Gettering Metal Stack for Oxygen Depletion in Semiconductor Contacts
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Solution Overview
Problem
As semiconductor circuits become denser, controlling parasitic resistance and capacitance becomes increasingly difficult due to the shrinking size of circuit elements, which affects their performance, and existing methods struggle to manage the electrical characteristics of contact interfaces effectively.
Innovation Solution
The method involves forming a metal stack on a silicon-containing semiconductor substrate with a gettering metal film to migrate oxygen away from the contact interface, forming a metal silicide layer, and using anneal processes like millisecond laser anneals to control the chemical composition and physical structure of the contact, thereby reducing parasitic resistance and capacitance and tailoring the workfunction of the contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit elements are shrunk to increase density, then productivity and circuit density are improved, but parasitic resistance and capacitance increase causing performance degradation
Solution Approach 1:
The patent extracts and removes oxygen from the contact interface region through a gettering mechanism. A metal stack containing gettering metals (such as titanium, tantalum, cobalt, or tungsten) is deposited and annealed to migrate and trap oxygen atoms away from the silicon-containing region, thereby eliminating the harmful oxide formation that causes parasitic resistance and capacitance.
Solution Approach 2:
The patent introduces a gettering metal layer as an intermediary substance between the silicon-containing region and the metal cap. This intermediary layer acts as a trap for oxygen atoms, preventing them from forming oxides at the critical contact interface while allowing the desired electrical contact to be formed.
2Ease of manufacture
If conventional contact formation methods are used, then manufacturing simplicity is maintained, but electrical characteristics of contact interfaces cannot be effectively controlled
Solution Approach 1:
The patent changes the chemical composition parameters of the contact structure by introducing specific gettering metals with known oxygen affinity. By controlling the type and amount of gettering metal in the metal stack, the patent precisely controls the oxygen depletion level at the contact interface, thereby controlling the electrical characteristics such as contact resistivity and workfunction.
Solution Approach 2:
The patent performs preliminary oxygen depletion through the gettering mechanism before final contact formation. The metal stack with gettering metals is deposited and annealed in advance to migrate and trap oxygen, creating an optimized contact interface environment before the actual electrical contact is established.
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 reduces parasitic resistance and capacitance, improves specific contact resistivity, and allows for similar workfunction values on both NFET and PFET structures, enhancing the overall performance of semiconductor circuits by controlling the diffusion of materials during anneal steps.
Implementation Method 1
annealing the metal stack to cause oxygen to migrate from the substrate to the gettering metal film
Implementation Method 2
annealing the metal stack to cause oxygen to migrate from the substrate to the gettering metal film
Implementation Method 3
using anneal processes like millisecond laser anneals to control the chemical composition and physical structure
Implementation Method 4
a gettering-metal oxide layer within an upper portion of the metal stack
Data Source
AI summary
A device is created by forming a layer of dielectric material on a silicon-containing region of a semiconductor substrate. An opening is created through the layer of dielectric material, the opening having a bottom and exposing the silicon-containing region. A metal stack is formed within the opening. The metal stack includes at least a first metal film on the silicon-containing region and a second gettering metal film on the first metal film. The metal stack is annealed to cause oxygen to migrate from the substrate to the gettering metal film. A first liner is formed within the opening. A fill metal is deposited in the opening.