A NOVE LOW-TEMPERATURE MICROCAP PACKAGING USING SU-8 BONDING Y.K. Kim, S.W. Kim, and B.K. Ju

1
A NOVE LOW-TEMPERATURE MICROCAP PACKAGING USING
SU-8 BONDING Y.K. Kim, S.W. Kim, and B.K. Ju

• Korea ,Chungju National,Chungju and
  University,KOREA
• Tranducer 2007
• ??? ???

2
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

3
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

4
Motivation

• MEMS packaging is much more expensive, heavy and
  large than in case of integrated circuits
  packaging.
• MEMS often reaches more than 70 of the total
  cost of the microsystem.
• Higher temperature may damage metallization
  layers and cause considerable stress in the
  bonded materials.

5
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

6
Structure Design
A cavity with desired thickness is formed for cap
structure by using KOH wet etching. Dimensions
of the microcap are determined such that the
width and the length are 800 and 1100um.
7
Material Properties
The proposed packaging method used the polymer
as a cap structure and the intermediate adhesive
layer.
YK Kim, SH Yi, SW Kim, BK Ju, A Novel
Low-Temperature Microcap Packaging Using SU-8
Bonding,2007.
8
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

9
Packaging process
KOH at 80?(70um)
Bonding by heating and pressure
Silicon oxide(8um) SU-8 spin coated Exposure and
bake(95?)
Via holes by DRIE Gold by electroplating
Cu deposited
10
SU-8 photoresist process

• The finally optimized recipes of SU-8 photoresist
  are shown in under table.

YK Kim, SH Yi, SW Kim, BK Ju, A Novel
Low-Temperature Microcap Packaging Using SU-8
Bonding,2007.
11
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

12
Bonding Strength
The bonding strength of the bonded pair for
various bonding temperatures was measured by pull
testing. Fig. shows the tensile test curves under
different bonding temperatures. The maximum
strength is 15.7 MPa at 120?.
YK Kim, SH Yi, SW Kim, BK Ju, A Novel
Low-Temperature Microcap Packaging Using SU-8
Bonding,2007.
13
Packaging Results
The thickness of the microcap and cavity were
50um and 30um. Polymers are by far more permeable
to gas and moisture than ceramics or metal
sealants. They investigated sputtering copper
films(1um) as a diffusion barrier.
YK Kim, SH Yi, SW Kim, BK Ju, A Novel
Low-Temperature Microcap Packaging Using SU-8
Bonding,2007.
14
Outline

• Motivation
• Packaging Design
• Fabrication Process
• Experimental Details And Results
• Conclusion
• References

15
Conclusion

• This method provides a simple process, easy
  assembly and low temperature processing.
• The optimal bonding temperature was 120?.
• SU-8 adhesive bonding shows a strong bonding
  tensile strength about 7-17MPa.

16
References

• YK Kim, SH Yi, SW Kim, BK Ju, A Novel
  Low-Temperature Microcap Packaging Using SU-8
  Bonding, Actuators and Microsystems Conference
  pp. 2107 2110, 2007.
• A. R. Mirza, wafer-level packaging technology
  for MEMS, The 7th IEEE Intersoc. ConF. Thermal
  and Thermomechanical Phenomena in Electronic
  Systems., vol. 2, pp. 113-119, 2000.
• F. Niklaus, P.Enoksson, E. Kalvesten, G. Stemme,
  Low temperature full wafer adhesive bonding of
  structured wafers, J. Micromech. Microeng. Vol.
  11 pp. 100-107, 2001.