Reusable Semiconductor Support Substrate with Etch Channels
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Solution Overview
Problem
The existing bonded assembly fabrication process for semiconductor devices consumes the thinned or removed substrate, leading to higher manufacturing costs due to the loss of valuable material, which is not recycled.
Innovation Solution
A reusable support substrate with a plurality of channels on its front side and a sacrificial cover layer is used, allowing for the separation from the bonded assembly through an isotropic etch process, enabling the reuse of the substrate and reducing material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate is thinned or removed after formation of semiconductor devices, then the thickness of the bonded assembly is reduced to facilitate dicing and packaging, but the substrate material is consumed and not recycled, leading to higher manufacturing costs
Solution Approach 1:
The substrate is segmented into a reusable support substrate and a removable sacrificial cover layer. The support substrate retains the channels and provides structural support, while the sacrificial cover layer is removed after bonding, achieving thickness reduction without consuming the entire substrate.
Solution Approach 2:
The sacrificial cover layer is designed to be discarded after serving its protective function during bonding, while the support substrate is recovered and reused for subsequent bonding operations. This selective discarding and recovering resolves the contradiction by eliminating material loss of the valuable support substrate.
2Ease of repair
If a sacrificial cover layer is deposited over the channels to enable substrate separation, then the support substrate can be reused, but additional manufacturing steps and materials are required
Solution Approach 1:
The sacrificial cover layer is extracted as a separate, removable component that can be selectively removed after bonding. This extraction enables the support substrate to be reused while the added complexity is confined to a single removable layer that simplifies the overall separation process.
Solution Approach 2:
The sacrificial cover layer acts as an intermediary between the support substrate and the bonded assembly during the bonding process. It provides a temporary protective function that facilitates bonding, then is easily removed to enable substrate reuse, with its complexity offset by the significant benefit of substrate reusability.
3Ease of manufacture
If channels are formed on the support substrate to enable isotropic etch access, then the sacrificial cover layer can be removed to separate the substrate, but the channel formation adds to the device structure complexity
Solution Approach 1:
The channels are formed in advance on the support substrate before bonding operations. This preliminary action enables subsequent easy removal of the sacrificial cover layer through isotropic etching, as the channels provide pre-established access paths for the etchant to reach and remove the sacrificial material.
Solution Approach 2:
The channel structure creates a porous or networked pathway system within the support substrate. This porous structure allows isotropic etchant to efficiently penetrate and remove the sacrificial cover layer through the channels, enabling easy substrate separation while the channel geometry can be optimized to minimize overall structural complexity.
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 allows for the recycling of the support substrate and device substrate, significantly reducing manufacturing costs by enabling multiple uses of the substrate and minimizing material loss during the semiconductor device assembly process.
Implementation Method 1
removing the cover layer employing an isotropic etch process by propagating an isotropic etchant through the cavities
Implementation Method 2
forming a cover layer by anisotropically depositing a sacrificial cover material over the plurality of channels
Implementation Method 3
conformally depositing an encapsulation layer on a top surface of the cover layer and on a backside surface of the support substrate
Data Source
AI summary
A support substrate including a plurality of channels on a front side is provided. A cover layer is formed by anisotropically depositing a sacrificial cover material over the plurality of channels. Cavities laterally extend within the plurality of channels underneath a horizontally extending portion of the cover layer. An encapsulation layer is conformally deposited. First semiconductor devices, first metal interconnect structures, and first bonding pads are formed over a top surface of the encapsulation layer. A device substrate with second bonding pads is provided. The second bonding pads are bonded with the first bonding pads to form a bonded assembly. Peripheral portions of the encapsulation layer are removes and peripheral portions of the cover layer are physically exposed. The cover layer is removed employing an isotropic etch process by propagating an isotropic etchant through the cavities to separate the support substrate from the bonded assembly.