Semiconductor Device Gate Electrode Impurity Concentration Control
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Solution Overview
Problem
Existing methods for forming semiconductor devices with different power source voltages on the same substrate face challenges such as increased number of steps, damage to silicon substrates, and reduced reliability due to high concentration ion implantation for accelerated oxidation, which affects the quality and thickness of gate and capacitive oxide films.
Innovation Solution
The method involves forming semiconductor devices with electrodes having different impurity concentrations to control the effective thickness of insulating films, using impurity implantation and processing to achieve desired electrical thicknesses for gate and capacitive insulating films without increasing the number of steps, thereby preventing depletion and maintaining film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high concentration ion implantation is used for accelerated oxidation to form thick oxide films for high voltage transistors, then the oxide film thickness is increased, but the silicon substrate is damaged and film quality is reduced
Solution Approach 1:
The patent applies local quality by implanting impurities selectively in specific regions where thick oxide films are needed (such as I/O regions and analog circuit regions) while leaving other regions (like digital circuit regions) unaffected. This allows different parts of the substrate to have different oxide film thicknesses tailored to their specific voltage requirements, avoiding the need for high concentration ion implantation across the entire substrate and thus preventing substrate damage.
Solution Approach 2:
The patent uses preliminary action by first forming a thin oxide film uniformly across the entire substrate, then selectively implanting impurities in regions requiring thicker oxide films, and finally performing a second oxidation step. This preliminary formation of the thin oxide film provides a foundation that prevents substrate damage during the subsequent selective thickening process, while the impurity implantation accelerates oxidation only in needed regions.
2Length of stationary object
If multiple photo resist patterning steps and wet etching steps are repeated to form oxide films of different thicknesses, then various thicknesses are achieved, but the number of steps increases and oxide film damage occurs
Solution Approach 1:
The patent merges multiple separate processes (oxide film formation and impurity implantation) into a single integrated process flow. By combining the impurity implantation step with the oxidation process, the patent achieves different oxide film thicknesses in different regions without requiring separate patterning and etching steps for each thickness variation, thereby reducing the total number of process steps.
Solution Approach 2:
The patent changes the parameter of oxidation rate by introducing impurities into specific regions, which accelerates the oxidation process locally. This parameter change allows different regions to develop different oxide film thicknesses during a single oxidation step, eliminating the need for multiple oxidation cycles with different patterning steps.
3Length of stationary object
If high concentration ions are implanted to promote accelerated oxidation for capacitors, then the capacitive oxide film becomes thicker, but more damage is given to the silicon substrate and reliability is reduced
Solution Approach 1:
The patent applies local quality by selectively implanting impurities only in regions where capacitors are to be formed, rather than across the entire substrate. This localized approach achieves the necessary thick oxide film for capacitor insulation only where needed, minimizing substrate damage to regions where thin oxide films are sufficient for transistor operation.
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 allows for the securement of electrical effective thicknesses for insulating films, ensuring reliable operation of transistors and capacitors with different power sources while minimizing the number of steps and substrate damage, thus enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
a gate electrode 4b having a higher concentration of impurity than the capacitor electrode 4c, thereby depletion under the gate electrode 4b is prevented
Implementation Method 2
forming a gate electrode layer containing an impurity on the gate insulating film
Data Source
AI summary
A semiconductor device able to secure electrical effective thicknesses required for insulating films of electronic circuit elements by using depletion of electrodes of the electronic circuit elements even if the physical thicknesses of the insulating films are not different, where gate electrodes of high withstand voltage use transistors to which high power source voltages are supplied contain an impurity at a relatively low concentration, so the gate electrodes are easily depleted at the time of application of the gate voltage; depletion of the gate electrodes is equivalent to increasing the thickness of the gate insulating films; the electrical effective thicknesses required of the gate insulating films can be made thicker; and the gate electrodes of high performance transistors for which a high speed and large drive current are required do not contain an impurity at a high concentration where depletion of the gate electrodes will not occur, so the electrical effective thickness of the gate insulating films is kept thin.