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We investigated the etching characteristics of three kinds of methacrylate polymer films which have the same main chain with a different side chain using a plasma beam irradiation apparatus. The polymers are polytbutylmethacrylate (PtBuMA), polybenzylmethacrylate (PBMA), and polycyclohexylmethacrylate (PCHMA). The etch yield (EY) of PtBuMA was higher than those of the others in the case of N2 plasma beam. The EYs of PBMA and PCHMA increased with an increase in the ion energy of up to 330eV and saturated at over 330eV. On the other hand, that of PtBuMA was almost constant at the ion energy higher than 130eV. It was supposed that nitridation of the polymer plays an important role in the enhancement of etching by N2 plasma. In the case of Ar plasma, EY increased linearly with an increase in the square root of ion energy for every polymer. In the case of H2 plasmas, EY scarcely depended on the ion energy regardless of the polymers. Etching behaviors with Ar and H2 plasma irradiation showed physical sputtering and chemical sputtering, respectively. The order of the magnitude of EY was PtBuMA, PCHMA, and PBMA for all of the Ar, H2, and N2 plasmas.

Correlation between the early stage of copper metal organic chemical vapor deposition and the material properties of thin filmThe gap-filling property of Cu deposited by chemical vapor deposition was investigated in 1/4-m-wide trenches and 1/4-m-diam holes. Attention was paid to the influences on the gap-filling property of both substrate temperature and partial pressure of the source gas. At a low deposition temperature of 180°C, Cu could completely fill a hole with an aspect ratio of 7. A high deposition rate could be obtained at the high substrate temperature and high partial pressure of the source gas. However the coverage probably deteriorated because of the increase in sticking coefficient due to an increase in the reaction rate at high temperature. As the source gas pressure increased, the deposition rate increased and saturated in the high source pressure region. The good gap-filling property at high source pressures was attributed to the Langmuir-Hinshelwood reaction where almost the same deposition rate is realized from the top to the bottom of the trench. At a high temperature of 215°C, voids were observed at both the center and along the wall of the trench. The voids along the wall were assumed to be formed at the initial stage of deposition. They disappeared with an increase in source gas flow rate. Therefore, the formation of voids could be due to an insufficient supply of source gas. By annealing the Cu film, its properties of increase in grain size and the reduction in the amount of C, O, and F contaminants were improved. After annealing and chemical mechanical polishing treatment, scanning electron microscopy observation showed Cu interconnecting lines with grains larger than the wire width.

The authors investigated the etching characteristics of three kinds of methacrylate polymer films, which have the same main chain but with different side chains, using a plasma beam irradiation apparatus. The polymers are polytbutylmethacrylate, polybenzylmethacrylate, and polycyclohexylmethacrylate. The major desorbed products during nitrogen plasma beam etching were found to be HCN and C2N2 for all methacrylate polymer films. The desorbed products originating from the polymer structure, namely, the main chain and the side chain, were hardly observed. The energy distributions of desorbed products were mainly composed of Maxwell-Boltzmann distribution with a small component of collision cascade distribution for all three polymers and were slightly dependent on the ion energy. It is concluded that chemical sputtering, which can be defined as the production of weakly bound species by ion bombardment, followed by thermal desorption, is the significant ion induced mechanism of organic polymer etching.

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