Uncooled infrared detector and preparation method thereof

Abstract

The invention discloses an uncooled infrared detector and a preparation method thereof, and belongs to the technical field of MEMS devices. According to the invention, the conductive layer with the step covering capability higher than that of the titanium layer is used as the anchor post, when the hard mask is used for forming the contact hole, the surface of the contact hole with the undercut structure can be better covered, the connection position of the sacrificial layer and the hard mask cannot be disconnected, good electric connection can be ensured, and the contact hole forming efficiency is improved. Therefore, the stability and reliability of the anchor post can be improved; meanwhile, the conducting layer serves as a conducting layer and a supporting layer, a traditional anchor column formed by stacking the supporting layer, a titanium layer and a protective layer is replaced, the problems that the titanium layer serves as the conducting layer of the traditional anchor column, the step covering capacity in the contact hole is poor, and media are needed for protection and supporting are solved, and the technological process is simplified.

Description

Technical Field

[0001] The present application relates to the technical field of MEMS devices, and in particular to an uncooled infrared detector and a method for preparing the uncooled infrared detector. Background Art

[0002] The processing of uncooled infrared detectors (Focal Plane Array, FPA) belongs to the field of micro-electromechanical systems (MEMS), which is a high-tech field based on microelectronics and micromachining technology. In the manufacturing process of FPA, complex three-dimensional structures are involved, and sacrificial layers are required to make micro-bridge structures. In the process of making micro-bridge structures, anchor columns are also required for support.

[0003] The commonly used process route for making anchor pillars is to first etch support holes on the sacrificial layer without using a hard mask, and then further etch contact holes in the support holes, and then deposit a conductive layer in the contact holes, and finally grow a thermosensitive film layer and other film layers. With the development of technical routes and technological innovation, the pixel size of uncooled infrared detectors has grown from 50μm to 8μm. However, according to the existing process route, the anchor pillar cannot be reduced in proportion to the pixel size. An existing improvement scheme is to use a hard mask to etch support holes on the sacrificial layer, but this method will form an undercut, and the conductive layer is easily disconnected in the undercut structure, resulting in reduced stability and reliability of the anchor pillar. Summary of the invention

[0004] The purpose of the present application is to provide an uncooled infrared detector and a method for preparing an uncooled infrared detector, thereby improving the stability and reliability of the anchor column.

[0005] To achieve the above-mentioned purpose, the present application provides an uncooled infrared detector, comprising: a readout circuit wafer, an electrode, an anchor column and a MEMS device; the anchor column comprises a first conductive layer; the MEMS device comprises a thermosensitive film and a second conductive layer; the readout circuit on the surface of the readout circuit wafer, the electrode, the first conductive layer, the second conductive layer and the thermosensitive film are electrically connected in sequence; the step coverage capability of the first conductive layer is stronger than the step coverage capability of the titanium layer.

[0006] Optionally, the anchor column further includes a first dielectric film; the first dielectric film covers a surface of the first conductive layer that is away from the electrode.

[0007] Optionally, the MEMS device further includes a first absorption layer; the first absorption layer covers the thermosensitive film.

[0008] Optionally, the first absorption layer and the first conductive layer are made of the same material; the first conductive layer has a stronger ability to absorb infrared light than the titanium layer.

[0009] Optionally, the first absorption layer and the first conductive layer are formed by the same preparation process.

[0010] Optionally, the MEMS device further includes a second dielectric film, a third dielectric film and a fourth dielectric film;

[0011] The second dielectric film is connected to the side wall of the first conductive layer away from the electrode; the thermosensitive film is located on the surface of the second dielectric film;

[0012] The third dielectric film covers the thermosensitive film and the second dielectric film; the second conductive layer covers the third dielectric film, and one end of the second conductive layer penetrates through the third dielectric film and is electrically connected to the thermosensitive film;

[0013] The fourth dielectric film covers the second conductive layer.

[0014] Optionally, the stacked second dielectric film, the third dielectric film, the second conductive layer and the fourth dielectric film are used as a hard mask to form the first conductive layer.

[0015] Optionally, the MEMS device also includes a fifth dielectric film; the fifth dielectric film covers the thermosensitive film; the third dielectric film covers the fifth dielectric film and the second dielectric film; one end of the second conductive layer sequentially penetrates the third dielectric film and the fifth dielectric film and is electrically connected to the thermosensitive film.

[0016] Optionally, the second dielectric film, the third dielectric film, the second conductive layer and the fourth dielectric film located between the first conductive layer and the thermosensitive film form a bent microbridge structure.

[0017] To achieve the above objectives, the present application also provides a method for preparing an uncooled infrared detector, comprising:

[0018] A sacrificial layer is provided on the surface of a readout circuit wafer; the readout circuit and the electrode on the surface of the readout circuit wafer are electrically connected;

[0019] Prepare a MEMS device; the MEMS device includes a thermosensitive film and a second conductive layer;

[0020] Etching the sacrificial layer along a first direction to expose the electrode and form a contact hole;

[0021] A first conductive layer is provided on the inner surface of the contact hole to form an anchor column; the step coverage capability of the first conductive layer is stronger than that of the titanium layer; the electrode, the first conductive layer, the second conductive layer and the thermosensitive film are electrically connected in sequence;

[0022] The sacrificial layer is removed to obtain the uncooled infrared detector.

[0023] Optionally, the step of providing a first conductive layer on the inner surface of the contact hole to form an anchor column includes:

[0024] The first conductive layer is disposed on the surface of the readout circuit wafer having the contact hole formed thereon; the first conductive layer has a stronger ability to absorb infrared light than the titanium layer;

[0025] The first conductive layer is patterned to retain the first conductive layer covering the inner surface of the contact hole to form the anchor column, and the first conductive layer covering the thermosensitive film is retained to form a first absorption layer.

[0026] Optionally, the preparing of the MEMS device includes:

[0027] On a surface of the sacrificial layer facing away from the readout circuit wafer, a second dielectric film, the thermosensitive film, a third dielectric film, the second conductive layer and a fourth dielectric film are sequentially arranged along the first direction;

[0028] The second dielectric film is connected to the side wall of the first conductive layer away from the electrode; the thermosensitive film is located on the surface of the second dielectric film; the third dielectric film covers the thermosensitive film and the second dielectric film; the second conductive layer covers the third dielectric film, and one end penetrates the third dielectric film and is electrically connected to the thermosensitive film; the fourth dielectric film covers the second conductive layer.

[0029] Optionally, etching the sacrificial layer along the first direction to expose the electrode and form a contact hole includes:

[0030] The second dielectric film, the third dielectric film, the second conductive layer and the fourth dielectric film that are stacked are used as a hard mask, and the sacrificial layer is etched along the first direction using the hard mask to expose the electrode, thereby forming the contact hole.

[0031] Obviously, the non-cooled infrared detector provided by the present application uses a conductive layer with a stronger step coverage ability than that of the titanium layer as an anchor column. When a contact hole is formed using a hard mask, it can better cover the surface of the contact hole in the contact hole with an undercut structure, and will not be disconnected at the connection position between the sacrificial layer and the hard mask, which can ensure a good electrical connection, thereby improving the stability and reliability of the anchor column; at the same time, the conductive layer serves as both a conductive layer and a supporting layer, replacing the traditional anchor column formed by stacking a supporting layer, a titanium layer and a protective layer, solving the problem that the traditional anchor column uses a titanium layer as a conductive layer and has poor step coverage in the contact hole, and requires a medium for protection and support, and simplifies the process flow. The present application provides a method for preparing a non-cooled infrared detector, which can prepare the above-mentioned non-cooled infrared detector and also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0033] Figure 1 A flow chart of a method for preparing an uncooled infrared detector provided in an embodiment of the present application;

[0034] Figures 2 to 12 A schematic flow chart of a method for preparing an uncooled infrared detector provided in an embodiment of the present application.

[0035] The following are the descriptions of the reference numerals:

[0036] 1-readout circuit wafer; 2-electrode; 3-sixth dielectric film; 4-sacrificial layer; 5-second dielectric film; 6-thermosensitive film; 7-fifth dielectric film; 8-third dielectric film; 9-second conductive layer; 10-fourth dielectric film; 11-first absorption layer; 12-anchor column first conductive layer; 13-first dielectric film; 14-microbridge structure. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] The existing uncooled infrared detectors are mainly prepared by the following method: etching a support hole on the sacrificial layer without using a hard mask, the support hole is a straight hole (anisotropic etching) or an inclined hole with a certain inclination (such as 50~70°); then depositing a support layer in the support hole, and photolithography to open the support layer at the bottom of the support hole to form a contact hole; then depositing a conductive layer and a protective layer in the contact hole to form an anchor column with a stacked support layer, a titanium layer and a protective layer, and then completing a series of processes such as the subsequent thermal film layer and other film layers. The problems with this method are as follows:

[0039] 1) After the sacrificial layer is etched, the size of the anchor column is difficult to control and cannot meet the miniaturization requirements;

[0040] 2) Using PVD (Physical Vapor Deposition) to deposit a titanium layer as a conductive layer has poor filling capacity at the bottom and sidewalls of the contact hole, which can easily lead to product failure. In addition, the conductive layer needs a dielectric to protect and support it in the through hole, so before preparing the conductive layer, it is necessary to open a hole at the bottom of the dielectric at the bottom of the support hole to ensure that the conductive layer can contact the electrode at the bottom. The entire process is cumbersome and complicated.

[0041] 3) The process flow is to make through holes first and then deposit the thermal-sensitive film. The thermal-sensitive film in the through holes is difficult to etch, resulting in product failure.

[0042] As the pixel size of uncooled infrared detectors continues to shrink, the size of the anchor column is required to be further reduced. However, according to the existing process route, the anchor column cannot be reduced in proportion to the pixel size. An existing improvement scheme is to use a hard mask to etch support holes on the sacrificial layer, but this method will form an undercut, and the conductive layer is easily disconnected in the undercut structure, resulting in reduced stability and reliability of the anchor column. There is also a preparation method in the prior art that uses a hard mask to etch support holes on the sacrificial layer, and then fills the hole with metal tungsten to form a solid anchor column. The problems with this method are as follows:

[0043] 1) An undercut is formed between the sacrificial layer and the hard mask, and the metal tungsten cannot be completely filled. In addition, the roughness of the metal tungsten is large, which may cause other film layers to be etched through or tungsten residue to remain during the subsequent process, resulting in product failure;

[0044] 2) The deposition temperature of metal tungsten is high, which can easily lead to failure of the thermal sensitive film;

[0045] 3) Solid anchor columns have large heat capacity, which reduces product performance.

[0046] Therefore, the present application provides an uncooled infrared detector, which optimizes and innovates the key supporting structure anchor column of the uncooled infrared detector, and can be applicable to the structure and manufacturing process of the pixel size of 12μm and below, and reduce the difficulty of process manufacturing, to ensure that when the pixel size is reduced, the anchor column structure is reduced and still maintains the original stability and reliability, and improves and solves the new problems introduced by the size reduction.

[0047] Please refer to Figures 2 to 12 An uncooled infrared detector provided in an embodiment of the present application may include: a readout circuit wafer 1, an electrode 2, an anchor column and a MEMS device; the anchor column includes a first conductive layer 12; the MEMS device includes a thermosensitive film 6 and a second conductive layer 9; the readout circuit, the electrode 2, the first conductive layer 12, the second conductive layer 9 and the thermosensitive film 6 on the surface of the readout circuit wafer 1 are electrically connected in sequence; the step coverage capability of the first conductive layer 12 is stronger than that of the titanium layer.

[0048] It should be noted that the first direction in this embodiment represents the thickness direction of the readout circuit wafer 1, the second direction represents the direction parallel to the surface of the readout circuit wafer 1, and the third direction is parallel to the surface of the readout circuit wafer 1 and perpendicular to the second direction.

[0049] This embodiment does not limit the specific type of the electrode 2, and the electrode 2 can be, but is not limited to, a metal electrode 2. Further, the uncooled infrared detector in this embodiment may also include: a sixth dielectric film 3; the electrode 2 is located on the surface of the readout circuit wafer 1; and the sixth dielectric film 3 covers the readout circuit wafer 1 and the electrode 2. This embodiment does not limit the specific type of the sixth dielectric film 3, and it can be any insulating dielectric film.

[0050] The present embodiment does not limit the specific type of the first conductive layer 12 , and the first conductive layer 12 may be any conductive layer having a step coverage capability greater than that of a titanium layer. For example, the first conductive layer 12 may be a titanium nitride layer.

[0051] This embodiment does not limit the specific type of the thermosensitive film 6 , and the thermosensitive film 6 may be, but is not limited to, a vanadium oxide layer or an amorphous silicon layer.

[0052] This embodiment does not limit the specific type of the second conductive layer 9. The second conductive layer 9 may be, but is not limited to, a metal layer; the metal layer may be, but is not limited to, a titanium layer, an aluminum layer, a titanium-tungsten layer or a second composite film layer; the second composite film layer may be, but is not limited to, a stacked structure formed by a titanium layer and a titanium nitride layer arranged in sequence along a first direction.

[0053] Furthermore, in this embodiment, the anchor column may also include a first dielectric film 13; the first dielectric film 13 covers the surface of the first conductive layer 12 facing away from the electrode 2. It should be noted that the first dielectric film 13 is provided to prevent the first conductive layer 12 from contacting the air on the one hand, and to provide auxiliary support for the first conductive layer 12 on the other hand, thereby further improving the stability and reliability of the anchor column. This embodiment does not limit the specific type of the first dielectric film 13, and the first dielectric film 13 may be, but is not limited to, a silicon nitride layer.

[0054] Furthermore, in this embodiment, the MEMS device may further include a first absorption layer 11; the first absorption layer 11 covers the thermosensitive film 6. It should be noted that the provision of the first absorption layer 11 can increase infrared absorption. In this embodiment, a second absorption layer may also be provided on the surface of the first absorption layer 11. It should be noted that the provision of the second absorption layer can further increase infrared absorption.

[0055] The present embodiment does not limit the specific type of the first absorption layer 11. For example, the first absorption layer 11 can be made of the same material as the first conductive layer 12. The first conductive layer 12 has a stronger ability to absorb infrared light than the titanium layer. In addition, the first absorption layer 11 can also be made of different materials than the first conductive layer 12 in the present embodiment.

[0056] Furthermore, when the first absorption layer 11 and the first conductive layer 12 are made of the same material, in order to simplify the process flow, in this embodiment, the first absorption layer 11 and the first conductive layer 12 are formed by the same preparation process.

[0057] Furthermore, the MEMS device in this embodiment may also include a second dielectric film 5, a third dielectric film 8, and a fourth dielectric film 10; the second dielectric film 5 is connected to the side wall of the first conductive layer 12 away from the electrode 2; the thermosensitive film 6 is located on the surface of the second dielectric film 5; the third dielectric film 8 covers the thermosensitive film 6 and the second dielectric film 5; the second conductive layer 9 covers the third dielectric film 8, and one end penetrates the third dielectric film 8 and is electrically connected to the thermosensitive film 6; the fourth dielectric film 10 covers the second conductive layer 9. Among them, the second dielectric film 5 is used to support the thermosensitive film 6, the third dielectric film 8 is used to isolate the thermosensitive film 6 and the second conductive layer 9, and the fourth dielectric film 10 is used to isolate the second conductive layer 9 and the first conductive layer 12 during the preparation process.

[0058] The present embodiment does not limit the specific type of the second dielectric film 5. The second dielectric film 5 may be, but is not limited to, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a first composite film layer; the first composite film layer may be, but is not limited to, a stacked structure formed by at least two of a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer arranged in sequence along a first direction. The present embodiment does not limit the specific type of the third dielectric film 8. The third dielectric film 8 may be, but is not limited to, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, or a first composite film layer; the first composite film layer may be, but is not limited to, a stacked structure formed by at least two of a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer arranged in sequence along a first direction. The present embodiment does not limit the specific type of the fourth dielectric film 10. It may be any insulating dielectric film.

[0059] Furthermore, in this embodiment, the stacked second dielectric film 5 , the third dielectric film 8 , the second conductive layer 9 and the fourth dielectric film 10 are used as a hard mask to form the first conductive layer 12 .

[0060] Furthermore, the MEMS device in this embodiment further includes a fifth dielectric film 7; the fifth dielectric film 7 covers the thermosensitive film 6; the third dielectric film 8 covers the fifth dielectric film 7 and the second dielectric film 5; one end of the second conductive layer 9 sequentially penetrates the third dielectric film 8 and the fifth dielectric film 7 and is electrically connected to the thermosensitive film 6. It should be noted that the fifth dielectric film 7 is used as a hard mask in the process of forming the patterned thermosensitive film 6 to protect the retained thermosensitive film 6.

[0061] This embodiment does not limit the specific pattern of the thermosensitive film 6, as long as the thermosensitive film 6 and the fifth dielectric film 7 do not cover the electrode 2. For example, the electrode 2 may include a first electrode and a second electrode sequentially arranged along the second direction; the first electrode may be located between adjacent thermosensitive films 6, the second electrode may be located between adjacent thermosensitive films 6, and a thermosensitive film 6 is arranged between the first electrode and the second electrode.

[0062] Furthermore, in this embodiment, the second dielectric film 5, the third dielectric film 8, the second conductive layer 9 and the fourth dielectric film 10 located between the first conductive layer 12 and the thermosensitive film 6 form a bent microbridge structure 14. After the microbridge structure 14 is formed in this embodiment, one end of the second conductive layer 9 is electrically connected to the first conductive layer 12, and the other end of the first conductive layer 9 is electrically connected to the thermosensitive film 6 after being bent at least once on a plane parallel to the readout circuit wafer.

[0063] Based on the above embodiments, the present application adopts a conductive layer with a step coverage ability stronger than that of the titanium layer as an anchor column. When a hard mask is used to form a contact hole, it can better cover the surface of the contact hole in a contact hole with a bottom cut structure, and will not be disconnected at the connection position between the sacrificial layer and the hard mask, thereby ensuring a good electrical connection, thereby improving the stability and reliability of the anchor column; at the same time, the conductive layer serves as both a conductive layer and a supporting layer, replacing the traditional anchor column formed by stacking a supporting layer, a titanium layer and a protective layer, solving the problem that the traditional anchor column uses a titanium layer as a conductive layer and has poor step coverage in the contact hole, and requires a medium for protection and support, and simplifies the process flow.

[0064] Please refer to Figures 1 to 12 , an embodiment of the present application provides a method for preparing an uncooled infrared detector, the method may include:

[0065] S101 : a sacrificial layer 4 is provided on the surface of the readout circuit wafer 1 ; and the readout circuit and the electrode 2 on the surface of the readout circuit wafer 1 are electrically connected.

[0066] This embodiment does not limit the specific types of the film layers that are subsequently arranged. For details, please refer to the embodiment of the above-mentioned preparation method, which will not be described in detail here.

[0067] Furthermore, in this embodiment, before step S101 , a sixth dielectric film 3 may be disposed on the surface of the readout circuit wafer 1 , so that the sixth dielectric film 3 covers the readout circuit wafer 1 and the electrode 2 .

[0068] The present embodiment does not limit the specific type of the sacrificial layer 4. The sacrificial layer 4 may be, but is not limited to, an organic material layer; the organic material layer may be, but is not limited to, a PI (Polyimide) layer, a PMMA (Polymethyl methacrylate) layer, or an amorphous carbon layer. The present embodiment does not limit the specific manner of setting the sacrificial layer 4. The specific manner of setting the sacrificial layer 4 may be determined according to the specific type of the sacrificial layer 4. For example, the sacrificial layer 4 may be coated. That is, in the present embodiment, after the electrodes 2 and the sixth dielectric film 3 are sequentially arranged on the surface of the readout circuit wafer 1 along the first direction, the sacrificial layer 4 may be directly coated on the surface of the readout circuit wafer 1 to cover the sixth dielectric film 3; and finally, the sacrificial layer 4 may be directly released to remove the sacrificial layer 4.

[0069] S102 : preparing a MEMS device; the MEMS device comprises a thermosensitive film 6 and a second conductive layer 9 .

[0070] The present embodiment does not limit the specific method of preparing the MEMS device, and the specific method of preparing the MEMS device can be determined according to the specific structure of the MEMS device. For example, the second dielectric film 5, the thermosensitive film 6, the third dielectric film 8, the second conductive layer 9 and the fourth dielectric film 10 can be sequentially arranged along the first direction on the surface of the sacrificial layer away from the readout circuit wafer 1; the second dielectric film 5 is connected to the side wall of the first conductive layer 12 away from the electrode 2; the thermosensitive film 6 is located on the surface of the second dielectric film 5; the third dielectric film 8 covers the thermosensitive film 6 and the second dielectric film 5; the second conductive layer 9 covers the third dielectric film 8, and one end thereof penetrates through the third dielectric film 8 and is electrically connected to the thermosensitive film 6; and the fourth dielectric film 10 covers the second conductive layer 9.

[0071] Further, in this embodiment, after the second dielectric film 5, the thermosensitive film 6, the third dielectric film 8, the second conductive layer 9 and the fourth dielectric film 10 are sequentially arranged along the first direction, the fourth dielectric film 10, the second conductive layer 9, the third dielectric film 8 and the second dielectric film 5 can be sequentially etched along the first direction to form a hard mask. The hard mask can be used to form the first conductive layer 12. It should be noted that when etching to form the hard mask, the top film layer may be transitionally etched to both sides in a direction parallel to the film layer surface at the opening position.

[0072] It should be noted that in this embodiment, the thermosensitive film 6 is formed before etching the contact hole, which can avoid the thermosensitive film 6 being deposited in the through hole, making it difficult to etch the thermosensitive film 6 in the through hole, and causing product failure.

[0073] Furthermore, in this embodiment, a fifth dielectric film 7 may be disposed on the surface of the thermosensitive film 6 to serve as a hard mask in the process of forming the patterned thermosensitive film 6 to protect the retained thermosensitive film 6. The specific steps may be:

[0074] On a surface of the sacrificial layer 4 facing away from the readout circuit wafer 1, a second dielectric film 5, a thermosensitive film 6 and a fifth dielectric film 7 are sequentially arranged along a first direction;

[0075] The first stacked structure composed of the thermosensitive film 6 and the fifth dielectric film 7 is subjected to a patterning process;

[0076] A third dielectric film 8 is provided on the surface of the readout circuit wafer 1 having the patterned first stacked structure;

[0077] Performing a patterning process on the second stacked structure composed of the fifth dielectric film 7 and the third dielectric film 8;

[0078] A second conductive layer 9 is provided on the surface of the readout circuit wafer 1 having the patterned second stacked structure, and the second conductive layer 9 is patterned; one end of the second conductive layer 9 sequentially penetrates the third dielectric film 8 and the fifth dielectric film 7 and is electrically connected to the thermosensitive film 6;

[0079] A fourth dielectric film 10 is provided on the surface of the readout circuit wafer 1 on which the patterned second conductive layer 9 is formed.

[0080] The present embodiment does not limit the specific manner of setting the second dielectric film 5, and the second dielectric film 5 can be grown in a corresponding manner according to the specific type of the second dielectric film 5. The present embodiment does not limit the specific manner of setting the thermosensitive film 6, and the thermosensitive film 6 can be grown in a corresponding manner according to the specific type of the thermosensitive film 6. The present embodiment does not limit the specific manner of setting the fifth dielectric film 7, and the fifth dielectric film 7 can be grown in a corresponding manner according to the specific type of the fifth dielectric film 7.

[0081] The present embodiment does not limit the specific method of setting the third dielectric film 8. The third dielectric film 8 can be grown in a corresponding manner according to the specific type of the third dielectric film 8. For example, the third dielectric film 8 can be deposited on the surface of the readout circuit wafer 1 having the patterned first stacked structure by CVD (Chemical Vapor Deposition).

[0082] This embodiment does not limit the specific method of setting the second conductive layer 9. The second conductive layer 9 can be grown in a corresponding manner according to the specific type of the second conductive layer 9. For example, the second conductive layer 9 can be deposited on the surface of the readout circuit wafer 1 having a patterned second stacked structure by PVD (Physical Vapor Deposition).

[0083] The present embodiment does not limit the specific manner of disposing the fourth dielectric film 10 , and a corresponding manner may be selected to grow the fourth dielectric film 10 according to the specific type of the fourth dielectric film 10 .

[0084] This embodiment does not limit the specific method of patterning the first stacked structure, as long as it is ensured that the thermosensitive film 6 and the fifth dielectric film 7 do not cover the electrode 2. For example, when the electrode 2 includes a first electrode and a second electrode sequentially arranged along the second direction, the thermosensitive film 6 and the fifth dielectric film 7 covering the first electrode, and the thermosensitive film 6 and the fifth dielectric film 7 covering the second electrode can be etched away, so that the first electrode is located between adjacent thermosensitive films 6, the second electrode is located between adjacent thermosensitive films 6, and a thermosensitive film 6 is arranged between the first electrode and the second electrode.

[0085] This embodiment does not limit the specific method of etching the thermosensitive film 6 and the fifth dielectric film 7, as long as it is ensured that the thermosensitive film 6 and the fifth dielectric film 7 covering the electrode 2 can be removed. For example, a photolithography method can be used to etch and remove the thermosensitive film 6 and the fifth dielectric film 7 covering the first electrode, and the thermosensitive film 6 and the fifth dielectric film 7 covering the second electrode.

[0086] S103: etching the sacrificial layer 4 along the first direction to expose the electrode 2 and form a contact hole.

[0087] It should be noted that in this embodiment, a conductive layer with a step coverage capability stronger than that of the titanium layer is used as the anchor column. The conductive layer serves as both a conductive layer and a supporting layer, which solves the problem that the traditional anchor column 12 uses a titanium layer as a conductive layer and has poor step coverage capability in the contact hole, and requires a dielectric for protection and support. The contact hole can be achieved in just one step, simplifying the process flow.

[0088] This embodiment does not limit the specific method of forming the contact hole, as long as it is ensured that the electrode 2 can be exposed. For example, the stacked second dielectric film 5, the third dielectric film 8, the second conductive layer 9 and the fourth dielectric film 10 can be used as a hard mask, and the sacrificial layer 4 can be etched along the first direction using the hard mask to expose the electrode 2 to form a contact hole. It should be noted that when the sacrificial layer 4 is etched using the hard mask, an undercut will be formed. The contact hole actually formed in this embodiment includes a first through hole penetrating the sacrificial layer 4 (when the surface of the electrode 2 is covered with the sixth dielectric film 3, the first through hole will also penetrate the sixth dielectric film 3) and a second through hole penetrating the hard mask; the width of the first through hole is greater than the width of the second through hole. The contact hole is a stepped shape with a narrow top and a wide bottom.

[0089] It should be noted that, in this embodiment, all the film layers are deposited first, and then all the film layers stacked on the surface of the sacrificial layer 4 are used as a hard mask, and the sacrificial layer 4 and the dielectric film at the bottom of the sacrificial layer 4 are etched to form a contact hole. Since the composite film layer is used as a hard mask when etching the sacrificial layer 4, the size of the anchor column can be better controlled, thereby ensuring that the size of the anchor column meets the miniaturization requirement; at the same time, a conductive layer with a step coverage ability stronger than that of the titanium layer is set inside the contact hole as an anchor column, so that this embodiment can simultaneously achieve the reduction of the size of the anchor column and maintain the stability and reliability of the anchor column.

[0090] S104: a first conductive layer 12 is disposed on the inner surface of the contact hole to form an anchor column; the step coverage capability of the first conductive layer 12 is stronger than that of the titanium layer; the electrode 2, the first conductive layer 12, the second conductive layer 9 and the thermosensitive film 6 are electrically connected in sequence.

[0091] It should be noted that, in this embodiment, the first conductive layer 12 is disposed on the bottom surface and the side surface inside the contact hole.

[0092] This embodiment does not limit the specific method of forming the anchor column, as long as the first conductive layer 12 can cover the inner surface of the contact hole, for example, the following method can be used:

[0093] A first conductive layer 12 is provided on the surface of the readout circuit wafer 1 where the contact hole is formed;

[0094] The first conductive layer 12 is patterned to retain the first conductive layer 12 covering the inner surface of the contact hole to form an anchor column.

[0095] This embodiment does not limit the specific method of setting the first conductive layer 12. The first conductive layer 12 can be grown in a corresponding manner according to the specific type of the first conductive layer 12. For example, when the first conductive layer 12 is a titanium nitride layer, the first conductive layer 12 can be deposited on the surface of the readout circuit wafer 1 with contact holes using CVD.

[0096] It should be noted that in this embodiment, the titanium nitride layer is electrically connected to the thermosensitive film 6 indirectly through the second conductive layer 9, which can solve the problem of high contact resistance and poor conductivity when the titanium nitride layer is directly connected to the thermosensitive film 6.

[0097] Furthermore, when the ability of the first conductive layer 12 to absorb infrared light is stronger than that of the titanium layer, in this embodiment, the first conductive layer 12 is patterned, and the first conductive layer 12 covering the thermosensitive film 6 can be retained to form the first absorption layer 11. Furthermore, according to the specific pattern of the thermosensitive film 6, in this embodiment, the first conductive layer 12 covering the thermosensitive film 6 between the first electrode and the second electrode can be retained to form the first absorption layer 11. It should be noted that the provision of the first absorption layer 11 can increase infrared absorption.

[0098] The present embodiment does not limit the specific method of patterning the first conductive layer 12, as long as the first conductive layer 12 covering the thermosensitive film 6 and the inner surface of the contact hole can be retained, for example, the first conductive layer 12 can be patterned using a photolithography method.

[0099] Furthermore, after forming the first absorption layer 11, the present embodiment may also include: setting a second absorption layer on the surface of the first absorption layer 11. The present embodiment does not limit the specific manner of setting the second absorption layer. For example, a sacrificial layer 4 may be set on the surface of the readout circuit wafer 1 on which the first absorption layer 11 is formed; the sacrificial layer 4 is etched to expose the first absorption layer 11; a second absorption layer is set, and the sacrificial layer 4 is removed. It should be noted that setting the second absorption layer can further increase infrared absorption. The structure prepared by this method is a multi-layer FPA structure. The present application can be used not only for single-layer FPA structures, but also for the layer where the heat-sensitive film 6 is located in a multi-layer FPA structure.

[0100] Furthermore, after step S104, this embodiment may further include: providing a first dielectric film 13 on the surface of the readout circuit wafer 1 formed with the first conductive layer 12. It should be noted that the first dielectric film 13 is provided to prevent the first conductive layer 12 from contacting the air, and to provide auxiliary support for the first conductive layer 12, thereby further improving the stability and reliability of the anchor column.

[0101] Furthermore, after step S104, this embodiment may further include: etching the fourth dielectric film 10, the second conductive layer 9, the third dielectric film 8, and the second dielectric film 5 between the first conductive layer 12 and the thermosensitive film 6 along the third direction to form a bent microbridge structure 14. After the microbridge structure 14 is formed in this embodiment, one end of the second conductive layer 9 is electrically connected to the first conductive layer 12, and the other end of the first conductive layer 9 is electrically connected to the thermosensitive film 6 after being bent at least once on a plane parallel to the readout circuit wafer.

[0102] S105: removing the sacrificial layer 4 to obtain an uncooled infrared detector.

[0103] Based on the above embodiments, the present application can prepare the above-mentioned uncooled infrared detector, which also has the above-mentioned beneficial effects.

[0104] The following is a specific example to illustrate the preparation process of the above uncooled infrared detector. Please refer to Figures 2 to 12 , Figures 2 to 12 A schematic diagram of a process for preparing an uncooled infrared detector provided in an embodiment of the present application is provided. The process is as follows:

[0105] 1. If Figure 2 As shown, a readout circuit wafer 1 is provided, and an electrode 2 and a sixth dielectric film 3 are arranged on the surface of the readout circuit wafer 1;

[0106] 2. If Figure 3 As shown, a sacrificial layer 4 is coated on the surface of the readout circuit wafer 1, and a second dielectric film 5 and a fifth dielectric film 7 are grown;

[0107] 3. If Figure 4 As shown, a pattern is etched on the thermosensitive film 6 and the fifth dielectric film 7 using a photolithography method, so that the thermosensitive film 6 and the fifth dielectric film 7 do not cover the electrode 2;

[0108] 4. If Figure 5 As shown, the third dielectric film 8 is deposited by CVD, and patterns are etched on the fifth dielectric film 7 and the third dielectric film 8 to expose the thermosensitive film 6;

[0109] 5. If Figure 6 As shown, the second conductive layer 9 is deposited by PVD to form a pattern;

[0110] 6. If Figure 7 As shown, a fourth dielectric film 10 is grown;

[0111] 7. If Figure 8As shown, the fourth dielectric film 10, the second conductive layer 9, the third dielectric film 8, and the second dielectric film 5 are sequentially etched to form a hard mask; the sacrificial layer 4 and the sixth dielectric film 3 are sequentially etched using the hard mask to expose the electrode 2 and form a contact hole;

[0112] 8. If Fig. 9 As shown, the first conductive layer 12 is deposited by CVD, and is patterned by photolithography, the first conductive layer 12 covering the inner surface of the contact hole is retained as an anchor, and the first conductive layer 12 covering the thermosensitive film 6 between the two electrodes 2 is retained as a first absorption layer 11;

[0113] 9. If Fig.10 As shown, a first dielectric film 13 is deposited;

[0114] 10. Fig.11 As shown, a microbridge structure 14 is etched out.

[0115] 11. If Fig.12 As shown, the sacrificial layer 4 is released to form a suspended structure, thereby obtaining a pixel structure of an uncooled infrared detector.

[0116] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the embodiments are in a progressive relationship, each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The description of the above embodiments is only used to help understand the method and core ideas of the present application. For ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0117] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

Claims

1. An uncooled infrared detector, characterized in that: include: A readout circuit wafer (1), an electrode (2), an anchor column and a MEMS device; the anchor column comprises a first conductive layer (12); the MEMS device comprises a thermosensitive film (6) and a second conductive layer (9); the readout circuit on the surface of the readout circuit wafer (1), the electrode (2), the first conductive layer (12), the second conductive layer (9) and the thermosensitive film (6) are electrically connected in sequence; and the step coverage capability of the first conductive layer (12) is stronger than that of the titanium layer.

2. The uncooled infrared detector according to claim 1, characterized in that: The anchor column further comprises a first dielectric film (13); the first dielectric film (13) covers a surface of the first conductive layer (12) that is away from the electrode (2).

3. The uncooled infrared detector according to claim 1, characterized in that: The MEMS device further comprises a first absorption layer (11); the first absorption layer (11) covers the thermosensitive film (6).

4. The uncooled infrared detector according to claim 3, characterized in that: The first absorption layer (11) and the first conductive layer (12) are made of the same material; the first conductive layer (12) has a stronger ability to absorb infrared light than the titanium layer.

5. The uncooled infrared detector according to claim 4, characterized in that: The first absorption layer (11) and the first conductive layer (12) are formed by the same preparation process.

6. The uncooled infrared detector according to claim 1, characterized in that: The MEMS device further comprises a second dielectric film (5), a third dielectric film (8) and a fourth dielectric film (10); The second dielectric film (5) is connected to a side wall of the first conductive layer (12) at one end facing away from the electrode (2); the thermosensitive film (6) is located on the surface of the second dielectric film (5); The third dielectric film (8) covers the thermosensitive film (6) and the second dielectric film (5); the second conductive layer (9) covers the third dielectric film (8), and one end of the second conductive layer penetrates through the third dielectric film (8) and is electrically connected to the thermosensitive film (6); The fourth dielectric film (10) covers the second conductive layer (9).

7. The uncooled infrared detector according to claim 6, characterized in that: The stacked second dielectric film (5), the third dielectric film (8), the second conductive layer (9) and the fourth dielectric film (10) are used as a hard mask to form the first conductive layer (12).

8. The uncooled infrared detector according to claim 6, characterized in that: The MEMS device further comprises a fifth dielectric film (7); the fifth dielectric film (7) covers the thermosensitive film (6); the third dielectric film (8) covers the fifth dielectric film (7) and the second dielectric film (5); and one end of the second conductive layer (9) sequentially penetrates the third dielectric film (8) and the fifth dielectric film (7) to be electrically connected to the thermosensitive film (6).

9. The uncooled infrared detector according to claim 6, characterized in that: The second dielectric film (5), the third dielectric film (8), the second conductive layer (9) and the fourth dielectric film (10) located between the first conductive layer (12) and the thermosensitive film (6) form a bent microbridge structure (14).

10. A method for preparing an uncooled infrared detector, characterized in that: include: A sacrificial layer (4) is provided on the surface of a readout circuit wafer (1); the readout circuit on the surface of the readout circuit wafer (1) is electrically connected to the electrode (2); Prepare a MEMS device; the MEMS device comprises a thermosensitive film (6) and a second conductive layer (9); Etching the sacrificial layer (4) along a first direction to expose the electrode (2) and form a contact hole; A first conductive layer (12) is arranged on the inner surface of the contact hole to form an anchor column; the step coverage capability of the first conductive layer (12) is stronger than that of the titanium layer; the electrode (2), the first conductive layer (12), the second conductive layer (9) and the thermosensitive film (6) are electrically connected in sequence; The sacrificial layer (4) is removed to obtain the uncooled infrared detector.

11. The method for preparing an uncooled infrared detector according to claim 10, characterized in that: The step of providing a first conductive layer (12) on the inner surface of the contact hole to form an anchor column comprises: The first conductive layer (12) is arranged on the surface of the readout circuit wafer (1) on which the contact hole is formed; the first conductive layer (12) has a stronger ability to absorb infrared light than the titanium layer; The first conductive layer (12) is patterned to retain the first conductive layer (12) covering the inner surface of the contact hole to form the anchor column, and the first conductive layer (12) covering the thermosensitive film (6) is retained to form a first absorption layer (11).

12. The method for preparing an uncooled infrared detector according to claim 10, characterized in that: The method of preparing a MEMS device comprises: On a surface of the sacrificial layer (4) facing away from the readout circuit wafer (1), a second dielectric film (5), the thermosensitive film (6), a third dielectric film (8), the second conductive layer (9) and a fourth dielectric film (10) are sequentially arranged along the first direction; The second dielectric film (5) and the first conductive layer (12) are connected at the side wall of one end away from the electrode (2); the thermosensitive film (6) is located on the surface of the second dielectric film (5); the third dielectric film (8) covers the thermosensitive film (6) and the second dielectric film (5); the second conductive layer (9) covers the third dielectric film (8), and one end penetrates the third dielectric film (8) and is electrically connected to the thermosensitive film (6); the fourth dielectric film (10) covers the second conductive layer (9).

13. The method for preparing an uncooled infrared detector according to claim 12, characterized in that: The step of etching the sacrificial layer (4) along a first direction to expose the electrode (2) and form a contact hole comprises: The second dielectric film (5), the third dielectric film (8), the second conductive layer (9) and the fourth dielectric film (10) that are stacked are used as a hard mask, and the sacrificial layer (4) is etched along the first direction using the hard mask to expose the electrode (2), thereby forming the contact hole.

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