Failure Analysis Protocol: Locating Chip Leakage Points Using EMMI and OBIRCH

In modern electronic products, semiconductor chips serve as the core functional units, and their performance and reliability directly impact the stability and lifespan of the devices. However, chips may experience leakage current issues during manufacturing or operation, which can lead to increased power consumption, functional abnormalities, or even device failure. To ensure chip quality and reliability, it is critical to quickly and accurately locate leakage points.

Alfa Chemistry provides professional semiconductor failure analysis services, combining advanced EMMI (Emission Microscopy Imaging) and OBIRCH (Optical Beam Induced Resistance Change) technologies to help clients precisely identify leakage locations in chips, providing a scientific basis for subsequent improvements and optimizations.

1. Experimental Objective

• To locate leakage points (Leakage Current) in CMOS chips
• To provide data support for failure analysis, reliability verification, and process optimization

2. Experimental Principle

EMMI (Emission Microscopy Imaging)

• Detects weak light emission generated by the chip under electrical current to quickly identify potential leakage regions
• Non-destructive and suitable for large-area scanning

OBIRCH (Optical Beam Induced Resistance Change)

• Uses a focused light beam to induce local resistance changes, combined with current monitoring, to precisely locate leakage points
• Capable of detecting deep-layer defects and suitable for multi-layer packaged chips

3. Instruments and Equipment

4. Sample Preparation

Example Sample: 5 × 5 mm CMOS bare die

4.1 De-packaging and Cleaning

• Clean the chip surface using isopropanol to remove residual packaging material
• Keep the chip dry to avoid contamination from dust or moisture

4.2 Electrode Connection

• Install microprobes on the chip pads
• Connect the chip to the bias control device to ensure stable current measurement

4.3 Environmental Conditions

• Room temperature: 22 ± 2 ℃
• Low-light, low-noise experimental environment
• Electrostatic protection (wear anti-static gloves and wrist strap)

5. Experimental Procedure and Parameters

5.1 EMMI Scanning

• Set bias voltage: V_DD = 1.8 V (according to chip specifications)
• EMMI scanning parameters:
• Spectral range: 400–1000 nm
• Optical magnification: 50×
• Scan speed: 0.5 mm/s
• Light detection sensitivity: medium-high
• Scan the entire bare die surface and record emission anomalies
• Generate an emission heat map and mark high-intensity regions (potential leakage points)

5.2 OBIRCH Scanning

• Select the abnormal regions identified by EMMI (approx. 50 × 50 μm)
• Laser scanning parameters:
• Laser wavelength: 1064 nm
• Laser power: 0.5–1 mW (to avoid chip damage)
• Scan step size: 1 μm
• Scan speed: 0.2 mm/s
• Monitor local resistance changes (ΔR)
• Confirm the leakage point location and repeat scanning to ensure reliability

5.3 Data Processing

• Overlay EMMI and OBIRCH data to generate a combined heat map
• Record leakage point coordinates and signal intensities
• Analyze leakage types (surface, deep, or process-related defects)

6. Precautions / Notes

• Avoid using high-power laser or light beams that could damage the sample
• Maintain a low-light, low-interference environment during scanning
• Reset the bias voltage after each scan to prevent residual current effects
• Handle samples in a non-destructive manner to allow for subsequent analysis

7. Experimental Output

7.1 EMMI Emission Heat Map (preliminary leakage location)

Note: The red regions indicate strong emission signals, representing potential leakage points; orange regions indicate secondary abnormal areas; blue regions represent background signals. The coordinates (100,150) correspond to the primary leakage point, and (120,160) correspond to the secondary point.

7.2 OBIRCH Resistance Change Heat Map (precise leakage point localization)

Note: Red regions indicate high ΔR values, confirming the primary leakage point; yellow regions indicate secondary leakage points; blue regions represent background noise. The coordinates (100,150) correspond to the primary leakage point, and (120,160) correspond to the secondary point.

7.3 Combined Leakage Point Localization Map

Note: The EMMI emission heat map and OBIRCH resistance change heat map are overlaid. Red regions indicate the primary leakage point P1, orange regions indicate the secondary leakage point P2, and blue regions represent background noise. Each leakage point is clearly labeled with its ID and coordinates.

7.4 Data Table: Leakage point coordinates, signal intensities, and voltage conditions

8. Application Scenarios

• Defect screening during chip R&D stage
• Failure analysis of products after mass production
• Reference protocol for customer laboratories to quickly locate leakage points

Frequently Asked Questions (FAQ)