Direct temperature monitoring for semiconductors in plasma immersion ion implantation

Abstract

In situ temperature monitoring is extremely important in plasma immersion ion implantation ͑PIII͒ of semiconductors. For instance, the silicon wafer must be heated to 600°C or higher in separation by plasma implantation of oxygen, and in the PIII/ion-cut process, the wafer temperature must remain below 300°C throughout the experiment. In this article, we present a thermocouple-based direct temperature measurement system for planar samples such as silicon wafers. In order to ensure reliable high-voltage operation and overall electrical isolation, the thermocouple assembly and wires are integrated into the sample chuck and feedthrough. Hydrogen plasma immersion ion implantation is performed in silicon to demonstrate the effectiveness and reliability of the device. Our experimental results indicate that instrumental parameters such as implantation voltage, pulse duration, and pulsing frequency affect the sample temperature to a different extent. The measured temperature rise is higher than that predicted by a theoretical model based on the Child-Langmuir law. The discrepancy is attributed to the finite-sample size and the nonplanar, conformal plasma sheath.

Two-dimensional sample temperature modeling in separation by plasma implantation of oxygen (SPIMOX) process

“…This trend is consistent with our experimental results obtained for different targets and processing parameters [18]. that it is not easy to reach 600 o C using ion implantation alone.…”

A semi-analytical method to study the temperature evolutions of a slab and a semi-infinite target for plasma immersion ion implantation

“…To confirm relevancy and accuracy of this model, a comparison between the predicted and measured surface temperatures as a function of time [17] for a hydrogen plasma and silicon wafer are shown in Fig. 2.…”

“…For example, the silicon wafer temperature must be heated to 600°C or higher in separation by plasma implantation of oxygen, and in the PIII/ion cut process, the wafer temperature must remain below 300°C during implantation [17]. Many methods and models have been proposed for measurement and prediction of the substrate temperature in the plasma [17][18][19][20][21][22][23]. Tian et al [17,18] proposed a thermocouple-based direct temperature measurement system to monitor the temperature evolution of silicon wafers during hydrogen plasma immersion ion implantation.…”

“…Many methods and models have been proposed for measurement and prediction of the substrate temperature in the plasma [17][18][19][20][21][22][23]. Tian et al [17,18] proposed a thermocouple-based direct temperature measurement system to monitor the temperature evolution of silicon wafers during hydrogen plasma immersion ion implantation. Experimental results indicated that implantation voltage, pulse duration and pulse frequency affect strongly the substrate temperature.…”

“…Precise controlling of the substrate temperature is extremely important in PIII of semiconductors. For example, the silicon wafer temperature must be heated to 600°C or higher in separation by plasma implantation of oxygen, and in the PIII/ion cut process, the wafer temperature must remain below 300°C during implantation [17]. Many methods and models have been proposed for measurement and prediction of the substrate temperature in the plasma [17][18][19][20][21][22][23].…”