A new film-deposition technology advance from Alchimer S.A.is said to cut fill deposition times and could provide new options for the electronics packaging industry as it struggles to bring through-silicon vias (TSVs) into cost-effective production.
Alchimer has disclosed that its AquiVia TSV barrier-layer process has the ability to provide uniform, guaranteed 100% step coverage over complex silicon topography, including high-aspect-ratio vias with scalloped walls. The barrier layer is one of the bottom-most elements in the TSV film stack. Alchimer’s unprecedented coverage capability means that subsequent depositions can be done in significantly less time and at lower cost, as they do not have to remediate problems in the barrier layer.
The 100% coverage also eliminates a range of coverage-related performance and reliability problems that can occur during subsequent seed-layer and fill deposition.
TSV technology is widely seen as a central enabler for 3D integration processes, which will allow multiple chips to be stacked and interconnected. This is an ideal solution for packing more computing power, memory, and other functions into extremely small devices, such as smartphones, tablet computers and other portable electronics.
Step coverage is the ratio of the thickness of a metallization film on the bottom of a TSV to the film’s thickness on the top, or flat surface.
“Existing etch technologies used to create TSVs have many good qualities, but they tend to create scalloping, steps, and other surface features that pose real challenges for subsequent film deposition,” said Claudio Truzzi, Alchimer’s chief technical officer. “Legacy vacuum-based deposition processes have been unable to put down high-quality barrier layers, especially in deep, small-diameter vias with aspect ratios of 10:1 and beyond – and these ratios are needed to fully realize the economic advantages of 3D integration.
“Poor-quality barrier layers lead directly to electromigration, poor fill results, and high-resistance pathways in interconnect circuits, all of which affect the performance and reliability of high-value 3D assemblies,” explained Truzzi. “This new demonstration of 100 percent coverage shows that our barrier films are uniform across the sides and bottom of vias, even when stair-step patterns and scalloping are present. As a result, subsequent layers can go down over an ideal foundation, in significantly less time, which provides an additional economic improvement.”
AquiVia Barrier and Alchimer’s entire suite of wet deposition products offer a combination of conformality, step coverage and purity that cannot be matched by PVD, CVD, or other dry processes, with costs 40 to 50% lower than standard dry processes. Customers may choose a single film or any combination of films and fills, based on their application needs.
MEET ALCHIMER AT SEMICON TAIWAN: Alchimer will be exhibiting with their Taiwanese partner, Kromax, at Booth 672, Sept. 7-9, 2011. Please visit them there for an in-depth briefing and to learn more about Alchimer’s wet deposition technology. In addition, Alchimer will present at a DigiTimes workshop on optimum 3D TSV structures and processes, on the afternoon of Sept. 7th at the Grand Hyatt, Taipei.
