NEAR-GLOBAL PLANARIZATION OF OXIDE-FILLED SHALLOW TRENCHES USING CHEMICAL-MECHANICAL POLISHING

The use of chemical mechanical polishing (CMP) is rapidly increasing a s a planarization technique in very large scale integrated process tec hnology. Many of the planarizing applications have been directed towar d interconnect dielectric planarization of triple level metal and quad ruple level metal schemes. Interest in CMP as a tool for use in planar ization of oxide-filled shallow trenches is now increasing. Isolation planarity with the silicon surface is required for achieving maximum l inewidth control during subsequent silicon gate processing. Increased planarity also helps reduce the amount of overetch required during the polysilicon definition step especially that is required to clear mini mum poly-to-poly spaces. Reactive ion etching overetch can contribute to junction leakage and critical dimension tolerance degradation. The utilization of CMP has been limited because of the dishing effect in w ide field regions, as well as the difficulty of planarizing large and small features simultaneously. In this work, we discuss our shallow tr ench planarization technique, using chemical mechanical polishing alon e. Dishing was reduced to less than 10 nm across 6 mm wide field regio ns. Large and small features were planarized simultaneously.