Thinned Wafer Groove Frame Anisotropic Etching
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Solution Overview
Problem
Current wafer thinning methods, such as full and partial grinding, face challenges like viscosity loss of temporary bonding layers at high temperatures and increased costs due to equipment requirements and warpage issues, which hinder efficient processing and transportation of thinned wafers.
Innovation Solution
An anisotropy etching process is employed to create grooves and reinforcing walls on the wafer's second surface, connecting them with the side surface, allowing for thinning without special equipment and providing a stable supporting structure for further processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If full grinding method is used to thin the wafer, then the wafer thickness is reduced, but the temporary bonding layer loses viscosity at high temperatures exceeding 260 degrees centigrade, causing the wafer to become unfixed and unable to be transported to the next process
Solution Approach 1:
The patent removes the temporary bonding layer from the system by using a self-supporting thinning method. The wafer is thinned while being supported by its own structure (frame structure formed during thinning) rather than relying on an external bonding layer that fails at high temperatures. This extraction of the problematic bonding layer resolves the contradiction between achieving thinness and maintaining bonding reliability at high temperatures.
Solution Approach 2:
The wafer supports itself during the thinning process through the formation of a frame structure that provides mechanical support. Instead of relying on an external temporary bonding layer, the wafer's own structural features (the frame formed by selective removal of material) provide the necessary support, enabling the wafer to maintain integrity and be transported without external assistance that fails at high temperatures.
2Ease of manufacture
If partial grinding method is used to thin the wafer, then the fabricating cost is reduced by avoiding temporary bonding layers, but warpage of the thinned wafer easily occurs and special equipment is needed
Solution Approach 1:
The patent applies segmentation by creating a frame structure through selective removal of material in specific regions of the wafer. This segmented approach removes material in a controlled pattern rather than uniformly, allowing the remaining structural elements to support the wafer and prevent warpage. The segmented removal pattern creates internal support structures that maintain wafer flatness while reducing overall material thickness.
Solution Approach 2:
The patent implements local quality by applying different treatments to different regions of the wafer. The frame structure is formed by selectively removing material from specific areas while leaving other areas intact. This localized approach creates regions of varying thickness and structural properties that work together to prevent warpage while achieving the desired thinness, avoiding the need for special equipment.
3Ease of manufacture
If partial grinding method is used to thin the wafer, then the fabricating cost is reduced, but special equipment is needed to perform the partial grinding
Solution Approach 1:
The patent achieves universality by developing a thinning method that can be performed using standard semiconductor processing equipment rather than requiring specialized partial grinding equipment. The frame structure formation and self-supporting thinning approach are compatible with conventional process tools, making the method universally applicable to existing fabrication lines without requiring additional specialized equipment investments.
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 method enables wafer thinning without warpage and special equipment, providing an effective supporting structure for subsequent processes like ion implantation and back electrode formation, reducing fabrication costs and improving efficiency.
Implementation Method 1
an anisotropy etching process is performed to the second surface with a mask to remove portions of the wafer while remaining the side surface thereby forming a number of grooves in the second surface and at least one reinforcing wall between the grooves
Data Source
AI summary
A thinning method of a wafer is provided. The method includes the following steps. First, a wafer having a first surface, a second surface, and a side surface is provided, and the side surface is connected between the first surface and the second surface. At least one semiconductor device is formed on the first surface. Then, an anisotropy etching process is performed to the second surface with a mask to remove portions of the wafer while remaining the side surface thereby forming a number of grooves in the second surface and at least one reinforcing wall between the grooves. As a result, a thinned wafer is obtained.