Laser annealing apparatus, and fabrication methods of polycrystalline silicon thin film and thin film transistor

A laser annealing apparatus, comprising:

• a laser generator, an optical system and an annealing chamber, wherein,
• the laser generator is configured to emit a laser beam, the laser beam is guided to the annealing chamber after passing the optical system;
• the optical system includes a beam splitter, the beam splitter decomposes the laser beam into a first beam and a second beam, an energy density of the first beam is greater than an energy density of the second beam, and the first beam and the second beam are guided into the annealing chamber for laser annealing;
• a side of the annealing chamber is provided with a first slit and a second slit, the first beam enters into the annealing chamber through the first slit, the second beam enters into the annealing chamber through the second slit, the first slit and the second slit are configured that the first slit is opened while the second slit is closed, and the second slit is opened while the first slit is closed;
• the optical system further includes a light uniformization component, a focus mirror and a reflection mirror, and in a propagation direction of the laser beam, the light uniformization component and the focus mirror are provided in front of the beam splitter, and the reflection mirror is provided after the beam splitter;
• the light uniformization component includes a short axis light uniformization element, a collection element, a long axis light uniformization element, a long axis expansion element and a short axis contraction element;
• and
• in the propagation direction of the laser beam, the short axis light uniformization element, the collection element, the long axis light uniformization element, the long axis expansion element, and the short axis contraction element are sequentially arranged in this order;
• the focus mirror includes a long axis focus mirror, a short axis focus mirror, and an auxiliary focus mirror;
• in the propagation direction of the laser beam, the long axis focus mirror is located between the long axis light uniformization element and the long axis expansion element;
• in the propagation direction of the laser beam, the short axis focus mirror is located between the short axis contraction element and the beam splitter;
• and
• in the propagation direction of the laser beam, the auxiliary focus mirror is located behind the beam splitter and the reflection mirror.