Chinese memory manufacturer CXMT is struggling to raise yields for fourth-generation HBM3, producing an initial yield of about 25% in pilot production, compared with more than 90% at South Korean rival SK Hynix. Industry sources estimate CXMT trails leading HBM manufacturers by roughly four to five years. The company’s 8-Hi HBM3 reportedly achieved front-end process yields of about 30%, while only around 70% of front-end survivors became qualified products after back-end packaging, meaning nearly 80 of every 100 chips were scrapped. The main obstacle is TSV (through-silicon via) technology, which vertically connects stacked DRAM layers and requires extensive wafer-processing and packaging experience. CXMT has nevertheless provided small quantities of working HBM samples to Alibaba and AI-chip designer Cambricon while continuing to improve its process. The company’s current yield is well below the industry’s approximately 80% mass-production threshold. HBM demand has surged alongside AI investment, prompting Samsung Electronics, SK Hynix and Micron Technology to redirect capacity toward HBM and intensifying conventional DRAM supply constraints. Samsung has allocated 50% to 60% of its 4nm capacity, or about 15,000 wafers per month, to HBM4 base dies, while its S5 and S6 lines at Pyeongtaek have combined capacity of 30,000 4nm wafers per month. KB Securities says Samsung Electronics and SK Hynix have less than 10 days of memory inventory, while next year’s supply is expected to remain insufficient. The brokerage says HBM4 requires about three times the wafer volume of conventional DRAM and projects DRAM and NAND demand will exceed supply by more than 10 percentage points in 2027. It also estimates global hyperscale data-center operators will raise AI infrastructure investment expectations for next year to $1.3 trillion, up 60% year over year, with memory representing 57% of 2027 investment versus 14% last year. SK Hynix, Micron and Samsung are pursuing different HBM4 technology strategies, and CXMT’s ability to overcome its yield bottleneck will be an important measure of China’s progress toward memory-industry self-reliance.