Patent DE-102007057241-A1 (DE)
Title: Method for producing a stack of layers on a crystalline substrate, which is free from nitride compound semiconductor by using metal organic gas-phase deposition, comprises forming a nitride-containing buffer layer on the substrate
Inventor: PETER MATTHIAS
IPC: H01L21/205
Filed: 2007-11-28
Abstract: The method for producing a stack of layers (2, 3, 4, 5, 6) on a crystalline substrate (1), which is free from nitride compound semiconductor by using metal organic gas-phase deposition, comprises forming a nitride-containing buffer layer on the substrate and then forming a crystalline layer made of group-III nitride compound semiconductor material, so that upper main surfaces (7, 8) of the buffer layer and crystalline layer are formed from nitrogen atoms. A contiguous region of upper main surface of the crystalline layer is smoothed. The crystalline layer has a diameter of more than 100 mu m. The method for producing a stack of layers (2, 3, 4, 5, 6) on a crystalline substrate (1), which is free from nitride compound semiconductor by using metal organic gas-phase deposition, comprises forming a nitride-containing buffer layer on the substrate and then forming a crystalline layer made of group-III nitride compound semiconductor material, so that upper main surfaces (7, 8) of the buffer layer and the crystalline layer are formed from nitrogen atoms. A contiguous region of the upper main surface of the crystalline layer is smoothed. The crystalline layer has a diameter of more than 100 mu m. The contiguous region has levels along the upper main surface of the crystalline layer, where the levels have a level height of less than 20 nm. The formation of the buffer layer comprises a supply of nitrogen-containing process gases at a determined substrate temperature of more than 1000[deg] C. A partial pressure of the process gases and the determined substrate temperature are selected, so that the upper main surface of the buffer layer is formed from the nitrogen atoms. The formation of the buffer layer comprises the formation of a crystalline buffer layer containing aluminum nitride. A c-axis of the crystalline buffer layer is parallel to a growth direction of the nitride-containing buffer layer. A c-axis of the crystalline layer is parallel to a growth direction of the crystalline layer. The formation of the crystalline layer comprises a formation of a gallium nitride layer, which has a layer thickness of more than 90 nm, and a formation of an aluminum gallium nitride layer. A ratio of the aluminum atoms and the gallium atoms in the aluminum gallium nitride layer is greater than 0.07. Before the formation of the crystalline layer, a first intermediate layer made of the group-III nitride compound semiconductor material is formed, which contains atoms of first and second group-III elements. A ratio of the atoms of the first group-III elements increases with increasing layer thickness of the first intermediate layer opposite to the atoms of the second group-III elements. After the formation of the first intermediate layer and before the formation of the crystalline layer, a further crystalline layer made of the group-III nitride compound semiconductor material is formed, which contains atoms of the first and second group-III elements, and a second intermediate layer made of the group-III nitride compound semiconductor material is formed. A ratio of the atoms of the first group-III elements increases with increasing layer thickness of the second intermediate layer opposite to the atoms of the second group-III elements. The crystalline substrate is made of sapphire. A c-axis of the crystalline substrate has an error orientation of 0.1-1.0[deg] opposite to a normal of a main surface of the substrate. An independent claim is included for an arrangement having a crystalline substrate.