| AVS 61st International Symposium & Exhibition | |
| Selective Deposition as an Enabler of Self-Alignment Focus Topic | Wednesday Sessions |
| Session SD-WeA |
| Session: | Process Development for Selective Deposition and Self-Aligned Patterning |
| Presenter: | FatemehSadat Minaye Hashemi, Stanford University |
| Authors: | F. Minaye Hashemi, Stanford University C. Prasittichai, Stanford University S.F. Bent, Stanford University |
| Correspondent: | Click to Email |
Planar and 3-D electronic structures such as those found in FinFETs contain metal/dielectric patterns, for which selective deposition processes may facilitate the fabrication of device features on the length scale of nanometers. The ultimate adoption of selective deposition approaches in device fabrication will require a technique that can provide for deposition of different materials with a variety of thicknesses while maintaining the selectivity even at high thickness limits. Atomic layer deposition (ALD) is a good choice for selective deposition because it is based on self-limiting reactions between gas phase precursors and specific functional groups at the growth surface. This chemical specificity provides a means to achieve selectivity in ALD on a spatially patterned substrate.
In our previous studies, we have demonstrated area selective ALD of dielectric-on-dielectric by selectively depositing an organic self-assembled monolayer (SAM) of octadecylphosphonic acid (ODPA) as the blocking layer on metal parts of a metal/dielectric (Cu/SiO2) pattern. This approach provided the ability to carry out selective deposition for film thicknesses above 10 nm. However, the deposition time of a well-packed ODPA passivation layer required to achieve such selectivity was over 40 hours. Also, it is desirable to remove the organic ODPA molecules from the metal surface after the process of area selective ALD. Moreover, due to the diverse chemical nature of different dielectric precursors, when using very reactive precursors the selectivity achieved using an ODPA passivation layer can be limited to dielectric film with thicknesses less than 10 nm. Here we propose a new strategy to resolve these issues by performing selective deposition combined with selective etching of dielectric films on metal/dielectric pattern.
In this approach, we first selectively deposit ODPA SAMs on a Cu/SiO2 pattern for a reduced deposition time. Subsequent ALD processes of dielectric material on the substrate results in poor or no selective deposition on the substrates. Then we use a mild etchant to selectively remove the deposited dielectric film on Cu surface without affecting the film grown on neighboring SiO2. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) measured after applying the etchant confirm no residual dielectric film on Cu, while ellipsometry and XPS results show metal oxide growth on SiO2. We thus show that using this method, not only the area selective ALD is achievable with more rapid processing but also high selectivity can be reached for deposition of a variety of high-κ dielectric materials, opening up the possibility for ne w applications.