Ion implantation apparatus and ion implantation method
AssigneeSumitomo Eaton Nova Corporation
InventorMitsuaki Kabasawa
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Abstract
In an ion implantation apparatus, a reduction of an energy contanimination is achieved when ions are implanted into a wafer with a low energy. A beam transportation efficiency between mutually different positions on a beam line correlates with the energy contamination of the wafer, and the beam transportation efficiency is adjusted so that the energy contamination becomes small. Since the beam transportation efficiency is obtained by measuring a beam electric current at each position, the beam transportation efficiency can be obtained before the ions are implanted into the wafer.
Claims24
An ion implantation apparatus for use in implanting an ion beam into a wafer by conducting the ion beam to the wafer along a predetermined path, the ion implantation apparatus comprising:
- means for measuring, along the predetermined path, beam electric currents at a plurality of measurement positions different from each other;
- means for obtaining a beam transport efficiency between the measurement positions from the beam electric currents measured at respective measurement positions to estimate a ratio of energy contamination specified by a neutralized ion beam and a desired ion beam both of which are implanted in the wafer, by using a correlation between the energy contamination and the beam transport efficiency.
An ion implantation method for use in an ion implantation apparatus comprising an ion source, an extraction electrode, a mass analysis unit, a mass analysis slit, and a wafer processing chamber, comprising the steps of:
- deciding a target value of energy contamination in a wafer;
- measuring, along a predetermined path, beam electric currents at a plurality of measurement positions different from each other to obtain a beam transport efficiency of an ion beam;
- and
- adjusting transport efficiency and the energy contamination.
A method of implanting ions into a wafer, comprising the steps of:
- setting a beam transport efficiency to a predetermined value;
- decreasing a neutral fraction of the beam;
- monitoring the beam transport efficiency;
- and
- reducing an energy contamination to a value lower than a target value.
An ion implantation apparatus comprising an ion source, an extraction electrode, a mass analysis unit, a mass analysis slit, and a wafer processing chamber, the apparatus having a measurement point determined at an intermediate convergent point or at a front or rear position of the mass analysis slit and being controlled so that a neutral fraction of a beam becomes lower than a predetermined rate.
An ion implantation apparatus, comprising:
- a table for storing measured results in necessary beam electric current values on the basis of an inverse proportion relation between a beam transport efficiency for each ion species and an amount of an energy contamination;
- and
- means for adjusting the energy contamination of ion implantation at each necessary beam electric current value, by using a limiting beam transport efficiency value obtained on the basis of the table.
Dependencies are inferred from the claim text.