Plasma Etching Film Stack for Gate Opening CD Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variations in dimensions during semiconductor microfabrication, particularly in the formation of gate electrodes, lead to performance issues due to uneven pattern dimensions and roughness, which existing techniques fail to adequately address.
Innovation Solution
A plasma processing method involving the formation of a first film and a second film with different etching rates and thicknesses on the side surfaces of openings, where the second film has a lower etching rate than the first film, allowing for controlled etching to equalize opening dimensions and improve local critical dimension uniformity (LCDU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single film is formed on the processing target, then the process is simple, but the dimensional uniformity and LCDU cannot be effectively controlled
Solution Approach 1:
The film formation process is segmented into two distinct steps: forming a first film with higher etching rate, then forming a second film with lower etching rate. This segmentation allows independent optimization of each film's properties to achieve both dimensional uniformity and controlled etching behavior that cannot be achieved with a single film.
Solution Approach 2:
The patent uses a composite structure of two different films with distinct etching rates. The first film (higher etching rate) and second film (lower etching rate) work together in a composite manner, where the first film provides material for etching to equalize dimensions while the second film maintains structural integrity and provides etching resistance.
2Productivity
If the etching rate is high, then the etching process is efficient, but the dimensional control and LCDU improvement are insufficient
Solution Approach 1:
The patent applies local quality by having different etching rates at different locations in the vertical structure. The first film has higher etching rate for efficient material removal, while the second film has lower etching rate for precise dimensional control. This spatial differentiation of etching rates allows simultaneous achievement of efficiency and precision.
Solution Approach 2:
The patent changes the etching rate parameter between the two films. The first film is formed with parameters that result in higher etching rate, while the second film is formed with parameters that result in lower etching rate. This parameter change enables the system to achieve both high productivity during etching of the first film and high precision during etching of the second film.
3Manufacturing precision
If the film thickness is uniform across all openings, then the deposition is simple, but the LCDU cannot be improved
Solution Approach 1:
The patent applies preliminary action by first forming the first film with uniform thickness, then forming the second film with thickness that varies according to opening size. This preliminary uniform deposition followed by selective thickness variation allows the system to start with a simple process while achieving the complex outcome of LCDU improvement through the etching step.
Solution Approach 2:
The patent introduces dimensional variation in the second film thickness based on opening size. Instead of uniform thickness in one dimension, the second film's thickness varies according to the opening dimensions, creating a relationship between film thickness and opening size that enables LCDU improvement during etching. This adds a new dimension of control to the deposition process.
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 effectively reduces dimensional differences between openings, enhancing LCDU and pattern roughness, thereby improving the uniformity and performance of semiconductor devices.
Implementation Method 1
forming a first film on the processing target; forming a second film on the first film
Implementation Method 2
forming a first film on the processing target; forming a second film on the first film
Implementation Method 3
etching the second film under a predetermined processing condition until a portion of the first film is removed
Data Source
AI summary
A plasma processing method executed by a plasma processing apparatus includes a first step, a second step, and an etching step. In the first step, the plasma processing apparatus forms a first film on a processing target in which a plurality of openings having a predetermined pattern are formed. In the second step, the plasma processing apparatus forms a second film having an etching rate lower than that of the first film on the processing target on which the first film is formed, and having different film thicknesses on the side surfaces of the openings according to the sizes of the openings. In the etching step, the plasma processing apparatus performs etching from above the second film under a predetermined processing condition until a portion of the first film is removed from at least a portion of the processing target.