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Method for temperature uniformity control in a flash anneal system using a multizone hotplate controller

IP.com Disclosure Number: IPCOM000011848D
Publication Date: 2003-Mar-19
Document File: 3 page(s) / 65K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for temperature uniformity control in a flash anneal system using a multizone hotplate controller. Benefits include improved transistor performance and reliability.

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Method for temperature uniformity control in a flash anneal system using a multizone hotplate controller

Disclosed is a method for temperature uniformity control in a flash anneal system using a multizone hotplate controller.� Benefits include improved transistor performance and reliability.

Background

        � � � � � In order to maximize transistor performance, it is desirable to maximize the temperature without degrading other transistor properties. Since the peak temperature is constrained, any temperature nonuniformity across the wafer results in regions with sub-optimal performance. All improvements in this area increase the portion of wafers processed under optimal conditions.

        � � � � � In a flash anneal system, a wafer is raised to an intermediate temperature with a hot-plate� (figure 1 – a halogen lamp based system can also be used).� The system is then irradiated with a rapid burst of energy from a flash anneal system that raises the surface of the wafer to the desired temperature.� In addition to the peak temperature and duration, one of the major design goal of this system is to produce a uniform peak temperature profile across the wafer.

        � � � � � RTP chamber design typically focus on optimizing uniformity based on blank silicon wafers implanted with a dopant for resistivity characterization.� Because a wafer covers a large percentage of the bottom of the reactor chamber (see Figure 4), it has a significant effect on the chamber uniformity.� A reflective wafer will couple differently than a black body because it is an integral part of the chamber.� A higher emissivity wafer has fewer reflections before absorption which results in a lower amount of light elsewhere in the chamber.� This can affect the temperature uniformity of the final surface temperature.� � �

        � � � � � Conventionally, patterned wafers will have significantly different emmisivities than blank silicon wafers because the component film stacks and chip layouts have different emissivities.� An anneal tool that utilizes radiation for heating/cooling that has a uniform temperature profile for all wafer emissivities is difficult to design.� The suggested approach is to compensate for gross non-uniformity and emmisivity dependent effects with a multi-zone hotplate (figure 2).� Having a large number of zones enables the temperature profile to be customized to compensate at the intermediate temperature to yield a uniform final temperature (Figure 3).� This method can also be applied to a system that utilizes a halogen light system instead of the hotplate.� In this case, the light intensity g...