Chemical vapor etching
At IEMN, we have developed for several years a know-how in the release of devices by dry process (MEMS, active layers for transfer on flexible...). Indeed, dry chemical etching offers an interesting alternative to wet etching since it avoids stiction effects, while keeping a high selectivity and strongly limiting the corrosion of many metals. This technique is also complementary to plasma etching because it offers isotropic etching, better selectivity between materials and avoids surface damage with slower etching speeds and no ion bombardment. Currently, we are able to etch 2 materials in the Si die: Si, using a Xactix X4 frame, and SiO2, using a µEtch SPTS frame.
Expertise and know-how: 3 key points
- transfer of active layers on flexible material
Transistor of the GaN die transferred on flexible after thinning of the substrate and 20µm XeF2 etching of the remaining Si layer (Carbon team)
- Si etching using vapor-phase XeF2 etch cycles exhibiting high selectivity over thermal oxide and resin.
Release by 10µm deep XeF2 etching of a thermoelectric characterization platform on 60nm Si membrane protected by BOX. The oxide is then etched by HF in vapor phase (MicroelecSi team)
- SiO2 etching, performing vapor phase HF etch cycles offering high selectivity to Si and very good compatibility with many materials such as SiC, Al, Pt, Au, Ni, Cr, TiW, and Al2O3.
Sub etching of a 2µm BOX by HF in vapor phase (Nam6 team)
Expertise and know-how: other
- Supercritical CO2 drying of wet-released structures to avoid stiction phenomena.
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