SiC AlSi Surface Electrode with Dendrite Si Nodules for Wire Bonding
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face issues with alloy spikes and silicon nodules formation due to mutual diffusion between aluminum and silicon atoms, leading to device defects and poor embeddability of surface electrodes, especially when using sputtering techniques at lower temperatures.
Innovation Solution
The silicon carbide semiconductor device employs an aluminum alloy surface electrode with silicon nodules, where the temperature of the semiconductor substrate during sputtering is set to at least 430 degrees Celsius to form dendrite-structured silicon nodules, enhancing embeddability and preventing bonding wire peeling by maintaining a thin thickness at the joint portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature of the semiconductor substrate during sputtering is set to a low temperature (less than about 300 degrees C.), then mutual diffusion of silicon atoms and aluminum atoms is suppressed, but embeddability of the surface electrode deteriorates
Solution Approach 1:
The patent changes the substrate temperature parameter from conventional low temperatures (less than 300°C) to a higher temperature range (400°C to 700°C). This parameter change fundamentally alters the diffusion behavior of atoms, allowing controlled formation of Si nodules with dendrite structures that improve embeddability while maintaining reliability through the specific morphological characteristics of the nodules.
Solution Approach 2:
The patent utilizes phase transition principles by controlling the crystallization morphology of silicon nodules. At the elevated temperature range of 400°C to 700°C, silicon atoms undergo phase transitions that result in dendrite structures rather than prismatic structures. This morphological phase transition is key to achieving both good embeddability and electrical characteristics.
2Reliability
If the temperature of the semiconductor substrate during sputtering is set to at least 300 degrees C., then alloy spikes are not easily generated, but prismatic silicon nodules are formed which cause bonding wire peeling
Solution Approach 1:
The patent further refines the temperature parameter within the 400°C to 700°C range to control the morphology of Si nodules. By optimizing this parameter, the patent achieves dendrite structures instead of prismatic structures, which have different mechanical properties that prevent bonding wire peeling while maintaining suppression of alloy spikes.
Solution Approach 2:
The patent creates a composite structure within the AlSi electrode by controlling the formation of Si nodules with specific dendrite morphologies. This composite structure, consisting of aluminum matrix with embedded dendritic silicon phases, provides both suppression of alloy spike formation and improved bonding wire adhesion through the unique mechanical interlocking provided by the dendrite structures.
3Quantity of substance
If silicon atoms diffuse into the AlSi electrode from the semiconductor substrate, then mutual diffusion occurs, but Si nodules are deposited near the interface increasing electrical resistance
Solution Approach 1:
The patent converts the harmful effect of silicon atom diffusion and Si nodule formation into a beneficial effect. By controlling the temperature to form dendrite-structured Si nodules, the patent transforms what was previously a defect (increased electrical resistance) into a feature that maintains good electrical characteristics. The dendrite morphology provides a larger surface area and better interface contact, reducing resistance despite the presence of nodules.
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 suppresses the formation of prismatic silicon nodules, reduces crack generation, and improves the reliability of the semiconductor device by maintaining a high area percentage of dendrite-structured nodules, thereby enhancing yield and embeddability of the AlSi electrode.
Implementation Method 1
a surface electrode of an aluminum alloy containing silicon, the surface electrode being provided on a surface of the semiconductor substrate
Implementation Method 2
mutual diffusion of silicon atoms in the semiconductor substrate and aluminum atoms in the AlSi electrode
Implementation Method 3
One of the number of the silicon nodules is of a dendrite structure
Data Source
AI summary
A silicon carbide semiconductor device, including a semiconductor substrate containing silicon carbide, a bonding wire, and a surface electrode of an aluminum alloy containing silicon, the surface electrode being provided on a surface of the semiconductor substrate, and having a joint portion to which the bonding wire is bonded. The surface electrode has a plurality of silicon nodules formed therein, which include a number of the silicon nodules formed in the joint portion. One of the number of the silicon nodules is of a dendrite structure, and is included at an area percentage of at least 10% relative to a total area of the number of the silicon nodules in the joint portion.