Effect of UV Radiation on Oxidation for Ru CMP

Abstract

As feature size continue to decrease, traditional copper (Cu) interconnections will encounter many problems. Ruthenium (Ru) is selected as a barrier material and even a future interconnection metal material because of its many advantages. However, due to its high hardness and chemical inertness, Ru is difficult to be removed during chemical mechanical polishing (CMP). In this study, the effect of UV-activated potassium persulfate (K2S2O8) on the removal rate of Ru CMP was studied. X-ray photoelectron spectroscopy (XPS) combined with electrochemistry is used to study the removal mechanism and chemical reactions. The results show that ultraviolet rays can enhance the chemical action in the CMP process and change the removal rate. Under the condition of 80 mM, the promotion rate is about 28.01%. When the particle diameter increases to 80 nm, the removal rate is also significantly increased by about 26.36%. Mechanism analysis shows that, on the one hand, it is affected by diffusion-control. On the other hand, the surface RuO3 and K2S2O8 undergo a Fenton-like reaction under UV conditions, which makes the Ru surface loose and porous (Rq = 0.533 nm), so it is easier to remove under mechanical action.

Materials Quest for Advanced Interconnect Metallization in Integrated Circuits

“…[ 189 ] Therefore, oxidizing agents, such as potassium perchlorate (KClO 4 ), potassium permanganate (KMnO 4 ), sodium hypochlorite (NaClO), potassium bromate (KBrO 3 ), potassium persulfate (K 2 S 2 O 8 ), potassium periodate (KIO 4 ), and hydrogen peroxide (H 2 O 2 ), have been screened. [ 190 , 191 , 192 , 193 , 194 , 195 , 196 ] The presence of IO 4 − ions in the slurry promotes the formation of mechanical structures and porous oxide layers on the Ru surface. It accelerates surface corrosion, thereby increasing the Ru removal rate.…”

Effect of ethylenediamine on CMP performance of ruthenium in H2O2-based slurries

“…To meet the requirements of efficient ruthenium removal, the researchers screened a number of oxidizers, such as KMnO 4 (potassium permanganate), KClO 4 (potassium perchlorate), NaIO 4 (sodium periodate), K 3 [Fe(CN) 6 ] (potassium ferricyanide), potassium peroxymonosulfate (oxone), K 2 S 2 O 8 (potassium persulfate), KIO 4 (potassium periodate), (NH 4 ) 2 S 2 O 8 (ammonium persulphate) and H 2 O 2 (hydrogen peroxide), among which KIO 4 and H 2 O 2 receive widespread attention. [7][8][9]12,[14][15][16][17][18][19][20][21] H. Cui et al 22 studied the effect of various oxidizers on the removal rate of ruthenium from the perspective of surface corrosion and oxidation. The experimental results suggested that the existence of IO 4…”

Effect of Novel pH Regulators on Copper film Chemical Mechanical Polishing for Ruthenium-Based Copper Interconnect under Weak Alkalinity Conditions

“…To meet the increasing demand for barrier layer materials, the use of Ru has become the preferred material for low-technology nodes. [7][8][9][10][11] The schematic illustration of Ru-based Cu CMP is presented in Fig. 1.…”