JP2951857B2 - Film forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming two or more kinds of thin films on the same substrate. More specifically, the present invention relates to a film forming method effective for a thin film element having a low resistance thin film wiring layer and a high stress metal thin film layer on the same substrate.

[0002]

2. Description of the Related Art As is well known, a semiconductor integrated circuit,
For a liquid crystal device, a high-density printed circuit board, and the like, it is necessary to form a thin film pattern many times. As means for forming a thin film pattern, a thin film having a predetermined thickness is sputtered on one main surface of a substrate constituting the device, and a normal pressure CV is applied.
D. After deposition using a thin film deposition apparatus such as plasma CVD, a desired photosensitive resin pattern is selectively formed on the thin film by photolithography using a photosensitive resin and an appropriate exposure machine. The photosensitive resin pattern is used as a mask at the time of etching (etching), and an unnecessary thin film is selectively removed with an appropriate etching solution or etching gas, and further, the photosensitive resin pattern is removed by an appropriate means. Need a series of microfabrication processes.

Among the above devices, in a TFT liquid crystal device in which a TFT (thin film transistor) made of an amorphous silicon semiconductor is arranged as a switching element at each intersection of a scanning line and a signal line, a glass substrate having a size exceeding 300 mm is used. Since it is a substrate and is mass-produced on a scale where the monthly processing amount exceeds 10,000 sheets, an in-line type vacuum film forming apparatus as shown in FIG. 2 is often used for forming a metal thin film.

FIGS. 2 and 3 briefly show the configuration of the apparatus.
This will be described below. In the figure, a metal, for example, a SUS tray 2 on which a plurality of glass substrates 1 are mounted has a first vacuum standby chamber 3 for accommodating a tray 2 from the atmosphere into a film forming apparatus, and a discharge electrode 4 composed of a sputter target. Film forming room 5
The minimum component is a configuration in which a second vacuum standby chamber 6 for taking out the tray 2 after film formation into the atmosphere again is connected in series via a gate valve between the respective chambers.

[0005] A predetermined thin film is deposited while moving in front of the discharge electrode 4 while the tray 2 is continuously connected in the film forming chamber 5. When substrate heating is necessary, a heating chamber 7 is arranged between the first vacuum standby chamber 3 and the film forming chamber 5 in addition to the inside of the film forming chamber 5 as shown in FIG. However, in order to form a plurality of metal thin films or shorten production tact, a design method such as arranging a plurality of targets in the film forming chamber 5 or arranging a plurality of film forming chambers in series is required. It is added.

FIG. 3 is a schematic sectional view of a film forming chamber 5, and a tray 2 is for mounting and transporting the glass substrate 1.
It is made of a metal having high heat resistance and high durability, for example, SUS. 8
Is a heater for heating the tray 2, 4 is a discharge electrode on which a sputter target is mounted, 5 is a film forming chamber capable of reducing pressure, and 9 is an exhaust port for exhausting the inside of the film forming chamber 5. The mechanism for holding and transporting the tray 2 and the glass substrate 1
The exhaust system such as a mechanism to be mounted on the apparatus and a vacuum pump is omitted. Although not shown, the argon gas, which is a discharge gas, is discharged into a small hole formed in a pipe disposed near a film formation (discharge) space formed by the discharge electrode 4 and the tray 2 into the space.

[0007] In recent years, from the viewpoint of improving the productivity, the recent sputtering apparatus transports the tray 2 vertically (moves in the direction perpendicular to the paper surface) and deposits the tray 2 on one side of the two trays 2 at the same time. It has a device configuration.

In the in-line sputtering apparatus configured as shown in FIG. 2, the glass substrate 1 mounted on the tray 2 is loaded (first vacuum standby chamber) chamber 3 as described above.
Into the heating chamber 7
And a predetermined temperature in the heating chamber 7 (up to about 400 ° C.)
After the temperature is increased, the film is moved to the film forming chamber 5, a predetermined thin film is formed in the film forming chamber 5, then moved to the unload (second vacuum standby chamber) chamber 6, and released to the atmosphere again in the unload chamber 6. You. After passing through the return rail 10 or being mounted on the shuttle-shaped movable carriage 11, the tray 2 returns to the load chamber 3, which is the entrance of the sputtering apparatus, and after the glass substrate after film formation is taken out, a new glass substrate is again formed. Is mounted and heads to the load room 3. As described above, the tray 2 continues to move endlessly, and the formed substrates are continuously produced. Since the substrate temperature decreases as the deposition time in the deposition chamber 5 increases, a heater 8 for heating the substrate is also disposed in the deposition chamber 5 as shown in FIG. Is done. The movement tact of the tray 2 as a mass production machine is as follows: the exhaust capacity in the vacuum standby chambers 3 and 6, the substrate heating capacity in the heating chamber 7, and the film forming chamber 5
And is generally about 3 to 5 minutes.

[0009]

As a matter of course, in the above-described film forming apparatus, if the continuous production is continued and the operation time of the film forming apparatus is prolonged, the thickness of the metal thin film deposited on the tray 2 is also reduced. It increases in proportion to the operation time. However, the thickness distribution of the metal thin film deposited on the tray 2 is not uniform, and there is a region where the thickness of the deposited film is extremely small, especially in the vertical direction perpendicular to the moving direction of the tray. In such a region, the quality of the deposited thin film is fragile, and the deposited thin film is easily peeled and separated from the tray 2.

The fragments, small pieces, and small pieces of the metal thin film peeled and separated from the tray 2 behave as dusts and particles in the film forming apparatus. As a result, the glass substrate can be formed before, during or after the film formation. It is taken in or adheres to 1. Considering that the thickness of a thin film required for a liquid crystal device or a semiconductor device is 0.1 to 1 μm, such dust and particles are unacceptable, and do not greatly affect the yield of the device. It is obvious.

The stress of the thin film to be deposited remarkably varies depending on the required film material and film forming conditions, and the adhesive force to the tray 2 largely depends on the surface treatment condition of the surface of the tray 2 and the thermal shock of the tray 2. However, it is usually difficult to maintain a state in which dust and particles are not generated without changing the tray 2 for three days.
For high melting point metals such as r and Mo, the tray 2 had to be replaced every few hours instead of every day.

It is necessary to remove the metal thin film adhering to the surface of the replaced tray 2 by physical means such as GBB (glass bead spraying) or homing treatment. Is difficult to automate due to the non-uniform thickness of the adhering material, and the size of the tray is not only difficult to handle because it exceeds 1 m, and its weight exceeding 20 kg poses many problems from the viewpoint of safety. The running costs, including the costs of pure water washing, drying, packing, transportation, etc., which followed, made up a very large percentage of the expenses.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a film forming method capable of extending a tray replacement time.

[0014]

To achieve the above object, according to an aspect of, in the film forming method of the present invention, at least the glass substrate was mounted on a metal tray, a first for loading and unloading with the atmosphere of the tray A vacuum standby chamber, a deposition chamber for depositing a metal film, and a second vacuum standby chamber are connected to each other to move a vacuum deposition apparatus to form a thin film. Aluminum and a high stress metal are provided as targets for the formation of aluminum, and aluminum is
It is characterized in that film formation and high stress metal film formation are performed alternately .

[0015] Two kinds of targets, ie, aluminum and high stress metal, are placed in the same film forming chamber, or targets of Al and high stress metal are placed in two film forming chambers, and the film forming type is changed in an appropriate cycle. Is preferred.

In the above-described film forming method, it is preferable that the high stress metal is any one of chromium, tantalum, molybdenum, and tungsten, or a silicide thereof.

[0017]

According to the present invention, as described above, a film is formed from aluminum and a high stress metal by periodically changing the film forming method using the same tray. Since the thin film is periodically deposited, the internal stress of the composite film deposited on the tray is reduced, and detachment and peeling of the composite film are suppressed.

The high stress metal is chromium, tantalum,
Since any one of molybdenum and tungsten or a silicide thereof is used, the internal stress of the composite film deposited on the tray is further reduced, and detachment and separation of the composite film can be suppressed well.

[0019]

EXAMPLES Examples will be described below in detail. In the case of aluminum (Al), the cumulative film thickness on the tray is 1 mm
Does not occur. This is known as Al
Is soft and almost no mechanical distortion occurs inside the film. On the other hand, in the case of chromium (Cr), the accumulated film thickness is 10 μm.
If it exceeds m, film peeling will occur in the region where the Cr film is unevenly applied on the upper and lower portions of the tray as described above.

This is equivalent to 50 sheets in terms of the number of sheets passed through a tray having two glass substrates mounted on one side when forming a film of Cr to a thickness of 0.1 μm, and an in-line type designed in 5 minutes of tact. This is equivalent to only continuous production for 250 minutes by sputtering. That is, it is necessary to replace the tray with a cleaned one such as a GBB process every 250 minutes.

Therefore, as a stage before the occurrence of Cr film peeling, when the cumulative film thickness exceeded 8 μm, the film forming type was changed, and Al was deposited with a cumulative film thickness of 4 to 40 μm. The cumulative film thickness of Al was determined from the following viewpoints. First, Al is 1 μm
If the thickness is too small, the stress of Cr cannot be absorbed, and the film formation type is switched in a very short time, which is not practical. Conversely, if Al exceeds 100 μm, the increase in the accumulated film thickness is accelerated, and the ratio of the operation time applicable to the Cr film formation decreases. The above cumulative film thickness is equivalent to 5 to 50 when converted to the number of sheets passing through a tray having two glass substrates mounted on one side when forming a film of Al with a thickness of 0.4 μm, and is designed in 5 minutes of tact. The in-line sputtering performed corresponds to continuous production for 25 to 250 minutes.

Under the above-mentioned film forming conditions, alternately forming films of Cr and Al is repeated about 10 times, and the cumulative film thickness becomes 8 by Cr.
0 μm, 40 to 400 μm for Al, and the total cumulative film thickness is 120 to 480 μm. However, since the internal stress of the Cr thin film is relaxed by Al, film peeling did not occur.

In the TFT liquid crystal device, not only Cr but also any one of tantalum (Ta), molybdenum (Mo), tungsten (W) or a refractory metal such as silicide thereof may be used as a scanning line material or a signal line material. Alternatively, they are used as heat-resistant barrier metals, and these metals or silicides also have a large internal stress like Cr and are easily peeled off on the tray.

As described above, in the present embodiment, in the present invention, when only the Cr single layer was formed, the tray had to be replaced every 250 minutes, but the Cr single layer film and the Al single layer film were replaced. It can be seen that alternate film formation allows the tray to be replaced every 2250-4500 minutes, which is 9 to 18 times the tray replacement cycle.
Therefore, when depositing the Cr thin film, it is not necessary to prepare a large number of replacement trays for frequent replacement.
The B treatment cost has also been reduced to 1/8, and the effect of industrial management is great from the viewpoint of reducing running costs.

In the prior art, there are 2 dedicated Cr and 2 dedicated Al.
The apparatus configuration which can be performed by two sputterings requires two equivalent film forming apparatuses having a first film forming chamber having a Cr target and a second film forming chamber having an Al target, which increases the apparatus price. Despite the drawbacks, the required number of replacement trays and the running cost are significantly reduced, and the effect is more than compensated.

It is obvious that two types of targets are required as an apparatus configuration required for carrying out the present invention, and there is a risk of undesirable cross-contamination if the targets are close to each other in the same film forming chamber. Therefore, it is preferable to arrange two film forming chambers 5 continuously as shown in FIG.

The present invention is unfortunately not applicable to a device requiring only the above-mentioned high stress metal such as Cr or a single layer of silicide. However, in a large-area TFT device or a semiconductor integrated circuit, the resistance of the wiring is reduced. Alternatively, Al is used or used in combination for ease of workability, so that it is extremely effective for manufacturing these devices.

[0028]

As described above, according to the present invention, by alternately forming a high stress metal or a silicide thereof and an Al single layer film, the tray replacement cycle can be reduced to 9-1.
It can be extended eight times. As a result, the number of replacement trays can be reduced when depositing the Cr thin film, the GBB processing cost of the tray can be reduced to about 1/8, and the running cost can be greatly reduced.

In the conventional case, there are two types dedicated to Cr and Al only.
The apparatus configuration which can be performed by two sputterings requires two equivalent film forming apparatuses having a first film forming chamber having a Cr target and a second film forming chamber having an Al target, which increases the apparatus price. Although there are drawbacks, the required number of replacement trays and the running cost are significantly reduced, and an effect more than compensating for an increase in the cost of the apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a film forming apparatus for carrying out the present invention.

FIG. 2 is a schematic configuration diagram of a conventional film forming apparatus.

FIG. 3 is a sectional configuration diagram of a film forming chamber.

[Explanation of symbols]

 1-glass substrate 2-tray 3-load (first vacuum standby) chamber 4-discharge electrode 5-film formation chamber 6-unload (second vacuum standby) chamber 7-heating chamber 8-heating heater 9- Exhaust port 10-Return rail 11-Movable carriage

Claims (2)

(57) [Claims] 1. A at least the glass substrate was mounted on a metal tray, a first for loading and unloading with the atmosphere of the tray
A vacuum standby chamber, a deposition chamber for depositing a metal film, and a second vacuum standby chamber are connected to each other to move a vacuum deposition apparatus to form a thin film. Aluminum and high-stress metal were provided as targets for the formation of aluminum, and the same tray was used to form the aluminum film and high-stress metal.
A film forming method characterized by alternately performing film forming. 2. The method according to claim 1, wherein the high stress metal is any one of chromium, tantalum, molybdenum, and tungsten, or a silicide thereof.