EP-4737871-A1 - DEVICE AND SYSTEM FOR IN-SITU SCANNING SUBSTRATE TEMPERATURE IN AN EPITAXIAL REACTOR

EP4737871A1EP 4737871 A1EP4737871 A1EP 4737871A1EP-4737871-A1

Abstract

A temperature monitoring system for measuring the temperature of a substrate in a reactor comprising: (i) a reaction chamber suitable for the deposition of a film on a deposition surface of a substrate; (ii) a temperature monitoring device comprising an optical device, a remote sensing thermometer, and a supporting device. The remote sensing thermometer comprises at least one detector of IR radiation adapted for temperature measurements. The reaction chamber is provided with at least one aperture; the at least one optical device is adapted to: (i) intercept IR radiation emitted from at least one point of the deposition surface of the substrate through the aperture; and (ii) divert the intercepted IR radiation to the detector.

Inventors

MESCHIA, MAURILIO

Assignees

LPE S.p.A.

Dates

Publication Date: 20260506
Application Date: 20251024

Claims (20)

A temperature monitoring system for measuring the temperature of a substrate during the deposition process of a reactor; wherein said temperature monitoring system comprises: - at least one reaction chamber of a reactor, suitable for the deposition of a film on a deposition surface of a substrate; - at least one temperature monitoring device comprising at least one optical device, at least one remote sensing thermometer, and a supporting device; wherein the supporting device is adapted to support the at least one optical device and comprises a retractable element integral with said optical device; wherein the remote sensing thermometer comprises at least one detector of IR radiation adapted for temperature measurements, and wherein the reaction chamber is provided with at least one aperture; the at least one optical device being adapted to: - intercept IR radiation emitted from at least one point of the deposition surface of the substrate through the at least one aperture; and - divert the intercepted IR radiation to the at least one detector; in order to measure the temperature of said at least one point of the deposition surface with said remote sensing thermometer.
The temperature monitoring system according to claim 1, wherein the remote sensing thermometer is a pyrometer preferably adapted for spot temperature measurements.
The temperature monitoring system according to claim 1 or 2, wherein the remote sensing thermometer comprises a light source; wherein said light source emits a light beam to highlight the at least one point of the deposition surface of the substrate emitting the IR radiation being measured.
The temperature monitoring system according to any one of claims 1 to 3, wherein the supporting device comprises a cooling system.
The temperature monitoring system according to any one of claims 1 to 4, wherein the supporting device is adapted to displace the optical device along a predefined direction, preferably said predefined direction is substantially perpendicular to the deposition surface of the substrate.
The temperature monitoring system according to any one of claims 1 to 5, wherein the supporting device is provided with an opening and the optical device is enclosed, in toto or in part, within the supporting device.
The temperature monitoring system according to any one of claims 1 to 6, wherein the retractable element is made of graphite.
The temperature monitoring system according to any one of claims 1 to 7, wherein the supporting device is adapted to displace the optical device from a position A to a position A' different from A; so that: - in position A, the optical device is adapted to divert the intercepted IR radiation emitted from a first reference point of the deposition surface of the substrate to the at least one detector through the at least one aperture; and - in position A', the optical device is adapted to divert the intercepted IR radiation emitted from a second reference point of the deposition surface of the substrate to the at least one detector through the at least one aperture; wherein said second reference point is different from the first.
The temperature monitoring system according to any one of claims 1 to 8, wherein the supporting device is configured to displace the optical device from a position A to a position B different from A; wherein: - in position A, the optical device is adapted to divert the IR radiation emitted from a first reference point of the deposition surface of the substrate to the at least one detector through the at least one aperture; and - in position B, the optical device is out of the line of sight of any and all points of the deposition surface of the substrate.
The temperature monitoring system of any one of claims 1 to 9, wherein the supporting device is configured to displace the optical device in a direction perpendicular to the deposition surface of the substrate to continuously scan the temperature of the deposition surface along a plurality of points, preferably said plurality of points includes a center point and at least one peripheral point of the deposition surface of the substrate, preferably the at least one peripheral point is the upstream peripheral point.
The temperature monitoring system according to any one of claims 1 to 10, wherein the at least one optical device is a prism or a mirror suitable to operate at temperatures between 1400-1750 °C.
The temperature monitoring system according to any one of claims 1 to 11, wherein the remote sensing thermometer is adapted to be displaced along a predefined trajectory in order to scan the temperature of the deposition surface along a plurality of points, including at least the center point and at least one peripheral point of said deposition surface.
The temperature monitoring system according to any one of claims 1 to 12, wherein the at least one aperture is an aperture adapted to discharge exhaust gases out of the reaction chamber.
The temperature monitoring system according to any one of claims 1 to 13, wherein the temperature monitoring device is connected to a gas source adapted to flow a gas between the optical device and the substrate.
The temperature monitoring system of claim 14, wherein the gas source is a source of inert gas, preferably argon, or hydrogen.
The temperature monitoring system according any one of claims 1 to 14; wherein the temperature monitoring device is adapted to convert the temperature measured by the remote sensing thermometer into a first electrical signal; wherein the temperature monitoring device further comprises: - a data acquisition system adapted to acquire said first electrical signal and convert it into a first set of digital numeric values; and - an accessible memory and a processor adapted to process said first set of digital numeric values.
The temperature monitoring system of claim 16; wherein the temperature monitoring device further comprises: a position sensor adapted to measure the position of the optical device and to convert it into a second electrical signal, and the data acquisition system is adapted to acquire said second electrical signal and convert it into a second set of digital numeric values; the processor being adapted to process said second set of digital numeric values, and associate them to the first set of digital values.
The temperature monitoring system according any one of claims 1 to 17, wherein the reaction chamber is a hot-wall, cross flow chamber adapted for the epitaxial deposition of silicon carbide films on a substrate.
A reactor for the deposition of films on the deposition surface of a substrate comprising: - the temperature monitoring system according to any one of claims 1 to 18; - an insulating system surrounding the reaction chamber; - a heating system surrounding the insulating system; wherein the temperature monitoring device is adapted to measure the temperature of one or more points of the deposition surface of the substrate in real-time, during reactor operation.
A temperature monitoring device comprising: - at least one optical device; - at least one remote sensing thermometer comprising an IR detector; and - a supporting device adapted to support the optical device and comprising a retractable element integral with the optical device; wherein the optical device is adapted to reflect, refract, or divert the optical path of IR light from a first direction to a second direction different from the first.

Description

FIELD OF INVENTION The present invention relates to the field of temperature monitoring systems for measuring the temperature of a substrate during the deposition process in a reactor. Additionally, though not exclusively, the present invention relates to the field of epitaxial deposition of semiconductor films on substrates; in particular to a reactor implementing a temperature monitoring system. Furthermore, the present invention relates to the field of the deposition of silicon carbide and gallium nitride films on a semiconductor substrate in a hot-wall, crossflow, homoepitaxial or heteroepitaxial reactor. BACKGROUND OF THE DISCLOSURE Semiconductor layers made by epitaxial growth, also known as epilayers, are formed by epitaxial deposition in the reaction chamber of a reactor. The deposited material may be the same as the substrate or involve different semiconductors with specific desirable qualities. Epitaxial techniques allow to control the crystal structure formed over the substrate and to improve the epilayer surface features, making them suitable for manufacturing complex microprocessors and memory devices. Typically, the reaction chamber is heated to a desired temperature before deposition, and the temperature is maintained substantially constant throughout the deposition process. To this effect, insulating systems are used to reduce the energy required to achieve and maintain the nominal temperature of the deposition process. The ability to maintain a controlled temperature in time, during the deposition process, and from run to run, impacts on the quality of the film's growth. However, also other temperature-related parameters affect the deposition process. Indeed, it has been observed that local temperature variations on the deposition surface of the substrates heavily affect the quality of the deposited films. Reaction chamber type (single wafer versus batch), reaction chamber design (i.e., horizontal, or vertical flow) and substrate size may influence the overall spatial temperature profile over the substrates to be processed. Typically, the deposition surface of the substrates is subject to a temperature gradient, which may produce undesired effects, including doping inhomogeneity, growth deviations and other defects. While some reaction chamber designs known in the art (such as the single wafer, horizontal, cross-flow chamber disclosed in EP4065747) exhibit improved temperature gradients on the substrate, they do not allow to measure such gradient or to directly monitor the temperature of the deposition surface of the substrates in real-time, for optimization of process conditions/design, or to follow run-to-run changes. In general, the constraints imposed by the reaction chamber design, its high operating temperature and the presence of corrosive process gases, make it difficult to accurately measure the temperature of the substrates in real time, on one or more points of their deposition surface. For instance, in case of epitaxial reactors for the deposition of silicon carbide, the temperature within the cavity of the chamber lies in the 1400 - 1750°C range, and the growth of parasitic SiC build up on chamber parts exposed to the process gases adds a further layer of complexity, as deposits may obstruct any smaller holes manufactured on the walls of the chamber, to allow remote sensing thermometers to directly point at the substrates. Larger holes may on the other hand affect the temperature profile within the reaction chamber. It is therefore desirable to provide a device and system adapted to measure the temperature of the deposition surface of a substrate, in-situ and during deposition, especially in case of a hot wall reactor for the deposition of silicon carbide. SUMMARY OF THE DISCLOSURE This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. It is an object of the present invention to overcome the disadvantages of the prior art. In particular, it is an object of the present invention to provide a temperature monitoring device and a temperature monitoring system incorporating said device, adapted to measure the temperature of one or more points of the deposition surface of a substrate in a reactor, during the deposition process. It is a further object of the present invention to provide a reactor for the deposition of silicon carbide provided with the above temperature monitoring device and/or temperature monitoring system. The main objectives hereinbefore described are achieved through the invention recited in the appended claims, which constitute an integral part of the present description. It is noted that the use of reference signs in the claims, i