Ion implantation method, ion implanter, and method for manufacturing semiconductor device

An ion implanter comprising:

• a beam scan unit that generates a first scan beam by performing a reciprocating scan using a spot-like ion beam in a predetermined direction, based on a first scan signal;
• a beam measurement device configured to measure a beam current of the first scan beam at a plurality of measurement positions different in the predetermined direction;
• and
• a control device that generates a scan signal for determining a time waveform of a plurality of scan command values with respect to scan positions in the predetermined direction, based on a measurement obtained by the beam measurement device,
• wherein the control device is configured to
• acquire a time waveform of the beam current of the first scan beam measured at the plurality of measurement positions,
• calculate a beam current matrix in which beam current values with respect to a plurality of positions different in the predetermined direction and the plurality of scan command values are set as components, based on the acquired time waveform of the beam current and the time waveform of the scan command values determined in the first scan signal,
• calculate a first beam current density distribution of the first scan beam in the predetermined direction by performing time integration on the measured beam current,
• correct a value of each component of the beam current matrix, based on the first beam current density distribution, and
• generate a second scan signal for realizing a target beam current density distribution in the predetermined direction, based on the corrected beam current matrix,
• wherein the second scan signal is generated by performing an optimization calculation so that an evaluation function in which a first evaluation value and a second evaluation value are combined is minimized,
• wherein the first evaluation value evaluates a difference between a beam current density distribution calculated based on the corrected beam current matrix and a candidate second scan signal, and the target beam current density distribution, and
• wherein the second evaluation value evaluates variations in time change rates of scan command values in the candidate second scan signal.

A method for manufacturing a semiconductor device, comprising:

• an ion implantation process,
• wherein the ion implantation process includes
• generating a first scan beam by performing a reciprocating scan using a spot-like ion beam in a predetermined direction, based on a first scan signal,
• measuring a beam current of the first scan beam at a plurality of measurement positions different in the predetermined direction,
• calculating a beam current matrix in which beam current values with respect to a plurality of positions different in the predetermined direction and a plurality of scan command values are set as components, based on a time waveform of the measured beam current and a time waveform of the scan command values determined in the first scan signal,
• calculating a first beam current density distribution of the first scan beam in the predetermined direction by performing time integration on the measured beam current,
• correcting a value of each component of the beam current matrix, based on the first beam current density distribution,
• generating a second scan signal for realizing a target beam current density distribution in the predetermined direction, based on the corrected beam current matrix,
• generating a second scan beam by performing the reciprocating scan using the ion beam in the predetermined direction, based on the second scan signal, and
• irradiating a workpiece with the second scan beam,
• wherein the second scan signal is generated by performing an optimization calculation so that an evaluation function in which a first evaluation value and a second evaluation value are combined is minimized,
• wherein the first evaluation value evaluates a difference between a beam current density distribution calculated based on the corrected beam current matrix and a candidate second scan signal, and the target beam current density distribution, and
• wherein the second evaluation value evaluates variations in time change rates of scan command values in the candidate second scan signal.