Manufacturing of a heterogenious Silicon-glass microfluidical system for bio-analytical purpuses

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Horváth Veronika
Department of Electron Devices

This thesis provides an insight into the Si/glass microfluidic heterogeneous structure of production technology. Within this, I’ve learnt about the technological development of glass etching and wafer bonding, and I’ve made the experiments in the MTA MFA MEMS laboratory.

I’ve presented the MEMS devices in general, including the possibilities for microfluidic adaptation. The ultimate goal is the development of a bioanalytical tool, therefore I also covered the bioperception topic. Furthermore, I wrote about the forthcoming device production steps, more in the depths of the glass etching and the wafer bonding.

The wet etching was carried out on Pyrex 7740 and Borofloat 33 types of borosilicate glass. According to the task announcement, the 20-50 μm deep cavities seem to be a critical point of the work. Etching depths in the borosilicate glass were inspected on the material types of the masks. The used masking materials were: photoresist mask, Cr / Au metal mask and sputtered silicon mask. In addition, I determined the etching speeds with the usage of oxide etching in the chemical laboratory.

The wafer bonding technology was developed with a SB6L SÜSS Microtech Wafer Bonder equipment which was available in the institute. During the production of the microfluidic sensor structure, a low temperature (200°C) anodic bonding was necessary on substrates having an intermediate layer (SiNx, SiO2). This type of experiments of anodic bonding has never made previously, so my task was to complete a parameter set for the procedure. After setting the appropriate parameters a 4-inch wafer was used and its alignment was carried out by a SÜSS MicroTech Mask Aligners/Bond Aligners MA6/BA6 interface device.

For glass etching characterization I used profilometry to measure the depth of the etched cavities and optical microscopy and scanning electron microscopy in order to evaluate the etching profile. For the characterization of the wafer bonding I used besides the eye inspection tensil strenght measurements, based on the so called “blade” and the pulling methods.

With these methods I managed to develop a particularly robust and hermetic Si / glass microfluidic device, which will be suited for microanalytical purpuses.


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