JPH01132762A - Method and device for sputtering - Google Patents

Abstract

PURPOSE:To prevent the camber of a semiconductor wafer after formation of sputtered films by sticking constituting atoms of the same kind simultaneously under the same conditions to both faces of the semiconductor wafer. CONSTITUTION:The semiconductor wafer 3 is grasped by fixing means 10, 10' in a vacuum chamber 1 so that the position of the wafer 3 is fixed and the electrical conduction thereof is assured. Two pieces of targets 11 are disposed to face each other on both sides of the wafer 3 in parallel in the positions equidisant on both sides and respectively two sets of magnet systems 12 are disposed in proximity to the respective rear faces of the targets 1 in such a positional relation where the magnet systems repulse magnetically to each other. The metal atoms of the targets 11 stick independently on both faces of the wafer 3 as a result of the sputtering. Since the films are formed under the same conditions for both faces, the internal stresses generated in the films are the same on both faces. The generation of the camber in the water 3 after the film formation is, therefore, obviated.

Description

[Detailed Description of the Invention] [Summary] Regarding a sputtering method for attaching constituent atoms of a target electrode to the surface of a semiconductor wafer, the target electrode and the semiconductor wafer are attached in a vacuum atmosphere of an inert gas with the aim of suppressing warping of the semiconductor wafer. In the sputtering method, the constituent atoms of the target electrode are attached to the surface of the semiconductor wafer by applying a high voltage between the two sides, and the constituent atoms of the same type are attached simultaneously and under the same conditions to both sides of the semiconductor wafer, which is held with both sides exposed. Configure.

[Industrial application field]

The present invention relates to a sputtering apparatus for attaching atoms constituting a target electrode to the surface of a semiconductor wafer, and more particularly to a sputtering apparatus designed to suppress warpage of the semiconductor wafer.

In general, when metal atoms such as tungsten (-) or aluminum (A/) are attached to one side of the semiconductor wafer using the normal sputtering method that forms a film on one side of the semiconductor wafer, tungsten (-) or aluminum (
Plasma ions of an inert gas such as argon gas are collided with the surface of a target electrode made of a metal to be deposited, and the energy is used to knock out metal atoms from the surface of the target electrode, thereby depositing one side of the semiconductor wafer. A film of the metal atoms is formed on the metal atoms.

In this case, the coating formed on one side of the semiconductor wafer is not necessarily uniform, and the coating itself has some inherent stress such as tension or compression. This causes warpage in the subsequent semiconductor wafer.

Therefore, in order to minimize the warpage of the wafer, conventionally the sputtering process was carried out by adjusting the current and voltage applied to the target electrode, the pressure of argon gas, etc. to optimal conditions set in advance, thereby relieving the stress of the film itself. I'm trying.

However, as the patterns on semiconductor wafers become finer and the wafer size becomes larger, slight warping of the wafer can no longer be ignored, and some metals, especially tungsten (alpha), It is difficult to control the stress inherent in the film by controlling current and voltage, argon gas pressure, etc., and the warping that occurs on the wafer after the film is formed often becomes large, so a solution to this problem is desired.

[Conventional technology]

FIG. 2 is a diagram showing an example of the configuration of the main parts of a conventional sputtering apparatus.

In the figure, the vacuum chamber l is 10-3 to 10-3 by the vacuum pump 2.
A degree of vacuum of about 1 O-ITorr is maintained, and the inside of the vacuum chamber 1 is filled with argon gas sent from the pipe 1a to a preset pressure.

Further, a semiconductor wafer 3 having a thickness of about 500 to 600 μm is placed on a base 4 electrically grounded to maintain electrical continuity so that the surface on which the film is formed is exposed.

The target 5 is made of tungsten, which is the same material as the required tungsten film to be formed on the semiconductor wafer 3, and is disposed in parallel and facing the semiconductor wafer 3 at a position corresponding to the target. In terms of potential, the external power source 6 is configured to have a negative potential with respect to the base 4 and, in turn, the semiconductor wafer 3.

In addition, two sets of magnet systems 7 are installed adjacent to the back surface of the target 5.
are arranged in such a positional relationship that they magnetically repel each other.

In the sputtering apparatus having such a configuration, the plasma-like argon gas existing in the vacuum chamber 1 is confined within the magnetic field of the magnet system 7, so that the plasma ions of the argon gas (oAr 3 in the figure) are efficiently released (on the target 5). Semiconductor wafer 3 where metal atoms that collide with the surface and are ejected by the energy generated face each other as indicated by dotted arrows in the figure.
efficiently reach the surface.

Therefore, a tungsten film with a thickness of 2,000 to 4,000 thick is formed on the surface of the semiconductor wafer 3 by adjusting the current and voltage applied to the target 5 and the pressure of argon gas sent from the pipe 1a to preset conditions.

The warpage of the wafer at this time can be suppressed to 200 μm or less in the diameter direction when the wafer size is 6p.

[Problem that the invention seeks to solve]

With conventional methods, it is not possible to completely eliminate warping of the wafer because the thickness of the semiconductor wafer is thin and the film is only formed on one side of the semiconductor wafer. By setting the argon gas pressure and other conditions to optimal conditions, the internal stress of the coating itself is minimized, and the warping of the wafer after the coating is formed is minimized.

However, as technology progresses, the patterns on semiconductor wafers become finer and the wafer size increases, requiring improvements in the dimensional accuracy of each part, resulting in the problem that wafer warpage, which was previously allowed, may no longer be ignored. was there.

[Means for solving the problem] The above problem is solved by sputtering, which applies a high voltage between the target electrode and the semiconductor wafer in a vacuum atmosphere of inert gas, and attaches constituent atoms of the target electrode to the semiconductor wafer surface. This problem is solved by a sputtering method in which constituent atoms of the same type are deposited simultaneously and under the same conditions on both sides of a semiconductor wafer which is held with both sides exposed.

[For production]

In the sputtering apparatus of the present invention, the same type of film is simultaneously deposited on both sides of a semiconductor wafer and has the same thickness.

Therefore, since coatings under exactly the same conditions are formed on both sides of the wafer, even if internal stress occurs in the coating, there is no stress difference between the two films, so that the semiconductor wafer after the coating is formed will not warp.

〔Example〕

FIG. 1 is a diagram showing an example of the configuration of the main part of the sputtering apparatus according to the present invention, in which (A) shows a case in which four sets of magnet systems, two sets on each side of a wafer, and (B) shows the entire structure. Another embodiment is shown that is constructed with a set of magnet systems.

In FIG. 1(A), a vacuum chamber 1 is maintained at a vacuum level of about 10-3 to 10-ITorr by a vacuum pump 2, and is filled with argon gas at a specified pressure injected from a vibrator 1a. This is as shown in Figure 2.

Reference numeral 3 designates a semiconductor wafer similar to that shown in FIG. 2, which is clamped and fixed by two fixtures 10 and 10', top and bottom electrically grounded, so that both surfaces are exposed while maintaining electrical continuity. In this case, the semiconductor wafer 3 must be easily attached to and removed from the fixture, must not be tilted when attached, and must maintain electrical continuity as described above. A ladder-shaped groove 10a having a bottom width approximately equal to the thickness of the semiconductor wafer 3 as shown in 11 is provided, and a groove having a short length and the same cross section as the groove 10a described above is provided as shown in FIG. Therefore, the circular semiconductor wafer 3 is held between the fixtures 10 and 10' having such grooves as shown by the dotted lines in the figure to ensure the position of the wafer 3 and electrical continuity. .

Furthermore, two targets 11 made of tungsten (-)
are arranged in parallel and facing each other at equal intervals on both sides of the semiconductor wafer 3. Note that the potential is configured to be negative with respect to the semiconductor wafer 3 by the external power supply 6 as in FIG.

Further, two sets of magnet systems 12 are arranged in close proximity to the back surfaces of the targets 11 facing the semiconductor wafer 3 in such a positional relationship that they magnetically repel each other.

In the sputtering apparatus having such a configuration, the metal atoms of the target 11 adhere to the opposing wafer surface independently as shown in the dotted line arrows on each side of the semiconductor wafer 3 as explained in FIG. Since the film is formed under certain conditions, the internal stress generated in the film is exactly the same on both sides.

Therefore, no difference in stress occurs between both sides of the wafer, and the wafer does not warp even after the coating is formed.

In addition, in FIG. 1(B), similar to FIG. 1(A), two targets 11 made of tungsten are arranged in the vacuum chamber 1, and the target 11
Furthermore, two magnets 13 having a size sufficient to cover the semiconductor wafer 3 are arranged, and the two magnets 13 are arranged so that their magnetic poles face each other so that they are magnetically attracted to each other. It is placed at the back.

In a sputtering apparatus having such a configuration, the metal atoms of the target 11 adhere to the opposing wafer surface as indicated by the dotted arrows in the figure, while both surfaces of the semiconductor wafer 3 remain independent, as described in FIG. In this case, since the lines of magnetic force generated by the two magnets 13 and the semiconductor wafer 3 are perpendicular to each other, the metal atoms ejected from the target 11 adhere to the wafer surface in an accelerated state.

However, in this case as well, the coating is formed under the same conditions as in Figure (A), so the internal stress generated in the coating is exactly the same on both sides, and the wafer does not warp even after the coating is formed.

〔Effect of the invention〕

As described above, by implementing the present invention, it is possible to provide a sputtering apparatus that does not require strict control of the current and voltage applied to the target, the pressure of inert gas such as argon gas, etc., and does not cause warping of semiconductor wafers after film formation. can do.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of the main part of a sputtering apparatus according to the present invention, and FIG. 2 is a diagram showing an example of the configuration of the main part of a conventional sputtering apparatus. In the figure, l is a vacuum chamber, 1a is a pipe, 2 is a vacuum pump, 3 is a semiconductor wafer, 6 is an external power supply, 10.10' is a fixture, 11 is a target, 12 is a magnet system, and 13 is a magnet. represent. (B)

Claims (2)

[Claims] (1) A semiconductor wafer held with both sides exposed in a sputtering method in which atoms constituting the target electrode are attached to the surface of the semiconductor wafer by applying a high voltage between the target electrode and the semiconductor wafer in an inert gas vacuum atmosphere. A sputtering method characterized in that constituent atoms of the same type are deposited on both sides of the substrate at the same time and under the same conditions. (2) A semiconductor wafer held with both sides exposed in a sputtering device that applies a high voltage between the target electrode and the semiconductor wafer in an inert gas vacuum atmosphere to attach constituent atoms of the target electrode to the semiconductor wafer surface. A sputtering apparatus characterized in that two target electrodes are disposed at approximately equal intervals on both sides of the screen so as to face each other in parallel.