Thins films play a critical role in many technical fields today, such as optics, semiconductor, and tool manufacturing. A widely used method for thin film deposition is magnetron sputtering, with Direct-Current Magnetron Sputtering (DCMS) being the most conventional approach. DCMS is very capable at depositing pure metallic (e.g. Al, Ti) or non-metallic (e.g. C, B) films, but encounters problems when depositing compound films, such as oxides or nitrides, in a process known as reactive DCMS (R-DCMS). The process tends to drift into either metallic mode, characterized by high deposition rate but lacking compound formation, or poisoned mode, where compound forms, but with significantly lower deposition rate. Ideally, the process should be maintained in the transition region in-between the two, but this mode is very unstable and further complicated by a hysteresis effect when switching between metallic and poisoned modes. An alternative approach is High-Power Impulse Magnetron Sputtering (HiPIMS) which has been shown to mitigate or remove the instability and hysteresis seen in R-DCMS, as well as improving film density, adhesion and film uniformity on complex geometries. In many cases however, feedback control is needed to stabilize the transition region in reactive HiPIMS (R-HiPIMS). This thesis presents a novel, non-invasive control method for R-HiPIMS using Plasma Emission Monitoring (PEM) to automatically adjust the HiPIMS pulse repetition rate to maintain the delicate transition region. The method was tested on growth of titanium oxide (TiOx) using an industrially relevant deposition system. It was bench-marked against deposition in poisoned mode, and against a control method based on peak discharge current. Results are promising, with higher deposition rate than poisoned mode deposition, and better process stability than peak current control. Challenges remain in making the controller more robust to changes in plasma characteristics due to moving parts, in this case a moving substrate carrier.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:ltu-108197 |
| Date | January 2024 |
| Creators | Törngren, Jacob |
| Publisher | Luleå tekniska universitet, Institutionen för system- och rymdteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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