Etch Stop Layer for Through-Substrate Interconnects
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Solution Overview
Problem
Existing methods for manufacturing semiconductor devices with through-substrate interconnects often result in a reduction of the intermetal dielectric thickness above the substrate during etching, leading to a loss of material and potentially affecting the integrity of the interconnect.
Innovation Solution
The method involves applying an etch stop layer on the intermetal dielectric before forming the side wall spacer and removing the insulation layer, which prevents the removal of the intermetal dielectric above the metal planes, thereby maintaining the initial thickness of the intermetal dielectric and ensuring precise etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching steps are performed to form the interconnect through the substrate, then the opening is formed and the insulation layer is removed, but the thickness of the intermetal dielectric above the metal planes is reduced
Solution Approach 1:
An etch stop layer is applied on the intermetal dielectric before the etching process begins. This preliminary action creates a protective barrier that prevents the etchant from removing the intermetal dielectric above the metal planes during subsequent etching steps, thereby resolving the contradiction between forming the opening and preserving the dielectric thickness.
Solution Approach 2:
The etch stop layer acts as an intermediary between the etchant and the intermetal dielectric. It is selectively removed after serving its protective function, allowing the process to continue while having prevented the harmful removal of the intermetal dielectric material during the critical etching phases.
2Reliability
If the insulation layer is removed from the bottom of the opening to uncover the connection pad, then electrical contact is enabled, but the intermetal dielectric above the metal planes is inadvertently removed
Solution Approach 1:
The etch stop layer is applied in advance before the insulation layer removal step. This preliminary protective measure ensures that when the insulation layer is removed from the bottom of the opening to expose the connection pad, the etchant cannot attack and remove the intermetal dielectric above the metal planes, thus maintaining both electrical connection reliability and dielectric thickness precision.
Solution Approach 2:
The etch stop layer serves as a protective intermediary during the insulation layer removal process. It allows selective removal of the insulation layer at the bottom while blocking the etchant from reaching and removing the intermetal dielectric above the metal planes, thereby resolving the contradiction between enabling electrical contact and maintaining dielectric integrity.
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 effectively maintains the thickness of the intermetal dielectric, resulting in a more reliable and precise formation of the interconnect through the substrate, enhancing the semiconductor device's performance and reducing material loss during the etching process.
Implementation Method 1
An etch stop layer is applied on the intermetal dielectric before the dielectric layer is produced, the etch stop layer being provided to prevent a removal of the intermetal dielectric above the metal planes during the formation of the side wall spacer and during the removal of the insulation layer from the bottom of the opening
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A semiconductor substrate (1) is provided on a main surface (14) with an intermetal dielectric (4) including metal planes (5) and on an opposite rear surface (15) with an insulation layer (2) and an electrically conductive connection pad (7). An etch stop layer (6) is applied on the intermetal dielectric to prevent a removal of the intermetal dielectric above the metal planes during subsequent method steps. An opening (9) having a side wall (3) and a bottom (13) is formed from the main surface through the substrate above the connection pad. A side wall spacer (10) is formed on the side wall by a production and subsequent partial removal of a dielectric layer (11). The insulation layer is removed from the bottom to uncover an area of the connection pad. A metal layer is applied in the opening and is provided for an interconnect through the substrate.