alpha300 Semiconductor Edition

Brochure

App Note

Large-area wafer inspection for the semiconductor industry

The alpha300 Semiconductor Edition is a high-end confocal Raman and photoluminescence (PL) microscope specifically configured for the chemical imaging of semiconducting materials. It helps researchers accelerate the characterization of crystal quality, strain and doping in their semiconductor samples and wafers.

The microscope’s extended-range scanning stage enables the inspection of up to 12 inch (300 mm) wafers and the acquisition of large-area Raman images. It is equipped with vibration damping and active focus stabilization to compensate for topographic variation during measurements over large areas or long acquisition times. All microscope components are fully automated, permitting remote-control and the implementation of standard measurement procedures.

Request Pricing Add to quote list View this product on your quote list

Benefits

Full inspection of up to 300 mm (12 inch) wafers
Non-destructive characterization of crystallinity, polymorphism, defects, strain and doping
Analysis of wide-bandgap semiconductors and layered structures
Surface analyses, depth scans and 3D imaging

3D defect analysis

Raman imaging is able to distinguish polymorphs and characterize crystal defects below the sample’s surface. This 3D Raman image reveals the origin of a defect in a 4H-SiC wafer and identifies it as the 3C-SiC polymorph. Read more in our application note: Correlative Raman Imaging of Compound Semiconductors

3D Raman image of a defect in a SiC wafer

3D Raman representation of a defect in an epitaxially overgrown SiC wafer. Blue: defect, red: epitaxial layer, green: wafer substrate. Dimensions: 240 x 240 x 12 μm³

Key features

Industry-leading confocal Raman and PL microscope for high speed, sensitivity and resolution – simultaneously
Scientific-grade, wavelength-optimized spectrometer for high signal sensitivity and spectral resolution
Large-area scanning (300 x 350 mm) for wafer inspection
Active focus stabilization for large-area measurements (TrueSurface)
Vibration damping
Extensive automation for remote-control and recurring measurement workflows
Software for advanced data post-processing

alpha300 Semiconductor Edition – Confocal Raman imaging microscope for wafer inspection

Large-area wafer inspection

Monitoring the quality of wafers is critically important for the semiconductor industry. In order to establish the homogeneity of the material and reveal areas of strain or inhomogeneous doping, the entire area of a wafer must be investigated.

In this example, the complete surface of a 150 mm (6 inch) silicon carbide (SiC) wafer was imaged with Raman microscopy using a 532 nm laser for excitation. The analysis showed that the doping concentration was not homogeneous over the full area. The microscope‘s highly sensitive UHTS 600 spectrometer was able to detect peak shifts below 0.01 cm^-1 and could thus reveal stress fields within the wafer.

To obtain a sharp Raman image of the entire wafer, actively keeping the surface in focus was crucial. TrueSurface recorded the wafer’s topography simultaneously with the Raman data and compensated for height variations.

Read more in our application note: Correlative Raman Imaging of Compound Semiconductors

Sample courtesy of the Fraunhofer Institute for Integrated Systems and Device Technology IISB, Erlangen, Germany.

Confocal Raman image of a 150 mm SiC wafer. TrueComponent Analysis identified two spectra, which mainly differed in the doping-sensitive A1 peak (ca. 990 cm^-1). The image reveals an oval region (blue) with a different doping concentration than the bulk wafer area (red).

Raman spectra identified in the 150 mm SiC wafer

Raman spectra of the two components identified in the 150 mm SiC wafer by TrueComponent Analysis.

Confocal Raman image of a 150 mm SiC wafer, color coded for the position of the stress-sensitive E2 peak (776 cm^-1). The image reveals a small, presumably stress-induced peak shift from the wafer’s center toward its edge.

Topography of a 150 mm SiC wafer with height variations of up to 40 µm.

Photoluminescence (PL) imaging

With the alpha300 Semiconductor Edition, you can perform PL measurements to complement your Raman analyses. This is particularly interesting for investigating wide-bandgap semiconductors such as SiC or gallium nitride (GaN). The PL emission wavelength serves as an indicator for the material’s electronic properties, including its bandgap.

This PL image of a SiC wafer shows differences in PL properties, revealing defects. Read more in our application note: Correlative Raman Imaging of Compound Semiconductors

PL image of defects in a 4H-SiC wafer. PL spectra show characteristics of 4H-SiC (red), 4H-SiC with stacking faults (blue, green) and 3C-SiC (yellow, cyan).

Topographic Raman imaging

Topographic Raman image of micro-structured silicon (blue) with fluorescent impurities (pink). Chemical and profilometric information were recorded simultaneously by TrueSurface technology and overlaid. The maximum height variation was 9 µm.

Layer characterization

Raman imaging provides insight into the sub-surface properties of layered semiconducting materials. This depth scan through an epitaxially overgrown SiC wafer visualizes the distribution of its different layers.

Raman depth scan of an epitaxially overgrown SiC wafer, showing a thin interface layer (blue) between the wafer substrate (green) and epitaxial layer (red).

Sample courtesy of the Fraunhofer Institute for Integrated Systems and Device Technology IISB, Erlangen, Germany.

2D materials analysis

Novel 2D materials are of increasing interest for their unusual structural, electronic and optical properties. Correlative Raman imaging enables thorough characterization of these few- to single-layered materials, including graphene and perovskite, as well as molybdenum disulfide (MoS₂), tungsten diselenide (WSe₂) and other transition metal dichalcogenides (TMDs).

Learn more in our Application Notes:

Characterization of a WSe₂ flake. A: bright-field image. B: high-resolution Raman image (102,400 spectra acquired in about 17 minutes), distinguishing single-layer (red), bi-layer (green), and multi-layer (blue) areas. C: photoluminescence image with visible grain boundary (white arrow).