Apparatus and method for determining the focus position
AssigneeVistec Semiconductor Systems GmbH
InventorMichael Heiden
Life of this patent
Estimating the term…
Abstract
An apparatus and a method for determining the focus of an optical system on a substrate are disclosed. A light source emits an auxiliary light beam into an auxiliary beam path, wherein the auxiliary light beam, after splitting, is offset in relation to an optical axis of a measuring objective. At least one optical switch is provided in the auxiliary beam path for switching the path of the auxiliary beam path from one side offset from the optical axis to the other side offset from the optical axis of the measuring objective.
Claims19
An apparatus for determining the focus of an optical system on a substrate, comprising:
- a measuring objective defining an optical axis;
- a light source emitting an auxiliary light beam in an auxiliary beam path, wherein each auxiliary light beam, after splitting, is offset in relation to the optical axis of the measuring objective;
- and
- at least one optical switch in the auxiliary beam path for switching the path of the auxiliary light beam from one side offset from the optical axis to the other side offset from the optical axis of the measuring objective.
A method for determining the focus of an optical system on a substrate, comprising the following steps:
- mapping at least one auxiliary light beam emitted by a light source with the aid of at least one lens onto an optical switch, which is provided in an optical axes of the apparatus;
- operating the optical switch in such a way that a path of the auxiliary light beam is switched from one side offset from the optical axis to the other side offset from the optical axis of the measuring objective;
- and
- directing the auxiliary light beam returning from the substrate onto a position-sensitive detector by means of a beam splitter.
Dependencies are inferred from the claim text.