Temporary Bonded Support Substrate for Uniform Wafer Thinning
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Solution Overview
Problem
The challenge in substrate thinning processes is achieving uniform thickness and flatness, particularly when reducing substrates to extremely low thicknesses, as non-uniform supporting members result in uneven thinning, which is critical for applications like surface acoustic wave technologies.
Innovation Solution
A temporary bonding process using a support substrate with a bonding layer having ultra-low total thickness variation (TTV) provides an even baseline for the substrate during grinding and polishing, ensuring uniform thickness reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a supporting member is used to enable handling of the substrate during thinning, then the substrate can be processed to very small thickness, but the supporting member may introduce thickness variation that results in uneven substrate thinning
Solution Approach 1:
The supporting member is pre-thinned and pre-polished to achieve uniform thickness and flatness before the substrate is bonded to it. This preliminary preparation ensures that the supporting member provides an even baseline during the subsequent substrate thinning process, preventing thickness variation from being introduced.
Solution Approach 2:
A bonding layer is introduced as an intermediary between the supporting member and the substrate. This bonding layer compensates for any minor surface irregularities and ensures uniform contact, thereby maintaining thickness uniformity during the thinning process while allowing the supporting member to provide mechanical support.
2Manufacturing precision
If the substrate is thinned to extremely low thickness (one micron or less), then the upper frequency limits of SAW filters are increased, but the substrate becomes more susceptible to damage and requires a supporting member
Solution Approach 1:
The supporting member is prepared in advance with precise thickness and flatness control through thining and polishing operations. This preliminary action ensures that when the substrate is bonded to it, the combined structure provides both the mechanical strength needed for handling and the precision required for achieving extremely thin final substrate thickness.
Solution Approach 2:
The supporting member provides localized mechanical support where needed during the thinning process, while allowing the substrate to achieve its final extreme thinness in the functional areas. The support is applied selectively during processing rather than being a permanent feature of the final device.
Data Source
AI summary
An article including a support unit, the support unit including a support substrate and a bonding layer such that the bonding layer is bonded to a surface of the support substrate. Furthermore, a total thickness variation TTV across a width of the support unit is about 2.0 microns or less.