ALD Precursors and Microelectronics

One of the largest markets for ALD precursors is the microelectronics sector. Samsung was working with ALD to enhance the storage capacitor in DRAM memories already in the late 1990s. Research and development in transistor manufacture now rely on the use of ALD to create conformal, pinhole-free films with precisely regulated thickness and a high dielectric constant.

ALD has grown significantly since the industry switched to high-k dielectrics and at Optima chem, we use cutting-edge technology such as high-k for the transistor gate stack in microelectronic devices. The high-k gate oxides on Si must be extremely homogeneous and pinhole-free to stop current leakage via the gate oxide. To overcome the difficulties associated with reducing oxide thickness, Intel used ALD in their mass manufacturing line in 2007.

ALD in microelectronics: high-k gate dielectrics

This is a major factor in their ability to go from the 65 nm to the 45 nm node technology without producing transistors that used noticeably more power. They used a high-k HfO2-based oxide with a k-value of around 20, a capping layer that matches the gate metal’s work function, and an interfacial layer of SiON to electrically passivate the surface of silicon. Subsequently, other significant players in the semiconductor industry followed suit and began their production using ALD to deposit high-k dielectrics.

New restrictions on the bulk Si crystal have driven the industry to explore other, more radical alternatives to the conventional transistor idea as the devices have continued to shrink, partly made possible by the ALD gate oxides, which lowered the equivalent gate oxide thickness. The tri-gate structure, a variation on the Fin field-effect transistor (FinFET) structure, was first produced by Intel with their newest technology, the 22 nm node.

This tri-gate design requires that the high aspect ratio fins projecting from the surface be covered with a gate oxide consistent in composition, thickness, and pinhole-free — a task ideal for ALD. Suppose conformal ALD gate oxides had not previously been a part of the production process. In that case, it is possible to wonder if such a non-planar structure would have been so easily fabricated.

Consider some of the topics that colleges or other organizations are currently researching, even if it is not known what will be applied by the chipmakers in the next-generation technology. Utilizing the conformal ALD gate oxides and carrying on with the FinFET track while making a little undercut on the fourth side to generate an omega gate is one option. The ideal design would enclose a semiconducting wire or tube, such as a nanotube, with a gate. The conformality of a technique like ALD facilitates these device architectures.

Another approach under investigation is to find a gate oxide for Si that can be produced by ALD and has a higher dielectric constant. SrTiO3, Al-doped TiO2, LaLuO3, Hf1xZrxO2, SrRuO3, and HfTiOx are examples of potential possibilities.

Once more, ALD’s capability to produce compositionally homogeneous films and its generally straightforward method of regulating useful methods for researching new high-k compounds because of the material composition created by switching between binary material cycles throughout growth.

Contact us for all your ALD precursor manufacturing and supply needs.