Laser processing apparatus and laser processing method

A laser processing apparatus comprising:

• a substrate holding unit which horizontally holds a substrate;
• a laser beam irradiating unit which irradiates a laser beam onto a surface of a substrate held on the substrate holding unit in order to carry out a processing operation with respect to the surface of the substrate;
• imaging means having an optical axis which is coaxial to an optical axis of a laser beam incident to the substrate, the imaging means imaging a substrate in order to align the substrate with the laser beam irradiating unit;
• a liquid supply nozzle which supplies a liquid onto the surface of the substrate held on the substrate holding unit;
• a guide member provided between the substrate held on the substrate holding unit and the imaging means, being formed in a reversed conical shape having a flat bottom face, the guide member having a bottom face facing the surface of the substrate, the guide member guiding the liquid ejected from the liquid supply nozzle so as to pass between the bottom face and the surface of the substrate, the guide member transmitting a laser beam from the laser beam irradiating unit;
• a nozzle unit including a nozzle main body which forms a half divided cylinder shape, and supports the guide member;
• a purge gas nozzle which blows a purge gas to a bottom face of the guide member in order to remove a liquid adhering to the bottom face of the guide member, the liquid supply nozzle and the purge gas nozzle each have ejection ports disposed so as to surround the guide member, and are incorporated in the nozzle main body;
• and
• a moving mechanism which moves the substrate holding unit and the laser beam irradiating unit relatively in a horizontal direction in order to move an irradiation position of a laser beam in a surface of the substrate.