As memory device packaging moves toward die stacking technology with thin chips of high density, wafer dicing has recently become a key factor in semiconductor yield. Stealth dicing technology, which produces laser irradiation inside the wafer to form a modified layer within the wafer without any damage to the surface, is an alternative and advanced dicing process that is in line with the future trend of thin wafers. The existing stealth dicing process that utilizes an ultrashort pulse laser is expensive. In this study, we proposed a low-cost method for wafer stealth dicing using quasi-continuous wave (QCW) lasers. We redesigned the focusing lens of a QCW metal-cutting laser machine to form a cutting head with a high numerical aperture (NA) that is suitable for wafer stealth dicing. An optothermal model used to simulate the dicing process and calculate the temperature was implemented numerically based on the Crank–Nicolson algorithm and the successive over-relaxation method. Both the simulation and experimental results demonstrate that a QCW laser machine with a high-NA focus lens is ideal for wafer stealth dicing.
We present the results of the ab initio calculated electronic properties, first and second harmonic generation for
the AII BIV N2 (AII=Be, Mg; BIV =C, Si, Ge) compounds with chalcopyrite structure performed using the Linear
Augmented Slater-Type Orbitals (LASTO) method. The second-order optical susceptibilities as functions of
frequency for AII BIV N2 are also presented. Specifically, we study the relation between the structural properties
and the optical responses. Our electronic band structure and density of states (PDOS) analysis reveal that the
underestimate bandgaps of these chalcopyrite AIIBIV N2 are wide enough (from 4eV to 6eV), direct transition
and mainly located at Γ-point. Calcultion results show this new category wide-bandgap ternary nitrides has
potential applications in optoelectronics.
We discuss a method for the recording of multiple images in a photorefractive LiNbO3 crystal which needs only a
single object beam without any reference beam. The object beam is modulated by a lenticular lens array sheet to produce
a set of sub-object beams. These beams are angularly separated on the recording plane but are made to overlap by light
scattered light by the photorefractive LiNbO3 crystal. The result is that only a single beam is needed to record multiple
holograms. Experimental results show that four holograms can be stored in a photorefractive LiNbO3:Fe crystal 30 mm
X 30 mm X 1 mm in size at the same time. The proposed method makes it especially simple to produce one-beam
write/read multiple holograms.
A systematic first-principles calculation of the linear and second-order optical susceptibilities as functions of
frequency for CsGeBr3 is presented. Specifically, we study the relation between the structural properties and
the optical responses. Three structural deformation factors, Δα, dGe, dX are used to express the degree of
distortion from the ideal perovskite structure in bond angle, Ge position, and anion position, respectively. Based
on our first-Principles studies, we find that Δα and dGe increase, while dX decreases as we substitute the
halogen ion from Cl to Br and then to I. The dielectric function and the second harmonic generation coefficient
are also found to increase with increasing Δα and dGe. Our calculation indicates that the direct bandgap, Eg,
of CsGeX3 occurs at the R-point for all three compounds, and its magnitude decreases as Δα and dGe increase
(i.e. Eg(CsGeI3) < Eg(CsGeBr3) < Eg(CsGeCl3)). Our partial density of states (PDOS) analysis reveals
that the valence band maximun (VBM) and conduction band minimum (CBM) are mainly associated with the
p-orbitals of Germanium. Interband and intraband analysed results for (formula available in manuscript) in CsGeBr3 can be separated into
two main groups of peaks. One was contributed from the magnitude electronic bandgap; the other part was
recognized to be attribution from the distortional structural factors. The magnitudes of (formula available in manuscript) were in the same
manner with some reported experiment near the band gap.
In this work we present a single exposure method for recording multiple holograms in reflection holography. In this
novel method, the input pattern is a segmented image composed of alternating slices of several original images and
modulated by a lenticular lens array sheet. A set of object beams can be produced simultaneously, which are angularly
separated on the recording plane and overlap one reference beam at the same time. Therefore, only one exposure is
needed for holographic recording multiple holograms. Experimental results show that a lenticular lens array sheet placed
as a modulator in the path of the object beam provides a simple yet effective ingredient of creating multiple images for
single-exposure holography. The proposed method is especially useful for one-step write/read multiple holograms and
for stereoscopic display applications.
We propose a new holographic memory scheme based on random phase-encoded multiplexing in a photorefractive LiNbO3:Fe crystal. Experimental results show that rotating a diffuser placed as a random phase modulator in the path of the reference beam provides a simple yet effective method of increasing the holographic storage capabilities of the crystal. Combining this rotational multiplexing with angular multiplexing offers further advantages. Storage capabilities can be optimized by using a post-image random phase plate in the path of the object beam. The technique is applied to a triple phase-encoded optical security system that takes advantage of the high angular selectivity of the angular-rotational multiplexing components.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.