Dishing effects in a chemical mechanical polishing planarization process for advanced trench isolation

Abstract

We report the first detailed study of dishing effects in chemical mechanical polishing (CMP) of oxide films, observed during the development of an advanced CMP-only trench isolation process. The degree of dishing has been determined for field widths ranging from 0.3 μm to 4 mm and was found to be highly pattern geometry (field width) sensitive, increasing from ∼0 nm at a field width of 5 μm and below to 200 nm at 4 mm. Although this dishing effect makes complete planarization in a large field oxide region (on the order of 1 mm) difficult, it poses no serious problem for trench isolation in narrow field regions due to its reduced effect at small field geometries.

A dishing model for STI CMP process

“…The oxide dishing is clearly very sensitive to oxide trench width and increases as the trench width increases. This predicted trend is consistent with the experimental observations [5,6]. Furthermore, the trench width has a stronger influence on field oxide dishing than the pattern density.…”

“…Significant research efforts have been made to investigate the effects of process parameters and pattern geometry on oxide dishing for STI CMP [5][6][7][8][9]. In these studies, it was found that the amount of oxide dishing is sensitive to pattern density, trench width and overpolishing time.…”

Metal Capping Layer Effects on Electromigration Failure Phenomena of Plasma Etched Copper Lines

“…In addition, the endpoint of the process is difficult to determine and the dishing phenomenon is often observed. [5][6][7] Furthermore, the CMP method is not applicable to the fabrication of large-area TFT arrays because the glass surface is not as flat as the wafer surface is.…”

Highly selective chemical mechanical polishing of Si3N4over SiO2using advanced silica abrasive

“…[1][2][3] The applications of CMP are shallow trench isolation (STI), planarization of inter-layer dielectric (ILD), the formation of contacts and interconnects, and so on. [4][5][6][7][8][9][10][11][12][13] CMP is a hybrid material removal process where chemical reaction with slurry chemicals and mechanical abrasion with abrasives complement each other. [14][15][16][17] With the advent of sub-20 nm device era, CMP faces many challenges such as provisions of nanometer level planarity and sub-nanometer level roughness to wafer surfaces without any surface damage, acquisition of versatile selectivity of removal rate (RR) and so on.…”