Hybrid Orientation Substrate Fabrication via Amorphization and Annealing
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Solution Overview
Problem
The existing methods for fabricating hybrid orientation substrates using direct silicon bonding (DSB) and solid phase epitaxy (SPE) result in a slanted interface region, leading to increased space consumption and reduced integration on semiconductor wafers due to larger shallow trench isolations (STIs).
Innovation Solution
The method involves providing a DSB wafer with substrates of (100) and (110) crystalline orientations, forming and patterning blocking layers to define regions, performing amorphization and annealing processes to recrystallize the substrates, and using stress layers to reduce lateral morphology extension and improve transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid phase epitaxy (SPE) is used to convert substrate orientation, then carrier mobility is improved, but the interface region becomes slanted and larger
Solution Approach 1:
The patent changes the crystalline orientation parameter of the substrate by performing amorphization followed by controlled recrystallization. Specifically, a (110)-oriented silicon substrate is amorphized and then recrystallized to form a (100)-oriented epitaxial region, thereby changing the crystallographic orientation to improve carrier mobility while controlling the interface geometry
Solution Approach 2:
The patent applies preliminary amorphization treatment to the (110)-oriented silicon substrate before recrystallization. This preliminary action of converting the crystal structure to amorphous phase enables subsequent controlled recrystallization along the (100) orientation of the first substrate, preventing the formation of a large slanted interface region
2Manufacturing precision
If a larger interface region is formed, then SPE recrystallization is achieved, but shallow trench isolation (STI) space increases and integration is reduced
Solution Approach 1:
The patent controls the recrystallization process parameters to achieve high-quality (100)-oriented epitaxial region formation with minimal lateral extension. By carefully controlling temperature, time, and the amorphization depth, the recrystallization proceeds vertically without significant lateral growth, maintaining small STI requirements
Solution Approach 2:
The preliminary amorphization step creates a controlled amorphized region that limits the lateral spread during subsequent recrystallization. This preliminary action ensures that the epitaxial region grows primarily in the vertical direction toward the surface, minimizing lateral morphology extension and reducing the space required for STI
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 interface region between substrates, economizes space for STIs, and enhances the speed and quality of MOS transistors by applying compressive and tensile stresses through blocking layers, improving electron and hole mobility.
Implementation Method 1
The NMOS region 110 is exposed to an amorphizing ion implantation 120 and is amorphized to a depth beyond the bonded interface
Implementation Method 2
a SPE method is used to convert the orientation of NMOS region 110 from (110)-oriented into (100)-oriented
Implementation Method 3
a (110)-oriented Si substrate 102 is directly bonded to the (100)-oriented Si substrate 100 by DSB technique
Data Source
AI summary
A method for fabricating a hybrid orientation substrate includes steps of providing a direct silicon bonding (DSB) wafer having a first substrate with (100) crystalline orientation and a second substrate with (110) crystalline orientation directly bonded on the first substrate, forming and patterning a first blocking layer on the second substrate to define a first region not covered by the first blocking layer and a second region covered by the first blocking layer, performing an amorphization process to transform the first region of the second substrate into an amorphized region, and performing an annealing process to recrystallize the amorphized region into the orientation of the first substrate and to make the second region stressed by the first blocking layer.