Overview of Semiconductor Technologies Key Semiconductor Technologies: - Bulk silicon, SOI, III-V and II-VI semiconductors Economic Impacts of Semiconductor Industry Comparison of SIA Technology Road Map

Economic Impact of Semiconductor Industry Global S.I. growth rate at 15%/year reaching $140 B in 97. This could reach to $300 B by early 2000 due to the strong demand of communications equipment and computers. S.I. growth holds down inflation: S.I. price index: -4.5%/yr vs. +3%/yr for the rest of economy. Higher wages and lower inflation. Faster technology diffusion (25%): Auto:60 yrs, Tel:35, TV:25, PC:13, Internet:< 10 yrs. Drivers of semiconductor market growth: declining prices and increasing performance: price/DRAM bit reduced by 25 to 30%/yr, while IC complexity double every 18 months (Moore’s Law). Less’s Law: improvements in reliability have accompanied increases in chip complexity:transistors/die increases from 2x10 3 in 1971 to 1.5x10 8 in 2003.

Current Status, Issues, and Trends in Semiconductor Technologies Bulk Silicon Technologies: - Scaled down submicron VLSIs - Larger wafer size, 8, 10, 12”.. - Copper interconnects Silicon-On-Insulator (SOI) technologies: - SIMOX and wafer bonding (WB). - low power, low voltage, high-speed, and high density ULSIs. 3- D IC’s III-V Semiconductor Technologies. - LEDs, LDs, detectors, MESFETS, HBTs, HEMTs, quantum effect devices (QWIPs). - p hotovoltaic devices (solar cells) technology - wi de band gap and high temperature devices ( InGaN, GaN, AlGaN, SiC, diamond)

Comparison of the World Semiconductor Industry

Comparison of SIA Technology Node Introduction Projections in 94 vs ’ Roadmap ”Roadmap Min feature(  m) Lithography248nm248/193193EUVEUV? DRAM bits/chip 256M1G4G16G64G  P xstrs/chip28M64M150M350M800M  P xstrs/cm 2 7M13M25M50M90M New Materials for the New Millennium: Cu- metallization replaces Al-Cu interconnects for Si IC’s. New dielectric materials such as Ta 2 O 5, BaSrTiO 3 are being investigated to replace SiO 2, Si 3 N 4 to handle the increase of DRAM density. New SOI technology to replace bulk Si technology for higher packing density, higher speed and lower power consumption.

Technology Road Map for Semiconductors

Delay Time vs. Power Dissipation for CMOS and Other Devices

Exponential Increase of DRAM Density vs. Year (Based on SIA Road Map)

Microprocessor Computational Power vs. Year

Silicon-On-Insulator (SOI) Technologies Separation by Implantation of Oxygen (SIMOX) Process. Wafer Bonding (WB) Process. SIMOX WB Process. Zone Melting Recrystallization (ZMR) Process Epitaxial Lateral Overgrowth (ELO) Process Fully Isolation of Porous Silicon (FIPOS) Process

Photovoltaic (PV) Market Analysis PV Market Growth Rate: Solar cell module production average increase: 14% per year 90-97, and production jumped by 38% in 1997 to 122 MW p. Growth rate is expected to increase at a rate of 20%/year over the next 15 years with potential annual module shipments of around 1,600 MW p (about $3billions per year by 2010) in the year PV Markets: - consumer electronic products (14%): calculators, watches, and lanterns... - off-grid residential power systems (35%): cottages, rural village homes.. - off-grid industrial power system (33%) : telecom.repeaters.. - off-grid connected PV systems(18%):government and/or utility demons.

Key PV Technologies Single crystal Si solar cells. Poly Si solar cells. a- Si thin film solar cells. Ribbon Si solar cells. CdTe thin film solar cells. CIS (CuInSe) thin film solar cells. III-V semiconductor (GaAs, InP, GaInP..) solar cells - single and multi-junction solar cells Concentrator solar cells.

III-V Semiconductor Technologies High-speed, high-frequency, quantum effect, and optoelectronic devices: - HBTs, HEMTs, MESFETs. - Quantum dot, quantum wire, and quantum well infrared photodetectors and lasers. Superlattice heterostructure devices - LEDs, LDs, solar cells. III-V materials: - GaAs/AlGaAs, InGaAs/GaAs, InGaAs/AlGaAs grown on GaAs - InGaAs/InAlAs, InGaAsP/InP grown on InP - InP, InAs, InSb, InGaSb, GaInN, GaN, AlN

II-VI and Wide Band Gap Semiconductors II-VI semiconductors: - ZnSe, ZnS, CdS, CdTe: Solar cells, LEDs, LDs - HgCdTe, CdZnTe, PbSnTe. Wide Band Gap Semiconductors: ( 2.5 < E g < 6.5 eV) - Diamond, SiC, AlN, GaN, AlGaN: high-temperature transistors (HBTs, MESFETS..), high- power devices, UV detectors and laser diodes.

A Bright Future for Blue/Green LEDs (Highly luminous III-V nitride based LEDs) ColorWavelength (nm) Violet< 430 Blue (GaN,InGaN/AlGaN LEDs) Green (InGaN/AlGaN or ZnSe, GaP LED) Yellow (AlInGaP LEDs) Orange Red > 630 (AlGaAs LEDs)

Chapter 1 Classification of Solids The Crystal Systems and Bravais Lattices. The Crystal Structure and The Unit Cell. Miller Indices and Crystal Planes. The Reciprocal Lattice and Brillouin Zone. Types of Crystal Bindings Defects in Crystalline Solids

Classification of Solids Based on geometrical aspects: - 7 crystal systems and 14 Bravais lattices Based on binding energy: - metallic, ionic, covalent, and molecular crystals Na, K; NaCl; C, Si, Ge; Ar, He, Ne Based on electrical conductivity: metals, semiconductors, insulators. - metals :  > 10 4 ; semiconductors: <  < 10 4 ; insulators:  < (ohm-cm) -1 Based on atomic arrangements (periodicity): - single crystalline solids: atomic arrangements are ordered with periocity extending through the entire crystal lattice. - polycrystalline solids: short range ordered within grain and separated by grain boundaries. - amorphous solids: no short range ordered, atomic arrangements are highly irregular. (glass, oxides,…)

Bravais Lattices Seven lattice systems and fourteen Bravais lattices Triclinicb 1  b 2  b 3 simple      Monoclinic b 1  b 2  b 3 simple, base-centered  =  = 90 o   Orthorhombic b 1  b 2  b 3 simple, base-centered  =  =  = 90 o  body-centered; F.C.C Tetragonal b 1 = b 2  b 3 simple, body-centered  =  =  = 90 o Trigonal b 1 = b 2 = b 3 simple,  =  =   90 o Hexagonal b 1 = b 2  b 3 simple,  =  = 90 o,   Cubic b 1 = b 2 = b 3 simple, body-centered  =  =  = 90 o F. C. C.

Unit Cell of a Bravais Lattice

The Bravais Lattice A space lattice is a concept introduced first by Bravais, and hence the Bravais lattice. The various arrangements of unit cells in a crystalline solid can be achieved by means of space lattice. A parallelepiped unit cell of a Bravais lattice is formed by 3 non-coplanar basis vectors b 1, b 2,, and b 3 with different lengths and angles between them. There are 14 Bravais lattices in space lattice as shown in Fig.1.1. A unit cell formed by 3 non-coplanar primitive basis vectors with lattice points only located in the vertices of the parallelepiped unit cell is called primitive cell. The translational basis vector can be used to generated any lattice points in the space lattice, which can be described by: - r (n 1, n 2, n 3 ) = r(0, 0, 0) + R where R = n 1 b 1 + n 2 b 2 + n 3 b 3 ; n 1, n 2, n 3 = 0, 1, 2, 3……

The Crystal Structure The crystal structure is formed by attaching an atom or a group of atoms to the lattice point of a Bravais lattice. Figure 1.3 (a) shows a 2-D space lattice, and Fig.1.3(b) shows a 2-D crystal structure with atoms attached to each lattice point. Four important crystal structures for semiconductors are shown in Fig.1.4. These are: (a) diamond structure (Si, Ge, GaAs), (b) Zinc-blende structure (III-V, II-VI semiconductors), (c)Wurtzite (III-V, II-VI), and (d) hexagonal closed-packed (HCP) structure.

Miller Indices The orientation of a crystal plane can be determined by 3 integers, h, k, l, known as the Miller indices, which are defined by: hh’ = kk’ = ll’(1) where h’, k’, l’, represent the intercepts of a particular plane on the three crystal axes (x,y.z) in units of lattice constant a. h, k, l, are the three smallest integers that satisfy eq.(1). Example: if h’, k’, l’ = a, 2a, 2a, then the smallest h, k, l that satisfy eq.(1) is (2,1,1), and the plane is called (211) plane.

Reciprocal Lattices and Brillouin Zone The reciprocal lattice is a geometrical construction which allows one to relate the crystal geometry directly to the electronic states and the symmetry properties of a crystal in the reciprocal space. It’s the Fourier transform of the direct (space) lattice in the reciprocal space, which can be expressed as: exp(iK.R) = 1 where: K = hb 1 * + kb 2 * + lb 3 * ; R = n 1 b 1 + n 2 b 2 +n 3 b 3 R.K = 2  (n 1 h+n 2 k+n 3 l) = 2  In a reciprocal lattice, a set of reciprocal basis vectors b * 1, b * 2, b * 3 can be defined in terms of the three translational basis vectors b 1, b 2, b 3 in the direct space: b * 1 = 2  (b 2 xb 3 )/|b 1.b 2 xb 3 | V d = |b 1.b 2 xb 3 | b * 2 = 2  (b 2 xb 3 )/|b 1.b 2 xb 3 | b * 3 = 2  (b 2 xb 3 )/|b 1.b 2 xb 3 | V r * = |b 1 *.b 2 * xb 3 * | = 8  3 /V d