Abstract: A process flow for forming a magnetic tunnel junction (MTJ) cell that is self-aligned to an underlying bottom electrode (BE) is disclosed. The BE is comprised of a lower BE layer having a first width (w1), and an upper (second) BE layer with a second width (w2) where w2>w1. Preferably, the BE has a T shape. A stack of MTJ layers including an uppermost hard mask is deposited on the BE and has width w2 because of a self-aligned deposition process. A dummy MTJ stack is also formed around the first BE layer. An ion beam etch where ions are at an incident angle <90° with respect to the substrate is used to remove extraneous material on the sidewall. Thereafter, an encapsulation layer is deposited to insulate the MTJ cell, and to fill a gap between the first BE layer and dummy MTJ stack.

Abstract: A method for etching a magnetic tunneling junction (MTJ) structure is described. A bottom electrode layer is provided on a substrate. A seed layer is deposited on the bottom electrode layer. The seed layer and bottom electrode layer are patterned. A dielectric layer is deposited over the patterned seed layer and bottom electrode layer and planarized wherein the seed layer is exposed. Thereafter, a stack of MTJ layers is deposited on the patterned seed layer comprising a pinned layer, a tunnel barrier layer, and a free layer. The MTJ stack is then patterned to form a MTJ device. Because the seed layer was patterned before the MTJ patterning step, the exposure of the device to etching plasma gases is shortened and thus, etch damage is minimized.

Abstract: A KrF (248 nm) photoresist patterning process flow is disclosed wherein photoresist patterns having a sub-100 nm CD are formed on a dielectric antireflective coating (DARC) thereby lowering cost of ownership by replacing a more expensive ArF (193 nm) photoresist patterning process. A key feature is treatment of a DARC such as SiON with a photoresist developer solution that is 0.263 N tetramethylammonium hydroxide (TMAH) prior to treatment with hexamethyldisilazane (HMDS) in order to significantly improve adhesion of features with CD down to about 60 nm. After the HMDS treatment, a photoresist layer is coated on the DARC, patternwise exposed, and treated with the photoresist developer solution to form a pattern therein. Features that were previously resolved by KrF patterning processes but subsequently collapsed because of poor adhesion, now remain upright and intact during a subsequent etch process used to transfer the sub-100 nm features into a substrate.

Abstract: A KrF (248 nm) photoresist patterning process flow is disclosed wherein photoresist patterns having a sub-100 nm CD are formed on a dielectric antireflective coating (DARC) thereby lowering cost of ownership by replacing a more expensive ArF (193 nm) photoresist patterning process. A key feature is treatment of a DARC such as SiON with a photoresist developer solution that is 0.263 N tetramethylammonium hydroxide (TMAH) prior to treatment with hexamethyldisilazane (HMDS) in order to significantly improve adhesion of features with CD down to about 60 nm. After the HMDS treatment, a photoresist layer is coated on the DARC, patternwise exposed, and treated with the photoresist developer solution to form a pattern therein. Features that were previously resolved by KrF patterning processes but subsequently collapsed because of poor adhesion, now remain upright and intact during a subsequent etch process used to transfer the sub-100 nm features into a substrate.

Abstract: A hard mask stack for etching a magnetic tunneling junction (MTJ) structure is described. The hard mask stack is formed on a stack of MTJ layers on a bottom electrode and comprises an electrode layer on the MTJ stack, a buffer metal layer on the electrode layer, a metal hard mask layer on the buffer metal layer, and a dielectric layer on the metal hard mask layer wherein a dielectric mask is defined in the dielectric layer by a photoresist mask, a metal hard mask is defined in the metal hard mask layer by the dielectric mask, a buffer metal mask is defined in the buffer metal layer by the metal hard mask, an electrode mask is defined in the electrode layer by the buffer metal mask, and the MTJ structure is defined by the electrode mask wherein the electrode mask remaining acts as a top electrode.

Abstract: A hard mask stack for etching a magnetic tunneling junction (MTJ) structure is described. The hard mask stack is formed on a stack of MTJ layers on a bottom electrode and comprises an electrode layer on the MTJ stack, a buffer metal layer on the electrode layer, a metal hard mask layer on the buffer metal layer, and a dielectric layer on the metal hard mask layer wherein a dielectric mask is defined in the dielectric layer by a photoresist mask, a metal hard mask is defined in the metal hard mask layer by the dielectric mask, a buffer metal mask is defined in the buffer metal layer by the metal hard mask, an electrode mask is defined in the electrode layer by the buffer metal mask, and the MTJ structure is defined by the electrode mask wherein the electrode mask remaining acts as a top electrode.

Abstract: The structure and method of formation of an integrated CMOS level and active device level that can be a memory device level. The integration includes the formation of a “super-flat” interface between the two levels formed by the patterning of a full complement of active and dummy interconnecting vias using two separate patterning and etch processes. The active vias connect memory devices in the upper device level to connecting pads in the lower CMOS level. The dummy vias may extend up to an etch stop layer formed over the CMOS layer or may be stopped at an intermediate etch stop layer formed within the device level. The dummy vias thereby contact memory devices but do not connect them to active elements in the CMOS level.

Abstract: A multi-layered bottom electrode for an MTJ device on a silicon nitride substrate is described. It comprises a bilayer of alpha tantalum on ruthenium which in turn lies on a nickel chrome layer over a second tantalum layer.

Abstract: A thin-film deposition, such as an MTJ (magnetic tunneling junction) layer, on a wafer-scale CMOS substrate, is segmented by walls or trenches and not affected by thin-film stresses due to wafer warpage or other subsequent annealing processes. An interface layer on the CMOS substrate is patterned by either undercut trenches extending into its upper surface or by T-shaped walls that extend along its upper surface. The thin-film is deposited continuously over the patterned surface, whereupon either the trenches or walls segment the deposition and serve as stress-relief mechanisms to eliminate adverse effects of processing as stresses such as those caused by wafer warpage.

Abstract: A thin-film deposition, such as an MTJ (magnetic tunneling junction) layer, on a wafer-scale CMOS substrate, is segmented by walls or trenches and not affected by thin-film stresses due to wafer warpage or other subsequent annealing processes. An interface layer on the CMOS substrate is patterned by either undercut trenches extending into its upper surface or by T-shaped walls that extend along its upper surface. The thin-film is deposited continuously over the patterned surface, whereupon either the trenches or walls segment the deposition and serve as stress-relief mechanisms to eliminate adverse effects of processing as stresses such as those caused by wafer warpage.

Abstract: A method of forming a thin-film deposition, such as an MTJ (magnetic tunneling junction) layer, on a wafer-scale CMOS substrate so that the thin-film deposition is segmented by walls or trenches and not affected by thin-film stresses due to wafer warpage or other subsequent annealing processes. An interface layer is formed on the CMOS substrate and is patterned by either forming undercut trenches extending into its upper surface or by fabricating T-shaped walls that extend along its upper surface. The thin-film is deposited continuously over the patterned surface, whereupon either the trenches or walls segment the deposition and serve as stress-relief mechanisms to eliminate adverse effects of processing as stresses such as those caused by wafer warpage.

Abstract: A wafer has a memory area and a logic area and a topmost metal contact layer on the surface covered with dielectric and etch stop layers. In the memory area, vias are opened through the dielectric and etch stop layers to topmost metal contact layer. In the logic area, evenly distributed dummy fill patterns are opened through a portion of the dielectric and etch stop layers. These are filled with a metal layer and planarized, forming a flat wafer surface. MTJ elements in the memory area and dummy elements in the logic area are formed on the flat surface. The dummy MTJ elements and fill patterns are etched away in the logic area. Metal connections are formed to the topmost metal contact layer in the logic area and top lead connections to MTJ elements are formed in the memory area.

Abstract: A composite hard mask is disclosed that prevents build up of metal etch residue in a MRAM device during etch processes that define an MTJ shape. As a result, MTJ shape integrity is substantially improved. The hard mask has a lower non-magnetic spacer, a middle conductive layer, and an upper sacrificial dielectric layer. The non-magnetic spacer serves as an etch stop during a pattern transfer with fluorocarbon plasma through the conductive layer. A photoresist pattern is transferred through the dielectric layer with a first fluorocarbon etch. Then the photoresist is removed and a second fluorocarbon etch transfers the pattern through the conductive layer. The dielectric layer protects the top surface of the conductive layer during the second fluorocarbon etch and during a substantial portion of a third RIE step with a gas comprised of C, H, and O that transfers the pattern through the underlying MTJ layers.

Abstract: A magnetic thin film deposition is patterned and protected from oxidation during subsequent processes, such as bit line formation, by an oxidation-prevention encapsulation layer of SiN. The SiN layer is then itself protected during the processing by a metal overlayer, preferably of Ta, Al, TiN, TaN or W. A sequence of low pressure plasma etches, using Oxygen, Cl2, BCl3 and C2H4 chemistries provide selectivity of the metal overlayer to various oxide layers and to the photo-resist hard masks used in patterning and metal layer and thereby allow the formation of bit lines while maintaining the integrity of the SiN layer.

Abstract: Two methods of fabricating a MEMS scanning mirror having a tunable resonance frequency are described. The resonance frequency of the mirror is set to a particular value by mass removal from the backside of the mirror during fabrication.

Abstract: A method of forming a thin-film deposition, such as an MTJ (magnetic tunneling junction) layer, on a wafer-scale CMOS substrate so that the thin-film deposition is segmented by walls or trenches and not affected by thin-film stresses due to wafer warpage or other subsequent annealing processes. An interface layer is formed on the CMOS substrate and is patterned by either forming undercut trenches extending into its upper surface or by fabricating T-shaped walls that extend along its upper surface. The thin-film is deposited continuously over the patterned surface, whereupon either the trenches or walls segment the deposition and serve as stress-relief mechanisms to eliminate adverse effects of processing as stresses such as those caused by wafer warpage.

Abstract: A CMOS device is provided in a substrate. A magnetic tunnel junction (MTJ) is provided over the CMOS device and connected to the CMOS device by a metal ring contact wherein a dielectric or other filling material forms the center of the metal ring contact and wherein a bottom of the metal ring contact underlying said filling material is metal.

Abstract: A STT-MRAM integration scheme is disclosed wherein the connection between a MTJ and CMOS metal is simplified by forming an intermediate via contact (VAC) on a CMOS landing pad, a metal (VAM) pad that contacts and covers the VAC, and a MTJ on the VAM. A dual damascene process is performed to connect BIT line metal to CMOS landing pads through VAC/VAM/MTJ stacks in a device region, and to connect BIT line connection pads to CMOS connection pads through BIT connection vias outside the device region. The VAM pad is a single layer or composite made of Ta, TaN, or other conductors which serves as a diffusion barrier, has a highly smooth surface for MTJ formation, and provides excellent selectivity with refill dielectric materials during a chemical mechanical polish process. Each VAC is from 500 to 3000 Angstroms thick to minimize additional circuit resistance and minimize etch burden.

Abstract: Formation of a bottom electrode for an MTJ device on a silicon nitride substrate is facilitated by including a protective coating that is partly consumed during etching of the alpha tantalum portion of said bottom electrode. Adhesion to SiN is enhanced by using a TaN/NiCr bilayer as “glue”.

Abstract: A STT-MRAM integration scheme is disclosed wherein the connection between a MTJ and CMOS metal is simplified by forming an intermediate via contact (VAC) on a CMOS landing pad, a metal (VAM) pad that contacts and covers the VAC, and a MTJ on the VAM. A dual damascene process is performed to connect BIT line metal to CMOS landing pads through VAC/VAM/MTJ stacks in a device region, and to connect BIT line connection pads to CMOS connection pads through BIT connection vias outside the device region. The VAM pad is a single layer or composite made of Ta, TaN, or other conductors which serves as a diffusion barrier, has a highly smooth surface for MTJ formation, and provides excellent selectivity with refill dielectric materials during a chemical mechanical polish process. Each VAC is from 500 to 3000 Angstroms thick to minimize additional circuit resistance and minimize etch burden.