Photolithography methods and resulting structures
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsChun-Yi Chang, Chunyao Wang
Life of this patent
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Abstract
As deposited, hard mask thin films have internal stress components which are an artifact of the material, thickness, deposition process of the mask layer as well as of the underlying materials and topography. This internal stress can cause distortion and twisting of the mask layer when it is patterned, especially when sub-micron critical dimensions are being patterned. A stress-compensating process is employed to reduce the impact of this internal stress. Heat treatment can be employed to relax the stress, as an example. In another example, a second mask layer with an opposite internal stress component is employed to offset the internal stress component in the hard mask layer.
Claims20
A method for forming a semiconductor device, comprising:
- forming a mask layer on an underlying layer, wherein the mask layer has a first coefficient of thermal expansion (CTE), the underlying layer has a second CTE, and further wherein the first CTE and the second CTE are mismatched, the mask layer having, as deposited, an internal stress, the internal stress having a first magnitude and a first direction;
- forming over the mask layer a stress-compensating layer, the stress compensating layer having an internal stress having a second magnitude and having a second direction opposite to the first direction;
- and
- performing a thermal process on the mask layer and the stress-compensating layer, wherein after the thermal process, the internal stress of the mask layer has a third magnitude lower than the first magnitude and has the first direction.
A method for forming a semiconductor device, comprising:
- forming a material layer over a substrate;
- forming a mask layer over the material layer, the mask layer having, as deposited, an internal stress, the internal stress being either compressive or tensile, wherein the mask layer comprises a material selected from the group consisting of silicon oxide, silicon nitride, silicon-oxy-nitride, a metal nitride, and a metal oxide;
- forming over the mask layer a stress-compensating layer, the stress compensating layer having an internal stress that is opposite in direction to the internal stress of the mask layer, wherein the stress-compensating layer reduces the internal stress of the mask layer;
- and
- performing a thermal process on the mask layer to further reduce the internal stress of the mask layer, wherein the mask layer, as deposited, has a compressive internal stress and further wherein, after performing the thermal process, the mask layer remains in compressive internal stress.
A method for forming a semiconductor device, comprising:
- forming a material layer over a substrate;
- forming a first mask layer over the material layer, the first mask layer having an internal stress extending from a topmost surface of the first mask layer to a bottommost surface of the first mask layer, the internal stress being either compressive or tensile;
- if the internal stress of the first mask layer is compressive:
- forming over the first mask layer a second mask layer having an internal stress that is tensile, wherein the second mask layer having an internal stress that is tensile at least partially offsets the compressive internal stress of the first mask layer, and
- performing a thermal process on the first mask layer to further offset the compressive internal stress of the first mask layer, wherein the first mask layer retains some compressive internal stress after the thermal process, and
- if the internal stress of the second mask layer is tensile:
- forming over the first mask layer a second mask layer having a compressive internal stress, wherein the second mask layer having an internal stress that is compressive at least partially offsets the tensile internal stress of the first mask layer, and
- performing a thermal process on the first mask layer to further offset the tensile internal stress of the first mask layer, wherein the first mask layer retains some tensile internal stress after the thermal process.
Dependencies are inferred from the claim text.