Unrivaled to small and powerful microchips

Fraunhofer ISIT and project partner IMS Nanofabrication ('IMS') have jointly developed the MEMS processing of a CMOS chip designed by IMS, which pushes the limits of what is technologically possible and represents a crucial key component for further miniaturization in semiconductor micro- and nanoelectronics. 


The challenge:

For decades, the semiconductor industry has strived to optimize the power consumption, switching speed and area requirements of electronic components through miniaturization. After more than 50 years of continuous miniaturization of structures, the current major technical and physical barriers lie in the imaging technologies of photolithography, and specifically in the fabrication of high-resolution photomasks. Photomasks are needed in every chip fabrication to transfer the micro- to nanometer-sized structures that define the chip onto a photoresist-coated silicon wafer. 

A technology node (smallest structure size) defines an achievable miniaturization level and thus the manufacturing processes based on it. By falling below the 10 nm technology node a few years ago, EUV lithography with a wavelength of only 13.5 nm became indispensable for further technical development.  

For the fabrication of photolithographic EUV masks, techniques are needed that allow the definition of very small structures sufficiently fast and efficiently. So-called electron beam mask writers are used for this purpose. 

If EUV masks with a high density of complex geometric structures are to be written, the current single-beam electron mask writers reach their limits. Limiting factors here are both the large amounts of data required to define such masks and the writing time required to produce them on the mask substrate. Single-beam electron mask recorders, for example, would require several days of writing time for a complex EUV mask. 


The solution:

The technical and economic conditions were the motivation of the electron multi-beam mask writer (MBMW - Multi-Beam Mask Writer) developed by IMS, whose core is the TROM2 chip - an electronically controllable "pinhole" processed by MEMS technology for parallel deflection of many electron beams. 

Integrated into this chip is advanced CMOS electronics with signal processing and circuit logic. On top of these electronic structures is the jointly developed MEMS design, which ensures that the electron beams fly through the chip while being individually deflected.

The TROM2 chip combines state-of-the-art CMOS high-speed signal processing with MEMS technologies. The entire MEMS process consists of over 200 individual steps and combines, among other things, high aspect ratio electroplating technologies, the Deep Reactive Ion Etch (DRIE) process based on the so-called BOSCH process, and anisotropic KOH etching of silicon.


Unique advantages of the TROM2 chip

Post-CMOS MEMS processing enables the TROM2 chip with 262,144 parallel writing electron beams to write complex structures within a few hours in high quality and resolution on photomasks for the 14 nm and 10 nm technology node as well as on high-resolution EUV masks for the 7 nm and 5 nm technology node.


Such a performance is so far completely unmatched in worldwide comparison with common electron beam mask writers, so that the concept of the MBMW currently represents the absolute spearhead of mask writing technologies.


For this reason, the TROM2 chip as the heart of the MBMW (Multi-Beam Mask Writer) plays a decisive key role for the further development of new technology generations in the semiconductor industry and thus for the further miniaturization of microelectronics.

The application

In 2017, the first multi-beam mask writer MBMW-101 was launched and was used for the production of masks for the 7 nm technology node.

The latest generation of multi-beam mask writer is the MBMW-201, equipment that has been in the FABs of major semiconductor manufacturers since 2019 and is used for the production of chips of the 5 nm technology node. The MBMW-201 can even be used for the future 3 nm technology node, which is expected to become commercially relevant from 2022.


The outlook

Currently, the developments of the follow-up project between IMS and ISIT are starting to realize the further improved TROM3 chip. This is expected to populate future MBMW-301 devices and enable the next big leap beyond the 3nm technology node in semiconductor technology. MBMW-301 devices will be able to meet the industry needs of future EUV lithography devices that continue to increase in resolution through the end of this decade and beyond. This keeps IMS at the forefront of the semiconductor industry with its MEMS manufacturing partner ISIT. 

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