KR101113123B1 - Method of sputtering - Google Patents

Abstract

The present invention provides a reactive sputtering method capable of forming a thin film while maintaining a high sputter rate without being affected by an insulating film formed in a peripheral region of the target. In the above method, while introducing the reaction gas into the sputter chamber 11, electric power is supplied to the conductive target 41 disposed to face the processing substrate S in the sputter chamber, and a plasma atmosphere is formed in each of the sputter chambers. A sputtering method for sputtering a target and forming a predetermined thin film on the surface of the processing substrate by reactive sputtering, wherein the integrated input power is monitored by a sputtering power source E that supplies power to the target, and the integrated value is a predetermined value. When the reaction gas is reached, the introduction of the reaction gas is stopped, and only the sputter gas is introduced to sputter the target for a predetermined time.

Description

Sputtering method {METHOD OF SPUTTERING}

TECHNICAL FIELD The present invention relates to a sputtering method for forming a predetermined thin film on a surface of a processing substrate, and more particularly, to a sputtering method for forming a thin film by reactive sputtering while introducing a reactive gas using a conductive target as a target.

Sputtering (hereinafter referred to as sputtering) is one of the methods for forming a predetermined thin film on the surface of a processing substrate such as glass or a silicon wafer. This sputtering method accelerates and bombards ions in a plasma atmosphere toward a target formed into a predetermined shape depending on the composition of a thin film deposited on the surface of the processing substrate, scatters sputter particles (target atoms), and adheres and deposits on the surface of the processing substrate. By forming a predetermined thin film. In the case of this sputter | spatter, predetermined | prescribed reaction gas, such as oxygen and nitrogen, is introduce | transduced with the sputter gas comprised from a rare gas, and a reactive sputter forms a thin film which consists of a compound of a sputter particle and a reactive gas.

Here, in the sputtering apparatus which implements the said sputtering method, the shield which generally fulfills the role as an anode grounded around a target is arrange | positioned. In this way, when a shield is placed around the target, and a direct current voltage is applied to the target to generate plasma in the direction of the sputter surface of the target, electrons or secondary electrons in the plasma are directed toward the shield. Flow. As a result, the plasma density of the peripheral area of the sputtering surface of the target becomes low, and this peripheral area is not sputtered and remains as a non-eroded area.

Concerning the case where the peripheral region of the sputter surface remains as a non-erosion region, in particular, when a reactive gas such as oxygen is introduced using a conductive target such as aluminum as a target, and a thin film of oxide is formed by the reactive sputtering, the inverse of the reactive sputtering By deposition, an oxide adheres to and surrounds the surrounding area. In other words, the peripheral region of the sputter surface is covered with an insulating film. In such a state, there is a problem in that electrons or secondary electrons in the plasma are charged up in the peripheral region, and abnormal charges are caused due to this charge up, thereby preventing satisfactory thin film formation.

Thereby, a sputtering method is known in Patent Document 1 in which, when a negative DC voltage is applied to a target to sputter the target, the applied voltage is changed to a positive potential at a constant pulse period.

In the sputtering method described in Patent Document 1, the charge-up charge remaining in the peripheral region of the target in the sputter is erased when a positive voltage is applied. For this reason, even if the peripheral area | region of a target is covered with the insulating film, generation | occurrence | production of the abnormal discharge (arc discharge) resulting from charge up is suppressed. However, there is a problem that the sputter rate is lowered because the plasma disappears once each time a positive voltage is applied to the target. For this reason, the thin film formation time on a single process board | substrate becomes long, and productivity is bad. In addition, a sputter power supply for applying a voltage whose polarity changes in a constant pulse period is required, resulting in high cost.

Patent Document 1: Japanese Patent Application Publication No. Hei 10-237640

In view of the above, it is an object of the present invention to provide a sputtering method capable of forming a thin film without maintaining the high sputtering rate without being affected by the insulating film formed in the peripheral region of the target, and incurring no cost. .

In order to solve the said subject, the sputtering method of Claim 1 introduce | transduces a reactive gas into a sputter chamber, inputs electric power to the electroconductive target arrange | positioned facing the process board | substrate in this sputter chamber, and creates a plasma atmosphere in a sputter chamber. A sputtering method of forming and sputtering each target and forming a thin film on the surface of the electroprocessing substrate by reactive sputtering. When the integrated value of the electric power input to the target reaches a predetermined value, the introduction of the electric reaction gas is stopped and the target is stopped. It is characterized by sputtering.

According to the present invention, when the integrated value of the electric power input to the target reaches a predetermined value, it is determined that the insulator has accumulated in the peripheral region of the sputter surface of the target by reverse deposition during reactive sputtering, and the introduction of the reactive gas is stopped, that is, The thin film formation on the processing substrate is once stopped. Then, only the sputter gas made up of the rare gas is introduced to sputter the target. In this state, conductive sputtered particles from the target collide with, for example, electrons in the plasma, and adhere to the peripheral region of the target to reversely deposit.

At this time, the charge-up charge on the insulating film is neutralized or sputtered by sputter particles or ionized sputter gas ions, and the sputter surface and the peripheral region of the conductive target are conducted again, and flow to and disappear from the target side. When the insulator in the peripheral region is covered with the conductive thin film again, the introduction of the reaction gas is resumed, and the thin film formation on the processing substrate is resumed.

As described above, in the present invention, since the input power is not changed at the time of forming a thin film on one sheet of processing substrate, the target can be sputtered while maintaining the optimum sputtering rate, and high productivity can be achieved. In addition, since the peripheral region of the target is periodically covered by a conductive film having the same composition as that of the target, the occurrence of abnormal discharge due to the charge-up is prevented, and the thin film can be formed using the target with a good lifetime of the target. In addition, in order to eliminate the influence of the charge-up on the insulating film formed as the target, no separate component is required and no high cost is incurred.

In addition, the sputtering method according to claim 2 transfers a processing substrate into the sputtering chamber in order, introduces a reaction gas into the sputtering chamber, and supplies electric power to an electrically conductive target disposed to face the processing substrate, thereby plasma is introduced into the sputtering chamber. A sputtering method in which an atmosphere is formed to sputter each target and a 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 predetermined value, the dummy substrate is positioned at a position facing the target. It conveys, and stops introduction of the said reaction gas, It is characterized by sputtering a target.

In the present invention, if the input power to the target at the time of stopping the reaction gas introduction is set higher than that at the reaction gas introduction, the time for stopping the thin film formation is shortened and the productivity can be increased.

In addition, the magnet assembly provided to form a tunnel-shaped magnetic flux in the front direction of the sputter face of the target is reciprocated in parallel along the back surface of the target, and the movement width of the magnet assembly is introduced when the reaction gas is stopped. If it is set smaller than that of the sample, the conductive thin film which causes the magnetic flux density to reach the center of the sputter face of the target close to the surrounding area is increased to the center side, and as a result, the surrounding area of the target is separated from the target. It can be reliably covered by a thin film of the same composition.

As described above, the sputtering method of the present invention is capable of forming a thin film while maintaining a high sputtering rate without being affected by the insulating film formed in the peripheral region of the target, thereby having no effect of causing high cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the sputtering apparatus of this invention.
(A) and (b) is a figure explaining the target state at the time of implementing reactive sputtering.
3 is a diagram illustrating a target state after implementing the present invention.
4 is a diagram illustrating the movement of the magnet assembly.

Referring to FIG. 1, 1 is a sputtering apparatus for implementing the reactive sputtering method of the present invention. The sputter apparatus 1 is an in-line system and has the sputter chamber 11 which can be maintained at predetermined | prescribed vacuum degree through vacuum exhaust means (not shown), such as a rotary pump and a turbo molecular pump. The substrate conveying means 2 is provided in the upper space of the sputter chamber 11. The board | substrate conveying means 2 has a well-known structure, for example, is equipped with the carrier 21 with which the process board | substrate S is mounted, drives a drive means intermittently, and is a process board | substrate in the position which opposes the target mentioned later. (S) can be returned in order.

The gas pressurizing means 3 is connected to the sputter chamber 11. The gas introduction means 3 is connected to the gas source 33 through the gas pipe 32 in which the mass flow controller 31 was opened, and the sputter chamber 11 uses sputter gas, such as argon, and the reactive gas used at the reactive sputter | spatter. Can be introduced at a constant flow rate. As the reaction gas, appropriately selected depending on the composition of the thin film to be deposited on the surface of the processing substrate S, oxygen, nitrogen, carbon, hydrogen containing gas, ozone, water or hydrogen peroxide or such a mixed gas is used. A magnetron sputter electrode C is disposed below the sputter chamber 11.

The magnetron sputter electrode C has a target 41 of a substantially rectangular parallelepiped (rectangular when viewed from the surface) provided to face the sputter chamber 11, and the target 41 is connected to the sputter power source E to supply the sputter power source. Through (E), a negative DC voltage can be applied. Here, the target 41 is produced by a known method in accordance with the composition of the thin film to be deposited on the processing substrate S, such as Al, Mo, Ti, Cu or ITO, so that the area of the sputter surface 411 is reduced to the processing substrate S. ) Is set larger than the external dimension. The target 41 is also joined to the backing plate 42 which cools the target 41 during sputtering through a bonding material such as indium or tin. Attached to the frame 44 of the magnetron sputter electrode C via the insulating plate 43 so that the sputter surface 411 faces the processing substrate S while the target 41 is bonded to the backing plate 42. do. When the target 41 is mounted, a shield 45 that serves as a grounded anode is provided around the target 41.

The magnetron sputter electrode C has a magnet assembly 5 behind the target 41. The magnet assembly 5 has a support plate (yoke) 51 provided in parallel with the target 41, and this support plate 51 is constructed from a magnetic plate made of magnetic material which amplifies the attraction force of the magnet. On the support plate 51, an annular shape is formed along the outer periphery of the support plate 51 so as to surround the center magnet 52 and the center magnet 52 which are positioned and disposed on a center line extending in the longitudinal direction of the support plate 51. Peripheral magnets 53 are arranged so as to change the polarity of the target side.

The sum of the volumes obtained when converting the volume converted from the central magnet 52 and the magnetization into the same magnetization of the peripheral magnet 53 surrounding the periphery (peripheral magnet: center magnet: peripheral magnet = 1 2: 1 (see Fig. 1)). As a result, in the front of the sputtering surface 411 of the target 41, a balanced closed loop tunnel-shaped magnetic flux M is formed, respectively. Then, by capturing electrons ionized on the front side of the target 41 (sputter surface 411) and secondary electrons generated by sputtering, the electron density in front of the target 41 is increased to increase the plasma density, and the sputter rate is increased. Can be made higher.

In addition, the width of the support plate 51 is sized to be smaller than the width of the target 41 (see FIG. 1), and a nut member 51a is provided on the rear surface of the support plate 51 of the magnet assembly 5. have. A feed screw 61 is screwed into this nut member 51a, and a motor 62 is attached to one end of the feed screw 61. Then, when the feed screw 61 is rotated by driving the motor 62, the magnet assembly 5 reciprocates along the back surface of the target 41 at a constant moving width D1 in the transverse direction of the target 41. . As a result, by changing the position of the high magnetic flux density in the lateral direction of the target 41, the sputtering surface 411 of the target 41 can be eroded substantially evenly, thereby increasing the utilization efficiency of the target 41. have. In this case, the moving width D1 of the magnet assembly 5 is appropriately set so that the erosion region extends to the transverse end portion in the sputter surface 411 of the target 41.

Then, the substrate conveying means 2 conveys the processing substrate S to the position facing the target 41, introduces a predetermined sputter gas and a reactive gas through the gas introducing means 3, and sputter power source ( When a negative DC voltage is applied through 5), an electric field perpendicular to the processing substrate S and the target 41 is formed, and a plasma is generated in front of the sputtering surface 411 of the target 41 so that the target 41 A thin film made of a sputtered sputtered sputtered particle and a reactant gas is formed on the surface of the processing substrate S.

Here, in the sputtering apparatus 1, since the shield 45 is arrange | positioned around the target 41, when the plasma generate | occur | produces in front of the sputter surface 411, the electron in a plasma and secondary electrons are shielded 45 Flows toward). As a result, the plasma density in the upper part of the peripheral area 412 of the sputtering surface 411 of the target 41 becomes low, and this peripheral area 412 is not sputtered and remains as a non-erosion area | region (refer FIG. 2 (a)). ).

For example, when a reactive gas made of oxygen is introduced using a conductive target of aluminum as a target 41 to form a thin film of oxide rather than a reactive sputter, the oxide is formed in the peripheral region 412 due to reverse deposition at the time of reactive sputtering. It adheres and deposits, and the peripheral area 412 is covered with the insulating film I. When the thin film formation by sputtering is continued in this state, electrons and secondary electrons in the plasma are charged up in the peripheral region 412 covered with the insulating film I (see FIG. 2 (b)). Therefore, it is necessary to prevent abnormal discharge from occurring due to such charge up.

In the present embodiment, the sputtering power source E is provided with calculating means for calculating an integrated value of the electric power input to the target 41, and when the calculated integrated value reaches a predetermined value, a mass flow controller (mass flow controller) ( The introduction of the reactive gas into the sputter chamber 11 through 31 is stopped, and the dummy substrate (not shown) is conveyed to the position opposed to the target 41 by the substrate transfer means 2, thereby sputtering gas. Only the target 41 is introduced to sputter the target 41. Subsequently, the integration time to be set and the sputtering time of the target 41 in the reactive gas introduction stop state are appropriately set depending on the target 41 to be used and the kind of reactive gas to be introduced.

As a result, when the integrated value of the electric power input to the target 41 reaches a predetermined value, it is determined that the insulator I has accumulated in the peripheral region 412 of the target 41 due to the reverse deposition during the reactive sputtering. Then, when the conductive target 41 is sputtered in the reaction gas introduction stop state, the conductive sputter particles from the target 41 collide with, for example, argon ions in the plasma, and thus the peripheral region 412 of the target 41. ) And back deposit.

At this time, the charge-up charge on the surface of the insulating film I is neutralized or sputtered by sputter particles or ionized sputter gas ions, and the peripheral region 412 conducts again to the conductive sputter surface 411 so that the target 412 becomes conductive. ) Flows to the side and disappears. The insulator I of the peripheral region 412 is covered with the conductive thin film F having the same composition as the target 41 (that is, the sputter surface 411 of the target 41 is surrounded by the other peripheral portion 412). Becomes a coin containing). Moreover, in order to shorten the time which thin film formation is interrupted and to raise productivity, it is preferable to set the input electric power from the sputter | spatter power supply E higher than at the time of introduction of reaction gas at the time of the sputter | spatter in the stop state of introduction of reaction gas. In this case, when the target is aluminum, the input power may be increased by about 10%.

When the insulator I is covered with the conductive thin film F, the substrate conveying means 2 conveys the processing substrate S to a position facing the target 41, and operates the mass flow controller 31. Introduction of the reaction gas is resumed, and thin film formation on the processing substrate S is resumed by reactive sputtering.

Thus, in this embodiment, since the input power from the sputter power supply E to the target 41 is not changed at the time of forming the thin film on the one process board | substrate S, it is a target with maintaining the optimum sputter rate. (41) can be sputtered and high productivity can be achieved. In addition, since the peripheral region 412 of the target 41 is regularly covered with a conductive film of the same composition as the target 41, the occurrence of abnormal discharge due to the charge up is prevented and the life of the target 41 is good. The target 41 can be used to form a thin film. In addition, in order to eliminate the influence of the charge-up on the insulating film I formed on the target 41, no separate component is required, and high cost is not required.

In addition, about the said embodiment, it is preferable to set the moving width D2 of the magnet assembly 5 at the time of reaction gas stop smaller than D1 at the time of reaction gas introduction (thin film formation) (FIG. 4). Reference). In this case, the moving width D2 is appropriately set depending on the target 41 to be used and the kind of reaction gas to be introduced. As a result, the position where the magnetic flux density increases is approaching the center side of the sputtering surface 411 of the target 41, so that the thin film F which reversely deposits the peripheral region 412 is extended to the center side thereof and the peripheral region 412 Can be reliably covered by the conductive film F having the same composition as the target 41.

Example 1

In the present Example 1, it bonded to the backing plate 42 using the aluminum product formed in substantially rectangular shape as the target 41 by the well-known method. In addition, using the glass substrate as the processing substrate S, the mass flow controller 31 is controlled as the sputtering condition to set the flow rate of the argon gas as the sputter gas to 45 sccm and the flow rate of the oxygen gas as the reaction gas to 150 sccm The power input to the target 41 was set at 1.8 kW. And, by transferring the processed substrate (S) at a position opposed to the target 41 by the substrate transfer means (2), and successively forming Al ₂ O ₃ film on the surface of substrate (S) by means of reactive sputtering. In this case, the sputtering time of one sheet of the processing substrate was 930 seconds. The arc discharge which generate | occur | produces in unit time (1 minute) by the sputter | spatter power supply E was counted among sputter | spatters. In this case, generation | occurrence | production of arc discharge was detected by detecting the phenomenon which discharge voltage falls below a reference value.

At that time, when the integrated value (kWh) of the input power to the target reaches 20 kWh, the introduction of oxygen gas is once stopped, and the flow rate of argon gas is 45 sccm and the input power to the target 41 is 2.0 kW. It was set and sputtered until the thickness of the film | membrane to deposit reaches 50 nm, and the peripheral area | region 412 was supposed to be covered by the thin film (F).

(Comparative Example 1)

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

According to the comparative example 1, when the integrated value (kWh) of the input electric power to the target 41 exceeds 20 kWh, occurrence of several times of arc discharge is confirmed every 1 minute, and when it exceeds 22 kWh, an arc discharge will generate | occur | produce a reactive sputter | spatter. It became impossible to form a thin film by. In contrast, according to Example 1, even if the integrated power of the target 41 reached 35 kWh, the number of occurrences of arc discharge in one minute was 1 to 3 times, and favorable thin film formation by reactive sputtering was possible. .

1 sputtering device
11 sputter rooms
2 board conveying means
3 gas introduction means
41 targets
5 magnet assembly
E1 AC Power
S processed substrate
E sputter power
F conductive thin film
I insulating film

Claims (4)

While introducing the reaction gas into the sputter chamber, electric power is supplied to the conductive target disposed opposite to the processing substrate in the sputter chamber, a plasma atmosphere is formed in the sputter chamber to sputter each target, and the treatment is performed by reactive sputtering. In the sputtering method of forming a thin film on the substrate surface,
The sputtering method characterized by stopping the introduction of the said reaction gas and sputter | spatting the target, when the integrated value of the electric power supplied to the thinning target reaches a predetermined value. While conveying the processing substrate into the sputter chamber in turn and introducing the reaction gas into the sputter chamber, electric power is supplied to the conductive target disposed to face the processing substrate, and a plasma atmosphere is formed in the sputter chamber to provide each target. In the sputtering method of forming a thin film on the said process board | substrate surface by sputtering by reactive sputtering,
And when the integrated value of the electric power supplied to the target reaches a predetermined value, the dummy substrate is transferred to a position facing the target, the introduction of the reaction gas is stopped, and the target is sputtered. The method according to claim 1 or 2,
The sputtering method characterized by setting the electric power supplied to the said target at the time of stop of the said reaction gas introduction to be higher than the electric power supplied at the time of introduction of reaction gas. The method according to claim 1 or 2,
The magnet assembly provided to form a tunnel-shaped magnetic flux in the forward direction of the sputter surface of the target is reciprocated in parallel along the back surface of the target, and when the introduction of the reaction gas is stopped, the moving width of the magnet assembly is introduced into the reaction gas. A sputtering method, characterized by setting smaller than the movement width of time.

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