WO2006114005A1 - A method for packaging integrated sensors - Google Patents
A method for packaging integrated sensors Download PDFInfo
- Publication number
- WO2006114005A1 WO2006114005A1 PCT/CH2005/000234 CH2005000234W WO2006114005A1 WO 2006114005 A1 WO2006114005 A1 WO 2006114005A1 CH 2005000234 W CH2005000234 W CH 2005000234W WO 2006114005 A1 WO2006114005 A1 WO 2006114005A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- substrate
- section
- buffer structure
- mold
- sensor
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 42
- 238000004806 packaging method and process Methods 0.000 title description 11
- 239000000758 substrate Substances 0.000 claims abstract description 38
- 239000000463 material Substances 0.000 claims abstract description 28
- 239000000126 substance Substances 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 238000001721 transfer moulding Methods 0.000 claims abstract description 4
- 238000005266 casting Methods 0.000 claims description 14
- 239000012528 membrane Substances 0.000 claims description 9
- 239000012530 fluid Substances 0.000 claims description 5
- 238000002844 melting Methods 0.000 claims description 5
- 230000008018 melting Effects 0.000 claims description 5
- 238000001704 evaporation Methods 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 description 9
- 238000000465 moulding Methods 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000005253 cladding Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/56—Encapsulations, e.g. encapsulation layers, coatings
- H01L21/565—Moulds
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
- G01D11/24—Housings ; Casings for instruments
- G01D11/245—Housings for sensors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6845—Micromachined devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/14—Casings, e.g. of special material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/14—Housings
- G01L19/141—Monolithic housings, e.g. molded or one-piece housings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/128—Microapparatus
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/4805—Shape
- H01L2224/4809—Loop shape
- H01L2224/48091—Arched
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/481—Disposition
- H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
- H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
- H01L2924/181—Encapsulation
- H01L2924/1815—Shape
Definitions
- the present invention relates to a method for manufacturing a sensor device comprising a substrate with an integrated sensitive structure, in particular using molding techniques. It also relates to a method for manu- facturing a substance sensor, in particular a gas sensor or a humidity sensor.
- a substrate e.g. a semiconductor substrate
- a substrate e.g. a semiconductor substrate
- advantages such as small size and the possibility to apply advanced manufacturing techniques as used in semiconduc- tor technology.
- further functionality such as amplifiers, D/A- converters, calibration circuitry, etc.
- a buffer structure is integrated on a surface of the substrate.
- the buffer structure covers and/or surrounds the sensor's sensitive structure and ex- tends away from the surface, i.e. it projects away from the surface.
- a mold is provided for casting the housing.
- the mold defines an interior space to receive a hardening material and has a section extending into or bordering the interior space.
- the substrate is placed in the mold, and the parts are arranged such that the section abuts against the buffer structure.
- the hardening material is introduced into the mold and hardened for forming the housing. After removing the mold, the access opening formed by the section extends from the surface of the housing to the buffer structure.
- a direct access opening extending all the way, to the sensitive structure is formed, e.g. by removing the buffer structure at least partially and/or by providing it with one or more suitable openings.
- the buffer structure is a frame surrounding the sensitive structure and having a central opening for providing access to the same. While casting the housing, the section abuts against the frame and prevents material from entering the central opening.
- the frame forms a tight seal between the substrate and the inward projecting sec- tion while introducing the hardening material into the mold.
- a substance sensor i.e. a sensor that is able to detect a substance in a fluid, such as a gas sensor or a humidity sensor.
- the substance sensor comprises a substrate with an integrated sensitive structure.
- This object is achieved by providing a mold defining an interior space and having a section extending into said interior space.
- the substrate is placed in the mold, wherein the parts are arranged such that the section extends towards the sensitive structure.
- the section may e.g. touch the sensitive structure directly, or it may be separated from the same by a buffer structure.
- Ma- terial is introduced into the mold for casting the housing over the substrate. After hardening the material at least partially, the section is removed, thereby forming an access opening from the surface of the housing towards the sensitive structure.
- Fig. 1 shows a semiconductor substrate with integrated sensor
- Fig. 2 shows the device of Fig. 1 after the addition of the buffer structure
- Fig. 3 shows the device of Fig. 2 after placement on a lead frame
- Fig. 4 shows the device of Fig. 3 after transfer molding
- Fig. 5 shows a sectional view through the mold
- Fig. 6 shows a sectional view during casting
- Fig. 7 shows a sectional view of the final sensor device
- Fig. 8 shows a substrate with a second embodiment of the buffer structure
- Fig. 9 shows the second embodiment of the device while casting the housing
- Fig. 10 shows the second embodiment of the device after casting the housing
- Fig. 11 shows the second embodiment of the device after removal of the buffer structure
- Fig. 12 shows a third embodiment of the device after casting and removal of the buffer structure
- Fig. 13 shows a fourth embodiment of the device where the sensitive structure is mounted on a membrane .
- Figure 1 shows a device comprising a semiconductor substrate 1.
- a sensitive structure 2, evaluation circuitry 3 and contact pads 4 are integrated on a top surface Ia of semiconductor substrate 1.
- substrate 1 can be a simple carrier for sensor 2 without active circuitry, in which case it may also be of a non- semiconductor material.
- the device of Fig. 1 may e.g. be a flow sen- sor, such as it is described in reference to Fig. 5 of US 6 729 181, in which case reference number 2 generally designates the membrane carrying the heater and tempera- ture sensors. It may also be a sensor for detecting substances, in particular humidity, such as it is described in US 6 690 569, in which case reference number 2 generally designates the measuring layer of the device, or it may be some other type of gas detector or, more generally, substance detector for detecting a substance in a fluid.
- the sensor may e.g. also be a light sensor, in which case reference number 2 generally designates the light sensitive area of the device, or it may be a pres- sure sensor, in which case reference number 2 generally designates a pressure sensitive area.
- a buffer structure 6 is attached to surface Ia adjacent to the sensitive structure 2.
- buffer structure 6 is a layer forming a frame around sensitive structure 2.
- Buffer structure 6 can e.g. be glued, bonded or soldered to substrate 1.
- it is manufactured by applying a buffer layer directly onto surface Ia of substrate 1 and structuring the same using photolitographic methods .
- Lead frames are known to the person skilled in the art. They generally are metal structures that carry the substrate during packaging and that form the contact pins or pads of the final device. Bond wires 8 are used to connect the contact pads 4 to lead frame 7 in conventional manner.
- a housing In a next step, as shown in Fig. 4, a housing
- Fig. 10 is formed, advantageously by transfer molding or another molding technique.
- the device of Fig. 3 is placed in a mold and a flowable material, such as a heated thermoplastic, is injected into the mold and then hardened. Finally the mold is removed.
- a flowable material such as a heated thermoplastic
- the mold is shaped to create an access opening 12 in housing 10.
- Fig. 5 shows an embodiment of a suitable mold for casting housing 10. It comprises an upper mold section 30 and a lower mold section 31, which, for clarity, are shown at a slight distance from each other. Between them, mold sections 30 and 31 form an interior space 32.
- Upper mold section 30 comprises a stamp-like, inward extending section 33 extending into interior space 32 and having a flat or centrally recessed end surface 34. Inward extending section 33 is advantageously mounted to upper mold section 30. It may be an integral part of upper mold section 30 or it may be a separate part placed into an opening or recess of upper mold section 30.
- Fig. 6 shows the device during casting (with lead frame 7 not shown for better clarity) .
- upper mold section 30 is positioned such that end face 34 of inward extending section 33 abuts against buffer structure 6.
- buffer structure 6 forms a seal between substrate 1 and inward extending section 33, sealing a central opening 35.
- Buffer structure 6 prevents inward extending section 33 from contacting sensitive structure 2 and damaging the same.
- a hardening material is introduced into interior space 32 through suitable openings (not shown) and is hardened by cooling and/or setting.
- mold sections 30, 31 with inward extending section 33 are removed to form a final device as shown in Fig. 7.
- the space occupied by inward extending section 33 now forms access opening 12, which communicates with central opening 35 in buffer structure 6, thereby providing direct access to sensitive structure 2.
- buffer struc- ture 6 is advantageously made of a deformable material, such as gold or a plastic.
- inward extending section 33 may be deformable at its end face 34.
- buffer structure 6 advantageously ex- tends over surface Ia by a height H of at least 10 ⁇ m, in particular between 10 ⁇ m and 100 ⁇ m, preferably between 25 ⁇ m and 50 ⁇ m.
- buffer structure 6 of this embodiment covers all of the sensor's sensitive structure 2. It forms a continuous layer directly applied to surface Ia and sensitive structure 2.
- the second embodiment of the device is again cast in a mold of the type as shown in Fig. 5 and, as illustrated in Fig. 9, end face 34 of inward extending section 33 again is placed to abut against buffer structure 6 for preventing material from entering between end face 34 and buffer structure 6.
- mold sections 30, 31 and inward extending section 33 are removed, thereby forming a device as shown in Fig. 10, where access opening 12 extends from a surface of housing 10 to buffer structure 6.
- buffer structure 6 is removed at least partially through access opening 12 for providing sensitive structure 2 with direct access to its surroundings .
- various techniques can be used, such as drilling, milling, laser ablation, etc.
- buffer structure 6 is removed by heat and/or chemical treatment.
- This can e.g. be achieved by one of the following means:
- A) Buffer structure 6 is made of a material with a melting or evaporation temperature lower than the melting point of housing 10.
- housing 10 is e.g. cast using a polymer precursor or a partially po- lymerized material, which is then cured such that it withstands a higher temperature than the one required for melting or evaporating buffer structure 6. Once that housing 10 has been cured and access opening 12 has been opened, the device is subjected to a temperature suffi- cient for evaporating or melting buffer structure 6 at least partially.
- a suitable material for housing 10 is e.g. Xydar by Solvay Advanced Polymers, LCC, Georgia, USA, which can be cast as a resin at low temperatures.
- An advantageous material to be used for forming buffer structure 6 is the Unity Sacrificial Polymer by Promerus LCC, Cleveland, USA.
- Buffer structure 6 is made of a material that can be solved or chemically decomposed after forming access opening 12.
- buffer structure 6 can be made of a salt that can be dissolved by water introduced through access opening 12.
- housing 10 can e.g. also be formed on top of lead frame 7 only. 12. This housing technique, where the lateral surfaces
- 10a of housing 10 are formed by cutting apart neighboring devices, is known to the person skilled in the art.
- the present technique can also be used for packaging flow sensors.
- the design of Figs. 8 - 11 can be used for a flow sensor if two spaced apart inward projecting sections are used, as indicated by dashed lines 33a, 33b in Fig. 9, for forming a device with two access openings as shown by dashed lines 12a, 12b in Fig. 11.
- a first access opening allows to feed the fluid to the cavity 14 formed by the removal of buffer structure 6, where its flow is measured, whereupon it exists through the second access opening.
- inward extending section 33 can be shaped to create a much wider, groove- shaped, access opening as indicated by dashed lines 33c in Fig. 9, which allows, after removal of buffer structure 6, to measure the flow of a fluid passing over the upper surface of housing 10.
- dashed lines 33c are shown to ex- tends upwards and outwards from buffer structure 6. However, they can also extend horizontally outwards, as indicated under reference numeral 33d, in which case section 33 is not truly extending into interior space 32 but rather merely bordering the same.
- buffer structure 6 was used for protecting sensor 2 during casting and formation of access opening 12. However, depending on the robustness of the sensor and the process for creating access opening 12, buffer structure 6 may be omitted, or buffer structure 6 may be formed by an outermost layer of sensor 2.
- buffer structure 6 is advantageous because it protects, as mentioned, sensitive structure 2, as well as substrate 1 in general, and be- cause it allows to simplify the design of inward extending section 33, obviating the need for a disposable soft cladding at end surface 34.
- the present invention is especially advantageous when being used in combination with a sensitive structure 2 mounted at least partially on a thin membrane, such as shown in Fig. 5 of US 6 729 181, which is incorporated by reference herein.
- a frame-like buffer structure 6 as shown in Fig. 2 of the present application extending around the thin membrane allows to protect the membrane from being damaged in the molding process.
- a corresponding device is shown in Fig. 13, which depicts the membrane 38 carrying part (or all) of sensitive structure 2.
- Typical sensor devices using such or similar membranes are flow sensors, pressure sensors, and infrared sensors, and various other types of sensors where sensitive structure 2 needs to be placed on a thin carrier.
Landscapes
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- Chemical & Material Sciences (AREA)
- Immunology (AREA)
- Electrochemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
A sensor device having a sensitive structure (2) integrated on a substrate (1) is packaged in a housing (10) by transfer molding while an inward extending section (33) of the mold (30,31) maintains an access opening to the sensor. A buffer structure (6) is arranged on the substrate between the inward extending section (33) and the sensitive structure (2). The buffer structure (6) may be a sacrificial material layer on the sensitive structure (2) and/or a frame around the sensitive structure (2) and protects the same from damage by the inward extending section (33). The invention also relates to a manufacturing method for a substance sensor, such as a gas sensor or a humidity sensor.
Description
A method for packaging integrated sensors
Technical Field
The present invention relates to a method for manufacturing a sensor device comprising a substrate with an integrated sensitive structure, in particular using molding techniques. It also relates to a method for manu- facturing a substance sensor, in particular a gas sensor or a humidity sensor.
Background Art
The integration of sensors on a substrate, e.g. a semiconductor substrate, provides a series of advantages, such as small size and the possibility to apply advanced manufacturing techniques as used in semiconduc- tor technology. In addition, when using a semiconductor substrate, it is possible to integrate further functionality on the substrate, such as amplifiers, D/A- converters, calibration circuitry, etc.
Many of the sensors devices of this type, such as gas sensors, flow sensors, humidity sensors or optical sensors, need to be in contact with their surroundings, which makes it impossible to use conventional semiconductor packaging for housing the devices. Rather, specialized packaging techniques are required, such as they are e.g. described in US 6 750 522 or US 6 729 181. These packaging techniques tend, however, to be expensive .
Another family of packaging techniques for light detectors and pressure gauges is described in WO 02/078077, WO 03/028086 and EP 1 246 235, where the housing is cast in a mold having an inwardly projecting section. The inwardly projecting section maintains an access
opening to the sensitive structure of the sensor device while casting the housing. When using these techniques, care must be taken in order to prevent the inwardly projecting section from damaging the sensor's sensitive structure. For this purpose, the end face of the inward projection section can be covered by a disposable soft cladding, which, however, needs to be replaced at intervals, thereby rendering the process -more expensive.
Disclosure of the Invention
Hence, it is a general object of the invention to provide an economical packaging technique for sensor devices.
This object is achieved by the method of claim 1. Accordingly, a buffer structure is integrated on a surface of the substrate. The buffer structure covers and/or surrounds the sensor's sensitive structure and ex- tends away from the surface, i.e. it projects away from the surface. For casting the housing, a mold is provided. The mold defines an interior space to receive a hardening material and has a section extending into or bordering the interior space. The substrate is placed in the mold, and the parts are arranged such that the section abuts against the buffer structure. Then the hardening material is introduced into the mold and hardened for forming the housing. After removing the mold, the access opening formed by the section extends from the surface of the housing to the buffer structure. A direct access opening extending all the way, to the sensitive structure is formed, e.g. by removing the buffer structure at least partially and/or by providing it with one or more suitable openings. In an advantageous embodiment, the buffer structure is a frame surrounding the sensitive structure and having a central opening for providing access to the
same. While casting the housing, the section abuts against the frame and prevents material from entering the central opening. Advantageously, the frame forms a tight seal between the substrate and the inward projecting sec- tion while introducing the hardening material into the mold.
In an other aspect of the invention, it is an object to provide an efficient and inexpensive method for manufacturing a substance sensor, i.e. a sensor that is able to detect a substance in a fluid, such as a gas sensor or a humidity sensor. The substance sensor comprises a substrate with an integrated sensitive structure.
This object is achieved by providing a mold defining an interior space and having a section extending into said interior space. The substrate is placed in the mold, wherein the parts are arranged such that the section extends towards the sensitive structure. The section may e.g. touch the sensitive structure directly, or it may be separated from the same by a buffer structure. Ma- terial is introduced into the mold for casting the housing over the substrate. After hardening the material at least partially, the section is removed, thereby forming an access opening from the surface of the housing towards the sensitive structure.
Brief Description of the Drawings
The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:
Fig. 1 shows a semiconductor substrate with integrated sensor,
Fig. 2 shows the device of Fig. 1 after the addition of the buffer structure,
Fig. 3 shows the device of Fig. 2 after placement on a lead frame,
Fig. 4 shows the device of Fig. 3 after transfer molding, Fig. 5 shows a sectional view through the mold,
Fig. 6 shows a sectional view during casting,
Fig. 7 shows a sectional view of the final sensor device, Fig. 8 shows a substrate with a second embodiment of the buffer structure,
Fig. 9 shows the second embodiment of the device while casting the housing,
Fig. 10 shows the second embodiment of the device after casting the housing,
Fig. 11 shows the second embodiment of the device after removal of the buffer structure,
Fig. 12 shows a third embodiment of the device after casting and removal of the buffer structure, and
Fig. 13 shows a fourth embodiment of the device where the sensitive structure is mounted on a membrane .
Modes for Carrying Out the Invention
Figure 1 shows a device comprising a semiconductor substrate 1. A sensitive structure 2, evaluation circuitry 3 and contact pads 4 are integrated on a top surface Ia of semiconductor substrate 1. Alternatively, substrate 1 can be a simple carrier for sensor 2 without active circuitry, in which case it may also be of a non- semiconductor material.
The device of Fig. 1 may e.g. be a flow sen- sor, such as it is described in reference to Fig. 5 of US 6 729 181, in which case reference number 2 generally designates the membrane carrying the heater and tempera-
ture sensors. It may also be a sensor for detecting substances, in particular humidity, such as it is described in US 6 690 569, in which case reference number 2 generally designates the measuring layer of the device, or it may be some other type of gas detector or, more generally, substance detector for detecting a substance in a fluid. The sensor may e.g. also be a light sensor, in which case reference number 2 generally designates the light sensitive area of the device, or it may be a pres- sure sensor, in which case reference number 2 generally designates a pressure sensitive area.
In the following, the steps for packaging the device of Fig. 1 in a housing are described.
In a first step, as shown in Fig. 2, a buffer structure 6 is attached to surface Ia adjacent to the sensitive structure 2. In the embodiment of Fig. 2, buffer structure 6 is a layer forming a frame around sensitive structure 2. Buffer structure 6 can e.g. be glued, bonded or soldered to substrate 1. Advantageously, it is manufactured by applying a buffer layer directly onto surface Ia of substrate 1 and structuring the same using photolitographic methods .
Now, as shown in Fig. 3, substrate 1 is placed on a lead frame 7. Lead frames are known to the person skilled in the art. They generally are metal structures that carry the substrate during packaging and that form the contact pins or pads of the final device. Bond wires 8 are used to connect the contact pads 4 to lead frame 7 in conventional manner. In a next step, as shown in Fig. 4, a housing
10 is formed, advantageously by transfer molding or another molding technique. For this purpose, the device of Fig. 3 is placed in a mold and a flowable material, such as a heated thermoplastic, is injected into the mold and then hardened. Finally the mold is removed. This technology is widely used for semiconductor packaging. The mold is shaped to create an access opening 12 in housing 10.
Fig. 5 shows an embodiment of a suitable mold for casting housing 10. It comprises an upper mold section 30 and a lower mold section 31, which, for clarity, are shown at a slight distance from each other. Between them, mold sections 30 and 31 form an interior space 32. Upper mold section 30 comprises a stamp-like, inward extending section 33 extending into interior space 32 and having a flat or centrally recessed end surface 34. Inward extending section 33 is advantageously mounted to upper mold section 30. It may be an integral part of upper mold section 30 or it may be a separate part placed into an opening or recess of upper mold section 30.
Fig. 6 shows the device during casting (with lead frame 7 not shown for better clarity) . As can be seen, upper mold section 30 is positioned such that end face 34 of inward extending section 33 abuts against buffer structure 6. Hence, buffer structure 6 forms a seal between substrate 1 and inward extending section 33, sealing a central opening 35. Buffer structure 6 prevents inward extending section 33 from contacting sensitive structure 2 and damaging the same.
Once the mold sections 30, 31 are placed around substrate 1, a hardening material is introduced into interior space 32 through suitable openings (not shown) and is hardened by cooling and/or setting.
After hardening the material, mold sections 30, 31 with inward extending section 33 are removed to form a final device as shown in Fig. 7. As can be seen, the space occupied by inward extending section 33 now forms access opening 12, which communicates with central opening 35 in buffer structure 6, thereby providing direct access to sensitive structure 2.
In order to provide a tight seal between inward extending section 33 and substrate 1, buffer struc- ture 6 is advantageously made of a deformable material, such as gold or a plastic. Alternatively, or in addition
thereto, inward extending section 33 may be deformable at its end face 34.
For providing sufficient protection of sensitive structure 2, buffer structure 6 advantageously ex- tends over surface Ia by a height H of at least 10 μm, in particular between 10 μm and 100 μm, preferably between 25 μm and 50 μm.
A second embodiment of the invention is now described with reference to Figs. 8 - 11. In contrast to the first embodiment, and as can be seen from Fig. 8, buffer structure 6 of this embodiment covers all of the sensor's sensitive structure 2. It forms a continuous layer directly applied to surface Ia and sensitive structure 2. The second embodiment of the device is again cast in a mold of the type as shown in Fig. 5 and, as illustrated in Fig. 9, end face 34 of inward extending section 33 again is placed to abut against buffer structure 6 for preventing material from entering between end face 34 and buffer structure 6.
After hardening the material of housing 10, mold sections 30, 31 and inward extending section 33 are removed, thereby forming a device as shown in Fig. 10, where access opening 12 extends from a surface of housing 10 to buffer structure 6.
In a next step, buffer structure 6 is removed at least partially through access opening 12 for providing sensitive structure 2 with direct access to its surroundings . For removing buffer structure 6, various techniques can be used, such as drilling, milling, laser ablation, etc.
Advantageously, in order to prevent mechanical stress, buffer structure 6 is removed by heat and/or chemical treatment. This can e.g. be achieved by one of the following means:
A) Buffer structure 6 is made of a material with a melting or evaporation temperature lower than the melting point of housing 10. For this purpose, housing 10 is e.g. cast using a polymer precursor or a partially po- lymerized material, which is then cured such that it withstands a higher temperature than the one required for melting or evaporating buffer structure 6. Once that housing 10 has been cured and access opening 12 has been opened, the device is subjected to a temperature suffi- cient for evaporating or melting buffer structure 6 at least partially. A suitable material for housing 10 is e.g. Xydar by Solvay Advanced Polymers, LCC, Georgia, USA, which can be cast as a resin at low temperatures. An advantageous material to be used for forming buffer structure 6 is the Unity Sacrificial Polymer by Promerus LCC, Cleveland, USA.
B) Buffer structure 6 is made of a material that can be solved or chemically decomposed after forming access opening 12. For example, buffer structure 6 can be made of a salt that can be dissolved by water introduced through access opening 12.
The present invention is suited for a variety of housing shapes and sizes. As shown in Fig. 12, housing 10 can e.g. also be formed on top of lead frame 7 only. 12. This housing technique, where the lateral surfaces
10a of housing 10 are formed by cutting apart neighboring devices, is known to the person skilled in the art.
The present technique can also be used for packaging flow sensors. In one embodiment, the design of Figs. 8 - 11 can be used for a flow sensor if two spaced apart inward projecting sections are used, as indicated by dashed lines 33a, 33b in Fig. 9, for forming a device with two access openings as shown by dashed lines 12a, 12b in Fig. 11. A first access opening allows to feed the fluid to the cavity 14 formed by the removal of buffer structure
6, where its flow is measured, whereupon it exists through the second access opening.
In an other embodiment, inward extending section 33 can be shaped to create a much wider, groove- shaped, access opening as indicated by dashed lines 33c in Fig. 9, which allows, after removal of buffer structure 6, to measure the flow of a fluid passing over the upper surface of housing 10.
In Fig. 9, dashed lines 33c are shown to ex- tends upwards and outwards from buffer structure 6. However, they can also extend horizontally outwards, as indicated under reference numeral 33d, in which case section 33 is not truly extending into interior space 32 but rather merely bordering the same. In the embodiments described so far, buffer structure 6 was used for protecting sensor 2 during casting and formation of access opening 12. However, depending on the robustness of the sensor and the process for creating access opening 12, buffer structure 6 may be omitted, or buffer structure 6 may be formed by an outermost layer of sensor 2.
Using buffer structure 6, however, is advantageous because it protects, as mentioned, sensitive structure 2, as well as substrate 1 in general, and be- cause it allows to simplify the design of inward extending section 33, obviating the need for a disposable soft cladding at end surface 34.
The present invention is especially advantageous when being used in combination with a sensitive structure 2 mounted at least partially on a thin membrane, such as shown in Fig. 5 of US 6 729 181, which is incorporated by reference herein. In particular using a frame-like buffer structure 6 as shown in Fig. 2 of the present application extending around the thin membrane allows to protect the membrane from being damaged in the molding process. A corresponding device is shown in Fig. 13, which depicts the membrane 38 carrying part (or all)
of sensitive structure 2. Typical sensor devices using such or similar membranes are flow sensors, pressure sensors, and infrared sensors, and various other types of sensors where sensitive structure 2 needs to be placed on a thin carrier.
Claims
1. A method for manufacturing a sensor device comprising a substrate (1) with an integrated sensitive structure (2), said method comprising the steps of integrating, onto a surface (Ia) of said substrate (1), a buffer structure (6) surrounding and/or covering said sensitive structure (2) and extending away from said surface (Ia), providing a mold (30,31) defining an interior space (32) and having a section (33) extending into or bordering said interior space (32), placing said substrate (1) in said mold (30,31) with said section (33) abutting against said buffer structure (6), introducing a hardening material into said mold (30,31) for casting a housing (10) over said substrate (1) , after hardening said material at least par- tially, removing said section (33) and forming an access opening extending to said sensitive structure (2) .
2. The method of claim 1 wherein said buffer structure (6) is a frame surrounding said sensitive structure (2) and surrounds a central opening (35) for access to said sensitive structure (2), wherein said section (33) abutting against said frame prevents said material from entering said central opening (35).
3. The method of claim 2 wherein said buffer structure (6) comprises a material selected from the group comprising plastics and gold.
4. The method of any of the claims 2 or 3 wherein, while introducing said material into said mold, said frame forms a tight seal between said substrate (1) and said section (33) .
5. The method of any of the claims 2 to 4 wherein said sensitive structure (2) is located at least partially on a membrane (38) of said substrate (1), wherein said frame is arranged around said membrane (38) .
6. The method of any of the preceding claims wherein said buffer structure (6) extends over said sur- face by a height (H) of at least 10 μm, in particular between 10 μm and 100 μm, in particular between 25 μm and 50 μm.
7. The method of any of the preceding claims comprising the step of after hardening said material at least partially, removing said buffer structure (6) at least partially.
8. The method of claim 7 comprising the steps of removing said section (33) after hardening said material at least partially, thereby creating an opening, removing said buffer structure (6) through said opening.
9. The method of any of the claims 7 or 8 comprising the step of melting, evaporating, dissolving or chemically decomposing said buffer structure (6) at least partially for removing said buffer structure (6) at least partially.
10. The method of any of the claims 7 to 9 wherein said buffer structure (6) covers all of said sensitive structure (2) .
11. The method of any of the preceding claims wherein the housing (10) is cast using transfer molding.
12. The method of any of the preceding claims comprising the step of, prior to casting said housing (10) , mounting the substrate (1) on a metallic lead frame (7) and connecting contact pads (4) of the substrate (1) to said lead frame (7), wherein said housing (10) is cast such that said lead frame (7) is accessible from outside said housing (10) for forming external contacts for said sensor (2 ) .
13. The method of any of the preceding claims wherein said buffer structure (6) is formed by applying a buffer layer directly onto said surface.
14. A method, in particular of any of the preceding claims, for manufacturing a substance sensor for measuring a substance in a fluid, said substance sensor comprising a substrate (1) with an integrated sensitive structure (2), said method comprising the steps of providing a mold (30,31) defining an interior space (32) and having a section (33) extending into or bordering said interior space (32), placing said substrate (1) in said mold with said section (33) extending towards said sensitive structure (2) , introducing a hardening material into said mold (30,31) for casting a housing (10) over said substrate (1) (2) , and after hardening said material at least partially, removing said section (33) for forming an access opening towards said sensitive structure (2) .
15. The method of claim 14 further comprising the steps of integrating, onto a surface (Ia) of said substrate, a buffer structure (6) surrounding and/or cov- ering said sensitive structure (2) and extending away from said surface, and abutting said section (33) against buffer structure (6) while said material is hardened at least partially.
16. The method of any of the claims 14 or 15 wherein said substance sensor is a humidity sensor.
17. The method of any of the claims 14 or 15 wherein said substance sensor is a gas sensor.
18. The method of any of the preceding claims wherein said section is mounted to said mold.
19. The method of any of the preceding claims wherein said section (33) extends into said interior space (32) .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/CH2005/000234 WO2006114005A1 (en) | 2005-04-27 | 2005-04-27 | A method for packaging integrated sensors |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/CH2005/000234 WO2006114005A1 (en) | 2005-04-27 | 2005-04-27 | A method for packaging integrated sensors |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2006114005A1 true WO2006114005A1 (en) | 2006-11-02 |
Family
ID=35527572
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CH2005/000234 WO2006114005A1 (en) | 2005-04-27 | 2005-04-27 | A method for packaging integrated sensors |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2006114005A1 (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2112487A1 (en) | 2008-04-23 | 2009-10-28 | Sensirion AG | Method for manufacturing a pressure sensor by applying a cover layer |
EP2154713A1 (en) | 2008-08-11 | 2010-02-17 | Sensirion AG | Method for manufacturing a sensor device with a stress relief layer |
EP2159558A1 (en) | 2008-08-28 | 2010-03-03 | Sensirion AG | A method for manufacturing an integrated pressure sensor |
EP2224218A1 (en) | 2009-02-25 | 2010-09-01 | Sensirion AG | A sensor in a moulded package and a method for manufacturing the same |
EP2273261A1 (en) | 2009-07-09 | 2011-01-12 | Sensirion AG | Sensor device on a flexible carrier |
EP2287596A1 (en) | 2009-08-11 | 2011-02-23 | Sensirion AG | Sensor with glob-top and method for manufacturing the same |
DE102011013468A1 (en) | 2011-03-09 | 2012-09-13 | Micronas Gmbh | Semiconductor package and method of manufacturing a semiconductor package |
EP2765410A1 (en) * | 2014-06-06 | 2014-08-13 | Sensirion AG | Gas sensor package |
US9355870B1 (en) | 2015-01-15 | 2016-05-31 | Silicon Laboratories Inc. | Integrated circuit with sensor area and resin dam |
EP3032227A1 (en) * | 2014-12-08 | 2016-06-15 | Sensirion AG | Flow sensor package |
US9914638B2 (en) | 2015-01-14 | 2018-03-13 | Sensirion Ag | Sensor package |
JP2018155572A (en) * | 2017-03-17 | 2018-10-04 | 日立オートモティブシステムズ株式会社 | Physical amount detection device |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4894707A (en) * | 1987-02-12 | 1990-01-16 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor device having a light transparent window and a method of producing same |
US20010023087A1 (en) * | 2000-03-14 | 2001-09-20 | Manfred Brandl | Method for housing sensors in a package |
EP1211722A1 (en) * | 2000-11-30 | 2002-06-05 | STMicroelectronics S.r.l. | Manufacturing method of electronic device package |
WO2002078077A1 (en) * | 2001-03-26 | 2002-10-03 | European Semiconductor Assembly (Eurasem) B.V. | Method for encapsulating a chip having a sensitive surface |
-
2005
- 2005-04-27 WO PCT/CH2005/000234 patent/WO2006114005A1/en active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4894707A (en) * | 1987-02-12 | 1990-01-16 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor device having a light transparent window and a method of producing same |
US20010023087A1 (en) * | 2000-03-14 | 2001-09-20 | Manfred Brandl | Method for housing sensors in a package |
EP1211722A1 (en) * | 2000-11-30 | 2002-06-05 | STMicroelectronics S.r.l. | Manufacturing method of electronic device package |
WO2002078077A1 (en) * | 2001-03-26 | 2002-10-03 | European Semiconductor Assembly (Eurasem) B.V. | Method for encapsulating a chip having a sensitive surface |
Non-Patent Citations (1)
Title |
---|
COTOFANA C ET AL: "Low-cost plastic sensor packaging using the open-window package concept", SENSORS AND ACTUATORS A, ELSEVIER SEQUOIA S.A., LAUSANNE, CH, vol. 67, no. 1-3, 15 May 1998 (1998-05-15), pages 185 - 190, XP004130134, ISSN: 0924-4247 * |
Cited By (24)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2112487A1 (en) | 2008-04-23 | 2009-10-28 | Sensirion AG | Method for manufacturing a pressure sensor by applying a cover layer |
EP2154713A1 (en) | 2008-08-11 | 2010-02-17 | Sensirion AG | Method for manufacturing a sensor device with a stress relief layer |
CN101667548A (en) * | 2008-08-11 | 2010-03-10 | 森斯瑞股份公司 | Temperature sensor with buffer layer |
US7901971B2 (en) | 2008-08-11 | 2011-03-08 | Sensirion Ag | Method for manufacturing a sensor device with a stress relief layer |
EP2159558A1 (en) | 2008-08-28 | 2010-03-03 | Sensirion AG | A method for manufacturing an integrated pressure sensor |
US8815623B2 (en) | 2008-08-28 | 2014-08-26 | Sensirion Ag | Method for manufacturing an intergrated pressure sensor |
EP2224218A1 (en) | 2009-02-25 | 2010-09-01 | Sensirion AG | A sensor in a moulded package and a method for manufacturing the same |
US8156815B2 (en) | 2009-02-25 | 2012-04-17 | Sensirion Ag | Sensor in a moulded package and a method for manufacturing the same |
EP2273261A1 (en) | 2009-07-09 | 2011-01-12 | Sensirion AG | Sensor device on a flexible carrier |
EP2287596B1 (en) * | 2009-08-11 | 2014-03-19 | Sensirion AG | Sensor with glob-top and method for manufacturing the same |
EP2287596A1 (en) | 2009-08-11 | 2011-02-23 | Sensirion AG | Sensor with glob-top and method for manufacturing the same |
US8822253B2 (en) | 2011-03-09 | 2014-09-02 | Micronas Gmbh | Semiconductor housing and method for the production of a semiconductor housing |
US8604599B2 (en) | 2011-03-09 | 2013-12-10 | Micronas Gmbh | Semiconductor housing and method for the production of a semiconductor housing |
DE102011013468A1 (en) | 2011-03-09 | 2012-09-13 | Micronas Gmbh | Semiconductor package and method of manufacturing a semiconductor package |
EP2549529A1 (en) | 2011-03-09 | 2013-01-23 | Micronas GmbH | Semiconductor housing and method for manufacturing same |
JP2015230315A (en) * | 2014-06-06 | 2015-12-21 | センシリオン アクチエンゲゼルシャフト | Gas sensor package |
EP2765410A1 (en) * | 2014-06-06 | 2014-08-13 | Sensirion AG | Gas sensor package |
CN105277594A (en) * | 2014-06-06 | 2016-01-27 | 盛思锐股份公司 | Gas sensor package |
US9952171B2 (en) | 2014-06-06 | 2018-04-24 | Sensirion Ag | Gas sensor package |
EP3032227A1 (en) * | 2014-12-08 | 2016-06-15 | Sensirion AG | Flow sensor package |
US10151612B2 (en) | 2014-12-08 | 2018-12-11 | Sensirion Ag | Flow sensor package |
US9914638B2 (en) | 2015-01-14 | 2018-03-13 | Sensirion Ag | Sensor package |
US9355870B1 (en) | 2015-01-15 | 2016-05-31 | Silicon Laboratories Inc. | Integrated circuit with sensor area and resin dam |
JP2018155572A (en) * | 2017-03-17 | 2018-10-04 | 日立オートモティブシステムズ株式会社 | Physical amount detection device |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2006114005A1 (en) | A method for packaging integrated sensors | |
EP1717562A1 (en) | A method for packaging integrated sensors | |
US6923069B1 (en) | Top side reference cavity for absolute pressure sensor | |
EP0985138B1 (en) | Sensor device and method of forming a sensor device | |
EP2224218B1 (en) | A sensor in a moulded package and a method for manufacturing the same | |
US6401545B1 (en) | Micro electro-mechanical system sensor with selective encapsulation and method therefor | |
US20090072333A1 (en) | Sensor array having a substrate and a housing, and method for manufacturing a sensor array | |
US8815623B2 (en) | Method for manufacturing an intergrated pressure sensor | |
US20100117185A1 (en) | Temperature sensor with buffer layer | |
US20100199777A1 (en) | Exposed Pad Backside Pressure Sensor Package | |
US20070022808A1 (en) | Sensor device and method for manufacturing the same | |
EP3356811A1 (en) | Gas sensor with a gas permeable region | |
US20130193530A1 (en) | Semiconductor Component and Corresponding Production Method | |
EP2871152B1 (en) | Sensor device | |
US20040171195A1 (en) | Method for encapsulating a chip having a sensitive surface | |
US9598280B2 (en) | Environmental sensor structure | |
WO2008046235A1 (en) | A method for packaging integrated sensors | |
WO2016100621A1 (en) | Exposed-die mold package for a sensor and method for encapsulating a sensor that interacts with the environment | |
US10858245B2 (en) | Deposition of protective material at wafer level in front end for early stage particle and moisture protection | |
US7617599B2 (en) | Sensor packaging method for a human contact interface | |
US7737544B2 (en) | Sensor system having a substrate and a housing, and method for manufacturing a sensor system | |
TWI583618B (en) | Micromechanic system and process to produce a micromechanic system | |
US20200231432A1 (en) | Method of manufacturing a sensor device and moulding support structure | |
KR102557238B1 (en) | A method for packaging one or more semiconductor components, and a semiconductor device | |
TWI543925B (en) | Mikromechanischer sensor und verfahren zu seiner herstellung |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWW | Wipo information: withdrawn in national office |
Country of ref document: DE |
|
NENP | Non-entry into the national phase |
Ref country code: RU |
|
WWW | Wipo information: withdrawn in national office |
Country of ref document: RU |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 05731405 Country of ref document: EP Kind code of ref document: A1 |