Pressure-controlled device for heating solid precursors

Abstract

Pressure-controlled heating device for solid precursors, comprising: a steel cylinder having a bottom plate and a peripheral wall, the bottom plate and the peripheral wall defining an interior space; a plurality of vertically stacked trays provided in the interior in a separable manner, each tray having a receiving space, a support plate, an annular side, and a circular ring; wherein in each tray, the receiving space is defined between the support plate, the annular side, and the circular ring, the support plate is connected to a lower portion of the annular side and is configured to support a solid precursor, the circular ring is connected to an upper portion of the annular side, and the annular side is in close contact with the peripheral wall; wherein the lowermost of the trays is defined as a bottom tray, and the support plate of the bottom tray has no hollow portion; and wherein the support plate of each tray except the bottom tray rests on the circular ring of an immediately underlying tray; a buffer tank having a buffer space, the buffer space being in fluid communication with the interior; a pressure gauge provided on the buffer tank and configured to detect a vapor pressure in the buffer space; and an induction heater in signal communication with the pressure gauge, the induction heater being configured to heat the steel cylinder by induction heating in accordance with the steam pressure detected by the pressure gauge.

Description

BACKGROUND OF THE INVENTION 1. Technical field

[0001] The present invention relates to a heating device for use in the production of a chemical reagent in the vapor phase. 2. Description of the state of the art

[0002] Vapor-phase reagents are used in vapor-utilizing processes in semiconductor manufacturing and other similar industrial applications. These vapor-phase reagents are produced by heating and ultimately sublimating their respective solid precursors in a heating device.

[0003] A conventional heating device for such a solid precursor works as follows. The steel cylinder of the heating device is heated with an external heat source and transfers the absorbed heat to the solid precursor inside the steel cylinder to sublimate the solid precursor. A temperature sensor is mounted outside the steel cylinder to measure the external temperature of the steel cylinder, and the measured temperature is used to control the heating process of the external heat source. The problem with the above prior art is that there is a difference between the temperatures inside and outside the steel cylinder. In other words, the external temperature detected by the temperature sensing element is not an accurate indicator of the internal temperature of the steel cylinder.Controlling the heating process of the external heat source according to the outside temperature tends to lead to a control delay, which makes the sublimation pressure of the solid precursor unstable. BRIEF SUMMARY OF THE INVENTION

[0004] The main object of the present invention is to provide a heating device for solid precursors which can stably control the vapor pressure of the solid precursor.

[0005] To achieve the above and other objects, the present invention provides a pressure-controlled heating apparatus for solid precursors, comprising a steel cylinder, a plurality of vertically stacked trays, a buffer tank, a pressure gauge, and an induction heater. The steel cylinder has a bottom plate and a peripheral wall, the bottom plate and the peripheral wall defining an interior space. The trays are provided in the interior space in a separable manner.Each tray has a receiving space, a support plate, an annular side, and a circular ring, wherein: the receiving space is defined between the support plate, the annular side, and the circular ring; the support plate is connected to a lower portion of the annular side and configured to support a solid precursor; the circular ring is connected to an upper portion of the annular side; and the annular side is in close contact with the peripheral wall. The lowest of the trays is defined as the bottom tray, and the support plate of the bottom tray has no hollow portion. The support plate of each tray except the bottom tray rests on the circular ring of the immediately underlying tray. The buffer vessel has a buffer space, and the buffer space is in fluid communication with the interior.The pressure gauge is located on the buffer tank and is designed to measure the steam pressure in the buffer chamber. The induction heater is connected to the pressure gauge and is designed to heat the steel cylinder by induction heating according to the steam pressure measured by the pressure gauge.

[0006] The present invention is advantageous because by monitoring the vapor pressure in the buffer space and performing feedback control on the induction heater, the vapor pressure in the buffer vessel can be maintained within a preset range, thereby reducing pressure fluctuations of the resulting chemical vapor phase reagent when the chemical vapor phase reagent is subsequently fed to a vapor-using process. BRIEF DESCRIPTION OF THE DIFFERENT VIEWS OF THE DRAWINGS Fig. 1 is a schematic drawing of an embodiment of the present invention. Fig. 2 is a perspective view of some of the components of the Fig. 1 shown embodiment. Fig. 3 is an exploded view of some of the components of the Fig. 1 shown embodiment. Fig. 4 is a sectional view of some of the components of the Fig. 1 shown embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] With reference to the Fig. 1 to 4, which show an embodiment of the pressure-controlled solid precursor heating apparatus of the present invention, the solid precursor heating apparatus comprises a steel cylinder 10, a plurality of vertically stacked trays 20a, 20b and 20c, a buffer tank 30, a pressure gauge 40 and an induction heater 50.

[0008] The steel cylinder 10 includes a bottom plate 11, a peripheral wall 12, and a lid 13. The bottom plate 11 and the peripheral wall 12 define an interior space 14. The lid 13 is provided on an upper portion of the peripheral wall 12 in a detachable manner. The steel cylinder 10 may further include a plurality of locking elements 15 for locking the cover 13 to the upper portion of the peripheral wall 12. In addition, the steel cylinder 10 includes a vapor outlet pipe 16 provided on the cover 13, which communicates with the interior space 14 and is configured to discharge a vaporized chemical reagent. In one possible embodiment, the steel cylinder 10 is made of stainless steel, and the magnetic permeability of the steel cylinder 10 (particularly the peripheral wall 12) is preferably higher than 1 H / m, for example, in the range of 1.04 to 1.05 H / m.In one possible embodiment, the stainless steel used may contain the following components: not more than 1 wt% nickel (Ni), 17-20 wt% chromium (Cr), 1.75-2.5 wt% molybdenum (Mo), not more than 0.025 wt% carbon (C), not more than 0.035 wt% nitrogen (N), a total of about 0.8 wt% titanium (Ti) and niobium (Nb), and the remainder iron (Fe). Preferably, the nickel content is not more than 0.6 wt%, the chromium content is 17.5-19.5 wt%, and the nitrogen content is not more than 0.025 wt%. A stainless steel with the above composition has good thermal conductivity and can be efficiently heated by induction heating.

[0009] The shells 20a, 20b, and 20c are provided in the interior space 14 in a separable manner. Each shell 20a / 20b / 20c has a receiving space 21, a support plate 22, an annular side 23, and a circular ring 24, wherein the receiving space 21 is defined between the support plate 22, the annular side 23, and the circular ring 24; the support plate 22 is connected to a lower portion of the annular side 23 and is configured to support a solid precursor (e.g., a tungsten or molybdenum precursor) that can be heated and thereby vaporized into a chemical vapor phase reagent; the circular ring 24 is connected to an upper portion of the annular side 23; and the annular side 23 is in close contact with the peripheral wall 12 so that the heat of the steel cylinder 10 can be conducted to the shells.The lowest of the shells is defined as the bottom shell 20c, and the support plate 22 of the bottom shell 20c has no hollow portion. For the shells other than the bottom shell 20c (i.e., shells 20a and 20b), each support plate 22 rests on the circular ring 24 of the shell immediately below. The uppermost of the shells is defined as the upper shell 20a, and the support plate 22 of the upper shell 20a has a central hollow portion. Between the lower shell 20c and the upper shell 20a is at least one shell, defined as the middle shell 20b (in this embodiment, there are multiple middle shells 20b). In the center of the support plate 22 of each middle tray 20b there is provided a vertical cylindrical member 25 which is open at both the upper end and the lower end, and an inner circular ring 26 which extends radially outward from the upper end of the vertical cylindrical member 25.The height of the vertical cylindrical element 25 of each central container 20b is less than the height of the annular side 23 of the central container 20b, so that a chemical reagent in the vapor phase can be discharged through the passage formed by the vertical cylindrical elements 25 and then through the vapor outlet pipe 16.

[0010] The buffer tank 30 has a buffer space 31. The buffer space 31 is fluidly connected to the interior space 14 so that a chemical reagent in the vapor phase can be supplied from the interior space 14 into the buffer space 31. The pressure gauge 40 is provided on the buffer tank 30 and configured to detect the vapor pressure in the buffer space 31. The induction heater 50 is in signal communication with the pressure gauge 40 and is configured to heat the steel cylinder 10 through an induction heating process according to the vapor pressure detected by the pressure gauge 40. More specifically, when the measured vapor pressure is lower than the required vapor pressure range, the induction heater 50 is either started to heat the steel cylinder 10 directly or increases its heating power.This indirectly heats the solid feedstock in the steel cylinder 10, generating more vapor-phase chemical reagent that can be supplied, for example, to a steam-using process. If the measured vapor pressure is higher than the required vapor pressure range, the induction heater 50 is either turned off or its heating power is reduced, thereby reducing the heat supplied to the steel cylinder 10 and thus the production of the vapor-phase chemical reagent to be supplied to the steam-using process. The supply pressure of the vapor-phase chemical reagent can therefore be kept more stable than with the prior art, and this solves the problem of control delay typical of the prior art. Furthermore, the induction heating method used in the present invention has higher energy efficiency than the conventional method of heating a steel cylinder by conduction.

[0011] A pressure-controlled heating device for solid precursors comprises a steel cylinder, a plurality of trays, a buffer vessel, a pressure gauge, and an induction heater. The steel cylinder has a bottom plate and a peripheral wall that together define an interior space. The trays are vertically and separably stacked within the interior space and each have a receiving space, a support plate, an annular side, and an annulus, the receiving space being defined between the support plate, the annular side, and the annulus. The buffer vessel has a buffer space that is in fluid communication with the interior space. The pressure gauge is attached to the buffer vessel and measures the vapor pressure in the buffer space. The induction heater is in signal communication with the pressure gauge and heats the steel cylinder by induction heating according to the vapor pressure measured by the pressure gauge.

Claims

[1] Pressure-controlled heating device for solid precursors, comprising: a steel cylinder having a bottom plate and a peripheral wall, the bottom plate and the peripheral wall defining an interior space; a plurality of vertically stacked trays provided in the interior in a separable manner, each tray having a receiving space, a support plate, an annular side, and a circular ring; wherein in each tray, the receiving space is defined between the support plate, the annular side, and the circular ring, the support plate is connected to a lower portion of the annular side and is configured to support a solid precursor, the circular ring is connected to an upper portion of the annular side, and the annular side is in close contact with the peripheral wall; wherein the lowermost of the trays is defined as a bottom tray, and the support plate of the bottom tray has no hollow portion; and wherein the support plate of each tray except the bottom tray rests on the circular ring of an immediately underlying tray; a buffer tank having a buffer space, the buffer space being in fluid communication with the interior; a pressure gauge provided on the buffer tank and configured to detect a vapor pressure in the buffer space; and an induction heater in signal communication with the pressure gauge, the induction heater being configured to heat the steel cylinder by induction heating in accordance with the steam pressure detected by the pressure gauge. [2] The pressure-controlled heating apparatus for solid precursors according to claim 1, wherein the steel cylinder further comprises a cover provided on an upper portion of the peripheral wall in a separable manner. [3] The pressure-controlled heating device for solid precursors according to claim 1, wherein the uppermost one of the shells is defined as an upper shell and the support plate of the upper shell has a central hollow portion. [4] A pressure-controlled heating device for solid precursors according to claim 3, wherein at least one tray is located between the lower and upper trays, the at least one tray being defined as the middle tray, the support plate of the middle tray being centrally provided with a vertical cylindrical member and an inner circular ring, the vertical cylindrical member having an open upper end and an open lower end, the inner circular ring extending radially outward from the upper end of the vertical cylindrical member, and the vertical cylindrical member of the middle tray having a height less than the height of the annular side of the middle tray.

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