1 Exhibit 21.1 SUBSIDIARIES OF THE REGISTRANT JURISDICTION OF SUBSIDIARY INCORPORATION OR ORGANIZATION - ---------------------------------------------------------------------------------------------- Eaton Semiconductor Limited Korea Eaton Services Pte Limited Singapore Axcelis Technologies, Inc. (Branch) Malaysia Axcelis Technologies, Inc. (Branch) India High Temperature Engineering Corporation (Delaware) United States Sumitomo Eaton Nova Japan Fusion Systems Corporation (Delaware) United States Fusion Technology International Inc. (Delaware) United States Fusion Europe Limited United Kingdom Axcelis Technologies Sarl France Fusion Semiconductor KK Japan Axcelis Technologies GmbH Germany Fusion Pacific Limited Korea Axcelis Technologies Limited United Kingdom Axcelis Technologies Ltd. Taiwan Axcelis Technologies Srl Italy Fusion Semiconductor Systems Corp. (Maryland) United States Fusion Investments Inc. (Maryland) United States Fusion Advanced Tech Corp. (Delaware) United States