CN114122036A - Infrared microbolometer detector module and wafer-level packaging method thereof - Google Patents

Infrared microbolometer detector module and wafer-level packaging method thereof Download PDF

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Publication number
CN114122036A
CN114122036A CN202111391673.0A CN202111391673A CN114122036A CN 114122036 A CN114122036 A CN 114122036A CN 202111391673 A CN202111391673 A CN 202111391673A CN 114122036 A CN114122036 A CN 114122036A
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wafer
bonding
infrared
bonding layer
detector module
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倪元浩
王超
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Suzhou Ruixin Microsystem Technology Co ltd
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Suzhou Ruixin Microsystem Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14687—Wafer level processing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/48—Thermography; Techniques using wholly visual means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14618—Containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14627—Microlenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14665—Imagers using a photoconductor layer
    • H01L27/14669—Infrared imagers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14685—Process for coatings or optical elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/1469—Assemblies, i.e. hybrid integration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J2005/0077—Imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
    • G01J2005/106—Arrays

Abstract

The application discloses an infrared microbolometer detector module and a wafer-level packaging method thereof, which comprises the steps of obtaining a wafer-level optical lens wafer with a bonding layer arranged on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units which are arranged in an array; obtaining a hollow-out type support with bonding layers on the upper surface and the lower surface and a substrate with a wafer-level packaged infrared detector chip on the upper surface, wherein the hollow-out area of the hollow-out type support and the infrared detector chip correspond to the lens unit; bonding the wafer-level optical lens wafer and the hollow bracket through the bonding layer; forming a bonding layer on the upper surface of the substrate, and bonding the substrate and the bonded hollow support through the bonding layer to obtain a bonded body; the center axis of the lens unit is aligned with the center of the microbolometer focal plane array; scribing the bonding body to obtain a single pretreatment detector module; and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module. The packaging efficiency and the lens alignment precision can be improved.

Description

Infrared microbolometer detector module and wafer-level packaging method thereof
Technical Field
The application relates to the technical field of infrared detector module packaging, in particular to an infrared microbolometer detector module and a wafer-level packaging method thereof.
Background
Infrared thermal imaging uses a photoelectric technology to detect infrared specific waveband signals of object thermal radiation, converts the signals into images and graphs which can be distinguished by human vision, and can further calculate temperature values.
The conventional Wafer Level Package (WLP) technology for infrared detectors mainly includes performing seal cap bonding and optional RDL (Re-Distribution Layer) on a detector chip at a Wafer Level, and then dicing the detector chip into independent sensors. However, in the existing infrared microbolometer detector module, an infrared detector chip, a lens unit, a shutter stop sheet and the like are assembled together manually, the lens unit needs to be supported and protected by means of a lens mount and a movement frame in the assembling process, and the assembly can be carried out only singly, namely, the single lens unit, the infrared detector chip, the shutter stop sheet and the like are assembled, the single packaging cost is high, the efficiency is very low, and the lens unit is high in alignment eccentricity due to large mechanical assembly errors, if the alignment precision is to be improved, a high-precision assembling device is needed, and the high-precision assembling device inevitably causes high assembling cost; meanwhile, a focusing device is required to be installed, the focal length of the lens and the focal plane array of the microbolometer are calibrated, the existence of the auxiliary tool focusing device leads to the fact that the size of the infrared microbolometer detector module is large, and meanwhile, the packaging cost of the infrared microbolometer detector module is increased.
Therefore, how to solve the above technical problems should be a great concern to those skilled in the art.
Disclosure of Invention
The utility model aims at providing an infrared microbolometer detector module and wafer level packaging method thereof to promote the encapsulation efficiency of infrared microbolometer detector module, reduce the encapsulation cost, promote the camera lens and aim at the precision, reduce the volume of infrared microbolometer detector module simultaneously.
In order to solve the above technical problem, the present application provides a wafer level packaging method for an infrared microbolometer detector module, which includes:
obtaining a wafer-level optical lens wafer with a bonding layer on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units arranged in an array;
obtaining a hollowed-out support with the bonding layer on the upper surface and the bonding layer on the lower surface and a substrate with an infrared detector chip packaged in a WLP wafer level on the upper surface, wherein a hollowed-out area in the hollowed-out support and the infrared detector chip correspond to the lens unit;
bonding the wafer-level optical lens wafer and the upper surface of the hollowed-out support through the bonding layer;
forming the bonding layer on the upper surface of the substrate, and bonding the substrate and the lower surface of the bonded hollow support through the bonding layer to obtain a bonded body; the central axis of the lens unit is aligned with the center of the microbolometer focal plane array;
scribing the bonding body to obtain a single pretreatment detector module;
and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module.
Optionally, before the bonding layer bonds the wafer-level optical lens wafer and the upper surface of the hollow bracket, the method further includes:
and etching the inner wall of the hollow area to increase the roughness of the inner wall of the hollow area.
Optionally, before the bonding layer bonds the wafer-level optical lens wafer and the upper surface of the hollow bracket, the method further includes:
and forming an infrared radiation absorption layer on the etched inner wall of the hollow area.
Optionally, before the infrared radiation absorbing layer is formed on the etched inner wall of the hollow area, the method further includes:
forming an adhesion layer on the etched inner wall of the hollow area;
correspondingly, forming the infrared radiation absorption layer on the etched inner wall of the hollow area comprises:
and forming an infrared radiation absorbing layer on the surface of the adhesion layer.
Optionally, before the bonding layer bonds the wafer-level optical lens wafer and the upper surface of the hollow bracket, the method further includes:
processing the inner wall of the hollow area to form a step-shaped inner wall;
a getter layer is deposited at the horizontal surface of the stepped inner wall.
Optionally, before depositing the getter layer at the horizontal surface of the stepped inner wall, the method further includes:
etching the horizontal surface of the stepped inner wall to form a groove;
accordingly, depositing a getter layer at the horizontal surface of the stepped inner wall comprises:
a getter layer is deposited at the horizontal surface of the stepped inner wall and within the recess.
Optionally, the bonding temperature when the substrate is bonded to the lower surface of the bonded hollow-out support through the bonding layer is lower than the bonding temperature when the wafer-level optical lens wafer is bonded to the upper surface of the hollow-out support through the bonding layer.
Optionally, the obtaining the wafer-level optical lens wafer with the bonding layer on the lower surface includes:
coating an adhesive layer on the lower surface of the wafer-level optical lens wafer;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
coating the adhesive layers on the upper surface and the lower surface of the hollow-out bracket;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and coating the adhesive layer on the upper surface of the substrate.
Optionally, the obtaining the wafer-level optical lens wafer with the bonding layer on the lower surface includes:
forming a metal bonding layer on the lower surface of the wafer-level optical lens wafer; the metal bonding layer comprises a metal layer and a solder block;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
forming the metal bonding layers on the upper surface and the lower surface of the hollow support;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and forming the metal bonding layer on the upper surface of the substrate.
The application also provides an infrared microbolometer detector module, which is obtained by any one of the above-mentioned wafer-level packaging methods.
The wafer-level packaging method for the infrared microbolometer detector module comprises the steps of obtaining a wafer-level optical lens wafer with a bonding layer arranged on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units which are arranged in an array; obtaining a hollowed-out support with the bonding layer on the upper surface and the bonding layer on the lower surface and a substrate with an infrared detector chip packaged in a WLP wafer level on the upper surface, wherein a hollowed-out area in the hollowed-out support and the infrared detector chip correspond to the lens unit; bonding the wafer-level optical lens wafer and the upper surface of the hollowed-out support through the bonding layer; forming the bonding layer on the upper surface of the substrate, and bonding the substrate and the lower surface of the bonded hollow support through the bonding layer to obtain a bonded body; the central axis of the lens unit is aligned with the center of the microbolometer focal plane array; scribing the bonding body to obtain a single pretreatment detector module; and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module.
It can be seen that, the packaging method of the application uses a wafer-level optical lens wafer, which comprises a plurality of lens units arranged in an array, and simultaneously uses a hollow-out type support and a substrate with an infrared detector chip, the infrared detector chip is obtained by WLP wafer-level packaging, the hollow-out area in the hollow-out type support and the infrared detector chip are both corresponding to the lens units, the wafer-level optical lens wafer is firstly bonded with the upper surface of the hollow-out type support, and then the substrate is bonded with the lower surface of the bonded hollow-out type support to obtain a bonded body, therefore, the bonded body comprises a plurality of pre-processing detector modules, the wafer-level integral packaging is realized, hundreds of modules with the lens units can be simultaneously packaged, the packaging efficiency of the infrared micro bolometer detector module is improved, then scribing and shutter installation are carried out to obtain the infrared micro bolometer detector module, the assembly cost is reduced; moreover, the center alignment of the central axis of the lens unit and the center of the microbolometer focal plane array is realized in the wafer-level bonding process, so that the assembly error is smaller, and the alignment precision is high; in addition, the thickness of the hollow-out support is adjusted to enable the infrared detector chip to be located on a focal plane of the lens unit, a focusing device is not needed to be arranged, packaging cost is reduced, the size of the infrared microbolometer detector module is reduced, the center axis of the lens unit is aligned with the center of the microbolometer focal plane array, and imaging definition of the infrared microbolometer detector module is guaranteed.
In addition, this application still provides an infrared microbolometer detector module that has above-mentioned advantage.
Drawings
For a clearer explanation of the embodiments or technical solutions of the prior art of the present application, the drawings needed for the description of the embodiments or prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a wafer level packaging method for an infrared microbolometer detector module according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of the substrate, the hollow bracket, and the wafer-level optical lens in the embodiment of the present application during alignment;
fig. 3 is a flowchart of another wafer level packaging method for an infrared microbolometer detector module according to an embodiment of the present disclosure;
fig. 4 is a schematic structural view of a stepped inner wall of the hollow-out bracket in the embodiment of the present application;
FIG. 5 is a schematic structural view of the hollow-out bracket according to the embodiment of the present application after a groove is formed on the stepped inner wall of the hollow-out bracket;
FIG. 6 is a bottom view of the infrared microbolometer detector module after a groove is formed on the stepped inner wall of the hollow-out bracket in the embodiment of the present application;
fig. 7 to 11 are process flow diagrams of a wafer level packaging method for a middle infrared microbolometer detector module according to the present application;
fig. 12 is a schematic structural view of an infrared microbolometer detector module made in the present application.
Detailed Description
In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As described in the background section, the conventional infrared microbolometer detector module is manually assembled, and can be assembled only singly during assembly, so that the cost of single packaging is high, the efficiency is low, the lens unit has high alignment eccentricity due to large mechanical assembly error, a high-precision assembly device is required to improve the alignment precision, and the high-precision assembly device causes high assembly cost; meanwhile, a focusing device needs to be installed, the existence of the auxiliary tool focusing device leads to the fact that the size of the infrared micro bolometer detector module is large, and meanwhile, the packaging cost of the infrared micro bolometer detector module is increased.
In view of the above, the present application provides a wafer level packaging method for an infrared microbolometer detector module, please refer to fig. 1, which includes:
step S101: and obtaining a wafer-level optical lens wafer with a bonding layer on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units arranged in an array.
A Wafer-Level optical lens Wafer is a Wafer-Level optical element (WLO) and is manufactured by using a Micro-Electro-Mechanical System (MEMS) technology. At present, the WLO technology has been widely applied to the lens of a mobile phone, and in the present application, a wafer-level lens element is applied to the infrared lens of an infrared microbolometer detector module, so as to implement wafer-level packaging of the infrared microbolometer detector module.
The lens unit includes a combination of a plurality of convex lenses and a plurality of concave lenses, and is set as needed.
Step S102: and obtaining a hollowed-out support with the bonding layer on the upper surface and the bonding layer on the lower surface, and a substrate with an infrared detector chip packaged in a WLP wafer level mode on the upper surface, wherein the hollowed-out area in the hollowed-out support and the infrared detector chip correspond to the lens unit.
The material of the hollowed-out support is not limited in the application, as long as the material does not transmit infrared light, the hollowed-out support is preferably silicon oxide generally, the cost is low, the processing is convenient, and the shape of the hollowed-out area includes but is not limited to a rectangle. The arrangement mode of the hollow areas is the same as that of the lens units and is aligned with the lens units one by one.
It should be noted that, the manner of forming the hollow-out region on the hollow-out type support in the present application is not specifically limited, and may be selected by oneself. For example, CNC (Computerized Numerical Control) or sand blasting or other micromachining methods may be used.
The height of the hollow-out support determines the distance between the lens unit and the infrared detector chip, and for better imaging quality, the height of the hollow-out support is consistent with the focal length of the lens unit. If the number of the lenses F is kept unchanged, the height of the hollow support depends on the clear aperture D of the WLO lens selected.
The infrared detector chip, which includes the CMOS readout circuitry, the microbolometers and the lid, is obtained in the form of a WLP wafer level package, the specific packaging process being well known to those skilled in the art and not described in detail herein. The infrared microbolometer detector module in this application utilizes the camera lens unit to assemble the infrared light on infrared detector chip, utilizes the heat effect of infrared light to convert light signal into heat signal, and rethread thermistor converts heat signal into the signal of telecommunication, reads out through CMOS readout circuit at last.
It should be noted that, in the present application, the manner in which the infrared detector chip is disposed on the substrate is not limited, as the case may be. For example, solder bonding or glue bonding may be used.
The substrate is typically a ceramic substrate. The arrangement mode of the infrared detector chips on the substrate is the same as that of the lens units, and the infrared detector chips are aligned with the lens units one by one. In order to facilitate alignment between the hollow area in the hollow support and the infrared detector chip and the lens unit, alignment marks 401 may be respectively disposed on the substrate 301, the hollow support 201, and the wafer-level optical lens wafer 101, as shown in fig. 2.
During bonding, the center axis of the lens unit is aligned with the center of the microbolometer focal plane array through the alignment mark, so that bonding alignment is facilitated, assembly errors of the lens unit are smaller, and imaging quality is higher.
Step S103: and bonding the wafer-level optical lens wafer and the upper surface of the hollowed-out support through the bonding layer.
In the step, the lower surface of the wafer-level optical lens wafer is bonded with the upper surface of the hollow bracket.
Step S104: forming the bonding layer on the upper surface of the substrate, and bonding the substrate and the lower surface of the bonded hollow support through the bonding layer to obtain a bonded body; the central axis of the lens unit is aligned with the center of the microbolometer focal plane array.
The purpose of aligning the central axis of the lens unit with the center of the microbolometer focal plane array is to ensure the imaging definition.
It will be appreciated that the bonding layer on the upper surface of the substrate is located around the infrared detector chip. In this step, the upper surface of the substrate is bonded to the lower surface of the hollow-out support bonded in step S103.
Step S105: and scribing the bonding body to obtain a single pretreatment detector module.
Step S106: and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module.
The bonding method is not limited in this application, and for example, glue bonding, metal solder reflow bonding, thermocompression bonding, and the like are used. The different bonding modes in this application are explained below.
When adopting gluey bonding mode, obtain the wafer level optical lens disc that the lower surface was equipped with the bonding layer, wherein include:
coating an adhesive layer on the lower surface of the wafer-level optical lens wafer;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
coating the adhesive layers on the upper surface and the lower surface of the hollow-out bracket;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and coating the adhesive layer on the upper surface of the substrate.
That is, when bonding with glue, all bonding layers are adhesive layers formed by coating glue.
When metal solder reflow bonding or hot-press welding bonding is adopted, the wafer-level optical lens wafer with the bonding layer arranged on the lower surface is obtained, and the method comprises the following steps:
forming a metal bonding layer on the lower surface of the wafer-level optical lens wafer; the metal bonding layer comprises a metal layer and a solder block;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
forming the metal bonding layers on the upper surface and the lower surface of the hollow support;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and forming the metal bonding layer on the upper surface of the substrate.
That is, when the metal solder reflow bonding or the thermal compression bonding is adopted, all the bonding layers are metal bonding layers, and the metal bonding layers include but are not limited to Cr/Ni/Au, Ti/Au, Ti/Pt/Au. When the bonding layer is a metal bonding layer, the bonding is performed by solder.
In order to improve the packaging stability of the infrared microbolometer detector module, the bonding temperature when the substrate is bonded with the lower surface of the bonded hollow support through the bonding layer is lower than the bonding temperature when the wafer-level optical lens wafer is bonded with the upper surface of the hollow support through the bonding layer. It should be further noted that, when the thermal compression bonding is adopted, the bonding pressure when the substrate is bonded to the lower surface of the bonded hollow-out support through the bonding layer is also lower than the bonding pressure when the wafer-level optical lens wafer is bonded to the upper surface of the hollow-out support through the bonding layer.
When metal solder reflow bonding or hot-press welding bonding is adopted, low-temperature solder, such as tin-bismuth alloy, tin-indium alloy, tin-silver-indium and the like, can be selected when the substrate is bonded with the lower surface of the bonded hollow support through the bonding layer, and high-temperature solder, such as tin-gold alloy, tin-silver-copper alloy and the like, can be selected when the wafer-level optical lens wafer is bonded with the upper surface of the hollow support through the bonding layer.
BCB (Benzocyclobutene), PI (Polyimide), PERMINEX (Benzocyclobutene) and the like can be used for the adhesive bondingTMAnd the like, common wafer level bonding glues. When the adhesive bonding is adopted, in order to improve the packaging stability, the curing temperature of the bonding adhesive in the step S104 is lower than that in the stepThe curing temperature of the bonding glue in step S103, or, when the same bonding glue is used in both steps, the bonding temperature in step S104 is lower than the bonding temperature in step S103, and accordingly, the bonding time in step S104 is longer than the bonding time in step S103.
The packaging method of the application uses a wafer-level optical lens wafer which comprises a plurality of lens units arranged in an array manner, a hollow-out type support and a substrate with an infrared detector chip are used at the same time, the infrared detector chip is obtained by WLP wafer-level packaging, a hollow-out area in the hollow-out type support and the infrared detector chip are both corresponding to the lens units, the wafer-level optical lens wafer is firstly bonded with the upper surface of the hollow-out type support, then the substrate is bonded with the lower surface of the bonded hollow-out type support to obtain a bonded body, therefore, the bonded body comprises a plurality of pretreatment detector modules, the wafer-level integral packaging is realized, hundreds of modules with the lens units can be packaged at the same time, the packaging efficiency of the infrared micro-bolometer detector module is improved, then scribing and shutter separation blade installation are carried out, and the infrared micro-bolometer detector module is obtained, the assembly cost is reduced; moreover, the center alignment of the central axis of the lens unit and the center of the microbolometer focal plane array is realized in the wafer-level bonding process, so that the assembly error is smaller, and the alignment precision is high; in addition, the thickness of the hollow-out support is adjusted to enable the infrared detector chip to be located on a focal plane of the lens unit, a focusing device is not needed to be arranged, packaging cost is reduced, the size of the infrared microbolometer detector module is reduced, the center axis of the lens unit is aligned with the center of the microbolometer focal plane array, and imaging definition of the infrared microbolometer detector module is guaranteed.
On the basis of the foregoing embodiment, in an embodiment of the present application, before bonding the wafer-level optical lens wafer and the upper surface of the hollow bracket through the bonding layer, the method for wafer-level packaging of an infrared microbolometer detector module further includes:
and etching the inner wall of the hollow area to increase the roughness of the inner wall of the hollow area.
The inner wall of the hollow area can be etched by using hydrofluoric acid, BOE (Buffered Oxide Etch), and other etching liquids.
The inner wall of the hollowed-out area can be a smooth surface before etching, the roughness of the inner wall of the hollowed-out area is increased through etching, the mirror reflection of the inner wall of the hollowed-out area is changed into diffuse reflection, the infrared radiation is prevented from being irradiated onto the infrared detector chip for the second time, and the interference of ambient light on the imaging of the microbolometer is reduced.
Further, in order to absorb the excess infrared radiation on the inner wall of the hollow area, before the bonding layer bonds the wafer-level optical lens wafer and the upper surface of the hollow bracket, the method further includes:
and forming an infrared radiation absorption layer on the etched inner wall of the hollow area.
The infrared radiation absorbing layer can be made of black silicon, black gold or other infrared absorbing materials, and the infrared radiation absorbing layer can be formed by an evaporation method or a sputtering method.
Further, in order to enhance the adhesion between the infrared radiation absorbing layer and the etched inner wall of the hollow area, before the infrared radiation absorbing layer is formed on the etched inner wall of the hollow area, the method further includes:
forming an adhesion layer on the etched inner wall of the hollow area;
correspondingly, forming the infrared radiation absorption layer on the etched inner wall of the hollow area comprises:
and forming an infrared radiation absorbing layer on the surface of the adhesion layer.
The material of the adhesion layer can be titanium or chromium.
Referring to fig. 3, fig. 3 is a flowchart of another wafer level packaging method for an infrared microbolometer detector module according to an embodiment of the present application, including:
step S201: and obtaining a wafer-level optical lens wafer with a bonding layer on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units arranged in an array.
Step S202: and obtaining a hollowed-out support with the bonding layer on the upper surface and the bonding layer on the lower surface, and a substrate with a wafer-level packaged infrared detector chip on the upper surface, wherein the hollowed-out area in the hollowed-out support and the infrared detector chip correspond to the lens unit.
Step S203: and etching the inner wall of the hollow area to form a step-shaped inner wall.
The structure of the stepped inner wall is schematically shown in fig. 4, the inner wall has only one step, and the getter layer is located on the horizontal surface 205 of the stepped inner wall. The manufacturing mode of the stepped inner wall can adopt modes such as CNC or sand blasting processing. The stepped inner wall can be obtained by machining or sand blasting together with the hollow area.
Step S204: a getter layer is deposited at the horizontal surface of the stepped inner wall.
The material of the getter layer can be selected from low-temperature activated getters, such as titanium, titanium-zirconium alloy, titanium-zirconium-vanadium, zirconium-vanadium-iron, titanium-zirconium, a small amount of lanthanide alloy, and the like.
In the present application, the deposition manner of the getter layer is not limited, as the case may be. For example, the hard mask is used by an evaporation method, a sputtering method, or the like.
Step S205: and bonding the wafer-level optical lens wafer and the upper surface of the hollowed-out support through the bonding layer.
Step S206: and forming the bonding layer on the upper surface of the substrate, and bonding the substrate and the lower surface of the bonded hollow support through the bonding layer to obtain a bonded body, wherein the center axis of the lens unit is aligned with the center of the microbolometer focal plane array.
Step S207: and scribing the bonding body to obtain a single pretreatment detector module.
Step S208: and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module.
In the above embodiments, the infrared detector chip has been subjected to wafer level packaging, that is, vacuum packaging, but in order to reduce the diffusion of external gas into the infrared detector chip, in this embodiment, the getter layer is deposited to keep the gas outside the infrared detector chip at a certain vacuum degree, so as to prevent the external gas from diffusing into the infrared detector chip and reduce the heat loss caused by air heat conduction.
Further, in order to make the infrared microbolometer detector module be applicable to the scene that the vacuum degree requirement is higher, before depositing the getter layer at the horizontal surface of notch cuttype inner wall, still include:
processing the horizontal surface of the stepped inner wall to form a groove;
accordingly, depositing a getter layer at the horizontal surface of the stepped inner wall comprises:
a getter layer is deposited at the horizontal surface of the stepped inner wall and within the recess.
The schematic diagram of the stepped inner wall after the groove is formed is shown in fig. 5, the getter layer 206 is further deposited in the groove 207, and the existence of the groove 207 increases the deposition area of the getter layer, so that the gettering effect is enhanced. At this time, the bottom view of the infrared microbolometer detector module is shown in fig. 6, and the infrared detector chip 302 is located within the getter layer 206.
In order to avoid damage and contamination to the lens unit during the packaging process, before the bonding layer bonds the wafer-level optical lens wafer and the upper surface of the hollow bracket, the method further includes:
coating a lens protection medium layer on the upper surface of the wafer-level optical lens wafer;
correspondingly, after obtaining a single pre-processing detector module by scribing the bonding body, the method further includes:
and removing the lens protection medium layer.
It should be noted that, in the present application, the material of the lens protection medium layer is not limited and can be selected by itself. For example, the lens protection medium layer may be made of a high temperature resistant polymer such as PI (Polyimide), PBI (polybenzimidazole), or an adhesive tape made of PI.
The lens protection medium layer can be removed by adopting a dry cleaning method and/or a wet cleaning method, and the application is not particularly limited.
On the basis of the foregoing embodiment, in an embodiment of the present application, after the shutter stop is installed on the preprocessing detector module, the method further includes:
and installing a lens protection sheet on the pretreatment detector module to protect the lens from being polluted.
The packaging process of the infrared microbolometer detector module is explained below by taking a thermocompression bonding manner as an example.
Step 1, depositing a metal layer on the upper surface of the silicon oxide support plate 201' by using methods such as evaporation, sputtering or electroplating, and the like, and patterning the metal layer by etching, Lift-off stripping and the like to form a metal bonding layer 202, as shown in fig. 7.
Step 2, hollowing a rectangular structure on the silicon oxide supporting plate 201' by adopting a CNC (computerized numerical control) processing mode to obtain a hollow-out type support 201; the hollow bracket 201 is put into hydrofluoric acid etching liquid, the roughness of the inner wall of the hollow bracket is changed, an adhesion layer is formed on the inner wall of the hollow bracket, and then an infrared radiation absorbing layer 203 is evaporated or sputtered on the surface of the adhesion layer, as shown in fig. 8.
Step 3, coating a lens protective medium layer 104 on the upper surface of the wafer-level optical lens wafer 101, depositing a metal layer on the lower surface of the wafer-level optical lens wafer 101, patterning the metal layer by etching or Lift-off stripping and the like to form a metal bonding layer 202, and then performing fusion bonding on the wafer-level optical lens wafer 101 and the hollow bracket 201 through a high-temperature solder 204, as shown in fig. 9.
Step 4, welding the wafer-level packaged infrared detector chip 302 on the upper surface of the ceramic substrate 301 by using a reflow soldering method, forming a metal bonding layer 202 on the upper surface of the ceramic substrate 301, and then performing fusion bonding on the ceramic substrate 301 and the hollow bracket through the low-temperature solder 208 to complete the overall packaging, so as to obtain a bonded body, as shown in fig. 10, wherein the infrared detector chip 302 includes a CMOS readout circuit 303, a microbolometer focal plane array 304 and a sealing cover 305. The temperature and pressure of the fusion bonding process in this step are lower than those in the bonding in step 3.
In the packaging process, alignment marks on a wafer-level optical lens wafer, a ceramic substrate and a hollow bracket need to be calibrated so as to ensure that the center of a focal plane array of the microbolometer is aligned with the central axis of the lens and ensure clear imaging.
And 5, scribing the bonding body according to the size of the chip, removing the lens protection medium layer, mounting structures such as a shutter blocking piece 102 and a lens protection piece 103 and the like to protect the lens from being polluted and perform blocking piece operation, and obtaining a single infrared microbolometer detector module as shown in fig. 12 as shown in fig. 11.
The application also provides an infrared microbolometer detector module, which is obtained by the wafer-level packaging method of the infrared microbolometer detector module in any embodiment.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The infrared microbolometer detector module and the packaging method thereof provided by the application are described in detail above. The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

Claims (10)

1. A wafer level packaging method for an infrared microbolometer detector module is characterized by comprising the following steps:
obtaining a wafer-level optical lens wafer with a bonding layer on the lower surface, wherein the wafer-level optical lens wafer comprises a plurality of lens units arranged in an array;
obtaining a hollow-out type support with the bonding layer on the upper surface and the bonding layer on the lower surface, and a substrate with an infrared detector chip packaged in wafer level WLP (wafer level package) on the upper surface, wherein the hollow-out area in the hollow-out type support and the infrared detector chip both correspond to the lens unit,
bonding the wafer-level optical lens wafer and the upper surface of the hollowed-out support through the bonding layer;
forming the bonding layer on the upper surface of the substrate, and bonding the substrate and the lower surface of the bonded hollow support through the bonding layer to obtain a bonded body; the central axis of the lens unit is aligned with the center of the microbolometer focal plane array;
scribing the bonding body to obtain a single pretreatment detector module;
and installing a shutter stop sheet on the pretreatment detector module to obtain the infrared microbolometer detector module.
2. The method for wafer level packaging of an infrared microbolometer detector module as recited in claim 1, wherein, prior to bonding the wafer level optical lens wafer to the upper surface of the hollowed-out support via the bonding layer, further comprising:
and etching the inner wall of the hollow area to increase the roughness of the inner wall of the hollow area.
3. The method for wafer level packaging of an infrared microbolometer detector module as recited in claim 2, wherein, prior to bonding the wafer level optical lens wafer to the upper surface of the hollowed-out support via the bonding layer, further comprising:
and forming an infrared radiation absorption layer on the etched inner wall of the hollow area.
4. The wafer-level packaging method of an infrared microbolometer detector module according to claim 3, wherein before the step of forming the infrared radiation absorbing layer on the etched inner wall of the hollowed-out region, the method further comprises:
forming an adhesion layer on the etched inner wall of the hollow area;
correspondingly, forming the infrared radiation absorption layer on the etched inner wall of the hollow area comprises:
and forming an infrared radiation absorbing layer on the surface of the adhesion layer.
5. The method for wafer level packaging of an infrared microbolometer detector module as recited in claim 1, wherein, prior to bonding the wafer level optical lens wafer to the upper surface of the hollowed-out support via the bonding layer, further comprising:
processing the inner wall of the hollow area to form a step-shaped inner wall;
a getter layer is deposited at the horizontal surface of the stepped inner wall.
6. The infrared microbolometer detector module wafer-level packaging method of claim 5, further comprising, prior to depositing a getter layer at the horizontal surface of the stepped inner wall:
etching the horizontal surface of the stepped inner wall to form a groove;
accordingly, depositing a getter layer at the horizontal surface of the stepped inner wall comprises:
a getter layer is deposited at the horizontal surface of the stepped inner wall and within the recess.
7. The wafer-level packaging method of the infrared microbolometer detector module as claimed in claim 1, wherein the bonding temperature when the substrate is bonded with the lower surface of the bonded hollowed-out support through the bonding layer is lower than the bonding temperature when the wafer-level optical lens wafer is bonded with the upper surface of the hollowed-out support through the bonding layer.
8. The method for wafer level packaging of an infrared microbolometer detector module according to any one of claims 1 to 7, wherein the obtaining of the wafer level optical lens wafer having the bonding layer provided on the lower surface thereof comprises:
coating an adhesive layer on the lower surface of the wafer-level optical lens wafer;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
coating the adhesive layers on the upper surface and the lower surface of the hollow-out bracket;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and coating the adhesive layer on the upper surface of the substrate.
9. The method for wafer level packaging of an infrared microbolometer detector module according to any one of claims 1 to 7, wherein the obtaining of the wafer level optical lens wafer having the bonding layer provided on the lower surface thereof comprises:
forming a metal bonding layer on the lower surface of the wafer-level optical lens wafer; the metal bonding layer comprises a metal layer and a solder block;
correspondingly, obtaining the fretwork type support that upper surface and lower surface all were equipped with bonding layer includes:
forming the metal bonding layers on the upper surface and the lower surface of the hollow support;
correspondingly, the forming the bonding layer on the upper surface of the substrate includes:
and forming the metal bonding layer on the upper surface of the substrate.
10. An infrared microbolometer detector module, characterized in that it is obtained by the wafer level packaging method of an infrared microbolometer detector module according to any one of claims 1 to 9.
CN202111391673.0A 2021-11-19 2021-11-19 Infrared microbolometer detector module and wafer-level packaging method thereof Pending CN114122036A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115356792A (en) * 2022-06-27 2022-11-18 杭州海康微影传感科技有限公司 Manufacturing method of optical lens wafer and manufacturing method of lens imaging module
WO2024067713A1 (en) * 2022-09-29 2024-04-04 杭州海康微影传感科技有限公司 Wafer-level packaging structure, manufacturing method therefor, and sensor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115356792A (en) * 2022-06-27 2022-11-18 杭州海康微影传感科技有限公司 Manufacturing method of optical lens wafer and manufacturing method of lens imaging module
CN115356792B (en) * 2022-06-27 2023-12-08 杭州海康微影传感科技有限公司 Manufacturing method of optical lens wafer and manufacturing method of lens imaging module
WO2024067713A1 (en) * 2022-09-29 2024-04-04 杭州海康微影传感科技有限公司 Wafer-level packaging structure, manufacturing method therefor, and sensor

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