How Digital Microscopy can Contribute to Efficient Workflows for Microelectronics and Electronics

Industrial Manufacturing Technical Report

November 30, 2016

This report describes how the digital microscope portfolio of Leica is intended to help users achieve overall, cost-effective workflows in research and development (R&D), product innovation, process engineering, production, quality control and assurance (QC/QA), and failure analysis (FA). Today many manufacturers of microelectronic and electronic devices are required to be workflow-centric in their processes for R&D, production, QC/QA, and FA. Faster and cheaper manufacturing through adaptation of novel materials and processes leading to further miniaturization, while still conforming to ever-stricter specifications, is the norm. State-of-the-art digital microscopes help users work efficiently and ergonomically in diverse fields, such as, automotive, microelectronics and electronics, information and communication technology, biomedical and electro-medical technologies, industrial machinery and equipment, and renewable energy technologies. Leica offers a complete digital microscope product portfolio with the motivation to optimize workflows leading to improved efficiency, reliability, and quality for inspection, documentation, analysis, and metrology. Often, the overall workflow involves going from a fast, macroscale overview to nanoscale, precise metrology.

Introduction

This report explains how users can benefit from the digital microscope portfolio of Leica to attain cost-effectiveness over entire workflows in research and development (R&D), product innovation, process engineering, production, quality control and assurance (QC/QA), and failure analysis (FA).

Inspection, documentation, and in-depth analysis of devices and their components to determine conformity with product  specifications can be done easily and quickly with digital microscopy. Digital microscopes [1] do not use eyepieces, but instead users observe an image displayed directly on a monitor.

Innovations in microelectronics and electronics have led to smaller, faster, and more efficient devices. As a result, it can be challenging to meet the constantly improving specifications for the manufacture  of these devices in a cost-effective way. Such devices serve as important product components in multiple fields, e.g., automotive, information and communication technologies, biomedical and electro- medical technologies, industrial machinery and equipment, consumer electronics and semiconductors, organic photovoltaics including OLEDs, and renewable energies. It is important that the parts are reliable as they are critical for maintaining the performance standards of the devices during their lifetimes. However, the demand for faster, cheaper production while still meeting or exceeding ever-stricter standards is growing. To this end, novel materials and processes are more and more adapted for device manufacture leading to increasing miniaturization and higher performance, i.e., reduced material and component size and better device reliability and efficiency.

The production of some microelectronic devices, such as hard drives, requires inspection and quality control of its various components over the full scale: from macroscopic (> 2 mm) to mesoscopic (10 mm ↔  25 µm) and microscopic (1000 µm ↔ 500 nm) down to nanoscopic < 500 nm). Microscopes having the ability to image with a large field of view for a simple part overview up to the highest resolution for precise metrology are needed. The demand for faster, cheaper production which fulfills improving specifications makes optimization over the complete workflow important. One way to achieve optimization is through the selection of appropriate optical  analysis and measurement systems for every step in the value chain or  stream.

How to optimize the entire workflow using Leica’s digital microscopy portfolio

Fig. 1: Chart showing the typical range of scale for application of the digital microscopes, the Leica DMS, DVM6, and DCM8, in the Leica digital product portfolio. For each microscope there are specific advantages to consider when selecting the most appropriate tool to help optimize the workflow.

The digital microscope portfolio offered by Leica is designed to help users in the optimization of their complete workflow [2] (refer to Figure 1). It can be optimized from the macroscopic and mesoscopic larger scale with low magnification for fast overview of parts to the microscopic and nanoscopic smaller scale with high magnification and resolution for metrology.

These different user needs can be addressed with the digital microscope portfolio consisting of the Leica DMS, Leica DVM6, and Leica DCM8 product lines.

Some of the performance advantages of each of the digital microscopes are shown in Table 1.

Advantages: Leica digital microscope portfolio

LEICA DMS [3]

LEICA DVM6 [4]

LEICA DCM8 [5]

Being able to see more of the part or sample in a single image with a large field of view (FOV) (max FOV = 82 × 64 mm 94 mm diagonal)

Being able to obtain easily consistent image results no matter the expertise of the user by virtue of the unique 5 axes (stage XYZ position and rotation plus head tilt)  encoded system allowing easy storage and rapid recall of important parameters, such as, optics, illumination, and camera settings [7]

Attain precise functional surface characterization of materials due to optimal lateral resolution (< 140 nm) and imaging with HD confocal  microscopy

Fast and easy to use when changing magnification with parfocal and parcentric optics

Staying focused on the part or sample and  finding a feature quickly and easily using the unique hybrid XYZ stage with the ability to move and rotate the sample both manually and with motorized control [8, 9]

Achieve precise metrology of material surface texture and roughness because of optimal vertical resolution (down to 0.1 nm) with HD  interferometry

Accurate measurement for samples having large height differences with high quality telecentric optics [6]

Making visible difficult-to-image details from versatile contrast methods available with the integrated LED (light-emitting diode) ring light, coaxial, and oblique illumination, or high dynamic range (HDR) imaging [8, 9, 10]

Viewing parts or samples in their authentic colors with confocal microscopy due to the 4 LED red- green-blue (RGB) illumination for HD true-color imaging

Standalone operation with direct live high definition (HD) image display on a monitor and data recording to secure digital (SD)  card

High quality image data essential for in-depth analysis thanks to the digital camera with 10 megapixel (MP) chip and plan apochromatic optics

Recording multi-focus images of sample areas with large height differences using focus variation (FV) or Z-stacking

 

Ability to obtain quickly large mosaic overviews of parts using XYZ stitching [8, 11], as well as, multi-focus images of sample areas with large height differences using extend depth of field (EDOF) or Z-stacking [7, 11]

 

Tab. 1: Performance advantages of each instrument in the digital microscope portfolio offered by Leica.

The Leica DMS digital microscope [3] enables efficient inspection and documentation workflows at the macro- to mesoscale (> 2 mm − 25 µm) and can be applied to inspection for component placement and defects, drilling, milling, laser ablation errors, and the quality of lead soldering, conductive and signal traces, conductive pads, through-holes, etc.

The Leica DVM6 digital microscope [4] permits efficient inspection, documentation, and analysis workflows at the meso- to microscale (10 mm − 500 nm) for such things as 2D and 3D measurements via diameter, circumference, and depth profiles of through-holes and vias, as well as, length, area, and height profiles of solder joints and components.

The Leica DCM8 digital and confocal microscope/optical profilometer [5] allows for efficient precision analysis and surface roughness measurement workflows at the micro- to nanoscale (1000 µm − < 500 nm) with respect to such things as surface roughness characterization of silicon and glass wafers, polished metal alloys and ceramics, films, and coatings, etc.

How to apply digital microscopy to inspection of a microelectronic device – hard drive for data storage

As mentioned above, a hard drive is one type of microelectronic device which requires inspection over the full size scale, from  macroscopic to nanoscopic. As an example of inspection of a microelectronic device with the digital microscope portfolio, parts of hard drives were analyzed with the Leica DMS1000, the Leica DVM6 A, and the Leica DCM8 in high end configuration. The results are shown below.

Inspection and documentation for line production or trouble- shooting using the Leica DMS1000

In most cases, inspection and in-line quality control is done during production to detect the presence of any defects or irregularities, such as scratches, component cracks and breaks, solder problems, short circuits, etc. Quick inspection at strategic points in the production process of hard drives can help ensure that the standards and specifications are being met. As time is money, any inspection needs to be done easily and quickly.

The Leica DMS1000 digital microscope permits practical, rapid inspection of hard drive parts and components at the macroscopic  and mesoscopic scale. A very large field of view (FOV) at low magnification allows users to make a large scale overview, then, if an area of interest is seen, they can zoom in to see more detail at higher magnification and resolution. As the microscope has encoded zoom optics, users also have the advantage of easy storage and fast recall  of the image data complete with system settings [3].

Figure 2 and 3 below show images of hard drive components recorded with the Leica DMS1000. When doing inspection for defects or errors, usually:

  • A large overview of the component at low magnification is made. For these specific cases, a top view of the disk or platter read-write head and actuator arm (Figure 2a) and the underside (Figure 3a) of a hard drive, showing the bottom of a printed circuit board (PCB) and the cable connector pins, are seen.
  • Then, if an interesting area for more detailed inspection is found, an image at higher magnification, by increasing the zoom factor, is recorded, as noted for the read-write head and actuator arm (Figure 2b) and hard drive underside (Figure 3b).
Fig. 2a: Image of a hard drive read-write head and actuator arm acquired with the Leica DMS1000 at lower magnification.
Fig. 2b: Zoom-in of the indicated area in Figure 2a showing more detail of the same hard drive read-write head and actuator arm. There are scratches on the arm’s metal surface near the head (arrow).
Fig. 3a: Image of the PCB underside of a hard drive taken with the Leica DMS1000 at lower magnification. The hard drive cable connector pins are shown at the bottom where 3 have been bent.
Fig. 3b: Zoom-in of the indicated area in Fig. 3a. The image at higher magnification shows more details of the bent connector pins.

Inspection, documentation, and analysis for product quality control (QC/QA) or development (R&D) using the Leica DVM6

As a microelectronic device, such as a hard drive, is assembled during production, off-line quality control is normally done at various  stages to minimize or even eliminate detective products which do not conform to the targeted specifications. During product development, often designs are optimized to ensure product performance and efficient production.

The Leica DVM6 digital microscope permits practical, rapid inspection, documentation, and analysis of microelectronic parts and components at the mesoscopic and microscopic scale. An advantage of the intuitive software operation and encoding of the Leica DVM6 is the ability to record multi-focus images using the Extended Depth of Field (EDOF) or Z-stack functions. Images recorded with these modes allow for easy data analysis in both 2D and 3D [4].

Fig. 4a: Image of a PCB controlling the read-write head and actuator arm of a hard drive taken with the Leica DVM6. Various 2D measurements, such as length, area, and angle, have been made on components of the PCB.
Fig. 4b: Multi-focus 3D Image of the same PCB shown above in Fig. 4a. Line profiles, height measurement, and point counting has been made on the leads of the chip and the diodes and capacitors found on the PCB.

Figure 4 above shows a portion of a PCB which controls the disk read-write head and actuator arm of a hard drive. Components,  such as chips, diodes, and capacitors, are found on the PCB, as seen in the images. Examples measurements in both 2D (Figure 4a) and 3D (Figure 4b) have been made.

Additionally, the integrated ring light, coaxial, and oblique illumination of the Leica DVM6 enables users to view hard drive parts and components with multiple contrast methods. These versatile contrast methods permit the fast and easy visualization of difficult to see features. Figure 5 above shows a portion of the underside of a hard drive, which is the bottom of a PCB. The pads, traces, through-holes, and substrate surface are seen in the images. The images were recorded with ring light (Figure 5a) and oblique illumination (Figure 5b). Different features, due to contamination, scratches, and defects, are better enhanced and more noticeable in each image.

Fig. 5a: Image of a portion of the PCB underside of a hard drive taken with the Leica DVM6 using the LED ring light and diffusor. Compare areas encircled areas and denoted by arrows with Figure 5b showing image with oblique illumination.
Fig. 5b: Image of the same portion of the PCB shown in Figure 5a. The image was recorded with the Leica DVM6 using oblique illumination. Notice the scratches and defects on the pads (arrows) and imperfections and variations on the substrate (encircled areas) become more visible compared to ring light illumination (Figure 5a).

In this image gallery you can find more application examples how the DVM6 is used in microelectronics and electronics quality control.

Precise measurement and surface analysis for product quality control (QC/QA) or development (R&D) using the Leica DCM8

Hard drives use disks, also called platters, coated with magnetic materials for data storage. During production and assembly, the disk and coating must also be inspected and quality controlled to identify those that fall outside of acceptable standards in terms of disk or coating defects, thickness variations, etc.

The Leica DCM8 microscope/optical profilometer enables documentation and precise measurement of hard drive parts and components, like the coated disk, at the microscopic and nanoscopic scale. The ability to operate in both compound and confocal microscope modes, as well as interferometry modes, allows users to attain the highest XY and Z resolution possible with an optical analytical instrument. Both high resolution microscopy and precision metrology using interferometry can be done [5].

Images of a hard drive disk surface are shown in Figures 6, 7, and 8. A microscopic dust particle (Figure 6) and fiber (Figure 7) on the disk surface, plus some of its height variations (Figure 8), most likely due to slight changes in the thickness of the magnetic film coating and contamination on the disk, are seen. The images were recorded in confocal mode (Figures 6 and 7) and phase shift interferometry (PSI) mode (Figure 8). The image data is displayed in both 2D and 3D.

Fig. 6a: 3D image of a dust particle present on the disk surface of a hard drive recorded with the Leica DCM8 in confocal mode. The height scale is shown in pseudo-color.
Fig. 6b: Maximum and mean height measurements of the dust particle seen in Figure 3a.
Fig. 7a: 3D image of a fiber present on the disk surface of a hard drive acquired with the Leica DCM8 in confocal mode.
Fig. 7b: Contour analysis of the fiber seen in Figure 7a showing width and length.
Fig. 8a: Disk surface of hard drive analyzed with the Leica DCM8 in inter- ferometry (PSI) mode. Height variations of the surface, with scale shown in pseudo-color, are seen on the order of 8 nm.
Fig. 8b: 3D display of the same interferometry data seen in Figure 8a. Results from an analysis of the surface using ISO 25178 height parameters are shown in Table 2.

ISO 25178: Height parameters

Sa

1.33 nm

Sq

1.67 nm

Tab. 2: ISO 25178 [12] height parameters measured for the hard drive disk surface image shown in Figure 8. Sa represents the arithmetical mean and Sq the root mean square of the surface height values.

Summary and conclusions

The microelectronics and electronics industry have an ever-growing demand for faster and cheaper production of devices, while meeting always improving product specifications. As a result, manufacturers need to make their process workflows more and more efficient, whether in product innovation, research and development (R&D), production, quality control and assurance (QC/QA), or failure analysis (FA). Normally, the workflow stretches from the macroscale.

State-of-the-art digital microscopes, microscopes which operate without eyepieces where the image is observed directly on a monitor, enable users to work efficiently and ergonomically. Today, they are used in the areas of R&D, production, QC, and FA. The digital microscope portfolio of Leica enables users to work efficiently and ergonomically with the goal to achieve overall cost-effectiveness. The portfolio currently consists of  the Leica DMS, Leica DVM6, and Leica DCM8 product lines. These digital microscopes can be used to optimize the entire inspection workflow from the macroscale (> 2 mm) to the mesoscale (10 mm − 25 µm) to the microscale (1000 µm − 500 nm) to the nanoscale (< 500 nm).

Results presented from a microelectronics application, the inspection, documentation, and analysis of a hard drive’s parts and components from the macroscopic to the nanoscopic level, demonstrate the practicality and usefulness of these 3 digital microscopes. Quick inspection at the macro- and mesoscale of the disk read-write head and actuator arm and underside, i.e., printed circuit board (PCB) bottom, of a hard drive has been done with the Leica DMS1000. The microscope’s very large field of view (FOV) for a wide overview and its ability to zoom in on an area of interest for more detail was exploited. Additionally, quick documentation and analysis at the meso- and microscale was done with the Leica DVM6. Multi-focus images of the hard drive using the Extended Depth of Field (EDOF) or Z-stack functions permitted easy 2D and 3D data analysis. Finally, precise measurements at the micro- and nanoscale on the hard drive disk surface were made with the Leica DCM8. The confocal microscopy and interferometry modes were used to analyze the magnetic material coating on the disk surface and identify/quantify contamination and defects, such as fibers, dust particles, and  scratches.

Table 3 summarizes the typical applications for use of the Leica DMS1000 and DVM6 digital microscopes, and the Leica DCM8 digital and confocal microscope/optical profilometer.

Digital microscope portfolio Leica – area of typical application microelectronics & electronics

Leica DMS1000 [3]

Leica DVM6 [4]

Leica DCM8 [5]

Inspection & documentation in 2D

Inspection, documentation, & analysis in 2D & 3D

Precise documentation & analysis in 2D & 3D

Macro- to mesoscale (> 2 mm − 25 µm)

  • Line production and assembly
  • In-line quality control (QC)
  • Documentation
  • Troubleshooting/failure analysis (FA)
 

Meso- to microscale (10 mm − 500 nm)

  • Product innovation (R&D)
  • Off-line quality control (QC)
  • Documentation for 2D & 3D analysis
  • In-depth failure analysis (FA)
 

Micro- to nanoscale (1000 µm − < 500 nm)

  • Surface metrology
  • Highly accurate measurement for QC
  • Precise documentation in 2D & 3D
 

Printed circuit board (PCB) components:

  • soldered leads
  • vias and bored through-holes
  • conductive and signal traces
  • conductive pads
  • chips, diodes, capacitors, resistors
 

Printed circuit board (PCB) components:

  • soldered leads
  • vias and through-holes
  • traces and pads
  • chips, diodes, capacitors, resistors
 

Solid state, semiconductor  devices:

  • integrated circuits
  • lithography
  • deposited films
  • silicon wafer surface roughness
 

Hard drive (HD) & solid state drive (SDD) components & housing

Hard drive (HD) & solid state drive (SDD) components

Organic photovoltaic devices, e.g., light-emitting diodes (LEDs)

Computer, laptop, smart phone, tablet, monitor components, displays, & housings

Computer, laptop, smart phone, tablet, monitor components

Magnetic coatings on hard drive (HD)  disks/platters

Solid state voltage adaptor, transformer, and power supply components & housing

Solid state voltage adaptor, transformer, and power supply components

Glass surface characterization for device displays

Special features

  • Large field of view (FOV) up to 94 mm diagonal
  • Zoom optics with 8:1 factor
 

Special features

  • Fast change over mag range (12x − 2,350x)
  • Hybrid stage and head tilt
  • 2D & 3D image capture modes
 

Special features

  • Confocal microscope mode with lateral resolution < 140 nm
  • Interferometry modes with vertical resolution down to 0.1 nm
 

Tab. 3: Typical applications for the Leica DMS1000, DVM6, and DCM8 digital microscopes with respect to inspection, documentation, analysis, measurement, and product innovation of microelectronics and electronics.

References

  1. DeRose J, Schlaffer G: What You Always Wanted to Know About Digital Microscopy, but Never Got Around to Asking. Science Lab.
  2. DeRose J, Schlaffer G: Work Up to 3X Faster with the Leica DVM6 Digital Microscope.
  3. Leica DMS1000 Product Page. Leica Microsystems.
  4. Leica DVM6 Product Page. Leica Microsystems.
  5. Leica DCM8 Product Page. Leica Microsystems.
  6. Smith C: Using Telecentric Optical Systems to Optimize Industrial Image Accuracy and Reproducibility: How to eliminate hidden errors in manufacturing. Science Lab.
  7. DeRose J, Schlaffer G: Inspecting and Analyzing Printed Circuit Boards Quickly and Reliably with a Digital Microscope. Leica DVM6 Product Page.
  8. DeRose J, Parma G: Fast and Reliable Inspection of Printed Circuit Boards with Digital Microscopy.
  9. DeRose J, Schlaffer G: Automotive Industry: Rapid and Precise Surface Inspection on Hard-to-Image Samples. Science Lab.
  10. DeRose J, Schlaffer G: Digital Microscopy with Versatile Illumination and Various Contrast Methods for More Efficient Inspection and Quality Control: Example applications using the Leica DVM6 with integrated ring light or coaxial illumination system. Science Lab.
  11. DeRose J, Reinhold A, Schlaffer G: Automotive Industry: How Suppliers and Auto Manufacturers Can Verify Parts Specifications Quickly and Easily: Inspecting and Documenting Automotive Parts with Digital Microscopy.
  12. ISO 25178-2:2012, Geometrical product specifications (GPS) – Surface texture: Areal – Part 2: Terms, definitions and surface texture parameters. International Organization for Standardization.

 

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