Solid State Image Pickup Contact Resistance Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the manufacturing of solid state image pickup apparatuses, the contact resistance between semiconductor regions and metal in pixel regions is increased due to metal scattering from the peripheral circuit region into the pixel region, leading to potential leakage currents and noise.
Innovation Solution
A method involving the formation of a high-concentration impurity layer at the contact bottom portion and using a compound layer composed of metal and semiconductor on the gate electrode, drain region, and source region in the peripheral circuit, while ensuring the compound layer is not exposed in the pixel region to prevent metal diffusion, thereby reducing contact resistance and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a compound layer composed of metal and semiconductor is disposed on the gate electrode, drain region, and source region in the peripheral circuit region, then high-speed operation is achieved, but metal scatters into the pixel region causing increased contact resistance and leakage currents
Solution Approach 1:
The patent divides the semiconductor substrate into distinct pixel region and peripheral circuit region, with the compound layer selectively disposed only in the peripheral circuit region on the gate electrode, drain region, and source region. This spatial segmentation prevents metal scattering from affecting the pixel region while maintaining high-speed operation in the peripheral circuit region.
Solution Approach 2:
The compound layer is applied locally only to specific regions (gate electrode, drain region, source region) in the peripheral circuit region, not uniformly across the entire substrate. This local quality approach ensures high-speed operation where needed while preventing metal scattering into the pixel region, thus resolving the contradiction between speed and reliability.
2Reliability
If the compound layer is disposed on the gate electrode, drain region, and source region, then transistor performance is improved, but metal diffusion into the pixel region occurs causing noise and leakage currents
Solution Approach 1:
The patent extracts the compound layer formation process to be applied only in the peripheral circuit region, separating it from the pixel region. By taking out the compound layer application from the entire substrate and limiting it to specific peripheral circuit regions, metal diffusion into the pixel region is prevented while maintaining improved transistor performance where the compound layer is applied.
Solution Approach 2:
The patent uses the peripheral circuit region as an intermediary zone where the compound layer is selectively disposed. This intermediary approach allows the beneficial effects of the compound layer (improved transistor performance) to be realized in the peripheral circuit region while preventing harmful metal diffusion into the pixel region, thus resolving the contradiction between reliability and harmful factors.
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 effectively reduces contact resistance and suppresses leakage currents in the photoelectric conversion unit, enhancing the operational speed and reliability of the solid state image pickup apparatus without increasing production steps or costs.
Implementation Method 1
forming, by removing part of an insulating layer by using a first mask, a first contact opening on an impurity region, and a second contact opening over a compound layer
Implementation Method 2
ion-implanting an impurity into the impurity region through the first contact opening while the first portion that covers the compound layer is exposed at the second contact opening
Data Source
AI summary
A method for manufacturing a solid state image pickup apparatus, including the steps of forming, by removing part of an insulating layer by using a first mask, a first contact opening on an impurity region, and a second contact opening over a compound layer such that a first portion, which covers the compound layer, of the insulating layer is exposed at a bottom of the second contact opening, and ion-implanting an impurity into the impurity region through the first contact opening while the first portion covering the compound layer is exposed at the second contact opening, wherein the impurity region is disposed in a pixel region including a photoelectric conversion unit, and the compound layer is disposed on at least one of a gate electrode, a drain region, and a source region of a transistor disposed in a peripheral circuit region and is composed of a metal and a semiconductor.