Semiconductor Contact Structure Using Sacrificial Layer Etching
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Solution Overview
Problem
As semiconductor devices become highly integrated, the reduced size and increased density of contact holes pose challenges for the photolithography process, limiting the process margin and yield rate due to the difficulty in forming contact holes between closely spaced device regions.
Innovation Solution
A method involving the formation of line patterns and molding patterns on a semiconductor substrate, where sacrificial layers are etched using these patterns as masks to create contact holes, allowing for the formation of contact patterns without the need for high-resolution photolithography, thereby overcoming the limitations of the photolithography process and ensuring a sufficient process margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form contact holes, then contact holes can be formed with existing process, but process margin is reduced and yield rate is limited due to small interval between contact holes
Solution Approach 1:
A sacrificial layer is introduced as an intermediary material between the gate electrode and the contact hole formation process. This sacrificial layer serves as a temporary structure that defines the contact hole position and shape, allowing contact holes to be formed without direct photolithography patterning at the critical dimension. The sacrificial layer acts as a mediator that decouples the contact hole formation from the photolithography resolution limit.
Solution Approach 2:
The sacrificial layer is formed in advance before contact hole formation, and its thickness is controlled to predetermined ranges. This preliminary action establishes the contact hole dimensions and spacing before the actual contact hole etching process, ensuring sufficient process margin without requiring high-resolution photolithography for the final contact hole patterning.
2Productivity
If contact hole size and interval are reduced to increase integration density, then integration density is improved, but photolithography process becomes difficult to perform
Solution Approach 1:
The sacrificial layer serves as an intermediary that enables contact hole formation at reduced dimensions without requiring proportionally reduced photolithography capabilities. By forming the sacrificial layer with controlled thickness and using it as an etch stop and pattern definition layer, the method allows contact holes to be formed at smaller sizes and closer intervals than would be achievable with direct photolithography patterning alone.
Solution Approach 2:
The method changes the critical parameter from photolithography resolution to sacrificial layer thickness control. By shifting the dimensional control from the photolithography process to the sacrificial layer formation process (where thickness can be more precisely controlled), the method enables smaller contact hole sizes and tighter spacing that would be difficult to achieve with photolithography alone.
3Ease of manufacture
If photoresist pattern is used as etching mask for contact hole formation, then contact holes can be formed between gate electrodes, but process margin is reduced when contact holes are formed in different device formation regions
Solution Approach 1:
The sacrificial layer acts as an intermediary etch stop layer that provides a reliable stopping point during contact hole etching. This intermediary layer ensures that contact holes are formed to the correct depth and that the etching process can be precisely controlled across different device regions, maintaining consistent process margin regardless of the specific location or orientation of the contact holes.
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 formation of contact structures with sufficient process margin and improved contact resistance characteristics, enhancing the yield rate and integration density of semiconductor devices without relying on high-resolution photolithography.
Implementation Method 1
etching the sacrificial patterns using the molding pattern and the gate pattern as an etching mask thereby forming contact holes
Data Source
AI summary
A method of forming a contact structure includes forming an isolation region defining active regions in a semiconductor substrate. Gate patterns extending to the isolation region while crossing the active regions are formed. A sacrificial layer is formed on the semiconductor substrate having the gate patterns. Sacrificial patterns remaining on the active regions are formed by patterning the sacrificial layer. Molding patterns are formed on the isolation region. Contact holes exposing the active regions at both sides of the gate patterns are formed by etching the sacrificial patterns using the molding patterns and the gate patterns as an etching mask. Contact patterns respectively filling the contact holes are formed. The disclosed method of forming a contact structure may be used in fabricating a semiconductor device.