Metrology Mark Replacement for Lithography Alignment
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Solution Overview
Problem
In semiconductor manufacturing, degraded metrology marks can lead to inaccurate pattern transfer and reduced device yield due to misalignment and metrology incompatibilities, causing inefficiencies and inaccuracies in the patterning process.
Innovation Solution
A method and apparatus that measure degraded metrology marks using a first type of metrology and create replacement marks using a second type of metrology, allowing for improved alignment and metrology accuracy by applying a replacement mark prior to subsequent lithographic steps, utilizing sensors and mark application devices to ensure compatibility and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single type of metrology mark is used throughout the lithographic process, then the initial measurement is simple, but the mark becomes degraded and incompatible with subsequent lithographic steps
Solution Approach 1:
The patent divides the metrology marking process into multiple segments: initial metrology marks are created in a first format suitable for pre-lithography measurement, and replacement metrology marks are created in a second format suitable for post-lithography measurement. This segmentation allows each mark type to be optimized for its specific measurement context, resolving the contradiction between initial measurement simplicity and subsequent compatibility.
Solution Approach 2:
The patent performs preliminary metrology measurements using initial marks before the lithographic step, then creates replacement marks after lithography. This preliminary action sequence ensures that measurements are taken at the appropriate times with appropriate mark types, preventing the degradation and incompatibility issues that would arise from using a single mark type throughout.
2Productivity
If degraded metrology marks are used in subsequent lithographic steps, then the process continues without interruption, but alignment accuracy deteriorates and device yield decreases
Solution Approach 1:
The system performs self-service by automatically detecting degraded metrology marks and creating replacement marks without requiring external intervention or process interruption. The lithographic apparatus itself carries out the mark replacement function, maintaining productivity while ensuring measurement precision.
Solution Approach 2:
The patent changes the parameters of the metrology marks by creating replacement marks with different characteristics (second format) that are suitable for post-lithography measurement. This parameter change from initial mark format to replacement mark format resolves the alignment accuracy deterioration that would occur with degraded marks.
3Adaptability or versatility
If replacement metrology marks are created after lithography, then compatibility with subsequent steps is improved, but additional process time is required
Solution Approach 1:
The patent merges the metrology mark creation function with the existing lithographic process by utilizing the same apparatus to both perform lithography and create replacement metrology marks. This combining of functions minimizes additional process time while achieving the compatibility benefits of replacement marks.
Data Source
AI summary
A method including: subsequent to a first device lithographic step of a device patterning process, measuring a degraded metrology mark on an object and/or a device pattern feature associated with the degraded metrology mark, the degraded metrology mark arising at least in part from the first device lithographic step on the object; and prior to a second device lithographic step of the device patterning process on the object, creating a replacement metrology mark, for use in the patterning process in place of the degraded metrology mark, on the object.