JPH0641732A - Sputtering method - Google Patents

Abstract

PURPOSE:To uniformalize the film thicknesses by passage of trays by changing the electric power of sputtering according to the position of a support with respect to a target. CONSTITUTION:Plural sheets of substrates 3 to be formed with thin films are mounted to the plural sheets of trays 2 which are then introduced into a sputtering device 1. The film thickness distribution tends to be thicker near the ends of the trays 2 and thinner near the center and the positions of the trays 2 are therefore detected by beam sensors, etc., and a power source is so controlled as to increase the supply electric power nearer the central part of the trays 2 by computation from the moving speed of the trays 2. As a result, the film thickness distribution is surely decreased and the effective method is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film by a passage type sputtering apparatus. The present invention particularly relates to a method of making a formed film thickness uniform in a sputtering method using a high frequency power source.

[0002]

2. Description of the Related Art A passage type sputtering apparatus is often used when it is required to form a film at a relatively low cost such as a recording layer film formation of a magnetic disk / optical disk. Usually, a plurality of substrates are set on a tray (support for substrates) and are collectively processed. At that time, a technique for forming a film so that the thickness of the formed film is uniform is required. As a sputtering method, there are cases where a direct current power source (DC) is used and cases where a high frequency power source (RF) is used. The former is characterized by relatively stable discharge, and the latter is characterized by being able to sputter even an insulator. .

[0003]

In the passage type sputtering apparatus, it should be considered that the internal structure of the apparatus substantially changes with time due to the passage of the tray. When a high-frequency power source whose discharge is relatively unstable is used, the discharge state may change due to passage of the tray, and a film thickness distribution may occur in the tray advancing direction. In order to prevent this phenomenon, it is important to reduce the change in the discharge state due to the passage of the tray. For that purpose, installation of a plate covering the gap of the tray, or a structure for confining plasma in a specific space have been considered.

In the case of a passing type sputtering apparatus, it is structurally difficult to eliminate the gap between the trays. Even when a plate covering this gap is installed, plasma may flow from the empty space. In particular, in the case of sputtering using high frequency, plasma easily wraps around even in a slight gap, a change in discharge state occurs, and a film thickness distribution in the tray advancing direction cannot be avoided.

[0005]

The present invention has been made to solve the above problems, and is to predict the film thickness distribution to occur in advance and change the discharge power accordingly. The gist of the present invention is a pass-through sputtering method in which sputtering is performed while moving a substrate attached to a support in front of the target in a decompression tank, and a thin film is deposited on the surface of the substrate, and the method is used to position the support relative to the target. According to the present invention, there is provided a sputtering method characterized in that the sputtering power is changed. Less than,
The present invention will be described in detail.

FIG. 1 is a schematic explanatory view of an example of an apparatus used in the method of the present invention. In the figure, 1 is a passage type sputtering device, 2 is a substrate support (tray), 3 is a substrate, 4 is a charging chamber, 5 is a sputtering chamber (decompression tank), 6 is a target, 7 is a take-out chamber, 8, 9 and Reference numeral 10 denotes a suction port, and 11 denotes a gas supply port. In order to perform sputtering using the passage type sputtering device 1, a plurality of substrates 3 for forming thin films such as optical disc substrates and semiconductor substrates on the surface are prepared, and the substrates 3 are used as a support (tray) 2. It is installed and introduced into the sputtering apparatus 1 from the charging chamber 4.
The charging chamber 4, the sputtering chamber (decompression tank) 5, and the take-out chamber 7 of the sputtering apparatus 1 are depressurized by sucking air from the suction ports 8, 9 and 10. Normally, a predetermined amount of argon gas is supplied from the gas supply port 11. It is in a state suitable for sputtering. When performing reactive sputtering or the like, a gas such as nitrogen or oxygen may be supplied from the gas supply port 11.

The support (tray) 2 to which the substrate 3 introduced from the preparation chamber 4 is attached passes through the front of the target 6 while moving at a predetermined speed, and the molecules sputtered from the target are on the surface of the substrate 3. To form a thin film. When the sputtering is completed, it is taken out from the take-out chamber 7. In the thin film forming step, in the case of the passage type sputtering apparatus used in the present invention, the discharge state changes depending on whether the end portion or the central portion of the support 2 is located in front of the target. This causes a distribution in the film thickness as described above.

In the present invention, first, the film thickness distribution in the traveling direction of the tray 2 is measured without controlling the power supply.
It suffices if there is no in-plane film thickness distribution of the substrate 3 installed on the tray 2, but more preferably, in order to clearly know the distribution state, the inside of the tray 2 including the part where the substrate 3 is not installed is included. The thickness of the deposited thin film is measured at regular intervals. The same measurement is performed on a plurality of trays 2 to confirm the reproducibility of the distribution, and the average value of the film thickness is obtained at each position in the tray 2 to obtain a typical film thickness distribution inside the tray 2. Further, the average value of the tray 2 in the vertical direction is calculated and the tray 2
The film thickness distribution d (x) in the horizontal direction (traveling direction) is obtained.
(X: lateral position of tray) Next, regarding the control method, assuming that the relationship between the discharge power (electric power) and the sputter rate can be approximated linearly (Δd / Δp = constant), the control formula is as follows. become that way.

[0009]

## EQU00002 ## p (x) = po + C.multidot. (Dm-d (x)) Equation (1) where p (x) is the input power at the position x of the support, po
Is the power when not controlled, dm is the average value of the film thickness when not controlled,
d (x) is the film thickness at the position (x) of the support when not controlled, C
Is a coefficient (obtained from Δp / Δd). The value of C needs to be optimized by performing sputtering several times.

Normally, the film thickness distribution is thick near the end of the tray 2 and thin near the center. Therefore, in order to make the film thickness uniform, control is performed such that the power supply is increased when the vicinity of the central portion of the tray 2 is located rather than when the end portion of the tray 2 is located in front of the target 3. Become. Next, the hardware for realizing the above power supply control will be described. This is just an example.

First, regarding the detection of the position of the tray 2, a beam sensor or the like for detecting the position of the tray 2 is usually installed in the passage type sputtering apparatus, and this is utilized. If there is no sensor, install it. The light emitting / shading signals of the sensor are fetched into a computer (such as a personal computer) and internally processed. First, the actual position of the tray 2 can be obtained by multiplying the moving speed of the tray 2 by a predetermined elapsed time from the light blocking of the sensor (passage of the tip of the tray). This is applied to the equation (1) to obtain the power p (x). At this time, d (x) is previously stored as data in the computer. The value of p (x) is sent to the controller of the power source, and the power source is controlled.

[0012]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited by the following examples unless it exceeds the gist.

Example 1 A recording layer of an optical disk was formed by using the apparatus schematically shown in FIG. As the sputtering device, one capable of mounting eight 5.25-inch optical disk substrates per tray was used. A rectangular target having a composition ratio of Te ₈₅ Se ₁₅ was used as the target, the pressure inside the apparatus was reduced, and argon gas was introduced up to 1 × 10 ⁻² Torr from the gas supply port.
High frequency sputtering was performed with a power of W. The tray transport speed was 330 mm / min.

The film thickness of the obtained film was measured by a fluorescent X-ray analyzer for 5 trays, and the average value at 4 lateral positions in the tray was determined. The film thickness is 28 in order from the tray advancing direction.
5Å, 260Å, 265Å, 285Å, ± 4.6
% Film thickness distribution. (Thickened at both ends of the tray and thinner at the center of the tray). The average of 4 points is 274
It becomes Å.

In this system, since the sputtering power and the sputtering speed are in a substantially proportional relationship, C in the equation (1) is
220/274 = 0.803. When the control power is calculated by the equation (1), it is 21
It becomes 1W, 231W, 227W, 211W. Based on this result, sputtering was performed while changing the power supply amount. The power was changed in the form of a line graph. Other conditions are exactly the same as before control.

The film thickness of the obtained film was measured by a fluorescent X-ray analyzer for 5 trays, and the average value at 4 lateral positions in the tray was determined. The film thickness is 27 in order from the tray advancing direction.
5Å, 270Å, 275Å, 265Å, ± 1.9
%, The film thickness distribution was almost uniform.

[0017]

According to the method of the present invention, the film thickness distribution can be surely reduced. Therefore, it is practically very effective for producing optical disks, semiconductor devices, and the like.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an apparatus used in the method of the present invention.

[Explanation of symbols]

 1 Passing Type Sputtering Equipment 2 Substrate Support (Tray) 3 Substrate 4 Loading Room 5 Sputtering Room (Decompression Tank) 6 Target 7 Removal Room

Claims (3)

[Claims] 1. A pass-through sputtering method in which a substrate mounted on a support is moved in front of a target in a decompression tank while performing sputtering to deposit a thin film on the surface of the substrate according to the position of the support relative to the target. The sputtering method is characterized in that the sputtering power is changed. 2. The sputtering according to claim 1, wherein the power supply is increased when the center of the support is in front of the target, compared to when the end of the support is located in front of the target. Method. 3. The sputtering method according to claim 1, wherein the index for changing the power is obtained by the following equation. [Mathematical formula-see original document] p (x) = po + C. (Dm-d (x)) where p (x) is the applied power at the position (x) of the support, po is the applied power when the control is not performed, and dm is the uncontrolled power. The average value of the film thickness d (x) represents the film thickness C at the position (x) of the support in the non-controlled state, which is a coefficient (a coefficient obtained from the relationship between the amount of power change / the amount of film thickness change).