Pre Purchase FAQs

What is the benefit of the Atomic Force Probe (AFP) to the market?; What is an Atomic Force Microscope (AFM)?; What is a MultiScan™ AFP probe?; Can I image and probe high aspect ratio samples?; Are the tips fragile and expensive?; What is the advantage of using wire tips?; What is force feedback, and why is it important?; How do I position the probes?; Can I probe multiple, tight geometry nodes?; How does MultiScan™ software help me probe?; How do MultiScan probes help companies meet their objectives?; How does a MultiProbe AFP II nanoprober improve productivity of the engineering staff?; Who should buy this solution?; What is the value of this solution over other submicron node probing alternatives?; What is the benefit of the Atomic Force Probe (AFP) to the market?
Leading semiconductor device companies have pushed their chip technology beyond the limits of optical microscopy-based testing techniques. This turnkey system enables the rapid development of future generations of nano-scale geometry devices.; What is an Atomic Force Microscope (AFM)?
An AFM uses nanometer resolution actuators to scan a tiny probe on a surface while maintaining force control. Force-feedback-control loops maintain a constant deflection and therefore a constant force between the probe and the surface. Tools that do not use force feedback are not AFMs and risk increased contact force as the probe deflects over features, which can cause damage to both the sample and probe.; What is a MultiScan™ AFP probe?
The MultiScan™ AFP probe is the world’s highest resolution contact nanoprobing tool which permits imaging of nano-scale circuit features without damage, while allowing enough contact force to make secure and reliable node contacts for accurate test measurements. The AFP consists of an AFM head specialized for use with robust solid tungsten probe needles. The MultiScan™ user interface allows the operator to simultaneously control and probe with multiple heads.
Back to Top: Can I image and probe high aspect ratio samples?
The tungsten wire probe tip has another distinct advantage over traditional AFM probe tips. The tip is long enough to reach into apertures and over multiple metal layers to contact and image high aspect ratio lines.; Are the tips fragile and expensive?
The tips are easy to replace and quite robust, permitting the user to make multiple measurements with each tip.; What is the advantage of using wire tips?
Conventional AFM probe tips are made in three main types: silicon, silicon with metal coatings, and deposited metal in the shape of a tip. Each of these types of tips have serious drawbacks when used for contact node probing. Silicon is an unsuitable material for making contact to nodes, forming a schottkey diode in place of ohmic contact, which distorts measurements and should not be used in conducting high-frequency or low-current signals. During scanning and contacting, tips naturally experience some wear. However, metal coatings on silicon tips wear off too quickly and leave an intrinsic diode at the contacting tip. Deposited metal tips are typically made with materials that are unable to contact hard metals like tungsten vias.
Unlike the other three alternatives, tungsten wire tips are extremely hard and have been used successfully for years to probe all electronic materials. There are no junction or ohmic contact issues and the tips will not interfere with sensitive or high-frequency measurements.
Back to Top: What is force feedback, and why is it important?
When contacting a surface, the tip of the probe is deflected a few nanometers and this probe deflection is measured with an optical beam. As the probe tip scans over the chip’s surface features, a force-feedback loop adjusts the height of the piezo actuator to compensate for the height of the feature. The probe tip is automatically lifted by the feedback loop to maintain a constant deflection and therefore a constant force between the tip and the surface. In this way, the deflection of the probe during imaging is be kept quite small (a few nanometers). Wth force feedback,the probe tip can have a high spring constant and still not apply large forces to the sample while imaging
Without force feedback, the contact force changes as the probe tip deflects while scanning over features. Therefore, to avoid damage the tip must be extremely soft. Why not just use a soft tip? In order to be able to conduct electrical tests, the tip must also be able to generate considerable force to break though oxides or reliably contact tungsten vias. Without force feedback, the user must sacrifice either sample damage or ohmic contact. With force feedback the user sacrifices nothing.; How do I position the probes?
The probes are designed so that the tips are visible in the station optics. Gross mechanical positioners are used in the normal way to bring the AFP probes to the target. The required positioning accuracy is dramatically lowered since the MultiScan™ software positions the probes with ultra-high-resolution piezo stages.; Can I probe multiple, tight geometry nodes?
The probe tips are manufactured to be the furthest extent of the probe allowing them to be placed within a few radii of each other.
Back to Top: How does MultiScan™ software help me probe?
The software that controls the multiple AFP units allows the operator to simultaneously image the surface with all of the probes and locate the desired node to be probed. The probing is done by placing a cursor representing each probe tip over the nodes to be contacted. Contact force can be adjusted and specified for each contact. All probe images can be overlaid and registered to facilitate node location. This feature-rich software platform forms an ideal environment that can be customized to suit special requirements.; How do MultiScan probes help companies meet their objectives?
Implementation of the MultiScan™ AFP Probe with its AFM capabilities provides semiconductor companies with:; These factors contribute to reducing a manufacturer’s time-to-market for their next-generation devices.; How does a MultiProbe AFP II nanoprober improve productivity of the engineering staff?
The MultiProbe AFP II nanoprober system use of a closed-loop-positioning system coupled with AFM performance allows for the rapid imaging of deep-submicron features and ensures reliable contact with minimal set-up. This atmospheric solution makes submicron probing possible in any FA lab without the disadvantages of vacuum-based probing options.; Who should buy this solution?
Any company that needs to probe submicron features would benefit from this solution, especially if the lab needs to force or sense currents and voltages as in transistor characterization or mixed-signal products. Moreover, the system can be used to isolate individual cells within arrays to characterize single bit failures.
Back to Top: What is the value of this solution over other submicron node probing alternatives?
Other alternatives fall into two categories: traditional optical-based techniques and vacuum-based options like E-beam and FIB solutions. While it is possible to use optical-based techniques to 0.25µm, fundamental barriers remain. Typical submicron probing using optical techniques is time-consuming and difficult. Most test analysts would be more productive if they could concentrate on their applications and not on placing probes. Vacuum-based solutions require very expensive equipment, a highly trained staff, and long set-up times. The E-beam of SEM based solutions cause a shift of the electrical properties of the device being analyzed. For a detailed comparison see the AFP vs. SEM technical note.