Low Temperature Wafer Bonding Process Using Sol-Gel Intermediate Layer

2004 ◽  
Author(s):  
S. S. Deng ◽  
J. Wei ◽  
C. M. Tan ◽  
W. B. Yu ◽  
S. M. L. Nai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Bond Strength ◽  
Silicon Wafer ◽  
Process Parameters ◽  
Wafer Bonding ◽  
Intermediate Layer ◽  
Bonding Temperature ◽  
Sol Gel ◽  
Dominant Factor ◽  
Bond Quality

Silicon-to-silicon wafer bonding has been successful prepared using sol-gel intermediate layer, which is deposited by spinning acid catalyzed tetraethylthosilicate (TEOS) solution on both two silicon wafer surfaces. To investigate the effects of the process parameters, Draper-Lin small composite design is used, as it requires the minimum runs in the design of experiments. Four process parameters, bonding temperature, solution PH value, solution concentration and solution aging time, have been considered to influence the bond quality, including bond efficiency and bond strength. The bond efficiency is in the range of 40%–90% and bond strength is up to 35 MPa. Statistic analysis shows that the bonding temperature is the dominant factor for the bond quality, while the interaction between temperature and concentration is significant on bond strength. Various characterization techniques, including differential thermal analysis (DTA), atomic force microscopy (AFM), scanning electron microscope (SEM), contact angle measurement and ellipsometry, have been used to study the surface and interface properties. The residual organic species inside the sol-gel coating may be the origin of the significant effect of bonding temperature on the bond efficiency. The interaction effect on bond strength is attributed to the surface hydrophilicity and porosity of sol-gel coating. Higher concentration solution can form lower hydrophilic wafer surface, which results in lower bond strength when bonding temperature is at low level. Whereas, at high bonding temperatures, the increase of porosity of the sol-gel coating prepared by higher sol concentration can absorb more undesired hydrocarbon gas molecules and lead to higher bond strength. The bonding mechanism for the low temperature sol-gel intermediate layer bonding technique is related to the smooth coating surface, porous intermediate layer and water-absent bonding groups.

Sol-Gel Coating Facilitating Si-to-Si Wafer Bonding at Low Temperature

2005 ◽  
Author(s):  
J. Wei ◽  
S. S. Deng ◽  
C. M. Tan
Keyword(s):  
Low Temperature ◽  
Bond Strength ◽  
Wafer Bonding ◽  
Intermediate Layer ◽  
Bonding Temperature ◽  
Sol Gel ◽  
Bond Quality ◽  
Bubble Generation ◽  
High Bond ◽  
High Bond Strength

Silicon-to-silicon wafer bonding by sol-gel intermediate layer has been performed using acid-catalyzed tetraethylthosilicate-ethanol-water sol solution. High bond strength near to the fracture strength of bulk silicon is obtained at low temperature, for example 100°C. However, The bond efficiency and bond strength of this intermediate layer bonding sharply decrease when the bonding temperature increases to elevated temperature, such as 300 °C. The degradation of bond quality is found to be related to the decomposition of residual organic species at elevated bonding temperature. The bubble generation and the mechanism of the high bond strength at low temperature are exploited.

Low-temperature sol–gel intermediate layer wafer bonding

2006 ◽  
Vol 496 (2) ◽  
pp. 560-565 ◽  
Author(s):  
S.S. Deng ◽  
C.M. Tan ◽  
J. Wei ◽  
W.B. Yu ◽  
S.M.L. Nai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Wafer Bonding ◽  
Intermediate Layer ◽  
Sol Gel

LOW TEMPERATURE SILICON WAFER BONDING BY SOL-GEL PROCESSING

2003 ◽  
Vol 04 (03) ◽  
pp. 655-658 ◽  
Author(s):  
S. S. DENG ◽  
J. WEI ◽  
C. M. TAN ◽  
M. L. NAI ◽  
W. B. YU ◽  
...  
Keyword(s):  
Low Temperature ◽  
Silicon Wafer ◽  
Wafer Bonding ◽  
Sol Gel ◽  
Gel Processing

Mechanism of sol–gel intermediate layer low temperature wafer bonding

2005 ◽  
Vol 38 (8) ◽  
pp. 1308-1312 ◽  
Author(s):  
C M Tan ◽  
S S Deng ◽  
J Wei ◽  
W B Yu
Keyword(s):  
Low Temperature ◽  
Wafer Bonding ◽  
Intermediate Layer ◽  
Sol Gel

Low Temperature Direct Silicon Wafer Bonding Using Argon Activation

1997 ◽  
Vol 36 (Part 2, No. 5A) ◽  
pp. L527-L528 ◽  
Author(s):  
Robert W. Bower ◽  
Frank Y.-J. Chin
Keyword(s):  
Low Temperature ◽  
Silicon Wafer ◽  
Wafer Bonding

Low Temperature Wafer Level Bonding Using Benzocyclobutene Adhesive Polymers

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 1-24
Author(s):  
Michael Gallagher ◽  
Jong-Uk Kim ◽  
Eric Huenger ◽  
Kai Zoschke ◽  
Christina Lopper ◽  
...  
Keyword(s):  
Low Temperature ◽  
Wafer Bonding ◽  
Flip Chip ◽  
Bonding Temperature ◽  
Bonding Process ◽  
Curing Temperature ◽  
Wafer Level ◽  
Mechanical Adhesion ◽  
3D Stacking ◽  
Dry Etch

3D stacking, one of the 3D integration technologies using through silicon vias (TSVs), is considered as a desirable 3D solution due to its cost effectiveness and matured technical background. For successful 3D stacking, precisely controlled bonding of the two substrates is necessary, so that various methods and materials have been developed over the last decade. Wafer bonding using polymeric adhesives has advantages. Surface roughness, which is critical in direct bonding and metal-to-metal bonding, is not a significant issue, as the organic adhesive can smooth out the unevenness during bonding process. Moreover, bonding of good quality can be obtained using relatively low bonding pressure and low bonding temperature. Benzocyclobutene (BCB) polymers have been commonly used as bonding adhesives due to their relatively low curing temperature (~250 °C), very low water uptake (<0.2%), excellent planarizing capability, and good affinity to Cu metal lines. In this study, we present wafer bonding with BCB at various conditions. In particular, bonding experiments are performed at low temperature range (180 °C ~ 210 °C), which results in partially cured state. In order to examine the effectiveness of the low temperature process, the mechanical (adhesion) strength and dimensional changes are measured after bonding, and compared with the values of the fully cured state. Two different BCB polymers, dry-etch type and photo type, are examined. Dry etch BCB is proper for full-area bonding, as it has low degree of cure and therefore less viscosity. Photo-BCB has advantages when a pattern (frame or via open) is to be structured on the film, since it is photoimageable (negative tone), and its moderate viscosity enables the film to sustain the patterns during the wafer bonding process. The effect of edge beads at the wafer rim area and the soft cure (before bonding) conditions on the bonding quality are also studied. Alan/Rey ok move from Flip Chip and Wafer Level Packaging 1-6-12.

Low Temperature Anodic Bonding for MEMS Applications

2002 ◽  
Author(s):  
J. Wei ◽  
Z. P. Wang ◽  
L. Wang ◽  
G. Y. Li ◽  
Z. Q. Mo
Keyword(s):  
Low Temperature ◽  
Bonding Strength ◽  
Transition Period ◽  
Bonding Temperature ◽  
Testing Machine ◽  
Acoustic Microscopy ◽  
Anodic Bonding ◽  
Dominant Factor ◽  
Glass Wafer ◽  
Bonding Parameters

In this paper, anodic bonding between silicon wafer and glass wafer (Pyrex 7740) has been successfully achieved at low temperature. The bonding strength is measured using a tensile testing machine. The interfaces are examined and analyzed by scanning acoustic microscopy (SAM), scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). Prior to bonding, the wafers are cleaned in RCA solutions, and the surfaces become hydrophilic. The effects of the bonding parameters, such as bonding temperature, voltage, bonding time and vacuum condition, on bonding quality are investigated using Taguchi method, and the feasibility of bonding silicon and glass wafers at low temperature is explored. The bonding temperature used ranges from 200 °C to 300 °C. The sensitivity of the bonding parameters is analyzed and it is found that the bonding temperature is the dominant factor for the bonding process. Therefore, the effects of bonding temperature are investigated in detail. High temperatures cause high ion mobility and bonding current density, resulting in the short transition period to the equilibrium state. Almost bubble-free interfaces have been obtained. The bonded area increases with increasing the bonding temperature. The unbonded area is less than 1.5% within the whole wafer for bonding temperature between 200 °C to 300 °C. The bonding strength is higher than 10 MPa, and increases with the bonding temperature. Fracture mainly occurs inside the glass wafer other than in the interface when the bonding temperature is higher than 225 °C. SIMS results show that the chemical bonds of Si-O form in the interface. Higher bonding temperature results in more oxygen migration to the interface and more Si-O bonds. The bonding mechanisms consist of hydrogen bonding and Si-O chemical reaction.

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