Filament-Assisted CVD for Low-k Dielectric Films
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Solution Overview
Problem
Conventional chemical vapor deposition (CVD) and plasma-enhanced CVD (PECVD) processes for depositing low-k dielectric films in semiconductor manufacturing face challenges such as high substrate temperatures, thermal and mechanical performance issues, copper migration, and plasma-induced damage, which hinder the reduction of interconnect delay in integrated circuits.
Innovation Solution
A filament-assisted CVD method that uses a non-ionizing heat source to decompose Si-containing and organic chemical precursors, allowing for the deposition of graded organosilicon-containing materials at lower substrate temperatures without plasma, thereby reducing plasma-induced damage and improving film morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional CVD or PECVD processes are used to deposit low-k dielectric films, then the films can be formed with appropriate dielectric properties, but the substrate temperature becomes very high (exceeding 400°C) which adds to the thermal budget and causes thermal stress
Solution Approach 1:
The patent introduces a filament as an intermediary heating element that directly heats the chemical precursors in the gas phase before they reach the substrate. This mediator approach allows the precursors to be activated at high temperature near the filament while the substrate itself remains at a lower temperature, thereby decoupling the heating requirement from the substrate thermal budget
Solution Approach 2:
The patent replaces the conventional thermal field (heating the substrate directly) with a localized thermal field generated by the filament. This substitution changes the heating mechanism from bulk substrate heating to localized gas-phase precursor heating, enabling film deposition at lower substrate temperatures
2Object-affected harmful factors
If PECVD process is used to deposit low-k dielectric films, then the deposition can occur at lower temperatures compared to conventional CVD, but plasma-induced damage occurs which degrades film quality and causes copper migration
Solution Approach 1:
The patent extracts and removes the plasma component from the deposition process entirely. By using only thermal field (filament heating) without plasma, the harmful plasma-induced damage is eliminated while still achieving effective chemical precursor decomposition and film deposition through thermal activation alone
Solution Approach 2:
The patent converts the potentially harmful high-energy plasma environment into a beneficial low-energy thermal field environment. The filament provides controlled thermal energy that activates the precursors without creating the damaging plasma conditions, effectively transforming a harmful process into a benign one
3Productivity
If porous low-k films are deposited to reduce dielectric constant, then the interconnect delay is reduced, but the films suffer from poor thermal and mechanical performance
Solution Approach 1:
The patent changes the deposition parameters by using filament-assisted thermal CVD with controlled precursor flow and temperature gradients. This enables the formation of films with optimized porosity and density characteristics that maintain mechanical integrity while achieving the desired low dielectric constant for reduced interconnect delay
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
The method achieves a lower dielectric constant, improved thermal budget, and enhanced mechanical properties of the deposited films, addressing the limitations of traditional CVD and PECVD processes by maintaining film quality while reducing thermal stress and plasma damage.
Implementation Method 1
exposing the process gas to a non-ionizing heat source separate from the substrate holder to cause decomposition of the one or more chemical precursors
Implementation Method 2
a chemical vapor deposition (CVD) method for depositing a thin film on a substrate
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E
AI summary
A chemical vapor deposition (CVD) method for depositing a thin film on a surface of a substrate is described. The CVD method comprises disposing a substrate on a substrate holder in a process chamber, and introducing a process gas to the process chamber, wherein the process gas comprises a chemical precursor. The process gas is exposed to a non-ionizing heat source separate from the substrate holder to cause decomposition of the chemical precursor. A thin film is deposited upon the substrate.