利用添加劑來改善銅膜性質,如沉積速率,電阻率,晶向比率,

There are several critical technical challenges which need to be met to enable electroless Cu deposition to become a generic ULSI metallization technology. These relate to (1) electroless Cu deposition at high plating rate with low electrical resistivity of deposits, (2) catalytic layer protection from passivation, (3) defect-free filling of sub-half-micron trenches/vias of high aspect ratios.
40nm thick TaN was deposited on silicon wafer. Cu seed layers were then deposited onto TaN/SiO2/Si by long throw sputtering or ionized metal plasma (IMP) method. Electroless Cu deposition solution contains copper sulfate (supplier of Cu2+cations), ethylenediaminetetraacetic acid (EDTA, the complexing agent for Cu2+ cations), potassium hydroxides (supplier of OH-), formaldehyde (reducing agents) and additives such as RE610 or PEG (surfactants and wetting agents).

The XRD data show that the growth orientation of electroless Cu films was affected by the seed layer. Raising temperature to 60 ℃ is a good way to improve the deposition rate, filling capability, grain size and resistivity. No void formation was observed in 0.18 μm trench when the temperature of the solution was raised to 60 ℃. The resistivity of the plated copper films is 2.0 μΩ-cm. However, at 75 ℃, the solution is unstable to plate the copper films. The seed layer will effect the Cu(111)/Cu(200) intensity ratio of the deposited copper films. Stirring the solution helps to dissolve the hydrogen gas produced by the redox reaction.

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