SiC AlSi Electrode Sputtering to Control Si Nodule Growth
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Solution Overview
Problem
Conventional methods for manufacturing silicon carbide semiconductor devices face issues with Si nodules formation in AlSi electrodes, leading to device failure, peeling during wire bonding, and reduced yield due to interdiffusion of silicon and aluminum atoms, especially when high temperatures are used for sputtering.
Innovation Solution
The method involves sputtering the AlSi electrode at a temperature range of 430 degrees C. to 577 degrees C., allowing the silicon concentration to exceed solid solubility, which suppresses interdiffusion and promotes the formation of Si nodules with a dendrite structure, reducing peeling and enhancing embeddability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the sputtering temperature of the AlSi electrode is set to a high temperature (300°C or greater), then the embeddability of the surface electrode is improved, but Si nodules precipitate in the AlSi electrode and alloy spikes form in the semiconductor substrate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sputtering temperature within the range of 300°C to 577°C and adjusting the silicon concentration in the AlSi electrode to exceed solid solubility. This controlled parameter change allows the formation of Si nodules with dendrite structure that prevent alloy spike progression while maintaining good embeddability of the surface electrode into the contact hole.
Solution Approach 2:
The patent utilizes phase transitions by controlling the sputtering process to create Si nodules with dendrite structure through controlled solidification from a supersaturated state. The dendrite structure formation during phase transition is key to preventing alloy spike progression while maintaining electrode integrity and embeddability.
2Reliability
If the sputtering temperature is set to a low temperature (less than 300°C), then interdiffusion of silicon and aluminum atoms is suppressed, but the embeddability of the surface electrode deteriorates
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter to the optimized range of 300°C to 577°C and simultaneously adjusting the silicon concentration parameter to exceed solid solubility. This combined parameter change enables both suppression of harmful interdiffusion and achievement of good embeddability through controlled Si nodule formation with dendrite structure.
3Reliability
If silicon concentration in the AlSi electrode is increased above solid solubility, then Si nodules form to suppress interdiffusion, but device failure may occur due to nodule progression to pn junction
Solution Approach 1:
The patent applies parameter changes by controlling the silicon concentration to exceed solid solubility while precisely managing the sputtering temperature (300°C to 577°C). This controlled parameter change ensures Si nodules form with dendrite structure that actively suppress alloy spike progression rather than allowing progression to the pn junction, thereby preventing device failure.
Solution Approach 2:
The patent converts the potentially harmful effect of Si nodule formation into a beneficial effect by controlling the nodule structure to be dendrite-type. These dendritic nodules act as barriers that suppress alloy spike progression and protect the pn junction, transforming what could be a failure mechanism into a protective feature.
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 prevents Si nodules from growing into prismatic shapes, reduces peeling during wire bonding, and enhances the reliability and yield of silicon carbide semiconductor devices by maintaining the AlSi electrode's integrity and embedding ability.
Implementation Method 1
sputtering and thereby depositing the surface electrode on the surface of the semiconductor substrate
Implementation Method 2
A silicon concentration of the surface electrode is higher than a solid solubility of silicon in the surface electrode. A temperature of the semiconductor substrate, or a temperature of a vicinity of a region in which the surface electrode is formed, or both is in a range of 430 degrees C. to 577 degrees C.
Data Source
AI summary
An AlSi electrode containing an aluminum alloy that contains silicon is sputtered on a surface of a semiconductor substrate that contains silicon carbide. Si nodules having a dendrite structure precipitate in AlSi electrode. At least some of the Si nodules have a dendrite structure, and the rest of the Si nodules have a prismatic structure. A height of the Si nodules having either dendrite structures or prismatic structures in the AlSi electrode in a thickness direction of the AlSi electrode is not more than 2 μm. A height of the Si nodules having the dendrite structures in the AlSi electrode, preferably, may be 1 μm or less. A solid solubility of silicon in the AlSi electrode is in a range of 0.3 wt % to 1.59 wt %. A sputtering temperature of the AlSi electrode is in a range of 430 degrees C. to 577 degrees C.