Substrate processing apparatus

1. A substrate processing apparatus for processing a surface of a substrate by a processing fluid, comprising:

a substrate holder in the form of a flat plate, the substrate being placeable in a horizontal posture on an upper surface of the substrate holder;

a chamber including a processing space capable of accommodating the substrate holder having the substrate placed thereon and a side surface having an aperture that communicates with the processing space and allows the substrate holder to pass through; and

a lid part configured to close the aperture by coming into contact with the chamber via a sealing member,

wherein:

the substrate holder projects on a chamber side surface of the lid part and the lid part closes the aperture with the substrate holder inserted in the processing space,

the chamber is provided with an introduction flow passage for receiving the processing fluid from outside the chamber and introducing the processing fluid into the processing space,

the introduction flow passage is open to the processing space on a side further backward than the substrate in the processing space when viewed from the aperture,

a ceiling surface of the processing space and an upper surface of the substrate holder are facing each other in parallel across a gap on a side closer to the aperture than the substrate in the processing space, thereby forming an upper flow passage having a constant flow passage cross-sectional shape, the processing fluid having passed above the substrate flowing in the upper flow passage,

the upper flow passage is formed by being surrounded by the lid part, the chamber and the sealing member and connected to a buffer space having a larger flow passage cross-sectional area than the upper flow passage, and

a discharge flow passage for discharging the processing fluid to the outside of the chamber is connected to the buffer space.

2. The substrate processing apparatus according to claim 1 , wherein a flowing direction of the processing fluid is changed by 90 degree or more in a connecting part of the upper flow passage and the buffer space.

3. The substrate processing apparatus according to claim 1 , wherein:

a recess retracted further than an opening surface of the aperture is formed above the aperture in the side surface of the chamber, and

the sealing member and the lid part arranged above the recess close the recess to form the buffer space.

4. The substrate processing apparatus according to claim 3 , wherein a width of the recess is equal to or larger than an opening width of the aperture in a horizontal direction.

5. The substrate processing apparatus according to claim 3 , wherein the processing space and the recess are separated by a separation wall in the form of a horizontal flat plate.

6. The substrate processing apparatus according to claim 5 , wherein a size of a clearance between a tip of the separation wall and the lid part is equal to a size of a gap between the ceiling surface of the processing space and the upper surface of the substrate holder.

7. The substrate processing apparatus according to claim 1 , wherein:

a lower surface of the substrate holder and a bottom surface of the processing space are facing each other in parallel across a gap on the side closer to the aperture than the substrate in the processing space, thereby forming a lower flow passage having a constant flow passage cross-sectional shape, the processing fluid having passed below the substrate flowing in the lower flow passage,

the lower flow passage is formed by being surrounded by the lid part, the chamber and the sealing member and connected to a lower buffer space having a larger flow passage cross-sectional area than the lower flow passage, and

a lower discharge flow passage for discharging the processing fluid to the outside of the chamber is connected to the lower buffer space.

8. The substrate processing apparatus according to claim 1 , wherein the processing fluid is a supercritical fluid.