Flowable Film Gap Fill with Compressive Capping Layer
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Solution Overview
Problem
Forming crack-free semiconductor features with high aspect ratios and narrow gaps is challenging due to dielectric material clogging, leading to voids and subsequent substrate cracking, especially as semiconductor geometries continue to scale smaller.
Innovation Solution
A process involving the formation of a flowable film to fill gaps with a capping layer having compressive stress, which counteracts the tensile stress induced by curing, preventing crack formation in the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flowable dielectric material is used to fill narrow gap high aspect ratio patterns, then void formation is prevented, but tensile stress during curing causes substrate cracking
Solution Approach 1:
A capping layer with compressive stress is deposited over the flowable dielectric material before curing. This compressive stress serves as a preliminary counteraction to the tensile stress that will develop during curing, preventing substrate cracking while allowing complete gap filling to occur
Solution Approach 2:
The stress state of the dielectric system is changed by introducing a capping layer with opposite stress characteristics. The capping layer's compressive stress parameter counterbalances the tensile stress parameter that develops during curing of the flowable dielectric, resolving the contradiction between complete filling and substrate integrity
2Reliability
If the flowable film is cured before forming the dielectric film, then the stress balance is achieved, but crack prevention is ineffective
Solution Approach 1:
The capping layer with compressive stress is formed in advance, before the flowable film is cured. This preliminary action ensures that the counteracting compressive stress is already in place to prevent cracking when tensile stress develops during the subsequent curing process
3Productivity
If semiconductor geometries are scaled smaller with narrower gaps, then device density is improved, but gap filling difficulty increases due to higher aspect ratios
Solution Approach 1:
The capping layer acts as an intermediary element that enables gap filling in high aspect ratio structures. By providing compressive stress, it mediates between the need to fill narrow gaps completely and the need to prevent substrate cracking, making manufacturing of scaled-down geometries feasible
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 ensures crack-free filling of high aspect ratio structures by balancing tensile and compressive stresses, thereby preventing substrate damage and ensuring reliable semiconductor feature formation.
Implementation Method 1
The dielectric film has compressive stress in the open area in the horizontal direction
Implementation Method 2
The curing increases tensile stress of the flowable film in the open area in the horizontal direction
Implementation Method 3
The flowable film is cured after forming the dielectric film. The curing increases tensile stress of the flowable film
Implementation Method 4
a flowable CVD (Chemical Vapor Deposition) oxide may be treated with a high temperature steam anneal to convert the flowable CVD oxide to silicon oxide
Implementation Method 5
The compressive stress of the dielectric film in the horizontal direction counteracts the tensile stress of the flowable film in the horizontal direction in the open area
Data Source
AI summary
Techniques disclosed herein may achieve crack free filling of structures. A flowable film may substantially fill gaps in a structure and extend over a base in an open area adjacent to the structure. The top surface of the flowable film in the open area may slope down and may be lower than top surfaces of the structure. A capping layer having compressive stress may be formed over the flowable film. The bottom surface of the capping layer in the open area adjacent to the structure is lower than the top surfaces of the lines and may be formed on the downward slope of the flowable film. The flowable film is cured after forming the capping layer, which increases tensile stress of the flowable film. The compressive stress of the capping layer counteracts the tensile stress of the flowable film, which may prevent a crack from forming in the base.