Etching Method for Fine and Large Hole CD Control
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Solution Overview
Problem
Existing etching methods struggle to control the critical dimension (CD) of fine and large holes etched simultaneously, often resulting in over-etching and connection of fine holes, due to the lack of precise control over the etching process for different patterns.
Innovation Solution
A method involving a substrate processing apparatus that performs a first etching step, followed by a deposition step to clog the openings of fine holes while maintaining the openings of large holes, and a second etching step to deepen the large holes without affecting the fine holes, using specific gas combinations and power settings to control the protective film deposition and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single etching process is used to etch both fine holes and large holes simultaneously, then the process is simple and fast, but the critical dimension of fine holes cannot be controlled precisely due to over-etching and connection
Solution Approach 1:
The single etching process is divided into two separate etching steps: a first etching step that etches both fine holes and large holes to a first depth, and a second etching step that etches only large holes to a second depth. This segmentation allows precise control of fine hole CD while maintaining high productivity through batch processing.
Solution Approach 2:
A protective film is deposited on the mask before the second etching step to prevent etching of fine holes during the second step. This preliminary protective action ensures that fine holes are not over-etched or connected, while allowing large holes to be etched deeper in the same batch.
2Reliability
If the etching depth is increased to ensure complete etching of large holes, then large holes are properly formed, but fine holes become over-etched and connected
Solution Approach 1:
The etching process is segmented into two depth levels: a first etching step that etches to a first depth suitable for fine holes, and a second etching step that etches to a second depth for large holes. This ensures complete etching of large holes without over-etching fine holes.
Solution Approach 2:
A protective film is introduced as an intermediary layer on the mask during the second etching step. This protective film acts as a barrier that prevents the etchant from reaching and over-etching fine holes, while allowing the second etching step to complete the large holes to the required depth.
3Manufacturing precision
If separate etching processes are used for fine holes and large holes, then critical dimension is controlled precisely, but the process complexity and time increase
Solution Approach 1:
The process merges the advantages of separate etching by combining two etching steps and one deposition step into a single batch process. While the process has multiple steps, fine holes and large holes are processed together in the same chamber sequence, reducing overall complexity compared to completely separate processing lines.
Solution Approach 2:
The protective film deposition is performed as a preliminary action before the second etching step, allowing the system to prepare for selective etching in advance. This preliminary preparation enables the subsequent second etching step to proceed efficiently without requiring additional process interruptions or equipment changes.
4Manufacturing precision
If a protective film is deposited on the mask to prevent fine hole etching, then fine hole CD is controlled, but the process time increases due to additional deposition step
Solution Approach 1:
The deposition step is merged into the same batch process sequence as the two etching steps, performed without breaking vacuum or removing the substrate from the processing chamber. This integration minimizes the total process time by eliminating transitions between separate equipment or atmospheric exposures.
Solution Approach 2:
The protective film deposition is performed continuously in the same chamber without interrupting the batch process flow. The substrate remains in the chamber throughout the deposition and subsequent second etching step, maintaining continuous useful action and avoiding time loss from chamber evacuation, loading, or unloading operations.
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 allows for precise control of CD in both fine and large holes, preventing over-etching and connection of fine holes, thereby improving the accuracy and efficiency of the etching process.
Implementation Method 1
a first etching step of etching the etching film to a predetermined depth; a deposition step of depositing a protective film on the mask after the first etching step
Implementation Method 2
a deposition step of depositing a protective film on the mask after the first etching step
Data Source
AI summary
A method of etching a substrate including an etching film and a mask formed on the etching film is provided. The mask includes a first pattern of a first recess having a first opening and a second pattern of a second recess having a second opening. The method includes etching the etching film to a predetermined depth; depositing a protective film on the mask after the etching; and etching the etching film after the depositing. The first opening is smaller than the second opening. As a result of the depositing, the first opening of the first pattern is clogged and the second opening of the second pattern is not clogged.