JPH11209872A - Sputtering device and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering device for making the compositional ratio of a silicide film formed by sputtering constant and to provide a sputtering method. SOLUTION: Both sides of an Si target 1 are provided with W targets 2a and 2b fitted to rods 10a and 10b for rotating a target, and while the inclined angle α of the W targets 2a and 2b is varied within the range of the angle of tan<-1> (b/L)<=α<=tan<-1> (a+b)/L}, sputtering is executed. In this way, the radiation angle of high m.p. metal and Si atoms in a silicide film is corrected, and the compositional ratio of the silicide film formed on the flat part in the stage error on a semiconductor substrate 8 and the compositional ratio of the side wall part in the stage error can be made equal to prevent deterioration in its chemcal resistance and the peeling of the film caused by the difference in the compositional ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sputtering apparatus and a sputtering method used for forming a metal alloy thin film on a semiconductor substrate, and more particularly to a sputtering apparatus and a sputtering method used for forming a silicide metal thin film.

[0002]

2. Description of the Related Art Conventionally, SiMOS devices and GaAsF
For the gate electrode of the ET, a silicide metal thin film such as WSi or MoSi is used by a sputtering method for the purpose of improving heat resistance.

[0003] These silicide thin films are compounds of W and Mo, which are refractory metals, and Si, and film characteristics such as resistivity and internal stress vary depending on the composition ratio. For this reason, using a refractory metal target or a refractory metal silicide target and a Si target so as to keep the composition ratio constant, the refractory metal film or the refractory metal silicide film and the Si film are alternately formed by magnetron sputtering. The layers were stacked and the composition ratio was kept constant.

[0004] Such a conventional sputtering method will be described with reference to the drawings. FIG. 3 is a sectional view of a conventional sputtering apparatus. First, a refractory metal or refractory metal silicide target 31 having a permanent magnet 33a and a Si target 32 having a permanent magnet 33b
Are connected to DC sputtering power supplies 34a and 34b provided outside the sputtering chamber 39, respectively.

In the sputtering chamber 39, a transfer device 35 is provided, and a substrate holder 36 is mounted. The substrate holder 36 holds the target 3
The semiconductor substrates 37 are mounted opposite to the semiconductor devices 1 and 32 at regular intervals. In this state, Ar gas is introduced from the Ar gas introduction line 38, and the substrate holder 36 moves left and right on the front surfaces of the targets 31 and 32 at a fixed interval by the transfer device 35, and the semiconductor substrate 37 on the substrate holder 36 Then, a high-melting-point metal or a laminated film of high-melting-point metal silicide and Si is formed.

At this time, in order to keep the composition ratio constant, the composition ratio of the refractory metal target or refractory metal silicide target 31, the voltage applied to each target 31 and 32 during sputtering by power sources 34a and 34b, the sputtering It is possible by adjusting the Ar gas pressure and the like.

[0007]

However, in the above-mentioned sputtering method, the composition ratio and the film thickness of the film formed due to the difference in the emission angle of each target element are not constant in the semiconductor substrate surface, The deviation of the composition ratio causes a decrease in chemical resistance and a difference in internal stress of the film, so that the film is peeled off.

The angle of emission of the sputtered particles differs depending on the constituent elements of the target as proposed in JP-A-1-91342 and JP-A-2-173260. As shown in the cross-sectional view of the sputtering apparatus, a metal target 41b having a permanent magnet 42b and a metal target 41c having a permanent magnet 42c are provided on both sides of a metal target 41a having a permanent magnet 42a facing the semiconductor substrate 46. The structure is such that it is arranged with an inclination angle with respect to 41a. In addition, each metal target 41a, 41b,
41c includes DC sputtering power supplies 43a, 43b, 43c.
Is connected.

As described above, the metal targets 41b and 41b
When c has a tilt angle, the sputtered particles are less affected by the emission angle distribution, and the semiconductor substrate 4
Since the substrate holder 45 uniformly distributed on the substrate 6 and further mounted with the semiconductor substrate 46 is moved right and left on the front surfaces of the metal targets 41 a, 41 b and 41 c by the transport roll 44, the composition is flat on the semiconductor substrate 46. Both the ratio and the film thickness become constant.

However, even if the above-mentioned conventional sputtering apparatus is used, a step structure as shown in the sectional view of FIG. 5A (IEICE Technical Report, September 1993, published by the Institute of Electronics, Information and Communication Engineers).
(Published on pages 7 to 12 of the monthly issue), ie, the semiconductor substrate 51
In the case of the structure having the step of the insulating film 52 and the silicide film 53 on the plane of the above, even if the composition ratio in the flat portion 53a on the insulating film is constant, the flat portion 53c on the substrate and the insulating film side wall 5
3b, the concentration of Si is higher than the concentration of the refractory metal, and in the case of a contact hole structure as shown in the cross-sectional view of FIG. The portion 53e has a high concentration of the high melting point metal, and the flat portion 53d in the opening has a high concentration of Si.

The tendency of the composition ratio is such that as the ratio (aspect ratio) between the hole diameter and the height of the hole portion increases, the silicide film made of a metal having a large mass difference from Si such as W is formed. Since the effect becomes remarkable in the case of sputtering, the effect of the difference in the emission angle of the sputtered particles cannot be eliminated only by inclining the metal target at a certain angle.

An object of the present invention is to provide a sputtering apparatus and a sputtering method capable of maintaining a constant composition ratio in a metal silicide film by sputtering regardless of the shape of a film to be formed. It is in.

[0013]

According to the present invention, when forming an alloy thin film of a first metal and a second metal on a step portion formed on a semiconductor substrate by sputtering, the target of the first metal is applied to the semiconductor substrate. In a sputtering apparatus installed in parallel with the surface and further comprising a second metal target disposed on both sides of the first metal target so as to have an inclination angle α with respect to the first metal target, the second metal target Are rotatable about a target rotation rod inclined at an angle α with respect to the normal direction of the semiconductor substrate surface, respectively, and the second metal is The tilt angle α of the target is variable, and the target of the second metal is rotatable while changing the tilt angle α. A sputtering apparatus according to claim.

Further, according to the present invention, when forming an alloy thin film of a first metal and a second metal on a step portion formed on a semiconductor substrate by sputtering, the target of the first metal is parallel to the surface of the semiconductor substrate. In the sputtering method, the second metal target is disposed on both sides of the first metal target so as to face the first metal target at an inclination angle α, and sputtering is performed.
Sputtering is performed simultaneously using the first and second metal targets, and at this time, the second metal target is rotated at an inclination angle α, or is rotated while changing the inclination angle α within a predetermined angle range. Forming the metal alloy thin film having a constant composition ratio on a step portion on the semiconductor substrate.

[0015]

Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a first embodiment of the sputtering apparatus of the present invention.
2A is a cross-sectional view showing the structure of a WSi sputtering film forming apparatus, and FIG. 2B is an explanatory view showing its function.

First, as shown in FIG. 1A, a Si target 1 having a permanent magnet 3a on the back side is
It is arranged so that it may become parallel. On both sides of the Si target 1, a W target 2a having a permanent magnet 3b on the back surface and a W target 2b also having a permanent magnet 3c on the back surface are respectively provided with target rotating rods 10a,
With external power 11a, 11b using 10b as a rotation axis,
The inclination angle α with respect to the Si target 1 is made variable within the vacuum of the sputtering chamber 9. A spherical bearing is used as the variable mechanism.

Also, a Si target 1 and a W target 2
a, W target 2b is a sputtering chamber 9
Are connected to power supplies 4a, 4b, 4c provided outside the power supply, respectively, so that different voltages can be applied by the respective power supplies. An electrostatic shield 5 is provided between the Si target 1 and the W targets 2a and 2b.

Using an apparatus having such a target arrangement, W: Si is formed on the step portion of the insulating film on the semiconductor substrate 8.
In the case of forming a WSi film having a composition ratio of = 2: 1 to a thickness of 100 nm, first, the semiconductor substrate 8 mounted on the substrate holder 7 is introduced into the sputtering chamber 9 and A
Ar gas is introduced from the r gas introduction line 6, and 400 W of electric power is supplied to the Si target 1 and the W targets 2a, 2
A power of 800 W is applied to each of b.

Here, as shown in FIG. 1B, the inclination angle α of the W targets 2a, 2b with respect to the Si target 1.
Is the distance between the Si target 1 and the substrate holder 7 is L, the length of one side of the square substrate holder 7 is a, and
Assuming that a distance from a point A where a line passing through the centers of the W targets 2a and 2b is perpendicular to the surface direction of the substrate holder 7 to an end of the substrate holder 7 is b, tan ^-1 (b / L) ≦ α ≦ tan ^-1 So that the angle α satisfies the condition of {(a + b) / L}.
a and 10b are changed using the rotation axis. In the first embodiment, the sputtering is started from an inclination angle α of 20 degrees, and the W targets 2a and 2b are rotated while gradually increasing the angle to 45 degrees at the end.

As described above, by changing the inclination angle α, the emission direction of W atoms to the semiconductor substrate 8 changes, and the W atoms adhere to the step side wall portion shown in FIG. Since the amount of W atoms in the insulating film sidewall 53b increases and the amount of W atoms attached to the insulating film flat portion 53a decreases, the composition ratio of WSi in the insulating film sidewall 53b is reduced to the insulating film flat portion 53a. Approximately the same composition ratio.

The composition of the WSi film thus formed was analyzed by Auger electron spectroscopy.
The WSi film composition of a is W: Si = 2: 1, and the composition of the stepped insulating film side wall portion 53b and the flat portion 53c on the substrate is W: Si.
= 1.8: 1, and the composition ratio of the entire film is constant.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a sectional view of a sputtering apparatus according to the second embodiment. In the present embodiment, a WSi target is used instead of the Si target used in the first embodiment.

First, in FIG. 2, the permanent magnet 3a
Target 21 having a composition of W: Si = 5: 3
Are arranged in parallel with the semiconductor substrate 8. On both sides of the WSi target 21, a permanent magnet 3
b and a W target 2b also having a permanent magnet 3c on the back surface, respectively, and external power 1 using the target rotation rods 10a and 10b as rotation axes.
1a and 11b, the inclination angle α with respect to the WSi target 21 is made variable in the vacuum of the sputtering chamber 9.

The WSi target 21, the W target 2a, and the W target 2b are connected to power supplies 4a, 4b, and 4c provided outside the sputtering chamber 9, respectively, so that different voltages can be applied by the respective power supplies. It has become.

Using an apparatus having such a target arrangement, W: Si is formed on the step portion of the insulating film on the semiconductor substrate 8.
When a WSi film having a composition ratio of 5: 3 is formed to a thickness of 100 nm, first, the semiconductor substrate 8 mounted on the substrate holder 7 is introduced into the sputtering chamber 9 and the W
A power of 500 W is applied to the Si target 21, and a power of 1000 W is applied to the W targets 2a and 2b.

Here, in the second embodiment, the inclination angle α of the W targets 2a and 2b with respect to the WSi target 21 is 45 degrees at the start of sputtering and 20 degrees at the end of sputtering.
While gradually decreasing the W target 2a,
2b is rotated using the target rotation rods 10a and 10b as rotation axes.

As described above, by changing the inclination angle α, the emission direction of W atoms to the semiconductor substrate 8 changes, and the W atoms adhering to the inner wall 53e of the opening shown in FIG.
The amount of atoms decreases, the amount of W atoms adhering to the flat portion 53d in the opening increases, and the composition ratio of WSi in the inner wall portion 53e and the flat portion 53d in the opening becomes the flat portion on the insulating film. The composition ratio is almost the same as 53a.

The composition of the WSi film formed by this method was analyzed by Auger electron spectroscopy.
a: WSi film composition: W: Si = 5: 3;
The composition of 3e and the flat portion 53d in the opening is W: Si = 4.
9: 3, and the film composition ratio between the inside of the opening and the flat portion is constant.

In each of the first and second embodiments, the WSi film is formed.
In other silicide films such as MoSi and TiSi,
With this sputtering film forming method, the composition ratio of the film can be made constant.

[0030]

As described above, according to the sputtering apparatus and the sputtering method of the present invention, a silicide film can be formed at a constant composition ratio without depending on the shape of a step pattern or an opening pattern. As a result, peeling of the film due to a decrease in chemical resistance and a difference in internal stress can be prevented.

[Brief description of the drawings]

FIG. 1 is a view showing a WSi sputtering apparatus according to a first embodiment of the present invention, FIG. 1 (a) is a sectional view thereof, and FIG. 1 (b) is a functional explanatory view thereof.

FIG. 2 is a sectional view of a WSi sputtering apparatus according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of a conventional sputtering apparatus.

FIG. 4 is a cross-sectional view showing the structure of another conventional sputtering apparatus.

5A and 5B are diagrams showing a film formation structure formed on a semiconductor substrate, wherein FIG. 5A is a sectional view of a step structure, and FIG. 5B is a sectional view of an aperture structure.

[Explanation of symbols]

 Reference Signs List 1 Si target 2a, 2b W target 3a, 3b, 3c Permanent magnet 4a, 4b, 4c Power supply 5 Electrostatic shield 6 Ar gas introduction line 7 Substrate holder 8 Semiconductor substrate 9 Sputtering chamber 10a, 10b Target rotation rod 11a, 11b External Power 21 WSi target 31 Refractory metal target 32 Si target 33a, 33b Permanent magnet 34a, 34b Power supply 35 Transport device 36 Substrate holder 37 Semiconductor substrate 38 Ar gas introduction line 39 Sputtering chamber 41a, 41b, 41c Metal target 42a, 42b, 42c Permanent magnets 43a, 43b, 43c Power supply 44 Transport roll 45 Substrate holder 46 Semiconductor substrate 51 Semiconductor substrate 52 Insulating film 53 Silicide film 53a Flat portion on insulating film 53b Discontinued Film side wall portion 53c on the substrate flat portion 53d opening the flat portion 53e opening in the side wall portion

Claims (6)

[Claims] When forming an alloy thin film of a first metal and a second metal on a step portion formed on a semiconductor substrate by sputtering, a target of the first metal is set in parallel with a surface of the semiconductor substrate, In a sputtering apparatus in which a target of a second metal is disposed on both sides of the target of the first metal so as to be opposed to the target of the first metal at an inclination angle α, the targets of the second metal are each formed by the semiconductor substrate surface method. A sputtering apparatus characterized in that the sputtering apparatus is rotatable about a target rotation rod inclined at an angle α with a line direction. 2. The sputtering apparatus according to claim 1, wherein the inclination angle α of the second metal target is variable with the target rotation rod as a central axis. 3. The sputtering apparatus according to claim 1, wherein the second metal target is rotatable while changing an inclination angle α. 4. The distance between the substrate holder on which the semiconductor substrate is mounted and the target of the first metal is L, the width dimension of the substrate holder is a, and the extension of the a dimension extends the second metal from the end of the substrate holder. Assuming that the distance to a point directly above the center of the target is b, the inclination angle α of the target of the second metal is tan ⁻¹ (b / L) ≦ α ≦ tan ⁻¹ {(a +
b) / L}. 5. When forming an alloy thin film of a first metal and a second metal on a step portion formed on a semiconductor substrate by sputtering, the target of the first metal is set in parallel with the surface of the semiconductor substrate. In a sputtering method in which sputtering is performed by arranging a target of a second metal on both sides of the target of the first metal so as to have an inclination angle α with respect to the target of the first metal, the first and second metal targets may be used. A sputtering method wherein the metal alloy thin film having a constant composition ratio is formed on a step portion on the semiconductor substrate by rotating a target of the second metal at the same time. 6. The method according to claim 6, further comprising: rotating the target of the second metal while changing the inclination angle α within the angle range to form the metal alloy thin film having a constant composition ratio on the step portion on the semiconductor substrate. The sputtering method according to claim 5, wherein: