Recovery from Plasma-Process-Induced Damage in Porous Silica Low-k Films by Organosiloxane Vapor Annealing

Abstract

It was demonstrated that recovery from dry etching and ashing damage in porous silica low-k films occurred by 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) vapor annealing. The increase in k-value after Ar/C5F8/O2 plasma etching was reduced from 35 to 6.5% of the initial value (k=2.25) by TMCTS vapor annealing. Leakage current also returned to the initial level. Hydrofluoric acid wet etching revealed the sidewall damaged region in a porous silica trench due to plasma processes. The TMCTS vapor annealing was found to be effective for recovery from the sidewall damage. Fourier transformed infrared absorption spectroscopy indicated that the replacement of Si–CH3 bonds in low-k films by Si–O and Si–OH bonds occurred during plasma processes. The recovery mechanism involves hydrophobic bond (–CH3) reintroduction into the film followed by stable cross-linked poly(TMCTS) network formation on pore wall surfaces by TMCTS vapor annealing.

Systematic investigation of silylation materials for recovery use of low-kmaterial plasma damage

“…20) Also, many recovery processes using silylation are reported using various kinds of silylation materials. [7][8][9][10][11] For example, trimethylsilyldimethylamine (TMSDMA) was used for the recovery process and showed good capacitance value 9) and excellent results in the stress-induced-void (SIV) test. 7) In this paper, we focused on two aspects of silylation materials.…”

Effectiveness of Dimethyl Carbonate and Dipivaloyl Methane Chemicals for Internal Repair of Plasma-Damaged Low-k Films

“…Therefore, many trials on the restoration of plasma-damaged porous SiOCH films have been extensively conducted. [10][11][12][13][14][15][16][17][18][19][20] Mor et al reported that hexamethyldisilazane (HMDS) vapor converts hydrophilic silanol groups into hydrophobic Si-O-Si-(CH 3 ) 3 groups. 11) Huang et al showed that trimethylchlorosilan (TMCS) vapor silylation was effective for the recovery of the carbon loss induced by O 2 radicals.…”

Trench Sidewall Elimination Effect on Line-to-Line Leakage Current in Scalable Porous Silica (k= 2.1)/Cu Interconnect Structure

“…[5][6][7] When porous low-k materials are integrated into the copper (Cu) metallization process, several additional processes are often applied to protect the etched surface of the porous low-k film, e.g., silylation recovery and sidewall (SW) formation. [8][9][10][11][12][13] Silylation recovery is applied to reduce absorbed moisture because porous low-k films are susceptible to trench formation damage, such as chemical bond breakage and moisture absorption. [8][9][10]14) SW formation is generally applied to protect the etched surface and to suppress metal diffusion into the low-k film.…”

“…[8][9][10][11][12][13] Silylation recovery is applied to reduce absorbed moisture because porous low-k films are susceptible to trench formation damage, such as chemical bond breakage and moisture absorption. [8][9][10]14) SW formation is generally applied to protect the etched surface and to suppress metal diffusion into the low-k film. As a result, the bulk dielectric film and cap/low-k interface are protected from line-to-line leakages.…”