SK hynix

What the company is

SK hynix describes itself as a Korea-headquartered semiconductor supplier of DRAM and NAND flash memory to customers worldwide^[1]. The two product families do different jobs. DRAM is the working memory a processor reads from and writes to while a program runs; NAND flash is the storage that keeps data when the power is off. Both are sold as standard parts to many customers, and both are exposed to wide swings in price and demand.

Alongside those two lines, the company has become known for high-bandwidth memory (HBM). HBM is built differently from ordinary memory chips. Rather than placing DRAM dies flat, it stacks several dies vertically and connects the layers with through-silicon vias (TSV) — narrow vertical wires that pass through the silicon so that the stacked layers can be used together as one wide, fast device. The purpose of stacking is bandwidth: a broader path between memory and processor than a conventional package provides.

From 2009 to the first product

SK hynix says it began HBM development in 2009, and that work on TSV technology took four years before the first product was ready. In December 2013 the company released the world's first HBM based on through-silicon via technology^[2]. The gap between the start of development and the announcement is the part of the story the company tends to emphasise: the stacking process, not the memory cell, was the hard problem.

Six generations

The company counts six HBM generations: HBM, HBM2, HBM2E, HBM3, HBM3E and HBM4^[2]. It says it is the only supplier to have developed and shipped every one of them, from HBM1 through HBM3E^[1].

Three dates mark the recent part of that sequence. In March 2024 SK hynix began mass production of HBM3E, which it described at the time as the world's best-performing HBM^[2]. In September 2024 it became the first company to mass produce 12-layer HBM3E, with a capacity of 36 GB^[1]. In March 2025 it supplied 12-layer HBM4 samples to major customers, the first in the industry to do so^[3].

Reading the milestones

Two numbers run through the company's recent announcements: how many dies are stacked, and how much capacity the stack holds. Stacking more layers in the same package area is one route to more capacity per device, and the move from earlier layer counts to a 12-layer product with 36 GB is presented by the company in exactly those terms^[1]. Samples, mass production and customer shipment are also different stages: a sample is a part sent for evaluation, while mass production means the part is being built in volume.

Memory has long been a business where suppliers compete heavily on cost and scale, because the parts are standardised and interchangeable. HBM moves part of the competition somewhere else — into the stacking and packaging process, where the number of layers, the yield of the stack and the connection between layers decide what a supplier can offer. That is why the company traces its position back to the four years of TSV work before its first product, rather than to a single generation^[2].

It is worth being precise about what these records are. The claim of having shipped every generation, the description of HBM3E as the best-performing HBM, and the firsts for 12-layer HBM3E and 12-layer HBM4 samples are all the company's own statements about its products^[1][2][3]. They describe what SK hynix says it has built and when, not an independent comparison against other suppliers. On the public record, the sequence stops at HBM4 samples; the company's announcements do not yet describe volume production of that generation.