Improvement of Barrier CMP Performance with Alkaline Slurry: Role of Ionic Strength

Low material removal rate (MRR) and poor surface quality are the two main problems in ultra-precision machining of LiTaO3 wafer. In order to improve the MRR of LiTaO3 in chemical mechanical polishing (CMP), the effect of alkaline metal ion in slurry on the MRR of LiTaO3 was studied. The results show that adding an appropriate concentration of alkali metal ions to the slurry can increase the abrasive particle size and reduce the electrostatic repulsion between the abrasive and the wafer surface so as to enhance the mechanical effect. At mean time, Li+ replaced by K+ on the LiTaO3 wafer to produce easily removed KTaO3. Adding a certain amount of alkaline metal ion to the slurry improves the MRR of LiTaO3 wafer. Finally, when CMP was performed in slurry (pH 9) with a composition of 10 wt% SiO2 and 0.07 M KCl, the MRR of LiTaO3 is 111 nm/min and the surface roughness (Sq) is 0.3 nm.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effect of Alkali Metal Ion on Chemical Mechanical Polishing of LiTaO₃

Li¹,

Zhang²,

Li³

et al. 2022

“…It also indicates that the MRRs of Cu and Ta increase with the H 2 O 2 concentration increasing because H 2 O 2 modifies the metal surface to promote chemical dissolution while reduces the surface hardness of oxide films which are then removed easily through mechanical force. The oxidizing reactions in the alkaline solution are as follows: 20,21 Cu H O CuO H O 1…”

Section: Resultsmentioning

confidence: 99%

A High Antibacterial Weakly Alkaline Barrier Slurry with the Tunable Selectivity

Luan

Gao

et al. 2021

Self Cite

Barrier chemical mechanical planarization (CMP) is a critical process in the manufacturing of integrated circuits (ICs). Bacterial infestation, the material removal rate (MRR) selectivity and slurry aging are important factors in the evaluation of barrier CMP slurry. In this paper, H2O2 concentration in a lower level was used to adjust the rate selectivity and enhance removal rate on copper to ensure the trench copper thickness reaches the target value. The effects of dodecyl dimethyl benzyl ammonium chloride (DDBAC) and 1,2-Benzisothiazol-3-one (BIT) on bacteria growth were investigated. The total organic carbon analysis and the after-cleaning defect map of the patterned wafer proved the DDBAC and BIT contained in the barrier slurry could prevent bacteria formation within four weeks. The effect of aging on the performance was investigated systematically for the slurry contained containing H2O2, DDBAC and BIT. Aging has been shown to have a small effect on zeta potential, particle size and viscosity of the slurry. The polishing rate and pH decrease with time due to chemical degradation of a part of H2O2. Luckily, the rate selectivity still remains at a high value over time and the barrier slurry after 30d has an effective performance in topography modification.

“…There are Si-OH groups on the surface of TEOS under alkaline condition, which are negatively charged, as shown in the reaction 19 . [26][27][28][29][30] The attractive force between silica abrasive and TEOS surface was improved with the addition of PTH increases, lead to the mechanical force increased and the RR of TEOS increased. The schematic diagram is shown in Fig.…”

Section: The Corrosion Current Density (I Corr ) and Corrosion Potent...mentioning

confidence: 99%

Effect of Potassium Tartrate on Removal Rate Selectivity of Co/TiN/TEOS for Cobalt “Buff Step” Chemical Mechanical Planarization

Cheng

Wang

et al. 2020

Self Cite

As the technology node of integrated circuits (ICs) shrinks down to 7 nm and below, cobalt (Co) has been identified as the promising candidate for the interconnect/contact material. In this paper, colloidal silica was used as abrasive, potassium tartrate (PTH) was used as the promoter of TEOS and complexing agent of Co and titanium nitride (TiN), H2O2 was used as oxidant. The effects of PTH and H2O2 on the removal rate (RR) of Co/TiN/TEOS were studied. Polishing results showed that PTH can improve the RR of Co/TiN/TEOS effectively. The removal mechanism was revealed by X-ray photoelectron spectroscopy (XPS), electrochemical and UV–visible (UV-vis) spectroscopy measurements. It revealed that PTH can complex with Co(II)/Co(III) and TiO2+ ions produced during CMP, and formed Co(II)-PTH/Co(III)-PTH and TiO-PTH complex increases the RR of Co and TiN. The attractive force between silica abrasive and TEOS surface was improved as the concentration of PTH increased, resulting in the mechanical force increased and the RR of TEOS enhanced.