MEMS Fabrication Tools

Tube furnace reactors (6" capable) for:

• silicon oxidation (wet and dry)
• solid source boron diffusion
• low stress silicon nitride/polysilicon LPCVD
• LPCVD of low temperature oxide

Si etching tools:

• Isotropic dry etching using XeF₂
• Deep reactive ion etching

Capabilities include the following processes:

• Dry/Wet oxidation of Si wafers with SiO₂ thicknesses up to 1 micrometer. The dry oxidation process yields pinhole free oxide films for 2 micrometer line width MOS gate technology. The wet oxidation process is capable of rapid growth of oxide films for masking dopant diffusion patterns.
• Solid source boron doping. The boron doping process with BN source wafers yields dopant profiles suitable for bulk micromachining of Si with subsequent anisotropic wet chemical etches. In addition, doping profiles suitable for 2 micrometer line width gate technology are attainable with the process.
• Low-stress Si₃N₄ low pressure chemical vapor deposition (LPCVD). The LPCVD Si₃N₄ process is capable of depositing a pinhole free film to be used for masking dopant diffusion patterns. In addition, the process is capable of depositing low stress Si₃N₄ onto sacrificial oxide or glass layers for the purposes of surface micromachining free standing Si₃N₄ micromechanical devices for MEMS integration.
• Poly Si LPCVD. The process is capable of depositing poly Si onto sacrificial oxide or glass layers for the purposes of surface micromachining free poly Si micromechanical devices for MEMS integration.
• Low temperature oxide (LTO) LPCVD. The LTO LPCVD process will be capable of depositing smooth sacrificial foundation layers for Si₃N₄ or poly Si films. The LTO layer has a fast wet chemical etch rate compared to the Si, Si₃N₄, or poly Si films.
• XeF₂ dry etching of Si. XeF₂ is a solid source dry etchant for extremely rapid isotropic etching of Si, with very high selectivity to oxide, nitride and other masking materials. The technique is useful for whole wafer backside etching and releasing surface micromachined structures with poly-Si as the sacrificial layer.
• Deep reactive ion etching. This tool uses the Bosch SF₆/C₄F₈ process to provide extremely high aspect ratio etching of Si with high selectivity. This allows nearly vertical structures to be machined into Si wafers.