Wire Saw Slicing Temperature Control for Nano-Topography
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Solution Overview
Problem
The existing wire saw slicing method causes significant nano-topography issues, particularly at the slicing end portion, due to rapid cooling and contraction of the ingot, leading to precipitous changes in the wafer's Warp shape and reduced yield in device manufacturing.
Innovation Solution
The slicing method involves controlling the slurry supply temperature to maintain the ingot temperature at 30°C or above near the end of slicing, reducing thermal contraction and stabilizing the slicing trajectory, thereby suppressing nano-topography by minimizing rapid cooling and its effects on the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the slurry supply temperature is not controlled (conventional method), then the slicing process is simple, but the ingot undergoes rapid cooling and contraction at the end of slicing, causing precipitous changes in Warp shape and generating nano-topography
Solution Approach 1:
The invention changes the temperature parameter of the slurry supply from constant (conventional) to variable (controlled). By controlling the slurry supply temperature to maintain the ingot temperature at 30°C or above near the end of slicing, the thermal contraction is reduced, preventing precipitous changes in slicing trajectory and Warp shape, thereby suppressing nano-topography generation.
Solution Approach 2:
The invention implements a feedback control system where the slurry supply temperature is adjusted based on the ingot temperature. The temperature control mechanism monitors the ingot temperature and adjusts the slurry supply temperature accordingly to maintain the ingot temperature at 30°C or above, creating a closed-loop control that prevents excessive thermal contraction.
2Manufacturing precision
If the slurry supply temperature is controlled to maintain ingot temperature, then nano-topography is suppressed, but the temperature control mechanism increases device complexity
Solution Approach 1:
The invention controls the temperature parameter of the slurry supply to maintain the ingot temperature at 30°C or above. This parameter change stabilizes the slicing trajectory by preventing thermal contraction, directly improving manufacturing precision while the control mechanism manages the added complexity.
3Productivity
If rapid cooling occurs at the end of slicing, then the slicing process is fast, but the ingot contracts precipitously causing Warp shape changes and reduced wafer yield
Solution Approach 1:
The invention changes the cooling rate parameter by controlling the slurry supply temperature. Instead of allowing rapid cooling, the slurry temperature is adjusted to maintain the ingot temperature at 30°C or above, reducing thermal contraction and stabilizing the Warp shape while maintaining slicing productivity.
Solution Approach 2:
The invention applies preliminary anti-action by pre-controlling the slurry supply temperature before rapid cooling can occur. The temperature control mechanism proactively maintains the ingot temperature, preventing the thermal contraction that would otherwise cause Warp shape changes and nano-topography.
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 effectively reduces nano-topography levels, improving wafer quality and yield by stabilizing the slicing trajectory and preventing excessive temperature fluctuations near the slicing end, resulting in higher-quality wafers with reduced surface waviness.
Implementation Method 1
a slurry can be supplied to the grooved rollers 3 and the wire 2
Implementation Method 2
the ingot is rapidly cooled and contracted in the time close to end of slicing
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention provides a slicing method comprising winding a wire around a plurality of grooved rollers and pressing the wire against an ingot to be sliced into wafers while supplying a slurry for slicing to the grooved rollers and causing the wire to travel, wherein a supply temperature of the slurry for slicing is controlled, and slicing is performed in such a manner that the supply temperature of the slurry for slicing and a temperature of the ingot become at least 30°C or above at end of slicing the ingot. As a result, there is provided the slicing method that can alleviate precipitous cooling of an ingot in the time close to end of slicing the ingot and thereby suppress production of a nano-topography when slicing the ingot by using a wire saw.