Photosensitive Dielectric Layer Thickness Uniformity via HMDS Monolayer
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Solution Overview
Problem
In semiconductor device fabrication, the challenge lies in achieving uniformity and minimizing thickness loss of dielectric layers during processing, particularly in the formation of package structures where vertical stacking and interconnections are critical, and existing methods fail to provide sufficient selectivity during development, leading to residue and non-uniform thickness across the wafer and die regions.
Innovation Solution
The application of a thin layer, such as a self-assembled monolayer formed by exposing the dielectric layer to hexamethyldisilazane (HMDS) gas, which enhances the selectivity between exposed and un-exposed portions during development, reducing thickness loss and improving uniformity by forming a chemically bonded trimethylsilyl group on the surface of the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photosensitive dielectric layer is deposited and developed without additional surface treatment, then the process is simple, but thickness loss and non-uniformity occur during development
Solution Approach 1:
A self-assembled monolayer is formed on the surface of the photosensitive dielectric layer before lithography and development. This preliminary surface modification creates a trimethylsilyl group layer that prevents excessive etching during development, thereby reducing thickness loss and improving thickness uniformity across the wafer while maintaining a relatively simple overall process flow
Solution Approach 2:
The self-assembled monolayer acts as an intermediary layer between the photosensitive dielectric layer and the development solution. This intermediate layer selectively protects the dielectric layer surface during development, controlling the interaction between the developer and the dielectric material to minimize thickness loss and improve uniformity
2Manufacturing precision
If hexamethyldisilazane (HMDS) gas is used to form a self-assembled monolayer, then thickness loss is reduced and uniformity is improved, but additional process steps are required
Solution Approach 1:
The hexamethyldisilazane gas treatment causes the dielectric layer surface to self-assemble into a monolayer with trimethylsilyl groups. This self-organizing process occurs automatically when the gas interacts with the dielectric surface, eliminating the need for complex coating or deposition equipment while achieving consistent thickness control and uniformity improvement
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly decreases thickness loss and increases uniformity of the dielectric layer across the wafer and die regions, achieving a standard deviation of less than 1.5% in thickness, thereby improving the integration density and reducing residue in scribe line regions and vias.
Implementation Method 1
a self-assembled monolayer formed by exposing the dielectric layer to hexamethyldisilazane (HMDS) gas
Implementation Method 2
forming a chemically bonded trimethylsilyl group on the surface of the dielectric layer
Data Source
AI summary
Some embodiments contemplate methods for forming a package structure and a package structure formed thereby. An embodiment method includes depositing a photosensitive dielectric layer on a support structure; forming a first layer on a surface of the photosensitive dielectric layer; exposing the photosensitive dielectric layer to radiation; and after the forming the first layer and the exposing to radiation, developing the photosensitive dielectric layer. The support structure includes an integrated circuit die. The layer has a different removal selectivity than the photosensitive dielectric layer during the developing. According to some embodiments, a thickness uniformity of the photosensitive dielectric layer after developing may be increased, and thickness loss from developing the photosensitive dielectric layer can be reduced.