Improved Plasma Resistance for Porous Low-k Dielectrics by Pore Stuffing Approach

Abstract

The pore stuffing method is studied with the objective of improving the plasma induced damage for porous organo-silicate glass low-k dielectrics. Experiments on blanket films show that, pore stuffing reduces the low-k degradation compared to non-protected porous films during plasma etch. The post etch surface roughness is also improved. The protection mechanism is attributed to reduced radical penetration, mainly fluorine and oxygen. The resistance against vacuum UV degradation is also improved by pore stuffing, since polymers used as filling agents have a higher VUV absorption coefficient than Si-O based dielectric network. The protection effect against fluorocarbon-based gas discharges is extensively studied with both blanket and patterned samples. For patterning of porous, non-stuffed low-k films, the addition of polymerizing gas reduces surface plasma damage but this polymerizing protection effect doesn't work well on trench sidewalls. Pore stuffing enables an efficient sidewall protection even with oxidizing gas discharges.

Synergistic effect of VUV photons and F atoms on damage and etching of porous organosilicate films

“…It was shown that the low‐k damage by VUV light cannot be completely avoided even when the pores completely filled with the sacrificial polymer. Significant penetration of fluorine into low‐k film after P4 and cryo processing has also been observed . Although in both cases the fluorine penetration itself did not change electrical characteristics of low‐k film, simultaneous effects of VUV light and fluorine atoms have not been studied in detail.…”

Review of methods for the mitigation of plasma‐induced damage to low‐dielectric‐constant interlayer dielectrics used for semiconductor logic device interconnects

“…This protective effect depends on both the polymer nature and level of porosity fill . This process is called post porosity plasma protection (P4) technology or the pore stuffing method . The protection mechanism is attributed to reduced penetration of radicals, such as fluorine and oxygen and the resistance against VUV degradation because of a higher VUV absorption coefficient compared with that for a Si‐O‐based dielectric network .…”

“…This process is called post porosity plasma protection (P4) technology or the pore stuffing method . The protection mechanism is attributed to reduced penetration of radicals, such as fluorine and oxygen and the resistance against VUV degradation because of a higher VUV absorption coefficient compared with that for a Si‐O‐based dielectric network . However, the pore stuffing protection (PMMA, molecular weight = 4000 g·mol −1 ) against oxidizing radicals and VUV photons was insufficient for porous low‐k (k = 2.05) materials and no barrier Ta diffusion appeared during barrier deposition by physical vapor deposition .…”

Quantitative characterization of pore stuffing and unstuffing for postporosity plasma protection of low-k materials

“…This new class of materials, commonly known as organosilicate glasses (OSG) or porous organosilicate glasses (p-OSG), can be deposited by plasma enhanced chemical vapor deposition (PECVD) or spin-on technology. 8 Pore stuffing mitigates the plasma-induced damage of the low-k dielectric because it prevents the diffusion of active species into the bulk of the porous material. 2 Plasma etching and resist strip (ash) cause methyl depletion which leads to moisture adsorption and degradation of the dielectric properties.…”