Interlaced Active Areas for Non-Destructive IC Defect Detection
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Solution Overview
Problem
In integrated circuit manufacturing, particularly in DRAM production, piping defects caused by voids or keyholes between word lines during inter-layer dielectric deposition are difficult to detect, especially as feature sizes shrink, and existing charged particle beam systems often require destructive annealing to identify these defects.
Innovation Solution
A test structure with interlaced normal and defective active areas is designed to detect electrical shorts between contact plugs using a charged particle beam system, where the defective areas are created by intentional doping variations, allowing for non-destructive detection of void-induced shorts and non-open contacts through modulated voltage contrast imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charged particle beam systems are used to detect piping defects, then detection capability is improved, but destructive annealing process is required which increases process complexity and time
Solution Approach 1:
The patent applies preliminary action by performing doping modifications to contact plugs before the deposition process. Specifically, arsenic doping is applied to contact plugs in alternating rows during the ILD deposition process, creating intentional conductivity variations that will later enable non-destructive detection of piping defects through voltage contrast imaging with charged particle beam systems.
Solution Approach 2:
The patent changes the electrical conductivity parameter of contact plugs by applying selective arsenic doping. This parameter change creates distinguishable voltage contrast between doped and non-doped contact plugs, enabling the charged particle beam system to detect piping defects without requiring destructive annealing processes.
2Productivity
If feature size continues to shrink, then integration density is improved, but piping defect detection becomes more difficult
Solution Approach 1:
The patent applies local quality by creating spatially varying doping patterns in contact plugs. Alternating rows of contact plugs are doped with arsenic while others remain undoped, creating local electrical property differences that enhance detectability of piping defects even as overall feature sizes shrink and integration density increases.
Solution Approach 2:
The doping modification is performed preliminarily during the ILD deposition process itself, before defect formation occurs. This preliminary doping establishes a detectable pattern that will reveal piping defects through voltage contrast imaging, enabling detection capability to keep pace with shrinking feature sizes.
3Measurement precision
If destructive polysilicon anneal process is used, then piping defect detection is enabled, but manufacturing time and process steps increase
Solution Approach 1:
The patent performs the doping modification action preliminarily during the standard ILD deposition process, eliminating the need for subsequent destructive annealing steps. The arsenic doping is applied to contact plugs before defect formation, creating a detectable signature that enables piping defect identification through non-destructive voltage contrast imaging.
Solution Approach 2:
The patent replaces the mechanical/thermal destructive annealing process with a chemical doping approach combined with non-destructive charged particle beam imaging. Instead of using high-temperature annealing to make defects detectable, the method uses selective arsenic doping to create electrical property differences that can be detected through voltage contrast, eliminating the need for destructive thermal processing.
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 method enables effective detection of piping defects and contact open issues in integrated circuits without destructive processes, improving defect identification accuracy and reducing the challenges associated with shrinking feature sizes.
Implementation Method 1
Another advantage of EBI is that it can detect voltage contrast (VC) defects of electrical circuitry such as open circuit, short circuit or leakage underneath the wafer surface because of surface charge induced gray level (GL) variation.
Implementation Method 2
Ion implantation is a process in which dopant atoms are accelerated into a solid, typically a semiconductor, to change the electrical properties of the solid.
Data Source
AI summary
The present invention discloses a structure and method for determining a defect in integrated circuit manufacturing process, wherein the structure comprises a plurality of normal active areas formed in a plurality of first arrays and a plurality of defective active areas formed in a plurality of second arrays. The first arrays and second arrays are interlaced, and the defect is determined by monitoring a voltage contrast from a charged particle microscope image of the active areas.