Semiconductor Wafer Peeling Using a Laser-Formed Separation Layer
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Solution Overview
Problem
Existing methods for manufacturing semiconductor wafers face challenges in improving processing quality and ease during the peeling step, leading to issues such as surface roughness and increased processing time, as well as the need for higher loads to achieve peeling, which affects manufacturing yield.
Innovation Solution
A method involving the formation of a peeling layer on the ingot surface using a laser beam, followed by applying a moment or dynamic force to concentrate stress at the edge of the ingot, allowing for controlled peeling with reduced load and improved surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional peeling methods are used, then wafers can be separated from the ingot, but surface roughness increases and processing time extends
Solution Approach 1:
The method applies preliminary action by forming a modified layer and cracks in the ingot before the peeling step. The laser beam creates a peeling surface with controlled defects that facilitate subsequent separation. This preliminary preparation reduces the force needed during peeling and minimizes surface roughness, thereby reducing griding and polishing time while improving surface quality.
Solution Approach 2:
The invention segments the peeling process into distinct stages: forming a modified layer, creating cracks, and then separating the wafer. By dividing the peeling action into controlled segments rather than applying force all at once, the method achieves cleaner separation with less surface damage and reduced processing time.
2Reliability
If higher loads are applied during peeling, then separation can be achieved, but processing ease deteriorates
Solution Approach 1:
The method applies preliminary action by forming a modified layer and cracks in the ingot before the peeling step. The laser beam creates a peeling surface with controlled defects that facilitate subsequent separation. This preliminary preparation reduces the force needed during peeling and minimizes surface roughness, thereby reducing griding and polishing time while improving surface quality.
Solution Approach 2:
The modified layer and cracks act as an intermediary structure between the wafer and the bulk ingot. This intermediate peeling surface facilitates separation by providing a predetermined path for crack propagation, reducing the direct mechanical stress needed for separation and improving processing ease.
3Productivity
If conventional peeling methods are used, then wafers can be separated, but surface quality deteriorates due to increased roughness
Solution Approach 1:
The method applies preliminary action by forming a modified layer and cracks in the ingot before the peeling step. The laser beam creates a peeling surface with controlled defects that facilitate subsequent separation. This preliminary preparation reduces the force needed during peeling and minimizes surface roughness, thereby reducing griding and polishing time while improving surface quality.
Solution Approach 2:
The invention changes the physical parameters of the ingot surface by using laser irradiation to create a modified layer with specific thermal and structural properties. This parameter change in the surface layer enables controlled crack formation and cleaner peeling, improving surface quality and manufacturing yield.
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 reduces the peeling load, enhances processing ease, and improves manufacturing yield by ensuring precise and efficient separation of wafers with minimal surface roughness.
Implementation Method 1
a laser beam is radiated to a silicon ingot with the focusing point positioned at a depth corresponding to a wafer thickness from the first surface of the ingot
Implementation Method 2
a laser beam is radiated to a silicon ingot... forming a peeling surface composed of a modified layer and cracks
Implementation Method 3
a moment force acts on the ingot where one end of the pad is the working point and the other end is the supporting point, thereby peeling the part of the ingot with the peeling surface as the boundary surface
Implementation Method 4
peeling the part of the ingot with the peeling surface as the boundary surface
Implementation Method 5
applying a dynamic force to the ingot such that a tensile stress along an ingot thickness direction acts on an entire area of the ingot in the surface direction
Data Source
Figure 1~3
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Figure 6~8
AI summary
A manufacturing method of semiconductor wafers includes preparing a ingot (20) having a first major surface (21) and a second major surface (22) in a back side of the first major surface, a peeling layer (23) being formed in the ingot along the first major surface; and applying a load to the ingot from outside thereof with respect to a surface direction along the first major surface such that a moment with a supporting point (PP) which is a first end of the ingot in the surface direction acts on the ingot, thereby peeling a wafer precursor (24) from the ingot. Also, a dynamic force may be applied to the ingot such that a tensile stress along an ingot thickness direction acts on an entire area of the ingot in the surface direction, thereby peeling the wafer precursor (24) from the ingot.