WAFER PROCESSING METHOD AND PROCESSING DEVICE

To provide a wafer processing method capable of solving such a problem that the time is required for removing a beveling part to lead to a low productivity and a problem that the other wafer is damaged.SOLUTION: A wafer processing method comprises: a modified layer formation step of forming modified layers S1 to S4 by positioning and radiating a focal point of a laser beal LB of a wavelength having transparency with respect to a first wafer 10 to an internal part from which a portion where a beveling part 10C and a notch 10d are formed is removed from a back surface 10b of the first wafer 10; and a grinding step of holding a second wafer 20 side on a chuck table 35, and reducing the thickness of the back surface 10b of the first wafer 10 by grinding. In the modified layer formation step, a plurality of the focal points P1 to P4 of the laser beam LB is formed in a down step form so as to gradually approach to a joint layer 20 from an internal side toward an external side of the wafer W. Modified layers S1 to S4 are widely formed by the plurality of focal points.SELECTED DRAWING: Figure 5 【課題】面取り部の除去に時間が掛かり、生産性が悪いという問題と共に、他方のウエーハに傷が付いてしまうという問題を解消することができるウエーハの加工方法を提供する【解決手段】第一のウエーハ１０に対して透過性を有する波長のレーザー光線ＬＢの集光点を第一のウエーハ１０の裏面１０ｂから面取り部１０Ｃ及びノッチ１０ｄが形成された部位を除去する内部に位置付けて照射し改質層Ｓ１～Ｓ４を形成する改質層形成工程と、第二のウエーハ２０側をチャックテーブル３５に保持し、第一のウエーハ１０の裏面１０ｂを研削して薄化する研削工程と、を含み、該改質層形成工程において、レーザー光線ＬＢの集光点Ｐ１～Ｐ４は、ウエーハＷの内側から外側に向かって徐々に接合層２０に近づくように下り階段状に複数形成され、複数の集光点によって改質層Ｓ１～Ｓ４が末広がりに形成される。【選択図】図５