Inductors are challenging to fabricate directly on integrated circuits (ICs) primarily due to their physical size and complexity. Unlike resistors and capacitors, which can be miniaturized using semiconductor processes, inductors require a substantial amount of space and typically involve wire windings around a core. This makes it impractical to integrate them into the compact and densely packed structure of ICs without significantly increasing the IC’s size and cost.
In integrated circuit components, inductors are often avoided due to several factors. Firstly, their size and the need for magnetic cores make them incompatible with the planar fabrication processes used for ICs. Secondly, inductors can introduce unwanted noise and interference in high-frequency circuits, impacting the overall performance and reliability of the IC. As a result, designers prefer to use alternative methods such as active circuits or external discrete components to achieve similar functionality without compromising the IC’s compactness and performance.
In IC and RC (resistor-capacitor) circuits, inductors are typically not used due to the difficulty in integrating them directly onto the semiconductor substrate. IC fabrication processes are optimized for creating layers of conductive and insulating materials, which are well-suited for creating resistors and capacitors but not inductors. Inductors also tend to be more susceptible to variations in manufacturing processes, which can affect their performance consistency compared to resistors and capacitors fabricated on ICs.
Certain components such as mechanical switches or large passive components like transformers cannot be fabricated directly on an IC due to the nature of semiconductor manufacturing processes. Mechanical switches involve moving parts that cannot be integrated into the solid-state structure of ICs, while transformers require intricate winding of coils and magnetic cores that are not compatible with the planar layers used in IC fabrication. These components are typically used externally in conjunction with ICs to achieve specific functions in electronic circuits.
One thing that is not possible to fabricate on an IC is a three-dimensional structure such as a mechanical switch or a complex electromagnetic device like a transformer. IC fabrication processes are fundamentally planar, meaning they involve layers of materials deposited and patterned on a flat substrate. Creating three-dimensional structures or devices with moving parts exceeds the capabilities of standard semiconductor manufacturing techniques used for ICs. Therefore, components requiring such configurations must be implemented separately from the IC itself.