Solar Cell In-Situ PECVD Coating for Faster Layer Deposition
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Solution Overview
Problem
Existing solar cell production methods using low-pressure chemical vapor deposition (LPCVD) result in low deposition rates for doped semiconductor layers, leading to increased operating costs and reduced throughput.
Innovation Solution
A method involving plasma oxidation and plasma-enhanced chemical vapor deposition (PECVD) to coat substrates with oxide and silicon or SiC layers in situ, under vacuum, without the need for loading and unloading procedures, using low-pressure plasma with controlled plasma parameters to maintain efficiency and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-pressure chemical vapor deposition (LPCVD) is used to deposit doped semiconductor layers, then the deposition can be performed under controlled vacuum conditions, but the deposition rate is low leading to reduced productivity and increased operating costs
Solution Approach 1:
The patent changes the deposition method from LPCVD to PECVD, altering the physical and chemical parameters of the deposition process. PECVD uses plasma-enhanced chemical vapor deposition with parameters such as radio frequency power (13.56 MHz), lower pressure (0.1-10 mbar), and reactive gas mixtures (silane, oxygen, nitrogen) to achieve higher deposition rates while maintaining layer quality and controllability
Solution Approach 2:
The patent replaces the thermal field-based LPCVD process with a plasma field-based PECVD process. The mechanical/thermal energy used in LPCVD is substituted with electromagnetic plasma energy, enabling lower temperature operation and faster deposition rates through enhanced chemical reactivity of plasma-excited species
2Manufacturing precision
If multiple deposition steps are performed with loading and unloading procedures between them, then each layer can be deposited with optimal parameters, but the process time increases and throughput decreases
Solution Approach 1:
The patent merges the deposition of the oxide tunnel layer and the doped semiconductor layer into a single continuous PECVD process step. Both layers are deposited in the same vacuum chamber without breaking vacuum, eliminating loading/unloading cycles and aeration steps, thereby reducing total process time while maintaining layer quality through optimized gas sequence control
Solution Approach 2:
The patent implements continuous deposition of multiple layers without interrupting the vacuum state. The useful action of deposition continues uninterrupted by using in-situ layer formation, where the first layer (oxide) and second layer (doped semiconductor) are deposited sequentially in the same chamber, eliminating idle time associated with chamber pressurization and re-evacuation
3Manufacturing precision
If plasma oxidation is used to generate the oxide layer, then the layer can be formed with high homogeneity and controlled thickness, but the process requires precise plasma parameter control
Solution Approach 1:
The patent optimizes plasma deposition parameters including radio frequency power (13.56 MHz), pressure (0.1-10 mbar), gas flow rates, and temperature (200-450°C) to achieve homogeneous oxide and semiconductor layers with controlled thickness. The plasma power density and gas composition are carefully adjusted to balance deposition rate and layer uniformity
Solution Approach 2:
The patent employs real-time monitoring and control of plasma parameters during deposition. Process variables such as plasma power, gas flow, and chamber pressure are continuously monitored and adjusted to maintain optimal deposition conditions, ensuring homogeneous layer formation and consistent thickness control across the substrate
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 method enhances deposition rates, reduces operational costs, and improves the homogeneity of the oxide layer, leading to more efficient solar cell production with lower layer thickness deviations, suitable for mass manufacturing.
Implementation Method 1
oxidizing the substrate by exposing it to an oxygen-containing gas and to a first plasma, to generate an oxide layer
Implementation Method 2
exposing it to an oxygen-containing gas and to a first plasma
Implementation Method 3
depositing a silicon layer or SiC-(silicon carbide) layer by exposure to a silicon-containing gas, an optional carbon-containing gas and a second plasma
Implementation Method 4
depositing a silicon layer or SiC-(silicon carbide) layer by exposure to a silicon-containing gas
Data Source
AI summary
A method for producing a solar cell, including the following steps: a) providing a substrate having a front side and a back side in a deposition apparatus, and b) coating the substrate in situ with two layers, including b1) oxidizing, by exposing the substrate to an oxygen-containing gas and a first plasma, to create an oxide layer and b2) subsequently depositing a silicon layer or SiC layer by exposure to a gas containing silicon, an optional gas containing carbon and a second plasma, wherein step b) is carried out under vacuum in the deposition apparatus and the vacuum is maintained continuously during step b).