TWI444490B - Sputtering method - Google Patents

Description

Sputtering method

The present invention relates to a sputtering method for forming a specific thin film on a surface of a substrate to be processed, and in particular, to use a target which is conductive as a target, and to introduce a reactive gas while reactively splashing A sputtering method for performing film formation by plating.

As one of the methods of forming a specific thin film on the surface of a substrate such as glass or tantalum wafer, there is a sputtering method. The sputtering method accelerates and impacts the ions in the plasma atmosphere toward the target which is formed into a specific shape in accordance with the composition of the film to be formed on the surface of the substrate to be processed, and causes sputtering. The particles (target atoms) scatter and adhere to and deposit on the surface of the processing substrate to form a specific film. In the sputtering, a specific reaction gas such as oxygen or nitrogen is introduced together with a sputtering gas formed of a rare gas, and the sputtering particles are formed by reactive sputtering. The film formed by the compound between the reaction gas and the reaction gas.

Here, in the sputtering apparatus which performs the above-described sputtering method, generally, a mask which is grounded and which functions as an anode is disposed around the target. If the mask is placed around the target as such, when the DC voltage is applied to the target and the plasma is generated in front of the sputtering surface of the target, the electrons or secondary electrons in the plasma will Flows toward the mask. As a result, the plasma density is lowered at the peripheral region of the sputtering surface of the target, and the peripheral region is not sputtered and remains as a non-erosion region.

When the peripheral region of the sputtering surface remains as a non-erosion region, in particular, a conductive target such as aluminum is used as a target, and a reaction gas such as oxygen is introduced and reactive sputtering is used. In the case of forming an oxide film, due to the reverse deposition during reactive sputtering, the oxide system adheres and accumulates in the peripheral region. That is, the peripheral region of the sputtered surface is covered by the insulating film. In this state, at the peripheral region, the electrons in the plasma or the secondary electrons are charged up, which causes an abnormal discharge due to the charging, and may cause a good film formation. The problem of hindrance.

Here, Patent Document 1 knows that when a negative DC voltage is applied to a target and a target is sputtered, the applied voltage is changed to a positive potential with a predetermined pulse period. Sputtering method.

In the sputtering method described in Patent Document 1, the charge charge remaining in the peripheral region of the target during sputtering is canceled when a positive voltage is applied. Therefore, even if the peripheral region of the target is covered with the insulating film, the abnormal discharge (arc discharge) due to charging is suppressed. However, when a positive voltage is applied to the target every time, since the plasma system temporarily disappears, there is a problem that the sputtering rate is lowered. Therefore, the film formation time of one processing substrate becomes long, and the productivity is poor. Further, it is a sputtering power source that is required to apply a voltage that changes polarity with a certain pulse period, resulting in high cost.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 10-237640

The present invention has been made in view of the above, and provides a film which can be formed without being affected by an insulating film formed at a peripheral region of a target, while maintaining a high sputtering speed. A reactive sputtering method that does not cause a high cost is a problem.

In order to solve the above problem, the sputtering method described in the first aspect of the invention is that the sputtering gas and the reaction gas are introduced into the sputtering chamber while being disposed opposite to the processing substrate in the sputtering chamber. A sputtering method in which a conductive film is put into a power, and a plasma atmosphere is formed in a sputtering chamber to perform sputtering on each target, and a specific thin film is formed on the surface of the processing substrate by reactive sputtering. When the integrated value of the electric power input to the target reaches a specific value, the introduction of the reaction gas is stopped, and a sputtering gas is introduced to perform sputtering on the target.

According to the present invention, if the integrated value of the electric power input to the target reaches a specific value, it is judged that the insulation is deposited at the peripheral portion of the sputtering surface of the target due to the reverse deposition at the time of reactive sputtering. And stopping the introduction of the reaction gas, that is, forming a film for processing the substrate temporarily Sexually interrupted. Then, only the sputtering gas formed by the rare gas is introduced, and the target is sputtered. In this state, the conductive sputter particles from the target collide with, for example, electrons in the plasma, and adhere to the peripheral region of the target to be reversely stacked.

At this time, the charge on the insulating film is neutralized and disappeared by sputtering particles or ionized sputtering gas ions, or is made conductive by being constantly sputtered. The target's sputtered surface is again turned on and the peripheral area is turned on, and flows to the target side and disappears. Then, if the insulator in the peripheral region is again covered with the conductive film, the introduction of the reaction gas is started again, and the film formation for the substrate is resumed.

As described above, in the present invention, since the input electric power is not changed when the film is formed on one of the substrates, it is possible to maintain the optimum sputtering rate while maintaining the optimum sputtering rate. The target is sputtered and can achieve high productivity. Further, since the peripheral region of the target is periodically covered by the conductive film having the same composition as the target, the induction of abnormal discharge due to charging is prevented, and it is possible to consistently The target is used and film formation is performed until the end of the life of the target. Further, in order to eliminate the influence on the insulating film formed at the target due to charging, no additional constituent parts are required, and there is no possibility of causing an increase in cost.

Further, in the sputtering method described in the second aspect of the invention, the processing substrate is sequentially transferred to the sputtering chamber, and the sputtering gas and the reaction gas are introduced into the sputtering chamber, and the sputtering chamber is placed therein. The conductive target disposed opposite to the processing substrate is put into the power, and is in the sputtering chamber. a sputtering method in which a plasma atmosphere is formed, a specific thin film is formed on the surface of the processing substrate by reactive sputtering, and is characterized by: if it is input to the target When the integrated value of the electric power reaches a specific value, the dummy substrate is carried to a position facing the target, the introduction of the reaction gas is stopped, and a sputtering gas is introduced to sputter the target.

In the present invention, when the introduction of the reaction gas is stopped, the input power to the target is set to be higher than when the reaction gas is introduced, and the time during which the film formation is interrupted can be shortened, and the production can be shortened. Sexual improvement, but ideal.

In addition, the magnet assembly provided to form a tunnel-shaped magnetic flux in front of the sputtering surface of the target reciprocates in parallel along the back surface of the target, and when the introduction of the reaction gas is stopped The movement width of the magnet assembly is set to be smaller than when the reaction gas is introduced, and the position where the magnetic flux density is increased is directed to the center side of the sputtering surface of the target, and is reversed at the peripheral region. The deposited conductive film is extended to the center side thereof, and as a result, the peripheral region of the target can be surely covered by a film having the same composition as the target.

As described above, the sputtering method of the present invention can obtain the effect that it is not affected by the insulating film formed at the peripheral region of the target, and can be maintained. The film is formed in a state of high sputtering speed without causing cost increase.

Referring to Fig. 1 and the description, reference numeral 1 is a sputtering apparatus for carrying out the reactive sputtering method of the present invention. The sputtering apparatus 1 is an in-line type, and is provided with a vacuum holding means (not shown) such as a rotary pump or a turbo molecular pump to maintain a specific degree of vacuum. Plating chamber 11. The substrate transfer means 2 is provided in the upper space of the sputtering chamber 11. The substrate transporting means 2 is provided with a well-known structure, and includes a carrier 21 on which, for example, a processing substrate S is mounted, and the driving means is intermittently driven, whereby the processing substrate S can be sequentially transported to a target opposite to the target to be described later. The location.

At the sputtering chamber 11, a gas introduction means 3 is connected. The gas introduction means 3 is provided with a gas pipe 32 of the mass flow controller 31 interposed therebetween, and is connected to the gas source 33, and is capable of using a sputtering gas such as argon or a reaction gas used in reactive sputtering. It is introduced into the sputtering chamber 11 at a constant flow rate. As the reaction gas, it is suitably selected in accordance with the composition of the film to be formed on the surface of the substrate S, and a gas containing oxygen, nitrogen, carbon, hydrogen, ozone, water or hydrogen peroxide is used, or It is such a mixed gas or the like. On the lower side of the sputtering chamber 11, a magnetron sputtering electrode C is disposed.

The magnetron sputtering electrode C is provided with a target 41 which is provided in a substantially rectangular parallelepiped (rectangular in plan view) facing the sputtering chamber 11, and the target 41 is connected to the sputtering power source E. At the same time, it becomes a negative DC voltage that can be applied via the sputtering power source E. Here, the target 41 is produced by a known method in accordance with a composition of a film to be formed on the substrate S, such as Al, Mo, Ti, Cu, or ITO, by a known method. The area of 411 is set to be larger than the size of the processing substrate S. Further, the target 41 is joined to the backing plate 42 which is cooled by the target 41 during sputtering, and is joined by a bonding material such as indium or tin. In a state where the target 41 is bonded to the backing plate 42, the sputtering surface 411 and the processing substrate S are opposed to each other so as to be attached to the magnetron sputtering electrode C via the insulating plate 43. At frame 44. In the case where the target 41 is mounted, a mask 45 which is grounded to function as an anode is attached to the periphery of the target 41.

The magnetron sputtering electrode C is provided with a magnet assembly 5 behind the target 41. The magnet assembly 5 is provided with a support plate (yoke) 51 provided in parallel with the target 41. The support plate 51 is formed of a flat plate made of a magnetic material that amplifies the attraction force of the magnet. On the support plate 51, a central magnet 52 disposed in such a manner as to be positioned on a center line extending in the longitudinal direction of the support plate 51, and a periphery surrounding the central magnet 52, along the support plate 51 The peripheral magnet 53 which is arranged in a ring shape on the outer circumference is provided to change the polarity of the target side.

In the case where the central magnet 52 is converted into the same magnetized volume, the surrounding magnet 53 surrounded by the surrounding magnet is converted into the sum of the magnetized volumes (peripheral magnet: central magnet: peripheral magnet = 1:2: 1) The way to design. Thereby, in front of the sputtering surface 411 of the target 41, a tunnel-shaped magnetic flux M having a closed loop that is balanced with each other is formed. On the other hand, the electrons that are ionized on the side of the target 41 (sputter surface 411) and the secondary electrons generated by the sputtering are captured, and thus, will be in front of the target 41. The electron density is increased, which increases the plasma density and increases the sputtering rate.

Further, the horizontal width of the support plate 51 is dimensioned to be smaller than the width of the target 41 (refer to FIG. 1), and is provided at the back surface of the support plate 51 of the magnet assembly 5. A nut member 51a is provided. At the nut member 51a, a feed screw 61 is screwed, and at one end of the feed screw 61, a motor 62 is provided. Then, when the drive motor 62 rotates the feed screw 61, the magnet assembly 5 reciprocates along the back surface of the target 41 in a certain movement width D1 of the target 41 in the lateral direction. Thereby, the position where the magnetic flux density is high can be changed in the lateral direction of the target 41, and the sputtering surface 411 of the target 41 can be slightly eroded, and the utilization efficiency of the target 41 can be improved. . In this case, the movement width D1 of the magnet assembly 5 is preferably set so that the erosion region extends in the sputtering surface 411 of the target 41 to the end portion in the lateral direction.

Then, if the processing substrate S is transported to the position facing the target 41 via the substrate transfer means 2, the specific sputtering gas and the reaction gas are introduced through the gas introduction means 3, and then the sputtering power source is supplied. 5, when a negative DC voltage is applied, an electric field perpendicular to the processing substrate S and the target 41 is formed, and plasma is generated in front of the sputtering surface 411 of the target 41, so that the target 41 is sputtered, and On the surface of the substrate S, a film of a compound between the sputtered particles and the reaction gas thus formed is formed.

Here, in the sputtering apparatus 1 described above, since the mask 45 is provided around the target 41, when the plasma is generated in front of the sputtering surface 411, the electrons in the plasma or the second The secondary electrons flow toward the mask 45. As a result, at the peripheral region 421 of the sputtering surface 411 of the target 41, the plasma density is lowered, and the peripheral region 412 is not sputtered and remains as a non-erosion region (refer to Fig. 2 (a )).

For example, if a conductive target of aluminum is used as the target 41 and a reaction gas made of oxygen is introduced, and a film of an oxide is formed by reactive sputtering, the reverse deposition due to reactive sputtering At the peripheral region 412, the oxide system adheres and accumulates, and the peripheral region 412 is covered by the insulating film 1. If the film formation by sputtering is continued in this state, the electrons in the plasma or the secondary electrons are charged up at the peripheral region 412 covered by the insulating film 1. (Refer to Figure 2(b)). Therefore, it is necessary to set such that abnormal discharge caused by such charging is not induced.

In the present embodiment, the sputtering power source E is provided with a calculation means for calculating the integrated value of the electric power that has been input into the target 41, and the calculated integrated value is reached. When the specific value is passed, the introduction of the reaction gas to the sputtering chamber 11 is stopped by the mass flow controller 31, and a dummy substrate (not shown) is transferred to the target 41 via the substrate transfer means 2. At the opposite position, only the sputtering gas is introduced, and the target 41 is sputtered. In addition, the integration time to be set and the sputtering time of the target 41 in the state in which the reaction gas is introduced are appropriately set depending on the type of the target 41 to be used or the type of the reaction gas to be introduced.

Thereby, when the integrated value of the electric power input into the target 41 reaches a specific value, it is judged that the insulator is deposited at the peripheral region 412 of the target 41 due to the reverse deposition at the time of reactive sputtering. I. Then, when the target gas 41 is sputtered while the reaction gas is introduced, the conductive sputter particles from the target 41 collide with, for example, argon ions in the plasma. And attached to the peripheral region 412 of the target 41 for reverse stacking.

At this time, the charge charge on the surface of the insulating film I is neutralized by sputtering particles or ionized sputtering gas ions, or is made conductive by being constantly sputtered. The target sputtering surface 411 and the peripheral region 412 are again turned on, and flow to the target 412 side and disappear. On the other hand, the insulator I of the peripheral region 412 is covered by the conductive film F having the same composition as the target 41 (that is, the sputtered surface 411 of the target 41 includes the outer peripheral portion 412 thereof. The ground becomes the same potential). In addition, in order to shorten the time for the film formation to be interrupted and to improve the productivity, the sputtering power from the sputtering power source E is set to be more reactive gas introduction during the sputtering in the state where the introduction of the reaction gas is stopped. It is ideal when the input power is higher. In this case, when the target is aluminum, it is only necessary to increase the input electric power by about 10%.

When the insulator I is covered with the conductive film F, the substrate S is transferred to the position facing the target 41 via the substrate transfer means 2, and the mass flow controller 31 is activated to start the reaction gas again. The introduction is carried out, and the film formation of the substrate S is again initiated by reactive sputtering.

In this manner, in the present embodiment, since the input power to the target 41 from the sputtering power source E is not changed when the film of the one processing substrate S is formed, it is possible to The target 41 is sputtered while maintaining the optimum sputtering rate, and high productivity can be achieved. Further, since the peripheral region 412 of the target 41 is periodically covered by the conductive film having the same composition as the target 41, the induction of abnormal discharge due to charging is prevented, and the The target 41 is used satisfactorily and film formation is performed until the end of the life of the target 41. Further, in order to eliminate the influence on the insulating film 1 formed at the target 41 due to charging, no additional constituent parts are required, and there is no possibility of causing an increase in cost.

Further, in the above-described embodiment, it is preferable that the movement width D2 of the magnet assembly 5 when the reaction gas is stopped is set to be smaller than the movement width D1 when the reaction gas is introduced (film formation) (refer to FIG. 4). . In this case, the movement width D2 is appropriately set depending on the type of the target 41 to be used or the type of the reaction gas to be introduced. Thereby, the position at which the magnetic flux density is increased can be made to be toward the center side of the sputtering surface 411 of the target 41, whereby the film F which is reversely stacked at the peripheral portion 412 is extended to the same. At the center side, the peripheral region 412 can be surely covered by the conductive film F having the same composition as the target 41.

[Example 1]

In the first embodiment, as the target 41, an aluminum target which is formed into a rectangular shape in a plan view by a known method is used and joined to the shutter 42. Further, as the processing substrate S, a glass substrate is used, and as the sputtering condition, the mass flow controller 31 is controlled, and the flow rate of the argon gas which is a sputtering gas is set to 45 sccm, and oxygen as a reaction gas is used. The flow rate was set to 150 sccm, and the input power to the target 41 was set to 1.8 kW. Then, the processing substrate S is transferred to a position facing the target 41 via the substrate transfer means 2, and an Al ₂ O ₃ film is sequentially formed on the surface of the processing substrate S by reactive sputtering. In this case, the sputtering time of one of the processing substrates was set to 930 seconds. In the sputtering, the arc discharge generated per unit time (1 minute) by the sputtering power source E was counted. In this case, the occurrence of the arc discharge is detected by detecting the phenomenon that the discharge voltage is lower than the reference value.

At this time, if the integrated value (kWh) of the input power to the target reaches 20 kWh, the introduction of oxygen is temporarily stopped, and the flow rate of the argon gas is set to 45 sccm, and the input power to the target 41 is set to 2.0 kW. Sputtering is performed until the thickness of the deposited film reaches 50 nm, and the peripheral region 412 is covered by the film F.

(Comparative Example 1)

As Comparative Example 1, an Al ₂ O ₃ film was successively formed on the surface of the handle substrate S by reactive sputtering under the same conditions as described above.

According to the first comparative example, if the integrated value (kWh) of the input electric power to the target 41 exceeds 20 kWh, the occurrence of the plurality of arc discharges is confirmed every minute, and if it exceeds 22 kWh, the arc is generated. Most of the discharge systems occur, and film formation by reactive sputtering cannot be performed. On the other hand, according to the first embodiment, even if the integrated electric power of the target 41 reaches 35 kWh, the number of occurrences of arc discharge per minute is also 1 to 3 times, and reactive splashing can be performed. Good film formation due to plating.

1. . . Sputtering device

11. . . Sputtering room

2. . . Substrate transfer means

3. . . Gas introduction means

41. . . Target

5. . . Magnet assembly

E1. . . AC power

S. . . Processing substrate

E. . . Sputter power supply

F. . . Conductive film

I. . . Insulating film

Fig. 1 is a view schematically showing a sputtering apparatus of the present invention.

[Fig. 2] (a) and (b) are diagrams for explaining the state of the target at the time of reactive sputtering.

Fig. 3 is a view for explaining a state of a target after the implementation of the present invention.

Fig. 4 is a view for explaining movement of a magnet assembly.

41. . . Target

411. . . Sputtered surface

412. . . Peripheral area

F. . . Conductive film

I. . . Insulating film

Claims (4)

A sputtering method in which a sputtering gas and a reaction gas are introduced into a sputtering chamber, and electric power is input to a conductive target disposed in the sputtering chamber opposite to the processing substrate. a sputtering method in which a plasma atmosphere is formed in a sputtering chamber to perform sputtering on each target, and a specific thin film is formed on the surface of the processing substrate by reactive sputtering, which is characterized in that if it is input to the target When the integrated value of the electric power reaches a specific value, the introduction of the reaction gas is stopped, and a sputtering gas is introduced to sputter the target. A sputtering method is a method in which a processing substrate is sequentially transferred into a sputtering chamber, and a sputtering gas and a reaction gas are introduced into the sputtering chamber, and the conductive layer disposed opposite to the processing substrate is disposed. A sputtering method in which a target is charged with electric power, and a plasma atmosphere is formed in the sputtering chamber, and sputtering is performed on each target, and a specific thin film is formed on the surface of the processing substrate by reactive sputtering. When the integrated value of the electric power input to the target reaches a specific value, the dummy substrate is carried to a position facing the target, and the introduction of the reaction gas is stopped, and the sputtering gas is introduced and the target is introduced. The target is sputtered. The sputtering method according to the first or second aspect of the invention, wherein when the introduction of the reaction gas is stopped, the input power to the target is set to be higher than when the reaction gas is introduced. Splashes as described in item 1 or 2 of the patent application scope In the method, a magnet assembly provided to form a tunnel-shaped magnetic flux in front of the sputtering surface of the target is reciprocated in parallel along the back surface of the target, and the reaction gas introduction is stopped. At this time, the moving range of the magnet assembly is set to be smaller than when the reaction gas is introduced.