| abstract |
In the manufacture of a large-area electronic device such as a large-area liquid-crystal display device with thin-film address and drive circuitry, a plasma treatment is carried out on a device substrate (4) which is mounted on a supporting electrode (11) facing a perforated gas-feeding electrode (12). A reactive plasma (5) is generated in a space between the electrodes (11, 12) from a mixture of reaction gases which is fed into the space through at least the perforated electrode (12). The mixture of gases comprises a first reaction gas (e.g. SiH 4 ) which is depleted at a faster rate in the plasma treatment than a second reaction gas (e.g N 2 ). Through an area (12b) of the perforated electrode, one or more second supply lines (22) feeds a secondary mixture which is richer in the first reaction gas than a primary mixture supplied by a first supply line (21). This arrangement permits the plasma treatment to be carried out more uniformly over the area of the supporting electrode (11), by fine tuning the gas composition in depleted areas after the main aspects of the process performance (e.g temperature, pressure, reactant gases, composition of the primary mixture) have been determined in accordance with the desired plasma treatment properties. |