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New Gate Stack Scheme (Gate Stack in Reverse Order)

IP.com Disclosure Number: IPCOM000233535D
Publication Date: 2013-Dec-11
Document File: 4 page(s) / 340K

Publishing Venue

The IP.com Prior Art Database

Abstract

We report here introducing gate stack in reverse order and forming on a donor silicon wafer. The polysilicon, metal gate and metal oxide depositions were done using non-conventional sequence on a donor Si wafer. Here, the gate stack is in reverse order and formed on a donor wafer. The final gate stack is constructed on a device Si wafer.

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New Gate Stack Scheme (Gate Stack in Reverse Order)

ABSTRACT

We report here introducing gate stack in reverse order and forming on a donor silicon wafer.  The polysilicon, metal gate and metal oxide depositions were done using non-conventional sequence on a donor Si wafer.  Here, the gate stack is in reverse order and formed on a donor wafer.  The final gate stack is constructed on a device Si wafer.

The “gate first” process approach consists of metal oxide dielectric (1) on silicon followed by metal gate (2), and then polysilicon (3) deposition.

The “gate last (replacement gate)” which is more complex than the gate first approach is an option.  Here, we are introducing “gate stack in reverse order and forming on a donor silicon wafer” as a new option.  

As shown below, first deposit poly-Si on the donor wafer, and implant hydrogen into the donor wafer.  Then form metal gate(s), and finally metal oxide dielectric on the donor wafer.  Prepare device Si wafer (with well implants and STI) in parallel.  Bond donor wafer, directly bonding metal oxide dielectric with device wafer as shown below.  Then separate gate stack from donor wafer at the hydrogen implanted layer (or, by CMP if H implant is not used in the step above).  Majority of donor wafer is removed and the poly-Si forms the top Si layer. 

 

Simple process to tune MeOx composition for higher permittivity (higher K) and to tune MG composition to module work function (lower Vt).  It lowers (~4X) t...