Multistate HF RF Pulsing for HAR Etch Profile Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RF plasma etching technologies face a trade-off between bow critical dimension (CD) control and capping margin in high aspect ratio (HAR) feature processing, where reducing bow CD leads to increased capping due to uneven deposition.
Innovation Solution
Implementing a multistate pulsing regime with a high-HF RF power intermediate state to increase deposition conformality, reducing deposition in the neck region while enhancing deposition in the bow region, thereby improving bow protection and reducing capping risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polymerizing chemistry is used to decrease bow critical dimension, then bow CD control is improved, but deposition occurs more in the neck region than in the bow region, leading to capping before desired passivation is achieved
Solution Approach 1:
The patent applies periodic action by implementing a multistate RF pulsing regime that cycles through different power states (high power, intermediate power, low power) during the etch process. This periodic modulation of RF power enables dynamic control of deposition patterns, allowing passivation in the bow region while preventing excessive deposition in the neck region, thereby resolving the contradiction between bow CD control and capping margin
Solution Approach 2:
The patent applies dynamics by transitioning from a static RF power mode to a dynamic multistate pulsing mode. The system dynamically adjusts RF power levels across three distinct states with varying durations, enabling real-time optimization of deposition conformality throughout the etch process. This dynamic control allows the process to adapt deposition patterns spatially and temporally, achieving both bow control and capping prevention
2Shape
If polymerizing chemistry is used for sidewall passivation, then lateral etch is prevented, but deposition on top of the mask worsens mask morphology and leads to early onset of capping
Solution Approach 1:
The patent applies local quality by creating spatially differentiated deposition patterns through multistate RF pulsing. The intermediate power state specifically targets the mask region to reduce polymer deposition on the mask surface, while other states maintain sidewall passivation. This localized control of deposition quality prevents mask morphology degradation while preserving sidewall profile control
Solution Approach 2:
The patent introduces an intermediate power state as a mediator between the high power state (which provides strong sidewall passivation) and the low power state (which reduces deposition). This intermediate state acts as a transition that specifically addresses mask deposition without compromising sidewall protection, thereby resolving the contradiction between shape control and mask morphology
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 multistate pulsing regime effectively breaks the trade-off between bow CD reduction and capping margin, achieving better bow protection and reduced capping risk by optimizing deposition patterns in HAR features.
Implementation Method 1
The RF generator generates an RF signal, which is supplied to the match network
Implementation Method 2
The output RF signal is used to etch the wafer
Implementation Method 3
RF plasma etching of features on semiconductor wafers
Implementation Method 4
This not only reduces the deposition in the neck region but also increases the deposition in the bottom region
Implementation Method 5
the use of a more polymerizing chemistry. However, the deposition from this polymerizing chemistry happens more in the top region
Data Source
AI summary
A method for performing a plasma etch process is provided. The method initiates with receiving a substrate into a chamber. A high frequency (HF) RF signal is generated, said HF RF signal being pulsed in at least a three-state cycle including a first state, a second state, and a third state. The first state is configured at a first power level; the second state is configured at a second power level less than the first power level; and, the third state is configured at a third power level less than the second power level. The second power level of the HF RF signal being in the range of about 0 W to 3500 W. The HF RF signal is applied to an electrode of the chamber for performing the plasma etch process.