Method of overlay measurement
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsShih-Yu Chang, Chien-Han Chen, Chien-Chih Chiu, Chi-Che Tseng
Life of this patent
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Abstract
A method includes depositing an inter-metal dielectric (IMD) layer over a conductive line. A via opening is formed in the IMD layer and directly over the conductive line. A width of the conductive line is greater than a width of the via opening. An overlay measurement is performed. The overlay measurement includes obtaining a backscattered electron image of the via opening and the conductive line and determining an overlay between the via opening and the conductive line according to the backscattered electron image.
Claims20
A method comprising:
- depositing an etch stop layer over a conductive line, wherein the etch stop layer comprises:
- a first sub-layer over the conductive line;
- a second sub-layer over the first sub-layer;
- and
- a third sub-layer over the second sub-layer;
- depositing an inter-metal dielectric (IMD) layer over the etch stop layer;
- depositing an etching mask over the IMD layer;
- patterning the etching mask;
- after patterning the etching mask, patterning the IMD layer by using the patterned etching mask to form a via opening in the IMD layer, wherein the via opening exposes the etch stop layer;
- etching the etch stop layer to deepen the via opening, wherein the via opening in the etch stop layer does not expose both opposite sidewalls of the conductive line, and etching the etch stop layer comprises:
- etching the third sub-layer such that the via opening exposes the second sub-layer;
- etching the second sub-layer such that the via opening exposes the first sub-layer;
- and
- etching the first sub-layer such that the via opening exposes the conductive line;
- and
- after etching the third sub-layer of the etch stop layer and prior to etching the first sub-layer of the etch stop layer, performing an overlay measurement to obtain a backscattered electron image of the via opening and the conductive line.
A method comprising:
- depositing an etch stop layer over a conductive line;
- depositing an inter-metal dielectric (IMD) layer over the etch stop layer;
- form a via opening in the IMD layer, wherein the via opening exposes the etch stop layer;
- etching the etch stop layer to deepen the via opening, wherein the via opening in the etch stop layer does not expose both opposite sidewalls of the conductive line;
- performing an overlay measurement comprising:
- obtaining a backscattered electron image of the via opening and the conductive line;
- and
- determining an overlay between the via opening and the conductive line according to the backscattered electron image;
- and
- after performing the overlay measurement, etching the etch stop layer by using the IMD layer as an etch mask to expose the conductive line.
A method comprising:
- forming a conductive line over a substrate, wherein the conductive line extends in a first direction;
- depositing an etch stop layer over the substrate and covering the conductive line;
- depositing an inter-metal dielectric (IMD) layer over the etch stop layer;
- form a via opening in the IMD layer, wherein the via opening exposes the etch stop layer;
- etching the etch stop layer to deepen the via opening, wherein the via opening in the etch stop layer does not expose both opposite sidewalls of the conductive line;
- performing an overlay measurement to obtain a spatial distribution of an atomic weight of the conductive line and a spatial distribution of an atomic weight of the etch stop layer;
- and
- after performing the overlay measurement, etching the etch stop layer by using the IMD layer as an etch mask to expose the conductive line.
Dependencies are inferred from the claim text.