JPH0718005B2 - Sputtering device - Google Patents

Description

The present invention relates to a sputtering apparatus, and more particularly to a sputtering apparatus suitable for forming a uniform film on a plurality of substrates.

[Conventional technology]

A conventional sputtering apparatus for forming a film on a plurality of substrates is disclosed in
As shown in No. 56-130147, a film is formed on a substrate as a center and a substrate arranged concentrically around the substrate, and the target is also circular. In this case, no consideration was given to the fact that the film thickness and the like slightly differ between the central substrate and the concentrically arranged substrates. A rectangular target is shown in FIG. 2 of Japanese Patent Laid-Open No. 189372/1983, but there is no drawing regarding the substrate arrangement. Further, in these conventional examples, the shape of the erosion area, which has an important influence on the film thickness distribution and the step coverage, has not been known and therefore not mentioned.

[Problems to be solved by the invention]

Regarding the above-mentioned conventional technique, regarding the formation of a uniform film on a plurality of substrates, no knowledge has been obtained about the size of the target erosion area and the film formation characteristics, and there is a problem that it is difficult to form a uniform film. there were.

An object of the present invention is to form a uniform film on a plurality of substrates.

[Means for solving problems]

As a result of various studies to achieve the above object, the inventors of the present invention changed the width of the erosion area to obtain a film thickness distribution of the sputtered film formed on a plurality of substrates (the film thickness in the substrate surface). Determined by the minimum and maximum values, the smaller the film thickness distribution,
It shows that the film thickness is uniform. ) Changes, and the step coverage (ratio of the thickness of the slope portion to the thickness of the flat portion (see FIG. 4)) also changes with the erosion area width, and the present invention was completed based on this new finding. It was done. Specifically, the above object is achieved by defining the width and length of the erosion area to be a certain range determined by the relationship with the substrate diameter in a structure having a rectangular target and a rectangular erosion area.

That is, the sputtering apparatus of the present invention includes (1) a substrate holder capable of holding a plurality of substrates in a vacuum container capable of maintaining airtightness, a target facing the substrate holder, and a pair of magnetrons arranged on the back surface of the target. A sputtering apparatus that includes a magnet, supplies electric power to the target, causes plasma discharge in the supply of sputtering gas, and forms thin films on a plurality of substrates held on the substrate by sputtered particles from the target. The erosion area defined by the center line between the pair of magnetron magnets has a shape defined by a short side and a long side, and the width a (mm) that is the short side is the diameter of the substrate. When (or the long side of the rectangular substrate) is expressed in d (mm) and α (inch), 2d (α / 3) ^1/4 −40 ≦ a ≦ 2d (α / 3) ^1/4 +40 (mm) When And (2) a substrate holder capable of holding a plurality of substrates in a vacuum container capable of maintaining airtightness, a target facing the substrate holder, and a pair arranged on the back surface of the target. Magnetron magnet is supplied, electric power is supplied to the target to generate plasma discharge in the supply of sputter gas, and thin films are formed on a plurality of substrates held on the substrate by sputter particles from the target. In the sputtering apparatus, the erosion area defined by the center line between the pair of magnetron magnets has a shape defined by a short side and a long side, and the length b, which is the long side of the erosion area, is the number of substrates. Where n is and the diameter or the long side of the substrate is d (mm), b ≧ nd + (n−1) · 15 + 50 (mm) It includes two inventions, each characterized by having an area length b.

[Action]

As described above, the sputtering apparatus of the present invention defines the width of the erosion area satisfying both target values of the small film thickness distribution and the large step coverage in relation to the diameter of the substrate or the size of the long side. Therefore, if the width of the erosion area is within the range, it is possible to obtain a uniform sputtered film having a small film thickness distribution and a large step coverage.

Further, as described above, by setting the diameter or the long side of the substrate to a predetermined size, setting the distance between the substrate and the target to a predetermined size, or setting a plurality of substrates in a predetermined arrangement, It is possible to obtain a sputtered film having a small film thickness distribution and a uniform step coverage.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. First
The figure shows the structure of a sputtering apparatus according to the present invention. A plurality of substrates 3 are fixed to a substrate holder 2 arranged inside a vacuum container 1, and a target 4 is placed on a target holder 5 facing a substrate. Fixed and target 4 substrate 3
On the opposite side, a pair of permanent magnets 6 are arranged so that the magnetic poles are different, the yoke 7 forms a magnetic path on one side of the magnet, and the earth shield 8 covers the target 4. The target holder 5 is insulated from the vacuum container 1 by an insulator 9, and is connected to a power source 11 via a matching box 10. The vacuum vessel 1 is at ground potential and therefore the target holder is at ground potential as well as the vacuum vessel. Normal target 4 and target holder 5
The magnet (hereinafter referred to as magnetron magnet) 6 and the target 4 are water-cooled by a pipe passing through the inside of the target holder 5. Vacuum container 1 is 2
Two pipes 12 and 13 are provided, a sputter gas such as Ar is supplied from one pipe 12, and the other pipe 13 is connected to a vacuum exhaust device such as a cryopump.

Next, a process of forming a sputtered film on the substrate 3 will be described with reference to FIG. The vacuum vessel 1 is a vacuum pumping device, 10 ^-7 Torr
After being evacuated to a high vacuum of the order, a sputtering gas such as Ar is supplied, and the vacuum container is maintained at a vacuum degree of the order of 10 ⁻⁴ Torr, for example. Here, the target 4 electrically connected to the target holder is supplied with a high frequency power source of 13.5 MHz from 11 for example. As a result, a plasma discharge is generated between the target 4 and the substrate holder 2. On the surface of the target 4, the leakage magnetic field of the magnetron magnet 6 forms a magnetic field tunnel as shown by the dotted line 14 and the electrons in the plasma are confined in the magnetic field by the electromagnetic force, and the frequency of collision with gas increases, A dense plasma is produced. The target 4 may be made of any material, but in this embodiment, permalloy, which is a magnetic material, is used.

The positive ions in the plasma are the target 4 that serves as the cathode.
The particles constituting the target are repelled, become sputtered particles, adhere to the substrate 3 which is normally heated, and the film grows. Here, the region between the pair of magnetron magnets 6 where the sputtering phenomenon is promoted and the target is drastically reduced is defined as the erosion area defined by the center line between the pair of magnetron magnets 6. FIG. 2 is a view taken in the direction of the arrow from AA ′ in FIG. 1, and shows the substrate 3 (diameter d), the target 4 and the pair of magnetron magnets 6, and the width a of the rectangular erosion area and its length b. Is shown. The plurality of substrates 3 (three substrates are shown here, but more may be used) are arranged on a straight line approximately in the longitudinal direction of the rectangular erosion area. When forming a film on a plurality of substrates, it is required to form a uniform film on the plurality of substrates in order to enhance the industrial utility value. Here, it was found by calculation and experiments that there is a width of the erosion area that can satisfy both the requirements of a particularly small film thickness distribution and a high step coverage.

FIG. 3 shows the relationship between the calculated erosion area width and the film thickness distribution, which is a V-shaped characteristic having the minimum value in the erosion area width having a film thickness distribution. FIG. 4 shows the relationship between the erosion area width and the step coverage. The step coverage increases with the increase of the erosion area width and then decreases. The smaller the film thickness distribution and the larger the step coverage are, the better the characteristics of the film are. However, the upper limit of the usable film thickness distribution and the lower limit of the step coverage are shown as the target range in FIGS. 3 and 4. FIG. 3 shows the film thickness distribution and the erosion area width that satisfies both the target range of the step coverage shown in FIG. 4 together with FIG. 3 and 4 show the calculation results for a practically used 3-inch diameter substrate, the same results were obtained for a 5-inch diameter substrate. To calculate the film thickness, use the formula described in Reference (1),
The measurement was performed by applying the measured emission angle distribution of sputtered particles. Fig. 3 shows the measured data (deposition conditions: injection power 3kW,
Sputtering gas Ar and gas pressure 2-3 × 10 ⁻⁴ Torr) are also shown together, and they are in good agreement with the calculation results.

The width a of the erosion area that satisfies both the target of the film thickness distribution and the step coverage is 112 m in the case of the 3-inch substrate.
The range is from m to 192 mm. On the other hand, when the calculation is performed for a 5-inch substrate, both targets are satisfied when the width a is in the range of 132 mm to 212 mm. Here, in order to reduce the film thickness distribution,
It can be seen from FIGS. 3 and 4 that a value near the middle value of the fluctuation range may be selected as the value of a, while a larger value may be selected as the value of a in order to increase the step coverage.

As described above, in the case of the 3-inch substrate, the width a of the erosion area that satisfies both the target of the film thickness distribution and the step coverage is in the range of 112 mm to 192 mm. This is expressed by the following equation when the substrate diameter is d (mm).

2d−40 ≦ a ≦ 2d + 40 (mm) Similarly, in the case of a 5-inch substrate, the width of the erosion area 132 mm to 212 mm that satisfies both the target of the film thickness distribution and the step coverage can be expressed by the following formula. it can.

2d (5/3) ^1/4 −40 ≦ a ≦ 2d (5/3) ^1/4 +40 (mm) When the substrate diameter is expressed in α (inch) in addition to d (mm), the above two equations are It can be summarized as the following formula.

2d (α / 3) ^1/4 −40 ≦ a ≦ 2d (α / 3) ^1/4 +40 (mm) The range of a in this formula is applicable to 3 inch substrate and 5 inch substrate which are often used in practice. This is clear from the above description, but if the film-forming area is on the order of this order, it is sufficiently applicable to substrates of other shapes regardless of the size of the substrate.

By setting the width a of the erosion area within the above range, it is possible to obtain a uniform film having a small film thickness distribution and a large step coverage on a plurality of substrates.

FIG. 5 shows the relationship between the inter-electrode distance (distance between the substrate 3 and the target 4 in FIG. 1) and the film thickness distribution. As a result of calculating two types of substrate shapes, the film is formed on a plurality of substrates. It is understood that the distance between the electrodes should be 90 mm or more to form a film with a small thickness distribution.

Therefore, if the distance between the electrodes is 90 mm or more, there is an effect that a film having a small film thickness distribution can be formed.

FIG. 6 shows a different embodiment of the present invention, and the pipes 12 and 13 in FIG. 1 are not shown in the figure because they are displaced by 90 degrees from those in FIG. The difference from FIG. 1 is that the vacuum container 1
In the example in which the Helmholtz coil 15 is arranged outside of, and a coil for inducing uniaxial magnetic anisotropy is used in the film, in this figure as well, if the erosion area width a is contained in the region of the above formula, A film capable of inducing magnetic anisotropy has an effect of having a small film thickness distribution and a large step coverage.

FIG. 7 shows a further different embodiment in which a permanent magnet 16 is arranged so that a unidirectional magnetic field can be applied to the substrate 3, and the same effect can be obtained if the erosion area width a is contained in the area of the above formula.

FIG. 8 shows a case where the substrate 3 has a square shape. Even in this case, d in the above equation can be similarly calculated by inserting the length d of one side in FIG. 8, and in the case of a rectangular substrate, the long side may be d.

In FIG. 9, the shape of the erosion area 17 sandwiched between the permanent magnets 6 shown in FIG. 2 is an elliptical shape, unlike the rectangle shown in FIG. Also in this case, by defining the width a of the erosion area as described above, it is possible to form a uniform sputtered film on a plurality of substrates.

FIG. 10 shows a case where a plurality of substrates are arranged in a row. At this time, if d is a short side of a shape determined by the outermost sides of the plurality of substrates as shown in the drawing, it can be applied to the above equation, The same effect can be obtained.

When the length b of the erosion area shown in FIG. 2 is short,
Due to the influence of spatter from the erosion area on the short side, the thickness of the substrate at both ends is greater than that of the substrate at the center,
The film thickness distribution becomes worse. The longer the length b of the erosion area is, the better the film thickness distribution and the step coverage are, but the shorter the better in making the device. When n substrates of diameter d (mm) are arranged on a straight line and the length b of the erosion area is set to the shortest b = n · d, the film thickness distribution is poor and at least 25 mm away from the outer substrate. It turns out to be good to place an erosion area. When arranging a plurality of substrates on a straight line, the substrates are not arranged without a gap, and usually a space of about 15 mm is set. Therefore, multiple (n
), The length b of the erosion area is the outer length of the first and nth substrates [nd +
It is better to make it longer than the sum of (n-1) · 15] and 2 × 25 (mm) = 50 (mm). When this is expressed by an equation, b ≧ nd + (n−1) · 15 + 50 (mm), and the film thickness distribution and the step coverage are excellent.

Further, as shown in FIG. 2, by arranging a plurality of substrates on a straight line substantially in the center in the longitudinal direction of the erosion area, each substrate is similarly affected by the spatter from the erosion area composed of long sides, and the short length is shortened. It is less affected by the erosion area consisting of edges, and is characterized in that a uniform film can be formed on a plurality of substrates.

References (1) JB Bindlell and others: Step Coverage fro
m an Extended Sputtering Source Thin Solid Films 2
3 31-47,1974 [Effect of the invention] According to the present invention, the film thickness distribution of the film formed on a plurality of substrates can be made small and the step coverage can be made large. The effect is that a uniform film can be formed over the entire area.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a top view as seen from AA 'in FIG. 1, FIG. 3, FIG.
FIG. 5 is a characteristic diagram showing the film thickness distribution and step coverage,
FIG. 6 is a sectional view showing another embodiment, and FIGS. 7 to 10 are partial views showing still another embodiment. 3 ... Substrate, 4 ... Target, 6 ... Permanent magnet, a ... Erosion area width, b ... Erosion area length, 15 ... Helmholtz coil, 16 ... Permanent magnet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Sato 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Hidetsugu Seto 1-1 1-1 Kokubuncho, Hitachi City, Ibaraki Stock Hitachi, Ltd., Kokubun Plant (72) Inventor, Mitsuhiro Kamei 1-1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture Stock, Hitachi, Ltd., Kokubun Plant (56) Reference JP-A-62-33764 (JP, A)

Claims (8)

[Claims] 1. A target comprising a substrate holder capable of holding a plurality of substrates, a target facing the substrate holder, and a pair of magnetron magnets arranged on the back surface of the target, in a vacuum container capable of maintaining airtightness. In a sputtering apparatus for forming a thin film on a plurality of substrates held on the substrate by sputter particles from the target by supplying electric power to the substrate to generate plasma discharge in the supply of the sputtering gas. The erosion area defined by the center line between the magnets has a shape defined by the short side and the long side, and the width a (mm) that is the short side is the diameter of the substrate (or the length of the rectangular substrate). Side) is d (mm),
A sputter characterized by having an erosion area width a of 2d (α / 3) ^1/4 −40 ≦ a ≦ 2d (α / 3) ^1/4 +40 (mm) when expressed in α (inch) apparatus. 2. The sputtering apparatus according to claim 1, wherein the erosion area has a rectangular shape. 3. The sputtering apparatus according to claim 1, wherein the shape of the erosion area is an elliptical shape. 4. The sputtering apparatus according to claim 1, further comprising a Helmholtz coil as a magnetic field applying means to the substrate surface. 5. The sputtering apparatus according to claim 1, further comprising a permanent magnet as the magnetic field applying means to the substrate surface. 6. A target comprising a substrate holder capable of holding a plurality of substrates, a target facing the substrate holder, and a pair of magnetron magnets arranged on the back surface of the target, in a vacuum container capable of maintaining airtightness. In a sputtering apparatus for forming a thin film on a plurality of substrates held on the substrate by sputter particles from the target by supplying electric power to the substrate to generate plasma discharge in the supply of the sputtering gas. The erosion area defined by the center line between the magnets has a shape defined by short sides and long sides. The length b, which is the long side of the erosion area, is the number of substrates n, the diameter or length of the substrates. Edge d
The sputter device is characterized by having an erosion area length b such that b ≧ nd + (n−1) · 15 + 50 (mm) when (mm). 7. The sputtering apparatus according to claim 6, further comprising a Helmholtz coil as a magnetic field applying means to the substrate surface. 8. The sputtering apparatus according to claim 6, further comprising a permanent magnet as the magnetic field applying means to the substrate surface.