Substrate Thinning via Buried Layer Stop
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Solution Overview
Problem
Conventional substrate thinning methods in semiconductor technology are prone to inaccuracies due to sensitivity to doping levels and impurity diffusion, leading to variations in substrate thickness and electrical properties, which can impair the performance of integrated circuits.
Innovation Solution
A method involving the formation of a buried layer with a solid-state compound having greater resistance to thinning, acting as both a thinning stop and diffusion barrier, using ion implantation of chemical elements like carbon or nitrogen to create a stable layer that prevents impurity atoms from diffusing and ensures precise substrate thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional grinding or electrochemical etching is used for substrate thinning, then substrate thickness can be reduced, but manufacturing precision deteriorates due to sensitivity to doping levels and impurity diffusion
Solution Approach 1:
A buried layer is formed in advance at a predetermined depth within the substrate before the thinning process. This buried layer serves as a pre-established reference marker that enables precise thickness control during subsequent processing steps, eliminating the need for complex real-time adjustments during thinning.
Solution Approach 2:
The buried layer acts as an intermediary reference structure between the thinning process and the final substrate thickness specification. By providing a physically distinct layer with different etching characteristics, it mediates the thinning process to achieve uniform and precise thickness control across the substrate.
2Manufacturing precision
If substrate thinning is performed to achieve precise thickness control, then manufacturing precision improves, but impurity diffusion occurs which deteriorates electrical properties
Solution Approach 1:
The buried layer serves as a diffusion barrier that mediates between the thinning process and the substrate's impurity content. It prevents impurity atoms from diffusing into active regions during thermal processing steps that accompany thinning, thereby maintaining electrical property stability while achieving precise thickness control.
Solution Approach 2:
The buried layer introduces local quality differentiation within the substrate structure. By creating a region with distinct chemical composition and diffusion characteristics at a specific depth, it provides localized protection against impurity diffusion without affecting the overall thinning process or other substrate regions.
3Reliability
If a buried layer is formed to prevent impurity diffusion, then reliability improves, but device complexity increases
Solution Approach 1:
The buried layer is designed to perform multiple functions simultaneously: it serves as a diffusion barrier to prevent impurity migration, a reference marker for precise thickness measurement, and a mechanical strengthening element. This multi-functionality reduces the need for separate structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The formation of the buried layer is merged with existing substrate preparation processes. By integrating the diffusion barrier function into the substrate structure itself rather than adding separate components, the solution achieves reliability improvement with minimal increase in overall device complexity.
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 reduces substrate thickness variations and prevents impurity diffusion, enhancing the reliability and performance of integrated circuits by providing a precise and stable thinning process.
Implementation Method 1
using ion implantation of chemical elements like carbon or nitrogen to create a stable layer
Implementation Method 2
the buried layer may include a solid state compound having a greater resistance to the thinning than the substrate and wherein the thinning stops at the buried layer
Data Source
AI summary
According to various embodiments, a method may include: providing a substrate having a first side and a second side opposite the first side; forming a buried layer at least one of in or over the substrate by processing the first side of the substrate; thinning the substrate from the second side of the substrate, wherein the buried layer includes a solid state compound having a greater resistance to the thinning than the substrate and wherein the thinning stops at the buried layer.