Inductively coupled plasma reactive ion etching (ICP-RIE) of copper thin films patterned with SiO₂ hard masks was carried out using piperidine/O₂/Ar gas mixture. The etch rate, etch selectivity, and etch profile of copper thin films were investigated by varying gas concentration in piperidine/O₂/Ar gas mixture. In addition, the etch parameters including ICP RF power, DC-bias voltage to substrate, and process pressure were varied to examine the etch characteristics. X-ray photoelectron spectroscopy and optical emission spectroscopy were employed to elucidate the etch mechanism under piperidine/O₂/Ar gas chemistry. Finally, 150 nm-line patterned copper thin films were successfully etched using piperidine/ O₂/Ar etch gas under the optimized etch conditions.

A textured front surface is required in high efficiency silicon solar cells to reduce reflectance and to improve light trapping. Wet etching with alkaline solution is usually applied for mono crystalline silicon solar cells. However, alkali texturing method is not appropriate for multi-crystalline silicon wafers due to grain boundary of random crystallographic orientation. Accordingly, acid texturing method is generally used for multi-crystalline silicon wafers to reduce the surface reflectance. To reduce reflectivity of multi-crystalline silicon wafers, double texturing method with combination of acid and reactive ion etching is an attractive technical solution. In this paper, we have studied to optimize RIE condition by different RF power condition (100, 150, 200, 250, 300 W).

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study. the wafers were first texturing by NaOH solution at 80℃ for 35 min. Then the wafers were texturing by SF_6 and O_2 plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.