Study of Low-Temperature Wafer Bonding With Au-Au Bonding Technique

Kurotaki, H.; Shinohara, H.; Kobayashi, H.; Mizuno, Jun; Shoji, Shuichi

doi:10.1115/micronano2008-70064

Cited by 4 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The average bond strengths listed in Table 3 were similar to or higher than the strengths reported in earlier studies (Taklo et al 2004;Kurotaki et al 2008;Schjølberg-Henriksen et al 2012;Malik et al 2014). The large standard deviations of the fracture force distributions imply that no clear conclusion can be made regarding which of the two investigated bonding metals that resulted in the highest strength.…”

Section: Discussionsupporting

confidence: 68%

Non-destructive wafer-level bond defect identification by scanning acoustic microscopy

et al. 2014

View full text Add to dashboard Cite

Metal-based thermocompression bonding enables the creation of hermetic seals formed at relatively low processing temperatures and occupying a small portion of the device area. In the current study we have investigated the application of scanning acoustic microscopy (SAM) for assessing the quality of metal thermocompression bonds, both by evaluating its capabilities of localizing areas of poor bonding, and by finding defects in the integrity of the bond seal. Wafer laminates containing a test vehicle with pre-defined defects in the bond metal layer were sealed by Au-Au and Al-Al thermocompression bonding. Employing SAM, an area of 5 chips of poor bonding was identified non-destructively on the Al-Al laminate.Line defects of width 3.6 µm and point defects of diameter 22.4 µm have also been identified by SAM. The dicing yield for sealing frames was above 96% for all frame structures and both bond metal systems. The average bond strength was 31.5 ± 11.9 MPa for Al-Al thermocompression bonds and 37.3 ± 9.7 MPa for Au-Au thermocompression bonds.Scanning acoustic microscopy operates non-destructively and proved to be an extremely useful tool complementing current state-of-the-art methods for bond quality assessment.

show abstract

Section: Discussionsupporting

confidence: 68%

Non-destructive wafer-level bond defect identification by scanning acoustic microscopy

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Also, the mean bond strengths obtained from our laminates was higher than the previously reported bond strength of ∼20 MPa by Kurotaki et al 4 and ∼10 MPa by Taklo et al 8 Table III shows that the calculated maximum leak rate of the bonded dies was below 10 −11 mbar · l · s −1 for all laminates. The actual leak rate of the bonds may be significantly lower than the calculated 10 -11 mbar · l · s -1 range; however the accuracy of the applied detection method prevented a better estimate.…”

Section: Discussioncontrasting

confidence: 42%

“…• C. 8 Bonding of porous Au has been performed at room temperature. 9 To our knowledge, reports on the reliability and hermeticity of Au-Au thermocompression bonds have not yet been presented.…”

mentioning

confidence: 99%

Environmental Stress Testing of Wafer-Level Au-Au Thermocompression Bonds Realized at Low Temperature: Strength and Hermeticity

Malik

Tofteberg

Poppe

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

Hermeticity, reliability and strength of four laminates bonded at different temperatures by Au-Au thermocompression bonding have been investigated. Laminates with a diameter of 150 mm were realized by bonding a wafer containing membrane structures to a Si wafer with patterned bond frames. A bond tool pressure of 2266 mbar was applied for 15 minutes at temperatures ranging from 150-300 • C. The hermetic properties were estimated by membrane deflection measurements applying white-light interferometry after bonding. Reliability was tested by exposing the laminates to a steady-state life test, a thermal shock test, and a moisture resistance test. Bond strength was estimated by pull test measurements. A dicing yield above 90% was obtained for all laminates. Laminates bonded at 200 • C and above had significantly higher hermetic yield than the laminate bonded at 150 • C. No degradation in hermeticity was observed after the reliability tests. The maximum leakage rate (MLR) was estimated from two measurements of membrane deflection executed at two different times and was below 10 −11 mbar • l • s −1 . The average bond strength ranged from 44 to 175 MPa.

show abstract

“…The helium leak rate of Au-Au thermocompression bonds was measured to be 2.74×10 -11 Pa m 3 /s by Pa m 3 /s by Xu et al, indicating that high quality hermetic packaging can be realized using this technology [10,20]. As diffusion barrier and adhesion layer Cr, Ti, W, TiW and NiCr have been used [10,12,16,17,19,20].The relatively large discrepancy in the reported bonding parameters for Au-Au thermocompression bonding indicates that the process is still not fully understood and described. This paper presents an investigation of Au-Au bonding in the temperature range 350 -450 °C.…”

mentioning

confidence: 99%

“…Bonding temperatures vary from 100 to 450 °C [9,16] and bonding pressure varies from 0.5 to 120 MPa [12,17] . For many applications, a low bonding temperature is desired.…”

mentioning

confidence: 99%

Wafer-level Au–Au bonding in the 350–450 °C temperature range

Tofteberg

Schjølberg-Henriksen

Fasting

et al. 2014

J. Micromech. Microeng.

View full text Add to dashboard Cite

Abstract:Metal thermocompression bonding is a hermetic wafer-level packaging technology that facilitates vertical integration and shrinks the area used for device sealing. In this paper, Au-Au bonding at 350, 400 and 450 °C has been investigated, bonding wafers with 1 µm Au on top of 200 nm TiW. Test Si laminates with device sealing frames of width 100, 200, and 400 µm were realized. Bond strengths measured by pull tests ranged from 8-102 MPa and showed that the bond strength increased with higher bonding temperatures and decreased with increasing frame width. Effects of eutectic reactions, grain growth in the Au film and stress relaxation causing buckles in the TiW film were most pronounced at 450 °C and negligible at 350 °C. Bond temperature below the Au-Si eutectic temperature 363 °C is recommended. CONFIDENTIAL -FOR REVIEW ONLY JMM-100282.R2Wafer-level Au-Au bonding in the 350-450 °C temperature range Abstract. Metal thermocompression bonding is a hermetic wafer-level packaging technology that facilitates vertical integration and shrinks the area used for device sealing. In this paper, Au-Au bonding at 350, 400 and 450 °C has been investigated, bonding wafers with 1 µm Au on top of 200 nm TiW. Test Si laminates with device sealing frames of width 100, 200, and 400 µm were realized. Bond strengths measured by pull tests ranged from 8-102 MPa and showed that the bond strength increased with higher bonding temperatures and decreased with increasing frame width. Effects of eutectic reactions, grain growth in the Au film and stress relaxation causing buckles in the TiW film were most pronounced at 450 °C and negligible at 350 °C. Bond temperature below the Au-Si eutectic temperature 363 °C is recommended. Submitted to: Journal of Micromechanics and Microengineering IntroductionMicroelectromechanical system (MEMS) technology enables sensitive and reliable devices to be produced at low cost due to the advantages of batch processing. However, packaging of the individual devices can account for more than 70% of the device cost [1]. Wafer-level bonding lowers these costs substantially. Several bonding technologies are used in packaging of commercial MEMS devices. Glass-frit bonding [2-4], anodic bonding [5,6] and fusion bonding [7,8] are well known and widely used techniques for wafer-level packaging and sealing of MEMS devices.Recently, metal thermocompression bonding has found its application as a hermetic waferlevel packaging technology that facilitates vertical integration. Thermocompression bonding, also referred to as diffusion bonding, is a form of solid-state welding. Pressure and heat are applied simultaneously to bring two metal surfaces into close contact. The atoms can then migrate from lattice site to lattice site joining the interface together [9,10]. To enable metal-to-metal contact, the bonding mechanism must deform the two surfaces in contact in order to disrupt any intervening surface films [11].Cu, Al, and Au are the three most commonly applied metals for thermocompression bonding. The lowest proces...

show abstract

Study of Low-Temperature Wafer Bonding With Au-Au Bonding Technique

Cited by 4 publications

References 0 publications

Non-destructive wafer-level bond defect identification by scanning acoustic microscopy

Non-destructive wafer-level bond defect identification by scanning acoustic microscopy

Environmental Stress Testing of Wafer-Level Au-Au Thermocompression Bonds Realized at Low Temperature: Strength and Hermeticity

Wafer-level Au–Au bonding in the 350–450 °C temperature range

Contact Info

Product

Resources

About