Research On Deep Silicon Etching Technoligy Using An Ultra-low Cost Tool For Flexible,small Volume Manufacturing

RIE(reactive ion etching),as the core process of micro fabrication technology,has been significantly effected on the semiconductor manufacturing.Its epitaxial deep reactive ion etching(DRIE)combines the process of physical and chemical reactions to remove materials from the wafer surface to realize high-speed etching of deep and narrow structures,and has become an indispensable process link in the construction of microelectromechanical systems(MEMS).At present,noval micro-fabrication processing techniques based on desktop equipment are becoming more and more active as a new field of application for MEMS.It is very important to research and develop flexible and simple etching process with the etching equipment of the desktop processing system.In this paper,DRIE technology is studied and explored based on the trial production of etching equipment in micro desktop processing system.Specific research contents are as follows(1)Structural optimization and trial-manufacture of deep silicon etching equipment in micro-desktop processing system were carried out.Unlike large commercial equipment,the etching system is designed to change the spacing of gas distribution nozzles,ICP coils and substrate chuck assemblies in order to maintain the flexibility of the interior structure of the chamber.The effects of binary and ternary mixed gases on silicon etching were designed and studied.(2)The influence of SF6/O2,SF6/C4F8 and SF6/Ar on Si etching was studied.Studies have shown that adding O2 to SF6 increases the density of fluorine free radicals and hence the etching rate.Meanwhile,the generated SixOyFz passivates the substrate surface to obtain anisotropic etching profile.The optimum oxygen content was 33.3%and the etching rate was 2.4 μm/min.Adding appropriate amount of C4Fs to SF6 will make etching and passivation form a chemical balance and obtain a good anisotropic profile.Adding Ar to SF6 can effectively increase the etching rate(2.8 μm/min)and reduce the roughness at the bottom of the groove(3)Based on the study of binary mixed gas etching,the influence of C4F8/SF6/O23 ternary mixed gas on Si etching was studied.The results showed that adding a small amount of C4F8 into the SF6/O2 mixture not only increased the etching rate(3.5 μm/min),but also obtained the side wall with higher verticity,and the selection ratio and smoothness at the bottom of the groove were also improved.Adding Ar to SF6/C4F8 mixture only slightly increased the etching rate,but reduced the anisotropy.Adding Ar to the SF6/O2 mixture increased the etching rate to a maximum of 3.3μm/min when Ar content was 30%.The addition of Ar can also improve the "black silicon" phenomenon in SF6/O2 etching.