Semiconductor Contact Layer Segmentation for Ni Diffusion Control
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Solution Overview
Problem
In semiconductor manufacturing, particularly for MOSFET devices at technology nodes below 65 nm, NiSi contact layers face challenges with high Ni diffusion leading to shorts and inadequate contact resistance, which existing materials like TiSi2 and CoSi2 cannot effectively address.
Innovation Solution
A method involving the formation of a semiconductor structure with a first contact layer having a smaller diffusion coefficient than a second contact layer, where the first layer is closer to the gate stack and the second layer is farther away, limiting diffusion into the channel region and improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NiSi contact layer is used to reduce contact resistance, then contact resistance is reduced, but Ni diffusion increases causing shorts in the channel
Solution Approach 1:
The contact layer is divided into multiple segments: a first contact layer (NiSi with low diffusion coefficient) positioned closer to the gate stack, and a second contact layer (NiSi with higher diffusion coefficient) positioned farther away. This segmentation allows each layer to perform its specific function - the first layer suppresses diffusion while the second layer provides low contact resistance
Solution Approach 2:
Different regions of the contact structure are assigned different material properties. The first contact layer uses material with lower diffusion coefficient suited for the region near the gate stack where diffusion control is critical, while the second contact layer uses material with higher diffusion coefficient suited for the region farther from the gate where contact resistance is the primary concern
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 suppresses Ni diffusion and reduces contact resistance, enhancing the reliability and performance of semiconductor devices by strategically positioning and forming contact layers with varying diffusion coefficients.
Implementation Method 1
Ni has a higher diffusion coefficient than Ti, Co or Pt, etc. When Ni laterally diffuses into the channel region, a silicide layer is formed in the channel accordingly.
Implementation Method 2
The contact layer is beneficial to the reduction of the contact resistance of the source/drain region.
Data Source
AI summary
The present invention provides a method for manufacturing a semiconductor structure, comprising: forming a first contact layer on an exposed active region of a first spacer; forming a second spacer at a region of the first contact layer close to a gate stack to partially cover the exposed active region; forming a second contact layer in the uncovered exposed active region, wherein when a diffusion coefficient of the first contact layer is the same as that of the second contact layer, the first contact layer has a thickness less than that of the second contact layer; and when the diffusion coefficient of the first contact layer is different from that of the second contact layer, the diffusion coefficient of the first contact layer is smaller than that of the second contact layer. Correspondingly, the present invention also provides a semiconductor structure. The present invention is beneficial to the suppression of the diffusion of corresponding compositions from the contact layers into the channel region, reduction of the short channel effects, and improvement of the reliability of the semiconductor structure.