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1
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- Richard Sun, Peter Hou and Frank Luo
- Angstrom Sun Technologies Inc., Acton, MA
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2
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- To evaluate the difference in thickness and refraction index between
inside and outside via-holes in micro electromechanical system (MEMS).
- To provide guideline for optical system design
- To provide tooling factors for processing control and thus
- To achieve the designed film thickness, desired refraction index and
satisfied device performance
- In this study, we start to evaluate and understand the deposition
difference inside and outside via-holes for single layer films such as
SiO2 and TiO2. Based on real requirements, a
method was developed to quality bottom mirror and thus control the
device performance.
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3
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4
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5
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6
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7
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8
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9
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10
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11
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12
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13
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14
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15
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16
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17
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- Non destructive optical approach, spectroscopic ellipsometry and microspectrophotometry,
were applied to study the thickness difference inside and outside
via-holes and thus used for device quality controls.
- It has been found that there are significant difference between SiO2
film and TiO2 films and thus with different tooling factors
for different films, which is important to perform valid optical
designs.
- The characteristic band position shift is ideal method to monitor the
mirror quality and thus device performance.
- The cross section inspection on various samples including mirror
structures confirmed the results with optical tools.
- Therefore, combined ellipsometry and microspectrophotometry make it
possible to characterize geometry effect on thickness and optical
properties of films deposited inside and outside via-holes or other
patterned device.
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Notes
