Side-Diffused Trench Plug Structure for Narrower Semiconductor Isolation
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Solution Overview
Problem
Existing semiconductor plug formation techniques require high thermal budgets and result in large lateral widths due to lateral diffusion and thick silicon layers, limiting device spacing and efficiency.
Innovation Solution
A semiconductor device structure and method involving a trench etched into the semiconductor layer with vertical sidewalls, filled with a dopant layer, and annealed to form a diffused region with vertical boundaries, reducing thermal budget and allowing for narrower plug widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature thermal treatment is used to form semiconductor plug structures, then dopant species can be driven to target depth for forming junction isolation or low resistance structures, but the thermal budget increases and lateral diffusion occurs resulting in larger lateral width
Solution Approach 1:
The invention segments the plug formation process into two independent steps: first forming the plug depth through ion implantation followed by low-temperature annealing, then separately forming the lateral width through a second ion implantation step. This segmentation allows independent control of depth and width parameters, resolving the contradiction between achieving sufficient depth while minimizing lateral diffusion.
Solution Approach 2:
The invention performs preliminary ion implantation to the full target depth before performing lateral width formation. By establishing the depth profile first through ion implantation and low-temperature annealing, subsequent lateral diffusion is minimized because the temperature budget has already been consumed in the first annealing step.
2Reliability
If thick silicon layers are employed to achieve acceptable isolation properties, then junction isolation can be formed, but the lateral width of the semiconductor plug structure increases
Solution Approach 1:
The invention changes the doping parameter profile by using ion implantation with specific doses and energies to create the depth profile, then using a second ion implantation step with different parameters to form the lateral width. This parameter separation allows achieving reliable isolation properties through controlled doping profiles without being constrained by lateral width increases from thermal diffusion in thick layers.
3Stability of the object's composition
If lateral diffusion is allowed during thermal treatment, then dopant species distribute throughout the semiconductor layer, but the lateral width of the semiconductor plug structure increases restricting device spacing
Solution Approach 1:
The invention performs preliminary ion implantation to establish the dopant distribution at the target depth before performing lateral width formation. The first ion implantation and low-temperature annealing step establishes the vertical dopant profile, and subsequent lateral diffusion is controlled because the thermal budget has already been consumed.
Solution Approach 2:
The invention uses different ion implantation parameters (dose, energy, angle) for the first and second implantation steps to independently control vertical depth distribution and lateral width. This parameter separation allows achieving stable dopant distribution without excessive lateral diffusion that would restrict device spacing.
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
The approach reduces the thermal budget and achieves narrower semiconductor plug widths, enhancing device spacing and efficiency by controlling the width independently of depth, facilitating better device integration.
Implementation Method 1
annealing the substrate, wherein a diffused region is formed, the diffused region having a first boundary and a second boundary, the first boundary and second boundary extending within the semiconductor layer from the first trench sidewall and the second trench sidewall
Data Source
Figure 1A~1D
Figure 2A~2F
Figure 3A~3C
AI summary
A semiconductor device structure may include a substrate having a substrate base comprising a first dopant type; a semiconductor layer disposed on a surface of the substrate base, the semiconductor layer comprising a second dopant type and having an upper surface; and a semiconductor plug assembly comprising a semiconductor plug disposed within the semiconductor layer, the semiconductor plug extending from an upper surface of the semiconductor layer and having a depth at least equal to a thickness of the semiconductor layer, the semiconductor plug having a first boundary, the first boundary formed within the semiconductor layer, and having a second boundary, the second boundary formed within the semiconductor layer and disposed opposite the first boundary, wherein the first boundary and second boundary extend perpendicularly to the surface of the substrate base.