Effect of Glycine and TT-LYK in Alkaline CMP Slurry on Controlling the Galvanic Corrosion at Al-Co Interface

As the characteristic size of integrated circuits has continued to shrink, there has been increasing interest in using aluminum (Al) as the gate material. Here, we have looked at the role ethylenediamine tetraacetic acid dipotassium (EDTA-2K) plays in the chemical mechanical polishing (CMP) of Al for use as a gate material. Currently, the preferred approach to CMP is to use colloidal silica as an abrasive, EDTA-2K as the complexing agent, and H2O2 as the oxidant. We have explored the influence of EDTA-2K and H2O2 on the Al removal rate (RR) during CMP. The results show that when the concentration of EDTA-2K is 1 wt%, the removal rate reaches 3450 Å/min, and the surface roughness is 0.425 nm. The mechanism of the action of EDTA-2K during CMP was studied through particle size distribution analysis, X-ray photoelectron spectroscopy, electrochemical tests, and UV-visible spectroscopy. The results show that EDTA-2K reacts with aluminum ions (Al3+) to form a soluble Al-EDTA complex, which promotes the corrosion rate on the Al surface and thus increases the removal rate of Al.

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

The Role of EDTA-2K in the Chemical Mechanical Polishing of Aluminum

Yang

Mei

Xie

et al. 2023

“…During the CMP process of polysilicon wafers, the high temperature and high pressure between the abrasive and the local contact point would lead to a series of complex tribochemical reactions. 25 Under the action of alkaline slurry polysilicon wafers formed a corrosive softening layer, which was removed by mechanical action of the abrasive and exposed a new surface that allowed the entire reaction cycle to proceed. 23,24 An ultra-smooth polished surface could only be obtained when the rate of formation of the softening layer was balanced by the rate of removal of the abrasive.…”

Section: Resultsmentioning

confidence: 99%

“…Wang et al 25 studied the synergistic effect of glycine and TT-LYK to effectively control galvanic corrosion between Al-Co interfaces in alkaline polishing liquid. The study of Qinzhi Xu and Lan Chen 26 examined the effect of different pH values in polishing liquid on the removal rate of aluminum.…”

mentioning

confidence: 99%

Effect of Different pH in HKMG on the Selection Ratio of Al and Poly Removal Rates

Wang

et al. 2023

When the characteristic size of integrated circuits developed to 28 nm and below according to Moore's Law, aluminum was widely used as a gate material in HKMG structures, and the chemical mechanical planarization (CMP) technology of aluminum gates was a breakthrough in the upgrading of HKMG post-gate process technology. Aluminum gate CMP requirements are much higher than aluminum wiring and Damascus wiring, the key to aluminum gate CMP is to achieve high material removal selectivity and high perfect surface. At home and abroad, the research on aluminum gate CMP is mostly concentrated on removal rate and Al-Co galvanic corrosion. This paper explores the influence of the rate selection ratio of aluminum and polysilicon under glycine hydrogen peroxide system with different pH conditions via CMP experiments, electrochemical experiments, ultraviolet, and X-ray photoelectron spectroscopy experiments, etc.

“…In order to reduce the leakage current because of short channel effect, metal gate/high-k stacks have been widely used in sub-45 nm technology node of complementary metal-oxide-semiconductor (CMOS). 1,2 Intel firstly proposed an approach of high-k metal gate (HKMG) integrated with a replacement meatal gate (RMG) for the 45 nm technology node. 3,4 Subsequently, IBM developed an Al-Co gate to effectively reduce the gate length to 11 nm.…”

mentioning

confidence: 99%

Synergetic Effect of 1,2,4-triazole and Glycine on Chemical Mechanical Planarization of Aluminum at Low Polishing Pressure in an Eco-Friendly Slurry

Sun

Wang

Liu

et al. 2020

In this paper, glycine and 1,2,4-triazole (TAZ) are used as eco-friendly additives to compensate the decrease in removal rate owing to the low polishing pressure in chemical mechanical planarization (CMP) of aluminum (Al) at near-neutral pH value. It demonstrated that the synergetic effect of glycine and TAZ participates in the formation of a weak passive layer with the hardness of 0.419 GPa on Al surface, which is compact enough to protect the Al surface from chemical dissolution and meanwhile relatively weak enough to achieve high polishing rate. Even at a low polishing pressure of 1.0 psi, a material removal rate of 750 nm min−1 with surface roughness of 0.19 nm was obtained in an eco-friendly slurry at pH 7.5. It was found that the weak passive layer is physicochemical formed on surface of Al with Al-TAZ bonds, which is subsequently complexed by glycine with Al-COOH bonds verified by Langmuir isotherm theory and X-ray photoelectron spectroscopy test. The above two synergistic parts are integrated into the material removal process. The material planarization mechanism in CMP process of Al was discussed as well.