| 摘要 |
PURPOSE:To form an impurity region, in which a potential gradient is generated, by conducting scanning, increasing the current density of ion beams gradually and continuously by computer control and performing scanning, elevating the current density of ion beams in a stepped manner. CONSTITUTION:The convergent ion beams of phosphorus ions (P<+>) having a beam diameter such as 0.1mumphi one are scanned under the conditions of acceleration energy of 100KeV and beam scanning speed of 10cm/s in order to shape an n-type impurity region having a potential gradient to a p-type Si substrate 4 (e.g., substrate concentration 1X10<15>cm<-3>). The current density of convergent ion beams is changed into 10-20mA/cm<2> at that time by controlling field strength applied to a liquid metallic ion source by a computer. Consequently, phosphorus ions are implanted onto the Si substrate in effective dosage of 5-10X10<15>/cm<2>. Implanted ions are activated through heat treatment for approximately one hr at a temperature of 800 deg.C, and the n-type impurity region 6 having a potential gradient within a range of 3-10eV is formed.
|
