Measuring apparatus
AssigneeMetryx Limited
InventorsRobert John Wilby, Adrian Kiermasz
Life of this patent
Estimating the term…
Abstract
Measuring apparatus for monitoring the position of the center of mass of a semiconductor wafer is disclosed. The apparatus includes a wafer support (14) with a ledge for supporting an edge of a wafer (2) when it is lifted at a detection point by a probe (16). The probe (16) is connected to a force sensor (18) which senses a force due to a moment of the wafer about a fulcrum (4) on the wafer support (14). Moment measurements are taken at a plurality of detection points and a processing unit calculates the position of the center of mass from the moment measurements. Changes in wafer mass distribution (e.g. due to faulty treatment steps) which cause movement of the center of mass can be detected.
Claims10
A method of monitoring a mass distribution of a semiconductor wafer during a fabrication process, the method including the steps of:
- measuring the force on a force sensing device due to the moment of the wafer about a pivot axis for each of a plurality of detection points on the wafer;
- calculating, in a processing unit, the moment at each detection point by determining a normal distance from the detection point to the pivot axis;
- and
- determining movement of centre of mass of the wafer using the calculated moments.
A method of monitoring a mass distribution of a semiconductor wafer during a fabrication process, the method including the steps of:
- before performing one or more fabrication processing steps on the semiconductor wafer,
- measuring the force on a force sensing device due to the moment of the wafer about a pivot axis for each of a plurality of detection points on the wafer,
- calculating, in a processing unit, the moment at each detection point by determining a normal distance from the detection point to the pivot axis, and
- determining a first position of centre of mass of the wafer using the calculated moments;
- performing the one or more fabrication processing steps on the semiconductor wafer;
- after performing one or more fabrication processing steps on the semiconductor wafer,
- measuring the force on a force sensing device due to the moment of the wafer about a pivot axis for each of a plurality of detection points on the wafer,
- calculating, in a processing unit, the moment at each detection point by determining a normal distance from the detection point to the pivot axis, and
- determining a second position of centre of mass of the wafer using the calculated moments;
- and
- comparing the first and second positions of centre of mass to determine a movement of the centre of mass caused by the one or more fabrication processing steps.
Dependencies are inferred from the claim text.