Patent ID: 8419854

Claim:
A film-forming apparatus comprising a film-forming chamber and a shower head unit, the shower head unit having: a square material gas diffusion chamber having four corners; and a reactive gas diffusion chamber, wherein a gas passage connecting the square material gas diffusion chamber and a material gas introduction pipe together is constituted into two stages, a first stage having a number of first-stage gas passages and a second stage having a number of second-stage gas passages, the number of gas passages in each stage being represented by 2 n-1 (where n represents the number of the stage), the material gas introduction pipe is connected to a center of a first-stage gas passage, the first-stage gas passage communicates with the second-stage gas passages by connection holes that are provided on both ends of the first-stage gas passage and are connected to a center of each of the second-stage gas passages, and each of the second-stage gas passages is connected to the four corners of the square material gas diffusion chamber by connection holes formed on both ends of each of the second-stage gas passages.