PROPETIES OF MMIC

(A)The basic material for MMIC in general are subdivided  into four categories

(1) Subtract material: alumina,beryllia,ferrite,Gas retile & sapphire

(2) Conductor material:- aluminum,copper,gold&silver

(3) Dielectric Films: Al₂O_3, sio,sio₂ , si₃N₄ and ta₂

(4) Resistive Film:- cr, cr- Sio Nicr Ta and Ti 

MATERIAL	Tan Φ x 104 At 10 ghz	Relative Dielectric Constant	Thermal conductivity	Application
Alumina	2	10	0.3	Micro strip suspended substrate
Beryllia	1	6	2.5	Compound substrated
Ferrite	2	13-16	.03	Microstripe Coplanar substrate
gaAs	16	13	0.03	High frequency Microstrip MIC
Glass	4	5	0.01	Lumped element
Rutile	4	100	0.02	Microstrip
Sapphire	1	9.3-11.7	0.4	microstrip

Substrate material: a substrate of monolithic microwave integrated circuit is a piece of substrate on which electronic devices are built. The ideal substrate materials should have the following characteristic.

(1) High dielectric constant

(2) Low dissipation factor

(3) High purity and constant thickness

(4) High surface smoothness

(5) High thermal conductivity

Conductor materials: the ideal conductor material for monolithic microwave integrated circuit should have the following properties

(1) High conductivity

(2) Low temperature coefficient

(3) Good adhesion to substrate

(4) Good solder ability

MMIC FABRICATION PROCESS

MMIC FABRICATION PROCESS

FLOW CHART

ION IMPLATATION

MESA ISOLATION

OHMIC CONTACT

GATE FORMATION

RESISTORBDEPOSITION

DIELECTRIC DEPOSITION

SECOND LEVEL METAL

VIA HOLE AND BACKSIDE PLATING

MMIC FABRICATION TECHNIQUE

MMIC  FABRICATION  TECHNIQUES

1.       Doping techniques

2.       Epitaxial grouth

3.       Lithography

4.       Etching

5.       Metalfilm deposition

6.       Oxidation

7.       Filom deposition                           

Doping techniques:

Diffussion and ion implitation are two main techniques

1.diffussion techniques

The process of diffussion consist of diffussing impurities into a pure metal in order to aleter the basic electronic characteristics of pure metal.

2.ion imlation is process introduction of high enrgy charged’

dopant atom vaporized

enerigis lie between 30 to 300

*advantage of ion implatation

-accurate control of dopant dose and implantation

-posibility of light doping

-high uniformly over wafer

-good reproductilbility

2. Epitaxial Growth

-grouth of thin crystline substarte

*three types of epitaxial process

1.vapor –phase epitaxy

2.molecular –beam epitaxy

3.liquied-phase epitaxy

3.Lithography

Transffring pattern of geometric shapes through a mask to thin layer

The exposing radiation are uv rays,electrons,x-rays,ions

-four types of lithography

1.optical lithography

2.electron beam lithography

3.ion beam lithography

4.x-ray lithography

4. Metal film deposition

Metal Films deposition can be formed by various methods like physical vapour deposotion

PVD is commonly used for making MMIC

PVD TYPES

1.Evaporation

2.sputtering

5.Oxidation

Chemical process

In film depositon chemical vapor deposition techniques is used for semiconductor processing.