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11.发明授权公开(公告)号：US10043851B1
公开(公告)日：2018-08-07
申请号：US15668113
申请日：2017-08-03
发明人： Dongna Shen , Yu-Jen Wang
摘要： A process flow for forming magnetic tunnel junction (MTJ) nanopillars with minimal sidewall residue and damage is disclosed wherein a pattern is first formed in a hard mask or uppermost MTJ layer. Thereafter, the hard mask sidewall is etch transferred through the remaining MTJ layers with a RIE process comprising main etch and over etch portions, and a cleaning step. The RIE process features noble gas and an oxidant that is one or more of CH3OH, C2H5OH, NH3, N2O, H2O2, H2O, O2, and CO. Noble gas/oxidant flow rate ratio during over etch may be greater than during main etch to avoid chemical damage to MTJ sidewalls. The cleaning step may comprise plasma or ion beam etch with the noble gas and oxidant mixture. Highest values for magnetoresistive ratio and coercivity (Hc) are observed for noble gas/oxidant ratios from 75:25 to 90:10, especially for MTJ nanopillar sizes ≤100 nm.
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公开(公告)号：US09608200B2
公开(公告)日：2017-03-28
申请号：US14670596
申请日：2015-03-27
发明人： Dongna Shen , Yu-Jen Wang , Tom Zhong
CPC分类号： H01L43/12
摘要： 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.
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13.发明申请Method to Minimize MTJ Sidewall Damage and Bottom Electrode Redeposition Using IBE Trimming 有权使用IBE修剪最小化MTJ侧壁损伤和底部电极重新沉积的方法公开(公告)号：US20170069834A1
公开(公告)日：2017-03-09
申请号：US14848378
申请日：2015-09-09
发明人： Rao Annapragada , Yu-Jen Wang , Dongna Shen
CPC分类号： H01L41/47 , H01F41/308 , H01L27/224 , H01L41/06 , H01L41/12 , H01L43/02 , H01L43/08 , H01L43/12
摘要： An improved method for etching a magnetic tunneling junction (MTJ) structure is achieved. A stack of MTJ layers is provided on a bottom electrode. The MTJ stack is patterned to form a MTJ device wherein sidewall damage or sidewall redeposition is formed on sidewalls of the MTJ device. A dielectric layer is deposited on the MTJ device and the bottom electrode. The dielectric layer is etched away using ion beam etching at an angle relative to vertical of greater than 50 degrees wherein the dielectric layer on the sidewalls is etched away and wherein sidewall damage or sidewall redeposition is also removed and wherein some of the dielectric layer remains on horizontal surfaces of the bottom electrode.
摘要翻译： 实现了一种用于蚀刻磁隧道结（MTJ）结构的改进方法。 在底部电极上设置一堆MTJ层。 图案化MTJ堆叠以形成MTJ装置，其中侧壁损伤或侧壁再沉积形成在MTJ装置的侧壁上。 电介质层沉积在MTJ器件和底部电极上。 使用离子束蚀刻以相对于大于50度的垂直方向的角度蚀刻电介质层，其中侧壁上的电介质层被蚀刻掉，并且其中侧壁损伤或侧壁再沉积也被去除，并且其中一些电介质层保持在 底部电极的水平表面。
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公开(公告)号：US20210104663A1
公开(公告)日：2021-04-08
申请号：US16592210
申请日：2019-10-03
发明人： Jesmin Haq , Tom Zhong , Luc Thomas , Zhongjian Teng , Dongna Shen
摘要： A three terminal spin-orbit-torque (SOT) device is disclosed wherein a free layer (FL) with a switchable magnetization is formed on a Spin Hall Effect (SHE) layer comprising a Spin Hall Angle (SHA) material. The SHE layer has a first side contacting a first bottom electrode (BE) and an opposite side contacting a second BE where the first and second BE are separated by a dielectric spacer. A first current is applied between the two BE, and the SHE layer generates SOT on the FL thereby switching the FL magnetization to an opposite perpendicular-to-plane direction. The SHE layer is a positive or negative SHA material, and may be a topological insulator such as Bi2Sb3. A top electrode is formed on an uppermost hard mask in each SOT device. A single etch through the FL and SHE layer ensures a reliable first current pathway that is separate from a read current pathway.
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公开(公告)号：US10153427B1
公开(公告)日：2018-12-11
申请号：US15856129
申请日：2017-12-28
发明人： Dongna Shen , Yu-Jen Wang
IPC分类号： H01L21/00 , H01L43/12 , H01L21/02 , H01L21/3065 , H01L21/311 , H01L21/3213 , H01L43/08
摘要： A process flow for forming magnetic tunnel junctions (MTJs) with minimal sidewall residue and reduced low tail population is disclosed wherein a pattern is first formed in a hard mask that is an uppermost MTJ layer. Thereafter, the hard mask pattern is etch transferred through the underlying MTJ layers including a reference layer/tunnel barrier/free layer stack. The etch transfer may be completed in a single RIE step based on a first flow rate of O2 and a second flow rate of an oxidant such as CH3OH where the CH3OH/O2 ratio is at least 7.5:1. The RIE may also include a flow rate of a noble gas. In other embodiments, a chemical treatment with an oxidant such as CH3OH, and a volatilization at 50° C. to 450° C. may follow an etch transfer through the MTJ stack when the ion beam etch or plasma etch involves noble gas ions.
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公开(公告)号：US20180294405A1
公开(公告)日：2018-10-11
申请号：US15479514
申请日：2017-04-05
发明人： Yu-Jen Wang , Dongna Shen , Vignesh Sundar , Sahil Patel
CPC分类号： H01L43/12
摘要： A method for etching a magnetic tunneling junction (MTJ) structure is described. A stack of MTJ layers is provided on a bottom electrode. A top electrode is provided on the MTJ stack. The top electrode is patterned. Thereafter, the MTJ stack not covered by the patterned top electrode is oxidized or nitridized. Then, the MTJ stack is patterned to form a MTJ device wherein any sidewall re-deposition formed on sidewalls of the MTJ device is non-conductive and wherein some of the dielectric layer remains on horizontal surfaces of the bottom electrode.
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公开(公告)号：US09972777B1
公开(公告)日：2018-05-15
申请号：US15479497
申请日：2017-04-05
发明人： Jesmin Haq , Tom Zhong , Zhongjian Teng , Dongna Shen
摘要： 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.
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公开(公告)号：US09935261B1
公开(公告)日：2018-04-03
申请号：US15479522
申请日：2017-04-05
发明人： Sahil Patel , Ru-Ying Tong , Dongna Shen , Yu-Jen Wang , Vignesh Sundar
CPC分类号： H01L43/08 , H01L27/222 , H01L43/02 , H01L43/12
摘要： A magnetic device for magnetic random access memory (MRAM), spin torque MRAM, or spin torque oscillator technology is disclosed wherein a perpendicularly magnetized magnetic tunnel junction (p-MTJ) with a sidewall is formed between a bottom electrode and a top electrode. A first dielectric layer is 3 to 400 Angstroms thick, and formed on the p-MTJ sidewall with a physical vapor deposition RF sputtering process to establish a thermally stable interface with the p-MTJ up to temperatures around 400° C. during CMOS fabrication. The first dielectric layer may comprise one or more of B, Ge, and alloys thereof, and an oxide, nitride, carbide, oxynitride, or carbonitride. The second dielectric layer is up to 2000 Angstroms thick and may be one or more of SiOYNZ, AlOYNZ, TiOYNZ, SiCYNZ, or MgO where y+z>0.
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公开(公告)号：US09887350B2
公开(公告)日：2018-02-06
申请号：US14726545
申请日：2015-05-31
发明人： Dongna Shen , Yu-Jen Wang , Jesmin Haq
CPC分类号： H01L43/12
摘要： A hard mask stack for etching a magnetic tunneling junction (MTJ) structure is described. An electrode layer is deposited on a stack of MTJ layers on a bottom electrode. A photoresist mask is formed on the electrode layer. The electrode layer is etched away where it is not covered by the photoresist mask to form a metal hard mask. The metal hard mask is passivated during or after etching to form a smooth hard mask profile. Thereafter, the photoresist mask is removed and the MTJ structure is etched using the metal hard mask wherein the metal hard mask remaining acts as a top electrode. The resulting MTJ device has smooth sidewalls and uniform device shape.
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公开(公告)号：US20160284985A1
公开(公告)日：2016-09-29
申请号：US14670596
申请日：2015-03-27
发明人： Dongna Shen , Yu-Jen Wang , Tom Zhong
IPC分类号： H01L43/12
CPC分类号： H01L43/12
摘要： 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.
摘要翻译： 描述了用于蚀刻磁隧道结（MTJ）结构的硬掩模叠层。 硬掩模叠层形成在底部电极上的一层MTJ层上，并且包括在MTJ堆叠上的电极层，电极层上的缓冲金属层，缓冲金属层上的金属硬掩模层和介电层 在金属硬掩模层上，其中通过光致抗蚀剂掩模在电介质层中限定介电掩模，金属硬掩模通过介电掩模限定在金属硬掩模层中，缓冲金属掩模由缓冲金属层限定在缓冲金属层中 通过缓冲金属掩模在电极层中限定金属硬掩模，电极掩模，MTJ结构由电极掩模限定，其中剩余的电极掩模用作顶部电极。
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