Double Patterning Test Structure for Charged Particle Beam Inspection
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Solution Overview
Problem
The shrinking size of semiconductor devices requires finer test structures with specific pattern layouts and electrical characteristics to effectively inspect defects, which existing double patterning techniques struggle to achieve, especially in detecting open and short defects with precise defect sizes and locations.
Innovation Solution
A test structure fabricated using double patterning technology, featuring sampling lines and grounding lines with programmable defects, where sampling lines are alternately grounded and isolated, and the distance between pattern elements is carefully controlled to form interlaced grounded and isolated lines, allowing for precise defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard lithographic pattern and etch techniques are applied twice to reduce feature size, then smaller feature size is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the pattern formation into two separate lithographic steps with different resist materials (positive and negative resist). Each step forms a subset of the final pattern, and the combined result achieves the dense line pattern with pitch below 2k1(λ/NA). This segmentation allows standard lithographic techniques to be used twice rather than requiring a single complex exposure step.
Solution Approach 2:
The patent employs periodic action through alternating exposure steps: first exposure with positive resist, development, etching, resist stripping, then second exposure with negative resist. This periodic application of lithographic and etching steps enables the formation of dense patterns by repeating the pattern formation process with complementary resist materials.
2Manufacturing precision
If double patterning technique is used to achieve smaller pitch, then line width below 2k1(λ/NA) is achieved, but process steps increase
Solution Approach 1:
The patent merges two separate patterning operations into a unified process flow. The first pattern formed in positive resist and the second pattern formed in negative resist are combined through the etching step to create the final dense line pattern. This merging allows achieving line widths below the single-exposure limit while using standard lithographic equipment.
Solution Approach 2:
The patent uses an intermediary etching step between the two lithographic exposures. The first resist pattern serves as an etch mask to transfer the pattern to the underlying layer, and after stripping, the second resist pattern is formed. The etching process acts as an intermediary that combines the effects of both exposures to achieve the final sub-2k1(λ/NA) pitch pattern.
3Measurement precision
If test structures with finer features are fabricated to inspect semiconductor devices, then defect detection accuracy is improved, but fabrication difficulty increases
Solution Approach 1:
The patent applies preliminary action by pre-forming patterns in resist materials before the final etching step. The first and second resist patterns are formed and developed in advance, serving as masks that guide the etching process. This preliminary pattern formation allows precise control of the final test structure features, enabling accurate defect detection while managing fabrication complexity.
Solution Approach 2:
The patent changes parameters by using different resist materials (positive and negative) with different properties in sequential steps. The positive resist responds to irradiated regions while the negative resist responds to non-irradiated regions. This parameter change in resist chemistry enables the double patterning approach to achieve finer features than single-exposure lithography.
Data Source
AI summary
A test structure and a method for fabricating the same are disclosed. The test structure includes a plurality of sampling lines over a substrate located between a plurality of a first grounding lines and a plurality of a second grounding lines. The sampling lines are selectively electrically coupled to the first grounding line or the second grounding line and include at least one programmed defect. A double-patterning fabricating approach is utilized to produce such test structure which may be applied to a charged particle beam such as an electron-beam defect inspection system.