Cryogenic Focused Ion Beam (Cryo-FIB) Microscopy

Introduction to Cryogenic Focused Ion Beam (Cryo-FIB) Microscopy

Cryogenic focused ion beam (Cryo-FIB) technology is a state-of-the-art semiconductor examination method that can finely mill frozen and hydrated samples from subsurface layers or thin lamellae from bulk materials. This method offers in-depth insights into the morphology and structure of samples by combining transmission electron microscopy (TEM) with scanning electron microscopy (SEM).

Principle and Methodology

Cryo-FIB is a technique that uses a dual-beam system consisting of a scanning electron microscope (SEM) and a focused ion beam (FIB) to analyze samples. The SEM allows surface imaging and characterization, while the FIB enables precision milling. Gallium ions are accelerated and focused onto the sample surface, creating cross-sections with sub-5 nm resolution. A typical instrument includes a gallium ion source for FIB milling and a high-resolution SEM with a field emission gun. This technique is beneficial for thin lamella processing in structural biology, allowing for accurate analysis of soft materials by cooling the sample to cryogenic temperatures during the thinning process.

Applications and Significance

Ion chromatography is a versatile tool for analyzing charged organic or inorganic components in the mobile phase. It uses anion exchange resins to separate common inorganic ions like sulfate, chloride, and nitrate and cation exchange resins to separate cations like potassium, sodium, and lithium. It can also separate proteins and amino acids based on their pH-dependent ionization behavior in water. Cryo-FIB technology is used in materials science, semiconductor analysis, and structural biology, providing unparalleled insights into sample structure and content. This method improves the characterization of various materials and biological specimens, a breakthrough in electron microscopy.
Common Uses of Cryogenic Focused Ion Beam (Cryo-FIB) Microscopy

• The determination of biomacromolecules’ three-dimensional structures.
• Analysis of biological organisms’ surface, porosity, and structure, soft matter materials, and nanoparticles.
• Solid-state physics and semiconductor failure analysis both make use of it.
• Preparing (s) tem specimens for susceptible crystalline materials is an effective tool.
• At an atomic resolution, reveal intricate, undiscovered local structures.

Industrial Applications of Cryo-FIB

• Used to process and characterize delicate battery materials, such as frozen liquid electrolytes in lithium dendrite characterization
• Perovskite solar cell preparation for atom probe tomography
• Used to fabricate, alter, and ablate chips and devices in the semiconductor industry.
• Prevents the creation of hydride and unwanted hydrogen pick-up during the preparation of Ti alloys

Advantages of Cryo-FIB

• Automation, Cryo-lift-out lamella process, increased run time, and 3D microscopic visualization.
• FIB milling and imaging at 30 KV with a 5 nm resolution.
• Reduces the amount of structural damage brought on by the ion beam milling procedure
• Minimizes sample contamination and prevents the movement of light elements
• A high-quality sample with the specified orientation can be created from a bulk crystal to a large area.
• Permit the analysis of wet samples and regulate radiation harm to frozen samples at room temperature.
• Able to identify between proteins, lipids, and nucleic acids by contrast.
• Biological structures within the vacuum chamber are well preserved.
  Limitations of Cryo-FIB
• The meager ratio of signal to noise.
• Measurement of pictures from skewed samples is challenging.
• In a cryo-EM, the sample temperature should be less than 135 ^oC.
• Producing samples without an effective technique and high-quality samples is more time-consuming.