JP2895505B2 - Sputtering equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thin film forming apparatus used in a part of a manufacturing process of a semiconductor integrated circuit. And a sputtering film forming apparatus for forming a thin film using a sputtering phenomenon generated by the sheath voltage.

[Prior Art] Conventionally, a sputtering film forming apparatus is mainly used for forming an Al thin film used for wiring in a semiconductor integrated circuit (hereinafter, IC).

With the recent advances in technology and the ultra-miniaturization of ICs,
Various requirements have been output for the formation of Al thin films. In addition, the out is also used in the formation of substances other than such as SiO ₂ Al.

The initial sputtering film forming apparatus was as simple as placing a wafer, which is a thin film-forming object, and a target in a vacuum chamber, and applying DC or RF power between them. Later, in order to cope with mass processing of wafers, a badge type device for processing a plurality of wafers at once was developed. At present, single wafer type planar magnetron sputtering equipment has become the mainstream of production equipment due to the demand for high quality thin film materials and the proposal of high-speed film formation by magnetron discharge sputtering (“Basics of thin film production”).
Tatsuo Mato, Nikkan Kogyo Shimbun page 119).

[Problems to be Solved by the Invention] However, the following problems are presently a problem.

Generally, when a thin film is formed by sputtering, the wafer surface is cleaned by Ar sputtering impact before film formation. However, the surface of the cleaned wafer is quickly removed from the residual gas (mainly H ₂ O, N ₂ , C
O ₂ ). In the case of the Al film for wiring, this contamination forms oxides and nitrides between the wafer surface and the aluminum wiring and hinders ohmic contact. Further, when exchanging the target, it is necessary to open the film formation chamber to the atmosphere. At this time, gas molecules in the atmosphere such as H ₂ O, N ₂ , and CO ₂ are adsorbed on the walls of the deposition chamber. As a result, gases such as H ₂ O, N ₂ , and CO ₂ adsorbed on the walls during film formation are desorbed and mixed as impurities into the film being formed or adhere to the target surface. , Causing plasma instability. In order to avoid this, conventionally, it has been necessary to exhaust the gas for a long time after replacing the target.

Also, a part of the sputtered target material,
When it adheres to the wall of the film forming chamber and the pressure in the film forming chamber increases when the target or the wafer is replaced, it is detached again as particles. This is a factor that deteriorates the yield rate in the IC process and the like.

[Object of the Invention] Accordingly, an object of the present invention is to eliminate contamination by residual gas in a vacuum vessel, improve the film quality of a deposited film, and significantly improve the bonding characteristics at the interface between a wafer and the deposited film. An object of the present invention is to provide a sputtering film forming apparatus.

Another object of the present invention is to provide a sputtering film forming apparatus having a high operating rate that can easily perform target replacement in a vacuum and perform preparation of a deposited film in a short time without being affected by impurity contamination. To provide.

Another object of the present invention is to provide a sputtering film forming apparatus which suppresses generation of particles and increases the yield of the process.

[Means for Solving the Problems] The gist of the present invention is to provide a sputtering film forming apparatus for irradiating a surface of a target material with ions, thereby adhering sputtered particles of the target material to a substrate surface to form a thin film. , A substrate cleaning chamber for cleaning a substrate surface by a dry process before film formation, a transfer chamber provided with a substrate and target transfer device, and an introduction for introducing the substrate and target from the atmosphere into the device. Wherein the film forming chamber and the substrate cleaning chamber are independently connected to the transfer chamber via a valve having an opening diameter through which the substrate and the target can pass. chamber and having said substrate cleaning chamber respectively ultrahigh vacuum exhaust system and the deposition chamber pressure of 10 ^-10 torr or more of the transport chamber and the substrate cleaning chamber It is evacuated to present in the sputtering film forming apparatus according to claim.

[Operation] Hereinafter, the configuration and operation of the present invention will be described together with the knowledge obtained in forming the present invention.

In order to solve the above problems, the present inventors have considered the following matters.

After cleaning, a film is formed before the impurity gas adheres to the wafer surface. That is, the residual gas molecules in the vacuum vessel are reduced, so that the impurity gas does not reach the wafer surface.

 The above is shown by the following equation.

The number Z of gas molecules incident on the wafer surface is as follows: Z (cm ⁻² · sec ⁻¹ ) = n (8RT) ^1/2 / 4πm (1) n: gas molecule density R: gas constant m: gas molecule It is obtained by mass, and the amount attached to the wafer surface can be obtained by multiplying Z by the adhesion coefficient. The time required for the impurity gas molecules to cover the wafer surface is obtained from the following equation from Z obtained from (1).

t (sec) = 5 × 10 ¹⁴ (cm ⁻² ) / (Z × a) (2) a: Adhesion coefficient (approximately 0.9 in H ₂ O) Generally, the time from the cleaning of a wafer to the start of film formation. It takes about 60 seconds. 5 × 1 pressure in the transfer chamber
At 0 ^-10 torr, wafer surface contamination is mainly due to residual gas.
Assuming H ₂ O, the wafer surface is covered in 5000 seconds according to the equations (1) and (2). Therefore, if the transfer chamber is maintained at 5 × 10 ⁻¹⁰ torr, the contamination on the wafer surface becomes about 1% and can be ignored.

When replacing the target, do not open the film formation chamber to the atmosphere.
That is, similarly to the wafer, the target is introduced into the film forming chamber via the introduction chamber and the transfer chamber, and is fixed to the target holder.

In order to remove the target material attached to the film forming chamber wall, when the target material on the film forming chamber wall reaches a certain thickness, the target and the wafer are taken out to the transfer chamber, and the film forming chamber is cleaned by plasma etching. After the cleaning of the film forming chamber is completed, the target is fixed to the target holder in the film forming chamber again, and the film is formed.

2000-3000 μm of target material adhered to the deposition chamber wall
Becomes a source of particles. Therefore,
It is most economical to clean the film forming chamber when the thickness of the attachment portion becomes 2000 μm. Generally, when etching Al and Si by plasma etching, the etching rate is about 1 μm / min. Therefore, it takes about one hour to clean the film forming chamber by plasma etching. During the cleaning of the film forming chamber, the target is held in the transfer chamber, so that the target surface is contaminated by residual gas in the transfer chamber. To avoid this, it is necessary to set the pressure in the transfer chamber to about 5 × 10 ⁻¹¹ torr according to equation (2). By keeping the pressure in the transfer chamber at 5 × 10 ⁻¹¹ torr, the target surface is contaminated by only about 1% even after being left for one hour, and film formation can be started immediately. From the time of wafer exchange,
It is necessary to lower the pressure during cleaning of the film forming chamber.
In addition, it is easily presumed that if surface cleaning by pre-sputtering of the target is used in combination, it can be carried out in some cases even at about 10 ^-10 torr with a contamination degree of about 10%.

In order to satisfy the above conditions, an introduction chamber that can independently evacuate and introduce a wafer and a target from the atmosphere to the transfer chamber is required. In addition, the transfer of the wafer and the target between the introduction chamber and the transfer chamber is performed by vertically moving the introduction chamber and the transfer chamber, and moving the vacuum-sealed transfer rod easily, resulting in a highly reliable configuration. .

When transferring the wafer and target between the introduction chamber and the loading chamber, when the target is light or magnetic coupling with a large magnetic flux density is used, a magnetic coupling transfer rod can be used. When the transfer rod is extremely heavy, the reproducibility of each elevating movement is not good with the transfer rod of the magnet couple type.

More preferably, the mechanism is vacuum-sealed with a bellows, and a mechanism that can be driven from the atmosphere by a motor improves reliability.

The transfer of the wafer and the target between the transfer chamber and the film forming chamber or between the transfer chamber and the etching chamber can be sufficiently performed by the horizontal movement. ^-11 t
Orr level pressure can be obtained.

In addition, the transfer of the wafer and the target between the transfer rod and the wafer holder and the target holder in the film forming chamber and the etching chamber can be easily performed by vertically moving the transfer rod as a whole. The wafer and target holding of the transfer rod between the film forming chamber and the transfer chamber can be carried at the same time by placing them vertically at the tip of one rod, so that the wafer and target can be carried at the same time. Reliability can be increased by simplification of the device.

EXAMPLES Hereinafter, the sputtering film forming apparatus of the present invention will be described in detail with reference to the drawings.

FIGS. 1 to 3 show diagrams of an apparatus embodying the present invention,
FIG. 4 shows the operation of each part when replacing the wafer and the target.

By this operation, each chamber of the transfer chamber, the film formation chamber and the etching chamber is kept at a vacuum, and the pressure of the film formation chamber and the transfer chamber is set to 10 ^-10 torr
It can be held below.

The operation of each part at the time of wafer replacement will be described step by step. 4 (1) to (10) are cross-sections as viewed from the direction A in FIG.

FIG. 4 (1) A wafer is placed on the table 3 and the introduction chamber 14 is evacuated.

FIG. 4 (2) After the pressure in the introduction chamber 14 reaches a level of 10 ⁻⁸ torr, the gate valve 4 is opened, and the wafer is transferred to the transfer chamber by the vertical transfer rod 2 (hereinafter abbreviated as “transfer rod 2”). ). At this time, transfer rod 1 for horizontal movement between etching chamber and transfer chamber
(Hereinafter abbreviated as "transfer rod 1") moves below the wafer.

FIG. 4 (3) The transfer rod 2 is lowered, and the wafer is on the transfer rod 1. Then, the gate valve 4 closes.

FIG. 4 (4) The gate valve 7 is opened, and the transfer rod 1 advances to above the wafer holder 6 with the wafer placed thereon.

FIG. 4 (5) The transfer rod 1 is lowered while being held horizontally, and the wafer is placed on the wafer holder 6.

FIG. 4 (6) The transfer rod 1 leaves the etching chamber 15 while descending, and returns to the position of FIG. 4 (1). Thereafter, the gate valve 7 closes. The wafer placed in the etching chamber is now plasma etched by Ar or active gas plasma. During that time, the transfer chamber is evacuated.
It is kept at 10 ^-11 torr.

FIG. 4 (7) After the completion of the wafer etching, the gate valve 7 is opened, and the transfer rod 1 moves below the wafer while being lowered horizontally.

FIG. 4 (8) The transfer rod 1 rises horizontally to lift the wafer.

FIG. 4 (9) The transfer rod 1 returns to the transfer chamber with the wafer mounted thereon and stops on the table 5. Gate valve 7 closes.

FIG. 4 (10) The table 5 is raised, and the wafer is lifted from the transfer rod 1. Then, the transfer rod 1 returns to the position shown in FIG.

4 (11) to (20) are cross-sectional views as viewed from the direction B in FIG.

FIG. 4 (11) The gate valve 8 is opened and the transfer rod 11 for horizontal movement between the film forming chamber and the transfer chamber (hereinafter abbreviated as “transfer rod 11”) is lowered horizontally and the wafer is placed under the wafer on the wafer holder 10. Insert the fork. (The black wafer in the figure shows the film formed, and the white wafer shows the film before the film formation.) FIG. 4 (12) The transfer rod 11 rises, lifts the wafer, and returns to the transfer chamber. The gate valve 8 closes.

FIG. 4 (13) The table 5 is raised, and the wafer is lifted from the transfer rod. Then, the transfer rod 11 returns to the position shown in FIG.

FIG. 4 (14) The table 5 rotates, and the etched wafer comes on the transfer rod 2.

4 (15) The table 5 is raised, the transfer rod 11 is advanced, and the wafer fork of the wafer transfer rod 11 is positioned below the new wafer on the table 5. After that, the table 5 descends and the gate valve 8
Opens. Then, the transfer rod 11 advances to the film forming chamber and stops on the wafer holder 10. Then, the transfer rod 11 descends horizontally, and the wafer holder 10
Place the wafer on the top. Thereafter, the transfer rod 11 returns to the position shown in FIG. 4A, the gate valve 8 closes, and a film can be formed.

FIG. 4 (16) When the gate valve 8 is closed, the table 5 is rotated and stopped at a position where the film-formed wafer (black wafer in the figure) is on the transfer rod 2.

FIG. 4 (17) The table 5 is raised. Thereafter, the transfer rod 11 is advanced, and the transfer rod 11
Stop at a position where the wafer fork is below the wafer.
Thereafter, the table 5 is lowered.

FIG. 4 (18) The table 5 is rotated so that the cut portion of the table 5 comes above the gate valve 4. Then, the gate valve 4 opens, the transfer rod 2 rises, and lifts the wafer from the transfer rod 11.

FIG. 4 (19) The transfer rod 11 returns to the position of FIG. 4 (1).

FIG. 4 (20) The transfer rod 2 supporting the wafer is lowered below the table 3 and the wafer is placed on the table 3. Then, the gate valve 4 closes.

Next, the operation of each unit when the target is replaced will be described.

FIG. 5 (1) A new table is set on the table 3 and the introduction chamber 14 is evacuated.

FIG. 5 (2) When the pressure in the introduction chamber 14 reaches 10 ^-8 torr, the gate valve 4 is opened, the transfer rod 2 is raised, and the target is lifted to a position higher than the transfer rod 11. Then, the transfer rod 11 is advanced so that the target fork of the transfer rod 11 is located below the target.

Fig. 5 (3) Lower the transfer rod 2,
The target is placed on the transfer rod 11. Thereafter, the gate valve 4 is closed. Then, the table 5 is rotated so that the sample holder section is at a position above the gate valve 4.

FIG. 5 (4) The table 4 is raised, and the target on the transfer rod 11 is lifted.

5 (5) Return the transfer rod 11 to the position shown in FIG. 5 (1), lower the table 5 on which the target is placed, and rotate the table 5 so that the sample holder portion of the table 5 is positioned above the gate valve 4.

FIG. 5 (6) The gate valve 8 is opened and the target fork of the transfer rod 11 is advanced so as to be below the target holder 9. Then, the transfer rod 11 is raised horizontally and brought into contact with the target held by the target holder. Thereafter, the power of the electrostatic chuck embedded in the target holder 9 is turned off, and the target is dropped on the transfer rod 11.

FIG. 5 (7) The transfer rod 11 on which the target is placed is retracted to above the sample holder portion of the table 5 and the gate valve 8 is closed.

FIG. 5 (8) The table 5 is raised, the target is lifted from the transfer rod 11, and the transfer rod 11 is returned to the position shown in FIG. 5 (1).

FIG. 5 (9) The table 5 is rotated so that a new wafer is positioned on the gate valve 4.

FIG. 5 (10) The table 5 is raised, and the transfer rod 11 is advanced so that the target fork of the transfer rod 11 is below the new target. Then, the table 5 is lowered, the gate valve 8 is opened, and the transfer rod 11 is moved forward so that the target is positioned below the target holder 10. A voltage is applied to the mounted electrostatic target to fix the target.
Then, after lowering the transfer rod 11, the transfer rod 11 is returned to the position shown in FIG. 5A, and the gate valve 8 is closed.

By using all and a part of the embodiment shown above,
The target and the wafer can be held in the transfer chamber when the target and the wafer are exchanged and when the film forming chamber is cleaned. As a result, the walls of the film forming chamber and the transfer chamber are always kept clean, and high-quality film can be continuously formed for a long time.

[Effects of the Invention] As described above, in a sputtering film forming apparatus, a film forming chamber, a wafer cleaning chamber, a transfer chamber including a wafer and a target transfer apparatus, and introduction of introducing a wafer and a target from the atmosphere into the apparatus. By evacuating the pressure of the film forming chamber and the transfer chamber to 10 ^-10 torr or more, the influence of the impurity gas on the deposition can be eliminated.

In addition, since the wafer and the target can be transferred from the introduction chamber to the film formation chamber via the transfer chamber by the linear introduction machine provided with the fork at the tip, it is easy to exchange the wafer and the target under high vacuum. Become.

Furthermore, since the transfer chamber has a holder capable of holding a plurality of targets, continuous multilayer film stacking and deposition of various materials can be performed in a short time with good reproducibility without breaking vacuum.

Furthermore, by performing between the film forming chamber and the transfer chamber with a magnetically coupled linear transfer linear introduction machine, and between the introduction chamber and the transfer chamber with a vertical movement linear transfer machine using a bellows seal,
A highly reliable device can be obtained with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing the configuration of the entire apparatus according to the present invention, and FIG.
FIG. 3 is a cross-sectional view as viewed from the direction A in FIG. 1, and FIG.
Sectional drawing seen from the B direction in a figure. FIG. 4 is a view for explaining the movement of each part at the time of wafer replacement, FIG. 5 is a view for explaining the movement of each part at the time of target replacement, and FIG. 6 is the transfer in FIGS. 1 and 3. In the sample holding fork of the rod 11, (a) is a diagram viewed from the side, and (b) is a diagram viewed from above. 1. Transfer rod for horizontal movement (etching chamber,
(Between transfer chambers), 2 ... Transfer rod for vertical movement (for elevating sample), 3 ... Sample table for introduction chamber, 4 ...
Gate valve, 5: sample table for transfer chamber, 6: wafer holder for etching, 7: gate valve, 8: gate valve, 9: target holder, 10: wafer holder for film formation, 11: transfer rod for horizontal movement (Between the film chamber and transfer chamber), 12: transfer chamber, 13: deposition chamber, 14: introduction chamber, 15: etching chamber, 16: introduction chamber door, 17: transfer rod lifting / lowering cylinder, 18: transfer rod lifting / lowering cylinder , 19… Cylinder for gate valve operation,
20: transfer rod lifting motor, 21: table lifting motor, 22: table rotation motor, 23 ... cryopump, 24 ... cryopump, 25 ... cryopump, 26 ... vacuum gauge, 27 ... vacuum gauge, 28 ... vacuum 29, table rotation motor, 30 ... gate valve operation cylinder,
31: Gate valve operating cylinder, 32: Cryopump, 33: Heater for wafer heating, 34: Power supply for heater,
35: electrostatic chuck for holding the target, 36: power supply for the electrostatic chuck, 38: high frequency power supply for sputtering, 39: bellows for lifting and lowering the transfer rod, 40 ... bellows for raising and lowering the transfer rod.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 14/34

Claims (5)

(57) [Claims] 1. A surface of a target material is irradiated with ions.
In a sputtering film forming apparatus for forming a thin film by attaching particles of a target material sputtered on the surface of a substrate to form a thin film, a substrate cleaning chamber for cleaning the substrate surface by a dry process before film formation; It has a transfer chamber provided with a target transfer device, and an introduction chamber for introducing the substrate and the target into the apparatus from the atmosphere, and the film forming chamber and the substrate cleaning chamber are opened so that the substrate and the target can pass through. The film forming chamber, the transfer chamber, and the substrate cleaning chamber each have an ultra-high vacuum exhaust system respectively connected to the transfer chamber via a valve having a diameter, and the film forming chamber and the transfer chamber And a pressure in the substrate cleaning chamber is evacuated to 10 ⁻¹⁰ torr or less. 2. The horizontal movement of the substrate and the target between the film forming chamber and the transfer chamber is performed by a transfer rod for horizontal movement by magnetic coupling, and the transfer between the transfer chamber and the introduction chamber is performed. The sputtering film forming apparatus according to claim 1, wherein the movement of the substrate and the target is performed by a transfer rod for vertical movement by a bellows seal. 3. The base support unit and the target support unit according to claim 2, wherein different forks for the base and the target are attached to the distal end of the horizontal transfer rod. Sputtering film forming equipment. 4. The transfer rod for horizontal movement and the transfer chamber are connected by a bellows, and the transfer rod for horizontal movement can be attached and detached within the elastic range of the bellows. 4. The sputtering film forming apparatus according to claim 2, wherein the step is performed by vertically moving or changing the angle of the transfer rod for horizontal movement. 5. The sputtering film forming apparatus according to claim 1, further comprising a holder capable of holding a plurality of said targets in said transfer chamber.