highlights in this page

SINTEF-Heliosi Characterization

SINTEF

[Cheetah Partner]

Silicon characterization, including raw material, ingot and wafer characterization

Technical Info

MAIN FEATURES :

Sample preparation:

SINTEF has:

in-house laboratories dedicated for sample preparation, such as cutting, grinding, mechanical- and chemical polishing of wafers and other samples.
The state of the art etching facilities includes two etch benches dedicated for silicon etching with automatic filling and careful temperature control for chemical polishing, defect etching and texturisation as well as dissolution of silicon matrix to study inclusions

Structural properties of mc-Si:

the laboratories include:

an extensive electron microscopy laboratory with both SEMs and TEMs and other specialised instruments, for studying microstructures in mc-Si ingots, blocks, wafers and other samples.
The use of large scale mapping techniques (such as PVScan for mapping of dislocation densities, high resolution EBSD for grain orientations maps of areas up till 5x5 cm2 and IR camera) combined with several high resolution techniques and accurate sample preparation (including FIB) makes it possible to map structures of interest throughout a whole ingot as well as study features in detail.

Structural properties of mono-Si:

Characterization of defects in monocrystalline silicon requires a different set of dedicated techniques as compared to multicrystalline silicon. To detect voids, interstitials and oxygen precipitates, the following techniques are available in SINTEF laboratories.:

Flow pattern defects (FPD
FCu decoration
FOxygen induced stacking fault (OiSF)

Chemical analysis:

SINTEF laboratories can measure:

dopants and metallic impurity elements in silicon matrix of solid- or dissolved samples on a 0.1 ppbw level (GDMS and high resolution ICP-MS, respectively).
Oxygen and Carbon concentrations are measured by FTIR and LECO.
Impurities may form inclusions and precipitates , and these are detected and measured with respect to the types, forms and density of inclusions by:

1. Near IR screening of Si blocks

2. PVScan on polished wafers

3. SEM with Energy Dispersive

4. Spectroscopy detector

Electrical properties:

Properties such as resistivity (4pp) and minority carrier lifetime (QSSPC and CDI), are measured on a macroscopic scale where whole wafers or other large samples aremapped with respect to the property of interest. On a microscopical scale (probe electricalstructure), electrical properties can be measured by:

1. Electron Beam-Induced Current (EBIC)
2. Photoluminescence Spectroscopy (PLS)
3. X-ray photoelectron spectroscopy (XPS)
4. Auger Spectroscopy (AES)

Characterization equipment relevant for mechanical properties of wafers:

At SINTEF laboratories, standard techniques, such as 4 point bending test, have been adapted for silicon wafers. Bending tests of wafers have also been developed for use with near IR ellipsometry for in situ inspection. Further, a high speed (visual light) camera, that is ableto take up to 500 000 frames/second can be used e.g. for inspection of fracture initiation point and fracture propagation in 4-point bending test. Acoustic emission is also used for sensing of microcracking during e.g. handling operations on wafers.

Surface metrology:

A finite focus microscope makes us able to create 3D images of surfaces,allowing for detailed measurement of roughness, TTV etc. The lateral resolution is 400 nm and the depth resolution is 10 nm.

LIMITATIONS OR CONSTRAINTS:

The access will be allowed with technical and scientific assistance from SINTEF in the frame of joint projects and agreement between parties

TYPICAL SERVICES OR RESULTS:

SINTEF laboratores are able to follow one defect or type of defects from macroscopical scale down to atomic scale. Typical services are: