WO2013009163A1

WO2013009163A1 - Nanostructured sensing device and method of fabricating same

Info

Publication number: WO2013009163A1
Application number: PCT/MY2012/000145
Authority: WO
Inventors: Anees ABDUL AZIZ; Daniel Chia Sheng Bien
Original assignee: Mimos Berhad
Priority date: 2011-07-11
Filing date: 2012-06-25
Publication date: 2013-01-17
Also published as: MY158140A

Abstract

The present invention relates generally to a nanostructured sensing device comprises of a support structure, at least one suspended resistor structure which is formed perpendicular to said support structure and a plurality of sensing elements being assembled onto said resistor structure, wherein said resistor structure is anchored to said support structure via at least one hinge pad. Said sensing device of the present invention can be fabricated by two different approaches, either said hinge pad is being deposited first and followed by the grow of said plurality of sensing elements on both top and bottom of said resistor structure or said plurality of sensing elements is grown before said hinge pad is deposited.

Description

NANOSTRUCTURED SENSING DEVICE AND METHOD OF

FABRICATING SAME

1. TECHNICAL FIELD OF THE INVENTION

2. BACKGROUND OF THE INVENTION

Gas sensors or detection instruments are widely used in many industrial, medical and commercial applications such as industrial health and safety, environmental monitoring, manufacture process monitoring, petrochemical refining, semiconductor processing and biomedical applications. A variety of research about gas sensor has been performed due to its wide spread applications in many fields of science and technology. A lot of research and development is also done to design small and cheap gas sensor that possess high sensitivity, selectivity and stability with respect to give application to detect the absolute gas concentrations or odorless gases. For example, gas sensors for chip- based applications may detect gas levels of effluents such as H₂, NO2, CO, H₂S, petrochemical products, alcohols, etc.

The development of gas sensor devices with the use of semiconductor fabrication line is the preferred manufacturing process because of the potential to reduce cost. However fundamental materials and processing issues which are critical in affecting performance of gas sensors need to be addressed. The sensors with large ratio of surface area to volume would increase the opportunities for surface reactions. One of the new technologies is the use of nano crystalline material which is able to offer immense promise for improved sensitivity due to its unique physical properties. Gas sensors made of nanoscale materials exhibit the desirable large ratio of surface area to volume. It is believed that improved sensing technologies can therefore be configured and developed by taking advantage of recent advances in nano-sized materials.

Currently, micromachining technology is being extensively used to reduce device size, to lower production cost, to improve sensor performance and to make monolithic integration with microelectronics circuit or micromechanical systems to broaden the sensor application. The use of semiconductor thin film gas sensor based on metal oxides is found to have good sensitivity to some relevant gases such as CO, H₂, NO_x and hydrocarbons. Metal oxide gas sensors are frequently used in leakage detection, ambient air quality monitoring traffic, toxic gas detection as well as smoke gas monitoring in houses and buildings.

There are two different structures for micromachined gas sensor using metal oxide as the gas sensing material. One is the closed-membrane gas sensor and the other is suspended-membrane type gas sensor. The closed-membrane type is formed by means of anisotropic etching of silicon from backside whereby wet etchant like potassium hydroxide (KOH) are generally used. Appropriate etch stops for those etchant is required in closed-membrane gas sensor. While for the suspended-membrane-type is completely processed from the front side and it is often claim to be more compatible with CMOS processing. The suspended membrane is either formed by anisotropic etching with KOH or EDP (an aqueous solution of ethylene diamine and pyrocatechol) from the front or by sacrificial etching of oxide layers, whereby both techniques required substrate removal. For both of the closed-membrane gas sensor and the suspended-membrane type gas sensor, the gas sensitive area is located on the membrane which is the hottest part of the sensor due to exothermic reaction involved is gas detection and the use of heaters for sensing efficiency. Suspended membrane and free-standing gas sensors have been developed to reduce heat conduction losses to the substrate. The structures are produced by bulk micromachining, which is a technique to reduce power consumption significantly while improving heat capacity. However, while the structures using bulk micromachining solves some of the heat transfer problems, it introduces some of its own difficulty in the fabrication process. At present, the gas sensitive area which is free standing structure in air above cavities, which substrate is being removed by etchant through the back side of the substrate thickness. The front side of the wafer must therefore be protected with a piece of material that is resistant to etchant, and it is important to make sure that the resistant layer is thick enough so that a significant part at the front are survive at every point. While other disadvantages include the dimensions of the cavity are usually larger than needed and also difficulty in the alignment. The current method of fabricating gas sensors requires long fabrication time and complicated steps, which makes the process complex and costly. When a gas sensor is fabricated, there are also complicated fabricating processes in which expensive equipment is needed or thermal processing is performed at comparatively high temperature and costs are comparatively high such that it is difficult to widely implement gas sensors. It would hence be extremely advantageous if the above shortcoming is alleviated by having a nanostructured sensing device comprises of three- dimensional out of plane resistor heater with nanotubes or nanowires sensing material. The present invention is developed by self-assembly process which involves in-plane fabrication of resistor heater with nano-structured sensing material and subsequent rotation of the structure by surface tension force of a hinge pad.

3. SUMMARY OF THE INVENTION

Accordingly, it is the primary aim of the present invention to provide a nanostructured sensing device with three-dimensional out of plane resistor heater wherein the process steps of etching can be reduced with no etching of the substrate is required and no substrate modification is involved.

It is another object of the present invention to provide a nanostructured sensing device wherein the fabricating method for said nanostructured sensing device does not require etch stop for etchant.

Yet another object of the present invention is to provide a nanostructured sensing device which is able to give faster respond time based on the resistor heater with nano sensing material will lift up out-of-plane for gas detection. Yet another object of the present invention is to provide a nanostructured sensing device wherein resistor out-of-plane is based on surface tension force of hinge pad.

Yet another object of the present invention is to provide a nanostructured sensing device wherein planar resistor is fabricated in plane.

Yet another object of the present invention is to provide a nanostructured sensing device wherein the fabricating method for said nanostructured sensing device can be carried out on fully CMOS processed.

Other and further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice.

According to a preferred embodiment of the present invention there is provided,

A nanostructured sensing device comprising, a support structure; at least one resistor structure; a plurality of sensing elements; characterized in that said resistor structure is attached to said support structure via at least one hinge pad to obtain a three dimensional out-of-plane nanostructured sensing device.

In another aspect there is provided,

A method of fabricating nanostructured sensing device comprising step

i. depositing a layer of silicon dioxide or silicon nitride which is a sacrificial layer on top of support structure; ii. depositing a first layer of metal catalyst onto said sacrificial layer; iii. depositing a conductive layer onto said first layer of metal catalyst to form resistor structure and contact pads; characterized in that said method of fabricating nanostructured sensing device further comprising the following steps after Step iii: iv. etching of said sacrificial layer, said conductive layer and said first layer of metal catalyst to form a mould for hinge pad to reflow; v. depositing a second layer of metal catalyst on top of said resistor structure; vi. depositing said hinge pad; vii. etching part of said sacrificial layer which is under said resistor structure; viii. growing plurality of sensing elements on at least one surface of resistor structure; ix. reflow of said hinge pad substantially above the material's eutectic melting temperature to lift up said resistor structure.

In yet another aspect there is provided,

A method of fabricating nanostructured sensing device comprising step

i. depositing a layer of silicon dioxide or silicon nitride which is a sacrificial layer on top of support structure; ii. depositing a first layer of metal catalyst onto said sacrificial layer; iii. depositing a conductive layer onto said first layer of metal catalyst to form resistor structure and contact pads; characterized in that said method of fabricating nanostructured sensing device further comprising the following steps after Step iii: iv. etching of said sacrificial layer, said conductive layer and said first layer of metal catalyst to form a mould for hinge pad to reflow; v. depositing a second layer of metal catalyst on top of said resistor structure; vi. etching part of said sacrificial layer which is under said resistor structure; vii. growing plurality of sensing elements on at least one surface of resistor structure; viii. depositing said hinge pad; ix. reflow of said hinge pad substantially above the material's eutectic melting temperature to lift up said resistor structure.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Other aspect of the present invention and their advantages will be discerned after studying the Detailed Description in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a nanostructured sensing device of the present invention.

FIG. 2- A, FIG. 2-B and FIG. 2-C are the preparation flow of the three- dimensional out-of-plane structure based on surface tension forces of the hinge pad.

FIG. 3 is a process flow chart of the first embodiment for fabricating nanostructured sensing device of the present invention.

FIG. 4 is a cross-section view of said sensing device in a first embodiment of the fabrication process.

FIG. 5 is a process flow chart of the second embodiment for fabricating nanostructured sensing device of the present invention. FIG. 6 is a cross-section view of said sensing device in a second embodiment of the fabrication process.

5. DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those or ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and/ or components have not been described in detail so as not to obscure the invention.

The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings which are not drawn to scale.

Referring to FIG. 1, there is shown a perspective view of a nanostructured sensing device comprises of a support structure (101), at least one suspended resistor structure (103) which is formed substantially perpendicular to said support structure (101) and a plurality of sensing elements (209) being assembled onto said resistor structure (103), wherein said resistor structure (103) is anchored to said support structure (101) via at least one hinge pad (105). Said support structure (101) includes a substrate comprises of silicon or any other structure such as glass, polymer or metal. Said resistor structure (103) is a meander or parallel wire type structure. The resistor structure is of a conductive material, typically metals. Typically resistor has structure that lies flat or in-plane with the substrate as in FIG. 1 and FIG. 2-A, while the resistor structure of the present invention is lifted up perpendicular to the substrate as illustrated in FIG. 2-C. Said hinge pad (105) is used to lift up said resistor structure (103) during reflow.

Referring to FIG. 2-A, FIG. 2-B and FIG. 2-C, there is shown the preparation flow of the three-dimensional out-of-plane structure based on surface tension forces of said hinge pad (105) which is also a cross section views on the line A- A' of FIG.l. The material being used for said hinge pad (105) can be solder, polymer or borophosphosilicate (BPSG). The deposition of solder which act as hinge pad can be carried out by techniques such as plating, evaporation or lithography lift off, while BPSG was deposited by repetitive spin coating and rapid thermal annealing of sol gel. In silicon based process, said resistor structure (103) is formed from polysilicon, wherein one end portion of said resistor structure (103) is attached to another end portion of said hinge pad (105). Said resistor structure (103) act as mechanical parts lie beneath said hinge pad (105) and therefore said resistor structure (103) must be fabricated first on a sacrificial structure. Then said hinge pad (105) is deposited on said resistor structure (103). All layers except the sacrificial material must be immune to the undercut etchant The etchant used only etches the sacrificial material and not the other structures. For example, if the sacrificial is resist, the etchant is typically solvent which does not affect the metal resistor structure. If the sacrificial material is oxide, then hydrofluoric acid is typically used and it also should not affect the metal structures. When said hinge pad (105) is heated to the melting point, the hinge pad will deform due to the reduction of the free surface perimeter by rotation of said hinge pad and its decreases reduce its surface energy, as shown in FIG. 2-B. The decrease in free energy may exceed the work needed to rotate said resistor structure (103). The energy given up could carry out and raise the center of the gravity of said resistor structure (103) and the geometry will stabilize when a balance among torques is achieved. At this point the temperature may be lowered to freeze or to resolidified said hinge pad (105) as in FIG. 2-C.

Said sensing device of the present invention can be fabricated by two different approaches, wherein the first approach is said hinge pad (105) being deposited first and followed by the grow of said plurality of sensing elements (209) on both top and bottom of said resistor structure (103). In the second approach, said plurality of sensing elements (209) is grown before said hinge pad (105) is deposited. Both of the two approaches will be discussed in detail respectively. Referring to FIG. 3, there is shown a process flow chart for fabricating said nanostructured sensing device of the present invention, wherein the first embodiment involves deposition of said hinge pad (105) being carried out before said plurality of sensing elements (209) is grown. This is further substantiated by FIG. 4, showing a cross-section view of said sensing device in a first embodiment of the fabrication process. The fabrication process begins by depositing a layer of silicon dioxide or silicon nitride (302) on top of said support structure (101) which is a substrate comprises of silicon (301). This layer will act as insulating layer and sacrificial layer (201), whereby the deposited silicon dioxide is grown by using thermal oxidation method or other methods such as physical vapour deposition (PVD) method or chemical vapour deposition (CVD) method or silicon nitride deposited by PVD or CVD methods. A first layer of metal catalyst (203) is then deposited onto said sacrificial layer (303) by means of PVD method or CVD method with materials selected from a group comprising but not limited to gold (Au), cobalt (Co), iron (Fe), nickel (Ni), indium (In) and copper (Cu). This is followed by deposition of a thick conductive layer (304) on top of said metal catalyst (203) by PVD method or CVD method. The said conductive layer is typically of thickness less than 3μηι. Said conductive layer (205) is also a resistor layer which will form the resistor structure (103) and contact pads (206) with materials selected from a group comprising but not limited to gold (Au), platinum (Pt), nickel (Ni), tungsten (W), cobalt(Co) and copper (Cu). Upon completion of depositing said sacrificial layer (201), said conductive layer (205) and said first layer of metal catalyst (203), etching of all of said three layers (305) is carried out in order to forsm a mould for said hinge pad (105) to reflow. Said etching step can be carried out by means of argon plasma or in a wet chemical solution. Thereafter, a second layer of metal catalyst is deposited (306) on top of said resistor structure (103), followed by depositing said hinge pad (307). The material being used for said hinge pad (105) can be solder, polymer or borophosphosilicate (BPSG). The deposition of solder which act as hinge pad can be carried out by techniques such as plating, evaporation or lithography lift off, while BPSG is deposited by repetitive spin coating and rapid thermal annealing of sol gel. Then part of said sacrificial layer (201) which is under said resistor structure (103) is then being etched (308) by buffered hydrofluoric acid (HF) in order to expose the bottom of said first layer of metal catalyst (203). Thus, the growing of said plurality of sensing elements (309) is now being grown on at least one flat surface of said resistor structure, which is at the top and / or bottom of said resistor structure through the exposed layer of said metal catalyst. Preferably, said plurality of sensing elements (209) is nano structured element, comprises of a plurality of nanotubes, nanowires or nanoparticles which can be grown by a method selected from the group of chemical vapour deposition (CVD), Metalorganic chemical vapour deposition (MOCVD), plasma enhanced chemical vapor deposition (PECVD), hot wire chemical vapour deposition (HWCVD), atomic layer deposition (ALD), electrochemical deposition, solution chemical deposition and combinations thereof. Said nanostructured sensing element can comprises of a single type of nanotube or nanowire or combination thereof. Said nano structure materials includes but not limited to carbon, silicon, metal, metal oxides (such as zinc oxide and tungsten oxide) or a combination thereof. The growth temperature of said sensing elements (209) is lower than the eutectic melting point of said hinge pad (105). Upon completion of said growing of said sensing elements (209) on said resistor structure (103), reflow of said hinge pad (310) is carried out substantially above the material's eutectic melting temperature to lift up said resistor structure. Said hinge pad (105) is positioned between said suspended resistor structure (103) and said device electrical contact pad (206) to rotate the resistor structure out-of-plane by surface tension forces. Once said hinge pad (105) reach the equilibrium, said hinge pad (105) is allowed to cool down and re-solidify. Hence the position of said resistor structure (103) with plurality of said sensing elements (209) is fixed on said support structure (101) via said hinge pad (105) and a nanostructured sensing device with three- dimensional out-of-plane resistor structure of the present invention is obtained.

Referring to FIG. 5, there is shown a process flow chart for fabricating said nanostructured sensing device of the present invention, wherein the second embodiment involves deposition of said hinge pad (105) being carried out after said plurality of sensing elements (209) is grown. This is further substantiated by FIG. 6, showing a cross-section view of said sensing device in a second embodiment of the fabrication process. The fabrication process begins by depositing a layer of silicon dioxide or silicon nitride (302) on top of said support structure which is a substrate comprises of silicon (302). This layer will act as insulating layer and sacrificial layer, whereby the deposited silicon dioxide is grown by using thermal oxidation method or other methods such as physical vapour deposition (PVD) method or chemical vapour deposition (CVD) method or silicon nitride by PVD or CVD methods. A first layer of metal catalyst is then deposited (303) onto said sacrificial layer (201) by means of PVD method or CVD method with materials selected from a group comprising but not limited to gold (Au), cobalt (Co), iron (Fe), nickel (Ni), indium (In) and copper (Cu). This is followed by deposition of a thick conductive layer (304) on top of said metal catalyst by PVD method or CVD method. The said conductive layer is typically of thickness less than 3μπι. Said conductive layer (205) is also a resistor layer which will form the resistor structure (103) and contact pads (206) with materials selected from a group comprising but not limited to gold (Au), platinum (Pt), nickel (Ni), tungsten (W), cobalt(Co) and copper (Cu). Upon completion of depositing said sacrificial layer (201), said conductive layer (205) and said first layer of metal catalyst (203), etching of all of said three layers (305) is carried out in order to form a mould for said hinge pad to reflow. Said etching step can be carried out by means of argon plasma or in a wet chemical solution. Thereafter, a second layer of metal catalyst is deposited (306) on top of said resistor structrue (103), followed by part of said sacrificial layer (201) which is under said resistor structure layer is being etched (507) by buffered hydrofluoric acid (HF) in order to expose the bottom of said first layer of metal catalyst (203). Thus, the growing of said plurality of sensing elements (508) is now being grown on at least one flat surface of said resistor structure (103), which is at the top and / or bottom of said resistor structure (103) through the exposed layer of said metal catalyst. Preferably, said plurality of sensing elements (209) is nano structured element, comprises of a plurality of nanotubes, nanowires or nanoparticles which can be grown by a method selected from the group of chemical vapour deposition (CVD), Metalorganic chemical vapour deposition (MOCVD), plasma enhanced chemical vapor deposition (PECVD), hot wire chemical vapour deposition (HWCVD), atomic layer deposition (ALD), electrochemical deposition, solution chemical deposition and combinations thereof. Said nanostructured sensing element can comprises of a single type of nanotube or nanowire or combination thereof. Said nano structure materials includes but not limited to carbon, silicon, metal, metal oxides (such as zinc oxide or tungsten oxide) or a combination thereof. When, the growth temperature of said sensing elements is higher than the eutectic melting point of said hinge pad, then the deposition of said hinge pad (509) is carried out upon completion of said growing of said sensing elements on said resistor structure (103). The material being used for said hinge pad can be solder, polymer or borophosphosilicate (BPSG). The deposition of solder which act as hinge pad can be carried out by techniques such as plating, evaporation or lithography lift off, while BPSG is deposited by repetitive spin coating and rapid thermal annealing of sol gel. Reflow of said hinge pad (510) is then carried out substantially above the material's eutectic melting temperature to lift up said resistor structure. Said hinge pad is positioned between said suspended resistor structure (103) and said device electrical contact pad to rotate the resistor structure out-of-plane by surface tension forces. Once said hinge pad (105) reach the equilibrium, said hinge pad (105) is allowed to cool down and resolidify. Hence the position of said resistor structure (103) with plurality of said sensing elements (209) is fixed on said support structure (101) via said hinge pad (105) and a nanostructured sensing device with three-dimensional out-of-plane resistor structure of the present invention is obtained. The present invention demonstrates a joint used to obtain the out of plane for lifting up said resistor structure with said plurality of sensing elements. The operating of said out of plane nanostructured sensing device is based on the change in electrical resistance. As a general, when compared to the conventional devices, said nanostructured sensing element of the present invention would cover almost all of said resistor structure active area, and therefore giving separation from substrate and capable to sense the concentration of gasses without waiting for the gasses to flow downwards. Therefore, this in turn enhances the sensitivity and provides quick respond time of the sensor. While the present invention of nanostructured sensing device can be used in environmental monitoring, the present invention is not restricted to this but may alternatively be applied to other areas such as detection of anti terrorism gas, toxic gas, odor in industries and the like.

While the preferred embodiment of the present invention and its advantages has been disclosed in the above Detailed Description, the invention is not limited thereto but only by the scope of the appended claim.

Claims

WHAT IS CLAIMED IS:

1. A nanostructured sensing device comprising: a support structure (101); at least one resistor structure (103); a plurality of sensing elements (209); characterized in that said resistor structure (103) is attached to said support structure (101) via at least one hinge pad (105) to obtain a three dimensional out-of-plane nanostructured sensing device.

2. A nanostructured sensing device as claimed in Claim 1 wherein said support structure (101) is a substrate comprises of silicon or any other structure such as glass, polymer or metal.

3. A nanostructured sensing device as claimed in Claim 1 wherein said resistor structure (103) is a meander or parallel wire type structure.

4. A nanostructured sensing device as claimed in Claim 1 wherein said resistor structure (103) is formed from polysilicon, wherein one end portion of said resistor structure (103) is attached to another end portion of said hinge pad (105).

5. A nanostructured sensing device as claimed in Claim 1 wherein said resistor structure (103) is substantially perpendicular to said support structure (101) due to the surface tension force provided by said hinge pad (105), thus creating said three dimensional out-of- plane structure.

6. A nanostructured sensing device as claimed in Claim 1 wherein the material used for said hinge pad (105) can be solder, polymer or borophosphosilicate (BPSG).

7. A nanostructured sensing device as claimed in Claim 1 wherein said plurality of sensing elements (209) are grown on a layer of metal catalysts, which is attached to at least one flat surface of said resistor structure (103).

8. A nanostructured sensing device as claimed in Claim 1 wherein said plurality of sensing elements (209) is nano structured element, comprises of plurality of nanotubes, nanowires or nanoparticles or combination thereof.

9. A nanostructured sensing device as claimed in Claim 1 wherein said plurality of sensing elements (209) are made of material comprising of carbon, silicon, metal, metal oxides or a combination thereof.

10. A nanostructured sensing device as claimed in Claim 1 further comprising a sacrificial layer (201) which is deposited on top of said support structure (101).

11. A nanostructured sensing device as claimed in Claim 10 wherein said sacrificial layer (201) is a layer of silicon dioxide or silicon nitride.

12. A nanostructured sensing device as claimed in Claim 10 further comprising a first layer of metal catalyst (203) deposited onto said sacrificial layer (201) before deposition of said hinge pad (105) on top of said sacrificial layer (201).

13. A nanostructured sensing device as claimed in Claim 12 further comprising a contact pad (206) deposited onto said first layer of metal catalyst (203).

14. A nanostructured sensing device as claimed in Claim 13 wherein said resistor structure (103) and said contact pad (206) are made of material comprising of gold, platinum, nickel, tungsten, cobalt or copper.

15. A nanostructured sensing device as claimed in Claim 13 further comprising a second layer of metal catalyst (207) deposited onto said resistor structure (103).

16. A nanostructured sensing device as claimed in Claim 12 or Claim 15 wherein said layer of metal catalyst (203, 207) are made of material comprising of gold, cobalt, iron, nickel, indium or copper.

17. A method of fabricating nanostructured sensing device comprising steps of: i. depositing a layer of silicon dioxide or silicon nitride which is a sacrificial layer on top of support structure (302); ii. depositing a first layer of metal catalyst onto said sacrificial layer (303); iii. depositing a conductive layer onto said first layer of metal catalyst to form resistor structure and contact pads (304); characterized in that said method of fabricating nanostructured sensing device further comprising the following steps after Step iii: iv. etching of said sacrificial layer, said conductive layer and said first layer of metal catalyst to form a mould for hinge pad to reflow (305); v. depositing a second layer of metal catalyst on top of said resistor structure (306); vi. depositing said hinge pad (307); vii. etching part of said sacrificial layer which is under said resistor structure (308); viii. growing plurality of sensing elements on at least one surface of resistor structure (309); ix. reflow of said hinge pad substantially above the material's eutectic melting temperature to lift up said resistor structure (310).

18. A method of fabricating nanostructured sensing device comprising steps of: i. depositing a layer of silicon dioxide or silicon nitride which is a sacrificial layer on top of support structure (302); ii. depositing a first layer of metal catalyst onto said sacrificial layer (303); iii. depositing a conductive layer onto said first layer of metal catalyst to form resistor structure and contact pads (304);

^" characterized in that said method of fabricating nanostructured sensing device further comprising the following steps after Step iii: iv. etching of said sacrificial layer, said conductive layer and said first layer of metal catalyst to form a mould for hinge pad to reflow (305); v. depositing a second layer of metal catalyst on top of said resistor structure (306); vi. etching part of said sacrificial layer which is under said resistor structure (507); vii. growing plurality of sensing elements on at least one surface of resistor structure (508); viii. depositing said hinge pad (509); ix. reflow of said hinge pad substantially above the material's eutectic melting temperature to lift up said resistor structure (510).

19. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of depositing sacrificial layer on top of support structure (301) comprises using thermal oxidation method, physical vapour deposition method or chemical vapour deposition method.

20. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of depositing a layer of metal catalyst (303, 306) comprises using physical vapour deposition method or chemical vapour deposition method.

21. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of depositing conductive layer onto said first layer of metal catalyst (304) comprises using physical vapour deposition method or chemical vapour deposition method.

22. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of etching said sacrificial layer, said conductive layer and said first layer of metal catalyst (305) can be carried out by means of argon plasma or in a wet chemical solution.

23. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of depositing said hinge pad (307, 509) can be carried out by techniques such as plating, evaporation, lithography lift off, repetitive spin coating and rapid thermal annealing of sol gel.

24. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of etching part of said sacrificial layer (308, 507) which is under said resistor structure is carried out by means of buffered hydrofluoric acid.

25. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of growing plurality of sensing elements on at least one surface of resistor structure (309, 508) comprises using chemical vapour deposition, metalorganic chemical vapour deposition, plasma enhanced chemical vapour deposition, hot wire chemical vapour deposition, atomic layer deposition, electrochemical deposition, solution chemical deposition or combinations thereof towards the top and / or bottom surface of said resistor structure.

26. A method of fabricating nanostructured sensing device as claimed in Claim 17 or Claim 18 wherein said step of reflow said hinge pad substantially above the material's eutectic melting temperature (310, 510) is achieved by performing the following sub-steps: i. rotating of said resistor structure out-of-plane by surface tension forces; ii. allowing said hinge pad to cool down after said hinge pad reach equilibrium; iii. re-solidifying said hinge pad.

27. A method of fabricating nanostructured sensing device as claimed in Claim 17 wherein the growth temperature of said plurality of sensing elements (209) is lower than the eutectic melting point of said hinge pad (105).

28. A method of fabricating nanostructured sensing device as claimed in Claim 18 wherein the growth temperature of said plurality of sensing elements (209) is higher than the eutectic melting point of said hinge pad (105).