JPH0855801A - Sputtering apparatus and sputtering method - Google Patents

Abstract

PURPOSE:To cause a secure electric discharge in a space between a target and a work by surrounding this space with a deposit-preventing plate and forming an opening in the side periphery of this plate. CONSTITUTION:An ionized (Ar) gas is introduced into a vacuum chamber 1 and a DC voltage is applied between a wafer W and a target 2, whereby Al particles are sputtered from the surface of the target 2 and buried into the wafer W supported by a susceptor 3 while the gas enteres into the gap at an opening 52 between the target 2 and deposit-preventing plate 3 and into the interior of this plate from the gap between an opening 51 and wafer W and exhausted by a vacuum pump from the plate 5 through an opeing 53. Thus, impurities e.g. water content are separated and scattered from the surface of the plate 5 or wafer W by a heater 3. Since the impurities are exhausted from the inside of the plate 5 with a flow of the Ar gas into an exhaust chamber 11 through the opening 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus and method thereof.

[0002]

2. Description of the Related Art The method of forming a film by sputtering is suitable for processing a large number of wafers because the adhesion of the film is excellent and the control factor is small. This method is performed, for example, by using the sputtering device shown in FIG.
It is applied when forming M bit lines. In this case, an inert gas such as argon (Ar) gas is introduced into the vacuum chamber 61, and the target 62 made of, for example, aluminum is used as a cathode to form the vacuum chamber 61 and the target 62.
A wafer is placed on the heater 64 by applying a voltage between them and forming a magnetic field in the vicinity of the target 62 by the magnet 63 or the like to turn the inert gas into plasma, thereby knocking out aluminum particles from the target 62 and mounting it on the heater 64. The film is formed in a W fine pattern.

At this time, not only the wafer W but also the vacuum chamber 6
Aluminum particles are scattered and the film adheres to the inner wall surface of No. 1 as well, but if the film adheres in this way, cleaning and maintenance of the vacuum chamber 61 are required. However, since cleaning and maintenance of the vacuum chamber 61 require troublesome work and downtime of the apparatus becomes long, a cylindrical deposition-preventing plate 65 is provided at the peripheral edge portion of the target 62 and the wafer W, and the vacuum chamber 61 is The film is prevented from adhering to the inner wall surface. In the apparatus in which the deposition-preventing plate 65 is arranged in this way, the Ar gas is used in
5, the upper gap between the vacuum chamber 61 and the deposition preventive plate 65 and the wafer W.
It enters into the lower side of the target 62 through the gap between and and is turned into plasma.

[0004]

By the way, recently, the integration of semiconductor devices has been further advanced, and the capacity of DRAM is being increased from 4M, 16M to 64M, 256M. As the circuit pattern becomes finer in this way, the aspect ratio of the bit line embedding hole in the memory cell structure of the DRAM also increases, but in this case, it becomes difficult to embed aluminum in the hole without any gaps. it is conceivable that. The reason is,
This is because if the aspect ratio becomes large, it becomes difficult for sputtered particles to reach the inside of the hole, so that the deposition may proceed on the side wall near the entrance of the hole and this part may be blocked to form a cavity inside. .

Therefore, the film forming pressure is set to 0.5 mTorr to 10
Reduce the pressure to a few mTorr and reduce the concentration of Ar gas,
It has become necessary to increase the mean free path of sputtered particles and thereby improve step coverage.

However, in the conventional apparatus, the power supply is turned off after the processing of one wafer W is completed and the power supply is turned on during the processing of the next wafer W. However, if the film forming pressure is lowered in this way. In some cases, a current may not flow within a predetermined time after applying a predetermined voltage. In this case, an alarm will be generated, so the wafer W must be discarded.

The cause of such a discharge failure is that water is mainly generated when the wafer or the deposition preventive plate is heated during film formation and becomes an impurity, but if the Ar gas concentration is low under a low pressure, Ar is generated. The ratio of impurities to gas increases. Therefore, even if the Ar gas is ionized, the ions collide with the impurities and disappear, so that discharge is less likely to occur. Ar gas enters the lower side of the target through the gap of the deposition preventive plate, but if the Ar gas concentration is low under a low pressure, the amount of Ar gas necessary for generating discharge does not enter. And so on,
It is presumed that the factors are especially large.

The present invention has been made under the above circumstances, and an object thereof is to provide a sputtering apparatus and a sputtering method capable of reliably causing discharge.

[0009]

According to a first aspect of the present invention, an area between a target and an object to be processed which is disposed so as to face the target is protected in a vacuum chamber having an exhaust port. A sputtering apparatus which is surrounded by a plate, generates a plasma by applying a voltage between the target and the object to be processed, thereby causing sputtered particles to be emitted from the target, and performing a film forming process on the object to be processed. In the above, the opening is formed in the side peripheral portion of the adhesion-preventing plate.

According to a second aspect of the present invention, in the first aspect of the invention, the opening is formed at a portion of the side peripheral portion of the deposition-inhibitory plate near the exhaust port.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the target is made of a metal material or a semiconductor material.

The invention of claim 4 is the invention of claim 1, 2 or 3.
In the invention described above, the auxiliary deposition preventive plate is disposed between the wall of the vacuum chamber and the deposition preventive plate, at least at a position on the extension of the line of sight of the opening from the target.

According to a fifth aspect of the present invention, a region between a target made of a metal material or a semiconductor material and an object to be processed which is arranged so as to face the target is prevented in a vacuum chamber having an exhaust port. A sputtering method in which a voltage is applied between the target and the object to be processed to generate plasma, which causes sputtered particles to be emitted from the target, thereby performing a film formation process on the object to be processed. The method is characterized in that an opening is formed in a side peripheral portion of the deposition-inhibiting plate, and gas in a region surrounded by the deposition-inhibiting plate is exhausted through the opening.

According to a sixth aspect of the present invention, in the invention according to the fifth aspect, the opening is formed in a portion of a side peripheral portion of the deposition-inhibitory plate near the exhaust port.

The invention of claim 7 is characterized in that, in the invention of claim 5 or 6, the process pressure is 10 mTorr or less.

[0016]

When the deposition preventive plate is disposed so as to surround the region between the target and the object to be processed facing the target and the exhaust opening is formed in the deposition preventive plate, impurities generated inside the deposition preventive plate are formed. Is exhausted smoothly through the opening. Therefore, the amount of impurities is reduced, ionization of the inert gas is not hindered, and the ionized gas necessary for the discharge is secured, so that the discharge is reliably generated. Further, since particles scattered from the opening into the vacuum chamber adhere to the auxiliary deposition preventive plate, it is possible to prevent particles from adhering to the inner wall of the vacuum chamber.

[0017]

1 is a sectional view showing an example of a sputtering apparatus used in the present invention, and FIG. 2 is a cross-sectional plan view thereof. In the figure, reference numeral 1 denotes a vacuum chamber having an exhaust chamber 11 projecting downward, and a gas introduction pipe 12 for introducing an ionized gas, for example, Ar gas, is provided at the upper part of the vacuum chamber 1, and the exhaust chamber 1 is provided. A vacuum pump 13 for vacuum exhausting is connected to the left side surface of 11 through an exhaust port 14. In the vacuum chamber 1, a target 2 supported by a target unit 21 and made of a conductive material such as a metal material or a semiconductor material is vertically installed, and a heater is built in at a position facing the target 2. Susceptor 3
And the wafer W is held vertically by the susceptor 3. At this time, the distance between the target 2 and the wafer W is set to 40 mm, for example.

A DC power supply 22 is connected between the vacuum chamber 1 and the target 2 via a switch 23 so that the target 2 serves as a cathode, and the wafer W is grounded. Further, a magnet 4 is provided inside the target unit 21 on the back surface side of the target 2, and a magnetic field formed by the magnet 4 traps electrons, for example, to form a plasma region.

Outside the target unit 21,
A deposition prevention plate 5 made of, for example, stainless steel or aluminum is provided so as to surround a space sandwiched between the target 2 and the wafer W. As shown in FIG. 3, the deposition preventive plate 5 has a cylindrical shape in which both ends are open and the end on the wafer side is reduced in diameter, and the opening 51 on the wafer W side is formed on the wafer W side. It is formed larger than the diameter. Further, for example, a width of 37.8 m is provided on the side of the exhaust chamber 11 on the side of the deposition preventive plate 5 in order to more effectively exhaust impurities generated inside the deposition preventive plate.
An exhaust opening 53 having a length of m and a length of 577 mm is formed.

Further, between the deposition preventive plate 5 and the inner wall of the exhaust chamber 11 (which is a part of the vacuum chamber), an auxiliary protection is provided in a region including an extended position of the line of sight of the opening 53 from the target 2. The attachment plate 54 is detachably arranged. The auxiliary deposition preventive plate 54 is made of, for example, stainless steel or aluminum as shown in FIG. 4, and prevents aluminum particles emitted from the target 2 through the opening 53 from adhering to the bottom wall and the side wall of the exhaust chamber 11. It is configured to cover the portion. Both the target unit 21 and the deposition preventive plate 5 are detachable, and the attachment unit 5 is installed first, and then the target unit 21 is arranged.

Explaining the sputtering by the above-mentioned apparatus, first, the object to be processed, for example, the wafer W, is transferred onto the susceptor 3 at a position on the right side of FIG. After moving the susceptor 3 to the left side to the position shown in FIG.
The inside is evacuated. Then, an ionized gas such as Ar gas is supplied into the vacuum chamber 1 through the gas introduction pipe 12 for, for example, 10-20
It is introduced at a flow rate of 0 SCCM, and the inside of the vacuum chamber 1 is evacuated by the vacuum pump 13 to a predetermined degree of vacuum, for example 0.5 ×.
It is maintained at 10 ⁻³ Torr to 1 × 10 ⁻² Torr. Then, a DC voltage of, for example, -1500 V is applied between the wafer W and the target 2, and a magnetic field is formed in the vicinity of the target 2 by the magnet 4 to generate plasma of Ar gas, whereby aluminum particles are generated from the surface of the target 2. Wafer W that is struck out and supported by susceptor 3
Of the holes of the DRAM, for example, a recess (fine pattern) having the bottom surface of polysilicon and the side wall of the silicon oxide film is filled with the aluminum particles.

At this time, Ar gas enters the inside of the deposition preventive plate 5 through the gap between the vacuum chamber 1 and the deposition preventive plate 5 on the side of the opening 52 or the gap between the opening 51 and the wafer W, and the vacuum pump 13 opens the opening 53. It is exhausted from the deposition preventing plate 5 via the. Therefore, the heater 3 mainly separates and scatters impurities such as water from the surface of the wafer W or the deposition preventive plate 5, and these impurities are dispersed in the deposition preventive plate 5 through the opening 53 together with the flow of Ar gas. Since it is discharged into the exhaust chamber 11 from one side, in the space sandwiched between the target 2 and the wafer W, A
It is possible to suppress an increase in the ratio of impurities in the r gas.
Further, the Ar gas uniformly flows in the space sandwiched between the target 2 and the wafer W, and the gas pressure distribution in this space is made uniform.

Therefore, 0.5 × 10 ^-3 Torr to 1 × 10
Even under a low pressure of ⁻² Torr, the ratio of impurities to Ar gas can be kept low, so Ar ions do not disappear, and a sufficient amount of Ar gas for discharge generation is sandwiched between target 2 and wafer W. Since it enters the space, the discharge is surely generated, and the discharge can be stabilized.

Since the space sandwiched between the target 2 and the wafer W is surrounded by the deposition preventive plate 5, the target 2
Even if the more struck aluminum particles scatter in a direction different from the surface of the wafer W, the particles adhere to the inner wall surface of the deposition preventive plate 5. Further, since the deposition preventive plate 5 is formed with the opening portion 53, a part of the aluminum particles is discharged into the exhaust chamber 11 through the opening portion 53, but the auxiliary deposition preventive plate is directed in the flying direction of the discharged particles. 54 is present and attached to it. Therefore, it is possible to prevent the aluminum particles from adhering to the inside of the exhaust chamber 11, while preventing the adhesion prevention plate 5 and the auxiliary adhesion prevention plate 5
Since No. 4 is removable, it can be easily washed regularly.

Next, an example of an experiment conducted to confirm the effect of the present invention will be described. Using the above-mentioned device as an experimental device, as the experimental conditions, the internal pressure of the device, the presence or absence of the opening of the deposition preventive plate, the base of the wafer W, ON / OFF of the ion gauge filament which is a vacuum gauge, and the type of magnet are variable. The presence or absence of discharge was inspected. As a method for inspecting the occurrence of discharge, the time change of voltage and current was measured. That is, when discharge occurs, current flows immediately when voltage is applied as shown in FIG. 5 (1), but when no discharge occurs, the voltage reaches the maximum value as shown in FIG. 5 (2). In addition to the case where the current does not flow, the case where the current does not flow even when the predetermined voltage is applied for the predetermined time is included. The experimental results are shown in Table 1. Here, in the table, the number of occurrences of defective discharge indicates the number of inspections in the numerator and the number of discharges in which the denominator did not occur.

[0026]

[Table 1] Next, experimental conditions and results will be described. Experiments 1 to 4
Is the case of using the deposition-inhibitory plate in which the opening is not formed, and Experiments 5 to 8 are the cases of using the deposition-inhibition plate in which the opening is formed. Further, when the opening is not formed, the pressure inside the apparatus is changed in Experiment 1 and Experiment 2, the base of the wafer and the ion gauge are changed in Experiment 2 and Experiment 3, and the magnet is changed in Experiment 3 and Experiment 4. Is being inspected,
In each of the experimental examples, defective discharge occurred.

On the other hand, when the opening is formed, in Experiment 5, the other conditions are the same as those in Experiment 4, but no discharge failure occurs, and in Experiment 6, film formation is actually performed under the same conditions as Experiment 5. Although the treatment was performed, no defective discharge occurred.
Further, in Experiment 7, the number of processed sheets was increased, but no discharge failure occurred. Furthermore, in Experiment 8, the inspection was performed by changing the substrate, ion gauge, and magnet of the wafer, but no discharge failure occurred.

From the above results, the cause of the defective discharge is
It has been confirmed that there is an opening in the deposition-inhibiting plate, not in the base of the wafer, ion gauge, or magnet.By forming an opening in the deposition-inhibiting plate, it is possible to prevent the occurrence of defective discharge and ensure It was also confirmed that a discharge could occur. It was also confirmed that the lower the pressure of the process gas, the easier the remarkable effect tends to be obtained.

In the above, in the present invention, the exhaust opening may be formed in the side peripheral portion of the deposition-inhibitory plate, which is far from the exhaust port, for example, on the gas introduction side.

[0030]

According to the present invention, since the opening is formed in the deposition preventive plate, it is possible to surely cause the discharge as described above. In this case, by providing the auxiliary deposition preventive plate, it is possible to prevent the sputtered particles emitted from the opening from adhering to the inner wall of the vacuum chamber.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a sputtering apparatus for carrying out the present invention.

FIG. 2 is a plan view showing an example of a sputtering apparatus for carrying out the present invention.

FIG. 3 is a perspective view showing an attachment prevention plate of the present invention.

FIG. 4 is a perspective view showing an example of a sputtering apparatus for carrying out the present invention.

FIG. 5 is a characteristic diagram showing changes over time in voltage and current, for explaining a method for inspecting discharge occurrence.

FIG. 6 is a cross-sectional view of a conventional sputtering device.

[Explanation of symbols]

 1 Vacuum Chamber 11 Exhaust Chamber 13 Vacuum Pump 2 Target 21 Target Unit 3 Susceptor 4 Magnet 5 Protective Plate 53 Opening 54 Auxiliary Protective Plate

Front page continued (72) Inventor Tsuyoshi Yamauchi 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd. (72) Inventor Yasushi Katsukawa 2-3-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Tokyo Electron Limited (72) Inventor Susumu Ota 2-3-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Tokyo Electron Ltd.

Claims (7)

[Claims] 1. A vacuum chamber in which an exhaust port is formed,
A target and an area between the object to be processed arranged so as to face the target are surrounded by a deposition preventing plate, and a voltage is applied between the target and the object to generate plasma,
This will release sputtered particles from the target,
A sputtering apparatus for performing a film forming process on the object to be processed, wherein an opening is formed in a side peripheral portion of the deposition preventing plate. 2. The sputtering apparatus according to claim 1, wherein the opening is formed at a portion of a side peripheral portion of the deposition preventive plate near the exhaust port. 3. The sputtering apparatus according to claim 1, wherein the target is made of a metal material or a semiconductor material. 4. Between the wall of the vacuum chamber and the deposition preventive plate,
4. The sputtering apparatus according to claim 1, wherein the auxiliary deposition preventive plate is disposed at a position on the extension of the line of sight of the opening from the target. 5. In a vacuum chamber having an exhaust port,
A region between a target made of a metal material or a semiconductor material and an object to be processed arranged so as to face the target is surrounded by an adhesion preventing plate, and a voltage is applied between the target and the object to be processed. In this sputtering method, in which plasma is generated, and thereby sputtered particles are emitted from the target to form a film on the object to be processed, an opening is formed in a side peripheral portion of the deposition-inhibitory plate, A sputtering method, characterized in that gas in a region surrounded by a deposition plate is exhausted through an opening. 6. The sputtering method according to claim 5, wherein the opening is formed in a portion of the side peripheral portion of the deposition-inhibitory plate near the exhaust port. 7. The sputtering method according to claim 5, wherein the process pressure is 10 mTorr or less.