Current and Next Generation Lithography - Fundamentals and Applications

We recommend you to submit your preliminary or firm registration at least 4 weeks before course start to ensure a seat on the course.

TECHNOLOGY FOCUS
The explosive growth in the capability of semiconductor devices has to a large extent been due to advances in lithography. Miniaturization has enabled both the number of transistors on a chip and the speed of the transistor to be increased by orders of magnitude. At the same time, one has managed to reduce the power per transistor so that the chips do not overheat. This trend still continues uninterrupted. Sustaining Moore's Law requires continuous advancements in lithographic resolution.

Mainstream optical lithography has kept pace with this evolution for several decades and has always been the workhorse for patterning the critical layers in semiconductor applications. However, the physical limits of optical lithography are coming closer and alternative (non-optical) lithography technologies are expected to take over at some point in time. Besides semiconductors, non-semiconductor nano- and micro-technologies, e.g. MEMS, sensors, magnetic storage media, are emerging and will eventually find their place in volume markets as well. The lithography requirements for these technologies are often totally different from the semiconductor requirements. As a consequence other types of lithography may be preferred for these applications. The ability to replicate patterns from micro-scale to nano-scale is of crucial importance to the advance of micro- and nano-technologies and the study of nano sciences.

COURSE CONTENT
The goal of this course is to give a broad overview of various micro- and nanolithography technologies that are being used or considered for semiconductor and non-semiconductor applications. For each technology, the strong and weak points and typical applications will be treated. For all mask based lithographies, the status and challenges for mask (template) manufacturing will be discussed.

WHO SHOULD ATTEND
This course is intended for engineers who are active in the field of lithography or have to take strategic decisions on lithography for their company. It will form the basis for a better fundamental understanding of the capabilities and limitations of each type of lithography, and may also suggest better, cheaper or alternative lithography technologies to be considered for their applications.

Monday - ROEL GRONHEID
ADVANCED OPTICAL LITHOGRAPHY

State-of-the-Art Lithography

• The Continuous Trend of Miniaturization in Integrated
  Circuit Manufacturing. ITRS Roadmap
• The Importance of Lithography as Enabling Technology
• Evolution of the Exposure Tools Towards Advanced Step and Scan Systems

Theory of Optical Imaging

• The Principle of Image Formation in the Optical Lithography Process
• Formation of Aerial Image by Means of Current Projection Tools
• Performance Parameters: Depth of focus, exposure latitude, E-D windows
• Focus and Exposure Dose Budgets

Resist Chemistry

• Chemistry and Processing of I-Line Resists
• Chemically Amplified Resists for 248nm and Beyond
• Environmental Stability: T-top formation, line-width variation
• Possible Solutions to Overcome Problems: Improved chemistry, interfacing of track and stepper, chemically filtered air

Practical Resist Implementation Issues

• Contributions to CD Variation Due to Bulk Effect, Reflective Notching, Swing Curve and Standing Waves Correlated to the Optical Parameters of the Resist
• Advanced Resist Technologies: Addition of dyes, top-and bottom anti reflective coatings, dry development, top surface imaging

Tuesday - ROEL GRONHEID
Advanced Optical Imaging

• Phase Shifting Masks
• Off-Axis Illumination
• Optical Proximity Correction
• Lens Aberrations

Optical Lithography Roadmap

• 157nm Lithography Roadblocks
• Immersion Lithography Status and Challenges
• Double Patterning Techniques

Wednesday am - ROEL GRONHEID
Extreme UV Lithography, EUVL
Mainstream optical lithography is ultimately limited by diffraction and, since some time, shorter wavelength alternatives have been pursued to prepare for post-optical applications. EUVL is being developed for the 22nm or smaller generations. It is currently the most favoured of the emerging lithography options for volume manufacturing due, in part, to its extendibility beyond the 22nm half pitch node without loss in throughput. The CD entry-point, commercial infrastructure, and tool availability are described. The worldwide efforts in EUVL will be summarized.

• Description of EUVL and Overview of Worldwide Efforts
• Status and Challenges of EUV Sources, EUV Optics, EUV
• Masks and EUV Resist

Wednesday pm - HANS PFEIFFER
ELECTRON-BEAM LITHOGRAPHY, MASK-MAKING
Electron beam lithography has been pursued for many years as a means to achieve higher pattern feature resolution, needed for the advancing miniaturization, and to generate integrated circuit patterns without the need for masks. This pattern generation capability, in combination with high resolution, has also made electron beams the technology of choice for mask making.
This lecture provides a comprehensive knowledge of recent advances in electron beam lithography based on an in-depth understanding of the challenges and opportunities in charged particle optics. We present the physics factors limiting throughput and compare the various techniques developed to overcome these limitations. A specific focus is on massively parallel pixel exposure, which has been achieved with Electron beam Projection Lithography (EPL) and which is currently being developed for Maskless Lithography (ML2).The advantages of using advanced electron beam tools, in a mix and match lithography with optical tools, will be presented.

Introduction

• Competitive Position/ITRS Roadmap
• Basic Electron Optics
• Coulomb Interaction Limitations
• Challenges and Opportunities

State-of-the-Art of Various E-Beam Techniques

• Gaussian Beam, Shaped Beam, Character, Cell, Block Exposure
• Multi-Beams, Multi-Columns, and Multi-Emitters
• Electron-beam Projection Lithography (EPL)
• Progress and Recent Results with EPL

Thursday am - HANS PFEIFFER
Maskless Lithography (ML2)

• Direct Write Experience
• Review of Worldwide ML2 Activities
• Progress in Projection Maskless Lithography (PML2)
• Issues and Prospects

E-Beam Mask-Making

• Mask-Making Trends and Challenges
• Electron Beam Pattern Generators in Photomask Production

Thursday pm - CHRISTOPH HOHLE

• E-Beam Resist Processing
  -Resist types and tonalities
  -Electron-resist interactions
  -Differences to optical resists (e.g. vacuum effects)

• Proximity Effect Correction (PEC)
  -Point Spread Function (PSF)
  -Dose & geometrical correction

• E-Beam Integration into optical litho flow
  -Alignment / Overlay
  -Mix&Match integration

• Application Examples
  -Device Engineering
  -Rapid Prototyping
  -Imprint Template Manufacturing

Friday - STELLA PANG
IMPRINT LITHOGRAPHY
Since the mid-90th, Nano Imprint Lithography (NIL) has become an emerging lithographic technology that promises high throughput patterning of nanostructures on large areas. Based on the mechanical embossing principle of a polymer, NIL can achieve pattern resolutions beyond the limitations set by the light diffractions or beam scatterings in other conventional techniques. It has been recently demonstrated that it was possible to achieve sub-10nm resolution and alignment with NIL, and large area pattern fidelity. This technology allows for the creation of devices and microsystems with nanometer features at higher rate and lower cost than possible in today's high resolution patterning techniques. NIL has been applied to fabrication of various devices, including patterned magnetic disk, microoptics, compact disk, micro-fluidics, biomedical and Micro-Electro-Mechanical System (MEMS) devices, and field-effect transistors.

• Principles of Imprint Lithography: Hot embossing, microcontact printing, step and flash, and reversal imprint technologies
• Nanoimprint Systems
• Fabrication of Imprint Stamps (hard and soft)
• Adhesive Properties of the Molds: Issues and solutions
• Process Issues: Large area, high resolution, defects
• 3D nanostructures by NIL
• Applications in Electronic, Photonic, Storage, Sensor, and Biomedical devices and systems

Said about the course from previous participants:
"Great overview to sort known pieces of the whole puzzle. Comparison of advantages and disadvantages of the different techniques."
"Close contact with the teachers, their openness and expertise."
" Presentation of latest results, good balance between fundamental physical concepts and achievements of lithography companies."