JP2003073801A - Sputtering apparatus and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron sputtering apparatus which enables a via hole with a high aspect ratio to be filled up, and has a function of restraining peeling of dust from a deposition shield, and provide a method therefor. SOLUTION: The deposition shield 6c arranged near a stage 3, is formed so as to be capable of controlling a potential applied to it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus and method for performing a sputtering process on a substrate such as a semiconductor wafer.

[0002]

2. Description of the Related Art In the sputtering technique, a plasma is generated in the vicinity of a target by electric discharge, and the ions of this plasma are made to collide with the target to sputter particles, and the sputtered particles are attached to the substrate to form a thin film on the substrate. Are used to form ions or to positively ionize particles scattered from a target and draw ions by using the substrate as a bias potential to fill through holes in the substrate.

For example, the structure of a film forming chamber of a magnetron sputtering apparatus using a flat plate target will be described with reference to the cross-sectional view shown in FIG. 3. The substrate 42 for depositing a film inside the chamber 41 is a flat plate target 43. It is placed on a stage 44 that also functions as an electrode and faces each other. A magnet 45 is arranged on the back surface of the flat plate target 43, and magnetic force lines 46 are formed. Also, the flat plate target 4
A portion other than 3 is provided with an earth shield 47 so as to generate a discharge. Further, a mass flow controller 48 for controlling the flow rate of Ar gas introduced to generate an electric discharge outside the chamber 41, a valve 49, and a pump 5 for exhausting the inside of the chamber 41 to a high vacuum.
1. A high-voltage power supply 52 for applying a high voltage to the flat plate target 43 is provided.

Further, an adhesion preventive plate 53 is provided to prevent particles scattered by sputtering from the target material from adhering to each part of the chamber 41. This protective plate 5
3 is usually electrically grounded or floated. They positively ionize the particles scattered from the target, draw the ions with the substrate 42 as a bias potential, and fill the through holes.

Further, the adhesion-preventing plate 53 is subjected to a treatment for roughening the surface and providing a catch in order to prevent the film formed on itself from peeling off due to film stress or thermal stress. GBB (glass bead blast) treatment, wet etching treatment, Al spraying treatment, or the like is used for these treatments.

[0006]

However, in the magnetron sputtering apparatus described above, there is a strong demand for improvement in the embedding ability of via holes in the substrate with the miniaturization of the wiring of semiconductor devices and the like, so there is a tendency to increase the input power. is there. As a result, the amount of current flowing through the deposition-inhibitory plate increases, raising the temperature of the deposition-inhibitory plate and increasing the temperature difference between the deposition-inhibitory plate during discharge and during stoppage. As a result, the film deposited on the adhesion-preventing plate peels off due to thermal stress, and dust is generated.

Further, when the discharge is carried out for a long time, the film adhered to the deposition-inhibitory plate becomes thick and may be detached from the deposition-inhibitory plate due to thermal stress or film stress. Further, in a material having a weak binding force, a phenomenon occurs in which the material is decomposed by collision of plasma and gradually removed. In particular, a large number of adhesion-preventing plates occur in the vicinity of the thin film formed on the substrate, which is particularly remarkable in the case where the material is composed of multiple elements.

As a measure against dust due to peeling of the film deposited on the adhesion-preventing plate, as described above, the surface of the adhesion-preventing plate is blasted or Al sprayed, or a method of bonding an embossed Cu plate to the adhesion-preventing plate itself. Countermeasures are being taken. However, the temperature history due to the increase in the input power cannot be eliminated even by those processes.

As a result, when a metal wiring film is formed using a metal target, if dust accumulates on the surface of the substrate, there is a problem in that the wiring becomes defective and the wiring becomes defective.
There is also a problem that the via hole becomes defective in shape. In semiconductors, recording media, etc., minute defects due to these dusts cause defective devices.

In particular, burying a via hole having a small opening diameter and a large aspect ratio is performed by IMP (Ionized).
Metal Sputter, SIS (Self I)
A process such as an animated sputter) is used. However, since IMP and SIS have a metal internal antenna inside the chamber, there is a problem in maintainability against deterioration of the antenna. Also, SIS
Since a positive electric potential is applied near the target to form a large current path, the problem of dust increase due to thermal history is inevitable.

Further, when the deposition preventive plate near the wafer stage on which the substrate is placed is electrically floated, the potential near the corner of the wafer stage changes, which changes the electric field and causes the corner of the wafer stage to change. Affects the plasma distribution near the area. Therefore, good plasma treatment cannot be performed on the peripheral portion of the substrate unless the film formation time is extended.

The present invention has been made based on these circumstances, and it is possible to fill a via hole having a high aspect ratio and a magnetron sputtering apparatus having a function of suppressing peeling dust from an adhesion preventing plate. And its purpose is to provide a way.

[0013]

According to the means of the invention of claim 1, a stage for mounting a target and a substrate spaced apart from the target inside the chamber, and a target of the target from the vicinity of the stage. In a sputtering apparatus provided with a deposition preventive plate arranged to protect the inner wall of the chamber up to the vicinity, the deposition preventive plate is divided into a plurality of between the stage and the target, at least, The deposition apparatus provided in the vicinity of the stage is provided with a controllable electric potential applied to the deposition apparatus.

According to the second aspect of the present invention,
The deposition preventive plate formed so that the applied potential can be controlled is formed so that a floating state, a grounded state, and a voltage applied state can be selected freely.

According to the means of the invention of claim 3,
In a sputtering method in which a substrate disposed apart from a target is sputtered in a chamber in which a plurality of deposition-inhibitory plates are formed, in the sputtering method, at least one of the plurality of deposition-inhibitory plates located closest to the substrate is protected. The sputtering method is characterized by controlling the electrical connection of the deposition plate.

According to the means of the invention of claim 4,
The control of the electrical connection of the deposition preventive plate is a sputtering method characterized in that the floating state, the grounding state, and the voltage application state are selectively controlled according to the progress of the sputtering process.

According to the means of the invention of claim 5,
The sputtering process is directed to the filling of via holes formed in the substrate, which is the above-described sputtering method.

[0018]

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 configuration diagram showing a configuration of a main part of the magnetron sputtering apparatus according to the present embodiment.

A flat plate-shaped target (cathode) 2 and a stage 3 which also serves as an electrode are arranged opposite to each other inside a chamber 1 which is a closed container. The substrate 4 formed by plasma processing is placed on the stage 3. A magnet 5 that forms magnetic lines of force is arranged on the back surface of the target 2. Most of the inside of the chamber 1 except the target 2 and the stage 3 is partitioned into double-walled shapes by the deposition-inhibitory plates 6a, 6b, and 6c. This attachment plate 6a, 6
b, 6c have three steps of upper, middle, and lower depending on the position inside the chamber 1, and the adhesion-preventing plate A6a, the adhesion-preventing plate B6b, and the adhesion-preventing plate C
6c is separated and configured.

A mass flow controller 7 for controlling the flow rate of Ar gas introduced to generate an electric discharge outside the chamber 1, a valve 8 for shutting off the introduction of gas, and a chamber 1
A pump 9 for evacuating the inside of the chamber to a high vacuum and a high voltage power source 11 for applying a high voltage to the target 2 are provided.

Regarding the electrical system connection, the DC power supply 12 is connected between the target 2 and the ground. On the other hand, the stage 3 is grounded via a blocking capacitor 13 and a high frequency power supply 14. As a result, the self-bias is formed on the substrate 4 so that the positive ions are easily attracted.

Both the deposition preventive plate A6a and the deposition preventive plate B6b are electrically grounded. On the other hand, the protective plate C6
c is grounded through a circuit in which the switch 18 and the DC power supply 17 are connected in series and the switch 18 is connected in parallel. The protection plate C6c turns on the switch 16 and the switch 18
By turning off, the bias potential is applied,
By turning off both the switches 16 and 18, a floating (floating potential) state can be controlled, and by turning off the switch 16 and turning on the switch 18, it is possible to perform control such that a ground state is achieved.

When positive ions are drawn into the deposition preventive plate C6c, the deposition preventive plate C6c is controlled to have a negative potential, and when positive ions are pushed back, the deposition preventive plate C6c is controlled to have a positive potential.

That is, in the magnetron sputtering device,
Due to the negative potential applied to the target 2, rare gas positive ions such as Ar are drawn into the target 2 and collide with them. With this collision, the atoms of the target 2 are sputtered and knocked out. Particles scattered in the atomic state behave approximately according to the cosine law. Some of the particles scattered in the atomic state are ionized by the collision of electrons or the like. The ionized sputtered particles and the rare gas positive ion particles such as Ar control the direction of the positive ion particles incident on the substrate 4.

The cause of film peeling of the film adhered to the adhesion-preventing plate C6c occurs when the film stress exceeds the critical point due to film shrinkage due to thermal history. The temperature at the time of film formation of the deposition preventive plate C6c becomes high because the velocity vector of the scattered particles is large and the particles collide at an angle close to vertical. Therefore, anti-adhesion plate C
The potential of 6c is controlled to suppress and reduce the current flowing through the plasma.

FIG. 2A is a timing chart of the control of the switches 16 and 18 with respect to the deposition preventive plate C6c, and FIG. 2B is a graph showing the temperature change of the deposition preventive plate C6c due to it.

The film forming process is roughly controlled in three modes.

As shown in FIG. 2A, the first mode is at the start of film formation, and in this first mode, the film thickness in the via hole is mainly increased. In this case, the switches 16 and 18 of the deposition-inhibiting plate C6c are turned off so that the film is deposited in an electrically floating state so that no current flows through the deposition-inhibiting plate C6c. Therefore, since there is no current flow at the temperature of the deposition-inhibiting plate C6c, as shown in FIG. 2B, the temperature of only collision energy between electrons and ions due to ambipolar diffusion (T1).
And avoids high temperature.

Next, the mode is changed to the second mode. The second mode is a mode for making the film thickness uniform. Therefore, the switch 18 is turned on (the switch 16 is turned off) during the film formation (for example, 50% or more of the entire time of the film formation process) to electrically ground the film. As a result, the temperature of the deposition-inhibiting plate C6c rises from (T1) and then becomes the ground potential, so that current flows and the deposition-inhibiting plate C6c rises to the temperature (T2). At the same time, the electric field in the vicinity of the substrate 4 changes, and the direction in which positive ions enter the substrate 4 changes to the direction of the chamber 1.

Next, the mode is changed to the third mode. This second mode is a mode for returning due to pushability. In this mode, the switch 18 is turned off and the switch 16 is turned on in the latter half of the film forming process, and the voltage is applied electrically. The deposition preventive plate C6c is brought into the vicinity of the floating floating potential, and the via hole of the substrate 4 is opened. Controls ion injection and improves embeddability. At this time, an electric current flows through the deposition prevention plate C6c, and the deposition protection plate C6c rises to the temperature (T3).

In these controls, each switch 16,
By optimizing the control of the on / off time of 18, it is possible to minimize the temperature rise of the deposition preventive plate C6c and enable filling of via holes with a small opening diameter.

In the Cu wiring technology based on the SIS process in which the temperature of the deposition preventive plate C6c is controlled in this manner, by applying a negative bias to the substrate 4, Cu ions are attracted to the substrate 4 side, and thereby, in the via hole. Coverage can be increased.

As described above, according to the present invention, it is possible to prevent the detachment of the film adhering to the deposition preventive plate. Therefore, good film formation can always be performed on the substrate.

[0034]

According to the present invention, it is possible to suppress the peeling dust from the deposition preventive plate when filling the via hole in the sputtering process, and it is possible to favorably form the film in the via hole and the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a main part of a magnetron sputtering apparatus of the present invention.

FIG. 2A is a timing chart of switch control for the deposition preventive plate, and FIG. 2B is a graph showing changes in the temperature of the deposition preventive plate.

FIG. 3 is a cross-sectional view showing the structure of a film forming chamber of a conventional magnetron sputtering apparatus.

[Explanation of symbols]

1 ... Chamber, 2 ... Target, 3 ... Wafer stage,
4 ... Substrate, 5 ... Magnet, 6a, 6b, 6c ... Protection plate, 16
… Switch, 17… DC power supply, 18… Switch

Claims (5)

[Claims] 1. A stage for mounting a target and a substrate arranged apart from the target inside the chamber, and an inner wall of the chamber between the vicinity of the stage and the vicinity of the target. In the sputtering device provided with the deposition preventive plate arranged, the deposition preventive plate is divided into a plurality of between the stage and the target,
At least, the anti-adhesion plate arranged near the stage,
A sputtering apparatus, wherein the potential applied to the deposition preventive plate is controllable. 2. The sputtering according to claim 1, wherein the deposition-inhibitory plate formed so that the applied potential can be controlled is formed so that a floating state, a grounding state, and a voltage application state can be selected. apparatus. 3. A sputtering method in which a substrate disposed apart from a target is subjected to a sputtering process inside a chamber in which a plurality of deposition-inhibitory plates are formed, at least the nearest of the plurality of deposition-inhibitory plates to the substrate. A method for sputtering, comprising controlling the electrical connection of the deposition-inhibitory plate located at. 4. The control of the electrical connection of the deposition preventive plate selectively controls a floating state, a grounding state and a voltage application state according to the progress of the sputtering process. Sputtering method. 5. The sputtering method according to claim 3, wherein the sputtering process is aimed at filling a via hole formed in the substrate.