Micron announced on March 25, 2020 that its first-generation 128-layer replacement-gate (RG) 3D NAND was entering volume production in fiscal Q3 2020, with revenue shipments expected in fiscal Q4. The announcement described a manufacturing transition—not an immediate switch of every Micron SSD to a faster, cheaper flash technology.
What Micron actually announced
Micron’s fiscal Q2 2020 results release on March 25, 2020 set the date behind the headline. In its prepared remarks, the company said first-generation 128-layer RG NAND would enter volume production during the current quarter, Micron’s FQ3 2020, and that revenue shipments would follow in FQ4 2020. The original remarks are available from Micron; the results release is dated March 25, 2020.
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“This quarter” was therefore a historical fiscal-quarter reference, not a claim about the current quarter in 2026. AnandTech’s contemporary report appeared on April 1, 2020: Micron to Start Volume Production of 128-Layer 3D NAND With RG Architecture This Quarter.
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The production and shipment sequence
| Stage | What it meant in this announcement |
|---|---|
| Technology development or sampling | Earlier engineering and qualification work, not the milestone Micron announced. |
| Volume production | The 128-layer first-generation RG process entered high-volume manufacturing in FQ3 2020. |
| Customer qualification | Parts still had to be validated by customers and product teams; production did not make every product immediately available. |
| Revenue shipments | Micron expected commercial revenue shipments in FQ4 2020. |
| Broad deployment | A gradual ramp across products and customers, with RG output expected to become a meaningful share of NAND production by the end of calendar 2020. |
Micron later confirmed the sequence. Its FQ3 prepared remarks recorded volume production and initial customer shipments, while its FQ4 remarks confirmed that RG-based consumer SSD shipments had begun: FQ3 FY2020 remarks and FQ4 FY2020 remarks.
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What “128-layer 3D NAND” means
Vertical memory, not a speed rating
3D NAND stacks memory cells vertically instead of placing them only across a flat planar surface. “128-layer” referred to a generation with up to 128 active memory layers. More layers can increase bits per wafer and reduce the die area needed for a given capacity, but the number alone does not specify an SSD’s speed, endurance, power use, or price.
Those product results also depend on whether the flash is TLC or QLC, the controller, channel count, NAND interface, firmware, DRAM or host-memory-buffer design, thermal limits, and the workload. A 128-layer die in one SSD can therefore behave very differently from a 128-layer die in another.
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Why layer counts are not perfectly comparable
Manufacturers did not always count layers in exactly the same way. String-stacking methods, peripheral circuitry, cell design, and definitions of an “active” layer varied among Samsung, SK hynix, Intel, Kioxia, Western Digital, Micron, and YMTC. The 128 figure is useful for identifying Micron’s process generation, but it is not a universal performance leaderboard.
What RG, or replacement gate, means
RG stands for replacement gate. In this approach, gate structures are formed or replaced through a different manufacturing sequence than in Micron’s earlier floating-gate NAND. The process change affects how the vertical cell array is built and scaled; it is not a software feature or an SSD interface standard.
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Micron had developed earlier NAND with Intel around a floating-gate approach. After the companies separated their NAND-development work, Micron moved toward replacement-gate/charge-trap designs. AnandTech’s retrospective describes the 128-layer generation as Micron’s first flash technology designed solely by Micron after that separation: AnandTech’s 2020 SSD and NAND retrospective. That attribution is industry reporting rather than a claim that appears verbatim in the earnings remarks.
Why the transition mattered strategically
A new manufacturing platform
The important milestone was the change in architecture as much as the 128-layer count. Replacement-gate manufacturing was intended to give Micron a platform for smaller dies, greater density, lower long-run cost per bit, and continued layer scaling. It also gave the company experience with a post-Intel NAND process before later RG generations were deployed more broadly.
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Not an instant cost or price cut
Micron did not expect the 2020 transition alone to create a meaningful company-wide cost-per-bit reduction during that year, according to contemporary reporting by AnandTech. New-node output initially coexisted with older generations, and ramping a process carries engineering, yield, qualification, and capacity costs. A manufacturing objective of lower cost per bit should therefore not be read as an immediate reduction in retail SSD prices.
A measured ramp rather than a wholesale conversion
Micron did not plan to move all NAND products to fourth-generation RG immediately. Volume production meant that the process was being manufactured at scale; it did not mean every wafer, capacity, customer, or SSD model had switched. Older NAND remained part of the product mix while the new process ramped.
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Which products used the NAND?
At announcement time, Micron had not identified the first products that would use the 128-layer RG technology. The later FQ4 remarks establish that RG-based consumer SSDs began shipping, but they do not show that every consumer SSD—or every capacity in a product family—used the same die.
It is therefore not safe to assign this NAND to a particular retail model without a product specification or teardown tied to that model, capacity, firmware, sample date, and production source. SSD brands can change NAND suppliers or generations while retaining the same model name.
How it fit the 2020 NAND market
In 2020, several manufacturers were moving toward three-digit-layer 3D NAND. The competitive question was not simply who could print the largest number: yield, die size, bit density, controller integration, reliability, and the ability to ramp usable output mattered just as much.
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What happened next
- March 25, 2020: Micron announced the planned FQ3 volume-production ramp with FQ4 revenue shipments.
- FQ3 2020: Micron later confirmed that first-generation 128-layer RG NAND entered volume production and that initial customer shipments began.
- FQ4 2020: RG-based consumer SSD shipments began, confirming commercial deployment without implying universal adoption across the portfolio.
- Fiscal 2021: Micron expected a second-generation RG node to enter volume production and support broader deployment.
What the announcement meant for SSD buyers
- A 128-layer label identifies a NAND generation, not a guaranteed sequential speed or random-I/O result.
- Drive performance depends on the complete SSD implementation, including controller, firmware, flash type, cache design, thermals, and workload.
- Production, customer qualification, and retail availability are separate milestones.
- The announcement did not establish that all Micron SSDs used RG NAND or that a named retail drive contained this exact 128-layer generation.
- Immediate, company-wide lower prices were not promised; the principal near-term significance was Micron’s manufacturing transition.
The Bottom Line
Micron’s headline referred to a specific 2020 milestone: first-generation 128-layer replacement-gate NAND entered volume production in FQ3 2020, followed by revenue and consumer-SSD shipments in FQ4. It marked a new Micron NAND architecture and roadmap step—not an instant, across-the-board SSD upgrade.
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