JP2003213409A - Method and apparatus for film deposition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain both a high step coverage characteristic and uniform thickness distribution. <P>SOLUTION: An alternating voltage of constant power is applied to a target electrode 12 and a substrate electrode 14 in a vacuum vessel 10 containing an Ar gas from a power source 20 for a target and a power source 22 for a substrate, respectively. Thereby, discharge is generated between the target electrode 12 and the substrate electrode 14. The sputtering of the target electrode 12 is carried out by the discharge, and sputtered particles are deposited on the substrate electrode 14. At that time, the bias electrical potential of the substrate electrode 14 is detected, the phase difference of an alternate current signal outputted from each power source 20 and 22 is adjusted according to the bias electrical potential with a phase adjuster 24, and impedance based on the discharge is controlled constant. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method and apparatus, and in particular, an AC voltage is applied to a target electrode and a substrate electrode to form a discharge between the electrodes, and the target electrode is sputtered by this discharge. The present invention relates to a film forming method and apparatus suitable for depositing sputtered particles on a substrate electrode to form a film.

[0002]

2. Description of the Related Art As a film forming apparatus, there is known a sputtering apparatus which employs a sputtering method instead of the conventional plating method. This kind of sputtering apparatus has been in increasing demand in various fields as one of means for thinning various materials.

Among the sputtering methods adopted in the sputtering apparatus, the method of applying an alternating voltage to the target electrode and the substrate electrode, which are arranged to face each other in the vacuum container, is known as the bias sputtering method. When the film is formed by the bias sputtering method, the parameters that can be set regarding the process are the AC output applied to the target electrode, the bias potential applied to the target electrode, the AC output applied to the substrate electrode, the bias potential on the substrate side and each It is the phase difference of the AC signal applied to the electrodes. Among them, as a combination of commonly set parameters,
(1) The phase difference between the AC output applied to the target electrode and the AC output applied to the substrate electrode, (2) the AC output applied to the target electrode, the bias potential on the substrate side, and the AC output applied to each electrode are is there. Particularly, as a method for forming a film while keeping the phase difference of the AC signal constant, for example,
It is disclosed in Japanese Patent Laid-Open No. 3-107456.

[0004]

In the above-mentioned prior art, various film forming methods are adopted from the viewpoint of enhancing the functionality of thin film materials. The first priority of the function is the uniformity of film thickness. It is in. Next, flattening, that is, maintaining functions such as high step coverage, film stress, and film hardness above a certain range.

Considering that, as a recent tendency, depending on the shape of the device, the film thickness is required to be flattened more than the film thickness uniformity, the film deposition method with the film thickness uniformity as the first priority is taken into consideration. Then, it is not possible to form a film according to the demand.

That is, simply by applying an AC voltage to the target electrode and the substrate electrode, it is not possible to follow the change in the impedance of the discharge (plasma) generated between the electrodes, and etching is performed from the start of discharge to the end of discharge. It is uncertain how the quantity will be.

Further, even when the phase difference between the alternating current output applied to each electrode and the bias potential on the substrate side is kept constant while the phase difference between the alternating current output applied to each electrode is kept constant, the discharge impedance changes from moment to moment. Therefore, a film having a high step coverage cannot be formed.

An object of the present invention is to provide a film forming method and apparatus capable of achieving both high step coverage and uniform film thickness distribution.

[0009]

In order to solve the above-mentioned problems, the present invention applies an AC signal to each of a target electrode and a substrate electrode which are arranged opposite to each other in a vacuum container containing a process gas. An alternating current applied to the target electrode when a discharge is formed between the target electrode and the substrate electrode, and the target electrode is sputtered by the formed discharge to deposit sputtered particles on the substrate electrode to form a film. The film forming method is characterized by forming a film while changing the phase difference between the signal and the AC signal applied to the substrate electrode.

When the film forming method is adopted, the film is formed while the phase difference is controlled to be constant, or the AC signal applied to the target electrode and the substrate electrode are applied so that the impedance due to the discharge becomes constant. It is also possible to form the film while changing the phase difference of the alternating signal.

In adopting each of the above film forming methods, the following elements can be added.

(1) A film is formed in a state where the power of the AC signal applied to the target electrode and the power of the AC signal applied to the substrate electrode are kept constant.

Further, according to the present invention, a vacuum container for containing a process gas, a target electrode housed in the vacuum container, and a substrate electrode housed in the vacuum container so as to face the target electrode. A target power supply for applying an AC signal to the target electrode, a substrate power supply for applying an AC signal to the substrate electrode, an AC signal generated by the output of the target power supply, and an AC signal generated by the output of the substrate power supply. And a phase adjuster for adjusting the phase difference, by sputtering the target electrode according to the discharge formed between the target electrode and the substrate electrode by applying the AC signal, to deposit sputtered particles on the substrate electrode. A film forming apparatus for forming a film is configured.

In constructing the film forming apparatus, the following elements can be added. (1) Each of the target power supply and the substrate power supply maintains a constant output power of an AC signal. (2) The phase adjuster is adjusted so that the phase difference of the AC signal due to the output of each power supply is kept constant.

According to the above-mentioned means, when the film is formed while changing the phase difference between the AC signal applied to the target electrode and the AC signal applied to the substrate electrode, the current flowing through the substrate electrode between the start of discharge and the end of discharge is reduced. Since the amount becomes constant, the discharge impedance seen from the substrate electrode can be kept constant. That is, by changing the phase difference of the AC signal applied to each electrode so that the impedance due to the discharge (plasma) becomes constant, the energy and amount of ions jumping into the substrate electrode can be controlled, and the efficiency can be kept constant. The etching amount can be secured. In particular, since the etching at the step corners of the pattern on the substrate electrode is always performed constantly, a high step coverage can be obtained. Further, by making the phase difference constant, it is possible to keep the interference of the plasma generated by the power output applied to each electrode constant and to ensure the uniformity of the film thickness.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a sputtering apparatus showing an embodiment of the present invention. In FIG. 1, a sputtering apparatus that employs a bias sputtering method as a film forming apparatus includes a vacuum container 10, a target electrode 12, a substrate electrode 14, matching devices 16 and 18, a target power supply 2
0, a substrate power source 22, a phase adjuster 24, and an oscillator 26.

Ar gas is introduced into the vacuum container 10 as a process gas from a gas inlet (not shown), and the inside of the vacuum container 10 is maintained at a set gas pressure. Further, the target electrode 12 is provided in the vacuum container 10.
And the substrate electrode 14 are arranged to face each other, the target electrode 12 is connected to the target power supply 20 via the matching device 16, and the substrate power supply 14 is connected to the substrate power supply 22 via the matching device 18. Has been done. That is, each of the power supplies 20 and 22 is connected to the target electrode 12 or the substrate electrode 14 via the matching devices 16 and 18 for matching the impedance of the load.

The target power supply 20 includes a phase adjuster 24.
A low-frequency or high-frequency AC signal is input from the input terminal, the input signal is amplified, and a feedback signal f1 related to the output of the target electrode 12 and the bias potential is input, and the output power is kept constant while monitoring the feedback signal f1. The AC signal is configured to be applied to the target electrode 12 via the matching device 16.

On the other hand, the board power source 22 is composed of a phase adjuster 24.
A low-frequency or high-frequency AC signal is input from the amplifier, the input signal is amplified, and a feedback signal f2 regarding the output of the substrate electrode 14 and the bias potential is input.
While monitoring the feedback signal f2, an AC signal is applied to the substrate electrode 14 via the matching device 18 while keeping the output power constant.

The phase adjuster 24 inputs a low-frequency or high-frequency AC signal from the oscillator 26, generates an AC signal of phase φ1 from the input AC signal, and outputs the generated AC signal to the target power supply 20. Further, an AC signal of phase φ2 is generated from the input AC signal, and the generated AC signal is output to the board power supply 22. Further, in order to monitor the phase of the AC signal applied to the target electrode 12, the AC signal applied to the target electrode 12 is input as the feedback signal f3 to the phase adjuster 24, and at the same time, to the substrate electrode 14. In order to monitor the phase of the applied AC signal, the AC signal applied to the substrate electrode 14 is input as the feedback signal f4.

Phase adjuster 24 to which various signals are input
Monitors the feedback signals f3 and f4,
Phase difference of the AC signals output to the respective power supplies 20 and 22 (φ1-
φ2) is adjusted. In this case, the phase adjuster 24 adjusts the phase φ2 of the AC signal output to the substrate power supply 22 while controlling the phase φ1 of the AC signal output to the target power supply 20, and controls the phase difference between the two. Is configured to. As the high-frequency AC signal, for example, a 13.56 MHz signal can be used.

In the above structure, when an AC voltage whose output power is kept constant is applied to the target electrode 12 and the substrate electrode 14, respectively, the target electrode 12 and the substrate electrode 14
And a discharge is generated between them and plasma by Ar gas is generated. When the target electrode 12 is sputtered by this discharge or plasma, the target electrode 12
Sputtered particles fly out of the substrate, and the sputtered particles are deposited on the substrate electrode 14 to form a film. In this case, since the speed of electrons is higher than that of Ar + ions, when a positive voltage of the AC signal is applied to each electrode, the positive charges are neutralized by the attachment of electrons. On the other hand, when a negative voltage of the AC signal is applied to each electrode, the potential of each electrode is kept negative, and a negative bias voltage is applied to each electrode as a whole.

Here, when the output (power) of the AC signal applied to the target electrode 12 and the bias voltage of the substrate electrode 14 are made constant and the phase difference of the AC signal applied to each electrode is adjusted, the characteristic A in FIG. , B were obtained. The characteristic A in FIG. 2 shows the change in the output of the alternating current applied to the substrate electrode 14 when the phase difference of the alternating current output applied to each electrode is changed. Characteristic B shows a change in the bias potential of the target electrode 12 when the phase difference of the AC output applied to each electrode is changed. In this case, the matching device 16 matches the impedance of the load with the impedance of the line to efficiently apply the AC voltage to the target electrode 12. Further, with respect to the substrate electrode 14, while monitoring the bias potential of the substrate electrode 14, the output of the power supply 22 is adjusted so that the potential becomes constant.

Next, phase control for keeping the phase difference of each AC signal constant and power control for keeping the output of the AC signal applied to the substrate electrode 14 constant while adjusting the phase difference of each AC signal were performed. However, the results shown in FIG. 3 were obtained. FIG. 3 is a characteristic diagram showing the relationship between the bias potential of the substrate electrode 14 and the step coverage. Both the characteristic A by the phase control and the characteristic B by the power control show the output of the alternating current applied to the target electrode 12 and the substrate electrode 14. The bias potential is the result when measured with the bias potential kept constant.

Here, the quantitative evaluation of the step coverage is performed by the following equation (1) in consideration of the relationship shown in FIG.

B / c × 100 (%) (1) b: minimum film thickness in the vicinity of the step c: average film thickness in a region away from the vicinity of the step The step (on the substrate electrode 14) When the relative relationship between the height a of the stepped portion formed by the formed pattern and the b is changed, the value of the c is changed even for the same b.
/ C is kept constant.

From the result of FIG. 3, in the case of phase control, characteristic A
As shown by, it can be confirmed that as the bias potential on the substrate electrode 14 side is increased, the step coverage is increased up to about -200V. However, when a bias potential is further applied to reach a bias potential of, for example, about −300 V, among the patterns on the substrate electrode 14,
The etching effect strongly appears on the corners of the step,
It can be seen that the step coverage is decreasing.

On the other hand, in the case of power control, as shown by the characteristic B, the bias potential of the substrate electrode 14 is set to about −.
Even if it is raised to around 220V, the etching effect does not appear,
It can be seen that the step coverage is high.

As described above, according to this embodiment, the phase difference of the AC signal applied to each electrode is kept constant while the power of the AC output applied to each electrode is kept constant.
Since the phase difference is adjusted so that the impedance due to the discharge becomes constant, it is possible to achieve both high step coverage and uniform film thickness distribution.

Further, since the step portion can be formed with the minimum film thickness, the film forming time can be shortened.

Further, since the film can be formed without forming a hole in the region near the step, it is possible to improve the film quality and contribute to the improvement of the yield, and the production in the next step. It can contribute to the improvement of the sex.

[0032]

As described above, according to the present invention,
Since the high step coverage and the uniform film thickness distribution are made compatible, the film quality can be improved and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a sputtering apparatus showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between target potential, bias power, and phase difference.

FIG. 3 is a characteristic diagram showing a relationship between a bias potential and step coverage in phase control and power control.

FIG. 4 is a diagram for explaining a quantitative evaluation of step coverage.

[Explanation of symbols] 10 vacuum container 12 target electrode 14 substrate electrode 16, 18 Matching device 20 Target power supply 22 Substrate electrodes 24 Phase adjuster 26 oscillators

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuhiro Kamei             1-1-1 Kokubuncho, Hitachi-shi, Ibaraki Stock             Hitachi High-Technologies Corporation Design / Manufacturing             Kokubu Business Office (72) Inventor Ken Tanaka             1-1-1 Kokubuncho, Hitachi-shi, Ibaraki Stock             Hitachi High-Technologies Corporation Design / Manufacturing             Kokubu Business Office F-term (reference) 4K029 AA29 BD01 CA05 DC29 DC35                       EA09                 4M104 DD39

Claims (7)

[Claims] 1. A discharge is formed between the target electrode and the substrate electrode by applying an AC signal to the target electrode and the substrate electrode, which are arranged opposite to each other in a vacuum container containing a process gas, When the target electrode is sputtered by the formed discharge to deposit sputtered particles on the substrate electrode to form a film, the phase difference between the AC signal applied to the target electrode and the AC signal applied to the substrate electrode is changed. While forming a film, a film forming method. 2. A discharge is formed between the target electrode and the substrate electrode by applying an AC signal to the target electrode and the substrate electrode, which are arranged opposite to each other in a vacuum container containing a process gas, A film forming method characterized in that, when the target electrode is sputtered by the formed discharge to deposit sputtered particles on the substrate electrode to form a film, the impedance due to the discharge is controlled to be constant. 3. A discharge is formed between the target electrode and the substrate electrode by applying an AC signal to the target electrode and the substrate electrode, which are arranged opposite to each other in a vacuum container containing a process gas, When the target electrode is sputtered by the formed discharge to deposit sputtered particles on the substrate electrode to form a film, an AC signal applied to the target electrode and the substrate electrode are applied so that the impedance due to the discharge becomes constant. A film forming method, which comprises forming a film while changing a phase difference of an AC signal applied to the film. 4. Any one of claims 1, 2 and 3
The film forming method as described in the item 1, wherein the film is formed in a state in which the power of the AC signal applied to the target electrode and the power of the AC signal applied to the substrate electrode are kept constant. 5. A vacuum container for containing a process gas, a target electrode housed in the vacuum container, a substrate electrode housed in the vacuum container facing the target electrode, and a target electrode for the target electrode. A target power supply for applying an AC signal, a substrate power supply for applying an AC signal to the substrate electrode, and a phase difference between an AC signal output by the target power supply and an AC signal output by the substrate power supply are adjusted. A phase adjuster is provided, and the target electrode is sputtered according to the discharge formed between the target electrode and the substrate electrode by applying the AC signal to deposit sputtered particles on the substrate electrode to form a film. Film forming equipment. 6. The film forming apparatus according to claim 5, wherein the phase adjuster adjusts a phase difference between the AC signals according to a bias potential of the substrate electrode. apparatus. 7. The film forming apparatus according to claim 5, wherein the target power supply and the substrate power supply each hold a constant output power of an AC signal.