Dummy Pillars for Uniform CMP Pressure in TSV Substrates
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Solution Overview
Problem
The combination of conductive pillar technology with through-silicon via (TSV) technology faces challenges due to non-uniform pressure distribution during chemical mechanical polish, leading to varying TSV lengths and uneven backside surfaces, which adversely affect subsequent lithography processes.
Innovation Solution
The use of dummy pillars, evenly distributed alongside active conductive pillars, to ensure uniform pressure distribution during the thinning process, improving the depth uniformity of the substrate and enhancing the planarity of the backside surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductive pillars are formed on the front surface of the substrate without dummy pillars, then the manufacturing process is simpler, but the pressure distribution during CMP becomes non-uniform, resulting in varying TSV lengths and uneven backside surfaces
Solution Approach 1:
The patent introduces dummy pillars to create a homogeneous distribution of pressure points across the substrate surface during CMP. The dummy pillars are distributed uniformly in regions where active pillars are absent, ensuring that the polishing pressure is evenly distributed across the entire backside surface, thereby achieving uniform TSV lengths and smooth backside surfaces.
Solution Approach 2:
The dummy pillars act as intermediary elements that mediate the pressure distribution between the CMP polishing head and the substrate. These non-conductive or conductive dummy structures serve as placeholders that transfer and distribute the polishing pressure uniformly, preventing direct contact issues and ensuring consistent polishing depth across the substrate.
2Manufacturing precision
If dummy pillars are added to ensure uniform pressure distribution, then the backside surface uniformity improves, but the device complexity increases
Solution Approach 1:
The patent segments the pillar structure into two functional categories: active conductive pillars for electrical connection and dummy pillars for mechanical support and pressure distribution. This segmentation allows each type of pillar to be optimized for its specific function, with dummy pillars placed in non-critical areas where they provide structural benefits without interfering with electrical performance.
Solution Approach 2:
The patent applies local quality by giving different regions of the substrate different pillar configurations. Areas requiring electrical connection have active conductive pillars, while areas requiring only mechanical support have dummy pillars. This localized differentiation optimizes the overall system by providing uniform pressure distribution without adding complexity to the electrical interconnect structure.
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
The introduction of dummy pillars effectively distributes pressure evenly, resulting in a smooth and uniform backside surface, which enhances the reliability of the manufacturing process and supports subsequent lithography processes by maintaining high integration density.
Implementation Method 1
The through silicon vias are exposed by polishing the back surface of the substrate using CMP
Data Source
AI summary
A semiconductor component formed on a semiconductor substrate is provided. The semiconductor substrate has a first surface and a second surface. The semiconductor substrate includes a plurality of devices on the first surface. A plurality of through silicon vias (TSVs) in the semiconductor substrate extends from the first surface to the second surface. A protection layer overlies the devices on the first surface of the semiconductor substrate. A plurality of active conductive pillars on the protection layer have a first height. Each of the active conductive pillars is electrically connected to at least one of the plurality of devices. A plurality of dummy conductive pillars on the protection layer have a second height. Each of the dummy conductive pillars is electrically isolated from the plurality of devices. The first height and the second height are substantially equal.