High-precision heterogeneous integration based on flip-chip bonding using misalignment self-correction elements

Suzuki

Kato

et al. 2013

Jpn. J. Appl. Phys.

High-precision integration has valuable meaning in heterogeneous convergent technology. In this paper we report on a new high-precision low-temperature bonding approach, capable of submicron alignment accuracy, based on the conventional ultrasonic flip-chip bonding technique and modified metal pad and bump elements. The interconnection pair made from a conductive-sloped hollow bonding pad (concave) and metal cone bump (convex) elements, i.e., misalignment self-correction elements, helps in aligning and maintaining the alignment between the chip and the substrate during stacking. By this method, the stacking accuracy can be improved significantly and effectively. Repeatable submicron (i.e., less than 500 nm) bonding accuracies are confirmed through experimental investigation. Moreover, reliable bond characteristics including electrical and mechanical properties are observed, validating the performance of the bonding approach. With these results, the proposed high-precision low-temperature bonding approach shows its suitability for heterogeneous electronics–optics integration applications.

Section: (A)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sub-Micron-Accuracy Gold-to-Gold Interconnection Flip-Chip Bonding Approach for Electronics–Optics Heterogeneous Integration

Suzuki

Kato

et al. 2013

Jpn. J. Appl. Phys.

“…To improve the accuracy of the bonding process, we propose misalignment selfcorrection elements (MSCEs) which are utilized to correct and maintain the alignment of chip to substrate during staking, automatically [16]. The MSCEs are based on the principle of using bump (convex) and hollow (concave) elements ( Fig.…”

Section: Bonding Approach Based On Misalignment Self-correction Elementsmentioning

confidence: 99%

Heterogeneous integration approach based on flip-chip bonding and misalignment self-correction elements for electronics-optics integration applications

Suzuki²,

Kato³

et al. 2012

Vietnam J. Mech.

This paper presents a high precision bonding approach, capable of submicron alignment accuracy, based on the thermosonic flip-chip bonding technique and misalignment self-correction elements. The precision of the bonding technique is guaranteed by using of misalignment self-correction bump (convex) and hollow (concave) elements. Metal cone bump and conductive sloped hollow bonding pad elements are created using micro-machining techniques, on a chip specimen and substrate, respectively. The chip and substrate are bonded face-to-face using of an ultrasonic-enhanced flip-chip bonder. By introducing of misalignment self-correction elements, repeatable bonding accuracies of less than 500 nm were confirmed through experimental investigation. Bond properties, including electrical and mechanical properties, are also characterized to confirm the success of the bonding approach. With the obtained results, the proposed bonding approach is capable of being use in electronics-optics heterogeneous integration applications.

“…In our study, we proposed a high-precision room-temperature bonding approach, capable of achieving submicron post-bond alignment accuracy, based on the ultrasonicassisted thermo-compression FCB technique and self-aligned interconnection pairs. [26][27][28][29] The conventional bump/planarpad interconnection [Fig. 2(a)] was modified to form concave-convex self-aligned structures: a truncated inverted pyramid (TIP) bonding pad and a micro bump [Fig.…”

Section: Introductionmentioning

confidence: 99%

15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications

Kato

Watanabe

et al. 2014

Jpn. J. Appl. Phys.

In this paper, we report the development of reliable fine-pitch micro bump interconnections that used a high-precision room-temperature bonding approach. The accuracy of the bonding process is improved by modifying conventional bump/planar-bonding-pad interconnections to form self-aligned micro bumps/truncated inverted pyramid (TIP) bonding pads, i.e., misalignment self-correction elements (MSCEs). Thermosonic flip-chip bonding (FCB) is utilized to form reliable bonds between these MSCEs at acceptable low temperatures. By applying the proposed bonding approach, the demonstration of fine-pitch Cu bump to Au bonding pad interconnects chip stacking has been realized. Microstructure analyses reveal that 15-µm-pitch micro bump joints are fabricated at room temperature.