Precise depth etching

Hence, dry etching processes are particularly useful for the precision etching of thin layers in microelectronics. Wet etching allows for high etching rates and is suitable for the depth etching in micromechanics and microsystem technologies, which require low and medium batch sizes. 

To obtain the periodic structure of grooved Si we used chemical anisotropic etching of (110) Si wafer [6]. The narrow grooves, oriented precisely along the <111> crystallographic direction [7], formed an artificial lattice with periods a = 4, 5 and 6 pm for three samples under investigation (see Table). Si vertical ribs with thickness dsi of 1 frni are altered with air space of air thick. The depth of the... 

Photopolymer cliches are etched following UV light exposure and are best utilized for lower quantity print runs given their low hardness. At an etched depth of 25 microns for both metal and polymer cliches, surface tensions of the ink, cliche, and pad will allow about a 12 micron ink film to be picked-up by the pad [5]. During the ink transfer process, solvents, which comprise approximately 50% of the ink, will evaporate and ultimately deliver an actual pad-to-substrate transfer with a thickness of between 6 and 8 microns. More precisely, once the cliche is wiped by a doctor blade to level the ink in the cliche reservoir, the ink surface becomes tacky as the solvents evaporate. This evaporation process allows the ink to more effectively wet the pad. Upon drying at the substrate surface, the actual dry ink film layer is approximately 4.8 microns thick [6]. 

The main advantage of diffusion modification method to structure glasses is the relatively precise etch stop at the position of the threshold value of the silver concentration. The maximum permitted diffusion time is 20 h which allows for a maximum depth of structures of 400 pm. This hmit of diffusion time is due to the onset of undesired LMS crystallisation at the glass surface during the crystallisation process. The reason is the presence of too much silver in the glass surface which will be reduced also without special UV exposme and forms nuclei dming thermal treatment. If diffusion times in excess of 10 h are required a surface treatment should follow the diffusion process. 

---