Polysilazane Isolation Structure for Low Stress
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Solution Overview
Problem
Conventional methods for forming insulating films in electronic devices often result in trench isolation structures that are prone to cracking and deformation due to stress, which can lead to substrate damage and pattern collapse.
Innovation Solution
A method involving the use of polysilazane compositions to form a siliceous film with a low shrinkage percentage and reduced stress, where a first polysilazane composition is coated, fired to create a porous film, and then impregnated with a second polysilazane composition to fill voids and enhance the film's properties, reducing tensile stress and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form oxide films in minute trench isolation structures, then the isolation structure can be formed, but the fine trench walls cannot bear the stress applied by the oxide films, causing cracks and deformation of the substrate
Solution Approach 1:
The patent changes the material parameters by using polysilazane composition instead of conventional oxide precursor, which undergoes chemical transformation during firing to form a siliceous film with different stress characteristics. This parameter change in material composition resolves the contradiction by providing a film that exerts less stress on the trench walls while maintaining isolation functionality
Solution Approach 2:
The patent employs a composite approach by using polysilazane composition containing both silicon and nitrogen elements, which transforms into a siliceous film with composite properties. This composite material structure allows the film to have reduced tensile stress while maintaining adequate insulation, thus preventing trench wall cracking while achieving isolation
2Reliability
If the oxide film is formed to provide electrical insulation, then the isolation function is achieved, but the film exerts stress that causes pattern collapse and substrate deformation
Solution Approach 1:
The patent changes the chemical composition parameters by using polysilazane (containing Si-N bonds) instead of conventional oxide precursors. During the firing process, the polysilazane transforms into a siliceous film with different physical properties, specifically reduced tensile stress, while maintaining the electrical insulation function. This parameter change resolves the contradiction between achieving insulation and preventing substrate deformation
3Ease of manufacture
If the insulating film is formed with conventional materials, then the isolation structure can be created, but the film has high stress that leads to cracks and exfoliation
Solution Approach 1:
The patent changes the material parameters by employing polysilazane composition as the precursor material. During firing, this composition transforms into a siliceous film with fundamentally different stress properties compared to conventional oxide films. The transformed film exhibits lower tensile stress and better adhesion, thus preventing cracks and exfoliation while maintaining ease of manufacture through the coating and firing process
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
The method effectively forms an isolation structure with low shrinkage and stress, preventing cracks and substrate deformation, while improving the physical strength and refractive index of the siliceous film.
Implementation Method 1
a first polysilazane composition is coated, fired to create a porous film
Implementation Method 2
the trenches on the substrate surface are filled with the composition containing oxide precursor and thereafter an insulating film is further inlaid therein
Implementation Method 3
the porous film is impregnated with a second polysilazane composition to fill voids
Data Source
Figure 1(A)~1(D)
AI summary
To provide a method for forming an isolation structure having a low shrinkage percentage and a low tensile stress. [Means for solving] A first polysilazane composition containing a porogen is cast on the surface of a substrate to form a coat, and then the coat is fired to form a porous siliceous film having a refractive index of 1.3 or less. Thereafter, the surface of the porous siliceous film is soaked with a second polysilazane composition, and then fired to form an isolation structure of a siliceous film having a refractive index of 1.4 or more.