Authors:

Antariksh Krishnan

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Professor:

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About Paper:

Three-dimensional Integrated Circuits (ICs) offer a solution to the limitations of two-dimensional ICs, which are reaching the limit of Moore's Law. Chips are stacked using microbumps, solder materials heated until melting to form high melting point intermetallic (IMC) bonds, allowing for heterogenous integration. The main issue with these microbumps is solder leakage beyond microbump boundaries, causing inter-bump shorting. To address this, high-density microbumps can be formed on a surface to mitigate solder leakage. The focus of this project is on designing the porous structure and developing a microfabrication process. Regarding the porous structure design, three different types of porous models were explored by utilizing the capabilities of 3D printing and considering the dimensions of the microbump geometry. For the fabrication process, we will carefully review and discuss the detailed process flows, including factors such as chemicals and equipment. In our preliminary results, we followed a specific process flow. We developed three microbump models using SOLIDWORKS software and microfabricated five samples of each model onto a copper surface using IP-Q resin. After microfabrication, the model was electroplated with copper and treated with Acetone to reveal the etched surface. The porosity and microbump density of the modified copper surface were then examined using a Scanning Electron Microscope (SEM). Upon analyzing all the samples, the microporous layer with a fixed diameter of 1 µm exhibited the highest porosity and the smallest microbump pitch among the three models. The objective of this project is to enable safe and reliable microbump interconnections between Flip Chips.

Source:

Purdue University / 2023

Topics:

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Co-authors:

Antariksh Krishnan