Microsystems have been recently introduced as tools for screening in the chemistry, biochemistry and biological fields. More precisely, it has been shown that non-contact micro-dispensing systems could be a viable and interesting technology for accurate, high throughput deposition of biological fluids.The present study considers the ejection and the impact of polymeric fluids onto a silicon wafer having a number of pits covered by functionalized surfaces. The polymeric fluid is used to protect the constituent bases of DNA during reactive processes using a proprietary technology. It is shown here that the film constituted after drying should have a given thickness in order to be able to fulfill the masking role. Now, it is well known that the jetting of a polymeric fluid gives longer filaments which may be detrimental for accurate deposition and process reproducibility. The deposition process is rendered more difficult by the fact that the drops should land in well defined pits of different diameters with straight walls. We give here the methodology used to overcome these difficulties.After giving the basics of the oligonucleotides in-situ synthesis process with special emphasis on the microfluidics aspect, we conduct extensive jetting of some polymeric fluids in order to choose the appropriate polymer and concentration for masking purposes and to ascertain their behavior in an industrial environment. Concerning the impact process itself, we characterize the surface of the silicon biochip at each step of the process and follow the thin film formation of single and multiple drops using a number of elaborate techniques. To conclude, we demonstrate that the combination of tailored operating conditions leads to satisfactory synthesis performance.