The machines that etch the most advanced chips will soon need much larger “stencils.”
To manufacture a chip, manufacturers project extremely fine patterns onto a wafer, layer by layer. These patterns come from a photomask, a highly precise template used by the lithography machine. Today, the masks used for the most advanced processes measure about 15 cm on each side.
Detail of the structures inscribed on a chrome photomask.
Credit: Sei / Wikimedia Commons — CC BY-SA 4.0
ASML and TSMC are now preparing to move to a format measuring about 30 cm, or 12 inches. The change will accompany the new generation of machines using extreme ultraviolet, or EUV. This light makes it possible to draw the tiny details required by today’s processors. The first so-called High NA machines will nevertheless operate with the current masks.
Why double their size? Future chips, particularly those intended for artificial intelligence, will be very large. With the current system, the machine may need to expose several areas separately to reproduce the entire design. These sections must then be joined with extremely high precision. This operation, known as assembly or “stitching,” slows manufacturing and imposes additional constraints.
A larger mask would make it possible to place more patterns in a single usable area. Manufacturers could therefore produce large chips with fewer separate exposures. For a factory processing thousands of silicon wafers, avoiding a few steps can have a significant effect on machine throughput and the cost of each chip.
But changing the format is a major investment: the entire chain must evolve: mask manufacturing, defect inspection, handling, and transport. Lithography machines will also have to be adapted. That is why ASML and TSMC are launching this transition several years before its planned industrial use.
The timeline gives an idea of the scale of the project. TSMC plans to use ASML’s High NA technology for mass production starting in 2030, initially with the current masks. The partners want to establish a pilot line for 12-inch masks in 2031. Systems compatible with this format are expected for advanced production around 2033.
This development directly concerns the generations of processors that will follow those currently in preparation.
The move to large photomasks now depends on many suppliers, not just ASML and TSMC. Semiconductor manufacturers and mask specialists have already expressed interest in the initiative. The coming years will notably be used to build the equipment capable of producing and inspecting these new masks before they arrive in factories.