JPH08186074A - Sputtering device - Google Patents

Abstract

PURPOSE: To prevent wafer transfer abnormalities due to Al film coalescence by providing a means that presses a subject to be processed to a holder before releasing the subject from a clamp ring. CONSTITUTION: When sputtering is completed, introduction/relief valves 19 and 26 are closed, an exhaust valve 28 is opened and the pressure of an adjustment chamber 17 is set at a first prescribed value. A main valve 12 is closed simultaneously with the opening of the exhaust valve 28, and the pressure in a sputtering room 10 is set at a second prescribed value. Since different pressure is applied on the front and rear planes of the wafer 2, the wafer 2 is held on a holder 4 by the pressure difference. Then, a clamp ring is permitted to ascend. Even when the clamp ring coalesces with the wafer 2 by the Al film, since the wafer 2 is pressed to the holder 4 by the pressure difference, the coalescence part of the Al film is torn by the ascending of the clamp ring. Then, the exhaust valve 28 is closed, the relief valve 26 is opened, and the pressure in the sputtering room 10 and the pressure in the adjusting chamber 17 are permitted to be at the same value. Then, a plunging up pin 3 is permitted to ascend, and the wafer 2 is brought up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering device, and more particularly to a sputtering device having a structure in which a wafer mounted on a holder is clamped by a clamp ring, and more particularly to a technique effectively applied to a technique for forming an aluminum film.

[0002]

2. Description of the Related Art Sputtering devices are often used in thin film formation in the manufacture of semiconductor devices such as ICs and LSIs. The sputtering apparatus is described in, for example, "Electronic Materials" published by the Industrial Research Society, March 1993 issue, March 1, 1993, P28 to P33. It is described that the sputter device described in the document is also a sputter device that can be used for manufacturing a 64 Mbit DRAM in which a contact of wiring and a hole of a through hole have a diameter of about 0.3 μm. In addition, the usage of this device is 6
It is a multilayer film having a high melting point of 4M (0.3 μm) aluminum.

[0003]

In the conventional sputtering apparatus as described above, as shown in FIG. 7, the wafer (semiconductor substrate) 2 sent to the sputtering chamber by the transfer arm 1 has the push-up pin 3 of Ascending moves from the transfer arm 1 onto the push-up pin 3. Further, the transfer arm 1 moves backward and moves to the outside of the sputtering chamber. Then, the push-up pin 3 descends, and the wafer 2 on the push-up pin 3 is lowered.
On the holder 4. Then, the clamp ring 5 descends to press the wafer 2 against the holder 4. After that, sputtering is performed. After the sputtering is completed, the clamp ring 5 rises and the push-up pin 3 also rises. The push-up pin 3 lifts the wafer 2 on the holder 4 when it is lifted. After that, the transfer arm 1 enters the sputtering chamber, and the wafer 2 on the push-up pin 3 is moved to the transfer arm 1 by lowering the push-up pin 3. The sputtering is completed by carrying the wafer 2 out of the sputtering chamber by the transfer arm 1.

In such a sputtering apparatus, as shown in FIG. 8, when the wafer 2 is displaced with respect to the clamp ring 5, the height of the clamp ring 5 becomes low. It has been found that the film 7 and the Al film 7 deposited on the wafer 2 may be integrated (adhered portion 8) due to heat. Also,
Even if the wafer 2 is not displaced, the Al film 7 deposited on the surface of the clamp ring 5 and the Al deposited on the wafer 2 are repeatedly sputtered as shown in FIG.
It was found that the membrane 7 may adhere (adhesion portion 8). The adhesion shown in FIG. 9 is, for example, 100% by sputtering.
It occurs in a state of repeating about 0 times. In such adhesion, when the clamp ring 5 rises, the wafer 2 is lifted together with the clamp ring 5 and a wafer position shift or the like occurs, which causes an abnormal delivery (wafer crack) between the push-up pin 3 and the transfer arm 1. cause.

It has also been found that the positional deviation of the wafer 2 causes rubbing between the push-up pins 3 and the wafer 2 to generate foreign matter, which causes the foreign matter to adhere to the wafer 2.

An object of the present invention is to provide a sputtering apparatus capable of preventing a wafer transfer abnormality due to adhesion of an Al film.

Another object of the present invention is to provide a sputtering apparatus capable of preventing the contamination of the wafer by foreign matter.

The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0009]

The outline of the representative ones of the inventions disclosed in the present application will be briefly described as follows. That is, the sputtering apparatus of the present invention, a holder that is provided in the sputtering chamber and mounts the object to be processed on the upper surface, and a push-up pin that pushes up the object to be processed placed on the holder upwards as necessary, A sputtering apparatus having a clamp ring for pressing an object to be processed placed on the holder against the holder,
When the clamp ring separates from the object to be processed, a pressing means for pressing the object to be processed against the holder is provided prior to the separation. The pressing means comprises a recess provided in the holder portion on the lower surface side of the object to be processed, and a pressure control system for controlling the pressure inside the recess and the pressure inside the sputtering chamber. The object is held in the holder by the difference.
That is, in the sputtering apparatus of the present invention, before the clamp ring is raised, the inside of the depression provided in the holder on the lower surface side of the wafer to be processed is evacuated, and at the same time, the pressure in the sputtering chamber (wafer surface side) is increased. By doing so, a pressure difference is provided on the front and back surfaces of the wafer, the wafer is held by the holder by this pressure difference, and then the clamp limp is raised. Moreover, in this sputtering apparatus, an aluminum thin film is formed.

The pressing means in the sputtering apparatus according to another embodiment of the present invention is a spring which is attached to the lower surface side of the clamp ring and elastically presses down the object to be processed downward.

[0011]

According to the above-mentioned means, in the sputtering apparatus of the present invention, when the clamp ring rises, the wafer is held by the holder due to the pressure difference. Therefore, the clamp ring and the wafer are formed by the Al film formed by sputtering. Even if they are adhered to each other, the clamp ring is separated from the wafer due to the tearing of the Al film, so that the wafer is not displaced and the abnormal wafer transfer can be prevented.

In the sputtering apparatus according to another embodiment of the present invention, since the wafer is held by the holder by the spring pressure when the clamp ring rises, the Al ring formed by sputtering adheres the clamp ring and the wafer. However, since the clamp ring is separated from the wafer due to the tearing of the Al film, the wafer is not displaced, and abnormal wafer transfer can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a main part of a sputtering chamber of a sputtering apparatus according to an embodiment of the present invention, FIG. 2 is a schematic plan view showing a part of a wafer transfer mechanism in the sputtering apparatus, and FIG. 3 is a schematic sectional view showing the same. FIG. 4 is a front view showing a part of a transfer arm in the sputtering apparatus, and FIG. 5 is a flowchart showing the unloading state of the wafer after sputtering in the sputtering apparatus.

The sputtering chamber of the sputtering apparatus of this embodiment has a structure as shown in FIG. That is,
The sputtering chamber 10 is formed of an airtight chamber 11. A main valve 12 is provided on one side of the chamber 11, and a vacuum exhaust pump 13 is connected to the main valve 12. The vacuum exhaust pump 13 evacuates the sputtering chamber 10 to about 10 to ⁸ torr. In addition, the gas supply pipe 1 is provided on the ceiling of the chamber 11.
4 are connected. From this gas supply pipe 14, a gas, for example, an argon gas (Ar) is supplied to the sputtering chamber 10 by opening the introduction valve (V1) 15.

A holder 4 for mounting a wafer (semiconductor substrate) 2, which is an object to be processed, is arranged at the center of the lower part of the sputtering chamber 10. The holder 4 has a structure for supporting the peripheral portion of the wafer 2. Therefore, the inside of the supporting portion that supports the wafer 2 becomes the depression 16, and
Adjustment chamber 17 closed by placing the wafer 2 thereon
Becomes In this adjusting chamber 17 (recess 16), the chamber 1
A gas supply pipe 18 extending from the outside is connected. Gas, for example, Ar gas, is supplied from the gas supply pipe 18 to the adjusting chamber 17 by opening the introduction valve (V2) 19.
It is supplied to. The gas supply pipe 18 is branched at two points. The first branch pipe 25 is connected to the sputtering chamber 10. A relief valve (V4) 26 is attached to the branch pipe 25.
The second branch pipe 27 that branches between the introduction valve 19 and the relief valve 26 is connected to the vacuum exhaust pump 13. An exhaust valve (V3) 28 is attached to the second branch pipe 27.

The gas supply pipe 18, the branch pipe 25,
27, the vacuum exhaust pump 13 and the like constitute a vacuum exhaust system of the sputtering apparatus, and the clamp ring 5
It also constitutes a pressure control system that causes the holder 4 to hold the wafer 2 when the pressure is raised. In this pressure control system,
By closing the relief valve 26 and the exhaust valve 28 and opening the introduction valve 19, Ar gas can be supplied to the adjustment chamber 17 (in the recess). Further, by closing the introduction valve 19 and the exhaust valve 28 and opening the relief valve 26, the sputtering chamber 10 and the adjustment chamber 1
7 is equal pressure. Further, by closing the introduction valve 19 and the relief valve 26 and opening the exhaust valve 28, the adjustment chamber 17 can be further evacuated by the action of the vacuum exhaust pump 13.

Therefore, in this state, the sputtering chamber 1
By making the pressure in the adjusting chamber 17 smaller than the pressure of 0, the wafer 2 on the holder 4 is held by the pressure difference in the holder 4
Can be held. For example, the adjustment chamber 17
Is reduced to less than 100 mTorr and the sputtering chamber 1
If the pressure of 0 is increased to 5 Torr or more, a differential pressure of about 1.5 kg is obtained for an 8-inch wafer, and the wafer 2 can be pressed and held by the holder 4 by this differential pressure.

The wafer 2 placed on the holder 4 can be pushed upward by the push-up pin 3. Then, by the vertical movement of the push-up pin 3, the transfer arm 1 that has entered the sputtering chamber 10.
The wafer 2 is exchanged between and. The transfer arm 1 is
As shown in FIGS. 2 and 3, the width is narrower than the diameter of the wafer 2 so as not to collide with the push-up pins 3 extending in four directions. Further, as shown in FIG. 4, a recess 30 matching the shape of the wafer 2 is provided on the upper surface of the tip of the transfer arm 1 to accommodate the wafer 2.

When the transfer arm 1 supporting the wafer 2 enters the sputter chamber 10, the push-up pin 3 moves upward from below the transfer arm 1 to move upward from the transfer arm 1. Wafer 2 is received. When the wafer 2 is transferred to the transfer arm 1, before the transfer arm 1 enters the sputtering chamber 10, the push-up pins 3 move upward while supporting the wafer 2, and the transfer arm 1 moves downward. After coming down, it descends and pushes up pin 3
The wafer 2 is transferred from the transfer arm 1 to the transfer arm 1.

A clamp ring 5 which moves up and down is arranged above the holder 4. This clamp ring 5
After the wafer 2 is placed on the holder 4, it moves down and presses the peripheral edge of the wafer 2 against the holder 4.

On the other hand, the chamber 1 facing the holder 4
A target 31 is attached to the ceiling portion 1.

On the other hand, a transfer gate valve 32 is provided on one side of the chamber 11. Transport arm 1
Enters when the transfer gate valve 32 is opened.

In such a sputtering apparatus, after the wafer 2 is supplied to the holder 4 by the transfer arm 1, the wafer 2 is clamped by the clamp ring 5 and then sputtering is performed. For spatter, open the introduction valve (V2) and press A
Introducing valve (V1) 15 while controlling the temperature of the wafer 2 in Ar atmosphere of about 5 Torr by flowing r gas into the adjusting chamber 17.
Open and open the sputter chamber 10 with Ar gas for about 3 m.
Sputtering is performed in Ar atmosphere of Torr. By setting the pressure on the front surface (main surface) side of the wafer 2 to about 3 mTorr and the pressure on the back surface side to about 5 Torr, the Al film can be sputtered while controlling the wafer temperature during sputtering.
The l-film is well formed. Further, after the Al film is formed on the surface of the wafer 2 by sputtering, the wafer 2 is carried out of the sputtering chamber 10.

When the wafer 2 is unloaded, the pressure control system operates in the sputtering apparatus of this embodiment. That is, as shown in the flowchart of FIG. 5, sputtering is completed (step 101).
Introducing valve (V2) 19 and relief valve (V
4) 26 is closed (step 102) and the exhaust valve (V3
) Is opened (step 103) and the pressure in the adjusting chamber 17 (P2
) Is set (confirmed) to 100 mTorr or less (step 104).

At the same time, the main valve (MV) 12 is closed (step 105), and the pressure in the sputtering chamber 10 (P1
) Is set (confirmed) to 5 Torr or more (step 10).
6).

Since the front and back surfaces of the wafer 2 have different pressures of 5 Torr or more (main surface) and 100 mTorr or less (rear surface), the wafer 2 has a pressure difference (a differential pressure of about 1.5 Kg for an 8-inch wafer). It will be held by the holder 4.

Then, the clamp ring 5 is raised (step 107). Even if the Al film deposited on the surface of the wafer 2 and the Al film deposited on the surface of the clamp ring 5 adhere to each other, the wafer 2 is pressed against the holder 4 by the pressure difference. As the clamp ring 5 rises, the adhered portion of the Al film is torn off, so that the wafer 2 is not pulled up even when the clamp ring 5 rises. Therefore, the position of the wafer 2 on the holder 4 is not changed, and subsequent lifting by the push-up pin 3 can be performed with high accuracy.

Next, the exhaust valve (V3) 28 is closed (step 108), the relief valve (V4) 26 is opened (step 109), and the inside of the sputtering chamber 10 and the adjusting chamber 17 are closed.
After the pressure inside (in the depression) is made the same, the push-up pins 3 are raised (step 110) to lift the wafer 2 (step 111). When the wafer 2 is lifted, the wafer 2 does not move when the clamp ring 5 is lifted as described above, so the wafer 2 can be lifted with high precision by the push-up pins 3. Therefore, the transport arm 1
It is possible to accurately and surely carry out the sputter chamber 10 from the sputter chamber 10.

In such a sputtering apparatus, even if the Al film on the wafer and the Al film on the clamp ring are adhered to each other, when the clamp ring is raised, the pressing means by the pressure control system acts to hold the wafer on the holder. Since the wafer is pushed, the movement of the wafer does not occur, and the subsequent lifting of the wafer by the push-up pin can be performed accurately and reliably, so that the wafer can be carried out with high accuracy.

Further, in the sputtering apparatus of the present embodiment, since the position shift of the wafer does not occur when the clamp ring is lifted, no rubbing occurs between the push-up pin and the wafer at the time of subsequent push-up by the push-up pin, and foreign matter is prevented. Can be prevented, and contamination of the wafer with foreign matter can be prevented.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example,
As shown in FIG. 6, the pressing means may be a structure having a spring 40 attached to the peripheral portion of the lower surface of the clamp ring 5. That is, the spring 40 is the clamp ring 5
The washer 41 and the screw 42,
Can be installed using. Then, the acting end 43 that acts elastically is brought into elastic contact with the wafer 2 on the holder 4. When the clamp ring 5 is raised, the wafer 2 is pressed against the holder 4 by the elastic force of the spring 40. Then, in this pressing state, the Al film 7 deposited on the surface of the clamp ring 5 and the Al film 7 deposited on the surface of the wafer 2.
The adhered portion (adhesive portion 8) is torn by the rise of the clamp ring 5. After the Al film 7 is torn, the working end 43 of the spring 40 is separated from the wafer 2. Therefore,
As in the previous embodiment, when the clamp ring 5 is raised, the holder 4
The position of the upper wafer 2 does not shift. As a result, the lifting of the wafer 2 by the push-up pin 3 is performed with high accuracy, and the transfer arm 1 reliably carries the wafer 2 out of the sputtering chamber 10.

In the above description, the case where the invention made by the present inventor is mainly applied to a sputtering technique including an Al film, which is a field of application which is the background of the invention, is not limited thereto. The present invention can be applied to at least a film forming technique.

[0033]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. According to the sputtering apparatus of the present invention, the adhesion between the clamp ring and the wafer by the Al film is
Since the wafer is divided by the pressing means while being held by the holder, the wafer does not move when the clamp ring is raised, and the unloading of the wafer can be performed with high accuracy. This reduces the failure rate and improves throughput by about 2%.

In the sputtering apparatus of the present invention, since the position of the wafer does not shift when the clamp ring is lifted, rubbing between the push-up pin for pushing up the wafer and the wafer does not occur, and it is possible to prevent the generation of foreign matter due to the rubbing and to prevent the foreign matter from the wafer. It can prevent pollution.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part of a sputtering chamber of a sputtering apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a part of a wafer transfer mechanism in the sputtering apparatus of this embodiment.

FIG. 3 is a schematic cross-sectional view showing a part of a wafer holding mechanism in the sputtering apparatus of this embodiment.

FIG. 4 is a front view showing a part of a transfer arm in the sputtering apparatus of this embodiment.

FIG. 5 is a flowchart showing a unloading state of a wafer after sputtering in the sputtering apparatus of this embodiment.

FIG. 6 is a sectional view showing a part of a wafer holding mechanism according to another embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a wafer holding mechanism in a conventional sputtering apparatus.

FIG. 8 is an enlarged cross-sectional view showing the adhesion state of the Al film deposited on the surfaces of the wafer and the clamp ring due to the displacement of the wafer in the conventional sputtering apparatus.

FIG. 9 is an enlarged cross-sectional view showing the adhesion state of the Al film deposited on the surfaces of the wafer and the clamp ring when the sputtering is repeatedly performed in the conventional sputtering apparatus.

[Explanation of symbols]

1 ... Transfer arm, 2 ... Wafer, 3 ... Push-up pin, 4 ...
Holder, 5 ... Clamp ring, 7 ... Al film, 8 ... Adhesion part, 10 ... Sputtering chamber, 11 ... Chamber, 12 ... Main valve, 13 ... Vacuum exhaust pump, 14 ... Gas supply pipe, 1
5 ... Introduction valve (V1), 17 ... Adjustment chamber, 18 ... Gas supply pipe, 19 ... Introduction valve (V2), 25 ... Branch pipe, 26
... Relief valve (V4), 27 ... Second branch pipe, 28
... Exhaust valve (V3), 30 ... Recess, 31 ... Target, 32 ... Transport gate valve, 40 ... Spring, 41 ... Washer, 42 ... Screw, 43 ... Working end.

Claims (4)

[Claims] 1. A holder provided in a sputtering chamber for mounting an object to be processed on an upper surface, a push-up pin for lifting an object to be processed mounted on the holder upward as necessary, and a holder on the holder. A sputtering apparatus having a clamp ring for pressing a placed object to be processed against a holder, wherein the clamp ring is separated from the object to be processed,
The sputtering apparatus is provided with pressing means for pressing the object to be processed against the holder prior to leaving. 2. The pressing means includes a recess provided in a holder portion on the lower surface side of the object to be processed, and a pressure control system for controlling the pressure in the recess and the pressure in the sputtering chamber. The object to be processed is held in a holder by a pressure difference in the recess.
The sputtering apparatus described. 3. The sputtering apparatus according to claim 1, wherein the pressing means is a spring attached to the lower surface side of the clamp ring and elastically pressing down the object to be processed downward. 4. The sputtering apparatus according to claim 2, wherein the sputtering apparatus forms an aluminum thin film.