Author_Institution :
M/A Com., Lowell, MA, USA
Abstract :
Reactive ion etching is a widely-used technique for fabricating via holes in polymer-metal multilayer interconnect structures. Reactive ion etching of thin film polymers was studied using Benzocyclobutene polymer and photoresist etch mask, in O2 and SF6 plasma. A design of experiments (DOE) was carried out with rf power, pressure, and SF6 concentration as the design variables, with a constant total gas flow rate. The responses measured in this study were dc bias, etch rate, via angle, uniformity, selectivity, lateral etch rate, and etch cleanliness. The DOE revealed some complex relationships between variables. DC bias was a very important parameter for explaining the observed effects on etch rate, via angle, selectivity, and lateral etching. A simple model was formulated to explain the dependence of via angle on design variables. The etching characteristics of the photoresist mask affected not only the selectivity, but also the via angle and lateral etch rate. Due to conflicting requirements posed by the responses, optimization of the reactive ion etch (RIE) process involves many trade-offs which depend on the particular application
Keywords :
design of experiments; integrated circuit interconnections; integrated circuit measurement; photoresists; polymer films; semiconductor process modelling; sputter etching; 200 W; 250 mtorr; O2-SF6; O2-SF6 plasma; RIE process optimization; SF6; SF6 concentration dependence; benzocyclobutene polymer films; constant total gas flow rate; dc bias; design of experiments; etch cleanliness; etch rate; etch selectivity; etch uniformity; lateral etch rate; model; photoresist etch mask; polymer-metal multilayer interconnect structures; pressure dependence; reactive ion etching; rf power dependence; via angle; via hole fabrication; Dielectric thin films; Etching; Integrated circuit interconnections; Nonhomogeneous media; Plasma applications; Plasma chemistry; Plasma materials processing; Polymer films; Resists; US Department of Energy;
Journal_Title :
Components, Packaging, and Manufacturing Technology, Part C, IEEE Transactions on