MIM Capacitor Insulator Stack for Stable Withstand Voltage
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Solution Overview
Problem
Conventional MIM capacitors in semiconductor devices often fail to provide sufficient withstand voltage between the lower and upper electrodes due to defects in the semiconductor layer, leading to dielectric breakdown.
Innovation Solution
Incorporating a first insulator layer with a polyimide or silicon oxide surface over the semiconductor layer, along with additional insulator layers containing silicon, to enhance the flatness and adhesion between electrodes, thereby minimizing dielectric breakdown and improving withstand voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional MIM capacitor structure is used with a semiconductor layer, then the device can be manufactured with standard processes, but defects in the semiconductor layer cause insufficient withstand voltage and dielectric breakdown
Solution Approach 1:
An insulator layer is introduced between the semiconductor layer and the lower electrode to act as an intermediary that prevents harmful effects. This insulator layer has a flat upper surface that prevents electric field concentration, thereby preventing dielectric breakdown even when the semiconductor layer contains defects such as pits or protrusions.
Solution Approach 2:
The insulator layer is placed beforehand to cushion or buffer the harmful effects of semiconductor layer defects before they can cause dielectric breakdown. By positioning this protective layer in advance, the patent prevents the concentration of electric fields that would otherwise occur at defective regions of the semiconductor layer.
2Reliability
If the upper surface of the insulator layer is not flat, then manufacturing is simpler, but electric field concentration occurs leading to dielectric breakdown
Solution Approach 1:
The patent applies a specific property (flat upper surface) to a local region (the upper surface of the insulator layer that contacts the lower electrode) to prevent dielectric breakdown. This localized flatness ensures uniform electric field distribution in the critical region between electrodes, while other regions of the device can maintain standard manufacturing tolerances.
3Reliability
If additional insulator layers are added to improve flatness and adhesion, then withstand voltage stability improves, but device complexity increases
Solution Approach 1:
The insulator layer performs multiple functions simultaneously: it provides a flat upper surface to prevent electric field concentration, offers adhesion between the semiconductor layer and lower electrode, and acts as an additional insulating barrier. By combining these functions into a single layer, the patent improves reliability without proportionally increasing device complexity.
Data Source
AI summary
A semiconductor device includes a substrate having a first upper surface; a semiconductor layer provided on the substrate; a first insulator layer provided over the semiconductor layer and having a second upper surface; a lower electrode provided over the first insulator layer; a dielectric layer provided on the lower electrode; and an upper electrode provided on the dielectric layer. A difference between a maximum value and a minimum value of a distance between the first upper surface of the substrate and the second upper surface of the first insulator layer is smaller than a thickness of the semiconductor layer.