TAU-9000 Minority Carrier Lifetime Imaging System

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The TAU‑9000 system employs pump‑probe‑based ultrafast transient spectroscopy imaging to achieve high temporal and spatial resolution characterization of wafer minority carrier lifetimes. Photogenerated carriers are excited by pump light, and their decay dynamics are measured through time-resolved imaging, enabling precise assessment of the effects of dislocations, point defects, and surface contamination on carrier lifetimes, thereby reflecting overall wafer quality. The system supports multiple wafer sizes (2″, 4″, 6″, 8″, 12″) and a range of materials including SiC, GaN, GaAs, InP, and Si, with a lifetime measurement range from <5 ns to several seconds, spatial resolution of 275 μm, and temporal resolution of 1–10 ns. A vacuum chamber prevents optical damage to the sample surface. Integrated AI algorithms enable quantitative defect density analysis and customized evaluation, allowing full-chain quality tracking from substrate, through epitaxy, to device. TAU‑9000 delivers high-throughput imaging suitable for both production and R&D, providing intuitive minority carrier lifetime maps and quantitative data. Unlike conventional microwave photoconductance decay (μ‑PCD) methods, the TAU‑9000 employs transient spectroscopy full-wafer imaging, enabling fast and high-spatial-resolution acquisition of minority carrier lifetime information. It significantly outperforms traditional μ‑PCD in terms of temporal resolution, spatial resolution, and data acquisition efficiency.
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TAU 9000

Principle

Core Advantages

Specifications

Case Examples

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Principle

The high-speed, non-destructive defect inspection technology for compound semiconductor wafers developed by TimeTechSpectra is based on photogenerated carrier dynamics spectroscopy. Under optical excitation, electron–hole pairs are generated and exhibit a characteristic lifetime in an ideal lattice. However, crystallographic defects such as dislocations, stacking faults, and point defects introduce carrier trapping and non-radiative recombination, resulting in reduced local carrier concentration and shortened lifetimes.

By analyzing the spatial distribution and time-resolved decay dynamics of photogenerated carriers, the location, distribution, and density of defects can be quantitatively characterized. This approach integrates transient absorption/reflection imaging and time-resolved photoluminescence spectroscopy, relying on excited-state absorption and radiative recombination signals, respectively, enabling high-sensitivity, high-throughput, wafer-scale inspection across materials including SiC, GaN, Ga₂O₃, GaAs, and InP.

Key Features

Utilizes ultra-fast transient optical spectroscopy imaging technology to achieve high temporal and spatial resolution
Incorporates a vacuum chamber to effectively prevent laser damage to the sample surface
Allows for separate detection of the wafer surface and bulk material by switching the excitation wavelength
Compatible with functions such as laser annealing and bipolar degradation detection
High-speed, high-throughput detection meets production line requirements

Overcoming Industry Challenges

The minority carrier lifetime of semiconductor wafers, such as SiC, is one of the key parameters indicating wafer quality. Measuring the minority carrier lifetime provides valuable insights into the point defect concentration and surface contamination by metal ions. Furthermore, as demand for high-voltage SiC devices continues to grow, the need for measuring the minority carrier lifetime of thick epitaxial wafers will also increase.

Specifications

Inspection Time	5 min/wafer (6", 8", and 12")
Lifetime Inspection Window	<5 ns to seconds
Spatial Resolution	275 μm (6", 8", and 12")
Inspectable Samples	SiC、GaN、GaAs、InP、Si
Temporal Resolution	<1 ns to 10 ns
Compatible Sample Size	2"、 4"、 6"、 8"、12"
Point defect concentration, surface contamination, carrier lifetime, and lattice quality evaluation
Equipped with a vacuum chamber to prevent laser damage to wafer surfaces

Case Examples

Differing from the conventional μ-PCD technique, the TAU-9000 series uses transient spectroscopic full-wafer imaging to capture minority carrier lifetime data at high speed and with high spatial resolution, far exceeding traditional μ-PCD in key metrics like temporal resolution, spatial resolution, and throughput.

	TAU-9000	Conventional μ-PCD
Testing Principle	Pump-probe full-wafer single-shot imaging (High Efficiency)	Microwave Photoconductivity Decay (μ-PCD) Point-by-Point Scanning
Excitation Wavelength	355 nm / 266 nm	349 nm (Single Wavelength)
Temporal Resolution	< 5 ns (SiC)	> 30 ns
Spatial Resolution	275 μm	>1mm
Scanning Time	< 5 min/wafer	~90 min @ 0.5 mm Step Size
Max Wafer Size	12"	8"

TAU 9000-EX-1

TAU-9000 Minority Carrier Lifetime Imaging System.pdf

TAU-9000 Minority Carrier Lifetime Imaging System

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