CN116443804A - Wafer-level packaged infrared detector and manufacturing method thereof - Google Patents
Wafer-level packaged infrared detector and manufacturing method thereof Download PDFInfo
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- CN116443804A CN116443804A CN202310459810.2A CN202310459810A CN116443804A CN 116443804 A CN116443804 A CN 116443804A CN 202310459810 A CN202310459810 A CN 202310459810A CN 116443804 A CN116443804 A CN 116443804A
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- 229920002120 photoresistant polymer Polymers 0.000 claims description 32
- 230000004888 barrier function Effects 0.000 claims description 16
- 238000005530 etching Methods 0.000 claims description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 14
- 229910052710 silicon Inorganic materials 0.000 claims description 14
- 239000010703 silicon Substances 0.000 claims description 14
- 239000012790 adhesive layer Substances 0.000 claims description 12
- 230000003213 activating effect Effects 0.000 claims description 10
- 239000007772 electrode material Substances 0.000 claims description 9
- 230000000149 penetrating effect Effects 0.000 claims description 6
- 238000011049 filling Methods 0.000 claims description 4
- 238000001994 activation Methods 0.000 abstract description 66
- 230000001965 increasing effect Effects 0.000 abstract description 14
- 238000004806 packaging method and process Methods 0.000 abstract description 7
- 238000007725 thermal activation Methods 0.000 abstract description 5
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- 230000008569 process Effects 0.000 description 16
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- 238000007738 vacuum evaporation Methods 0.000 description 7
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Classifications
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/0032—Packages or encapsulation
- B81B7/0035—Packages or encapsulation for maintaining a controlled atmosphere inside of the chamber containing the MEMS
- B81B7/0038—Packages or encapsulation for maintaining a controlled atmosphere inside of the chamber containing the MEMS using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00261—Processes for packaging MEMS devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00261—Processes for packaging MEMS devices
- B81C1/00277—Processes for packaging MEMS devices for maintaining a controlled atmosphere inside of the cavity containing the MEMS
- B81C1/00285—Processes for packaging MEMS devices for maintaining a controlled atmosphere inside of the cavity containing the MEMS using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
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- 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
- G01J5/02—Constructional details
- G01J5/08—Optical arrangements
- G01J5/0875—Windows; Arrangements for fastening thereof
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Computer Hardware Design (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
The application relates to the field of semiconductors, and discloses an infrared detector of wafer level package and a manufacturing method thereof, wherein the infrared detector comprises the following steps: the sensor comprises a sensor wafer, a window wafer, a getter and a metal activation electrode, wherein the window wafer is provided with a groove surrounded by a wall body, and the getter is arranged on the end face and/or the inner side face of the wall body; the sensor wafer and the window wafer are bonded to form a vacuum cavity, and the metal activation electrode is arranged in an area outside the vacuum cavity; the getter is connected to the metal activated electrode or electrically connected through a conductive medium. The metal activated electrode only heats the getter, so that the problems of MEMS structure thermal failure, detector packaging failure, solder overflow ball and the like caused by thermal activation are avoided. The getter is arranged on the end face and/or the inner side face of the upper wall of the window wafer, so that the area of the getter can be increased on the premise of not increasing the size of the detector, and the vacuum degree in the vacuum cavity can be better maintained; the light emergent surface of the window wafer can be used for setting an optical window, so that the performance of the detector is improved.
Description
Technical Field
The present disclosure relates to the field of semiconductors, and more particularly, to an infrared detector packaged at a wafer level and a method for manufacturing the same.
Background
The wafer-level packaged infrared detector is a detector prepared by bonding a window wafer and a sensor wafer through a wafer-level packaging technology, and a vacuum cavity with high air tightness is formed in the detector so as to ensure that the sensor can work normally. In order to avoid the vacuum degree in the cavity from decreasing in the use process, a getter is usually arranged in the cavity and on the light-emitting surface of the window wafer. During packaging, H is adsorbed by the surface of the getter exposed to the atmosphere 2 O、CO 2 And hydrocarbon, etc., the getter needs to be activated in order to ensure the vacuum in the chamber.
The current ways to activate the getter are high temperature heat activation and thermal radiation activation. The high-temperature heating activation mode has the following defects that firstly, the high temperature easily causes the problems of thermal failure, detector packaging failure and the like of a MEMS (Micro-Electro-Mechanical System) structure; secondly, the solder in bonding has high fluidity at high temperature, and is easy to generate overflow balls, and can influence the detector. The thermal radiation activation mode is activated by utilizing thermal radiation, is a non-contact activation mode, and has the defects of low efficiency, difficulty in accurately controlling an activation area and easiness in damaging a detector.
Therefore, how to solve the above technical problems should be of great interest to those skilled in the art.
Disclosure of Invention
The purpose of the application is to provide an infrared detector of wafer level package and a manufacturing method thereof, so as to avoid the occurrence of MEMS structure thermal failure, detector package failure and solder overflow ball during activation, and simultaneously improve activation efficiency and accuracy.
In order to solve the above technical problem, the present application provides an infrared detector of wafer level package, including:
sensor wafer, window wafer, getter and metal activated electrode;
the window wafer has a groove surrounded by the wall body;
the getter is arranged on the end face and/or the inner side face of the wall body;
the sensor wafer and the window wafer are bonded to form a vacuum cavity, and the metal activation electrode is arranged in an area outside the vacuum cavity;
the getter is electrically connected to the metal activation electrode or through a conductive medium.
Optionally, the bonding adopts a solder bonding mode, the metal activated electrode is arranged on the surface of the sensor wafer and is electrically connected with the solder layer, and the getter is electrically connected with the solder layer.
Optionally, the getter includes an end surface portion and an inner side surface portion, wherein the end surface portion and the inner side surface portion are connected to each other, and the getter is electrically connected to the solder layer.
Optionally, the metal activation electrode is disposed on an outer side surface of the wall, and the metal activation electrode is electrically connected with the getter by penetrating through the wall.
Optionally, the getter is disposed on an inner side surface of the wall and an end surface of the wall, and a gap is left between the getter and the solder layer disposed on the end surface of the wall.
Optionally, when the getter is disposed on the end face of the wall, the surfaces of the getter and the solder layer, which are in contact with the end face of the wall, are the same horizontal plane.
Optionally, when the end face of the wall body is provided with the getter, the thickness of the solder layer is greater than that of the getter, the blind pixel structure area is arranged in a preset area of the sensor wafer, and the preset area is a projection area of the getter located on the end face on the sensor wafer.
Optionally, the getter is disposed on at least two end surfaces and/or at least two inner side surfaces of the wall body.
Optionally, an optical window is disposed on the window wafer.
The application also provides a manufacturing method of the infrared detector of the wafer level package, which comprises the following steps:
preparing a window wafer with a groove; the groove is surrounded by a wall body;
preparing a getter on the end face and/or the inner side face of the wall body on the window wafer;
preparing a metal activated electrode outside the vacuum cavity; the getter is electrically connected with the metal activated electrode or through a conductive medium;
and bonding the window wafer and the sensor wafer to form the vacuum cavity, and activating the getter through the metal activation electrode in an electric activation mode to obtain the infrared detector of the wafer level package.
Optionally, preparing the metal activated electrode includes:
preparing the metal activation electrode on the surface of the sensor wafer; wherein the metal activated electrode is connected with the solder layer formed by bonding after bonding.
Optionally, preparing the metal activated electrode includes:
forming a through hole penetrating through the thickness of the wall body on the wall body;
and sequentially preparing an adhesion layer and a barrier layer in the through hole, filling a metal activated electrode material, and arranging the metal activated electrode on the outer side surface of the wall body.
Optionally, preparing the window wafer with the recess includes:
forming patterned photoresist on the light-emitting surface of the window wafer to be processed;
and etching the window wafer to be processed by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
Optionally, preparing the window wafer with the recess includes:
bonding the light emergent surface of the window wafer to be processed with the bare silicon wafer;
forming patterned photoresist on the surface of the bare silicon wafer, which is away from the window wafer to be processed;
and etching the bare silicon wafer by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
Optionally, before preparing the solder layer on the end face of the wall of the window wafer, the method further includes:
preparing an adhesion layer on the end face of the wall body;
and preparing a barrier layer in a local area of the adhesive layer, wherein the barrier layer corresponds to the solder layer.
The application provides an infrared detector of wafer level package, includes: sensor wafer, window wafer, getter and metal activated electrode; the window wafer is provided with a groove surrounded by a wall body, and the getter is arranged on the end face and/or the inner side face of the wall body; the sensor wafer and the window wafer are bonded to form a vacuum cavity, and the metal activation electrode is arranged in an area outside the vacuum cavity; the getter is electrically connected to the metal activation electrode or through a conductive medium.
Therefore, the metal activation electrode for electrically activating the getter is arranged in the application, and only the getter is heated during activation, so that the whole temperature of the detector is prevented from rising, the problems of MEMS structure thermal failure, detector packaging failure, solder overflow ball and the like caused by thermal activation are avoided, and multiple activations can be realized to ensure the vacuum degree in the vacuum cavity. The metal activation electrode can directionally activate the getter, so that the activation efficiency can be improved, and the activation accuracy can be improved. In addition, the getter is arranged on the end face and/or the inner side face of the upper wall of the window wafer, so that the area of the getter can be increased on the premise of not increasing the size of the detector, the vacuum degree in the vacuum cavity is better maintained, and the normal operation of the detector is ensured; meanwhile, the area of the getter occupying the light-emitting surface of the window wafer can be avoided, and the light-emitting surface of the window wafer can be fully used for setting an optical window, so that the transmissivity of infrared radiation of a required wave band is enhanced, stray light is reduced, and the performance of the detector is further improved.
In addition, the application also provides a manufacturing method with the advantages.
Drawings
For a clearer description of embodiments of the present application or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description that follow are only some embodiments of the present application, and that other drawings may be obtained from these drawings by a person of ordinary skill in the art without inventive effort.
Fig. 1 is a schematic structural diagram of an infrared detector of a wafer level package according to an embodiment of the present application;
FIG. 2 is a top view of a window of an infrared detector of a wafer level package according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of another wafer level packaged infrared detector according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of another wafer level packaged infrared detector according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of another embodiment of an infrared detector with wafer level package;
FIG. 6 is a top view of a window of an infrared detector of another wafer level package according to an embodiment of the present application;
FIG. 7 is a flowchart of a method for fabricating an infrared detector of wafer level package according to an embodiment of the present disclosure;
in the figure: 1. sensor wafer 2, window wafer, 3, MEMS sensor, 4, blind pixel structure area, 5, wall, 6, solder layer, 7, vacuum cavity, 8, getter, 9, metal activation electrode, 10, optical window.
Detailed Description
In order to provide a better understanding of the present application, those skilled in the art will now make further details of the present application with reference to the drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
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 other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
As described in the background art, the current mode of activating the getter comprises high-temperature heating activation and thermal radiation activation, and the high-temperature heating activation is easy to cause the problems of thermal failure of MEMS structure, detector packaging failure, solder overflow ball and the like; thermal radiation activation has the disadvantages of low efficiency, difficulty in precisely controlling the activation area and vulnerability of the detector.
In view of this, the present application provides an infrared detector of wafer level package, please refer to fig. 1 to 5, comprising:
a sensor wafer 1, a window wafer 2, a getter 8 and a metal activation electrode 9;
the window wafer 2 is provided with a groove surrounded by a wall body 5;
the getter 8 is arranged on the end face and/or the inner side face of the wall body 5;
the sensor wafer 1 and the window wafer 2 are bonded to form a vacuum cavity 7, and the metal activation electrode 9 is arranged in an area outside the vacuum cavity 7;
the getter 8 is electrically connected to the metal activation electrode 9 or through a conductive medium.
The getter 8 is electrically connected directly to the metal activation electrode 9, and indirectly via a conductive medium. The conductive medium may be a solder layer 6 bonding the window wafer 2 and the sensor wafer 1.
The window wafer 2 with the grooves and the sensor wafer 1 are bonded to form a vacuum cavity 7 of the detector. A MEMS sensor 3 is provided in the cavity on the upper surface of the sensor wafer 1 (the surface opposite to the light-emitting surface of the window wafer 2) for detecting infrared radiation.
The window wafer 2 and the sensor wafer 1 are bonded through a solder layer 6, and the solder layer 6 is positioned on the end face of the wall body 5. The inner side surface of the wall body 5 is the surface close to one side of the vacuum cavity 7.
In order to enhance the adhesion effect between the solder layer 6 and the end face of the wall 5, an adhesion layer may be further provided between the end face of the wall 5 and the solder layer 6. Further, in order to prevent the intermetallic compound from forming between the solder layer 6 and the adhesion layer, which affects the film properties, a barrier layer may be provided between the adhesion layer and the solder layer 6.
The location of the metal activation electrode 9 is not limited in this application, and may be any appropriate. The following description will be made separately.
In one embodiment of the present application, as shown in fig. 1 to 3, the metal activation electrode 9 is disposed on the surface of the sensor wafer 1 and is electrically connected to the solder layer 6, and the getter 8 is electrically connected to the solder layer 6.
The metal activation electrode 9 is provided on the upper surface of the sensor wafer 1 in a region other than the vacuum chamber 7.
When the metal activation electrode 9 is provided on the upper surface of the sensor wafer 1, the manner of providing the getter 8 is not particularly limited, and may be set by itself.
Alternatively, as an embodiment, as shown in fig. 1, the getter 8 is disposed on an end surface of the wall 5. The width (thickness) of the wall body 5 where the getter 8 is located is far greater than the width of the solder layer 6, so that the getter 8 is arranged on the end face of the wall body 5, the getter 8 is connected with the solder layer 6, the solder layer 6 is in contact connection with the metal activation electrode 9 as shown in fig. 2, the solder layer 6 is composed of a metal material, and therefore current can flow to the getter 8 through the solder layer 6, and when the current flows through the getter 8, electric energy is converted into heat energy, and the getter 8 is heated, so that the activation of the getter 8 is realized.
A certain space is reserved between the getter 8 and the upper surface of the sensor wafer 1, the space is communicated with the vacuum cavity 7, and the getter 8 can adsorb gas molecules in the vacuum cavity 7 through the space, so that the vacuum degree of the cavity is ensured.
Alternatively, as another embodiment, as shown in fig. 3, the getter 8 includes an end surface portion provided on the wall 5 and an inner side surface portion of the wall 5, which are connected to each other, wherein the getter 8 provided on the end surface of the wall 5 is electrically connected to the solder layer 6.
Compared with fig. 1, in the wafer-level packaged infrared detector shown in fig. 3, besides the getter 8 is arranged on the end face of the wall body 5, the getter 8 is arranged on the inner side face of the wall body 5, the area of the getter 8 is increased, and the ratio of the getter 8 is increased, so that the vacuum degree of the vacuum cavity 7 is better maintained.
For the wafer-level packaged infrared detector shown in fig. 1 and 3, in order to enhance the adhesion effect between the getter 8 and the end face of the wall 5, an adhesion layer may be further disposed between the end face of the wall 5 and the getter 8.
In other embodiments of the present application, as shown in fig. 4 to 5, the metal activation electrode 9 is disposed on the outer side surface of the wall 5, and the metal activation electrode 9 is electrically connected to the getter 8 by penetrating through the wall 5. The outer side surface of the wall body 5 is opposite to the inner side surface, namely the surface far away from the vacuum cavity 7.
When the metal activation electrode 9 is disposed on the outer side surface of the wall 5, the manner of disposing the getter 8 is not particularly limited, and may be self-disposed.
Alternatively, as an embodiment, as shown in fig. 4, the getter 8 is disposed on the inner side of the wall 5. At this time, the width of the wall 5 is equal to the width of the solder layer 6.
The wall body 5 is provided with an electrode through hole, the electrode through hole transversely penetrates through the wall body 5, electrode materials are filled in the electrode through hole to form a metal activation electrode 9, the metal activation electrode 9 is in contact with the getter 8, and the metal activation electrode 9 supplies power to the getter 8, so that the electrical activation of the getter 8 can be realized.
Alternatively, as another embodiment, as shown in fig. 5, the getter 8 is disposed on the inner side surface of the wall 5 and the end surface of the wall 5, and a gap is left between the getter 8 and the solder layer 6 disposed on the end surface of the wall 5.
Compared with fig. 4, in the infrared detector of the wafer level package shown in fig. 5, besides the getter 8 is disposed on the inner side surface of the wall 5, the getter 8 is disposed on the end surface, the area of the getter 8 is increased, and the ratio of the getter 8 is increased, so as to better maintain the vacuum degree of the vacuum cavity 7. The width of the wall 5 is now much larger than the width of the solder layer 6.
For the wafer-level packaged infrared detector shown in fig. 5, in order to enhance the adhesion effect between the getter 8 and the end face of the wall 5, an adhesion layer may be further disposed between the end face of the wall 5 and the getter 8.
For the wafer-level packaged infrared detector shown in fig. 4 and 5, in order to enhance the adhesion effect between the getter 8 and the wall 5, an adhesion layer may be further provided between the end surface of the wall 5 and the getter 8, and between the inner side surface and the getter 8.
In this embodiment, the metal activation electrode 9 for electrically activating the getter 8 is provided, and only the getter 8 is heated during activation, so as to avoid the overall temperature rise of the detector, thereby avoiding the problems of thermal failure of the MEMS structure, package failure of the detector, solder overflow ball and the like caused by thermal activation, and realizing multiple activations to ensure the vacuum degree in the vacuum cavity 7. The metal activation electrode 9 can be used for directionally activating the getter 8, so that the activation efficiency can be improved, and the activation accuracy can be improved. In addition, the getter 8 is arranged on the end face and/or the inner side face of the upper wall body 5 of the window wafer 2, so that the area of the getter 8 can be increased on the premise of not increasing the size of the detector, the vacuum degree in the vacuum cavity 7 can be better maintained, and the normal operation of the detector is ensured; meanwhile, the getter 8 can be prevented from occupying the area on the light-emitting surface of the window wafer 2, and the light-emitting surface of the window wafer 2 can be fully used for arranging the optical window 10, so that the transmissivity of infrared radiation of a required wave band is enhanced, stray light is reduced, and the performance of the detector is further improved.
On the basis of the above embodiment, in one embodiment of the present application, as shown in fig. 1, 3 and 5, when the getter 8 is disposed on the end surface of the wall 5, the surfaces of the getter 8 and the solder layer 6, which are respectively in contact with the end surface of the wall 5, are the same level, so that the getter 8 and the solder layer 6 can share the adhesive layer, and the respective adhesive layers do not need to be prepared, which can reduce one-time photolithography and etching processes, simplify the process steps, improve the production efficiency and reduce the production cost.
When the getter 8 and the surface of the solder layer 6 in contact with the end face are at the same level, the thickness of the solder layer 6 is greater than the thickness of the getter 8, so that there is a gap between the getter 8 and the underlying sensor wafer 1 after bonding.
On the basis of any of the above embodiments, in one embodiment of the present application, as shown in fig. 1, 3 and 5, when the getter 8 is disposed on the end surface of the wall 5, the thickness of the solder layer 6 is greater than the thickness of the getter 8, and the blind pixel structure area 4 is disposed in a preset area of the sensor wafer 1, where the preset area is a projection area of the getter 8 located on the end surface on the sensor wafer 1.
The blind pixel structure area 4 has a circuit function, the structure of the blind pixel structure area is consistent with the pixel structure of the MEMS sensor 3, the blind pixel structure area can be used as a reference pixel, the pixel parameter change caused by the temperature change of the detector is compensated, the pixel imaging of the MEMS sensor 3 is ensured to be stable, and the influence of the temperature is reduced as much as possible. The blind pixel structure area 4 needs to be protected from light and cannot receive infrared radiation so as to play a role of a reference pixel.
In the related art, the blind pixel structure region 4 is disposed in a region of the sensor wafer 1 corresponding to the light-emitting surface of the window wafer 2, and an opaque film layer is plated on the light-emitting surface to shade the blind pixel structure region 4. The blind pixel structure region 4 is arranged below the getter 8, and the getter 8 plays a role in absorbing gas and maintaining vacuum degree and shading the blind pixel structure region 4, namely shading the blind pixel structure region 4 directly by the getter 8 without additionally plating a shading film layer on the light-emitting surface of the window wafer 2; and because the blind pixel structural region 4 is closer to the getter 8, the shading effect on the blind pixel structural region 4 is better, and the performance of the detector is improved.
In order to ensure the suction effect, the vacuum degree of the vacuum cavity 7 is better maintained, and in one embodiment of the application, the getter 8 is arranged on at least two end surfaces and/or at least two inner side surfaces of the wall body 5.
The wall 5 has four end faces and four inner side faces.
For the wafer level packaged infrared detector of fig. 1, getters 8 may be disposed on two, three, or four sides of wall 5. A top view of the window of the wafer level packaged detector is shown in fig. 6 when getters 8 are provided at the four end faces. For the wafer level packaged infrared detector of fig. 4, getters 8 may be disposed on two, three, or four interior sides of wall 5. For the wafer level packaged infrared detector shown in fig. 3 and 5, getters 8 may be disposed on two, three, or four inner sides and end faces of wall 5.
On the basis of any one of the above embodiments, in one embodiment of the present application, an optical window 10 is disposed on the window wafer 2 in the wafer-level packaged infrared detector, so as to improve the transmittance of infrared radiation.
Because the getter 8 is arranged on the end face and/or the inner side face of the wall body 5, the light-emitting surface of the window wafer 2 can be fully used for arranging the optical window 10, thereby enhancing the transmissivity of infrared radiation of a required wave band, reducing stray light and further improving the performance of the detector.
In summary, the wafer-level packaged infrared detector in the present application has the following advantages:
1. the electrical activation of the getter is realized by arranging the metal activation electrode on the side wall of the sensor wafer or the wall body, only the getter is heated, the overall temperature of the detector is low, the problems of thermal failure of the MEMS structure, packaging failure of the detector, solder overflow ball and the like caused by thermal activation can be avoided, and multiple activations can be realized to ensure the vacuum degree in the cavity;
2. the getter is arranged on the end face of the wall body, firstly, the getter and the solder layer are positioned on the same plane, the adhesive layers of the getter and the solder layer can be prepared at the same time, the step-by-step process is not needed, one-time photoetching and etching processes can be reduced, the process steps are simplified, the production efficiency is improved, and the production cost is reduced; secondly, compared with the getter arranged at the bottom of the deep cavity (the light-emitting surface of the window wafer), the getter positioned at the end face of the wall body is closer to the sensor wafer, so that a better shading effect can be achieved on a blind pixel structure area on the sensor wafer, and the performance of the detector is improved; thirdly, after the getter is transferred from the bottom of the deep cavity to the end face of the wall body, the area of the bottom of the deep cavity can be fully used for setting an optical window, so that the transmissivity of infrared radiation of a required wave band is enhanced, stray light is reduced, and the performance of the detector is further improved;
3. the getter is arranged on the side wall of the wall body, so that the area of the getter can be increased on the premise of not increasing the size of the detector, the vacuum degree in the vacuum cavity can be maintained better, and the normal operation of the detector is ensured.
The application further provides a method for manufacturing the infrared detector of the wafer level package, please refer to fig. 7, which includes:
step S101: preparing a window wafer with a groove; the groove is surrounded by a wall body.
As one embodiment, preparing a window wafer having a recess includes:
step S1011a: and forming patterned photoresist on the light-emitting surface of the window wafer to be processed.
And coating photoresist on the light-emitting surface of the window wafer to be processed, exposing and developing the photoresist, etching the exposed area to form a groove, and forming a wall body in the area protected by the photoresist.
When the getter is arranged on the end face of the wall body, the width of the wall body where the getter is arranged is larger. By changing the mask plate used in the photoresist patterning process, the area of the wafer of the window to be processed, which is protected by the photoresist, is changed, and then the wall body with one or more widened sides is obtained.
Step S1012a: and etching the window wafer to be processed by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
As another embodiment, preparing a window wafer having a recess includes:
step S1011b: bonding the light emergent surface of the window wafer to be processed with the bare silicon wafer;
step S1012b: forming patterned photoresist on the surface of the bare silicon wafer, which is away from the window wafer to be processed;
step S1013b: and etching the bare silicon wafer by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
Etching is stopped until the surface of the bare silicon chip, which is contacted with the window wafer to be processed, exposes an optical window on the window wafer.
When the getter is arranged on the end face of the wall body, the width of the wall body where the getter is arranged is larger. By changing the mask plate used in the photoresist patterning process, the area of the wafer of the window to be processed, which is protected by the photoresist, is changed, and then the wall body with one or more widened sides is obtained.
Step S102: and preparing a getter on the end face and/or the inner side face of the upper wall of the window wafer.
And (3) performing gluing and photoresist patterning treatment on the light emergent surface of the window wafer to expose the area where the getter is required to be manufactured. The getter is manufactured by a magnetron sputtering method and a vacuum evaporation process.
In order to enhance the adhesion between the getter and the wall, an adhesion layer may be formed in the area where the getter is required to be formed before the getter is formed.
It should be noted that, before preparing the getter, the method further comprises the step of preparing a solder layer on the end face of the wall body.
Preferably, before the preparing the solder layer on the end face of the window wafer, the method further comprises:
preparing an adhesion layer on the end face of the wall body;
and preparing a barrier layer in a local area of the adhesive layer, wherein the barrier layer corresponds to the solder layer.
The adhesion layer can strengthen the adhesion effect between the solder layer and the wall body, and the barrier layer can prevent the solder and the adhesion layer from forming intermetallic compounds to influence the performance of the film layer.
When the getter is provided on the end face of the wall, the surface of the getter and the solder layer contacting the end face are in the same horizontal plane, and the adhesive layer on the end face can be manufactured at one time.
Step S103: preparing a metal activated electrode outside the vacuum cavity; the getter is electrically connected to the metal activation electrode or through a conductive medium.
As one embodiment, preparing a metal activated electrode includes: preparing the metal activation electrode on the surface of the sensor wafer; wherein the metal activated electrode is electrically connected with the solder layer formed by bonding after bonding.
The metal activated electrode can be manufactured by a magnetron sputtering method or a vacuum evaporation process.
As another embodiment, preparing a metal activated electrode includes:
forming a through hole penetrating through the thickness of the wall body on the wall body;
and sequentially preparing an adhesion layer and a barrier layer in the through hole, filling a metal activated electrode material, and arranging the metal activated electrode on the outer side surface of the wall body.
The metal activated electrode can be manufactured by a magnetron sputtering method and a vacuum evaporation process.
The adhesion layer can enhance the adhesion between the electrode material and the inner wall of the through hole, and the blocking layer can prevent the electrode material from reacting with the adhesion layer to form intermetallic compounds.
Step S104: and bonding the window wafer and the sensor wafer to form the vacuum cavity, and activating the getter through the metal activation electrode in an electric activation mode to obtain the infrared detector of the wafer level package.
The method also comprises the following steps before bonding: MEMS sensors are fabricated on a sensor wafer.
The metal activation electrode for electrically activating the getter is arranged in the detector manufactured in the embodiment, and only the getter is heated during activation, so that the whole temperature of the detector is prevented from rising, the problems of MEMS structure thermal failure, detector packaging failure, solder overflow ball and the like caused by thermal activation are avoided, and multiple activations can be realized to ensure the vacuum degree in the vacuum cavity. In addition, the getter is arranged on the end face and/or the inner side face of the upper wall of the window wafer, so that the area of the getter can be increased on the premise of not increasing the size of the detector, the vacuum degree in the vacuum cavity is better maintained, and the normal operation of the detector is ensured; meanwhile, the area of the getter occupying the light-emitting surface of the window wafer can be avoided, and the light-emitting surface of the window wafer can be fully used for setting an optical window, so that the transmissivity of infrared radiation of a required wave band is enhanced, stray light is reduced, and the performance of the detector is further improved.
The fabrication process of the infrared detector of different wafer level packages will be described in detail below.
Example 1: for the wafer level package infrared detector shown in fig. 1
Step 1, preparing a window wafer with grooves, wherein the preparation method comprises the following two modes:
(1) performing gluing and photoresist patterning on the light emergent surface of the window wafer, etching the exposed area after the patterning to form a groove, forming a wall body in the area protected by the photoresist, and changing the mask plate used in the photoresist patterning to change the area protected by the photoresist so as to obtain a wall body with one or more widened sides;
(2) the light emergent surface of the window wafer is tightly combined with another bare silicon wafer through silicon-silicon bonding, and photoetching and etching are carried out on the back surface of the bare silicon wafer, so that an optical window on the window wafer is exposed, and a groove is formed; likewise, by changing the mask used in the photoresist patterning process, a wall with one or more widened sides can be obtained;
step 2, performing gluing and photoresist patterning treatment on the light emergent surface of the window wafer to expose the end surface of the wall, and preparing an adhesion layer on the wall by using a magnetron sputtering or evaporation method to strengthen the adhesion between the metal film layer and the wall;
step 3, gluing and photoresist patterning are carried out on the light emergent surface of the window wafer, so that an adhesive layer of a region to be plated with solder is exposed, a barrier layer and a solder layer are sequentially prepared on the adhesive layer through a magnetron sputtering or evaporation process, and the barrier layer is used for preventing the solder layer and the adhesive layer from forming intermetallic compounds so as to influence the performance of the film layer;
step 4, performing gluing and photoresist patterning treatment on the light-emitting surface of the window wafer, and plating a getter on the inner side of the solder layer of the widened wall body through a magnetron sputtering or vacuum evaporation process;
step 5, gluing and patterning are carried out on one side of the sensor wafer provided with the MEMS structure, and a metal activation electrode is prepared through a magnetron sputtering or vacuum evaporation process;
and 6, bonding the sensor wafer and the window wafer, and activating the getter in an electrically activated mode.
Example 2: for the wafer level package infrared detector shown in fig. 4
Step 1, preparing a window wafer with grooves, wherein the preparation method comprises the following two modes:
(1) photoetching and etching are carried out on the light emergent surface of the window wafer, the exposed area after the patterning is etched to form a groove, and the area protected by photoresist forms a wall body;
(2) the light emergent surface of the window wafer is tightly combined with another bare silicon wafer through silicon-silicon bonding, and photoetching and etching are carried out on the back surface of the bare silicon wafer, so that an optical window on the window wafer is exposed, and a groove is formed;
step 2, photoetching and etching a wall body on one side to form a through hole which transversely penetrates through the wall body; sequentially preparing an adhesion layer and a barrier layer in the through hole through magnetron sputtering and vacuum evaporation, and finally filling electrode materials to form an activated electrode, wherein the adhesion layer is used for enhancing the adhesion between the electrode materials and the inner wall of the through hole, and the barrier layer is used for preventing the electrode materials and the adhesion layer from reacting to form intermetallic compounds;
step 3, performing gluing and photoresist patterning treatment on the light emergent surface of the window wafer to expose the end face of the wall body, and sequentially preparing an adhesive layer, a barrier layer and solder in the exposed area by using a magnetron sputtering or evaporation method;
step 4, performing gluing and photoresist patterning treatment on the light emergent surface of the window wafer to expose the inner side wall of the wall body with the active electrode, and sequentially preparing an adhesive layer and a getter on the inner side wall of the wall body through a magnetron sputtering or vacuum evaporation process;
and 5, bonding the sensor wafer and the window wafer, and activating the getter in an electric activation mode.
Example 3: infrared detector for wafer level package as shown in FIG. 5
In this embodiment, the manufacturing process refers to the manufacturing process of the above example 2, and is different in that in the step 1, a widened wall is obtained by changing the mask used in the photoresist patterning process, a metal activated electrode is manufactured on the widened wall, a getter is manufactured by widening an end face and an inner side face of the wall, the getter on the inner side face is in contact with the activated electrode, and the getter on the end face of the wall is located inside the solder layer and is not in contact with the solder layer.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other.
The wafer-level packaged infrared detector provided by the application and the manufacturing method thereof are described in detail above. Specific examples are set forth herein to illustrate the principles and embodiments of the present application, and the description of the examples above is only intended to assist in understanding the methods of the present application and their core ideas. It should be noted that it would be obvious to those skilled in the art that various improvements and modifications can be made to the present application without departing from the principles of the present application, and such improvements and modifications fall within the scope of the claims of the present application.
Claims (15)
1. An infrared detector of a wafer level package, comprising:
a sensor wafer (1), a window wafer (2), a getter (8) and a metal activation electrode (9);
the window wafer (2) is provided with a groove surrounded by a wall body (5);
the getter (8) is arranged on the end face and/or the inner side face of the wall body (5);
the sensor wafer (1) and the window wafer (2) are bonded to form a vacuum cavity (7), and the metal activation electrode (9) is arranged in an area outside the vacuum cavity (7);
the getter (8) is electrically connected to the metal activation electrode (9) or through a conductive medium.
2. The wafer level packaged infrared detector as set forth in claim 1, wherein the bonding is by solder bonding, the metal activation electrode (9) is disposed on the surface of the sensor wafer (1) and is electrically connected to the solder layer (6), and the getter (8) is electrically connected to the solder layer (6).
3. The wafer-level packaged infrared detector as set forth in claim 2, wherein the getter (8) comprises an end face portion provided separately to the wall (5) and an inner side portion of the wall (5) connected to each other, wherein the getter (8) provided to the end face of the wall (5) is electrically connected to the solder layer (6).
4. The wafer level packaged infrared detector as set forth in claim 1, wherein the metal activation electrode (9) is disposed on an outer side surface of the wall (5), the metal activation electrode (9) being electrically connected to the getter (8) by penetrating the wall (5).
5. The wafer level packaged infrared detector as set forth in claim 4, wherein the getter (8) is disposed on an inner side surface of the wall (5) and an end surface of the wall (5), and a gap is left between the getter (8) and the solder layer (6) disposed on the end surface of the wall (5).
6. The wafer-level packaged infrared detector as set forth in claim 1, wherein when the getter (8) is disposed on the end face of the wall (5), surfaces of the getter (8) and the solder layer (6) respectively in contact with the end face of the wall (5) are in the same horizontal plane.
7. The wafer-level packaged infrared detector as set forth in claim 1, wherein when the getter (8) is provided on an end surface of the wall (5), the thickness of the solder layer (6) is greater than the thickness of the getter (8), and the blind pixel structure region (4) is provided in a predetermined region of the sensor wafer (1), the predetermined region being a projection region of the getter (8) located on the end surface on the sensor wafer (1).
8. The wafer-level packaged infrared detector as claimed in claim 1, wherein the getters (8) are provided on at least two end faces and/or at least two inner sides of the wall (5).
9. The wafer level packaged infrared detector according to any of claims 1 to 8, wherein an optical window (10) is provided on the window wafer (2).
10. The manufacturing method of the infrared detector of the wafer level package is characterized by comprising the following steps of:
preparing a window wafer with a groove; the groove is surrounded by a wall body;
preparing a getter on the end face and/or the inner side face of the wall body on the window wafer;
preparing a metal activated electrode outside the vacuum cavity; the getter is electrically connected with the metal activated electrode or through a conductive medium;
and bonding the window wafer and the sensor wafer to form the vacuum cavity, and activating the getter through the metal activation electrode in an electric activation mode to obtain the infrared detector of the wafer level package.
11. The method of fabricating a wafer level packaged infrared detector as recited in claim 10, wherein preparing a metal activated electrode comprises:
preparing the metal activation electrode on the surface of the sensor wafer; wherein the metal activated electrode is connected with the solder layer formed by bonding after bonding.
12. The method of fabricating a wafer level packaged infrared detector as recited in claim 10, wherein preparing a metal activated electrode comprises:
forming a through hole penetrating through the thickness of the wall body on the wall body;
and sequentially preparing an adhesion layer and a barrier layer in the through hole, filling a metal activated electrode material, and arranging the metal activated electrode on the outer side surface of the wall body.
13. The method of fabricating a wafer level packaged infrared detector as recited in claim 10, wherein preparing a window wafer having grooves comprises:
forming patterned photoresist on the light-emitting surface of the window wafer to be processed;
and etching the window wafer to be processed by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
14. The method of fabricating a wafer level packaged infrared detector as recited in claim 10, wherein preparing a window wafer having grooves comprises:
bonding the light emergent surface of the window wafer to be processed with the bare silicon wafer;
forming patterned photoresist on the surface of the bare silicon wafer, which is away from the window wafer to be processed;
and etching the bare silicon wafer by taking the patterned photoresist as a mask to form a groove, thereby obtaining the window wafer.
15. A method of fabricating an infrared detector as claimed in any one of claims 10 to 14, further comprising, prior to preparing a solder layer on an end face of the wall of the window wafer:
preparing an adhesion layer on the end face of the wall body;
and preparing a barrier layer in a local area of the adhesive layer, wherein the barrier layer corresponds to the solder layer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310459810.2A CN116443804A (en) | 2023-04-21 | 2023-04-21 | Wafer-level packaged infrared detector and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310459810.2A CN116443804A (en) | 2023-04-21 | 2023-04-21 | Wafer-level packaged infrared detector and manufacturing method thereof |
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| CN116443804A true CN116443804A (en) | 2023-07-18 |
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| CN202310459810.2A Pending CN116443804A (en) | 2023-04-21 | 2023-04-21 | Wafer-level packaged infrared detector and manufacturing method thereof |
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