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Film Thickness Measurement System

The thickness of the epitaxial layer, substrate, etching (residual layer), liquid crystal cell gap, and other semiconductor layers dramatically impacts semiconductor device performance. Management of layer thickness during the manufacturing process is extremely crucial for production of large yields of stable devices.

JASCO's film-thickness measurement system is a nondestructive, non-contact analysis method using the latest interferometric technology to provide rapid film thickness measurements. Utilizing a proprietary frequency analysis method, the sample interference spectrum is converted to a spatialgram and the film thickness calculated with a high degree of accuracy. This integrated system offers the film thickness measurements required for the exacting standards of the semiconductor industry including high-speed sample mapping; a wide thickness measurement range; and a refined operating environment, supporting a wide range of analysis requirements from process use to R&D. JASCO offers near-infrared and mid-infrared models according to the thickness measurements desired.

System Features

  • Wide thickness measurement capability
    Enables film thickness (substrate thickness) measurements from 0.25 to 750 µm.

  • Highly accurate thickness measurements
    Acquisition of precision data using a high-accuracy interferometer and high-throughput optics.

  • Support for multi-wafer cassettes
    Optional automated cassette sampling system, enabling fully automated measurement for wafer cassettes.

  • Simplified operating system
    Various conditions for measurement, mapping, and film thickness calculations are configured as preset recipes and managed in a recipe table. Measurement of film thickness is initiated by simply selecting a required method from the recipe table and clicking the Measure button.

Intuitive Software for Film Thickness Measurements

1. Measurement information
Input information for an analysis.
2.

Fringe spectrum
The cycle of the interference spectrum changes according to film thickness.

3. Point map
Displays the measurement positions.
4.

Spatialgram
Calculates accurate film thickness from the peak position.

5. Film thickness distribution graph


High Measurement Reproducibility

The following table shows consecutive measurement results for a Silicon epitaxial layer.
The error of 10 consecutive measurements is less than ±0.001 µm. These figures demonstrate the extremely reproducible film thickness measurement capability.

Reproducibility of consecutive measurements

Measurement No. Measured Value (µm) Devitation (µm)
1 4.9001 -0.0013
2 4.9014 0.0000
3 4.9010 -0.0004
4 4.9019 0.0005
5 4.9015 0.0001
6 4.9018 0.0004
7 4.9011 -0.0003
8 4.9014 0.0000
9 4.9017 0.0003
10 4.9021 0.0007
Average value (µm): 4.9014
Standard devitation (µm): 0.0006


Specifications

Measurement method FT-IR interference method for film thickness measurements
Measurement configuration Reflection
Objectives

Near infrared: Lens objectives (4X, 12.5X) and Cassegrain objectives (15X, 30X) Mid-infrared: Cassegrain objectives (15X, 30X)

Focus mechanism
11 mm stroke
Sampling area
20 x 20 to 1200 x 1200 µm
Sample positioning
Verification of measurement area using an integrated CCD camera
Measurement range/accuracy
Film thickness
0.25 to 750 µm (for Si)
Reproducibility ±0.005 µm or less (for Si with identical measurements)
XY stage
Stage movement
200 x 200 mm (Other options available)
Minimum step size
2 µm
Data processing unit
Operating System
Windows 98, NT, 2000 and XP
Monitor
15-inch LCD
UPS(Uninterruptible Power Supply)
Maintains PC and display power for 15 minutes after a power failure
System control
JASCO Spectra Manager software; Optics and X-Y stage control; Wafer cassette system control (option)
Table
Type
Integrated vibration isolation table
Dimensions
1240 x 810 x 1550 mm (excluding protrusions or optional cassette loading system)
Power requirement 300 VA


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