Etching method and apparatus
An etching apparatus comprises a workpiece holder ( 21 ) for holding a workpiece (X), a plasma generator ( 10, 20 ) for generating a plasma ( 30 ) in a vacuum chamber ( 3 ), an orifice electrode ( 4 ) disposed between the workpiece holder ( 21 ) and the plasma generator ( 10, 20 ), and a grid electrode ( 5 ) disposed upstream of the orifice electrode ( 4 ) in the vacuum chamber ( 3 ). The orifice electrode ( 4 ) has orifices ( 4 a ) defined therein. The etching apparatus further comprises a voltage applying unit ( 25, 26 ) for applying a voltage between the orifice electrode ( 4 ) and the grid electrode ( 5 ) to accelerate ions from the plasma ( 30 ) generated by the plasma generator ( 10, 20 ) and to pass the extracted ions through the orifices ( 4 a ) in the orifice electrode ( 4 ), for generating a collimated neutral particle beam having an energy ranging from 10 eV to 50 eV.
1. An etching method comprising:
generating a collimated neutral particle beam having an energy ranging from 10 eV to 50 eV from a gas through an orifice plate made of an electrically conductive material, said orifice plate having orifices defined therein; and
applying said neutral particle beam to a surface of a workpiece comprising Si and SiO 2 ,which is masked by a resist having a pattern smaller than 0.1 μm, to etch the surface of the workpiece;
wherein said generating comprises neutralizing negative ions by passing said negative ions through said orifices to generate said neutral particle beam said orifices having sidewall surfaces so that said negative ions passing through said orifices are collided with said sidewall surfaces of said orifices and hence neutralized.
2. An etching method according to claim 1 , wherein said neutral particle beam includes fluorine atoms or chlorine atoms.
3. An etching method according to claim 1 , wherein said gas does not include an additive gas for forming a sidewall passivation layer.
4. An etching method according to claim 1 , wherein a distance between said orifice plate and said workpiece is set to be in the range from 2 mm to 50 mm.
5. An etching method according to claim 1 , further comprising:
separating a beam generating chamber for generating said neutral particle beam from a process chamber in which said workpiece is disposed; and
setting the pressure of said process chamber to be lower than the pressure of said beam generating chamber.
6. An etching method according to claim 5 , wherein the pressure of said process chamber is set to be not more than 0.1 Pa.
7. An etching apparatus comprising:
a workpiece holder for holding a workpiece comprising Si and SiO 2 , which is masked by a resist having a pattern smaller than 0.1 μm;
a plasma generator for generating a plasma in a vacuum chamber;
a first electrode disposed between said workpiece holder and said plasma generator, said first electrode having orifices defined therein;
a second electrode disposed upstream of said first electrode in said vacuum chamber; and
a voltage applying unit for applying a voltage between said first electrode and said second electrode to accelerate ions from the plasma generated by said plasma generator and to pass the extracted ions through said orifices in said first electrode,
wherein said voltage applying unit is adapted to generate a collimated neutral particle beam having an energy ranging from 10 eV to 50 eV; and
wherein said first electrode serves to neutralize negative ions by passing said negative ions through said orifices to generate said neutral particle beam, said orifices having sidewall surfaces so that said negative ions passing through said orifices are collided with said sidewall surfaces of said orifices and hence neutralized.
8. An etching apparatus according to claim 7 , wherein a distance between said first electrode and said workpiece is set to be in the range from 2 mm to 50 mm.
9. An etching apparatus according to claim 7 , wherein the pressure of said process chamber is set to be not more than 0.1 Pa.
10. An etching apparatus according to claim 7 , wherein said first electrode is made of an electrically conductive material.
11. An etching apparatus according to claim 10 , wherein a distance between said first electrode and said workpiece is set to be in the range from 2 mm to 50 mm.
12. An etching apparatus according to claim 10 , wherein the pressure of said process chamber is set to be not more than 0.1 Pa.
13. An etching method according to claim 1 , wherein said negative ions are generated by use of a pulse-time-modulated plasma.
14. An etching method according to claim 5 , wherein said negative ions are generated by use of a pulse-time-modulated plasma.
15. An etching method according to claim 1 , wherein said orifice plate is thick enough for each of said orifices to have an aspect ratio (L/d), which is a ratio of length (L) to diameter (d) being 10.
16. An etching apparatus according to claim 7 , wherein said orifice plate is thick enough for each of said orifices to have an aspect ratio (Lid), which is a ratio of length (L) to diameter (d) being 10.