Application of three-step epitaxial process to dual trench epitaxial diode array

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Electrical Engineering

Background:

• High-density phase change random access memory (PCRAM) requires advanced diode arrays for efficient operation.
• Arsenic auto-doping from heavily doped substrates poses a challenge in fabricating high-performance epitaxial diode arrays.
• Conventional Chemical Vapor Deposition (CVD) epitaxial processes struggle to mitigate arsenic auto-doping effectively.

Purpose of the Study:

• To report the application of a three-step epitaxial (EPI) process for dual trench epitaxial diode arrays in PCRAM.
• To investigate the suppression of vertical and lateral Arsenic auto-doping using the proposed EPI method.
• To evaluate the impact of the three-step EPI process on diode performance metrics.

Main Methods:

• Implementation of a three-step epitaxial (EPI) process, including a pre-deposition step at high temperature and low deposition rate.
• Fabrication of dual trench epitaxial diode arrays on Arsenic heavily-doped substrates.
• Characterization of the EPI layer quality, thickness uniformity, and Arsenic auto-doping levels.

Main Results:

• Achieved a high-quality single crystalline EPI layer with good thickness uniformity across a 200 mm wafer.
• Effectively suppressed both vertical and lateral Arsenic auto-doping by 2-3 orders of magnitude compared to conventional CVD EPI.
• Demonstrated a significant improvement in diode breakdown voltage (> 11 V) and On/Off current ratio (> 9 orders of magnitude).

Conclusions:

• The three-step EPI process is highly effective in suppressing Arsenic auto-doping in PCRAM diode arrays.
• This method enables the fabrication of high-performance epitaxial diodes with superior breakdown voltage and On/Off current ratios.
• The optimized EPI process is crucial for advancing high-density PCRAM technology.