| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Brian Krist, Intel Corporation |
| Authors: | B.J. Krist, Intel Corporation J.S. Chawla, Intel Corporation M. Chandhok, Intel Corporation S.R. Cook, Intel Corporation H.J. Yoo, Intel Corporation |
| Correspondent: | Click to Email |
Transmission electron microscopy (TEM) imaging of narrow critical dimension (CD) features patterned in low-k materials is critical for functional validation of the patterning process steps. For interconnect applications in particular, low-k porous dielectrics can be mechanically weak and suffer structural damage from plasma processing due to higher carbon content.
Cross-section TEM sample lamellae prepared by focused ion beam (FIB) milling using conventional in-situ protective cap materials like insulator deposition (IDep, eg. TEOS), Pt, and W alter the low-k material line width, edge/surface roughness, and profile due to stress and high energy secondary electron interaction during localized capping. In addition, the conventional cap materials cannot gap fill features trenches that are less than 20 nm wide. Gapfill defects can cause poor mechanical stability during TEM sample preparation and imaging. These defects can also lead to ion beam damage during TEM sample preparation.
In this paper, we investigate the ability of the ex-situ liquid inks as cap material for TEM cross-section sample lamellae to replace conventional in-situ cap materials. The use of ink fill protects the surface from the secondary electron beam damage that occurs using conventional in-situ FIB dual beam capping methods. Ink fill capped samples have undistorted ILD patterns that hold to zone axis. The ink to Pt FIB mill is matched unlike high dense high stress IDep so both sample thickness and stress are more consistent. Several inks where reviewed and down selected for lack of high aspect ratio fill, or inability to cure out solvents in ink. Cross-section images in this work use either hand dispensed BIC Mark it, or automate dispensed using GenesisEcono-Jet printer 3440BK INK.
We also demonstrate how ink fill capping enables imaging of the smallest features in interconnect process technology having low-k ILD.