Vaccum drying apparatus

A vacuum drying apparatus for performing a vacuum drying treatment to a photoresist coated on a surface of a substrate, wherein the vacuum drying apparatus comprises a sealed chamber, a gas pressure adjusting device, and a support platform in the sealed chamber, wherein

• the support platform is configured to support the substrate coated with the photoresist, the gas pressure adjusting device is disposed at a side of the sealed chamber, and the gas pressure adjusting device comprises a main air pipe and a branch air pipe for introducing a protection gas to the sealed chamber, wherein the branch air pipe is connected to the main air pipe, the branch air pipe extends in a direction perpendicular to a direction in which the main air pipe extends, and the main air pipe is symmetrically disposed at an upper portion and a lower portion of the side surface of the sealed chamber;
• the main air pipe comprises an upper main air pipe and a lower main air pipe which are symmetrically disposed at the upper portion and the lower portion of the side surface of the sealed chamber, the sealed chamber has a capacity of accommodating 2n pieces of the substrates, wherein the upper main air pipe is configured to supply air to upper n pieces of the substrates in the sealed chamber, and the lower main air pipe is configured to supply air to lower n pieces of the substrates in the sealed chamber, wherein n is a positive integer;
• and
• the branch air pipe is a double-layered pipe.