CN108884556B

CN108884556B - Method for coating substrate and coater

Info

Publication number: CN108884556B
Application number: CN201680084352.7A
Authority: CN
Inventors: 朴炫灿; 任东吉; 格奥尔·曼克; 托马斯·格比利
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2016-04-21
Filing date: 2016-04-21
Publication date: 2020-11-03
Anticipated expiration: 2036-04-21
Also published as: CN112575301B; CN108884556A; CN112575301A; TWI627300B; WO2017182081A1; KR20180137536A; TW201805462A; KR102337787B1; KR20210014777A; JP2019519673A

Abstract

A method for coating a substrate (100) with at least one cathode assembly (10) is provided, the at least one cathode assembly (10) having three or more rotatable targets (20), the three or more rotatable targets (20) each including a magnet assembly (25) located therein. The method comprises the following steps: rotating the magnet assembly (25) to a plurality of different angular positions relative to a plane (22), the plane (22) extending perpendicularly from the substrate (100) to the axes (21) of respective ones of the three or more rotatable targets (20); and altering at least one of the following according to a function stored in the database or memory: power provided to the three or more rotatable targets (20), dwell time of the magnet assembly (25), and continuously changing angular velocity of the magnet assembly (25).

Description

Method for coating substrate and coater

Technical Field

The present application relates to a method for coating a substrate and a coater, and particularly to a method for sputtering a layer having high uniformity on a substrate and a coater for performing the method.

Background

The formation of layers with high uniformity (i.e. uniform thickness and electrical properties over extended surfaces) on a substrate is an issue in many technical fields. For example, in the field of Thin Film Transistors (TFTs), thickness uniformity and uniformity of electrical properties can be an issue for reliably fabricating display channel regions. Furthermore, a uniform layer generally facilitates manufacturing reproducibility.

One method for forming a layer on a substrate is sputtering. Sputtering has developed into a valuable process in a variety of manufacturing areas, such as in the manufacture of TFTs. During sputtering, atoms are ejected from the target material by bombarding the target material with energetic particles, such as excited (energized) ions of an inert or reactive gas. The ejected atoms can be deposited on a substrate, thereby forming a sputtered material layer.

However, forming layers by sputtering may have high uniformity specifications due to, for example, the geometry of the target and/or substrate. In particular, it may be difficult to achieve a uniform layer of sputtered material and ion bombardment over a wide substrate due to the irregular spatial distribution of sputtered material and ion bombardment. Providing multiple targets over the substrate may improve layer uniformity.

In view of the above, a new method and coater for coating a substrate that overcomes at least some of the problems in the art would be beneficial.

Disclosure of Invention

In view of the above, a method for coating a substrate and a coater are provided. Other aspects, advantages, and features of the disclosure are apparent from the claims, the description, and the drawings.

According to an aspect, a method is provided for coating a substrate with at least one cathode assembly having three or more rotatable targets each including a magnet assembly located therein. The method comprises the following steps: rotating the magnet assembly to a plurality of different angular positions relative to a plane extending perpendicularly from the base plate to an axis of a respective rotatable target of the three or more rotatable targets; and altering at least one of the following according to a function stored in the database or memory: power provided to the three or more rotatable targets, dwell time of the magnet assembly, and continuously changing angular velocity of the magnet assembly.

According to a further aspect, a coater for performing a method of coating a substrate is provided.

Further aspects, details, advantages and features are apparent from the dependent claims, the description and the drawings.

Embodiments also relate to apparatus for performing the disclosed methods, and include apparatus components for performing each of the method aspects described. These method aspects may be performed by hardware components, a computer programmed by suitable software, any combination of the two, or in any other manner. Furthermore, embodiments according to the present disclosure also relate to methods for operating the described apparatus. Methods for operating the described devices include method aspects for performing the functions of the devices.

Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described below:

fig. 1 shows a schematic cross-sectional view of a coater illustrating a method for coating a substrate according to embodiments described herein;

FIG. 2 shows a schematic cross-sectional view of a coater illustrating a method for coating a substrate according to embodiments described herein;

fig. 3a and 3b show schematic cross-sectional views of a coater illustrating a method for coating a substrate according to embodiments described herein;

FIG. 4 shows a schematic cross-sectional view of a coater illustrating a method for coating a substrate according to embodiments described herein;

FIG. 5 depicts variation of power as a function according to embodiments described herein;

FIG. 6 depicts a continuous variation of angular velocity as a function according to embodiments described herein;

FIG. 7 depicts additional variations in power as a function according to embodiments described herein;

FIG. 8 depicts additional variations in power as a function and variations in dwell time as a function according to embodiments described herein;

fig. 9 depicts a schematic cross-sectional view of three or more rotatable targets positioned for coating a substrate according to embodiments described herein;

FIGS. 10a and 10b depict a comparison of the thickness of films deposited by conventional processes and by the processes described herein; and

fig. 11a and 11b show a comparison of electrical properties of films deposited by conventional processes and by the processes described herein.

Detailed Description

Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. In the following description of the drawings, like reference numerals refer to like parts. Generally, only the differences with respect to the respective embodiments are described. The examples are provided by way of explanation of the disclosure and are not intended as limitations of the disclosure. Furthermore, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the present description include such modifications and variations.

The sputtering may be performed as diode sputtering or magnetron sputtering. Magnetron sputtering has the advantage, in particular, of a high deposition rate. Typically, the magnet is located in a rotatable target. A rotatable target as used herein is generally a rotatable curved (curved) target. By arranging the magnet or magnets behind the target, i.e. inside the target in the case of a rotatable target, these electrons are forced to move in the magnetic field and cannot escape in order to capture free electrons in the generated magnetic field, which is generated directly below the target surface. This generally increases the probability of ionizing gas molecules by several orders of magnitude. This in turn significantly increases the deposition rate.

The term "magnet assembly" as used herein is a unit capable of generating a magnetic field. Generally, the magnet assembly includes a permanent magnet. In particular, the magnet assembly may consist of permanent magnets. This permanent magnet is typically arranged in the rotatable target such that free electrons are trapped in a magnetic field generated below the surface of the rotatable target. In many embodiments, the magnet assembly includes a magnetic yoke. According to an aspect, the magnet assembly may be movable in the rotatable tube. By moving the magnet assembly, more particularly by rotating the magnet assembly along the axis of the rotatable tube as the center of rotation, the sputtered material can be directed in different directions.

The substrate may be continuously moved during coating ("dynamic coating"), or the substrate to be coated may be stationary during coating ("static coating"). According to embodiments described herein, the methods provide a static deposition process. In general, there may be a distinction between static deposition and dynamic deposition, particularly for large area substrate processing, such as processing of vertically oriented large area substrates. Dynamic sputtering is a tandem (inline) process in which the substrate is moved continuously or quasi-continuously adjacent to the deposition source. Dynamic sputtering is easier due to the fact that the process can be stabilized before the substrate moves into the deposition zone and then remains unchanged as the substrate passes through the deposition source. However, dynamic deposition can have other drawbacks, such as particle generation. This may be particularly the case for TFT backplane deposition. According to embodiments described herein, static sputtering may be provided, for example, for TFT processing, where the plasma may be stabilized prior to deposition on an initial substrate. It should be noted that the skilled person will appreciate that the different term static deposition process as compared to dynamic deposition process does not exclude any motion of the substrate. The static deposition process may include, for example, a static substrate position during deposition, an oscillating substrate position during deposition, a substantially fixed average substrate position during deposition, a dithering substrate position during deposition, a wobbling substrate position during deposition, a deposition process in which the cathodes are disposed in one chamber (i.e., a deposition process in which a predetermined set of cathodes are disposed in the chamber), a substrate position during layer deposition in which the deposition chamber has a sealed atmosphere with respect to an adjacent chamber, for example, by closing a valve unit that separates the chamber and the adjacent chamber, or a combination thereof. Thus, a static deposition process may be understood as a deposition process with a static substrate position, a deposition process with a substantially static substrate position, or a deposition process with a partially static substrate position. Thus, the static deposition process described herein can be clearly distinguished from the dynamic deposition process, rather than the substrate position for the static deposition process being completely free of any motion during deposition.

The terms "vertical direction" or "vertical orientation" are to be understood as being distinguished from "horizontal direction" or "horizontal orientation". That is, "vertical direction" or "vertical orientation" may relate to, for example, a substantially vertical orientation of the carrier and the substrate, wherein deviations from the exact vertical direction or vertical orientation by a few degrees, for example up to +/-10 ° or even up to +/-15 °, may still be considered as "substantially vertical direction" or "substantially vertical orientation". The vertical direction may be substantially parallel to gravity.

According to embodiments described herein, which may be combined with other embodiments described herein, substantially perpendicular may be understood as allowing +/-20 ° or less, for example +/-10 ° or less, from the perpendicular direction, particularly when referring to the substrate orientation. This offset may be provided, for example, because a slight offset from a vertically oriented substrate support may result in a more stable substrate position. However, such substrate orientation during deposition of organic material may be considered substantially vertical, which may be considered different from a horizontal substrate orientation.

The term "substantially perpendicular" may relate to a substantially perpendicular orientation, for example, of the axis of rotation and the support surface or substrate surface, wherein deviations of a few degrees from the exact perpendicular orientation, for example up to +/-10 deg. or even up to +/-15 deg., may still be considered "substantially perpendicular".

The examples described herein may be used to deposit on large area substrates, for example, for lithium battery fabrication or electrochromic windows. As an example, a plurality of thin film batteries may be formed on a large area substrate using a cooling device for processing layers comprising materials having a low melting temperature. According to some examples, the large area substrate may be a generation 4.5, a generation 5, a generation 7.5, a generation 8, or even a generation 10, the generation 4.5 corresponding to about 0.67m²Substrate (0.73m x 0.92.92 m), generation 5 corresponds to about 1.4m²Substrate (1.1mx 1.3m), generation 7.5 corresponds to about 4.29m²Substrate (1.95m x 2.2.2 m), generation 8 corresponds to about 5.3m²Substrate (2.16m x 2.46.46 m), generation 10 corresponds to about 9.0m²The substrate (2.88m × 3.13 m). Even higher generations such as 11 th generation, 12 th generation, etc. and corresponding substrate areas may be similarly applied.

The term "substrate" as used herein shall in particular comprise non-flexible substrates, such as glass plates. The present disclosure is not so limited and the term "substrate" may also include flexible substrates, such as webs (web) or foils.

Sputtering can be used in the production of displays. In more detail, sputtering may be used for metallization, such as creating electrodes or busbars. Sputtering is also used to create Thin Film Transistors (TFTs). Sputtering can also be used to create ITO (indium tin oxide) layers.

Sputtering can also be used to produce thin film solar cells. The thin film solar cell includes a back contact, an absorber layer, and a transparent conductive oxide layer (TCO). Typically, the back contact and TCO layers are created by sputtering, while the absorber layer is typically made in a chemical vapor deposition process.

In the context of the present application, the terms "coating", "depositing" and "sputtering" are used synonymously.

According to embodiments described herein, a method for coating a substrate is provided. The method may be performed by a coater. The coater includes at least one cathode assembly having three or more rotatable targets. The three or more rotatable targets, in particular each of the three or more rotatable targets, comprises a magnet assembly positioned therein. Typically, particularly during deposition of material on the substrate, the magnet assembly is rotated to a plurality of different angular positions relative to a plane extending perpendicularly from the substrate to the axis of a respective rotatable target of the three or more rotatable targets. In particular, for each of the plurality of different angular positions, the magnet assembly has an angle relative to a plane extending perpendicularly from the base plate to an axis of a respective rotatable target of the three or more rotatable targets. Typically, the three or more rotatable targets can each be a cylindrical sputtering cathode rotatable about an axis of rotation.

According to an aspect of the disclosure, at least one of: altering, according to a function, at least one of: power provided to the three or more rotatable targets, dwell time of the magnet assembly, and angular velocity of the magnet assembly, which varies continuously. That is, non-constant power is provided to three or more rotatable targets and/or different dwell times are used and/or varying angular velocities of the magnet assembly are used. Typically, the sputtering power, dwell time and/or angular velocity varies depending on the position of the magnet assembly. It is noted that the sputtering power generally corresponds directly to the power applied to the rotatable target. The relationship between the applied voltage and the sputtering power is linear in the first approximation (first approximation) except for a value close to 0V. Thus, a description of a change in power provided to three or more rotatable targets 20 may be understood as a change in voltage provided to three or more rotatable targets 20, and vice versa. In particular, in practice, the sputtering power may be varied, which may result in varying the power applied to the three or more rotatable targets. In general, the voltage may vary in the range from-200V to-800V, in particular in the range from-300V to-550V. Furthermore, it is also possible to vary the current provided to three or more rotatable targets. Thus, a description of a change in power provided to three or more rotatable targets 20 may be understood as a change in voltage provided to three or more rotatable targets 20 and/or a change in current provided to three or more rotatable targets 20, and vice versa.

According to embodiments described herein, varying the dwell time of the magnet assembly at the respective angular position is performed according to a discrete function and/or varying the angular velocity of the magnet assembly at the respective angular position is performed according to a continuous function.

According to embodiments described herein, a function for at least one of: a change in power provided to the three or more rotatable targets, a change in dwell time of the magnet assembly, and a continuous change in angular velocity of the magnet assembly. Then, performing a change of at least one of: the power provided to the three or more rotatable targets, the dwell time of the magnet assembly, and the angular velocity of the magnet assembly, the angular velocity of the magnet assembly being continuously varied or being continuously varied. In particular, the functions may be predetermined for a particular process, for example, and read from a database or memory before the particular process is performed. For example, different functions for different thicknesses of layers to be sputtered may be stored.

That is, the function is stored in the memory and is changed according to the function execution. In general, the function may be a function according to the angular position, i.e. the function may comprise different values for different angular positions. According to embodiments, the amount of material sputtered on the substrate at these angular positions may be determined by a function. That is, by including a value depending on the angular position, a layer having high uniformity can be sputtered on the substrate when the embodiment is carried out. In general, the function may be predetermined based on some trajectories.

Typically, the power provided to the three or more rotatable targets and one of the following varies according to a function: the dwell time of the magnet assembly and the continuously changing angular velocity of the magnet assembly. The angular velocity of the magnet assembly is continuously varied. In particular, the dwell time of the magnet assembly may vary according to a discrete function and/or the angular velocity of the magnet assembly may vary according to a continuous function. That is, the power provided to the three or more rotatable targets and the dwell time of the magnet assembly are varied according to a function, or the power provided to the three or more rotatable targets is varied according to a function and the angular velocity of the magnet assembly is continuously varied according to a function.

In the context of the present application, a continuous change of angular velocity may be distinguished from a discontinuous change of angular velocity, such as a stepwise (stepwise) change of angular velocity, i.e. from zero to a certain value, and vice versa.

When the embodiment mode is performed, formation of a layer having high quality over a substrate can be facilitated. In particular, the thickness of the deposition layer on the substrate may be highly uniform throughout the entire substrate. Furthermore, a high homogeneity of the layer (e.g. in terms of characteristics such as structure of the growing crystal, specific resistance (specific resistance) and/or layer stress) may be facilitated. For example, embodiments may be advantageous in practice for forming metallization layers in TFT production (e.g. for manufacturing TFT-LCD displays), as the signal delay therein depends on the thickness of the layers, such that non-uniformity of the thickness may cause the pixels to be powered on at slightly different points in time (energized). Furthermore, embodiments may be advantageous in practice for forming subsequently etched layers, since uniformity of layer thickness facilitates achieving the same result at different locations of the formed layer.

In the context of the present application, the three or more rotatable targets may each be a cylindrical sputtering cathode rotatable about an axis of rotation.

According to an embodiment, the coating system comprises a vacuum chamber in which the sputtering process is performed. The term "vacuum" in the present application means less than 10^-2A pressure of mbar (e.g. about 10 when it may be the case that the process gas flows in the vacuum chamber^-2mbar, but not limited thereto), or more particularly below 10^-3A pressure of mbar (e.g. about 10 when it may be the case that no process gas is flowing in the vacuum chamber^-5mbar, but not limited thereto). The coating system may form a process module that forms part of a manufacturing system. For example, the coating system may be implemented in a system for TFT manufacturing, or more particularly, a system for TFT-LCD manufacturing, such as, but not limited to, an AKT-PiVot PVD system (applied materials), Santa Clara, Calif. (CA)).

Fig. 1 schematically illustrates a substrate 100 positioned on a substrate holder 110. The rotatable target 20 of the cathode assembly 10 may be positioned over the substrate 100. A negative potential may be applied to the rotatable target 20. The magnet assembly 25 is schematically depicted as being positioned in the rotatable target 20. In many embodiments, an anode (not shown in fig. 1), to which a positive potential may be applied, may be positioned proximate to the rotatable target 20. The anode may have the shape of a rod, the axis of which is arranged generally parallel to the axis of an angled tube. In other embodiments, additional bias voltages may be applied to the substrate. As used herein, "positioning the magnet assembly" may be understood as operating the coater with the magnet assembly in a fixed position. In fig. 1, only one rotatable target 20 of three or more rotatable targets 20 is depicted. However, the same principles can be applied to two or more of the three or more rotatable targets 20.

A typical permanent magnet used in the embodiments described herein has a first magnet having a first magnetic pole and a pair of second magnets having a second magnetic pole. Each of these poles means a surface of the magnet assembly. These surfaces generally face the rotatable target from the inside.

According to embodiments described herein, the magnet assembly has a first magnetic pole in the direction of the first plasma track and a second magnetic pole in the direction of the second plasma track. The first magnetic pole may be a magnetic south pole and the second magnetic pole may be a magnetic north pole. In other embodiments, the first magnetic pole may be a magnetic north pole and the second magnetic pole may be a magnetic south pole. The pair of second magnets may have a second magnetic pole (e.g., a south pole or a north pole) in the direction of the first plasma track and a first magnetic pole (e.g., a north pole or a south pole) in the direction of the second plasma track.

Thus, each of the three magnets may be comprised of one or more sub-magnets, the three magnets may form two magnetrons, one magnetron forming the first plasma track and one magnetron forming the second plasma track. The first plasma track and the second plasma track may each have a primary direction of ejection of material from the target upon ion bombardment of the plasma. Thus, the magnet assembly 25 may comprise a main direction of material ejection, which may be a superposition of the main directions of the first and second plasma tracks.

In fig. 1, an enlarged view of the magnet assembly 25 is shown, depicting an exemplary situation described herein. As shown, the south pole is located in the middle, while the north pole frames the south pole therebetween.

The surface of the substrate may define a plane, which is horizontally disposed in the illustrated view. In the context of the present application, the angle of the magnet assembly is defined relative to a plane extending perpendicularly from the substrate 100 to the axis of the rotatable target 20. In embodiments described herein, this plane may also be perpendicular to the substrate holder. In the context of the present application, this plane may be referred to as a "substrate-target interconnection plane". In fig. 1, 3a and 3b, this plane is exemplarily depicted as a vertically arranged dashed line, having reference numeral 22.

Although the embodiments depicted in the figures illustrate the rotatable target 20 as being disposed above a horizontally disposed substrate 100, and the definition of the substrate-target interconnection plane is illustratively explained with reference to these embodiments, other orientations are possible. In particular, the orientation of the substrate may also be vertical as described herein. In particular, in view of large area coating, if the substrate is vertically oriented, the transfer and handling of the substrate may be simplified and made easy. In other embodiments, the substrate may even be arranged somewhere between the horizontal and vertical orientation.

According to embodiments described herein, magnet assembly 25 is rotatable to a plurality of different angular positions in which magnet assembly 25 has an angle relative to plane 22, plane 22 extending perpendicularly from substrate 100 to axis 21 of a respective rotatable target of the three or more rotatable targets. The angle of the angular position may be equal to or greater than-60 °, in particular equal to or greater than-40 °, typically equal to or greater than-15 ° and/or equal to or less than 60 °, in particular equal to or less than 40 °, typically equal to or less than 15 °.

Further, the magnet assembly 25 may have a starting or reference angle from which the magnet assembly 25 is rotated to a first angular position of a plurality of different angular positions. The starting angle may be non-zero, such as +/-5 ° to +/-15, relative to a plane 22 extending perpendicularly from the substrate 100 to an axis 21 of a respective rotatable target of the three or more rotatable targets 20. Further, the ranges described herein for the angular position may be relative to the starting angle. That is, the angular position may be measured relative to a starting angle, which may be zero or non-zero relative to a plane 22 extending perpendicularly from the substrate 100 to the axis 21 of a respective rotatable target of the three or more rotatable targets 20.

Typically, the rotatable target 20 has a cylindrical shape. To elaborate on the angular position of elements in the cylinder, such as the magnet assembly, cylinder coordinates may be used. In the present disclosure, angles are used to indicate position, taking into account the particular concern of angular position. In the present disclosure, the zero angle position shall be defined as the position in the rotatable target that is closest to the substrate. The zero angle position is thus generally located in the straight substrate target attachment plane 22.

As shown in fig. 2, the magnet assembly 25 may be positioned in an angular position having an angle a in the rotatable target 20. More particularly, the magnet assembly 25 can be positioned in a plurality of angular positions having an angle α in the rotatable target 20. That is, the magnet assembly 25 is rotatable to a plurality of different angular positions in which the magnet assembly has an angle α relative to a plane 22 extending perpendicularly from the substrate 100 to the axis 21 of a respective rotatable target of the three or more rotatable targets 20.

Fig. 3a and 3b exemplarily show a situation in which the magnet assembly 25 is rotated to a first angular position having a negative angle- α (see fig. 3a) and a second angular position having a positive angle α (see fig. 3b) of a plurality of different angular positions. Reference numeral 23 illustrates the direction of ejection of material from the magnet assembly 25.

For example, the magnet assembly 25 may be rotated to a plurality of angular positions at an angular velocity having an absolute value greater than zero. In particular, the magnet assembly may be rotated from one limit (e.g., an upper limit) of the range of the angle α to another limit (e.g., a lower limit) of the range of the angle α, and vice versa. Under the limit of the range, a diversion of the angular velocity can occur, i.e. the angular velocity can change sign (sign).

Alternatively, the magnet assembly 25 may be rotated from one angular position to another in a stepwise manner. That is, the magnet assembly 25 may rotate to one angular position where the magnet assembly 25 may remain stationary for a predetermined dwell time, and then rotate to another angular position where the magnet assembly 25 may remain stationary for the same or another predetermined dwell time. This stepwise motion may be repeated to rotate magnet assembly 25 to a plurality of different angular positions, such as four or more different angular positions.

In addition, the angle α may also indicate the main direction of material ejection. That is, material will be sputtered onto the substrate, particularly in the direction of the angle α. When changing the angular position of the magnet assembly, the main direction of the emission may be changed over the substrate 100.

In practicing an embodiment, the uniformity of the formed layer may be improved based on the power applied for each angular position, how long the magnet assembly stays at each position, and/or at what angular velocity the magnet assembly is rotated. In particular, sputtering may be performed when the magnet assembly dwells at an angular position for a dwell time.

In particular, by varying the power provided to the three or more rotatable targets according to a function, by varying the dwell time of the magnet assembly according to a function, and/or by continuously varying the angular velocity of the magnet assembly according to a function, the homogeneity and in particular the uniformity of the layer to be sputtered can be improved. Thus, by performing sputtering with varying time and/or power, homogeneity can be improved. In the case of varying the dwell time, the sputtering field can be switched off further during the movement (i.e. when the angular position is changed), so that the uniformity can be increased further.

Fig. 4 schematically illustrates in more detail a cathode assembly used in embodiments described herein. It will be understood that the elements depicted in fig. 4 may also be applied in the other embodiments described herein, in particular in the embodiments described with respect to fig. 1, 2, 3a and 3 b. As shown in fig. 4, a rotatable target 20 can be placed on the backing tube and the target material to be sputtered can be applied to the backing tube. To reduce the high temperature of the target due to the sputtering process, a tube of cooling material 40 may be provided on the inside of the rotatable target 20. Generally, water may be used as the cooling material. When the embodiments are implemented, a substantial portion of the energy input to the sputtering process, typically on the order of several kilowatts, is converted to heat in the target, which can be cooled as described herein. As shown in the schematic diagram of fig. 4, the magnet assembly may be positioned in the backing tube and the cooling material tube such that the magnet assembly may be moved therein to different angular positions. According to other embodiments, the entire interior of the target tube is filled with a cooling material, such as water.

The magnet assembly may be mounted on a shaft of the target tube. The pivotal movement described herein may be initiated by an actuator, such as an electric motor that provides a rotational force. In a typical embodiment, the cathode assembly is equipped with two shafts: a first shaft and a second shaft, a rotatable target tube being mounted on the first shaft. The first shaft rotates when the cathode assembly is in operation. A movable magnet assembly is typically mounted to the second shaft. The second shaft is movable independently of the first shaft, typically in a manner so as to allow the magnet assembly to move as described herein.

In the present disclosure, the figures depict a coater and a schematic cross-sectional view of an exemplary substrate shown. Generally, the cathode assembly 10 includes a rotatable target 20 that may have a cylindrical shape. In other words, when looking at the drawings, the rotatable target 20 extends out of the paper and into the tension. The same applies to the magnet assembly 25, the magnet assembly 25 also being only schematically illustrated as a cross-sectional element. The magnet assembly may extend along the entire length of the cylinder. For technical reasons, the magnet assembly typically extends for at least 100% of the length of the cylinder, more typically for at least 105% of the length of the cylinder.

Fig. 5 illustrates the change in power provided to three or more rotatable targets 20 as a function. In particular, the function may provide different power values for different angular positions. In the graph depicted in fig. 5, the vertical axis is the power U provided to the three or more rotatable targets 20 and the horizontal axis is the angle α.

As the distance from the magnet assembly 25 to the substrate 100 increases, the ion bombardment of the material ejected onto the substrate 100 decreases. While the distance between the magnet assembly 25 or the rotatable target 20 and the substrate 100 along a plane extending perpendicularly from the substrate 100 to the axis 21 of the rotatable target 20 may be constant, the distance traveled by material ejected from the rotatable target 20 to reach the substrate 100 increases with increasing value, or absolute value, of the angle α. Thus, a higher angle α deposits less material than a lower angle α.

Furthermore, as the value, or absolute value, of the angle α increases, the angle of incidence at which the material to be deposited reaches the substrate 100 increases, which reduces the energy of the ion bombardment. By controlling the local ion bombardment energy and intensity, this effect locally affects the structure, morphology and electrical or optical properties of the growing film.

According to an embodiment, the power provided to the three or more rotatable targets 20 is varied to compensate for the reduced material deposition at angular positions having a high angle α. In particular, the higher the angle α of the angular position, the higher the power provided to the three or more rotatable targets 20, and vice versa. When implementing embodiments, the uniformity of the layer to be deposited can be increased, in particular if the sputtering power changes over time while the magnet is moving.

As shown in fig. 5, the function for varying the power provided to the three or more rotatable targets 20 may be a symmetric function. Further, the function for varying the power provided to the three or more rotatable targets 20 may be an asymmetric function. For example, the function for varying the power provided to the three or more rotatable targets 20 may be a polynomial function, a trigonometric function, and/or a combination thereof. For example, the power may vary in a range from-2 kW to 20kW, in particular in a range from 5kW to 10 kW.

In addition, the magnet assembly 25 may continuously rotate ("rock") between a left maximum angle and a right maximum angle. However, as shown in fig. 6, in addition to varying the power, the angular velocity of the magnet assembly 25 may be continuously varied to increase the uniformity of the layer to be deposited. Furthermore, similar results with respect to uniformity may be obtained in practice when the angular velocity of the magnet assembly 25 is continuously varied instead of varying the power.

Given the relationship described herein between the value of angle α and the material deposited at angular positions having angle α, it may be advantageous to continuously vary the angular velocity of the magnet assembly in such a way that a smaller absolute value of angle α has a higher angular velocity than a larger absolute value of angle α. That is, the magnet assembly 25 rotates faster at a smaller absolute value of angle α than at a larger absolute value of angle α. Thus, by reducing the time, or effective residence time, for material to be deposited at angular positions having a smaller absolute value of angle α, a higher deposition rate at angular positions having a smaller absolute value of angle α can be compensated for, as compared to angular positions having a higher absolute value of angle α.

The function for continuously varying the angular velocity of the magnet assembly 25 may be a symmetric function. Further, the function for continuously varying the angular velocity of the magnet assembly 25 may be an asymmetric function. For example, the function for continuously varying the angular velocity of the magnet assembly 25 may be a polynomial function, a trigonometric function, and/or a combination thereof.

While the function for varying the power provided to the three or more rotatable targets 20 may be an upward opening function (upward opening function), i.e. having a larger value on the vertical axis for larger absolute values on the horizontal axis, the function for continuously varying the angular velocity of the magnet assembly 25 may be a downward opening function (downward opening function) having a smaller value on the vertical axis with respect to larger absolute values on the horizontal axis. For example, the angular velocity may be continuously varied in a range from 0,5 °/s to 500 °/s, in particular in a range from 2 °/s to 200 °/s.

Fig. 7 depicts further examples of functions for varying the power provided to three or more rotatable targets 20. In particular, fig. 7 depicts an asymmetric function for varying the power provided to three or more rotatable targets 20.

Further, fig. 7 depicts two different ways of varying the power provided to three or more rotatable targets 20. The solid lines represent continuous functions for varying the power provided to the three or more rotatable targets 20, while the individual points in the graph represent discrete functions for varying the power provided to the three or more rotatable targets 20. A continuous function may be used in the case of a rocking magnet assembly, i.e. the magnet assembly 25 is continuously rotated at a constant angular velocity or a continuously changing angular velocity. A discrete function may be used in the case of a stepwise rotation of the magnet assembly 25, i.e. a stepwise rotation of the magnet assembly 25 from one angular position to another.

The term "continuously changing" or "continuously changing" angular velocity of the angular velocity as used herein shall particularly be distinguished from a stepwise changing angular velocity in the case of a stepwise rotating magnet assembly 25. In particular, for stepwise rotation, the angular velocity is often zero when the magnet assembly 25 stays in an angular position and jumps to a predetermined value when the magnet assembly moves from an angular position to the next angular position. Such a movement is to be understood in particular as a non-continuous movement. Thus, the dwell time of the magnet assembly may be varied according to a discrete function, and/or the angular velocity of the magnet assembly may be varied according to a continuous function.

According to an embodiment, the discrete function comprises more than four steps (step). In particular, the more steps a discrete function has, the more the discrete function approximates a continuous function. Thus, for applying functions into a coater for performing the methods described herein, it may be advantageous to use discrete functions while increasing the number of steps to approximate a continuous function.

Fig. 8 depicts further examples of functions for varying the power provided to three or more rotatable targets 20 and examples of functions for varying the dwell time of the magnet assembly.

As outlined herein, the magnet assembly 25 dwells for a specific dwell time at each step of the stepwise rotation of the magnet assembly 25. By varying the dwell time for the stepwise rotation of the magnet assembly 25, a similar effect can be achieved as by continuously varying the angular velocity of the continuously rotating magnet assembly 25. In particular, the dwell time at the angle α of smaller absolute value may be lower than the dwell time at the angle α of larger absolute value. That is, the magnet assembly 25 dwells for a shorter amount of time at a smaller absolute value of angle α than at a larger absolute value of angle α. Thus, higher deposition rates at angular positions having an angle α with a smaller absolute value can be compensated by reducing the dwell time when depositing material at these angular positions compared to angular positions having an angle α with a higher absolute value. Thus, the function for varying the dwell time of the magnet assembly 25 may be an upwardly open function. For example, the residence time may vary in the range from 0.5s to 30s, in particular in the range from 2s to 10 s.

According to embodiments described herein, the power provided to the three or more rotatable targets 20 and one of the following may be varied according to a function: the dwell time of the magnet assembly 25 and the continuously changing angular velocity of the magnet assembly 25. That is, the power provided to the three or more rotatable targets 20 may be varied in the case of stepwise rotation along with the dwell time of the magnet assembly 25, and in the case of a rocking magnet assembly 25 along with a continuous change in the angular velocity of the magnet assembly 25. Fig. 8 depicts a combination of a change in power provided to three or more rotatable targets 20 and a change in dwell time. Thus, a function may depend on multiple variables, may be multidimensional, and/or include one or more sub-functions.

By combining power changes and time changes (dwell time or angular velocity), the uniformity of the layer to be deposited can be further increased. Furthermore, the power provided to the rotatable target 20 may be technically limited in the upper and/or lower range of power that may be provided to the rotatable target 20. For example, it may be contemplated to use values of power provided to the rotatable target 20 that are not technically specified for the cathode assembly 10. Thus, values of power provided to the rotatable target 20 that fall within a specified range may be used, and deviations from expected values may be compensated for by adjusting the values of dwell time or angular velocity. In particular, if the power provided to the rotatable target 20 is used for a particular angular position that is greater than the prescribed range, this deviation can be compensated by a longer dwell time for that particular angular position or a smaller angular velocity for that particular angular position, and vice versa. When implementing embodiments, high throughput may be achieved that reduces overall processing time and cost.

According to an embodiment, a process chamber is provided. In particular, the process chamber may be a vacuum process chamber. The process chamber may include at least one cathode assembly described herein. Further, the processing chamber may be configured to perform the methods for coating a substrate described herein. In general, a process chamber may be configured for coating a substrate at a point in time. A number of substrates may be coated one after the other.

According to an embodiment, the at least three rotatable targets may be arranged in a regularly arranged one-dimensional array of rotatable targets. Typically, the number of rotatable targets is between 3 and 20, more typically between 8 and 16.

According to an embodiment, the rotatable targets 20 may be equally spaced from each other. Typically, the length of the rotatable target 20 may be slightly longer than the length of the substrate to be coated. Additionally or alternatively, the region spanned by the rotatable target 20 may be slightly wider in width than the width of the substrate. "slightly" generally includes a range between 100% and 110%. Providing a slightly larger coating length/width helps to avoid boundary effects. Typically, the cathode assemblies are positioned equidistant from the substrate.

According to an embodiment, three or more rotatable targets 20 may be arranged along an arc. The arc shape may be such that the rotatable target 20 is positioned closer to the substrate 100 than the outer rotatable target 20. This is schematically depicted in fig. 9. Alternatively, the arc defining the position of the rotatable target 20 may also be such that the outer rotatable target 20 is positioned closer to the substrate 100 than the inner rotatable target 20. The scattering behavior depends on the material to be sputtered. Thus, providing the rotatable target 20 in an arc shape may actually further increase homogeneity, depending on the application, i.e. depending on the material to be sputtered. The direction of the arc may depend on the application.

Additionally or alternatively, three or more rotatable targets 20 may be arranged in a manner that the distance between two adjacent rotatable targets 20 varies from the inner rotatable target 20 to the outer rotatable target 20. For example, the distance between adjacent outer rotatable targets 20 may be greater than the distance between adjacent inner rotatable targets 20. Alternatively, the distance between adjacent outer rotatable targets 20 may be less than the distance between adjacent inner rotatable targets 20. By making the distance of the outer rotatable targets 20 smaller than the distance between adjacent inner rotatable targets 20, the outermost rotatable targets 20 move closer to the inner portion of the substrate. According to embodiments, less material may be wasted.

Further, fig. 9 depicts exemplary anode rods positioned between cathode assemblies, which may be used in some embodiments described herein.

According to an embodiment, the function for at least one of the following may be the same for all rotatable targets: variations in power provided to the three or more rotatable targets, variations in dwell time of the magnet assembly, and continuous variations in angular velocity of the magnet assembly. Alternatively, different functions may be used for different rotatable targets.

For example, different functions may be used for the outer or outermost rotatable targets 20 relative to the other rotatable targets 20. Since the outermost rotatable target 20 often sputters material on an area of the substrate 100 where the deposited layers are a superposition of material from fewer rotatable targets 20 than the inner area of the substrate 100, an asymmetric function may be used for the outer or outermost target 20 to compensate for this deviation in asymmetric deposition. Thus, the function may have a higher value with respect to power, a higher value with respect to dwell time, and/or a lower value with respect to angular velocity for a region in which the deposited layers are a superposition of material from fewer rotatable targets 20 than the inner region of the substrate 100.

In the context of the present application, an "outer" rotatable target may be understood as a rotatable target arranged close to the edge of the substrate, whereas an "inner" rotatable target may be understood as a rotatable target arranged close to the inner region of the substrate. In particular, when referred to as an "outer" rotatable target and an "inner" rotatable target, the "outer" rotatable target may be closer to the edge of the substrate than the "inner" rotatable target. Further, an "outermost" rotatable target may be understood as a rotatable target arranged closer to the edge of the substrate than an adjacent rotatable target.

Fig. 10a and 10b show a comparison of the thickness of films deposited by conventional processes and the processes described herein. The deposition is performed using a rotatable target disposed at the location of the solid line spaced from the substrate.

Fig. 10a schematically depicts the profiles of two films measured after deposition with a conventional process and with the process described herein. The y-axis represents a unit of measure for the thickness of the film, while the x-axis represents a unit of measure for the length of the substrate. As can be seen from fig. 10a, the film deposited by the process described herein has less deviation in thickness in the region between the rotatable targets 20 than in the region directly below the rotatable targets, as compared to the case of the conventional process.

FIG. 10b depicts a statistical analysis of the deviation in thickness of films deposited with conventional processes and with the processes described herein. As can be seen from fig. 10b, the deviation in thickness is higher for the conventional process depicted on the left side compared to the process described herein depicted on the right side. When the embodiment is carried out, the uniformity of the layer thickness can be increased.

Fig. 11a and 11b show a comparison of electrical properties of films deposited by conventional processes and using the processes described herein. The deposition is performed using a rotatable target disposed at the location of the solid line spaced from the substrate.

FIG. 11a depicts profiles of three films measured after deposition with two different conventional processes and with the processes described herein. The y-axis represents a unit of measure for the electrical properties of the film, while the x-axis represents a unit of measure for the length of the substrate. As can be seen from fig. 10a, the electrical properties of the films deposited by the process described herein are shown to be more constant, particularly overall, than is the case with conventional processes.

FIG. 11b depicts a statistical analysis of the deviation in electrical properties of films deposited by two conventional processes and by the processes described herein. As can be seen from fig. 11b, the deviation in electrical properties of the conventional process shown on the left and middle sides is higher compared to the process described herein shown on the right side. When the embodiment is carried out, uniformity of electrical properties of the deposited layer may be increased.

In the following, embodiments are described which result in particularly high homogeneity.

According to an aspect, a method is provided for coating a substrate with at least one cathode assembly having three or more rotatable targets, each of the three or more rotatable targets including a magnet assembly therein. The method comprises the following steps: rotating the magnet assembly to a plurality of different angular positions relative to a plane extending perpendicularly from the base plate to an axis of a respective rotatable target of the three or more rotatable targets; and altering at least one of the following according to a function stored in the database or memory: power provided to the three or more rotatable targets, dwell time of the magnet assembly, and continuously changing angular velocity of the magnet assembly.

According to an embodiment, a method is provided for coating a substrate with at least one cathode assembly having three or more rotatable targets each including a magnet assembly therein. The method comprises the following steps: rotating the magnet assembly to a plurality of different angular positions at which the magnet assembly has an angle relative to a plane extending perpendicularly from the base plate to an axis of a corresponding rotatable target of the three or more rotatable targets; reading from memory a function for at least one of: a change in power provided to the three or more rotatable targets, a change in dwell time of the magnet assembly, and a continuous change in angular velocity of the magnet assembly; and changing, according to the function, at least one of: power provided to the three or more rotatable targets, dwell time of the magnet assembly, and continuously changing angular velocity of the magnet assembly.

According to an embodiment, a method is provided for coating a substrate with at least one cathode assembly having three or more rotatable targets each including a magnet assembly therein. The method comprises the following steps: rotating the magnet assembly to at most four different angular positions in which the magnet assembly has an angle relative to a plane extending perpendicularly from the base plate to an axis of a corresponding rotatable target of the three or more rotatable targets; reading a function of the variation in dwell time of the magnet assembly at the more than four different angular positions; and varying the dwell time of the magnet assembly at the more than four different angular positions according to the function.

According to an embodiment, a method is provided for coating a substrate with at least one cathode assembly having three or more rotatable targets each including a magnet assembly therein. The method comprises the following steps: rotating the magnet assembly to more than four different angular positions relative to a plane extending perpendicularly from the base plate to an axis of a respective rotatable target of the three or more rotatable targets; and varying dwell times for the more than four different angular positions according to a function stored in a database.

Typically, the dwell time is different for each different angular position.

According to an embodiment, a coater for performing the method described herein is provided. The coater may include a memory from which functions may be read. In particular, the memory may include a look-up table (look-up) that stores functions.

The methods and coaters disclosed herein may be used to deposit materials on a substrate. More particularly, the method and coater provide high uniformity of the deposited layer and thus may be used in the production of displays, such as flat panel displays, e.g., TFTs. In the case of improved homogeneity, as a further effect thereof, the overall material consumption can be reduced, which is particularly desirable when expensive materials are used. For example, the proposed method and coater may be used to deposit an Indium Tin Oxide (ITO) layer in the production of flat panel displays.

According to certain embodiments, a conductive layer manufacturing process and/or system is provided that may be used to prepare electrodes or busbars (particularly in TFTs), comprising a method and/or system of coating a substrate according to embodiments herein, respectively. For example, but not limited thereto, such a conductive layer may be a metal layer or a transparent conductive layer, such as but not limited to an ITO (indium tin oxide) layer. For example, the methods described herein may be used to form an active layer in a TFT, such as an active layer made of or including IGZO (indium gallium zinc oxide).

For example, at least some embodiments of the present disclosure may achieve high uniformity with respect to the resistivity of an aluminum layer or an IGZO layer formed on a glass substrate. For example, thickness deviations between 0% and 2%, or even between 0.5% and ± 1.5% can be achieved over a substrate area of 406mm x 355 mm. Furthermore, a deviation of the electrical properties between 2% and 8% or even between 5% and 7% over a substrate area of 406mm x 355mm can be achieved.

In the present disclosure, at least some of the figures depict cross-sectional schematic views of a coating system and a substrate. At least some of the depicted targets are cylindrically shaped. In these figures, it should be noted that when looking at the figure, the target extends into and out of the paper. The same applies to magnet assemblies which are also only schematically shown as cross-sectional elements. The magnet assembly may extend along the entire length of the cylinder defined by the cylindrical target. For technical reasons, the magnet assembly typically extends for at least 100% of the length of the cylinder, more typically for at least 105% of the length of the cylinder.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A method for coating a substrate (100) with at least one cathode assembly (10), the at least one cathode assembly (10) having three or more rotatable targets (20) each including a magnet assembly (25) located therein, the method comprising:

-rotating the magnet assembly (25) to a plurality of different angular positions relative to a plane (22), the plane (22) extending perpendicularly from the base plate (100) to the axis (21) of a respective one of the three or more rotatable targets (20); and

-changing at least one of the following according to a function stored in a database or in a memory: a power provided to the three or more rotatable targets (20), a dwell time of the magnet assembly (25), and a continuously changing angular velocity of the magnet assembly (25), wherein the higher the power provided to the three or more rotatable targets, the higher the angle a of the angular position of the magnet assembly, and the dwell time of the angle a at smaller absolute values is lower than the dwell time of the angle a at larger absolute values.

2. The method of claim 1, wherein the power provided to the three or more rotatable targets (20) and one of the following is varied according to the function: the dwell time of the magnet assembly (25) and the continuously changing angular velocity of the magnet assembly (25).

3. The method of claim 1, further comprising:

-reading the function from the database or the memory for at least one of: a change in power provided to the three or more rotatable targets (20), a change in the dwell time of the magnet assembly (25), and a continuous change in the angular velocity of the magnet assembly (25).

4. The method of claim 1, wherein the function comprises a polynomial function or wherein the function comprises a trigonometric function.

5. The method of claim 4, wherein the function comprises a polynomial function and wherein the function comprises a trigonometric function.

6. The method of claim 1, wherein the function comprises a symmetric function.

7. The method of claim 1, wherein the function comprises an asymmetric function.

8. The method of any of claims 1 to 7, wherein the function determines an amount of material sputtered on the substrate (100) at the plurality of different angular positions.

9. The method of any of claims 1 to 7, wherein said function is used for sputtering a uniform layer on said substrate (100).

10. The method of any of claims 1 to 7, wherein the database comprises a look-up table.

11. The method of claim 8, wherein the function is a function that depends on the angular position.

12. The method of any of claims 1 to 7, wherein the function is a function dependent on individual rotatable targets (20) of the three or more rotatable targets (20).

13. The method of any of claims 1 to 7, wherein the magnet assembly (25) is rotated to the plurality of different angular positions at an angular velocity greater than zero.

14. The method of any of claims 1 to 7, wherein the function comprises a discrete function for varying the dwell time.

15. The method of claim 14, wherein the three or more rotatable targets (20) are rotated to the plurality of different angular positions in a stepwise manner according to the discrete function.

16. A coater for coating a substrate using the method of any one of claims 1 to 7.

17. A method for coating a substrate (100) with at least one cathode assembly (10), the at least one cathode assembly (10) having three or more rotatable targets (20) each including a magnet assembly (25) located therein, the method comprising:

-rotating the magnet assembly (25) to more than four different angular positions relative to a plane (22), the plane (22) extending perpendicularly from the base plate (100) to the axis (21) of a respective one of the three or more rotatable targets (20); and

-varying the dwell time of the magnet assembly (25) at the more than four different angular positions according to a function stored in a database or memory, wherein the dwell time of an angle a at the angular position of smaller absolute value is lower than the dwell time of the angle a at larger absolute value.

18. A coater for coating a substrate using the method of claim 17.