Beam-induced etching
A method and apparatus for local beam processing using a beam activated gas to etch material are described. Compounds are disclosed that are suitable for beam-induced etching. The invention is particularly suitable for electron beam induced etching of chromium materials on lithography masks. In one embodiment, a polar compound, such as ClNO 2 gas, is activated by the electron beam to selectively etch a chromium material on a quartz substrate. By using an electron beam in place of an ion beam, many problems associated with ion beam mask repair, such as staining and riverbedding, are eliminated. Endpoint detection is not critical because the electron beam and gas will not etch significantly the substrate.
1. A method of repairing a photolithograph mask including excess chromium material on a quartz substrate, comprising:
directing an electron beam toward the excess chromium material on the quartz substrate;
directing a gas toward the excess chromium material, the gas including a gaseous compound including XNO, XNO 2 , or XONO 2 in which X is a halogen, the gaseous compound reacting in the presence of the electron beam to etch the excess chromium material while not significantly etching the quartz substrate.
2. The method of claim 1 in which directing an electron beam toward the excess chromium material on a substrate includes directing an electron beam toward a metallic chromium, an chromium oxygen compound, or a chromium nitrogen compound.
3. The method of claim 1 in which directing an electron beam toward the excess chromium material on a substrate includes directing an electron beam toward the chromium material on a quartz substrate, the chromium material etching at a rate at least twice as great as the rate at which the quartz substrate is etched.
4. The method of claim 1 in which the gaseous compound has a dipole moment greater than about 0.4 debye.
5. The method of claim 1 in which the molecules of the gaseous compound have an adsorption energy on the quartz substrate of greater than about 8 kcal/mol.
6. The method of claim 1 , wherein X is a chlorine atom.
7. The method of claim 1 in which directing a gaseous compound toward the excess chromium material includes directing a gaseous compound including HCl.
8. The method of claim I in which directing a gaseous compound toward the chromium material, includes directing a compound of the form F w Cl x Br y I z N t O s H r , in which w, x, y, z, t, s, and r integers, at least two of w, x, y, and z are greater than zero, and at least t and s are also greater than zero, the gaseous compound reacting in the presence of the electron beam to etch the chromium material.
9. The method of claim 1 in which directing a gaseous compound toward the excess chromium material includes directing a gaseous compound of the form ClNO x .
10. The method of claim 9 in which directing a gaseous compound toward the excess chromium material includes directing a gaseous compound having the form ClN0 2 or ClNO.
11. The method of claim 1 in which directing a gaseous compound toward the excess chromium material includes directing a compound of the form X r N s O t H u , in which X is a halogen; r, s, t, and u are integers; and r, s, t, and u are greater than zero.
12. The method of claim 11 in which X is chlorine.
13. The method of claim 11 in which X is fluorine, bromine or iodine.
14. A method of beam-induced selective etching of a material on a substrate, comprising:
directing the beam toward the material on a substrate;
directing a gaseous compound toward the chromium material to be removed, the gaseous compound including XNO, XNO 2 , or XONO 2 , in which X is a halogen, or including ClNO x , the gaseous compound reacting in the presence of the electron beam to etch the material.
15. The method of claim 14 in which X is chlorine.
16. The method of claim 14 in which the gaseous compound has a dipole moment greater than about 0.4 debye.
17. The method of claim 14 in which the material is a chromium material.
18. The method of claim 14 in which directing the beam toward the material on a substrate includes directing a focused ion beam toward the substrate.
19. The method of claim 14 in which directing the beam toward the material on a substrate includes directing a laser beam toward the substrate.
20. The method of claim 14 in which directing the beam toward the material on a substrate includes directing a focused ion beam toward a excess chromium material on a transparent photolithography substrate.
21. A method of repairing a photolithograph mask including excess chromium material on a quartz substrate, comprising:
directing an electron beam toward the excess chromium material on the quartz substrate;
directing a gas toward the excess chromium material, the gas including a gaseous compound including ClNO x , the gaseous compound reacting in the presence of the electron beam to etch the excess chromium material while not significantly etching the quartz substrate.