JP5875462B2 - Sputtering method - Google Patents

Description

  In the present invention, a substrate is disposed oppositely in a vacuum chamber where a target is installed, a sputtering gas is introduced into the vacuum chamber, a predetermined power is applied to the target, plasma is formed in the vacuum chamber, and the target is sputtered. The present invention also relates to a sputtering method for forming a predetermined thin film on a surface of a substrate facing a target.

  One of the methods for forming a predetermined thin film on the surface of a substrate to be processed such as glass is a sputtering (hereinafter referred to as “sputtering”) method. By trapping the electrons ionized in front of the sputtering surface of the target and the secondary electrons generated by sputtering with the tunnel-like magnetic flux from the magnet unit arranged on the back side), the electron density in the front is increased, The plasma density can be increased by increasing the collision probability between these electrons and the gas molecules of the sputtering gas composed of a rare gas introduced into the vacuum chamber. For this reason, there is an advantage that the film forming speed can be improved, and in recent years, it is often used for film forming on a substrate having a large area such as a glass substrate for FPD production.

  Here, as a sputtering apparatus for forming a film with a good film thickness distribution on a large-area substrate, a device in which a plurality of targets having the same shape are arranged in parallel at equal intervals in a vacuum chamber is known. In this case, since sputtered particles are not emitted from the region between the targets, when a predetermined thin film is formed on the surface of the substrate, the film thickness distribution of the thin film and the film quality distribution at the time of reactive sputtering are waved (for example, film thickness In the case of distribution, it tends to be non-uniform (as the thick and thin portions repeat at the same period). When there is such a wavy film thickness distribution or film quality distribution, for example, when an FPD is manufactured by forming a transparent electrode (ITO) on a glass substrate and enclosing liquid crystal, there is a problem that unevenness occurs on the display surface.

  Therefore, during sputtering, each target is moved back and forth integrally with a predetermined stroke in parallel with the substrate to change the region where the sputtered particles are not released, that is, the sputtered particles from the target over the entire surface of the substrate. It is known that the non-uniformity of the film thickness distribution and the film quality distribution is improved by facing the region from which the gas is released. In this case, in order to further improve the uniformity of the film thickness distribution and the film quality distribution, each magnet unit is also reciprocated relatively by a predetermined stroke in parallel with the substrate, thereby generating a tunnel-like magnetic flux that increases the sputter rate. The position is changed (see, for example, Patent Document 1). However, even in this conventional example, it has been found that the film thickness distribution and the film quality distribution which are slightly waved over the entire surface of the substrate cannot be sufficiently improved, in other words, the film thickness distribution and the film quality distribution which are slightly waved locally remain. Therefore, the present inventors have conducted extensive research and can effectively suppress the occurrence of undulating film thickness distribution and film quality distribution by synchronizing the reciprocation of the target (or substrate) and the reciprocation of the magnet unit. Obtained knowledge.

JP-A-2004-346388 (for example, refer to the description of the scope of claims)

  In view of the above points, the present invention, when sputtering to form a film, particularly when sputtering a film having a plurality of targets arranged in parallel at a predetermined interval, An object of the present invention is to provide a sputtering method capable of effectively suppressing the occurrence of film quality distribution.

In order to solve the above problems, a substrate is placed opposite to a vacuum chamber in which a target is installed, a sputtering gas is introduced into the vacuum chamber, power is applied to the target, and plasma is formed in the vacuum chamber to form the target. In a sputtering method in which sputtering is performed to form a film on a surface of a substrate facing the target, a plurality of magnet units are arranged at predetermined intervals in the X direction, which is one direction of the target, with the surface facing the target substrate facing up. In parallel with each other, each magnet unit forms a tunnel-like leakage magnetic field above the target, and during sputtering, each magnet unit is integrally reciprocated relative to the target with a predetermined stroke in the X direction, Each magnet unit reciprocates relative to the target with a predetermined stroke in the X direction. Causes relatively moving the substrate in the opposite direction, characterized in that the time until the respective magnet unit and the substrate to reach the return position from the starting point of reciprocation was equal.

  According to the present invention, each magnet unit and the substrate are moved relative to each other in the opposite direction, and each magnet unit and the substrate are equalized in time until the magnet unit and the substrate reach the folding position from the starting point of the reciprocating motion. As a result, it becomes opposed to the region where the sputtered particles are emitted from the target. As a result, the film thickness distribution and the film quality distribution that are slightly undulated locally do not remain, and the film thickness distribution and the film quality distribution are not uniform. It can be effectively suppressed.

  In the present invention, the target is formed by arranging a plurality of target materials having the same shape in parallel in the X direction at equal intervals, and provided with a magnet unit corresponding to each target material. It is preferable that the distance is equal to the sum of the stroke of the magnet unit and the stroke of the substrate. According to this, the region where the sputtered particles are emitted from the target is more evenly opposed over the entire surface of the substrate, and the nonuniformity of the film thickness distribution and film quality distribution can be more effectively suppressed. . In the present invention, the target having the same shape means that the target shape in plan view is the same, and the thickness of each target may be different from each other.

The schematic cross section explaining the structure of the sputtering device of this invention. Sectional drawing along the II-II line of FIG. (A)-(c) is a figure which shows typically the board | substrate W and magnet unit which move to the opposite direction. (A) is a graph showing the measurement result of the invention experiment, (b) is a graph showing the measurement result of the comparative experiment 1, and (c) is a graph showing the measurement result of the comparative experiment 2.

  Hereinafter, with reference to the drawings, a plurality of targets having the same shape are arranged in parallel in the sputtering chamber at a predetermined interval, and AC power is supplied to a pair of the arranged targets to form each target. Implementation of the present invention by sputtering and introducing oxygen gas into the sputtering chamber to form a metal film made of a target material or a metal oxide film by reactive sputtering on a substrate to be processed such as a glass substrate The sputtering apparatus SM of the form will be described.

  As shown in FIGS. 1 and 2, the magnetron type sputtering apparatus SM includes a vacuum chamber 1 that defines a sputtering chamber 1a. An exhaust port 11 is opened on the wall surface of the vacuum chamber 1, and an exhaust pipe 12 leading to a vacuum exhaust means P such as a rotary pump or a turbo molecular pump is connected to the exhaust port 11 to evacuate the sputtering chamber 1 a. Can be maintained at a predetermined degree of vacuum. A gas introducing means 2 is provided on the wall surface of the vacuum chamber 1. The gas introducing means 2 communicates with a gas source not shown through gas pipes 22a and 22b having mass flow controllers 21a and 21b interposed therebetween, and is used for sputtering gas composed of a rare gas such as argon or reactive gas used in reactive sputtering. Can be introduced at a constant flow rate. As the reactive gas, a gas containing oxygen, nitrogen, carbon, hydrogen, ozone, water, hydrogen peroxide, or a mixed gas thereof is used depending on the composition of the thin film to be formed on the substrate W. In the following, a target and a substrate W, which will be described later, face each other in the sputtering chamber 1a, the direction from the target to the substrate is “up”, the direction from the substrate W to the target is “down”, and the target and magnet unit are arranged in parallel A direction will be described as an X direction (left and right direction in FIG. 1), and a direction perpendicular to the X direction will be described as a Y direction.

A magnetron sputtering electrode C is disposed at the bottom of the sputtering chamber 1a. Magnet magnetron sputtering electrode C includes a four target 3 ₁ to 3 ₄ substantially provided so as to face the sputtering chamber 1a cuboid (rectangular plan view), provided respectively below each target 3 ₁ to 3 ₄ Units 4 ₁ to 4 ₄ are provided. The number of targets arranged in parallel is not limited to the above, and the target depends on the composition of the thin film to be formed on the substrate W, such as Si, Al and its alloys, Mo and ITO. What was produced by the well-known method can be used. Each target 3 ₁ to 3 ₄ has only to have the same shape in plan view, the thickness may be different respectively.

Each target 3 ₁ to 3 _4, in the film formation by sputtering is bonded to a copper backing plate 31 to cool the target 3 ₁ to 3 ₄ via a bonding material such as indium or tin. Then, joining the target ₃ 1 to 3 ₄ to the backing plate 31, it is provided in the sputtering chamber 1a via an insulator 32 of the vacuum seal combined in a state in which the target ₃ 1 to 3 ₄ to the upper side. In this case, the upper surface of the target 3 ₁ to 3 ₄ constitutes the sputtering surface 3a to be sputtered with ions of the sputtering gas will be described later at the time of film formation. Further, the targets 3 _{1 to} 3 ₄ are arranged at equal intervals in the Y direction in the sputtering chamber 1a and so that the unused sputtering surfaces 3a are located in the same plane parallel to the substrate W ( The shape of each target is designed so that the total area of the sputtered surfaces 3a arranged side by side is larger than the outer dimension of the substrate W.

After placement into the sputtering chamber 1a of the target ₃ 1 to 3 _4, around each of the target ₃ 1 to 3 _4, plate-shaped shield 5 provided with an opening 51 in which the target ₃ 1 to 3 ₄ faces are respectively disposed The Each shield 5 is made of, for example, aluminum. Further, two targets 3 ₁ and 3 _{2 and} 3 ₃ and 3 ₄ that are adjacent to each other among the targets 3 _{1 to} 3 _{4 that} are arranged in parallel are paired, and the targets 3 _{1 to} 3 ₄ that make a pair are exchanged with each other. Outputs Eo from the power source E are connected to each other. Then, at the time of film formation, a predetermined frequency from an AC power source E (e.g., 1Hz～100kHz) AC power are respectively put into the target ₃ 1 to 3 ₄ paired.

Magnet units 4 ₁ to 4 ₄ which are respectively disposed below (outside the sputtering chamber 1a) of the backing plate 31 have the same form, will be described one of the magnet unit 4 ₁ as an example, the magnet unit 4 _1, A support plate 41 (yoke) is provided that is provided in parallel to the backing plate 31 and is made of a flat plate made of a magnetic material that amplifies the attractive force of the magnet. On the support plate 41, a central magnet 42 disposed on the center line extending in the longitudinal direction of the support plate 41 and an annular shape along the outer periphery of the upper surface of the support plate 41 so as to surround the center magnet 42. And a peripheral magnet 43 arranged in the direction of the target is provided with the polarity on the target side changed. In this case, for example, the volume when the volume when converted to the same magnetization of the central magnet 42 is converted to the same magnetization of the peripheral magnet 43 surrounding the periphery (peripheral magnet: center magnet: peripheral magnet = 1: 2: 1 (see FIG. 1)). As a result, tunnel-like leakage magnetic fields M1 and M2 that are balanced above the targets 3 _{1 to} 3 ₄ are formed. The central magnet 42 and the peripheral magnet 43 are known ones such as a neodymium magnet. These central magnet and peripheral magnet may be integrated, or may be configured by arranging a plurality of magnet pieces having a predetermined volume. Also good.

The support plate 41 is formed so that its outer dimension is slightly smaller than the outline of the target, and the magnet units 4 ₁ to 4 ₄ are connected to the first moving means 6 via the support plates 41. The first moving means 6 includes a feed screw 61 that is screwed into a nut member 41 a that is suspended from the lower surface of each support plate 41, and a motor 62 that rotationally drives the feed screw 61 in the forward and reverse directions. When the feed screw 61 is rotationally driven, the magnet units 4 ₁ to 4 ₄ reciprocate at a predetermined speed and a constant stroke S1 on the same plane in the X direction according to the rotational direction. As shown in FIG. 1, the feed screw 61 is provided on the base plate 63 and is slidable on a pair of left and right rail members 64R and 64L extending horizontally over the entire length of the target 41 in the Y direction. It may be engaged and held by sliders 65R and 65L provided with a drive motor (not shown). When both sliders 65R and 65L are moved in the Y direction in synchronization, the magnet units 4 ₁ to 4 ₄ can be integrally reciprocated on the same plane in the Y direction at a predetermined speed and with a constant stroke. As a result, the magnet units 4 ₁ to 4 ₄ are moved relative to the targets 3 _{1 to} 3 ₄ positioned immediately above the magnet units 4 ₁ to ₄ 4 from a predetermined starting point and returned to the starting point. Is repeated.

Further, the upper portion of the vacuum chamber 1, a holder 7 for holding a substrate W so as to face is provided on the target 3 ₁ to 3 ₄ arranged side by side. The holder 7, the recess 71 is recessed to correspond to the contour of the substrate W is provided on the lower surface of the recess 71, central opening lower surface of the substrate W (film forming surface) faces the target 3 ₁ to 3 ₄ 72 is formed. The holder 7 is connected to the second moving means 8. The second moving means 8 is screwed into a nut member 73 provided on the lower surface of the holder 7, and a feed screw 81 provided through the side wall of the vacuum chamber 1, and the feed screw 81 is driven to rotate in forward and reverse directions. And a motor 82. When the feed screw 81 is rotationally driven, the holder 7 and, consequently, the substrate W reciprocate on the same plane in the X direction at a predetermined speed and a constant stroke S2 in accordance with the rotational direction. In this case, the center-to-center distance (also referred to as “cathode pitch”) Dt of the adjacent targets 3 _{1 to} 3 ₄ is equal to the sum of the stroke S _{1 of} each magnet unit 4 ₁ to 4 _{4 and} the stroke S 2 of the substrate W. .

Next, film formation by sputtering using the sputtering apparatus SM will be described with reference to FIG. First, after setting the substrate W in the holder 7, the inside of the sputtering chamber 1a is evacuated to a predetermined pressure. At this time, as shown in FIGS. 1 and 3A, the holder 7 is at the starting position of the right end of the reciprocating motion, and each of the magnet units 4 ₁ to 4 ₄ is at the starting position of the left end of the reciprocating motion. . Then, a predetermined sputtering gas and a reactive gas are introduced through the gas introduction means 2, and AC power is supplied to each of the targets 3 _{1 to} 3 ₄ that form a pair through the AC power source E. Thus, two targets 3 ₁ and 3 ₂ and 3 ₃ and 3 ₄ in a pair serve the respective anode and cathode, above the respective target 3 ₁ to 3 _4, a tunnel-shaped leakage magnetic field is formed As a result, high-density plasma is generated in a racetrack shape passing through a position where the vertical component of the leakage magnetic field becomes zero. In the start position shown in FIG. 3 (a), since the leakage magnetic field above the target 3 ₁ to 3 ₄ left portion is formed, the left portion of the target 3 ₁ to 3 ₄ are respectively sputter. Then, sputtering particles emitted from the target 3 ₁ to 3 _4, collected and deposited on the opposite surface of the substrate W.

During sputtering, the magnet units 4 ₁ to 4 ₄ are moved from the starting position at the left end toward the folding position at the right end by the first moving means 6, and on the other hand, the holder 7 and eventually the substrate by the second moving means 8. W is moved from the starting position at the right end toward the folding position at the left end. As shown in FIG. 3B, when the substrate W is at an intermediate position between the left end and the right end, each of the magnet units 4 ₁ to 4 ₄ is also at an intermediate position between the right end and the left end. As described above, when both the substrate W and each of the magnet units 4 ₁ to 4 ₄ are in the intermediate position, a leakage magnetic field is formed above the center portion of each of the targets 3 _{1 to} 3 _4, so that the centers of the targets 3 _{1 to} 3 ₄ are formed. A portion is sputtered, and sputtered particles emitted from the central portion adhere to the surface of the opposing substrate W. And there when the substrate W as shown in FIG. 3 (c) is in the folded position of the reciprocating path (left end position), also the return position of the reciprocating each magnet unit ₄₁ to ₄ (right end position). At this time, since a leakage magnetic field is formed above the right side portion of each target 3 _{1 to} 3 _{4, the} right side portion of the target 3 _{1 to} 3 ₄ is sputtered, and the sputtered particles emitted from this right side portion are opposed to the opposing substrate W. Adhere to the surface.

Thereafter, each of the magnet units 4 ₁ to 4 ₄ is moved from the rightmost folded position toward the leftmost starting position, while the substrate W is moved from the leftmost folded position to the rightmost starting position.

In this way, the magnet units 4 ₁ to 4 ₄ and the substrate W are moved in opposite directions, and at this time, the moving speed is set so as to equalize the time from the starting point of the reciprocating movement to the return position. . Then, while repeating this operation, sputtered particles from the targets 3 _{1 to} 3 ₄ adhere and deposit on the surface of the substrate W (while reacting with the reaction gas) to form a predetermined thin film.

According to the above, the magnet units 4 ₁ to 4 ₄ and the substrate W are moved in opposite directions, and the time required to reach the return position from the starting point of the reciprocating motion is equalized. 3 _{1 to} 3 ₄ are evenly opposed to the region from which sputtered particles are emitted (that is, plasma is irradiated over the entire surface of the substrate W), and as a result, the surface is slightly undulated. The film thickness distribution and the film quality distribution do not remain, and the nonuniformity of the film thickness distribution and the film quality distribution can be effectively suppressed.

Further, the target center distance Dt as described above, by the equivalent sum of the stroke S2 of the stroke S1 and the substrate W of the magnet unit, area where sputtering particles are emitted from the target 3 ₁ to 3 _4, It becomes more evenly opposed over the entire surface of the substrate W, and non-uniformity in film thickness distribution and film quality distribution can be more effectively suppressed.

In order to confirm the above effects, the following experiment was performed using the sputtering apparatus SM shown in FIG. In this experiment, we used as ITO made of the target 3 ₁ to 3 _4, formed into a substantially rectangular same plan view, and bonded to the backing plate 31. Further, as the support plate 41 of the magnet unit ₄₁ to _4, with those having outer dimensions of 130 mm × 1300 mm, on each support plate 41, rod-shaped central magnet along the longitudinal direction of the target ₃ 1 to 3 ₄ 42 and peripheral magnets 43 are provided along the outer periphery of the support plate 41.

Then, a glass substrate for so-called 8.5th generation flat panel display is used as the substrate W, and as a sputtering condition, the pressure in the sputtering chamber 1a evacuated is maintained at 0.3 Pa. The mass flow controllers 21a and 21b are controlled to introduce sputtering gas argon and water vapor gas into the sputtering chamber 1a, and by applying 15 kW of input power (alternating voltage) to the targets 3 _{1 to} 3 ₄ , sputtering is performed. went. The distance between the substrate W and the targets 3 _{1 to} 3 ₄ was 216 mm.

In the invention experiment, during the above sputtering, the magnet units 4 ₁ to 4 ₄ and the holder 7 and eventually the substrate W were moved in opposite directions, and the time from the reciprocation starting point to the return position was made equal. In this case, the sum of the distance between the centers Dt of adjacent target _{3 1 ~3 4 (= 250mm)} , the stroke S1 of the magnet units ₄ 1 _{~4 4} (= 84mm) and the substrate W stroke S2 and (= 166 mm) was equal, the moving speed of the magnet unit ₄₁ to ₄ and 14.8 mm / sec, the moving speed of the holder 7 (substrate W) was 47.88mm / sec. With respect to the ITO thin film formed in the inventive experiment, the reflectance with respect to light in the wavelength region of 300 to 800 nm was measured, and the measurement result is shown in FIG. The measurement locations were locations of 0 mm, 100 mm, 200 mm, 300 mm, and 400 mm when the end of the left side of the substrate W (starting side of the reciprocating motion) was set to zero. The in-plane uniformity of the measured reflectance was 0.61%, and it was confirmed that the occurrence of undulating film thickness distribution and film quality distribution can be effectively suppressed.

In comparative experiment 1 with respect to the above-described invention experiment, the substrate W was fixed without moving during the sputtering, and the magnet units 4 ₁ to 4 ₄ were reciprocated at a speed of 14.8 mm / sec. Similar to the above-described invention experiment, the measurement result of the reflectance of the ITO thin film formed in this comparative experiment 1 is shown in FIG. The in-plane uniformity of reflectance was as low as 1.12%, and it was confirmed that the film thickness distribution and film quality distribution were non-uniform.

In another comparative experiment 2, both the substrate W and the magnet units 4 ₁ to 4 ₄ were moved during the sputtering, but the substrate W and the magnet units 4 ₁ to 4 ₄ were not synchronized. That is, both were moved not only in the opposite direction but also in the same direction. Similar to the above-described invention experiment, the measurement result of the reflectance of the ITO thin film obtained in this comparative experiment 2 is shown in FIG. The in-plane uniformity of the reflectance is 0.74%, and it is found that the in-plane uniformity is lower than that of the invention experiment, although the in-plane uniformity is improved as compared with the comparative experiment 1. Also in this case, a undulating film thickness distribution and film quality distribution are generated.

  The magnetron type sputtering apparatus SM according to the embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment. In the above embodiment, the case where the holder 7 is provided in the vacuum chamber 1 and the substrate W is reciprocated has been described as an example. However, for example, the sputtering apparatus SM is configured as an inline type and faces the target of the vacuum chamber. In the case where the substrate is transported using a carrier at a position, the carrier may be reciprocated during sputtering.

In the above embodiment, a plurality of targets are arranged in parallel, and AC power is supplied to a pair of targets by an AC power source. However, the present invention is not limited to this, and one target is used. The present invention can also be applied to the case of comprising. When there is one target, there is no gap between the targets as in the above embodiment. For this reason, as shown in FIG. 3A, it is not necessary to provide a region Dm in which the magnet units 4 ₁ to 4 ₄ are not moved in order to prevent the abnormal discharge due to the backing plate 31 being sputtered. When the region Dm exists for some reason, the present invention can be preferably applied.

  The present invention can also be applied to the case where DC power is input from a DC power source. The present invention can also be applied to a circular target in which the magnet unit rotates about the center of the target.

SM ... Sputtering apparatus, 1a ... Sputtering chamber, 31-34 ... Target, 41-44 ... Magnet unit, 5 ... Floating shield, 6 ... Moving means, E ... AC power supply, M1, M2 ... Leakage magnetic field, W ... Substrate.

Claims (2)

The substrate is placed opposite to the vacuum chamber in which the target is installed, sputtering gas is introduced into the vacuum chamber, power is applied to the target, plasma is formed in the vacuum chamber, and the target is sputtered. In the sputtering method of forming a film on the opposite surface,
A plurality of magnet units are arranged in parallel at a predetermined interval in the X direction, which is one direction of the target, with the surface facing the target substrate facing upward, and a tunnel-like leakage magnetic field is formed above the target by each magnet unit. Form the
During sputtering, each magnet unit is integrally reciprocated relative to the target with a predetermined stroke in the X direction, and the substrate is reciprocated relative to the target with a predetermined stroke in the X direction.
A sputtering method, wherein each magnet unit and the substrate are relatively moved in opposite directions, and the time required for each magnet unit and the substrate to reach the turn-back position from the starting point of the reciprocating motion is equalized. 2. The sputtering method according to claim 1, wherein the target is formed by arranging a plurality of target materials having the same shape in parallel in the X direction at equal intervals, and a magnet unit is provided corresponding to each target material. In
A sputtering method, wherein a distance between centers of adjacent targets is made equal to a sum of a stroke of a magnet unit and a stroke of a substrate.

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