WO2022146393A2

WO2022146393A2 - A silicon-based closed and integrated platform for the investigation of radiation transfer at micro-nano scale

Info

Publication number: WO2022146393A2
Application number: PCT/TR2021/051588
Authority: WO
Inventors: Elif Begum ELCIOGLU; Hanife Tuba OKUTUCU OZYURT; Mustafa Pinar MENGUC
Original assignee: Orta Dogu Teknik Universitesi; Ozyegin Universitesi; Eskisehir Osmangazi Universitesi; Eskisehir Teknik Universitesi; Istanbul Teknik Universitesi
Priority date: 2020-12-31
Filing date: 2021-12-29
Publication date: 2022-07-07
Also published as: TR202022603A1; WO2022146393A3

Abstract

The invention is a closed and integrated NFR platform (12) for inspection of radiation transfer at micro-nano scale, and comprises of an emitter (5) comprises of a silicon carbide thin film (2) coated on a silicon substrate (1), a receiver (6) comprising a silicon carbide thin film (2) coated on a silicon substrate (1). The silicon carbide thin films (2) of the emitter (5) and the receiver (6) are coated and bonded under vacuum along their patterned contact surfaces, silicon dioxide intermediate pillars such that distance between the emitter (5) and the receiver (6) is smaller than thermal radiation wavelength and parallel to each other. The attained integrated structure (7) at wafer size is diced to obtain 3cmx3cm chips. The fabrication method of the NFR platform (12) is within the scope of the invention.

Description

A SILICON-BASED CLOSED AND INTEGRATED PLATFORM FOR THE INVESTIGATION OF RADIATION TRANSFER AT MICRO-NANO SCALE

Field of the Invention

The invention relates to a silicon-based, closed and integrated near-field radiation (NFR) platform developed for the inspection of radiation transfer at the micro- and nano scale and the production method thereof. The production method of the aforementioned platform is based on micro-nano fabrication techniques.

Known State of the Art

When the distance (d) between two objects kept at different temperatures is smaller than the thermal radiation wavelength (I), the heat transfer between the objects by radiation is named near-field radiation (NFR). NFR transfer is observed when the distance (d) between materials supporting surface waves is smaller than the dominant wavelength (I) that is used as a scale according to Planck's law. This wavelength should be less than 10 pm at room temperature. Therefore, NFR transfer can also be defined as radiation transfer at the micro-nano scale.

While the distance between the objects where the radiation heat transfer takes place must be at a micro-nano scale in order for the NFR to occur, these objects themselves do not need to be of micro- nano size.

Depending on the structure of the objects, the heat transfer by NFR can exceed the blackbody limit by several orders of magnitudes (e.g., more than 1000 times) at certain wavelengths. For example, the transfer of NFR between two mutually placed objects at a temperature of 1000 K, and at a distance d = 100 nm between the emitter and the receiver is 7525 times higher for the gallium nitrate (GaN) emitter-receiver pair, 4168 times higher for the silicon carbide (SiC) emitter-receiver pair, and 3307 times higher for the cubic boron nitride (cBN) emitter -receiver pair than the blackbody limit, at certain wavelengths. These increases have application-based potential to address the need for environmentally-sensitive use of energy.

Precise determination of NFR between two bodies is possible by isolating the amount of radiation heat transfer through the elimination of conduction and convection heat transfer mechanisms. For this purpose, NFR is measured in vacuum chambers by adjusting very sensitive (nanometric precision) distances, planar and angular positions of the high-temperature object (emitter) and the low-temperature object (receiver) with the help of a micro-nano positioner so that d would be less than X. In addition to the micro-nano positioner, the mentioned systems require the use of a heater for keeping the emitter at a high temperature, a cooler for keeping the receiver at a low temperature and monitoring of emitter and receiver temperatures, and measurement of the heat transfer between the emitter and the receiver. These systems also need to be surrounded by costly and complex vacuum systems that require specialized expertise and manpower, as well as simultaneous control, monitoring and recording of a plurality of measurement parameters such as ambient vacuum level.

The fundamental configuration, which includes parallel plates for theoretical and experimental investigation of NFR is shown in Figure-1. More specifically, Figure-1 shows the emitter (object at high temperature), the receiver (object at low temperature) and vacuum between the emitter and the receiver. The distance between the emitter and the receiver is d < I. Heat input and cooling are indicated by arrows.

Systems developed worldwide by which NFR is investigated operate by bringing objects closer to each other by mechanical assemblies in artificially created controlled vacuum environments. These systems are useful for measurements of NFR but they are still considered to be in research and laboratory phase. Many researchers report the necessity and difficulty of precisely determining the distance (d) between the emitter and receiver.

The main difficulties in the systems for the inspection of NFR in the literature are to ensure a uniform distance between the emitter and the receiver, to maintain and repeatability of the mentioned distance, and to ensure parallelism between the emitter and the receiver.

The document titled “Journal of Heat Transfer” (G. A. Domoto, R. F. Boehm, C. L. Tien, 1970, 412-416) reports difficulties faced during NFR experiments, such as parallel alignment of emitter and receiver, and providing a uniform distance therebetween. In "Applied Physics Letters 106” (K. Ito, A. Miura, H. lizuka, H. Toshiyoshi, 2015, 083504) the distance d between the emitter and the receiver was adjusted using separator micro-pillars and it has been observed that the distance between the emitter and the receiver may be smaller than the pillar height due to the deformation caused by the pressure applied to position the emitter and the receiver during measurements. In the study of “Applied Physics Letters 92” (L. Hu, A. Narayanaswamy, X. Chen, G. Chen, 2008, 133106), measurements were made for the distance of d=l pm between the objects, however, it has been reported that the measurement results were consistent with the theoretical results they obtained for the distance of d=1.6 pm. The difference of 60% is significant and it is predicted that this may be caused by size differences of the polystyrene particles placed between the emitter and the receiver to ensure the distance therebetween. The document titled “Physical Review Letters 120” (M. Ghashami, H. Geng, T. Kim, N. lacopino, S. K. Cho, K. Park, 2018, 175901) reports that even if the bottom stage of the system carrying the receiver is tilted by an angle of ±0.002°, it disrupts the emitter-receiver parallelism and changes the NFR ratio by ±5%. In the study titled “Nature Photonics ” (E. Rousseau, A. Siria, G. Jourdan, S. Volz, F. Comin, J. Chevrier, J-J. Greffet, 2009, 3, 514-517) a sphere-plate configuration, instead of the flat plate -plate configuration was investigated considering the importance of the emitter -receiver parallelism and the difficulty of ensuring the same.

In theoretical studies, emitter-receiver pairs with uniform micro-nano distances therebetween, in perfect parallelism with each other and with smooth surfaces are considered as the ideal NFR system. Although the applications closest to the above-mentioned ideal system are developed with highly sensitive and high-technology methods and carried out in a controlled vacuum environment, they have problems related to distance (d), parallelism, and repeatability.

Unlike the vacuum chamber-based NFR platforms, which are the general trend in the technique, a platform intended to work under standard environmental conditions is reported in "FABRICATION OF NANOSTRUCTURED SAMPLES FOR THE INVESTIGATION OF NEAR FIELD RADIATION TRANSFER” (Z. Artvin, 2012, Master's Thesis, Middle East Technical University). The aforementioned document is about samples containing SiOz-coatcd Si wafers and manufactured by MEMS fabrication techniques to measure NFR effects. In the mentioned document, different numbers of chips (samples) with a surface area of 1 mm x 1 mm, 2 mm x 2 mm, 5 mm x 5 mm and 20 mm x 20 mm are fabricated in a permanently joined structure. In the mentioned document, four structures are separated from each other depending on the distance d (25 nm, 50 nm, 100 nm, 200 nm) between parallel positioned Si samples, on which the SiO was grown. The applicability of 1 mm x 1 mm, 2 mm x 2 mm and 5 mm x 5 mm structures involves certain challenges for the use of equipment such as a heater plate to be mounted on the emitter side of the sample, a heat sink to be mounted on the receiver side of the sample, a temperature meter and a heat flux meter. It is possible for the parallel parts separated by a distance d to collapse and come into contact with each other in structures containing trapped vacuum therein and those that would work under atmospheric conditions. One of the two structures of 20 mm x 20 mm mentioned in the document is located in the pair of wafers bonded as a whole and it is seen that this structure only has outer walls. However, the document does not disclose the platform and derivatives thereof containing SiC that enables it to support surface phonon polaritons.

The document titled "IMPACTS OF MATERIAL TYPES AND FABRICATION METHODS TO ENHANCE NEAR FIELD RADIATIVE TRANSFER FOR ENERGY HARVESTING" (Elif Begum Elcioglu, Tuba Okutucu Ozyurt, M. Pinar Menguc) may be referred as another example of the current state of the art. The aforementioned document examines the effect of material selection on the analysis of NFR and the fabrication of energy harvesting devices. The document mentions a general production method of NFR energy harvesting devices and in more detail the devices containing SiC coated samples. The fabrication method in its most general form includes thin film deposition, lithography, etching, wafer bonding, and dicing process steps. The document does not provide detailed information about the parameters and related surfaces of each of the fabrication techniques. In addition, a platform that provides the distance d and parallelism between the emitter and the receiver is not disclosed in the document.

In order to eliminate the above-mentioned disadvantages, a closed and integrated NFR platform has been developed to provide a solution to the problems of providing a uniform distance between the emitter and the receiver, maintaining the uniform distance and ensuring its repeatability, in order to investigate the NFR under atmospheric conditions without requiring a vacuum outside the platform.

Detailed Description of the Invention

The invention relates to a silicon (Si)-based, closed and integrated NFR platform (12) developed for the inspection of NFR and to the fabrication method of this NFR platform (12). In more detail, the invention includes Si-based micro-nano fabrication processes, and silicon carbide (SiC) and silicon dioxide (S iCC) materials. The fabrication method of the NFR platform (12) of the invention is based on various micro-electro-mechanical systems (MEMS) approach and fabrication steps.

The invention is in the intersection area of mechanical engineering, electrical-electronics engineering, material science and engineering, energy systems engineering, and physics.

One objective of the invention is to obtain the energy output that can be used in today's applications demanding high efficiency and low carbon footprint, by using radiation heat transfer, which is achievable at micro-nano scale and amounts to order of magnitudes higher rates compared to the macroscale. Therefore, a device in the form of a Si-based, closed and integrated NFR platform (12) and the fabrication method thereof have been developed by going beyond the controlled laboratory environment with the appropriate quality and temperature of waste heat input, by selecting appropriate materials and configuration. Silicon carbide (SiC) is another main material of the device/NFR platform (12) developed owing to its high efficiency and suitability for use in Si-based micro-nano fabrication techniques.

The invention is a closed and integrated NFR platform (12) for the inspection of radiation transfer at micro-nano scale, comprising an emitter (5) comprising a silicon carbide thin film (2) coated on a silicon substrate (1), a receiver (6) comprising a silicon carbide thin film (2) coated on a silicon substrate (1), silicon dioxide intermediate pillars coated on the silicon carbide thin films (2) of the emitter (5) and receiver (6) and wherein the silicon dioxide intermediate pillars acts as a contact surface between the emitter (5) and the receiver (6), when the emitter (5) and the receiver (6) are bonded in a vacuum environment such that the emitter (5) and the receiver (6) are parallel to each other and the distance between them is smaller than thermal radiation wavelength (X) and wherein the contact surfaces of the mentioned intermediate pillars are patterned.

In an embodiment of the invention, the pattern is the pattern of the thick square wall (8), the thin square wall (9), the column (10) and of the hexagonal honeycomb (11).

In an embodiment of the invention, the silicon dioxide thin films (3) are patterned to have mirror symmetry with each other and bonded.

In an embodiment of the invention, the silicon substrates (1) of the emitter (5) and the receiver (6) comprise codes defining the contact surface pattern.

In an embodiment of the invention, the size of the NFR platform (12) is 3 cm x 3 cm.

The fabrication method of the closed and integrated NFR platform (12) developed for the inspection of radiation transfer at the micro-nano scale of the invention is also within the protective scope of the invention.

The fabrication method of the closed and integrated NFR platform (12) developed for the inspection of radiation transfer at the micro-nano scale of the invention in its most general form comprises the following process steps; a. obtaining an emitter (5) by coating a silicon carbide thin film (2) on a silicon substrate (1) and obtaining a receiver (6) by coating a silicon carbide thin film (2) on a silicon substrate (1), b. coating on the silicon carbide thin films (2) of the emitter (5) and the receiver (6) with a silicon dioxide thin film (3) to form intermediate pillars, c. patterning the surfaces of the mentioned silicon dioxide thin film (3), d. closing by bonding the emitter (5) and the receiver (6) under vacuum such that the contact surface is patterned and the distance between the emitter (5) and the receiver (6) is smaller than the thermal radiation wavelength (I) and the emitter (5) and the receiver (6) are parallel to each other, e. obtaining a single NFR platform (12) by dicing the integrated structure (7) obtained. In an embodiment of the invention, in step c, it is patterned with the pattern of thick square wall (8), thin square wall (9), column (10) and/or hexagonal honeycomb (11).

In an embodiment of the invention, the silicon carbide thin film (2) is coated by RF magnetron sputtering technique in step a.

In an embodiment of the invention, the silicon carbide thin film (2) is coated by RF magnetron sputtering technique with an integrated SiC target.

In an embodiment of the invention, the silicon carbide thin film (2) is coated by RF magnetron sputtering technique with a monolithic SiC target.

In an embodiment of the invention, the silicon dioxide thin film (3) is coated by the plasma- enhanced chemical vapor deposition technique in step b.

In an embodiment of the invention, the surfaces of the silicon dioxide thin film (3) are patterned by photolithography technique in step c.

In an embodiment of the invention, the emitter (5) and the receiver (6) are bonded along the silicon dioxide contact surfaces coated by the plasma-enhanced chemical vapor deposition technique by chemical activation in step d.

In an embodiment of the invention, the emitter (5) and the receiver (6) are bonded along the silicon dioxide contact surfaces coated by the plasma-enhanced chemical vapor deposition technique by plasma activation in step d.

In an embodiment of the invention, the emitter (5) and the receiver (6) are bonded along the thermal oxide (S i O2) contact surfaces by plasma activation in step d.

In an embodiment of the invention, 4 NFR platforms (12) with a surface area of 3 cm x 3 cm are obtained by dicing from the joined integrated structure (7) in step e. The integrated structure (7) is the NFR platform (12) before it is reduced to 3 cm x 3 cm.

A NFR platform (12) of an embodiment of the invention is given in Figure-2b, and a perspective of the systems in which the NFR in the literature is investigated is provided in Figure -2a. As shown in Figure -2a, while the installation of the platform required for the investigation of NFR in the literature generally requires holding and positioning the emitter (5) and the receiver (6) with the material holder (13) as required by the system, each NFR platform (12) is produced with a determined d-distance value, as the inventive NFR platform (12) shown in Figure -2b is an integrated and closed system.

The fabrication stages of the NFR platform (12) of an embodiment of the invention are schematically outlined in Figure-3a. Silicon carbide thin film (2) deposition for the invented NFR device/NFR platform (12) was performed by RF magnetron sputtering method. Silicon dioxide thin film (3) deposition on silicon carbide thin film (2) was performed by plasma-enhanced chemical vapor deposition (PECVD) method. As can be seen in Figure-3a, the contact surfaces of Si materials coated with silicon carbide thin film (2) are silicon dioxide thin films (3). Selection of the contact surface with low thermal conductivity such as SiO is necessary in order to inspect the NFR in a closed system, since one of the bonded SiC coated Si wafers will be the emitter (5) by heating on one side and the other will be the receiver (6) by cooling on the other side. In order to examine the effect of contact surfaces on heat transfer by conduction, contact areas and shapes were created at different sizes. The contact areas and shapes of different sizes are thick square walls (8), thin square walls (9), columns (10), and hexagonal honeycomb column (11) and shown in Figure-3b. The inner surfaces of the materials formed by photolithography in such a way that the patterns on them are mirror images of each other are given in Figure-3b and the outer surfaces are given in Figure-3c before joining them in a vacuum environment. On the outer surface of the fabricated NFR platform (12), there are codes defining the internal pattern and the pattern related to these codes is formed by photolithography. Since this NFR platform (12) is to be used in atmospheric conditions and only the space where the NFR would take place would be vacuum, the bonding of the system was performed in a vacuum environment. After bonding, the structure whose outer surface is shown in Figure-3c was diced along the dashed lines to obtain 4 pieces of 3 cm x 3 cm NFR devices.

The fabrication method of the NFR platform (12) of the invention is described in more detail below. ) Silicon carbide thin film (2) deposition

Two different RF magnetron sputtering recipes have been developed: for the use of integrated SiC target material (2 diameter) and monolithic SiC target material (4" diameter) for coating Si wafers with SiC by RF magnetron sputtering. a) Developing the RF Magnetron Sputtering Recipe with integrated SiC target

In the integrated SiC target material, the SiC target is combined with a copper (Cu) plate, and the manufacturer aims to ensure effective heat management of the target during the process with the help of a high conductivity Cu plate and to protect the SiC target from thermal shocks. RF magnetron sputtering was initiated with the following recipe parameters developed using the integrated SiC target: 150 seem Ar flux, 75% inlet valve (gate valve) position (1.3x10 ² Torr pirani vacuum gauge value, 1.6xl0³ Torr ion gauge pressure value) and 15 rpm silicon substrate (1) rotation speed. Power increase-decrease rates in the deposition process for the use of the integrated target material have been determined by the manufacturer as 10 W/min. After the plasma was formed, the parameters were set to 100 seem Ar flow, 60% inlet valve position, 4.3 mTorr pirani vacuum gauge value, 1.3 mTorr ion gauge pressure value. When 62 W RF power was reached, the parameters were set as 100 seem Ar flow, 61% inlet valve position, and the substrate to be coated rotation speed at 15 rpm, and the coating was initiated. With this recipe, a deposition rate of approximately 1 nm/min was obtained. In the following processes, the same recipe was used for different durations and its repeatability was proven. Figure-4a and Figure -4b show the recipe developed for RF magnetron sputtering process with integrated target material and process voltage - RF power of the processes made with high repeatability (Figure -4a) and process durations corresponding to the value of silicon carbide thin film (2) read from the thickness monitor (TM) (Figure-4b). The developed recipe has high repeatability as shown in Figure -4a and Figure -4b. b) Developing the RF Magnetron Sputtering Recipe with a monolithic SiC target

Here, SiC is more sensitive to heating since the material cannot be kept together if the target material breaks due to thermal shocks due to the absence of a conductor (e.g. Cu) back plate in the monolithic target. To prevent overheating of the monolithic target, the coating recipe has been developed as follows: 150 W RF power, 3 mTorr process pressure and 50 seem Ar flow conditions, for 30 min process, 30 min stop (break), 30 min process (i.e., in an intermittent way). The process outputs are 148 W and 75 volts. As a result of the process, approximately 50 nm thick SiC film was obtained at the deposition rate of 0.833 nm/min with this recipe. ) Silicon dioxide thin film (3) coating

Silicon dioxide thin film (3) deposition on silicon carbide thin films (2) was performed by the PECVD method at 300 °C using the following values: 12 seem SiH4, 1420 seem N2O, 392 seem N2 flux, 550 mTorr process pressure, 60 W RF power. ) Patterning of silicon dioxide thin film (3) by photolithography

By the application of silicon dioxide thin film (3) on SiC coated samples by patterning, the bonding (contact) regions of the structure were formed.

The following are critical parameters in the design of SiCF contact areas: (i) ratio of radiation heat transfer area (A_r) to conduction heat transfer area (A_c), i.e., A_r/A_c, and (ii) bending of the surfaces due to the difference between the vacuum inside the device and the atmospheric pressure in the external environment. Heat transfer by conduction is present due to the contact between SiCh surfaces. However, the selection of contact surfaces as low conductivity SiCh keeps this mechanism less effective. Convection heat transfer can be neglected because of the vacuum gap (4) between SiC surfaces (due to the absence of a heat-carrying medium (e.g. gas) therebetween).

Since it is aimed to investigate the NFR between SiC coated Si media with the NFR platform (12) of the invention that allows the NFR to take place in a closed and integrated environment, the A_r/A_c value must be maximum in order to minimize the conduction heat transfer from the auxiliary SiO surfaces. Minimizing the expected bending due to the pressure difference between the cavity and the external environment is essential in order to prevent the contact of the emitter (5)- the receiver (6) in extreme bending situations and to obtain a uniform d distance as much as possible. In this context, 11 configurations were modelled. Models that best meet the both mentioned criteria, thin square walls (9), straight columns (10), and hexagonal honeycomb columns (11), and thick square walls (8)- a comparison model, are shown in Figure-5a to 5d. Figure-6 shows the design of the photolithography mask used in the fabrication of the structures schematized in Figure-5a-5d. The photolithography mask containing the full symmetry of the aforementioned design was also produced and applied on the other wafer to be joined.

S1813, a positive photoresist (PR), was used for photolithography and the following steps were performed. i) Dehydration bake: Applied in the oven at 110 °C for 10 minutes. The material was removed from the oven when it reached room temperature. ii) Spin coating: For better adhesion of PR onto the sample, HDMS was applied to the surface with a 30-second spin coating at 3000 rpm. Then PR was coated with the same parameters. iii) Soft bake: Applied using the hot plate at 115 °C for 1 minute. iv) UV light exposure: Applied using EVG620 for 5 seconds. v) Developing: Applied using MF319 for 60 seconds. vi) Hard bake: Applied in the oven at 110 °C for 5 minutes. The sample was kept in the oven until the sample temperature dropped to 70°C or below.

The structure after step vi was immersed in (1 :7) buffered hydrofluoric acid (buffered HF) and SiO was etched, the sample was immersed in PRS-2000, and washed with deionized water after PR was removed. ) Bonding of the SiC coated Si wafer pair from their patterned SiO? surfaces under vacuum Wafer bonding is the permanent joining of two aligned wafers. The fusion bonding technique was employed in the fabrication of the NFR platform (12) of the invention in bonding of SiC coated Si wafers (emitter (5) and receiver (6)) from the SiO contact surface. The outer surface of the samples with the patterns shown in Figure-5a to 5d applied by photolithography on the inner surface was also patterned. The patterns transferred to the inner and outer surface of the structure are schematically shown in Figure-3b and Figure-3c. There is a risk of contamination on the processed surfaces due to the fact that the photolithography process performed for patterning purposes requires contact with the material (the material is placed on the hot plate, placed in ovens with various sample holders and subjected to heating process, etc.) On the other hand, fusion bonding is highly sensitive to roughness and particle contamination on the surfaces to be bonded. During the photolithography stage of the samples, it is important to protect the surfaces and to minimize particle contamination, given that both sides of the sample will contact with various surfaces. a. Wafer bonding

Since fusion bonding depends on the structure and roughness of the surface to be bonded, this process has been carried out in the following ways: al. by chemical activation along SiO surfaces coated by PECVD, a2. by plasma activation along SiO? surfaces by PECVD, a3. by plasma activation along SiO? surfaces grown onto Si by thermal oxidation. al. Bonding along PECVD SiO? contact surfaces (by chemical activation): In this inspection, the 200 nm thick silicon dioxide thin film (3), the inner surface of which is as illustrated in Figures-5a to 5d, was coated and patterned directly on the Si wafer using PECVD. This sample was combined with an unpatterned 200 nm PECVD silicon dioxide thin film (3) coated Si wafer. Since the silicon carbide thin film (2) does not have a direct effect on the bonding stage, the silicon carbide thin film (2) was not included in this investigation. The stages of bonding are as outlined below.

1- PECVD silicon dioxide thin film (3) deposition (Since the deposition was performed previously, the wafer pair was cleaned in a piranha solution to prevent contamination from the carrier box.)

3- Oxide densification: Performed under vacuum using EVG520 at 300°C for 1.5 hours.

4- Chemical activation: Performed using NFUOELFbOz^O (6:1:3) solution, as described in the documents titled “RSC Advances 5” (C. Mai, M. Li, S. Yang, 2015, 42721) and “RSC Advances 6”( C. Mai, J. Sun, H. Chen, C.-K. Mai, M. Li, 2016, 37079-37084). The samples to be bonded were kept in the activation solution at 80 °C for 30 minutes. The samples were then rinsed with deionized water for 5 minutes and dried under vacuum.

5- Fusion bonding: It was performed using EVG520IS by applying 10 kN force at 300°C for 1.5 hours under vacuum on the samples to be bonded. 6- Characterization: At this stage, inspection was performed with c-SAM (scanning acoustic microscope) at 200 MHz. Figure- 7 shows that the 10 kN force applied for the bonding does not cause the upper sample to collapse on the lower sample. Darker areas indicate the contact areas and lighter areas indicate the areas that do not have contact each other and have vacuum media therebetween. The bonding occurred particularly in the middle of the structure and towards the outer wall of the wafer.

After the inspection to obtain a high -resolution (10 pm) c-SAM image, it is observed that the bonding between the two wafers was not preserved. This high-resolution inspection lasted for 6 hours. For this reason, it can be said that the integrated structure (7) remains joined for less than 6 hours after bonding. a2. Bonding along PECVD SiCF contact surfaces (by plasma activation): For this process, Si wafers coated with 100 nm thick PECVD silicon dioxide thin film (3) coated on 50 nm silicon carbide thin film (2) are patterned as shown in Figures-5a to 5d, and then they were activated and joined using O2 plasma for 60 seconds. Figure-8a and 8b characterization of c-SAM as a result of fusion bonding shows that the wafers are partially bonded. Especially in the part where the pillars are located, it is observed that the bonding is better than other regions. As in the al process, the bonding between these two has not been permanent. a3. Bonding along thermal oxide (\SiO2) contact surfaces (by plasma activation): In this process Si wafers on which 1.2 pm -thick silicon dioxide thin film (3) is grown by thermal oxidation, are bonded. In previous fusion bonding trials, in case trapped gases existed in the samples, the wafer pairs were first heated to 300 °C and then contacted by applying 10 kN force to release them before bonding. In this trial (a3), the wafer pair was first contacted, then heated at 300°C. Other process steps were kept the same. The result of c-SAM characterization after fusion bonding is shown in Figure -9. When Figure -9 is reviewed, it is seen that the two wafers are successfully and permanently bonded. As can be seen from the dark color on the unpatterned part of the wafer, sufficient contact has occurred between the SiO surfaces. There is good bonding quality especially in the upper left (thick square wall (8)) lower right (column (10)) structure.

5) Obtaining the NFR platform (12) by dicing the integrated structure (7)

Since, it is desired to obtain 4 chips (NFR test sample, NFR platform (12)) with a surface of 3 cm x 3 cm by dicing the integrated structure (7) as a last step, in order to prevent the dicing process from damaging the chips and SiO walls, the outer surface pattern shown in Figure-3c and the identifiers of the geometries in Figure-5a to 5d were applied to the outer side of the integrated structure (7). The integrated structure (7) was diced along the dashed lines shown in Figure- 10. The flat cut (FC) cutting speed was applied as 1 mm/min in the process.

Thanks to the silicon-based closed and integrated platform of the invention, radiation transfer at micro-nano scale can be inspected under atmospheric conditions, standard operating conditions, without requiring a vacuum environment outside the NFR platform (12). Patterned silicon dioxide thin film (3) of the NFR platform (12) provides solutions to the distance and parallelism problems in the art with the help of the surfaces. In addition, regarding the experiments which are aimed to be performed on fabricated 30 mm x 30 mm NFR platforms (12) provide physical convenience and applicability for the use of equipment such as the heater plate to be mounted on the emitter (5) side of the sample, a heat sink to be mounted on the receiver (6) side of the sample, a temperature meter and a heat flow meter.

As it supports surface phonon polaritons, SiC has been frequently examined in theoretical NFR studies and its positive effect on system efficiency has been presented. The use of SiC on the platform and its derivatives of the invention is advantageous because it supports surface phonon polaritons and also has favorable properties of SiC such as high melting temperature, high temperature operability, thermal stability, and mechanical strength.

Description of the Figures

Figure-1 A view of the configuration of parallel plates in which near field radiation is inspected Figure-2a A view of the general structure of platforms developed for the inspection of NFR in the literature

Figure-2b A view of the near field radiation platform of the invention

Figure-3a A figure of the fabrication stages of the NFR platform of the invention

Figure-3b Inner surface pattern view of intermediate pillars of the emitter and receiver of the invention

Figure-3c The outer surface pattern view of the emitter and receiver of the invention

Figure-4a A graph of (a) RF magnetron sputtering recipe parameters developed for the use of integrated SiC target

Figure-4b A graph of the SiC thickness - process time relationship for (a) RF magnetron sputtering recipe developed for the use of integrated SiC target

Figure-5a A thick square wall view of SiO structures integrated into the NFR platform Figure-5b A thin square wall view of SiO structures integrated into the NFR platform Figure-5c A straight column view of SiO? structures integrated into the NFR platform Figure-5d A hexagonal honeycomb view of SiO? structures integrated into the NFR platform Figure-6 A view of the photolithography mask constructed to include the optimized SiCE wall designs

Figure-7 A figure of c-SAM image of the contact surfaces of the integrated structure containing

PECVD SiOz contact surfaces after bonding

Figure-8a A figure of c-SAM image of the inner surfaces of the integrated structure containing

PECVD SiOz contact surfaces after bonding

Figure-8b A figure of c-SAM image of the outer surfaces of the integrated structure containing

PECVD SiOz contact surfaces after bonding

Figure-9 A view of c-SAM characterization of the integrated structure with thermal oxide intermediate surface after fusion bonding

Figure-10 A schematic view of the obtaining process of individual and integrated NFR platforms by dicing

Description of Reference Numbers in Figures

1. Silicon substrate

2. Silicon carbide thin film

3. Silicon dioxide thin film

4. Vacuum gap

5. Emitter

6. Receiver

7. Integrated structure

8. Thick square wall

9. Thin square wall

10. Columns

11. Hexagonal honeycomb column

12. NFR platform

13. Material holder

Claims

1. A closed and integrated platform for the inspection of radiation transfer at micro-nano scale is characterised by comprising: an emitter (5) comprising a silicon carbide thin film (2) deposited on a silicon substrate (1), a receiver (6) comprising a silicon carbide thin film (2) deposited on a silicon substrate (1), silicon dioxide intermediate pillars deposited on the silicon carbide thin films (2) of the emitter (5) and receiver (6) and wherein the silicon dioxide intermediate pillars acts as a contact surface between the emitter (5) and the receiver (6), when the emitter (5) and the receiver (6) are bonded in a vacuum environment such that the emitter (5) and the receiver (6) are parallel to each other and the distance between them is smaller than thermal radiation wavelength (X) and

- wherein the contact surfaces of the mentioned intermediate pillars are patterned.

2. The platform according to claim 1, wherein the pattern is the pattern of a thick square wall (8), a thin square wall (9), a column (10) and/or a hexagonal honeycomb (11).

3. The platform according to claim 1 , wherein the silicon dioxide thin films (3) are bonded to be mirror images of each other.

4. The platform according to claim 1, wherein the silicon substrates (1) of the emitter (5) and the receiver (6) comprise codes defining the contact surface pattern.

5. The platform according to claim 1 , wherein the surface dimensions are 3 cm x 3 cm.

6. A fabrication method of a closed and integrated platform for the inspection of radiation transfer at micro-nano scale comprises of the following steps of a. obtaining an emitter (5) by coating a silicon carbide thin film (2) on a silicon substrate (1) and obtaining a receiver (6) by coating a silicon carbide thin film (2) on a silicon substrate (1), b. deposition on the silicon carbide thin films (2) of the emitter (5) and the receiver (6) with a silicon dioxide thin film (3) to form intermediate pillars, c. patterning the surfaces of the mentioned silicon dioxide thin film (3), d. closing by bonding the emitter (5) and the receiver (6) under vacuum such that the contact surface is patterned and the distance between the emitter (5) and the receiver (6) is smaller than the thermal radiation wavelength (I) and the emitter (5) and the receiver (6) are parallel to each other, e. obtaining single NFR platforms (12) by dicing the integrated structure (7) obtained.

7. The method according to claim 6, wherein in step c it is patterned with the pattern of a thick square wall (8), thin square wall (9), column (10) and/or of hexagonal honeycomb (11).

8. The method according to claim 6, wherein the silicon carbide thin film (2) is coated by RF magnetron sputtering technique in step a.

9. The method according to claim 6, wherein the silicon carbide thin film (2) is coated by RF magnetron sputtering technique with an integrated SiC target.

10. The method according to claim 6, wherein the silicon carbide thin film (2) is coated by RF magnetron technique with a monolithic SiC target.

11. The method of claim 6, wherein the silicon dioxide thin film (3) is coated by plasma-enhanced chemical vapor deposition technique in step b.

12. The method according to claim 6, wherein the surfaces of the silicon dioxide thin film (3) are patterned by photolithography technique in step c.

13. The method according to claim 6, wherein the emitter (5) and the receiver (6) are bonded along the silicon dioxide contact surfaces coated by plasma-enhanced chemical vapor deposition technique by chemical activation in step d.

14. The method according to claim 6, wherein the emitter (5) and the receiver (6) are bonded along the silicon dioxide contact surfaces coated by plasma-enhanced chemical vapor deposition technique by plasma activation in step d.

15. The method according to claim 6, wherein the emitter (5) and the receiver (6) are bonded along the thermal oxide (SiCh) contact surfaces by plasma activation in step d.

16. The method according to claim 6, wherein 4 NFR platforms (12) with a surface area of 3 cm x 3 cm in step e are obtained by dicing from the bonded integrated structure (7).