Contact Hole Etching with Sacrificial Layers to Minimize Substrate Loss
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Solution Overview
Problem
The manufacturing of semiconductor devices with contact holes of different etch depths poses challenges due to varying step heights, leading to substrate loss and inefficiencies during the manufacturing process.
Innovation Solution
A method is developed to minimize substrate loss by forming first and second etch targets at different levels, creating dielectric layers, and using sacrificial layers to control etching and gap-filling processes, allowing for the formation of contact holes with conductive materials while maintaining etch selectivity and minimizing substrate exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contact holes are formed to accommodate different step heights of conductive lines, then contacts with different etch depths can be achieved, but substrate loss occurs during the manufacturing process
Solution Approach 1:
A sacrificial layer is introduced as an intermediary material between the dielectric layer and the substrate. This sacrificial layer has different etch selectivity compared to the dielectric layer, allowing it to be selectively removed to expose the substrate in specific regions while protecting other areas. The sacrificial layer acts as a temporary mediator that enables differential etching depths without causing substrate loss, as it can be precisely controlled and removed only where needed.
Solution Approach 2:
The method utilizes etch selectivity parameters by choosing materials with different etching characteristics. The dielectric layer and sacrificial layer are selected to have different etch rates and selectivity ratios, allowing the etching process to differentiate between these layers. By adjusting etching parameters such as chemistry composition, power, and pressure, the process can selectively remove the dielectric layer down to the sacrificial layer in some regions while preserving it in others, enabling contacts of different depths without substrate damage.
2Ease of manufacture
If conventional etching methods are used for contacts with different depths, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to substrate exposure
Solution Approach 1:
The sacrificial layer serves as a protective intermediary that prevents direct exposure of the substrate during etching. By placing this intermediate layer over the substrate, the etching process can proceed with relaxed precision requirements, as the sacrificial layer absorbs the variability in etch depth. The sacrificial layer can be selectively removed afterward to expose the substrate only in regions where deeper contacts are needed, thereby maintaining both manufacturing simplicity and precision.
Solution Approach 2:
The sacrificial layer is formed in advance before the contact etching process. This preliminary action prepares the structure by creating a protective barrier that defines the maximum etch depth. By pre-positioning this layer, the subsequent etching process does not require precise depth control to avoid substrate exposure, as the sacrificial layer physically prevents over-etching. This preliminary protective measure simplifies the manufacturing process while ensuring precise etch depth control.
Data Source
AI summary
According to the embodiment of the present invention, it is possible to minimize the loss of the substrate that may be caused by the difference in etching height by taking advantage of the difference in the etch selectivity between a nitride material, an oxide material, and a conductive material, and minimizing the exposure of the substrate while each contact hole is formed. According to the embodiment of the present invention, a loss of the substrate may be minimized when contact holes having different etching depths are formed.