KR0182092B1 - Sputtering apparatus and sputtering method - Google Patents

Abstract

The present invention is to provide a sputtering apparatus capable of reliably generating a discharge even at low pressure or low concentration of reaction gas. The sputtering apparatus includes a housing having a processing chamber therein, a target disposed within the housing, Supporting the object to be opposed to the target at intervals, and in this way, support means having a space portion defined between the target and the object, means for evacuating the inside of the housing, and between the target and the object to be processed. Plasma generating means for generating plasma and thereby discharging spatter particles from the target, and means for depositing means provided in the housing, the means for protecting the target body and the cylinder surrounding the target and the space portion, An opening formed at one end and formed on the exhaust means side of the cylinder to discharge impurities generated by the generation of plasma therein; Is configured to have an opening.

Description

Sputtering device

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view schematically showing an example in a sputtering apparatus embodying the present invention.

2 is a cross-sectional view of the sputtering apparatus.

3 is a perspective view showing a protective plate used in the present invention.

4 is a perspective view showing a portion of a sputtering apparatus of the present invention cut away.

5A and 5B are characteristic diagrams showing time-dependent changes in voltage and current for explaining a method of inspecting discharge generation.

6 is a schematic cross-sectional view of a conventional sputtering apparatus.

* Explanation of symbols for main parts of the drawings

1 housing 1a main housing

2: target 5, 65: barrier plate

11: auxiliary housing 14: exhaust port

53: opening

The present invention relates to a sputtering apparatus using plasma.

The method of forming a film by sputtering is excellent in adhesion to the substrate of the film and there is little control factor thereon, which is suitable for mass processing of wafers. This method is applied to, for example, the case of forming a bit line of a DRAM as the sputtering apparatus shown in FIG. In this case, an inert gas such as argon (Ar) gas or the like is introduced into the vacuum chamber 61 and placed in the vacuum chamber 61 using, for example, a target 62 made of aluminum as a cathode. The vacuum chamber and the target 62 and At the same time, while applying a voltage, the rotating magnet 63 or the like forms a rotating magnetic field in the vicinity of the target 62 to form an inert gas, thereby removing aluminum particles from the target 62 and heating the heater. A film is formed on the fine pattern of the wafer W placed on (64).

At this time, not only the wafer W but also aluminum particles are scattered on the inner wall surface of the vacuum chamber 61 to form only an aluminum film. However, when such a film adheres, cleaning or maintenance of the vacuum chamber 61 is required. However, the cleaning and maintenance of the vacuum chamber 61 not only requires very cumbersome hands but also increases the downtime of the apparatus. For this reason, the cylindrical adhesion plate 65 is arrange | positioned at the peripheral part of the target 62 and the wafer W, and the film adheres to the inner wall surface of the vacuum chamber 61. As described above, in the apparatus in which the anti-glare plate 65 is disposed, the Ar gas is targeted from the upper gap between the anti-glare plate 65 and the inner wall surface of the vacuum chamber 61 or the gap between the anti-glare plate 65 and the wafer W. It enters into the lower side and becomes plasma.

In recent years, the integration of semiconductor devices has been further advanced, and the capacity of DRAM has been increased from 4M and 16M to 64M and 256M, and the circuit pattern has to be miniaturized. If the circuit pattern is made fine in this manner, for example, the aspect ratio of the bit line filling hole in the memory cell structure portion of the DRAM also increases, but in this case, it is considered that it is difficult to embed, for example, aluminum without gaps in the hole. The reason for this is that as the aspect ratio increases, it is difficult for the spatter particles to reach the depths of the hole, so that the traces may progress from the sidewalls close to the hole entrances, which may cause the parts to close and form a cavity therein.

Therefore, it is necessary to lower the film forming pressure to 0.5 mTorr to 10 mTorr, to lower the concentration of Ar gas, to increase the average free stroke of the spatter particles, thereby improving the step coverage.

However, in the conventional apparatus, the power supply is turned off after the processing of one wafer W is finished, and the power supply is turned on during the processing of the next wafer W. After the voltage is applied, the current may not flow within a predetermined time, and in this case, the alarm W will have to be discarded so that the wafer W has to be discarded.

As a cause of such discharge failure, (1) moisture is mainly generated when the wafer or the adhesion plate is heated during film formation, and this becomes an impurity, and when the Ar gas concentration is low under low pressure, the ratio of impurities to Ar gas increases. For this reason, even if Ar gas is ionized, it collides with an ion impurity and disappears, and it becomes difficult to generate discharge. (2) Ar gas penetrates into the lower side of the target from the gap of the deposition plate, but if the Ar gas concentration is low under low pressure, the amount of Ar gas necessary for generating discharge does not penetrate. Etc. are considered, and it is estimated that the factor of (1) is large especially.

An object of the present invention is to provide a sputtering apparatus that can surely cause a discharge even at a low pressure or a low concentration of the reaction gas.

According to the present invention, a sputtering apparatus includes a housing having a processing chamber therein, a target disposed in the housing, and an object to be processed so as to face each other at a distance from the target, so that a space is formed between the target and the object. A defined device means, means for evacuating the interior of the housing, plasma generation means for generating a plasma between the target and the object to be treated, thereby releasing spatter particles from the target, and a room provided in the housing. The means for attaching the target means and the space means includes a cylinder surrounding the target and the space portion, an opening formed at one end on the side of the object to be processed, and impurities formed by the generation of plasma therein at the exhaust means side of the cylinder. It is provided to have an opening for discharging.

In the said sputtering apparatus, when a barrier plate is arrange | positioned so that the area | region between a target and the to-be-processed object corresponding to this may be formed, and an opening part for exhaust gas will be formed in a barrier plate, the impurity which generate | occur | produced inside the guard plate may pass through an opening part. Exhaust naturally. Therefore, since the amount of impurities is reduced, the ionization of the inert gas is not disturbed, and since the ionizing gas necessary for the discharge is secured, the discharge is surely generated. In addition, the particles scattering in the vacuum chamber at the opening portion are attached to the auxiliary deposition plate, so that the particles adhere to the vacuum chamber inner wall.

In FIG. 1 and FIG. 2, the code | symbol 1 has shown the housing which has the main housing 1a which achieves sputtering, and the auxiliary housing 11 which protrudes below this main body and comprises an exhaust chamber.

The main housing 1a has a cylindrical shape extending in the horizontal direction, and is divided into a wafer detachment chamber and a plasma generating chamber by a partition wall having an opening for susceptor insertion therein. One end side (the right side in FIG. 1) of the main housing 1a on the side of the wafer detachment chamber is closed. Although not shown, the closed wall is provided with a known gate valve that enables conveyance and removal of the wafer to the housing. The opening 52a to which the target unit mentioned later is attached is formed in the closing wall 52 of the other end side (left side in FIG. 1) of the main housing 1a by the side of a plasma generation chamber. In the upper part of the plasma generating chamber side of the main housing 1a, a gas introduction pipe 12 for introducing, for example, Ar gas, which is an ionization gas, is installed, and a vacuum for evacuating the inside of the housing is provided on the opposite side of the auxiliary housing 11. The pump 13 is connected via the exhaust port 14. In this housing 1, a target 2 made of a conductive material such as a metal material or a semiconductor material supported on one end surface of the target unit 21 is provided vertically. The target is formed of, for example, titanium, titanium nitride, aluminum or aluminum alloy, preferably aluminum or aluminum alloy. The unit 21 is formed of a metal such as aluminum, and includes a main body composed of a cylindrical body, a permanent magnet 4 rotatably disposed in the main body, and a motor 4a for rotating the magnet 4. Consists of. The permanent magnet 4 is made of, for example, plank stones of which both ends are different in polarity. The permanent magnet 4 is attached to the rotational axis of the motor 4a, rotates in a plane parallel to the wafer, and the wafer W and the target 2 Generate a magnetic field between the and.

Electrons are trapped in this rotor field to generate plasma. As shown in FIG. 1, the unit 21 is detachably inserted into the main housing 1a at one end to which the target 2 is attached. The susceptor 3 incorporating a heater is disposed at an opposite position of the target 2, and the susceptor 3 holds the wafer W vertically. At this time, the distance between the target 2 and the wafer W is preferably set to 35 mm to 45 mm, for example, 40 mm. The susceptor 3 is in the range of 90 ° to the main housing 1a, i.e., the processing position for vertically supporting the wafer as shown in FIG. It is supported so as to be rotatable between. Loading of the wafer to be processed onto the susceptor through the gate at the transfer position and to the outside of the apparatus of the processed wafer are performed.

The wafer W supported by the susceptor 3 is grounded through the housing 1, and the cathode of the DC power supply 22 is switched to the target 2 so that the target 2 becomes the cathode. It is connected via.

For example, an adhesion plate 5 made of metal such as stainless steel or aluminum is disposed so as to surround the space where the outer circumferential side of the target unit 21 and the target 2 are inserted into the wafer W. The anti-corrosion plate 5 is coaxial with the target unit 21, and the proximal end is detachably attached to one end wall of the main housing 1a so as to define an annular space different from the outer circumferential surface of the unit 21. Attached. As shown in FIG. 3, this anti-corrosion board 5 has the main body of the cylindrical shape 5a which opened both ends, and the protrusion installation piece 5b which protruded inclined inwardly from the front end side of this main body. This protruding piece may be formed over the entire circumference of the circular tip, but is formed along approximately half the circumference in this preferred embodiment. The opening 51 on the side of the wafer W on which the protruding pieces of the adhesion plate 5 are formed is formed larger than the diameter of the wafer W. As shown in FIG. An opening 53 is formed on the side of the auxiliary housing 11 of the side wall portion of the adhesion plate 5 to more effectively exhaust impurities generated inside the adhesion plate. This opening portion 53 is not limited to a rectangle as shown in the figure, and may be a polygon or a circle. In this embodiment, the shape is rectangular with a width of 37.8 mm and a length of 577 mm. As shown in FIG. 1, this opening portion 53 is preferably formed at a position where most of the width direction faces the space between the target 2 and the wafer W. As shown in FIG. Instead, the entire width direction of the opening may face the space.

In the sub-housing 11 (part of the housing), the sub-deposition plate assembly 54 is detachably disposed in an area including the position of the prospective extension view of the opening 53 in the target 2. The auxiliary adhesion plate 54 is made of, for example, stainless steel or aluminum, so that the aluminum particles emitted from the target 2 to the opening 53 in the auxiliary housing do not adhere to the bottom wall and the side wall of the auxiliary housing 11. It is comprised in the shape which covers a part. In this embodiment, the auxiliary deposition plate assembly 54 is constituted by three auxiliary deposition plates 54a, 54b, 54c. The first plate 54a is disposed along this inner side surface so as to cover the inner side surface of the auxiliary housing. The second plate 54b is disposed along this inner surface so as to cover the inner surface of one end of the auxiliary housing facing the vacuum pump 13. The third plate 54c is disposed to face the opening 53 at a predetermined interval. These auxiliary release plates 54a, 54b, 54c are each independently provided in the auxiliary housing 11 through an opening 52a formed in the one end closing wall 52 of the housing 1 on which the target unit 21 is mounted. Inserted and mounted. Although not shown, these auxiliary barrier plates are provided with appropriate engaging grooves and protrusions to be assembled by being assembled to each other. The antifouling plate 5 is also inserted into and mounted in the housing through the opening 52a. After these barrier plates 5 and the auxiliary barrier plate assembly 54 are mounted, the unit 21 is inserted into the housing in the opening of the closure wall 52 and fixed to the base end closure wall 52.

Next, a description will be given of the use of aluminum as a target for the sputtering by the above-described apparatus. First, the transfer of the Peter W, for example, the wafer W onto the susceptor 3 at the position on the right side of FIG. It is handed horizontally by a mechanism, for example, it is preserve | saved by electrostatic adsorption, and the susceptor 3 is rotated to the position of FIG. As a result, the wafer W is stored vertically with a predetermined distance from the target 2. In this state, the inside of the housing 1 is evacuated by the vacuum pump 13. Subsequently, an ionizing gas, for example Ar gas, is introduced into the housing 1 at a flow rate of, for example, 10 to 200 SCCM by the gas introduction pipe 12, and the housing 1 is evacuated by the vacuum pump 13. ) Is kept at a predetermined degree of vacuum, for example, 0.5 × 10 ⁻³ Torr to 1 × 10 ⁻² Torr. By applying a DC voltage of −1500 V, for example, to the target 2 and rotating the magnet 4, a magnetic field is formed in the vicinity of the target 2 to generate a plasma of Ar gas. As a result, electrons in the generated plasma collide with the surface of the target 2, and aluminum particles are shaken off from this surface. The aluminum particles enter a recess (fine pattern) having a bottom surface of polysilicon, for example, a DRAM hole of the wafer W supported by the susceptor 3, and having a silicon oxide film as a sidewall. Landfilling is carried out.

At this time, Ar gas is deposited from the gap between the inner surface of the closing wall 52 of the housing 1 and the base end of the deposition plate 5 or the gap between the tip of the adhesion plate 5 and the wafer W. ), And is evacuated by the vacuum pump 13 into the auxiliary housing 11 through the opening plate 53 through the opening plate 53. For this reason, impurities such as moisture are mainly scattered and scattered from the surface of the wafer W or the deposition plate 5 by the heater 3, but these impurities flow through the opening 53 with the flow of Ar gas. Since it is discharged into the auxiliary housing 11 from the inside, the increase of the ratio of the impurity in Ar gas in the space | interval interposed by the target 2 and the wafer W is suppressed. In addition, the Ar gas flows uniformly in the space sandwiched by the target 2 and the wafer W, so that the pressure distribution of the gas in this space becomes uniform.

Therefore, even at a low pressure of 0.5 x 10 ^-3 Torr to 1 x 10 ^-2 Torr, the ratio of impurities to Ar gas is suppressed low, so that Ar ions are not lost and the amount of Ar gas necessary for discharge is generated. Discharging into the space sandwiched by the target 2 and the wafer W, the discharge is surely generated, and the discharge can be stabilized.

Since the space sandwiched by the target 2 and the wafer W is substantially surrounded by the adhesion plate 5, even if the aluminum particles shaken off the target 2 are scattered in a direction different from the surface of the wafer W, the particles are dispersed. It adheres to the inner wall surface of the adhesion plate 5. Moreover, since the mechanism part 53 is formed in the adhesion plate 5, a part of aluminum particle is discharged | emitted into the auxiliary housing 11 from this opening part 53, but the auxiliary adhesion plate assembly 54 is carried out in the scattering direction of the discharge particle | grains. Is present and attached to it. Therefore, the aluminum particles can be prevented from adhering to the auxiliary housing 11, and the anti-detachment plate 5 and the auxiliary anti-deposition plate assembly 54 can be detached from the housing and can be removed from the housing to be easily cleaned regularly. Can be.

The following describes an experimental example performed to confirm the effect of the present invention. The above-described apparatus is used as an experimental apparatus, and the experimental conditions are variable pressures, the presence or absence of openings of the deposition plate, the basis of the wafer W, the ON / OFF of the ion gauge filament which is a vacuum meter, and the type of the magnet. The occurrence of discharge was examined. As a test method of discharge generation, time variation of voltage and current was measured. When discharge occurs, the current gradually flows as shown in FIG. 5B with the solid line display voltage of FIG. 5A that gradually increases the voltage and does not reach the maximum voltage of 1500V. On the other hand, when discharge does not occur, even when the maximum voltage value is reached as indicated by the broken line in FIG. 5A, no current flows as shown in FIG. 5B. The experimental results at this time are shown in Table 1. Here, the number of occurrences of discharge failure in the table indicates the number of inspections for the numerator and the number of generations for which the denominator has not been discharged.

Next, the experimental conditions and the results will be described. Experiments 1 to 3 are used when the protective plate is not formed, and Experiments 4 to 6 are used when the protective plate is formed with the opening. In the case where no opening was formed, the test was performed again by changing the internal pressure of the apparatus in Experiment 1 and Experiment 2, and changing the base and ion gauge of the wafer in Experiment 2 and Experiment 3. This is happening.

On the other hand, in the case where the openings were formed, in Experiment 4, other conditions were the same as in Experiment 3, but no discharge failure occurred. Furthermore, although the number of treatments was increased in Experiment 5, discharge failure did not occur. Moreover, in Experiment 6, the wafer foundation, ion gauge, and magnet were changed and inspected, but no discharge failure occurred.

As a result of the above, it is confirmed that the cause of discharge failure is not in the base of the wafer and the ion gauge, but in the presence or absence of the opening of the deposition plate. By forming an opening in the deposition plate, the occurrence of discharge failure is prevented and reliably. It was also confirmed that it could cause a discharge. It was also confirmed that the lower the pressure of the process gas, the more prominent the effect tends to be.

As mentioned above, in this invention, you may make it the exhaust opening part in the side part of the side surface part of a barrier plate far from an exhaust port, for example, the gas introduction side.

According to the present invention, since the opening is formed in the anti-corrosion plate, discharge can be reliably generated as described above. In this case, by providing the auxiliary release plate, it is possible to prevent the sputtered particles emitted from the openings from adhering to the inner wall of the housing.

Claims (13)

A housing 1 having a processing chamber therein; A target 2 disposed in the housing; Support means for supporting the target object so as to face the target 2 at intervals, and in this way a space portion is defined between the target 2 and the target object; Means for evacuating the inside of the housing (1); Plasma generating means for generating a plasma between the target (2) and the object to be treated, thereby releasing spatter particles from the target; An attachment means provided in the housing 1, wherein the attachment means includes a cylinder surrounding the target 2 and the space portion, an opening formed at one end of the object side of the cylinder, and the exhaust means of the cylinder. The sputtering apparatus characterized by having the opening part which discharges the impurity produced | generated by generation | occurrence | production of a plasma during being formed in the side. 2. The sputtering apparatus according to claim 1, wherein said exhaust means comprises an exhaust port (14) formed on an outer circumference of the housing (1), and said opening portion (53) is located between the exhaust port and the processing chamber. 3. The housing (1) according to claim 2, wherein the housing (1) has a main housing (1a) having a processing chamber therein, and an auxiliary housing (11) communicating with the main housing (1a) and having an exhaust port (14), wherein the opening The sputtering device, characterized in that the anti-seal means is installed inside the housing (1) so that the secondary housing (11) faces. The said plasma generating means is a magnetic field generating means which generates a magnetic field in the said space part, and the voltage generating means which produces a voltage between the target 2 and the to-be-processed object. Sputtering apparatus, characterized in that having a. 5. A sputtering device according to claim 4, having a unit detachable to said housing (1), said unit supporting said target (2) at one end and having a magnetic field generating means therein. The sputtering apparatus according to claim 3, further comprising auxiliary preventing means disposed in the auxiliary housing (11) and preventing the impurities from adhering to the inner surface thereof. 7. The sputtering apparatus according to claim 6, wherein the auxiliary preventing means has a plurality of auxiliary adhesion plates (54a, 54b, 54c) detachably attached to the auxiliary housing (11). 8. The sputtering apparatus according to claim 7, wherein the at least one subsidiary deposition plate has a subsidiary deposition plate arranged to cover it along the inner surface of the auxiliary housing (11). The sputtering apparatus according to claim 8, wherein the adhesion means and the auxiliary adhesion means are made of stainless steel or aluminum. The sputtering apparatus according to any one of claims 1 to 9, wherein the target (2) is formed of a metal or a semiconductor. The sputtering apparatus according to any one of claims 1 to 10, wherein the target (2) is formed of titanium, titanium nitride, aluminum, or an aluminum alloy. The sputtering apparatus according to claim 8, wherein the adhesion means and the auxiliary adhesion means are made of stainless steel or aluminum. A housing 1 having a closing wall with an opening formed at one end thereof and having a processing chamber defined therein; This housing 1; A target unit inserted into the housing (1) via the opening, detachably supported on the closing wall, and supporting the target (2) on the insertion end side; Support means for supporting the target object so as to face the target 2 at an interval of 35 to 45 mm, and thus defining a space portion between the target 2 and the target object; Means for evacuating the housing 1 to maintain a vacuum of 0.5 × 10 ⁻³ Torr to 1 × 10 ⁻² Torr during processing; Plasma generating means for generating a plasma between the target (2) and the object to be treated, thereby releasing spatter particles from the target; Attachment means provided in the housing 1, and the attachment means are formed in the cylinder surrounding the target 2 and the space, an opening formed at one end of the to-be-processed object side of the cylinder, and the exhaust means side of the cylinder. An opening 53 for discharging impurities generated by the generation of plasma in the air; An auxiliary adhesion assembly for preventing the impurities discharged from the opening 53 from adhering to the inner surface of the housing 1, wherein the assembly includes at least one first auxiliary adhesion plate disposed along the inner surface of the housing; A sputtering apparatus, characterized in that it has a second auxiliary barrier plate disposed to face the opening.