Doped thermosensitive vanadium oxide film, preparation method thereof and infrared conversion functional structure

Abstract

The invention provides a temperature-sensitive vanadium oxide doped film, a preparation method thereof and an infrared conversion functional structure, and the preparation method of the temperature-sensitive vanadium oxide doped film comprises the following steps: growing a V2O5 layer, a free metal vanadium layer and a doped metal layer which are stacked to form a temperature-sensitive layer; and the thermosensitive layer is heated, so that V2O5, free metal vanadium and doped metal of the thermosensitive layer are diffused and fused, and the doped thermosensitive vanadium oxide film is obtained. The doped thermosensitive vanadium oxide thin film adopts a laminated structure form, and a doped metal element and a matrix vanadium element are fused in a high-temperature diffusion manner, so that the doped vanadium oxide thin film which is uniform in doping and lossless in surface is obtained, the doped thermosensitive vanadium oxide thin film can be obtained by utilizing a common semiconductor process, and complicated equipment and expensive materials are prevented from being used; and the resistance value of the thermosensitive film is regulated and controlled by utilizing the thicknesses of the V2O5 layer, the free metal vanadium layer and the doped metal layer, so that the resistance value requirement of a signal processing circuit is further matched, the regulation and control mode is simple, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of non-refrigerated infrared detectors, and in particular relates to a doped thermosensitive vanadium oxide film and a preparation method thereof. Background Art

[0002] Thermosensitive film is the core material of microbolometer, and its thermal properties directly affect the key performance indicators and imaging quality of microbolometer, so it is necessary to study and improve the thermal properties of thermosensitive materials. Among them, the use of doping engineering is a common and effective way to improve performance. By doping with appropriate elements, the temperature coefficient of resistance of thermistor film can be increased, and then a microbolometer with higher response rate and better photoelectric conversion efficiency can be prepared.

[0003] Currently, there are two main methods for preparing doped films. One is to cast the element to be doped together with vanadium into an alloy target by melting and casting, or to embed the element to be doped on a metal vanadium target and bombard the target in an oxygen atmosphere to obtain a doped vanadium oxide film. The other is to use high-energy ions to bombard the prepared vanadium oxide film and inject the element to be doped into the vanadium oxide film.

[0004] However, the existing methods for preparing doped films are costly and have unavoidable original process defects. Using a molten cast target to deposit a doped vanadium oxide film has the advantage of uniform distribution of doping elements to ensure uniformity, but the purchase cost of each target is very high, the cost of adjusting the doping concentration is too high, and the research and development cost remains high. Using a mosaic target to deposit a doped vanadium oxide film, due to the uneven distribution of solid-state source elements, it is difficult to obtain a thermosensitive film with uniform composition, which will cause different pixels to have different detection effects when responding to uniform radiation. At the same time, due to the different consumption rates of different vapor pressures of different elements, the surface of the target is prone to unevenness under long-term work, which greatly reduces the service life of the target and brings excessive material loss to mass production. When using high-energy ion bombardment, special ion implantation equipment needs to be purchased, but the ion implantation process is relatively complicated, and the doping dose is different at different depths. The high-energy ion bombardment itself is prone to damage the crystal structure of the thermosensitive film due to its excessive energy, forming a damaged layer on the film surface. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a doped thermosensitive vanadium oxide film, which can at least solve some of the defects existing in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The preparation method of the doped thermosensitive vanadium oxide film comprises the following steps:

[0008] Growing a stacked V2O5 layer, a free metal vanadium layer and a doped metal layer to form a thermal sensitive layer;

[0009] The thermosensitive layer is subjected to heat treatment to diffuse and fuse the V2O5, free metal vanadium and doped metal in the thermosensitive layer to obtain a doped thermosensitive vanadium oxide film.

[0010] Furthermore, the thermosensitive layer includes at least two V2O5 layers, and at least one doped metal layer and at least one free metal vanadium layer are disposed between every two adjacent V2O5 layers.

[0011] Furthermore, between every two adjacent V2O5 layers, a first doped metal layer, a free metal vanadium layer and a second doped metal layer are arranged from bottom to top.

[0012] Furthermore, the V2O5 layer is deposited by magnetron sputtering or ion beam deposition under oxygen-rich conditions.

[0013] Furthermore, the doped metal layer is grown by magnetron sputtering, electron beam evaporation, molecular beam epitaxy or atomic layer deposition.

[0014] Furthermore, the free metal vanadium layer is grown by magnetron sputtering or ion beam deposition under oxygen-free conditions.

[0015] Furthermore, the thickness of the V2O5 layer and the doped metal layer is adjusted to obtain a target doping ratio, and / or the thickness of the V2O5 layer and the free metal vanadium layer is adjusted to obtain a target valence state of vanadium ions.

[0016] Furthermore, the heat-sensitive layer is heated at a temperature of 250-300° C. for a time of 10-60 min.

[0017] In addition, the present invention also provides a doped thermosensitive vanadium oxide film, which is prepared by using the above-mentioned method for preparing the doped thermosensitive vanadium oxide film.

[0018] The present invention also provides an infrared conversion functional structure, comprising a substrate, an infrared absorption layer, a thermosensitive film layer, and a passivation protection layer arranged in sequence from bottom to top, wherein the thermosensitive film layer adopts the above-mentioned doped thermosensitive vanadium oxide film.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The doped thermosensitive vanadium oxide film provided by the present invention adopts a laminated structure, and then uses high-temperature diffusion to fuse the doped metal element with the matrix vanadium element, thereby obtaining a doped vanadium oxide film with uniform doping and intact surface. The preparation method is simple and can be achieved using common semiconductor processes, avoiding the use of complex equipment and expensive materials.

[0021] (2) The present invention adjusts the doping concentration by adjusting the thickness of the doped metal layer in the thermosensitive layer, and adjusts the valence state of the vanadium ions in the thermosensitive film by adjusting the thickness of the V2O5 layer and the free metal vanadium layer. The resistance value of the thermosensitive film is regulated by these two aspects to match the resistance value requirement of the signal processing circuit. This method of regulating the doped vanadium oxide thermosensitive film to obtain the target ratio is simple and low-cost.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the method for preparing the infrared conversion functional structure of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0028] Embodiment 1:

[0029] like Figure 1As shown, this embodiment provides a doped thermosensitive vanadium oxide film, and the preparation method of the doped thermosensitive vanadium oxide film includes the following process:

[0030] 1) growing a stacked V2O5 (vanadium pentoxide) layer, a free metal vanadium layer and a doped metal layer to form a thermosensitive layer. The doped metal X of the doped metal layer can be one of tungsten, molybdenum and chromium as the doping element of the thermosensitive vanadium oxide film.

[0031] 2) The thermosensitive layer is subjected to heat treatment to diffuse and fuse the V2O5, free metal vanadium and doped metal in the thermosensitive layer to obtain a doped thermosensitive vanadium oxide film.

[0032] Specifically, the temperature of the heat-sensitive layer is 250-300°C, and the time is 10-60 minutes. The deposited heat-sensitive layer is placed in this high-temperature environment. The thermal kinetic energy can make the V2O5, free metal vanadium, and doped metal in the heat-sensitive layer fully diffuse and fuse with each other, thereby obtaining a doped heat-sensitive vanadium oxide film with uniform composition.

[0033] In a detailed implementation method, the V2O5 layer, free metal vanadium layer and doped metal layer of the thermosensitive layer adopt a laminated structure, and the thermosensitive layer includes at least two V2O5 layers, and at least one doped metal layer and at least one free metal vanadium layer are arranged between each two adjacent V2O5 layers; preferably, a first doped metal layer, a free metal vanadium layer and a second doped metal layer are arranged from bottom to top between each two adjacent V2O5 layers. Among them, since the thermosensitive layer in the doped thermosensitive vanadium oxide film of the present invention requires an intermediate state of vanadium (i.e., VO2), the intermediate state VO2 is generally very difficult to obtain. In this embodiment, the V2O5 layer and the free metal vanadium layer are superimposed and obtained by mutual diffusion and fusion in a stable state, and the doped metal layer is added between the two layers (i.e., the V2O5 layer and the free metal vanadium layer) to ensure uniform diffusion. In this thermosensitive layer structure, the uniformity of the film layer composition can be increased by designing multiple V2O5 layers, but the working hours are increased accordingly, so the number of V2O5 layers in the thermosensitive layer can be reasonably designed according to actual needs.

[0034] Specifically, in this embodiment, two V2O5 layers are used as an example, and the thermosensitive layer includes a first V2O5 layer, a first doped metal layer, a free metal vanadium layer, a second doped metal layer, and a second V2O5 layer stacked from bottom to top. The process of growing the thermosensitive layer includes the following steps:

[0035] (a) Under oxygen-rich conditions, a first V2O5 layer is grown on the infrared absorption layer by magnetron sputtering or ion beam deposition; the oxygen-rich molecules in the V2O5 layer will fuse and diffuse with the subsequently deposited thin film layer during the heating process. In this embodiment, the oxygen-rich condition refers to an oxygen concentration of more than 25%.

[0036] (b) growing a first doped metal layer on the V2O5 layer by magnetron sputtering, electron beam evaporation, molecular beam epitaxy or atomic layer deposition.

[0037] (c) Under oxygen-free conditions, a free metal vanadium layer is grown on the first doped metal layer by magnetron sputtering or ion beam deposition; its oxygen-deficient state will be subsequently neutralized with oxygen-rich vanadium pentoxide to obtain a thermally sensitive film with a suitable valence state.

[0038] (d) growing a second doped metal layer on the free metal vanadium layer by magnetron sputtering, electron beam evaporation, molecular beam epitaxy or atomic layer deposition; preferably, the second doped metal layer is symmetrical with the first doped metal layer to ensure uniform distribution of the doping elements.

[0039] (e) Under oxygen-rich conditions, a second V2O5 layer is grown on the second doped metal layer by magnetron sputtering or ion beam deposition. The rich oxygen molecules in the V2O5 layer will fuse and diffuse with the previously deposited thin film layer during the subsequent heating process.

[0040] On the basis of obtaining the above-mentioned thermosensitive layer, the doping concentration can be adjusted by adjusting the thickness of the doped metal layer in the thermosensitive layer, and the valence state of the vanadium ions in the thermosensitive film can be adjusted by adjusting the thickness of the V2O5 layer and the free metal vanadium layer. Through these two aspects of adjustment, the resistance value of the thermosensitive film can be controlled to match the resistance requirement of the signal processing circuit.

[0041] Preferably, the first doped metal layer and the second doped metal layer are designed to have the same thickness, and the first V2O5 layer and the second V2O5 layer are designed to have the same thickness, so that the components of the thermosensitive layer are more evenly distributed during the heating and fusion process.

[0042] Therefore, the doped thermosensitive vanadium oxide film provided in the present embodiment adopts a laminated structure, and then uses high-temperature diffusion to fuse the doped metal elements with the matrix vanadium elements, thereby obtaining a doped vanadium oxide film with uniform doping and intact surface. The preparation method is simple and can be achieved using common semiconductor processes, avoiding the use of complex equipment and expensive materials; and the doping concentration is adjusted by adjusting the thickness of the doped metal layer in the thermosensitive layer, and the valence state of the vanadium ions in the thermosensitive film is adjusted by the thickness of the V2O5 layer and the free metal vanadium layer. The resistance value of the thermosensitive film is regulated by these two aspects to match the resistance value requirements of the signal processing circuit. This method of regulating the doped vanadium oxide thermosensitive film to obtain a target ratio is simple and low-cost.

[0043] Embodiment 2:

[0044] This embodiment provides an infrared conversion functional structure, including a substrate, an infrared absorption layer, a thermosensitive film layer, and a passivation protection layer arranged in sequence from bottom to top. The thermosensitive film layer adopts the doped thermosensitive vanadium oxide film in the above embodiment 1.

[0045] The preparation process of the infrared conversion functional structure is as follows Figure 1 As shown, the specific steps include:

[0046] S1. growing an infrared absorption layer on a substrate.

[0047] In some embodiments, the substrate is a Si microcircuit wafer; the infrared absorption layer is one of Si3N4, TiO2, Al2O3, CeO2, ZrO2, ZnO, SnO2, and MgO, preferably Si3N4 infrared absorption layer, which plays the role of passivation and absorption of infrared radiation into heat energy, so as to facilitate the diffusion and fusion of the doped metal elements of the subsequent thermal sensitive layer and the matrix vanadium element. The infrared absorption layer can be deposited by PECVD (plasma enhanced chemical vapor deposition) method.

[0048] Preferably, before the infrared absorption layer is grown, the substrate may be cleaned to remove possible contamination on the surface thereof and to avoid the introduction of impurities during the growth of the infrared absorption layer.

[0049] S2. Growing a thermosensitive layer on the infrared absorption layer. The thermosensitive layer adopts the thermosensitive layer in the above embodiment 1. Its growth process is the same as that in the above embodiment 1 and will not be repeated here.

[0050] S3, depositing a passivation protective layer on the thermosensitive layer; by setting the passivation protective layer, deformation and contamination of the surface of the thermosensitive layer during the subsequent heating treatment process are avoided, thereby preventing surface defects of the thermosensitive layer.

[0051] S4, heat-treating the structure of step S3, so that the V2O5, free metal vanadium and doped metal in the thermosensitive layer diffuse and fuse to form a thermosensitive film layer, thereby obtaining an infrared conversion functional structure.

[0052] As an optional implementation, the passivation protection layer includes a Si3N4 passivation layer and a SiO2 dielectric layer. The Si3N4 passivation layer is first deposited on the thermal sensitive layer, and then the SiO2 dielectric layer is deposited on the Si3N4 passivation layer. Both the Si3N4 passivation layer and the SiO2 dielectric layer can be deposited by, but not limited to, PECVD. The Si3N4 passivation layer can protect the surface of the top V2O5 layer of the thermal sensitive layer to prevent it from deforming during subsequent processes. At the same time, the Si3N4 passivation layer can also absorb infrared radiation and convert it into heat energy. The SiO2 dielectric layer can further protect the thermal sensitive layer from being intruded and contaminated by water vapor or other metal ions.

[0053] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a doped thermosensitive vanadium oxide film, characterized in that: The process includes the following: Growing a stacked V2O5 layer, a free metal vanadium layer and a doped metal layer to form a thermal sensitive layer; The thermosensitive layer is subjected to heat treatment to diffuse and fuse the V2O5, free metal vanadium and doped metal in the thermosensitive layer to obtain a doped thermosensitive vanadium oxide film.

2. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 1, characterized in that: The thermosensitive layer comprises at least two V2O5 layers, and at least one doped metal layer and at least one free metal vanadium layer are arranged between every two adjacent V2O5 layers.

3. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 2, characterized in that: Between every two adjacent V2O5 layers, a first doped metal layer, a free metal vanadium layer and a second doped metal layer are arranged from bottom to top.

4. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 1, characterized in that: The V2O5 layer is deposited by magnetron sputtering or ion beam deposition under oxygen-rich conditions.

5. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 1, characterized in that: The doped metal layer is grown by magnetron sputtering, electron beam evaporation, molecular beam epitaxy or atomic layer deposition.

6. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 1, characterized in that: The free metal vanadium layer is grown in an oxygen-free condition by magnetron sputtering or ion beam deposition.

7. The method for preparing a doped thermosensitive vanadium oxide thin film according to any one of claims 1 to 6, characterized in that: The thickness of the V2O5 layer and the doped metal layer is adjusted to obtain a target doping ratio, and / or the thickness of the V2O5 layer and the free metal vanadium layer is adjusted to obtain a target valence state of vanadium ions.

8. The method for preparing a doped thermosensitive vanadium oxide thin film according to claim 1, characterized in that: The temperature of the heat-sensitive layer heating treatment is 250-300° C. and the time is 10-60 minutes.

9. A doped thermosensitive vanadium oxide film, characterized in that: The method is described in any one of claims 1 to 8.

10. An infrared conversion functional structure, characterized in that: The invention comprises a substrate, an infrared absorption layer, a thermosensitive film layer and a passivation protection layer arranged in sequence from bottom to top, wherein the thermosensitive film layer adopts the doped thermosensitive vanadium oxide film as claimed in claim 9.

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