光刻技术简介

16
Basic Concept
Resolution depends on wavelength and NA of optical system used
17
Driving Resolution by Wavelength
Resolution is determined by the amount of diffraction energy collected by the projection lens
Other Terms used to Describe Photolithography
masking photomasking photo lithography litho yellow room dark room
源自文库
Lithography Illustrated
Lithography: The process of transferring a circuit pattern from a reticle to the wafer.
The ability to print smaller and denser patterns by photolithography mainly depends on the optical characteristics by the optical system used in the process. Other factors such as photoresist are also critical.
Resolution is represented by Half Pitch (HP)
R(HP) = k1 λ/NA
Line, Space, Pitch
l Pitch s
p s l
20
Numerical Aperture or NA: Other component affecting resolution
First, make smaller features on the reticle (mask). To some extends, the reticle features are so small that they will not be transferred onto the Si with reasonable fidelity. This is the limit of Resolution.
Resolution – Use half pitch to represent smallest feature that can be printed. See next slide for more information. DOF 19
Depth of focus. The range in which the image is acceptable.
Photolithography is at the Center of the Wafer Fabrication Process
Thin Films
Polish
Patterned wafer
Diffusion
Photo
Etch
Test/Sort
Implant
*
4
What else is Photolithography?
April 2008 Rev1
Outline
¾ Introduction ¾ Basic photolithography concept ¾ Lithography process technology ¾ Litho metrology and monitors ¾ Process flow through litho ¾ Way to the future?
3-dimensional circuit patterning Most critical step in IC process
• •
Determines feature resolution Determines overlay accuracy
Bottleneck in the fab process The leading technology
8
Photolithography -- Definitions
Photolithography is used to produce 3-D images using light sensitive photoresist and controlled exposure to light.
Microlithography is the technique used to print ultra-miniature patterns -- used primarily in the semiconductor industry.
• • • •
Understand the importance of lithography technology in semiconductor industry Understand major elements of litho process technology Introduce key terminology Comprehend the engineering and operational challenges faced by litho
Opaque
Reticle (mask) Photoresist Layer to be patterned Silicon
Clear
13
Patterning process overview
Etch and Litho are the two functional areas involved in the patterning process
14
Importance of Resolution and Overlay Registration
VSS Vin VDD
Top view of Transistor
s
g
d
s
g
d
Vout p-channel transistor n-channel transistor
polysilicon gate
2005 2010
Quad Core Itanium™ 2 Processor
Source: http://www.intel.com/technology/mooreslaw/ 6
Moore’s Law – How to realize it?
Print ever smaller patterns on Si through photo lithography:
Cramming more components onto integrated circuits, Gordon Moore, Electronics Magazine, Vol.38, No.8, Apr 19, 1965
5
Moore’s Law - 2008
Transistors Per Die
2
Outline
¾ Introduction ¾ Basic photolithography concept ¾ Lithography process technology ¾ Litho metrology and Monitors ¾ Process flow through Litho ¾ Way to future?
3
Introduction
This session provides an overview of the Lithography (Litho) functional area. More detailed reference material is listed at the end of this presentation for those who wish to read further. Intent
1G 2G
1010 109 108 107 106 105 104 103 102 101 100
1960 1965 1970 1975 1980 1985 1990 1995 2000
1K
512M Dual Core Itanium™ 2 Processor 256M 128M Itanium™ 2 Processor 64M Itanium™ Processor 16M Pentium® 4 Processor 4M Pentium® III Processor 1M Pentium® II Processor 256K Pentium® Processor 64K 486™ Processor 16K 386™ Processor 4K 80286 8080 8086 8008 1965 Data (Moore) 4004 Memory Microprocessor
metal
contact
field oxide
p+ source
p+ drain n-substrate
n+ n+ source drain p-well
Cross-section of Transistor
gate oxide
How to print smaller features with photo lithography?
18
Resolution Limits
Resolution = k1 DOF = k1
Definitions: λ– The wavelength used in the optical system
λ
NA
= k1
λ
n sin θ
λ
NA
2
= k1
λ
(n sin θ ) 2
NA – Numerical Aperture. Bigger NA means more light information could path through and be printed on the wafer. See coming slide. K1 – Everything else.
Shrink
Shrink
Shrink
Shrink
Shrink
Shrink
Shrink
Shrink
7
Outline
¾ Introduction ¾ Basic photolithography concept ¾ Lithography process technology ¾ Litho metrology and Monitors ¾ Process flow through Litho ¾ Way to future?
Quad Core Itanium™ 2 Processor: World’s first 2-billion transistor chip (2008)
Exponential ExponentialGrowth Growthin inTransistor TransistorDensity Density
Introduction to Lithography
Disclaimer 1: This training material is intended to provide generic semiconductor industry knowledge, and contains no specific or proprietary information from any company, including Intel. Disclaimer 2: Names, brands, trademarks cited in this presentation are properties of respective companies.
4
Moore’s Law – Guiding principle for the Semiconductor industry
Intel co-founder Gordon Moore is a visionary. In 1965, his prediction, popularly known as Moore's Law, states that the number of transistors on a chip will double about every two years.