Leading products in optical metrology Made in Germany

Overlay

Overlay is the process of aligning one layer of a process stack to the subsequent layer. The overlay error is the shift between those two layers. An overlay specification was created by international SEMATECH to better understand the issues facing optical metrology and to determine the best way to analyze a tool set. The methodologies include: measurement of precision (repeatability and reproducibility), determination of throughput, accuracy, through focus measurement, and Tool-Induced Shift (TIS) variability. The measurement of the overlay is executed at two structures which were produced in different, separate production steps and which in most cases consist of different materials. 

Common test structure

A very common test structure to measure the overlay is a box-in-box structure. In preparation for a precise overlay measurement, the software has to recognize or say “learn” the approximate center position and the borders of the inner and the outer box, to define the ideal measurement parameters. This learning procedure is comfortably supported by a single mouse click in the NanoStar software. The result of the learning routine is then displayed in the so called IP Window as shown on the right. Besides box-in-box test structures, the MueTec Tools measures also frame-in-frame, L-bars, circle in circle, cross in cross or any other kind of customized overlay features. Nowadays several other types of structures are in use to measure the overlay parameter. 

Advantages of Muetec Systems

The MueTec systems - if equipped with infrared illumination – are able to measure overlay top-to-bottom outside and also inside the substrate.

The overlay application makes it possible to measure wafers with very low contrast appearing in manufacturing processes like STI (shallow trench isolation), and CMP (chemical mechanical polishing) using proprietary algorithms.

A homogeneous objective lens with a Strehl value of better than 0.98, selected especially for overlay demands, guarantees homogeneous images for better performance.

To optimize the overlay measurement performance to its utmost level, tool parameters like illumination homogeneity and optical quality of the objective lenses are automatically corrected. This so called Tool Induced Shift (TIS) of the results is corrected automatically using the automated TIS correction. These parameters for this correction are recorded once by reference measurements on each type of wafer during the job setup and are then automatically used to calculate the corrected overlay results for each measurement.

 

MueTec has put a lot of effort into resolving these key issues. The outcome is a user friendly, advanced overlay measurement tool with highest precision and throughput, best repeatability and grade of automation and lowest TIS.

Box-in-box test structure layout


Nowadays several other types of structures are in use to measure the overlay parameter. Below are just two examples:

Cross in cross layout


Circle in circle layoutt

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MT3000
Fully automated metrology and inspection system (open cassette)

Typical Applications

CD
Overlay
Film Thickness
Defect Inspection
Defect Review


Features

VIS, UV

Simultaneous wafer handling 75 - 200mm

SECS/GEM

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MT2010
Fully automated metrology and inspection system (open cassette)

The MT2010 is designed for high precision defect inspection and metrology tasks on masks up to 6”. The system uses different illumination sources in transmitted and reflected light such as visible, I-line (365nm) and DUV (248nm).

MT2010 comes with laser autofocus and an anti-vibration isolating base frame with light tower.

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Spector-A
Fully automated mask metrology and inspection system

Typical Applications

CD
Defect Inspection


Features

Mask sizes up to 8“ by 8“

Robot handling

SECS/GEM

VIS, UV

Also available as semi-automated system with manual mask loading (Spector-M)

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MT8300
300mm metrology and inspection system (FOUP/SMIF)

Typical Applications

CD
Overlay
Film Thickness
Defect Inspection
Defect Review
300mm and 200mm wafer sizes
SECS/GEM
VIS, UV 

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MT5500 / MT7500
Large area metrology and inspection system

Features

CD > 0,3 micron

contact holes > 0,3 micron

chrome and phase shift

resist on chrome

line edge roughness

substrate size up to 550mm x 550mm

DUV, 248nm; UV 365nm

DUV, UV, VIS

reflected and transmitted light

 

Substrates

large area scales

plastic electronics

glass scales

special customized solutions

Individual Inquiry

Contact

MueTec Europe

Headquarter

+49 89 1500 169 0

info@muetec.com

Hans-Bunte-Str. 5
80992 Munich / Germany

 

 

Manufacturing

+49 9938 9191-0

info@muetec.com

Isarauer Str. 77
94527 Aholming / Germany