SURAGUS – High-Frequency (HF) Eddy Current Technology
SURAGUS are specialists in high frequency (HF) eddy current testing systems. A wide measurement frequency range from 10 kHz to 100 MHz enables the characterization of diverse materials ranging from thick metal films to highly resistive semiconductors; all with only a single system. Additionally, frequency modulation enables penetration depth variation, which provides insight into vertical resistivity profiles.
With strong competence in designing and manufacturing non-contact eddy current sensors, SURAGUS solutions characterize single or multilayers in three modes: frontside reflection mode, backside reflection mode and transmission mode.
Double-side transmission mode sensors and tools operate in large distances to the wafer and excel with high tolerance to vertical wafer surface positions. This means the same set can be used for immediate measurement of thin and thick wafers without requiring time consuming set up changes. With large sensor elements gaps up to 100 mm makes double sided transmission ideal for robot handling and the integration into process tools without requiring additional tool space or processing time.
An alternative and superior to 4-Point Probe (4PP) testing of conducting and semi-conducting layers
One of the most important quality parameters that determines the electrical characteristics of conductive coatings and substrates is sheet resistance (Rsor R). Sheet resistance (typically stated in Ω/sq or Ohm/sq) is a measure of the electrical resistance of thin layers. It is the main physical parameter for describing the electrical performance of electrodes. The sheet resistance Rs correlates with the material thickness if the bulk resistivity can be assumed to be constant. The formula is Rs = ρ/t
There are two different modes to measure the sheet resistance – non-contact and contact. Most popular are the following technologies:
Non-contact: Eddy current
Contact: Two-point Probe, Four-point probe (4PP), Hall effect, Van der Pauw
The eddy current testing method is a non-destructive evaluation method that allows accurate measurement without impacts due to inhomogeneous contact quality, without damaging any sensitive surface or inducing artefacts due to contacting. Applying noncontact technology, there is no wear of needles or tips, which typically causes high replacement costs in common 4-point-probe mapping systems. A further significant advantage is the short measurement time. A measurement takes only a few milliseconds for each measurement and no time for contacting the sample is needed. This also allows to measure inline during production or “on the fly” in mapping systems. In result, the eddy current sheet resistance mapping systems measure thousands of positions in a couple of seconds. No interpolation between measurements points as typical in 4-point-probe mapping systems is required. Hence, defects and nonuniform areas can be identified. Furthermore, it allows the accurate measurement of single and multilayer systems which includes inaccessibly buried or encapsulated layers.
Their solutions contribute to a sustainable use of resources in various industries. SURAGUS solutions for process control and quality assurance support efficient production processes with highest product qualities at high throughput and low scrap rates. Moreover, it is important to them that they offer an inspiring, professional work environment to their staff, which provides freedom for self-actualization as well as security and flexibility for their families.
SURAGUS provides non-contact metal metrology process control measurements of the metallization uniformity. Often, SURAGUS tools achieve much lower tolerances as compared to alternate methods. As a result, it is stable at much higher frequencies and significantly more stable over time. There are also several benefits over alternative methods:
It is non-contact.
After the initial calibration, it can be used in SPC mode.
It can determine thin film thickness if sheet resistance is known.
It can provide an end point measurement of Cu plating removal during CMP.
Metal tool qualifications after PM.
Eliminates these types of problem with contact measurements:
Four-point probe can have issues with metal contamination (from metal films to bare substates)
Cross contamination from monitoring different metals
Changing probe conditions which can lead to erroneous and inconsistent data
SURAGUS tools can provide effective characterization of CMP processes. Mapping of layer thickness values provides a damage free way of determining thin film uniformity based on material resistivity. From hand-held tools to full mapping systems, SURAGUS can configure non-contact metrology that allows one to get closer to the edge of the wafer, thereby maximizing the number of sellable die per wafer. From there, sophisticated and modern software makes the system easy to use and especially well suited for engineering investigations.
We encourage customers to put SURAGUS to schedule an initial online consultation, to be followed if appropriate by no charge sample testing of your material, and a comprehensive written report of the findings.
About E Test Reps:
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