Method of implanting a substrate and an ion implanter for performing the method

An ion implanter comprising:

• an ion beam generator producing an implant beam having a predetermined beam flux of a desired atomic species,
• a substrate holder for holding a substrate to be implanted,
• mechanical scanning apparatus operable to translate a substrate on the holder in a translation direction transverse to the beam direction to produce at least one pass of the beam over the substrate, and to mechanically reciprocate the substrate transversely to said translation direction and transversely to the beam direction, to produce a plurality of scans of the beam over the substrate during each said pass,
• and a controller for said scanning apparatus to effect said translation of the substrate in a plurality of translation steps between respective pairs of successive said scans of the beam, whereby said scans draw on the substrate a raster of non-intersecting uniformly spaced substantially parallel lines.

An ion implanter comprising:

• an ion beam generator producing an implant beam having a predetermined beam flux of a desired atomic species,
• a substrate holder for holding a substrate to be implanted,
• mechanical scanning apparatus operable to translate a substrate on the holder parallel in a translation direction transverse to the beam direction to produce at least one pass of the beam over the substrate, and to mechanically reciprocate the substrate transversely to said translation direction and transversely to the beam direction, to produce a plurality of scans of the beam over the substrate during each said pass, whereby said scans draw on the substrate a raster of lines having mid-points which have a predetermined spacing in said translation direction, and whereby said raster provides an implanted dose of said atomic species over the substrate, said implanted dose having a uniformity in said translation direction which includes a uniformity component which is a function of said predetermined spacing,
• a beam profiler to measure the cross-sectional profile of the ion beam at least in said translation direction, and a controller for said scanning apparatus operative
• a) to calculate a desired value of said spacing of said mid-points from data including said beam flux, the speed of said mechanical reciprocation and the desired dose per unit area to be delivered to the substrate,
• b) using said measured cross-sectional profile of the ion beam, to calculate a value of said dose uniformity component which would be obtained at the calculated desired spacing value, and
• c) to control said translation of the substrate to select said desired spacing value as the spacing to be employed, only if said calculated uniformity is not worse than a desired value of said uniformity component.

An ion implanter comprising:

• an ion beam generator producing an implant beam having a predetermined beam direction,
• a substrate holder for holding a substrate to be implanted at a desired orientation relative to the implant beam about an axis transverse to the plane of the substrate,
• a substrate scanner operative to produce relative movement between the substrate and the beam both (i) in a first direction transverse to the beam direction to produce at least one pass of the beam over the substrate and (ii) in a second direction transverse to the beam direction and said first direction to produce a plurality of scans of the beam over the substrate during each said pass, whereby said scans draw on the substrate a raster of lines having mid-points which have predetermined spacing in said first direction,
• and a controller for said scanner and said holder operative to orient the substrate to a first said orientation and, with the substrate in said first orientation, to produce a first said relative movement to draw on the substrate a first said raster of lines,
• and then to orient the substrate to a second said orientation at 180° about said axis to said first orientation and, in said second orientation, to produce a second said relative movement to draw on the substrate a second said raster of lines which are interleaved with the lines of said first raster.

An ion implanter comprising:

• an ion beam generator producing an implant beam having a beam flux of a desired atomic species.
• a substrate holder for holding a substrate to be implanted,
• mechanical scanning apparatus operable to translate a substrate on the holder in a translation direction transverse to the beam direction to produce at least one pass of the beam over the substrate, and to mechanically reciprocate the substrate transversely to said translation direction and transversely to the beam direction, to produce a plurality of scans of the beam over the substrate during each said pass, whereby said scans draw on the substrate a raster of lines, and whereby said raster provides an implanted dose of said atomic species over the substrate,
• and a controller for said scanning apparatus operative such that said scans of a pass have different lengths to reduce the aggregate of times at the ends of each scan during which no beam flux is absorbed by the substrate.

An ion implanter comprising an ion beam generator producing an implant beam having a predetermined beam direction,

• a substrate holder for holding a substrate to be implanted at a desired orientation relative to the implant beam about an axis transverse to the plane of the substrate,
• a substrate scanner operative to produce relative movement between the substrate and the beam both (i) in a first direction transverse to the beam direction to produce at least one pass of the beam over the substrate and (ii) in a second direction transverse to the beam direction and said first direction to produce a plurality of scans of the beam over the substrate during each said pass, whereby said scans draw on the substrate a raster of lines
• and a controller for said scanner and said holder operative to orient the substrate to a first said orientation and, with the substrate in said first orientation, to produce a first said relative movement to draw on the substrate a first said raster of lines,
• and then to orient the substrate to a second said orientation at 180° about said axis to said first orientation and, in said second orientation, to produce a second said relative movement to draw on the substrate a second said raster of lines which are interlaced with the lines of said first raster.