小型腔式微波离子源的研制

INVESTIGATION ON A COMPACT CAVITY TYPE MICROWAVE ION SOURCE

研制了１种用在离子束细胞刻蚀装置中的小型腔式微波离子源，它由石英放电管、同轴谐振腔和封装在管一端的二电极引出系统组成。该源由同轴腔激发起的表面波在石英管内产生等离子体柱。为了提高柱末端等离子体离子引出流密度，选用了在内径７．０ｍｍ直管的一端加上一内径５．０ｍｍ衬管的放电管。在微波频率为２．４５ＧＨｚ，输入功率为９３Ｗ下，氮的引出流密度分别为４８．４ｍＡ／ｃｍ２和９１．７ｍＡ／ｃｍ２。这种表面波放电等离子体源体积小、结构简单，可在较宽的压强范围内产生重复性好、工作稳定的等离子体柱。

A small cavity type microwave ion source used in the device of ion beam cell etching has been fabricated,which consists of a quartz discharge tube,a coaxial cavity and a two grid extractor enclosing one end of tube.The plasma column of the source was sustained by surface wave excited by the cavity.In order to increase ion current extracted from the end of the column,two different quartz tube configurations,a straight tube geomtry with inner diameter of φ 7 0 mm and the same straight tube inserted by a liner tube with inner diameter of φ 5 0 mm at one end,has been operated to verify our theory.For nitrogen,ion current density of 48 4 mA/cm 2 and 91 7 mA/cm 2 have been extracted from sources respectively,when they are operated at a frequency of 2 45 GHz and a incident power of 93 W.This plasma source is of many advantages,such as small volume,simple configuration and high density of ionized electron in the plasma with good stability and reproductivity over a large pressure range,etc.