Manufacturing method to reduce chiplet development costs

Manufacturing method to reduce chiplet development costs

Technology News |
By Jean-Pierre Joosting

Shin-Etsu Chemical has developed equipment to manufacture semiconductor package substrates using a new manufacturing method that aims to cut the cost chiplet development.

The method uses high-performance processing equipment that uses an excimer laser in which a dual damascene method, as is also used in the front end of semiconductor manufacturing process, is applied to the package substrate manufacturing process (back end process). This back end process is known as the Shin-Etsu dual damascene method. As a result, an interposer’s functions directly formed into a package substrate. This not only eliminates the need of an interposer, but also enables further microfabrication, that conventional manufacturing methods cannot realize. It also reduces costs and capital investment as it does not require the photoresist process in package substrate manufacturing process, making it ideal for chiplet and microelectronics fabrication.

A chiplet, in which circuits are singulated and then assembled in a package, is a technology that can potentially reduce the manufacturing cost of higher-performance semiconductors. This technology requires a process to mount several chiplets on an intermediate substrate and connect them. The intermediate substrate is called an “interposer.”

With the Shin-Etsu dual damascene method, the interposer is not necessary any more, so it significantly simplifies the assembly process. In this method, chiplets are connected to a package substrate with wiring patterns, which has the equivalent function of an interposer. Consequently, the assembly process of advanced semiconductors with chiplet technology can be shortened and its cost can be drastically reduced.

The equipment’s sophisticated microfabrication technology allows complicated electric circuit patterns to be formed directly in each of the organic insulation layers of a multi-layered package substrate, followed by circuit forming via copper plating. It uses an excimer laser as a light source to form large-area electric circuit patterns in batches.

Coreless organic interposer for chiplets

The Shin-Etsu dual damascene method enables further miniaturized microfabrication, which could not be achieved by using the mainstream semi-additive processing (SAP) method that relies on dry film resist. The laser processing equipment can process an area of 100 mm square or larger at one time, using a combination of a photomask made from large photomask blanks and a unique special lens, both from Shin-Etsu. Processing time varies depending on the size of the package substrate,. However, the time required to process the wiring pattern and electrode pads is the same as that required to process vias. Moreover, the via processing time does not depend on the number of vias. For example, it takes about 20 minutes to form trenches of 2 µm width and 5 µm depth and electrode pads of 10 µm diameter and 5 µm depth on an organic substrate of 515 mm × 510 mm, as well as to form vias (upper diameter 7 µm, lower diameter 5 µm, depth 5 µm).

Shin-Etsu Chemical is working on initiatives to integrate its own material and equipment technologies. By developing new process technology, Shin-Etsu Chemical will propose complete solutions from the perspectives of both equipment and materials and take the lead in the development of next-generation technologies, including contributing to the cost reduction of ongoing chiplet development.

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