KR20090088302A - Apparatus for treating a substrate - Google Patents

Abstract

An apparatus for treating a substrate is provided to perform uniform coating by providing a pull-down resistor having resistance value more than 2 ohm. At least two or more cathode structures are formed inside a vacuum chamber(2). At least two or more anodes are formed inside the vacuum chamber. A connecting line(63) is connected to the anodes(28~32). A resistor(34) is connected to the connecting line. The other end of the resistor is connected to a ground(33). The resistor has a resistance value of at least 2 ohm. The vacuum chamber is connected to the ground.

Description

Device for substrate processing {APPARATUS FOR TREATING A SUBSTRATE}

The present invention relates to an apparatus for processing a substrate.

Magnetron sputtering sources are used to process (eg, code) substrates such as semiconductors, optical devices or flat panel displays (FPDs). These magnetron sources cause ions in the plasma to sputter material from the target. This sputtered target material is then deposited on the surface of the substrate to form a thin film. Also, the ions may etch the substrate.

A sputter source with at least two electrically insulated stationary bar-shaped target arrangements, one mounted side by side and separated by each slit, is already present. Known (see US 6,093,293, see also US 6,284,106 and US 6,454,920). Each of the target structures includes a respective electric pad, so that each target structure can be operated electrically independently of other target structures. Each target structure also has a controlled magnet structure to create a magnetron field that changes over time on each target structure. The sputter source also has an anode structure having an anode side by side between the target structures and / or along the smaller side of the target structures.

Also known is an arrangement for coating a substrate, which comprises two electrodes that are electrically separated from the sputtering chamber and electrically separated from each other, where one of the electrodes is a cathode electrically connected to the target and the other The electrode is an anode (DE 40 42 289 A1). A capacitor and a resistor are connected in series with the anode and ground. According to DE 41 36 655 A1 the capacitor can be omitted. The problem to be solved in both inventions (DE 40 42 289 A1 and DE 41 36 655 A1) is the suppression of arc discharge.

If the anodes are placed before the cathode as shown in DE 41 36 655 A1, the conditions of ignition are improved. However, disadvantages arise from the fact that the anodes are a hindrance to the flow of plasma particles, whereby the anodes are also coated. This coating then results in particles of the anode falling on the substrate and worsening the quality of the layer. On the other hand, by reactive sputtering, the surface of the anode opposite the surface of the cathode can be coated with a dielectric. Thus, the ignition conditions are worse. This effect is known as the "disappearing anode."

Also known is a plasma source comprising a chamber for confining a feed gas (WO 2005/052979 A2). An anode is located in the chamber and a segmented magnetron cathode comprising a plurality of magnetron cathode segments is located in the chamber in proximity to the anode.

Finally, a plurality, ie three or more cathodes, arranged in the chamber are known from US 4,417,968, JP 2003-183829 and EP 1 594 153 A1.

It is an object of the present invention to provide a structure for coating a substrate, for example glass, whereby the coating process has a long term stability so that the layers deposited on different substrates are not substantially different from each other.

This problem is solved by providing an apparatus for coating a substrate according to the features of claim 1.

Accordingly, the present invention relates to an apparatus for treating (eg, coating) a substrate in a vacuum chamber. In this vacuum chamber n cathodes and n + 1 anodes are arranged, each of which is adjacent to the cathode. Each of the n cathodes and the n assigned anodes are connected to a power supply. One of the anodes not assigned to the cathode is connected to the wire connecting the respective anodes. A pull-down resistor is connected to the wire at one end thereof and to ground at the other end thereof.

By using such a structure in the sputtering process, the layers of coated substrates have good stability over a long period of time. In addition, the properties of the layers, for example sheet resistance and sheet uniformity, are improved.

Very good properties can be obtained at resistance values above 10Ω. For example, when the pull-down resistor has a resistance value of 440-470Ω, good properties for the coating of the substrate are obtained, and the substrate is coated by an apparatus having three or more, for example nine magnetron sputter sources.

1 shows a cross-sectional view of an apparatus for coating a substrate. The apparatus 1 comprises a vacuum chamber 2 with surrounding walls 3, 4, 5, 6 and a plurality of cathode structures 7 to 10. Each of the cathode structures 7-10 is connected to one of the power sources 11-14 to form a cathode. The anodes 28 to 32 are arranged near the cathode structures 7 to 10 and are connected to the power sources via lines. These lines pass through the wall 5 through the insulators 23 to 27. Anodes 29-32 are connected to one of the power sources 11-14, and each power source is connected with one of the anodes 29-32 and one of the cathode structures 7-10. These power sources 11-14 are all electrically connected to ground 33 which serves as a protective earth.

The resistance between the anodes 28-32 and the supplying line is about 100-200 mΩ. If the resistance of the resistor 34 is lower than 2 ohms, a larger current will flow through the lids 53 and 54 because the transition resistance of the shrouds 53 and 54 is lower. If the resistor 34 is bypassed by a short circuit R = 0, all surfaces of the sputter chamber 2 have the function of an anode. Such a large anode has the advantage that the ignition of the plasma is improved. However, with a structure comprising a plurality of cathodes 7-10, an electric field can be formed which is defined by grounded metallic parts that determine the unevenness of the layer.

The resistor 34 of the present invention is used to eliminate the effect of the grounded portions of the chamber 2 on a configuration comprising a plurality of cathodes.

When the resistance of the resistor 34 increases, the influence of the grounded parts after ignition of the plasma is even more eliminated, because after ignition the plasma current flows in particular between the anodes 28 to 32 and the cathodes 7 to 10. to be. At the moment of ignition, little current flows and the voltage of the resistor 34 is lowered. However, a large current flows due to the constant burning plasma, so that the voltage of the resistor 34 increases. Thus, the grounded portions of the chamber 1 are substantially separated from the sputter current circuit. If R = ∞, current flows only between the anodes and the cathodes.

As can be seen in FIG. 1, five anodes 28 to 32 are arranged in the chamber 2, but there are only four target structures 7 to 10, each comprising a cathode, or a cathode. That is, generally speaking, there are n + 1 anodes and n cathodes. However, the number of cathodes may be equal to the number of anodes.

By having this configuration, including n + 1 anodes and n cathodes, geometric and electrical mirror symmetry is established with respect to the substrate moving through the chamber.

The anodes 28 to 32 are electrically connected to each other via a line 63 and to the ground 33 via a resistor 34 so that all the anodes 28 to 32 have a common electrical potential. Is connected to.

Resistor 34 is a pull-down resistor having a defined resistance. The resistance value is beyond 2 Ω up to several kΩ, preferably up to 1 MΩ. By this limited resistance value, it is possible to set a limited potential including a power supply source, an anode and a cathode, thereby establishing a uniform distribution of plasma in the chamber 2. As a result, a uniform coating of the substrate is obtained.

If the resistance value of the resistor 34 is less than 2 Ω, current does not flow completely through the anodes 28 to 32. To avoid this, the resistor 34 has a resistance value of more than 2 ohms, preferably more than 10 ohms, so that current flows through the anodes 28-32. At resistance values above 2Ω, the coated sheet resistance is independent of current and voltage.

Without the pull-down resistor 34, the potential values mentioned above do not have limited values with respect to earth or ground. Therefore, the potential may correspond to R = 0 at one time point and R ≠ 0 at another time point. There is no guarantee of a uniform distribution of the plasma, ie the distribution of the coating can be good at one moment and bad at another. In addition, long term stability cannot be controlled.

Referring again to FIG. 1, a plane substrate 35 is shown, which is, for example, a glass plate, moving through the interior 36 of the vacuum chamber 2, the substrate 35 being a cathode structure. Coated as they pass through the fields 7 to 10.

As understood from FIG. 1, the substrate 35 moves in the direction of the arrow 37 leaving the chamber 2 through the opening 38. When the substrate 35 leaves the chamber 2, another substrate 39 to be coated enters the chamber 2 through the opening 40 disposed on the opposite side of the opening 38. Although not shown in FIG. 1, lock chambers are disposed on both sides of the vacuum chamber 2 so that the substrate 35 emerging from the lock chamber disposed next to the opening 40 is arranged next to the opening 38. It may be allowed to move through chamber 2 to enter another locked chamber.

A constant vacuum is provided in the chamber 2 throughout the coating process. This is done by the vacuum pumps 41, 42 shown in FIG. 1.

The gas reservoirs 43, 44 supply gas or gas mixture to the chamber 2. A gas or gas mixture flows through the pipe 47, which enters the chamber 2 through the openings 45, 46 of the pipe 47.

Thereafter, the gas or gas mixture can be removed via the pumps 41, 42, which leave the chamber 2 through the openings 48, 49. Each gas reservoir 43, 44 may include different gases. For example, if a reactive sputtering process is performed, one of the reservoirs 43, 44, for example reservoir 44, contains a reactive gas, such as N ₂ , O ₂ , while the other reservoir 43 ) Includes an inert gas such as Ar.

Gas flow may be regulated through valves 50, 51, 52 controlled by a computer, not shown in FIG. 1.

Although four magnetron sputtering sources 7 to 10 are shown in FIG. 1, it will be apparent to those skilled in the art that not only four but more magnetron sputtering sources may be disposed but not less than two.

As can be seen in FIG. 3, the anodes 29-32 are in turn connected to respective power supplies 11-14 and other anodes 28. All these anodes 28 to 32 are connected to each other, and a pull-down resistor 34 is disposed between these anodes 28 to 32 and ground 33.

FIG. 2 shows a cut-out of the device 1 according to FIG. 1, showing a cathode structure 8 and a cut section of the cathode structure 7.

The cathode structure 8 and the corresponding anode 30 are connected to the power supply 12. The anode 30 is also electrically connected to a wire or line 63. This power supply 12, which is a DC power supply, is connected to ground 33. The cathode structure 8 comprises a cathode body 55 which is partly disposed in the chamber 2. Sealing 62 is provided to maintain a stable vacuum in the vacuum chamber 2.

The cathode structure 8 further comprises magnets 56, 57, 58 disposed in the yoke 59, the yoke 59 between the magnets 56, 57, 58 and the body 55. Is placed on.

Further, a plate 60, which is preferably a copper plate, is disposed between the magnets 56 to 58 and the target 61, and the target material is for example Mo, Ti, Cu, Si, Al, Zn, Zr, Ni, Cr, NiCr or an oxide of these materials. ITO can also be used as the target material.

Although not shown, the cathode structures 8 in the vacuum chamber 2 as well as other cathode structures include a cooling device for cooling the cathode structures during the coating process.

3 shows an apparatus similar to that shown in FIG. 1. However, cylindrical cathodes are provided instead of planar cathodes. Cylindrical carriers 15 to 18 are surrounded by cylindrical targets 19 to 22 connected to the negative potential of each voltage source 11 to 14 via lines 64 to 67. Details on these cylindrical cathodes are disclosed by EP 1 722 005 B1. In addition, besides linear and cylindrical cathodes, planar “MoveMag” cathodes as shown in FIG. 2 of DE 197 01 575 A1 can be used.

4 shows a graph showing the sheet resistance Rs, i.e. the resistance of the coating on the substrate and the uniformity of the coating according to the different resistance values of the pull-down resistor 34 for the process, where the The power of one of the cathodes 10 arranged in one stage is P = 30 kW and the power of the other cathodes 7-9 is P = 27 kW, the pressure p = 0.15 Pa and the layer thickness is about d = 10 ^−7. m. Uniformity

, Where Min is the minimum value of the layer thickness d and Max is the maximum value.

In order to avoid being injured by floating potentials and to avoid electrostatic charging, the surrounding walls 3 to 6 of the chamber 2 can be grounded or earthed. For the same reason, the housings of the power supplies 11-14 are grounded. The ground of the housing is not connected to the anodes 28 to 32.

As can be seen in FIG. 4, there is a lack of uniformity when the resistance values of pull-down resistor 34 are lower than 2 Ω. If the resistance values are greater than 2 Ω, the effect on two properties, namely sheet resistance and uniformity, is reduced, and thus a more uniform coating can be achieved by providing a pull-down resistor 34 having resistance values greater than 2 Ω.

Other powers are derived from the position of the cathodes 7 to 10 in the chamber 2. Instead of allowing other powers to be applied to the cathodes, it is also possible to apply only one power to the cathodes.

The break of the curve at R = 2Ω is due to the fact that the measurement contains only three points. In practice, the curve may take the form of an e-function. If the resistor 34 has a resistance value of 2 k ?, the effect of the present invention is also achieved. However, the ignition of the cathodes is worse compared to the lower pulldown resistance values.

By understanding the following description in conjunction with the accompanying drawings, the invention will be better understood and the various objects and advantages of the invention will be better understood.

1 is a cross sectional view of an apparatus for coating a substrate, the apparatus comprising a linear cathode.

FIG. 2 is a cut-out view of the device according to FIG. 1.

3 is a cross-sectional view of an apparatus for coating a substrate, the apparatus comprising a tubular cathode.

4 is a graph showing sheet resistance of coatings with different resistance values.

Claims (12)

An apparatus for processing a substrate, 1.1 vacuum chamber 2; 1.2 at least two cathode arrangements 7-10 in the vacuum chamber 2, where n ≧ 2, and n is the number of cathodes; 1.3 at least two anodes 28-32 in the vacuum chamber 2; 1.4 a connecting line 63 to which each of said anodes 28-32 is electrically connected; 1.5 resistor 34 connected to the connecting line 63 at one end thereof and to ground 33 at the other end, the resistor 34 having a resistance of at least 2Ω; Apparatus for processing a substrate comprising a. The method of claim 1, and n cathode structures (7-10) and n + 1 anodes are provided. The method of claim 1, The vacuum chamber (2) is an apparatus for processing a substrate electrically connected with the ground (33). The method of claim 1, Each of the anodes 29-32 and their assigned cathodes 7-10 is connected to a common electrical power source 11-14, so that each of the cathodes 7-10 and Assigned anodes (29-32) are operable to operate electrically independently from other cathodes and assigned anodes. The method of claim 1, Each of the cathodes (7-10) comprises a planar target. The method of claim 1, Each of the cathodes (7-10) comprises a cylindrical target (cylindrical target). The method of claim 6, The resistor (34) has a resistance of 40Ω to 10kΩ. The method of claim 1, And a shroud (53, 54) is arranged in the chamber (2). The method of claim 1, And the resistor (34) is a pull-down resistor. The method of claim 7, wherein And the resistance of the resistor (34) is between 400 and 500 ohms. The method of claim 1, And said cathodes are planar cathodes. The method of claim 1, And said cathodes are cylindrical cathodes.

Images