Semiconductor metrology instruments are designed for wafer and thin film in-line inspection after semiconductor processing. Today, semiconductor manufacturing follows very strict standards and must accommodate very small dimensions. The resulting quality control (QC) procedures and semiconductor inspection processes have resulted in the development of high-precision semiconductor metrology instruments. Many of these devices and systems use a combination of laser, optical, and electron beam technologies. As a result, these semiconductor metrology instruments can help improve quality and output at every stage of production. By using semiconductor metrology instruments, manufacturers can facilitate semiconductor inspection, reduce manufacturing costs, and shorten the product development cycle.
Types of Semiconductor Metrology Instruments
There are many different types of semiconductor metrology instruments. Examples include wafer probers, imaging stations, ellipsometers, and CD-SEMs. A wafer prober is used to test a semiconductor wafer before it is separated into individual dies or chips. An ellipsometer determines the properties and surfaces of thin films by measuring material characteristics such as layer thickness, optical constants, surface roughness, composition, and optical anisotropy. A critical-dimension scanning electron microscope or CD-SEM is used to ensure the stability of the manufacturing process. These semiconductor metrology instruments can be used to monitor features such as line, space, and pitch; roundness or concentricity; or depth or sidewall measurements.
Semiconductor metrology instruments include ion mills, C-V systems, interferometers, source measure units (SME) magnetometers, optical and imaging systems, and profilometers. An ion mill is used to prepare heterogeneous bulk materials when wide areas of material must be uniformly thin. A C-V system measures capacitance versus voltage (C-V) and capacitance versus time (C-t) characteristics of semiconductor devices. An interferometer is used to measure distances in terms of wavelength, and to determine wavelengths of particular light sources. There are two major types of SMU semiconductor metrology instruments: capacitance measurement units (CMU) and picoammeter units (PAU).
Reflectometers, resistance probes, resistance high-energy electron diffraction (RHEED) system, and X-ray diffractometers are types of semiconductor metrology instruments. Reflectometers or radiometers measure the reflectivity and radiance from a surface. Resistance probes are used to measure the resistivity of thin-films. RHEED systems are used to measure or monitor crystal structure or crystal orientation of epitaxial thin-films of silicon or other materials. X-ray diffractometers are semiconductor metrology instruments that are employed to unambiguously determine crystal structure, crystal orientation, film thickness and residual stress in silicon wafers, epitaxial films or other substrates.
Suppliers of semiconductor metrology instruments are located across the United States and around the world. They conform to a variety of quality standards and regulatory requirements. In Europe, semiconductor metrology instruments bear the CE Mark to indicate that products conform to appropriate European Union (EU) directives. Groups such as the International Standards Organizations (ISO) also provide guidelines to which suppliers adhere.