FR2957938A1 - Injector for injecting gas in treatment chamber, comprises inlet for receiving gas wave or gas pulse, curved section for dilating the gas in a direction perpendicular to propagation axis of gas, and outlet for ejecting the gas - Google Patents

Abstract

The injector (11) comprises an inlet for receiving a gas wave or a gas pulse, a curved section (20) for dilating the gas in a direction perpendicular to the propagation axis of the gas, and an outlet for ejecting the gas. The section includes first and second walls (23), which diverge according to an angle of divergence with respect to the gas propagation axis, a unit to slow the velocity of the gas near the center of the section compared to the gas velocity, and a constriction region having a first height close to the center of the section and a second height close to the wall. The injector (11) comprises an inlet for receiving a gas wave or a gas pulse, a curved section (20) for dilating the gas in a direction perpendicular to the propagation axis of the gas, and an outlet for ejecting the gas. The section includes first and second walls (23), which diverge according to an angle of divergence with respect to the gas propagation axis, a unit to slow the velocity of the gas near the center of the section compared to the gas velocity, and a constriction region having a first height close to the center of the section and a second height close to the wall. The first height is lower than the second height so as to slow down the velocity of the gas close to the center of the section and the wall. The section further comprises a first dilation region (25) having a constant height following the constriction region and in which the wall diverge according to the first angle of divergence, and a second dilation region (26) comprising the constriction region. The constriction region is followed to other region of dilation having a constant height lower than the first height of the constriction region. The first angle of divergence varies with the second angle of divergence, and has a maximum value at the end of the first region. The second angle of divergence is constant and below the maximum value of the first divergence angle. The constriction region are formed so that the gas ejected by the output has a velocity profile with a variation of less than 10% between the maximum and minimum, and 90% of the width of the output. Independent claims are included for: (1) a system for depositing thin layers in the injector; and (2) a process for injection of a gas wave or a gas pulse in the treatment chamber.

Description

GAS INJECTION DEVICE WITH UNIFORM GAS SPEED

The present invention relates to a gas injection device 5 and a method for injecting a gas into a treatment chamber. The present invention more particularly relates to a method for injecting a gas into a treatment chamber of a thin-film reactor. Thin film deposition techniques, such as physical vapor deposition and chemical vapor deposition, are techniques for depositing thin films on a substrate, for example a semiconductor substrate. A particular example of CVD is atomic layer deposition "ALD", also referred to as "ALE" or "ALCVD". This process is used for the manufacture of semiconductors and the manufacture of magnetic thin-film heads. It is currently envisaged to use this method for the manufacture of various new devices, for example organic light emitting diodes and photovoltaic elements. FIG. 1A shows a conventional thin-film deposition system TFS1 comprising at least one injector 1 with a flow shaping section 2, a treatment chamber 4 in which a substrate 5 can be arranged, and a device of FIG. discharge 6. A gas tube 7 connects the injector 1 to at least one gas source 8. During the deposition process, a carrier gas comprising reactants is generally introduced into the injector 1 for a certain period of time, thus forming a "gas wave" or "gas pulse". As described in US Pat. No. 7,163,587, the shaping section 2 of the injector may have a shape

triangular with a first and a second wall which diverge at a constant divergence angle with respect to a propagation axis XX 'of the gas wave in the injector. The shaping section 2 laterally expands the gas wave during its passage from a point 0 to the inlet of the shaping section 2 until it reaches the injector outlet which gives The gas is then injected into the treatment chamber 4, as shown in FIG. 1A by the arrows. In the treatment chamber, reactants in the gas may react with the surface of the substrate 5 and / or with previously deposited molecules. The treatment chamber 4 can then be purged by injection of an inert gas which discharges all the reactants and excess products from the system, by means of the evacuation device 6. The pulse / purge steps can then be repeated with a second gas from another source of gas. Thin layers, for example between 0.1 and 3 Å, are formed on the substrate 5. This cycle is repeated as many times as necessary to obtain the desired thickness of the thin layer. Due to its layer-by-layer implementation, an atomic layer deposition achieves a very high structural quality and a very good control of the thickness of the thin layers, as well as a good recovery of any element present on the substrate. Nevertheless, because of the pulse and purge steps, the duration of this process can be from a few minutes to several hours, depending on various factors such as the thickness of the desired thin layer, the reactants used, the duration of the cycles, etc., resulting in a relatively low production capacity. Recent research and developments have focused on reducing the deposition time of thin films

to make this technique more interesting in the context of a large-scale manufacturing. To decrease the cycle time, it is usual to increase the gas flow. However, because of the Poiseuille law, the triangular shape of the shaping section makes the gas in the center of the injector reaches the outlet before the gas in the vicinity of the walls. Therefore, when such an injector is used in an application where a time-sequential composition profile is created at the input, this peak velocity distribution becomes a non-uniform gas composition distribution, which slows the process by increasing the time required for a gas wave to pass through the treatment chamber, as will be explained in connection with Figures 1B, 1C. FIG. 1B represents the profile C01 of the velocity V of the gas, expressed in meters per second, at the outlet of the injector 1 of FIG. 1A. The velocity of the gas is measured along an axis YY 'perpendicular to the axis of propagation XX'. It can be noted that the COl profile of the gas velocity has a maximum value at the point 0 'at the center of the injector outlet, and decreases rapidly away from the point O', reaching 0 in the vicinity of the walls. of the injector. FIG. 1C shows two profiles P01, P02 for concentration of the gas GC along the axis of propagation XX 'through the treatment chamber 4, starting from the point 0' at the outlet of the injector, at two different times after the injection of the gas wave. The gas concentration is expressed as a percentage of the reactant present in the gas per unit volume. It may be noted that by diffusion of the reactant into the carrier gas, the length of the gas wave or pulse increases as it passes through the process chamber.

In the light of FIGS. 1B and 1C, it will be understood that a relationship exists between the length of the gas wave P01 and the velocity profile of the gas C01. The increase in the non-uniformity of the velocity profile along the axis YY 'at the outlet of the injector causes an increase in the time to evacuate the gas from the injector, an increase in the length of the profile of the injector. gas wave along XX 'which passes through the treatment chamber, and an increase in the time required between the injection of two successive gas pulses, since the part of the slowest gas wave must be removed from the chamber before the injection of the next wave. Nonuniform gas distribution can also lead to deposition anomalies and irregularities in the thin layers. Therefore, it may be desired to have a gas distribution across the substrate as uniform as possible. The gas wave should be optimized for the thin film deposition system and is closely related to the physical properties of the injectors, the dimensions of the treatment chamber, the substrate on which the deposition will be made, etc. Since thin film deposition systems are typically used for electronic applications, they are, in general, optimized for standard substrate sizes commonly used in this industry, for example diameters of 150, 200 and 300 mm. In order to apply these techniques to larger substrates in other fields of application, the dimensions of the injectors, the gas inlets, the treatment chamber, the evacuation device, etc. must be suitably modified, which complicates and increases the cost price of thin film deposition systems for large substrates with very short cycle times. It is neither practical nor economical to develop a system for each treatment combination

possible, and the current systems are not well suited to large substrates, which limits their utility for other areas of application. In addition, recent interest has emerged in the application of thin film deposition methods to other industries, such as the deposition of layers on glass, the production of displays, and the production of photovoltaic elements. These applications use much larger substrates, for example 1200 x 600 mm glass plates or a continuous roll of flexible material, which requires an increase in the amount of gas passing through the injector and an expansion of the outlet. of the injector. However, the increase of the gas flow rate and the widening of the injector outlet cause turbulence and recirculation of the gas in the injector, resulting in a distribution of the gas on the surface of the substrate even less uniform, and a purge of reactants from the inefficient system.

Embodiments of the present invention provide an injector for injecting gas into a process chamber, comprising an inlet for receiving a gas wave or a gas pulse; a shaping section for expanding the gas in a direction perpendicular to a gas propagation axis; an outlet for ejecting the gas; the shaping section having first and second walls which diverge at an angle of divergence from the axis of propagation of the gas. In one embodiment, the shaping section includes means for slowing the velocity of the gas near the center of the shaping section relative to the velocity of the gas near at least one wall. According to one embodiment, the shaping section includes a constriction region having a first height near the center of the shaping section and a second height near at least one wall of the shaping section. shape, the first height being lower than the second height to slow the speed of the gas near the center of the shaping section relative to the velocity of the gas near the wall. According to one embodiment, the shaping section comprises a first expansion region having a constant height, followed by the constriction region. In one embodiment, the constriction region is followed by another dilation region having a constant height less than the first height of the constriction region. According to one embodiment, the shaping section comprises: a first expansion region in which at least one wall diverges at a first angle of divergence; and a second expansion region comprising the constriction region, wherein at least one wall diverges at a second angle of divergence smaller than the first divergence angle, to accelerate the velocity of the gas near the wall relative to the velocity. gas near the center of the gas. According to one embodiment, the first angle of divergence varies and has a maximum value at the end of the first region, and the second angle of divergence is constant and less than the maximum value of the first angle of divergence. According to one embodiment, the shaping section and the constriction region are formed such that the gas ejected through the outlet has a velocity profile with a variation of less than 10% between the maximum and minimum velocities, over at less 90% of the width of the exit.

According to one embodiment, the injector comprises a curved shaping section. Embodiments of the invention also relate to a system comprising a processing chamber; at least one injector according to the injector described above, the output of which gives on the treatment chamber; and at least one gas source coupled to the inlet of the injector. According to one embodiment, the system comprises two superimposed injectors, arranged one on the other and having a common output. According to one embodiment, the system comprises at least two adjacent injectors forming a large equivalent injector having a large equivalent outlet comprising the outlets of the adjacent injectors and expanding the gas over the large equivalent outlet. Embodiments of the invention also relate to a method of injecting a gas wave or a gas pulse into a process chamber, comprising the steps of: expanding the gas in a direction perpendicular to a gas propagation axis by means of an injector comprising an inlet, a shaping section, and an outlet for ejecting the gas; and inject the gas into the treatment chamber. According to one embodiment, the gas expansion comprises a step of reducing the gas velocity near the center of the injector shaping section relative to the velocity of the gas in the vicinity of the wall of the nozzle. shaping section, in order to control the velocity profile of the gas at the outlet of the injector. According to one embodiment, the method comprises a step of providing in the injector at least one constriction region having a first height in the vicinity of a center of the shaping section and a second height in the vicinity of the wall of

the shaping section, the first height being less than the second height. According to one embodiment, the method comprises the steps of: in a first region of the shaping section, causing the shaping section walls to diverge at a first angle of divergence; and in a second region of the shaping section including the constriction region, causing the shaping section walls to diverge at a second angle of divergence smaller than the first divergence angle to increase the velocity of the gas in the vicinity of the wall with respect to the velocity of the gas in the vicinity of the center of the shaping section. According to one embodiment, the method includes steps of varying the first divergence angle so that it has a maximum value at the end of the first region, and keeping the second angle of divergence constant and less than the first angle of divergence. maximum value of the first angle of divergence.

According to one embodiment, the method comprises a step of reducing the velocity of the gas near the center of the shaping section so that the gas injected into the processing chamber has a velocity profile with a lower variation. at 10% between the maximum and minimum speeds over at least 90% of the width of the exit. Embodiments of the invention will be described in the following with reference to, but not limited to, the accompanying drawings in which: FIG. 1A previously described is a schematic top view of a conventional thin film deposition system; FIG. 1B previously described represents a velocity profile of a gas passing through the system of FIG. 1A; FIG. 1C previously described represents a concentration profile of a gas that passes through the system of FIG. 1A; FIGS. 2A and 2B are schematic side and top views of a thin film deposition system according to a first aspect of the invention; FIG. 3 is a view from above of a first embodiment of an injector of the system represented in FIGS. 2A, 2B; FIGS. 4A, 4B, 4C, 4D are sectional views of the injector of FIG. 3 according to various sectional planes; FIGS. 5A, 5B, 5C, 5D show different velocity profiles of a gas passing through the injector of FIG. 3, at different points of the injector; FIG. 6 represents variations in a speed profile of a gas at an outlet of the injector of FIG. 3, for different gas inlet speeds; Figure 7 shows different gas concentration profiles that cross the system shown on 2A, 2B; - Figure 8 is a sectional view of an assembly of injectors of the system shown on 2A, 2B; Fig. 9 is a perspective view of a second embodiment of an injector of the system shown at 2A, 2B; FIG. 10 is a schematic view of a first embodiment of a thin film deposition system according to a second aspect of the invention; FIG. 11 is a schematic view from above of a second embodiment of a thin film deposition system according to the second aspect of the invention; FIGS. 12A and 12B show diffuser plates present in the system of FIG. 11;

FIG. 13 is a schematic view from above of a third embodiment of a thin film deposition system according to the second aspect of the invention; FIG. 14 represents the velocity profile of a gas passing through the system of FIG. 13; and - Figures 15A, 15B, 15C show different arrangements of gas circuits of a thin film deposition system according to the invention. One embodiment of a TFS2 thin film deposition system according to a first aspect of the invention is shown schematically in Fig. 2A and Fig. 2B. For reasons of clarity of the drawings, the elements are not necessarily shown to scale and the drawings do not necessarily show all aspects of the system. The TFS2 system is designed for atomic layer deposition and comprises an injector assembly 10 having two injectors 11, 11 ', a base unit 40, and an evacuation device 60. The base unit 40 includes a chamber processor 41 receiving a substrate 50 which can be mounted on a support. Each injector 11, 11 'has a gas inlet inlet connected to a gas source 81, 82 through a gas tube 71, 72 and a valve 85, 86. The base unit 40 may be made of metal, for example aluminum or stainless steel, and may include other components, such as components for creating a vacuum, for heating the treatment chamber and / or the substrate, openings for the introduction and removing the substrate, cleaning, aligning the base unit with other components, etc. A first gas wave is introduced into the injector 11 and propagates along a propagation axis XX 'through the injector 11, in which it is expanded laterally, that is to say along an axis Y4Y4'

perpendicular to the propagation axis XX ', before being injected into the treatment chamber 41. In the treatment chamber, the first gas wave passes through the surface of the substrate 50 into a wave which is substantially parallel to the surface of the substrate, and reacts with the substrate before being purged from the chamber by means of the evacuation device, which is connected to a pump 60. A second wave of gas is then introduced into the injector 11 'and propagates along of the propagation axis XX 'through the injector 11', in which it is expanded laterally along the axis Y4Y4 'before being injected into the treatment chamber 41. In the treatment chamber, the second wave of The gas passes through the surface of the substrate 50 into a wave that is substantially parallel to the surface of the substrate, and reacts with deposits left by the first gas injection. By way of example, to obtain an Al 2 O 3 layer, a first gas comprising aluminum is pulsed through the first injector into the treatment chamber where it reacts with the substrate. Then, the first gas is purged from the chamber by means of the evacuation device while an inert gas, such as nitrogen N2 or argon Ar, is introduced into the chamber by means of the first injector. Then, a second gas comprising oxygen is pulsed into the chamber through the second injector, and the oxygen reacts with the aluminum, forming a monolayer of Al2O3. The chamber is still purged with an inert gas, and the cycle is repeated. Figure 3 is a top view showing in more detail the structure of the injector 11 according to a first embodiment of the invention. It is assumed that in this embodiment the two injectors 11, 11 'have the same structure. Consequently,

only the injector 11 will be described. Nevertheless, other embodiments may be provided, wherein the injectors 11, 11 'have different structures, for example depending on the nature of the gas they eject. The injector 11 comprises a body 12 and a shaping section 20. The shaping section 20 may be a countersunk cavity of the body 12. The body may be a metal plate, for example aluminum or stainless steel . The cavity can be formed by precise milling of the metal plate. A cover 13 may be assembled to the body 12 by welding, or solder, or simply mounted thereon by means of screws, plugs, etc.

The shaping section 20 includes an inlet 21 and an outlet 22. The inlet 21 is connected to the gas tube 71 and has the shape of a small opening. The outlet 22 has the shape of a larger opening and gives access to the treatment chamber for injecting the gas therein. The shaping section comprises left and right walls 23, a lower surface, and an upper surface formed for example by the lid mentioned above. The lower and upper surfaces are substantially parallel except in a region to be described below. The walls 23 diverge outwardly from the inlet 21 to the outlet 22, expanding the gas wave in a direction perpendicular to a propagation axis XX 'of the gas wave. The shaping section 20 further includes a constriction region 24 for shaping the gas velocity profile as desired. As will be explained below, the height of the shaping section 20 in the constriction region 24 varies to uniformize the gas wave velocity over the entire lateral expansion width of the injected gas wave. in the treatment chamber 41. The injector 11 expands

thus the gas wave along the axes YlYl ', Y2Y2', Y3Y3 ', Y4Y4' perpendicular to the axis of propagation XX ', while adjusting the speed of the gas over the entire width of lateral expansion. In particular, and as shown in FIG. 4C, the constriction region may have a reduced height h2 in the vicinity of the propagation axis and a greater height h3 in the vicinity of the walls 23, in order to reduce the speed of the gas in the vicinity. from the center of the shaping section relative to its speed near the walls. In the embodiment shown in Fig. 3, the shaping section further comprises a first expansion region 25 which achieves only a lateral dilation and a second expansion region 26 which includes the constriction region 24 and performs an expansion. lateral and vertical constriction. The first expansion region 25 extends from the inlet 21 to a transition point X2, and the second expansion region 26 extends from the point X2 to the outlet 22. The first and second expansion regions can consist of two different parts connected together, or simply be different parts of one piece.

The first expansion region 25 includes a left wall 23a and a right wall 23b, and the second expansion region 26 comprises a left wall 23c and a right wall 23d. The walls 23a, 23b of the first expansion region 25 diverge at a divergence angle A1 with respect to the propagation axis XX 'of the gas wave, while the walls 23c, 23d of the second expansion region 26 diverging at an angle of divergence A2 with respect to the axis of propagation XX '. In one embodiment, the angle of divergence A1 is greater than the divergence angle A2, so that the

second expansion region 26, while performing an overall lateral expansion of the gas wave, also performs an additional constriction function in the vicinity of the walls, to further reduce the velocity of the gas near the center with respect to its velocity to near the walls of the second expansion region 26. In one embodiment, the divergence angle A1 varies and increases with increasing distance from the inlet 21, to reach a maximum value Almax at the end of the first expansion region 25, while the divergence angle A2 is constant, Almax being greater than A2. Preferably, the angle of divergence A1 varies according to a "supralinear" function, for example a quadratic or exponential function. A supralinear lateral dilation promotes the suppression of turbulence near the inlet 21 of the injector 11, where the gas velocity is the highest. In the embodiment shown in FIG. 3, the walls 23a, 23b of the first expansion region 25 exponentially diverge while the walls 23c, 23d of the second expansion region 26 diverge linearly with a constant angle A2. FIGS. 4A, 4B, 4C, 4D show sectional views of the injector of FIG. 3 in different sectional planes, respectively P1, P2, P3, P4, which are perpendicular to the propagation axis XX '. The plane P1 passes through a point X1 of the axis XX ', the point X1 being situated at a distance d1 from a reference point 0 to the input 21. The plane P2 passes through a point X2 of the axis XX X2 being at a distance d2 from the point 0, the distance d2 being greater than the distance d1 and equal to the length of the first expansion region 25. The plane P3 passes through a point X3 of the axis XX ', the point X3 being situated at a distance d3 from the point 0, the

distance d3 being greater than the distance d2 and substantially corresponding to the central point of the constriction region 24. The plane P4 passes through a point X4 of the axis XX ', the point X4 being situated at a distance d4 from the point 0, the distance d4 being greater than the distance d3 and equal to the length of the shaping section 20, so that the plane P4 includes the outlet 22 of the injector. In FIG. 3, the axis of propagation XX 'and a longitudinal axis of symmetry of the injector coincide, so that the points X1, X2, X3, X4 are each equidistant from the left and right walls of the section of the injector. In FIG. 4A, the sectional view of the first expansion region 25 of the shaping section 20 has a substantially rectangular shape, with a width W1 and a height h1. The height h1 is the distance between the lower surface and the upper surface of the shaping section 20, the upper surface being constituted by a lower face of the cover 13. In FIG. 4B, the sectional view of the section at the boundary between the first and the second expansion region 25, 26, has a substantially rectangular shape with a width W2> W1 and a height h1 equal to that of FIG. 4A. In FIG. 4C, the sectional view of the shaping section 20, in the constriction region 24 located in the second expansion region 26, has a width W3> W2, a flat upper surface and a substantially convex lower surface. . It therefore has a first height h2 in the center of the region 26 and a second height h3 close to the walls, where h3 is greater than h2 in order to reduce the speed of the gas at the center of the second expansion region with respect to the speed of the gas near the walls. In a mode of

realization, the shape of the convex lower surface along the axis Y3Y3 'is defined according to a Bezier curve. In this embodiment, h2 is greater than h1 but may be less than or equal to h1 in other embodiments. In FIG. 4D, the sectional view of the shaping section 20, close to the outlet 22, has a substantially rectangular shape with a width W4> W3 and a height h4 less than h3 and also less than h1. In other embodiments, h4 may be greater than h1 and less than h2. In one embodiment, the lower surface of the second expansion region 26 comprises two surfaces defined by "non-uniform rational b-spline"), one in the area between the Y2Y2 'and Y3Y3' axes, and another in the zone. between the axes Y3Y3 'and Y4Y4'. FIGS. 5A, 5B, 5C, 5D represent different profiles C1, C2, C3, C4 of velocity V of a gas wave which passes through the injector, measured along different perpendicular axes Y1Y1 ', Y2Y2', Y3Y3 ', Y4Y4' to the propagation axis XX 'and respectively included in the planes P1, P2, P3, P4. A digital fluid mechanics analysis on a discrete three-dimensional model of the injector geometry using the finite volume method can be used to obtain such profiles. It can be noted that: - In FIG. 5A, the profile C1 is very sharp around the central point X1 of the shaping section 20 and has a high speed at this point, then it decreases rapidly while moving away from the point X1 to reach a speed of 0 m / s in the vicinity of the walls 23;

In FIG. 5B, the profile C2 is always pointed, but less, around the central point X2, has a speed lower than the point X2, and decreases less rapidly than the profile C1 while moving away from the central point X2, to reach a velocity of 0 m / s in the vicinity of the walls 23; - In Figure 5C, it can be noted that the correction of the speed distribution between the center of the injector and the walls has begun. The profile C3 is no longer sharp around the central point X3, and has a fairly flat profile with steep slopes in the vicinity of the walls 23. The higher height h3 generates a reduced resistance of the flow near the walls, leading the gas to edges. As a result, the gas has a higher speed of about 10% near the edges with respect to the center. The profile C3 thus has a small "hollow" in the vicinity of the central point S3 and two "bumps" on each side of the hollow; and - In FIG. 5D, the profile C4 is substantially uniform over the majority of the outlet 22 and decreases abruptly at a speed of 0 m / s in the vicinity of the walls 23. Consequently, the different heights h1, h2, h3, h4 of the injector can be adjusted to adjust as desired the speed profile of the gas injected into the treatment chamber. In applications where a uniform velocity profile is desired at the nozzle exit, the present invention provides a velocity distribution of less than 10% between the maximum and minimum speeds over at least 90% of the width of the nozzle. exit. Generally, the velocity distribution at the outlet 22 of the injector depends not only on the difference between h1, h2, h3, h4, but also on the difference between the maximum angle of divergence Al of the first region of the injector.

dilation 25 and the divergence angle A2 of the second expansion region 26, and also the initial velocity of the inlet gas 21, as will be demonstrated with reference to FIG. 6.

FIG. 6 represents the effect of the speed of the inlet gas on the velocity profile of the gas at the outlet of the injector 11, along the axis Y4Y4 '. The gas velocity is expressed here as a ratio between the gas velocity along the Y4Y4 'axis and its maximum velocity. In this example, the first expansion region 25 has a width W2 of 10 cm, a length d2 of 7.5 cm, and an angle of divergence A1 which varies exponentially. The constriction region 26 has a height h3 = 0.5 * h2. Three profiles C4 ', C4 ", C4"' are represented and correspond to the input speeds 21, respectively 10 m / s, 40 m / s, 70 m / s. The profiles C4 'and C4' 'have two lateral "bumps" and a central "hollow", and therefore have the lowest speed near the central point X4 and the two highest points near the walls. The C4 "'profile has three" bumps "and two" hollows ", and therefore a center point and two maximum speed side points, and two points of minimum speed between the maximum speed points.It will be noted that these profile features of speed are shown in an exploded view and are, in practice, of relatively small dimensions, for example, for the profile C4 "', the difference between the" bumps "and the" hollows "represents a variation of less than 1% of the gas velocity, which is therefore substantially uniform over most of the width of the outlet of the injector. These profiles demonstrate that, for a given shape of the expansion regions 25, 26 and the constriction region 24, a critical speed VC exists. The behavior of the injector differs in

a function of the gas inlet velocity, depending on whether it is below or above the critical velocity VC. Below the critical velocity, there is no turbulence and recirculation in the first expansion region 25; the speed profile is substantially constant and independent of the input speed. Above the critical speed, recirculation occurs in the first expansion region 25, and the output velocity profile changes with the input velocity, causing changes in the uniformity of the velocity profile. The value of the critical velocity VC depends on the geometry: a first short and / or wide expansion region has a lower critical velocity VC, which means that recirculation or turbulence occurs at a lower input velocity relative to a longer and / or narrower expansion region. As a result, there is an approximate relation of the type VC = f (d2 / W2). The output velocity profile can be adjusted by adjusting the height h2 of the constriction region at the point X2. The correction required depends on the length of the first expansion region 25 and the desired operating point. A method of designing the injector may consist of a slight overcompensation of the speed in the vicinity of the walls so that its most uniform speed profile is at the highest input speed before reaching the critical speed. In general, those skilled in the art have the ability to adjust the properties of the injector, for example by modifying the heights h1, h2 h3, h4 to obtain the desired gas profile in connection with an application. considered. The height h1 may be chosen to correspond approximately to the diameter of the gas inlet tube, which may have a standard diameter of

6 mm or about 12 mm, in some applications. If a height h1 is chosen so that it is significantly different from the diameter of the inlet, a step in the path of the gas can be created, which generates recirculation or turbulence. The height h4 may be relatively small, for example 1 to 2 mm in some applications, and may be limited by the manufacturing process. A reduced height h4 can help prevent gas reflux from another injector if there is more than one injector. FIG. 7 shows profiles P10, P11, P12, P13 of a gas concentration GC along the propagation axis XX 'through the treatment chamber 41, from point X4 to the outlet of the injector, to four moments after injection of the gas wave into the injector, respectively, 80 ms, 100 ms, 120 ms and 140 ms. The gas concentration is expressed as a percentage of the reactant present in the gas per unit volume. During the propagation of the gas wave through the treatment chamber, the gas wave remains very uniform, without losing much of its height or becoming very dispersed. This is due to the initial uniformity of the gas velocity profile at the outlet of the injector. The width of the wave pulse increases slowly, with a slight difference between the values near the walls relative to the values near the center of the injector. It has been observed that the thin film deposition system is ready to begin the next cycle after the purge of the half of the treatment chamber contrary to a conventional method such as that described by US Patent 7,404,984, in which a pulse purge of at least twice the volume of the treatment chamber must be injected before starting the next cycle. Therefore, the speed profile monitoring, thanks to the structure

of the injector according to the invention, allows an increase in the rate of pulses and purge cycles. FIG. 8 shows a sectional view of an embodiment of the TFS2 thin film deposition system shown in FIGS. 2A, 2B, which illustrate how two injectors 11, 11 'can be assembled to form an injector assembly 10 As previously described, each injector 11, 11 'comprises a machined body 12 in which the different regions 24, 25, 26 of the forming section 20 have been formed, and a cover 13. A divider block 87 is arranged between the injectors 11, 11 'to form a physical support. Each injector is arranged on the divider block 87 so that its cover 13 is against the divider block. Viewed in section, the divider block has a triangular shape so that each injector 11, 11 'is oriented relative to the other at a given angle, for example 60 °, and their outputs 22 meet to form a common output. The common outlet is formed by a region where their respective bodies 12 are not covered by the cover 13 and are opposite to each other. The injectors 11, 11 'are integral with the base unit 40 and are aligned therewith by means of alignment devices 88, 89, for example pegs. Each injector 11, 11 'is connected at the inlet to a gas tube 71, 72 respectively, which is itself connected to one or more gas sources. In another embodiment, the injectors may not comprise a lid. The divider block 87 can itself form the upper surface of each injector. FIG. 9 represents another embodiment of an injector 111 according to the invention. The injector 111 comprises an inlet 112, followed by a first shaping section 113, itself followed by a second

shaping section 114, and an outlet 115 at the end of the second shaping section 114. The first shaping section 113 has a curved shape, substantially S-shaped. It also has walls 116 which diverge at a first angle of divergence A1, preferably a variable angle increasing according to a quadratic or exponential function. Accordingly, the first shaping section 113 forms an expansion device that corresponds to the first expansion region previously described. A propagation axis X1X1 'of the gas here has a curved shape due to the gas passing through the shaped forming section 113 curved. The second shaping section 114 has walls 117 and a constriction region 118 in which its height varies along an axis perpendicular to the axis of propagation X1X1 'of the gas, with a height near its center which is less than the height near the walls 117. In one embodiment, the walls 117 diverge at an angle A2 and the second shaping section 114 corresponds to the second expansion region described above, which includes the constriction region. . In another embodiment, the second shaping section 114 has parallel walls 117 and forms a constriction device for the gas wave ejected by the first shaping section 113, without additional lateral expansion of the gas. It will be appreciated that various other embodiments and applications of an injector according to the invention may be provided by those skilled in the art. The constriction region may have various shapes and may for example be obtained both by variations of the lower surface and the upper inner surface of the shaped section. The constriction region

may also be implemented by means of a diffusion plate of the type described below in relation to FIGS. 12A, 12B. These plates have openings dimensioned and / or spaced from each other so that in the constriction region, the center of the gas wave is slowed relative to its edges. Furthermore, although it has been indicated above that the TFS2 system is designed for the atomic layer deposition in which gas waves are injected into the treatment chamber, embodiments of an injector according to the invention. The invention can also be used for other processes and other material deposition systems, for example, chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, chemical vapor deposition plasma-assisted, and more generally, any process in which a gas passes through an injector and enters a treatment chamber.

Also, the use of the term "substrate" in the description should mean any type of material on whose surface a chemical reaction can occur so that thin layers can be formed. These substrates may be semiconductor material, plastic, metal, glass, optoelectronic devices, flat screens, liquid crystal displays, etc. and can be of various sizes, shapes, and formats. Also, embodiments of an injector according to the invention may also be used to expand a continuous flow of gas instead of forming a gas wave. Such embodiments may improve a thin film deposition process by homogenizing the amount of reactant deposited by the gas

over the entire treated surface, and therefore uniformize the thickness of the deposited thin film. Also, a thin film deposition system according to the invention may comprise a single injector instead of an assembly comprising two or more injectors according to the invention. In addition, embodiments of an injector according to the invention are not only designed to make the velocity profile of the gas uniform at the outlet of the injector. In other applications, it may instead be desired for the gas velocity in the vicinity of the walls to be different from the gas velocity at the center of the outlet, and in particular it may be desired to obtain a gas velocity greater than adjacent walls relative to the speed in the center of the outlet, which will be demonstrated below in connection with the description of a second aspect of the invention. As noted above, the application of thin film deposition techniques to process substrates larger than conventional semiconductor substrates, requires the dimensions of the injectors, the process chamber, the evacuation device, etc. . be adapted accordingly. In such applications, it may be desired to provide a thin film deposition system suitable for large substrates. In this case, it may be desired to provide injectors with a large output. However, it has been observed that the greater the output of an injector, the more difficult it is to control the velocity profile of the gas, i.e. when the ratio of the width of the outlet to the width of the injector the entrance increases. An increase in the width of the outlet while keeping the constant gas velocity at the exit requires that the injector has a greater length, than the amount of gas required to pass through the injector

is increased, and the gas is injected at a higher speed at the inlet. All of these constraints create a greater risk of inlet gas turbulence and recirculation, a less efficient deposition process, non-uniform gas distribution, deposition anomalies, and irregularities in the thin layers. Figure 10 schematically shows a top view in section of a thin film deposition system TFS3 according to a second aspect of the invention. The TFS3 system comprises a modular injector 100, a large processing chamber 42 formed to receive a large substrate 52, and a suitable evacuation device 62. The modular injector 100 comprises at least two adjacent injectors, here two conventional injectors 1, 1 ', such as those described in connection with Figure 1A. The two injectors are arranged side by side, and have sidewalls 91 in contact with each other or separated by a seal. Each injector has an inlet coupled to a gas tube 71, 71 'for receiving a gas wave, a shaping section 2, 2' having left and right walls which diverge at a diverging angle, and an outlet for eject the gas.

The modular injector 100 forms a large equivalent injector having a large equivalent output which includes the outputs of the adjacent injectors 1, 1 'and expands the gas on the large equivalent output. The modular injector ejects a gas wave resulting from a juxtaposition of gas waves ejected by each injector, which passes through the processing chamber 42 along a propagation axis X2X2 '. Such an arrangement in parallel of the injectors 1, 1 'avoids the drawbacks indicated above, in particular in that it does not require an increase.

the length of the injectors and an increase in the speed of the gas injected at the inlet, thus reducing the associated problems, such as recirculation and turbulence. In practice, the choice of the number of injectors to use depends on the size of the substrate to be treated. In addition, development costs are reduced by optimizing a single injector which is then used as many times as desired to obtain a modular injector.

To ensure the generation of a uniform gas wave at the output of the two or more injectors that form a modular injector, different factors must be taken into account, such as the proper alignment of the injectors and the synchronization of the gas waves of all the injectors. These factors can be quite easily treated. The alignment of the injectors with each other and with the treatment chamber can be accomplished by any known means, for example positioning pins, rails, etc.

Synchronization of gas waves can be accomplished with precision by precisely controlling gas sources, valves, and gas tubes with more or less identical components for each modular injector. For example, electrically actuated pneumatic valves allow injection of gas pulses of up to 20 ms and synchronization of several values with an accuracy greater than 1 ms. Another factor that can be considered is the uniformity of the pulse on the large equivalent output of the modular injector. However, with reference to FIG. 10, it can be noted that a connection zone 90 exists between the injectors, where the two injectors 1, 1 'are connected. The connection zone 90 is defined as a distance between adjacent walls 91 of the

injector outlets 1, 1 '. More generally, in a modular injector comprising more than two injectors, it is defined as the distance between adjacent walls of the outlet of any two adjacent injectors. Such a connection zone is generally equal to twice the thickness of the walls of the injectors which are side by side. It may also include the thickness of any alignment or attachment means that can be arranged between two adjacent injectors.

It may be further noted that in the absence of gas injection into the connection zone, the gas velocity profile may have a non-uniform region 92 facing the connection zone, along the axis X2X2 'propagation of the resulting gas wave. This phenomenon is aggravated by the fact that conventional injectors 1, 1 'inherently have a non-uniform distribution of gas on their outlets, with a lower gas velocity near the walls. Figure 11 schematically shows a sectional top view of a TFS4 thin film deposition system according to the second aspect of the invention, which provides a better uniformity of the velocity profile of the gas in the processing chamber. The TFS4 system is generally similar to the TFS3 system and also comprises a modular injector 101 with two injectors 1, 1 ', the treatment chamber 42, and the evacuation device 62. Each injector 1, 1' further comprises a pressure plate. diffusion 95, 95 ', arranged at its output. Each diffusion plate 95, 95 'is designed to increase the gas flow near the adjacent walls of the injectors, to compensate for the lack of ejected gas in the connection zone 90. Therefore, the large gas wave in the processing chamber, at a distance from the outlet of the modular injector 101, a

uniform velocity profile in a region 93 opposite to the connection zone. Figure 12A shows an exemplary embodiment 95-1 of the diffusion plates 95, 95 '. The diffusion plate 95-1 comprises openings 96-1 having constant diameters and a non-constant distribution, so that there are more openings near the edges of the plate 95-1 corresponding to the walls of the wall. injector, only in the center of the plate. For example, the center-to-center distance between the apertures varies from a minimum value S1 on the edges of the plate to a maximum value S2 in the center of the plate, where the apertures are further spaced. Figure 12B shows another embodiment 95-2 of the diffusion plates 95, 95 '. The diffusion plate 95-2 comprises apertures 96-2 having variable diameters and a constant center-to-center distance, arranged such that there are larger apertures near the edges of the plate 95-2. corresponding to the walls of the injector, in the center of the plate. For example, the diameter of the openings varies from a minimum value D1 near the center of the plate to a maximum value D2 at the edges of the plate.

A third embodiment of the plates 95, 95 ', not shown, may include varying center-to-center distances between the apertures and varying aperture diameters. It will be noted that in Figs. 12A, 12B, the apertures of the diffusion plates 95-1, 95-2 have a similar arrangement on the right and left edges of the diffusion plates. This symmetrical arrangement makes it possible to increase the flow of gas on each edge of the injector outlets 1, 1 ', to compensate both for the absence of gas ejection in the connection zone 90 and the

presence of non-adjacent side walls 91 'on each side of the modular injector. Accordingly, the equivalent width of the output of the modular injector can be considered as the sum of the widths of each output, plus the sum of the thicknesses of the adjacent walls 91, plus the sum of the thicknesses of the non-adjacent side walls 91 '. In other embodiments, the apertures of the diffusion plates 95-1, 95-2 may have a non-symmetrical arrangement on the left and right edges of the diffusion plate. FIG. 13 schematically represents a top view in section of another embodiment TFS5 of a thin film deposition system according to the second aspect of the invention, which also provides for a better uniformity of the gas velocity profile in the treatment chamber and compensates for the presence of the connection zone 90. The TFS5 system comprises a modular injector 102, the treatment chamber 42, the evacuation device 62, and the connection zone 90. The modular injector 102 comprises two injectors 211, 211 'arranged in such a way that they are adjacent and which are designed according to the first aspect of the invention, each injector comprising an expansion region 25 and a constriction region 24.

Each injector 211 or 211 'differs from the injector 11 or 11' previously described in that the expansion and constriction regions are configured such that, at the outlet of the injector, the speed of the gas near the walls is greater than the gas velocity near the center of the outlet, which also means that the gas flow near the walls is greater than the gas flow near the center of the outlet. In an unsymmetrical embodiment of the injector 211, 211 ', the regions of expansion and

constriction can be configured such that the velocity of the gas is greater than near the wall which is adjacent to one wall of the other injector. FIG. 14 represents the profile C5 of the velocity V of the gas at the outlet of the injectors 211, 211 'of FIG. 13. The velocity of the gas is measured along an axis Y5Y5' which is perpendicular to the axis of propagation of the large gas wave, and at a determined distance d5 from the output of the modular injector, for example 5 mm from the modular injector. The speed profile C5 is substantially constant and has a variation of less than 10% between the maximum and minimum speeds over at least 90% of the width of the large equivalent output of the modular injector.

A modular injector is susceptible to various other embodiments and applications. In one embodiment, a plurality of modular injectors, each comprising N injectors in parallel, are arranged in a thin film deposition system which comprises a conveyor belt on which substrates are arranged or a continuous roll of a flexible substrate. Whenever a substrate or part of the continuous substrate is in front of the output of a modular injector, one or more pulses of one or more gases are ejected onto the substrate. Such a system makes it possible to obtain a continuous deposition of thin layers on a series of substrates, with a higher production capacity. FIGS. 15A, 15B, 15C show various arrangements for supplying a gas to a modular injector 100, 101, 102. Since it is desired to obtain a uniform gas profile at the outlet of the modular injector, it is important to precisely synchronize the injection of the gas into each injector, in particular when a pulsed process is implemented. On the face

15A, a single source of gas 81 is connected to the injectors 1,1 'or 211, 211' by means of a single valve 85. In FIG. 15B, a single source of gas 81 is connected to the injectors 1, 1 'at means of two valves 85, 85 ', one per injector. In FIG. 15C, a first gas source 81 is connected to the first injector 1 or 211 by means of a first valve 85. A second gas source 81 'supplying the same gas as the first gas source 81 is connected to the first gas source 81. second injector 1 'or 211' by means of a second valve 85 '. It will be apparent to those skilled in the art that these arrangements are applicable to modular injectors comprising N parallel injectors. More particularly, N parallel injectors can be controlled by a single valve.

Moreover, despite the fact that the present invention has been described in connection with applications relating to thin film deposition techniques, it will be apparent to those skilled in the art that embodiments of an injector or modes of embodiments of a modular injector according to the invention can be used for other purposes, in different applications where it is necessary to inject a gas in a treatment chamber, for example for etching, diffusion, etc.

Claims (16)

REVENDICATIONS1. Injector (11, 111, 211) for injecting a gas into a treatment chamber (41), comprising: - an inlet (21, 112) for receiving a gas wave or a gas pulse, - a shaping section (20, 113, 114) for expanding the gas in a direction (YY ') perpendicular to an axis of propagation (XX', X1X1 ') of the gas, - an outlet (22, 115) for ejecting the gas, the section of forming having a first and a second wall (23, 116, 117) which diverge at a divergence angle (A1) with respect to the axis of propagation of the gas, characterized in that the shaping section comprises means for slowing the velocity of the gas near the center of the shaping section, relative to the velocity of the gas near at least one wall. Injector according to claim 1, wherein the shaping section comprises a constriction region (24, 118) having a first height (h2) near the center of the shaping section and a second height (h3). ) near at least one wall (23, 23a, 23b, 23c, 23d, 116, 117) of the shaping section, the first height (h2) being less than the second height (h3) in order to slow down the velocity of the gas near the center of the shaping section relative to the velocity of the gas near the wall. An injector according to claim 2, wherein the shaping section comprises a first expansion region (25, 113) having a constant height (h1), followed by the constriction region (24, 118). 32 Injector according to claim 3, wherein the constriction region (24, 118) is followed by another expansion region having a constant height (h4) less than the first height (h2) of the constriction region. Injector according to one of claims 2 to 4, wherein the shaping section (20, 113, 114) comprises: - a first expansion region (25, 113) in which at least one wall (23a, 23b, 116) diverges at a first angle of divergence (Al), and - a second expansion region (26, 114) comprising the constriction region (24, 118), wherein at least one wall (23c, 23d, 117) ) diverges at a second angle of divergence (A2) less than the first divergence angle (A1), in order to accelerate the velocity of the gas in the vicinity of the wall relative to the velocity of the gas near the center of the gas. Injector according to claim 5, wherein the first divergence angle (Al) varies and has a maximum value (A1max) at the end of the first region (25, 113), and the second divergence angle (A2) is constant and less than the maximum value of the first angle of divergence. Injector according to one of claims 2 to 6, wherein the shaping section (20, 113, 114) and the constriction region (24, 118) are formed in such a way that the gas ejected from the outlet (22, 115) has a velocity profile with a variation of less than 10% between the maximum and minimum speeds over at least 90% of the width of the exit. 8. Injector (111) according to one of claims 1 to 7, comprising a curved forming section (113). 9. System (TFS2, TFS5) comprising: - a treatment chamber (41), - at least one injector (11, 111, 211) according to one of claims 1 to 8, whose output (22, 115) gives on the treatment chamber, and - at least one gas source (81, 82) coupled to the inlet of the injector. 10. System according to claim 9, comprising two injectors (11, 11 ', 111) superimposed, arranged on one another and having a common output. 11. System (TFS5) according to claim 9, comprising at least two adjacent injectors (11, 211) forming a large equivalent injector having a large equivalent outlet comprising the outlets (22, 115) of the adjacent injectors and expanding the gas on the large equivalent output. 12. A method of injecting a gas wave or a gas pulse into a process chamber (41), comprising the steps of: - expanding the gas in a direction perpendicular to an axis of propagation (XX) ', X1X1') of the gas by means of an injector (11, 11 ', 111, 211) comprising an inlet (21, 112), a shaping section (20, 113, 114), and an outlet (22, 115) for ejecting the gas, and injecting the gas into the treatment chamber (41), characterized in that the gas expansion comprises a step of reducing the velocity of the gas in the vicinity of the center of the section. shaping (20) the nozzle relative to the gas velocity in the vicinity of the wall of the shaping section (20) to control the velocity profile of the gas at the outlet of the injector . The method of claim 12, including a step of providing in the injector at least one constriction region (24, 118) having a first height (h2) in the vicinity of a center of the shaping section and a second height (h3) in the vicinity of the wall of the shaping section, the first height (h2) being less than the second height (h3). The method of claim 13, comprising the steps of: - in a first region (25, 113) of the shaping section, causing the shaping section walls to diverge at a first angle of divergence ( A1), and - in a second region (26, 114) of the shaping section comprising the constriction region (24, 118), causing the shaping section walls to diverge at a second angle of divergence ( A2) less than the first divergence angle, in order to increase the gas velocity in the vicinity of the wall with respect to the velocity of the gas near the center of the shaping section. The method of claim 14, comprising steps of varying the first divergence angle (Al) so that it has a maximum value (Almax) at the end of the first region (25), and keeping the second angle of divergence (A2) constant and less than the maximum value (Almax) of the first angle of divergence. The method according to one of claims 12 to 15, comprising a step of reducing the velocity of the gas near the center of the shaping section (20) so that the gas injected into the treatment chamber has an velocity profile with a variation of less than 10% between the maximum and minimum speeds over at least 90% of the width of the exit.