GB2369436A - Chemical sensing micro-mechanical cantilever - Google Patents
Chemical sensing micro-mechanical cantilever Download PDFInfo
- Publication number
- GB2369436A GB2369436A GB0018520A GB0018520A GB2369436A GB 2369436 A GB2369436 A GB 2369436A GB 0018520 A GB0018520 A GB 0018520A GB 0018520 A GB0018520 A GB 0018520A GB 2369436 A GB2369436 A GB 2369436A
- Authority
- GB
- United Kingdom
- Prior art keywords
- micromechanical
- micromechanical component
- substrate
- array
- well
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- 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
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/0015—Cantilevers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C2201/00—Manufacture or treatment of microstructural devices or systems
- B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
- B81C2201/0101—Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
- B81C2201/0102—Surface micromachining
- B81C2201/0105—Sacrificial layer
- B81C2201/0109—Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Micromachines (AREA)
Abstract
A micromechanical component such as a microcantilever 10, or an array of microcantilevers, for use in a sensor for example, is fabricated by depositing a layer of PiRL 2 on a substrate 1 and then forming polyimide regions 6 on the PiRL 2, these regions 6 being the microcantilevers in the finished device. If a coating is required on the microcantilevers, this may be applied by adding another layer 7 over the regions 6, forming a well 8 in it and adding the coating material 9. The PiRL layers 2 and 7 are then removed.
Description
Micromechanical Devices This invention relates to micromechanical
components and more particularly, but not exclusively, to sensors which use a microcantilever in monitoring a variable.
A microcantilever is a beam of small dimensions, typically in the hundred of microns s range, which is fixed in one place and free to move at an end. Microcantilevers are commercially available and are conventionally formed from silicon or silicon nitride.
Movement of the beam may be used in a sensing device. For example, material to be detected may be absorbed onto the microcantilever surface to which a chemical coating has been applied. This changes the mass of the microcantilever, the mass change being lo measured by monitoring the change in the resonance frequency of the microcantilever.
In other types of sensor, microcantilevers may 'bend' in response to a physical or chemical change. Several methods of monitoring the degree of bending have previously been suggested. In one apparatus, a laser beam is directed onto a reflective part of the IS microcantilever and the direction of reflection is monitored, the direction changing as the angle of the microcantilever surface changes with respect to the direction of the laser source. According to a first aspect of the present invention, a method of fabricating a 20 micromechanical component on a substrate includes the steps of: taking a substrate; laying down a layer of first material on the substrate; removing part of the first material to define a pattern of at least one window; laying down a second material on the patterned first
material; and then removing the first material from between the second material and the substrate, the second material forming the micromechanical component.
The invention is particularly advantageous where the micromechanical component is a s microcantilever but may also be applicable to the fabrication of other types of component.
For example, the micromechanical component may be a structure which does not have an end which is free to move. The method may be used in the fabrication of microelectromechanical systems ( MS), but other micromechanical systems which do not involve electrical aspects in their operation may be manufactured using the inventive lo method.
The patterning and removing steps of the method may be performed using standard photolithographic and etching techniques and enable sub-micron accuracy to be achieved in alignment and dimensioning on features of a few tens or hundreds of microns. A 5 particularly suitable first material is PiRL (Polyimide Release Layer from Brewer Science).
Advantageously, the second material is polymeric, such as polyimide. However, any materials may be used which may be manipulated to meet the requirements of the inventive method. For example the second material may be a metal (such as aluminium), silicon nitride or polycrystalline silicon, or other material which is capable of being 20 patterned and has the required structural characteristics. The substrate may be, for example, of silicon or glass.
The window or windows defined in the first material may extend completely therethrough
to expose the underlying substrate or may be formed as recesses in which the first material is the bottom surface of the recess.
In a particularly advantageous additional step, a third material is laid down on the second s material, some of the third material is then removed to define a well and a fourth material is added in the well. This step allows a coating of some kind to be accurately laid down on the surface of the microcantilever or other micromechanical component. The well defines a boundary to contain the fourth material, being particularly useful where the material is in liquid form and might otherwise flow uncontrollably. The amount of fourth material used lo on the finished microcantilever may be controlled by the dimensions of the well and by subsequent patterning or planarising, if necessary, of the fourth material. The correct thickness of the final coating on the microcantilever may alternatively be attained by dispensing an accurately controlled volume into the well, the dimensions of which are known. The fourth material may be, for example, a chemically sensitive material suitable for use in detecting gases, vapours or liquids. Where an array of wells is defined, adjacent wells may hold different types of fourth material. Several different materials may be dispensed in one step on different microcantilevers in an array, thus reducing processing times and steps, 20 with the additional improvement in yield. With this technique, several micromechanical component arrays may be processed on the same wafer substrate. An advantageous aspect of the method is that the materials commonly used for patterning PiRL are in general also compatible with chemically sensitive materials. The fourth material may be selected for other functions in the final device. For example it may be reflective to laser beams.
In a second aspect of the invention, a method of depositing material on a micromechanical component includes the steps of: taking a substrate which carries at least one micromechanical component; depositing a layer of a first material over the 5 micromechanical component; removing first material over the micromechanical component to define a well; depositing a second material in the well; and then removing remaining first material from the micromechanical component. This aspect of the invention is applicable, for example, to microcantilevers formed from polymeric material and also to those of other materials, such as silicon or polysilicon. The substrate may be lo acquired from a supplier prefabricated with an array of microcantilevers or other components, and then the inventive method used to customize the array by laying down on the components a particular coating or coatings as the second material. This aspect of the invention enables accurate dispensing of coating materials to be carried out in a relatively small number of overall process steps.
According to a feature of the invention, a device in accordance with the invention comprises a micromechanical component of polymeric material, which preferably is polyimide. Polymeric material particularly lends itself to photolithographic and etching techniques, so that a device having a microcantilever, say, of such material is likely to be 20 accurately dimensioned, and where an array of nominally identical microcantilevers are included this is particularly advantageous. Also polymeric material has particularly suitable properties for use as a microcantilever, with good thermal characteristics, flexibility and lifetimes.
In one embodiment of the invention, the micromechanical component is included in a sensor and may be included in an array with other such components.
Some ways in which the invention may be performed are now described by way of s example with reference to the accompanying drawings in which: Figures 1 to 9 illustrate steps in a method in accordance with the invention.
With reference to Figure 1, a method of forming an array of polyimide microcantilevers on lo a silicon substrate for use in a sensor device includes taking a silicon wafer on which is then deposited a layer 2 of PiRL (Polyimide Release Layer) available from Brewer Science or another appropriate sacrificial material. The thickness of the PiRL 2 is arranged to be that of the distance between the free end of the microcantilevers and the substrate in the finished device. This can be achieved accurately in one step using conventional 5 techniques. In this embodiment, the PiRL 2 is a few microns thick. However, if necessary, the PiRL 2 could be laid down in several layers to obtain the desired thickness.
A layer of positive photoresist 3 is then deposited on the PiRL 2 and is exposed and developed using standard VLSI photolithographic methods. The development step of the 20 photoresist method also etches the underlying PiRL, giving a pattern of windows as shown in Figure 2.
The remaining part of the photoresist layer 3 is then removed so as to leave patterned PiRL 2 on the silicon substrate 1, as shown in Figure 3, the PiRL layer 2 having a plurality of windows 4, substantially rectangular in plan view, distributed over the silicon substrate 1.
5 A layer of polymeric structural material S. in this case polymide, is then laid down on top of the PiRL 2, as shown in Figure 4. The polyimide layer 5 is then patterned to leave an array of cantilever precursors 6 as shown in Figure 5. The cantilever precursors 6 are anchored to the silicon substrate 1 through windows 4 in the PiRL 2 and are supported by the PiRL 2 If required, the PiRL layer 2 under each cantilever precursor 6 is then etched, leaving the polyirnide intact, to give an array of uncoated polyimide microcantilevers. This may represent the final stage of the processing method. However, usually, where the array is to be included in a sensor device additional processing is required. Thus, instead of removing IS the PiRL 2 from the structure shown in Figure S. this is retained. An additional layer of PiRL 7 is then laid down on top of the polyimide regions 6 as shown in Figure 6. The additional PiRL 7 is then patterned to give wells 8 where parts of the polyimide regions 6 are exposed, as shown in Figure 7.
20 As shown in Figure 8 some of the wells 8 are filled with a chemical sensing material 9.
Different materials are used in respective different wells, with picopippetting techniques being used to dispense a material 9 in a liquid form into the wells. Some of the wells are left empty and the associated microcantilevers act as references in the final device. The
solvents are driven off to leave the materials 9 in the wells. The wells 8 are accurately defined and thus the chemically sensitive materials are also accurately defined.
Then the additional layer of PiRL 7 is removed, as is the first layer of PiRL 2 underlying 5 the polyimide regions 6, to leave an array of polyimide microcantilevers 10, shown in Figure 9. The steps shown in Figures 6 to 9 may be applicable to other types of MEMs device. In another method in accordance with the invention, the starting point involves taking a lo silicon substrate on which silicon or silicon nitride microcantilevers have already been fabricated. PiRL is deposited around and underneath the microcantilevers and then etched to define wells on the top surfaces of the microcantilevers which are then able to receive materials, in a similar way to the steps shown in Figures 6, 7 and 8. The PiRL is then removed to leave coated microcantilevers.
Although the methods described above concern forming sensor arrays used for chemical sensing to detect, for example, aromas, the method may be also applied to other forms of sensors, for example thermal sensors. The method may also be used in devices where the microcantilevers are designed to perform as switches or actuators, or some other function.
Claims (32)
1. A method of fabricating a micromechanical component on a substrate, including the steps of: taking a substrate; laying down a layer of first material on the substrate; removing part of the first material to define a pattern of at least one well; laying down a second material on the pattern first material; and then removing the first material from between the second material and the substrate, the second material forming the micromechanical component.
2. A method as claimed in claim 1 wherein the first material is PiRL.
3. A method as claimed in claim 1 or 2 wherein the second material is polymeric.
4. A method as claimed in claim 3 wherein the second material is polyimide.
5. A method as claimed in any preceding claim wherein the substrate is silicon or glass.
6. A method as claimed in any preceding claim wherein the micromechanical component is a microcantilever.
7. A method as claimed in any preceding claim wherein an array of micromechanical components is formed.
8. A method as claimed in any preceding claim and including the steps of laying down a third material on the second material; then removing some of the third material to define a well; and adding a fourth material in the well.
9. A method as claimed in claim 8 wherein the second and third materials are the same.
10. A method as claimed in claim 8 or 9 wherein the fourth material is chemically sensitive material.
11. A method as claimed in claim 8, 9 or 10 wherein respective different fourth materials are added to different wells defined in the third material.
12. A method as claimed in any one of claims 8 to 11 wherein the step is included of removing the third material after the fourth material has been added to the well.
13. A method as claimed in any preceding claim wherein the micromechanical component is included in a sensor device.
14. A method of depositing material on a micromechanical component including the steps of: taking a substrate which carries at least one micromechanical component; depositing a layer of a first material over the micromechanical component; removing first material over the micromechanical component to define a well; depositing a second material in the well; and then removing remaining first material from the micromechanical component.
15. A method as claimed in claim 14 wherein the micromechanical component is of silicon, silicon nitride, metal, polysilicon or polymer
16. A method as claimed in claim 14 or 15 wherein the micromechanical component is a micro c an ti l e ver.
17. A method as claimed in any preceding claim and including the step of incorporating the component in a MEMs device.
18. A device comprising a micromechanical component of polymeric material.
19. A device as claimed in claim 18 wherein a second different material is carried by the polymeric material.
20. A device as claimed in claim 19 wherein the second material is chemically sensitive.
21. A device as claimed in claim 18, 19 or 20 wherein the micromechanical component is a microcantilever.
22. A device as claimed in claim 18, 19, 20 or 21 and including an array of micromechanical components of polymeric material.
23. A device as claimed in claim 22 wherein micromechanical components included in the array have respective different sensitivities to a variable being sensed.
24. A device as claimed in claim 22 or 23 wherein the array includes micromechanical components arranged to act as reference means.
25. A device as claimed in any one of claims 18 to 24 wherein the polymeric material is polyimide.
26. A device as claimed in any one of claims 18 to 25 wherein the micromechanical components or array of micromechanical components is carried on a substrate of a material different to that of the polymeric material.
27. A device as claimed in claim 26 wherein the substrate is silicon or glass.
28. A device as claimed in any one of claims 18 to 27 wherein the micromechanical component is movable in dependence on a variable being sensed.
29. A device as claimed in any one of claims 18 to 28 and including read out means for providing an output signal representative of the movement of the micromechanical component or array of micromechanical components.
30. A MEMs including a device as claimed in any one of claims 18 to 29.
31. A method substantially as illustrated in and described with reference to the accompanying drawings.
32. A device substantially as illustrated in and described with reference to the accompanying drawings.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0018520A GB2369436A (en) | 2000-07-28 | 2000-07-28 | Chemical sensing micro-mechanical cantilever |
PCT/GB2001/003331 WO2002010065A1 (en) | 2000-07-28 | 2001-07-24 | Micromechanical devices |
AU2001275701A AU2001275701A1 (en) | 2000-07-28 | 2001-07-24 | Micromechanical devices |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0018520A GB2369436A (en) | 2000-07-28 | 2000-07-28 | Chemical sensing micro-mechanical cantilever |
Publications (2)
Publication Number | Publication Date |
---|---|
GB0018520D0 GB0018520D0 (en) | 2000-09-13 |
GB2369436A true GB2369436A (en) | 2002-05-29 |
Family
ID=9896494
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB0018520A Withdrawn GB2369436A (en) | 2000-07-28 | 2000-07-28 | Chemical sensing micro-mechanical cantilever |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU2001275701A1 (en) |
GB (1) | GB2369436A (en) |
WO (1) | WO2002010065A1 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0766089A2 (en) * | 1995-09-28 | 1997-04-02 | Siemens Aktiengesellschaft | Microelectronic integrated sensor and method for manufacturing the same |
US5618760A (en) * | 1994-04-12 | 1997-04-08 | The Board Of Trustees Of The Leland Stanford, Jr. University | Method of etching a pattern on a substrate using a scanning probe microscope |
GB2308460A (en) * | 1995-12-19 | 1997-06-25 | Daewoo Electronics Co Ltd | Method for manufacturing an actuated mirror array |
WO1998050773A2 (en) * | 1997-05-08 | 1998-11-12 | University Of Minnesota | Microcantilever biosensor |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4762426A (en) * | 1986-12-19 | 1988-08-09 | Honeywell Inc. | Remote passive temperature sensor |
US4740410A (en) * | 1987-05-28 | 1988-04-26 | The Regents Of The University Of California | Micromechanical elements and methods for their fabrication |
US5374792A (en) * | 1993-01-04 | 1994-12-20 | General Electric Company | Micromechanical moving structures including multiple contact switching system |
US5771902A (en) * | 1995-09-25 | 1998-06-30 | Regents Of The University Of California | Micromachined actuators/sensors for intratubular positioning/steering |
US5563341A (en) * | 1995-06-07 | 1996-10-08 | Fenner; Ralph L. | Vapor pressure sensor and method |
US5870007A (en) * | 1997-06-16 | 1999-02-09 | Roxburgh Ltd. | Multi-dimensional physical actuation of microstructures |
US6261494B1 (en) * | 1998-10-22 | 2001-07-17 | Northeastern University | Method of forming plastically deformable microstructures |
-
2000
- 2000-07-28 GB GB0018520A patent/GB2369436A/en not_active Withdrawn
-
2001
- 2001-07-24 WO PCT/GB2001/003331 patent/WO2002010065A1/en active Application Filing
- 2001-07-24 AU AU2001275701A patent/AU2001275701A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5618760A (en) * | 1994-04-12 | 1997-04-08 | The Board Of Trustees Of The Leland Stanford, Jr. University | Method of etching a pattern on a substrate using a scanning probe microscope |
EP0766089A2 (en) * | 1995-09-28 | 1997-04-02 | Siemens Aktiengesellschaft | Microelectronic integrated sensor and method for manufacturing the same |
US6156586A (en) * | 1995-09-28 | 2000-12-05 | Infineon Technologies Ag | Method for producing a microelectronic sensor |
GB2308460A (en) * | 1995-12-19 | 1997-06-25 | Daewoo Electronics Co Ltd | Method for manufacturing an actuated mirror array |
WO1998050773A2 (en) * | 1997-05-08 | 1998-11-12 | University Of Minnesota | Microcantilever biosensor |
Also Published As
Publication number | Publication date |
---|---|
WO2002010065A1 (en) | 2002-02-07 |
GB0018520D0 (en) | 2000-09-13 |
AU2001275701A1 (en) | 2002-02-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6016693A (en) | Microfabrication of cantilevers using sacrificial templates | |
US7579622B2 (en) | Fabrication of MEMS devices with spin-on glass | |
CA2338374C (en) | Method of manufacturing a capacitive ultrasound transducer | |
EP1211219B1 (en) | Process for manufacturing micromechanical and microoptomechanical structures with backside metalization | |
EP0562031A1 (en) | Microdevice for sensing or applying a force and method of making the same | |
EP1213259B1 (en) | Process for manufacturing micromechanical and microoptomechanical structures with single crystal silicon exposure step | |
US20080121042A1 (en) | Fluid paths in etchable materials | |
US9731957B2 (en) | Polymer anchored microelectromechanical system (MEMS) cantilever and method of fabricating the same | |
US20070196998A1 (en) | System and method for forming moveable features on a composite substrate | |
Singh et al. | Determination of precise crystallographic directions for mask alignment in wet bulk micromachining for MEMS | |
GB2369436A (en) | Chemical sensing micro-mechanical cantilever | |
JP2002162576A (en) | Method of manufacturing optical mems component and the optical mems structure | |
Bosch-Charpenay et al. | Real-time etch-depth measurements of MEMS devices | |
US20060050373A1 (en) | Probe for an optical near field microscope and method for producing the same | |
JP2004531720A (en) | Biosensor matrix and method for producing the same | |
KR20050095964A (en) | Sensor and fabrication method of piezoelectric ceramic nanobalance | |
Keeler et al. | Laterally deformable optical NEMS grating transducers for inertial sensing applications | |
EP1491950B1 (en) | Micro device and process for producing it | |
Fedele | Suspended microchannel resonators for Biosensing applications | |
Huff et al. | Microsystems process integration, testing, and packaging | |
Chen et al. | Micromachined SiO 2 microcantilever for high sensitive moisture sensor | |
Davies et al. | Engineering in-and out-of-plane stress in PECVD silicon nitride for CMOS-compatible surface micromachining | |
JP2002283296A (en) | Method of manufacturing micromechanical and microoptomechanical structure having prepatterning | |
US20040113148A1 (en) | Structure and method for measuring the etching speed | |
RU2340963C2 (en) | Method of composite cantilever production for scanning probe microscope |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |