JPH02209485A - Plasma treating device - Google Patents

Abstract

PURPOSE:To enhance plasma treating characteristics by regulating the position for maximumly producing plasma species (treating species) which are produced by utilizing cyclotron movement of charged particles to a range within the distance of a mean free path thereof from a base plate and making the angle of the normal of a base plate face for plasma flow variable. CONSTITUTION:The angle of a base plate holder 2 is made variable for the center axis of a device and also the holder is transferred to the position of the base plate 1 from the end of a window for introducing microwave 6 because it can be rotated around the base plate. On the other hand, the position of an electronic cyclotron which becomes the position for maximumly producing the plasma species is decided by regulating the amount of power supply of the main and auxiliary magnetic field coils 9, 10 and thereby controlling the magnetic flux density. Thereby the side part of the difference of the surface level of the base plate is uniformly treated and efficiency of plasma treatment is enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to semiconductor device manufacturing and functional thin film device manufacturing methods, and in particular, in processing substrates with stepped portions, high coverage of stepped portions and high quality film formation. The present invention also relates to a plasma processing apparatus suitable for highly efficient and appropriate doping of impurities to the side surfaces of steps, surface smoothing, and the like.

[Conventional technology]

The conventional plasma processing equipment is Advanced In-Electronics and Electron Physics 30.
．． (1971) on page 76 (Advin Electro
nics and Electron Phys 30
．． (1971), p. 76), by sputtering a target to generate a deposition species, and making the deposition species obliquely incident on the substrate, it is possible to form a film even on the side surfaces of the substrate step. equipment and JP-A-56-
As described in No. 155535, an apparatus that uses electron cyclotron resonance to generate highly excited plasma treatment species at low pressure, and causes the treatment species to reach the substrate surface almost perpendicularly to the substrate surface using a magnetic field to form a high-quality film. was there.

[Problem that the invention sought to solve]

The above-mentioned conventional technology takes into account the method for the treatment species to reach the side surface of the stepped portion on the substrate, but it does not take into account the degree of excitation of the treatment, the processing characteristics, or the appropriate method for generating the treatment species. For example, in film formation, there were problems such as poor film quality or slow formation speed. In the latter case, when a film is formed.

There have been problems in that the stepped portion becomes steeper, an overhang is formed, and the film quality on the top surface and the side surface of the stepped portion is significantly different.

For this reason, the desired size conductor device could not be manufactured.

An object of the present invention is to solve the above-mentioned disadvantages.

[Means to solve the problem]

The above objectives are as follows: 11) Generate plasma species in a highly excited state in a low pressure region, that is, process species, by using electron cyclotron or ion cyclotron motion to generate process species for treating a substrate, and The maximum generation position of is located within the mean free path distance of the treated species from the substrate.

2) The treated species is transported in the direction of the applied magnetic lines of force or electric lines of force and becomes a plasma flow. Plasma processing is performed by setting an angle to the normal to the substrate surface with respect to this plasma flow.

This is achieved by doing two things at the same time.

[Effect]

The characteristics of plasma processing largely depend on the excited state of the processing species that reach the substrate, and the higher the excited state, the higher the processing characteristics and processing efficiency. When plasma is generated using the cyclotron motion of the heavy particles, highly excited treatment species are efficiently generated.

In addition, if the maximum generation position of the plasma is located within at least the mean free path distance of the treated species from the substrate, the rate of deactivation due to collisions between particles will be significantly reduced, so that the highly excited state that reaches the substrate The proportion of treated species increases. The processing species can be incident on the substrate side as a plasma flow using a magnetic or electric field, but if an angle is created between the direction of the plasma flow and the normal line of the substrate, the processing species can be efficiently applied to the side surfaces of the stepped portions on the substrate. Good incidence. At this time, when the substrate is rotated, the stepped side portions of the substrate are uniformly processed.

Therefore, when a substrate is processed by the above method, plasma processing with excellent properties can be efficiently performed on the side surfaces of the step, such as forming a high quality deposited film with excellent coverage of the step.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of a microwave plasma processing apparatus based on the present invention.

This device includes a plasma generation chamber 4, a microwave waveguide 7, (the oscillator of the microwave 6 is omitted from the diagram), a main magnetic field coil 9, an additional magnetic field coil 10, a processing chamber 2, a substrate holder 3, and an exhaust port 1.
2 (the exhaust system is omitted from the diagram), the first gas supply nozzle 5 and the second
It consists of a gas supply nozzle 11 (the gas supply system is not shown). The plasma generation chamber 4 is made of quartz and has a conical top serving as a microwave introduction window 8. The substrate holder has a structure in which the angle with respect to the center axis of the device is variable and it rotates with respect to the center of the substrate. By adjusting the current flowing through the main magnetic field coil 9 and the additional magnetic field coil 10, the magnetic flux density applied within the device can be controlled. FIG. 2 shows the magnetic flux density distribution in the direction of the central axis of the device. By controlling the magnetic flux density, the electron cyclotron resonance (ECR) position, which is the position where plasma species are maximally generated, can be moved from the edge of the microwave introduction window to the substrate position, as shown in the figure.

Example 1 A 5iOz film was deposited on a silicon substrate (125 φ [m]) on which a thermally oxidized film was formed and patterned with AQ (thickness 7.0 [μm]) as the substrate to be processed. The formation conditions were: introduced microwave power of 500 (w
), and oxygen and 02 gas are supplied from the first gas supply nozzle 5.
00 [mΩ/m1n) moxirane, 5iHa gas was added to the second
The gas was introduced from the gas supply nozzle 11 at a rate of 20 [mΩ/m1n]. The reaction pressure was 0.3 [pal], and the ECR position was 100 [:un] away from the substrate (Figure 2, curve B).
. Figures 3 and 4 show the film thickness a on the top surface of the step and the film thickness s on the side surface of the step when a SiO2 film of 0.8 [μm] was deposited on the top surface of the step on the above substrate using an electron microscope. The figure shows this as the coverage (b/a) of the step part, and the buffered hydrofluoric acid solution (HF:NH) of the step top surface film and step side film.
4F=1:6) is a diagram showing the etch rate, VB and vl. The horizontal axis is the angle between the normal to the board surface and the center axis of the device. I took it. Note that the substrate was rotated 5 [rotations/minute]. From this result, the degree of coverage improves as the angle increases, especially. On the other hand, the coverage increases rapidly after 〉25°, and the etch rate of the film on the top surface increases sharply at 〈65°, and the film becomes rough.

At 25° < o < 65°, the etch rate is slow for both the top and side surfaces, the film is dense, and there is little difference between the two.
In particular, it can be seen that the uniformity of both is the highest at o 45°. From these facts, it was found that the plasma processing characteristics of the stepped portion are significantly improved when the normal to the substrate surface is tilted with respect to the plasma flow, and that when an appropriate angle is set (25° < o <
65°) It can be seen that the processing characteristics can be made uniform on the sidewall and top surface. Figures 5 and 6 show the etch rate and dielectric breakdown of 5iOz films deposited at different distances between the ECR position and the substrate when the tilt angle was 45° and the reaction pressure was 0.3 (pa). It is a figure showing an electric field. These results show that the closer the ECR position, that is, the plasma generation position, is brought to the substrate, the denser the film and the more excellent the insulation properties. Also, 0.3 [pa)
Then, the mean free path distance of 02 ion is 15' (mn)
However, it can be seen that when the ECR position is located within the above distance from the substrate, a particularly dense film with excellent insulation properties can be formed.

Therefore, if the maximum plasma generation position is set within the mean free path distance of the plasma treated species and the treated species reaches the substrate before the excited state is lost due to collisions between particles, etc., high quality It can be seen that this is effective in forming a film.

Example 2 As the substrate to be processed 1, an n-type silicon substrate (diameter 125 φ [m]) on which an SiOx film was deposited and holes were formed was used, and an aluminum film was deposited thereon. The formation conditions were: 100 mQ/m1n of argon and Ar were supplied from the first gas supply nozzle 5, and triisobutyaluminum, (C3H7)aAQ was supplied from the second gas supply nozzle 11.
(10 Cm Q /m1n) was introduced. The ECR position was 100 [nm] away from the substrate, and the inclination angle of the substrate surface was changed for deposition. Other conditions are the same as in Example 7. FIG. 7 is a diagram showing changes in the angle formed by a perpendicular line from the substrate surface and a tangent to the deposited film surface at the bottom of the hole, as a measure of the deposition state in the hole portion. Figure 8 shows A
FIG. 4 is a diagram showing the change in wire breakage rate when 200 wires were made to conduct continuously by depositing n. A is the value when the ECR position is 50 [mn] away from the substrate, and C is the value when the film is deposited at a distance of 300 [mn] from the substrate. From these results, it can be seen that as the inclination of the substrate surface becomes 25°<o<65°, the overhang condition at the hole portion is alleviated and the throwing power is improved.

Further, the disconnection rate is low at 25°<o<65°, and it can be seen that the closer the ECR position is to the substrate, the better the conduction of AQ becomes. These results indicate that by tilting the substrate within a certain appropriate range and allowing highly excited treatment species to reach the substrate, it is possible to form a film with excellent throwing power and film conductivity at the gap. .

Example 3: The substrate to be processed 1 has a diameter of 125 (mn)φ.
A groove with a depth of 7 μml and an aspect ratio of 7 was formed in an n-type single crystal silicon substrate, and boric acid, B
Doping was carried out for 20 minutes. B2Fe was used as the doping gas, and was introduced from the seventh gas supply nozzle 5 at a flow rate of 50 (mQ/m1n). FIG. 9 is a diagram showing the dependence of the B concentration on the top and side surfaces of the step on the substrate inclination angle.

FIG. 10 is a diagram showing the concentration profile in the depth direction from the top surface of the substrate when the tilt angle is 45'. In the figure, A, B, and C have ECR positions 50, 10Q from the board,
This is the value when 300 (mn) away. These results show that as the inclination angle increases, the B doping amount decreases on the top surface, increases to about 65° on the side surfaces, and then decreases. The decrease on the side surfaces is due to the fact that the opposing side walls prevent ions from entering the side walls. From this, 25° < o < 65°
It can be seen that the surface is highly doped.

It can also be seen that the amount of doping increases as the ECR position gets closer to the substrate. From these facts, even in doping, high-quality plasma processing can be achieved with high efficiency by tilting the substrate at an appropriate angle with respect to the plasma flow and allowing highly excited treatment species to reach the substrate efficiently. I can see what will be done.

Example 4 A substrate with a diamond film formed on a Si substrate (diameter 10φ [■]) was used as the substrate to be processed.
The surface was smoothed by sputtering using r.

Ar is supplied from the first gas supply nozzle at 100 mQ/mi
n) A DC bias potential of -100 [V] is introduced into the substrate.
was applied.

Other conditions are the same as in Example 1. Figure 11 shows 633 [
FIG. 3 is a diagram showing changes in reflectance measured using an integrating sphere from a diamond film with respect to sputtering time for light of nn). The ECR position is 100 [rounds] away from the board. The horizontal axis represents the inclination angle. The value of t in the figure indicates sputtering time (minutes).

This result shows that sputtering can be performed efficiently at 25°<o<65°, and the substrate surface can be easily smoothed. FIG. 12 is a diagram showing the reflectance when the sputtering time is 4 minutes at an inclination angle of 45° and the distance from the ECR position to the substrate on the horizontal axis. This result shows that the substrate surface can be efficiently smoothed by bringing the substrate close to the ECR position so that highly excited sputtering species can efficiently enter the substrate.

As described above, according to this embodiment, by separating the plasma flow from the substrate surface normal direction, rotating the substrate, and locating the maximum plasma generation position at least within the mean free path distance of the treated species from the substrate, This has the effect that a high-quality film can be formed with good coverage and embedding of the stepped portion, and that doping on the side surface of the stepped portion and smoothing of the substrate surface can be done efficiently.

In the above embodiments, the inclination of the substrate was changed with respect to the plasma flow, but of course the plasma flow may be controlled by a magnetic field or an electric field to vary the angle of incidence on the substrate. FIG. 13 shows a device in which the additional magnetic field coil of the device shown in FIG. 7 has been removed and the main magnetic field coil has been strengthened. The substrate is installed parallel to the central axis of the device. The magnetic lines of force are curved around the center of the main magnetic field coil, and the direction of the lines of magnetic force near the substrate is at an angle of approximately 45° with respect to the substrate surface. FIG. 14 shows a device in which an additional magnetic field coil is installed only on one side with respect to the center axis of the device, and is separated from the center axis in the direction of the lines of magnetic force. The direction of the lines of magnetic force can be set at 45° near the substrate. FIG. 15 shows an apparatus that can apply a potential to a substrate holder, and is an apparatus that can form a plasma flow in a direction determined by a magnetic line of force vector and an electric force line vector. Above, the substrates were processed using the above three devices.
The same effect as the above embodiment was obtained.

〔Effect of the invention〕

According to the present invention, a high-quality film with good coverage at step portions can be formed extremely efficiently, so that the withstand voltage can be improved in the formation of an interlayer film, and wiring defects can be reduced in the wiring material. Further, since doping and smoothing of the substrate surface are efficiently performed, processing efficiency can be improved. This has the effect of significantly improving throughput and reducing manufacturing costs in manufacturing semiconductor devices such as LSIs.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main parts of the device of the present invention, Fig. 2 is a distribution diagram of the magnetic flux density applied within the device, and Figs. 3 and 4 are the coverage of the stepped portion and the inclination angle of the etch rate of the film. Diagram showing dependencies,
Figures 5 and 6 show the etch rate of the film and the E of the dielectric breakdown electric field.
Figures 7 and 8 are diagrams showing CR position dependence, and Figures 9 and 1 are diagrams showing inclination angle dependence of aluminum film coverage and disconnection rate.
Figure 0 shows the slope angle dependence of the doping amount and the profile, and Figures 11 and 12 show the slope angle and EC of the surface reflectance.
Figures 13, 14, and 15 showing R position dependence are main views of an apparatus showing one type of the present invention. 1... Board, 2, 2'... Board rotating holder, 3...
・Processing chamber, 4... Plasma generation chamber, 5, 11... Gas supply nozzle, 6... Microwave, 7... Waveguide,
8...Microwave introduction window, 9...Main magnetic field coil, 1
o, 10'...Additional magnetic field coil, 12...Exhaust port, 1
3...Magnetic field lines, 14...Plasma flow, 15...E
CR surface, 16...Bias potential, A・E CR-substrate distance 5o (III11), B・E CR-1 substrate distance 00 (m11), C-ECR-1 substrate distance 300
(m+3, a... Film thickness on the top surface of the step, b... Film thickness on the side surface of the step, va... Etch rate of the film on the top surface of the step,
Vb...Etch rate of the step side film. (ssnη Rinnu) ■Nagisa＊γ

Claims (1)

[Claims] 1. In a plasma processing method in which plasma is generated using cyclotron motion of charged particles and the plasma species are caused to reach a substrate to process the substrate, plasma formed by the action of an electric or magnetic field. A plasma processing apparatus characterized in that plasma processing is performed with the angle between the flow direction of the flow and the normal to the plane of the substrate to be processed being within a range of 25° to 65°. 2. The plasma processing apparatus according to claim 1, wherein the substrate to be processed is rotated. 3. Claims 1 or 2, characterized in that the point of maximum generation of plasma species is located at a position where the plasma species generated by the cyclotron motion reach the substrate within a mean free path distance. The plasma processing apparatus described. 4. The flow direction of the plasma flow is made to substantially match the propagation direction of the introduced high frequency wave, and the angle formed with the substrate surface is controlled by tilting the substrate.
The plasma processing apparatus according to items 1 to 3. 5. By making the normal line of the surface of the substrate to be processed and the propagation direction of the introduced high-frequency wave almost coincident, and by separating the direction of the applied magnetic lines of force from the microwave propagation direction at least in the vicinity of the substrate, the plasma flow to the substrate can be directed around the above-mentioned angle. 4. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus comprises: 6. The direction of propagation of the introduced high-frequency waves is made to substantially match the surface of the processed substrate, and the direction of the applied magnetic lines of force is separated from the propagation direction of the introduced high-frequency waves at least in the vicinity of the substrate, thereby directing the plasma flow toward the substrate at the angles described above. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the plasma processing apparatus is made to be incident. 7. By making the direction of propagation of the introduced high frequency wave and the direction of the lines of magnetic force substantially coincide with the surface of the processing substrate, and by making the direction of the lines of electric force applied to the vacuum container substantially match the normal direction of the substrate at least in the vicinity of the substrate, 4. The plasma processing apparatus according to claim 1, wherein the plasma flow is incident on the substrate at the angle described above. 8. The plasma processing apparatus according to claims 1 to 7, wherein the angle is variable. 9. A plasma processing apparatus as described above, characterized in that the mechanism for rotating the substrate is installed in a vacuum container. 10. A plasma processing apparatus according to claims 1 to 9, characterized in that a film is formed on at least a substrate. 11. A plasma processing apparatus according to claims 1 to 9, characterized in that an element is added to at least the surface of the substrate. 12. A plasma processing apparatus according to any one of claims 1 to 9, characterized in that it etches at least a substrate. 13. A plasma processing apparatus according to any one of claims 1 to 9, characterized in that the irregular step portions on the surface of the substrate are at least smoothed.