Cup and substrate processing apparatus

1. A cup for surrounding a substrate held in a substantially horizontal posture when the substrate is processed using a processing liquid, comprising:

a first member having an upper surface facing upward surrounding said substrate;

a second member having a lower surface facing downward arranged above said upper surface of said first member to surround said substrate; and

a third member surrounding said first and second members,

wherein a spacing between said upper surface of said first member and said lower surface of said second member gradually decreases outward from an outer peripheral portion of said substrate while a clearance is formed between said upper surface of said first member and said lower surface of said second member in respective outer peripheral portions of said first and second members,

a distance between an innermost edge of said upper surface of said first member and a center of the substrate is larger than a distance between an innermost edge of said lower surface of said second member and the center of the substrate as viewed in a side view taken parallel to the substrate,

the innermost edge of the upper surface of the first member is a portion of the upper surface closest to the center of the substrate as viewed in said side view,

the innermost edge of the lower surface of the second member is a portion of the lower surface closest to the center of the substrate as viewed in said side view, and

said third member has an inner surface spaced apart from said clearance outside said clearance and surrounding said clearance.

2. The cup according to claim 1 , wherein said inner surface of said third member extends from below a lower end of said clearance to above an upper end of said clearance.

3. The cup according to claim 1 , further comprising a closing member that closes a gap between said second member and said inner surface of said third member above said clearance.

4. The cup according to claim 1 , wherein a gap through which a downflow can pass is formed between the outer peripheral portion of said second member and said inner surface of said third member.

5. The cup according to claim 1 , wherein said upper surface of said first member, said lower surface of said second member, said clearance, and said inner surface of said third member have a shape rotationally symmetric about a common axis.

6. The cup according to claim 1 , wherein said lower surface of said second member is inclined outward and downward diagonally to an upper surface of said substrate.

7. The cup according to claim 6 , wherein said lower surface of said second member forms an angle of not less than 5 degrees nor more than 20 degrees with the upper surface of said substrate.

8. The cup according to claim 1 , wherein at least a region, on the side of an inner peripheral portion of said upper surface, of said first member is inclined outward and upward diagonally to an upper surface of said substrate.

9. The cup according to claim 8 , wherein said upper surface of said first member forms an angle of not less than 5 degrees nor more than 20 degrees with the upper surface of said substrate.

10. A substrate processing apparatus that processes a substrate, comprising:

a spin holder that holds and rotates the substrate in said substantially horizontal posture;

a processing liquid supply system that supplies a processing liquid onto the substrate held by said spin holder; and

the cup according to claim 1 , surrounding the substrate held by said spin holder.

11. The substrate processing apparatus according to claim 10 , wherein the viscosity of said processing liquid is 10 cP or less.