The TSV copper plating materials field is anticipated to be a 10 billion yen market from 2017, where additives will occupy around 5 billion yen. We aim to acquire a market share of 50% by establishing the new additive system.
Semiconductor manufacturers have recently been attempting to achieve a smaller size and higher performance of devices by stacking multiple chips into the 3D structure. TSV technology is indispensable in creating these 3D structures, considering benefits of the shortest and high-density connections. TSV electrodes provide vertical electrical connections that pass internally through semiconductor chips. The development of TSV-based 3D structures involves key technologies such as the formation of via (a small hole a few micrometers to a few tens of micrometers in diameter) and via filling with conductors. Via filling technique based on copper electroplating draws attention as one of the most important technologies for electrode formation.
In the copper filling process, TSV via must be perfectly filled without voids or seams for a reliable electrical connection. Copper sulfate plating solution for copper plating contains a suitable balance of several types of additives (such as accelerator, suppressor, and leveler). However, our newly developed additive is of a single type and gives high performance with copper filling.
The features of this new additive include the following:
(1) Single component enhances manageability: Strict constant control of plating solutions is required at manufacturing sites that use plating methods. This new single-component type additive makes it easier to control solutions compared with other types, leading to a significant cost reduction.
(2) Complete bottom-up filling: Bottom-up filling (copper deposition progress from the bottom of the via) avoids the occurrence of defects in the filled copper.
(3) Highly versatile: The new additive is effective with TSVs of various sizes. We confirmed perfect filling for a wide range of via sizes, i.e. 5 to 20 micrometers in diameter and aspect ratios of 1 to 10. Our additive is also effective with via holes of different sizes on the same wafer.