DHEM Differential Hall Effect Metrology

Introduction of DHEM

Optimizing device performance in semiconductor technology requires a thorough understanding of the electrical characteristics of surface layers. A non-destructive technique for accurately characterizing the electrical properties of semiconductor surfaces and thin films is differential hall effect metrology or DHEM. DHEM uses the Differential Hall effect and the Van der Pauw approach to evaluate a semiconductor sample’s sheet resistance and mobility at different depths. This method is essential to producing semiconductors, process control, and material science. DHEM relies on iterative etching and traditional Hall effect measurements. The active carrier profile is measured without assuming carrier movement. Additionally, measurements are taken by peeling the material in steps rather than beveling the surface. MaTestLab is one the leading testing service providers in the USA and Canada. We have an extensive network of testing laboratories in the USA.

Principle and Methodology of DHEM

DHEM utilizes a mesa pattern on the semiconductor sample to create an electrically isolated test area. The mesa pattern features four electrical contacts at the corners, forming a Van der Pauw cross. By adjusting the size of the test region, typically ranging from 0.5 mm × 0.5 mm to 2 mm × 2 mm, the collected data becomes representative of the area under investigation. The mesa design, which has an insulating barrier at the bottom of the test region, electrically isolates the test area from the surrounding bulk of the sample.

DHEM employs chemical or electrochemical etching or oxidation processes to probe successive layers within the sample. A small process chamber nozzle is sealed into the test region to deliver chemical solutions, DI water, or nitrogen gas for etching or oxidation. Sheet resistance and mobility measurements are conducted on each layer exposed by the etching or oxidation. The collected data was analyzed to obtain depth profiles of mobility, carrier concentration, and resistivity providing valuable insights into the electrical properties of the semiconductor sample.

The electrochemical etching/oxidation process in DHEM requires precision and control to ensure accurate measurements. Different chemical recipes and process selections are applicable for various materials, allowing for tailored characterization of semiconductor surfaces and thin-film interfaces.

Instrumentation

Differential Hall Effect Metrology (DHEM) equipment typically comprises the following fundamental components, namely: Hall Sensors, Magnetic Field Source, Sample Holder, Temperature Control System, and Control and Measurement Software.

Applications and Significance of DHEM

Applications for DHEM are numerous in sectors of study and industry that demand an in-depth understanding of the electrical characteristics at thin-film interfaces or semiconductor surface layers. DHEM can be expanded to characterize metal/semiconductor or insulator/semiconductor interfaces in addition to semiconductor films by creating customized recipes. Because of this feature, DHEM is a valuable tool for developers, process control engineers, and semiconductor manufacturers who want to maximize the performance of their devices and material attributes. Differential Hall Effect Metrology’s industrial uses include creating and producing semiconductors.

Differential Hall Effect Metrology’s Common Applications

•  Maximizing activation of dopants
• Ultra-thin junction evaluation
•  Optimization of the epilayer
•  Examining the links between composition, defectivity, stress, and mobility in layers like the n- and p-well areas

Differential Hall Effect Metrology’s Benefits

• The automated DHEM method has a high-depth resolution of less than 1 nm.
• The technique can be widely used at a reasonable cost.
• Differential Hall Effect Metrology’s Drawbacks
• The accuracy and controllability of the layer removal process determine the depth resolution of the data derived from DHEM.
• It is a destructive testing technique. An etching/oxidation development recipe must be established to characterize each type of material.

Limitations of Differential Hall Effect Metrology (DHEM)

• DHEM setups require precise control over experimental parameters, making implementation challenging.
• Accuracy and reliability of DHEM measurements can be influenced by sample quality and preparation.
• DHEM measurements are sensitive to environmental factors like temperature variations, stray magnetic fields, and electromagnetic interference.
• The size of the Hall probe or spacing between measurement points can limit the spatial resolution of DHEM measurements.
• Interpreting DHEM data can be complex, especially for heterogeneous materials or systems with nonlinear behavior.
• DHEM measurements are typically performed on small-scale samples or thin films, limiting applicability to bulk materials or larger structures.
• DHEM may not be suitable for all types of materials or systems.
• The equipment and expertise required for DHEM measurements can be costly and not readily available in all research facilities.

Related Techniques

The techniques that are related to DHEM are as follows

• Magnetotransport Measurement
• Magneto-optical Kerr Effect (MOKE)
• Faraday Effect measurements
• Magnetoresistance Measurement