Nanocatalysis has received considerable attention in the scientific community due to their superior reactivity compared to their macro-sized counterparts. MEMS nanoreactors allow scientists to view these reactions in-situ. This opens up doors to finally understanding the underlying mechanisms of the nanocatalyst's effectiveness, which may eventually improve our every day lives.

This thesis focuses on the viewing port of the device -- the electron-transparent window (ETW) -- and how they can be improved for future generations. From scattering theory, it was determined that the best way to improve the imaging quality of current ETWs was to develop thinner ones. Two questions were then asked: can a thinner ETW be integrated into a nanoreactor process? If so, how will it affect the mechanical strength of the ETW?

Aluminum oxide (alumina) was chosen specifically because of its deposition method, atomic layer deposition (ALD). The characteristics and material properties of ALD alumina were assessed and it was determined that they are suitable for ETW applications.

Using ALD alumina presented a few challenges in its integration into nanoreactors, especially the use of vapor hydrogen fluoride. ALD alumina ETWs were able to be successfully integrated into a nanoreactor down to 5 nm thick. The 5 nm alumina ETWs are able to withstand a pressure difference at least 0.75 bar, however they were not able to survive inside a TEM as they disintegrated immediately under the electron beam.

Alumina ETWs that are 10 nm were able to be imaged in a TEM. These windows were tested in a transmission electron microscope (TEM) and scanning electron microscope (SEM) to showcase the improved electron-transparency.

The ultra-thin ALD alumina ETWs can improve the imaging quality of nanoreactors, due to their lower thickness compare to current nanoreactors. The successful release of 5 nm membranes may also be useful for other applications, such as sensors.

Micro-hotplate and Micro-hotplate integrated Nano-reactors are a revolution for in-situ observations in Transmission Electron Microscopy (TEM) imaging. They currently operate at about 400oC without any problems. The SiNx membranes of micro-hotplate and Nano-reactors have integrated micro-heater along with electron transparent windows. The major problem is the shift in 'z' direction of the membranes as a function of pressure and temperature. This creates a change in focus during in-situ TEM imaging affecting the image quality. Net compressive forces can be a reason for bending of membranes, as far as temperature is concerned. Thus, introduction of residual tensile stress was considered to solve this problem. Simple COMSOL simulations were made using plate models to verify the effect of residual tensile stress in membranes as a function of temperature and pressure individually, as well as a combination of both. It was concluded that residual tensile stress does reduce thermal buckling. It also reduces the bulging due to pressure but bulging as a function of pressure can't be made zero. It also concludes thermal buckling is more dominant at lower pressure and pressure bulge is more dominant at higher pressure.

Different residual stress LPCVD SiNx films were deposited and material properties like Young's modulus, refractive index and density were characterized. A saturation to the deposition and residual tensile stress was found as a function of gas-ratio. Surface morphology and IR spectra were also determined using AFM and FTIR respectively. All the characterization done proves the change in material composition with fabrication parameters. The introduction of high residual stress questions the reliability of the membrane and hence, there was a need to check if high tensile residual stress doesn't break the membranes. Thus, a new device for wafer level pressure testing of membranes was designed and fabricated. The pressure bulge test was done and reflections were recorded for various pressure and stress levels. The membranes were found reliable up to a pressure of 1.5 bar. New generation of micro-hotplates were fabricated using this concept and an increment 400oC in the operating temperature of micro-hotplates and nano-reactors, without any-shift in 'z' direction due to temperature, was achieved.

A high aspect ratio and large current 3D electrochemical sensor was de- signed. This miniaturized sensor was built by using silicon microfabrication technologies in comparison to screen printed electrode. New tilting tool for CHA solution platinum evaporator is designed and realized. The analysis of tilt angles and rotation for evaporation of platinum on 3D structure in evap- orator is done. Different recipe of DRIE etching have been tested in order to get straight pillars. Different recipe in both ”Trikon Omega 201” and ”Rapier Omega i2L DRIE etcher” were tested to minimise the scalloping effects on the pillars. The final sensor with straight pillar structure with platinum working electrode is fabricated.