Method for characterizing defects on semiconductor wafers

A method of characterizing defects on a test surface, wherein the test surface is contained within a test volume represented by a Cartesian coordinate system having x, y, and z axes describing a set of unique x-y-z coordinates, the method comprising the steps of:

• scanning the test surface in the test volume with a focussed beam so that the focal point of the focussed beam coincides, in turn, with each unique x-y-z coordinate within the test volume;
• determining, for each column of points specified by a unique x-y coordinate in the test volume, a maximum reflected intensity value of the focussed beam;
• storing all the maximum reflected intensity values for all the unique x-y coordinates to form an array of test data representing a two-dimensional image of the test surface;
• extracting a set of intensity test primitives from the intensity test data;
• comparing the set of intensity test primitives with a set of intensity reference primitives to determine whether the set of intensity test primitives is different from the set of intensity reference primitives;
• if a difference exists between the set of intensity test primitives and the set of intensity reference primitives, then
• generating intensity difference data from the difference between the set of intensity test primitives and the set of intensity reference primitives,
• extracting intensity defect parameters from the intensity difference data, and
• matching the intensity defect parameters with a knowledge base of intensity defect reference data;
• determining, for each column of points specified by a unique x-y coordinate of the test volume, the z coordinate resulting in a maximum reflected intensity of the focussed beam;
• storing all the locations along the z axis of all of the points on the test surface to form an array of z test data representing a three-dimensional image of the test surface
• extracting a set of z test primitives from the z test data;
• comparing the set of z test primitives with a set of z reference primitives to determine whether the set of z test primitives is different from the set of z reference primitives;
• if a difference exists between the set of z test primitives and the set of z reference primitives, then
• generating z difference data from the difference between the set of z test primitives and the set of z reference primitives,
• extracting z defect parameters from the z difference data, and
• matching the z defect parameters with a knowledge base of z defect reference data.

A method of characterizing defects on a test surface, wherein the test surface is contained within a test volume represented by a Cartesian coordinate system having x, y, and z axes describing a set of unique x-y-z coordinates, the method comprising the steps of:

• scanning the test surface in the test volume with a focussed beam so that the focal point of the focussed beam coincides, in turn, with each unique x-y-z coordinate within the test volume;
• determining, for each column of points specified by a unique x-v coordinate in the test volume, a maximum reflected intensity value of the focussed beam;
• storing all of the maximum reflected intensity values for all of the unique x-y coordinates as an array of test data representing a two-dimensional image of the test surface;
• extracting a set of intensity test primitives from the intensity test data;
• comparing the set of intensity test primitives with a set of intensity reference primitives to determine whether the set of intensity test primitives is different from the set of intensity reference primitives;
• and
• if a difference exists between the set of intensity test primitives and the set of intensity reference primitives, then
• generating difference data from the difference between the set of reference primitives and the set of test primitives,
• extracting defect parameters from the difference data, and
• matching the defect parameters with a knowledge base of defect reference data.