Method of etching a semiconductor device by an ion beam

A method of forming a hole of a predetermined shape at a surface area having a step-like portion on a protective film of a semiconductor device, said method comprising the steps of:

• extracting a high-intensity ion beam from a high-intensity ion source to obtain an extracted ion beam;
• focusing the extracted ion beam by an ion optical system to obtain a focused ion beam;
• determining a position of a high-level region (W2) relative to the step-like portion based on at least a scanning ion microscope image of the surface area including the step-like portion obtained from secondary particles produced when scanning the surface of said semiconductor device with the focused ion beam;
• pre-etching the high-level region by scanning substantially only the high-level region (W2) excluding said step-like portion with the focused ion beam so that the high-level region becomes substantially equal in level to a low-level region relative to the step-like portion;
• and,
• forming said hole having a substantially flat bottom on the semiconductor device by etching said high-level region and said low-level region while removing a remaining convex portion of the step-like portion, which is formed by said pre-etching, based on an ion beam sputtering rate increased in accordance with ion incident angle effect to said remaining convex portion, by scanning a whole region (W1) including said high-level region, said low-level region and said step-like portion of the semiconductor device where said hole is to be formed with the focused ion beam so that a wiring existing under the step-like portion of the protective film can be substantially completely cut.

A method of etching a semiconductor device having multi-layered wiring including an upper wiring conductor having an undulation, a lower wiring conductor and an insulating film between said upper and lower wiring conductors by an ion beam, comprising the steps of:

• extracting a high-intensity ion beam from a high-intensity ion source to obtain an extracted ion beam;
• focusing the extracted ion beam by an ion optical system;
• determining target shape data representing a target shape of a first hole to be formed with a curved bottom corresponding to the undulation of said upper wiring conductor in the semiconductor device;
• calculating scan control data relating to forming of said first hole having the target shape comprising first scanning by a scanning process including a whole area scanning by which the focused ion beam scans a whole area substantially corresponding to the first hole and a local area scanning by which the focused ion beam scans partially said whole area, wherein the scan control data is based on said target shape data, an ion incident angle effect on ion beam sputtering rate, a redeposition effect on sputtered hole profile and focused ion beam characteristics;
• and,
• repeating said scanning process according to said calculated scan control data so as to form said first hole having the target shape with a depth capable of reaching the insulating film formed between said upper and lower wiring conductors and the curved bottom of the first hole being formed only by said insulating film and having a configuration substantially corresponding to the undulation of said upper wiring conductor.