This ALD-inSE tool comprises a Picosun R200 ALD system and a Woollam RC2-XI spectroscopic ellipsometer for in situ measurements.

The ALD system features a hot wall, viscous flow reactor fed by up to 6 liquid or solid precursor sources and 2 gas precursors (H₂S and either ozone or O₂). Along with H₂O, the standard precursors include diethylzinc (DEZn), trimethylaluminum (TMA) and tin(II) acetylacetonate [Sn(acac)₂]. The ozone source is shared with PT17 and is useful both for in situ substrate cleaning and as a reactant for ALD.

The ALD system is configured for thermal ALD with substrate temperatures from room temperature up to 500 °C. The standard holder fits substrates up to 6” in diameter, but a mini-batch holder can also be mounted for running up to 5 substrates at a time. The ALD software permits advanced precursor sequences to be saved in recipes and is also capable of running a sequence of preprogrammed recipes, including different temperature settings.

Standard recipes are available to deposit common materials. These materials include ZnS, ZnO, Al₂O₃ and SnS. Currently, precursors for HfO₂ are also available.

The spectroscopic ellipsometer is mounted at a fixed angle and includes a dual rotating compensator and a near infrared extension such that wavelengths from 210 to 1690 nm (~1065 wavelength values) are covered. Spectra can be acquired in 0.5 s (typically 2 s) and include the full Mueller matrix (15 independent variables). This allows for full characterization of anisotropic samples. The in situ SE software mode enables real-time monitoring of thickness and optical properties of growing films.

The tool is mainly intended for:

• Deposition of pin-hole free, conformal and ultrathin (~1-100 nm) metal sulfide and metal oxide layers on inorganic and possibly nanostructured substrates.
• Deposition of 2D semiconductors based on sulfides, and their multilayer counterparts.
• In situ characterization of growing films by spectroscopic ellipsometry in standard, generalized or full Mueller matrix ellipsometry mode.

Clean Si and glass substrates are accepted. Other substrates must be approved by the tool responsible.