Photosensitive Polymer Buffer Layer for Capacitor Etching
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Solution Overview
Problem
Conventional methods for forming buffer layer patterns in capacitors, such as those used in DRAM devices, are inefficient and costly, requiring lengthy deposition and etching processes, and can damage the lower electrode or leave residues that cause malfunction, while also necessitating high-temperature ashing that may deteriorate the electrode.
Innovation Solution
A method using a polymer with repeating units of anthracene-methyl methacrylate and alkoxyl-vinyl benzene is formed into a buffer layer pattern, which is baked to become insoluble and serve as an etching mask, then converted to a soluble form for removal without ashing, simplifying the manufacturing process and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide buffer layer is formed through deposition and etched through etch-back or CMP, then a buffer layer pattern is formed, but the process requires relatively long time for deposition and etching
Solution Approach 1:
The invention changes the material parameter from oxide to photosensitive polymer, and changes the process parameter from thermal deposition/etching to photo-lithography. The photosensitive polymer layer is formed by coating and then patterned by exposing to light and developing, which significantly reduces the process time compared to oxide deposition and etch-back
Solution Approach 2:
The invention replaces the mechanical/thermal processes (deposition and etching) with a photochemical process. The photosensitive polymer undergoes chemical change when exposed to light, allowing pattern formation through chemical development rather than mechanical removal, thus reducing process time
2Strength
If conventional photoresist is used and baked at high temperature (>270°C) to harden, then the photoresist film is hardened, but the lower electrode may be damaged during subsequent ashing and cleaning processes
Solution Approach 1:
The invention changes the thermal parameter from high temperature (>270°C) to low temperature (room temperature or mild heating). The photosensitive polymer achieves sufficient hardness and structural stability without requiring high-temperature baking, thus preventing damage to the lower electrode during subsequent processing
Solution Approach 2:
The photosensitive polymer serves as a temporary sacrificial layer that is easily removed after serving its buffering function. It provides the necessary structural support during electrode formation but can be completely removed without damaging the electrode, unlike conventional photoresist that may leave residues or require harsh removal
3Productivity
If high temperature ashing (150-250°C) is performed to remove buffer layer pattern efficiently, then removal efficiency is improved, but the lower electrode is deteriorated and/or oxidized
Solution Approach 1:
The invention changes the temperature parameter from high (150-250°C) to low (room temperature or mild conditions). The photosensitive polymer can be removed at low temperatures through photochemical degradation or simple solvent dissolution, avoiding thermal damage and oxidation to the lower electrode while maintaining removal efficiency
Solution Approach 2:
The invention replaces thermal ashing with a photochemical or solvent-based removal process. The photosensitive polymer degrades or dissolves through chemical means at low temperature rather than requiring high-temperature oxidation, thus protecting the electrode integrity and maintaining capacitor reliability
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 simplifies the manufacturing process for capacitors by reducing the need for high-cost exposure devices and ashing processes, preventing damage to the lower electrode, and ensuring effective removal of the buffer layer without compromising electric capacitance.
Implementation Method 1
A first buffer layer pattern including a polymer having a repeating unit of anthracene-methyl methacrylate and a repeating unit of alkoxyl-vinyl benzene is formed on the conductive layer in the opening. The first buffer layer pattern is then baked to cross-link the polymers thereby forming a second buffer layer pattern that is insoluble in a developing solution.
Implementation Method 2
The conductive layer on a top portion of the mold layer is selectively removed by using the second buffer layer pattern as an etching mask.
Data Source
AI summary
In a method of forming a pattern and a method of manufacturing a capacitor using the same, a conductive layer is formed on a mold layer having an opening. A first buffer layer pattern including a polymer having a repeating unit of anthracene-methyl methacrylate and a repeating unit of alkoxyl-vinyl benzene is formed on the conductive layer in the opening. The first buffer layer pattern is baked to cross-link the polymers and form a second buffer layer pattern that is insoluble in a developing solution. The conductive layer on a top portion of the mold layer is selectively removed by using the second buffer layer pattern as an etching mask. Accordingly, a conductive pattern for a semiconductor device is formed. The method of forming a pattern may simplify manufacturing processes for a capacitor and a semiconductor device, and may improve their efficiencies.