Noncontact measurement of substrate temperature by optical low-coherence interferometry in high-power pulsed magnetron sputtering

Abstract

Substrate temperature is one of the important parameters that affect the quality of deposited films. The monitoring of the substrate temperature is an important technique of controlling the deposition process precisely. In this study, the Si substrate temperature in high-power pulse magnetron sputtering (HPPMS) was measured by a noncontact method based on optical low-coherence interferometry (LCI). The measurement was simultaneously performed using an LCI system and a thermocouple (TC) as a contact measurement method. The difference in measured value between the LCI system and the TC was about 7.4 °C. The reproducibilities of measurement for the LCI system and TC were +0.7 and +2.0 °C, respectively. The heat influx from the plasma to the substrate was estimated using the temporal variation of substrate temperature and increased from 19.7 to 160.0 mW/cm 2 with increasing target applied voltage. The major factor for the enhancement of the heat influx would be charged species such as ions and electrons owing to the high ionization degree of sputtered metal particles in HPPMS.

Fiber Bragg grating sensor for in situ substrate temperature measurement in a magnetron sputtering system

“…It is also most common to deposit a thin film on bigger substrates for all real life applications. In such cases, thermocouple, bimetallic strip, pyrometer and LCI method [10,18] can only detect temperature at one point and there is no way to get information about the temperature gradient from centre to the periphery of a substrate. To demonstrate the additional utility of this method and multiplexing capability of FBGs, temperature was recorded using four FBGs and successfully mapped the temperature variation along the lateral direction of a substrate.…”

“…But when different substrates are loaded, the angle and point of contact with thermocouple varies leading to an error in the temperature measured [9]. To overcome erroneous measurement by thermocouple, non-contact temperature measurement by low coherence interferometry (LCI) was proposed by Katsuhiro Hattori et al [10]. Since this non-contact method eliminates the errors due to placement of thermocouple and the contact with the substrate, it has better repeatability.…”

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

“…Noncontact measurements of the substrate temperature have been reported by low-coherence interferometry. 187) The uniformity of the substrate temperature was controlled using a multizone heating system. [188][189][190][191] The temperature of the electrostatic chuck, used as a wafer susceptor, was monitored using a wireless-type on-wafer temperature monitoring system.…”

Effect of pulse width on deposition of diamond-like carbon on high-power pulsed magnetron sputtering

“…26,27) Energy flux to the substrate was also evaluated by using non-contact optical low-coherence interferometry on Ti-HPPMS. 28) It is essential to diagnose the plasma chemistry in HPPMS plasma to characterize the microstructure of the DLC film, because the ionic or neutral species produced in the plasma are incident on the film. The production mechanism of ions or the measurement of ion energy and ion flux in carbon-HPPMS has been reported.…”