| 1. |
- Nyberg, Tomas, et al.
(författare)
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A simple model for non-saturated reactive sputtering processes
- 2019
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 688
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Tidskriftsartikel (refereegranskat)abstract
- Reactive sputtering processes are quite complex processes and therefore difficult to understand in detail. However, a number of attempts to clearify the behaviour of reactive sputtering of oxides and nitrides have been made. Several process modelling results for such processes have been published that reasonable well mirrors the actual experimental findings. All of these models indicate that the processes normally exhibit hysteresis effects and that the oxides/nitrides will saturate at the stoichiometric compound values. We therefore call these processes saturated reactive sputtering processes. Carrying out reactive sputtering in a hydrocarbon gas like CH4 instead of in oxygen or nitrogen cannot be described with the previously suggested models for oxide or nitride formations. Decomposition of the CH4 molecule in the plasma may result both in carbide formation with the target metal as well as plasma deposited carbon. Depending on the supply of the CH4 the deposited film composition may vary from 0 to 100% of carbon. In the extreme case of very high supply of CH4 a pure carbon film will be deposited. We expect that similar behaviour will be found when carrying out reactive sputtering in other solid material containing gases like e.g. silane or diborane. We have chosen to call such processes non-saturated reactive sputtering processes. In order to understand the behaviour of non-saturated reactive sputtering processes we have developed a new model that enables the user to find the response to individual processing parameters and thus obtain a tool for process optimization. In order to limit the number of parameters our model is outlined for reactive sputtering of Ti in a mixture of argon and CH4. In this article we report that the simulation results reasonable well correlate with our experimental findings.
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| 2. |
- Rosén, Daniel, 1974-
(författare)
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Studies of the Reactive Sputtering Process and its Application in Electro-Acoustic Devices
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electro-acoustic devices such as surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices have been in commercial use for over 60 years and can be found in applications ranging from specialised scientific and military equipment to consumer products, such as mobile telephones, TV and radio receivers, etc. Today by far the largest market for electro-acoustic devices is the telecommunication industry which annually consumes approximately three billion acoustic wave filters for frequency control alone.The development of new materials and technologies for electro-acoustic devices has gained a substantial and growing interest from both academic and industrial research communities in recent years due to the enormous growth in the telecommunication industry and other forms of wireless data communication. One of the bigger issues has been to replace the single crystalline substrates with thin film piezoelectric materials deposited by reactive sputtering. This would not only reduce the manufacturing costs but will also enable high frequency of operation and a wider choice of substrate materials. However, in order to obtain the material properties required for the intended application a detailed theoretical description of the reactive sputtering process is necessary since the texture and other functional properties of the piezoelectric material are extremely sensitive to the process parameters in addition to the structure of the underlying material.This thesis studies the reactive sputtering process and its application for the fabrication of thin film electro-acoustic devices. The aim has been to gain a further insight into the process and make use of this knowledge to improve the fabrication of electro-acoustic devices. In this work modelling of the reactive sputtering process has been improved by studying certain fundamental aspects of the process and in particular the dynamics of the processes taking place during sputtering both at the target and the substrate surfaces. Consequently, highly textured thin piezoelectric aluminium nitride films have been synthesized and thin film bulk acoustic resonators (FBAR) operating in the GHz range have been fabricated and studied.
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| 3. |
- Särhammar, Erik, et al.
(författare)
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Applying "the upgraded Berg model" to predict hysteresis free reactive sputtering
- 2016
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Ingår i: Surface and Coatings Technology. - : Elsevier BV. - 0257-8972.
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Konferensbidrag (refereegranskat)abstract
- Reactive sputtering is a popular process to deposit oxides, nitrides, and several other compounds. Unfortunately, this process mostly exhibits a hysteresis effect. The hysteresis causes a delicate choice of either a high deposition rate but not a fully oxidized/nitrided film or a fully formed compound film but at a significantly lower deposition rate. For high reactivity target material/reactive gas systems, the hysteresis forces the process to flip quite abrupt between these two conditions. Process control may therefore be quite critical. In this work we will use the original "Berg model" as well as the newly published "upgraded Berg model" to illustrate how hysteresis is generated. We have selected one simple graph (reactive gas flow vs. partial pressure) that gives clear indications of how the process may be affected in such a way as to decrease or even eliminate the hysteresis. Specific values of target size and composition, gas mixture as well as total pressure and pumping speed are processing parameters that may be selected in a way to eliminate hysteresis. We will show that this behavior is predicted by the simulations and also refer to experimental evidence for such behavior.
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| 4. |
- Särhammar, Erik, et al.
(författare)
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Applying "the upgraded Berg model" to predict hysteresis free reactive sputtering
- 2015
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 279, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- Reactive sputtering is a popular process to deposit oxides, nitrides, and several other compounds. Unfortunately, this process mostly exhibits a hysteresis effect. The hysteresis causes a delicate choice of either a high deposition rate but not a fully oxidized/nitrided film or a fully formed compound film but at a significantly lower deposition rate. For high reactivity target material/reactive gas systems, the hysteresis forces the process to flip quite abrupt between these two conditions. Process control may therefore be quite critical. In this work we will use the original "Berg model" as well as the newly published "upgraded Berg model" to illustrate how hysteresis is generated. We have selected one simple graph (reactive gas flow vs. partial pressure) that gives clear indications of how the process may be affected in such a way as to decrease or even eliminate the hysteresis. Specific values of target size and composition, gas mixture as well as total pressure and pumping speed are processing parameters that may be selected in a way to eliminate hysteresis. We will show that this behavior is predicted by the simulations and also refer to experimental evidence for such behavior.
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| 5. |
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| 6. |
- Barankova, Hana, et al.
(författare)
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Abnormal High Rate Deposition of TiN Films by the Radio Frequency Plasma Jet System
- 1995
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Ingår i: J Electrochem Soc. - 0013-4651. ; 142:3, s. 883-887
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency Ar and Ar + N-2 plasma jets generated in a hollow electrode terminated by a small size Ti nozzle were used for deposition of Ti and TiN films. The regime with low content of reactive gas resulted in an extreme enhancement of TiN deposition
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| 7. |
- Barankova, Hana, et al.
(författare)
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Characterization of the linear arc discharge (LAD) source for film deposition
- 1997
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Ingår i: SURFACE & COATINGS TECHNOLOGY. - 0257-8972. ; 94-5:1-3, s. 578-582
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Tidskriftsartikel (refereegranskat)abstract
- The linear arc discharge (LAD) source is a parallel plate hollow cathode with a magnetic field perpendicular to the plates near the outlet slit of the cathode. The hollers cathode discharge is generated by radio frequency (rf) power and is confined mainly
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| 8. |
- Barankova, Hana, et al.
(författare)
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Hysteresis effects in the sputtering process using two reactive gases
- 1995
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Ingår i: Thin Solid Films. - 0040-6090. ; 260:2, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- The reactive sputtering process involving two reactive gases has been investigated. Sputtering titanium in the presence of oxygen and nitrogen in argon was studied by means of optical emission and mass spectrometries. The experiments reveal the mechanism
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| 9. |
- Barankova, Hana, et al.
(författare)
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Linear arc discharge (LAD): A new type of hollow cathode plasma source
- 1996
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Ingår i: SURFACE & COATINGS TECHNOLOGY. - 0257-8972. ; 87-8:1-3, s. 377-380
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Tidskriftsartikel (refereegranskat)abstract
- A novel linearly scalable source for low pressure plasma processing is described. The source is based on a parallel plate hot hollow cathode in a focusing magnetic field which allows generation of a linearly uniform plasma in a gas admitted into the slit
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| 10. |
- Barankova, Hana, et al.
(författare)
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Metastable assisted deposition of TiN films
- 1995
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Ingår i: Appl Phys Lett. - 0003-6951. ; 67:11, s. 1521-1523
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Tidskriftsartikel (refereegranskat)abstract
- An excess heat from an exothermic reaction of metastable Ar (4(3)P(0)) and Ar (4(3)P(2)) atoms with N-2 molecules at low contents of N-2 in Ar was found to be responsible for an enhanced thermionic emission, an enhanced production of Ti target vapor, an i
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