche diode units in existing single-photon avalanche diode detectors. This effectively reduces the ion concentration of metal ions diffused into the working area of ​​the device, improves the possibility of increased dark current due to ion contamination, which could lead to incorrect time and distance information in pixel feedback, effectively improves imaging quality and manufacturing yield, and reduces product application and manufacturing costs.

[0034] In one embodiment, a single-photon avalanche diode detector is provided, which is prepared using the above-described method for preparing a single-photon avalanche diode detector. The single-photon avalanche diode detector includes a single-photon avalanche diode unit array composed of multiple single-photon avalanche diode units. Each single-photon avalanche diode unit is isolated from the others by a deep trench. The surface of the deep trench is sequentially grown with a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, an adhesion layer, and a metal layer.

[0035] Among them, the single-photon avalanche diode detector is an important photoelectric conversion device with wide applications in autonomous driving, intelligent transportation systems and high-precision imaging.

[0036] The first buffer layer, the hafnium oxide layer, the aluminum oxide layer, the tantalum oxide layer, the second buffer layer, the adhesion layer and the metal layer are sequentially grown on the deep groove surface of the single photon avalanche diode detector, so that the ion concentration of metal ions diffused to the working area of the device can be effectively reduced, the time and distance information of pixel feedback errors caused by ion contamination can be improved, and the imaging quality and the production yield can be effectively improved.

[0037] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

[0038] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for fabricating a single-photon avalanche diode detector, characterized in that, The method includes: After etching the deep trenches between each adjacent single-photon avalanche diode unit in the single-photon avalanche diode unit array, a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, and an adhesion layer are sequentially grown on the surface of the deep trenches. Then, the deep trenches are filled with metal layers to planarize the surface, thus obtaining a single-photon avalanche diode detector.

2. The method according to claim 1, characterized in that, The adhesive layer includes a first adhesive layer and a second adhesive layer; The first adhesive layer is located on the surface of the second buffer layer, and the second adhesive layer is located on the surface of the first adhesive layer.

3. The method according to claim 2, characterized in that, The material of the first adhesive layer is titanium.

4. The method according to claim 2, characterized in that, The material of the second adhesion layer is titanium nitride.

5. The method according to claim 1, characterized in that, The material of the tantalum oxide layer is tantalum pentoxide.

6. The method according to claim 5, characterized in that, The thickness of the tantalum oxide layer is 500 Å to 600 Å.

7. The method according to claim 1, characterized in that, The material of the first buffer layer is silicon dioxide.

8. The method according to claim 1, characterized in that, The material of the second buffer layer is silicon dioxide.

9. The method according to claim 1, characterized in that, The metal layer is made of tungsten.

10. A single-photon avalanche diode detector, characterized in that, The single-photon avalanche diode detector is prepared by the fabrication method of any one of claims 1-9. The single-photon avalanche diode detector includes a single-photon avalanche diode unit array composed of multiple single-photon avalanche diode units. Each single-photon avalanche diode unit is isolated from each other by a deep trench. The surface of the deep trench is sequentially grown with a first buffer layer, a hafnium oxide layer, an aluminum oxide layer, a tantalum oxide layer, a second buffer layer, an adhesion layer, and a metal layer.

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