JPS63169378A - Sputtering method - Google Patents

Abstract

PURPOSE:To deposit a film forming material capable of infiltrating into the minute stepped parts, grooves, and holes with a low bias voltage not causing the film defect such as bulging by impressing a negative bias voltage on the surface of a substrate to be treated in the title sputtering device. CONSTITUTION:The substrate 25 such as a semiconductor device and the target 5 on the film forming material are provided in a vacuum vessel 1 in opposition to each other, and gaseous Ar is introduced from a gas inlet 19. A target coil 6 and a substrate coil 14 are energized to generate magnetic fields in the directions opposite to each other, and a cusped magnetic field formed by the lines of magnetic force 26 is generated. A sputtering voltage is further impressed on a sputtering electrode 4 to generate high-density plasma 27 of the same shape as the lines of magnetic fore 26. A DC bias is impressed on the surface of the substrate 25 by a DC power source 22 or a high-frequency power is impressed on a substrate electrode 10 by a high-frequency power source 21 to induce a bias voltage on the surface of the substrate 25. Consequently, the surface of the substrate 25 is kept at a negative bias potential, high-density plasma is produced in the vicinity of the substrate by the cusped magnetic field, and a film infiltrating into the small stepped parts, grooves, and holes of the substrate surface is formed with a low bias voltage not causing film defects.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to thin film sputter deposition technology, and in particular to the application of a deposition material to fine steps, grooves, and holes on the surface of a substrate such as a semiconductor device. This relates to a sputtering method that provides relatively good adhesion.

[Conventional technology]

In the sputtering film forming technique, an attempt to increase the amount of flow flowing into the film to be formed by increasing the magnetic field applied to the plasma is described in, for example, Japanese Patent Laid-Open No. 60-221565. That is, by placing a magnetron sputter electrode and a substrate facing each other and applying a negative bias voltage to the substrate surface, some of the ions in the plasma generated on the magnetron sputter electrode flow into the substrate surface. , it has become a kind of bias sputtering device disease.

On the other hand, US Patent U8P3.325.594 describes a sputtering film forming technique using a cusp magnetic field.

That is, the spa 2'1 pole and the substrate to be film-formed are placed facing each other,
Two sets of electromagnets are used to form a cusp magnetic field between them to improve the plasma 1aWE and improve the film forming rate. In order to increase the film formation speed, K is a method using a cusp magnetic field, which is more effective than the sputtering film formation method using the cusp magnetic field, since the device configuration is simpler and the effect is greater than the sputtering film formation method that is assisted by the cusp magnetic field. The use of was not considered.

[Problem that the invention seeks to solve]

Bias sputtering is a process in which a film material is deposited on a substrate, and at the same time a negative bias voltage is applied to the substrate surface, ions in the plasma are incident, and the energy of the ions is imparted to the forming particles, causing the particles to move on the surface. By increasing the strength, it is possible to improve the ability to go around holes. Therefore, it is important to increase the amount of ions that enter the substrate, and possible ways to do this include increasing the plasma density on the substrate and increasing the ion current flowing into the substrate, or increasing the bias voltage. .

Since conventional magnetron sputtering electrodes confine plasma to the sputter facing the substrate, simply applying a bias voltage to the substrate surface does not sufficiently increase the plasma density on the substrate. In our preliminary experiment, when the bias voltage is -1oov, the plasma density on the substrate is about 2x, Dtam-1, and the ion current flowing into this n-substrate is about α5 A/φ125,
In addition, the film-forming material (An
) was not sufficiently frequent.

On the other hand, it is known that increasing the bias voltage increases the amount of Ar gas occluded in the sputtered film.

From our preliminary experiments, we have found that post-sputter annealing causes voids and blisters to occur in sputtered films formed at a high bias pressure, and that the lower limit for this occurrence is 140 V, [degrees].

The purpose of the present invention is to provide a sputtering method that improves the ion current flowing into a substrate in order to uniformly adhere fine steps, grooves, or large-scale deposition materials with a low bias voltage that does not cause film defects such as voids and blisters. Our goal is to provide the following.

Another object of the present invention is to provide a sputtering method that can control the energy of ions entering the substrate while keeping the amount of ions flowing into the substrate substantially constant by controlling the bias voltage.

[Means for solving problems]

The above object is achieved by combining plasma densification using a Kags magnetic field and bias sputtering that applies a bias to the substrate side electrode.

[Effect]

A sputter electrode and a substrate electrode are placed facing each other.

By forming a cusp magnetic field in between, high-density plasma is generated from the surface of the sputtering electrode to near the surface of the substrate. Furthermore, applying a negative bias voltage to the substrate surface K
Therefore, high-density ions in the plasma near the substrate surface are drawn into the substrate at a low bias voltage that does not cause film defects, and the ion current flowing into the substrate is improved. As a result, the mobility of the sputtered particles adhering to the substrate surface is improved,
Specifically, the film material adhering to the upper corner of the step #1 on the substrate surface and the corner of the hole entrance is sputtered to form the lower step and the groove.

Bed adheres to the bottom of the hole. Therefore, it is possible to improve the distribution of sputtered material to steps, gaps, and holes without causing film defects.

Furthermore, since the bias voltage can be set independently of the generation of high-density plasma, the ion energy incident on the substrate can be controlled while the ion current flowing into the substrate is kept approximately constant.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

First, the configuration of this embodiment will be described.

A sputter electrode 4 is attached to an opening 2K at the top of the vacuum container 1 via an insulator 3. On the vacuum chamber side of the sputter electrode 4 is a target 5 made of sputtering material. The atmosphere Ill has a target coil 6 and a yaw 7 for generating a magnetic field, and furthermore, on the outer periphery of the target 5, there is a distance between the target and the target so as not to cause an electric discharge.
Seven nodes 28 are attached to the vacuum vessel 1 via insulators 8.

The yoke 7 is used to strengthen the leakage magnetic flux density generated by the target coil 6.

The potential of the anode 28 can be set to floating,
Wired to earth or any positive or negative potential.

There is a substrate electrode 10 on which a substrate 25 is placed in the opening 9 at the bottom of the vacuum container 1. Around the substrate electrode 10, an insulator 11 having a vacuum sealing function is placed between the target 5 and the surface of the substrate electrode 100. A vertically movable substrate holder 12 is further fixedly attached to a shield 14 or to the vacuum container 1 via an insulator 13 having a vacuum sealing function around the substrate holder 12.

Further, the other opening 15 at the bottom of the vacuum container 1 has a true 9! A substrate coil 17 is installed in a coil container 16 that is attached to the valley device 1 in a vacuum-sealed state.

The inside of the vacuum container 1 is evacuated by the exhaust means 18, and gas is introduced by the gas introduction means 19, so that the pressure is maintained at approximately 10 Torr.

Sputter electrode 4, substrate electrode IQ, substrate holder 12. A sputter power supply 2 is connected to the target coil 6 and the substrate coil 17, respectively.
0. High frequency power source 21, DC source 22, target coil power source 23. The substrate coil power supply 24 and the vacuum vessel 1 are connected to ground.

When applying a DC'9 bias voltage to the substrate surface, the DC power supply 22 is not required (when the high frequency power supply 21 applies a high frequency bias voltage), and when applying a high frequency bias voltage -, the high frequency power supply 22 is not required. The presser foot 12 is made of an insulating material to shield high frequency plasma.

The target coil 6 and the target coil power supply 23 and the substrate coil 17 and the substrate coil power supply 24 are not limited to these electromagnets, but permanent magnets that generate a magnetic field equivalent to the electromagnets may be used.

The substrate 25 to be subjected to the sputtering film forming process is placed on the substrate holder 1.
On the target 5 side, spaced apart from the substrate electrode 10,
After being placed on the substrate electrode 10 by a transport mechanism (not shown), it is held by a substrate presser 12.

This embodiment with the above configuration operates as follows.

A substrate 25 is conveyed from an inlet (not shown) of the vacuum container 10, placed on the substrate electrode 10, and then fixed by a substrate holder 12. After the vacuum chamber 1 is evacuated to a high vacuum by the exhaust means 15, Ar gas is introduced from the gas introduction means 19i' (to maintain a predetermined sputtering pressure). When a coil current is applied to the substrate coil 14 and the substrate coil 14 so as to generate mutually opposite magnetic fields, a cusp magnetic field having the shape of the magnetic lines of force 26 shown in FIG. When applied, a high-density plasma 27 having the same shape as the magnetic field lines 26 is generated.
It occurs from the surface of the target 50 to near the surface of the substrate 25.

Press the board holder 12 from the straight L electric TM22 and press the board 250.
By applying a DC bias to the surface or applying high frequency power from the high frequency power source 21 to the substrate electrode 10 to further generate high frequency plasma on the substrate 25 and inducing a bias voltage on the surface of the substrate 25, the substrate surface is A negative bias potential is maintained to direct ions in the plasma 27 to the substrate 25.
It flows upward.

As described above, in this embodiment, high-density plasma can be generated up to the vicinity of the substrate 25 by the cusp magnetic field.
Apply the sputtered material to the grooves and holes (you can obtain enough ion current to form a film).

An example of measuring the inflow current in this embodiment is shown in FIG.

Figure 2 shows substrate bias voltage: -100V, substrate ζ
14: So easy data between targets. When the ratio of substrate coil current/target coil current is small, the center diameter of the plasma ring is larger than the diameter of the substrate.

By increasing this ratio, the center diameter of the plasma ring can be made equal to the diameter of the substrate. And about 5 times more lX than conventional technology
A plasma density of 10"Cm and a substrate inflow current (within ψ125) of about twice as much as 1.1 people were obtained.

The AI throwing method when depositing Aj into microholes by bias sputtering by changing the ion current flowing into the substrate is 88M.
The results determined from the photos are shown in Table 1.
1 sm, and the film formation rate was 1200 Il/rn i n ).

The ○ mark indicates that the AJ adhesion to the side surface of the hole is approximately 40 mm or more of the film thickness at the flat part. In this way, the ionic current is 1A//
It was confirmed that φ125 is sufficient for one turn into a hole of 1.0 Jrn.

Table M1 shows the relationship between the bias voltage and the inflow current in this embodiment as the third factor (the vertical axis is weighted against 1). Similar to Figure 2,
The distance between the substrate and the target is 5011B. Even if the bias voltage is changed from -100V to -40V, the inflow ion current remains almost constant. That is, the total amount of ion energy incident on the substrate can be controlled over a wide range while keeping the ion current flowing into the substrate substantially constant.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a high flow of ions flowing into the substrate with a low bias voltage, so the Svantha film can be adhered to the step, groove, and hole without causing film defects such as voids and blisters. . Also, since the substrate bias voltage can be set independently of high-density plasma generation,
The ion energy can be controlled while the amount of ions flowing into the substrate is kept almost constant, improving latitude in film quality control.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, FIG. 2 is a diagram showing substrate inflow current data in an embodiment of the present invention, and FIG. 3 is a diagram showing bias voltage and inflow current in an embodiment of the present invention. It is a figure showing data. 1... Vacuum container, 2... Opening, 3... Insulator, 4
...Sputter electrode, s...Target, 6...Target coil, 7°...Yoke, 8...Insulator, 9
゛...Opening, 10...Substrate electrode, 11...Insulator,
12... Substrate holder, 13... Insulator, 14... Shield, 15... Opening, 16... Coil container, 17
. . . Substrate coil, 18 . . . Exhaust means, 19 . . . Gas introduction means, 20 . ... board coil power supply, 25... board,
26...Magnetic field lines, 27...Plasma, 28...Anode.

Claims (1)

[Claims] 1. In a sputtering method in which a material to be sputtered placed on a sputtering electrode to which a voltage is applied is sputtered onto a sample substrate facing each other at a predetermined distance, a cusp magnetic field is applied between the target and the substrate. By forming a high-density plasma, and applying a bias voltage to the substrate surface, ions are incident on the substrate surface, and the sputtering material ejected from the target is attached to the substrate to form a film. Characteristic sputtering method. 2. The sputtering method according to claim 1, characterized in that a DC voltage is applied to the surface of the substrate. 3. In the sputtering method according to claim 1, applying a high frequency voltage to a substrate electrode on which the substrate is placed,
A sputtering method characterized by inducing a negative DC bias voltage on the surface side of a substrate.