JPS6318071A - Leaf type bias sputtering device - Google Patents

Abstract

PURPOSE:To improve the uniformity of a bias effect in a substrate plane by providing magnets respectively to a target side electrode on the side opposite from the side facing the substrate and to a substrate side electrode on the side opposite from the side facing the target and forming a prescribed magnetic field distribution. CONSTITUTION:RF electric power is impressed as a target bias from a power source 15 to the target side electrode 11 at the time of forming an inter-layer insulating film. A DC voltage is impressed as a target bias from a DC power source to said electrode at the time of forming a conductive film. RF electric power is impressed as a substrate bias from a power source 16 to the substrate side electrode 12. An excitation coil 18 of the target side electromagnet is disposed via an insulating material 17 to the target side electrode 11 on the side opposite from the side facing the substrate. An excitation coil 19 is similarly disposed to the substrate side electrode 12 on the side opposite from the side facing the target. The target side magnet sets the magnetic field in such a manner that uniform sputters can be formed at the time of biasing the target. The substrate side magnet sets the magnetic field in such a manner that the reverse sputtering speed at the time of biasing the substrate is uniform within the substrate plane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a sputtering apparatus used in the manufacture of semiconductor devices, and particularly to a single-wafer bias sputtering apparatus.

(Prior Art) Single-wafer bias sputtering equipment used to form interlayer insulating films and metal films by sputtering in the multilayer wiring process of semiconductor integrated circuits has conventionally been configured as shown in FIG. 3, for example. ing. That is, in the electromagnetic magnetron bias sputtering apparatus shown in FIG.
and 32 are a pair of electric bridges facing each other in parallel in the film forming chamber, and the pair of electric bridges h31*3j! A target 33 and a substrate (semiconductor wafer) 34 are held in correspondence with each other on opposing surfaces. RF power is applied to the target side electrode 31 as a target bias from an RF' (high frequency) power source 35 using a magnetron when forming an l-interlayer insulating film, and a metal film (&l film, s-1 alloy film, , a high melting point gold X film or its crystallization, etc.), direct AT voltage is applied as a target bias from a DC power source (not shown). Further, RF'@@ is applied to the substrate side electrode 32 from the RF power source 36 as a substrate bias. An excitation coil 38 of an electromagnet is disposed on the back side of the target of the target side electrode 31 with an insulating material 37 interposed therebetween.

In the above bias sputtering device, the electrodes 31, 32
A plasma 39 of a rare gas or the like is generated by magnetron discharge between the two, and an interlayer insulating film or a metal film is sputtered on the substrate by making full use of the impact of the 11C ions present in the plasma on the target material. In addition, target ill! The It magnet controls the plasma region using the generated magnetic field to confine the plasma, thereby reducing damage to the substrate caused by the plasma and increasing the speed of sputtering film formation.

According to the above-mentioned bias sputtering apparatus, the step coverage of the step part of the base of the film formation (the step part of the wiring, the opening part of the insulating film) and the flatness of the film-forming surface are improved. As shown in Fig. 4 (b), a cylindrical permanent magnet 42 and a cylindrical permanent magnet 43 are attached to a yoke 41.
Even in the case of a permanent magnet magnetron bias sputtering device disposed on the back surface of the target of the fil bridge 31, sputtering film formation can be performed in the same manner as described above. In addition,
In FIG. 4, the same parts as in FIG. 3 are given the same reference numerals.

However, the conventional sputtering equipment described above does not have a uniform bias effect (
Improving step coverage on the step part under the sputtered film,
(planarization of the sputtered film surface) is not necessarily sufficient.

That is, (1) the distribution of the magnetic field generated on the target is such that a uniform thin film can be sputtered on the substrate when the target is biased. However, due to the effect of this magnetic field, when a bias is applied to the substrate, the bias effect becomes non-uniform within the substrate plane, and the variation value of the bias effect can exceed ±40%. is shown in Figure 5. That is, FIG. 5(a) shows (a) the film forming speed at a target bias of 2000 W, and (b) the film forming speed at bias sputtering (Targera) of 2000 W/substrate 200 under the conditions that the film forming speed is uniform when the target bias is applied.
The in-plane distribution of gold on the substrate is shown for each of the film forming rate of W) and the substrate sputtering rate at a VJ substrate bias of 200 W. In addition, the step coverage of sputtering film formation (in the case of an insulating film) at the center of the wafer and at the periphery of the wafer under the above conditions is shown in FIG. 5(b) and (Cl). (2) Conversely, if the magnetic field is set using a magnet on the target side so that the bias effect is uniform within the substrate plane, the film formation distribution when the target bias is applied becomes non-uniform, and this situation is shown in Figure 6. ing.

That is,! @Figure 6 ta) shows (a) film formation speed at target bias, (b) I film speed at J bias sputtering, V→ It shows the distribution within the substrate for each substrate sputtering speed under substrate bias.It also shows the step coverage of sputter film formation (in the case of an insulating film) at the center, urchin, and periphery of the wafer under the above conditions. The corresponding figures are shown in FIGS. 6(tb) and (C).

In addition, Fig. 5 1b), IcI and Fig. 6 1bl
1 (C) & 51 is a silicon substrate (Way S)
, 52 is a thermal oxide film (8i0. film), 53 is a metal wiring pattern (for example, made of Al-81 alloy), and 54 is a sputtered oxide film formed by sputtering.

As can be seen from the characteristics shown in FIGS. 5(a) and 6(a) above, according to the conventional bias sputtering apparatus, the uniformity of the sputtered oxide film deposition rate within the substrate surface is approximately 15%. ,
Further, the step coverage on the step of the metal wiring is good at the wafer/periphery (good taper), but not at the center of the wafer. Similarly, when forming a film on a metal film by sputtering in an opening in an insulating film, step coverage deteriorates at the center of the wafer, so there is a risk of wire breakage due to electromigration or the like.

(Problems to be Solved by the Invention) As described above, the present invention is based on the problem that it is difficult to set the relationship between target bias, substrate bias, and magnetic field distribution so that the total bias effect is uniform within the substrate plane. This was developed to solve the problem, and the object is to provide a single-wafer type bias sputtering apparatus that can appropriately set the magnetic field distribution so as to improve the uniformity of the bias effect within the substrate surface.

[Structure of the invention]

(Problem tl - Means for Solving) The single wafer type bias sputtering apparatus of the present invention is based on Targera) 1
! It is characterized in that a gold film is formed on the magnet to form a predetermined magnetic field distribution on the opposite side of the substrate-facing surface of the Ili pole and on the opposite side of the target-facing surface of the substrate-side electrode.

(Function) The target i11! can be sputtered to form a uniform thin film on the substrate during target bias. By forming the magnetic field distribution of the Iia stone and forming the magnetic field distribution of the substrate side magnet so that the reverse sputtering speed when applying a substrate bias is uniform within the substrate surface, a uniform bias effect can be obtained within the substrate surface. It becomes like this.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to all the drawings.

FIG. 1 schematically shows an electromagnetic magnetron bias sputtering apparatus, and 11 and 12 are a pair of electrodes facing each other in parallel in a film forming chamber that is maintained at a high vacuum by introducing Ar gas, for example. A target 13 is held on the opposite surface of the target side electrode 11, and the substrate side electrode 1
A base ffL (semiconductor wafer) 14 is held on the opposing surface of the wafer 2.

To the target-side electrode 11, RFK force is applied as a target bias from the RF power source 15 when forming the glabella insulating film, and DC 1K force is applied as the target bias from a direct flux source (not shown) when forming the conductive film. . Also, one pole 12 on the board side has an R
FyL force is applied as a substrate bias. Then, on the opposite cki side of the target@electrode 11 facing the substrate ljIiga, a target a'ti is placed via an insulating material 17.
An a-stone excitation coil 18 is disposed, and similarly, an excitation coil 19 of a substrate-side electromagnet is disposed on the opposite surface of the substrate-side electrode 12 from the target-facing surface with an insulating material 17 interposed therebetween.

Incidentally, in place of the target-side electromagnet and substrate-side electromagnet, permanent magnets as shown in FIGS. 4(a) and 4(b) may be provided.

In the above bias sputtering apparatus, the magnetic field of the target-side magnet is set so that a uniform thin film can be sputtered on the substrate during target bias, and the substrate gag
The magnetic field of the i-stone is set so that the reverse sputtering speed when a substrate bias is applied is uniform within the substrate surface.

FIG. 2(b) shows a method of forming a sputtered oxide film by sputtering using the bias sputtering apparatus described above.

(e)? Refer to and explain. First, a thermal oxide film 22 is formed on a semiconductor substrate 21 to a thickness of 100 l, and a 1.0 μm thick It-Si film is deposited thereon by a sputtering method, followed by a normal photo-etching process. A wiring pattern 23 is formed by phosphorography and RIB (reactive ion etching).Next, a sputtered oxide film 24 having a thickness of 1.1 pm is formed using the bias sputtering apparatus described above.

The sputtering conditions at this time are as follows:
The degree of vacuum (xr partial pressure) in the film forming chamber is 0.40 Pascal (P
a), the power applied to the target electrode is 2000 W, the power applied to the substrate electrode is 200 W, and the film forming rate is approximately 800 A/m.
It is in.

In the bias sputtering apparatus described above, (a) distribution of the film formation rate during target bias within the wafer surface, (b) distribution within the wafer surface of the film formation speed during bias sputtering, (
c) The in-wafer surface distribution of the substrate sputtering rate at substrate bias had the characteristics shown in FIG. 2(a). Further, at this time, the step coverage of the insulating film on the step portion of the metal wiring at the wafer central portion and the wafer peripheral portion is as shown in FIGS. 2(tb) and (C), respectively. That is, as can be seen from the above characteristics, the uniformity of the sputtered oxide film deposition rate within the substrate surface was a good value of ±4%, which was significantly improved by 1 compared to the conventional example. In addition, good step coverage was obtained at the center of the wafer and at the periphery of the wafer.

Note that even when a sputtering film such as a Hel film or an A/-8 alloy film is formed on an insulating film having an opening such as a contact hole or a through hole, the step coverage of the opening in the insulating film and Good flatness of the film-formed surface was obtained, and metal wiring resistant to disconnection could be uniformly formed on the substrate.

Therefore, according to the bias sputtering apparatus of the present invention,
It can be used in an insulating film formation process and a metal film formation process when forming multilayer wiring on a semiconductor substrate.

〔Effect of the invention〕

According to the single wafer type bias sputtering apparatus of the present invention as described above, the uniformity of the bias effect within the substrate surface can be greatly improved, and a sputtered insulating film with good step coverage can be formed on the stepped portion of metal wiring. Since a sputtered metal film with good step coverage can be formed in the opening of the insulating film, it is suitable for use in the process of forming a multilayer wiring structure in the manufacture of semiconductor integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the single wafer type bias sputtering apparatus of the present invention, FIG. (C1 is a cross-sectional view showing the step coverage of the oxide film obtained at the center of the wafer and the periphery of the wafer under the characteristics shown in FIG. The configuration explanatory diagram showing an example of the apparatus, Fig. 4 ta) is the same (the configuration explanatory diagram showing another example of the conventional single-wafer bias sputtering apparatus, Fig. 4 1b) is the target side permanent part in the same figure t8). Figure 5(a) is a plan view showing the magnet 9 taken out, and a sputtered oxide film is formed using the apparatus shown in Figure 3 with a 1111iH stone set so that the film formation rate is uniform when a target bias is applied. A diagram showing the characteristics when formed, FIG. 5(b),

[C] is a cross-sectional view showing the step coverage of the oxide film obtained at the center of the 9-wafer and around the wafer under the characteristics shown in Figure 6(a). FIG. 6(b) is a diagram showing the characteristics when a sputtered oxide film is formed with the target@magnet set so that the reverse sputtering speed is uniform when a substrate bias is applied. (C) is a cross section showing the step coverage of the oxide film obtained at the wafer center and the wafer periphery under the characteristics shown in Figure (a). 1 No. Target side 'tun bridge, 12... Substrate side electrode, 13... Target, 14... Substrate (semiconductor wafer), 15.16... High frequency power supply, 17... Insulator , 18...Tagela) IIg electromagnet excitation coil, 1
9... Excitation coil of the board side electromagnet. Applicant's representative Patent attorney Suzue Takehiko Fig. 1 uni to Fg9 bu [ (a) Fig. 2 Fig. 3 crs s3 + husband Raeno\top: = 1 尤 = i 艷 (a) (b) (C) Fig. 5 Standing 9F above the wafer <a> Fig. 6

Claims (1)

[Claims] A target-side electrode and a substrate-side electrode for sputtered film formation that are provided to face each other in parallel in a film-forming chamber, a target held by the target-side electrode, and a high-frequency wave that applies high-frequency power or DC voltage to the target-side electrode. a power source or a DC power source; a high-frequency power source that applies a high-frequency power to the substrate-side electrode; a target-side magnet that is disposed on the opposite side of the target-side electrode to the surface facing the substrate and forms a predetermined magnetic field distribution; and the substrate. 1. A single-wafer bias sputtering apparatus comprising: a substrate-side magnet disposed on the opposite side of the target-facing surface of the side electrode to form a predetermined magnetic field distribution.