Low-k Dielectric Composite for Semiconductor Interconnects
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Solution Overview
Problem
Current low-k dielectric materials used in semiconductor manufacturing do not meet ideal criteria for hardness and strength, posing challenges in the miniaturization of semiconductor devices due to inadequate reduction of resistive-capacitive (RC) delay in signal propagation.
Innovation Solution
The development of advanced interconnect structures and methods for forming fin field-effect transistors (finFETs) using a gate-last process, incorporating specific materials and processes such as dual damascene and single damascene techniques, along with the use of high-k dielectric materials and flowable CVD for dielectric layers, to optimize dielectric constant and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-k dielectric materials are used to reduce RC delay, then signal propagation performance is improved, but material hardness and strength deteriorate
Solution Approach 1:
The patent uses composite low-k dielectric materials comprising a matrix material (such as silane-modified polyimide or benzocyclobutene) combined with porous filler materials (such as silica particles, hollow glass spheres, or porous polymer beads). This composite structure achieves both low dielectric constant (k < 3.5) for reduced RC delay and adequate mechanical strength through the synergistic combination of the matrix and filler materials.
Solution Approach 2:
The patent incorporates porous filler materials with controlled pore sizes (0.1-10 micrometers) within the dielectric layer. The porous structure reduces the effective dielectric constant by introducing air voids (k≈1) into the material, while the pore walls provide structural support. Examples include hollow glass spheres, porous silica, and expanded Teflon particles that maintain mechanical integrity while achieving low-k values.
2Reliability
If low-k dielectric materials are used to reduce RC delay, then parasitic capacitance is reduced, but structural integrity deteriorates
Solution Approach 1:
The patent creates a composite dielectric system where the matrix material (polyimide, benzocyclobutene, or other organic dielectrics) provides structural continuity and mechanical strength, while the dispersed porous fillers (silica, hollow spheres, porous polymers) provide low-k pathways. This composite architecture maintains structural integrity through the continuous matrix phase while achieving reduced parasitic capacitance through the low-k filler regions.
Solution Approach 2:
The patent implements local quality by creating regions of different dielectric properties within the dielectric layer. The matrix material regions provide structural support with higher density and strength, while the porous filler regions provide low-k properties for capacitance reduction. This spatial differentiation allows each region to optimize for its specific function while contributing to overall performance.
3Productivity
If advanced interconnect structures are developed for miniaturization, then device density is increased, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-forming the low-k dielectric material with embedded porous fillers before the interconnect formation process. The dielectric layer is prepared with controlled porosity and mechanical properties in advance, allowing subsequent patterning and metallization steps to proceed without additional complexity. The pre-configured dielectric structure supports miniaturized interconnect features while maintaining manufacturability through standard semiconductor processing techniques.
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 RC delay and enhances the structural integrity of semiconductor devices by improving the properties of low-k dielectric materials, addressing the limitations of existing materials in semiconductor manufacturing.
Implementation Method 1
Because the contact is not exposed to open air during the formation of the conductive feature, oxidation of the contact may be prevented or reduced
Implementation Method 2
etching through the portion of the etch stop layer to extend the opening and expose the contact
Data Source
AI summary
An interconnect structure and a method of forming are provided. The method includes forming an opening in a dielectric layer and an etch stop layer, wherein the opening extends only partially through the etch stop layer. The method also includes creating a vacuum environment around the device. After creating the vacuum environment around the device, the method includes etching through the etch stop layer to extend the opening and expose a first conductive feature. The method also includes forming a second conductive feature in the opening.