Nanoscale Failure Analysis with Protective Layer Transfer
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Solution Overview
Problem
Existing nanoscale failure analysis methods face challenges such as metal diffusion during sample transfer, inability to confirm electrical characteristics of fail twin bit lines, limitations in reducing failure range, reliance on time-consuming SEM high-voltage observation, and difficulty in ensuring sample flatness.
Innovation Solution
A nanoscale failure analysis method involving the use of a protective layer deposited by an electron beam in an FIB machine to prevent metal diffusion during sample transfer to a nano prober, followed by surface micro treatment to expose the metal pattern for electrical testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the sample is transferred from FIB machine to nano prober without protective layer, then the transfer process is simple and fast, but metal diffusion occurs severely during transfer
Solution Approach 1:
A protective layer is deposited on the cross section surface before transferring the sample from FIB machine to nano prober. This preliminary protective action prevents metal diffusion during the transfer process, and the protective layer can be removed later at the target location to expose the metal pattern for electrical testing.
Solution Approach 2:
The protective layer acts as an intermediary substance that temporarily covers the metal pattern during transfer. It mediates between the need for fast transfer and the need to prevent metal diffusion, allowing the sample to be transferred safely and then restored to its original state for testing.
2Ease of manufacture
If metal diffusion is allowed to occur, then the transfer process is simple, but electrical characteristics of fail twin bit lines cannot be confirmed
Solution Approach 1:
The protective layer is deposited in advance before transfer to prevent metal diffusion, ensuring that the metal patterns remain distinct and electrical characteristics can be accurately confirmed during subsequent nano probe testing.
3Device complexity
If no protective layer is used, then the process steps are reduced, but the target area cannot be continuously reduced through bisection method
Solution Approach 1:
By depositing the protective layer in advance, the method enables subsequent precise bisection operations. The protective layer maintains sample integrity during transfer, allowing the target area to be systematically reduced through repeated bisection methods to locate the exact failure position.
4Ease of manufacture
If sample flatness is not ensured through manual polishing, then the polishing process is simplified, but it becomes difficult to ensure proper sample flatness for testing
Solution Approach 1:
The manual mechanical polishing process is replaced with FIB machine cutting to create the cross section, followed by protective layer deposition. This substitution eliminates the need for complex manual polishing while ensuring proper sample flatness and surface quality for subsequent electrical testing.
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 effectively prevents metal diffusion, allows for accurate electrical testing, and enables continuous reduction of the target area containing the fail position, thereby reducing analysis time and improving accuracy.
Implementation Method 1
depositing a protective layer on the first cross section by using an electron beam of the FIB machine
Implementation Method 2
performing cutting on a selected area of the first sample by using an ion beam in the FIB machine to form a first cross section and expose a metal pattern
Implementation Method 3
performing surface micro treatment on the first sample by using an ion source in the nano prober to remove the protective layer and expose the metal pattern
Data Source
AI summary
This application discloses a nanoscale failure analysis method, including step 1: placing a first sample to be analyzed on a sample stage of an FIB machine, and performing cutting on a selected area of the first sample by using an ion beam in the FIB machine to form a first cross section and expose a metal pattern on the first cross section; step 2: depositing a protective layer on the first cross section by using an electron beam of the FIB machine; step 3: transferring the first sample to a nano prober, the protective layer being used for protecting the metal pattern and preventing metal diffusion in a transfer process; step 4: performing surface micro treatment on the first sample by using an ion source in the nano prober to remove the protective layer; step 5: performing probing on the metal pattern and implementing electrical testing through the nano prober.