Epitaxial growth of SiGe films by annealing Al–Ge alloyed pastes on Si substrate

Abstract

A simple, low-cost, and non-vacuum epitaxial growth method to realize large-area semiconductors on crystalline silicon will become the game-changer for various applications. For example, we can expect the disruptive effect on the cost of large-scale III–V multi-junction solar cells if we could replace the high-cost germanium substrate with silicon–germanium (SiGe) on Si. For SiGe epitaxial growth, we attempted to develop a process using original Al–Ge pastes for screen printing and subsequent annealing. We compare two pastes including Al–Ge alloyed pastes with compositional uniformity in each particle and Al–Ge mixed pastes. We revealed that Al–Ge alloyed paste could form flatter SiGe film with much less residual pastes, supported by in-situ observations. The uniform and sufficient dissolution of the alloyed paste is responsible for these and led to higher average Ge-composition by annealing at 500 °C. The composition in SiGe was vertically graded up to ~ 90% at the topmost surface. These results show that printing and firing of Al–Ge alloyed paste on Si is the desirable, simple, and high-speed process for epitaxial growth of SiGe, which could be potentially used as the lattice-matched virtual substrate with III–V semiconductors.

Comprehensive Review of RF MEMS Switches in Satellite Communications

“…Based on the microwave characterization results, a packaging structure for the shunt capacitive contact of RF MEMS switches was designed, achieving a fault-free lifespan of up to 10.2 billion cycles. Al-Ge eutectic bonding is a widely used bonding technique in microelectronics [132,133], offering significant advantages over other eutectic wafer bonding processes, like Au−Ge and Au−Si, in terms of compatibility with standard CMOS wafer manufacturing processes [134]. Al-Ge eutectic bonding provides not only a conductive path between two substrates but also allows for patterning.…”

Effect of annealing ambient on SiGe layer formation using Al–Ge paste for III–V solar cell application

“…This method is a simple process using a conventional screen-printer and a furnace, and it has been confirmed that uniform SiGe layers with a thickness of more than 20 μm can be formed in a short processing time. [24][25][26][27][28] In this method, a liquid phase of Al-Ge-Si can be formed at a temperature below the mp of Si by screen-printing Al-Ge paste on a Si substrate. After the liquid phase is formed at high temperatures, cooling leads to the epitaxial growth of a SiGe layer at the interface of the Si substrate.…”