CN114739519A

CN114739519A - Packaging cover plate of detector, preparation method of packaging cover plate and detector

Info

Publication number: CN114739519A
Application number: CN202210647704.2A
Authority: CN
Inventors: 崔亚春; 刘建华; 丁金玲
Original assignee: Hangzhou Hikmicro Sensing Technology Co Ltd
Current assignee: Hangzhou Hikmicro Sensing Technology Co Ltd
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2022-07-12
Anticipated expiration: 2042-06-09
Also published as: CN114739519B

Abstract

The invention discloses a packaging cover plate of a detector, a preparation method of the packaging cover plate and the detector, relates to the field of microelectronics, and aims to improve the influence of infrared radiation of a target object on a reference pixel structure. The detector includes a plurality of active pixel structures and a plurality of reference pixel structures. The package cover includes a cover body and an infrared absorbing structure. The infrared absorbing structure is for absorbing infrared radiation directed to a plurality of reference pixel structures external to the detector. The packaging cover plate provided by the embodiment of the invention can improve the influence of the infrared radiation of a target object on the reference pixel structure in the detector, so that the detector can better utilize the reference pixel structure to eliminate the influence of the temperature of the semiconductor substrate on the effective pixel structure, and the detection precision is improved.

Description

Packaging cover plate of detector, preparation method of packaging cover plate and detector

Technical Field

The invention relates to the field of microelectronics, in particular to a packaging cover plate of a detector, a preparation method of the packaging cover plate and the detector.

Background

The microbolometer is the most representative uncooled infrared focal plane detector, the pixel of the microbolometer adopts a microbridge structure manufactured by a Micro-Electro-Mechanical System (MEMS) technology, the bridge deck of the microbridge structure consists of an absorption layer for absorbing infrared radiation energy and a thermal resistance layer (usually amorphous silicon or vanadium oxide) sensitive to red light, and the bridge pier and the bridge arm have the functions of supporting and electrically connecting. When infrared radiation is incident on the pixel bridge floor, the resistance value of the thermistor changes along with the temperature, the variable quantity of the thermistor is detected by a corresponding CMOS (Complementary Metal Oxide Semiconductor) reading Circuit (ROIC) and converted into a corresponding electrical signal to be output, so that the intensity of the external infrared radiation is judged, and meanwhile, the information of the target object is obtained through the difference of the radiation degrees of the target object and background information. However, the resistance of the thermistor of the microbolometer is not only related to the change of the infrared radiation of the target object, but also affected by the current substrate temperature, and since the infrared radiation of the target object causes only a slight temperature change, the presence of the substrate temperature will seriously affect the detection of the infrared radiation of the target object by the detector.

Disclosure of Invention

The embodiment of the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides a package cover plate of a detector, where the detector includes a plurality of active pixel structures and a plurality of reference pixel structures. The package cover includes a cover body and an infrared absorbing structure. The infrared absorption structure is positioned on one side of the cover plate main body and is used for absorbing infrared radiation emitted to the plurality of reference pixel structures. When the packaging cover plate of the embodiment is used on a detector, the infrared absorption structure does not influence the infrared radiation of an external target object to the effective pixel structure, but can absorb the infrared radiation of the external target object to the reference pixel structure, so that the reference pixel structure has no response to the radiation of the external target object. Therefore, the reference pixel structure in the detector is only influenced by the temperature of the semiconductor substrate and the Joule temperature rise, and the effective pixel structure is influenced by the infrared radiation of an external target object besides the temperature of the semiconductor substrate and the Joule temperature rise. The infrared radiation of an external target object can be obtained through the signal difference between the reference pixel structure and the effective pixel structure. Namely, the encapsulation cover plate of the embodiment can effectively eliminate the influence of the temperature of the semiconductor substrate and the joule temperature rise on the effective pixel structure in the detector so as to accurately acquire the absolute infrared radiation of the target object.

Optionally, the infrared absorbing structure is a super surface absorbing structure. The super-surface absorption structure comprises a first metal layer, an insulating medium layer and a second metal layer. The first metal layer is positioned on one side of the packaging cover plate far away from the semiconductor substrate. The insulating medium layer is positioned on one side of the first metal layer far away from the packaging cover plate. The second metal layer is positioned on one side of the insulating medium layer far away from the first metal layer. The second metal layer comprises a plurality of columnar structures arranged at intervals. At this time, the orthographic projection shape of the columnar structure on the insulating medium layer can be a regular pattern or an irregular pattern. With such a configuration, the infrared absorption structure of the embodiment forms a Metal-Insulator-Metal (MIM) resonant structure, and can achieve high absorption in a wide wavelength band (e.g., 8 μm to 14 μm) in the infrared region. In this case, the entire infrared absorbing structure can be considered as a resonant cavity. When the incident light penetrates through the second metal layer, the first metal layer can act as a reflecting mirror surface and can reflect surface plasmon polariton polarized waves excited by an interface between the first metal layer and the insulating medium layer. Meanwhile, the plurality of columnar structures in the second metal layer can also serve as a plurality of local reflecting mirror surfaces to reflect surface plasmon polariton waves excited by the interface between the second metal layer and the insulating medium layer. The surface plasmon polariton waves excited by the interface between the first metal layer and the insulating medium layer and the surface plasmon polariton waves excited by the interface between the second metal layer and the insulating medium layer are subjected to destructive interference, so that a resonant cavity mode is excited. The high absorption of the infrared band can be realized by reasonably designing the geometric parameters of the infrared absorption structure. In addition, the second metal layer of the embodiment includes a plurality of columnar structures arranged at intervals, and a coupling effect can be generated among the plurality of columnar structures, so that the absorption rate of infrared radiation of a target object can be improved.

Optionally, the thickness of the first metal layer is larger than the skin depth of the infrared radiation of the target objectδ；

Wherein,

is the circumferential ratio;

the operating frequency of the infrared absorbing structure;

is the permeability of the first metal layer;

is the conductivity of the first metal layer. In this embodiment, the thickness of the first metal layer is set to be greater than the skin depth of the infrared radiation of the target object, so that the transmittance of the first metal layer can be approximately 0, and the infrared radiation is effectively prevented from passing through the infrared absorption structure.

Optionally, the shape of the orthographic projection of the at least one columnar structure on the insulating medium layer is a regular pattern. Or the orthographic projection shape of the at least one columnar structure on the insulating medium layer is a centrosymmetric pattern. Or the orthographic projection of the columnar structure on the insulating medium layer is circular. The radius of the columnar structure is 0.25 μm to 2.5 μm.

Regular patterns may include, for example, circles, equilateral triangles, squares, and other regular polygons. In this embodiment, the regular shape of the orthographic projection of the columnar structure on the insulating medium layer can reduce the influence of the incident angle on the absorption performance of the infrared absorption structure, that is, the sensitivity of the absorption spectrum of the columnar structure to the incident angle.

The centrosymmetric pattern may include, for example, a circle, a square, etc. By the arrangement, the infrared absorption structure has good polarization performance, and the influence of an incident angle on the absorption performance of the infrared absorption structure can be reduced.

The shape of the orthographic projection of the columnar structure on the insulating medium layer is circular, and when the radius of the columnar structure is 0.25-2.5 microns, the absorption rate of the columnar structure to infrared radiation of a target object can be improved.

Optionally, the characteristic dimension of the columnar structure is of sub-wavelength magnitude, and the plurality of columnar structures are periodically arranged. Wherein the feature size comprises at least one of: a maximum width of the columnar structure in a direction parallel to the first metal layer; when the orthographic projection of the columnar structure on the first metal layer is a polygon, the length of the longest edge of the polygon is equal to the length of the longest edge of the polygon; alternatively, the maximum height of the columnar structure in a direction perpendicular to the first metal layer.

For example, when the shape of the orthographic projection of the columnar structure on the insulating medium layer is a circle, the characteristic dimension of the columnar structure may include at least one of the radius of the orthographic projection and the height of the columnar structure; when the shape of the orthographic projection of the columnar structure on the insulating medium layer is square, the characteristic dimension of the columnar structure comprises at least one of the side length, the diagonal distance and the height of the orthographic projection.

In an example, the sub-wavelength level is one level smaller than the operating wavelength (e.g., 0.1 times one level), and if the operating wavelength is 8 μm to 14 μm, the characteristic dimension of the columnar structure is 0.8 μm to 1.4 μm, which can be specifically adjusted according to the operating wavelength.

Exemplary periodic arrangements include square arrays, circular arrays, and the like.

By such arrangement, the characteristic dimension of the columnar structure is in the sub-wavelength order and is periodically arranged, so that the second metal layer is equivalent to a uniform medium capable of absorbing infrared radiation. And then the electromagnetic property of the second metal layer can be analyzed through an equivalent medium theory so as to obtain the electromagnetic property parameters of the second metal layer. Then, by designing the structural characteristics of the columnar structure, for example, changing the shape, characteristic dimension, material, and the like of the columnar structure, the equivalent permittivity and permeability of the second metal layer can be controlled and modulated to achieve the equivalent permittivity and equivalent permeability of the columnar structure. At this time, the impedance of the second metal layer is equal to the wave impedance of the electromagnetic wave in vacuum, and impedance matching between the second metal layer and the surrounding air medium is realized, so that the incident electromagnetic wave can pass through the second metal layer without obstruction, and the reflectivity is approximately 0.

Optionally, the material of the cover plate main body includes at least one of silicon or germanium.

Optionally, the thickness of the second metal layer is 0.01 μm to 0.1 μm. That is, the height of each columnar structure is 0.01 μm to 0.1 μm. It will be appreciated that with a thinner second metal layer, the infrared absorbing structure has lower losses and lower absorption. In order to achieve high losses and high absorption of the infrared absorbing structure, the second metal layer should be as thick as possible. However, in order to achieve the coupling effect, the second metal layer should be as thin as possible. Therefore, according to the working requirement, a compromise thickness range of 0.01-0.1 μm is selected for the second metal layer. When the thickness of the second metal layer is within this range, the absorption performance and coupling effect of the infrared absorbing structure can meet the working requirements.

Optionally, the material of the first metal layer includes at least one of titanium or gold.

The material of the second metal layer comprises at least one of titanium or gold.

Titanium (Ti) has a high loss characteristic in the infrared band, and can enhance absorption of infrared radiation, so that the arrangement can improve the infrared radiation absorption rate of the first metal layer and the second metal layer. The gold (Au) has better reflectivity, and can enable the first metal layer and the second metal layer to have higher reflectivity.

Optionally, the material of the insulating dielectric layer includes at least one of silicon dioxide or germanium.

Optionally, the package cover plate further includes an antireflection film. The antireflection film is positioned on the surface of the cover plate main body far away from the infrared absorption structure, or is positioned on the same side surface of the cover plate main body with the infrared absorption structure. The orthographic projection of the antireflection film on the cover plate main body is not overlapped with the orthographic projection of the infrared absorption structure on the cover plate main body. The antireflection film can reduce or eliminate the reflected light of the optical surface, thereby increasing the light transmission amount of the element and reducing or eliminating the stray light of the system. So set up, can reduce the encapsulation apron to external target object infrared radiation's reflectivity to improve transmissivity.

Optionally, the orthographic projection of the antireflection film on the semiconductor substrate of the detector covers a plurality of effective pixel structures. So set up, can make the more effective radiation of infrared radiation of target object to effective pixel structure.

In a second aspect, an embodiment of the present invention provides a method for manufacturing a package cover plate, including:

forming a first metal layer on one side of the cover plate main body;

forming an insulating medium layer on one side of the first metal layer far away from the cover plate main body;

forming a second metal layer on one side of the insulating medium layer far away from the first metal layer;

and patterning the second metal layer to form a plurality of columnar structures.

The method for manufacturing the package cover plate provided by the embodiment of the invention can manufacture the package cover plate of the detector in the first aspect, and the package cover plate of the detector can improve the influence of the infrared radiation of a target object on a reference pixel structure in the detector, so that the detector can better utilize the reference pixel structure to eliminate the influence of the temperature of a semiconductor substrate on an effective pixel structure, and the detection precision is improved.

Optionally, the method further includes: an antireflection film is formed on the surface of the cover plate main body. The orthographic projection of the antireflection film on the cover plate main body is not overlapped with the orthographic projection of the first metal layer on the cover plate main body, and the orthographic projection of the antireflection film on the semiconductor substrate can cover a plurality of effective pixel structures.

In a third aspect, embodiments of the present invention provide a probe. The detector comprises a semiconductor substrate, a plurality of effective pixel structures, a plurality of reference pixel structures and the packaging cover plate. The plurality of effective pixel structures are located on one side of the semiconductor substrate and electrically connected with the readout circuit. The plurality of reference pixel structures and the plurality of effective pixel structures are located on the same side of the semiconductor substrate, and the plurality of reference pixel structures are electrically connected with the readout circuit. The orthographic projection of the multiple reference pixel structures on the semiconductor substrate is not overlapped with the orthographic projection of the multiple effective pixel structures on the semiconductor substrate. The packaging cover plate is positioned on one side of the plurality of effective pixel structures and the plurality of reference pixel structures, which is far away from the semiconductor substrate. Wherein, the orthographic projection of the infrared absorption structure on the semiconductor substrate covers the plurality of reference pixel structures, and does not cover the plurality of effective pixel structures.

It should be noted that the temperature change of the effective pixel structure is not only affected by the infrared radiation of the target object, but also affected by the temperature of the semiconductor substrate and joule heating, and the temperature change of the effective pixel structure caused by the temperature of the semiconductor substrate is many times greater than the temperature change of the effective pixel structure caused by absorbing the infrared radiation of the target object, so the presence of the temperature of the semiconductor substrate will seriously affect the detection of the infrared radiation of the target object by the detector. Therefore, the reference pixel structure is arranged in the embodiment, and the influence of the temperature of the semiconductor substrate and joule heating on the effective pixel structure can be eliminated by utilizing the signal difference between the reference pixel structure and the effective pixel structure.

In addition, the package cover plate of the embodiment is provided with an infrared absorption structure. The orthographic projection of the infrared absorption structure on the semiconductor substrate covers the plurality of reference pixel structures and does not cover the plurality of effective pixel structures. According to the arrangement, the infrared absorption structure can absorb the infrared radiation of the external target object to the reference pixel structure, so that the reference pixel structure has no response to the radiation of the external target object. But the infrared absorption structure does not influence the infrared radiation of an external target object to the effective pixel structure. Therefore, the reference pixel structure is only influenced by the temperature of the semiconductor substrate and the Joule temperature rise, and the effective pixel structure is influenced by the infrared radiation of an external target object besides the temperature of the semiconductor substrate and the Joule temperature rise. The infrared radiation of an external target object can be obtained through the signal difference between the reference pixel structure and the effective pixel structure, namely, the influence of the temperature and joule temperature rise of the semiconductor substrate on the effective pixel structure is effectively eliminated by arranging the infrared absorption structure and the reference pixel structure, so that the absolute infrared radiation of the target object is accurately obtained.

Optionally, the height between the semiconductor substrate and the package cover plate is h. The orthographic projection of the infrared absorption structure on the semiconductor substrate is a first projection, the orthographic projection of the multiple reference pixel structures on the semiconductor substrate is a second projection, and the orthographic projection of the multiple effective pixel structures on the semiconductor substrate is a third projection. The second projection is located within the first projection and the third projection is located outside the first projection. The minimum distance d1 from any point on the boundary of the first projection to the boundary of the second projection is 1.5 h-2.5 h. The minimum distance d2 from any point on the boundary of the first projection to the boundary of the third projection is 1.5 h-3.5 h. According to the arrangement, the plurality of reference pixel structures can be prevented from receiving radiation of an external target object, the influence of the infrared absorption structure on the effective pixel structures is avoided, and the plurality of effective pixel structures can work normally.

Optionally, the plurality of effective pixel structures are arranged in multiple rows and multiple columns to form an effective pixel array. The plurality of reference pixel structures includes a plurality of first reference pixel structures and a plurality of second reference pixel structures. The plurality of first reference pixel structures are arranged in multiple rows to form a first reference pixel array. The first reference pixel array is located on one side or both sides of the effective pixel array in the column direction. The plurality of second reference pixel structures are arranged in a plurality of rows to form a second reference pixel array. The second reference pixel array is positioned on one side or two sides of the effective pixel array along the row direction.

It can be understood that the effective pixel array has a certain length and width, the position of each effective pixel structure on the semiconductor substrate is different, and the substrate temperature of the position of each effective pixel structure is different. The plurality of first reference pixel structures form a first reference pixel array which is positioned on one side or two sides of the effective pixel array along the column direction, and the temperature difference between the effective pixel structures arranged along the row direction can be offset. And a plurality of second reference pixel structures form a second reference pixel array which is positioned on one side or two sides of the effective pixel array along the row direction and can offset the temperature difference between the effective pixel structures of each row arranged along the column direction. And then, the absolute infrared radiation of the target object is accurately acquired.

And each column in the first reference pixel array is arranged in parallel with each column in the effective pixel array. And each row in the second reference pixel array is arranged in parallel with each row in the effective pixel array. The first reference pixel array is arranged for eliminating the temperature difference between the effective pixel structures of all the rows arranged along the row direction of the effective pixel array, the second reference pixel array is arranged for eliminating the temperature difference between the effective pixel structures of all the rows arranged along the row direction of the effective pixel array, and then the influence of the temperature of the semiconductor substrate on the effective pixel array can be effectively eliminated through the matching of the first reference pixel array and the second reference pixel array.

The number of columns of the first reference pixel array is equal to that of the effective pixel array; the number of rows of the second reference pixel array is equal to the number of rows of the effective pixel array. And/or the number of rows of the first reference pixel array is greater than or equal to 10 rows; the number of columns of the second reference pixel array is greater than or equal to 10 columns. By the arrangement, the first reference pixel array can more effectively offset the temperature difference of each row of effective pixel structures arranged along the row direction, and the second reference pixel array can more effectively offset the temperature difference of each row of effective pixel structures arranged along the row direction.

Optionally, the first reference pixel array is located on one side of the effective pixel array along the column direction. The second reference pixel array is located on one side of the effective pixel array along the row direction. The infrared absorbing structure includes a first portion and a second portion. The orthographic projection of the first part on the semiconductor substrate is a first sub-projection, and the orthographic projection of the first reference pixel array on the semiconductor substrate is a third sub-projection. The third sub-projection is located within the first sub-projection. The orthographic projection of the second portion on the semiconductor substrate is a second sub-projection. The orthographic projection of the second reference pixel array on the semiconductor substrate is a fourth sub-projection. The fourth sub-projection is located within the second sub-projection. The minimum distance from any point on the boundary of the third sub-projection to the boundary of the first sub-projection is d3, the value range of d3 is 1.5 h-2.5 h, the minimum distance from any point on the boundary of the fourth sub-projection to the boundary of the second sub-projection is d4, and the value range of d4 is 1.5 h-2.5 h.

According to the arrangement, the first reference pixel array and the second reference pixel array can not receive infrared radiation of an external target object more effectively, and the influence of the infrared radiation of the external target object on the first reference pixel array and the second reference pixel array is avoided more effectively.

Optionally, the height between the semiconductor substrate and the package cover plate is h. The orthographic projection of the effective pixel array on the semiconductor substrate is a third projection. Any point on the boundary of the first sub-projection, the minimum distance d11 to the boundary of the third sub-projection; at any point on the boundary of the first sub-projection, the minimum distance to the boundary of the third projection is d 21. The value range of d11 is 1.5-2.5 h. The value range of d21 is 1.5-3.5 h. The minimum distance from any point on the boundary of the second sub-projection to the boundary of the fourth sub-projection is d 12; at any point on the boundary of the second sub-projection, the minimum distance to the boundary of the third projection is d 22. The value range of d12 is 1.5-2.5 h; the value range of d22 is 1.5-3.5 h. So set up, can avoid infrared absorption structure to the influence of effective pixel array more effectively, guarantee effective pixel array can normally work more effectively.

Optionally, the height h between the semiconductor substrate and the package cover plate is 20 μm to 500 μm. So set up, make the infrared radiation of target object can radiate on the effective pixel structure more effectively.

Optionally, the package cover plate includes a cover plate main body and an infrared absorption structure; the cover plate main body is connected with the semiconductor substrate, and an accommodating cavity is formed between the semiconductor substrate and the cover plate main body; the plurality of effective pixel structures and the plurality of reference pixel structures are positioned in the accommodating cavity; the infrared absorbing structure is located on a side of the cover plate body remote from the semiconductor substrate. In this embodiment, the outer absorption structure is located on a side of the cover plate main body away from the semiconductor substrate, which facilitates processing.

Optionally, the detector further comprises a first metal ring, a second metal ring and a solder ring. The first metal ring is located on the surface of the cover plate body close to one side of the semiconductor substrate. The second metal ring is positioned on the surface of one side of the semiconductor substrate close to the cover plate main body, and the effective pixel structure and the reference pixel structure are surrounded by the second metal ring. The solder ring is connected between the first metal ring and the second metal ring, and a containing cavity is formed among the cover plate main body, the semiconductor substrate and the solder ring. In this embodiment, the solder ring is connected to the first metal ring and the second metal ring, so that the wettability of the solder ring during melting can be improved, and the solder ring can be prevented from diffusing and wetting, thereby preventing the solder ring from contacting the package cover plate.

Optionally, the receiving cavity is a vacuum cavity. In this embodiment, a vacuum cavity (for example, the vacuum cavity may be less than or equal to 0.01 mbar) is formed between the package cover plate and the semiconductor substrate by using the package cover plate, and the plurality of effective pixel structures and the plurality of reference pixel structures are packaged in the containing cavity, so that heat exchange between the effective pixel structures and the reference pixel structures and air is avoided, and the influence of air heat conduction on the response and sensitivity of the effective pixel structures and the reference pixel structures is reduced. In addition, a plurality of effective pixel structures and a plurality of reference pixel structures are packaged in the accommodating cavity, so that the influence of substances such as moisture, dust and the like in the external environment on the effective pixel structures and the reference pixel structures can be avoided, and the service life of the detector is prolonged.

Optionally, the effective pixel structure is the same as the reference pixel structure. So set up, make effective pixel structure and reference pixel structure possess the same thermal conductance, heat capacity and thermal insulation performance, can effectively eliminate the influence of semiconductor substrate temperature and joule temperature rise to effective pixel structure through the reference pixel.

Optionally, the detector further comprises a readout circuit; the plurality of active pixel structures and the plurality of reference pixel structures are electrically connected to a readout circuit.

In a fourth aspect, embodiments of the present invention provide a method for manufacturing a detector. The preparation method comprises the following steps:

forming a plurality of effective pixel structures and a plurality of reference pixel structures on the same side of a semiconductor substrate; orthographic projections of the multiple reference pixel structures on the semiconductor substrate do not overlap with orthographic projections of the multiple effective pixel structures on the semiconductor substrate; the semiconductor substrate includes a readout circuitry; the plurality of reference pixel structures and the plurality of effective pixel structures are electrically connected with the reading circuit;

forming an infrared absorption structure on one side of the packaging cover plate;

the packaging cover plate is combined with the semiconductor substrate to form an accommodating cavity, the plurality of effective pixel structures and the plurality of reference pixel structures are located in the accommodating cavity, and the orthographic projection of the infrared absorption structure on the semiconductor substrate covers the plurality of reference pixel structures and does not cover the plurality of effective pixel structures.

The detector of the third aspect can be prepared by the method for preparing a detector provided by the embodiment of the invention, so that the method has all the beneficial effects of the first aspect, and details are not repeated herein.

Optionally, the bonding the package cover plate and the semiconductor substrate includes: forming a first metal ring on one side of the packaging cover plate; forming a second metal ring on one side of the semiconductor substrate; and forming a solder ring, wherein the solder ring is connected with the first metal ring and the second metal ring so as to combine the packaging cover plate with the semiconductor substrate.

In the scheme, the first metal ring is formed on one side of the packaging cover plate, the second metal ring is formed on one side of the semiconductor substrate, and then the solder ring is formed by coating the solder, so that the wettability of the solder during melting can be improved, the solder can be prevented from diffusing and infiltrating, and the solder is prevented from contacting the packaging cover plate.

Drawings

FIG. 1 is an overall block diagram of a detector according to some embodiments of the invention;

FIG. 2 is a cross-sectional view A-A of FIG. 1;

FIG. 3 is a block diagram of an infrared absorbing structure disposed on a package cover according to some embodiments of the invention;

FIG. 4 is a schematic illustration of the radiation area of an external target object's infrared radiation at the detector focal plane, in accordance with some embodiments of the present invention;

FIG. 5 is a top view of a semiconductor substrate according to some embodiments of the invention;

FIG. 6 is a projection view of an array of active pixels, an array of reference pixels, and an infrared-absorbing structure onto a semiconductor substrate according to some embodiments of the present invention;

FIG. 7 is a block diagram of a probe according to some embodiments of the invention;

FIG. 8 is a block diagram of yet another probe according to some embodiments of the invention;

FIG. 9 is a flow chart of a method of fabricating a package cover plate for a probe according to some embodiments of the present invention;

FIGS. 10-13 are schematic diagrams illustrating a process for fabricating a package cover plate according to some embodiments of the invention;

FIG. 14 is a flow chart of another method of fabricating a package cover plate for a probe according to some embodiments of the present invention;

FIG. 15 is a flow chart of a method of fabricating a detector according to some embodiments of the invention;

FIG. 16 is a flow chart of another method of fabricating a detector according to some embodiments of the invention;

FIGS. 17-23 are schematic diagrams of a process for fabricating a detector according to some embodiments of the invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

FIG. 1 is an overall block diagram of a probe according to some embodiments of the invention. Fig. 2 is a sectional view a-a of fig. 1.

Some embodiments of the present invention provide a probe 100. It will be appreciated that the detector 100 is a sensor that converts incident infrared radiation from a target object into an electrical signal. The present embodiment does not further limit the specific application of the detector 100. The structure of the probe 100 will now be illustrated.

Referring to fig. 1 and 2, a detector 100 includes a semiconductor substrate 101, a plurality of active pixel structures 102, a plurality of reference pixel structures 103, and a package cover plate 200.

A plurality of effective pixel structures 102 are located on one side of the semiconductor substrate 101. The plurality of reference pixel structures 103 and the plurality of effective pixel structures 102 are located on the same side of the semiconductor substrate 101. The orthographic projection of the plurality of reference pixel structures 103 on the semiconductor substrate 101 does not overlap with the orthographic projection of the plurality of effective pixel structures 102 on the semiconductor substrate 101.

The package cover plate 200 is located on a side of the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 away from the semiconductor substrate 101. Illustratively, referring to fig. 1 and 2, a package cover 200 may be coupled to the semiconductor substrate to form the receiving cavity 105. A plurality of reference pixel structures 103 and a plurality of active pixel structures 102 can be located within the receiving cavity 105.

Some embodiments of the invention provide a package cover plate 200 for a probe. The package cover 200 can be used with the probe 100 described above. Of course, it is understood that the package cover 200 can also be applied to other types of detection devices, and is not limited herein.

Referring to fig. 2, the package cover 200 includes a cover body 104 and an infrared absorbing structure 106. The infrared absorbing structure 106 is located on one side of the cover body 104. The infrared absorbing structure 106 serves to absorb infrared radiation directed to the plurality of reference pixel structures 103 from outside the detector 100.

In some examples, referring to fig. 2, a package cover plate 200 is located on a side of the plurality of active pixel structures 102 and the plurality of reference pixel structures 103 away from the semiconductor substrate 101. Wherein, the orthographic projection of the infrared absorption structure 106 on the semiconductor substrate 101 covers the plurality of reference pixel structures 103 and does not cover the plurality of effective pixel structures 102.

Illustratively, the wafer material of the cover plate body 104 includes at least one of silicon (Si) or germanium (Ge). It should be noted that silicon or germanium is used as a main component of the cover plate body 104, the content of elements can reach about 98%, and a small amount of impurities such as iron, aluminum, calcium, etc. can be contained.

In the present embodiment, the infrared radiation of the external target object cannot pass through the infrared absorption structure 106, and therefore cannot act on the reference pixel structure 103, i.e., the reference pixel structure 103 does not respond to the infrared radiation of the external target object. But infrared radiation of an external target object can act on the plurality of effective pixel structures 102 through the cover plate body 104. Through the cooperation of the infrared absorption structure 106 and the reference pixel structure 103, the influence of the temperature and joule temperature rise of the semiconductor substrate 101 on the effective pixel structure 102 is effectively eliminated, and the absolute infrared radiation of the target object can be accurately acquired.

In some embodiments, the infrared absorbing structure 106 is a super-surface absorbing structure.

In some examples, referring to fig. 3, the super surface absorbent structure includes a first metal layer 1063, an insulating dielectric layer 1064, and a second metal layer 1065. The first metal layer 1063 is located on a side of the cover plate body 104 facing away from the semiconductor substrate 101. The insulating dielectric layer 1064 is located on a side of the first metal layer 1063 away from the cap body 104. Second metal layer 1065 is situated on a side of dielectric layer 1064 away from first metal layer 1063. Second metal layer 1065 includes a plurality of spaced apart pillar structures 10651.

For example, the material of the first metal layer 1063 includes at least one of titanium (Ti) and gold (Au).

For example, the material of the second metal layer 1065 includes at least one of titanium (Ti) and gold (Au).

Titanium (Ti) has high loss characteristics in the infrared band, and enhances absorption of infrared radiation, so that the first and

second metal layers

1063 and 1065 can increase the absorption rate of infrared radiation. Gold (Au) has a good reflectivity, and thus is disposed to have a high reflectivity between the first and

second metal layers

1063 and 1065.

For example, the second metal layer 1065 and the first metal layer 1063 are made of the same material. In other examples, second metal layer 1065 may be made of a different material than first metal layer 1063.

Illustratively, the material of the insulating dielectric layer 1064 includes silicon dioxide (SiO)₂) Germanium (Ge), and the like.

The infrared absorbing structure 106 of this embodiment constitutes a periodic array of Metal-Insulator-Metal (MIM) resonant structures. When incident light penetrates through the second metal layer 1065, the first metal layer 1063 functions as a mirror surface capable of reflecting surface plasmon polariton waves excited at the interface between the first metal layer 1063 and the insulating dielectric layer 1064. Meanwhile, the plurality of columnar structures 10651 in second metal layer 1065 also act as a plurality of partial mirror surfaces, reflecting surface plasmon polarized waves excited at the interface between second metal layer 1065 and dielectric layer 1064. The surface plasmon polarization wave excited at the interface between first metal layer 1063 and insulating medium layer 1064 destructively interferes with the surface plasmon polarization wave excited at the interface between second metal layer 1065 and insulating medium layer 1064, thereby exciting the cavity mode. High absorption in the infrared band can be achieved by reasonably designing the geometric parameters of the MIM absorber.

In the present embodiment, the second metal layer 1065 includes a plurality of pillar structures 10651 disposed at intervals. Each columnar structure 10651, the insulating medium layer 1064 and the first metal layer 1063 which are right below the columnar structure 10651 form a resonant cavity structure, and a coupling effect can be generated among a plurality of resonant cavity structures, so that the absorption rate of the infrared absorption structure 106 on the infrared radiation of a target object can be effectively improved. In this case, the shape of the orthogonal projection of the columnar structure 10651 on the insulating dielectric layer 1064 may be a regular pattern or an irregular pattern.

In some embodiments, referring to fig. 3, the thickness n1 of the first metal layer 1063 is greater than the skin depth of the target object's infrared radiation. The skin depth δ is calculated as:

wherein,

is the circumferential ratio;

the operating frequency of the infrared absorbing structure;

is the permeability of first metal layer 1063;

is the conductivity of first metal layer 1063. The skin depth is the depth of the target object infrared radiation entering the first metal layer 1063, and the thickness n1 of the first metal layer 1063 is greater than the skin depth of the target object infrared radiation, so the transmittance of the first metal layer 1063 may be approximately 0, and the infrared radiation is effectively prevented from passing through the infrared absorption structure.

In some embodiments, referring to fig. 3, the orthographic shape of the at least one pillar structure 10651 on the dielectric layer 1064 is a regular pattern. The regular pattern may include, for example, other regular polygons such as circles, triangles, squares, and the like.

When the shape of the orthographic projection of the columnar structure 10651 on the insulating medium layer 1064 is a regular pattern, the influence of the incident angle on the absorption performance of the infrared absorption structure, that is, the sensitivity of the absorption spectrum of the infrared absorption structure to the incident angle can be reduced.

In some embodiments, referring to fig. 3, the at least one pillar 10651 has an orthographic shape on the dielectric layer 1064 in a centrosymmetric pattern. The centrosymmetric pattern may include, for example, a circle, a square, etc. It can be understood that, with such an arrangement, when the orthographic projection shape of the columnar structure 10651 on the insulating medium layer 1064 is a central symmetric pattern, good polarization performance can be achieved, and the influence of the incident angle on the absorption performance of the infrared absorption structure can be reduced.

In some embodiments, referring to fig. 3, the shape of the orthogonal projection of the pillar structures 10651 on the dielectric layer 1064 is circular. The radius R1 of the columnar structure 10651 is 0.25 μm to 2.5 μm. The radius R1 of the columnar structure 10651 is 0.25 μm to 2.5 μm, and the corresponding working wavelength range is 2.5 μm to 25 μm. With this arrangement, the absorption range of the columnar structure 10651 for infrared radiation of the target object can be expanded, and the absorption rate can be improved.

Illustratively, the distance L between two adjacent columnar structures 10651 is equal. The structure of the second metal layer 1065 can be more uniform, which is beneficial to generating the coupling effect.

In some embodiments, referring to fig. 3, the feature size of the pillar structures 10651 is on the order of sub-wavelength, and the plurality of pillar structures 10651 are arranged periodically. Wherein the feature size includes at least one of: the maximum width of columnar structure 10651 in a direction parallel to first metal layer 1063; when the orthographic projection of the columnar structure 10651 on the first metal layer 1063 is a polygon, the length of the longest side of the polygon; alternatively, the maximum height of columnar structures 10651 in a direction perpendicular to first metal layer 1063.

For example, when the shape of the orthographic projection of the columnar structure 10651 on the insulating medium layer 1064 is a circle, the characteristic dimension of the columnar structure 10651 may include at least one of the radius of the orthographic projection and the height of the columnar structure 10651; when the shape of the orthographic projection of the columnar structure 10651 on the insulating dielectric layer 1064 is square, the characteristic dimension of the columnar structure 10651 includes at least one of the side length, the diagonal distance, and the height of the columnar structure 10651 of the orthographic projection.

In the present embodiment, the feature size of the pillar structures 10651 is in the order of sub-wavelength and is periodically arranged, so that the second metal layer 1065 is equivalent to a uniform medium capable of absorbing infrared radiation. And then the electromagnetic property of the second metal layer 1065 can be analyzed by the equivalent medium theory to obtain the electromagnetic property parameters of the second metal layer 1065. Thereafter, by designing the structural characteristics of the pillar structures 10651, such as changing the shape, feature size, and material of the pillar structures 10651, the equivalent permittivity and permeability of the second metal layer 1065 can be controlled and modulated to achieve the equivalent permittivity and equivalent permeability. At this time, the impedance of the second metal layer 1065 is equal to the wave impedance of the electromagnetic wave in vacuum, and impedance matching between the second metal layer 1065 and the surrounding air medium is achieved, so that the incident electromagnetic wave can pass through the second metal layer 1065 without hindrance, and the reflectivity is approximately 0.

In some embodiments, referring to FIG. 3, the thickness n2 of the second metal layer 1065 is generally 0.01 μm to 0.1 μm. That is, the height of each columnar structure is 0.01 μm to 0.1 μm. It will be appreciated that with a thinner second metal layer 1065, the infrared absorbing structure 106 has low loss and low absorption, and the second metal layer 1065 should be as thick as possible for high loss and high absorption. However, for the coupling effect, the second metal layer 1065 should be as thin as possible. Therefore, depending on the absorber operating requirements, a compromise thickness range is taken for the second metal layer 1065: 0.01 μm to 0.1 μm. In this range, the absorption rate and coupling effect of the infrared absorbing structure 106 can meet operational requirements.

In some embodiments, referring to FIG. 3, the thickness n3 of the insulating dielectric layer 1064 is generally 0.1 μm to 1 μm. The thickness of the insulating medium layer 1064 can affect the resonance intensity of the surface plasmon and the light wave between the first metal layer 1063 and the second metal layer 1065, and the influence on the absorption performance is the largest, which is a key factor for controlling the maximum absorption value and the reflection coefficient of the infrared absorption structure. The specific formula is as follows:

wherein,λ _resis the wavelength of the resonance, and is,nis the refractive index of the insulating dielectric layer,dis the thickness of the layer of insulating medium,

is the phase shift of the reflected wave of the second metal layer,

is the phase shift of the reflected wave of the first metal layer,mrepresents the absorption order of the infrared absorbing structure,mare integers.

From the above formula, it can be deduced that, with other parameters being constant,mthe larger, theλThe smaller. I.e. the higher the absorption order of the infrared absorbing structure, the smaller the wavelength of the resonant wave. Increase without changing other parametersnOrd，λAnd also increases. I.e., increasing the refractive index or thickness of the dielectric layer, the wavelength of the resonant wave becomes larger (i.e., red-shifted). Increase without other parameters being changeddThen, thenmIt will also become larger. Namely, the thickness of the insulating medium layer is increased, a multi-order absorption mode of the infrared absorption structure is excited, and light absorption is promoted. In this embodiment, when the thickness n3 of the insulating medium layer 1064 is 0.1 μm to 1 μm, the wavelength and the absorption rate of the resonant wave can satisfy the working requirement.

In some embodiments, referring to fig. 7 and 8, the cover plate body 104 further includes an anti-reflection coating 110. An antireflective coating 110 is located on the surface of the cover body 104 away from the infrared absorbing structure 106. Or on the same side surface of the cover body 104 as the infrared absorbing structure 106. The orthographic projection of the antireflective coating 110 on the cover body 104 does not overlap the orthographic projection of the infrared absorbing structure 106 on the cover body 104.

As an example, the orthographic projection of the antireflection film 110 on the semiconductor substrate 101 covers the plurality of effective pixel structures 102.

For example, referring to fig. 7, an antireflection coating 110 is disposed on a surface of the cover body 104 remote from the infrared absorbing structure 106.

For example, referring to FIG. 8, the antireflection coating 110 and the infrared absorbing structure 106 are located on the same side surface of the cover body 104.

The antireflection coating 110 may be an optical coating with a wide application range, and mainly functions to reduce or eliminate the reflected light from the surface of the main body of the cover plate, thereby increasing the amount of transmitted light and reducing or eliminating the stray light of the system. For example, the material of the antireflection film 110 includes silicon oxide, silicon nitride, titanium dioxide, and the like. For example, the antireflection film 110 may be formed by a chemical vapor deposition method, a sputtering method, or the like. With this arrangement, the reflectance of the cover main body 104 with respect to the infrared radiation of the target object can be reduced, and the transmittance of the infrared radiation of the target object can be improved.

In some embodiments, referring to fig. 4, the height between the semiconductor substrate 101 and the cover plate body 104 is h.

In an example, the value range of h is 20-500 μm. So set up, can make the infrared radiation of target object radiate on the effective pixel structure more effectively.

In some examples, referring to fig. 4 and 6, an orthographic projection of the infrared absorbing structure 106 on the cover plate body 104 on the semiconductor substrate 101 is a first projection 1060, an orthographic projection of the plurality of reference pixel structures 103 on the semiconductor substrate 101 is a second projection 1030, and an orthographic projection of the plurality of active pixel structures 102 on the semiconductor substrate 101 is a third projection 10211. The second projection 1030 is located within the first projection 1060 and the third projection 10211 is located outside the first projection 1060. At any point on the boundary of the first projection 1060, the minimum distance d1 from the boundary of the second projection 1030 is 1.5h to 2.5 h. At any point on the boundary of the first projection 1060, the minimum distance d2 to the boundary of the third projection 10211 is 1.5h to 3.5 h.

In some embodiments, referring to FIG. 5, a plurality of active pixel structures 102 are arranged in a plurality of rows and columns to form an active pixel array 1021. The plurality of reference pixel structures 103 form a first reference pixel array 1031 and a second reference pixel array 1032. The first reference pixel array 1031 is located at one side or both sides of the effective pixel array 1021 in the column direction. The second reference pixel array 1032 is located at one side or both sides of the effective pixel array 1021 in the row direction.

For example, as shown in fig. 5, the first reference pixel array 1031 is located at one side of the effective pixel array 1021 in the column direction; the second reference pixel array 1032 is located on one side of the effective pixel array 1021 in the row direction.

It is understood that the effective pixel element array 1021 has a certain length and width, where the position of each effective pixel element structure 102 on the semiconductor substrate 101 is different, and the temperature of the semiconductor substrate 101 where each effective pixel element structure 102 is located is different. In this embodiment, a plurality of reference pixel structures 103 are made to form a first reference pixel array 1031 and a second reference pixel array 1032. The first reference pixel array 1031 is located at one side or both sides of the effective pixel array 1021 in the column direction, and can offset a temperature difference between the effective pixel structures 102 in each column arranged in the row direction. The second reference pixel array 1032 is located at one side or both sides of the effective pixel array 1021 in the row direction, and can cancel the temperature difference between the effective pixel structures 102 in each row arranged in the column direction. In summary, in the present embodiment, the temperature difference of the effective pixel array 1021 in the row and column directions can be offset by the cooperation of the first reference pixel array 1031 and the second reference pixel array 1032, so as to accurately obtain the absolute infrared radiation of the target object.

In some embodiments, referring to fig. 5, the number of columns of the first reference pixel array 1031 is equal to the number of columns of the effective pixel array 1021; the number of rows of the second reference pixel array 1032 is equal to the number of rows of the effective pixel array 1021.

It is to be understood that the first reference pixel array 1031 of the present embodiment is used to eliminate a temperature difference between columns of the effective pixel structures 102 arranged in the row direction, and the second reference pixel array 1032 is used to eliminate a temperature difference between rows of the effective pixel structures 102 arranged in the column direction. The influence of the temperature of the semiconductor substrate 101 on the effective pixel array 1021 can be effectively eliminated by the cooperation of the first reference pixel array 1031 and the second reference pixel array 1032.

In some embodiments, referring to fig. 5, each column in the first reference pixel array 1031 is arranged side by side with each column in the effective pixel array 1021. Each row in the second reference pixel array 1032 is arranged side by side with each row in the effective pixel array 1021. In the present embodiment, each column in the first reference pixel array 1031 is used to eliminate a temperature difference between columns in which the effective pixel array 1021 is arranged in the row direction. Each row in the second reference pixel array 1032 is used to eliminate the temperature difference between the rows of the effective pixel array 1021 arranged along the column direction, and further the influence of the semiconductor substrate temperature on the effective pixel array is effectively eliminated through the cooperation of the first reference pixel array 1031 and the second reference pixel array 1032.

In some embodiments, referring to fig. 1 and 6, the infrared absorbing structure 106 includes a first portion 1061 and a second portion 1062. An orthographic projection of the first portion 1061 of the infrared absorbing structure 106 on the semiconductor substrate 101 is a first sub-projection 10611. An orthogonal projection of the first reference pixel array 1031 on the semiconductor substrate 101 is a third sub-projection 10311. The third sub-projection 10311 is located within the first sub-projection 10611. At any point on the boundary of the third sub-projection 10311, the minimum distance to the boundary of the first sub-projection 10611 is d 11. The value range of d11 is 1.5-2.5 h. By the arrangement, the first reference pixel array 1031 can be prevented from receiving radiation of an external target object more effectively.

An orthographic projection of the second portion 1062 of the infrared absorbing structure 106 on the semiconductor substrate 101 is a second sub-projection 10621. An orthogonal projection of the second reference pixel array 1032 on the semiconductor substrate 101 is a fourth sub-projection 10321. The fourth sub-projection 10321 is located within the second sub-projection 10621. At any point on the boundary of the fourth sub-projection 10321, the minimum distance to the boundary of the second sub-projection 10621 is d 12. The value range of d12 is 1.5-2.5 h. By the arrangement, the second reference pixel array 1032 can be effectively prevented from receiving radiation of an external target object.

In some embodiments, referring to fig. 6, an orthogonal projection of the effective pixel array 1021 on the semiconductor substrate 101 is a third projection 10211. At any point on the boundary of the first sub-projection 10611, the minimum distance to the boundary of the third sub-projection 10311 is d 11. At any point on the boundary of the first sub-projection 10611, the minimum distance to the boundary of the third projection 10211 is d 21. The value range of d11 is 1.5-2.5 h. The value range of d21 is 1.5-3.5 h.

By the arrangement, the first reference pixel array 1031 can be effectively prevented from receiving radiation of an external target object, the first part 1061 of the infrared absorption structure 106 is prevented from influencing the effective pixel array 1021, and the effective pixel array 1021 can work normally.

With continued reference to fig. 6, at any point on the boundary of the second sub-projection 10621, the minimum distance to the boundary of the fourth sub-projection 10321 is d 12. At any point on the boundary of the second sub-projection 10621, the minimum distance to the boundary of the third projection 10211 is d 22. The value range of d22 is 1.5-3.5 h.

By the arrangement, the two reference pixel arrays 1032 can be effectively prevented from receiving radiation of an external target object, the second part 1062 of the infrared absorption structure 106 is prevented from influencing the effective pixel array 1021, and the effective pixel array 1021 can work normally.

In some embodiments, referring to fig. 7, the cover plate body 104 is connected with the semiconductor substrate 101, and a receiving cavity 105 is formed between the semiconductor substrate 101 and the cover plate body 104. A plurality of active pixel structures 102 and a plurality of reference pixel structures 103 are both located within the receiving cavity 105. The infrared absorbing structure 106 is located on a side of the cover plate body 104 remote from the semiconductor substrate 101.

In this embodiment, the cover plate main body 104 is used to form the accommodating cavity 105 between the cover plate main body 104 and the semiconductor substrate 101, and the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 are encapsulated in the accommodating cavity 105, so that the influence of substances such as moisture and dust in the external environment on the effective pixel structures 102 and the reference pixel structures 103 can be avoided, and the service life of the detector is prolonged.

Illustratively, the containment chamber is a vacuum chamber. In this example, the accommodating chamber 105 is a vacuum chamber, which can prevent the effective pixel structure 102 and the reference pixel structure 103 from exchanging heat with air, and reduce the influence of air heat conduction on the response speed and sensitivity of the effective pixel structure 102 and the reference pixel structure 103. Illustratively, the vacuum level of the receiving chamber 105 is less than 0.01 mbar.

In some embodiments, referring to fig. 1 and 2, the detector 100 further includes a first metal ring 107, a second metal ring 108, and a solder ring 109. The first metal ring 107 is located on a surface of the cover plate body 104 on a side close to the semiconductor substrate 101. A second metal ring 108 is located on the first side of the semiconductor substrate 101, the second metal ring 108 surrounding the effective pixel structure 102 and the reference pixel structure 103. The solder ring 109 is connected between the first metal ring 107 and the second metal ring 108, and the accommodation cavity 105 is formed between the cap body 104, the semiconductor substrate 101, and the solder ring 109.

In some embodiments, referring to fig. 5, the active pixel structure 102 is the same as the reference pixel structure 103. For example, the active pixel structure 102 and the reference pixel structure 103 may be both micro-bridge structures. The micro-bridge structure comprises a bridge deck, piers and bridge arms, wherein the bridge deck comprises an absorption layer for absorbing infrared radiation energy and a thermal resistor layer (usually alpha-Si or vanadium oxide) sensitive to red light, and the piers and the bridge arms have the functions of supporting and electrically connecting. When the infrared radiation is incident on the bridge deck, the resistance value of the thermal resistor layer changes along with the temperature, the resistance value change amount of the thermal resistor layer is detected through a corresponding read Integrated Circuit (ROIC) and converted into a corresponding electrical signal to be output, and therefore the intensity of the external infrared radiation is judged. Meanwhile, the information of the target object can be acquired through the difference of the radiation degrees of the target object and the background information.

In this embodiment, the effective pixel structure 102 is the same as the reference pixel structure 103, so that the effective pixel structure 102 and the reference pixel structure 103 have the same thermal conductivity, thermal capacity, and thermal insulation properties, and therefore, the influence of the temperature and joule temperature rise of the semiconductor substrate 101 on the effective pixel structure 102 can be effectively eliminated by the reference pixel structure 103.

In some embodiments, the detector 100 also includes readout circuitry. In some examples, the readout circuitry is located within the semiconductor substrate 101. In other examples, the readout circuitry may also be disposed outside the semiconductor substrate 101. The plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 are electrically connected to a readout circuit provided outside the semiconductor substrate 101.

The structures of the probe 100 and the package cover 200 of the present embodiment are described above, and the operation principle of the probe 100 of the present embodiment is described next.

In some examples, a temperature sensor is disposed within the housing cavity 105 of the probe. The temperature sensor is used for detecting the junction temperature inside the probe.

The temperature sensor built in the probe 100 can test the junction temperature in the probe 100 in real timeT ₁. The reference pixel structure 103 is subject to internal junction temperatureT ₁And the influence of Joule temperature rise₁The effective pixel structure 102 is subjected to target infrared radiation energy and internal junction temperatureT ₁Joule temperature rise₂By outputting a signal value V₁And V₂The difference between the target and the target can be determined by combining the circuit and subsequent algorithm processing, and the absolute temperature of the target object can be determined as shown in formula 1T ₂。T ₂The schematic formula of (a) may be:

(formula 1)

Wherein,

is the temperature sensing coefficient.

The embodiment of the invention also provides a preparation method of the packaging cover plate 200 of the detector. As shown in fig. 9, the preparation method includes: s1 to S4.

S1, referring to fig. 10, a first metal layer 1063 is formed on one side of the cap body 104. The first metal layer 1063 may be formed by a deposition process or a sputtering process.

S2, referring to fig. 11, an insulating dielectric layer 1064 is formed on the first metal layer 1063 at a side away from the cover plate body 104. The insulating dielectric layer 1064 may be formed on the first metal layer 1063 by a deposition process.

S3, referring to fig. 12, a second metal layer 1065 is formed on the insulating dielectric layer 1064 on a side away from the first metal layer 1063. The second metal layer 1065 may be formed on the insulating dielectric layer 1064 by a deposition process or a sputtering process.

S4, referring to fig. 13, the second metal layer 1065 is patterned to form a plurality of pillar structures 10651.

The method for manufacturing the package cover plate 200 according to this embodiment can manufacture the package cover plate 200 of the detector, and the package cover plate 200 of the detector can improve the influence of the infrared radiation of the target object on the reference pixel structure 103 in the detector, so that the detector can better utilize the reference pixel structure 103 to eliminate the influence of the temperature of the semiconductor substrate 101 on the effective pixel structure 102, and improve the detection accuracy.

For example, a first metal film layer may be formed on one side of the cover plate body 104, an insulating dielectric film layer may be formed on the first metal film layer, and a second metal film layer may be formed on the insulating dielectric film layer. Then, the first metal film layer, the insulating dielectric film layer, and the second metal film layer are patterned, and redundant portions are removed, so that the first metal film layer becomes the first metal layer 1063, the insulating dielectric film layer becomes the insulating dielectric layer 1064, and the second metal film layer becomes the second metal layer 1065. The second metal layer 1065 is patterned to form a plurality of pillar structures 10651.

In some embodiments, referring to fig. 14, the method for preparing the package cover plate 200 further includes:

s0, forming an antireflection film 110 on one side of the cover plate body 104. It should be noted that the antireflection coating 110 may be disposed on the side of the cover body 104 away from the infrared absorbing structure 106, or may be disposed on the same side of the cover body 104 as the infrared absorbing structure 106.

Illustratively, the orthographic projection of the antireflection film 110 on the cover body 104 does not overlap the orthographic projection of the infrared absorbing structure 106 on the cover body 104.

As an example, the orthogonal projection of the antireflection film 110 on the semiconductor substrate 101 can cover a plurality of effective pixel structures 102.

It is understood that after the antireflection film 110 is formed on the surface of the cover plate body 104, the antireflection film 110 is patterned so that the orthographic projection of the antireflection film 110 on the cover plate body 104 does not overlap with the orthographic projection of the infrared absorption structure 106 on the cover plate body 104.

In some examples, the antireflective coating 110 is on a surface of the cover body 104 on a side away from the infrared absorbing structure 106.

In other examples, the antireflection coating 110 may also be located on the same side surface of the cover body 104 as the infrared absorbing structure 106.

In this embodiment, by providing the antireflection film 110, the reflectivity of the package cover plate to the infrared radiation of the external target object can be reduced, and the transmittance can be improved. In some examples, the anti-reflection coating 110 may be formed on the surface of the cover plate body 104 through a deposition process. In other examples, the anti-reflection coating 110 may also be formed on the surface of the cover plate body 104 through a sputtering process.

The embodiment also provides a manufacturing method of the detector 100. As shown in fig. 15, the manufacturing method of the probe 100 includes: S10-S30.

S10, referring to fig. 21, a plurality of effective pixel structures 102 and a plurality of reference pixel structures 103 are formed on the same side of a semiconductor substrate 101; the orthographic projection of the plurality of reference pixel structures 103 on the semiconductor substrate 101 does not overlap with the orthographic projection of the plurality of effective pixel structures 102 on the semiconductor substrate 101. Illustratively, the semiconductor substrate 101 includes a readout circuit. The plurality of reference pixel structures 103 and the plurality of effective pixel structures 102 are each electrically connected to a readout circuit. For example, the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 may be formed on the semiconductor substrate 101 through photolithography and deposition processes.

S20, referring to fig. 19, a package cover 200 is provided, the package cover 200 including at least a cover body 104 and an infrared absorbing structure 106. Illustratively, the infrared absorbing structure 106 may be formed on the cover plate body 104 by sputtering, deposition, and photolithography processes.

S30, combining the cover plate main body 104 with the semiconductor substrate 101 to form a containing cavity 105, the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 being located in the containing cavity 105, and the orthographic projection of the infrared absorption structure 106 on the semiconductor substrate 101 covering the plurality of reference pixel structures 103 and not covering the plurality of effective pixel structures 102, see fig. 2.

In the preparation method of the detector provided in this embodiment, a containing cavity may be formed between the cover plate main body 104 and the semiconductor substrate 101 by using a Wafer Level Package (WLP) technology, and the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 are packaged on the surface of the semiconductor substrate 101, where the surface is located in the containing cavity. The heat exchange between the effective pixel structure 102 and the reference pixel structure 103 and the air is avoided, and the influence of the air heat conduction on the response and the sensitivity of the effective pixel structure 102 and the reference pixel structure 103 is reduced. In addition, the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 are packaged in the accommodating cavity 105, so that the influence of substances such as moisture and dust in the external environment on the effective pixel structures 102 and the reference pixel structures 103 can be avoided, and the service life of the detector 100 is prolonged.

It should be noted that the temperature change of the effective pixel structure 102 is affected not only by the infrared radiation of the target object but also by the temperature of the semiconductor substrate 101 and the joule heating, and the temperature change of the effective pixel structure 102 caused by the temperature of the semiconductor substrate 101 is many times greater than the temperature change of the effective pixel structure 102 caused by the absorption of the infrared radiation of the target object, and therefore, the detection of the infrared radiation of the target object by the detector 100 will be seriously affected by the presence of the temperature of the semiconductor substrate 101. In this embodiment, by providing the reference pixel structure 103, the influence of the temperature of the semiconductor substrate 101 and the joule heating on the effective pixel structure 102 can be eliminated by using the signal difference between the reference pixel structure 103 and the effective pixel structure 102.

In addition, the present embodiment also provides an infrared absorbing structure 106 on the cover body 104. The orthogonal projection of the infrared absorption structure 106 on the semiconductor substrate 101 covers the plurality of reference pixel structures 103 and does not cover the plurality of effective pixel structures 102. In this way, the infrared absorption structure 106 can absorb the infrared radiation of the external target object to the reference pixel structure 103, so that the reference pixel structure 103 has no response to the radiation of the external target object, but does not affect the infrared radiation of the external target object to the effective pixel structure 102. The reference pixel structure 103 is made to be affected only by the temperature and joule heating of the semiconductor substrate 101, and the effective pixel structure 102 is also affected by infrared radiation of an external target object in addition to the temperature and joule heating of the semiconductor substrate 101. The infrared radiation of the external target object can be obtained through the signal difference between the reference pixel structure 103 and the effective pixel structure 102, that is, the influence of the temperature and joule temperature rise of the semiconductor substrate 101 on the effective pixel structure 102 is effectively eliminated by setting the infrared absorption structure 106 and the reference pixel structure 103 in this embodiment, so as to accurately obtain the absolute infrared radiation of the target object.

In some embodiments, as shown in fig. 16, the bonding of the cover plate body 104 to the semiconductor substrate 101 includes: s301 to S303.

S301, a first metal ring 107 is formed on one side of the cap body 104. Illustratively, referring to fig. 17 and 18, the cap body 104 is first provided, and then a first metal ring 107 is formed on the cap body 104 by a photolithography and deposition process.

In some examples, referring to fig. 19, the first metal ring 107 and the infrared absorbing structure 106 are located on opposite sides of the cover body 104. In this example, the first metal ring 107 may be formed before the infrared absorbing structure 106. The reason why the first metal ring 107 is formed first and then the infrared absorption structure 106 is formed is that the infrared absorption structure 106 is complicated, and if the infrared absorption structure 106 is formed on one side of the cover main body 104 and then turned over, and the first metal ring 107 is formed on the opposite side, the infrared absorption structure 106 is easily broken. Thus, in this example, the infrared absorbing structure 106 is not easily broken during the fabrication of the detector.

S302, a second metal ring 108 is formed on one side of the semiconductor substrate 101. For example, referring to fig. 20 and 21, a semiconductor substrate 101 is first provided, and then a second metal ring 108 is formed by a photolithography and deposition process on the side of the semiconductor substrate 101 where the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103 are provided. Referring to fig. 22, a second metal ring 108 surrounds the plurality of effective pixel structures 102 and the plurality of reference pixel structures 103.

S303, forming a solder ring 109, the solder ring 109 connecting the first metal ring 107 and the second metal ring 108 to bond the cover plate body 104 and the semiconductor substrate 101. Illustratively, referring to fig. 23 and 19, in this step, after forming a solder ring 109 on the second metal ring 108, the structure shown in fig. 23 is formed, and then the structure shown in fig. 23 and the structure shown in fig. 19 are connected together through the solder ring 109, so as to form the structure shown in fig. 2.

In this embodiment, the first metal ring 107 is formed on one side of the cover plate body 104, the second metal ring 108 is formed on one side of the semiconductor substrate 101, and the solder ring 109 is formed by coating solder, so as to increase wettability of the solder during melting, prevent the solder from diffusing and wetting, and prevent the solder from contacting the package cover plate.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can appreciate that changes or substitutions within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The packaging cover plate of the detector is characterized in that the detector comprises a plurality of effective pixel structures and a plurality of reference pixel structures; the package cover plate includes:

a cover plate main body;

an infrared absorption structure located at one side of the cover main body; the infrared absorption structure is used for absorbing infrared radiation emitted to the plurality of reference pixel structures from the outside of the detector.

2. The cover plate for packaging a detector according to claim 1, wherein the infrared absorption structure is a super surface absorption structure; the super surface absorbent structure comprises:

the first metal layer is positioned on one side of the cover plate main body;

the insulating medium layer is positioned on one side of the first metal layer, which is far away from the cover plate main body;

the second metal layer is positioned on one side of the insulating medium layer far away from the first metal layer; the second metal layer comprises a plurality of columnar structures arranged at intervals.

3. The cover for packaging a detector according to claim 2, wherein the thickness of the first metal layer is larger than the skin depth of the infrared radiation of the target objectδ；

Wherein,

is the circumferential ratio;

the operating frequency of the infrared absorbing structure;

is the permeability of the first metal layer;

is the conductivity of the first metal layer.

4. The cover plate for packaging a detector according to claim 2, wherein the shape of the orthographic projection of at least one of the columnar structures on the insulating medium layer is a regular pattern; or the orthographic projection shape of at least one columnar structure on the insulating medium layer is a centrosymmetric figure; or the orthographic projection of the columnar structure on the insulating medium layer is circular, and the radius of the columnar structure is 0.25-2.5 microns.

5. The cover plate for packaging a detector according to claim 2, wherein the feature size of the columnar structure is in the order of sub-wavelength, and a plurality of the columnar structures are arranged periodically;

wherein the feature size comprises at least one of: a maximum width of the columnar structure in a direction parallel to the first metal layer; or when the orthographic projection of the columnar structure on the first metal layer is a polygon, the length of the longest edge of the polygon is equal to the length of the longest edge of the polygon; or the maximum height of the columnar structure in the direction perpendicular to the first metal layer.

6. The cover plate for packaging a detector according to claim 2, wherein the material of the cover plate main body comprises at least one of silicon or germanium.

7. The cover plate for packaging the detector according to claim 2, wherein the thickness of the second metal layer is 0.01 μm to 0.1 μm.

8. The cover plate for packaging a detector according to claim 2, wherein the material of the first metal layer comprises at least one of titanium or gold;

9. The cover plate for packaging a detector according to claim 2, wherein the material of the insulating dielectric layer comprises at least one of silicon dioxide or germanium.

10. The cover plate for packaging a detector according to any one of claims 1 to 7, further comprising:

the antireflection film is positioned on the surface, far away from the infrared absorption structure, of the cover plate main body, or is positioned on the same side surface of the cover plate main body with the infrared absorption structure;

the orthographic projection of the antireflection film on the cover plate main body is not overlapped with the orthographic projection of the infrared absorption structure on the cover plate main body.

11. The cover plate for packaging a probe according to claim 10,

and the orthographic projection of the antireflection film on the detected semiconductor substrate covers the plurality of effective pixel structures.

12. A method for preparing a packaging cover plate of a detector is characterized by comprising the following steps:

forming a first metal layer on one side of the cover plate main body;

13. The method of manufacturing according to claim 12, further comprising:

forming an antireflection film on the surface of the cover plate main body; the orthographic projection of the antireflection film on the cover plate main body is not overlapped with the orthographic projection of the first metal layer on the cover plate main body, and the orthographic projection of the antireflection film on the semiconductor substrate covers a plurality of effective pixel structures.

14. A probe, comprising:

a semiconductor substrate;

a plurality of effective pixel structures located at one side of the semiconductor substrate, the plurality of effective pixel structures being used for sensing infrared radiation of a target object;

a plurality of reference pixel structures located on the same side of the semiconductor substrate as the plurality of active pixel structures, the plurality of reference pixel structures being configured to sense a temperature of the semiconductor substrate; orthographic projections of the multiple reference pixel structures on the semiconductor substrate do not overlap with orthographic projections of the multiple effective pixel structures on the semiconductor substrate;

the package cover plate of any one of claims 1-11, located on a side of the plurality of active pixel structures and the plurality of reference pixel structures away from the semiconductor substrate; wherein the orthographic projection of the infrared absorption structure on the semiconductor substrate covers the plurality of reference pixel structures and does not cover the plurality of effective pixel structures.

15. The detector of claim 14, wherein a height between the semiconductor substrate and the package cover plate is h;

the orthographic projection of the infrared absorption structure on the semiconductor substrate is a first projection, the orthographic projection of the multiple reference pixel structures on the semiconductor substrate is a second projection, and the orthographic projection of the multiple effective pixel structures on the semiconductor substrate is a third projection; the second projection is located within the first projection, and the third projection is located outside the first projection;

the minimum distance d1 from any point on the boundary of the first projection to the boundary of the second projection is 1.5 h-2.5 h;

and the minimum distance d2 from any point on the boundary of the first projection to the boundary of the third projection is 1.5 h-3.5 h.

16. The detector of claim 15, wherein the plurality of active pixel structures are arranged in a plurality of rows and columns to form an array of active pixels;

the plurality of reference pixel structures include:

the pixel array comprises a plurality of first reference pixel structures which are arranged in a plurality of columns to form a first reference pixel array; the first reference pixel array is positioned on one side or two sides of the effective pixel array along the column direction;

the plurality of second reference pixel structures are arranged in multiple rows to form a second reference pixel array; the second reference pixel array is positioned on one side or two sides of the effective pixel array along the row direction;

each column in the first reference pixel array is arranged in parallel with each column in the effective pixel array; each row in the second reference pixel array is arranged in parallel with each row in the effective pixel array;

the number of columns of the first reference pixel array is equal to that of the effective pixel array; the number of rows of the second reference pixel array is equal to the number of rows of the effective pixel array; and/or the number of rows of the first reference pixel array is greater than or equal to 10 rows; the number of rows of the second reference pixel array is greater than or equal to 10 columns.

17. The detector of claim 16, wherein the first array of reference pixels is located on one side of the array of active pixels in a column direction; the second reference pixel array is positioned on one side of the effective pixel array along the row direction;

the infrared absorbing structure includes:

the orthographic projection of the first part on the semiconductor substrate is a first sub-projection, and the orthographic projection of the first reference pixel array on the semiconductor substrate is a third sub-projection; the third sub-projection is located within the first sub-projection;

the orthographic projection of the second part on the semiconductor substrate is a second sub-projection, and the orthographic projection of the second reference pixel array on the semiconductor substrate is a fourth sub-projection; the fourth sub-projection is located within the second sub-projection.

18. The detector of claim 17, wherein a height between the semiconductor substrate and the package cover plate is h; the orthographic projection of the effective pixel array on the semiconductor substrate is a third projection;

at any point on the boundary of the first sub-projection, the minimum distance to the boundary of the third sub-projection is d 11; any point on the boundary of the first sub-projection, the minimum distance to the boundary of the third projection being d 21; the value range of d11 is 1.5-2.5 h; the value range of d21 is 1.5-3.5 h;

at any point on the boundary of the second sub-projection, the minimum distance to the boundary of the fourth sub-projection is d 12; any point on the boundary of the second sub-projection, the minimum distance to the boundary of the third projection being d 22; the value range of d12 is 1.5-2.5 h; the value range of d22 is 1.5-3.5 h.

19. The detector of claim 15 or 18, wherein a height h between the semiconductor substrate and the package cover plate is 20 μm to 500 μm.

20. The detector of claim 14, wherein the package cover includes a cover body and an infrared absorbing structure; the cover plate main body is connected with the semiconductor substrate, and an accommodating cavity is formed between the semiconductor substrate and the cover plate main body; the plurality of effective pixel structures and the plurality of reference pixel structures are both positioned in the accommodating cavity; the infrared absorption structure is located on one side of the cover plate main body far away from the semiconductor substrate.

21. The probe of claim 20, further comprising:

a first metal ring located on a surface of the cover plate body on a side close to the semiconductor substrate;

the second metal ring is positioned on the surface of one side, close to the cover plate main body, of the semiconductor substrate, and the second metal ring surrounds the effective pixel structure and the reference pixel structure;

a solder ring connected between the first metal ring and the second metal ring, the receiving cavity being formed between the cover plate body, the semiconductor substrate, and the solder ring.