Development of Cu CMP Slurry with High Throughput and Low Dishing

Abstract

To follow the Moore's law, the advanced Cu slurry needs to continue the trend of cost reduction and performance improvement at the same time. With the technology node shrinking, there is a need to develop a Cu slurry with fast rate for high throughput and low dishing for minimal within die and within wafer variation, and stringent defect requirement such as residue, corrosion, and micro scratches. In this paper, we introduce a high performance Cu CMP slurry to overcome these performance challenges in Cu CMP process. The impact of slurry formulation on the slurry performance will be presented under different process conditions, including blanket removal rates/profiles, static etch rates, dishing, Cu residue clearance capability and corrosion status. Electrochemical study was also conducted to support the results and performance. With the optimized formulation and polishing process, the slurry achieves dishing under 300A at near 1 um Cu polishing rate. For multiple layers stacking, the slurry also has tunable dishing to provide a wide process integration window.

Chemically Impregnated Abrasives Provide High Planarization Efficiency Copper CMP Slurry

“…Current CMP slurries have a limited planarization efficiency (PE) (ratio of step height removed to thickness removed) which introduces restrictions on the design rules that specify the layer thickness and other process parameters during semiconductor design. Without an improvement in PE, CMP is going to become an increasingly expensive and limiting step in the semiconductor manufacturing process (2,3). Current commercial CMP slurries consist of homogenous mixtures of abrasives (typically metal oxide nanoparticles) and chemical components.…”

“…This dissolution also decreases the PE, and requires an increase in the incoming copper plating thickness, which adds cost to the wafer processing. A corrosion inhibitor is sometimes added to prevent the dissolution, but this tends to prevent the glycine-copper oxide complex reaction, and decreases the MRR (2,5). Figure 1 illustrates the typical mechanisms that occur during copper CMP.…”

Model-Based Optimization of CMP Process Parameters for Uniform Material Removal Selectivity in Cu/Barrier Planarization

“…Different slurry chemistries result in different MRR of Cu and barrier materials. 12,[14][15][16][17][18][19][20][21] Xu investigated the effect of H 2 O 2 on MRR and found that the MRR of Cu increases till 10 ml of H 2 O 2 per liter of the slurry while it decreases if the concentration of H 2 O 2 is increased beyond 10 ml. 22 Cao studied the MRR of TiN, NDC, and Cu and found an optimized slurry formulation that can meet the requirements of the new integration scheme.…”

The Effect of 2-hydroxyphosphonoacetic Acid on the Removal Rate Selectivity of Cu/Co/TEOS in H2O2Based Alkaline Slurries

“…The increase of resistance capacity (RC) delay and electromigration phenomenon caused by dishing and erosion seriously reduce the reliability and yield of the device. [10][11][12] After finishing polishing, a period of over polishing was need to remove the residual copper on the wafer surface. Because the Cu RR is fast and Co RR is slow, the slurry corrodes the copper in the groove, so the dishing and erosion are initially formed.…”