Wafer Bonding Seal Ring

Sealing rings after eutectic wafer bonding.

Wafer bonding seal ring.

Most of the metal seal bonding technologies require metal frames on both wafers as shown in figure 32 1. Article osti 1107804 title wafer level packaging with compression controlled seal ring bonding author farino anthony j abstractnote a device may be provided in a sealed package by aligning a seal ring provided on a first surface of a first semiconductor wafer in opposing relationship with a seal ring that is provided on a second surface of a second semiconductor wafer and. Metal layer bonding pattern seal rings and bond pads photolithographically eutectic bonding uses eutectic point in metal si phase diagrams to form silicides au and si have eutectic point at 363 c. Here a cap wafer is manufactured with a gold ring metallization and the mems wafer provides a silicon frame area for the metallurgical reaction.

It is found that the principal cause of the partial bonding is due to non flat bcb sealing ring caused by multilayer bcb coating process. The seal ring in one embodiment includes a pair of seal rings i e a first seal ring 150a and a second seal ring 150b. This paper presents the effect of bcb sealing ring flatness on bcb bonding for wafer scale bcb cap transfer packaging. One such technique is wafer level packaging wlp which forms a hermetically sealed cavity in which the device element is situated.

A material a b c d e f cap dicing. Wafer to wafer bonding and packaging dr. Eutectic ausi bonding is the only method where only one joining partner requires a metal frame. Finally both cap and interposer wafers were bonded together using a wafer to wafer bonder and an adapted ausn soldering process scheme.

The bottom wafer generally was a 300µ m thick 4 si wafer having a low bow and a low total thickness variation ttv. The polymer caps can be implemented through sacrificial etching and a wafer level transfer technique. The pair of seal rings for example is arranged in parallel. The seal ring 150 as shown in fig.

Finally polymer cap encapsulation combining the merits of wafer to wafer bonding and thin film packaging has been reported. These results demonstrate that bonding with the cusn thin film sealing ring at 400 c. 17 21 it consists of a polymer membrane as a packaging cover and a polymer sealing ring. Thara srinivasan lecture 25.

Due to the concave regions un etched bond rings when the cap wafer comes into a contact with a planar device wafer only the concave seal area un etched area gets bonded. With advances in wafer bonding technology this process has been widely applied to the fabrication of mems devices. Deposited on patterned si bonding ring. As a solution bcb dry etching has been proposed to.

The bond seal area is defined by etching the backside of a cap wafer by 2 µm.