Patent Number: 
Section: claims

1. A method of tuning an ion beam in an ion implanter, wherein the ion beam is dependent upon a plurality of operational parameters of the ion implanter, the method comprising:retrieving a set of operational parameters at least some of which are stored in a dynamic database;configuring the ion implanter according to the retrieved set of operational parameters thereby to provide an ion beam;optimizing the ion beam by varying one or more of the operational parameters; andupdating the operational parameters stored in the dynamic database that changed during optimization with rolling averages calculated using the values obtained for those operational parameters at the end of the optimization. 2. The method of claim 1, comprising updating the operational parameters only if a particular operational parameter changed within a predefined limit. 3. The method of claim 2, comprising updating the operational parameters only if a particular operational parameter changed by less than a predefined fraction. 4. The method of claim 1, comprising retrieving at least one of the set of operational parameters from those stored in a principal database. 5. The method of claim 4, wherein, if an operational parameter is stored in both the principal database and the dynamic database, the method comprises retrieving the operational parameter from the principal database in preference to the dynamic database. 6. The method of claim 4, comprising optimising the ion beam by varying one or more of the operational parameters and storing one or more operational parameters so established in the principal database. 7. The method of claim 4, wherein, even if an operational parameter that changed during optimisation was retrieved from the principal database, the method comprises updating that operational parameter stored in the dynamic database. 8. The method of claim 1, comprising retrieving a set of operational parameters associated with a particular implant recipe from a plurality of such sets associated with different implant recipes. 9. The method of claim 8 comprising, when an implant recipe does not have an associated set of operational parameters, retrieving a set of operational parameters stored in an initialisation database, configuring the ion implanter according to the retrieved set of operational parameters thereby to provide an ion beam, optimising the ion beam by varying one or more of the operational parameters, and storing the operational parameters in the dynamic database as determined during optimisation. 10. The method of claim 1, further comprising using an ion source of the ion implanter to generate the ion beam. 11. The method of claim 10, comprising retrieving a set of operational parameters from a plurality of such sets associated with different ages of the ion source. 12. The method of claim 11, comprising retrieving a set of operational parameters from a plurality of such sets associated with total ion beam current delivered by the ion source. 13. The method of claim 11, comprising retrieving a set of operational parameters from a plurality of such sets associated with the product of the age of the ion source and the total ion beam current delivered by the ion source. 14. The method of claim 11, further comprising resetting the operational parameters stored in the dynamic database after the ion source has been serviced or replaced. 15. The method of claim 11, further comprising keeping the operational parameters stored in the dynamic database after the ion source has been serviced or replaced, and subsequently retrieving a set of operational parameters from the plurality of such sets associated with different ages of the ion source according to the age of the ion source since servicing or replacement. 16. An ion implanter and a computer program comprising computer code instructions that, when executed, cause the ion implanter to operate in accordance with the method of claim 1. 17. A programmable controller arranged to retrieve from memory the computer program of claim 16 and to execute the computer program. 18. An ion implanter and a computer readable medium having recorded thereon a computer program that, when executed, causes the ion implanter to operate according to the method of claim 1. 19. An ion implanter comprising a controller configured to implement the method of claim 1.