Selective Etch of High-k Dielectric Layer via Ar Sputtering and BCl3
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Solution Overview
Problem
The etching of high-k dielectric materials is challenging due to lower volatility of etch byproducts, resulting in lower etch rates and selectivity compared to ONO films, and conventional BCl3-based etch processes suffer from microloading issues at low bias voltages.
Innovation Solution
A method involving partial removal of the high-k dielectric layer by Ar sputtering followed by etching with a BCl3-based gas is used, which improves selectivity and reduces microloading by generating a plasma from Ar sputtering gas and then BCl3 etching gas, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional BCl3-based etch chemistry is used with low bias voltage to achieve good etch selectivity to polysilicon, then etch selectivity is improved, but micro loading problems occur
Solution Approach 1:
The etching process is divided into two distinct segments: a first etching process using BCl3-based chemistry at low bias voltage to achieve selective removal of high-k dielectric material from polysilicon, and a second etching process using different chemistry or parameters to address micro loading. This segmentation allows each process to optimize for its specific function, resolving the contradiction between selectivity and micro loading control.
2Reliability
If high-k dielectric material is used to replace ONO to increase dielectric constant, then dielectric constant is improved, but etch rate and selectivity decrease
Solution Approach 1:
The patent applies parameter changes by adjusting etch chemistry composition, bias voltage, and process temperature to optimize the etching of high-k dielectric materials. By modifying these parameters, the process achieves adequate etch rates while maintaining the high dielectric constant property of the material, thus resolving the contradiction between material performance and processability.
3Reliability
If high-k dielectric material is used to replace ONO to increase dielectric constant, then dielectric constant is improved, but etch selectivity to polysilicon decreases
Solution Approach 1:
The patent introduces intermediary substances or process conditions that facilitate selective etching of high-k dielectric material while protecting polysilicon. This intermediary approach enables the etch process to distinguish between the dielectric material and polysilicon, achieving both high dielectric constant and adequate etch selectivity.
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 enhances the etch selectivity of high-k dielectric layers with respect to polysilicon materials, reducing microloading and achieving higher etch rates, thereby addressing the limitations of conventional etching processes.
Implementation Method 1
The high-k dielectric layer is partially removed by Ar sputtering... a sputtering gas containing Ar is provided into an etch chamber in which the substrate is placed, a plasma is generated from the sputtering gas
Implementation Method 2
the etching gas is provided into the etch chamber, a plasma is generated from the etching gas... an etching gas comprising BCl3
Implementation Method 3
the high-k dielectric layer is etched using an etching gas comprising BCl3
Data Source
AI summary
A method for selectively etching a high-k dielectric layer with respect to a polysilicon material is provided. The high-k dielectric layer is partially removed by Ar sputtering, and then the high-k dielectric layer is etched using an etching gas comprising BCl3. The high-k dielectric layer and the polysilicon material may be formed on a substrate. In order to partially remove the high-k dielectric layer, a sputtering gas containing Ar is provided into an etch chamber in which the substrate is placed, a plasma is generated from the sputtering gas, and then the sputtering gas is stopped. In order to etch the high-k dielectric layer, the etching gas is provided into the etch chamber, a plasma is generated from the etching gas, and then the etching gas is stopped.