Advanced Process Control in Megasonic- Enhanced Pre-Bonding Cleaning

Abstract

The increased complexity of microelectronic and sensor applications that have emerged over the past decade have driven wafer bonding to mature as a production technology for both MEMS and 3D stacked die manufacturing. The use of CMOS device wafers has restricted the types of viable bonding processes to low temperature fusion bonding, adhesive bonding and metal bonding. Due to the specific requirements of CMOS technology the allowed bonding processes had to be adapted in order to fulfill the specific CMOS-compatibility demands. This paper presents a novel single wafer Megasonic based cleaning method with enhanced process control capabilities. This cleaning process is integrated in low temperature fusion bonding process and enables higher bonding yields and a reduction in process fluid usage.

Monolithic Thin Wafer Stacking Using Low Temperture Direct Bonding

“…A standard DI water rinse cleaning process, a megasonic-enhanced DI water cleaning process and a megasonic-enhanced cleaning process using diluted NH 4 OH followed by a DI water cleaning step were compared. Details about megasonic-enhanced wafer cleaning technologies were reported in detail elsewhere [5]. Table 1 shows the particle contamination after different cleaning processes.…”

High Efficiency Cleaning Processes for Direct Wafer Bonding

“…The manifold dispenses the process fluid directly into the gap between wafer and transducer allowing more uniform fluid distribution in the active area as well as allowing higher speed rotation of the substrate and requiring less fluid than the single point of dispense. The higher RPM provides for more centrifugal force during the process enabling a more positive, accelerated particle removal path away from the substrate, therefore a shorter cleaning time (6).…”

Megasonic Enhanced Photoresist Strip with DiO₃

“…The radial dispense manifold facilitated an increased maximum operating spin speed and reduces the process fluid requirements. [3] The ozonated DIW (DiO 3 ) was supplied by an MKS LIQUOZON® Single Ozonated Water Delivery System. (figure 2) This model is compact and suited to single substrate processing.…”