Sensor Chip Metal Etch Stop for Uniform Gap Depth
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Solution Overview
Problem
Existing sensor chips face challenges in achieving uniform etch depths and measuring material volumes between electrode elements, leading to varying measurement results due to uncontrollable etching processes.
Innovation Solution
A sensor chip design featuring a metal structure at a second level on the substrate, acting as an etch stop in addition to electrode elements, ensures uniform etch depths by extending over projected gaps between electrode elements, with the metal structure's area being slightly smaller or larger than the projected gap to effectively stop the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If etching time is defined upfront to etch insulating material in gaps between electrode elements, then the etching process can be controlled, but the etch depth varies across the wafer and from wafer to wafer
Solution Approach 1:
The patent introduces a metal etch stop layer positioned between the insulating material and the substrate at locations corresponding to the gaps between electrode elements. This preliminary structural preparation ensures that when etching is performed, the metal layer automatically stops the etching process at a predetermined depth, eliminating the need to precisely control etching time while ensuring uniform etch depth across the wafer and between wafers.
2Manufacturing precision
If electrode elements serve as etch stop, then etching can be stopped at electrode elements, but gaps between electrode elements cannot be effectively stopped
Solution Approach 1:
The patent segments the etch stop function into two parts: the electrode elements serve as etch stops where they are present, and the metal etch stop layer serves as etch stops in the gaps between electrode elements. This segmentation ensures complete coverage of etch stop functionality across the entire sensor chip area, addressing both regions effectively.
Solution Approach 2:
The metal etch stop layer acts as an intermediary structure that bridges the gap between the insulating material and the substrate in regions where electrode elements are absent. This intermediary layer provides the necessary etch stop functionality in the gaps, complementing the electrode elements' etch stop role and ensuring uniform etching across the entire chip.
3Ease of manufacture
If varying etch depth is accepted, then manufacturing is simpler, but measurement results vary requiring increased calibration efforts
Solution Approach 1:
By pre-positioning the metal etch stop layer at a specific depth between the insulating material and substrate, the patent establishes a predetermined etching depth limit before the etching process begins. This preliminary structural constraint ensures that the etching process automatically achieves uniform depth across all wafers and locations, eliminating measurement variations without requiring extensive calibration efforts.
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 design results in a sensor chip with uniform gaps between electrode elements, allowing for consistent filling with measuring material and improved measurement accuracy, reducing the need for extensive calibration.
Implementation Method 1
the metal structure acts as an etch stop in addition to the electrode elements
Data Source
Figure 1~2b
Figure 2c~2e
Figure 2f~3
AI summary
The present sensor chip comprises a substrate (1). A plurality of electrode elements (5) is arranged at a first level (L1) on the substrate (1) with at least one gap (g5) between neighbouring electrode elements (5). A metal structure (6) is arranged at a second level (L2) on the substrate (1), wherein the second level (L2) is different from the first level (L1). The metal structure (6) at least extends over an area of the second level (L2) that is defined by a projection of the at least one gap (g5) towards the second level (L2).