Diamond Thin Film - Laser Etching

Diamond Thin Film - Laser Etching

Material Name: Diamond
Recipe No.: 10305
Primary Chemical Element in Material: C
Sample Type: Thin film
Uses: Etching
Etchant Name: None
Etching Method: Laser etching
Etchant (Electrolyte) Composition: Two thicknesses of thin film diamond deposited by the technique of microwave plasma enhanced chemical vapour deposition (MWPECVD) have been employed in this study. The properties of these two films designated THIN and THICK are summarized in table 1. Both types of films displayed a morphology consisting of randomly aligned coalesced crystallites. Prior to laser processing and subsequent characterization, the samples were subjected to a wet etching treatment consisting of immersion in a saturated solution of H2SO4:NH4(SO4) (30 min, 200 C) followed by a H2O2:NH4OH solution (15 min, boiling); this has been shown to remove surface graphitic layers. An excimer laser (Lambda Physik LPX305i) operating at 193 nm (ArF) with an average pulse duration of 20 ns was used throughout. The output beam of the laser system, measuring 20 mm ~ 10 mm, was directed onto a chrome-on-quartz mask; the mask pattern was then directly projected via a 10:1 reduction lens system (NA = 0.05) onto the sample placed on a microprocessor controlled x-y-z stage. The system has been described in more detail elsewhere. SEM images were recorded using a Hitachi S800 instrument; film profiling was carried out using a Tencor Instrument profilometer. Raman scattering analysis was performed with a Renishaw System 2000 Raman spectrometer (He.Ne (632.8 nm) laser excitation). AES was carried out in an ultra-high vacuum (UHV) chamber with a base pressure 5 x 10 exp(-10) Torr. A primary electron beam energy of 3 kV was used throughout with a low beam current (1 µA) to minimize electron induced damage within the surface region; a Varian 981-2707 cylindrical mirror analyser (CMA) and associated electronics was used to produce differential Auger spectra. Electrical measurements were made using a Hewlett Packard HP4140B semiconductor parameter analyser.
Procedure (Condition): No data
Note: Excimer laser projection patterning with an ArF (193 nm) source has been employed in the irradiation of thin diamond films. The effect of a number of process parameters including laser fluence and processing ambient on the quality of the etch product has been investigated; scanning electron microscopy shows that good control of etch quality may be achieved with excellent lateral reproduction of images down to 2 ìm. Raman scattering and Auger electron spectroscopy of irradiated films have been correlated, and modifications in the diamond surface have been quantified according to processing parameters. Electrical tests on laser modified surfaces show that the reactivities of metals have a major role in the performance of contact metallizations on such a material. The viability of excimer laser etching of diamond as a manufacturing technique is considered.
Reference: Simon S M Chan, et al., The effect of excimer laser etching on thin film diamond, Semicond. Sci. Technol. 18 (2003) S47–S58.

Table 1: Details of diamond films used within this study. ‘Grain size’ is the average size of the grains on the top surface of the film as judged by scanning electron microscopy.