Superconformal Film Growth

The evolution of superconformal Cu electrodeposition in high aspect ratio through silicon vias (TSVs) is examined as a function of polymer suppressor concentration, applied potential and hydrodynamics. Electroanalytical measurements in a CuSO 4 -H 2 SO 4 -Cl electrolyte are used to explore and quantify the effect of such parameters on the metal deposition process. Hysteretic voltammetry due to suppressor breakdown reveals an S-shaped negative differential resistance that leads to non-linear spatial-temporal patterning during metal deposition. For the given hydrodynamic conditions, cyclic voltammetry reveals the potential regime over which positive-feedback gives rise to the superconformal feature filling dynamic. Breakdown of suppression is primarily related to polymer concentrations in the electrolyte while its reformation is dependent on its transport to the interface. Morphological evolution during the early stages of TSV filling reveals two distinct growth front geometries. For dilute polymer concentrations, an initial bifurcation into passive-active surfaces occurs on the side walls of the TSVs followed by bottom-up fill. The depth of the initial sidewall bifurcation within the via increases with polymer concentration. For higher polymer concentrations, i.e. ≥ 25 μmol/L, active metal deposition is rapidly confined to the bottom surface of the via followed by sustained bottom-up filling.

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confidence: 98%

mentioning

confidence: 99%

Superconformal Copper Deposition in Through Silicon Vias by Suppression-Breakdown

Josell

Moffat

2018

“…7c that predict the higher additive consumption rate (left-hand via) and higher additive incorporation (right-hand via) at this location. The highest PEI incorporation levels are along the passivated sidewalls, approaching 75 mol/m 3 in the adjacent deposits; the PEI concentration color map saturates at half of this maximum value to improve visualization of interior regions with somewhat lower impurity levels.…”

Section: Fixed Potential Deposition In Tsvmentioning

confidence: 99%

“…1,2 However, the relative impacts of transport, adsorption, consumption and surface area on these processes change as the feature size, e.g., trench and via dimensions, varies from deep-sub-micrometer to multi-micrometer dimensions. [3][4][5][6] Toward the larger end, bottom-up copper electrodeposition in through silicon vias (TSV) [7][8][9][10][11] has been proposed to occur through critical phenomena associated with suppression breakdown, as captured by an S-shaped Negative Differential Resistance (S-NDR) mechanism.…”

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confidence: 99%

Superconformal Nickel Deposition in Through Silicon Vias: Experiment and Prediction

Braun

Kim

Lee

et al. 2018

This work examines the filling of Through Silicon Vias (TSV) by Ni deposition from a NiSO 4 + NiCl 2 + H 3 BO 3 electrolyte containing a branched polyethyleneimine suppressor. Feature filling occurs due to the interaction of transport limited suppressor adsorption and its consumption by potential dependent metal deposition. The interaction between surface topography and suppressor transport yields a sharp transition from passive to active deposition within the TSV. The transition is associated with significant incorporation of the suppressor, or its components, within the Ni deposit that results in grain refinement evident by electron backscatter diffraction (EBSD). Potential waveforms that progressively shift the location of the passive-active transition upward to optimize feature filling were examined. The evolution of feature filling and deposit microstructure are compared to predictions of a three-dimensional model that reflect critical behavior associated with suppressor-derived, S-shaped negative differential resistance (S-NDR). The model uses adsorption and consumption kinetics obtained from voltammetric measurements of the critical potential associated with suppression breakdown. Good agreement between experiment and simulation is demonstrated.

“…No attempt is being made here to provide a comprehensive review of the wealth of studies published on Cu damascene electroplating. Many groups and individuals in industry and academics have made contributions; 1 however, the pioneering work at IBM begun in the 1990s where the Cu damascene process was conceived, [2][3][4] followed by the continuous work at National Bureau of Standards, [5][6][7][8][9][10][11][12][13][14][15] plater and process development work at Novellus (now Lam Research), 16,17 and Semitool (now Applied Materials), 18,19 as well as the university studies of Professors Alan C. West of Columbia University [20][21][22][23][24] and Uziel Landau of Case Western Reserve University [25][26][27][28] and their research students deserve high recognition. A list of representative publications from these groups is provided in the bibliography.…”

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confidence: 99%

Review—Management of Copper Damascene Plating

Carpio

Jaworski²

2018

An overview of process and quality control issues faced in controlling copper damascene plating is provided. The challenges for effective management of a copper damascene plating process have evolved due to early limitations and problems which were discovered, and then as more demands resulted from Chemical Mechanical Planarization issues, yield and reliability concerns, reduction in critical feature size and the shift to 300 mm wafers as well as the adoption of dielectric films with low dielectric constants. The demands have been addressed by adherence to quality control methodology, improvements in plater design and operation, advancements in plating electrolytes, and by new metrology tools and methodology. The key measurement areas outlined here are bath concentration measurement and control, film properties metrology, contamination issues, and defects. Particular attention is given to the use of electrochemical and optical methods with enhanced capabilities. This includes the use of chemometrics for electroanalytical bath concentration control and optical methods for film thickness, surface roughness, and film stress/wafer curvature measurements.