DETAILED ACTION
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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 4/2/2026 has been entered.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim(s) 1-6 and 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Song et al. (US 2019/0140021 A1).
Regarding claim 1, Song discloses a memory device (Fig. 16A), comprising:
a substrate (102);
a bottom electrode (120) disposed over the substrate;
a top electrode (140) disposed over the bottom electrode; and
a phase change layer (130) disposed between the top electrode and bottom electrode, wherein the phase change layer comprises a GeSbTe material that contains a Ge content of about 1-20 at%, an Sb content of about 30-55 at%, and a Te content which is close to the claimed range of 40-55 at% (“Ge1Sb4Te7”, ¶ 0058; the Examiner notes that 58.3% is considered to be close to the range of “40-55 at%”). As the percentage of tellurium disclosed by Song is close to the claimed range of 40-55 at%, a prima facie case of obviousness exists (MPEP 2144.05(I)).
Regarding claim 2, Song discloses that the phase change layer comprises the multilayer structure (¶ 0058).
Regarding claim 8, Song further discloses a barrier electrode (170, ¶ 0028) disposed on the phase change layer; and
a selector layer (150, ¶ 0042) disposed between the barrier electrode and the top electrode
Regarding claim 3, Song does not explicitly set forth an example as claimed.
However, Song discloses that the phase change layer may be a superlattice comprising a repetition of different GST compositions (¶ 0058). Selecting a repeating structure comprising alternating layers of GST124 and GST147 (two of the compounds explicitly listed by Song) would therefore have been obvious to one having ordinary skill in the art to use a superlattice structure with alternating layers of equal thickness of GST124 and GST147 as it amounts to choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success (see MPEP 2143).
In the resulting configuration, germanium content of the phase change layer will vary from about 5 to about 15 at% between the layers of GST124 and GST147 in a thickness direction extending between the bottom electrode and the top electrode.
Regarding claim 4, Song does not explicitly set forth an example as claimed.
However, Song discloses that the phase change layer may be a superlattice comprising a repetition of different GST compositions (¶ 0058). Selecting a repeating structure comprising alternating layers of GST124 and GST147 (two of the compounds explicitly listed by Song) would therefore have been obvious to one having ordinary skill in the art to use a superlattice structure with alternating layers of equal thickness of GST124 and GST147 as it amounts to choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success (see MPEP 2143).
In the resulting configuration, the phase change layer comprises first sublayers (i.e., the topmost layer and every third layer from the topmost layer which alternates composition between GST124 and GST147) and second sublayers (the layers directly beneath the first sublayers) alternatively stacked, the topmost layer is a first sublayer in contact with the top electrode layer, and Ge contents of the first sublayers of the phase change layer are discontinuously changed in a thickness direction.
Regarding claim 5, Song does not explicitly set forth an example as claimed.
However, Song discloses that the phase change layer may be a superlattice comprising a repetition of different GST compositions (¶ 0058). Selecting a repeating structure comprising alternating layers of GST124 and GST147 (two of the compounds explicitly listed by Song) would therefore have been obvious to one having ordinary skill in the art to use a superlattice structure with alternating layers of equal thickness of GST124 and GST147 as it amounts to choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success (see MPEP 2143).
In the resulting configuration, the germanium content of the phase change layer is discontinuously changed in a thickness direction extending between the bottom electrode and the top electrode (it changes as it alternates between GST124 and GST147).
Regarding claim 6, Song does not explicitly set forth an example as claimed.
However, Song discloses that the phase change layer may be a superlattice comprising a repetition of different GST compositions (¶ 0058). Selecting a repeating structure comprising alternating layers of GST124 and GST147 (two of the compounds explicitly listed by Song) would therefore have been obvious to one having ordinary skill in the art to use a superlattice structure with alternating layers of equal thickness of GST124 and GST147 as it amounts to choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success (see MPEP 2143).
In the resulting configuration, the phase change layer comprises second sublayers (i.e., the topmost layer and every third layer from the topmost layer which alternates composition between GST124 and GST147) and first sublayers (the layers directly beneath the second sublayers) alternatively stacked, the topmost layer is a second sublayer in contact with the top electrode layer, and Ge contents of the first sublayers of the phase change layer are discontinuously changed in a thickness direction.
Claim(s) 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Song et al. (US 2019/0140021 A1) as applied to claim 1, above, and further in view of Takeuchi et al. (US 2022/0407001 A1) and Cheng (US 2023/0099931 A1).
Regarding claim 7, Song discloses using alternating layers of GST and chalcogenide materials comprising two elements such as antimony and tellurium (¶ 0058). Song differs from the claimed invention by the substitution of GST467 and Sb2Te3 with other GST and chalcogenide compositions. However, GST 467 and Sb2Te3 and their corresponding functions were known in the art (¶ 0018 of Takeuchi and ¶ 0018 of Cheng). As such, it would have been obvious to one having ordinary skill in the art before the Application's effective filing date to have substituted the known compounds of GST467 and Sb2Te3 as taught by Takeuchi and Cheng for the superlattice layer compositions of Song in equal thickness and the results of the substitution would have been predictable. (see MPEP § 2143(I)(B)).
In the resulting configuration, the phase change layer comprises Ge4Sb6Te7 and Sb2Te3 in a ratio of 10:1 to 1:10.
Claim(s) 9-16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Song et al. (US 2019/0140021 A1) in view of Takeuchi et al. (US 2022/0407001 A1) and Cheng (US 2023/0099931 A1).
Regarding claim 9, Song discloses a memory device (Fig. 16A), comprising:
a lower interconnect structure (110) over a substrate (102);
a bottom electrode (120) disposed over the lower interconnect structure;
a top electrode (140) disposed over the bottom electrode;
a phase change layer (130) disposed between the top electrode and bottom electrode, wherein the phase change layer comprises a GeSbTe material and a SbTe based material (¶ 0058); and
an upper interconnect structure (170) over the top electrode,
wherein a sidewall of the phase change layer (top sidewall) and a sidewall of the top electrode (bottom sidewall) are coterminous (see Fig. 16A).
Song discloses using alternating layers of GST and chalcogenide materials comprising two elements such as antimony and tellurium (¶ 0058). Song differs from the claimed invention by the substitution of GST467 and Sb2Te3 with other GST and chalcogenide compositions. However, GST 467 and Sb2Te3 and their corresponding functions were known in the art (¶ 0018 of Takeuchi and ¶ 0018 of Cheng). As such, it would have been obvious to one having ordinary skill in the art before the Application's effective filing date to have substituted the known compounds of GST467 and Sb2Te3 as taught by Takeuchi and Cheng for the superlattice layer compositions of Song in equal thickness and the results of the substitution would have been predictable. (see MPEP § 2143(I)(B)).
In the resulting configuration, the phase change layer comprises Ge4Sb6Te7 and Sb2Te3 in a ratio of 5:1 to 1:5 and when in that ratio the phase change layer contains a Ge content of about 1-20 at%, an Sb content of about 30-55 at%, and a Te content of about 40-55 at%.
Regarding claim 10, in the resulting configuration, the Ge content of the phase change layer is discontinuously changed in a thickness direction extending between the bottom electrode and the top electrode (discontinuously changed between the sublayers).
Regarding claim 11, in the resulting configuration, the phase change layer first sublayers (i.e., the topmost layer and every third layer from the topmost layer which alternates composition between GST124 and GST147) and second sublayers (the layers directly beneath the first sublayers) alternately stacked, and Ge contents of the first sublayers of the phase change layer are discontinuously changed towards the thickness direction.
Regarding claim 12, in the resulting configuration, the phase change layer comprises first sublayers (the GST467 layers) and second sublayers (the Sb2Te3 layers) alternately stacked.
Regarding claim 13, the first sublayers and the second sublayers comprise different materials (see rejection of claim 12, above).
Regarding claim 14, each of the first sublayers and the second sublayers comprise GST467, Sb2Te3, or a combination of both (see rejection of claim 9, above).
Regarding claim 15, in the resulting configuration, the phase change layer comprises a multilayer structure (see rejection of claim 9, above).
Regarding claim 16, Song further discloses doping the phase change layer with a dopant including nitrogen (¶ 0058).
Response to Arguments
Applicant has amended claim 1 to narrow the claimed range of tellurium to exclude the example taught by Song. As such, the 35 USC 102 rejection of claim 1 is withdrawn. However, as the disclosed tellurium content of Song is close to the claimed range, a prima facie case of obviousness exists, as discussed in the rejection above.
Applicant argues that “the claimed phase change layer can provide higher crystallization temperature and lower reset current, so as to improve the performance of the device, which is an unexpected effect over Song.” This argument is not persuasive as the evidence of record indicates that the composition of Song also has the alleged higher crystallization temperature and lower reset current (Applicant’s disclosure included the tellurium content percentage of Song, see ¶ 0045 of Applicant’s Specification).
Regarding claim 9, Applicant further argues that the resistive memory layer and top electrode layer of Song are “laterally offset” and, therefore, do not have sidewalls that are coterminous. This argument is not persuasive as claim 9 did not require the lateral sidewalls to be coterminous, only that sidewalls of the respective layers are coterminous. As a top sidewall of the resistive memory layer and a bottom sidewall of the top electrode are coterminous, the claimed limitation is satisfied.
Conclusion
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/CHRISTOPHER A CULBERT/Examiner, Art Unit 2815
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