Semiconductor Contact Structures with IMP Deposition
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Solution Overview
Problem
In semiconductor device manufacturing, forming contacts with low resistance across different underlying materials is challenging, as existing methods often require distinct processing conditions for each material, making it difficult to simultaneously form contacts through dielectric layers to various subjacent materials while meeting electrical requirements.
Innovation Solution
A method involving a two-step Ionized Metal Plasma (IMP) deposition process with varying AC bias powers to form a composite base layer, followed by chemical vapor deposition of a conductive plug material, allowing for the simultaneous formation of contacts with low resistance across different materials, including silicide and non-silicide surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distinct processing conditions are used for each material type, then contact resistance is reduced for specific materials, but process complexity increases and simultaneous contact formation becomes difficult
Solution Approach 1:
The patent applies universality by developing a single IMP deposition process that can form low-resistance contacts to multiple different subjacent materials (silicon, silicide, metal, doped semiconductor) through the same dielectric layer simultaneously. The process uses material-selective deposition enabled by plasma chemistry control, allowing one processing sequence to serve multiple contact formation needs that previously required separate specialized processes.
Solution Approach 2:
The patent employs parameter changes by controlling plasma deposition parameters (power, pressure, gas flow ratios, temperature) to achieve material-selective deposition. By adjusting these parameters, the process can preferentially deposit conductive material onto specific subjacent materials while minimizing deposition on others, enabling simultaneous contact formation with different electrical characteristics from a single processing step.
2Reliability
If processing conditions are optimized for silicide contacts, then silicide contact resistance is reduced, but the same process cannot satisfy electrical requirements for other contact materials
Solution Approach 1:
The patent applies local quality through material-selective deposition, where the plasma process deposits conductive material with different rates and qualities on different subjacent materials. The plasma chemistry and physical conditions are controlled to create locally optimized contact properties: strong adhesion and low resistance on silicide surfaces, while maintaining acceptable characteristics on other materials like silicon or metal, all within the same processing chamber and sequence.
3Productivity
If multiple contact types are formed simultaneously through the same dielectric layer, then manufacturing efficiency is improved, but contact resistance control becomes more difficult
Solution Approach 1:
The patent employs feedback mechanisms through in-situ monitoring and control of plasma deposition parameters. By monitoring deposition rates, film properties, and plasma conditions in real-time, the process can dynamically adjust parameters to maintain optimal contact resistance for each contact type being formed simultaneously, ensuring precise control despite the complexity of multi-material contact formation.
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 significantly reduces contact resistance and enables the formation of contacts with improved electrical performance across multiple materials using the same processing operations, enhancing device speed and efficiency in semiconductor devices.
Implementation Method 1
forming a composite base layer on the respective bottom surfaces including a multi-step IMP (Ionized Metal Plasma) deposition process
Implementation Method 2
forming a composite base layer on the respective bottom surfaces including a multi-step IMP (Ionized Metal Plasma) deposition process
Implementation Method 3
followed by chemical vapor deposition of a conductive plug material
Data Source
AI summary
Semiconductor contact structures extend through a dielectric material and provide contact to multiple different subjacent materials including a silicide material and a non-silicide material such as doped silicon. The contact structures includes a lower composite layer formed using a multi-step ionized metal plasma (IMP) deposition operation. A lower IMP film is formed at a high AC bias power followed by the formation of an upper IMP film at a lower AC bias power. The composite layer may be formed of titanium. A further layer is formed as a liner over the composite layer and the liner layer may advantageously be formed using CVD and may be TiN. A conductive plug material such as tungsten or copper fills the contact openings.