Cylindrical Grinding Alignment for Wafer Plane Orientation Accuracy
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Solution Overview
Problem
Existing methods fail to produce wafers with a constant generation state of waviness relative to the plane orientation due to deviations in the center axis of monocrystalline silicon from the target crystal axis, preventing accurate wafer bonding for Through Silicon Via connections.
Innovation Solution
A cylindrical grinding apparatus and method that corrects the attitude of monocrystalline silicon by rotating and turning it around specific angles to align the plane orientation with the target orientation, followed by grinding to produce wafers with consistent waviness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the monocrystal for slicing is horizontally turned to adjust the plane orientation, then the horizontal deviation is corrected, but the vertical deviation between the plane orientation and target plane orientation cannot be canceled when the displacement between center axis and target crystal axis is large
Solution Approach 1:
The invention introduces a vertical turning capability in addition to the conventional horizontal turning. The orientation adjusting mechanism can now perform rotation around the center axis and turning around a vertical turn axis, adding a new dimensional degree of freedom to correct plane orientation deviations that were previously uncorrectable through horizontal turning alone.
Solution Approach 2:
The invention changes the operational parameters of the orientation adjusting mechanism by enabling it to perform vertical turning in addition to horizontal rotation. This parameter expansion allows the mechanism to handle cases with large displacement between the center axis and target crystal axis, transforming a two-parameter adjustment system into a three-parameter system that can resolve orientation deviations in both horizontal and vertical directions.
2Ease of manufacture
If the center axis of monocrystalline silicon is displaced from the target crystal axis, then the material can be obtained from standard Czochralski production, but the plane orientation of resultant wafers deviates from the target plane orientation
Solution Approach 1:
The invention performs preliminary orientation correction during the cylindrical grinding process, before the slicing operation. By detecting the crystal axis orientation and adjusting the monocrystal for slicing's attitude in advance, the system ensures that subsequent slicing produces wafers with the correct target plane orientation, preventing orientation errors from propagating through the manufacturing process.
Solution Approach 2:
The invention implements a feedback mechanism where the crystal axis orientation is detected and measured, and this information is used to automatically adjust the orientation adjusting mechanism. The system continuously monitors the plane orientation and makes real-time corrections to ensure the final wafer orientation matches the target, closing the loop between measurement and adjustment.
3Productivity
If conventional cylindrical grinding is performed without attitude correction, then the processing is simple and fast, but wafers with constant generation state of waviness cannot be obtained when axis displacement is large
Solution Approach 1:
The attitude correction is performed as a preliminary step before the cylindrical grinding operation. The orientation adjusting mechanism pre-aligns the monocrystal for slicing with the correct attitude based on detected crystal axis orientation, ensuring that the subsequent grinding process produces consistent waviness patterns. This preliminary alignment prevents the need for rework and ensures quality output without significantly extending the overall process time.
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
The method ensures that wafers are produced with aligned plane orientations, improving wafer bonding accuracy for integrated circuits by aligning the notch and slicing start position, thereby enhancing the precision of Through Silicon Via connections.
Implementation Method 1
performing cylindrical grinding, in the cylindrical grinding an outer circumferential surface of a monocrystal for grinding being ground while the monocrystal for grinding is rotated around a rotation axis
Implementation Method 2
by performing a rotation and a turn based on a plane orientation difference between a plane orientation of the monocrystal for grinding and a target plane orientation of a wafer to be obtained by slicing the monocrystal for slicing
Implementation Method 3
in the rotation the monocrystal for grinding being rotated around the center axis, in the turn the monocrystal for grinding being turned around a turn axis orthogonal to the center axis
Implementation Method 4
a grinding section configured to cylindrically grind the outer circumferential surface of the monocrystal for grinding while rotating the monocrystal for grinding whose attitude has been corrected around the rotation axis
Data Source
AI summary
A cylindrical grinding apparatus produces a monocrystal for slicing by cylindrical grinding an outer circumferential surface of a monocrystal for grinding while rotating the monocrystal for grinding around a rotation axis. The cylindrical grinding apparatus includes: an attitude correcting section for correcting an attitude of the monocrystal for grinding to incline a center axis thereof with respect to the rotation axis, by rotating the monocrystal for grinding around the center axis and turning the monocrystal for grinding around a turn axis orthogonal to the center axis based on a plane orientation difference between a plane orientation of the monocrystal for grinding and a target plane orientation of a wafer to be obtained by slicing the monocrystal for slicing; and a grinding section for cylindrically grinding the outer circumferential surface of the monocrystal for grinding while rotating the monocrystal for grinding whose attitude has been corrected around the rotation axis.