Infrared absorption layer and infrared thermopile detector using the same, and manufacturing method

Abstract

The present invention discloses an infrared absorption layer and an infrared thermopile detector using the same, and a manufacturing method thereof, comprising a tungsten layer, a first silicon nitride layer, a first silicon dioxide layer, and a second silicon nitride layer, wherein the tungsten layer, the first silicon nitride layer, the first silicon dioxide layer, and the second silicon nitride layer are arranged in sequence. The present invention uses tungsten, silicon nitride, and silicon dioxide materials to construct the infrared absorption layer, introduces tungsten, a commonly used material in CMOS, as a component of the infrared absorption layer, effectively improves the infrared absorption efficiency of the silicon composite film structure, and reduces the thickness and quality of the infrared absorption layer at the same absorption efficiency. Tungsten is usually used as a through-hole connection material in the CMOS process, and can complete the preparation of the infrared absorption layer while completing the preparation of the integrated circuit in the CMOS process, thereby simplifying the preparation process of the infrared detector. Due to the improved infrared absorption efficiency, the infrared detector can be reduced in size under the same performance, thereby reducing the cost.

Description

Technical Field

[0001] The present invention belongs to the field of infrared absorption technology, and in particular relates to an infrared absorption layer and an infrared thermopile detector using the same, and a manufacturing method thereof. Background Art

[0002] Uncooled infrared detectors are small in size, low in cost, and highly stable. They have been widely used in home appliances, security, industry, and other fields. They are gradually becoming compatible with CMOS technology, and the device area is further reduced. In order to improve the performance of the device, it is very important to choose a suitable infrared absorption layer.

[0003] The materials or structures commonly used in the existing technology for the thermopile absorption layer include "black" substances (black silicon, black gold, carbon black, etc.) and silicides (silicon nitride, silicon carbide, etc.). They have high absorption rates for infrared radiation, but the process is complex and some are incompatible with CMOS process; silicon-based composite films (such as silicon dioxide-silicon nitride-silicon dioxide structure, etc.), in order to achieve high absorption rate, the material mass (or volume) is large, and the absorption rate is low when the material mass (or volume) is small; special hole array structure, by using designed hole array patterns to improve infrared absorption efficiency, but the array structure design is complex.

[0004] In order to improve the absorption capacity of the infrared absorption layer, infrared thermopiles usually make "black" materials (such as black silicon, black gold, carbon black, etc.), silicon-based composite films, and special geometric structure films on the device.

[0005] "Black" matter: Taking black silicon as an example, in the MEMS process, when dry etching is used to etch the material, "black" matter will appear. This "black" matter is a needle-like forest structure on the surface, and this special structure improves the absorption of infrared rays.

[0006] Silicon-based composite films improve the absorption of infrared rays by the overall structure by arranging materials with different refractive indices in order and thickness. However, when silicon-based composite films achieve high absorption rates, they require repeated stacking of several layers of materials, which increases the overall mass (or volume) while improving the infrared absorption efficiency, and increases the complexity of the process. Summary of the invention

[0007] In view of this, the main purpose of the present invention is to provide an infrared absorption layer and an infrared thermopile detector using the same, and a manufacturing method.

[0008] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] Embodiment 1 of the present invention provides an infrared absorption layer, including a tungsten layer, a first silicon nitride layer, a first silicon dioxide layer and a second silicon nitride layer, wherein the tungsten layer, the first silicon nitride layer, the first silicon dioxide layer and the second silicon nitride layer are sequentially prepared by thin film processes such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering.

[0010] Preferably in the present invention, the thickness of the tungsten layer is at least 1 nm.

[0011] Preferably, in the present invention, the thickness of the first silicon nitride layer is 0-5000 nm.

[0012] Preferably in the present invention, the thickness of the first silicon dioxide layer is 500nm-1500nm.

[0013] Preferably in the present invention, the thickness of the second silicon nitride layer is 200nm-5000nm.

[0014] Embodiment 2 of the present invention provides an infrared thermopile detector, comprising the above-mentioned infrared absorption layer, silicon substrate layer, silicon oxide layer, first polysilicon layer, second silicon dioxide layer, second polysilicon layer, third silicon dioxide layer and fourth silicon dioxide layer;

[0015] After the silicon substrate layer is polished, a silicon oxide layer is thermally grown on its surface;

[0016] Depositing a first polysilicon layer on the surface of the silicon oxide layer by LPCVD;

[0017] Depositing a second silicon dioxide layer on the surface of the first polysilicon layer by LPCVD;

[0018] Depositing a second polysilicon layer on the surface of the second silicon dioxide layer by LPCVD;

[0019] The first polysilicon layer and the second polysilicon layer are formed into n-type or p-type polysilicon by ion implantation, and the first polysilicon layer and the second polysilicon layer are formed into different types of polysilicon by ion implantation and have opposite Seebeck coefficients;

[0020] Depositing a third silicon dioxide layer on the surface of the second polysilicon layer by LPCVD;

[0021] Depositing a fourth silicon dioxide layer on the surface of the third silicon dioxide layer by LPCVD;

[0022] An infrared absorption layer is disposed on the surface of the fourth silicon dioxide layer.

[0023] Preferably, in the present invention, lead holes are photoetched on the second silicon dioxide layer and the third silicon dioxide layer, and the lead holes are filled with tungsten. Aluminum is deposited between the third silicon dioxide layer and the fourth silicon dioxide layer by magnetron sputtering to connect the first polysilicon layer and the second polysilicon layer.

[0024] Embodiment 3 of the present invention provides a method for preparing the above-mentioned infrared absorption layer, and the preparation method comprises the following steps:

[0025] S1. Depositing a layer of tungsten on an infrared detector covered with insulating material by using a thin film process such as electron beam evaporation, thermal evaporation or magnetron sputtering to obtain a tungsten layer;

[0026] S2, depositing a layer of silicon nitride on the surface of the tungsten layer using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0027] S3, depositing a layer of silicon dioxide on the surface of the first silicon nitride layer by using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0028] S4, depositing a layer of silicon nitride on the surface of the first silicon dioxide layer by using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0029] S5. Etch the silicon nitride and silicon oxide obtained in steps S2 to S4 to obtain a first silicon nitride layer, a first silicon dioxide layer, and a second silicon nitride layer.

[0030] Compared with the prior art, the present invention uses tungsten, silicon nitride, and silicon dioxide materials to construct an infrared absorption layer, and introduces tungsten, a commonly used material in CMOS, as a component of the infrared absorption layer, which effectively improves the infrared absorption efficiency of the silicon composite film structure, while reducing the thickness and quality of the infrared absorption layer under the same absorption efficiency. Tungsten is usually used as a through-hole connection material in the CMOS process. When the preparation of the integrated circuit is completed in the CMOS process, the infrared absorption layer can be completed at the same time, which simplifies the preparation process of the infrared detector (MEMS)-ASIC (CMOS). Since the infrared absorption efficiency is improved, the infrared detector can be reduced in size with the same performance, thereby reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of an infrared absorption layer provided in Example 1 of the present invention;

[0032] Figure 2 is the broken line of the infrared absorption efficiency of the infrared absorption layer provided in Example 1 of the present invention for the 5μm to 20μm band infrared rays Figure 1 ;

[0033] Figure 3is the broken line of the infrared absorption efficiency of the infrared absorption layer provided in Example 1 of the present invention for the 5μm to 20μm band infrared rays Figure 2 ;

[0034] Figure 4 The structure preparation of the infrared thermopile detector provided in Example 2 of the present invention Figure 1 ;

[0035] Figure 5 The structure preparation of the infrared thermopile detector provided in Example 2 of the present invention Figure 2 ;

[0036] Figure 6 The structure preparation of the infrared thermopile detector provided in Example 2 of the present invention Figure 3 . DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the description of the present invention, it should be clarified that terms such as "vertical", "lateral", "longitudinal", "front", "rear", "left", "right", "up", "down", and "horizontal" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are merely for the convenience of describing the present invention. They do not mean that the devices or elements referred to must have a specific direction or position, and therefore cannot be understood as limitations on the present invention.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Embodiment 1:

[0041] like Figure 1 As shown, embodiment 1 of the present invention provides an infrared absorption layer, including a tungsten layer 11, a first silicon nitride layer 12, a first silicon dioxide layer 13 and a second silicon nitride layer 14, wherein the tungsten layer 11, the first silicon nitride layer 12, the first silicon dioxide layer 13 and the second silicon nitride layer 14 are prepared by thin film processes such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering.

[0042] like Figure 2As shown, the thickness of the tungsten layer 11 is at least 1 nm.

[0043] like Figure 2 As shown, the thickness of the first silicon nitride layer 12 is 0-5000 nm.

[0044] like Figure 2 As shown, the thickness of the first silicon dioxide layer 13 is 500nm-1500nm.

[0045] like Figure 2 As shown, the thickness of the second silicon nitride layer 14 is 200 nm-5000 nm.

[0046] In the above-mentioned first embodiment, the first silicon nitride layer 12 can be omitted in the infrared absorption layer. Relatively speaking, when the first silicon nitride layer 12 is omitted, the infrared absorption efficiency is slightly reduced compared with when the first silicon nitride layer 12 is used.

[0047] When the tungsten layer 11 is set to 50nm, the first silicon nitride layer 12 is set to 100nm, the first silicon dioxide layer 13 is set to 800nm, and the second silicon nitride layer 14 is set to 500nm, the absorption efficiency of infrared light in the wavelength range of 5000nm to 20000nm is as follows: Figure 2 shown.

[0048] When the first silicon nitride layer 12 is not used, the tungsten layer 11 is 50 nm, the first silicon dioxide layer 13 is 800 nm, and the second silicon nitride layer 14 is 500 nm, the absorption efficiency of infrared light in the wavelength range of 5000 nm to 20000 nm is as follows: Figure 3 shown.

[0049] Embodiment 2:

[0050] Embodiment 2 of the present invention provides an infrared thermopile detector, comprising the above-mentioned infrared absorption layer, silicon substrate layer 61, silicon oxide layer 62, first polysilicon layer 63, second silicon dioxide layer 64, second polysilicon layer 65, third silicon dioxide layer 66 and fourth silicon dioxide layer 69;

[0051] After the silicon substrate layer 61 is polished, a silicon oxide layer 62 is thermally grown on its surface as a supporting film;

[0052] A first polysilicon layer 63 is deposited on the surface of the silicon oxide layer 62 supporting film by LPCVD;

[0053] A second silicon dioxide layer 64 is deposited on the surface of the first polysilicon layer 63 by LPCVD, boron is ion-implanted, and the polysilicon is photoetched to form a lower thermocouple strip;

[0054] A second polysilicon layer 65 is deposited on the surface of the second silicon dioxide layer 64 by LPCVD to serve as a dielectric layer between the first polysilicon layers 63;

[0055] A third silicon dioxide layer 66 is deposited on the surface of the second polysilicon layer 65 by LPCVD, phosphorus is ion-implanted, and the polysilicon is photoetched to form an upper thermocouple strip;

[0056] The first polysilicon layer 63 and the second polysilicon layer 65 are formed into n-type and p-type polysilicon by ion implantation. The first polysilicon layer and the second polysilicon layer are formed into different types of polysilicon by ion implantation and have opposite Seebeck coefficients.

[0057] A fourth silicon dioxide layer 69 is deposited on the surface of the third silicon dioxide layer 66 by LPCVD, lead holes are photoetched on the second silicon dioxide layer 64 and the third silicon dioxide layer 66, and the lead holes are filled with tungsten 67, and aluminum 68 is deposited between the third silicon dioxide layer 66 and the fourth silicon dioxide layer 69 by magnetron sputtering to connect the first polysilicon layer 63 and the second polysilicon layer 65;

[0058] An infrared absorption layer is disposed on the surface of the fourth silicon dioxide layer 69 , which serves as a dielectric layer between the lead and the infrared absorption layer.

[0059] A layer of tungsten is deposited on the surface of the fourth silicon dioxide layer 69 by using a thin film process such as electron beam evaporation, thermal evaporation or magnetron sputtering to obtain a tungsten layer 610 .

[0060] The first silicon nitride layer 611, the first silicon dioxide layer 612 and the second silicon nitride layer 613 are sequentially deposited by PECVD and photoetched to retain the required position for absorbing infrared light and form an infrared absorption structure with the tungsten layer 610. The first silicon nitride layer 611, the first silicon dioxide layer 612 and the second silicon nitride layer 613 at the support beam position and other positions can be selected to be retained as a passivation layer.

[0061] The cavity is opened by photolithography etching, and the silicon dioxide formed in the above step is etched. Finally, TMAH is used to perform cavity etching on the silicon substrate to form a cavity 614 on the silicon substrate 61 .

[0062] Among the above, LPCVD, magnetron sputtering and other processes can also be used to deposit silicon nitride, silicon dioxide, and silicon nitride.

[0063] In the above, the second silicon dioxide layer 64 and the second polysilicon layer 65 can be eliminated, and the thermopile device can be composed of a single polysilicon and aluminum.

[0064] Embodiment three:

[0065] Embodiment 3 of the present invention provides a method for preparing the above-mentioned infrared absorption layer, and the preparation method comprises the following steps:

[0066] S1, depositing a layer of tungsten on an infrared detector covered with an insulating material by using a thin film process such as electron beam evaporation, thermal evaporation or magnetron sputtering to obtain a tungsten layer 11;

[0067] S2, depositing a layer of silicon nitride on the surface of the tungsten layer using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0068] S3, depositing a layer of silicon dioxide on the surface of the first silicon nitride layer 12 using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0069] S4, depositing a layer of silicon nitride on the surface of the first silicon dioxide layer 13 using a thin film process such as plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering;

[0070] S5 , etching the silicon nitride and silicon oxide obtained in steps S2 to S4 to obtain a first silicon nitride layer 12 , a first silicon dioxide layer 13 , and a second silicon nitride layer 14 .

[0071] The present invention uses tungsten, silicon nitride, and silicon dioxide materials to form an infrared absorption layer, and introduces tungsten, a commonly used material in CMOS, as a component of the infrared absorption layer, which effectively improves the infrared absorption efficiency of the silicon composite film structure, while reducing the thickness and quality of the infrared absorption layer under the same absorption efficiency. Tungsten is usually used as a through-hole connection material in the CMOS process, and the infrared absorption layer can be manufactured while the integrated circuit is manufactured in the CMOS process, thereby simplifying the preparation process of the infrared detector (MEMS)-ASIC (CMOS). Due to the improved infrared absorption efficiency, the infrared detector can be reduced in size under the same performance, thereby reducing the cost.

[0072] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An infrared thermopile detector, characterized in that: It includes an infrared absorption layer, a silicon substrate layer, a silicon oxide layer, a first polysilicon layer, a second silicon dioxide layer, a second polysilicon layer, a third silicon dioxide layer and a fourth silicon dioxide layer; An infrared absorption layer, comprising a tungsten layer, a first silicon nitride layer, a first silicon dioxide layer and a second silicon nitride layer, wherein the tungsten layer, the first silicon nitride layer, the first silicon dioxide layer and the second silicon nitride layer are prepared by plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering thin film process; The thickness of the tungsten layer is at least 1 nm; The thickness of the first silicon nitride layer is 0-5000nm; The thickness of the first silicon dioxide layer is 500nm-1500nm; The thickness of the second silicon nitride layer is 200nm-5000nm; After the silicon substrate layer is polished, a silicon oxide layer is thermally grown on its surface; Depositing a first polysilicon layer on the surface of the silicon oxide layer by LPCVD; Depositing a second silicon dioxide layer on the surface of the first polysilicon layer by LPCVD; A second polysilicon layer is deposited on the surface of the second silicon dioxide layer by LPCVD; it serves as a dielectric layer between the first polysilicon layers; Depositing a third silicon dioxide layer on the surface of the second polysilicon layer by LPCVD; Depositing a fourth silicon dioxide layer on the surface of the third silicon dioxide layer by LPCVD; An infrared absorption layer is provided on the surface of the fourth silicon dioxide layer; The first polysilicon layer and the second polysilicon layer are formed into n-type or p-type polysilicon by ion implantation. The first polysilicon layer and the second polysilicon layer are formed into different types of polysilicon by ion implantation and have opposite Seebeck coefficients.

2. The infrared thermopile detector according to claim 1, characterized in that: Lead holes are photoetched on the second silicon dioxide layer and the third silicon dioxide layer, and the lead holes are filled with tungsten. Aluminum is deposited between the third silicon dioxide layer and the fourth silicon dioxide layer by magnetron sputtering to connect the first polysilicon layer and the second polysilicon layer.

3. A method for preparing an infrared absorption layer in an infrared thermopile detector as claimed in claim 1, characterized in that: The preparation method comprises the following steps: S1. Depositing a layer of tungsten on an infrared detector covered with an insulating material by electron beam evaporation, thermal evaporation or magnetron sputtering thin film process to obtain a tungsten layer; S2, depositing a layer of silicon nitride on the surface of the tungsten layer by using plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering thin film process; S3, depositing a layer of silicon dioxide on the surface of the first silicon nitride layer using plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering thin film process; S4, depositing a layer of silicon nitride on the surface of the first silicon dioxide layer by using plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition or magnetron sputtering thin film process; S5. Etch the silicon nitride and silicon oxide obtained in steps S2 to S4 to obtain a first silicon nitride layer, a first silicon dioxide layer, and a second silicon nitride layer.

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