AML Launch new Temporary bonding technique for TSV applications
Applied Microengineering Ltd (AML) has announced the launch of its revolutionary "adhesive-free" temporary bonding solution for the 3D integration of silicon wafers using Through Silicon Vias (TSV). This new temporary bonding solution - filed for patent by AML - will enable fab lines to substitute the current adhesives based solutions and gain from cost reductions, simplified procedures, fewer processing steps, increased yields and lower manufacturing cost.
The 3D-integration of silicon wafers using TSV is now revolutionised by the new AML vacuum wafer carrier which provides a quick, clean & easy way of holding the wafer to be thinned & processed using just a vacuum, superseding the need for the adhesive temporary bonding.
3D integration of silicon wafers using Through Silicon Vias (TSV), like the stacking of wafers, is key, in continuing the "Moore's law" increase in packing density of devices on a chip and is currently the biggest application in microelectronics manufacturing. A key step is the temporary bonding of wafers onto a carrier to facilitate processes such as wafer grinding to thin the wafers. The thinned wafers are required to enable the TSV to be formed with a high enough packing density. The temporary bonding solution has been very difficult to solve, and until now it has been down to the crude technique of gluing the wafers together using an adhesive. This technology process has many flaws: complex procedures, low yields, and very expensive equipment to name but three. However the industry has had no choice, until now.
AML who bucked the trend and gave the industry the now recognised superior unique technique of in-situ alignment and bonding in one chamber has now turned its innovative thinking to temporary bonding:
The new AML vacuum wafer carrier provides a quick, clean and easy way of holding the wafer to be thinned using just a vacuum. This temporary bonding step can be carried out in a standard AML wafer bonder! De-bonding is also very simple, the temporarily bonded assembly is placed back into the AML bonder and the chamber is pumped down to a pressure lower than the vacuum pressure encapsulated between the carrier and bonded wafer - the temporary bonded wafer is simply released - no need for any further processing such as removing traces of adhesive! In some cases, a simple injection of a gas into the cavity will enable the de-bond.
Importantly, the absence of adhesives also allows direct contact of any existing solder bumps on the device wafer with contact pads on the carrier - the carrier can be designed to specifically align these bumps in pre-machined recesses. This facilitates the ability to perform wafer level testing!
Obviously keeping vacuum integrity is key to this technology. The AML vacuum wafer carrier requires being equipped with the adequate seal, a critical application success component. The sealing solution also needs to withstand the chemical environments and thermal loads - typical of the subsequent 3D integration processes -, and offers cleanliness and low outgassing properties. DuPont engineered a proprietary sealing solution to respond to the requirements of the AML vacuum wafer carrier bonding system. AML had tested many sealing solutions and found the DuPont high performance seals to be the best.
"I am very proud that one of our products is helping AML to translate a concept into a very promising new technology that aims to accelerate the industry adoption of 3D TSV," comments Michele Vigliotti, Semiconductors Market Development Manager, at DuPont, EMEA, "It has been a great collaborative development journey with AML."
"Choosing the right partner for this was very important and DuPont not only offered the best product but the best support, the technical know-how and outstanding resources. They are an ideal partner for AML" says Rob Santilli, CEO, of AML. "DuPont are a pleasure to work with, responsive, fast, with a vast and comprehensive knowledge of materials suitable for this application - I could not think of a better partner".
