Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d) based on an application filed in the Republic of Korea on September 19, 2022, and receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. It should be noted that in order to effectively benefit from the foreign priority date, an English translation of the certified copy (of the foreign application as filed) filed together with a statement that the translation of the certified copy is accurate must be presented.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on April 19, 2023 was filed in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Title
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed. The following title is suggested:
--Variable Resistance Element With Improved Switching Reliability Consisting Of A Metal Chalcogenide Tunnel Barrier--
Claim Objections
Claims 1, 7, and 17 are objected to because of the following informalities:
Regarding Claim 1, the preamble lacks a transitional phrase (e.g. ‘comprising’, ‘consisting of’, etc.) to define the scope of the claim as it relates to the variable resistance element. With consideration to consistency with the independent Claim 10, and presumable desired broadness of the claim set generally, it’s the Examiner’s understanding that the intent was for the preamble to include the term “comprising” but was simply forgotten as a typographical error.
For the purpose of this Office Action, the Examiner will read the preamble of Claim 1 as --A variable resistance element comprising--
Regarding Claims 7 and 17, The limitation “band gap energy(Eg)” should read --band gap energy (Eg)--, i.e. a space is missing.
Appropriate correction is required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 2, 5-9 are rejected under 35 U.S.C. 103 as being unpatentable by Chio et al. (U.S. Pat. 9,564,581), hereinafter Chio, in view of Chowdhury et al. (‘Optical and structural characterization of ZnSe thin film fabricated by thermal vapour deposition technique’ AIMS Materials Science 4.5 (2017): 1095-1121), hereinafter Chowdhury.
Regarding Claim 1, Chio teaches a variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29), comprising:
-a free layer having a variable magnetization direction ((308); Fig. 3, Col. 4, Lines 44-46);
-a pinned layer having a fixed magnetization direction ((312); Fig. 3, Col. 4, Lines 49-50); and
-a tunnel barrier layer (consisting of (310) and (314); Fig. 3, Col. 4, Lines 50-51 and 60-61) interposed between the free layer (308) and the pinned layer (312) and including a metal chalcogenide (Zinc Selenide ‘ZnSe’; Col. 4, Line 60).
Chio does not explicitly state whether the metal chacogenide Zinc Selenide used has a cubic crystal structure (zincblende) or is of a hexagonal form (wurzite).
Chowdhury teaches a method of forming Zinc Selenide thin films wherein:
-the metal chalcogenide has a cubic crystal structure (3. Results and Discussion, 3.1 Structural Characterization, 1st Paragraph).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the teachings of Chowdhury into the device of Chio such that it included a metal chalcogenide having a cubic crystal structure (cubic ZnSe). This would be due to the fact that doing so would ensure the formation of a high-quality film (e.g. maintaining stoichiometry during growth) (Chowdhury, 1. Introduction, 1st Paragraph).
Regarding Claim 2, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-the tunnel barrier layer ((310) and (314)) includes a metal chalcogenide having a cubic crystal structure (cubic ZnSe) and belonging to a space group Fm-3m or F-43m (cubic ZnSe belongs to F-43m, see for example Chowdhury 3. Results and Discussion, 3.1 Structural Characterization, 3rd and 5th Paragraphs).
Regarding Claim 5, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-the tunnel barrier layer ((310) and (314)) includes CrS, CrSe, CrTe, MnS, MnSe, MnTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, GeS, GeSe, GeTe, SnS, SnSe, or SnTe, or a combination thereof. (ZnSe)
Regarding Claim 7, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-the metal chalcogenide (cubic ZnSe) exhibits a lower band gap energy(Eg) (approximately 2.64 eV, see Chowdhury, 4. Conclusion) and a higher breakdown voltage (Vbd) (known to have a high breakdown voltage, see e.g. 20V, Lipson (U.S. Pub. 2005/0077539) Paragraph [0022]) compared to MgOx (Provided by Applicant as 5-7.6 eV and 1.1~1.2 V, respectively, Paragraph [0039] of the instant Specification).
Regarding Claim 9, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-each of the pinned layer (312) and the free layer (308) includes an alloy containing Fe and Co. (Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43)).
Claims 3 and 4 are rejected under 35 U.S.C. 103 as being unpatentable by Chio in view of Chowdhury and in further view of Kreupl (U.S. Pub. 2003/0142562), hereinafter Kreupl, as further evidenced by Hotje et al. (‘Lattice constants and molar volume in the system ZnS, ZnSe, CdS, CdSe’ Solid State Sci. 5, 1259-1262 (2003)), hereinafter Hotje.
Regarding Claim 3, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-The tunnel barrier layer consists of two sublayers ((310) and (314)) wherein the material used for the secondary sublayer (314) has a crystal lattice similar to that of the first sublayer (310) (Col. 5, Lines 2-4).
Chio nor Chowdhury teach:
- the tunnel barrier layer includes a combination of two or more metal chalcogenides. (i.e. that (314) is a metal chacogenide)
Kreupl teaches a variable resistance element ((9); Fig. 1, Paragraph [0100]) comprising a free layer ((3); Fig. 1, Paragraph [0101]), a fixed layer ((5); Fig. 1, Paragraph [0101]), and a tunnel barrier ((4); Fig. 1, Paragraph [0100]), where:
-the tunnel barrier is a metal chalcogenide ((ZnS); Paragraph [0115]) that has a crystal lattice similar to that of Chio (310).
ZnS has a cubic structure (sphalerite) in the space group F-43m with a lattice constant of approximately 5.401 Å (See, e.g. Tables 1 and 2 of Hotje) This is less than 5% lattice mismatched to ZnSe as required for the material of (310) of Choi (Choi, Col. 5, Lines 4-7).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the teachings of Kreupl into the device of Chio as modified by Chowdhury such that the secondary sublayer (Chio, (314)) is made of ZnS, so that the tunnel barrier layer includes a combination of two or more metal chalcogenides. This would be due to the fact that doing so would incorporate a viable material to Chio (314) so that the perpendicular magnetic anisotropy (PMA) is enhanced and thus thermal stability of the magnetic moments are maintained. (Chio, Col. 1, Lines39-45, Col. 4, Lines 60-61, and Col. 5, Lines 1-7).
Regarding Claim 4, Chio and Chowdhury as modified by Kreupl teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-the combination (Of ZnS of (314) and ZnSe of (310)) has a composition that is configured to adjust a band gap energy (Eg) (As required to ensure improved perpendicular magnetic anisotropy (PMA), Choi. Col. 4, Lines 60-61) and a lattice constant of the tunnel barrier layer (As required to ensure lower mismatch between barrier layer sublayers, Choi Col. 5, Lines 1-7, and generally between the interfaces with the fixed and free magnetic layers, Choi Col. 1, Lines 31-36).
Claims 6 and 8 are rejected under 35 U.S.C. 103 as being unpatentable by Chio in view of Chowdhury and as further evidenced by Hasegawa et al. (‘Stabilisation of tetragonal FeCo structure with high magnetic anisotropy by the addition of V and N elements’ Sci Rep 9, 5248 (2019)), hereinafter Hasegawa.
Regarding Claim 6, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-the tunnel barrier layer ((310) and (314)) has a lattice constant (the ZnSe of (310) has a lattice constant of about 5.68 Å, see Chowdhury Table 1) that is in a range of 1.7 to 2.3 times a lattice constant of the pinned layer (312) or the free layer (308).
Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43), which is known to have a lattice constant of approximately 2.85 Å (See, for example, Hasegawa, 2nd paragraph of section ‘Structural BCC to FCC Transformation of FeCo Due to VN addition’). 5.68 Å is approximately 2 times 2.85 Å.
Regarding Claim 8, Chio as modified by Chowdhury teaches the variable resistance element ((102E); Fig. 3, Col. 4, Lines 22-29) of Claim 1, wherein:
-each of the pinned layer (312) and the free layer (308) includes a material having a body-centered cubic (BCC) crystal structure.
Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43), which is known to be have a BCC crystal structure (See, Hasegawa Pg. 1, 2nd paragraph of the introduction)
Claims 10-12 and 16-20 are rejected under 35 U.S.C. 103 as being unpatentable by Kim (U.S. Pub. 2016/0181320), hereinafter Kim, in view of Chio and Chowdhury.
Regarding Claim 10, Kim teaches a semiconductor device (memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]), comprising:
-a variable resistance layer ((100); Fig. 1, Paragraph [0035]; and
-a selector layer ((12); Fig. 1, Paragraph [0033]) disposed over the variable resistance layer or under the variable resistance layer (In this case, under (100), as in Fig. 1).
Kim does not explicitly teach the variable resistance layer:
- including a magnetic tunnel junction (MTJ) structure that includes a free layer having a variable magnetization direction that switches between different magnetization directions upon application of a magnetic field, a pinned layer having a fixed magnetization direction and a tunnel barrier layer interposed between the free layer and the pinned layer and including a metal chalcogenide having a cubic crystal structure;
Chi teaches a magnetic tunnel junction (MTJ) structure ((102E); Fig. 3, Col. 4, Lines 22-29) that includes:
-a free layer having a variable magnetization direction ((308); Fig. 3, Col. 4, Lines 44-46);
-a pinned layer having a fixed magnetization direction ((312); Fig. 3, Col. 4, Lines 49-50); and
-a tunnel barrier layer (consisting of (310) and (314); Fig. 3, Col. 4, Lines 50-51 and 60-61) interposed between the free layer (308) and the pinned layer (312) and including a metal chalcogenide (Zinc Selenide ‘ZnSe’; Col. 4, Line 60).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the teachings of Choi into the device of Kim such that it includes a magnetic tunnel junction (MTJ) structure that includes a free layer having a variable magnetization direction that switches between different magnetization directions upon application of a magnetic field, a pinned layer having a fixed magnetization direction and a tunnel barrier layer interposed between the free layer and the pinned layer and including a metal chalcogenide having a cubic crystal structure. This would be due to the fact that doing so would allow the memory device to have greater efficiency and have enhanced perpendicular magnetic anisotropy (Choi, Col. 1, Lines 34-45 and 51-52).
Chio does not explicitly state whether the metal chacogenide Zinc Selenide used has a cubic crystal structure (zincblende) or is of a hexagonal form (wurzite).
Chowdhury teaches a method of forming Zinc Selenide thin films wherein:
-the metal chalcogenide has a cubic crystal structure (3. Results and Discussion, 3.1 Structural Characterization, 1st Paragraph).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the teachings of Chowdhury into the device of Kim as modified by Chio such that it included a metal chalcogenide having a cubic crystal structure (cubic ZnSe). This would be due to the fact that doing so would ensure the formation of a high-quality film (e.g. maintaining stoichiometry during growth) (Chowdhury, 1. Introduction, 1st Paragraph).
Regarding Claim 11, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, further comprising:
-a first electrode layer ((16); Fig. 1, Paragraph [0035]) disposed at an uppermost portion of a memory cell (Kim, (10); Fig. 1, Paragraph [0032]) including the variable resistance layer (Kim, modified (100)) and the selector layer (Kim, (12)),
-a second electrode layer (Kim, (11); Fig. 1, Paragraph [0032]) disposed at a lowermost portion of the memory cell (Kim, (10)), and
-a third electrode layer (Kim, (13); Fig 1, Paragraph [0032]) disposed between the variable resistance layer (Kim, modified (100)) and the selector layer (Kim, (12)).
Regarding Claim 12, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-the tunnel barrier layer (Choi, (310) and (314)) includes a metal chalcogenide having a cubic crystal structure (cubic ZnSe) and belonging to a space group Fm-3m or F-43m (cubic ZnSe belongs to F-43m, see for example Chowdhury 3. Results and Discussion, 3.1 Structural Characterization, 3rd and 5th Paragraphs).
Regarding Claim 17, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-the metal chalcogenide (cubic ZnSe) exhibits a lower band gap energy(Eg) (approximately 2.64 eV, see Chowdhury, 4. Conclusion) and a higher breakdown voltage (Vbd) (known to have a high breakdown voltage, see e.g. 20V, Lipson (U.S. Pub. 2005/0077539) Paragraph [0022]) compared to MgOx (Provided by Applicant as 5-7.6 eV and 1.1~1.2 V, respectively, Paragraph [0039] of the instant Specification).
Regarding Claim 19, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-each of the pinned layer (Choi, (312)) and the free layer (Choi, (308)) includes an alloy containing Fe and Co. (Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43)).
Claims 13-15 are rejected under 35 U.S.C. 103 as being unpatentable by Kim in view of Chio and Chowdhury, and in further view of Kreupl, as further evidenced by Hotje.
Regarding Claim 13, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-The tunnel barrier layer consists of two sublayers (Choi, (310) and (314)) wherein the material used for the secondary sublayer (Choi, (314)) has a crystal lattice similar to that of the first sublayer (Choi, (310)) (Choi, Col. 5, Lines 2-4).
Kim, Chio, nor Chowdhury teach:
- the tunnel barrier layer includes a combination of two or more metal chalcogenides. (i.e. that (Choi, (314)) is a metal chacogenide)
Kreupl teaches a variable resistance element ((9); Fig. 1, Paragraph [0100]) comprising a free layer ((3); Fig. 1, Paragraph [0101]), a fixed layer ((5); Fig. 1, Paragraph [0101]), and a tunnel barrier ((4); Fig. 1, Paragraph [0100]), where:
-the tunnel barrier is a metal chalcogenide ((ZnS); Paragraph [0115]) that has a crystal lattice similar to that of Chio (310).
ZnS has a cubic structure (sphalerite) in the space group F-43m with a lattice constant of approximately 5.401 Å (See, e.g. Tables 1 and 2 of Hotje) This is less than 5% lattice mismatched to ZnSe as required for the material of (310) of Choi (Choi, Col. 5, Lines 4-7).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the teachings of Kreupl into the device of Kim as modified by Chio and Chowdhury such that the secondary sublayer (Chio, (314)) is made of ZnS, so that the tunnel barrier layer includes a combination of two or more metal chalcogenides. This would be due to the fact that doing so would incorporate a viable material to Chio (314) so that the perpendicular magnetic anisotropy (PMA) is enhanced and thus thermal stability of the magnetic moments are maintained. (Chio, Col. 1, Lines39-45, Col. 4, Lines 60-61, and Col. 5, Lines 1-7).
Regarding Claim 14, Kim, Choi, and Chowdhury, as modified by Kreupl, teach a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 13, wherein:
-the combination (Of ZnS of (314) and ZnSe of (310)) has a composition that is configured to adjust a band gap energy (Eg) (As required to ensure improved perpendicular magnetic anisotropy (PMA), Choi. Col. 4, Lines 60-61) and a lattice constant of the tunnel barrier layer (As required to ensure lower mismatch between barrier layer sublayers, Choi Col. 5, Lines 1-7, and generally between the interfaces with the fixed and free magnetic layers, Choi Col. 1, Lines 31-36).
Regarding Claim 15, Kim, Choi, and Chowdhury, as modified by Kreupl, teach a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 13, wherein:
-the tunnel barrier layer ((310) and (314)) includes CrS, CrSe, CrTe, MnS, MnSe, MnTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, GeS, GeSe, GeTe, SnS, SnSe, or SnTe, or a combination thereof. (Choi, ZnSe, and Kreupl, ZnS)
Claims 16 and 18 are rejected under 35 U.S.C. 103 as being unpatentable by Kim in view of Chio and Chowdhury and as further evidenced by Hasegawa.
Regarding Claim 16, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-the tunnel barrier layer (Choi, (310) and (314)) has a lattice constant (Choi, the ZnSe of (310) has a lattice constant of about 5.68 Å, see Chowdhury Table 1) that is in a range of 1.7 to 2.3 times a lattice constant of the pinned layer (Choi, (312)) or the free layer (Choi, (308)).
Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43), which is known to have a lattice constant of approximately 2.85 Å (See Hasegawa, 2nd paragraph of section ‘Structural BCC to FCC Transformation of FeCo Due to VN addition’). 5.68 Å is approximately 2 times 2.85 Å.
Regarding Claim 18, Kim, as modified by Choi and Chowdhury, teaches a semiconductor device (Kim, memory unit (1010); Figs. 1 and 4, Paragraphs [0046] and [0047]) of Claim 10, wherein:
-each of the pinned layer (Choi, (312)) and the free layer (Choi, (308)) includes a material having a body-centered cubic (BCC) crystal structure.
Chio teaches that both (312) and (308) are FeCo (Col. 4, Lines 40-43), which is known to be have a BCC crystal structure (See, Hasegawa Pg. 1, 2nd paragraph of the introduction)
Conclusion
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/D.M./Examiner, Art Unit 2812
/DAVIENNE N MONBLEAU/Supervisory Patent Examiner, Art Unit 2812