Optical design for line generation using microlens array

A thermal processing apparatus for processing a semiconductor substrate, comprising:

• a substrate support;
• an array of laser diode bars emitting laser radiation at a first wavelength, the array of laser diode bars being arranged in plural parallel rows extending along a slow axis, the rows of laser diode bars being arranged in a stack along a fast axis, wherein the slow axis and the fast axis are orthogonal to an optical path between the array of laser diode bars and the substrate support;
• an illumination optics disposed between the array of laser diode bars and the substrate support along the optical path, the illumination optics comprising:
• a polarizing beamsplitter;
• a set of slow-axis lenses having at least a first cylindrical lens and a second cylindrical lens spaced apart from each other;
• a set of fast-axis lenses having at least a first cylindrical lens and a second cylindrical lens spaced apart from each other, the set of fast-axis lenses being disposed between the first cylindrical lens and second cylindrical lens of the set of slow-axis lenses;
• a dichroic mirror disposed downstream of the set of fast-axis lenses and configured to redirect laser radiation of a second and a third wavelengths reflected from the heated substrate to a pyrometer;
• and
• a waveplate disposed downstream of the dichroic mirror to transform the linear polarization of laser radiation into circular polarization;
• a homogenizer disposed between the illumination optics and the substrate support along the optical path for homogenizing laser radiation along the slow axis, the homogenizer comprising:
• a first lens array;
• and
• a second lens array, the lenses of the second lens array having a larger pitch than the lenses of the first lens array;
• and
• a condensing lens set disposed between the homogenizer and the substrate support along the optical path for focusing line image at a surface of the substrate, the condensing lens set comprising at least five spherical lenses.

A thermal processing apparatus for processing a semiconductor substrate, comprising:

• a substrate support;
• an array of laser diode bars arranged in plural parallel rows extending along a slow axis, the rows of laser diode bars being arrayed in a stack along a fast axis, the slow-axis being generally perpendicular to the fast-axis;
• an illumination optics disposed between the array of laser diode bars and the substrate support, the illumination optics comprising:
• a set of slow-axis lenses having at least a first cylindrical lens and a second cylindrical lens spaced apart from each other, the set of slow-axis lenses collimate laser beam radiation in the slow axis;
• and
• a set of fast-axis lenses having at least a first cylindrical lens and a second cylindrical lens spaced apart from each other, the set of fast-axis lenses being disposed between the first and second cylindrical lenses of the set of slow-axis lenses to collimate laser beam radiation in the fast axis;
• and
• a homogenizer disposed between the illumination optics and the substrate support for homogenizing laser beam radiation collimated by the illumination optics along the slow axis, the homogenizer comprising:
• a first lens array of cylindrical lenses;
• and
• a second lens array of cylindrical lenses disposed parallel and spaced apart from the first lens array of cylindrical lenses, wherein the lenses of the second lens array of cylindrical lenses have a larger pitch than the lenses of the first lens array of cylindrical lenses, and axes of the first lens array and axes of the second lens array are oriented parallel to a fast axis of the source of laser radiation;
• and
• a condensing lens set disposed between the homogenizer and the substrate support along an optical path intersecting the substrate support for focusing line image at a surface of the substrate, the condensing lens set comprising at least five spherical lenses.