JP4521606B2 - Method and apparatus for controlling film thickness distribution in thin film manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for controlling the film thickness distribution of a thin film formed on a substrate by a thin film manufacturing apparatus, and more particularly to a method and apparatus for obtaining a desired thin film with a uniform film thickness distribution. .
[0002]
[Prior art]
In a sputtering method or a vapor deposition method used as a thin film manufacturing method, the evaporated substance generally has an evaporation angle distribution, and a film thickness distribution on the opposing substrate surface. In addition, the sputtering method has a non-uniform film formation rate in the target surface, and the evaporation method has a deviation in the evaporation direction from the evaporation source, making it difficult to make the film thickness distribution on the substrate uniform and reproducible. .
[0003]
Therefore, in the conventional thin film manufacturing apparatus, as shown in JP-A-2-11757, when the substrates are arranged facing the target, they are arranged eccentrically, and the eccentricity is optimized. It has been common practice to improve the thin film distribution on the substrate by rotating the substrate at a high speed.
[0004]
At this time, the substrate was rotated at a constant speed, and the inner surface distribution of the substrate was improved by rotating the substrate at high speed as many times as possible within the film formation time.
[0005]
In addition, in the Japanese Patent Application No. 10-238338, the present inventor is provided with a shape measuring mechanism for monitoring the target consumption state, that is, the erosion portion of the target by magnetron sputtering, and according to the target consumption state. Then, the substrate stage is driven by the control device that varies the TS distance, the optimum distance between the substrate and the target is set, the film formation rate is calculated, and sputtering is performed for a predetermined time, thereby obtaining a desired film thickness. A method and apparatus for controlling the film thickness distribution in a sputtering apparatus have been proposed to obtain a uniform film thickness distribution.
[0006]
[Problems to be solved by the invention]
However, the deposited film thickness required for electronic devices in recent years is as thin as several tens of nanometers, the film formation time is short due to the demand for shortening the tact time, and the required accuracy of the in-plane distribution is becoming increasingly strict. For this reason, the improvement of the film thickness distribution by the high-speed rotation of the substrate has a limit from the viewpoint of the rotation speed.
[0007]
In addition, as the rotation speed increases, the durability and reliability of the shaft seal introduced into the vacuum is greatly reduced, and the additional mechanism such as substrate chucking corresponding to the φ300 mm diameter substrate size that has been put into practical use in recent years is complicated. In addition, the weight is increased, making it difficult to increase the rotation speed.
[0008]
Further, as described above, even when the method proposed by the present inventor is implemented as Japanese Patent Application No. 10-238338 "Method and apparatus for controlling film thickness distribution in sputtering apparatus", the substrate has become increasingly strict. In order to clear the required accuracy of in-plane distribution stably with high productivity, further improvements have been required.
[0009]
The present invention solves the conventional problems as described above, and provides a method and apparatus for minimizing the substrate film thickness distribution resulting from the non-uniformity of the deposition rate in the target surface and the deviation of the evaporation direction. It aims at improving and the reliability of a thin film manufacturing apparatus while providing.
[0010]
[Means for solving the problems]
In the present invention, an actual value or a predicted value of the film forming rate is obtained by a film thickness monitor attached inside the film forming apparatus or measurement of a parameter that can be measured externally, and these values and a target film thickness are obtained. The predicted film formation time is calculated from the value, and the rotation speed of the motor is controlled so that the substrate is rotated an integer number of times set in advance for this predicted film formation time. The substrate rotation start time and stop time are linked to the film formation start time and film formation end time, respectively.
[0011]
An integer number of substrate rotations can offset the non-uniformity of the deposition rate within the target surface and the deviation of the evaporation direction, thereby improving the film thickness distribution on the substrate.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
(1) Description of Configuration of Embodiment As an embodiment of the present invention, an embodiment in sputtering film formation will be described with reference to the drawings.
The sputtering apparatus shown in FIG. 1 discharges the vacuum chamber (1) to a high vacuum region of about 1 × 10 ⁻³ Pa by a gas exhaust valve (11) and then discharges Ar or the like in the cylinder (9) from the gas introduction valve (7). The working gas is introduced at a pressure of about 0.08 to 3 Pa, a sputtering power is applied to the target (4) above the substrate (12) to start the discharge, and the target material is generated by the magnetron discharge generated by the magnet (2). The film of the target material is deposited on the substrate (12).
[0013]
Further, a shape measuring device (17) for monitoring the consumption state of the target (4) is provided by a driving device in which the laser displacement meter (15) is interlocked with the shape sensor motor (16) by a gear or the like. . From the shape measurement result of the target (4) by the measuring device (17), the substrate stage linked to the substrate stage motor (14) of the substrate stage driving device (18) by a gear or the like by the control device (19). (13) is driven to set the optimum distance between TSs.
[0014]
Further, the control unit (19) rotates the substrate stage (13) linked to the substrate stage rotation drive motor (20) of the substrate stage rotation drive device (21) by gears or the like an integer number of times according to the film formation time. It is configured to drive.
[0015]
(2) Description of operation and operation of the embodiment Hereinafter, in the configuration apparatus of FIG. 1, (4) a round substrate (12 mm in diameter) using an aluminum target having a diameter of 250 mm and a thickness of 6 mm as a target. An example in which an aluminum film is deposited thereon is shown.
Argon gas was introduced as a discharge gas from the gas inlet (7) to a partial pressure of 0.4 Pa, and 3.3 kW of power was applied to the target (4) by the sputtering power source (6) to form a film. .
[0016]
Note that the erosion depth (d) is measured immediately before the film formation, and the distance between the target and the substrate (T / S distance) is finely adjusted so that the film thickness distribution is the best, and the discharge measured at the time immediately before the film formation. The film formation speed (R) estimated in advance from the voltage (Vd), the discharge current (Id), etc. is calculated from the empirical formula (1) using a control computer, and the target film is further calculated from the formula (2). The film formation time (T) for obtaining the thickness (D) is obtained, the substrate stage rotation speed (r) is derived from the equation (3) so that the substrate stage rotates once in T time, and the rotation speed variable motor (20) is used. The substrate (12) and the substrate stage (13) were rotated to start film formation at the same time.
[Expression 1]
R = {2.64 × 10 ⁻⁵ × d−8.95 × 10 ⁻⁶ × d ² + 2.43 × 10 ⁻³ −1.09 × 10 ⁻⁵ × TS}
× I _d × V _d ^1.4 ...... Formula (1)
[Expression 2]
T = D / R ... Formula (2)
[Equation 3]
r = n / T (3)
However, n is 1, 2, 3,... (Natural number), and indicates that the film rotates n times within the film formation T time.
[0017]
In addition, in order to measure the film thickness with high accuracy, nine crystal oscillators with a diameter of 12.6 mm are arranged vertically and horizontally in a 100 mm diameter substrate, and the film thickness is converted to the frequency change before and after film formation. Determined by
[0018]
FIG. 2 and FIG. 3 show the film thickness distribution measurement results in the substrate when an aluminum film having a thickness of about 420 nm is deposited on the substrate. In the figure, the horizontal axis indicates the positions in the X and Y directions from the center of the substrate, and the vertical axis indicates the film thickness.
[0019]
FIG. 2 shows the result of film formation without rotating the substrate stage (13). In this case, the in-plane distribution of the substrate was ± 1.25%.
[0020]
Further, FIG. 3 shows the substrate when n = 1 in the equation (3) and the substrate stage (13) is rotated once in accordance with the film formation time and the same aluminum film is deposited as in the case without rotation. It is a film thickness distribution measurement result. At this time, the in-plane distribution of the substrate was ± 0.48%.
[0021]
From this result, the gradient of the distribution that appears to be caused by the target inhomogeneity observed when the substrate is not rotated is hardly seen by performing the substrate rotation number integer control.
[0022]
(3) Description of other examples, description of examples of diversion to other applications In the above examples, a sputtering apparatus was used as the thin film manufacturing apparatus, but it may also be used for a vapor deposition apparatus using an electron beam or resistance heating. . An example diverted to a vapor deposition apparatus is shown in FIG.
After evacuating the vacuum chamber (1) to a high vacuum region of about 1 × 10 ⁻³ Pa by the gas exhaust valve (11), electric power is supplied to the evaporation source (25) from the evaporation source (26) and the shutter (27 ) To start deposition.
[0023]
The particles evaporated from the vapor deposition source (25) are vapor-deposited on the substrate (12) attached to the substrate dome (22) arranged opposite to form a thin film.
[0024]
The thin film monitor (24) monitors the thin film deposited on the substrate (12), and when the desired film thickness is obtained by the control device (19), the shutter (27) is closed to complete the film formation.
[0025]
At this time, the substrate dome (22) linked to the substrate dome rotation motor (23) by a gear or the like is configured to be driven to rotate an integral number of times in accordance with the film formation time. A thickness distribution can be obtained.
[0026]
Needless to say, the vapor deposition start time and end time are rotated in synchronization with the rotation start time and rotation end time of the substrate (12) attached to the substrate dome (22).
[0027]
【The invention's effect】
As described above, the present invention can compensate for inhomogeneities by accurately rotating the substrate an integer number of times within the film formation time even when particles flying to the substrate are not uniform in the plane. It is possible to improve the film thickness distribution.
[0028]
In particular, since a good film thickness distribution within the substrate surface can be obtained only by controlling the substrate from one to several rotations while synchronizing with the film formation time during film formation, the substrate is rotated many times as in the prior art. Therefore, it is possible to minimize the load on the substrate stage rotating shaft, motor, gear, etc., leading to simplified structure, lighter equipment, improved maintainability, and improved durability. .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment when the present invention is applied to a sputtering apparatus.
FIG. 2 is an explanatory diagram showing a relationship between a position on a substrate and a film thickness distribution before the present invention is applied.
FIG. 3 is an explanatory diagram showing a relationship between a position on a substrate and a film thickness distribution when the present invention is applied.
FIG. 4 is an explanatory diagram of an embodiment when the present invention is applied to a vapor deposition apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Magnet 3 Backing plate 4 Target 5 Erosion 6 Power supply for sputtering 7 Gas introduction valve 8 Memory 9 Gas cylinder 10 Key panel 11 Exhaust valve 12 Substrate 13 Substrate stage 14 Substrate stage motor 15 Shape measurement sensor 16 Shape sensor motor 17 Shape measuring device 18 Substrate stage driving device 19 Control device 20 Substrate stage rotation motor 21 Substrate stage rotation driving device 22 Substrate dome 23 Substrate dome rotation motor 24 Film thickness monitor 25 Evaporation source 26 Evaporation source power supply 27 Shutter

Claims (2)

In a thin film manufacturing apparatus that deposits particles on the surface of a substrate provided in a vacuum chamber and performs film formation by sputtering,
A shape measuring device for measuring the erosion depth, which is the consumption state of the target, and
A substrate stage rotation driving device for rotating the substrate mounted on the substrate stage in advance in accordance with a film formation time for obtaining a target film thickness ;
The erosion depth, the target and the distance between the substrates, the discharge current and the predicted deposition rate calculated from the discharge voltage, to calculate a predicted deposition time from the thickness of the said object, the predicted deposition time A control device that adjusts the rotation speed so that the substrate rotates an integer number in ;
A thin film manufacturing apparatus comprising: a variable mechanism for setting a distance between the target and the substrate .   The thin film manufacturing apparatus according to claim 1, wherein the shape measuring apparatus includes a laser displacement meter.

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