Finnish semiconductor metrology startup Chipmetrics has begun targeting the South Korean market. As 3D NAND moves beyond 300 layers toward 1,000 layers, technology to precisely measure thin-film quality inside deep, narrow holes is emerging as a new variable in the race for yield. Chipmetrics is aiming to enter the mass-production lines of Samsung Electronics and SK Hynix with metrology technology it says is hundreds of times faster than existing methods.

Chipmetrics visited South Korea through the EU Business Hub programme to coincide with Semicon Korea 2026. Chipmetrics CEO Mikko Utriainen (미코 우트리아이넨) said Samsung Electronics is already planning 1,000-layer 3D NAND. He said the more layers are stacked, the more crucial it becomes to precisely measure thin-film quality inside deep, narrow holes.

3D NAND memory increases capacity by stacking cells vertically. It has already surpassed 300 layers and is heading toward 1,000 layers. The problem is that the more layers are stacked, the deeper and narrower the holes become. This ratio is called the aspect ratio, and current 3D NAND is at 120 to 150. Uniformly depositing thin films inside the holes determines yield, but existing methods make precise measurement difficult.

Chipmetrics' core technology is a Lateral HAR Test Structure. Utriainen explained that conventional methods cut a wafer cross-section and image it with a transmission electron microscope, but even a slight tilt at the nanometre level affects results, making it very difficult and costly. He added that analysing 7 samples per day is the limit.

Chipmetrics uses a different structure. After peeling off a 5-micrometre-thick membrane, it measures thin-film thickness at points along the sidewalls. This produces a thickness mapping curve. Analysis takes 3 minutes, enabling processing of hundreds of samples a day. Utriainen said its test structure can measure aspect ratios up to 40,000. He said it can verify thin-film deposition quality in structures with aspect ratios that are effectively close to infinite.

Another strength of the technology is that it can identify the process window. Utriainen said conventional methods can only check whether a thin film exists, but Chipmetrics can tell exactly where deposition ends on the curve. He said this allows prediction of whether the current process is suitable for next-generation products.

◆Targeting the South Korean market: "The goal is to enter the supply chains of Samsung Electronics and SK Hynix"

Limits in existing metrology have also come close. Chipmetrics CTO Feng Gao (가오펑) explained using uniformity and conformality. Gao said the two are different concepts. He said uniformity means whether thickness is the same across the entire wafer, while conformality refers to uniformity inside three-dimensional structures.

Most fabs currently measure only planar uniformity. Even if they change precursors, they pass the process if thickness is the same on a flat surface. But conformality can differ. Gao said people think they have monitored everything, but the chip ultimately does not work. He said when they check at the final process step, they find a thin-film issue, but because ALD quality passed, they do not know the cause.

Such differences lead to product quality. Utriainen presented figures on yield improvement effects, saying a 1 percent yield improvement generates about $100 million in value for a device manufacturer. He said its equipment is priced at about $5 million, less than 5 percent of the value of yield improvement.

Chipmetrics currently has customer relationships with South Korean ALD equipment companies such as Wonik IPS. Its final goal is device manufacturers. Utriainen said they tend to prefer tier-one suppliers and are reluctant to share information. He said the company is currently focusing on technology validation through research institutes and universities.