Measurement of bonding energy in an anhydrous nitrogen atmosphere and its application to silicon direct bonding technology

Fournel, Frank; Continni, Léonardo; Morales, Christophe; Fonseca, Jeremy Da; Moriceau, H.; Rieutord, F.; Barthelemy, A.; Radu, Ionut

doi:10.1063/1.4716030

Cited by 64 publications

(55 citation statements)

References 31 publications

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“…• C. Noteworthy, as shown also in our previous work, 8 Lawn's WSC equation 2 of Zone II for instance can be applied on the direct bonding crack opening phenomenon. where η is the number of absorbed molecules per active site, a 0 the distance between two absorption sites, l the mean free path of water vapor, m the water molecule mass, p H20 the water partial pressure and E the Young's modulus.…”

Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

“…In this study, we use the El-Zein's formula after having calculated the real bonding length using also El-Zein's beam equation. 8,27 After the adhesion energy measurement, the adherence or bonding energy could be measured simply by moving the blade inside the bonding to induce a classical debonded length.…”

Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

“…[3][4][5][6][7][8][9] In order to obtain the real bonding energy value, the measurement has to be done in anhydrous atmosphere. 8 Indeed as soon as siloxane bonds significantly appear at the bonding interface, during the blade insertion in humid atmosphere, the water corrodes them and the debonding length increases, reducing the apparent bonding energy. After the blade stops, the system simply follows the v(K) or v(G) curve of Figure 1a from the right to the left as explained also by Masteika et al…”

Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

“…The direct bonding energy measurement or the strain energy release rate, G, using the double cantilever (DCB) beam technique is for instance highly affected by the water stress corrosion. [3][4][5][6][7][8][9] In addition to the direct bonding energy measurement, this DCB technique is also very interesting to improve the direct bonding mechanism understanding. Indeed, as the water stress corrosion only appears with siloxane bonds, it could be an interesting characterization of the classical silicon direct bonding reaction 1:…”

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confidence: 99%

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Water Stress Corrosion in Bonded Structures

Fournel

Martin-Cocher

Radisson

et al. 2015

ECS J. Solid State Sci. Technol.

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Direct bonding is now a well-known technique to join two flat surfaces without any additional material. This technique is used in many applications and especially in SOI (Silicon-On-Insulator) elaboration or in some backside imager manufacturing processes which are now almost in mass production. Direct bonding mechanism study is then very important in order to clearly understand this bonding behavior. Especially in the case of silicon or silicon dioxide hydrophilic surface, the role of water is essential. Water could lead to lots of different reactions at the bonding interface and especially the water stress corrosion could play an important role in the direct bonding mechanism.

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Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

Section: Direct Bonding Siloxane Bondsmentioning

confidence: 99%

mentioning

confidence: 99%

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Water Stress Corrosion in Bonded Structures

Fournel

Martin-Cocher

Radisson

et al. 2015

ECS J. Solid State Sci. Technol.

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“…After the blade insertion, we measured the debonded length (i.e., the crack propagation length, L) using the IR imaging system within 30 s to avoid the effects of humid atmosphere on the surface energy as much as possible. 17 Fig . 3a shows the IR image of the crack-opening method for full bonded wafer.…”

Section: Methodsmentioning

confidence: 99%

Mechanisms for Room-Temperature Fluorine Containing Plasma Activated Bonding

Wang

Liu

et al. 2017

ECS J. Solid State Sci. Technol.

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Room-temperature direct bonding is an attractive approach to combine dissimilar wafers avoiding any thermal stress by a difference of thermal expansion coefficients. In this paper, we investigate a room-temperature bonding process using fluorine containing plasma activation and propose a mechanism model to address the roles of fluorine. Details of the plasma treated surface and the bonding interface are characterized. Experimental results show that fluorinated oxide formed on the silicon surface results in a lower bonding strength at the initial bonding step before the storage. On the other hand, during storage at room temperature, fluorinated oxide asperity might be more easily softened by the interfacial water enabling a significant bonding strength enhancement. As a result, strong bonding strength of Si/Si wafer pairs, very close to the fracture energy of bulk silicon, is achieved after storage in air for 24 h, even at room temperature. Room-temperature wafer direct bonding is a state-of-the-art technique that allows wafers to be bonded at room temperature (RT, ∼25• C) without employing heat, and therefore is highly desirable to avoid temperature-related problems for many applications.1-3 To achieve a robust bonding at RT, surface treatments are performed prior to bonding, e.g., plasma activation, 4-6 wet chemistry, 7 or combination of these processes. 8 Among them, by introducing fluorine (F) into oxide layers before bonding, a hydrofluoric (HF) acid treatment has been found to enhance the bonding strengths of silicon or/and silicon oxide wafers at RT.9,10 Very strong bonding strength (also represented by "surface energy") of SiO 2 /SiO 2 , equivalent to the silicon fracture energy (∼2.5 J/m 2 ), has been realized after storage at RT for 60 h.11 Because oxide layers can be easily deposited on non-silicon materials, e.g., using thermal oxidation or chemical vapor deposition (CVD), the fluorine-enhanced oxide-to-oxide bonding process offers bonding of multiple wafers with same or different coefficients of thermal expansion (CTE) for plenty of uses. 12In contrast to produce fluorinated layers by wet chemistry, our group has developed a fluorine containing plasma activated bonding process.13 By introducing a small amount of carbon tetrafluoride (CF 4 ) into oxygen plasma, strong bonding between Si or/and SiO 2 wafers has been achieved even at RT. Moreover, void formation at the bonding interfaces could be mitigated effectively during the subsequent annealing process.14 The fluorination process by plasma surface treatments has been further simplified without requiring a fluorinated gas in recent years.15 However, the physical and chemical mechanisms enabling RT wafer bonding are still poorly understood. In this paper, we focus on characterizations of the fluorine containing plasma treated surfaces as well as the bonding interfaces. The bonding parameters are optimized, such as CF 4 gas ratio, RT storage time and storage environments. Moreover, the roles of fluorine are addressed. Based on the experimental finding...

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Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer

Takeuchi

Matsumoto³

et al. 2021

Adv Materials Inter

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applications, the glass bonding should not deteriorate the transparency at the interface for efficient light transmission. Moreover, voids at the bonding interface are obstacles as they lead to a topical decrease in transparency. For these reasons, the indirect bonding of glass using adhesive including epoxy and UV-curing resins is not appropriate since the adhesive layer deteriorates the optical characteristics and the sealing performance especially against water permeation. Hence, a direct glass bonding is highly required for the fabrication of reliable applications. The direct bonding of glass has been studied for a long time. One popular method is hydrophilic bonding, in which the glass surfaces are treated to achieve OH groups, followed by the post-bonding annealing at over 600 °C to achieve covalent bonds between the glass surfaces. In this method, the OH groups and water on the bonding surfaces are decomposed and the generated H 2 diffuses into the amorphous structure of glass (2Si-OH  →  Si-O-Si + H 2 O, Si + 2H 2 O  →  SiO 2 + 2H 2). [10-12] However, the high temperature annealing process will lead to damage at the bonding interface, which is induced by residual stress due to the mismatch of the coefficient of thermal expansion. The high temperature process also leads to damage to heat-sensitive components including electrodes, enzymes, and light sources. Furthermore, the decomposed H 2 O and OH groups can be trapped at the bonding interface, resulting in interfacial voids. [10,13] Therefore, glass bonding at room temperature is a desirable process. In order to lower the post-bonding annealing temperature, hydrophilic bonding has been modified mainly by using surface activation such as plasma and UV in the previous studies. The surface activation using O 2 and/or N 2 plasmas has been widely investigated to increase the OH groups on the glass surface. [14-16] For the surface activation by UV irradiation, the organic contamination on the surface is removed using O 3 induced by UV. In the meantime, the hydrophilicity of the glass surface is improved. [17,18] However, since the hydrophilic bonding mechanism is the polymerization of OH groups, a post-bonding annealing at over 200 °C is usually necessary for strong bonding. Recently, surface activated bonding (SAB) has been developed to bond inorganic materials at room temperature. [19-21] In its standard process, the bonding surfaces are treated with This paper presents a room temperature bonding technique of glass substrates with a transparent bonding interface. As a room temperature bonding method, surface activated bonding (SAB) is applied for the bonding of glass using Si intermediate layer. However, the bonding interface is colored by the deposited Si layers, which leads to lower applicability to optical devices. In this study, a new concept of SAB is developed using aluminum oxide intermediate layer. Glass substrates are successfully bonded at room temperature via the aluminum oxide intermediate layers activated by Ar ion beam irradiation, showing a...

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Measurement of bonding energy in an anhydrous nitrogen atmosphere and its application to silicon direct bonding technology

Cited by 64 publications

References 31 publications

Water Stress Corrosion in Bonded Structures

Water Stress Corrosion in Bonded Structures

Mechanisms for Room-Temperature Fluorine Containing Plasma Activated Bonding

Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer

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