Method and apparatus for uniforming an injection gas flow on a surface in a vacuum chamber

Abstract

The present invention relates to a vacuum evaporation deposition apparatus (30) comprising: a deposition chamber or structure; depositing a carrier (32); an evaporation unit (36) for evaporating material towards the deposition substrate (32); a reaction gas injection unit (41) for injecting a reaction gas into the cavity; a unit for forming a baffle (2) around the deposition substrate, extending from the deposition carrier, an axis XX'forming a rotational symmetry axis perpendicular to and centered on a surface of the deposition carrier, the reaction gas injection unit (41) comprising a duct provided with several orifices enabling injection of reaction gas at a first moment distribution, the first moment distribution has rotational symmetry about the axis XX.

Description

Technical Field

[0001] This invention relates to the field of methods and apparatus for depositing thin layers.

[0002] One application of the present invention relates to microfabrication of circuits, wherein thin films are deposited in the presence of a reactive gas to form thin layers ranging from several nanometers to hundreds of nanometers. Background Technology

[0003] Cathodic sputtering is a known technique in which a target for the material to be deposited, such as an oxide (or nitride or hydride), is used. Atoms are extracted from the target by bombarding it with plasma. Deposition then occurs under high pressure (greater than microbars), where the path of freedom is on the order of millimeters, and the incident atoms on the substrate are therefore isotropic. These conditions allow for precise control of the stoichiometry of the deposit, enabling the deposit to become homogeneous over large surfaces.

[0004] However, this method has the drawback of bombarding the deposition surface and inducing stress in the layer or dislocations in the substrate, which leads to the search for other deposition methods, such as evaporation (via electron gun or Joule effect).

[0005] In evaporation deposition techniques, homogenization of the deposit can be achieved by rotating the deposition plate. In this case, the lateral gradient is partially averaged, but the radial gradient relative to the center of the plate is not eliminated. Furthermore, there are scenarios where planetary rotation does not provide a solution for homogenization: when rotation is not possible (e.g., in the case of angled deposition), or when the deposition duration is too short to allow for a large number of plate rotations relative to the plate at once (e.g., if the film to be deposited is too thin and the deposition rate cannot be reduced accordingly).

[0006] When seeking to evaporate elements in the presence of a reactant gas, the goal is to control the uniformity of both the gas flow rate and the flow rate of the evaporated element.

[0007] The evaporator is designed to ensure a uniform flow rate of the material being evaporated (which is initially in a solid state at room temperature): for this purpose, the source is placed at a certain distance from the deposition plate.

[0008] Regarding the flow of the reacting gas, the technical problem cannot be solved in a similar manner. In fact, the gas must be injected into a vacuum chamber. This is done through one or more orifices, causing the gas to expand from atmospheric pressure or slightly higher to the vacuum within the chamber. Once inside the chamber, the molecules do not collide with each other but instead follow ballistic trajectories.

[0009] The expansion of gas through the orifice generates a material flow with an angular distribution described by Clausing's formula [P. Clausing, Z. Physik 66, 471 (1930)].

[0010] Calculations based on these distributions show that it is impossible to perfectly focus the molecular flow leaving the orifice. Most molecules exit at an angle deviating from the orifice axis and accumulate in the vacuum cavity. Therefore, the incident gas flow on the deposition surface mainly originates from molecules that have already impacted the cavity wall at least once, and is not isotropic. Furthermore, it also depends on the geometry of the cavity.

[0011] Each molecule that impacts the wall is adsorbed onto the surface, remains there for a certain period of time, and is re-ejected at a velocity and angular distribution that depends on the wall temperature, chemical composition, and wall type.

[0012] Therefore, the problem lies in enabling the incident gas flow to operate in a ballistic state (i.e., at a speed of less than, for example, 5 × 10⁻⁶). -5 The pressure of millibars is used to homogenize the deposition surface, especially in vacuum chambers. This is particularly true when seeking to deposit alloys with a uniform composition (stoichiometry) between elements evaporated (by an electron gun or the Joule effect, which are in solid form at ambient temperature) and reactive gases injected into the chamber (which are in gaseous form at ambient temperature and pressure).

[0013] The problem also lies in the uniformity of the atomic or molecular flow of a gaseous compound at ambient temperature and pressure, which is incident on a deposition surface placed in a vacuum chamber in a ballistic manner. Summary of the Invention

[0014] One object of the present invention is to enable deposition by evaporation in a ballistic state and in the presence of reactive gases, resulting in a more uniform deposition (in composition) compared to known deposition techniques.

[0015] This invention first relates to a vacuum evaporation deposition apparatus, comprising:

[0016] Deposition cavity or structure;

[0017] Deposition carrier or substrate;

[0018] A gas injection unit is used to inject gas into the cavity;

[0019] An evaporation unit is used to evaporate material toward the deposition substrate;

[0020] A unit that forms a baffle around a deposition substrate.

[0021] The baffle-forming units extend from the deposition substrate or support, with axis XX' forming a rotational or rotational symmetry axis that is perpendicular to and preferably centered on the surface of the deposition support. These baffle-forming units surround and / or enclose the deposition surface, except for holes or openings positioned facing the source or evaporation unit.

[0022] Preferably, the reactive gas injection unit includes a pipe with several orifices, allowing gas to be injected in a first-order moment distribution, which has rotational symmetry about the axis XX'; these reactive gas injection units are, for example, in the form of spray heads. They are positioned between the evaporation unit and the deposition carrier.

[0023] The outer wall of the baffle and the surface of the deposition carrier can have an angle of less than, greater than or equal to 90°.

[0024] The present invention therefore provides an evaporation deposition apparatus that enables evaporation in a ballistic state, including a mechanical baffle surrounding the deposition surface, the mechanical baffle determining the incident gas flow on the surface and enabling good homogenization of gas diffusion toward the deposition substrate.

[0025] In the apparatus or method according to the invention:

[0026] The baffle has a geometry that allows the cavity and its elements or components to be observed from the same solid angle or from the most uniform solid angle possible at all points on the deposition surface; for example, the baffle has a truncated conical shape in which the axis of symmetry is perpendicular to the deposition surface and the base is located on or in the same plane as the deposition surface.

[0027] And / or the shape of the baffle can be generated by understanding and modeling the molecular flow in a ballistic state in a vacuum cavity;

[0028] And / or as viewed from the deposition surface, the baffle preferably has a uniform geometry. It has orifices to allow a flow of material emitted from the source or evaporation unit to pass through;

[0029] And / or seek to ensure that each point on the deposition surface observes substantially the same solid angle relative to the inner surface of the baffle. Calculating the solid angle allows for optimization of the baffle's geometry (wall height, diameter, orientation), thereby minimizing its variation on the deposition surface. Thus, for a deposition surface of, for example, 2 inches, better solid angle (and therefore flow rate) uniformity than 0.1% can be achieved, approaching 0.05%.

[0030] In the apparatus or method according to the invention, the baffle:

[0031] For example, it can be made of aluminum or stainless steel;

[0032] And / or has an axis of symmetry perpendicular to the deposition surface and centered on the deposition surface;

[0033] and / or has cylindrical or spherical symmetry;

[0034] And / or at least partially truncated conical, or even cylindrical;

[0035] And / or may include a short side portion or base portion having a first circular opening and a long side portion having a second circular opening opposite the short side portion. In some embodiments, the diameter of the second circular opening may be larger than the diameter of the first circular opening, or in other embodiments, the diameter of the second circular opening may be smaller than the diameter of the first circular opening.

[0036] The baffle extends from the deposition carrier by a length, for example, between 40 mm and 200 mm, with the upper limit set according to the size of the deposition apparatus. The optimal value for this length can be sought based on other parameters, such as, for example, the cone angle of the baffle and / or the opening at the top.

[0037] And / or the baffle may further include a diaphragm, such as a diaphragm made of stainless steel or aluminum, disposed at the inlet of the baffle (on the side opposite to the deposition carrier). Such a diaphragm allows for improved uniformity of gas diffusion toward the deposition substrate.

[0038] The device according to the invention may include two chambers, or the method according to the invention may use two chambers:

[0039] The first chamber includes a unit for evaporating material toward the deposited substrate;

[0040] The second chamber includes a deposition carrier, a baffle, and a unit for injecting gas into the chamber.

[0041] The two chambers are separated by a wall with openings to allow the evaporated material to flow through toward the deposition carrier.

[0042] The apparatus according to the invention may further include, or the method according to the invention may be used:

[0043] The suction unit is used to achieve up to 10 in the chamber before gas injection. -6 millibars or 5 x 10 -7 millibars or 10 -7 Millibar pressure; for example, these suction units allow for a pressure of 10 mbar or less before gas injection. -7 Pressure in the millibar range, or reaching between 10 and 10 on each side. -8 millibars or 2×10 -8 The ratio of millibars to the other side is 8×10. -8 millibars or 10-7 Pressures between millibars; during gas injection, these units allow for maintaining a pressure less than or equal to 1 × 10⁻⁶ within the deposition chamber or structure. -5 millibars or 5×10 -5 Millibar pressure;

[0044] And / or a gas supply unit for injecting gas into the cavity; the gas is a reactive gas that will react, or it reacts with the evaporated material.

[0045] According to a particular embodiment, the evaporation unit includes at least one electron gun or at least one resistor. These are, for example, co-evaporation units.

[0046] The present invention also provides a vacuum deposition method, which, for example, uses the apparatus according to the invention, wherein:

[0047] The deposition substrate is positioned on a deposition carrier of a deposition cavity or structure; the deposition substrate has, for example, a deposition surface with a diameter of at least 2 inches or 3 inches;

[0048] The cavity or frame is aspirated to a depth of less than or equal to, for example, 1 × 10⁻⁶. -5 millibars or 5×10 -5 millibars or 10 -6 millibar pressure, for example at 10 -7 Pressure in the millibar range, or being drawn to a level between 10 and 10. -8 millibars or 2×10 -8 The ratio of millibars to the other side is 8×10. -8 millibars or 10 -7 Pressure between millibars;

[0049] Less than or equal to 1×10 -5 millibars or 5×10 -5 At a pressure of millibars, the reactive gas is injected into the chamber using a gas injection unit, and the material is evaporated toward the deposition substrate using an evaporation unit.

[0050] Units forming baffles around a deposition substrate, these baffle-forming units extending from the substrate or deposition carrier, have an axis XX' forming a rotational or rotational symmetry axis, which is perpendicular to the surface of the deposition carrier and preferably centered on the surface.

[0051] The baffles form units that surround and / or enclose the deposition surface, except for holes or openings positioned to face the source or evaporation unit.

[0052] The apparatus or method according to the invention enables vacuum deposition in a ballistic state. The injected reactive gas constitutes the majority of the cavity (with less than 1% residual gas present).

[0053] The reactive gas injected into the cavity is, for example, molecular oxygen (oxygen gas), molecular nitrogen (nitrogen gas), or hydrogen or hydrogen gas.

[0054] For example, the material facing the deposition substrate can be evaporated by heating, such as using an electron gun or the Joule effect.

[0055] The material being evaporated is a material that is in a solid state at ambient temperature. Examples include aluminum, chromium, titanium, silicon, or transition metals. The reactant gas is in a gaseous state at ambient temperature and pressure.

[0056] The method according to the invention enables the deposition of, for example, titanium nitride (TiN), niobium nitride (NbN), aluminum nitride (AlN), titanium dioxide (TiO2), alumina (particulate aluminum-GrAl- or Al2O3), or silicon hydride (SiH).

[0057] The method according to the invention enables the production of deposits with thicknesses, for example, between 1 nm and 200 nm.

[0058] In the method according to the invention, the stoichiometric homogeneity of the sediment is preferably greater than or equal to 99.8% on a surface with a diameter of, for example, 2 inches.

[0059] A reactive gas that reacts with the evaporated material is injected using the apparatus or method according to the invention.

[0060] Gas injection pipes or units for injecting gas into the cavity are located between the evaporation unit and the deposition carrier.

[0061] The compounds or reactive gases used within the scope of this invention (apparatus or method) are in a gaseous form at ambient temperature and pressure. At ambient temperature, atoms or molecules of such compounds or gases deposited on the walls of a deposition chamber or structure are retained for only a short time τ (τ << considered to be the deposition time of the thin film in this application) before being re-emitted from the walls into the chamber, unless they react (e.g., oxidize) with another atom or molecule present on the wall during that time, thereby altering their chemical properties.

[0062] This invention (apparatus or method) achieves a so-called ballistic state: a gas flow state in which the path of freedom of the present matter is very large relative to the size of the cavity. This means that when the present matter moves within the cavity, they do not collide with each other, or collide very rarely.

[0063] This invention uses an evaporation technique in which the source of the element to be evaporated is heated, for example by an electron beam or by the Joule effect.

[0064] In this application, the ambient temperature is considered to be 300 K and the ambient pressure is 1 bar. Attached Figure Description

[0065] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0066] Figure 1A An isometric view of a shielding cover according to the invention is shown, the shielding cover comprising a conical baffle and a diaphragm;

[0067] Figure 1B A view of a shield according to the invention is shown, the shield being located on a deposition carrier and facing a gas distribution pipe;

[0068] Figure 2 The shielding cover according to the invention is schematically shown in a suitable position within the deposition chamber;

[0069] Figure 3A , Figure 3B and Figure 3C Different optimization results are shown;

[0070] Figure 4A , Figure 4B and Figure 4C The diagram shows different distributions of surface resistivity for aluminum evaporation on a wafer in the presence of an oxygen flow under three different configurations: without the baffle according to the invention ( Figure 4A ), and has a conical baffle according to the present invention ( Figure 4B ), and a conical baffle with a diaphragm according to the present invention ( Figure 4C );

[0071] Figure 5 It shows that according to Figures 4A to 4C The oxygen flow distribution on the surface of the wafer is reconstructed from the resistance measurement results shown.

[0072] Figure 6 It shows Figures 4A to 4C The relative standard deviation of oxygen distribution under the three configurations shown. Detailed Implementation

[0073] Figure 1A A baffle or shield 2 according to an embodiment of the present invention is shown schematically.

[0074] The baffle or shield 2 mainly comprises a truncated conical sidewall, which in this example extends between a short side or base 21 and a long side 22. The short side or base 21 has a first circular opening 23, and the long side 22 has a second circular opening 25 with a diameter greater than that of the circular opening 23. The shield 2 has rotational symmetry about the axial direction XX'.

[0075] In the illustrated configuration, the shield 2 also includes a diaphragm 10, which comprises a central circular opening 11 with a diameter smaller than that of the opening 25, thus keeping a portion of the opening 25 open. As will be seen below, the baffle according to the invention may or may not include such a diaphragm 10. The size of the diaphragm is chosen to avoid clogging the inlet of the evaporated material and thereby avoids the risk of reducing the uniformity of material deposition.

[0076] The short side 21 may be provided with a base 12, which in this example is generally formed as a circular ring, wherein a device 8 is provided to secure the baffle in the deposition chamber of the evaporator.

[0077] The angle α between the outer wall 22e of the baffle and the plane passing through the base 21 is less than 90°; this angle can be, for example, between 30° and 80°; preferably, this angle is less than 60°. The complementary angle β (180° - α) between the inner wall 22i of the baffle and the plane is greater than or equal to 90°, and this complementary angle is, for example, between 100° and 150°. If β = 90°, the baffle is cylindrical. Figure 1A The example baffle shown converges toward the deposition area, but alternatively, it can also be divergent or cylindrical. For example, in another configuration (not shown), the side at the base 12 is a long side with a first circular opening, while the opposite side has a second circular opening with a diameter smaller than (or even equal to) the diameter of the first circular opening; in the case of a divergent cone, the aforementioned angles must be negative.

[0078] The angle α of the baffle can be optimized so that each point on the surface of the deposition region (basically located at the center of the base 21) observes the inner surface 22i of the baffle 2 and the inner surface 10i of the diaphragm 10 at approximately the same solid angle (as shown in...). Figure 2 (See below for further details) Figure 1B (Explanation).

[0079] Figure 1B A baffle 2 is shown around a region on a carrier (or plate) 32 according to an embodiment of the invention, wherein a “wafer” (or deposition substrate) 33 (e.g., a wafer with a diameter of 2 inches or larger) can be positioned, and various materials can be deposited on its surface by evaporation. The remainder of the evaporator deposition chamber is not shown except for a gas injection conduit 41, which must be combined with the material to be deposited (as shown in the examples above and below). This conduit is provided with several orifices to allow gas injection, preferably in a first-moment distribution having rotational symmetry about axis XX'. The baffle has a height h, which can also be optimized according to other geometric parameters of the baffle 2 and the diaphragm 10 and is constrained by the geometry of the deposition structure.

[0080] It is generally believed that a larger height h produces better uniformity. The following section combines... Figures 3A to 3C Here is an example to describe the optimization of the dimensions of baffle 2.

[0081] However, the size (height, angle) of the baffle must also be selected based on the available volume inside the cavity.

[0082] Figure 2 The proper position of baffle 2 within the deposition chamber of evaporator 30 is shown. (Example) Figure 1A As shown, a baffle extends from the carrier 32; it is fastened to or abuts against the carrier 32 around a region in which a “wafer” (or deposition substrate) 33 (e.g., a wafer with a diameter of 2 inches or greater) can be positioned and on which (various) materials will be deposited by evaporation. The axis XX' of the baffle is aligned with the central axis of the evaporator.

[0083] Wall 42 separates the two chambers 38 and 40; it should be noted that a single chamber is also suitable, but the advantage of having two chambers is that samples can be aspirated more quickly (in smaller volumes) and the material source can be avoided with each sample introduction.

[0084] The first chamber 39 allows a source 34 of material to be deposited on the wafer to be positioned within the deposition chamber. The first chamber 39 also includes a heating unit 36 ​​(e.g., a resistor or an electron gun). The first chamber 39 is separated from the second chamber 40 by a wall 42, with an aperture 43 formed in the center of the wall 42, thereby allowing the flow 44 of the material to be deposited from the source 34 to the deposition wafer 33 when the heating unit 36 ​​is activated.

[0085] The carrier 32 and the shield 2 are located in a second chamber 40, which is separated from the first chamber by a wall 42. Therefore, it is in this second chamber that the wafer 33 can be disposed for deposition on its surface.

[0086] Evaporator 30 is connected to suction unit 50, which allows maintaining a temperature of less than or equal to 10 within the cavity or individual chambers. -5 Millibar pressure. For example, perform suction up to 10. -7 Millibars, then gas can be injected to bring the pressure up to 4 × 10⁻⁶. -5 millibars (maximum), even reaching 10 -5 Millibars. These values ​​are not absolute; everything depends on the intended use of the device. Although the path of freedom is quite large relative to the cavity size, it is a ballistic state, which is preferred for evaporation deposition.

[0087] For example:

[0088] The cavity is aspirated to a depth of less than or equal to, for example, 1 × 10⁻⁶-5 millibars or 5×10 -5 millibars or 10 -6 millibar pressure, for example at 10 -7 Pressure in the millibar range, or being drawn to a level between 10 and 10. -8 millibars or 2×10 -8 The ratio of millibars to the other side is 8×10. -8 millibars or 10 -7 Pressure between millibars;

[0089] Then, the reactive gas is injected into the cavity using a gas injection unit, and the material is evaporated toward the deposition substrate using an evaporation unit, while the pressure in the cavity is maintained at less than or equal to 1 × 10⁻⁶. -5 millibars or 5×10 -5 millibar.

[0090] Chamber 40 also includes units 41 for injecting gas, which may take the form of, for example, circular pipes (or “spray heads”) with multiple orifices, allowing for the homogenization of the gas inlet angle. These units 41 are positioned between the evaporator 30 and the deposition carrier 32. Other units for injecting gas could be used, such as pipe inlets, but this would result in gas atoms having the same first moment, or preferably the same orientation, and originating from the same location, which is detrimental to the homogenization of the gas inlet angle. These arrangements allow a flow 46 of gas (e.g., oxygen) to be injected into chamber 40 during evaporation operations. These units 41 are provided, for example, via assembly 60, which includes, for example, a high-pressure gas reservoir and a pressure-reducing valve. A flow meter may also be provided to regulate the supply gas flow rate. All these components may be connected to one or more pipes.

[0091] The injected gas is a reactive gas, which will react with the evaporated material. The reactive gas is in a gaseous state at ambient temperature and pressure.

[0092] When the cavity is under very low pressure obtained through unit 50, the gas atoms or molecules have a very large mean free path relative to the size of the cavity (typically a few meters in the pressure range used), so no collisions occur between the gas atoms or molecules. Once emitted into the cavity, they are thus adsorbed onto the inner wall 40i of the cavity 40.

[0093] When baffle 2 and diaphragm 10 are absent, a small proportion of the incident molecules on the wafer originate directly from the orifice of pipe 41, while the vast majority originate from the walls of the cavity and the objects located within it (in... Figure 2 Approximately 90% of the geometric shapes shown are represented.

[0094] When the baffle 2 and the diaphragm 10 are installed, some atoms or molecules adsorb onto the inner wall 22i of the baffle 2 and the inner wall 10i of the diaphragm 10. Essentially, it is these atoms or molecules 48, 52 originating from the inner wall 22i and the inner wall 10i of the diaphragm 10 that are released or diffused toward the surface of the wafer 33 for deposition thereon. However, as explained below, the shape of the baffle 2 homogenizes this diffusion.

[0095] The rotational symmetry of the shield 2 (whether or not it has a diaphragm 10) ensures good diffusion uniformity of the atoms of molecules adsorbed against the inner wall 22i and the inner wall 10i of the diaphragm 10 toward the wafer 33. The same solid angles of the baffle and the diaphragm are observed at two different points on the wafer. These two points will not observe the same walls in the same way, but in doing so, the same surface integral is observed. Therefore, the solid angles observed from the wafer are considered to allow for optimization of the baffle's geometric parameters (diaphragm angle α, height h, diameter φ) by examining the same solid angles of the baffle's inner wall that are approximately observed at each point on the wafer.

[0096] Figures 3A to 3C The standard deviation of the solid angle of the baffle across the entire 2-inch wafer is shown as a relative variation of angle α and / or height h (baffle geometry is...). Figure 1A (Geometry of the baffle), assuming a 3-inch diaphragm. For each value of α, an optimal height can be found to minimize the variation in solid angle, and thus the variation in gas flow. Overall, it is evident that increasing the baffle height and decreasing the angle α (which corresponds to maximizing the conical opening) makes sense; however, as... Figures 3A to 3C As shown, there exists a wide range of values ​​for α and h where the relative changes remain below 0.1%. In summary, it is preferable to select geometric values ​​that are compatible with the cavity of the depositional structure.

[0097] More specifically, for Figures 3A to 3C The following is a commentary:

[0098] Figure 3A The relative standard deviation of the total solid angle of the baffle, as observed from a 2-inch deposition surface, is shown in the configuration of the evaporator (Plassys MEB 550S model). This relative standard deviation is based on the baffle's cone angle and height (assuming the geometry shown) for three values ​​of height h (50 mm, 70 mm, and 100 mm). The optimal angle is the angle with the smallest standard deviation (indicating a consistent solid angle); the geometry is as shown... Figure 1A The geometry shown includes the cone and the diaphragm. Therefore, there are four geometric parameters: h, alpha (α), the diameter of the base 21, and the diameter of the diaphragm 10. For the case where the diameters of the base and the diaphragm are equal to 3 inches (= 7.62 cm), alpha is adjusted while h is fixed. Figure 3A),vice versa( Figure 3B ).

[0099] Figure 3B The diagram shows the relative standard deviation of the solid angle of the baffle as observed from a 2-inch deposition surface in an evaporator configuration (Plassys MEB 550S model). This relative standard deviation is based on the baffle height (assuming the same geometry as presented above) for four typical conical angle values: 30°, 40°, 50°, and 70°. The optimal height is the one with the smallest standard deviation (indicating a consistent solid angle).

[0100] Figure 3C The relative standard deviation of the solid angle of the baffle, as observed from the 2-inch deposition surface, is shown in an evaporator configuration (Plassys MEB 550S model). This relative standard deviation is based on the baffle height and the baffle cone angle α (which still exhibits the same geometry as described above). Only values ​​of h and α with a relative standard deviation less than or equal to 0.1% are represented here, which reflects the equivalent flow uniformity.

[0101] Figures 4A to 4C The diagram illustrates different surface resistivity (Rc) distributions of 30 nm thick deposits produced by aluminum evaporation on wafer 33 in the presence of an oxygen stream (particulate aluminum - GrAl) under three different evaporator configurations. In all three configurations, oxygen is introduced into the deposition chamber via a tube 41 bent into a circle parallel to the wafer plane. The tube 41 has uniformly spaced holes, the axes of which are oriented towards the edge of the 2-inch wafer. It should be noted that these holes have a diameter dispersion of approximately 5% associated with their fabrication method. This distribution system allows the density and first-order kinetic moment of the incoming gas to be substantially consistent.

[0102] In the first configuration ( Figure 4A Under these conditions, deposition was performed without the baffle according to the invention. Significant non-uniformity of resistance (Rc) was observed, varying by more than two times on the wafer surface.

[0103] The second configuration ( Figure 4B Under these conditions, deposition is performed with a truncated conical baffle 2 without a diaphragm according to the invention. The resistivity non-uniformity on the wafer surface is reduced to 60%.

[0104] In the third configuration ( Figure 4C Under the condition that the deposition occurs in the presence of a truncated conical baffle 2 with a diaphragm 10 according to the invention (e.g., as shown in the figure below), the deposition occurs in the presence of a truncated conical baffle 2 with a diaphragm 10 according to the invention (e.g., as shown in the figure below). Figure 1A and Figure 2This was performed under the condition shown in Figure A. This time, the non-uniformity on the wafer surface was only 10%. These distribution plots show the overall resistance uniformity via a minimum-maximum scale of Rc (on the right side of each plot), with Rc encoded in grayscale (…). Figure 4A The range is from 350 Ω to 850 Ω. Figure 4B The range is from 155 Ω to 280 Ω. Figure 4C (The resistance values ​​range from 204 Ω to 231 Ω). Therefore, the information that can be gleaned from these graphs is about the distribution of resistance values: the finer the graph, the more uniform the distribution, and the 2D distribution graph allows for visualization of oxygen distribution. Figure 4C In it, we see the ideal, expected cylindrical symmetry. Figure 4A and Figure 4B The presence of a lateral gradient—while the gas distribution exhibits cylindrical symmetry—indicates that, due to a lack of uniformity in aperture or orientation, there are objects that release more oxygen to some locations than others, or that the distribution releases more gas on one side than the other.

[0105] The resistance variations observed in these figures originate from the non-uniformity of the vast majority of the gas flow reaching the wafer.

[0106] Three possible factors causing non-uniformity of oxygen deposited on the wafer were identified: gas distribution system (e.g., due to irregular hole orientation and diameter in the tubes), deposition chamber visible from the wafer (e.g., suction holes, quartz scales, baffles that allow deposition to be opened and stopped, deposition plate mounting arms, etc.), or non-uniformity of the solid angle of the baffles (when present) as observed from the wafer.

[0107] The impact of each factor can be determined by comparison: through the first configuration ( Figure 4A ) and the second configuration ( Figure 4B A comparison between the two, using the shield 2 according to the invention, makes it possible to conceal lateral non-uniformities (objects, walls, holes). Through the second configuration ( Figure 4B ) and the third configuration ( Figure 4C The comparison between the two configurations shows that using the baffle 2 with diaphragm 10 according to the invention reduces the non-uniformity of the gas injection tube and the influence of most of the horizontal walls of the cavity (parallel to and facing the wafer). The third configuration ( Figure 4C The variation in residual resistance under the wafer is attributed to the non-uniformity of gas density and first-order kinetic moment, as well as the non-uniformity of the solid angle of the baffle observed from the wafer.

[0108] The distribution patterns in these three figures were validated through both experiments and simulations. Under the same configuration, the gradients observed from one deposition to another are reproducible.

[0109] These distribution maps show that:

[0110] Without using the baffle according to the invention, there is a very prominent asymmetry ( Figure 4A Clearly, the observed distribution reflects the asymmetry within the evaporator, which is caused by the different components (mentioned above) placed within it.

[0111] In the case where the baffle according to the invention is used but without a diaphragm (this is) Figure 4B (In the case of [the situation]), a better distribution can be achieved, but residual lateral gradients remain;

[0112] When the shield 2 and the diaphragm 10 are used in combination, the resulting deposits exhibit excellent uniformity. Figure 4C It also has rotational symmetry.

[0113] To accurately characterize the uniformity of gas flow, the dependence of the surface resistance of the deposited thin film (e.g., GrAl) on the gas flow during deposition can be utilized.

[0114] To characterize this dependence, a large number of n (n > 50) thin films were first deposited under identical conditions (identical thickness, e.g., 30 nm; identical evaporation rate, e.g., 1 nm / s; identical gas supply configuration, i.e., no baffle 2), but with varying gas flow rates controlled by a mass flow meter. To prevent uniformity issues, only the resistance value measured at the center of the plate was used. This statistical data allowed for the definition of an average curve representing the average surface resistance of the film as a function of the oxygen flow. Thus, when the surface resistance was measured by a two-shot method, a flow rate value, termed the effective gas flow rate, could be assigned to it. This enabled the quantification and comparison of gas flow rate uniformity on deposits with different resistance values, optionally performed under different conditions. To ensure this and validate the method, it was measured that the effective flow rate distribution reconstructed in this way from the resistance profile on the 2-inch wafer exhibited the same relative standard deviation (indicating the same relative gas flow rate non-uniformity) under the same spray configuration, regardless of the average flow rate.

[0115] Figure 5 It shows Figures 4A to 4C The effective flow distributions for each sediment shown (distribution 5a, distribution 5b, and distribution 5c correspond to respectively) Figure 4A , Figure 4B , Figure 4C (The situation).

[0116] Figure 6 It shows Figures 4A to 4C The relative standard deviation of traffic distribution under the above three configurations.

[0117] These figures illustrate that the gas distribution on the wafer surface was improved when the baffle was installed.

[0118] exist Figure 5 and Figure 6 It can be observed that when a baffle is introduced and then a diaphragm is introduced, the effective flow distribution (indicating the gas uniformity in the deposited film) is improved, and this improvement is not an artifact caused by changes in the absolute flow value.

[0119] Figure 6 The relative gas inhomogeneity on the 2-inch surface was quantified: without a baffle, the relative gas inhomogeneity was greater than 0.8% (which would result in a resistance change of more than twice for GrAl with a surface resistivity of around 500 ohms), and with the version tested with a baffle, the relative gas inhomogeneity was reduced to less than 0.2% (which would result in a resistance change of less than 2% for GrAl with a surface resistivity of around 200 ohms).

[0120] The baffle version used in this experiment is not optimal in terms of solid angle: its height h of 60 mm and its angle α of 51° predict a solid angle non-uniformity of 0.8%, and for this height, the optimal angle is 40°, which achieves a non-uniformity of 0.04%, an additional reduction of 20 times.

[0121] This optimization is based on the solid angle of the baffle observed on the wafer, but ignores the variation in gas density adsorbed on the baffle walls; for example, it can be expected that fewer molecules accumulate on the inner surface of the diaphragm compared to the inner surface of the cone, which is directly observed as part of the cavity; or it can be expected that more molecules accumulate at the edge of the opening 11 of the diaphragm compared to the corner of the cone's junction. Therefore, the density of adsorbed molecules may affect the calculation of the integral of the solid angle, but this depends on the unknown precise parameters of the cavity and gas distribution. Thus, this solid angle optimization method provides a preliminary approach to baffle design for empirical improvement.

[0122] This invention enables control of the incident gas flow (reactive gas) on a deposition surface within a vacuum chamber. Specifically, this invention enables control of the geometry of the emission surface of the chamber, which has a non-zero solid angle as observed through the deposition surface.

[0123] This invention can be applied, for example, to the formation of oxides of deposited elements in the presence of oxygen: aluminum produces granular aluminum or aluminum oxide Al2O3; chromium produces Cr2O3; titanium produces TiO2; and generally, transition metals produce thin magnetic films.

[0124] The present invention is also applicable to the formation of hydrides and nitrides of deposited elements in the presence of nitrogen or hydrogen: for example, in the presence of nitrogen, titanium or niobium produces TiN or NbN; for example, in the presence of hydrogen, silicon produces SiH.

[0125] This invention enables the homogenization of a gas flow injected into a vacuum cavity in a ballistic or molecular state (where the molecular path of freedom is greater than the cavity size), typically in a range of less than or equal to 10. -4 millibars or 10 -5 Under millibar pressure.

[0126] This invention enables the production of uniform material deposits (in stoichiometry) on a surface with a diameter, for example, greater than 2 inches, in the presence of a reactive gas and by evaporation, for example, via an electron gun or the Joule effect.

[0127] In particular, this invention enables the production of oxides, nitrides, or hydrides through evaporation via an electron gun or the Joule effect in the presence of a flow of molecular oxygen, molecular nitrogen, or hydrogen. The deposited material will then have a uniform composition over a large surface area (e.g., a diameter greater than or equal to 2 or 3 inches), which is significant for certain applications, such as transition metal oxides in the field of magnetic sensors, or in the field of quantum technology (e.g., granular aluminum, or titanium nitride, or niobium nitride, or silicon hydride).

Claims

1. An apparatus (30) for performing vacuum evaporation deposition in a ballistic state, comprising: Deposition cavity or structure; Deposition carrier (32); An evaporation unit (36) is used to evaporate material toward the deposition substrate (32); Gas injection unit (41), the gas injection unit (41) is used to inject reactive gas into the cavity; The unit forming the baffle (2) around the deposition substrate extends from the deposition carrier and has an axis (XX') forming a rotational symmetry axis that is perpendicular to and centered on the surface of the deposition carrier. The gas injection unit (41) includes a pipe with a plurality of orifices that allows the injection of reaction gas in a first-order moment distribution that has rotational symmetry about the axis XX'.

2. The apparatus according to claim 1, wherein, The outer wall of the baffle has an angle of less than, greater than or equal to 90° with the surface of the deposition carrier (32).

3. The apparatus according to claim 1 or 2, wherein, The baffle is made of aluminum or stainless steel.

4. The apparatus according to any one of claims 1 to 3, wherein, The baffle is at least partially truncated conical in shape.

5. The apparatus according to any one of claims 1 to 4, wherein, The baffle includes a short side or base (21) having a first circular opening (23) and a long side (22) having a second circular opening (25), the diameter of which is larger than the diameter of the first circular opening (23).

6. The apparatus according to any one of claims 1 to 5, further comprising a diaphragm (10) disposed at the inlet of the baffle (2).

7. The apparatus according to claim 6, wherein, The diaphragm is made of stainless steel or aluminum.

8. The apparatus according to any one of claims 1 to 7, comprising two chambers (38, 40), the first chamber (38) comprising the unit (36) for evaporating material toward the deposition substrate (32), and the second chamber (40) comprising the deposition carrier (32), the baffle (2) and the unit (41) for injecting gas into the chamber, the two chambers being separated by a wall (42) having orifices (43) to allow a flow (44) of evaporated material to pass through.

9. The apparatus according to any one of claims 1 to 8, further comprising a suction unit (50) for achieving a maximum, less than, or equal to 5 × 10⁻⁶ m² in the chamber. -5 Millibar pressure.

10. The apparatus according to claim 9, wherein the suction unit (50) enables: Before injecting the gas, the temperature should be less than or equal to 10. -7 Pressure in the millibar range, or reaching between 10 and 10 on each side. -8 millibars or 2×10 -8 The ratio of millibars to the other side is 8×10. -8 millibars or 10 -7 Pressure between millibars; During evaporation, a concentration of less than or equal to 1 × 10⁻⁶ is achieved in the deposition cavity or structure. -5 millibars or 5×10 -5 Millibar pressure.

11. The apparatus according to any one of claims 1 to 10, further comprising a gas supply unit (60) for supplying gas to the unit (41) for injecting gas into the cavity.

12. The apparatus according to any one of claims 1 to 11, wherein the unit (36) for evaporating material toward the deposition substrate (32) comprises a unit for heating the material to be evaporated, such as an electron gun or at least one resistor (36).

13. The apparatus according to any one of claims 1 to 12, wherein the gas injection unit (41) for injecting gas is disposed between the evaporation unit and the deposition carrier.

14. A vacuum deposition method, said vacuum deposition method using the apparatus according to any one of claims 1 to 13, wherein: Position the deposition substrate (33) on the carrier (32); The cavity is aspirated to a depth of less than or equal to 10. -6 Millibar pressure; Gas is injected into the cavity using the gas injection unit (41); The material is evaporated towards the deposition substrate using the evaporation unit (36), and the pressure in the deposition chamber or structure is less than or equal to 5 × 10⁻⁶. -5 millibar.

15. The method according to claim 14, wherein, The gas injected into the cavity is molecular oxygen (oxygen), molecular nitrogen (nitrogen), or hydrogen or hydrogen gas.

16. The method according to claim 14 or 15, wherein, The material is evaporated toward the deposition substrate by heating, for example, using an electron gun or the Joule effect.

17. The method according to any one of claims 14 to 16, wherein, The material being evaporated is aluminum, chromium, titanium, silicon, or a transition metal.

18. The method according to any one of claims 14 to 17, wherein, Deposition of titanium nitride (TiN), niobium nitride (NbN), aluminum nitride (AlN), titanium oxide (TiO2), aluminum oxide (particulate aluminum-GrAl- or Al2O3) or silicon hydride (SiH) is performed.

19. The method according to any one of claims 14 to 18, wherein, The deposition substrate (33) has a deposition surface with a diameter of at least 5.08 cm or 7.62 cm.

20. The method according to any one of claims 14 to 19, wherein, Depositions with thicknesses between 1 nm and 200 nm were performed.

21. The method according to any one of claims 14 to 20, wherein, The evaporation occurs in a ballistic state.

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