Papers by Author: Evi Vrancken

Abstract: The last decennia, a lot of effort has been made to introduce new channel materials in a Si process flow. High mobility materials such as Ge need a good gate stack passivation in order to ensure optimal MOSFET operation. Several routes for passivating the Ge gate stack have been explored in the last years. We present here the S-passivation of the Ge gate stack: (NH₄)₂S is used to create a S-terminated Ge surface. In this paper the S-treatment is discussed. The S-terminated Ge surface is not chemically passive but can still react with air. After gate oxide deposition, the Ge-S bonds are preserved and an adequate passivation is found for pMOS operation.

Abstract: The Si transistor has dominated the semiconductor industry for decades. However, to fulfill the demands of Moore’s law, the Si transistor has been pushed to its physical limits. Introducing new materials with higher intrinsic carrier mobility is one way to solve this problem. Ge, GaAs and InGaAs are known for their high mobilities and are therefore suitable candidates for replacing Si as a channel material. However, introduction of new materials raises new issues. For Si processing, several steps such as cleaning, etching and stripping are based on wet treatments. The knowledge of etch rates of the semiconductor material is of great importance. In this paper, etch rates of Ge, GaAs and InGaAs in several chemical solutions are studied. A comparison of the etch rates is made between the materials.