Patent Number: 
Section: claims

1. An ion implantation method of implanting ions into a substrate using both a ribbon-like ion beam in which, with or without performing an X direction sweep, a dimension in an X direction is larger than a dimension in a Y direction that is orthogonal to the X direction, and a mechanical scan of the substrate in a direction intersecting with a principal face of the ion beam, said method comprising:a scan speed calculating step of setting an initial value of a scan number of the substrate to 1, and calculating a scan speed of the substrate by using a beam current of the ion beam, a dose amount to the substrate and the initial value of a scan number of the substrate;a scan speed determining step of: determining whether the scan speed of the substrate is within a predetermined allowable scan speed range or not; if the scan speed is within the allowable scan speed range, setting the current scan number and the current scan speed as a practical scan number and a practical scan speed, respectively; if the scan speed is higher than an upper limit of the allowable scan speed range, aborting a process of obtaining the practical scan number and the practical scan speed; and, if the scan speed is lower than a lower limit of the allowable scan speed range, incrementing the scan number by one to calculate a corrected scan number;a corrected-scan speed calculating step of, when the corrected scan number is calculated, calculating a corrected scan speed by using the corrected scan number, the beam current, and the dose amount;a repeating step of, when the corrected scan speed is calculated, performing a process of said scan speed determining step on the corrected scan speed, and repeating said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range; andan ion implanting step of implanting ions into the substrate in accordance with the practical scan number and the practical scan speed. 2. An ion implantation apparatus for implanting ions into a substrate using both a ribbon-like ion beam in which, with or without performing an X direction sweep, a dimension in an X direction is larger than a dimension in a Y direction that is orthogonal to the X direction, and a mechanical scan of the substrate in a direction intersecting with a principal face of the ion beam, said apparatus comprising:a controlling device having a function of performing: (a) a scan speed calculating process of setting an initial value of a scan number of the substrate to 1, and calculating a scan speed of the substrate by using a beam current of the ion beam, and a dose amount to the substrate, and the initial value of a scan number of the substrate; (b) a scan speed determining process of: determining whether the scan speed of the substrate is within a predetermined allowable scan speed range or not; if the scan speed is within the allowable scan speed range, setting the current scan number and the current scan speed as a practical scan number and a practical scan speed, respectively; if the scan speed is higher than an upper limit of the allowable scan speed range, aborting a process of obtaining the practical scan number and the practical scan speed; and, if the scan speed is lower than a lower limit of the allowable scan speed range, incrementing the scan number by one to calculate a corrected scan number; (c) a corrected-scan speed calculating process of, when the corrected scan number is calculated, calculating a corrected scan speed by using the corrected scan number, the beam current, and the dose amount; (d) a repeating process of, when the corrected scan speed is calculated, performing a process of said scan speed determining step on the corrected scan speed, and repeating said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range; and (e) an ion implanting process of implanting ions into the substrate in accordance with the practical scan number and the practical scan speed. 3. An ion implantation method according to claim 1,wherein the scan speed determining step includes a scan number determining step of, if the scan speed is within the allowable scan speed range, determining whether the current scan number is even or odd; if the current scan number is even, setting the current scan number and the current scan speed as the practical scan number and the practical scan speed, respectively; and, if the current scan number is odd, incrementing the scan number by one to calculate a corrected scan number, andwherein the repeating step repeats said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range and the corrected scan number becomes even. 4. An ion implantation apparatus according to claim 2,wherein the function of performing (b) the scan speed determining process includes a scan number determining process of, if the scan speed is within the allowable scan speed range, determining whether the current scan number is even or odd; if the current scan number is even, setting the current scan number and the current scan speed as the practical scan number and the practical scan speed, respectively; and, if the current scan number is odd, incrementing the scan number by one to calculate a corrected scan number, andwherein the function of performing (d) the repeating process repeats said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range and the corrected scan number becomes even. 5. An ion implantation method according to claim 1, wherein, in said scan speed calculating step, the initial value of the scan number of the substrate is set to 2 in place of 1. 6. An ion implantation apparatus according to claim 2, wherein, in said scan speed calculating process of said controlling device, the initial value of the scan number of the substrate is set to 2 in place of 1. 7. An ion implantation method according to claim 1, wherein, in said scan speed calculating step, the initial value of the scan number of the substrate is set to 2 in place of 1, and, in said scan speed determining step, the scan number is incremented by 2 in place of one to calculate the corrected scan number. 8. An ion implantation apparatus according to claim 2, wherein, in said scan speed calculating process of said controlling device, the initial value of the scan number of the substrate is set to 2 in place of 1, and, in said scan speed determining process, the scan number is incremented by 2 in place of one to calculate the corrected scan number. 9. An ion implantation method of implanting ions into a substrate using both a ribbon-like ion beam in which, with or without performing an X direction sweep, a dimension in an X direction is larger than a dimension in a Y direction that is orthogonal to the X direction, a mechanical scan of the substrate in a direction intersecting with a principal face of the ion beam, and performance of ion implantation while, during a period when the ion beam does not impinge on the substrate, rotating the substrate by a step of 360/m deg. about a center portion of the substrate, and dividing one rotation of the substrate into a plurality m of implanting steps, said method comprising:a scan speed calculating step of setting an initial value of a scan number of the substrate per implanting step to 1, and calculating a scan speed of the substrate by using a beam current of the ion beam, a dose amount to the substrate, a implanting step number, and the initial value of the scan number of the substrate, and;a scan speed determining step of: determining whether the scan speed of the substrate is within a predetermined allowable scan speed range or not; if the scan speed is within the allowable scan speed range, setting the current scan number per implanting step, and the current scan speed as a practical scan number per implanting step, and a practical scan speed, respectively; if the scan speed is higher than an upper limit of the allowable scan speed range, aborting a process of obtaining the practical scan number per implanting step, and the practical scan speed; and, if the scan speed is lower than a lower limit of the allowable scan speed range, incrementing the scan number per implanting step by one to calculate a corrected scan number per implanting step;a corrected-scan speed calculating step of, when the corrected scan number per implanting step is calculated, calculating a corrected scan speed by using the corrected scan number per implanting step, the beam current, the dose amount, and the implanting step number;a repeating step of, when the corrected scan speed is calculated, performing a process of said scan speed determining step on the corrected scan speed, and repeating said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range; andan ion implanting step of implanting ions into the substrate in accordance with the practical scan number per implanting step and the practical scan speed. 10. An ion implantation apparatus for implanting ions into a substrate using both a ribbon-like ion beam in which, with or without performing an X direction sweep, a dimension in an X direction is larger than a dimension in a Y direction that is orthogonal to the X direction, a mechanical scan of the substrate in a direction intersecting with a principal face of the ion beam, and performance of ion implantation while, during a period when the ion beam does not impinge on the substrate, rotating the substrate by a step of 360/m deg. about a center portion of the substrate, and dividing one rotation of the substrate into a plurality m of implanting steps, said apparatus comprising:a controlling device having a function of performing: (a) a scan speed calculating process of setting an initial value of a scan number of the substrate per implanting step to 1, and calculating a scan speed of the substrate by using a beam current of the ion beam, a dose amount to the substrate, a implanting step number and the initial value of the scan number of the substrate per implanting step; (b) a scan speed determining process of: determining whether the scan speed of the substrate is within a predetermined allowable scan speed range or not; if the scan speed is within the allowable scan speed range, setting the current scan number per implanting step, and the current scan speed as a practical scan number per implanting step, and a practical scan speed, respectively; if the scan speed is higher than an upper limit of the allowable scan speed range, aborting a process of obtaining the practical scan number per implanting step, and the practical scan speed; and, if the scan speed is lower than a lower limit of the allowable scan speed range, incrementing the scan number per implanting step by one to calculate a corrected scan number per implanting step; (c) a corrected-scan speed calculating process of, when the corrected scan number per implanting step is calculated, calculating a corrected scan speed, by using the corrected scan number per implanting step, the beam current, the dose amount, and the implanting step number; (d) a repeating process of, when the corrected scan speed is calculated, performing a process of said scan speed determining step on the corrected scan speed, and repeating said scan speed determining step and said corrected-scan speed calculating step until the corrected scan speed is within the allowable scan speed range; and (e) an ion implanting process of implanting ions into the substrate in accordance with the practical scan number per implanting step and the practical scan speed. 11. An ion implantation method according to claim 9, wherein the implanting step number is even. 12. An ion implantation apparatus according to claim 10, wherein the implanting step number is even.