EXHIBIT 21 Subsidiaries of the Registrant PLASMA & MATERIALS TECHNOLOGIES (KOREA) CO., LTD., a Korean corporation PLASMA & MATERIALS TECHNOLOGIES, JAPAN KK, a Japanese corporation ELECTROTECH LIMITED, an English corporation ELECTROTECH EQUIPMENTS LIMITED, an English corporation ELECTROTECH (ASIA) LIMITED, an English corporation ELECTROTECH INTERNATIONAL LIMITED, an English corporation E.T. FABRICATIONS LIMITED, an English corporation E.T. ELECTROTECH RESEARCH LIMITED, an English corporation E.T. EQUIPMENTS LIMITED, an English corporation VACUUM CONTROL SYSTEMS LTD, an English corporation ELECTROTECH EQUIPMENTS, GmbH, a German limited liability company ELECTROTECH EQUIPMENTS, SARL, a French limited liability company