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Method of Cost-Effective SGOI Substrate Manufacturing

IP.com Disclosure Number: IPCOM000245404D
Publication Date: 2016-Mar-07
Document File: 2 page(s) / 24K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for cost-effective Silicon Germanium on Insulator (SGOI) substrate manufacturing. The method decreases defects in the initial top layer on the 85% Silicon Germanium (SiGe) wafer and then enables multiple bonding processes and layer transfers before the discarding or recycling of the donor wafer by Chemical Mechanical Planarization (CMP) and the epitaxial re-growth of the i.e. 85% SiGe layer.

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Method of Cost-Effective SGOI Substrate Manufacturing

Future technology nodes look toward high percentage Silicon Germanium (SiGe) or pure Ge fins as enabling elements for performance improvements. The band structure of SiGe becomes more Ge-like for Ge contents at and above 85%. That makes 85% SiGe to pure Ge potential candidates for channel materials for 7nm and later nodes. Those high percentage SiGe or pure Ge fins need to be on silicon or Silicon on Insulator (SOI), to work with current Complementary Metal-Oxide Semiconductor (CMOS) technology. Fins or nanowires can be formed out of these materials.

Fabricating the 85% SiGe on Insulator (SGOI) wafer is challenging. The process first requires the formation of 85%-99% SiGe or pure Ge on silicon, which is a challenge due to the high lattice mismatch of 3.7% or more. Growing such material leads to high defect densities due to dislocations and stacking faults formed to compensate the mismatch between the lattices. Typically, those layers grow to a high thickness (e.g., 10-20 micron or more), trapping most of the defects at the interface, and relaxing the material as the growth progresses. Another option is graded layers (i.e. graded Ge concentration) leading to even thicker stacks of layers. The long epitaxial process makes this process expensive. Those structures are bonded to an oxidized silicon wafer and the top layer is transferred. The donor wafer is discarded or recycled by Chemical Mechanical Planarization (CMP) and epitaxial re-growth of the i.e. 85%SiGe layer.

The novel method grows the initial top layer on the 85% SiGe wafer to a thickness that is greater than needed for one transfer (prior art), making the layer less defective. At the same time, it enables multiple bonding processes and layer transfers before the discarding or recycling of the donor wafer by CMP and the epitaxial re-growth of the i.e. 85% SiGe layer. This solution makes this process more cost effective.

Those high percentage 85% donor wafers...