Optical Proximity Correction Outermost Pattern Size Control
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Solution Overview
Problem
As semiconductor devices become highly integrated, the critical dimension (CD) uniformity on wafers deteriorates due to the limitations of photolithography, making it difficult to maintain pattern uniformity, especially with the transition from KrF to ArF processes, where assist features (AF) are challenging to optimize and often cause scum, reducing process margins.
Innovation Solution
A method to control pattern uniformity by adjusting the size of outermost patterns through optical proximity correction (OPC) and changing the space sizes or pattern widths of reference patterns within a specific range, without modifying existing exposure systems, to achieve improved CD uniformity and depth of focus margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If assist features (AF) are used to improve CD uniformity, then pattern uniformity is improved, but scum occurs and process margin is reduced
Solution Approach 1:
The invention extracts and removes the assist features (AF) from the photolithography process while maintaining their beneficial effect on CD uniformity through an alternative approach - optimizing the outermost pattern size to control the interference effect, thereby eliminating scum generation while preserving pattern uniformity
2Object-generated harmful factors
If pattern size of AF is optimized to prevent scum, then scum is reduced, but interference effect is weakened and CD uniformity deteriorates
Solution Approach 1:
The invention changes the critical parameter from AF pattern size to outermost pattern size, utilizing the interference effect between outermost and inner patterns to control CD uniformity without generating scum, thereby resolving the trade-off between preventing scum and maintaining interference effect
3Manufacturing precision
If outermost pattern size is increased to enhance interference effect, then CD uniformity is improved, but pattern density increases and scum may occur
Solution Approach 1:
The invention optimizes the outermost pattern size within a specific range (0.02L to 0.08L) to achieve the optimal balance between enhancing interference effect for CD uniformity and controlling pattern density to prevent scum, resolving the contradiction through precise parameter control
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 enhances CD uniformity and process margins by optimizing the size of outermost patterns, improving the uniformity of inner patterns, and maintaining optimal performance even at smaller feature sizes, such as those below 40 nm, without the need for assist features.
Implementation Method 1
photolithography is a technology for creating high integration semiconductor devices by forming patterns in a predetermined shape on a wafer substrate using light. Namely, light (e.g., an ultraviolet ray, an electron beam, or an X ray) is irradiated onto a photoresist layer where a predetermined portion of the photoresist layer is exposed to the light using a photo-mask
Implementation Method 2
The part of the layer (underneath the photo resist pattern) exposed by the photo resist pattern is removed by an etch process to form a desired semiconductor device pattern
Data Source
AI summary
A method for controlling uniformity of patterns formed in a semiconductor device includes obtaining simulation contours with respect to respective cases while controlling a size of an outermost pattern and determining a size of the outermost pattern in which uniform distribution values (3σ) value of patterns included in the simulation contours satisfying specific conditions as a size of target outermost pattern.