Multiple Spacer Structure for DRAM Lightly Doped Region Control
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Solution Overview
Problem
The challenge of shrinking the memory cell area in DRAM devices, particularly in the peripheral region, complicates manufacturing processes due to the difficulty in reducing the size of spacers and forming properly dimensioned lightly doped regions.
Innovation Solution
A semiconductor device with multiple spacers formed through multiple cycles of depositing and patterning dielectric layers, allowing for precise control of spacer dimensions and the formation of lightly doped regions with varying profiles, ensuring proper formation of heavily doped regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the memory cell area is shrunk to achieve miniaturization, then the device density is improved, but the manufacturing precision deteriorates due to difficulty in reducing spacer dimensions and forming properly dimensioned lightly doped regions
Solution Approach 1:
The spacer formation process is segmented into multiple sequential steps with different dielectric materials. First spacers are formed using a first dielectric material, then second spacers are formed using a second dielectric material. This segmentation allows each spacer type to be optimized independently for specific dimensional requirements, enabling precise control of overall spacer dimensions while maintaining miniaturization benefits.
Solution Approach 2:
Different regions of the spacer structure are assigned different materials with different properties. The first dielectric material is used in regions requiring one set of dimensional characteristics, while the second dielectric material is used in regions requiring different dimensional characteristics. This local differentiation enables precise control of lightly doped region dimensions while achieving overall device miniaturization.
2Device complexity
If single spacer structure is used to simplify manufacturing, then the device complexity is reduced, but the manufacturing precision deteriorates due to inability to form lightly doped regions with varying profiles
Solution Approach 1:
The spacer structure is divided into multiple segments (first spacers and second spacers) formed by separate dielectric layers. Each segment can be independently patterned and dimensioned, enabling the formation of lightly doped regions with varying profiles. This segmentation maintains manufacturing simplicity by using standard multi-layer dielectric processes while achieving complex doping profiles through the cumulative effect of multiple spacer segments.
3Manufacturing precision
If multiple cycles of depositing and patterning dielectric layers are performed to reduce spacer dimensions, then the manufacturing precision is improved, but the productivity deteriorates due to increased process cycles
Solution Approach 1:
The formation of first spacers and second spacers is merged into an integrated process flow where dielectric layers are deposited and patterned in sequence. The process combines multiple functions (forming different spacer types, defining different region boundaries, creating varying doping profiles) into a unified multi-cycle process that achieves high precision while minimizing redundant steps.
Solution Approach 2:
Dielectric layers are deposited and patterned in advance to define spacer regions before doping operations. The first and second dielectric layers are prepared beforehand to establish precise boundaries for lightly doped regions, ensuring that subsequent doping processes can be performed with accurate dimensional control without requiring additional precision-critical steps.
Data Source
AI summary
A semiconductor device and a method for preparing the same are provided. The semiconductor device includes a substrate, a gate electrode, a first spacer, and a second spacer. The gate electrode is disposed on the substrate. The first spacer is disposed on a sidewall of the gate electrode. The second spacer covers the first spacer. The first spacer includes dopants.