Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
177 words
The method of minimizing redeposition of underlying thin layer material which is removed by ion impact through a patterned resist mask, comprising the steps of: (a) determining the etching rates by ion impact of said resist mask and said underlying material in selected atmospheres; (b) interposing a thin layer of getter mask material between said resist mask and said underlying material, said getter mask material etching very slowly in a said selected atmosphere, relative to said resist mask and said underlying material; (c) selecting the relative thicknesses and etching rates of said resist mask, said underlying material, and said getter mask material to cause the portions of said getter mask material not protected by said resist mask to be removed by said ion impact shortly prior to faceting of the resist mask to the protected portions of said getter mask material in a selected first atmosphere; and (d) continuing etching by ion impact in a selected different atmosphere to remove the resist mask and reduce the thickness of the exposed getter mask material, thereby to minimize redepositing.
Claim 2
Independent Claim
177 words
The method of minimizing redeposition of underlying thin layer material which is removed by ion impact through a patterned resist mask, comprising the steps of: (a) determining the etching rates by ion impact of said resist mask and said underlying material in selected atmospheres; (b) interposing a thin layer of getter mask material between said resist mask and said underlying material, said getter mask material etching very slowly in a said selected atmosphere, relative to said resist mask and said underlying material; (c) selecting the relative thicknesses and etching rates of said resist mask, said underlying material, and said getter mask material to cause the portions of said getter mask material not protected by said resist mask to be removed by said ion impact shortly prior to faceting of the resist mask to the protected portions of said getter mask material in a selected first atmosphere; and (d) continuing etching by ion impact in a selected different atmosphere to remove the resist mask and reduce the thickness of the exposed getter mask material, thereby to minimize redepositing.
Claim 3
Dependent Claim
19 words
The method of claim 1, wherein: said material is metal; and said ion impact is caused by ion milling.
Claim 4
Dependent Claim
14 words
The method of claim 1, wherein: said ion impact is caused by sputter etching.
Claim 5
Dependent Claim
23 words
The method of claim 1, wherein: said underlying material is nickel iron; said getter mask material is titanium; and, said resist is AZ1350B.
Claim 6
Dependent Claim
32 words
The method of claim 4, wherein: the nickel iron is approximately 4000 A thick; the titanium getter mask material is approximately 800 A thick; and the AZ1350B is approximately 5000 A thick.
Claim 7
Dependent Claim
27 words
The method of claim 5, wherein: said first atmosphere is pure argon; and, the different atmosphere is 1×10 -5 Torr O 2 in 1×10 -4 Torr argon.
Claim 8
Dependent Claim
84 words
The method of claim 1, wherein: the thickness of the resist mask, X R , is determined for normal incidence ion etching by the formula: ##EQU5## where: X M =thickness of underlying material to be etched R.sub.θ.sbsb.p R =rate of erosion of the bevels of the resist mask θ p R =angle of maximum ion erosion rate for the resist material (bevel normal to ion direction) R 0 ° M =rate of erosion of the underlying material to be etched at normal (0°) incidence.