Analysis of semiconductor surfaces by secondary ion mass spectrometry
AssigneeMicron Technology, Inc.
InventorEugene P. Marsh
Life of this patent
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Abstract
An apparatus and method for mass spectrometric determination of contaminant components of a thin oxide surface layer of a semiconductor wafer use a movable mechanical stage to scan and raster a large area of the wafer in a continuous scanning motion. The mass of analyte is greatly increased, resulting in improved sensitivity to trace components in the surface layer by a factor of 10-100 or more. A light beam interferometer is used to determine non-planarity from e.g. warping of the wafer and provide a correction by maintaining a constant separation between the wafer and the extraction plate or adjusting the electrical bias of the wafer relative to the extraction bias.
Claims13
A method for determining contaminant levels in a surface depth Q on a semiconductor material, said method comprising:
- scanning said semiconductor material in a first direction;
- mechanically rastering said semiconductor material in a second direction;
- and
- sputtering a portion of said surface layer to a depth not generally exceeding depth Q at a sputtering rate in mass per unit time controlled by varying a primary ion beam strength and the depth controlled by varying a scanning speed in length per unit time.
A method for determining contaminant levels in a surface layer of depth Q on a semiconductor material having a surface non-planarity, said method comprising:
- scanning said semiconductor material in a first direction;
- mechanically rastering said semiconductor material in a second direction;
- sputtering a portion of said surface layer to a depth not generally exceeding depth;
- measuring the non-planarity of said semiconductor material;
- and
- continuously correcting for the non-planarity of said semiconductor material during sputtering.
A method of providing a uniform extraction field on a surface layer of a semiconductor material irrespective of non-planarity, said method comprising:
- measuring the non-planarity of a surface of said semiconductor material;
- correcting for the non-planarity of said surface of said semiconductor material;
- and
- sputtering said surface layer of said semiconductor material to a substantially uniform depth.
Dependencies are inferred from the claim text.