Indigenous Technology for Next
Generation IC Industry
In today’s world, semiconductor chips play a vital role in day to day life by making our life pleasurable, safer, and healthier. The radical improvements in integrated circuits (IC) performance stem primarily from the interconnection of millions of active and passive components such as logic, memory, input-output and power management modules on a single silicon chip. Semiconductor device manufacturers compete to offer cost effective devices that combine high performance and functionalities with low heat generation. This competition has resulted in a relentless drive to reduce the (IC) chip feature size. Reducing the device feature size boosts speed and improves the economics of manufacturing by allowing more transistors (often more than 50 million) to be placed on a single chip.
State of the art in IC fabrication technology
The current high end IC technology node in manufacturing is 22 nm and looking toward 16 and 10 nm nodes to meet the unprecedented market demand. Presently, the Deep Ultraviolet Lithography (DUVL) tool sets have reached their potential for further development and may not be able to break the 22 nm barrier.
Among the potential next generation tools (e.g., Extreme ultraviolet lithography (EUVL), EB, X-ray and nanoimprinting technologies), it is expected that EUVL at 13.5 nm wavelength has good prospects of being adopted for high volume production in the near future for ICs at the 16 and 10 nm nodes. For authentic realization and implementation with EUVL for sub-20 nm nodes, a highly sensitivity resist technology inclusive of narrow line width ~16 nm, small line edge roughness at 3σ (1.5nm), and high photo sensitivity at 2-10mJ/cm2
IIT Mandi tackles the Global Problem
Therefore, four years ago in 2012, IIT Mandi launched an initiative for the research and development of futuristic device fabrication technologies with the support of Intel Corp USA. Intel provided about Rs. 2.5 Crore to IIT Mandi with an additional Rs. 2 Crore for use of the EUV exposure facility at LBNL, USA. The goal of this project under the guidance of Prof. Kenneth Gonsalves, Visiting Distinguished Professor, was to design and develop a suitable and sustainable resist technology for next generation EUV technology at IIT Mandi.
Prof. Kenneth Gonsalves (material chemistry) with his interdisciplinary team of researchers developed a unique strategy to deal with key problems causing the technical deficiencies in the current EUV photoresist technology.
|Figure 1. FESEM images of EUV exposed at dose 98.1837 mj/cm2, MAPDSA–MAPDST (5:95) copolymer designed and developed at IIT Mandi resist formulation: High resolution 20, 22, 24, 26, 28 and 30 nm dense lines patterns with various L/S. |
|Left to right, Top row: Prof. Kenneth Gonsalves, Dr. Satinder Sharma; Bottom row: Dr. Subrata Ghosh, Dr. Pradeep Parameswaran ||The team included Dr. Subrata Ghosh (Organic Chemistry), Dr. Pradeep Parameswaran (Inorganic Chemistry), both Associate Professors, School of Basic Sciences (SBS); and Dr. Satinder Sharma (Electronic Materials), Assistant Professor, School of Computing and Electrical Engineering (SCEE) along with Postdoctoral research fellows Dr. Satyendra Prakash Pal, Dr. Pawan Kumar and Ph.D scholar Guruprasad Reddy. In 2012, they started work in the Advanced Materials Research Centre (AMRC) of IIT Mandi. |
The current project at IIT Mandi encompasses the design and development of resists that are directly sensitive to EUV photons without utilizing the concept of chemical amplification. These non-chemically amplified resists (non-CARs) address many of the inherent problems of currently used chemically amplified resist technology (e.g., acid diffusion, sensitivity, post exposure instability etc.). They are highly sensitive to photons of various wavelengths (EUV and EBL). This new resist design is accomplished by polymers that are prepared from radiation sensitive monomers containing sulfonium groups.
Figure 2. AFM images of EUV exposed MAPDSA–MAPDST (5:95) copolymer resist (a) and (b) High resolution 20, and 22 nm dense lines patterns with various L/S, (c) and (d) AFM images of EUV exposed Polyalkylsulfide resist high resolution 20, and 22 nm dense lines patterns with various L/S.
|Figure 3. (A) EUV exposed FESEM images of 20, 25, 30, 35, 40 nm [L/5S] and (B) A.F.M images of 20 and 25 nm line/ space of IIT Mandi designed and developed a novel Polyalkylsulfide resist formulation.|
This indigenously designed and developed resists formulation has successfully demonstrated for resolution of 20 nm under EUV, at SEMATECH, Lawrence Berkeley National Laboratory (LBNL) , USA (with available Micro Exposure Tool (MET)). It was also observed that these novel indigenously developed resists formulation are sensitive to e-beam irradiation also and would therefore be useful for EUVL down to the 16 nm node and below.
While we are at the forefront of Global competition on developing cutting-edge resists technology for sub-20 nm nodes, we are equally aware of our immediate National needs. The Indian semiconductor industries particularly Semiconductor Laboratory (SCL) , Mohali are involved in 180 nm node technology. To print these nodes, SCL is currently using four different types of photoresists that are sensitive to deep ultraviolet (DUV) light. As no Indian manufacturer develops these DUV resists, SCL is fully dependant on foreign vendors, and hence, there is a dire need for indigenous technology to develop DUV resists. In this context, the IIT Mandi photoresists team led by Prof. Kenneth Gonsalves has taken up the challenge of developing DUV resists for Indian semiconductor industries to establish sustainable ecosystem to meet National requirements.
Figure 4. (A) EUV exposed FESEM images of nanowaves and nanoboates complex patterns on IIT Mandi designed and developed MAPDST resist formulation; (B) Higher magnification images (mag 120K) of nanowaves; (C) Higher magnification images (mag 120K) of nanoboats
| Figure 5. (A) EUV exposed FESEM images of complex circular pattern on IIT Mandi designed and developed MAPDST resist formulation; (B) AFM images of the complex circular pattern on IIT Mandi designed and developed MAPDST resist formulation.|
After four years of successful development of indigenous high end DUV, EBL and EUVL photoresists and meeting the expectation of front line semiconductor industry, Intel, USA, IIT Mandi has recently received good amount of funding of about Rs. 7 crores from various Indian funding agencies including SCL (ISRO), DST and MHRD to develop indigenous resist technology. IIT Mandi is also now involved in a bilateral resists technology program with the National Taiwan University (NTU) to develop another class of novel photoresists to control some of the key issues associated with most of the commercial resists particularly for low node technology.
Encouraged and excited with the success of the highly prized nanotechnology research, IIT Mandi is gearing up to boost its nanofabrication technology research by putting up an advanced and sophisticated Centre for Design & Fabrication of Electronic Devices (C4DFED)
at IIT Mandi. This upcoming Centre is located in a specially-constructed building with ~4,000 square feet area. It will house Class 100 and 1000 labs equipped with the latest equipments and infrastructure required for ongoing and future research in the field of next generation device fabrication and characterization.
This state-of-art technology developed indigenously at IIT Mandi will also be helpful for Indian industries and entrepreneurs in context of Make in India initiative taken by the Government of India. For this promotion, IIT Mandi is in the process of organizing an International conference on the “Trends in Technologies for Fabrication of Futuristic Semiconductor Devices – Make in India context” in early 2017 where international experts, scientists, technologists, industrialists and entrepreneurs will gather to discuss and plan future strategies.
IIT Mandi acknowledges the financial support for this project by Intel Corp USA administered through the Semiconductor Research Corp (SRC) and the INUP at IIT-Bombay who provided facilities for the research.