Ion shower doping system for TFT-LCDs

Recently, improvement of LCD of TFT toward more large-size and high-density are carried on. And, improvement of yield and operation rate are required for manufacturing equipment. Ion shower doping technique which is impurity doping for silicon thin film for making source/drain region become attractive. It has unique characters which are different from conventional ion implantation system. Its ion beam is without mass separation technique which is used by conventional ion implanter. And, ions are implanted into whole area of glass substrate without beam scanning. This system is able to irradiate ion beam which current density is 20uA/cm2. Implantation which dose is 1x10(16) cm(-2) is finished for about 80s. Next, we discuss new type ion source for ion shower doping system. It is pointed that temperature rising of substrate is a severe problem for resist process. Conventional system uses typically 5% PH3 ( or B2H6) gas diluted with hydrogen gas. So, hydrogen ion in ion beam is extra heat source. If we can remove hydrogen ion, substrate temperature decrease. New type ion source can prevent extraction of hydrogen ion from ion source plasma. For preliminary examinations, increased phosphorous ratio in ion beam is up to about 80%.