Investigation of ULK etching processes by using plasma diagnostic and correlation analytics
In situ plasma diagnostics are becoming increasingly important to qualify dry etching processes. As part of an ECSEL project, Fraunhofer ENAS is working with a novel method, the quantum cascade laser absorption spectroscopy (QCLAS), to investigate less damaging plasma etching processes for ultra low-k (ULK) materials. Patterning processes of such materials are widely investigated and still a topic of interest. Especially for leading-edge technologies, research institutes and semiconductor industry undertake great effort to integrate the material in interconnect circuits. One of the main challenges is the chemical modification of the material during patterning, which leads to an increase of the dielectric constant, the well-known damage of ULK materials. In this light, Fraunhofer ENAS is working on approaches to monitor the damage behavior during the patterning process. In preliminary investigations and by using multivariable data analysis methods it was possible to extract the hidden dependency of the plasma specie SiF4 and the damage of the ULK.