Semiconductor Memory Device MILC Crystallization Yield
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Solution Overview
Problem
Conventional semiconductor memory devices face yield reduction and suboptimal electric properties in the channel region of memory cells due to defective crystallization during the metal-induced lateral crystallization (MILC) process, which affects the electron mobility and overall performance.
Innovation Solution
The semiconductor memory device employs a method where the channel semiconductor layer is crystallized using MILC, with a cap semiconductor layer formed before crystallization to stabilize the silicide layer and effectively getter metal atoms, ensuring high-quality crystalline silicon with improved electron mobility and reduced yield loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous silicon is crystallized by metal induced lateral crystallization (MILC), then electron mobility of the channel region is improved, but yield reduction occurs due to defective crystallization
Solution Approach 1:
A cap semiconductor layer is formed on the amorphous silicon layer before the MILC process. This preliminary action provides a template for crystallization that guides the formation of the silicide layer, ensuring uniform metal atom distribution and preventing defective crystallization during subsequent heating, thereby maintaining high yield while achieving improved electron mobility
Solution Approach 2:
The cap semiconductor layer acts as an intermediary between the amorphous silicon and the metal layer. It mediates the crystallization process by controlling metal atom diffusion and providing a structured interface that promotes uniform crystal grain formation, preventing the defective crystallization that would otherwise reduce yield
2Ease of manufacture
If the channel region is formed of polysilicon by rapid thermal annealing (RTA), then the manufacturing process is simple, but electron mobility is lower compared to crystallized silicon
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming the cap semiconductor layer, depositing the metal layer, and performing MILC heating. This segmentation allows each stage to be optimized independently, achieving high electron mobility through controlled crystallization while maintaining overall process simplicity through standardized fabrication steps
Solution Approach 2:
The crystallization method is changed from rapid thermal annealing to metal induced lateral crystallization. This parameter change in the heating process, combined with the cap layer structure, transforms the crystallization mechanism to produce larger crystal grains and higher electron mobility while keeping the process compatible with existing manufacturing capabilities
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 enhances electron mobility and suppresses yield reduction by stabilizing the crystallization process and effectively removing metal impurities, resulting in improved electric characteristics of the channel region.
Implementation Method 1
a cap semiconductor layer formed before crystallization to stabilize the silicide layer and effectively getter metal atoms
Implementation Method 2
a method in which amorphous silicon is crystallized by means of a metal induced lateral crystallization (MILC)
Data Source
AI summary
A semiconductor memory device, including: a substrate; a plurality of first conductive layers arranged in a first direction intersecting a surface of the substrate; a channel semiconductor layer extending in the first direction and including a first portion facing the plurality of the first conductive layers and a second portion further from the substrate than the first portion; a memory layer arranged between the first portion of the channel semiconductor layer and the plurality of the first conductive layers and including a memory part capable of storing data; and a first semiconductor layer connected to the second portion of the channel semiconductor layer, the first semiconductor layer including crystalline semiconductor containing a first impurity, and the channel semiconductor layer including a crystal grain having a crystal grain size larger than a thickness thereof.