Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
132 words
A method of selectively etching at least one opening in a given material (14) on a substrate or layer of different material (12) wherein said given material has a variable thickness at the locations to be etched and wherein a mask (16) is provided overlying said given material (14), said mask (16) defining the at least one opening (18, 20) at the locations to be etched, characterized by the steps of first isotropically etching the regions to be etched, detecting the initial end point at which a portion of said material (14) is completely etched away at some location to expose the surface of said different material (12) at said location, and thereafter anisotropically etching the remainder of said given material (14) until it has been completely removed from all etch locations.
Claim 2
Independent Claim
132 words
A method of selectively etching at least one opening in a given material (14) on a substrate or layer of different material (12) wherein said given material has a variable thickness at the locations to be etched and wherein a mask (16) is provided overlying said given material (14), said mask (16) defining the at least one opening (18, 20) at the locations to be etched, characterized by the steps of first isotropically etching the regions to be etched, detecting the initial end point at which a portion of said material (14) is completely etched away at some location to expose the surface of said different material (12) at said location, and thereafter anisotropically etching the remainder of said given material (14) until it has been completely removed from all etch locations.
Claim 3
Dependent Claim
14 words
Method according to claim 1 wherein the etching is performed in a gas atmosphere.
Claim 4
Dependent Claim
13 words
Method according to claim 2 wherein the etching is done by plasma etching.
Claim 5
Dependent Claim
100 words
Method according to claim 3 wherein the initial end point is determined by: a) selecting at least one emission band of one of the species involved in the etching reaction which changes in intensity responsive to the reaction at the initial end point; b) monitoring the intensity of said band during etching to produce a curve of said monitor result; c) utilizing the monitor intensity to provide a recognizable point on said curve where said initial end point occurs as it occurs; and d) terminating said isotropic etch process responsive to said recognizable change in intensity of said emission band.
Claim 6
Dependent Claim
31 words
Method according to claim 4 wherein the intensities of at least two emission bands are monitored and wherein said change is monitored as a function of said at least two bands.
Claim 7
Dependent Claim
41 words
Method according to claim 4 wherein said given material (14) consists of polysilicon and wherein the etching is done in an atmosphere which produces an active fluorine species, and the change in at least one fluorine band is said monitored band.
Claim 8
Dependent Claim
13 words
Method according to claim 7 wherein the band is the 703.7 nm band.
Claim 9
Dependent Claim
27 words
Method according to claim 4 wherein the utilizing of said monitored intensity includes successive monitoring of values and comparison with previously monitored values to establish that curve.
Claim 10
Dependent Claim
37 words
Method according to anyone of claims 4 to 8 wherein said recognizable point is defined by taking the second derivative of the curve of the monitored intensity with respect to time to identify the initial end point.