WO2019076609A1

WO2019076609A1 - Heatable gas injector

Info

Publication number: WO2019076609A1
Application number: PCT/EP2018/076441
Authority: WO
Inventors: Lotta Gaab; Wolfgang Stang; Christoph STERNKIKER; Thomas Piela; Jürgen Weber; Christian PELS; Larisa Von Riewel
Original assignee: Heraeus Noblelight Gmbh
Priority date: 2017-10-19
Filing date: 2018-09-28
Publication date: 2019-04-25
Also published as: DE102017124456A1

Abstract

Known gas injectors have a gas distributor element having a wall, which extends through a plurality of openings in order to supply process gas. In order to provide a heatable gas injector proceeding therefrom, having a simple design and ensuring homogeneous heating of the substrate, according to the invention the gas distributor element wall has a surface made of a dielectric, black heating material, which emits infrared radiation during heating, and a heating conductor track made of an electrically conductive resistance material is applied to the wall.

Description

Heatable gas injector

description

Technical background

The invention relates to a heatable Gasinjektor, with a gas distribution element having a wall through which a plurality of openings for the supply and / or discharge of process gas extends.

Such gas injectors are used, for example, in reactors for CVD deposition processes and dry etching processes for producing electronic components in semiconductor production or in the production of liquid crystal displays (LCDs). In this process, layers and layered patterns and structures are produced on substrates by ablation of material or by deposition from the gas phase. CVD deposition processes are also used to create surface layers with specific mechanical-tribological (wear-resistant, friction-reducing, hard, gas-impermeable), optical (reflective, antireflecting) or chemical (water-repellent) properties. The processing of each substrate requires at least one process step, but generally several process steps, in which process gases act on the substrate surface in a reactor chamber.

For drying or for crosslinking paints or varnish-like coatings or printed products as well as for laminating plastic films on various carrier materials, radiation dryers and drying systems are used in which heated process gas is applied to the material to be treated and generally removed therefrom.

State of the art

In reactors for CVD deposition processes and dry etching processes with and without plasma assist, process gases are often supplied to the reactor chamber through one or more gas injectors equipped, for example, with tubular or plate-shaped gas distribution elements. Tubular gasin The tubular gas distribution element runs along a vertical substrate stack (for example, a wafer stack) and has at least one gas outlet opening at the level of each substrate.Plate-type gas injectors are also used in batch processes but also in so-called batch processes Single-wafer processes. The gas distribution element here is in the form of a planar gas distributor plate (showerhead) which is arranged parallel to the processing wafer surface and which is provided with a multiplicity of gas nozzles directed onto the wafer surface.

A reactor for the batch processing of wafers with a gas injector with a tubular gas distribution element is described, for example, in US Pat. No. 9,017,763 B2. The gas distribution element has a hole structure, in which in each case one or more holes are assigned to the gap of adjacent wafers of the wafer stack. The center of each hole structure is arranged above the wafer surface at a height which is above half the wafer-wafer distance.

EP 0 844 314 B1 discloses a gas injector for the single-wafer process with a gas distribution plate of circular cross-section. The gas distribution plate is perforated with a plurality of gas nozzles that run along concentric circles. By mechanical separations, the gas nozzles are divided into several coaxial gas distribution zones. Each of the gas distribution zones is equipped with its own gas supply line and a mass flow controller, so that the gas quantities flowing out into the reactor chamber and the flow rates can be adjusted independently of each other.

US 2010/0300359 A1 describes a gas injector with a circular gas distributor plate for the batch processing of several wafers. The gas injector is composed of a front plate, an intermediate plate and a back plate, which are gas-tight soldered together. The front panel is perforated and forms the actual gas distribution element. The intermediate plate is structured so that it forms gas chambers and cooling channels. The back plate covers the gas chambers and Cooling channels gas-tight and is connected to several connecting pieces for the supply of process media.

In principle, the problem arises of making the treatment of the substrate as uniform and reproducible as possible in each process step. The running processes are largely determined by temperature and mass transport processes, so that temperature homogeneity and distribution of the process gases are the subject of constant further development. In particular, the temperature prevailing at the substrate has a decisive influence on the properties of the deposited film. In order to counteract changes in the temperature in the course of the deposition process or to be able to set a specific process temperature in a targeted manner, the reactor chamber is generally equipped with tempering elements.

In the above-mentioned US 2010/0300359 A1, these are, for example, the mentioned cooling channels in the gas injector itself and an inductively heatable heating element which is arranged within the reactor chamber below a rotatable substrate holder. However, this type of heating does not give a sufficiently homogeneous temperature distribution, especially for large-area substrates. For example, glass substrates with lateral dimensions of up to 165 cm (65 inches) must be homogeneously coated in display production.

An improvement in this respect results from a heatable gas injector according to the aforementioned type, as it is known from US 2016/0056032 A1. In the reactor described therein for an ALD deposition process (atomic layer deposition), heating or cooling elements are themselves mounted in the gas injector. The gas injector consists of a nozzle for the process media supply, a back plate and a perforated front plate provided with gas nozzles. The heating element is a resistance heater soldered into the back plate. The front panel forms the actual gas distribution element; It is made of aluminum or another tempera- ture- and plasma-resistant metal.

Drying devices for drying the printed substrate are thus used to remove solvents and / or to trigger crosslinking reactions. tions. DE 10 2010 046 756 A1 describes a selective dryer for printing machines for printing on sheet or roll material. The selective dryer consists of several arranged transversely to the transport direction dryer modules, each of which has an aligned on the substrate to be dried infrared radiator whose longitudinal axis is perpendicular to the transport direction of the printing material. By means of an adjustable ventilation system, an air flow is generated, which acts on the infrared radiator and on the substrate. The supply air is heated by means of a separate heating device and supplied to both sides of the infrared radiator gas outlet nozzles in the form of slit nozzles the substrate. The front in the transport direction for the substrate slit nozzle extends obliquely to the substrate level with an orientation opposite to the transport direction, and the rear in the transport direction slit also extends obliquely to the substrate level with an orientation in the transport direction. The degree of inclination of the slot nozzles is motor-changeable. By means of a fan arranged centrally above the infrared radiator, the infrared radiator is cooled and the waste heat is added to the heated supply air. The exhaust air is discharged via a suction channel and a heat exchanger.

Technical task

In the case of the heatable gas distribution element known from US 2016/0056032 A1, the current-carrying resistance heating element heats the back plate and the perforated front plate, and these components transfer their heat to the process gas flowing through by heat conduction. The heated process gas flowing out of the gas distribution element acts on the substrate in the reactor chamber and simultaneously tempers it.

In the dryer module known from DE 10 2010 046 756 A1, the heating of the printing substrate takes place on the basis of an infrared radiator arranged centrally with respect to the slot nozzles. The heated by the heater process gas exits via slot nozzles in the direction of the substrate and thereby acts on the substrate to be dried locally; Slot nozzles are structurally relatively complex. The invention aims to provide a structurally simple heatable gas injector, which ensures a homogeneous heating of the substrate.

General description of the invention

This object is achieved on the basis of a gas injector of the type mentioned in the present invention, that the Gasverteilelement wall has a surface of a dielectric, black and emanating upon heating infrared radiation heating material, and that on the wall a Heizleiterbahn is applied from an electrically conductive resistance material.

The gas injector according to the invention can be composed of several components, one of which is the gas distribution element. In the simplest case, the gas injector according to the invention consists only of the gas distribution element.

The gas distribution element consists at least partially of the dielectric, black heating material. This is electrically non-conductive and therefore not easily heated by direct current flow, but by heat conduction through the conductor of the heating element. The heating conductor serves to heat the heating material, which emits infrared radiation due to the heating in the direction of the substrate to be processed. The surface of the black heating material which faces the substrate and emits infrared radiation serves to heat the substrate and is also referred to below as "heating surface" or "emitting surface".

The openings in the wall of the gas distribution element are comparatively easy to produce; for example, by the usual thermal, mechanical and / or chemical removal techniques; In the simplest case, the openings are produced by laser drilling or mechanical drilling. They serve to deliver the heated process gas in the direction of the substrate. Depending on the application, the number, shape, size, distribution and direction can be selected such that a distribution which is as homogeneous as possible or corresponding to a desired flow pattern results on the substrate. In the case of the gas injector according to the invention, the gas distribution element therefore not only effects a homogeneous or targeted distribution of the process gas in the reactor chamber, but at the same time it also serves as a heating element emitting infrared radiation for heating the substrate. The substrate to be processed is thus heated in the reactor chamber not only by heat conduction and convection due to the process gas, but also due to the heat radiation emitted by the gas distribution element. The additional heat radiation can contribute to a higher homogeneity of the temperature profile on the substrate, in particular if the emission surface is larger than the substrate surface to be processed.

The gas distribution element may be formed from a plurality of materials, but it is preferably made entirely from the dielectric, black heating material. It is essential that the occupied with the Heizleiterbahn surface area - hereinafter also referred to as "contact surface" - consists of electrically insulating material to reliably prevent flashovers and short circuits between adjacent conductor track sections.

The surface facing the substrate and emitting infrared radiation heating surface and occupied with Heizleiterbahn contact surface preferably do not match, but they are in the simplest case on the Gasverteilelement- wall opposite.

The heating surface may have a structure and a surface geometry deviating from the flatness; For example, it may form the inner or outer cylindrical surface of a tubular Gasverteilelements. However, a flat and planar heating surface is preferred, because it has the advantage that it generates an equally planar radiation field, so that even at a short distance from the substrate results in a planar temperature profile on the substrate surface.

The resistance material of the heating conductor is preferably resistant to at least 1000 ° C temperature, ideally in oxidative environment. Advantageously, its electrical conductivity does not change significantly with temperature, or the change in resistance is known. These conditions are fulfilled in particular: (1) Of precious metal-containing resistance material. The preferred resistance material in this regard is at least 50 at%, preferably at least 95 at%, of platinum group elements. The platinum group includes the following precious metals: Ru, Rh, Pd, Os, Ir, Pt. These are present in pure form or as an alloy with one another or with one or more other metals, in particular with Au, Ag.

(2) High-temperature-resistant steel, tantalum, ferritic FeCrAI alloy, austenitic CrFeNi alloy, silicon carbide, molybdenum disilicide or molybdenum-based alloy. These materials, in particular silicon carbide (SiC), molybdenum disilicide (M0S12), tantalum (Ta), high-temperature steel or a ferritic FeCrAl alloy such as Kanthai ^®

(Kanthai ^® is a registered trademark of SANDVIK INTELLECTUAL

PROPERTY AB, 811 81 Sandviken, SE) are oxidation resistant in air and less expensive than platinum group metals.

The heating conductor is preferably produced as a thick-film layer, for example, from resistance paste by means of screen printing or from metal-containing ink by means of inkjet printing and then baked at high temperature. The conductor runs on the contacting surface, for example in a spiral or meandering line pattern.

The absorption capacity of the black heating material allows a homogenous radiation even with comparatively low track occupancy density of the contacting surface. A low occupation density is characterized in that the minimum distance between adjacent conductor track sections is 1 mm or more, preferably 2 mm or more. A large distance between the conductor sections avoids flashovers, which can occur especially when operating at high voltages under vacuum.

The heating conductor can be covered at least partially, preferably completely, with a layer of an electrically insulating and / or optically scattering material. This layer can serve as a reflector and / or for mechanical protection and stabilization of the heating conductor and it reduces the risk of electrical flashovers between adjacent Heizleiterbahn- Sections. The electrically insulating and / or optically scattering material is preferably opaque quartz glass.

The Heizleiterbahn is connected to an electrical contact, via which it is connectable to a circuit. Preferably, the electrical contact is detachably connectable to a circuit, for example via a plug, screw or clamp connection.

In particular with regard to a potentially corrosive effect of process gases, it is advantageous if the heating conductor track is applied in a region of the gas distribution element wall sealed by the process gas.

In this case, the wall of the gas distribution element is constructed, for example, of at least two layers, wherein the contacting surface extends between the layers and is sealed by the openings for the process gas supply. The contacting surface may extend, for example, in a space sealed by means of sealing elements. However, a particularly effective sealing of the contacting surface is achieved in that the heating conductor track is completely covered by a glaze layer, at least in the region of contact with the process gas. The glaze layer forms a layer of the gas distribution element in the case.

In a particularly preferred embodiment of the gas injector according to the invention, the heating material is a particle material which comprises an amorphous matrix component and an additional component in the form of a semiconductor material.

The amorphous material, such as quartz glass, can be easily brought to the appropriate for the application geometric shape, for example in the form of a flat, a curved or a corrugated plate or in the form of a tube with a round, oval, rectangular or polygonal cross-section. The incorporated therein additional component forms its own amorphous or crystalline phase of semiconductor material, such as silicon. The energy difference between valence band and conduction band (bandgap energy) decreases with increasing temperature. On the other hand, with sufficiently high activation energy, electrons can be lifted from the valence band into the conduction band, which associated with a significant increase in the absorption coefficient. The thermally activated occupation of the conduction band results in the semiconductor material being able to be somewhat transparent at room temperature for certain wavelengths (such as from 1000 nm) and becoming opaque at high temperatures. As the temperature of the heating material rises, therefore, the absorption and emissivity can increase suddenly. This effect depends, among other things, on the doping of the semiconductor. Pure silicon shows, for example, from about 600 ° C, a significant increase in emissions, which reaches about from about 1000 ° C saturation.

Therefore, if the semiconductor material is sufficiently heated, it can take a high-energy, excited state in which it emits infrared radiation of high power density. In this state, the semiconductive additional component significantly determines the optical and thermal properties of the heating element; more precisely, it causes absorption in the infrared spectral range (that is, in the wavelength range between 780 nm and 1000 pm).

The gas distribution element according to the invention is therefore preferably designed for a heating temperature of at least 600 ° C.

The heating temperature is the surface temperature of the gas distribution element. With such a gas distribution element power densities above 100 kW / m ² , preferably power densities in the range of 100 kW / m ² to 200 kW / m ² , can be achieved. The surface power is defined as the electrical connection power of the heating conductor in relation to the contact surface occupied by the heating conductor.

Such a heating material thus shows an excitation temperature, which must at least be achieved in order to obtain the thermal excitation of the material and thus a high radiation emission. The additional component then causes the heating material to emit infrared radiation. The spectral emissivity ελ can be calculated with known directional-hemispherical spectral reflectance Rgh and transmittance Tgh as follows: ελ = 1 -Rgh-Tgh (1) The "spectral emissivity" is understood to mean the "spectral normal emissivity". This is determined using a measurement principle known as "Black-Body Boundary Conditions" (BBC) published in "DETERMINING THE TRANSMITTANCE AND EMITTANCE OF

TRANSPARENT AND SEMITRANSPARENT MATERIALS AT ELEVATED TEMPERATURES ", J. Manara, M. Keller, D. Kraus, M. Arduini-Schuster, 5th European Thermal-Sciences Conference, The Netherlands (2008).

The doped with the additional component matrix has a higher heat radiation absorption than would be the case without the additional component. This results in improved heat conduction increased proportion of energy transfer by radiation from the Heizleiterbahn in the Gasverteilelement, a faster distribution of heat and a higher radiation rate to the substrate. This makes it possible to provide a higher radiation power per unit area and to produce a homogeneous radiation and a uniform temperature field even with a thin Gasverteilelement wall and / or at a relatively low trace occupancy density.

In the heating material, the additional component is preferably present at least in part as elemental silicon and is incorporated in an amount which in the heating material for wavelengths between 2 and 8 pm a spectral emissivity ε of at least 0.6 at a temperature of 600 ° C and a spectral Emissivity ε of at least 0.75 at a temperature of 1000 ° C causes.

The semiconductor material and in particular the preferably used, elemental silicon cause the blackening of the glassy matrix material and that at room temperature, but also at elevated temperature above, for example, 600 ° C. This achieves a good emission characteristic in the sense of a broadband, high emission at high temperatures. The semiconductor material forms an elementary semiconductor phase dispersed in the matrix. This may contain a plurality of semiconductor elements or metals (metals, however, up to a maximum of 50% by weight, better still not more than 20% by weight, based on the weight fraction of the additional component). The heat absorption of the heating material depends on the proportion of the additional component. In the case of silicon, the proportion by weight should preferably be at least 0.1%. On the other hand, a high proportion of silicon can impair the chemical and mechanical properties of the quartz glass matrix. In view of this, the proportion by weight of the weight fraction of the silicon additional component is preferably in the range between 0, 1 and 5%.

In a preferred embodiment of the gas injector at least a portion of the openings is formed as holes with a round cross-section. Holes with a round cross section are easy to produce, for example by mechanical drilling or by thermal drilling by means of a laser beam.

In a further preferred embodiment of the gas injector at least a part of the openings is formed as a slot. The slot or a plurality of slots extend, for example, in a straight extension, as a juxtaposition of curved separate slots or contiguously in meandering form; They are easy to introduce in Gasverteilelement, for example by mechanical milling or by thermal milling by means of laser beam.

In a further preferred embodiment of the gas injector, at least a part of the openings is in each case surrounded by a gas guide nozzle which protrudes from the wall on one or both sides.

The gas guide port extends perpendicularly or at an angle between 0 and 90 degrees from one side or both sides of the Gasverteilelement- wall away. In the simplest case, it has the same opening cross section as the opening in the wall of the gas distribution element. However, it can also vary over the length of the gas guide neck, for example, the opening cross-section can taper or widen. An advantage of this embodiment is that the inlet opening for the process gas into the gas guide nozzle and / or the outlet opening for the process gas can be displaced from the gas guide nozzle in a region or in a space which is remote from the actual opening in the gas distribution element. For example, the outlet opening for the process gas may be displaced in the direction of the substrate to be treated, or the inlet opening may terminate in a chamber which differs from the one to be treated Gasverteilelementwandung removed or is fluidly completed by this. The additional one- or two-sided gas guide port may be provided at all wall openings or at a portion of the wall openings He may be structurally the same in all wall openings; However, the gas guide can also differ in their construction and orientation from each other.

In view of this, in a particularly preferred embodiment of the invention, there is provided a first group of gas guide nozzles extending into a first chamber and a second group of gas guide nozzles extending into a second chamber.

The gas guide can stand on one and the same wall side but have different lengths. The first chamber and the second chamber may differ, for example, in the gas internal pressure applied in each case. The first chamber may be, for example, a space into which process gas is introduced, and the second chamber may be a space from which process gas is extracted, optionally the first group of gas guide nozzles serves as a process gas supply, and the second group of gas guide nozzles serves for process gas discharge.

This embodiment of the gas injector according to the invention can be used particularly advantageously in a dryer system in which dry process air is supplied to a substrate to be dried and the moisture-laden process air is withdrawn again, as for example in a printing press. The gas distribution element serves as an infrared radiator for heating the process air and the substrate.

In a particularly suitable embodiment of the gas injector according to the invention, the gas distribution element is part of an infrared dryer system for a printing press and for the supply of drying gas in a treatment chamber for a substrate to be dried and / or for the discharge of drying gas from the treatment chamber is designed. In another equally suitable embodiment of the gas injector according to the invention, the gas distribution element is part of a reactor for a dry etching or a CVD deposition process and designed for the supply of process gas into a reactor interior.

Working Example

The invention will be explained in more detail with reference to an embodiment and a drawing. In the drawing shows in a schematic representation in detail:

1 shows a device for sputtering and for etching individual wafers using a gas injector according to the invention in a cross-sectional view,

FIG. 2 shows an embodiment of a heatable gas distributor plate for use in the device of FIG. 1 in a plan view of the underside facing the wafer,

FIG. 3 shows the gas distributor plate of FIG. 2 in a plan view of the upper side facing away from the wafer;

FIG. 4 shows a further embodiment of a heatable gas distributor plate with slot-shaped gas outlet nozzles,

Figure 5 shows another embodiment of a heated gas distribution plate with

Gas outlet nozzles, which are provided with pipe sockets,

6 shows a printing machine using a gas injector according to the invention, and

FIG. 7 shows an embodiment of a dryer unit for use in the printing press of FIG. 6 with a further embodiment of a heatable gas distributor plate.

FIG. 1 schematically shows a typical plasma reactor 1 used for dry etching and coating processes for single wafers 2. The reactor 1 has a housing 3, which encloses a plasma reactor chamber 4. The upper end of the housing 3 is formed by a dielectric window 6, which is designed substantially as a round plate with a diameter of 520 mm and a plate thickness of 40 mm. From its upper side is an upper, coil-shaped electrode 5.

The dielectric window 6 has a center bore for receiving an injector 20, into which open one or more gas supply lines for process gases. Process gas is fed into a gastight gas distribution chamber 9 via the injector 20. This is formed by the dielectric window 6 and a mounted on the underside gas distribution plate 7 (showerhead).

The gas distribution plate 7 is located above the wafer 2 to be treated within the plasma reactor chamber 4 and is provided with a plurality of gas nozzles 8a, 8b, 8c and 8d (see FIG. 2) arranged in groups on concentric circles about the center axis 17 and extending as through holes between the gas distribution chamber 9 and the underside of the gas distribution plate 7. At its upper side, the gas distributor plate 7 has a circumferential raised edge 18 (see FIG. 3), which bears tightly against the dielectric window 6 and closes off the gas distributor chamber 9 to the outside. In addition, the top of the gas distribution plate 7 is provided with a heating conductor 30, which will be explained in more detail with reference to FIG 3. The gas distributor plate 7 consists of a black composite material at room temperature (20 ° C.), in which a phase of elemental silicon in the form of non-spherical regions is homogeneously distributed in a matrix of quartz glass. This composite material will be described in more detail below.

In order to provide a low pressure suitable for plasma processing, the reactor chamber 1 is evacuatable via a gas outlet 1200 connected to a high vacuum pump (not shown). By exciting the upper electrode 5 by means of a high-frequency energy source 11 (13.56 MHz), energy can be capacitively coupled into a plasma 12 ignited within the reactor chamber 4. Another RF power source 13 is connected to a lower electrode 14 which is positioned below the wafer 2 to be processed. The Wafer 2 is fixed on a holding device 14 and surrounded by an etching ring 15 for homogenization of the plasma action.

During operation of the plasma reactor 1, the gas distributor plate 7 is heated to temperatures above 600 ° C. by means of the heat-conducting track 30 through which current flows. The silicon-containing composite material branches at the high temperatures a pronounced absorption of heat radiation and a high emissivity. This depends on the temperature. At 600 °, the normal emissivity in the wavelength range from 2 pm to 4 pm is above 0.6. At 1000 ° C, the normal emissivity in the same wavelength range is above 0.75. The process gas introduced into the gas distributor space is thereby preheated and, on the other hand, the substrate is homogeneously heated by homogeneous, surface heat radiation of the gas distributor plate 7.

The plan view of the wafer 2 facing, planar bottom of the gas distribution plate 7 in Figure 2 shows the circular shape. Its diameter is 450 mm and the plate thickness 7 mm. The gas nozzles 8a, 8b, 8c and 8d are arranged in groups on concentric circles about the central axis 17, wherein the gas nozzle groups differ from each other in their size, shape and / or orientation. They are suitable for generating gas flows of different strength and direction, as indicated by the directional arrows 16. They are produced by laser drilling and are characterized by high accuracy.

For example, the gas nozzles 8c have an inner diameter of 0.8 mm and they form a gas nozzle density of more than 100 gas nozzles per 100 cm ² . The arranged on the same annulus gas nozzles are the same; however, they differ in size, shape or orientation from the gas nozzles on another annulus. As a result, it is possible to reproducibly set a defined non-homogeneous gas distribution over the wafer surface, which, for example, takes into account and compensates for a non-homogeneous temperature distribution so that uniform vapor deposition or removal can ultimately be achieved.

The plan view of the upper side of the gas distributor plate 7 facing away from the wafer 2 in FIG. 3 shows the above-mentioned peripheral edge 18, which is the upper edge of the gas distributor plate 7. side gives a recess in which the heating conductor 30 is received. The heating conductor 30 is designed in a spiral shape and meanders along the free surfaces around the gas nozzles 8a, 8b, 8c, 8d. At their ends, the heating conductor 30 is connected in each case with contacting regions 31 for bonding power connection wires. The diameter of the heating conductor spiral 32 is greater than the diameter of the wafer 2 to be treated.

The heating conductor 30 has a rectangular cross-section with a cross-sectional height of 20 pm and a cross-sectional width of 3 mm. The contacting regions 31 likewise have a rectangular cross-section with a cross-sectional height of 20 μm but a cross-sectional width of 6 mm. The free space between adjacent spiral sections is about 10 mm. The heating conductor 30 and the contacting areas 31 are produced in one operation and consist of platinum.

FIG. 4 schematically shows a further embodiment of a heatable gas distributor plate 47. This has a square cross section with a flat underside and a planar upper side. The edge length is 400 mm and the plate thickness is 2 mm. The gas nozzles 48 are designed as straight, parallel to each other and to the side edges extending longitudinal slots 48. The longitudinal slots 48 have a length of 300 mm and a width of 4 mm; they are produced by water jet cutting.

Between the longitudinal slots 48 meandering meandering a heating conductor 43, which is connected at its ends with contacting areas 41 for bonding power supply wires. The cross-sectional dimensions of heating conductor 43 and contacting regions 41 correspond to those of the embodiment of FIG. 3. The contacting surface is finally provided with a 1 mm thick glaze layer (not shown) of opaque quartz glass which completely covers the heating conductor 43 and leaves open the longitudinal slots 48.

Through the longitudinal slots 48 gas can be withdrawn from a treatment room and introduced into a treatment room. The heatable gas distribution plate 47 is suitable for a homogeneous heating of a substrate to be treated with simultaneous gas supply and / or gas discharge, for example at CVD coating or dry etching processes or in the drying of paints, inks and the like, for example in a printing press.

The geometric shape and the dimensions of the embodiment of the heatable gas distributor plate 57 shown schematically in FIG. 5 correspond to those of the gas distributor plate 47. The gas nozzles 58 are designed as through-holes 54 with a round cross-section. In a part of the through holes 54 quartz glass tubes 55 are welded. The through-holes 54 are generated by mechanical drilling. Their inner diameter is 5 mm and corresponds to the outer diameter of the quartz glass tubes 55. The quartz glass tubes 55 are perpendicular over a length of 58 mm from the occupied with the heating conductor 53 contact surface of the gas distribution plate 57 from above. The heating conductor 53 meanders between the gas nozzles 58 without (54) and (55) tube insert and is connected at their ends with contacting regions 51 for bonding power supply wires. The cross-sectional dimensions of heating conductor 53 and contacting regions 51 correspond to those of the embodiment of FIG. 4. Here too, the contacting surface is finally provided with a 1 mm thick glaze layer (not shown) made of opaque quartz glass which completely covers the heating conductor 53.

Through the gas nozzles 58, gas can be withdrawn from a treatment room and introduced into a treatment room. The heatable gas distributor plate 57 is also suitable for homogeneous heating of a substrate to be treated with simultaneous gas supply and / or gas discharge, for example in CVD coating or dry etching processes or in the drying of paints, inks and the like, for example in a printing press.

FIG. 6 shows schematically a printing machine in the form of a roll-type ink jet printing machine, to which reference numeral 60 as a whole is assigned. Starting from an unwinder 62, the material web 63 passes from a printing material, such as paper, to a printing unit 80. This comprises a plurality of along the web 63 successively arranged ink tenstrahldruckköpfe 81 through which water-based inks are applied to the substrate. Seen in the direction of transport 65, the web 63 passes from the printing unit 80 via a guide roller 66 then to an infrared dryer unit 70. This is equipped with a plurality of infrared heating elements 71, which are designed for drying or repelling the solvent in the web 63 and the will be explained in more detail below with reference to FIG 7.

The further transport path of the material web 63 passes through a tension roller 68, which is equipped with its own traction drive motor and via which the adjustment of the web tension takes place, to a winding roller 69.

In the infrared dryer unit 70, a plurality of heating elements 71 are combined to form a heating block, which extends over the maximum format width of the printing press 60. The individual heating elements 71 are in the heating block intermittently strung together and separated according to the dimensions and color assignment of the printing substrate controlled. The free distance between the heating surface of the heating elements 71 and the top of the material web 63 is 10 mm.

The transport speed of the material web 63 is typically set to 5 m / s. This is a comparatively high speed, which requires a high drying rate. FIG. 7 schematically shows a heating element 71 suitable for achieving this requirement for the dryer unit 70. The geometric shape and dimensions of the schematically illustrated embodiment of the heatable gas distributor plate 77 correspond to those of the gas distributor plate 57. As with the gas distributor plate 57, the gas nozzles 78 are also shown here Through holes with round cross section and an inner diameter of 5 mm. In all through holes are glued quartz glass tubes 75 with a high temperature adhesive, which extend on both sides of the gas distributor plate 77 and whose outer diameter is also 5 mm (inner diameter 3 mm). The downwardly projecting end of the quartz glass tubes 72 is directed perpendicular to the material web 63 and has a length of 50 mm, and the upper end 74 has a length of 80 mm and ends within a gas pressure chamber 76, which is supplied via a supply line 79 dry process air , as indicated by the directional arrow 80. The contact surface of the gas distributor plate 77 facing away from the material web is covered with a heating conductor 73 which meanders in a meandering manner between the gas nozzles 78 and is provided at its ends with contacting regions (not shown) to which power supply wires are bonded. The cross-sectional dimensions of heating conductor 73 and contacting regions correspond to those of the embodiment of FIG. 4. The heating conductor 73 extends in a space 81 of the drying unit 71, which has no fluidic contact with the process air 80.

During operation of the dryer unit 71, the gas distributor plate 77 is heated by current flow through the heating conductor 73 to a temperature above 600 ° C. It forms a flat temperature field, which acts homogeneously on the material web 63. At the same time, the dry process air 80 fed into the gas pressure chamber 76 passes directly through the gas nozzles 78 onto the material web 65, where it heats up on the transport through the pipe sockets 75 without coming into contact with the heating conductor 73. Via the gas outlets close to the material web 63 at the lower end 72 of the gas nozzles 78, a homogeneous distribution of the dry process air 83 on the material web 63 and effective drying is achieved.

The production of the composite material for the gas distributor plates 7, 47, 57 and 77 takes place by means of a method as described in WO 2015/067 688 A1. In this process, quartz glass grains are wet milled in deionized water to form a homogeneous base schicker with a solids content of 78%. Subsequently, a supplement in the form of silicon powder is added in an amount until a solids content of 83 wt .-% is reached. The silicon powder contains mainly non-spherical powder particles with a narrow particle size distribution whose D97 value is about 10 μm and whose fine fraction has been previously removed with particle sizes of less than 2 μm. The SäO2 particles in the homogenized slurry show a particle size distribution characterized by a Dso value of about 8 pm and by a D9o value of about 40 pm. The weight fraction of the silicon powder in the total solids content is 5%. The slurry is poured into a die casting mold of a commercial die casting machine and dewatered through a porous plastic membrane to form a porous green body. The green body has the shape and almost the dimensions of the respective gas distribution plate 7 or 47 and 57. To remove bound water, the green body is dried at about 90 ° C for 5 days in a ventilated oven.

After cooling, the resulting porous green body is mechanically processed almost to the final dimension of the produced quartz glass gas distributor plate 7 or 47, 57 and 77 and heated in a sintering furnace under air within 1 hour to a heating temperature of 1390 ° C and at this temperature for 5 hours held.

The resulting quartz glass plate consists of a gas-tight composite material with a density of 2.196 g / cm ³ , in which in a matrix of opaque

Quartz glass are separated from each other, non-spherical regions of elementary Si phase are homogeneously distributed, whose size and morphology largely correspond to those of the Si powder used. The maximum dimensions are on average (median value) in the range of about 1 pm to 10 μηι. The matrix is visually translucent to transparent. On microscopic examination it shows no open pores and possibly closed pores with maximum dimensions of on average less than 10 μm; the density calculated on the basis of the density is 0.37%. The composite material is gas-tight and stable in air up to a temperature of about 1150 ° C. In the respective gas distribution plates 7; 47, 57 and 77 gas nozzles are introduced, for example, as explained above with reference to the embodiments explained above.

The preparation of the respective Heizleiterbahn 33; 43; 53; 73 together with the associated contacting areas 31; 41; 51 is carried out in a joint operation by a platinum resistor paste by screen printing on the perforated gas distribution plate 7; 47; 57; 77 is applied. For this purpose, a fine mesh fabric is placed on the respective contacting surface, whose mesh openings in the region of the nozzle openings 8a, 8b, 8c, 8d; 48; 58 and the other places where no platinum resistor paste should be printed, are made impermeable. The platinum resistor paste consists of a sinterable platinum powder in pure form (20 to 80 wt .-%), a solvent (20 to 50 wt .-%), a plasticizer (1 to 10 wt .-%) and a binder (1 to 15% by weight), the data in parentheses for the respective component indicating preferred proportions by weight of the total mass of the paste. After printing and the removal of the tissue coated with the platinum resistor paste from the gas distribution plate 7; 47; 57, 77 obtained, wherein the coating, the later Heizleiterbahn 33; 43; 53; 73 or their contacting areas 31; 41; 51 images. By baking at a baking temperature of 1200 ° C, the finished electrically conductive components are obtained.

The heating conductor 33; 43; 53; 73 is then covered by means of an electrically insulating glaze. The glaze prevents flashovers and it serves to protect the conductor tracks 33; 43, 53; 73 against mechanical and corrosive stress. The glaze consists of a quartz glass material, which is evenly distributed when heated as a viscous glass phase and causes a gas-tight shielding. The glaze is also used as screen printing paste on top of the gas distribution element 7; 47; 57; 77 applied, so that the respective conductor track 33; 43; 53; 73 is completely embedded therein and it is sintered at a sintering temperature of 1200 ° C to the gas-tight and insulating glaze layer.

Claims

claims

1 . A heatable gas injector, comprising a gas distribution element (7, 47, 57, 77) having a wall through which a plurality of supply and / or discharge ports (8a; 8b; 8c; 8d; 48; 58; 78) Discharge of process gas extends, characterized in that the wall has a surface of a dielectric, black and emanating upon heating infrared radiation heating material, and that on the wall a Heizleiterbahn (30; 43; 53; 73) is applied from an electrically conductive resistance material.

2. Gas injector according to claim 1, characterized in that the gas distribution element (7, 47, 57, 77) is designed for a heating temperature of at least 600 ° C.

3. Gas injector according to claim 1 or 2, characterized in that the heating conductor (73) is applied in a sealed by the process gas region of the gas distribution element wall.

4. Gas injector according to one of the preceding claims, characterized in that the heating material is a composite material containing an amorphous matrix component and silicon as an additional component with a weight fraction which is at least 0.1% and which preferably in the range between 0.1 and 5 % lies.

5. Gas injector according to one of the preceding claims, characterized in that the heating conductor track (30; 43; 53; 73) is covered by a layer of an electrically insulating and / or optically scattering material.

6. Gas injector according to one of the preceding claims, characterized in that at least a part of the openings (8a; 8b; 8c; 8d; 58; 78) are designed as bores with a round cross-section.

7. Gas injector according to one of the preceding claims, characterized in that at least a part of the openings (48) is formed as a slot.

8. Gas injector according to one of the preceding claims, characterized in that at least a part of the openings (58; 78) in each case by a gas guide nozzle (55; 75) is surrounded, which protrudes on one side or on both sides of the wall.

9. Gas injector according to claim 7, characterized in that a first group of gas guide pipe is provided, which extend into a first chamber, and that a second group of gas guide nozzles is provided, which extend into a second chamber.

10. Gas injector according to one of the preceding claims, characterized in that the gas distribution element (47, 57, 77) is part of an infrared dryer system (70) for a printing press (60) and for the supply of drying gas (83) in a treatment chamber for a substrate to be dried (63) and / or for the discharge of drying gas (83) is designed from the treatment chamber.

1 1. Gas injector according to one of claims 1 to 9, characterized in that the gas distribution element (7, 47, 57) is part of a reactor (1) for a dry etching or a CVD deposition process and for the supply of process gas into a reactor interior ( 4) is designed.