Baohong Gao

Effect of annealing temperature on microstructure and thermoelectric properties of bismuth–telluride multilayer thin films prepared by magnetron sputtering

Abstract N-type bismuth–telluride (Bi–Te) multilayer thin films with total thickness of about 900 nm were deposited on amorphous structure glass substrate by magnetron sputtering at room temperature. The films were annealed at different temperatures under Ar ambient for 1 hour. The effect of annealing temperature was investigated for Bi–Te multilayer thin films by surface topography, chemical composition, crystal structure and thermoelectric properties. The results show that the Bi–Te multilayer thin films are all transformed into Bi–Te-based compounds. With the annealing temperature increasing, the films undergo an island growth mode with column structure, and grain size increases from 16·4 to 23·1 nm; in addition, the electrical conductivity and carrier mobility increase monotonously. The maximum Seebeck coefficient (−98·5 μV K−1) and power factor (14·47 μW K−2 cm−1) can be obtained for stoichiometric Bi2Te3 films annealed at 150°C.

A novel compound cleaning solution for benzotriazole removal after copper CMP

After the chemical mechanical planarization (CMP) process, the copper surface is contaminated by a mass of particles (e.g.silica) and organic residues (e.g.benzotriazole), which could do great harm to the integrated circuit, so post-CMP cleaning is essential.In particular, benzotriazole (BTA) forms a layer of Cu-BTA film with copper on the surface, which leads to a hydrophobic surface of copper.So an effective cleaning solution is needed to remove BTA from the copper surface.In this work, a new compound cleaning solution is designed to solve two major problems caused by BTA:one is removing BTA and the other is copper surface corrosion that is caused by the cleaning solution.The cleaning solution is formed of alkaline chelating agent (FA/O II type), which is used to remove BTA, and a surfactant (FA/O I type), which is used as a corrosion inhibitor.BTA removal is characterized by contact angle measurements and electrochemical techniques.The inhibiting corrosion ability of the surfactant is also characterized by electrochemical techniques.The proposed compound cleaning solution shows advantages in removing BTA without corroding the copper surface.