The efficacy of post porosity plasma protection against vacuum-ultraviolet damage in porous low-k materials

Abstract

As of today, plasma damage remains as one of the main challenges to the reliable integration of porous low-k materials into microelectronic devices at the most aggressive node. One promising strategy to limit damage of porous low-k materials during plasma processing is an approach we refer to as post porosity plasma protection (P4). In this approach, the pores of the low-k material are filled with a sacrificial agent prior to any plasma treatment, greatly minimizing the total damage by limiting the physical interactions between plasma species and the low-k material. Interestingly, the contribution of the individual plasma species to the total plasma damage is not fully understood. In this study, we investigated the specific damaging effect of vacuum-ultraviolet (v-UV) photons on a highly porous, k = 2.0 low-k material and we assessed the P4 protective effect against them. It was found that the impact of the v-UV radiation varied depending upon the v-UV emission lines of the plasma. More importantly, we successfully demonstrated that the P4 process provides excellent protection against v-UV damage.

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

“…The comparative analysis has revealed the typical features of OSG damage in all cases . These features are mainly caused by depletion and modification of surface Si–CH 3 bonds including etching in the case of F atoms present inside OSG bulk .…”

“…In the beginning, Si–CH 3 modification occurs due to reactions with fluorine atoms leading to formation of hydrofluorocarbon (CH x F y ) layer and afterwards etching gradually starts. Therefore, the OSG damage rate (the damage integrated over the total film thickness) was estimated from the evolution dynamics of Si–CH 3 peak in FTIR spectra similar to that it was done in the other works . The damage rate was estimated from the initial slope of [Si–CH 3 ] treated /[Si–CH 3 ] pristine ratio reduction when etching is still minimal and there is a small change of the film thickness.…”

“…OSG damage is mainly caused by exposure to active radicals, and VUV light generated in plasma . One of the most damaging steps is patterning (due to etching), which is typically conducted in fluorocarbon‐based plasma.…”

Hyperconnected molecular glass network architectures with exceptional elastic properties

“…It is well accepted that the incorporation of additional nanoporosity severely degrades the elastic properties and the resistance to processing damage of organosilicates, which can ultimately limit their integration into emerging technologies 47 , 48 . The sensitivity of these hybrid materials to plasma damage has been addressed in different ways 49 , 50 , and solutions based on the protection of the nanopores with polymers hold great promise 51 – 53 . Interestingly, if the polymer used to fill the pores becomes molecularly confined, a unique toughening effect is observed 54 .…”

Modification of Porous Ultralow-k Film by Vacuum Ultraviolet Emission

“…The low- k damage by active species can be decreased by reducing pore size, forming closed pores, and developing a high-tortuosity pore structure. ,, Destruction under the action of VUV radiation and the possibility of its reduction have been studied in many research works. ,, A comprehensive analysis of the most important published results, including analysis of general behavior of UV-induced degradation, practical applications, and atomic models of generated defects, has recently been published as a review . Particular attention has also been paid to the analysis of possible ways to reduce the VUV damage. ,− Most of these efforts are based on reducing the intensity of the most harmful UV photons by optimizing plasma conditions and chemistry. One exception is the P4 based approach where the intensity of VUV radiation in the low- k volume can be reduced by filling of low- k pores with sacrificial polymer that can significantly reduce the depth of penetration of VUV light into the low- k film.…”