Deliverables Flat epitaxial 3C SiC/Si(100) layers by checkerboard carbonisation The problems arising from the epitaxial growth of 3C SiC layers on Si substrates are due to the mismatch in lattice parameter and coefficient of thermal expansion between these two materials. This results in strained and poor crystalline quality layers. For device applications, the 3C SiC layer is used. The strain of the layer must be controlled to avoid a bow larger than a few tens of micrometers in order to enter the photolithography technological step of the devices production. It was investigated and then patented a process to reach this flatness. It consists of a checkerboard of compressive areas between tensile ones. This results in a balanced strain and a negligible bow. The crystalline quality of the compressive and tensile areas is better than the one that can be also obtained with a controlled carbonisation leading also to a very low bow. The size of the areas can be adapted to the device size SiC MEMS for gas sensing and biomedical application: prototype of electrostatic resonators able to work at high temperature, up to 300?C and prototypes of impedance biomedical sensors New high temperature SiC mass sensors based on electrostatic resonator structures are developed using FLASIC material. The maximum working temperature is 300?C. These type of sensors can be used for gas detection or molecules identification. Similar sensors have been developed by CNM and other labs on Silicon. The main advantage of the new sensors developed with FLASIC material is the higher performances (resonance frequency, resonance amplitude, quality factor) due to the higher young modulus of SiC compared with Si. To fabricate these devices, several technological processes have been set up with especial emphasis on deep SiC etching. Optimal etching condition with ICP has been found to obtain good etching rate, without damaging the Aluminium mask and maximizing the etching selectivity. With these new conditions, lateral cantilevers with widths down to 1um and a thickness of 2.5um have been obtained. This is a relevant technological result that can be also used for the integration of other type of devices in 3C-SiC on Si. Doping and contact formation on the SiC layer, needed for the full electrostatic sensor, have been also developed and optimised. In addition, SiC membrane formation process has been set up using backside-processing technology for Si removal. This process can be used for the fabrication of freestanding resonators for gas detection or for pressure/accelerometer sensors fabrication on SiC membranes. The targeted applications have a strong environmental impact. For example, in the case of gas sensors, it is aimed at the control and regulation of the gases exhaustion regimes. The energy transformation resulting from the burning process can be optimised in order to obtained a maximum efficiency and a limitation of gases rejected in the atmosphere. Other applications can be contemplated in the automotive field as well as in Aerospace applications. In a similar way, the efficiency of the internal combustion engines or reactors can be regulated and improved using information given by the exhaust gas sensing. This may allows reduction of fuel consumption. The main potential barriers are the long-term reliability validation of the sensors and the availability of a high temperature package for housing the sensors in the final application systems. Prototypes of impedance needle sensors have been also fabricated. The results on bulk SiC are very attractive and future commercialisation could be contemplated in the next 24 months. Fabrication of needles on Flasic material has to be optimised but is attractive due to its lower cost. Reconstruction of the available FLA equipment for FLASiC conditions and development of a new prototype equipment For the requirements of FLASiC the available FLA equipment was reconstructed regarding the preheating conditions, the homogeneity of the irradiated area (50mm wafer) and the reproducibility of the FLA parameters. A water-cooled halogen lamp heater was constructed for preheating temperatures up to 900°C. A higher preheating temperature was not possible for the available equipment. The flash pulse duration can be varied between 0.8 and 20ms. A dedicated temperature measurement and controlling equipment was installed for the reproducibility of the annealing parameters. For the FLASiC experiments a specific heating mode was developed and tested. The achieved homogeneity regarding wafer heating (preheating + flash annealing) for an area of 50mm diameter is proved to be < 5%. The extensive experience collected during the work with the reconstructed flash lamp equipment was used for the actual construction of the prototype of FLA equipment. The prototype equipment allow a preheating temperature up to 1100°C and flash pulse duration between 0.8 and 20ms. A wafer diameter up to 100mm is possible. The achieved homogeneity for 50mm diameter is proved to be <1.5% whereas for 100mm diameter < 5%. Both types of FLA equipment are running. The prototype should only be applied in Si and SiC technology whereas the reconstructed FLA could also be applied for other materials. For further details, please contact, W.Skorupa@fz-rossendorf.de and T.Gebel@nanoparc.de i-FLASiC technology for the formation of thick, good quality 3C-SiC layers The current technology of growing 3C-SiC films epitaxially on Si-substrates is based on CVD at 1350°C and MBE at lower 1100°C. The perfection of the deposited SiC layer depends on the perfection of the first SiC monolayer. Therefore, the aim is the formation of a good quality SiC layer (< 100 nm) on Si-bulk using flash lamp annealing. For this a thin stacking structure of SiC-cap/Si/SiC will be deposited on Si-bulk wafer. By the following flash, the light energy absorption is carried out in the Si-interlayer and this Si-layer will be molten. The SiC in contact with the molten Si dissociated. Simultaneously, the SiC from the SiC-cap layer will be moved to the lower SiC layer. During the cooling down the SiC grows epitaxially. After that the SiC-cap and the Si-interlayer must be removed. This can be carried out by a technology consist of physical + chemical etching. The remaining thin SiC layer is the seed for the deposition of thick SiC by CVD Harsh environment compatible sensor package The aim of the miniaturized liquid property monitoring device based on the FPW (flexural plate wave) principle is to measure density and viscosity of chemically aggressive media in aeronautical applications. The target application for the described device is for propellant analysis. For packaging of the sensor elements, a special housing has been developed, fabricated and tested. Only the sensitive area of the 3C-SiC sensor chip is exposed to the environment, the rest is protected. The sensor is flip chip mounted on an LTCC component with electrical feed through. Inside the housing there is the miniaturized electronic board. Pins in the LTCC provide the electrical contact to the electronic board. The modular design allows for easy replacement and modification of the different components. Since the housing is made of PEEK and well sealed, the packaging protects sensor and electronics in the harsh environment Computer simulation of the FLASiC process The development of a comprehensive computer model for the FLASiC process is a major achievement. The model has deepened understanding of the FLASiC process and is a valuable process simulation tool, important for subsequent commercial exploitation. A thermal model forms the core of the process model. The thermal model calculates heat flow, temperature distributions and the extent of any melting. Linked to the thermal model is an optical model, which calculates the energy, absorbed from the flash lamps taking into account the various layers in the FLASiC structure. Models include, as appropriate, the temperature dependence of material properties. The model has facilitated the analysis of new concepts such as melt stop techniques which give greatly increased control of melting and greater tolerance of variations in flash lamp conditions. Investigations have shown that carbon diffusion plays a key role in liquid phase epitaxy in FLASiC and a model for the transport of carbon, linked to the thermal model, is able to explain experimental observations. The non-uniform temperature distribution experienced by wafers during the FLASiC process leads to wafer stress and this has been predicted by linking a stress model to the thermal model. The software code is NOT limited to the FLASiC application but in modified manner to many other problems of msec-processing of materials Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
