The use of high down forces, abrasive slurry particles, and strong oxides make chemical mechanical planarization (CMP) techniques unfavorable for the future of CMOS device fabrication. Electrochemical mechanical planarization (ECMP) is a novel technology that is slowly replacing the current method of CMP for planarizing integrated circuits. ECMP provides more control over material removal rates while using less down force onto the wafer. ECMP has not been well studied and information about key factors such as electrolyte composition, i.e., influence of additives, pad/wafer interactions, pad/electrolyte interactions, applied electrical potential, effect of down force, tool geometry, are crucial to understand before ECMP will be considered for mainstream wafer processing. The low pressure, and possibly abrasive-free, capability of ECMP is particularly attractive for processing 65 nm and smaller structures containing mechanically fragile, porous low-k materials. ECMP involves precisely controlled material removal through simple adjustment of electrochemical variables in presence of different additives. In this chapter, an introduction to the ECMP process with the state of art for this technology is presented. Electrolyte studies using rotating disk electrode (RDE) setups are discussed and the effect of corrosion organic inhibitors investigated. The present chapter shows that benzotriazole (BTAH), which shows only a modest inhibition efficiency against the dissolution of copper in the acidic media, can be highly effective in neutral solutions. This can be attributed to the formation of a protective Cu(I)BTA complex at the copper surface. The film forms as a result of the reduction of Cu2+ to Cu+ ions, which react with the adsorbed BTAH to form the complex. Achieving the uniform across the wafer planarization in this technique, however, relies on controlled and repetitive formation and subsequent removal of a thin passivating layer at the sample surface. The opposite behavior is observed in the presence of phenyl-1H-tetrazole (PTA). It can be shown that the efficiency of PTA against the dissolution of copper is significantly higher in acidic than in neutral media.

Electrochemical mechanical planarization of copper with corrosion organic inhibitors

MAGAGNIN, LUCA;COJOCARU, PAULA
2009-01-01

Abstract

The use of high down forces, abrasive slurry particles, and strong oxides make chemical mechanical planarization (CMP) techniques unfavorable for the future of CMOS device fabrication. Electrochemical mechanical planarization (ECMP) is a novel technology that is slowly replacing the current method of CMP for planarizing integrated circuits. ECMP provides more control over material removal rates while using less down force onto the wafer. ECMP has not been well studied and information about key factors such as electrolyte composition, i.e., influence of additives, pad/wafer interactions, pad/electrolyte interactions, applied electrical potential, effect of down force, tool geometry, are crucial to understand before ECMP will be considered for mainstream wafer processing. The low pressure, and possibly abrasive-free, capability of ECMP is particularly attractive for processing 65 nm and smaller structures containing mechanically fragile, porous low-k materials. ECMP involves precisely controlled material removal through simple adjustment of electrochemical variables in presence of different additives. In this chapter, an introduction to the ECMP process with the state of art for this technology is presented. Electrolyte studies using rotating disk electrode (RDE) setups are discussed and the effect of corrosion organic inhibitors investigated. The present chapter shows that benzotriazole (BTAH), which shows only a modest inhibition efficiency against the dissolution of copper in the acidic media, can be highly effective in neutral solutions. This can be attributed to the formation of a protective Cu(I)BTA complex at the copper surface. The film forms as a result of the reduction of Cu2+ to Cu+ ions, which react with the adsorbed BTAH to form the complex. Achieving the uniform across the wafer planarization in this technique, however, relies on controlled and repetitive formation and subsequent removal of a thin passivating layer at the sample surface. The opposite behavior is observed in the presence of phenyl-1H-tetrazole (PTA). It can be shown that the efficiency of PTA against the dissolution of copper is significantly higher in acidic than in neutral media.
2009
Chemical Mineralogy, Smelting and Metallization
9781606928530
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/568150
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