Contact Plug Oxide Removal for Low-Resistance Interconnects
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Solution Overview
Problem
The scaling down of semiconductor devices poses challenges due to the formation of oxidized and nitrided portions in contact plugs, which increase contact resistance and hinder the formation of low-resistance conducting routes between contact plugs and upper-level interconnects.
Innovation Solution
A pre-deposition treatment involving a gas mixture of NH3 and N2 is used to reduce oxidized portions of contact plugs to metal, preventing the formation of nitride and ensuring that upper-level interconnects are in contact with metal portions, thereby reducing oxide or nitride formation between them, facilitating low-resistance conducting routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact plugs are formed using conventional materials and processes, then the fabrication process is simple, but oxidized and nitrided portions form in contact plugs increasing contact resistance
Solution Approach 1:
The patent applies preliminary action by performing a pre-deposition treatment on contact plugs before forming upper-level interconnects. This treatment reduces oxidized portions to metal and prevents nitride formation in advance, ensuring low-resistance conducting routes are established before subsequent fabrication steps. The pre-treatment addresses oxidation and nitridation issues proactively rather than reactively.
Solution Approach 2:
The patent changes the chemical state parameters of contact plug materials through controlled exposure to gas mixtures (NH3 and N2). By adjusting gas composition, temperature, and exposure time, the patent transforms oxidized portions back to metallic state and prevents unwanted nitride formation, thereby controlling the electrical properties of contact plugs to achieve low contact resistance.
2Productivity
If upper-level interconnects are formed directly on contact plugs, then the fabrication process is short, but oxide or nitride formation increases contact resistance
Solution Approach 1:
The patent inserts a pre-deposition treatment step between contact plug formation and upper-level interconnect formation. This preliminary action modifies the contact plug surface chemistry to prevent oxide and nitride formation during subsequent interconnect fabrication, ensuring low-resistance conducting routes are maintained throughout the manufacturing process.
Solution Approach 2:
The patent applies preliminary anti-action by using a pre-deposition treatment that counteracts the tendency of contact plugs to form oxides and nitrides during subsequent fabrication steps. The treatment creates a protective metallic surface state that resists oxidation and nitridation when upper-level interconnects are formed, thereby preventing contact resistance increase.
3Reliability
If pre-deposition treatment with NH3 and N2 gas mixture is applied, then oxide and nitride formation is reduced, but additional process steps are required
Solution Approach 1:
The patent merges multiple functions into a single pre-deposition treatment step: reducing existing oxides to metal, preventing nitride formation, and preparing the surface for subsequent interconnect deposition. This consolidation achieves multiple objectives (oxide removal, nitride prevention, surface preparation) in one integrated process rather than separate sequential steps.
Solution Approach 2:
The pre-deposition treatment with NH3 and N2 gas mixture serves multiple functions simultaneously: it acts as a reducing agent for oxides, a protective atmosphere against nitridation, and a surface preparation step for subsequent deposition. This multi-functional approach reduces the need for separate process steps while achieving comprehensive contact plug protection.
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 results in low-resistance conducting routes between contact plugs and upper-level interconnects, while also forming an insulating layer to protect the surrounding dielectric layers from over-etching during interconnect formation, enhancing the overall efficiency of semiconductor device fabrication.
Implementation Method 1
A pre-deposition treatment is performed that includes exposing contact plugs to a gas mixture of NH3 and N2. The pre-deposition treatment may reduce oxidized portions of the contact plugs to a metal element
Implementation Method 2
The pre-deposition treatment may reduce oxidized portions of the contact plugs to a metal element while preventing/reducing the formation of a nitride in or over the contact plugs
Data Source
AI summary
A method of forming a semiconductor device includes forming an electronic component over a substrate; forming a first insulating layer over the electronic component; forming a contact plug extending through the first insulating layer to the electronic component, wherein the contact plug includes a first portion formed of a conductive material and a second portion formed of an oxide of the conductive material disposed over the first portion; performing a treatment to expose the contact plug and the first insulating layer to a gas mixture of N2 and NH3; after performing the treatment, forming a second insulating layer over the contact plug and the first insulating layer; and forming an interconnect in the second insulating layer and in contact with the contact plug.