JPS6179768A - Sputtering method - Google Patents

Abstract

PURPOSE:To deposit a target material over the entire surface of a material to be treated to a uniform thickness by forming the surface of the target facing the material to be treated into a specific shape in the stage of sputtering the target material onto the surface of the material to be treated in a low-pressure Ar atmosphere. CONSTITUTION:The metallic target 5 such as Al and the material 1 to be treated are positioned in parallel so as to face each other in the gaseous Ar atmosphere under about 10<-3> Toor and electric discharge is generated between the target as a cathode and an anode to sputter and deposit metal such as Al with is the target material on the adherent surface 1a of the material 1 to be treated. The target 5 is separated to the central target 5 and the peripheral target 6 and the radiating surface 6a of the peripheral target 6 is made into the shape inclined inward with respect to the radiating surface 5a of the central target 5. Even if recesses 3 exist in the central and peripheral parts of the material 1, the target metal on the inside surface thereof is formed always to the uniform deposition thicknesses T1-T4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sputtering method, and in particular, to a sputtering method that sputters a sputtering method to a surface of an object to be processed, such as a wafer for manufacturing a semiconductor chip, which is a main component of a semiconductor device. For example, it relates to improvements in sputtering methods for depositing materials for forming electrodes.

A semiconductor chip generally has semiconductor elements such as transistors formed on a semiconductor wafer, and its reliability depends not only on the quality of the semiconductor element itself, but also on the quality of the wiring from the semiconductor element. It has a big impact.

This wiring is usually achieved by forming a contact hole in an insulating film covering the semiconductor element, depositing an electrode material such as aluminum on the contact hole by sputtering, and patterning this deposited film to form an electrode and a contact hole. This is done by forming wiring.

At this time, the quality of the wiring lead-out depends on the quality of the coverage in the contact hole portion of the deposited film, and it is desirable to propose a sputtering method that improves the coverage, which is a problem especially in the peripheral area of large wafers. It is rare.

[Conventional technology]

FIG. 2(A) is a side sectional view showing the main part configuration of a conventional general sputtering method, where l is an object to be processed such as a semiconductor wafer to which a deposited film is applied, and la is an object to be processed 1. The deposition surface 2 is a target formed of a deposition film material, and 2a is a radiation surface of the target 2 that emits the material.

The deposition film is formed by sputtering at approximately 0-3 Torr.
The object to be processed 1 and the target 2 are placed in an argon atmosphere of about
The deposited film material is radiated by arranging the deposited surface 1a and the radiation surface 2a so that their centers are parallel to each other and facing each other, and by using the target 2 as a cathode and discharging between it and an anode (not shown). Surface 2a・ radiates from surface 1
It is made by attaching it to a.

At this time, with respect to the size (for example, diameter) of the object to be processed 1,
It is known from experience that when the size of the target 2 is increased by about 1.5 times, the thickness of the deposited film formed on the deposited surface 1a becomes approximately uniform over the entire surface.

[Problem that the invention seeks to solve]

However, as in the case where the above-mentioned contact hole is provided, as shown in FIG.
-1), (B-2) As shown in the diagram (if there is a depression 3,
The thickness of the deposited film 4 is not uniform in the depression 3 portion.

That is, Figure (B-1) shows the case where the recess 3 is located at the center of the adherend surface 1a, and Figure (B-2) shows the case where the recess 3 is located at the periphery of the adherend surface (in the figure,
The left side shows the center side and the right side shows the edge side. In Figure (3-1), the thicknesses T1 and T2 of the deposited film 4 at the shoulder part of the depression 3 are the same, but in Figure (B In -2), the thicknesses T3 and T4 of the deposited film 4 at the shoulder portion of the depression 3 are different, and T4 on the edge side of the deposited surface 1a is thinner. This tendency becomes more noticeable as the object to be processed 1 becomes larger.

For example, a large wafer (approximately 150 fl in diameter) with a steel contact hole approximately 1.5 μm square in size and approximately 1 μm deep (
When aluminum is spun onto the wafer (6) so that the thickness T is approximately 1 μm, the thicknesses Tl to T3 are equal to the thickness T.
However, the thickness T4 is extremely thin, being 172 or less of the thickness T3.

This poses a problem, for example, in the wiring of a semiconductor chip when the wafer is thick (if the wafer is thick, the coverage of contact holes in the wafer periphery is poor, leading to a risk of disconnection in that area).

[Means for solving problems]

The above-mentioned problems ↓ can be solved by the sputtering method of the present invention, which uses targets separated into a central part and a peripheral part to sputter a target material onto an object to be processed.

According to the present invention, the radiation surfaces of the peripheral targets (7) are inclined inward with respect to the radiation surfaces of the central target, and the attachment surface of the object to be processed is aligned with the radiation surface of the central target. It is better to have them face each other in parallel.

(Function) In the conventional method, the reason why the coverage of the deposited film is poor in the depressions in the periphery of the deposition surface of the object to be treated is because of the shape of the target. This is thought to be due to the low radiation density in the direction.

Therefore, by separating the target into a central part and a peripheral part, and making the radiation surface of the peripheral part as described above, for example, to make the radiation density uniform depending on the direction of the adhered material, the problem of poor coverage can be improved. As a result, it becomes possible to reduce the risk of disconnection occurring at the contact hole portion, for example, in leading out the wiring of a semiconductor chip.

[Example] An example of the present invention will be described below with reference to the drawings. The same reference numerals indicate the same objects throughout the figures.

Figure 1 (A)! Figures 1 (B-1) and (B
-2) is a side sectional view showing an example of a film adhesion situation according to the example.

FIG. 1(A) is a diagram corresponding to FIG. 2(A), and is a diagram corresponding to FIG.
In the method shown in Figure (A), the target 2 is replaced by a central target 5 and a peripheral target 6, which are separated into a central part and a peripheral part.

The central target 5 has a diameter of approximately 100 m and its radiation surface 5a.
faces the adhering surface 1a of the object to be processed l, similar to the conventional radiation surface 2a. The peripheral target 6 has a radiation surface 6a in the shape of a truncated cone with an inner diameter of about 130 mm and an outer diameter of 250 mm.
The inclination angle α of the radiation surface 6a with respect to the radiation surface 5a is about 40 degrees.

The inventor of the present application has identified a central target 5 and a peripheral target 6.
The above-mentioned target in combination with
Adhesion surface 1 of a large wafer (6P wafer) with a diameter of approximately 150 m and having contact holes of m square and depth of approximately 1 μm.
a was placed at a position approximately 70 cages away from the radiation surface 5a, and aluminum was sputtered to a thickness T of approximately 1 μm.

The results are as shown in Figure 1 (B-1) and (B-2) corresponding to Figure 2 (B-1) and (B-2).
The thicknesses T1 to T4 of the deposited IPJ 4 at the shoulder portions were all about 40% of the thickness T, and it was possible to improve the coverage that was conventionally poor in the depressions 3 in the peripheral portions.

Furthermore, the applicant has developed a large wafer (8 tm) with a diameter of about 200 tm
! It has also been confirmed that it is possible to obtain generally good results using the above target, up to and including wafers.

〔Effect of the invention〕

As explained above, according to the sputtering method of the present invention, it is possible to suppress the deterioration of the coverage of the depressions in the periphery of the adhered surface as the object to be processed increases in size. In the manufacture of semiconductor chips, the present invention has the effect of reducing the risk of disconnection at contact holes for leading out wiring in the periphery of large wafers, and making it possible to increase the size of acid wafers.

[Brief explanation of drawings]

In the drawings, FIG. 1(A) is a side view (, 1IIJ 1) showing the main part configuration of an embodiment of the sputtering method according to the present invention, and FIG.
-1) and (B-2) are side cross-sectional views showing an example of the film deposition situation according to the embodiment, and Figure 2 (A) is a side cross-sectional view showing the main part configuration of a conventional general sputtering method. Figures 2 (B-1) and 2 (B-2) are side sectional views showing an example of the state of film deposition by this method. In addition, in the figure, ■ is the object to be processed, 1a is the adherend surface, 2 is the target, 2a is the radiation surface, 3 is the depression,
4 is a deposited film, 5 is a central target, 5a is its deposited surface, 6 is a peripheral target, 6a is its deposited surface, T, Tl
~T4 represents the thickness, and α represents the inclination angle, respectively. Figure 2 (A)

Claims (2)

[Claims] (1) A sputtering method characterized in that a target material is sputtered onto an object to be processed using a target separated into a central part and a peripheral part. (2) The radiation surface of the peripheral target is inclined inward with respect to the radiation surface of the central target, and the adhering surface of the object to be processed is opposed parallel to the radiation surface of the central target. A sputtering method according to claim 1, characterized in that: