Nitrogen-Containing Etching Gas Minimizes Sidewall Damage in Low-k Films
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Solution Overview
Problem
Current low k plasma etching processes cause significant sidewall damage and carbon loss in low k films, leading to increased dielectric constant and critical dimension issues, particularly during the etching of complex circuitry in microprocessors.
Innovation Solution
The use of a nitrogen-containing etching composition, specifically an organofluorine compound with C≡N, C═N, or C—N functional groups, is introduced to minimize sidewall damage by selectively etching the low k layer while maintaining profile control and selectivity to mask and etch stop layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching processes are used on low k layers, then etching can be performed, but significant sidewall damage and carbon loss occur leading to increased dielectric constant
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from conventional fluorocarbon-based gases to nitrogen-containing etching gases. This parameter change fundamentally alters the etching chemistry to reduce sidewall damage and carbon loss while maintaining etching capability. The nitrogen-containing gas provides different reaction pathways that preserve the low k film's carbon content and methyl group terminations.
Solution Approach 2:
The patent employs a simple gas phase etching process without requiring complex polymer deposition or additional protective layers. The nitrogen-containing etching gas acts as a self-limiting, disposable etchant that removes material through direct chemical reaction rather than requiring sustained polymer protection, thereby reducing complexity while maintaining sidewall integrity.
2Productivity
If conventional etching processes are used, then low k layers can be etched, but carbon depletion occurs leading to trench broadening in subsequent wet stripping processes
Solution Approach 1:
The patent changes the etching chemistry from fluorocarbon-based to nitrogen-containing gases, which fundamentally alters how carbon is handled during etching. The nitrogen-containing etching gas maintains carbon content in the low k film through different reaction mechanisms, preventing the carbon depletion that leads to trench broadening in subsequent processing steps.
3Productivity
If plasma etching is performed on low k layers, then material removal is achieved, but plasma-induced damage increases the dielectric constant
Solution Approach 1:
The patent uses a simple nitrogen-containing gas as the etchant that provides self-limited chemical etching without requiring sustained plasma polymer deposition. This disposable etching approach removes material through direct chemical reaction while minimizing plasma-induced damage that would otherwise increase the dielectric constant through prolonged exposure and repeated processing steps.
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 reduces sidewall damage and carbon loss, maintaining the integrity of the low k film's properties and ensuring precise etching with minimal impact on the dielectric constant and critical dimensions, even in high aspect ratio structures.
Implementation Method 1
The low k layer is etched with a plasma activated vapor of an organofluorine compound
Implementation Method 2
The low k layer is etched with a plasma activated vapor of an organofluorine compound having a formula selected from the group consisting of N≡C—R; (N≡C—)—(R)—(—C≡N); Rx[—C═N(Rz)]y; and R(3-a)—N—Ha
Data Source
AI summary
Methods for minimizing sidewall damage during low k etch processes are disclosed. The methods etch the low k layers f using the plasma activated vapor of an organofluorine compound having a formula selected from the group consisting of N≡C—R; (N@C—)—(R)—(—C≡N); Rx[-C═N(Rz)]y; and R(3-a)-N—Ha, wherein a=1-2, x=1-2, y=1-2, z=0-1, x+z=1-3, and each R independently has the formula HaFbCc with a=0-11, b=0-11, and c=0-5.