Dummy Pattern Layout for Aluminum Pad Etching
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Solution Overview
Problem
Conventional semiconductor processes face issues with insufficient process window and aluminum erosion during etching of aluminum pads due to low pattern density, leading to device reliability problems and defects.
Innovation Solution
The introduction of dummy patterns with varying densities and arrangements around electrical connection pads on a wafer, including peripheral and central patterns, to enhance the etching process window and reduce erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma etching is used to remove aluminum film for forming aluminum pads, then aluminum pads can be formed, but the process window is insufficient and aluminum erosion occurs due to low pattern density
Solution Approach 1:
Dummy patterns are formed in advance around the aluminum pads before the actual aluminum pad etching process. These dummy patterns pre-establish the required pattern density in the etching field, ensuring that when the aluminum pads are etched, the plasma distribution is uniform and erosion is minimized. This preliminary structuring resolves the contradiction by preparing the etching environment beforehand.
Solution Approach 2:
The invention changes the physical parameter of pattern density by introducing dummy patterns. The dummy patterns increase the local pattern density around the aluminum pads from a low state (causing erosion) to an optimized state (providing sufficient process window). This parameter transformation resolves the contradiction between forming aluminum pads and avoiding erosion during etching.
2Quantity of substance
If large areas of aluminum film are removed to form aluminum pads, then aluminum pads are formed, but large amount of plasma gas is consumed and process efficiency is reduced
Solution Approach 1:
Instead of uniformly increasing pattern density across the entire wafer, the dummy patterns are strategically placed only in specific regions where erosion is most likely to occur (peripheral regions and regions with low natural pattern density). This localized approach provides the necessary pattern density where needed while minimizing the total amount of dummy material that requires etching, thus resolving the contradiction between forming adequate aluminum pads and maintaining etching efficiency.
3Reliability
If copper is used for solder pad, then low resistance and good anti-electromigration performance are achieved, but the pad is easily destroyed during testing and requires additional cleaning steps
Solution Approach 1:
The invention uses aluminum copper alloy for the solder pads, combining the electrical performance benefits of copper (low resistance, good anti-electromigration) with the mechanical and chemical stability of aluminum (hardness, oxidation resistance). This composite material approach resolves the contradiction by integrating the advantageous properties of both materials into a single pad structure that performs well electrically and is easy to process.
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 layout of dummy patterns improves the etching process window and reduces pad erosion, thereby enhancing the reliability and uniformity of the semiconductor device.
Implementation Method 1
an aluminum film layer is first formed and then the aluminum film layer is processed with plasma etching
Data Source
AI summary
A layout of dummy patterns on a wafer having a plurality of pads disposed thereon is described. The layout of the dummy patterns includes having a plurality of dummy patterns spaced apart from each other and enclosing the plurality of the pads. The plurality of dummy patterns also include a plurality of peripheral dummy patterns and a plurality of central dummy patterns, wherein a minimum distance between the plurality of the central dummy patterns and the plurality of the pads is greater a minimum distance between the plurality of the peripheral dumpy patterns and the plurality of the pads.