Polycrystalline Diamond Substrate Grain Structure for Warpage Control
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Solution Overview
Problem
The manufacturing of polycrystalline diamond substrates for semiconductor devices is hindered by warpage issues, which lead to poor adhesion and reduced bonding strength when the warpage curvature is less than or equal to 1 m, and existing methods to mitigate warpage are costly and time-consuming.
Innovation Solution
A method involving the formation of a polycrystalline diamond substrate with a first and second layer, where the intermediate surface has a smaller average grain diameter than the principal surfaces, and the layers are grown under similar conditions to offset stress, thereby reducing warpage without extensive polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single crystal substrate is used, then high thermal conductivity and electrical insulation are achieved, but substrate cost increases and wafer size is limited to 6 inches or less
Solution Approach 1:
The patent employs a composite structure consisting of a polycrystalline diamond layer deposited on a cubic synthetic diamond substrate. This composite approach combines the high thermal conductivity of crystalline diamond with the cost-effectiveness and large-size capability of polycrystalline diamond, resolving the contradiction between thermal performance and manufacturing cost.
Solution Approach 2:
The substrate system is segmented into two functional layers: a cubic synthetic diamond substrate providing mechanical support and thermal conduction, and a polycrystalline diamond layer providing the semiconductor device growth medium. This segmentation allows each layer to optimize its specific function while overcoming the limitations of using a single crystal for the entire substrate.
2Temperature
If a single crystal substrate is used, then high thermal conductivity is achieved, but wafer size is limited to 6 inches or less
Solution Approach 1:
The composite structure allows the use of large-area polycrystalline diamond substrates (100mm or larger) while maintaining effective thermal conductivity through the underlying cubic synthetic diamond layer, thus achieving both large wafer size and high thermal conductivity.
Solution Approach 2:
The thermal management function is separated from the device growth function by adding a vertical dimension with the cubic diamond substrate layer beneath the polycrystalline layer, allowing heat dissipation in the thickness direction while maintaining large lateral dimensions for the wafer.
3Reliability
If a (100)-oriented cubic synthetic diamond substrate is used, then device characteristics improve, but substrate production capability is limited
Solution Approach 1:
The substrate system separates the orientation requirement from the production volume requirement: the cubic synthetic diamond substrate provides the necessary (100) orientation for device performance, while the polycrystalline diamond layer provides the growth surface that can be produced at larger scales, thus resolving the contradiction between device quality and production capability.
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 reduces the cost and time required to inhibit warpage, allowing for improved bonding and mass production of semiconductor devices using polycrystalline diamond substrates.
Implementation Method 1
polycrystal diamond substrate with high thermal conductivity
Implementation Method 2
having a (100) surface... photoluminescence characteristics
Data Source
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AI summary
A provided is a polycrystalline diamond substrate that can reduce the cost for inhibiting warpage. The polycrystalline diamond substrate is a polycrystalline diamond substrate having a first principal surface and a second principal surface, and includes, between the first principal surface and the second principal surface, a surface having an average grain diameter smaller than each of average grain diameters of the first principal surface and the second principal surface.