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US 11,963,457 B2Granted
MTJ device performance by controlling device shape
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsJesmin Haq, Tom Zhong, Zhongjian Teng, Vinh Lam, Yi Yang
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Abstract
A layered thin film device, such as a MTJ (Magnetic Tunnel Junction) device can be customized in shape by sequentially forming its successive layers over a symmetrically curved electrode. By initially shaping the electrode to have a concave or convex surface, the sequentially formed layers conform to that shape and acquire it and are subject to stresses that cause various crystal defects to migrate away from the axis of symmetry, leaving the region immediately surrounding the axis of symmetry relatively defect free. The resulting stack can then be patterned to leave only the region that is relatively defect free.
Claims20
A method comprising:
- forming an electrode layer having a convex top surface on a substrate, wherein the convex top surface extends from a first interface with the substrate to an opposing second interface with the substrate when viewed in cross-section after the forming of the electrode layer having the convex top surface on the substrate;
- forming a stack of magnetic tunneling junction (MTJ) layers on the electrode layer, wherein the stack of MTJ layers includes a first layer and a second layer, wherein the first layer and the second layer in the stack of MTJ layers acquire a respective curved top surface from the forming of the stack of MTJ layers, wherein defects associated with forming the first layer and the second layer in the stack of MTJ layers migrate to outer portions of the first layer and the second layer during the forming of the stack of MTJ layers, wherein the curved top surface of the first layer in the stack of MTJ layers spans a first distance over the substrate and the curved top surface of the second layer in the stack of MTJ layers spans a second distance after the forming of the stack of MTJ layers, wherein the first and second distances are measured along a first direction that is substantially parallel to a top surface of the substrate, wherein the first distance is different than the second distance and wherein the outer portion of the second layer has a flat top surface that is substantially parallel to the top surface of the substrate after the forming of the stack of the MTJ layers;
- and
- removing the outer portions of the first and second layers that contain defects and a portion of the convex top surface of the electrode layer to thereby expose a portion of the substrate, wherein the convex top surface of the electrode layer no longer interfaces with the substrate at the first and second interfaces after the removing of the portion of the convex top surface of the electrode layer.
1 more element
A method comprising:
- forming an electrode layer having a convex top surface on a substrate, wherein the convex top surface extends from a first interface with the substrate to an opposing second interface with the substrate when viewed in cross-section after the forming of the electrode layer having the convex top surface on the substrate;
- forming a first layer of a stack of MTJ layers on the convex top surface of the electrode layer thereby inducing strain in the first layer of the stack of MTJ layers to cause defects in the first layer to migrate from a second portion of the first layer to a first portion of the first layer, wherein the first portion of the first layer has a first top surface that is substantially parallel to the top surface of the substrate;
- and
- removing the first portion of the first layer and a portion of the convex top surface of the electrode layer after the forming of the first layer of the stack of MTJ layers on the convex top surface, wherein the convex top surface of the electrode layer no longer interfaces with the substrate at the first and second interfaces after the removing of the portion of the convex top surface of the electrode layer.
1 more element
A method comprising:
- forming a conductive layer on a top surface of a substrate;
- modifying the conductive layer to have a concave top surface;
- forming a stack of magnetic tunneling junction (MTJ) layers on the concave top surface of the conductive layer, wherein the stack of MTJ layers includes a first layer and a second layer disposed over the first layer, wherein the first layer and the second layer in the stack of MTJ layers have respective concave top surfaces, wherein defects associated with forming the first layer migrate to a first portion of the first layer during the forming of the stack of MTJ layers, wherein the concave top surface of the first layer in the stack of MTJ layers spans a first distance over the substrate and the concave top surface of the second layer in the stack of MTJ layers spans a second distance after the forming of the stack of MTJ layers, wherein the first and second distances are measured along a first direction that is substantially parallel to the top surface of the substrate, wherein the first distance is different than the second distance, wherein the first portion of the first layer has a flat top surface that is substantially parallel to the top surface of the substrate after the forming of the stack of the MTJ layers, wherein the first portion of the first layer physically contacts the top surface of the substrate after the forming of the stack of MTJ layers;
- and
- removing the first portion of the first layer that contains defects and a portion of the concave top surface of the conductive layer to thereby expose the top surface of the substrate.
2 more elements
Dependencies are inferred from the claim text.