Halftone Exposure Mask for Resist Edge Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for forming LDD and GOLD structures in semiconductor devices using photolithography struggle with forming separate structures for each circuit due to complex manufacturing steps and the formation of convex resist shapes, leading to uneven carrier concentration in semiconductor layers.
Innovation Solution
An exposure mask with a halftone mask structure, comprising a light-transmitting substrate, a semi-transparent film, and a light-shielding film, where the phase difference and transmittance satisfy specific conditions, is used to control the resist thickness and shape, allowing for the formation of resist patterns with gentle edges and different thickness regions without convex portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a halftone mask with conventional transmittance and phase difference conditions is used, then the resist can be formed with different thickness regions, but convex portions are formed at the end portions of the resist, causing uneven carrier concentration
Solution Approach 1:
The patent changes the optical parameters of the halftone mask, specifically setting the transmittance to 5-20% and the phase difference to 50-100 degrees. This parameter optimization prevents the formation of convex portions at resist end portions while maintaining the ability to form resist with different thickness regions, thereby solving the contradiction between resist thickness uniformity and end portion shape.
2Adaptability or versatility
If separate formation processes are used for LDD structure and GOLD structure, then each circuit can have customized structures, but the manufacturing steps become complex
Solution Approach 1:
The patent segments the mask pattern into different regions (first pattern region and second pattern region) with different optical properties. The first region has higher light intensity for forming LDD structures, while the second region has lower light intensity for forming GOLD structures. This allows both structures to be formed in a single photolithography step, maintaining circuit customization while simplifying the manufacturing process.
Solution Approach 2:
The halftone mask is designed to perform multiple functions simultaneously: it forms both LDD structures and GOLD structures in a single exposure step, and can accommodate different circuit designs (n-channel, p-channel, CMOS) without requiring different masks. This multi-functionality reduces manufacturing complexity while maintaining adaptability.
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 enables the formation of transistor, capacitor, and resistor structures with different electrode shapes in a self-aligned manner, reducing manufacturing steps and improving circuit integration without increasing complexity.
Implementation Method 1
exposure light which transmits through a transparent region of the halftone mask and exposure light which transmits through a halftone film (semi-transparent region), interfere with each other
Implementation Method 2
a phase difference Δθ of exposure light which transmits through a transparent region and a semi-transparent region
Implementation Method 3
intensity of the exposure light which transmits through a boundary portion of the halftone film is decreased
Data Source
AI summary
An exposure mask provided with a semi-transparent film, capable of forming a resist in which a convex portion is not formed in an end portion and the end portion has gentle shape. In an exposure mask having a first region and a second region having different phase and transmittance with respect to exposure light, the phase difference Δθ with respect to exposure light which transmits though the first region and the second region and the transmittance n of the second region with respect to exposure light are defined so as to satisfy following formula 1.Δθ≦arccos(−√n/2) [Formula 1]Accordingly, a resist having regions with different thicknesses and having gentle shape in an edge can be formed. By performing a process such as etching with this resist, regions having different thicknesses can be formed in a self-aligned manner.