Most of the HBM supply chain runs through Korea. Samsung Electronics and SK hynix, with 83 percent of HBM revenue in the second quarter of 2026 per Counterpoint Research, fabricate the core DRAM dies, form through-silicon vias in them, and stack, bond and test them in Korean plants. SK hynix buys its HBM4 base die from TSMC, and the finished stacks leave for advanced packaging lines, led by TSMC’s CoWoS, that mount them beside AI processors.
Market size and the national context sit in the reference guide to Korea’s semiconductor industry and its HBM leadership. This piece maps the chain itself: who controls each layer, where the two Korean makers diverge, and where a foreign equipment or materials supplier can enter.
Data current as of September 2026.
Who Leads the HBM Market in 2026?
SK hynix still leads, by a narrower margin: it held 50 percent of HBM revenue in the second quarter of 2026, Samsung 33 percent and Micron 18 percent, per Counterpoint Research’s quarterly tracker updated on 1 September 2026. A quarter earlier the split was 58, 21 and 21. A year earlier, SK hynix held 64 percent of revenue on Counterpoint’s current series; the firm’s original Q2 2025 release, which measured shipments, put its share at 62.
The swing came from timing. Samsung announced on 12 February 2026 that it had begun mass production of HBM4 and shipped commercial product to customers, which Samsung called an industry first, built on 1c DRAM with a 4nm logic base die, per its newsroom. Counterpoint noted in its September 2026 update that HBM3E still generated most HBM revenue, and in August that HBM4 shipments began rising in the third quarter as Nvidia Vera Rubin and AMD Instinct MI455X racks started shipping.
Share of revenue and share of the flagship customer are different measures. TrendForce reported in January 2026 that SK hynix was expected to supply about two thirds of Nvidia’s HBM4 demand for Vera Rubin. In August 2026 TrendForce, citing the Seoul Economic Daily, reported that Samsung’s HBM4 yield had reached 80 percent from below 60 percent at the start of mass production, and that Samsung was aiming for about 38 percent of the HBM market by year end, a company target.
What Are the Stages of the HBM Supply Chain?
HBM moves through six stages: core DRAM, base die, TSV and thinning, stacking and bonding, test, and integration beside the processor. For Samsung and SK hynix output, the core DRAM, TSV, stacking and test stages stay inside Korea; SK hynix buys its HBM4 base die from TSMC while Samsung makes its own, and integration goes to packaging lines led by TSMC.
Core DRAM. HBM consumes leading-edge DRAM capacity. SK hynix builds its HBM4 core dies on 1b DRAM and Samsung on 1c DRAM, per their newsrooms.
Base die. This is where the two Korean makers split most visibly. SK hynix sources its HBM4 base die from TSMC, while Samsung makes its own in its foundry, a difference set out in the comparison of Samsung vs SK hynix suppliers. The base die is also becoming a design surface. At Hot Chips in August 2026, Samsung presented custom HBM that moves memory control and some AI computation from the GPU into the base die, per the Seoul Economic Daily.
TSV, thinning and bumping. Each core DRAM wafer runs a wafer-level flow that SK hynix set out at Hot Chips in August 2026: silicon etch and copper fill for the through-silicon vias, metallization, thinning, back-side processing, singulation and test, with TSV formation and micro-bumping among the hardest steps, per ServeTheHome. In April 2024 SK hynix said M15X would be well placed for HBM production because it sits next to M15 in Cheongju, which has been expanding TSV capability, per its newsroom.
Stacking and bonding. Covered in the next section.
Test. Covered below.
Integration. The stack leaves Korea for 2.5D packaging. TrendForce reported in June 2026, citing Taiwanese press and Reuters, that TSMC’s monthly CoWoS capacity could reach 120,000 to 140,000 wafers in 2026, with the supply and demand gap expected to narrow from about 20 percent to about 10 percent by year end. The last constraint sits largely in Taiwan.
How Do Samsung and SK hynix Stack HBM Differently?
SK hynix uses mass reflow molded underfill (MR-MUF), and Samsung uses thermal compression with non-conductive film (TC NCF). That single process choice decides which materials each buys and which bonding and molding tools matter on its lines.
SK hynix introduced MR-MUF with HBM2E in 2019. The process melts the bumps between all stacked chips at once and fills the gaps with an epoxy molding compound. Each die is still tacked in place with a brief burst of heat as it is stacked, on thermal compression bonders, so both makers buy TC bonders; the processes differ in how the joints form and how the gaps are filled. Advanced MR-MUF, developed for 12-layer HBM3 in 2023, uses a new compound with 1.6 times the heat dissipation of the original, per the SK hynix Newsroom in July 2024. The company confirmed Advanced MR-MUF for its HBM4 when it completed what it called the world’s first HBM4 development on 12 September 2025. TrendForce reported in January 2026 that SK hynix would keep MR-MUF for 16-high HBM4 after fluxless bonding evaluations fell short, thinning each DRAM die to 30 micrometers to fit the JEDEC height limit of 775 micrometers.
Samsung applies film between each layer as it stacks. Its February 2024 newsroom release on 12-layer HBM3E described advanced TC NCF with the thinnest film it had made, a seven micrometer gap between chips, and bumps of varied sizes to improve thermal behavior.
Hybrid bonding is the next transition, and its timing keeps moving. It joins metal pads between dies directly with no intermediate material, which SK hynix presented at Hot Chips 2026 as reducing heat and strengthening the bond, per the Seoul Economic Daily. TrendForce reported in July 2026 that both Korean makers stayed with thermal compression bonding for HBM4 and that 16-high HBM4E was the earliest likely adoption point. At Hot Chips in August 2026, SK hynix said hybrid bonding would not be ready for HBM4E, moving its earliest use to HBM5, per Tom’s Hardware. Samsung is preparing a line of about 50 die-to-wafer hybrid bonders at Pyeongtaek, with BESI as preferred supplier and installation expected from the end of 2026, per The Elec on 22 July 2026; TrendForce, relaying that report and Weekly Post, put full-scale production at 2029 to 2030. TrendForce’s July report gave JEDEC’s package height at 720 micrometers for HBM3E and 775 for HBM4, with 900 to 1,000 micrometers under discussion for HBM5. A looser height limit lets thermal compression survive longer, which matters to every bonder and materials supplier. SK hynix buys HBM TC bonders from Hanmi Semiconductor, Hanwha Semitech and ASMPT, and Hanwha’s infringement suit against Hanmi is before the Seoul Central District Court; allocations and the case are covered in the Samsung vs SK hynix supplier comparison. Samsung’s TC bonders come mainly from its affiliate Semes, with Hanmi, ASMPT and BESI in talks, per Aju Business Daily in February 2026.
Why Has Test Become a Growth Layer in the HBM Supply Chain?
HBM4 requires more inspection items and longer test times than HBM3E, so the same output needs more testers. Global Economic reported that point in August 2026, alongside the order book: SK hynix placed four HBM4 wafer tester orders with two Korean equipment makers in 2026, worth a combined 247.84 billion won.
Digital Frontier, a subsidiary of DI Corporation, took 99.75 billion won in January and 96.25 billion won in March. Its March disclosure, reported by DigitalToday, set a contract period of 27 March to 31 August 2026. UniTest took 29.16 billion won in May and 22.68 billion won in July.
Techwing received its first commercial SK hynix order for its Cube Prober in June 2026, having already supplied Samsung, per The Elec. The system tests individual HBM cubes 256 at a time across a range of minus 40 to 150 degrees Celsius. TrendForce reported in February 2026, citing The Elec, that SK hynix had developed its own system-level test equipment for HBM4 to catch defects that appear only after integration with the AI chip, because customized base dies make compatibility checks part of the memory maker’s job.
Domestic makers now hold qualified positions at SK hynix in wafer test, burn-in and cube probing, which is the outcome Korea’s semiconductor localization policy exists to fund. The foreign position that holds is the automated test equipment itself: the Cube Prober runs Advantest and Teradyne testers, per The Elec. SK hynix co-developed its system-level tester with partners, per the same TrendForce report, so that step opens only through the maker’s own development programs.
Where Is Korea Adding HBM Capacity?
Memory demand is running ahead of supply: a KB Securities report of 7 September 2026, carried by DigiTimes, put memory inventories at both Korean makers below ten days. Korea is building HBM packaging capacity next to the DRAM fabs that feed it. SK hynix broke ground on 22 April 2026 on P&T7, a 19 trillion won advanced packaging plant in the Cheongju Technopolis industrial complex, with the wafer test line targeted for October 2027 and the wafer-level packaging line for February 2028, per TrendForce citing the company. KED Global reported in January 2026 that DRAM wafers from M15X would be packaged into HBM on site.
Samsung’s HBM back end sits at Onyang and Cheonan in South Chungcheong, and DigiTimes reported on 20 August 2026 that Samsung would break ground in September on a 6 trillion won HBM production and advanced packaging facility at Onyang. The longer-range memory capacity is in Yongin, where SK hynix targets its first cleanroom in February 2027, and the procurement paths for that site are set out in the guide to the Yongin semiconductor cluster. Co-location puts packaging tool, materials and facility-system decisions on the same construction timeline as the fab.
Part of the back end is also moving abroad. SK hynix broke ground on 27 August 2026, local time, on its first HBM production base in the United States, in West Lafayette, Indiana, where wafers made in Korea will be packaged and tested. Its newsroom gives an investment of over 4 billion dollars, cleanroom completion in October 2028 and mass production of next-generation HBM in the second half of 2029.
What Does the HBM Supply Chain Mean for Foreign Suppliers?
The addressable spend in HBM has moved toward bonding, molding, test and packaging facilities, and each layer is tied to a specific maker’s process.
Sell into a process lineage. An underfill or molding compound built for MR-MUF has no place on a TC NCF line, and a film has no place on an MR-MUF line. Identify which maker’s process your product fits before you build a Korea plan. TrendForce reported in January 2026 that the approaching expiry of SK hynix’s exclusive MR-MUF materials agreement with Namics is influencing its process planning, which opens a second-source question for molded underfill at the largest HBM maker.
Time against generations, and allow for slips. Samsung began shipping 12-layer HBM4E samples on 29 May 2026, per its newsroom, so HBM4E tool and material decisions are being made now. At SK hynix, hybrid bonding has slipped twice; Samsung is preparing a hybrid bonding line for full-scale production around 2029 to 2030. A supplier whose product depends on a process change should plan for it to arrive late.
Expect a Korean competitor in test and inspection. SK hynix’s disclosed 2026 HBM4 wafer tester orders went to domestic makers. A foreign tool now competes on a capability gap and on service depth.
Budget for qualification. Every one of these layers runs through formal evaluation at the memory maker, set out in the guide to the fab qualification process in Korea, and the finished stack then faces the GPU customer’s own. Samsung completed 12-layer HBM3E development in February 2024, per its newsroom, and KED Global reported in September 2025 that the product had passed Nvidia’s qualification after a string of failed attempts.
Frequently Asked Questions
What is the HBM supply chain? It is the sequence that turns DRAM wafers into High Bandwidth Memory stacks for AI processors: core DRAM fabrication, a logic base die, through-silicon vias, wafer thinning and bumping, stacking and bonding, multi-stage test, and integration beside the GPU on an interposer. Samsung and SK hynix run the DRAM, TSV, stacking and test stages inside Korea. SK hynix sources its HBM4 base die from TSMC, and integration is led by TSMC’s CoWoS packaging.
Who has the largest HBM market share in 2026? SK hynix, with 50 percent of HBM revenue in the second quarter of 2026, followed by Samsung at 33 percent and Micron at 18 percent, per Counterpoint Research’s tracker updated in September 2026. Samsung rose from 21 percent a quarter earlier after shipping what it called the industry’s first commercial HBM4 in February 2026. Shares move quarterly, so check the latest release.
How do SK hynix and Samsung stack HBM differently? SK hynix uses mass reflow molded underfill, bonding all stacked dies at once. Samsung uses thermal compression with non-conductive film applied layer by layer. Both kept thermal compression bonding for HBM4. TrendForce reported in July 2026 that hybrid bonding would most likely arrive first with 16-high HBM4E, but SK hynix said in August 2026 it would not be ready for HBM4E, putting its first use at HBM5 at the earliest, while Samsung is preparing a hybrid bonding line.
Where can a foreign supplier enter the HBM supply chain in Korea? The growing spend sits in bonding, molding materials, test and inspection, thermal management and the facility systems around new packaging plants such as SK hynix’s P&T7 in Cheongju. Each entry point is tied to one maker’s process, Korean toolmakers now compete hard in test, and every position runs through formal qualification at Samsung or SK hynix, with the finished stack then qualified by the GPU customer.
Where to Take This
Korean HBM value concentrates in stacking, test and packaging, split between two makers on different processes. Inquivix Technologies works with global semiconductor equipment, materials and clean-process companies entering Korea’s semiconductor market, covering representation, distribution, technical localization and qualification support. To work through where your product fits in the HBM chain, contact Joon K Lee at joon@joonklee.com.
