Metal Gate Surface Cleaning for Selective Oxide Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in fabricating semiconductor devices with metal gates due to issues such as high power dissipation and the need for improved device performance as feature sizes decrease, particularly in removing oxide layers without damaging the metal gate or causing trench widening during the IC fabrication process.
Innovation Solution
A method involving the use of a phosphoric acid solution to selectively remove aluminum oxide layers from metal gates, followed by nitrogen/hydrogen plasma reduction of native oxide layers, and subsequent Ar sputtering to expand trench widths, ensuring minimal damage and maintaining pattern integrity, combined with chemical mechanical polishing to form coplanar metal contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional oxide removal methods are used, then oxide layers can be removed, but the metal gate is damaged and trench widening occurs
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a phosphoric acid-based solution with specific composition ratios and controlling temperature and time parameters. This selective chemical etching approach removes oxide layers while preserving the metal gate structure, resolving the contradiction between oxide removal effectiveness and metal gate integrity.
Solution Approach 2:
The patent introduces a phosphoric acid-based cleaning solution as an intermediary substance that selectively reacts with oxide layers without attacking the metal gate. This intermediary chemical agent enables selective oxide removal while protecting the metal gate, thereby maintaining trench width control and preventing unwanted widening.
2Productivity
If feature size is decreased to increase functional density, then production efficiency improves, but power dissipation increases
Solution Approach 1:
The patent changes the material parameters by replacing traditional polysilicon gates with metal gates (such as tungsten, cobalt, or copper). This material substitution enables smaller feature sizes with lower resistance, thereby increasing functional density while reducing power dissipation through the gate structure.
3Reliability
If metal gate is used instead of polysilicon gate, then device performance improves, but oxide layer removal becomes more difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the etching solution to phosphoric acid-based formulations with specific concentrations and additive compositions. These parameter adjustments enable selective removal of aluminum oxide and other metal oxides from metal gate surfaces, making the manufacturing process easier while maintaining high device performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively removes oxide layers with high selectivity, prevents damage to the metal gate, minimizes trench widening, and enhances the process window, leading to improved reliability and performance of integrated circuit structures.
Implementation Method 1
A method involving the use of a phosphoric acid solution to selectively remove aluminum oxide layers from metal gates
Implementation Method 2
followed by nitrogen/hydrogen plasma reduction of native oxide layers
Implementation Method 3
nitrogen/hydrogen plasma reduction of native oxide layers
Implementation Method 4
subsequent Ar sputtering to expand trench widths
Implementation Method 5
combined with chemical mechanical polishing to form coplanar metal contacts
Data Source
AI summary
The present disclosure provides a method for forming an integrated circuit (IC) structure. The method includes providing a metal gate (MG), an etch stop layer (ESL) formed on the MG, and a dielectric layer formed on the ESL. The method further includes etching the ESL and the dielectric layer to form a trench. A surface of the MG exposed in the trench is oxidized to form a first oxide layer on the MG. The method further includes removing the first oxide layer using a H3PO4 solution.