ILD Recess Etching for Uniform Semiconductor Capping Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Process variation in forming capping layers during semiconductor processing can lead to reduced effectiveness and yield of subsequent processes, causing defects such as etching depth reduction, dishing, or void formation.
Innovation Solution
The techniques involve optimizing gas flow rates in an etch tool to promote uniformity of etch rates, thereby increasing the uniformity of recesses in interlayer dielectric (ILD) layers, which in turn allows for the formation of highly uniform capping layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form recesses in ILD layers, then the etching process can be completed, but process variation leads to non-uniform recess depths and defects such as dishing or void formation
Solution Approach 1:
The patent applies parameter changes by optimizing gas flow rates (e.g., NF3 at 500 sccm, CF4 at 100 sccm) and adjusting etching conditions to achieve uniform etching rates across the wafer surface. This resolves the contradiction by modifying process parameters to simultaneously achieve precise recess depth control and high yield in subsequent capping layer formation processes
2Productivity
If higher etching rates are used to increase productivity, then the etching process is faster, but uniformity of recess depths decreases leading to more defects
Solution Approach 1:
The patent changes multiple parameters simultaneously - gas composition (NF3/CF4 mixture), flow rates (500 sccm/100 sccm), and pressure conditions - to achieve an optimal balance where high etching productivity is maintained while recess depth uniformity is improved to within 1.6 nanometers variation
Solution Approach 2:
The etching process uses periodic gas flow patterns and pulsed deposition techniques to maintain uniform etching rates across the wafer surface, allowing high productivity while preventing local variations that would reduce precision
3Ease of manufacture
If capping layers are formed without optimized recess uniformity, then the process can proceed, but defect formation increases and yield is reduced
Solution Approach 1:
The patent performs preliminary optimization of the etching process to create uniformly deep recesses before forming capping layers. This preliminary action ensures that subsequent capping layer deposition proceeds without defects, maintaining both process continuity and high yield
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 significantly reduces the likelihood of defect formation and yield loss, while enhancing the performance of semiconductor devices by ensuring uniform capping layers with reduced variation from approximately 4 nanometers to approximately 1.6 nanometers or less.
Implementation Method 1
An example etch recipe includes providing a first gas flow of NF3 at a rate of approximately 500 sccm and a second gas flow of CF4 at a rate of approximately 100 sccm
Data Source
AI summary
Recesses may be formed in portions of an ILD layer of a semiconductor device in a highly uniform manner. Uniformity in depths of the recesses may be increased by configuring flows of gases in an etch tool to promote uniformity of etch rates (and thus, etch depth) across the semiconductor device, from semiconductor device to semiconductor device, and/or from wafer to wafer. In particular, the flow rates of gases at various inlets of the tch tool may be optimized to provide recess depth tuning, which increases the process window for forming the recesses in the portions of the ILD layer. In this way, the increased uniformity of the recesses in the portions of the ILD layer enables highly uniform capping layers to be formed in the recesses.