Download 1. VLSI Overview

1. VLSI Overview
Hiroaki Kunieda
Dept. of Communications and
Computer Engineering
Tokyo Institute of Technology
Outline
1.
2.
3.
4.
2
What is VLSI ?
Classification
Current Industry
Design Hierarchy
1.1 VLSI
1. What is VLSI ?

Circuit System implemented on the
surface of semiconductor, consisting of




Transistors (MOS or bipolar tr.)
connecting wires
One chip consists of 10 Million Gates or
40 Million Transistors in one circuit.
Performance is decided not only by


Circuit configuration
Placement of transistors and connection schemes of connecting wires
SoC (System_on_Chip) Example
SoC layout
process
0.18um
CMOS/6M1P
package
360 TFBGA
Power
supply
3.3V (I/O),
1.8V(core)
RISC
speed
200MHz
SRAM
32KB
ROM
64KB
SoC die
size
5mm x 5mm
Soc gate
count
1400K
Manufacturing on Wafer
Wafer


A series of identical chips are
patterned onto the Wafer.
Some space is reserved for
test circuit structures.
Example of Process
1)
2)
3)
4)
Put tubs into wafer.
Form an oxide
covering on wafer
and the polysilicon
wires.
Diffusion (wires)
(polysilicon masks
the formation of
diffusion wires.=selfaligned)
Metal connections are
made with filling cuts
(via) to make
connections after
another oxide layer is
deposited.
Wiring Processes
Example of Complex Layout
1.2 Classification
Manufacture
1.Monolithic LSI
Made of one semiconductor
1.1 Silicon LSI
Silicon is used as substrate.
1.1.1 MOS LSI
MOS technology such as MOS transistors are
employed.l
1.1.1.1
CMOS LSI
nMOS and pMOS are used to reduce power
consumption.
1.1.1.2
NMOS LSI
nMOS (Enhancement and Depletion Types) are
used for smaller area.
1.1.2 Bipolar LSI
1.2 GaAs LSI
2. Hybrid LSI
High speed is achieved, but complicated
fabrication process, suitable for Analog LSI.
Semiconductor is used for high frequency use.
Semiconductor chip and other components on
thin film substrate.
Design Method



Standard Design --------- Design by maker’s spec.
Full Custom Design ------ Design of all masks by customer’s spec.
 Manual Design
 Cell-Based Design
 Custom Cell/ Full Custom Design
 Standard Cell Design
Semi Custom Design ----- Design of routing wire & logic functions
by customer’s spec.


Gate Array
FPGA Design
Structure of LSI
Wire
Wire
Wire
gate
Source
Wire
gate
Drain
pMOS
Silicon Substrate (n)
Sorce
Drain
ｎMOS
P-Well
1.3 Semiconductor
Industry
Size of Industry (2006)
Automobile
700 B$
Semiconductor
28 B$
Microprocessor
DRAM, flashROM
SoC
Analog, Discrete
Digital
Consumer
Electronics
350 B$
PC
3２0 B$
Cellular
Phone
140 B$
Growth Forecast
Growth Rate (%)
20
■NAND FlashROM
15 ■sensor
10
■DSP
■MCU
5
0
0
10
■Analog
■MPU
■DRAM
20
30
■
specific logic
40
Market
50 B$
Moore’s Law and Intel
microprocessors
The transistor counts would double every
18 months.
microprocessor
Date of
introduction
#transistors
Feature size
(microns)
80286
1982.02
134,000
1.5
80386
1985.10
275,000
1.5
80486
1989.04
1,200,000
1.0
Pentium
1993.03
3,100,000
0.8
Pentium pro
1995.11
5,500,000
0.6
Pentium II
1997
9,500,000
0.25
Pentium III
2001
42,000,000
0.18
Dual Core
2008
0.065
1.4 Design Hierarchy
Design Partitioning
• Architecture: User.s perspective, what does it do?
• Instruction set, registers
• MIPS, x86, Alpha, PIC, ARM, .
• Micro architecture
• Single cycle, multcycle, pipelined, superscalar?
• Logic: how are functional blocks constructed
• Ripple carry, carry lookahead, carry select adders
• Circuit: how are transistors used
•Complementary CMOS, pass transistors, domino
• Physical: chip layout
•Datapaths, memories, random logic
Microprocessor
Execution
Unit
Control
Unit
registers
DRAM (Main Memory)
ＣＰＵ
① fetch instruction from main memory and send it to
control unit
② control unit gets instruction and control execution units
and registers to execute command of instructions.
③ Data are manipulated according to commands
① send data from registers (source) to execution units
② execution has been performed by execution units
③ results is sent to register (destination)
Micro operations
• Micro operations are performed by one clock
corresponding to register transfer logic.
• Processor works according to instructions (machine
codes), which are a sequence of micro operations.
•As an example, ADD instruction is performed as
1. ADD instruction is transferred from memory to inside.
2. the data is sent to Instruction Register.
3. the instruction is decoded and its information is sent to
control execution.
4. the required data for addition is transferred from
specified register to execution units such as ALU.
5. ALU executes addition.
6. the result is sent to the destination register.
ＲＴＬ
Load_A
Register
A
Register
B
A
B
ALU
Load_C
clock
S
Register
C
Load_B
ALU
(Arithmetic and Logic Units)
A
B
ALU
S
＋）
A ００１１
B １０１０
Ｓ １１０１
３
１０
１３
ALU performs arithmetic and logic operations
for 2 input data as A and B and to produce
the result S.
Operations are specified by control signals.
1 bit Adder
a
b
D
carry_out
0
1
0
head
D
sum
D
head_out
Master-Slave Flip Flop
rst
clk
~clk
D
Q
~clk
~clk
clk
clk
clk
~clk
Clocked Inverter
~clk
~clk
IN
IN
OUT
clk
clk
Operation of Transister
High Voltage Input
Switch ON
Low Voltage Input
Switch OFF
Layout Pattern of LSI
Silicon Substrate
Gate
wiring
Gate
wiring
Ｄｅｓｉｇｎ Ｍｅｔｒｉｃｓ
Cost (chip area)
Reliability (design margin
Scalability (expansion to larger system)
Speed (delay, operating frequency)
Power dissipation (Heat problem, battery Drive)
Energy to perform a function