Double-cathode intermittent copper polishing method

Abstract

The invention discloses a double-cathode intermittent copper polishing method. The double-cathode intermittent copper polishing method is a copper surface polishing method which is good in polishing effect, high in efficiency and convenient to operate. The method comprises the following steps: preparing a polishing solution and placing the polishing solution into a reaction vessel; immersing two carbon rods in the solution to serve as cathodes, and placing a copper sheet to be polished between the two cathodes to serve as an anode; and switching on a power supply to carry out intermittent polishing, namely, carrying out polishing continuously for a certain period of time (10-20s) under a certain current density (1.5-2.5 A / cm < 2 >), then reducing the current density to 0 and keeping the state for a certain period of time (such as 5-10 min), then carrying out polishing continuously for a certain period of time (10-20 s) under a certain current density (1.5-2.5 A / cm < 2 >), and repeating the operation for 5-10 times, wherein every 100g of the polishing solution comprises 64.7g of phosphoric acid with the purity of 85%, 0.3g of ascorbic acid with the purity of 99%, 0.2g of ethylene thiourea with the purity of 97% and the balance 34.8g of water.

Description

technical field [0001] The invention belongs to the field of electrochemistry and relates to a method for electrochemically polishing copper, in particular to a method for discontinuously polishing copper with double cathodes to prepare smooth and defect-free copper materials. Background technique [0002] Copper has good thermal and electrical properties and is widely used in large-scale integrated circuits. In the application process, it is often necessary to polish the copper surface to obtain a smooth and defect-free copper surface. Chemical mechanical polishing technology uses the synergistic effect of chemistry and machinery to complete the complete polishing of the copper surface, and has been used in the field of integrated circuit manufacturing for more than 20 years. [0003] With the development of technology, the feature size of the copper interconnection layer becomes thinner and thinner. In order to eliminate the RC delay effect, the interlayer dielectric cons...

AI Technical Summary

Problems solved by technology

Traditional electrochemical polishing only polishes one side of the copper sheet, and there will be a slight polishing reaction on the edge of the other side of the copper sheet during polishing, resulting in different material removal rates for the overall copper sheet, and as the reaction continues, the temperature of the solution rises High, the resistivity increases, the polishing current increases, the reaction rate is too fast, and the copper surface roughness Ra is higher

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