Hochschule Kempten      
Fakultät Elektrotechnik      
Microelectronics       Fachgebiet Elektronik, Prof. Vollrath      


02 History

Prof. Dr. Jörg Vollrath

01 Introduction

Video of lecture 03 24.03.2021

Länge: 1:02:33 min
0:0:54 Transistor, Layout, Cross Section

0:4:5 Transistor count

0:9:5 Moore's Law: Feature Size

0:13:0 Microelectronics over time

0:16:20 iFixit iPhone Analysis

0:18:5 iPhone Main Board

0:19:40 Blessing and Curse of Microelectronics

0:22:48 Design Entry

0:27:5 Software Tools

0:28:35 Integrated Circuit Challenges

0:29:55 Laboratory: Build a 4 bit positive number multiplier

0:32:43 Hierarchical description, one solution

0:36:40 Citations: Don't optimize too early.

0:39:19 Design flow

0:43:25 Technologies

0:47:15 Inverter schematic

0:49:45 Truth table

0:51:13 Source drain, schematic, color, layout box

0:54:5 Stick diagram

0:56:13 What do I do with 1 billion transistors?

0:57:32 Inverter schematic and layout

1:2:5 p-well and n-well

1:5:57 p-well and n-well contact

1:8:31 Layout well contact

1:12:45 F and lambda

1:13:29 N-MOSFET equations

1:16:16 β, width W, length L, capacitance Cox

1:22:4 0

Review and Overview

Transistor Evolution

Nachbau des ersten Transistors
Quelle: Wikimedia 1947 Bell
1 Bipolar transistor
30 μ m

50 MHz

Courtesy of Intel
2008 Intel Core i7
731 Million MOS Transistors
45 nm process
263 mm2
2.6..3.2 GHz

It can be seen that the Intel Core i7 has 731 million transistors in a process using 45nm feature size on an area of 263 mm2. As an critical thinking engineer it is important to be able to check statements, claims and facts.
In this example the number of transistors for the given chip area is checked. A single transistor needs a minimum size of 16 F2 as seen before. The number of transistors is chip area (AChip) divided by transistor area (AMOSFET).
263 mm2/(16 * (45nm)2) = 8117 Mio Transistors.
This is a factor of 11 higher than the claimed 731 million transistors.
In highly integrated chips the total size is not limited by the area of transistors, but by the area needed for contacts and wiring.
In a microprocessor one transistor needs around 180 F2. This number is important for estimation of chip area for a given circuit with a given number of transistors.


History of integrating microelectronic circuits

Electronic components


Moore's Law: Transistor count

Transistor Count and Moore's Law - 2011
Every 2 years the number of transistors per area doubles.
Each year manufacturing productivity gains are about 30%.

Moore's Law: Feature size

Comparison semiconductor process nodes

Microelectronics over time



Mobile phone components

iPhone 3 GS Teardown
Source: iFixit CC BY-NC-SA 3.0

Mobile phone main board

iPhone 3 GS Teardown
Source: iFixit CC BY-NC-SA 3.0
Samsung ARM processor S5PC100 600MHz

16 GB of Toshiba NAND flash memory
NOR Pseudo SRAM Numonyx

Analog Broadcom, Infineon

Power Management Infineon, NXP

Blessing and curse of microelectronics

Design and manufacturing
Curse (Challenge):

MOSFET Transistor

Quelle Vollrath
Quelle Vollrath
TechnologyRNRP COXVthn VDD IDDgmmax gdmaxft Model
1 μm15kΩL/W45kΩL/W 1.75fF WL/F21V 5V 3 mA cmosedu_models N_1um
600 nm ΩL/WΩL/W fF WL/F2 V mA C5_models
50 nm 34kΩ/W68kΩ/W 62.5aF WL/F20.3 V 1 V mA cmosedu_models N_50nm


A MOSFET (Metal oxide semiconductor field effect transistor) has the terminals gate (G), source(S), drain(D) and bulk(B). The gate controls current flowing between source and drain. There is a threshold voltage Vth which is needed to enable current flow. A bulk potential and bulk connection can change threshold voltage. Therefore bulk connections are needed to guarantee a stable threshold voltage.
There are enhancement mode PFETs and NFETS available making CMOS (complementary MOS) circuits possible. Enhancement mode FETS have a threshold voltage so that no current is flowing with 0V between source and gate.
NFETs have a positive threshold voltage, PFETS have a negative threshold voltage.

Transistor representation

Transistors as electrical components can be small black boxes with 3..4 wires. They are represented in a schematic as a symbol. In microelectronics a transistor is represented by a red rectangle (polysilicon) crossing a green rectangle (diffusion). Connections betweeen different colored areas are represented by black boxes between overlapping colored rectangles. Metal lines for connections are drawn as blue, violet or pink boxes.
In microelectronics circuits are built by transfering a transistor schematic to a layout (colored shapes). There are design rules limiting the size and distance of these colored boxes due to the limitations of the manufacturing process.

Minimum feature size and transistor area

The minimum total area of a transistor is based on the minimum feature size F.
The minimum feature size is the smallest pattern which can be realized in a given manufacturing process. The minimum feature size is depending on the wavelength of the used light source for the photoprocess used to transfer patterns with a mask onto the photoresist on a chip. A MOSFET uses at least 3 connections with minimum square area of F2. Since there should be no shorts a distance to the next feature should also has a minimum distance of 1 F. Therefore 3 connections and one active transistor area, where a red and green line are crossing, with isolation require:
4 * 4 F2 = 16 F2


Design Entry



Graphical State machine




Result: Integrated Circuit

Courtesy of Intel

Integrated Circuit Challenges

Lecture and Laboratory

2021 Build a 4 bit postive number multiplier

Next: LTSPICE and Electric

Circuit simulator: LTSPICE

Layout tool: Electric

03 MOSFET transistor