IC Industry Awards Winners
Award Materials - Improvement
System Cool Glass - Hermetic Borosilicate Thin-Film
Company MSG Lithoglas AG
Hermetic Borosilicate Thin Film
Borosilicate glass is well known for its chemical
inert behaviour and stability. It is temperature
stable and hardly dissolves in most acids, bases
and solvents. It is the close-to-perfect material
for semiconductor packaging in respect to its
electrical, chemical and physical properties.
Through being successful in special
applications like anodic bonding or glass-to-
metal seals, the use of glass for mainstream
packaging of semiconductors was limited by
lacking CMOS process compatibility and other
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manufacturing limitations.
MSG Lithoglas AG has developed and
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implemented a deposition and structuring
.eur technology, enabling the production of
oasiasemiconductor
microstructured borosilicate glass thin-films with
a thickness of 100 nm to 30 µm on a variety of
substrates at temperatures below 100 °C.
The deposition of the glass is done by a allows for processing of thin-film glass for a large
plasma-assisted e-beam evaporation process. It variety of other applications incl. Ge, InP, SiC,
is a high rate deposition process with at the LiNbO3, Borofloat or Pyrex, HTCC or LTCC
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same time low substrates temperature. With the substrates or even flexible substrates.
high deposition rate typical film thicknesses of 3 The combination of a low temperature
– 10 µm can be achieved easily and production deposition process with the excellent properties
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Issue VII 2009
can be run as a cost effective batch process. of glass being hermetic, chemically stable and
Thicker layers as thick as 100 µm have been robust enables a unique and revolutionary
demonstrated in R&D. solution for the passivation of semiconductors or
They have proven to exhibit low stress in other sensitive devices.
the deposited layers and leverage from their The Lithoglas process is a unique approach
thermal expansion being matched to silicon. The bring wafer-level-packaging to a new level of
glass layer can be microstructured by lift-off. reliability. It has the potential to replace
Since the deposition process is working at low polymers in harsh environment applications and
temperatures standard photo resists can be used to expand the conditions of use for low cost
for masking. electronics.
As a mainstream application the glass thin- The cost-effective, CMOS compatible
films are used for passivation of opto- process can act as a drop-in replacement of CVD
semiconductors on Si or GaAs easily meeting or polymer passivation leveraging from existing
harsh environment reliability requirements e.g. infrastructure ensuring excellent and stable
for automotive or space applications. manufacturability.
The high-volume Lithoglas process is The technology approach is new and
CMOS-Backend compatible and runs e.g. on inventive, matching the requirements of
SEMI standard silicon device wafer, but also advanced wafer-level packaging.
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