JPS63312962A - Sputtering device - Google Patents

Abstract

PURPOSE:To prevent generation of an abnormal discharge at the boundary between the top of a substrate and a mask and to stabilize plasma by insulating a holder which holds the substrate of a sputtering device and the mask from the earth potential. CONSTITUTION:The substrate 3 disposed to face a target (not shown in the figure) is held together with the mask 7 by the holder 6 in a vacuum vessel 1 in which the earth potential is maintained. A negative voltage is impressed on the magnetic target to generate plasma to sputter the target and to form a thin film on the substrate 3. The holder 6 and vacuum vessel 1 of the above- mentioned sputtering device are fixed in contact with each other via 'Teflon(R)' 15 which is an insulator to insulate the holder 6 and the mask 7 from the earth potential. A substrate cooling system consisting of a cooling water inlet 17 and outlet 18, a radiator 19, a circulation pump 20, etc., is preferably insulated from the earth potential as well. Generation of the abnormal discharge is thereby obviated even if the discharge is executed by large electric power. The film forming speed is thus increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in sputtering equipment for producing thin films.

BACKGROUND OF THE INVENTION Taking a conventionally widely used two-pole DC sputtering device as an example, this structure consists of a target 2 and a substrate 3 facing each other in a vacuum chamber 1 connected to ground potential, as shown in FIG. A negative voltage is applied to the target 2 by a DC power source 6 through a target holder 4. The substrate 3 is in electrical contact with the vacuum vessel 1 via a metal holder 6, and a portion of the holder and the mask are at ground potential. In FIG. 3, 8 is an insulating material, 9 and 1o are an argon gas inlet and an exhaust port, respectively, and 11 is a plasma.

The case where a transparent conductive film is produced on a glass substrate will be explained as an example. During film formation, positive argon ions in the plasma 11 shown in FIG. incident towards the direction. FIG. 4 specifically illustrates this state in the vicinity of a part of the holder and the substrate 3. However, in FIG. 4, the flying state of the transparent conductive film material is omitted. In Figure 4, 3 is the board, 6°7
are a holder and a mask of a part of the holder, respectively. Further, 12 is the above-mentioned incident electron, and 13 is a positive argon ion that enters the insulating substrate together with the electrons.

The holder 6 and the mask 7 are made of metal, and are electrically connected to the ground potential.
This part is always kept at ground potential even if electrons etc. are incident on it.

However, the electrons 12 and ions 13 that have entered the glass substrate 3 charge the surface of the glass substrate 3, making it a floating potential. As is well known, the floating potential is lower in potential than the space potential of plasma, but according to measurements by the present applicant, it is higher than the ground potential by several volts to several tens of volts.

On the other hand, it is difficult to completely contact the boundary between the mask 7 and the substrate 3, which is indicated by a in the figure, and a slight gap is created. Therefore, a potential difference of several volts to several tens of square meters is generated between the surface of the substrate 3 and the mask 7 through a minute space at the boundary portion a, and when this potential difference exceeds a limit value, a discharge occurs. This is abnormal discharge, and the larger the potential difference, that is, the higher the discharge voltage and the higher the floating potential, the more likely abnormal discharge will occur.

Also, an enlarged view of the surface of the substrate 3 and the mask 7 in FIG. 4 is shown in FIG.
As shown in the figure, even though the substrate 3 and the mask 7 are in contact with the transparent conductive film 14 in a spot-like manner, a rack as shown in b occurs on the surface of the thin film on the substrate 3 due to thermal stress, etc. Then, a potential difference occurs on both sides of this crack, and abnormal discharge occurs.

The above is the cause of occurrence of abnormal discharge, but this is not limited to the case where a conductive film is formed on an insulating substrate, but the same applies when an insulating film is formed. That is, abnormal discharge also occurs between an insulating film that has a floating potential and a mask that is at ground potential or a conductive substrate that is at ground potential.

Problems to be Solved by the Invention When forming a film using the above sputtering apparatus, if discharge is performed with high power to increase the film forming speed, abnormalities may occur on the substrate 3 and at the boundary between the substrate 3 and the mask 7. There are problems in that the plasma 11 generated on the target 2 fluctuates unstably due to the occurrence of discharge, and the thin film formed on the substrate 3 is damaged.

In view of this, an object of the present invention is to provide a sputtering apparatus in which abnormal discharge does not occur.

Means for Solving the Problems In order to solve the above problems, the present invention insulates the holder for holding the substrate and the mask from the ground potential.

Operation: By the above means, the mask, the substrate, the thin film to be produced, etc. can all be kept at the same floating potential, and no potential difference will occur between them.

Embodiment The first sectional view of a part of the holder which is the first embodiment of the present invention is shown below.
As shown in the figure. Note that elements common to those in the conventional example are given the same numbers and explanations are omitted. In FIG. 1, 1 is a vacuum container connected to ground potential, 3 is a substrate, 6 is a holder, and 7 is a mask.
It is fixed in contact with the vacuum container 1 via. 16 is the substrate cooling water system, 17.18 is the cooling water inlet and outlet pipe, 1
9 is a radiator, and 2o is a water circulation pump. Conventional sputtering equipment uses circulating cooling water within the factory as the substrate cooling water, but in this embodiment, the cooling water is also provided in a dedicated closed circuit, and the entire substrate cooling water system 16 is insulated from the ground potential. There is.

In this way, by electrically insulating the entire holder from the ground potential, the mask, substrate, thin film, etc. are kept at the same floating potential to prevent abnormal discharge from occurring.

FIG. 2 is a sectional view of a portion of a holder according to a second embodiment of the present invention. The numbers in the figure are the same as those in the first embodiment, but the feature of this embodiment is that the mask 7 is fixed in contact with the holder 6 via a highly thermally conductive insulating ceramic 21. With this configuration as well, effects similar to those of the first embodiment can be obtained.

Note that the present invention is not limited to the DC bipolar sputtering apparatus exemplified in the conventional example, but can also be applied to a sputtering apparatus using high-frequency discharge. Furthermore, it can also be applied to in-line sputtering equipment that is currently used as a mass-produced machine in factories.

Effects of the Invention According to the present invention, it is possible to obtain a sputtering apparatus that does not generate abnormal discharge even when discharging is performed with high power.

As a result, it becomes possible to increase the film formation rate by discharging a large amount of power.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a part of the holder of a sputtering apparatus according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a part of a holder of a sputtering apparatus according to a second embodiment of the present invention, and FIG. 4 is a schematic diagram of a part of the holder and the vicinity of the substrate during film formation, and FIG. 6 is a state diagram of the substrate surface, mask, and thin film. 1... Vacuum container, 3... Substrate, 6...
...Holder, 7...Mask, 15.21
······Insulator. Figure 2 Yuu Figure 3 Figure 4! 3″ Toma 5

Claims (6)

[Claims] (1) A sputtering device in which a holder for holding a substrate and a mask are insulated from ground potential. (2) The sputtering apparatus according to claim 1, wherein the holder and the vacuum container are fixed in contact with each other via an insulator. (3) A sputtering apparatus according to claim 1 or 2, wherein the substrate cooling water is insulated from earth potential. (4) The sputtering apparatus according to claim 1, wherein the mask is fixed in contact with the holder via an insulator. (5) The sputtering apparatus according to claim 1, wherein the holder is formed of an insulating material. (6) The sputtering apparatus according to claim 1, wherein the mask is formed of an insulator.