SSL Seminar Series 2003 No.1
Combined talks (three speakers)
Date: May 9, 2003
Venue: Physics Resource Room (Blk S13 # 02-16)
Speaker I: Mr. Siddharth Joshi
Title: Hydrophilic Surface Induced Nano-patterning of di-block
In recent years, nano-patterned (NP) surfaces of polymers have
become a subject of intense study in both experimental and theoretical
physics. The vast technological applications of patterned surfaces
in nano-circuits, nano-wires, sensors as well as biomedical tools
have drawn enormous scientific attention. Parallel to this, we also
embark on NP based research specifically on interactions between
block copolymers (BC) and surface of a substrate that are governed
by their physical and chemical properties. We would like to establish
the surface characterization methodologies for NP organic surfaces.
Firstly, we exploit surface sensitive spectroscopy tools such as
Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy
(XPS) and Surface Plasmon Resonance Spectroscopy (SPR) techniques.
Importantly, we propose a new surface, Self Assembled Monolayer
(SAM) of COOH-C15SH thiol/Au(111)/Mica to generate a patterned polymer
layer. Formation of NP surface is based on surface induced nano-phase
separation of di-block copolymers (DBC), poly styrene-block-2-polyvinylpyridine
(PS-b-P2VP) and poly-styrene-block-4-polyvinylpyridine (PS-b-P4VP)
as listed in Table 1(a). The intrinsic properties of the two blocks
will eventually lead to a phase separation. In addition, different
chemical affinity of each block with COOH-C15SH thiol adsorbed onto
an Au(111)/Mica surface will also enhance the formation of nano-patterns.
The di-block copolymers exhibited two types of surface-induced NP
(worms and dot/islands) due to their different compositions of block's
molecular weight. Table 1(b) lists the dimensions of these patterns
on SAM of COOH-C15SH thiol/Au(111)/ mica.
Speaker II: Mr. Ab Razak Chanbasha
Title: Ultra-low Energy Secondary Ion Mass Spectrometry
Downsizing in microelectronics has generated the need for ultra-shallow
junctions (< 40nm). At this depth, however, it becomes difficult
to provide accurate depth profile of the dopants, as the surface
transient effects of SIMS coincides. Improved depth resolution is
also necessary for better thin-film and interfacial profiling. These
analysis are possible with ultra-low energy SIMS.
In this work, we will study the characteristics of ultra-low energy
SIMS using O2+ and Cs+ ion beams at various incidence angles. Having
understood this, we will attempt to optimize analytical techniques
for accurate profiling and quantitation of B, As & SiON in Silicon.
In this presentation, we will highlight work done using O2+, below
1keV and at angles of incidence form 0o to 70o. Observations made
on surface transient effects, sputter rates and depth resolution
will be described.
Speaker III: Mr. Liu Rong
Title: High Depth Resolution Secondary Ion Mass Spectrometry
Following the increasingly stringent requirements in the characterization
of sub-micron IC devices, a good understanding of the various factors
affecting ultra shallow depth profiling in secondary ion mass spectrometry
(SIMS) has become crucial. Achieving high depth resolution (of the
order of 1 nm) is critical in the semiconductor industry today,
and various methods have been developed to optimize depth resolution.
In this work, we will discuss ultra shallow SIMS depth profiling
using B and Ge delta-doped Si samples using low energy (e.g. 500
eV) O2+ primary beams. The relationship between depth resolution
of the delta layers and surface topography measured by atomic force
microscopy (AFM) is studied. The technique of oxygen flooding and
sample rotation, used to suppress surface roughening is also investigated.
The various factors that limit the depth resolution in ultra shallow
SIMS depth profiling are discussed.