Laser-Marked Silicon Wafer Flatness via Two-Stage Marking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The raised areas around laser marks on silicon wafers, formed during the polishing process, compromise the flatness of the wafer periphery, which is critical as semiconductor devices become miniaturized and integrated, requiring higher flatness standards.
Innovation Solution
A method involving two-stage laser marking with different beam diameters to create dots with specific depth and wall angles, followed by etching and polishing, ensures that no raised areas are left after processing, maintaining wafer flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single beam diameter is used for laser marking, then the marking process is simple and fast, but raised areas form around the dots after polishing, reducing wafer flatness
Solution Approach 1:
The laser marking process is segmented into two distinct steps: first forming a shallow dot with a larger beam diameter, then forming a deeper dot with a smaller beam diameter. This segmentation of the marking process prevents raised area formation during polishing while maintaining process efficiency
Solution Approach 2:
The beam diameter parameter is changed between two marking steps - using a first beam diameter for the initial shallow marking, then switching to a second, smaller beam diameter for the deeper marking. This parameter variation creates the optimal dot structure that prevents raised areas during subsequent polishing
2Manufacturing precision
If etching is performed to remove raised areas, then wafer flatness improves, but additional process steps and time are required
Solution Approach 1:
The laser marking process performs preliminary action by creating dots with specific depth profiles and wall angles before polishing. The first portion with its smaller wall angle is designed to prevent raised area formation during the subsequent polishing step, eliminating the need for etching to remove raised areas
3Measurement precision
If the laser beam diameter is reduced for precise marking, then dot precision improves, but the marking process takes longer due to multiple steps
Solution Approach 1:
The marking process is divided into two segments with different beam diameters, where the first segment uses a larger beam for faster initial marking and the second segment uses a smaller beam for precise deep marking. This segmentation achieves both speed and precision requirements
Solution Approach 2:
Different beam diameters are applied to different depth zones of the dot - a larger beam diameter for the upper portion and a smaller beam diameter for the deeper portion. This local quality approach optimizes both marking speed and precision for different regions of the same dot
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 prevents the formation of raised areas around laser marks, resulting in a laser-marked silicon wafer with enhanced peripheral flatness and mirror-polished surfaces, meeting stringent quality standards.
Implementation Method 1
a laser mark printing step of printing a laser mark having a plurality of dots on a silicon wafer... each of the plurality of dots is formed by a first step of irradiating a predetermined position on a periphery of the silicon wafer with laser light
Implementation Method 2
an etching step of performing etching on at least a laser-mark printed region in a surface of the silicon wafer... etching to remove the above raised area
Implementation Method 3
a polishing step of performing polishing on both surfaces of the silicon wafer... polishing on the surface of the silicon wafer
Data Source
AI summary
A method of producing a silicon wafer includes: a laser mark printing step of printing a laser mark having a plurality of dots on a silicon wafer; an etching step of performing etching on at least a laser-mark printed region in a surface of the silicon wafer; and a polishing step of performing polishing on both surfaces of the silicon wafer having been subjected to the etching step. In the laser mark printing step, each of the plurality of dots is formed by a first step of irradiating a predetermined position on a periphery of the silicon wafer with laser light of a first beam diameter thereby forming a first portion of the dot and a second step of irradiating the predetermined position with laser light of a second beam diameter that is smaller than the first beam diameter thereby forming a second portion of the dot.