Method of etching conductive lines without undercutting
AssigneeAdvanced Micro Devices, Inc.
InventorLewis Shen
Life of this patent
Estimating the term…
Abstract
Undercutting of conductive lines in a dense array bordered by an open field is avoided by reducing the severity of etching when the conductive material in the open field is substantially removed. In a preferred embodiment, the flow rate of chlorine gas is reduced during high density chlorine plasma etching of a conductive pattern when the conductive material is substantially removed from the open field.
Claims27
A method of manufacturing a semiconductor device having a dense array of conductive lines, comprising:
- forming an insulating layer;
- forming a layer of conductive material on the insulating layer;
- forming a mask on the conductive layer, which mask contains a pattern comprising a dense array of conductive lines bordered by an open field;
- etching the conductive layer, in a first etching step, through the mask with a high density plasma of chlorine generated at a first chlorine gas flow rate until the conductive material is substantially completely removed between the conductive lines in the open field but conductive material remains in the dense array between the conductive lines;
- reducing the first chlorine gas flow rate to a second chlorine gas flow rate when the conductive material is substantially removed from the open field but conductive material remains in the dense array between the conductive lines;
- etching, in a second etching step, at the reduced second chlorine gas flow rate to until the conductive material between the conductive lines in the dense array is substantially completely removed;
- and
- etching, in a third etching step, to completely remove any resulting residue between the conductive lines of the dense array, and to remove a portion of the underlying insulating layer from the dense array and open field.
In a method of manufacturing a semiconductor device comprising etching a layer of conductive material on an insulating layer to form a dense array of conductive lines bordered by an open field, wherein etching is conducted with a high density plasma of chlorine generated at a first chlorine gas flow rate, the improvement comprising:
- reducing the chlorine gas flow rate to a second chlorine gas flow rate when the conductive material is substantially completely removed between the conductive lines in the open field but conductive material remains in the dense array between the conductive lines;
- etching, in a second etching step, at the reduced second chlorine gas flow rate until the conductive material between the conductive lines of the dense array is substantially completely removed;
- and
- etching, in a third etching step, to completely remove any resulting residue between the conductive lines of the dense array, and to remove a portion of the underlying insulating layer in the dense array and open field, thereby substantially avoiding undercutting the conductive lines in the dense array which would occur at the unreduced chlorine gas flow rate.
In a method of manufacturing a semiconductor device comprising etching under a first set of conditions to achieve an initial etching severity, a layer of conductive material on an insulating layer to form a dense array of the conductive lines bordered by an open field, the improvement comprising:
- changing one or more of the first etching conditions to reduce the initial etching severity to a second reduced etching severity when the conductive material is substantially completely removed between the conductive lines in the open field but conductive material remains in the dense array between the conductive lines;
- etching, in a second etching step, at the second reduced severity until the conductive material between the conductive lines in the dense array is completely removed;
- and
- etching, in a third etching step, to completely remove any resulting residue between the conductive lines of the dense array, and to remove a portion of the underlying insulating layer in the dense array and open field,
- thereby substantially avoiding undercutting the conductive lines in the dense array which would occur at the initial etching severity.
Dependencies are inferred from the claim text.