Introduction to Lithography

Driven by the US CHIPS and Science Act, there is a strong surge of interest in semiconductors in general and specifically in semiconductor manufacturing. Nanolithography is the key technology that enables the patterning of nanometer-scale device structures onto silicon wafers. This course is intended primarily for students that are targeting one of the Purdue Semiconductor Degrees. It will provide a comprehensive introduction into diffraction-based imaging, the technology and subsystems of the lithographic equipment, the metrology and process control strategies being employed in high-volume manufacturing. This course is the first in a set of three courses focused on nanolithography. The second course will cover topics from EUV Lithography, the technology used for today's most advanced semiconductor devices. The third course will cover topics in Computational Lithography, essential technology for robust imaging near to the resolution limit.

ECE59500

Credit Hours:

1

Learning Objective:

 A student who successfully fulfills the course requirements will have demonstrated an ability to:

  • Explain the fundamental role that nanolithography plays in the manufacturing of complexity of modern integrated circuits (manufacturing process, layer characteristics for logic and memory devices, associated lithography challenges)
  • Describe the role, functioning, and critical performance parameters of the subsystems involved in pattern transfer from mast to wafer (illumination, mask, projection optics, wafer and resist)
  • Compute resolution limits for practical lithographic use cases using theory of diffraction-based image formation (principles of Fourier optics, near-field versus far-field image formation, role of illumination optimization, resolution calculations, impact of aberrations)
  • Describe the functioning of both scanner and wafer metrology, the physical principles behind the measurements involved, and the role they play in manufacturing control ( alignment, leveling, critical dimensions, overlay, advanced process control)
  • Describe the key innovations and challenges involved in narrow-band, immersion, and EUV lithography without any help (light source, optics, mask, computational tools)

Description:

This course is the first in a series of three courses on nanolithography. This introductory course will provide a broad overview of this exciting field. Students will learn about 1) the critical role of lithography in semiconductor manufacturing, 2) the fundamentals of diffraction-based imaging, 3) the system architecture of the major subsystems of modern exposure tools, 4) in-scanner and on-wafer metrology and control loops for the ultimate performance in process control, 5) the essential role that Digital Twins and Computational Lithography play in advancing the state-of-the-art quickly.

Topics Covered:

The course will run for 8 weeks and consist of four major modules: 

  1. The Basics
  2. Diffraction-based Imaging
  3. Metrology is Key
  4. Digital Twins

Prerequisites:

The course focuses on conceptual understanding more than of teaching specific techniques. Knowledge of Fourier Analysis is quite essential to grasp diffraction-based imaging as well as many of the metrology concepts that will be discussed.

Applied / Theory:

70% / 30%

Homework:

There will be a homework assignment associated with each of the four modules. In addition, there will be group assignments where the emphasis will be on active participation and constructive collaboration 

Projects:

First project will involve picking an integrated circuit of interest to the student. The student will be asked to describe and explain a) why the IC is of interest, b) the unique features of this IC are that embody that interest, c) specific manufacturing challenges associated with these features and how they are being addressed. 

Exams:

No proctored final exam.

Web Address:

https://purdue.brightspace.com

 

Textbooks:

Required Text:

  1. Principles of Lithography (will be provided as a free download), 4th Edition, Harry J. Levinson, SPIE Press

Recommended Text:

None