An apparatus for manufacturing semiconductors includes a power amplifier to power a laser, a catalyst disposed in the power amplifier, an inlet port, and an exhaust port. The inlet port introduces a mixing gas to an interior of the power amplifier during a cleaning operation so that the mixing gas contacts a surface of the catalyst having a build-up thereon. The mixing gas reacts with and removes the build-up by generating gaseous by-products. The exhaust port removes the gaseous by-products from the power amplifier.