Carbon-Added Quartz SOQ Substrate Manufacturing
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Solution Overview
Problem
The use of quartz substrates in Silicon on Quartz (SOQ) manufacturing is hindered by their transparency, which prevents detection during wafer alignment and transfer processes, and surface roughening to enhance reflectivity can impair the substrate's flatness, while sapphire substrates are expensive and difficult to scale up in diameter.
Innovation Solution
A method involving a quartz substrate with a carbon concentration of 100 ppm or higher, where hydrogen ions are implanted into a silicon substrate, followed by surface treatment and bonding, and then delamination at low temperature to form a single crystal silicon thin film on the quartz substrate, allowing for a cost-effective, large-diameter SOQ substrate suitable for semiconductor manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent quartz substrate is used for SOQ substrate, then cost is reduced and diameter can be increased compared to sapphire substrate, but the substrate cannot be detected by transmission type sensors during wafer transfer and alignment processes
Solution Approach 1:
The invention changes the optical property of the quartz substrate by adding carbon impurities, transforming it from transparent to opaque. This allows the substrate to be detected by transmission type sensors during wafer transfer and alignment while maintaining the cost and diameter advantages of quartz substrates.
Solution Approach 2:
The invention changes the chemical composition parameter of the quartz substrate by controlling carbon concentration (100 ppm or higher). This parameter change modifies the optical transmission properties, enabling detection during manufacturing processes while preserving the economic benefits of using quartz instead of sapphire.
2Difficulty of detecting and measuring
If the back surface of the quartz substrate is sandblasted to increase reflectivity, then detection might be improved, but the substrate flatness is impaired and back-surface reflection remains insufficient due to low quartz reflectivity
Solution Approach 1:
Instead of modifying the surface morphology through sandblasting, the invention changes the bulk optical property by adding carbon impurities. This transforms the substrate from transparent to opaque, providing sufficient detection capability without compromising surface flatness or relying on insufficient back-surface reflection.
3Reliability
If sapphire substrate is used for SOS substrate, then heteroepitaxial growth can proceed due to close lattice constant match, but the substrate is very expensive and difficult to increase in diameter
Solution Approach 1:
The invention replaces expensive sapphire substrates with cheaper quartz substrates. By adding carbon impurities to make the quartz opaque, the invention enables detection during manufacturing, making the cheaper quartz substrate viable for producing SOS devices at lower cost with scalable diameter.
Solution Approach 2:
The invention changes the optical transmission parameter of the quartz substrate by controlling carbon concentration. This parameter modification enables the use of cost-effective quartz substrates with scalable diameters while maintaining manufacturing detectability, overcoming the economic and scalability limitations of sapphire substrates.
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 enables the production of a low-cost, large-diameter SOQ substrate that is adaptable to semiconductor device manufacturing, reducing power and signal losses in RF devices similar to SOS structures, while maintaining substrate flatness and avoiding surface roughness.
Implementation Method 1
an ion implantation step of implanting hydrogen ions to a main surface side of a single crystal silicon substrate
Implementation Method 2
a surface treatment step of performing surface activation through plasma treatment or ozone treatment
Implementation Method 3
a surface treatment step of performing surface activation through plasma treatment or ozone treatment
Implementation Method 4
a step of performing heat treatment on the single crystal silicon substrate and quartz substrate, which are bonded together, at a temperature of 350°C or lower
Implementation Method 5
the delamination step is preferably carried out by applying a mechanical shock onto a hydrogen ion implanted region at an edge of the single crystal silicon substrate
Data Source
Figure 1(A)~1(D)
AI summary
Hydrogen ions are implanted to a surface (main surface) of the single crystal Si substrate 10 to form the hydrogen ion implanted layer (ion-implanted damage layer) 11. As a result of the hydrogen ion implantation, the hydrogen ion implanted boundary 12 is formed. The single crystal Si substrate 10 is bonded to the quartz substrate 20 having a carbon concentration of 100 ppm or higher, and an external shock is applied near the ion-implanted damage layer 11 to delaminate the Si crystal film along the hydrogen ion implanted boundary 12 of the single crystal Si substrate 10 out of the bonded substrate. Then, the surface of the resultant silicon thin film 13 is polished to remove a damaged portion, so that an SOQ substrate can be fabricated. There can be provided an SOQ substrate highly adaptable to a semiconductor device manufacturing process.