Silicon Crystal Growth Control via Multi-Heater Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing silicon single crystals using the CZ method face challenges in controlling the temperature gradient, solid-liquid interface height, and oxygen concentration, leading to defects such as voids and dislocation clusters, which degrade device performance and are difficult to produce defect-free crystals stably across a wide range of pulling speeds.
Innovation Solution
The method involves adjusting the pulling speed of the silicon single crystal, the rotation speed of the crucible, and the output ratio of a multi-heater to control the temperature gradient and oxygen concentration, while using a cylindrical cooler and heat shield to manage the solid-liquid interface height, ensuring a defect-free silicon single crystal with controlled oxygen concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pulling speed is increased to improve productivity, then the manufacturing efficiency improves, but crystal defects such as voids and dislocation clusters occur more frequently
Solution Approach 1:
The patent applies parameter changes by adjusting the rotation speed of the crucible and crystal, the pulling speed, and the heater output ratio to optimize the temperature gradient and solid-liquid interface height. Specifically, setting the crucible rotation speed to 0.5-2 rpm and crystal rotation speed to 15-25 rpm, combined with controlled pulling speeds, prevents defect formation while maintaining high productivity.
Solution Approach 2:
The patent employs dynamics by making the rotation speeds of the crucible and crystal adjustable and independent of each other. This dynamic control allows the system to adapt to different pulling speeds and maintain optimal conditions for defect-free crystal growth throughout the manufacturing process.
2Ease of manufacture
If the temperature gradient and solid-liquid interface height are not controlled properly, then the manufacturing process is simpler, but crystal defects occur and oxygen concentration cannot be controlled
Solution Approach 1:
The patent implements feedback control by monitoring the solid-liquid interface height and temperature gradient, and adjusting the heater output ratio and rotation speeds accordingly. The multi-heater configuration with independent power control provides feedback mechanisms to maintain optimal growth conditions and prevent defects.
Solution Approach 2:
The patent applies segmentation by dividing the heating system into multiple heaters (typically three heaters arranged vertically) that can be independently controlled. This segmentation allows precise control of the temperature gradient along the crystal axis, enabling better management of the solid-liquid interface and oxygen concentration.
3Device complexity
If a single heater is used, then the device complexity is lower, but the ability to control temperature gradient and oxygen concentration is insufficient
Solution Approach 1:
The heating system is segmented into multiple independent heaters arranged vertically around the crucible. Each heater can be controlled independently to create the desired temperature gradient profile, which is essential for controlling the solid-liquid interface shape and oxygen distribution in the crystal.
Solution Approach 2:
The multi-heater configuration enables local quality control by allowing different sections of the crystal growth zone to have different temperature gradients. This is achieved by independently adjusting the power output of each heater, creating optimized local conditions for defect-free growth and controlled oxygen concentration.
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 allows for the stable and rapid production of defect-free silicon single crystals with controlled oxygen concentration, enabling higher pulling speeds and a wider range of defect-free manufacturing conditions, thereby improving device performance and efficiency.
Implementation Method 1
the raw material is heated and melted by a cylindrical heater 105 provided surrounding the crucible 108 to produce molten silicon 103
Implementation Method 2
disposing a cylindrical cooler around a silicon single crystal
Implementation Method 3
the seed holder 109 is pulled upward while the seed holder 109 and the crucible 108 are rotated in the same or opposite directions from each other to let a silicon single crystal 107 grow
Data Source
AI summary
A method for controlling the temperature gradient on the side surface of a silicon single crystal, the height of a solid-liquid interface, and the oxygen concentration in the longitudinal direction of the silicon single crystal is provided in order to manufacture a defect-free silicon single crystal whose oxygen concentration is controlled to a predetermined value rapidly and stably. By disposing a cylindrical cooler around the silicon single crystal, and adjusting the pulling speed of the silicon single crystal, the rotation speed of a crucible that stores molten silicon and the rotation speed of the silicon single crystal, and the output ratio of a multi-heater separated into at least two in the longitudinal direction of the silicon single crystal disposed around the crucible, the temperature gradient on the side surface, the height of the solid-liquid interface, and the oxygen concentration in the longitudinal direction of the silicon single crystal are controlled.