A Fundamental Approach to Electrochemical Analyses on Chemically Modified Thin Films for Barrier CMP Optimization

Abstract

Chemical Mechanical Planarization (CMP) process development for 10nm nodes and beyond demands a systematic understanding of atomic-scale chemical and mechanical surface interactions for the control of material removal, selectivity, and defectivity. Particularly the CMP of barrier/liner films is challenging with new materials introduced to better adhere the contact metal at the interface and limit the probability of metal diffusion to the transistors. The relative selectivity of the CMP removal rates of the barrier materials against the contact metal needs to be controlled depending on the integration scheme. This paper focuses on understanding the barrier CMP process selectivity on the model W/Ti/TiN applications through electrochemical evaluations and chemically modified thin film analyses. Ex-situ electrochemical evaluations are conducted on the W/Ti/TiN system to evaluate the passivation rates in various slurry formulations as a function of the slurry chemistry and the abrasive particle solids loading. Results of the passivation rates are compared to the removal rate selectivity and the post CMP surface quality on blanked W, Ti, and TiN films. A new methodology for CMP slurry formulations through ex-situ electrochemical analyses is outlined for new and more challenging barrier films while simultaneously highlighting an approach for corrosion prevention on the metallic layers.

Probing the Mechanisms of Metal CMP Using Tribo-Electroanalytical Measurements: Results for a Copper/Malonate System

“…Consistent with previously published results, 20,28,59,82 the TCRs measured here are significantly lower than those of the corresponding MRRs. The origin of this difference has been explained in terms of stress induced instability in the Cu-oxides present at the CMP sample surface.…”

Glycine as an Efficient Corrosion Inhibitor for TiN Oxidation Environments

“…This requires that the removal rate (RR) of TiN be very low, which plays a role in polishing self-stopping. [6][7][8][9] However, when TiN is exposed to an oxidizing environment, the surface of TiN will continue to be oxidized to titanium oxide due to the continuous substitution of nitrogen atoms by oxygen atoms, thereby accelerating dissolution. [10][11][12][13][14] Many researchers have used this to improve the RR of TiN in the CMP process.…”

Palladium Chemical Mechanical Planarization in Packaging and Barrier Level Integration

“…This systematic study on well-established W integration has set up a methodology for developing optimal CMP configurations for the newly introduced films to CMP applications based on electrochemical evaluations. 10 In this paper, we study the removal rate selectivity for Pd integrated CMP applications with a similar approach in a commercial baseline (BL) silica slurry as compared to a commercial Cu CMP slurry. Electrochemistry, surface wettability, slurry viscosity interactions which control the CMP performance are evaluated systematically.…”