Wafer grounding and biasing method, apparatus, and application
A wafer grounding apparatus and method adaptable to a charged particle beam apparatus is disclosed. A wafer substrate is supported by a wafer mount. A pulse current pin is arranged to be in contact with a backside film formed on a backside of the wafer substrate. A grounding pulse generator provides at least one pulse to drive the pulse current pin such that dielectric breakdown occurring at the backside film leads to establishment of a current path through the backside films. Accordingly, a current flows in the wafer substrate through this current path and then flows out of the wafer substrate via at least one current return path formed from capacitive coupling between the wafer substrate and the wafer mount.
1. A wafer grounding and biasing method, comprising:
positioning a wafer substrate on a wafer mount;
arranging only one current pin at a time to be in contact with said wafer substrate;
holding said wafer substrate with the wafer mount, wherein the wafer mount comprises a chuck electrode, and a capacitive coupling is formed between said chuck electrode and said wafer substrate; and
providing a current to the wafer mount via said current pin, wherein said current flows in a return path only through said capacitive coupling.
2. The wafer grounding and biasing method of claim 1 , wherein said chuck electrode comprises a positive chuck electrode and a negative chuck electrode.
3. The wafer grounding and biasing method of claim 2 , wherein said capacitive coupling comprises a positive capacitive coupling between said positive chuck electrode and said wafer substrate, and a negative capacitive coupling between said negative chuck electrode and said wafer substrate.
4. The wafer grounding and biasing method of claim 1 , wherein said current is a bias current provided by a wafer bias supply circuit.
5. The wafer grounding and biasing method of claim 4 , wherein said bias current is a direct current (DC).
6. The wafer grounding and biasing method of claim 1 , wherein said current is provided by a grounding pulse generator circuit.
7. The wafer grounding and biasing method of claim 6 , wherein said current is a pulsed current.
8. The wafer grounding and biasing method of claim 7 , wherein said pulse current is a direct current (DC).
9. The wafer grounding and biasing method of claim 1 , further comprises: providing a switch for selecting said current either from a wafer bias supply circuit or a grounding pulse generator circuit.
10. The wafer grounding and biasing method of claim 1 , further comprises: pushing said wafer substrate away from said wafer mount with a lifting pin.
11. The wafer grounding and biasing method of claim 1 , wherein the current is provided in a state where only said current pin and said wafer mount are in contact with said wafer substrate.
12. A wafer grounding and biasing apparatus, comprising:
a wafer mount for supporting a wafer substrate, wherein the wafer mount comprises a chuck electrode, and a capacitive coupling is formed between said chuck electrode and said wafer substrate; and
only one current pin at a time arranged for contacting said wafer substrate;
wherein a current is provided to the wafer mount via said current pin, and said current flows in a return path only through said capacitive coupling.
13. The wafer grounding and biasing apparatus of claim 12 , wherein said chuck electrode comprises a positive chuck electrode and a negative chuck electrode.
14. The wafer grounding and biasing apparatus of claim 13 , wherein said capacitive coupling comprises a positive capacitive coupling between said positive chuck electrode and said wafer substrate, and a negative capacitive coupling between said negative chuck electrode and said wafer substrate.
15. The wafer grounding and biasing apparatus of claim 12 , further comprises a wafer bias supply circuit for providing said current.
16. The wafer grounding and biasing apparatus of claim 15 , wherein said current is a direct current (DC).
17. The wafer grounding and biasing apparatus of claim 12 , further comprises a grounding pulse generator circuit for providing said current.
18. The wafer grounding and biasing apparatus of claim 17 , wherein said current is a pulsed current.
19. The wafer grounding and biasing apparatus of claim 18 , wherein said pulse current is a direct current (DC).
20. The wafer grounding and biasing apparatus of claim 12 , further comprises: a switch for selecting said current either from a wafer bias supply circuit or a grounding pulse generator circuit.
21. The wafer grounding and biasing apparatus of claim 12 , further comprises: a lifting pin for pushing said wafer substrate away from said wafer mount.
22. The wafer grounding and biasing apparatus of claim 12 , wherein the current is provided in a state where only said current pin and said wafer mount are in contact with said wafer substrate.