More Moore - highly complex microchips are ubiquitous

Microsystems technology has now become the omnipresent cross-sectional technology and growth continues. It is present in all sectors: whether in health care applications, sensor technology in digital cameras, gyroscopes for stabilizing aircraft such as helicopters, in active loudspeakers, or for controlling video games.

Moore's Law

The complexity of integrated circuits is growing at a remarkable rate. Moore's Law states that the complexity of integrated circuits doubles regularly with minimal component costs; depending on the source, 12 to 24 months are cited as the time period (source: Wikipedia).

This is currently a considerable challenge for the industry, because the higher complexity is associated with constantly changing requirements for production parameters, process control and quality assurance. In the last years, optical surface measurement in the form of multi-sensor measuring tools has shown to be capable of growing with the new requirements and to develop corresponding solutions to market maturity in a short time.

The preliminary product "wafer”

The manufacturers in the fields of microelectronics and microsystems technology have extremely high demands on the preliminary product "wafer". Even small deviations in the manufacturing tolerances can influence the quality in the downstream, cost-intensive process steps. The result would be a loss of yield and reduced efficiency and reliability of the end products. In a market where competition is so intense, economic success depends primarily on product quality. Process tolerances must be continuously monitored during roduction. Manufacturers rely on high-quality multi-sensor measurement technology for this task. With innovative solutions, it contributes to maintaining the required very high quality standards. The measuring instruments already have a central function in research and development. They create the basis for new products and manufacturing processes. Highest precision is required especially for the so-called thin wafers used to manufacture the 3D IC assemblies that are establishing themselves on the market. The manufacturing tolerances here are in the range of a few micro- or even nanometers.

Standard and special measuring tasks

Particularly in the MEMS industry, a multitude of measurement tasks usually have to be performed due to the high product complexity. In addition to standard measurement tasks such as the determination of roughness, contour, topography and layer thickness, there are also special measurement tasks such as the measurement of membrane deflections or the parallelism measurement of periodic structures. These measurement tasks cannot be performed with a single sensor. Innovative multi-sensor measuring tools are required to measure in different measuring ranges and on different materials and material combinations.

Through Silicon Vias and their Aspect Ratio

Completely new challenges for measurement technology in terms of resolution arise, especially in microsystems technology, where 3D IC and 3D chip stacks are becoming more and more important. In 3D IC manufacturing technology, individual chips are interconnected by stacking and connecting in a vertical direction to form packages. The technology is highly interesting and very attractive, especially for microsystems technology, as it allows heterogeneous chip structures, consisting of electronic circuits and mechanical elements, to be implemented in the smallest possible space. The individual chips stacked on top of each other are connected via so-called Through Silicon Via Interconnects (TSV). They are micrometer-sized contact holes that are produced at defined positions on the wafer by means of etching in the form of dimples. During subsequent wafer thinning, a part of the wafer surface is removed so that contact holes for the electrical circuit are created from the cavities. The diameter of these contact holes (TSVs) is continuously reduced, the etching depth even increases - both have to be measured, but this is a challenge for conventional methods. The problem is the high aspect ratio, i.e. the ratio of the diameter of the hole to be measured to its depth.

The technical solution

FRT uses an interferometric optical sensor that reliably measures the surface area and characterizes the TSV at high speed.

Which sensor is best suited depends on the material to be measured, its properties or the available measuring time. As a manufacturer of multi-sensor measuring systems, FRT offers e.g.

-      chromatic white light sensors,

-      infrared layer thickness sensors,

-      thin layer sensors,

-      confocal microscopes,

-      white light interferometers or

-      atomic force microscopes with resolutions in the sub-nanometer range

to name just a few.

The possibility of determining the required parameters in a single fully automatic multi-sensor tool not only saves valuable installation space in the production environment. The time required for process control is also reduced because the handling of the wafers can be reduced to a minimum. Furthermore, the modular and expandable design of the systems makes them particularly future-proof investments.

With the MicroProf® AP FRT offers a fully integrated measuring solution with robot-supported wafer handling, recipe creation, automatic evaluation of measurement data, mini environment including EFEM and a SEMI-compliant SECS/GEM interface for the connection to the Fab Host. Thanks to the modular multi-sensor concept, the MicroProf® AP can keep pace with the ambitious roadmaps of the industry.

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