Alignment Mark Dielectric Structure for Thick Silicon Wafers
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Solution Overview
Problem
The challenge in semiconductor manufacturing is achieving accurate alignment on thicker silicon substrates, as the through silicon alignment process becomes difficult due to the increased thickness, which hinders the formation of components on the back side of wafers.
Innovation Solution
A method involving the introduction of heteroatoms into the substrate to form a dielectric layer overlapping the alignment mark, allowing for improved alignment accuracy by reducing the substrate thickness above the alignment mark, enabling either a through thin silicon or non-through silicon alignment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thicker thinned substrate is used, then the substrate provides sufficient mechanical strength and structural integrity, but the through silicon alignment process becomes difficult or impossible to perform
Solution Approach 1:
The substrate is divided into two distinct regions: a first region with sufficient thickness for mechanical strength and a second region with reduced thickness for alignment. This segmentation allows the substrate to simultaneously provide structural integrity while enabling through-silicon alignment processes.
Solution Approach 2:
Different thickness characteristics are applied to different regions of the substrate. The first region maintains original thickness for strength, while the second region has locally reduced thickness to enable light transmission for alignment marks, creating local quality variation to solve the contradiction.
2Manufacturing precision
If the substrate thickness is reduced to enable through silicon alignment, then alignment precision is improved, but the substrate loses mechanical strength and structural integrity
Solution Approach 1:
The substrate is divided into two distinct regions: a first region with sufficient thickness for mechanical strength and a second region with reduced thickness for alignment. This segmentation allows the substrate to simultaneously provide structural integrity while enabling through-silicon alignment processes.
Solution Approach 2:
Different thickness characteristics are applied to different regions of the substrate. The first region maintains original thickness for strength, while the second region has locally reduced thickness to enable light transmission for alignment marks, creating local quality variation to solve the contradiction.
3Manufacturing precision
If ion implantation is performed to introduce heteroatoms, then a dielectric layer is formed to improve alignment, but additional manufacturing steps and process complexity are introduced
Solution Approach 1:
Ion implantation to introduce heteroatoms is performed before substrate thinning. This preliminary action allows the dielectric layer to form in advance, facilitating subsequent alignment processes and reducing the complexity of coordinating multiple steps.
Solution Approach 2:
The substrate undergoes parameter changes through ion implantation, where heteroatoms are introduced to alter the material properties and form a dielectric layer. This changes the physical and chemical characteristics of the substrate in the second region, enabling improved alignment without requiring extreme thickness reduction.
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 alignment precision and facilitates the formation of components on thicker substrates by creating a thinner effective alignment path, improving the accuracy of photolithographic processes on the back side of wafers.
Implementation Method 1
performing an ion implantation process
Implementation Method 2
reacting the heteroatoms with the substrate to form a dielectric layer
Data Source
AI summary
Provided is a semiconductor device includes a substrate, an isolation structure, an alignment mark, and a dielectric layer. The substrate includes a first region and a second region. The isolation structure is disposed in the substrate in the first region, wherein the isolation structure extends from a first surface of the substrate toward a second surface of the substrate.The alignment mark is disposed in the substrate in the second region. The alignment mark extends from the first surface of the substrate toward the second surface of the substrate and at the same level as the isolation structure. The dielectric layer is buried in the substrate in the second region and overlapping the alignment mark.