Spin-Coated Photosensitive Film Thickness Control for Semiconductor Steps
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Solution Overview
Problem
In semiconductor device manufacturing, the film thickness of coated films formed on semiconductor substrates is non-uniform due to the high fluidity of materials, leading to difficulties in achieving uniform heights during processing, particularly in regions with step parts.
Innovation Solution
A manufacturing method involving spin coating of photosensitive materials to form first and second pattern parts on the substrate, which are then sagged to control the fluidity of subsequent coating films, ensuring uniform film thickness and height across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a material with high fluidity is spin-coated on the semiconductor substrate to cover step parts, then the coating process is simple and efficient, but the film thickness becomes non-uniform with the central part being thicker than the outer peripheral part
Solution Approach 1:
The patent applies a first coating film before the second coating film to preliminarily address the thickness non-uniformity. This first coating film is specifically designed to be thicker at the outer peripheral part than at the central part, compensating for the expected thickness distribution of the subsequent second coating film. By performing this preliminary action, the patent ensures that the final multilayer coating achieves uniform overall thickness without requiring complex coating process adjustments.
Solution Approach 2:
The patent creates local quality differences by making the first coating film have different thickness characteristics in different regions of the substrate. Specifically, the first coating film is formed to be thicker at the outer peripheral part and thinner at the central part, which is the opposite of the natural spin-coating thickness distribution. This local quality variation in the first coating film compensates for the thickness non-uniformity that will occur in the second coating film, achieving uniform total thickness.
2Manufacturing precision
If the coated film is processed by etch back to achieve uniform height, then the film height can be uniformized, but the non-uniform initial thickness makes it difficult to obtain uniform results
Solution Approach 1:
The patent performs the preliminary action of forming the first coating film with compensated thickness distribution before applying the second coating film. This preliminary structure preparation ensures that when the second coating film is added, the combined thickness is uniform across the substrate. As a result, subsequent etch back processing becomes straightforward and achieves uniform film height more easily, reducing processing difficulty.
Solution Approach 2:
The patent changes the thickness parameter of the first coating film in different regions of the substrate. By controlling the first coating film to have different thicknesses at the central and outer peripheral parts, the patent creates a thickness profile that compensates for the second coating film's natural thickness distribution. This parameter change approach simplifies the etch back process and ensures uniform final film height.
3Reliability
If dummy electrodes and polysilicon films are formed as step parts to suppress antireflective film disappearance, then the antireflective film stability is improved, but the device structure becomes more complex
Solution Approach 1:
The patent extracts the function of preventing coating film disappearance from the structural elements (dummy electrodes and polysilicon films) and transfers it to the coating process design itself. Instead of relying on additional structural components to prevent antireflective film disappearance, the patent uses a multilayer coating approach where the first coating film's thickness distribution compensates for fluidity-related issues, eliminating the need for dummy structures.
Solution Approach 2:
The patent changes the approach from modifying structural parameters (adding dummy electrodes) to modifying coating parameters (first coating film thickness distribution). By controlling the thickness parameter of the first coating film to be thicker at the outer peripheral part, the patent prevents coating material disappearance without increasing structural complexity, thus improving reliability while maintaining simple device structure.
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 achieves a uniform film height and improved flatness of the semiconductor device surface, reducing variations in film thickness and enabling efficient etch back processes without increasing manufacturing costs.
Implementation Method 1
a first coating film made of photosensitive material having fluidity is formed by spin coating so as to cover a plurality of step parts
Implementation Method 2
the first pattern part and the second pattern part are sagged by heating
Implementation Method 3
the first pattern part and the second pattern part are sagged by heating
Data Source
AI summary
An object of the present invention is to provide a semiconductor device including a film to be processed having a uniform height. A first coating film made of photosensitive material is formed so as to cover step parts and to become thicker in a central part of a semiconductor substrate in planar view and to become thinner in an outer peripheral part. Next, a first pattern part located on the central part side relative to the step parts and a second pattern part located on the outer peripheral part side relative to the step parts are formed. The first pattern part and the second pattern part are formed so that the occupied area of the first pattern part in planar view becomes smaller than that of the second pattern part in planar view. Next, the first pattern part and the second pattern part are sagged by heating. Next, a second coating film is formed by spin coating so as to cover the step parts.