Epitaxial silicon

•  Manufacturing process of epitaxial silicon materials

1. Chemical vapor deposition (CVD)

• Process: With high purity silicon substrate as the substrate, silicon source gas (SIH₄ silane, SIHCL tetrachlorosilicon ₃, etc.) and hydrogen are introduced. Thermal decomposition reaction occurs at high temperature epitaxy (1000℃~1200℃) /800-950℃ (low temperature epitaxy) pressure: 10-100 TORR (low pressure CVD). Silicon atoms grow epitaxially on the surface of the substrate to form a single crystal layer. Growth rate: 0.5-5ΜM/MIN

Key technologies:

◦ Hydrogen cleaning: Remove oxide and pollutants on the surface of the substrate through H₂ high temperature treatment to ensure that the epitaxial layer matches the lattice of the substrate.

◦ Doping control: doping gas (B₂H₆ borane, PH₃ phosphine) is introduced simultaneously to realize the precise regulation of epitaxial layer resistivity and conductivity type.

2. Molecular beam epitaxy (MBE)

• Process: In ultra-high vacuum (10⁻¹⁰~10⁻⁹ TORR) environment, monocrystalline silicon film is deposited layer by layer by molecular beam bombardment on the surface of silicon substrate. It is suitable for low temperature (550℃~650℃) growth, reducing the diffusion of substrate impurities and improving the uniformity of the film.

3. Selective epitaxy technology

• Process: Using silica or silicon nitride as a mask, the silicon layer is grown only in specific regions to achieve local doping or hetero-integration.

Application scenario: used for PMOS source and drain SIGE epitaxial or NMOS SIC epitaxial to improve device mobility and drive current.

• Technical index advantages

1. High purity and low defect density

• Purity: The purity of electronic grade epitaxial silicon can reach 11N (99.999999999%), the resistivity range can cover 0.001-1000Ω·CM, and the impurity content is less than 0.1PPB, which can meet the requirements of different devices and reduce the risk of leakage and failure of devices.
• Defect control: lattice defect density <0.1/CM², metal impurities are migrated to the back of the substrate through “absorption (GETTERING)” technology to improve device reliability.
• Excellent electrical performance: epitaxial silicon has low leakage current (<1NA/ΜM), high breakdown voltage (>600V) and high carrier mobility (electron mobility>1500CM²/V·S), suitable for high frequency, high power scenarios.

2. Adjustable electrical properties

• Resistivity range: can be covered from 0.001Ω·CM to 1000Ω·CM through doping, suitable for different device requirements (low resistance layer for power devices, high resistance layer for RF devices).
• Migration rate optimization: The electron migration rate of N-type epitaxial layer is 1500CM²/V·S, and the hole migration rate of P-type is 450CM²/V·S, which supports high frequency and high power chip design.

Other advantages

• Application scenario advantages
• Semiconductor devices: used to manufacture power devices such as MOSFET and IGBT, the breakdown voltage is increased by 30%~50%, and the forward power consumption is reduced at the same time.
• Optoelectronics: as the core material of CIS (CMOS image sensor) and optical communication devices, improve quantum efficiency and response speed.

New energy and automotive electronics: Adapt to the demand for silicon carbide power chips, supporting high temperature and high pressure scenarios for inverter and charging pile of new energy vehicles.

• Integrated circuit: 12-inch epitaxial wafer is suitable for advanced processes below 7NM, improving chip integration and performance (logic device leakage reduced by 30%).

• Application scenarios and solutions

| trade         | Typical products                 | Extensive silicon advantages                              | Customer value

| Automotive electronics | IGBT module               | High blocking voltage + low conduction resistance                     The motor controller is reduced in size by 30%

| Photovoltaic inverter | High frequency DC/AC converter | High temperature stability (150℃ long term operation)               | System efficiency increased to 99.2%

| 5G base station | Power amplifier              | High electron mobility (1500 CM²/V·S)            Signal delay reduced by 15%

| Medical equipment | CT detector                High X-ray absorption rate (density 2.33G/CM³)           Image clarity improved by 25%

• Technology cost advantage

Material utilization: epitaxial growth reduces substrate loss and costs 70% less per wafer than silicon carbide

Process simplification: direct growth of PN junction structure, reduce 3 lithography processes, production cycle shortened by 20%

High temperature stability: the breakdown voltage of the epitaxial layer can reach 3000V,40% higher than ordinary silicon wafers, suitable for industrial motor drive

Radiation resistance: Through neutron transmutation doping (NTD) technology, the radiation resistance dose can reach 10⁶ RAD, meeting the requirements of aerospace grade

• Future technology trends
• Low temperature epitaxy technology: reduce the process temperature to below 550℃, reduce the self-doping effect (substrate impurity diffusion to the epitaxial layer), and improve the quality of the film.
• Large size wafers: Develop 12-inch wafers and develop 18-inch epitaxial wafers, combined with fluidized bed (FBR) to reduce energy consumption (40% less than traditional processes), to meet the needs of large-scale production in advanced processes (below 3NM).
• Green manufacturing: using a closed-loop circulation system to reduce exhaust emissions and reduce the carbon footprint by 80% compared with traditional processes.
• Intelligent process optimization: AI is introduced to monitor the epitaxial growth parameters (temperature gradient and gas flow) in real time, and the defect rate is reduced by 50%

The manufacturing processes for epitaxial silicon materials (such as CVD and MBE) have achieved a comprehensive improvement in electrical performance, defect control, and integration flexibility through high-purity silicon sources and precise doping techniques. These technological advantages are irreplaceable in the fields of semiconductor devices, optoelectronics, and new energy. In the future, they will continue to drive industrial upgrading with low-temperature processes, large-size wafers, and green manufacturing technologies.