Sapphire Ribbon Manufacturing with Segmented Heating Zones
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Solution Overview
Problem
The challenge lies in growing high-quality large sapphire ribbons using the Edge-Defined Film-Fed Growth (EFG) method, where controlling temperature distribution becomes increasingly difficult as the size of the monocrystal increases, leading to issues with crystal defects and shape consistency.
Innovation Solution
A monocrystalline ribbon manufacturing apparatus with a crucible wider than it is deep, featuring a die pair facing across a slit and four independently controlled heaters positioned around the crucible, allowing for precise temperature adjustment and distribution control, particularly at the die pair ends, to facilitate the growth of sapphire ribbons with widths of 40 cm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the width of the sapphire ribbon is increased to meet large substrate requirements, then the applicability and market value improve, but the temperature distribution control becomes more difficult leading to increased crystal defects
Solution Approach 1:
The heating system is divided into multiple independent heating zones (first heating zone, second heating zone, third heating zone, fourth heating zone) positioned at different locations around the crucible. Each zone can be independently controlled to precisely manage temperature distribution across the large-width ribbon, preventing thermal gradients that would cause crystal defects while enabling production of ribbons with width ≥40 cm.
2Length of moving object
If the ribbon width is increased to 40 cm or more for large substrate applications, then the product size requirement is met, but the quality of the monocrystal deteriorates due to difficult temperature control
Solution Approach 1:
Different regions of the heating system are assigned different functions: the first and second heating zones control temperature at the front end of the die pair, while the third and fourth heating zones control temperature at the rear end. This localized temperature control ensures uniform thermal conditions across the entire width of the large ribbon, maintaining monocrystal quality even at widths of 40 cm or more.
3Device complexity
If conventional single heating zone configuration is used, then the device complexity is low, but the ability to control temperature distribution at die pair ends is insufficient
Solution Approach 1:
The heating system is segmented into four independent heating zones positioned around the crucible, with each zone controlled by separate heating means. This segmentation enables precise independent adjustment of temperature at the front and rear ends of the die pair, achieving uniform temperature distribution across the width of large ribbons while maintaining reasonable device complexity.
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 configuration enables the production of high-quality large sapphire ribbons with fewer crystal defects and improved shape consistency, as evidenced by the ability to control the spread portion's inclination and shape, reducing manufacturing costs and time.
Implementation Method 1
A resulting melt 5 rises in the slit as far as upper surfaces of the die pair 3 by capillary phenomenon
Implementation Method 2
A raw material of a monocrystalline body filled in the crucible 1 is heated and melted by heating means 4 disposed around the outer periphery of the crucible 1
Implementation Method 3
A seed crystal 6 is brought into contact with a liquid surface of the melt 5 and being pulled upward while being annealed, whereby a monocrystalline body (ribbon) 11 is grown
Data Source
AI summary
A sapphire ribbon of the present disclosure has a width, a thickness, and a length that are orthogonal to one another, a length direction is a growth direction, and the sapphire ribbon further has two main surfaces separate from each other in a thickness direction, and the width is at least 40 cm. Further, a monocrystalline ribbon manufacturing apparatus using EFG method according to the present disclosure includes a crucible having a width greater than a depth thereof, a die pair installed in the crucible and facing each other across a slit in the depth direction, a first heater and a second heater disposed around the crucible and facing each other in the depth direction, and a third heater and a fourth heater disposed around the crucible and facing each other in the width direction.