Removal Mechanism of Tungsten CMP Process: Effect of Slurry Abrasive Concentration and Process Temperature

Wang, Zhefu; Peng, Rixin; Xia, Sherry; Kitajima, Tomohiko; Tsai, Stan

doi:10.1149/1.4717508

Cited by 7 publications

(8 citation statements)

References 12 publications

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“…Kaufman et al were the first to propose a surface oxidation model for the tungsten CMP mechanism, and this model has been widely accepted for slurry formulation. 15,18,19 A bare tungsten surface is quickly oxidized under low-pH conditions and tungsten oxide is easily removed by mechanical force. Therefore, tungsten oxidation is the determining parameter for tungsten CMP performance.…”

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confidence: 99%

Effects of Pad Temperature on the Chemical Mechanical Polishing of Tungsten

Kim

Ahn

Qin

et al. 2014

ECS J. Solid State Sci. Technol.

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In this study, the effects of pad temperature on the chemical mechanical polishing (CMP) of tungsten were investigated. During polishing, the pad temperature was monitored and the removal rate behavior with respect to the pad temperature evolution was explored. The pad temperature was increased during tungsten CMP, and the tungsten removal rate increased accordingly. Further, it was found that the two had a strong correlation. Although tetraethyl orthosilicate (TEOS) polishing experiment showed that the pad temperature increased similarly under various experimental conditions, the TEOS removal rate did not change for all conditions. A novel pad-cooling nozzle effectively reduced the pad temperature during tungsten polishing and influenced the tungsten removal rate drop. Table motor current monitoring revealed that friction forces were almost identical under all experimental conditions for tungsten polishing regardless of the application of pad cooling. On the basis of pad temperature and table motor current data, it was clear that the tungsten removal rate was determined by temperature, indicating that the tungsten removal mechanism was mostly driven by a chemical reaction. Further, the pad cooling function can be used to control the tungsten removal rate effectively, resulting in a stable tungsten CMP process.Chemical mechanical polishing (CMP) is one of the most critical processes for enabling sub-10 nm device manufacturing. The usage of the CMP process has rapidly increased owing to the increasing demands for planarized surfaces to be used in microprocessor manufacturing. Post-etch and deposition processes render a wafer surface uneven and bumpy; only the CMP process results in a globally flat wafer surface by chemical/electrochemical softening and removal of material by the mechanical action of slurry abrasive. In addition to its original role of planarization to meet the depth of focus (DOF) target for lithography, increasing demand for planarized surfaces for use as interconnects from middle end of the line (MEOL) to back end of the line (BEOL), 1 the fabrication of new three-dimensional stacked devices and emerging fin field-effect transistors (FinFET) requires a more challenging CMP process. 2-5 Moreover, recently developed high-k metal gate structures (HKMG) control the gate height by CMP instead of the conventionally used dry etching process to meet the performance demands for future IC devices. 6-9 Thus, different from the traditional planar structure device fabrication, CMP directly touches a gate module, which makes CMP as a valuable alternative to the classical polysilicon gate process. Extremely high levels of uniformity, planarity, and defect controls are required to achieve so-called dummy gate-open CMP and replacement metal gate CMP successfully. 2,10 Furthermore, through-silicon via (TSV) packaging and wafer-bonding technology requires a more stringent CMP process than traditional local/global planarization. 4,5 Moreover, with the introduction of new materials such as III-V and germanium for us...

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confidence: 99%

Effects of Pad Temperature on the Chemical Mechanical Polishing of Tungsten

Kim

Ahn

Qin

et al. 2014

ECS J. Solid State Sci. Technol.

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“…3,4 A key variable in determining the chemical and mechanical balance during CMP is the slurry used during the process. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The chemical nature of the slurry can be altered by changing the concentration and types of the chemical agents used in its formulation. As for its mechanical nature, which is of particular interest in this study, it can be altered by changing the abrasive [NP] without any changes to its formulation chemistry.…”

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confidence: 99%

“…SiO 2 , W, Cu, etc.). [6][7][8][9][10][11][12][13][14][15][16][17][18] Of these previous works, several have focused on varying [NP] in tungsten CMP processes. [14][15][16][17][18] Wang et al studied the effect of slurry abrasive concentration on removal rate (RR) and process temperature.…”

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confidence: 99%

“…[6][7][8][9][10][11][12][13][14][15][16][17][18] Of these previous works, several have focused on varying [NP] in tungsten CMP processes. [14][15][16][17][18] Wang et al studied the effect of slurry abrasive concentration on removal rate (RR) and process temperature. The authors found that process temperature remained constant and tungsten RR increased with abrasive concentration.…”

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confidence: 99%

“…The authors found that process temperature remained constant and tungsten RR increased with abrasive concentration. 14 However, the authors did not mention what type of abrasive was used in the chemical slurry. Jairath et al changed silica NP and oxidant concentrations to find that tungsten RR increased with both silica NP and oxidant concentration.…”

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confidence: 99%

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Effect of Abrasive Nanoparticle Concentration on the Tribological, Thermal and Kinetic Attributes of Tungsten Chemical Mechanical Planarization

McAllister

Mariscal

Dadashazar

et al. 2020

ECS J. Solid State Sci. Technol.

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The effect of slurry abrasive nanoparticle (NP) concentration on the tribological, thermal and kinetic attributes of tungsten chemical mechanical planarization (CMP) was investigated. Three tungsten slurries with different amounts of colloidal silica NPs, without any detectable changes in formulation chemistry, yielded three different polishing outcomes. As slurry nanoparticle concentration [NP] increased, the coefficient of friction (COF), temperature, tungsten removal rate (RR) and tungsten to silicon dioxide RR selectivity decreased. For tungsten, trends in COF, temperature and RR were successfully simulated using a two-step modified Langmuir-Hinshelwood model which also yielded values for the chemical and mechanical rate constants. Simulation results indicated that the process was chemically-limited for most polishing conditions, and that the process became even more chemically limited as P × v increased. Moreover, the process became more chemically-limited as [NP] increased. During the extraction of an important parameter for simulation purposes (apparent activation energy), a unique change in curvature of the Arrhenius plot was observed and attributed to the fact that chemical vapor deposited (CVD) tungsten films differ in their density, chemical composition and film morphology as a function of their thickness. The same explanation also accounted for the observed changes in instantaneous shear force vs polish time.

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Effect of slurry flow rates on tungsten removal optimization in chemical mechanical planarization

Liau

Lin

2023

Microelectronics Reliability

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Removal Mechanism of Tungsten CMP Process: Effect of Slurry Abrasive Concentration and Process Temperature

Cited by 7 publications

References 12 publications

Effects of Pad Temperature on the Chemical Mechanical Polishing of Tungsten

Effects of Pad Temperature on the Chemical Mechanical Polishing of Tungsten

Effect of Abrasive Nanoparticle Concentration on the Tribological, Thermal and Kinetic Attributes of Tungsten Chemical Mechanical Planarization

Effect of slurry flow rates on tungsten removal optimization in chemical mechanical planarization

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