Semiconductor Contact Depth Control via Segmented Mask
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Solution Overview
Problem
As semiconductor devices become highly integrated, there is a need for techniques to form contacts of different heights effectively, as existing methods struggle to stably create contact openings with varying depths.
Innovation Solution
A method involving a substrate with distinct regions, where photolithography and etching processes are used to form mask openings and contact openings of different depths, with a sacrificial mask and etching processes to expose elements at varying heights, allowing for the formation of conductive contact plugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography and etching processes are used to form contact openings, then the manufacturing process is simple, but it is difficult to stably form contact openings with different depths
Solution Approach 1:
The mask layer is divided into multiple regions with different thicknesses: a first region with greater thickness and a second region with lesser thickness. This segmentation allows different etching depths to be achieved through the mask layer, enabling stable formation of contact openings with different depths while maintaining a relatively simple process flow.
Solution Approach 2:
The mask layer is designed with non-uniform local properties - different thicknesses in different regions. The first region has greater thickness to protect deeper contact openings during etching, while the second region has lesser thickness to allow formation of shallower contact openings. This local quality variation enables precise depth control without complicating the overall manufacturing process.
2Manufacturing precision
If a single-layer mask is used in photolithography, then the manufacturing process is simple, but contact openings with varying depths cannot be formed
Solution Approach 1:
The mask layer is segmented into multiple thickness regions within a single continuous layer structure. This segmentation by thickness rather than by separate layers enables depth variation in contact openings while avoiding the complexity of multiple mask layers, thus resolving the contradiction between depth control capability and structural simplicity.
Solution Approach 2:
The thickness parameter of the mask layer is varied across different regions to achieve different contact opening depths. By changing the thickness parameter locally rather than using multiple layers with different materials or properties, the invention achieves depth control with minimal increase in structural complexity.
3Manufacturing precision
If etching is performed to expose elements at different heights, then contact openings of different depths are formed, but etching damage occurs
Solution Approach 1:
The mask layer with greater thickness in the first region serves as a protective cushion during the etching process. This thicker mask region prevents etching damage to underlying elements by providing an additional barrier that protects sensitive structures from excessive etching, while still allowing the formation of deep contact openings where needed.
Solution Approach 2:
The mask layer acts as an intermediary between the etching process and the underlying elements. By designing the mask layer with varying thickness, it mediates the etching process to achieve different contact opening depths while protecting elements from damage - the thicker regions protect deeper areas, and thinner regions allow shallower access.
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 method enables the stable formation of contact openings with different depths, minimizing etching damage and improving the reliability of contact formation in semiconductor devices.
Implementation Method 1
Photolithography and etching processes are performed on the mask to form a first mask opening passing through the mask and exposing the insulating layer on the first region
Implementation Method 2
The insulating layer exposed by the first mask opening may be etched to form a preliminary contact opening on the first region
Data Source
AI summary
A method of fabricating a semiconductor device includes forming a first contact opening having a relatively larger depth than a second contact opening to expose first and second contacts through an insulation layer, where the first and second contacts are located at different depths with respect to an upper surface of the insulation layer. Therefore, it is possible to prevent excessive over-etch of the second contact opening and minimize etching damage to the contact region exposed by the second contact opening.