MonolithIC 3D Inc. Granted Fundamental Patents on 3D-ICs for Logic and Memory Applications

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Techniques to monolithically build single crystal silicon transistors in 3D stacked layers invented.

Zvi Or-Bach, the President and CEO of MonolithIC 3D Inc.

Our patent portfolio includes broad and fundamental claims on Monolithic 3D-IC Technology

MonolithIC 3D Inc., a Silicon Valley startup, announced today that it has been granted 4 fundamental patents on monolithic 3D-IC technology. These patents describe techniques to obtain low-cost monolithic 3D chips with single crystal silicon transistors and high vertical connectivity. In addition to the 4 granted patents, the company has more than 50 other patents pending, making it one of the key players in the 3D-IC field. MonolithIC 3D Inc. was recently selected as a Finalist of the “Best of Semicon West 2011” for its disruptive technology.

The granted patents, which include US Patent #8,026,521, #7,986,042, #7,960,242 and #7,964,916, have important implications for both logic and memory chip technology. Zvi Or-Bach, the President and CEO of MonolithIC 3D Inc. said, “We are pleased with this recognition from the US Patent Office. Our patent portfolio includes broad and fundamental claims, providing MonolithIC 3D Inc. with strong IP protection. Our technologies utilize processes, materials and transistor types well-known to the semiconductor industry, making adoption practical and attractive.”

Since the 1960s, industry luminaries such as James Early have dreamt of chips where single crystal silicon transistors are constructed monolithically above Aluminum or Copper wiring layers. These could enable logic chips where components are arranged as a three-dimensional cube, making wires shorter and boosting chip performance. Unfortunately, high-quality transistors require temperatures higher than 900oC for activating dopants in source and drain regions. Such temperatures are not compatible with pre-processed Aluminum or Copper wiring layers.

MonolithIC 3D Inc.’s granted patents present practical solutions to this important problem. A gate-last process is used innovatively in combination with a breakthrough wafer-to-wafer alignment scheme. “Gate-last transistor technologies are considered the industry-standard today, with companies such as Intel, TSMC, Globalfoundries and Samsung all announcing support for the technology”, notes Brian Cronquist, MonolithIC 3D Inc’s VP of Technology & IP. “The fact that MonolithIC 3D Inc.’s logic solutions work with any gate-last transistor technology makes it particularly attractive. The vertical connection density of monolithic 3D technology is 10,000x higher than the Through-Silicon Via (TSV) 3D solutions available today.”

The granted patents also cover fundamental advances in monolithic 3D memory technology. Members of the memory industry, such as Toshiba, Samsung, Hynix and Micron, have been pursuing monolithic 3D NAND flash memories with polysilicon transistors. These technologies have challenges with the low drive current, high sub-threshold slope and large variability of polysilicon based transistors. This makes multi-level cell (MLC) operation difficult. MonolithIC 3D Inc.’s single crystal silicon transistors tackle this issue, and make Monolithic 3D NAND flash memories much more viable from a practical standpoint.

The company has also invented Monolithic 3D DRAM and resistive memory solutions that utilize single crystal silicon transistors and lithography steps that are shared between multiple layers of memory. Dr. Deepak Sekar, the Chief Scientist of MonolithIC 3D Inc., said, “While several companies have pursued Monolithic 3D NAND flash memory, there has been almost no work on Monolithic 3D DRAM or resistive memories where multiple layers of transistors are patterned with shared lithography steps. This is because polysilicon cannot be used for many of these applications. Our company’s single crystal silicon transistor stacks enable a cost-effective and practical application of Monolithic 3D to DRAM and resistive memories. The industry could achieve several generations of progress with these technologies.”

Further details of MonolithIC 3D Inc.’s technologies are available on its website. MonolithIC 3D Inc.’s business model involves Intellectual Property (IP) Licensing to partners who then take the technology to manufacturing.

About MonolithIC 3D Inc.:
MonolithIC 3D Inc. is an IP company dedicated to innovation in semiconductor design and fabrication. It invented and developed a practical path to the monolithic 3D Integrated Circuit, which includes multiple derivatives for Logic, Memory and Electro Optic devices. The company was recently selected as a finalist of the Best of Semicon West 2011, which recognizes the most important product and technology developments at Semicon West. More information about the company, including detailed technical information, can be found at its website.

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Brian Cronquist
MonolithIC 3D Inc.
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