Sputtering device with gas injection assembly

A sputtering device includes a chamber; and a substrate transferring unit for loading a substrate into, or unloading the substrate from the chamber, the substrate transferring unit including a gas injection assembly forming a gas cushion between the substrate and an upper surface of the substrate transferring unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sputtering device, and more particularly, to a sputtering device with a gas injection assembly.

2. Description of the Related Art

In recent years, as cutting edge electronic devices, such as liquid crystal devices (LCD), become light and thin, components mounted in these devices also become smaller. So does the distance between adjacent components. In order to form a minute line between each component, various methods for forming a thin film have been proposed, for example a sputtering method. The sputtering method will be explained as follows.

First, a substrate on which a thin film is to be formed is loaded inside a vacuum chamber using a substrate transferring device. Then, a specific pressure and a voltage are supplied to an inactive gas inside the vacuum chamber, to generate a plasma around a target. Positive ions in the plasma formed around the target hit a surface of the target with an electric force. Also, the positive ions in the plasma transfer their kinetic energy to atoms on the surface of the target. When the transferred kinetic energy is greater than a bonded energy between the hit atoms, the atoms on the surface of the target are emitted from the target to be deposited onto the substrate.

FIG. 1is a schematic view of a magnetron sputtering device according to the related art. Referring toFIG. 1, a sputtering device1includes a vacuum chamber10, a vacuum pump30for maintaining a vacuum state inside the vacuum chamber10, a supporter40for supporting a substrate to be sputtered, and a plasma generating unit20for generating a plasma in the vacuum chamber10. The plasma generating unit20includes a target21formed of aluminum (Al), aluminum alloy (AlNd), chrome (Cr), molybdenum (Mo), etc., depending on the type of thin film to be formed, a cathode plate23for fixing the target21, a magnet25for generating a magnetic field at rear surfaces of the target21and the cathode plate23. The magnet25collects plasma between the target21and a substrate29into a periphery of the target21, and increases the ion generating ratio on the target21. The supporter40is provided with a supporting unit27. The substrate29is transferred by a substrate transferring robot hand (not shown) to adhere and be fixed to the supporting unit27.

An inactive gas, such as Ar, is injected into the vacuum chamber10of the sputtering device. Then, the inactive gas is discharged and excited into a plasma state, in which positive ions and negative ions are mixed together. Also, a DC pulse is applied to the cathode plate23. Thus, a negative high voltage is applied to the target21. Ionized inactive gas (Ar+) is accelerated towards the target21. Because the ions accelerated towards the target21have more than several tens of KeV of kinetic energy, the ions partially transfer their kinetic energy to atoms on the surface of the target when they collide with the target21. The atoms on the target21are freed from the surface of the target21in the form of negative ions. The negative ions from the target21are quickly deposited onto the substrate29by an electric field and a magnetic field, and form a film on the substrate29.

However, in the related art sputtering device, the substrate and the supporter are fixed to each other. The contact between the rear surface of the substrate and the supporter may cause a back scratch, or cause the substrate to break. Especially, during loading or unloading of the substrate into/from the vacuum chamber, when the substrate goes through a region where the vacuum state is replaced by an atmospheric state, the entire substrate is not constantly moved due to an unstable air stream. Accordingly, the substrate may be damaged. Moreover, in the related art sputtering device, a substrate that has been horizontally transferred by a substrate transferring unit, such as a robot hand, is again transferred onto a substrate supporter inside a sputtering chamber.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a sputtering device with a gas injection assembly that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a sputtering device capable of preventing a back scratch of a glass substrate.

Another object of the present invention is to provide a sputtering device capable of preventing damage to a fragile glass substrate.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a sputtering device includes a chamber; and a substrate transferring unit for loading a substrate into, or unloading the substrate from the chamber, the substrate transferring unit including a gas injection assembly forming a gas cushion between the substrate and an upper surface of the substrate transferring unit.

In another aspect, a substrate transferring unit for a sputtering device includes a supporting unit supporting a substrate; a fixing unit fixing one side of the substrate to the supporting unit; and a gas injection assembly on an upper surface of the supporting unit, the gas injection assembly forming a gas cushion between the substrate and the upper surface of the supporting unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2is a view of an exemplary substrate transferring unit according to an embodiment of the present invention. Referring toFIG. 2, a substrate transferring unit140includes a supporting unit127for supporting a substrate300, a fixing unit400for fixing one side of the substrate300to the supporting unit127, and a roller126for moving the substrate transferring unit140. When loading/unloading the substrate300into/from a chamber (not shown), and when depositing a thin film in the chamber, the substrate transferring unit140is inclined by a specific angle (Θ) with respect to the vertical direction.

The supporting unit127is provided with a gas injection assembly100. The gas injection unit100injects gas onto an upper surface of the supporting unit127when loading the substrate300on the substrate transferring unit140, when loading/unloading the substrate transferring unit140with the substrate300into/from the chamber of the sputtering device, and when coating a thin film on the substrate300after it has been loaded into the chamber. The gas injection assembly100forms a gas cushion having a specific thickness by consecutively injecting and sucking gas into/from a front surface of the supporting unit127.

The substrate300is loaded on the front surface of the substrate supporting unit127. A lower portion of the substrate300is fixed to the supporting unit127by the fixing unit400. Then, the substrate300is lifted above the supporting unit127by the gas cushion underneath to be stably transferred.

In the sputtering device according to an embodiment of the present invention, the transfer of the substrate and the formation of the thin film are performed while the substrate is mounted on the substrate transferring unit. That is, the thin film is formed on the substrate while the substrate transferring unit is loaded into the chamber of the sputtering device. Moreover, the substrate is unloaded while the substrate transferring unit is moved out of the chamber after the formation of the thin film. The substrate300may later be included in a liquid crystal display device (not shown).

FIG. 3is a cross-sectional view of an exemplary gas injection assembly on the substrate transferring unit inFIG. 2in accordance with an embodiment of the present invention. Referring toFIG. 3, a gas injection assembly100includes a plurality of gas injection nozzles110,120,130, and140, a plurality of gas flow amount controllers150and151, and distance detecting sensors160and161. The nozzles110,120,130, and140generate a gas cushion200at a front surface of each of the nozzles by injecting gas and then sucking the gas. The gas flow amount controllers150and151partially control a gas flow amount to form the gas cushion200. The distance detecting sensors160and161are attached to the surface of the gas injection assembly100and detect a distance between the gas injection nozzles110,120,130, and140and the substrate300on which a thin film is to be formed. As described above, a lower portion of the substrate300is fixed to the supporting unit by the fixing unit400.

The gas injection nozzle110includes a gas injection pipe111′ for receiving gas from the gas flow amount controller150of a nozzle group g1and supplying the gas, an injection opening111for injecting the supplied gas, a plurality of inlets h arranged around the injection opening111for sucking gas injected from the injection opening111and circulating the gas, and gas exhaustion pipes l. The injection opening111is positioned in the middle of the gas injection nozzle110. The inlets h are radially formed around the injection opening111.

InFIG. 3, gas is injected into each of the gas flow amount controllers150and151. The injected gas can be an inactive gas, such as Ar. Gas flows from the gas amount controller150into the gas injection pipes111′,121′,131′, and141′. The flowing gas is injected through the injection openings111,121,131, and141of the gas injection nozzles110,120,130, and140. Then, the injected gas is sucked into the inlets h and is expelled through the gas exhaustion pipes l.

Because the injected gas forms the gas cushion200between the front surface of the gas injection assembly100and the substrate300, substrate damage due to contact between the substrate300and the supporting unit127can be prevented. Specifically, because the substrate300is loaded onto the gas cushion200formed on the front surface of the gas injection assembly100, the substrate300is stably lifted above the supporting unit by the gas cushion200. Thus, a back scratch is not generated on the back surface of the substrate.

Nozzle group g1in the gas injection assembly100includes at least two nozzles110and120. Nozzle group g2in the gas injection assembly100includes at least two nozzles130and140. The number of nozzles in each nozzle group can be eight, for example. Each of the nozzle groups g1and g2is provided with one gas flow amount controller150and151, respectively. Each of the nozzle groups g1and g2is also provided with at least one distance detecting sensor160and161, respectively, to individually control a distance between the substrate300and the supporting unit127.

The distance detecting sensors160and161are general optical sensors and are attached to the front surface of the gas injection assembly100to measure a distance between the substrate300on which a thin film is to be deposited and the gas injection assembly100in the sputtering device. The optical sensor is provided with a light emitting portion and a light receiving portion. Light irradiated on the surface of the substrate300from the light emitting portion is reflected, then detected by the light receiving portion to measure the distance between the nozzle and the substrate.

The distance detecting sensor160measures the distance between the substrate300and the supporting unit in a region corresponding to the nozzle group g1. The distance detecting sensor161measures the distance between the substrate300and the supporting unit in a region corresponding to the nozzle group g2. The measured distance values are transmitted to the gas flow amount controllers150and151, which control the gas flow amount based on the measured distance values.

A gas cushion with a uniform thickness is formed on the supporting unit to maintain a uniform gap of approximately 5-10 mm between the nozzle on the supporting unit127and the substrate300. For example, when the distance between a nozzle110or120in a nozzle group g1and the substrate300is more than a reference value, the gas flow amount supplied per unit time by the gas flow amount controller150is decreased, thus decreasing the thickness of the gas cushion between the nozzle110or120and the substrate300. Hence, the gap between the nozzle110or120and the substrate300is decreased. When the distance between the nozzle110or120and the substrate is less than a reference value, the gas flow amount supplied per unit time by the gas flow amount controller150is increased to increase the thickness of the gas cushion between the nozzle110or120and the substrate300. Hence, the gap between the nozzle110or120and the substrate300is increased. A similar process is applied to nozzles130and140in nozzle group g2.

FIG. 4is a front view of an exemplary gas injection assembly according to an embodiment of the present invention. Referring toFIG. 4, gas injection nozzles110respectively having a circular cross section are arranged left to right and top to bottom on the surface of the gas nozzle assembly100. A gap d between adjacent gas injection nozzles110is approximately 10 mm or less. At least two gas injection nozzles110adjacent to each other in up and down directions or in left and right directions, or in up, down, right and left directions are grouped together to form a group g. The at least two gas injection nozzles110in the group g are controlled by an individual control system composed of one gas flow amount controller150(shown inFIG. 3) and at least one distance detecting sensor160(shown inFIG. 3). InFIG. 4, eight gas injection nozzles constitute one nozzle group g. However, in other embodiments of the present invention, the number of gas injection nozzles110can have other values.

In an embodiment of the present invention, since each nozzle group g is individually formed, the nozzle groups g can be added to the gas injection assembly100or removed from the gas injection assembly100when necessary. For example, when the substrate300is large, additional nozzle groups g may be added to the gas injection assembly100. In contrast, when the substrate300is small, excess nozzle groups g may be removed from the gas injection assembly100.

FIG. 5is a detailed enlarged view of the gas injection nozzle shown inFIG. 4according to an embodiment of the present invention. Referring toFIG. 5, the gas injection opening111(shown inFIG. 3) is arranged in the central portion of the gas injection nozzle110, and a plurality of inlets h1and h2are radially formed around the gas injection opening111. The first inlets h1are spaced from the gas injection opening111by a first distance, and the second inlets h2are spaced from the gas injection opening111by a second distance. Gas injected from the gas injection opening111is continually sucked into the first inlets h1and the second inlets h2radially arranged. The gas is expelled and to form a gas cushion on the supporting unit127(shown inFIG. 2) to protect the loaded glass substrate300.

FIG. 6is a detailed enlarged view of the gas injection nozzle shown inFIG. 4according to another embodiment of the present invention. Referring toFIG. 6, the gas injection nozzle may be provided with a first ring-shaped inlet h3and a second ring-shaped inlet h4. The first ring-shaped inlet h3is spaced from a gas injection opening211with a first distance and the second ring-shaped inlet h4is spaced from the gas injection opening211with a second distance. In embodiments of the present invention, the shape and the number of gas injection nozzles are not limited.

In an embodiment of the present invention, the gas injection assembly is formed of a material that is not damaged by the gas flowing through the nozzle or the gas inside the chamber of the sputtering device. For example, the gas injection assembly may be formed of an opaque material such as ceramic, fused quartz, or polymer.

In an embodiment of the present invention, the gas injection assembly is mounted on the substrate transferring unit of the sputtering device so that the substrate transferring unit does not contact the substrate. Thus, degradation of the substrate due to contact between the substrate and the supporting unit is prevented.

In the related art, when loading or unloading the substrate into/from the vacuum chamber, when the substrate passes through a region where the vacuum state is replaced by an atmospheric state, the entire substrate does not move at a constant speed because of an unstable air stream, and may be damaged. In contrast, in an embodiment of the present invention, substrate damage is effectively prevented.