JPH02225667A - sputtering equipment - Google Patents

Abstract

PURPOSE:To form sputtered and vapor deposited films having a uniform film thickness distribution on a large-sized substrate by providing shielding plates near the peripheral surfaces of plural targets and forming the magnetic lines of force passing near the surfaces of the shielding plates by magnetron type magnets. CONSTITUTION:The plural circular or polygonal annular targets 3, 5, 7 are concentrically disposed on a circular table 1. The permanent magnets 29, 31, 33 are disposed to the lower parts of the targets 3, 5, 7 to form the magnetron type targets 65, 67, 69. The shielding plates 53, 55, 57, 59, 61, 63 are mounted near the inner peripheral surfaces and outer peripheral surfaces of the target parts 65, 67, 69. Plasma 70 diffuses easily onto the surfaces of the shielding plates 57, 59 curved along the magnetic lines of force. High-voltage DC currents are supplied from three units of DC power source circuits to the respective targets 3, 5, 7. The outputs thereof are detected by DC wattmeters 87, 89, 91 and the detected values P1 to P3 are fed back to control circuits 81,83, 85.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a sputtering apparatus, and more particularly, to an improvement of a target for making the thickness distribution of a deposited film uniform (conventional method). (Technology) Sputtering equipment, especially sputtering equipment that processes large substrates, is required to have the ability to form a deposited film with a uniform thickness over a wide range of substrate surfaces. For this reason, conventional sputtering equipment generally employs a configuration in which a long, thin magnetron-type target with a length roughly equivalent to one side of the substrate is placed in the center of the chamber, and the substrate is passed over it at a constant speed. ing.

(Problems to be Solved by the Invention) One problem with the conventional configuration is that a large chamber is required. That is, since the substrate is moved from one side of the target to the other side within the chamber, a chamber is required that is large enough to contain an area at least twice that of the substrate. Furthermore, there is also the problem of dust. That is, when the substrate is moved, dust is generated from the transport mechanism due to wear, which adversely affects product quality.

Therefore, an object of the present invention is to enable a sputter-deposited film with a uniform thickness distribution to be formed on a large substrate while the substrate is fixed.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a plurality of ring-shaped targets arranged concentrically, a shield plate arranged near the circumferential surface of each target, and a shield plate provided for each target. A sputtering apparatus is provided in which a magnet for forming a magnetron and a power supply means capable of independently controlling the amount of power supplied to each target are used, and the magnet has lines of magnetic force passing near the surface of the shield plate.

(Function) Each concentrically arranged target forms its own film thickness distribution. By controlling the amount of power supplied to each target to an appropriate value, non-uniformities in film thickness distribution for each target cancel each other out, and a uniform film thickness distribution can be obtained. Each target is a magnetron type, and has lines of magnetic force passing near the surface of a shield plate provided near the circumferential surface of each target. Along these lines of magnetic force, the plasma on the target surface diffuses onto the shield plate surface.

This diffusion improves sputtering efficiency in high frequency sputtering.

(Example) Hereinafter, preferred embodiments of the present invention will be described.

First, the structure of a target of a sputtering apparatus according to the present invention will be explained with reference to FIGS. 1, 2, and 4.

Referring to FIG. 1, three circular ring-shaped targets 3.
5.7 are arranged concentrically around the central axis ρ of the table 1. Although the chamber is not shown, table 1
The upper side, that is, the target side, is inside the chamber, and the lower side of the table 1 is outside the chamber. A substrate is fixed in the chamber parallel to and facing the upper surface of the target 3.5.7. The surface of this substrate is marked S in Figure 2.
is shown. The inside of the chamber is brought into a substantially vacuum state through an exhaust pipe (not shown). A gas supply port 9 is provided at the center of the table 1, and a gas supply pipe 10 is connected to the gas supply port 9, through which a predetermined gas is supplied into the chamber.

A metal cooling pipe 11.13.15 through which water flows to cool the target is arranged under each target 3.5.7. Cooling water is supplied from below 1 through water supply pipes 17.19.21.

Since the cooling pipes 11.13.15 are also used as conductive paths for supplying power to each target 3.5.7, bushings 23.25.
It is electrically insulated from the table 1 by 27. A ring-shaped permanent magnet 29.31.33 is arranged below each cooling pipe 11.13.15. Each permanent magnet29.
31.33 has magnetic poles on its inner circumferential surface and outer circumferential surface. Each cooling pipe 11.13.15 and permanent magnet 29.31.
Ring-shaped iron cores 35.37.39 and iron cores 4] and 43.45 are fitted into the inner and outer peripheral surfaces of 33, respectively, and these iron cores 35.37.39.41.43
．． 45, the magnetic pole of each permanent magnet 29.31.33 is magnetically coupled to the underside of each target 3.5.7.

With this structure, three ring-shaped magnetron type target parts 65, 67, and 69 are formed.

Here, between adjacent target parts, as shown in FIG. 2, the direction of the magnetic poles is set so that the respective permanent magnets face each other with the same type of magnetic pole. By adopting such a magnetic pole arrangement, the lines of magnetic force in the target part 67 repel each other with the lines of magnetic force in the adjacent target parts 69 and 65, as shown in FIG. 3 using the center target part 67 as an example. 67's magnetic field line is adjacent target #69.
A closed loop surrounding the target 5 is formed within the target portion 67 without entering the target portion 65. Therefore, the plasma 70 is well confined near the surface of the target 5, and mutual interference due to plasma coupling between adjacent target parts (this makes power detection and control for each target part difficult in high frequency sputtering) is prevented. can do.

The target parts 65, 67, 69 are electrically disconnected from the table 1 on ring-shaped pedestals 47, 49, 51 made of an insulating material (for example, Teflon) fixed on the table 1. installed. Furthermore, a metal shield plate 5 is placed on the table 1 to prevent sputter evaporation on the inner and outer peripheral surfaces of the target parts 65, 67, and 7.
3.55.57.59.61.63 are installed.

The upper end of each shield plate 53.55.57.59.61.63 has a shape smoothly curved toward the target 3.5.7. In addition, in FIG. 3, the shield plate 57
．． As shown in example 59, some of the lines of magnetic force are connected to the shield plate 5.
7.59 and passes near its surface. This produces a useful effect in high frequency sputtering. That is, referring to FIG. 3, plasma 70 easily diffuses onto the smoothly curved surfaces of shield plates 57 and 59 along the lines of magnetic force. Due to the diffusion of the plasma 70, the impedance at the time of photoelectron emission from the shield plates 57.5 (anodes) in high-frequency sputtering decreases, thereby increasing the proportion of power supplied during sputter evaporation of the target 5, and sputtering efficiency. will improve.

FIG. 2 shows the cross-sectional structure of the target section described above, as well as
Also shown is an example circuit for powering each target. The illustrated circuit is for DC sputtering, with 3
The three DC power supply circuits 71, 73, and 75 are configured to supply high voltage DC power to each target 3.5.7. The power supply circuit 71.73.75 is
Start signal 5TA from common start switch 79
RT starts outputting all at once 4, and a stop signal 5TOP is sent from each control circuit 81.83.8'5.
The output is stopped by .

The output of the wsR circuit 71.73.75 has a DC wattmeter 87.
．． 89.91 are connected, and the power detection values P1, P2, P3 from them are fed back to the control circuit 81.83.85.

The wattmeter 87 includes an ammeter 93 that detects the current supplied to the target and a voltmeter 95 that detects the applied voltage. These outputs are multiplied by a multiplication circuit 97 to obtain a power detection value P1.

Other wattmeters 89 and 91 have a similar configuration.

The control circuit 81 integrates a setting circuit (for example, a variable resistor, a low-reswitch, etc.) 99 that sets the amount of power to be supplied to the target, and a power detection value P1 from the wattmeter 87 to determine the amount of power supplied. It has a number of integration times Nl0I to obtain. The set power amount from the setting circuit 99 and the supplied power amount from the integrating circuit 101 are input to a comparator 103, and when the supplied power amount reaches the set power amount, a stop signal 5TOP is output.
is output. The other control circuits 83 and 85 have a similar configuration.

With the circuit having such a configuration, the amount of power supplied to each target 3.5.7 is controlled independently for each target.

FIG. 4 shows an example of a power supply circuit for high frequency sputtering.

In a 5R wave sputter, if high frequency power is supplied to each target at the same time, if there is a phase difference between the targets, high frequency current will flow between the targets, making it difficult to accurately measure the power supplied to each target. Therefore, the circuit shown in Fig. 3 supplies power to each target in a time-sharing manner so that power is always supplied to only one target, and also controls the time-sharing ratio to obtain the desired power. The amount of electricity can be supplied to each target.

In FIG. 4, the output high frequency power of the high frequency oscillation circuit 105 is divided into three powers by a transformer 107,
The distributed power is amplified to a predetermined value by power amplifiers 109, 111, and 113, and then sent to a matching circuit 115.
．． 117, 119 to target 3.5.7. The power amplifiers 109, 111, and 113 receive control pulses CL C2 given from the control circuit 121.
, C3. That is, the power amplifiers 109, 111, and 113 operate with a predetermined gain only during the time period when the control pulses C1, C2, and C3 are applied, and the gain is substantially zero during the period when the control pulses C1, C2, and C3 are not applied. power amplifier 109.111.113
High-frequency power meters 123, 125, and 127 for detecting the power supplied to each target are connected to the output of the high-frequency power meters 123, 125, and 127, and the detected power values P1, R2, and R3 outputted by these power meters are fed back to the control circuit 121. .

The control circuit 121 includes an integration circuit 129.131.1 that integrates the detected powers vIP1, R2, and R3 from the wattmeters 123.125 and 27 to obtain the amount of power to be supplied to the δ target.
33, and a setting circuit 135.137.139 for setting the amount of power to be supplied to each target. Comparator 141.143.145 manually compares the set amount of power output from comparator 141.143.1.
45 provides stop signals STI, ST2, and Sr1 to the pulse distribution circuit 147 when the amount of supplied power reaches the set amount of power.

The pulse distribution circuit 147 distributes control pulses C1, C2, and C that do not overlap each other by time division.
3 and output it to 09.111.113. This pulse distribution circuit 147 determines the time width ratio of each pulse C1, C2, and C3 according to the ratio of the set power amounts from each setting circuit 135, 137, and 139. Then, this pulse distribution circuit 147 starts outputting control pulses C1, C2, and C3 in response to the start signal 5TART from the start switch 149,
The output of the corresponding control pulse is stopped by the stop signals STI, ST2, and Sr1 from each comparator 141, 143, and 145.

Note that the circuits shown in FIGS. 2 and 4 monitor the power supply and control it so that it becomes the set value, so they have the advantage of not being affected even if the power supply fluctuates midway.

Next, the operation of the above embodiment will be explained.

Referring to FIG. 2, each target 3. 5. 7 have center radii R1, R2, and R3, respectively.

Further, the substrate surface S is the target 3. 5. It is arranged at a height H from 7. The height H of the substrate is set to be more than twice the width of each target 3.5.7. By doing this, the film thickness distribution of the vapor deposited film formed on the substrate surface S is substantially independent of the width of the targets 3.5.7, and is dependent on the height H and each target 3.5.7. 5.7 center radius R1,
Amount of power supplied to R2, R3 and each target 3, 5.7 Q
1, C2, and C3. The film thickness distribution of the vapor deposited film formed on the substrate surface by one point in the target is the so-called COS.
According to the (cosine) law, it is thickest at the position corresponding to that one point and becomes thinner as it moves away from the point.

By integrating the film thickness distribution at one point over the entire surface of one target, the film thickness distribution of the vapor deposited film formed by one target is determined.

This film thickness distribution is substantially independent of the target width if the height H is twice or more the target width as described above. In this way, the M thickness distribution for one target is determined for each target 3.5.7 as a function of the height H1 center radius R1 supplied power ff1Q. By adding up the film thickness distributions for each target 3.5.7 thus determined, the film thickness distribution finally formed by the three targets 3.5.7 is determined. Then, in order to make this final film thickness distribution uniform, the center radius R1, R of each target 3.5.7 is
2, R3 and supplied power amounts Ql, Q2, and C3 are set. In this case, as the height H of the substrate increases, the film thickness distribution becomes more uniform, but the adhesion efficiency (the proportion of the sputtered target material that adheres to the substrate surface) decreases. Therefore, the height H is set to an appropriate value in consideration of both the film thickness distribution and the adhesion efficiency.

Figure 5 A-E shows the substrate height H1 each target 3.5.7
Different conditions are set regarding the center radii R1, R2, R3 and the amount of power supplied (per unit length) Q1, Q2, Q3, and the situation of the film thickness distribution determined by the above calculation for each is shown. . Here, the dashed-dotted line drawn in the figure indicates the range in which a film thickness greater than or equal to the thinnest film thickness within the range from the central axis g to the center radius R3 of the outer target 7 can be obtained. In the figure, the adhesion efficiency E1, that is, the ratio of the amount of deposited film within the range of the line to the amount of deposited film on the entire substrate, assuming that the substrate is infinitely wide, is shown to the right of the line in the figure. .

Figure 5A shows H:R1:R2:R3 -30: 50: 100:150, Ql:Q2:Q
3 −1 :l :1, that is, the film thickness distribution is shown when each target 3.5.7 is arranged at equal intervals and the same amount of electric power is supplied.

Under this condition, a clear peak appears at each target 3.5
．． It appears at the center radius position of 7, and a uniform film thickness distribution cannot be obtained. Further, the adhesion efficiency E was 84.7%.

In Figure 5B, when H:R1:R2:R3 = 50:50:100:150, Ql:Q2:Q3 -1:1:1, that is, the substrate height H is lower than in the case of Figure 5A. This is the case when we try to increase the . Although the film thickness distribution was slightly improved,
It has a hilly distribution with the center and periphery being too thin. Furthermore, since the height H increased, the adhesion efficiency E decreased to 62.1%.

Figure 5C is the same as Figure 5B when H:R1:R2:R3 -50:50:100:150, Ql:Q2:Q3 -0.75:0.66: 1.00. This is a case where the power supplies ff1Q1 and Q2 are adjusted in the same arrangement. Although the film thickness distribution has become fairly uniform, it is still too thin in the center. Furthermore, the adhesion efficiency E was slightly improved to 65.9%.

The fifth diagram is: H:R1:R2:R3 -50:38:91.5:150, Ql:Q2:Q3 -0.66:0.71:1.00,
That is, this is a case where the center radius R1, R'2 of the target and the supplied power Q1, Q2 are further adjusted. It can be seen that a very uniform film thickness distribution was obtained. However, the adhesion efficiency E was slightly lower at 57.9%.

In FIG. 5E, H:R1:R2:R3 -55:38.5:91:150, Ql +Q2:Q3 -0. 62 20, 67: 1.
00, that is, when the substrate height H is mainly increased compared to the case of the fifth diagram. An extremely uniform film thickness distribution was obtained. However, the adhesion efficiency E is 55.
It has fallen even further to 9%.

From the above considerations, it can be said that conditions such as Figure 5 or E are close to optimal.

In the embodiment described above, the number of targets was three, but the present invention is not limited to this number of targets. Of course, it does not matter if the number of targets is larger. Higher deposition efficiency can be obtained by increasing the number of targets.

Further, the shape of the target is not limited to a circle, but may be a polygon (desirable because it approaches the Wakkanai shape, which has a large number of angles).

In particular, as the radius of the target increases, the polygonal target exhibits an effect similar to that of a circular target.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of ring-shaped targets arranged concentrically are provided and electric power is supplied to them independently, so that the radius of the target and the amount of electric power supplied can be adjusted. By making appropriate settings, it is possible to obtain a uniform film thickness distribution by canceling out the non-uniformity of the film thickness distribution formed for each target. Further, since the target is of a magnetron type and has lines of magnetic force passing near the surface of the shield plate, plasma is diffused onto the surface of the shield plate along the lines of magnetic force, improving sputtering efficiency in high-frequency sputtering.

4. F! ! BRIEF DESCRIPTION OF THE J-FACE FIG. 1 is a partial cross-sectional perspective view showing the configuration of a target portion of an embodiment of a sputtering apparatus according to the present invention, and FIG. 2 is a cross-sectional structure of the target portion shown in FIG. 1 and this target portion. FIG. 3 is a cross-sectional view showing the magnetic field line distribution and plasma distribution formed near the target part in FIG. 2, and FIG. A block diagram showing an example of a power supply circuit for high frequency sputtering applied to the target section in the figure, Figures 5A to 5E
2A and 2B are diagrams showing film thickness distributions formed by the target portion of FIG. 2 under different conditions.

3.5.7...Target, 29.31.33...
Permanent magnet, 65.67.69...Target part, 71
．． 73.75... Direct a power supply circuit, 81.83.85.
...Control circuit, 87.89.91...DC wattmeter, 9
9.135.137.139...setting circuit, 101.
129.131.133...Integrator circuit, 103.14
1.143.145...Comparison circuit, 105...High frequency oscillation circuit, 107...Transformer, 109.111.
113... Power amplifier circuit, 147... Pulse distribution circuit.

Claims (1)

[Claims] In a device that supplies power to a target in a chamber to perform sputtering on a workpiece in the chamber,
A plurality of circular or polygonal ring-shaped targets arranged concentrically, a shield plate arranged near the circumferential surface of each target, a magnet for forming a magnetron provided for each target, and each A sputtering apparatus comprising a power supply means capable of independently controlling the amount of power supplied to each target, and wherein the magnet has lines of magnetic force passing near the surface of the shield plate.