JP2001140055A - Sputtering system and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of difficulty in depositing a non-film-deposition region with high accuracy owing to the high thermal expansion coefficient of a mask made of metal. SOLUTION: A mask is constituted of an insulating material, and the surface of the mask, facing a cathode electrode 4, is coated with a metallic film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sputtering apparatus and a sputtering method, and more particularly to a sputtering apparatus and a sputtering method using a DC discharge.

[0002]

2. Description of the Related Art In a manufacturing process of a liquid crystal display device or the like,
A thin film transistor (TFT) is formed on an insulating substrate such as glass. In the manufacturing process of the TFT, a sputtering device using a DC discharge is used to form a metal film for forming wirings and pixel electrodes. When forming a metal film, if the metal film adheres to the edge of the substrate, it peels off in a later process and becomes a foreign substance, which causes a wiring short-circuit failure or the like. Therefore, it is necessary to provide a structure that shields the edge of the substrate from the sputtering source so that the metal film does not adhere to the edge of the substrate.

[0003] The most common shielding structure in a sputtering apparatus for mass production of TFTs is a position (0.
5 to 5 mm). This mask must also serve as a ground path in the case of DC discharge sputtering. The earth path of the DC discharge sputtering device is limited to a region (a metal mask region or a device wall region of the device) in which a DC current can flow from the cathode electrode through discharge.

In recent years, with the increase in the size of the TFT manufacturing substrate, the wall region from the cathode electrode is hardly visible. For this reason, the role of the mask region as ground is very important, and a metal mask is mainly used.

[0005]

In the above-mentioned conventional sputtering apparatus for forming a metal film, the substrate is formed with a view to reducing the resistance of the film, improving the adhesion between the substrate and the film, and improving the etching property. Usually, film formation accompanied by heating is performed.

However, since the metallic mask has a large coefficient of thermal expansion, even if its position is adjusted at room temperature, the thermal deformation of the mask during heating becomes remarkable, and there is a disadvantage that the non-film formation region cannot be formed accurately. Most of the materials having a low coefficient of thermal expansion that can solve this problem cannot be used as a mask that serves as a ground path because most of them are insulators.

Further, since the metallic mask itself is grounded, if the substrate comes into contact with the mask during film formation, an overcurrent is generated at the contact position between the charged glass substrate surface and the grounded mask. Flow and abnormal discharge may occur. To cope with this problem, measures have been taken to provide a mechanism for clamping the substrate in the apparatus or to make the internal mask portion have a floating structure, but there has been a problem that the apparatus becomes complicated.

An object of the present invention is to provide a sputtering apparatus and a sputtering method which improve the positional accuracy of the mask, do not complicate the apparatus, and do not cause abnormal discharge.

[0009]

According to a first aspect of the present invention, there is provided a sputtering apparatus comprising: a substrate holder provided in a sputtering chamber for mounting a substrate; a cathode electrode provided opposite to the substrate holder; A mask that covers a peripheral portion of the substrate placed on the holder, wherein the mask is made of an insulating material, and a surface facing the cathode electrode is covered with a metal film. In particular, the mask is made of ceramics or quartz, and the metal film is made of Al or Cu.

According to a second aspect of the present invention, a metal film is formed on a substrate placed on the substrate holder by using any one of the first to fourth aspects of the present invention. Is what you do.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 are a configuration diagram in a sputtering apparatus and a perspective view of a mask for describing an embodiment of the present invention.

Referring to FIGS. 1 and 2, the sputtering apparatus of the present invention comprises a substrate holder 2 provided in a sputtering chamber for placing a glass substrate 3 thereon, and a target provided opposite to the substrate holder 2 to constitute a target. It is mainly composed of a cathode electrode 4 and a ceramic mask 5 provided on the substrate holder 2 and keeping a constant distance from the glass substrate 3 and having a surface facing the cathode electrode 4 covered with a metal film 6.

The ceramic mask 5 is provided so as to have an interval H (0.5 to 5 mm) that does not make contact with the glass substrate 3. In FIG. 1, 7 is a DC power supply and 8 is a sputtered film.

Any mask can be used as long as it is an insulator and has a low coefficient of thermal expansion, but a material such as ceramics or quartz which is relatively inexpensive and has established processing accuracy is used.

The metal film formed on the mask is formed by a method such as thermal spraying, vapor deposition, plating, or sputtering.
Is used. Specifically, an Al film 6 having a thickness of several μm is formed by spraying Al.
A was deposited, and grounded with a screw portion 8 for fixing the mask to the apparatus as shown in FIG.

As a method of forming a metal film on the ceramic mask 5, the sputtering apparatus of the present invention can be used. For example, in FIG. 1, a ceramic mask 5 on which a metal film is not formed is attached, and a direct current discharge may be performed using a metal substrate holder and using Al, Cu, Au, or Cr as a cathode electrode. If there is a mechanism that can apply high-frequency power to a system different from DC power, the substrate holder may be an insulator, and a metal film can be formed on a ceramic mask.

FIG. 3 shows an equivalent circuit diagram in the sputtering chamber of the present invention. Since case without the formation of the metal film to the capacitance C ₁ of the ceramic mask itself is present, direct current does not flow by applying a DC voltage to the cathode electrode. However, by covering the mask surface seen from the cathode electrode with the metal film, an earth path is formed and a stable DC discharge can be maintained.

Further, in the present invention, the area which cannot be seen from the cathode electrode is left on the ceramic surface. That is, the mask surface facing the substrate for the insulator, an overcurrent does not flow even without C ₂ to the substrate and the mask is in contact during the formation, it is possible to suppress abnormal discharge. In the case of a conventional metal mask, when it comes into contact with a substrate during film formation, an abnormal discharge path is formed as shown by a dotted line, and abnormal discharge occurs.

Next, a case where a sputtered film 8 made of Cr is formed on the glass substrate 3 using this sputtering apparatus will be described. The film formation was carried out by a single-wafer transfer type sputtering apparatus for processing one glass substrate in a sputtering chamber. FIG. 4 shows the configuration of a single-wafer transport system.

The glass substrate 3 is transferred to each processing chamber centering on the transfer chamber 10. First, the glass substrate which has been evacuated in the load lock chamber 12 is heated to about 200 ° C. in the heating chamber 11, and then a Cr film is formed in the sputtering chamber 1 by a DC discharge sputtering method. The formed glass substrate is opened to the atmosphere in the unload lock chamber 12 and taken out.

The sputtering conditions are as follows:
The temperature of the substrate holder was adjusted to 0 ° C., the DC discharge power was set to about 5 kW, and the pressure was set to about 0.3 Pa (Ar flow rate 100
(SCCm).

The mask reaches a high temperature of about 200 ° C. without temperature control due to the heat generated during the generation of the discharge plasma and the influence of the radiant heat from the holder. The metal mask is
Due to the effect of large thermal expansion, warpage of several mm and deviation from the mounting position occur, but since the ceramic mask has small thermal expansion, stable positional accuracy can be obtained even in such a temperature range, The non-film formation region can be formed with high accuracy.

[0023]

As described above, according to the present invention, the following effects can be obtained by using a mask made of an insulator having a metal film formed on the surface.

First, since the mask can be formed of ceramics or quartz having a small coefficient of thermal expansion, the positional accuracy of the mask can be significantly improved, and the mask surface seen from the cathode electrode can be grounded by a metal film. Is formed, a stable DC discharge can be generated similarly to the conventional metallic mask.

Second, since the mask surface facing the substrate has no metal film and has an insulating structure, even when the substrate comes into contact with the mask due to warpage of the substrate during film formation, an abnormal discharge as seen with a metal mask is formed. Does not occur. Therefore, it is not necessary to employ a complicated mechanism as in the related art.

Third, since the metal film formed by sputtering and the ceramic or quartz of the mask material have a very high selectivity to the etching chemical, the mask can be easily regenerated and cleaned.

[Brief description of the drawings]

FIG. 1 is a configuration diagram in a sputtering apparatus for describing an embodiment of the present invention.

FIG. 2 is a perspective view of a mask used in the embodiment.

FIG. 3 is an equivalent circuit diagram of a sputtering chamber.

FIG. 4 is a schematic view of a single wafer transfer type sputtering apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sputter chamber 2 Substrate holder 3 Glass substrate 4 Cathode electrode 5 Ceramic mask 6 Metal film 6A Al film 7 DC power supply 8 Screw part 10 Transfer room 11 Heating room 12 Load lock / unload lock room

Claims (6)

[Claims] 1. A substrate holder provided in a sputtering chamber for mounting a substrate, a cathode electrode provided opposite to the substrate holder, and a peripheral portion of the substrate mounted on the substrate holder. A sputtering apparatus having a mask, wherein the mask is made of an insulator, and a surface facing the cathode electrode is covered with a metal film. 2. The sputtering apparatus according to claim 1, wherein said mask is made of ceramics or quartz. 3. A metal film covering the mask is made of Al or C.
3. The method according to claim 1, wherein said material is u, Au, or Cr.
The sputtering apparatus as described in the above. 4. The sputtering apparatus according to claim 3, wherein said metal film is formed by any one of thermal spraying, plating, vapor deposition, and sputtering. 5. A sputtering method, wherein a metal film is formed on a substrate mounted on the substrate holder by using any one of the sputtering apparatuses according to claim 1. 6. The sputtering method according to claim 5, wherein the sputtering is performed while maintaining a constant interval between the substrate mounted on the substrate holder and the mask.