Double-Sided Spalling for Dual Wafer Production
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Solution Overview
Problem
The high cost and time-consuming process of forming single-crystal semiconductor-containing structures, particularly those using III-V or II-VI compound semiconductors, limit the throughput and cost-effectiveness of semiconductor device manufacturing, as each base substrate typically yields only one device wafer.
Innovation Solution
A method is developed to form two device wafers from a single base substrate by spalling device layers from both the topmost and bottommost surfaces, allowing for concurrent production of two wafers and doubling growth throughput, with optional metal-containing adhesion layers, stressor layers, and handle substrates aiding in the spalling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional epitaxial growth methods are used on a base substrate, then high-quality single-crystal semiconductor layers are formed, but only one device wafer is produced per substrate, limiting throughput
Solution Approach 1:
The base substrate is segmented into two separate device wafers through controlled spalling. Device layers are grown on both the top and bottom surfaces of the base substrate, then the substrate is spalled at a predetermined depth to separate the two device wafers, each containing its own device layers. This segmentation doubles the productivity without significantly increasing process complexity.
Solution Approach 2:
The patent utilizes the third dimension (depth) by growing device layers on both the top and bottom surfaces of the base substrate simultaneously. This bidirectional growth approach transforms a single-sided process into a dual-sided process, effectively doubling the output per substrate while maintaining the same epitaxial growth equipment and procedures.
2Productivity
If multiple device layers are formed on both sides of the base substrate prior to spalling, then two device wafers can be produced from one substrate, but the process complexity and control difficulty increase
Solution Approach 1:
Device layers are grown on both surfaces of the base substrate before the spalling operation. This preliminary action of pre-growing layers on both sides allows the substrate to be processed once, producing two complete device wafers with fully formed device layers, rather than requiring separate growth processes for each wafer.
Solution Approach 2:
The base substrate serves as an intermediary carrier that temporarily holds device layers on both its top and bottom surfaces. This intermediary structure enables simultaneous processing of two device stacks, and the controlled spalling process cleanly separates the device layers from the substrate while maintaining the integrity of both device wafers.
3Productivity
If the base substrate is spalled to separate device layers, then two device wafers are produced concurrently, but precise control of the spalling depth is required to maintain manufacturing precision
Solution Approach 1:
The spalling process utilizes controlled changes in physical parameters such as temperature, stress, or chemical composition to achieve precise depth control. By adjusting these parameters, the spalling occurs at a predetermined depth that cleanly separates the device layers from the base substrate while maintaining the integrity and precision of both resulting device wafers.
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 significantly reduces production costs and increases throughput by enabling the simultaneous creation of two device wafers from a single substrate, enhancing the efficiency of semiconductor device manufacturing.
Implementation Method 1
The structure including the device layers is spalled within a region of the base substrate. The spalling provides a first device wafer including a portion of the base substrate and one of the device layers, and a second device wafer including another portion of the base substrate and the other of the device layer.
Data Source
AI summary
The present disclosure provides a method for forming two device wafers starting from a single base substrate. The method includes first providing a structure which includes a base substrate with device layers located on, or within, a topmost surface and a bottommost surface of the base substrate. The base substrate may have double side polished surfaces. The structure including the device layers is spalled in a region within the base substrate that is between the device layers. The spalling provides a first device wafer including a portion of the base substrate and one of the device layers, and a second device wafer including another portion of the base substrate and the other of the device layer.