Semiconductor Trench Isolation With Controlled Space Height
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Solution Overview
Problem
Forming an insulating film in a trench portion with a high aspect ratio is challenging due to difficulties in precisely controlling the closed position of the space left in the trench, leading to potential exposure during polishing and planarization, which can result in defective semiconductor devices with foreign matter issues.
Innovation Solution
A method involving the use of a hard mask, a first insulating film, and a second insulating film to form a space in the trench, where the first insulating film covers the side wall and the second insulating film covers the trench surface, allowing for precise control of the space height and preventing exposure during subsequent processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating film is formed by CVD to close the trench portion, then the element isolation properties are improved, but the closed position of the space cannot be precisely controlled and may become higher than the desired position
Solution Approach 1:
The insulating film formation process is segmented into two distinct steps: first forming a liner insulating film to cover the trench surface and hard mask, then forming a main insulating film to close the trench. This segmentation allows independent control of each film's thickness and position, enabling precise control of the space closed position while maintaining element isolation properties.
Solution Approach 2:
The liner insulating film is formed in advance before the main insulating film. This preliminary action creates a reference surface and protective layer that enables subsequent precise control of the main insulating film's deposition, ensuring the closed position reaches exactly the upper end of the space without exceeding it.
2Reliability
If the closed position of the space is higher than the desired position, then element isolation is achieved, but the space becomes exposed during polishing and planarization, leading to foreign matter contamination
Solution Approach 1:
The liner insulating film is formed in advance to create a precise reference surface. This preliminary layer ensures that when the main insulating film is deposited, the closed position of the space is controlled to reach exactly the upper end without exceeding it, preventing exposure during subsequent polishing and planarization steps.
Solution Approach 2:
The formation process uses different deposition parameters for the liner insulating film and main insulating film. The liner film is formed with controlled thickness to cover the trench surface and hard mask, while the main film is deposited to a specific thickness that closes the trench at the precise upper end of the space, preventing foreign matter contamination.
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 element isolation properties and performance of semiconductor devices by maintaining the integrity of the trench structure, reducing the risk of foreign matter introduction and improving the breakdown voltage and leakage current characteristics.
Implementation Method 1
covering the surface of the trench and the upper surface of the hard mask with a first insulating film
Implementation Method 2
forming a second insulating film to close an upper portion of the trench to form a space therein
Data Source
AI summary
To provide a semiconductor device having an element isolation structure formed in the main surface of a semiconductor substrate, having a space in a trench, and prevented from having deteriorated performance due to an increase in the height of the top portion of the space. A trench portion is formed in the main surface of a semiconductor substrate by using a hard-mask insulating film. A first insulating film that covers the upper surface of the hard-mask insulating film and the surface of the trench portion is formed, followed by etch-back of the first insulating film to expose the upper surface of the hard-mask insulating film. Then, second and third insulating films that cover the upper surface of the hard-mask insulating film and the surface of the trench portion are formed to form a space in the trench portion.