Mixed Wafer Exposure for Large Interposers Without Reticle Stitching
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Solution Overview
Problem
The existing process of fabricating microelectronic devices with large composite base dies requires multiple passes of the wafer through a stepper apparatus, which is time-consuming and expensive due to the need for reticle stitching, as the stepper apparatus's reticle is often smaller than the die size, and using multiple stepper apparatuses is impractical due to their high cost.
Innovation Solution
The use of both a stepper apparatus and an aligner apparatus to perform exposure operations on active and inactive regions of the wafer respectively, eliminating the need for reticle stitching by allowing the stepper to focus on fine-pitch active regions and the aligner to handle larger inactive regions in a single operation, thereby reducing the number of passes and equipment needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single stepper apparatus is used to expose large composite base dies, then manufacturing precision can be maintained, but processing time increases and productivity decreases due to multiple passes and reticle stitching
Solution Approach 1:
The patent divides the exposure task into two segments: the stepper apparatus handles active regions requiring fine pitch and high precision, while the aligner apparatus handles inactive regions with coarser pitch requirements. This segmentation allows each apparatus to operate optimally within its capability range, eliminating the need for multiple stepper passes and reticle stitching, thereby maintaining precision while significantly improving productivity
Solution Approach 2:
The patent applies partial action by having the stepper apparatus perform only the necessary high-precision exposure on active regions rather than processing the entire large composite base die. The aligner apparatus handles the remaining inactive regions, avoiding excessive use of the expensive and time-consuming stepper apparatus for areas that don't require its full capability
2Productivity
If multiple stepper apparatuses are used to process large composite base dies, then processing time can be reduced, but manufacturing cost increases significantly
Solution Approach 1:
The patent makes the aligner apparatus perform multiple functions: it handles inactive regions exposure and also provides alignment features for the stepper apparatus. This multi-functionality eliminates the need for additional expensive stepper apparatuses while maintaining high productivity, as the aligner is significantly cheaper than the stepper yet can handle the coarse-pitch inactive regions effectively
Solution Approach 2:
The patent replaces the use of expensive stepper apparatuses (which would be needed if multiple were used to reduce processing time) with a single, much cheaper aligner apparatus for handling inactive regions. The aligner, being significantly less costly than the stepper, provides a cost-effective solution that maintains productivity without requiring multiple high-cost devices
3Manufacturing precision
If the reticle size is reduced to match the stepper apparatus capability, then exposure precision is maintained, but the number of passes increases and processing time increases
Solution Approach 1:
The patent applies local quality by matching the apparatus capability to the regional requirements: the stepper apparatus with its smaller reticle handles active regions where high precision is critical, while the aligner apparatus handles inactive regions where coarser precision is acceptable. This local matching eliminates the need for multiple passes across the entire die, reducing processing time while maintaining precision where it matters most
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 significantly reduces processing time and costs by allowing simultaneous exposure of multiple active regions with the stepper and inactive regions with the aligner, enhancing the efficiency and cost-effectiveness of microelectronic device fabrication without the need for reticle stitching.
Implementation Method 1
A stepper apparatus may be used to expose the multiple mask sets, layer by layer
Implementation Method 2
an aligner apparatus to perform a second exposure operation on the wafer
Data Source
AI summary
Techniques and arrangements for performing exposure operations on a wafer utilizing both a stepper apparatus and an aligner apparatus. The exposure operations are performed with respect to large composite base dies, e.g., interposers, defined within the wafer, where the interposers will become a part of microelectronic devices by coupling with active dies or microchips. The composite base dies may be coupled to the active dies via “native interconnects” utilizing direct bonding techniques. The stepper apparatus may be used to perform exposure operations on active regions of the composite base dies to provide a fine pitch for the native interconnects, while the aligner apparatus may be used to perform exposure operations on inactive regions of the composite base dies to provide a coarse pitch for interfaces with passive regions of the composite base dies.