MOS Capacitor Impurity Grading for High Capacitance and Low Leakage
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Solution Overview
Problem
Conventional semiconductor devices struggle to simultaneously achieve high capacitance and low leakage current characteristics in MOS type capacitors, requiring different insulating film thicknesses and complex processes, which complicates manufacturing and increases costs.
Innovation Solution
The semiconductor device incorporates two MOS type capacitors with distinct impurity concentration distributions in their electrodes, allowing for a high capacitance value in one and a low leakage current in the other on the same substrate, achieved through controlled impurity implantation and heat treatment without varying insulating film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thin insulating film is formed to increase capacitance, then capacitance value is improved, but leakage current increases
Solution Approach 1:
The patent applies local quality by forming a first insulating film with a first thickness in a first region and a second insulating film with a second thickness (greater than the first thickness) in a second region. This allows different regions to have different insulating film thicknesses tailored to their specific functional requirements, enabling one region to achieve high capacitance while another region achieves low leakage current.
2Reliability
If different insulating film thicknesses are formed for high capacitance and low leakage current capacitors, then both characteristics are achieved, but manufacturing process complexity increases
Solution Approach 1:
The patent segments the semiconductor substrate into a first region and a second region, where each region receives a different insulating film thickness. This segmentation allows independent optimization of capacitor characteristics in different regions while using a unified manufacturing process flow, thereby achieving diverse performance characteristics without proportionally increasing overall process complexity.
Solution Approach 2:
The patent changes the insulating film thickness parameter across different regions of the semiconductor substrate. By forming a first insulating film with a first thickness and a second insulating film with a second thickness (where the second thickness is greater than the first thickness), the patent achieves different capacitor characteristics (high capacitance vs. low leakage current) through parameter variation rather than requiring fundamentally different manufacturing processes.
3Reliability
If multiple insulating films with different thicknesses are formed, then both high capacitance and low leakage current capacitors are achieved, but manufacturing cost increases
Solution Approach 1:
The patent achieves multi-functionality by using a single semiconductor substrate to host both high capacitance capacitors (in the first region with thinner insulating film) and low leakage current capacitors (in the second region with thicker insulating film). This universal approach allows one substrate to serve multiple functional purposes, reducing the need for separate processing lines or additional components, thereby controlling manufacturing costs while achieving diverse capacitor performance.
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 enables the production of semiconductor devices with both high capacitance and low leakage current capacitors on the same substrate, simplifying the manufacturing process and reducing costs while maintaining high performance.
Implementation Method 1
impurities are implanted to the first electrode 109 and the second electrode 110 by ion implantation
Implementation Method 2
the semiconductor substrate 101 is subjected to heat treatment such as RTA (Rapid Thermal Annealing) or LSA (Laser Spike Annealing) to activate the impurities implanted in each layer
Implementation Method 3
an insulating film 104 is formed on the semiconductor substrate 101 by oxidation or the like
Data Source
AI summary
A semiconductor device includes a first MOS type capacitor having a first insulating film and a first electrode that are formed on a semiconductor substrate, and a second MOS type capacitor having a second insulating film and a second electrode that are formed on the semiconductor substrate. The first electrode has a first concentration difference as a difference when an impurity concentration in an interface region with the first insulating film is subtracted from an impurity concentration in a top portion of the first electrode. The second electrode has a second concentration difference as a difference when an impurity concentration in an interface region with the second insulating film is subtracted from an impurity concentration in a top portion of the second electrode. The second concentration difference is larger than the first concentration difference.