Bonded Wafer Defect Prevention via Ion Implantation Orientation
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Solution Overview
Problem
The ion implantation separation method for producing bonded wafers often results in large fault defects on the surface of thin films, such as SOI layers, due to variations in shape during the separation process, which affects the separation speed and generates defects like scratches across a wide range.
Innovation Solution
Adjusting the settings of the ion implanter and ion implantation conditions to position the cutout portion of the bond wafer within 0±30° or 180±30° from the separation start position, and optimizing ion implantation by increasing ion damage and thermal conduction at specific areas to control the separation start position, thereby avoiding the involvement of cutout portions during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the separation heat treatment is performed on wafers with cutout portions (notches) aligned during bonding, then the bonding process is simplified and alignment is easier, but large fault defects (scratch-like defects) are generated on the thin film surface due to speed changes in the separation advancement
Solution Approach 1:
The invention intentionally creates an asymmetric arrangement between the cutout portion and the separation start position. By positioning the cutout portion at a specific angular offset (30° to 150°) from the separation start position, the symmetric alignment used during bonding is deliberately broken for the separation process. This asymmetric positioning prevents the cutout portion from interfering with the separation wave propagation, thereby eliminating large fault defects while maintaining easy bonding through standard alignment procedures
Solution Approach 2:
The invention performs preliminary positioning of the cutout portion relative to the separation start position during the ion implantation setup. By pre-calculating and setting the correct angular relationship between the cutout portion and the intended separation start position before bonding and separation occur, the system ensures that when separation happens, the cutout portion is already in the correct non-interfering position. This preliminary action prevents defects without requiring complex real-time adjustments during separation
2Manufacturing precision
If the cutout portion is positioned away from the separation start position to avoid defects, then thin film quality is improved, but additional adjustment steps are required in the ion implantation process
Solution Approach 1:
The invention replaces complex mechanical positioning and alignment systems with a simplified angular offset calculation method. Instead of using complex mechanical devices to dynamically position the cutout portion during separation, the system uses a straightforward angular relationship (30° to 150° offset) that can be calculated and set during ion implantation planning. This substitution reduces mechanical complexity while maintaining high precision in preventing defect formation
Solution Approach 2:
The invention changes the critical parameter from absolute position alignment to relative angular offset. By defining the relationship between the cutout portion and separation start position in terms of a simple angular parameter (30° to 150° offset) rather than complex spatial coordinates, the system simplifies the ion implantation setup. This parameter change makes the positioning requirement easier to implement and verify while achieving the same defect-prevention goal
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 effectively inhibits the occurrence of large fault defects by intentionally setting the separation start position, ensuring the cutout portion is not involved in the separation process, and facilitates easier separation with a shorter heat treatment time.
Implementation Method 1
implanting hydrogen ions, rare gas ions, or mixed gas ions thereof into a bond wafer from a surface of the bond wafer to form a layer of the implanted ions in an interior of the bond wafer
Implementation Method 2
separating the bond wafer along the layer of the implanted ions by performing a separation heat treatment on the wafers after the bonding step by using a heat treatment furnace
Data Source
Figure 1(a)~1(f)
Figure 2~3
Figure 4~5
AI summary
The present invention provides a method of producing a bonded wafer in which wafers each having a cutout portion are used as a bond wafer and a base wafer, and either or both of settings of an ion implanter with which ions are implanted and conditions of the ion implantation are adjusted in the step of implanting the ions such that a cutout portion of either or both of the bond wafer and the base wafer after bonding is located at within a range of 0±30° or 180±30° from a position at which separation of the bond wafer begins in the step of separating the bond wafer. This method can inhibit the occurrence of large fault defect that may be generated on a surface of a thin film right after the separation, when a thin film such as an SOI layer is formed by the ion implantation separation method.