JP2001152396A - Semiconductor manufacturing apparatus, and semiconductor manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing apparatus, and a semiconductor manufacturing method in which the power is supplied from an outer peripheral part of a semiconductor wafer using an electroplating method to form a plating layer on the wafer, and the variance in film thickness caused by non-uniform contact of the semiconductor wafer with a power supply electrode can be reduced. SOLUTION: When the power is supplied onto the semiconductor wafer from the outer peripheral part of the wafer, the power is supplied to the semiconductor wafer 2 using a plurality of power supply electrodes 801-808 as shown in Fig. 1, and the current in the power supply electrodes 801-808 is kept at a preset value by constant current sources 901-908. Even when the contact of a contact surface of the power supply electrodes with the wafer is non-uniform, the current distribution along the peripheral direction of the wafer is kept uniform, and the distribution of the film thickness on the plating layer becomes uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing apparatus and a semiconductor manufacturing method for forming wiring on a semiconductor wafer by electroplating, and more particularly to a semiconductor manufacturing apparatus and a semiconductor manufacturing method capable of forming a uniform plating film.

[0002]

2. Description of the Related Art When wiring is formed on a semiconductor wafer by electroplating using a semiconductor wafer surface as a surface to be plated, if the plating film thickness deposited on the wafer varies depending on the portion on the wafer, the plating film is formed after the electroplating. During the chemical mechanical polishing process, there are problems such as excessive polishing and unremoved portions, variation in wiring resistance, and different element characteristics depending on the portion on the wafer. In order to make the plating film thickness uniform, it is necessary to make the current density flowing into the surface to be plated as uniform as possible. A portion suitable for supplying power to the semiconductor wafer is very limited, such as the outer peripheral portion of the wafer. Usually, a power supply electrode on a ring is brought into contact with the outer peripheral portion of the wafer to supply power.
A conductive thin film (seed layer) is provided on the surface of the semiconductor wafer to be plated by sputtering or the like before electroplating, but the thickness of the seed layer is as small as about 0.1 μm or less and the resistance is high. Contact resistance between the substrate and the surface to be plated is large. In addition, since the power supply electrode material is limited in order to prevent impurities from entering the semiconductor wafer from the power supply electrode, it is necessary to use a power supply electrode material in which it is difficult to form a flat contact surface with the semiconductor wafer. Many. For this reason, when plating a semiconductor wafer, the contact between the surface to be plated and the power supply electrode tends to be uneven.

[0003] If the contact between the surface to be plated and the power supply electrode becomes non-uniform, a current easily flows to a portion having good contact, so that the film thickness in the direction connecting the center of the wafer and the portion having good contact increases.
Conversely, the film thickness becomes thinner in the direction toward poor contact. Thus, the film thickness varies in the circumferential direction of the wafer due to the uneven contact. Such variation in film thickness due to non-uniform contact becomes more remarkable when the resistance of the seed layer and the power supply electrode is large.

The following proposals have been made to make the plating film thickness uniform.

In Japanese Patent Application Laid-Open No. 9-53198, power is supplied using a plurality of power supply electrodes, and the power supply electrodes are arranged so as to form a pair with the center of the surface to be plated interposed therebetween, or are arranged at equal intervals on the outer peripheral portion. Alternatively, the power supply electrodes are continuously arranged in a ring shape over the entire outer peripheral portion, so that a uniform plating film can be formed.
However, no countermeasures are taken against the case where the contact is non-uniform, and when the contact between each power supply electrode and the surface to be plated is non-uniform, the current at each power supply electrode becomes non-uniform and the film thickness varies.

In Japanese Patent Application Laid-Open No. 10-13089, a current density sensor and a plurality of current shield plates are provided near the surface to be plated, and the hole diameter of the shield plate is adjusted so that the current flowing from the plating solution to the surface to be plated is uniform. By controlling online,
It enables uniform electroplating. However, since the film thickness formed on the semiconductor wafer is as thin as 1 to 2 μm or less, and the film formation rate is as high as 100 nm / min or more, the optimum shield plate hole diameter and shield plate position are searched and the hole diameter and position are changed. The plating process is completed within the time period. Also,
Since a device that automatically changes the aperture ratio of the current shielding plate and the position of the shielding plate according to the measurement result of the current density is required, the cost of the device increases.

[0007]

SUMMARY OF THE INVENTION According to the present invention, in forming wiring on a semiconductor wafer by electroplating, the variation in plating film thickness caused by uneven contact between the semiconductor wafer surface and the power supply electrode on the semiconductor wafer is reduced. It is an object of the present invention to provide a semiconductor manufacturing apparatus and a semiconductor manufacturing method that can perform the method.

[0008]

In order to solve the above-mentioned problems, in the present invention, a plurality of power supply electrodes are provided on an outer peripheral portion of a semiconductor wafer, and a current adjusting device is provided so that a current value of each power supply electrode becomes a set value. Thus, there is provided a semiconductor manufacturing apparatus capable of reducing variations in plating film thickness due to uneven contact between the semiconductor wafer surface and the power supply electrode. Furthermore, there is provided a semiconductor manufacturing apparatus capable of measuring the contact resistance between each power supply electrode and a wafer, and arranging the wafer so that the contact of the power supply electrode is uniform, thereby performing more reliable plating. You.

In addition, before the electroplating, the seed layer thickness at the contact portion of the outer peripheral portion of the wafer with the power supply electrode is increased to improve the uniformity of contact between the power supply electrode and the wafer, thereby performing the electroplating. A semiconductor manufacturing method capable of forming a thickness is provided.

[0010]

FIG. 1 is a schematic diagram of a semiconductor manufacturing apparatus used in this embodiment. This apparatus forms a plating film on a semiconductor wafer by electroplating. The apparatus includes a plating tank 5 surrounded by a cylindrical insulating wall 3 and an anode electrode 1 provided at a lower opening of the insulating wall 3, and a power supply electrode fixture 4 and power supply electrodes 801 to 808 are installed at an upper port. Have been.
When performing electroplating, the semiconductor wafer 2 is mounted on the power supply electrode fixture 4 and the power supply electrodes 801 to 808.
Power supply electrodes 801-8 are supplied by constant current power supplies 901-909.
08, power is supplied to the outer peripheral portion of the semiconductor wafer 2, and a plating film is formed. The insulating wall 3 has a length of 150 mm and an inner diameter of 180 mm. The plating tank 5 is filled with a plating solution. A plating solution inlet 6 is provided at the center of the circular anode electrode 1. The plating solution circulates through the plating solution inlet 6, the plating tank 5, and the plating solution outlet 7, and is sufficiently stirred. A feature of the present invention in the apparatus of FIG. 1 is that power is supplied to the semiconductor wafer 2 using a plurality of power supply electrodes 801 to 808 and constant current power supplies 901 to 909.

In order to explain the effects of the present invention, a method of supplying power to a normal semiconductor wafer and problems will be described. In a normal case, power is supplied to the semiconductor wafer 2 as shown in FIG. FIG. 2 shows only the power supply portion to the wafer on the upper side of the plating apparatus. The power supply to the semiconductor wafer 2 is performed by the annular power supply electrode 8.

FIGS. 3 (A) and 3 (B) show the dependence of the film thickness at 60 mm from the center of the wafer on the wafer circumferential direction when copper is formed by electroplating using the annular feeding electrode 8 of FIG. It is an experiment result of sex. In FIG. 4B, the semiconductor wafer 2 is strongly pressed against the annular power supply electrode 8 as compared with the condition of FIG. 4A, so that the contact uniformity between the semiconductor wafer 2 and the annular power supply electrode 8 is improved. ing. The conditions for forming copper by electroplating are as follows.

Before the electroplating, a copper film is deposited to a thickness of about 0.1 μm on the semiconductor wafer by sputtering to form a seed layer. The average current density was set to 100 A / m ² using a copper sulfate plating solution. Electroplating is 3.0
Then, a copper film is deposited on the semiconductor wafer by about 1 μm. The semiconductor wafer 2 has a radius of 100 mm,
It is in contact with the annular power supply electrode 90 mm outside the center of the wafer.

From FIGS. 3A and 3B, it can be seen that if the contact between the wafer and the power supply electrode is poor, the variation in the film thickness in the circumferential direction increases. The film thickness distribution is determined by the current density distribution on the wafer. That is, when the annular power supply electrode shown in FIG. 2 is used, current concentrates in a direction connecting the point of good contact between the annular power supply electrode and the wafer from the center of the wafer, and the film thickness increases. The thickness decreases. When the contact property is improved, the film thickness distribution approaches uniformity.

In order to improve the uniformity of contact between the wafer and the power supply electrode, a measure for forcibly pressing the semiconductor wafer against the power supply electrode can be considered. However, in this method, excessive stress is applied to the wafer, and elements formed on the wafer are destroyed. Therefore, as shown in FIG. 1, the power supply to the wafer (cathode electrode) 2 is divided like the power supply electrodes 801 to 808, and the current value on each power supply electrode is
The value is fixed to the set value by ９０908. Thus, it is possible to make the current flowing in each circumferential direction of the wafer uniform, and to reduce the variation in the film thickness. When the power supply electrodes are arranged at equal intervals in the outer peripheral portion, the current value flowing through each power supply electrode is (average current density flowing through the wafer × area of the surface to be plated).
/ Depends on the number of power supply electrodes. It is desirable that the number of power supply electrodes and current regulating devices be large.

Further, the following means have been invented in order to ensure reliable contact uniformity. When the semiconductor wafer is installed on the power supply unit, the resistance between the adjacent power supply electrodes 801 to 808 is measured by the constant current power supply 10 and the voltmeter 11 as shown in FIG. From the resistance measurement, the level of the contact resistance between each power supply electrode and the wafer can be known. The semiconductor wafer is placed in such a manner that the portion having a high contact resistance is pressed against the power supply electrode so that excessive stress is not applied to the wafer, and the portion where the contact resistance is low is weakened so that the contact resistance becomes uniform. By making the contact resistance between the power supply electrode and the wafer uniform, the film thickness distribution tends to be more uniform. It is desirable that the contact resistance between each power supply electrode and the semiconductor wafer can be directly measured.

When electroplating a wafer having a small diameter, it is necessary to shorten the distance between the power supply electrode and the center of the wafer. However, if a mechanism for changing the distance from the center of the wafer is added to the power supply electrode, it is difficult to stabilize the power supply electrode fixture because the fixture is unstable when fixed to the apparatus main body. Therefore, it becomes more difficult to ensure uniform contact between the wafer and the power supply electrode. In the present embodiment, as shown in FIG. 5, the power supply electrode fixture and the power supply electrode are replaced with ones that match the diameter of the wafer, thereby performing electroplating on a wafer having a small diameter. Thereby, even if the contact unevenness between the wafer and the power supply electrode due to the wobble of the fixture or the like is further increased, a uniform current distribution can be obtained by the current adjusting device, and the variation in the film thickness is reduced.

In electroplating a semiconductor wafer,
There is a problem of non-uniform film thickness distribution due to non-uniform contact between the wafer outer peripheral portion and the power supply electrode. As one means for solving this problem, the electroplating method shown in FIG. 6 is also effective. FIG. 6 is a view of a cross section of a semiconductor wafer. Portions 121 and 12 in contact with power supply electrodes on seed layer 13 deposited on semiconductor wafer 2
The copper film 131, 132 is formed on the power supply part by sputtering or the like using the mask 14 other than the mask 2. Thereby, the conductive film in the power supply portion becomes particularly thick, and the contact between the power supply electrode and the wafer is improved.

[0019]

According to the present invention, when a plating film is formed on a semiconductor wafer by electroplating, there is no variation in film thickness due to uneven contact between the outer peripheral portion of the wafer and the power supply electrode, and a uniform plating film can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a plating apparatus.

FIG. 2 is an enlarged view of a power supply unit of a plating apparatus using an annular power supply electrode.

3 is a film thickness distribution diagram along a wafer radial direction when the power supply electrode of FIG. 2 is used, and FIG. 3B shows a state in which the semiconductor wafer is strongly pressed against the power supply electrode as compared with FIG. FIG.

FIG. 4 is a diagram showing a resistance measuring device between power supply electrodes in the plating apparatus of FIG. 1;

FIG. 5 is an enlarged view of a power supply unit of the plating apparatus in FIG. 6 in which a distance from a center of the wafer to a power supply electrode is reduced.

FIG. 6 is an explanatory view of a seed layer forming process in which a contact portion with a power supply electrode on the outer peripheral portion of the wafer has a large film thickness.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Anode electrode, 2 ... Semiconductor wafer, 3 ... Insulating wall, 4
... Power supply electrode fixture, 5 ... Plating tank, 6 ... Plating solution inlet,
7 ... plating solution outlet, 8 ... annular feeding electrode, 801-80
Reference numeral 8: power supply electrode, 9: constant current power supply, 901 to 909: constant current power supply, 10: constant current power supply, 11: voltmeter, 121.1
22 ... parts in contact with the power supply electrodes, 13, 131, 132 ...
Conductive film deposited before electroplating, 14 mask.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Fukada 6-chome, Shinmachi 6-chome, Ome-shi, Tokyo F-term in the Device Development Center, Hitachi, Ltd. 4K024 BB12 CB04 CB08 CB26 GA16

Claims (5)

[Claims] In a semiconductor manufacturing apparatus for forming a plating film by supplying power from an outer peripheral portion of a semiconductor wafer using a semiconductor wafer as a surface to be plated, a plurality of power supply electrodes are provided on an outer peripheral portion, and a current value on each of the power supply electrodes is provided. A semiconductor manufacturing apparatus characterized in that an electroplating film is formed by power supply by a current adjusting device capable of adjusting a current. 2. In a semiconductor manufacturing apparatus for forming an electroplating film by supplying power from an outer peripheral portion of a semiconductor wafer using a semiconductor wafer as a surface to be plated, a plurality of power supply electrodes are provided on an outer peripheral portion. And a contact resistance measuring device. 3. The semiconductor manufacturing apparatus according to claim 1, wherein the electroplating film is formed by supplying power from an outer peripheral portion of the semiconductor wafer using the semiconductor wafer as a surface to be plated. 4. The semiconductor manufacturing apparatus according to claim 1, further comprising a mechanism for adjusting a distance from a center of the wafer to a plurality of power supply electrodes provided on an outer peripheral portion. . 5. In a semiconductor manufacturing method in which a semiconductor wafer is used as a surface to be plated and an electroplating film is formed by power supply from an outer peripheral portion of the semiconductor wafer, when a conductive material layer is deposited on the semiconductor wafer before electroplating, A semiconductor manufacturing method in which a conductive material layer is deposited so as to be thick at a portion on a periphery of a semiconductor wafer which is in contact with a power supply electrode.