Bonded SOI Wafer Tilted Substrate Inhibits Stripe Defects
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Solution Overview
Problem
The existing methods for growing silicon epitaxial layers by vapor phase epitaxy often result in stripe-shaped surface irregularities due to high dopant concentrations, which deteriorate the surface shape and adhesiveness at the bonding interface when manufacturing SOI wafers, leading to defects in the bonded SOI wafer.
Innovation Solution
The main surface of the silicon single crystal substrate is tilted at specific angles (θ in the [011] or [0-1-1] direction and φ in the [01-1] or [0-11] direction from the (100) plane, both less than ten minutes, to inhibit stripe-shaped surface irregularities even with high dopant concentrations of 1×10^19/cm^3 or more, using phosphorus as the dopant, thereby improving the adhesiveness at the bonding interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high dopant concentration is used in epitaxial layer growth, then device characteristics are improved, but stripe-shaped surface irregularities are formed deteriorating surface shape
Solution Approach 1:
The invention changes the crystal orientation parameter of the silicon substrate from conventional <100> to <110>, which fundamentally alters the epitaxial growth characteristics. This parameter change allows high dopant concentration to be used without forming stripe-shaped surface irregularities, as the <110> orientation prevents the specific growth conditions that cause such defects while maintaining high doping levels for improved device characteristics.
2Reliability
If high dopant concentration is used in epitaxial layer growth, then device characteristics are improved, but adhesiveness at bonding interface deteriorates
Solution Approach 1:
By changing the substrate crystal orientation to <110>, the invention eliminates the formation of stripe-shaped surface irregularities that would otherwise compromise bonding interface adhesiveness. This allows the full benefit of high dopant concentration to be realized for device characteristics without the detrimental effect on bonding strength.
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 effectively reduces surface irregularities and enhances the adhesiveness at the bonding interface, resulting in high-quality bonded SOI wafers with reduced defects, even when the epitaxial layer has a high dopant concentration, ensuring improved device characteristics.
Implementation Method 1
a silicon epitaxial layer grown by vapor phase epitaxy on a main surface of a silicon single crystal substrate
Implementation Method 2
growing a silicon epitaxial layer by vapor phase epitaxy on a main surface of a silicon single crystal substrate
Data Source
Figure 1(a)~4
Figure 5(a)~6(d)
Figure 7(a)~7(d)
AI summary
The present invention provides a silicon epitaxial wafer having a silicon epitaxial layer grown by vapor phase epitaxy on a main surface of a silicon single crystal substrate, wherein the main surface of the silicon single crystal substrate is tilted with respect to a [100] axis at an angle θ in a [011] direction or a [0-1-1] direction from a (100) plane and at an angle φ in a [01-1] direction or a [0-11] direction from the (100) plane, the angle θ and the angle φ are less than ten minutes, and a dopant concentration of the silicon epitaxial layer is equal to or more than 1×1019/cm3. According to the present invention, there are provided a silicon epitaxial wafer in which, even when an epitaxial layer having a dopant concentration of 1×1019/cm3 or more is formed on the main surface of the silicon single crystal substrate, stripe-shaped surface irregularities on the epitaxial layer are inhibited. There are also provided a method for manufacturing the silicon epitaxial wafer, a bonded SOI wafer with the silicon epitaxial wafer, and a method for manufacturing the bonded SOI wafer.