Characterization of Low Temperature, Wafer-Level Gold-Gold Thermocompression Bonds

1999 ◽  
Vol 605 ◽  
Author(s):  
Christine H. Tsau ◽  
Martin A. Schmidt ◽  
S. Mark Spearing
Keyword(s):  
Low Temperature ◽  
Strain Energy Release ◽  
Constant Load ◽  
Moderate Pressure ◽  
Cohesive Failure ◽  
Wafer Level ◽  
Simultaneous Application ◽  
Mems Packaging ◽  
Thermocompression Bonding ◽  
Die Bonding

AbstractLow temperature, wafer-level bonding offers several advantages in MEMS packaging, such as device protection during aggressive processing/handling and the possibility of vacuum sealing. Although thermocompression bonding can be achieved with a variety of metals, gold is often preferred because of its acceptance in die bonding [1] and its resistance to oxidation. This study demonstrates that the simultaneous application of moderate pressure (0.5 MPa) and temperature (300°C) produces strong wafer-level bonds. A four-point benddelamination technique was utilized to quantify bond toughness. Test specimens exhibited constant load versus displacement behavior during steady state crack propagation. Two distinct fracture modes were observed: cohesive failure within the Au and adhesive failure at the Ti-Si interface. The strain energy release rate for Au-Au fracture was found to be higher than that associated with Ti-Si fracture, consistent with the greater plastic deformation that occurs in the metal during fracture.

Influence of Macro- and Nanotopography, Thin Film Thermomechanical Behavior and Process Parameters on the Stability of Thermocompression Bonding.

2004 ◽  
Vol 854 ◽  
Author(s):  
Konstantinos Stamoulis ◽  
S. Mark Spearing
Keyword(s):  
Thin Film ◽  
Process Parameters ◽  
Strain Energy Release ◽  
Wafer Level ◽  
Bond Quality ◽  
Bond Yield ◽  
Thermocompression Bonding ◽  
Simple Contact ◽  
Point Bend ◽  
The Stability

ABSTRACTThe quality of wafer-level, gold thermocompression bonds is critically dependent on the interaction between the wafer topography, the thin film properties, the process parameters and tooling used to achieve the bonds. This study presents mechanics modeling of the effect of wafer topography. An analytical expression for the strain energy release rate associated with the elastic deformation required to overcome wafer bow is developed. Furthermore, a simple contact yielding criterion is used to examine the pressure and temperature conditions required to flatten nano-scale asperities in order to achieve bonding over the full apparent area. The analytical results combined with experimental data for the interface bond toughness obtained from four-point bend testing indicate that the overall wafer shape is a negligible contributor to bond quality. A micro-scale bond characterization based on microscopic observations and AFM measurements show that the bond yield is increased with increasing bond pressure.

Low-temperature Cu-Cu thermocompression bonding for encapsulation of a MEMS mirror

2019 ◽  
Vol 2019 (NOR) ◽  
pp. 000012-000016
Author(s):  
Henri Ailas ◽  
Jaakko Saarilahti ◽  
Tuomas Pensala ◽  
Jyrki Kiihamäki
Keyword(s):  
Low Temperature ◽  
Bond Strength ◽  
Bonding Temperature ◽  
Bonding Process ◽  
Ex Situ ◽  
High Yield ◽  
Maximum Temperature ◽  
Wafer Level ◽  
Cu Films ◽  
Thermocompression Bonding

Abstract In this study, a low temperature wafer-level packaging process aimed for encapsulating MEMS mirrors was developed. The glass cap wafer used in the package has an antireflective (AR) coating that limits the maximum temperature of the bonding process to 250°C. Copper thermocompression was used as copper has a high self-diffusivity and the native oxidation on copper surfaces can be completely removed with combination of ex situ acetic acid wet-etch and in situ forming gas anneal. Making it suitable for a development of a low temperature bonding process. In this work, bonding on of sputtered and electrodeposited copper films was studied on temperatures ranging from 200°C to 300°C as well as the effect of pretreatment on bond strength. The study presents a successful thermocompression bonding process for sputtered Cu films at a low temperature of 200°C with high yield of 97 % after dicing. The bond strength was recorded to be 75 MPa, well above the MIL-STD-883E standard (METHOD 2019.5) rejection limit of 6.08 MPa. The high dicing yield and bond strength suggest that the thermocompression bonding could be possible even at temperatures below 200°C. However, the minimum bonding temperature was not yet determined in this study.

scholarly journals Low-Temperature Al-Al Thermocompression Bonding with Sn Oxidation Protect Layer for Wafer-Level Hermetic Sealing

2017 ◽  
Vol 100 (8) ◽  
pp. 43-50
Author(s):  
SHIRO SATOH ◽  
HIDEYUKI FUKUSHI ◽  
MASAYOSHI ESASHI ◽  
SHUJI TANAKA
Keyword(s):  
Low Temperature ◽  
Wafer Level ◽  
Hermetic Sealing ◽  
Thermocompression Bonding

Wafer Level Hermetic Packaging for RF-MEMS Devices Using Electroplated Gold Layers

2006 ◽  
Vol 326-328 ◽  
pp. 617-620
Author(s):  
Gil Soo Park ◽  
Ji Hyuk Yu ◽  
Sang Won Seo ◽  
Woo Beom Choi ◽  
Kyeong Kap Paek ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Rf Mems ◽  
Gold Films ◽  
Mems Devices ◽  
Wafer Level ◽  
Promising Technique ◽  
Hermetic Packaging ◽  
Thermocompression Bonding ◽  
Via Hole

Thermocompression bonding of electroplated gold is a promising technique for achieving low temperature, wafer level hermetic bonding without the application of an electric field or high temperature. Silicon wafers were completely bonded at 320 at a pressure of 2.5. The interconnection between the packaged devices and external terminal did not need metal filling and was made by gold films deposited on the sidewall of the via-hole. In the hermeticity test, packaged wafers had the leak rate of 2.74 ± 0.61 × 10-11 Pa m3/s. In the result of application in packaging of FBAR filter, the insertion loss is increased from -0.75dB to -1.09dB at 1.9.

Locally Heated Low Temperature Wafer Level MEMS Packaging With Closed-Loop AuSn Solder-Lines

2002 ◽  
Author(s):  
Young Ho Seo ◽  
Tae Goo Kang ◽  
Young-Ho Cho ◽  
Seong-A. Kim ◽  
Geun Ho Kim ◽  
...  
Keyword(s):  
Low Temperature ◽  
Closed Loop ◽  
Applied Pressure ◽  
High Strength ◽  
Wafer Level ◽  
Mems Packaging ◽  
Bonded Interface ◽  
Heated Specimen ◽  
Internal Volume ◽  
Bonding Method

In this paper, locally heated closed-loop AuSn solder-line bonding method was proposed and evaluated for a low-temperature, high strength, and hermetic MEMS packaging. We fabricated two different test specimens including substrate-heated specimen and locally heated specimen in order to verify the performance of locally heated method. In air tightness test, the substrate-heated specimen and locally heated specimen show the maximum leak rate of 13.5±9.8×10−10mbar-l/s and 18.8±9.9×10−10mbar-l/s with the same internal volume of 6.89±0.2×10−6l, respectively. In the critical pressure test, any fracture was not found in the bonded specimens at applied pressure of 10±2bar. From these results, we approximately extracted the bonding strength of the proposed bonding process of 3.53±0.07MPa. By EDS (Energy Dispersive X-ray Spectrometer) analysis at bonded interface, we found that bonded interface (between AuSn solder and Ti/Au layer) of substrate-heated specimen was stronger than that of locally heated specimen.

Sign in / Sign up

Export Citation Format

Share Document