Semiconductors: nano-electronic “materials” details

Semiconductors: nano-electronic “materials” details

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Description: Semiconductor Devices, know about Nano-electronic, Moore’s Law, Growth of the Semiconductor Industry, Transistors wafer to Billions wafer, evolution of the Transistor, Basic Device in CMOS Technology is the MOSFET, Microprocessor Power Consumption, 2008 Vintage Intel Microprocessor, Strained Silicon MOSFET.

 
Author: Alan Doolittle, PhD (Fellow) | Visits: 1565 | Page Views: 3148
Domain:  High Tech Category: Semiconductors Subcategory: Education 
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Contents:
ECE 3080: Semiconductor Devices
for Computer Engineering and Telecommunication Systems
"The significant problems we face cannot be solved by the same level of thinking that created them." � Albert Einstein Dr. Alan Doolittle School of Electrical and Computer Engineering p g g Georgia Institute of Technology

Intel, 45-nm CMOS "Dual Core" process technology Compared to older p Pentium processor
Note: several images in this lecture were obtained from the Intel web pages

January 5, 2011

Dr. W. Alan Doolittle

1

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor Moore's Law: The Growth of the Semiconductor Industry y
Moore's law (Gordon Moore, co-founder of Intel, 1965): Empirical rule which predicts that the number of components per chip doubles every 18-24 months Moore s Moore's Law turned out to be valid for more than 30 years (and still is!)

January 5, 2011

Dr. W. Alan Doolittle

2

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor Moore's Law: The Growth of the Semiconductor Industry
>1 Billion Transistors

2000 Transistors

January 5, 2011

Dr. W. Alan Doolittle

3

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor

Transistor functionality scales with transistor count not speed! Speed is less important. p

from G. Moore, ISSCC 2003 January 5, 2011 Dr. W. Alan Doolittle 4

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor How did we go from 4 Transistors/wafer to Billions/wafer?
IBM 200 mm and 300 mm wafer http://www-3.ibm.com/chips/photolibrary

1.5 mm

First Planar IC 1961, Fairchild http://smithsonianchips.si.edu/ p p

300 mm

January 5, 2011

Dr. W. Alan Doolittle

5

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor
Sand to Silicon � Major Historical Hurdles.

Play parts of movie on Silicon Fabrication
January 5, 2011 Dr. W. Alan Doolittle 6

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor

Slide after Dr. John Cressler
January 5, 2011 Dr. W. Alan Doolittle 7

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor
Common Statement: First Transistor was invented by Shockley, Brattain and Bardeen on December 23, 1947 at 5 PM � Wrong! The first patent for the field-effect transistor principle was filed in p p p Canada by Austrian-Hungarian physicist Julius Edgar Lilienfeld on October 22, 1925

The level of understanding you gained about transistors in ECE 3040 is 60 years old!!!! Ga T h G d t G Tech Graduates make the future happen and thus need to understand the state of k th f t h d th dt d t d th t t f the art in order to advance it.
January 5, 2011 Dr. W. Alan Doolittle 8

The Basic Device in CMOS Technology is the MOSFET h
Direction of Desired Current flow... ...is controlled by an electric field... ...but this field can also drive current through a small gate. Modern transistors have more power loss in the gate circuit than the source drain! New approaches h are needed.
January 5, 2011 Dr. W. Alan Doolittle 9

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor
Early MOSFET: SiO2 Gate Oxide, Aluminum (Al) Source/Drain/Gate metals Problem: As sizes shrank, devices became unreliable due to metallic spiking through the gate oxide. Solution: Replace Metal Gate with a heavily doped poly-silicon.

This change carried us for decades with challenges in fabrication (lithography) being the primary barriers that were overcome ...until...

January 5, 2011

Dr. W. Alan Doolittle

10

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor
Semi-Modern MOSFET (late 1990's vintage): SiO2 Gate Oxide, Polysilicon gate metals, metal source/drain contacts and Aluminum metal interconnects metals Problem: As interconnect sizes shrank, Aluminum lines became too resistive leading to slow RC time constants Solution: Replace Aluminum with multimetal contacts (TiN, TaN, etc...) and copper interconnects.

This change carried us for ~ 1 decade with challenges in fabrication (lithography) being the primary b i i barriers th t that were overcome ...until...
January 5, 2011 Dr. W. Alan Doolittle 11

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor

Microprocessor Power Consumption
Gates b G t became so thin thi that the leakage currents through the thin Gate insulator consumed more power than the drain-source circuit! Gate

A new approach is needed!
from G. Moore, ISSCC 2003

January 5, 2011

Dr. W. Alan Doolittle

12

Why do we need to know about Nano-electronic "materials" details? � A Case study of the evolution of the Transistor

from G. Moore, ISSCC 2003

Dinsulator kinsulator E V Dinsulator kinsulator Gate t Gate I Gate Leakage etGate
January 5, 2011

Gate leakage current can be dramatically lowered by increasing Gate insulator thickness but to do so without changing the channel conductivity, you have to increase the dielectric constant of the insulator. NEW GATE INSULATORS FOR THE FIRST TIME IN 60 YEARS!!!!
Dr. W. Alan Doolittle 13

2008 Vintage Intel Microprocessor

January 5, 2011

Dr. W. Alan Doolittle

14

2008 Vintage Intel Microprocessor

January 5, 2011

Dr. W. Alan Doolittle

15

2008 Vintage Intel Microprocessor

January 5, 2011

Dr. W. Alan Doolittle

16

2008 Vintage Intel Microprocessor

January 5, 2011

Dr. W. Alan Doolittle

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2008 Vintage Intel Microprocessor
45 nm (~200 atoms) HafniumSilicate (Oxide)

Strained Si (lower bandgap ( g p � higher mobility)

January 5, 2011

Dr. W. Alan Doolittle

18

2008 Vintage Intel Microprocessor
45 nm (~200 atoms) �High K Gate Dielectric: �K of SiO2~3.9< Hafnium Silicate ~? < HfO2~ 22 �Deviation from SiO2 required reverting back to Metal Gates (no Poly-silicon) �Limited Speed of Silicon partially overcome by using SiGe to "mechanically strain" Si channel resulting in Energy Band structure modification that i E B d difi i h increases electron/hole mobility. HafniumSilicate (Oxide)

Strained Si (lower bandgap � higher mobility)

January 5, 2011

Dr. W. Alan Doolittle

19

Strained Silicon MOSFET

from IEEE Spectrum, 10/2002







Silicon in channel region is strained in two dimensions by placing a Si-Ge layer underneath (or more recently adjacent to) the device layer Strained St i d Si results in changes in the energy band structure of lt i h i th b d t t f conduction and valence band, reducing lattice scattering Benefit: increased carrier mobility, increased drive current (drain current)
Dr. W. Alan Doolittle 20

Slide after Dr. Oliver Brandt January 5, 2011

What is in the future? DoubleGate Transistors






Change of basic transistor structure by introducing a double d bl gate (or more general ( l enclose the channel area by the gate) Benefit: b B fi better channel control h l l resulting in better device characteristics Challenge: double-gate Ch ll d bl transistors require completely new device structures with new fabrication challenges
from IEEE Spectrum, 10/2002 Dr. W. Alan Doolittle 21

Slide after Dr. Oliver Brandt January 5, 2011

Double-Gate Transistor Designs
Channel in chip plane Channel perpendicular to chip plane with current flow in hi l i chip plane (Fi FET) (FinFET) Channel perpendicular to chip plane with current flow perpendicular to chip plane

from IEEE Spectrum, 10/2002 Slide after Dr. Oliver Brandt January 5, 2011 Dr. W. Alan Doolittle 22

FinFET Double-Gate Transistor

from http://www.intel.com/pressroom Slide after Dr. Oliver Brandt January 5, 2011 Dr. W. Alan Doolittle 23

Vertical multi-gate structures take us back to JFET like structures but now with the advantage of insulators. � Life g is circular

January 5, 2011

Dr. W. Alan Doolittle

24

And what about Bipolar and III-V?

January 5, 2011

Dr. W. Alan Doolittle

25

Future for Compound Semiconductors is strong!!!
�InP HEMT (transistors) operate above 1THz � Northrop Grumman Inc. �InP Double Heterostructure Bipolar Transistors (DHBT) operate to as high as 865 GHz! - Milton Feng et al al. �InP Double Heterostructure Bipolar Transistors (DHBT) circuits operate to as high as 310 GHz! - HRL Inc. �Demonstration of InP Optical Transistors and Lasers that can directly integrate into fiber optic systems at 100's of GHz. � Milton Feng et al. �SiGe HBTs operate to 300 GHz (500 GHz at cryogenic temperatures) � IBM / Dr. John Cressler et al. �InSb based devices offer even more promise for low power high speed (transistor mobility of ~30,000 compared to ~100 in Si MOSFET). MOSFET) �GaN based devices offer 100x improvement in power density! SiC capability. �SiC based devices offer Megawatts switching capability �Will likely see a surge in "Hybrid Si - ??? Technologies"
January 5, 2011 Dr. W. Alan Doolittle 26

Consider LED as a Case Study of why we must know the materials technologies on the "Nano Scale"

Movie Complements of Dr. Christian Kisielowski from Lawrence Berkeley DOE Labs. Labs

January 5, 2011

Dr. W. Alan Doolittle

27

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