Chemical mechanical polishing (CMP) pads play a critical role in microelectronics manufacturing, where consistent surface properties are essential for reliable performance. Nanoindentation is increasingly used to characterise CMP pads at the micro- and nanoscale, providing detailed insights into mechanical and viscoelastic behaviour.
This page explores how nanoindentation is used to analyse CMP pads, including measurement techniques, key properties, and example data. In this example, the Bruker Hysitron TS 77 Select was employed to quantitatively measure the viscoelastic properties of a hard pad.
This is a robust, reliable method for examining CMP pad surface quality and processes.
Why Use Nanoindentation for CMP Pads?
Nanoindentation enables precise measurement of mechanical and viscoelastic properties at small scales, making it ideal for analysing CMP pad performance. Compared to traditional metrology techniques, it provides greater control over test parameters and more detailed insight into local material behaviour.
CMP in Microelectronics
Chemical mechanical polishing (CMP) is used in microelectronics to planarise interlayer dielectrics and metal layers. Pads are a key consumable used for polishing in the CMP process. The mechanical properties of the pad and its surface morphology affect the quality and effectiveness of polishing.
CMP Pad Measurement Techniques
Metrology techniques such as dynamic mechanical analysis and Shore’s hardness characterisation are commonly used to measure and understand the mechanical and viscoelastic properties of CMP pads. However, there are limitations to these techniques. They provide non-localised, average values of hardness and modulus for large volumes of the sample, including the pores, which are often not adequate for quality control.
Nanoindentation for CMP Pad Analysis
Nanoindentation, in contrast, measures properties quantitatively at smaller scales. There is a high degree of control over test parameters such as:
- Indenter loading and unloading rates
- Dynamic oscillation
- Peak load
- Other programmable test conditions
The results are not affected by pores on the pad surface due to the small contact area, precise targeting capability, and surface stiffness mapping.
Example: Nanoindentation of a CMP Hard Pad
This example involves measuring the near-surface properties of a commercial CMP pad, a 100 MPa “hard pad”. It uses Bruker’s Hysitron TS 77 Select, a benchtop system for automated nanomechanical testing.
Dynamic indentation was used to measure properties, including the storage modulus, loss modulus, and tan delta, as a function of depth. Large grids of indents were made using the TS 77 Select’s automated features. Statistics were then calculated, and maps of regions containing pores were generated.
Full details of the experiment are available in a Bruker application note.
Viscoelastic Properties
The graphs below show the viscoelastic properties of the hard pad, including storage modulus, loss modulus, and tan delta between 200 and 600 nm of contact depth.
Histograms
The histograms below depict the storage modulus, loss modulus, and tan delta for the hard pad at contact depths of 200 to 600 nm.
Applications in Microelectronics and Materials Research
Nanoindentation is widely used for:
- CMP pad development and optimisation
- Process control and quality assurance
- Surface and mechanical performance analysis
- Materials research in semiconductor manufacturing
Conclusion
This method can be used to quantitatively measure various properties of CMP pads, including cross-sections, to better understand pad surface quality and processes.
The set-up allows full control over indenter loading and unloading rates, peak load, and other test parameters.
Constant-strain-rate dynamic indentation tests on the top surface of the pad yielded depth profiles of the storage modulus, loss modulus, and tan delta.
By indenting away from pores and using a large number of indents, structural variation in the pad appears to produce a bimodal distribution of modulus.
These insights support improved process control, material selection, and performance optimisation in CMP applications.
Bruker Hysitron TS 77 Select
- Best-in-class, entry-level nanoindenter
- Quantitative mechanical and tribological characterisation at the nanoscale to microscale
- Essential toolkit of testing modes
- Automated routines for reliable characterisation
- Based on established Bruker technology
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Last updated: March 2026