JP2771347B2 - Plasma chemical vapor deposition method and apparatus therefor and method for manufacturing multilayer wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ultra-highly integrated semiconductor device, and more particularly to a method for chemical vapor deposition of an insulating film.

[0002]

2. Description of the Related Art A conventional plasma enhanced chemical vapor deposition method uses TEOS and oxygen as reaction gases, applies a constant output of high-frequency power between opposed electrodes in a reaction vessel, and generates plasma of a constant intensity. Thus, a desired thin film has been formed on the substrate to be processed.

FIG. 9 shows a schematic view of a conventional plasma vapor deposition apparatus. TEOS (tetraethylorthosilicate) gas, which is a silicon raw material, is obtained by bubbling liquid TEOS 131 in a bubbler 132 with helium (He) gas whose flow rate is adjusted by a flow rate adjuster 123, and
EOS is produced by evaporation. The ozone-containing oxygen is generated by passing oxygen gas whose flow rate has been adjusted by the flow rate adjuster 120 through the ozone generator 165 to contain ozone having a concentration of about 10%. TEOS gas and ozone-containing oxygen gas are
It is introduced into the manifold 136 from the TEOS inlet 138 and the oxygen / ozone inlet 139, and the manifold 136
In the gas diffusion plate 140, and diffuses more uniformly through the shower electrode 142.
47 is sprayed on the surface. The substrate 147 is mounted on the SiC susceptor 144, is light-heated from a heating lamp 146 through a quartz plate 145, and is maintained at a temperature of about 350 ° C. The shower electrode 142 is
11. electrically isolated from other parts by 1;
A high frequency voltage of two frequencies generated by a 56 MHz high frequency power supply 129, a high-pass filter 130, a 450 kHz high frequency power supply 133 and a low pass filter 134 is applied via a matching box 135. The exhaust pipe 148 is connected to a vacuum pump 149, and the pressure in the reaction chamber 143 is maintained at several Torr.

Normally, in the above-described apparatus, first, TE
After spraying the substrate 147 from the mixed gas shower electrode 142 of the OS gas and oxygen and confirming the stability of the pressure and the like, a constant high-frequency voltage is applied to the shower electrode 142 to decompose TEOS and oxygen to form a desired surface on the substrate 147. Form a film.

[0005] In such a simple method, the step coverage of the formed film with respect to the underlying step (step coverage)
Has been found to be extremely bad (about 50%), and attempts have been made to alternately perform the plasma enhanced chemical vapor deposition and the thermal chemical vapor deposition of ozone and TEOS. FIG. 10 shows changes in the high-frequency power applied to the shower electrode 142, the number of oxygen ions in the plasma, and the ozone concentration in the source gas with respect to the film formation time when such a method is performed. While plasma chemical vapor deposition is performed and the number of oxygen ions shows the maximum value during the period when high-frequency power is applied, oxygen ozone thermal chemical vapor deposition is performed and oxygen gas is zero during the period when high-frequency power is zero. The number of ions is also zero. In addition, since the flow of ozone is started after the high-frequency power is reduced to zero, a certain time is required until the ozone concentration increases.

As described above, FIGS. 11A to 11D show how a film is formed when the plasma chemical vapor deposition method and the ozone thermal chemical vapor deposition method are alternately performed. Show.
First, a first plasma CVD film 154 is formed on the aluminum wiring 153 formed on the base substrate as shown in FIG. Next, as shown in (c), a first thermal CVD film 155 is formed to fill a narrow space between the aluminum wirings. Further, a second plasma CVD film 156 is formed as shown in FIG. These steps are repeated to form a film to a desired film thickness, and as shown in FIG.
A film having a multilayer structure is formed. In particular, in such a method, it is important that the ozone thermal CVD film 155 remains as it is.

FIG. 12 shows a method of forming a flattening insulating film for a multilayer wiring using a conventional plasma enhanced chemical vapor deposition method and a silica coating method. First, as shown in FIGS. 7A and 7B, a plasma CVD film 159 is formed on an aluminum wiring 158 formed on a substrate 157 so as to have a thickness such that voids cannot be formed in a space between wirings. I do. next,
As shown in FIG. 3C, a silica coating liquid is applied, and a heat treatment at 100 ° C. for evaporating the solvent and a heat treatment at about 300 ° C. for improving the film quality are performed to form a silica coating film (single application) 160. Since the flatness is insufficient as it is, the steps of silica coating and heat treatment performed in FIG. (C) are repeated two or more times as shown in FIG.
161 is formed. Further, etch back is performed by using a normal reactive ion etching method (RIE). At this time,
When the plasma CVD oxide film on the aluminum wiring is exposed, oxygen atoms are supplied from the oxide film, so that the etching rate of the silica coating film increases, and as shown in FIG. It is known that the space between the aluminum wiring steps is dented. Finally, the plasma CVD film 163 is formed again to complete the interlayer film.

In the above-mentioned conventional plasma enhanced chemical vapor deposition method, step coverage is required.
However, the space between sub-micron aluminum wirings could not be buried. In order to bury the space between the sub-micron aluminum wirings, as shown in FIG. 11, a plasma chemical vapor deposition method and a thermal chemical vapor deposition method of ozone and TEOS are alternately performed, as shown in FIG. It is necessary to form a silica coating film many times. However, an ozone-TEOS thermal CVD film or a silica coating film formed under a reduced pressure of about 10 Torr has a large amount of water contained in the film, and has problems in mechanical strength, insulation properties, and the like. There is a drawback that a connection failure of a through hole connecting the upper aluminum wiring occurs. Further, in the method of etching back the silica coating film as shown in FIG. 12, the step of forming the silica coating film and the step of etching back are very complicated,
There is also a disadvantage that the number of steps is increased and the yield is reduced.

[0008]

According to the plasma chemical vapor deposition method of the present invention, at least a part of the raw material gas contains an organic silane and oxygen or oxygen containing ozone, and the intensity of plasma irradiation on the substrate surface is periodically changed. While forming a desired thin film. At this time, as a means for changing the plasma irradiation intensity, two types of plasma generation state and non-generation state are repeatedly performed, and plasma irradiation and non-irradiation are repeatedly performed on the substrate surface. A high frequency voltage having the above frequency is applied, and part or all of the high frequency voltage is periodically changed.

Further, the plasma chemical vapor deposition apparatus of the present invention comprises a mechanism for supplying an organic silane, a mechanism for supplying oxygen or oxygen containing ozone, a mechanism for periodically changing the plasma generation intensity, or It has a plurality of plasma irradiation mechanisms provided in the reaction vessel and having different plasma intensities, and a mechanism for moving a substrate between the plurality of plasma irradiation mechanisms. Further, the plasma enhanced chemical vapor deposition apparatus of the present invention includes a mechanism for supplying organic silane and ozone-containing oxygen to the wafer surface, an oxygen plasma ion source, and a mechanical or electromagnetic means for periodically changing the plasma irradiation intensity. Shutter. Further, in the plasma enhanced chemical vapor deposition apparatus of the present invention, high frequency voltages of two or more frequencies are applied to opposing electrodes in the reaction vessel, and a part or all of the high frequency power is periodically changed. Has a mechanism.

Further, the method for manufacturing a multilayer wiring according to the present invention comprises:
3. An insulating film formed on a metal wiring by a chemical vapor deposition method according to claim 1 or 2, wherein the intensity of plasma irradiation on the substrate surface is periodically changed using organic silane and oxygen as source gases. Forming a film having a thickness equal to or greater than the height of the metal wiring, a step of forming a flattening film such as a resist film and an organic silica film, and a step of etching back by a reactive ion etching method.

[0011]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic vertical sectional view of a plasma enhanced chemical vapor deposition apparatus showing a first embodiment of the present invention. FIG. 2 shows FIG.
1 shows the operation of the plasma enhanced chemical vapor deposition apparatus of FIG. 1 with respect to the applied RF power, the number of oxygen ions, and the change over time of the ozone concentration. FIG. 3 is a model diagram schematically illustrating the principle of the present invention. FIG. 4 shows the state when the operation as shown in FIG. 2 is performed.
FIG. 5 is a longitudinal sectional view showing a lapse of time and a growth process of the film.
Is the high-frequency on-time (t) when the operation as shown in FIG. 2 is performed.
_ON ), the relationship between the film growth rate, the step coverage, and the absorption coefficient of OH groups.

In the plasma-enhanced chemical vapor deposition apparatus shown in FIG. 1, ethyl silicate (hereinafter referred to as TEOS) gas as a silicon raw material is obtained by mass-flowing liquid TEOS supplied from a TEOS tank not shown in FIG. The flow rate is controlled by a liquid flow controller 3 of a mold, completely vaporized by an evaporator 12, and mixed with helium whose flow rate is controlled by a flow controller 4 to be produced. The ozone-containing oxygen is obtained by converting the oxygen whose flow rate has been adjusted by the flow rate controller 2 into a silent discharge type ozone generator 11.
, And containing 1 to 10% of ozone. The TEOS gas and the ozone-containing oxygen gas thus generated are introduced into the manifold 15 from the TEOS inlet 14 and the ozone inlet 13. In the manifold, these gases are mixed and diffuse almost uniformly by hitting the gas diffusion plate 17. Furthermore, when it hits the shower electrode 19, it is more uniformly dispersed,
8 is sprayed on the surface. The substrate 28 is mounted on the SiC susceptor 21, and the heating lamp 2 passes through the quartz plate 22.
3 and lightly heated and maintained at a temperature of about 200 to 450 ° C. The shower electrode 19 is electrically insulated from other parts by the insulating ring 18 and
Hz high frequency power supply 39 and high pass filters 38, 4
50 kHz high frequency power supply 36 and low pass filter 3
The high frequency voltages of the two frequencies generated in 5 are applied via the matching box 37. The exhaust pipe 24 is connected to a vacuum pump 26, and the pressure in the reaction chamber 20 is maintained at 0.1 to several tens Toor.

In this embodiment, in a matching box 37 connected to the shower electrode 19, a mixer section for mixing high frequency voltages of two frequencies, a matching section for impedance matching, a dummy load, There is a switch so that the high frequency voltage applied to the shower electrode 19 can be turned on and off. In addition, it is also possible to change the output of the high-frequency power supplies 35 and 36 in synchronization with the pulse generated by the pulse generator 40 and change the high-frequency voltage applied to the shower electrode 19. These operations are controlled by the process controller 41, including the substrate temperature, the reaction chamber pressure, and the like. The transmission paths of these control signals and pulses are shown by broken lines in FIG.

Here, the operation of the present apparatus when the high-frequency voltage applied to the shower electrode 19 is turned on and off at a cycle of 1 second will be described with reference to FIGS.

The lower part of FIG. 2 shows the relationship between the film forming time and the high frequency power. Time t during which high frequency power is on
_{During ON} , plasma is generated between the shower electrode 19 and the substrate 28 or the SiC susceptor 21, and oxygen or ozone is decomposed to generate oxygen ions. The middle part of FIG. 2 shows the change in the number of oxygen ions. A certain period of time is required from the start of the application of the high-frequency power to the stabilization of the plasma state, resulting in a shoulder waveform. Since ozone is more unstable than oxygen, the ionization efficiency by applying high frequency power is high. Therefore, the number of ozone molecules in the plasma is
As shown in the upper part of FIG. 2, when the high-frequency power is on, it is considerably reduced.

FIGS. 3A and 3B are model diagrams showing the state near the substrate surface when the high frequency is turned on and off, respectively. When the high frequency is turned on, plasma is generated between the shower electrode 19 and the substrate 28 in FIG. In the plasma
Oxygen molecules and TEOS molecules are composed of 45 electrons and 4 oxygen ions.
7, dissociates into TEOS dissociating molecules 46, oxygen radicals 55 and the like. In addition, a sheath voltage is generated between the plasma and the substrate, and the oxygen ions 47 are accelerated by this voltage, drift, and collide with the substrate surface. TEOS dissociation molecule 46
Also diffuses toward the substrate surface, and the film-forming precursor 5 is formed on the surface of the formed film by thermal decomposition or decomposition by oxygen ion bombardment.
It becomes 0. Further, on the surface of the formation film, it reacts with oxygen radicals or the like, and the formation film 51 is formed. At this time, since the surface of the formed film 51 is subjected to a great deal of oxygen ion bombardment, the life of the film forming precursor 50 is considerably short, and the density on the formed film surface is low. Further, the oxygen ion bombardment has an effect of hardening the formed film 51, has a good film quality, and is useful for forming a film having a compressive stress.

Now, once the high frequency is turned on (FIG. 3)
(See (b)), the number of electrons and oxygen ions decreases rapidly, but the TEOS dissociation molecule 46 and oxygen radical 55
It still remains. These are diffused to the surface of the formation film 51 to become the film formation precursor 50, and then decrease. further,
The TEOS molecules 54 and the ozone molecules 56 also diffuse toward the film surface and react to become TEOS dissociated molecules or film-forming precursors. On the surface of the formation film 51, since the film formation reaction is only a thermochemical reaction, the film formation precursor exists at high density on the formation film surface, and the film formation precursor pseudo liquid layer 59 is formed. Since the film-forming precursor pseudo-liquid layer 59 exhibits liquid properties,
The thickness of the lower portion of the side surface of the step formed on the substrate 52 is increased, and the inclination of the side surface of the step is reduced.

FIG. 4 is a longitudinal sectional view showing a model of the lapse of time and film formation when high-frequency power is applied as shown in FIG. First, as shown in FIG.
_{During ON} (0.5 seconds in FIG. 2), the high frequency is turned on, and a first plasma CVD film 60 of about 10 nm is formed.
Next, as shown in FIG. 4B, a first thermal CVD film 62 is formed during a time t _OFF (0.5 seconds). The time T _OFF is as short as 0.5 seconds, and the thickness of the first thermal CVD film 62 is about 1 nm. Therefore, it is improved by oxygen ion bombardment or the like in the early _stage of the next t _ON , and the film quality becomes equivalent to that of the plasma CVD film. Therefore, as shown in FIG. 4C, the improved first thermal CVD film 62 becomes indistinguishable from the first plasma CVD film 60, and the first plasma C
It is taken into the VD film 60. The thermal CVD film can fill the narrow space between the wirings and the corner of the lower part of the step by the effect of the film forming precursor pseudo-liquid layer, and can smooth the shape. As a result, the formed film 6 having the same shape as the thermal CVD film and the same film quality as the plasma CVD film before the growth of the second plasma CVD film
4 is formed. Since the lower portion of the step has a rounded shape due to the formation film 64 before the second plasma CVD film growth, the second plasma CV formed thereon is formed.
The shape of the D film 63 is also rounded as shown in FIG.
Since the formation film 64 before the growth of the second plasma CVD film and the second plasma CVD film 63 are indistinguishable, in the subsequent growth stage (d) of the second thermal CVD film 65, the lower film is the second plasma CVD film. It becomes the formed film 66 after the growth.

By repeating the above steps many times, as shown in FIG. 4 (e), there is no void in the space between the aluminum wirings 61, and a good and almost equivalent to the plasma CVD film is obtained. A film with a film quality can be embedded.

FIG. 5 shows a duty ratio D (D = t _ON / (t _ON + t _OFF ) ×) calculated from t _ON and t _OFF in FIG.
100 (%)) and the relationship between the growth rate, the step coverage, and the absorption coefficient of OH groups in the film. FIG.
From the bottom, it can be seen that the growth rate increases as D increases, and from the middle, the step coverage begins to deteriorate when D exceeds 50%, and from the top, the OH groups show that D exceeds 40%. It turns out that it becomes small enough. From FIG.
Although the step coverage and the water content in the film (the OH group absorption coefficient in the film) tend to be contradictory, the two values are set by setting the value of the duty ratio D to an appropriate range (40 to 60% in this embodiment). It can be seen that it is possible to prevent damage.

In this embodiment, ethyl silicate (TEOS: Si (OC ₂ H ₅ ) ₄ ) was used as the organic silane gas, but tetramethylsilane (TMS: Si (C
H ₃ ) ₃ ), tetramethylcyclotetrasiloxane (T
MCTS), octamethylcyclotetrasiloxane (O
MCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH (OC ₂ H ₅ ) ₃ ), and tridimethylaminosilane (SiH (N (CH ₃ ) ₂ ) ₃ ). Is obtained. Also, even if ozone is not present in the reaction gas, the lifetime of oxygen radicals and TEOS dissociated molecules is considerably long,
A similar result can be obtained by appropriately selecting the value of the duty ratio. Further, the same result can be obtained when a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, a hydrogen compound such as phosphorus, boron, arsenic, or antimony or an organic compound is mixed in the reaction gas.

Further, in this embodiment, only the high-frequency power applied to the shower electrode 19 is changed. However, in synchronization with the pulse generated by the pulse generator 40, the high-frequency power, reaction chamber pressure, substrate temperature, gas flow rate By changing the above, a better step coverage can be obtained.

FIG. 6 shows a reaction chamber of the plasma enhanced chemical vapor deposition apparatus according to the second embodiment of the present invention, wherein (a) is a plan view thereof, and (b) is a two-dot chain line AA 'of (a). FIG. (A) is a plan view taken along a dashed line BB 'in (b).

The reaction chamber 72 is divided into six fan-shaped regions, and the fan shape in the direction of 3 o'clock of the clock is a thermal CVD region 70, and the plasma CVD region, the thermal CVD region, and the plasma CVD region are clockwise. They are arranged alternately with the CVD regions 166. The substrate 69 is mounted on a susceptor 71 rotating about a rotation axis 79, and a thermal CVD region and a plasma C
It passes through the VD region alternately.

The thermal CVD region 70 has a TEOS inlet 7
TEOS gas and ozone-containing oxygen are introduced from 3 and the ozone inlet 75, are uniformly dispersed by the gas dispersion plate 83 and the shower injector 81, and are then supplied to the surface of the substrate 69. Since the substrate 69 is heated to about 350 ° C. by the heater 80 provided on the back side of the susceptor 71, a thermal CVD film of ozone and TEOS grows on the substrate.

The plasma CVD region 166 contains TEOS
TEOS gas and acid gas are introduced from the inlet 73 and the oxygen inlet 74, are uniformly dispersed by the gas dispersion plate 83 ′ and the shower electrode 78, and are supplied to the surface of the substrate 69 ′. The shower electrode 78 is electrically insulated from other parts of the reaction chamber by an insulating ring 82 and an insulator 76.
13.56 MHz or 450 kHz from F introduction terminal 77
A high frequency voltage of z is applied. By applying these high-frequency voltages, plasma is excited between the shower electrode 78 and the substrate 69 'or the susceptor 71, and the plasma CV
A D film is formed. As described above, the substrate 69 and the rotating susceptor 71 alternately pass through the plasma CVD region and the thermal CVD region, so that the plasma CVD film and the thermal CVD film are formed alternately. At this time, if the rotation speed of the susceptor 71 is set to about 10 rotations per minute, the thermal CVD
The thickness of the thermal CVD film formed in the region 70 is about 2 nm, and the film is irradiated with plasma at the initial stage of film formation in the adjacent plasma CVD region, and the film quality is the same as that of the plasma CVD film. In this manner, as described with reference to FIG. 4, the film quality is the same as that of the plasma CVD film, and a CVD film having excellent step coverage and step filling properties is formed.

In this embodiment, the reaction chamber is divided into six regions. However, the number of regions may be any number as long as it is two or more. Further, the type of the film formation region is set to the thermal CVD region and the plasma C region.
Although two types of VD regions are used, two or more types may be provided depending on the frequency of high frequency applied to the plasma CVD region or the applied power.

Further, in this embodiment, the susceptor 71 has a flat turntable shape, and a shower injector and a shower electrode are provided above. The susceptor has a cylindrical or polygonal column shape, and a substrate is mounted on the outer surface thereof. Similar results can be obtained by providing a shower electrode or the like facing the substrate.

In this embodiment, ethyl silicate (TEOS: Si (OC ₂ H ₅ ) ₄ ) is used as the organic silane gas, but tetramethylsilane (TMS: Si (C
H ₃ ) ₃ ), tetramethylcyclotetrasiloxane (T
MCTS), octamethylcyclotetrasiloxane (O
MCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH (OC ₂ H ₅ ) ₃ ), and tridimethylaminosilane (SiH (N (CH ₃ ) ₂ ) ₃ ). Is obtained. Also, even if ozone is not present in the reaction gas, the lifetime of oxygen radicals and TEOS dissociated molecules is considerably long,
A similar result can be obtained by appropriately selecting the value of the duty ratio. Further, the same result can be obtained when a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, a hydrogen compound such as phosphorus, boron, arsenic, or antimony or an organic compound is mixed in the reaction gas.

FIG. 7 schematically shows a plasma enhanced chemical vapor deposition apparatus according to Embodiment 3 of the present invention. The ion source cavity 93 is supplied with oxygen gas O ₂ whose flow rate is adjusted by the flow rate adjuster 103 and argon gas Ar whose flow rate is adjusted by the flow rate adjuster 87, and the pressure is maintained at p = 1 mTorr. In addition, a microwave having a frequency of 2.45 GHz is supplied from a microwave power supply 84 via a waveguide 85 and a transmission window 86. Further, electron cyclotron resonance (ECR) occurs in the ion source cavity 93 due to the 875 Gauss magnetic field generated by the main electromagnet coil 94, and oxygen plasma having a high ionization rate is generated. Oxygen ions are extracted into the reaction chamber 95 by the diverging magnetic field of the main electromagnet coil 94 and the auxiliary coil 96, and irradiated to the supply 106.

TEOS gas as a silicon raw material is 80%.
TEOS11 kept at constant temperature and kept in constant temperature container 112
The TEOS gas evaporated from 1 is flow-regulated by the flow controller 113 and introduced into the reaction chamber from the TEOS inlet 107. The oxygen gas whose flow rate has been adjusted by the flow rate adjuster 101 passes through the ozone generator 98 to become ozone-containing oxygen, and is supplied from the ozone inlet 97. The substrate 106
It is mounted on a susceptor 109 and heated to 300 ° C. by a heater 110. The pressure in the reaction chamber is
The flow rate is adjusted by the flow rate adjuster 88, and the Ar inlet 10 is adjusted.
Argon gas for dilution supplied from 8 and vacuum pump 10
5 keeps it at about 1 mTorr.

In the plasma CVD mounting of this embodiment, first, oxygen plasma is generated in the ion source cavity 93. The current flowing through the auxiliary coils 96 and 96 'is set to a small value in a direction in which a magnetic field is generated from the ion source toward the substrate, and is set to a level at which the irradiation of the oxygen plasma becomes uniform. Also,
The current flowing through the reflective magnet coils 102 and 102 'is also set to a small value in a direction in which a magnetic field is generated from the ion source toward the substrate. In this state, when oxygen ions are irradiated to the surface of the substrate 106 and TEOS gas is supplied, ECR plasma vapor phase growth occurs, and a plasma CVD film having good film quality is formed. Of about 10 nm. Next, the auxiliary coil 9
6, 96 ', so that a mirror-type magnetic field is formed near the exit of the ion source cavity, and electrons and ions flowing out of the plasma are rebounded by the divergent magnetic field of the main electromagnet coils 94, 94'. To Then
On the supply 106, only neutral particles such as oxygen radicals and oxygen molecules diffused from the TEOS gas and the ion source are supplied, and only a thermal CVD reaction occurs, thereby forming a film with good step coverage. Therefore, the auxiliary coil 96,
When the current flowing through 96 'is changed at a cycle of about 1 second to 10 seconds, the number of oxygen ions applied to the substrate 106 changes periodically, and a plasma CVD film and a thermal CVD film are alternately formed. Also, the thermal CVD film is modified into a plasma CVD film to form a plasma CVD film having excellent step coverage and step embedding property as in FIG.
Particularly, in this embodiment, since the pressure in the reaction chamber is set to about 1 mTorr, it is possible to embed a groove having a large aspect ratio.

In the above example, the mirror type magnetic field formed by the auxiliary coil 94 is used as a means for changing the oxygen ions applied to the substrate 106.
A cusp type magnetic field formed by the susceptor 109 and a cusp type magnetic field formed by applying a positive voltage to the susceptor 109 may be used. Also, although not shown in FIG.
Similar results can be obtained using a mechanical shutter.
However, in the case of using a mechanical shutter or the like to prevent the diffusion of oxygen radicals, the ozone generator 9 is used.
Needless to say, it is better to operate ozone 8 to supply ozone to the vicinity of the substrate, to promote thermochemical vapor deposition, and to promote the growth of thermal CVD films.

In the above embodiment, an electron cyclotron resonance (ECR) ion source is used as the ion source. However, if the intensity of oxygen ions can be changed, similar results can be obtained regardless of the type. .

In this embodiment, ethyl silicate (TEOS: Si (OC ₂ H ₅ ) ₄ ) was used as the organic silane gas, but tetramethylsilane (TMS: Si (C
H ₃ ) ₃ ), tetramethylcyclotetrasiloxane (T
MCTS), octamethylcyclotetrasiloxane (O
MCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH (OC ₂ H ₅ ) ₃ ), and tridimethylaminosilane (SiH (N (CH ₃ ) ₂ ) ₃ ). Is obtained. Further, the same result can be obtained when a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, a hydrogen compound such as phosphorus, boron, arsenic, or antimony or an organic compound is mixed in the reaction gas.

FIG. 8 is a longitudinal sectional view showing a method of flattening an interlayer insulating film of an aluminum multilayer wiring based on Embodiment 4 of the present invention.

In this embodiment, first, an aluminum wiring 114 is formed on a substrate 115 on which a semiconductor element and the like are formed.
(A)). Next, using the plasma enhanced chemical vapor deposition apparatus of the first embodiment of the present invention, the CVD film 116 of the present invention is formed to be thicker than the aluminum wiring as shown in FIGS. A resist 117 is applied and hard baked. Etchback is performed using a reactive ion etching method adjusted so that the resist 117 and the CVD film 116 of the present invention have the same etching rate to make the surface of the CVD film flat. Then, the planarized interlayer film 118 is formed.
Is completed.

In this embodiment, a resist is used for flattening, but the same result can be obtained by using polystyrene, organic SOG, or the like. Also, if a polishing method is used as the flattening method, good flatness can be obtained over the entire surface of the substrate.

FIG. 13 shows a method of operating the fifth embodiment using the plasma enhanced chemical vapor deposition apparatus of the first embodiment shown in FIG. In FIG. 13, 13.56 MHz high frequency power, 4
It shows 50 kHz high frequency power, ion current density, and average ion energy. However, each value is normalized by the maximum value of each value.

In the method of operation of this embodiment, as shown in the first and second stages from the bottom in FIG. 13, the high frequency power supplies 39 and 36 having two frequencies of 13.56 MHz and 450 kHz in FIG.
, A pulse is sent from the pulse generator 40 so that the high-frequency maximum outputs of the two frequencies have opposite phases,
A voltage is applied to the shower electrode 19. Then, Figure 1
3 As in the third and fourth stages from the bottom, the change in ion current density is small, but the average ion energy is 450 kHz.
When the high-frequency power is at its maximum, it takes the maximum value and 13.56M
It is possible to minimize the frequency when the high-frequency power is at the maximum.
This is because when the frequency of the applied high frequency is high, the voltage (sheath voltage) generated between the plasma and the substrate decreases. Thus, when only the ion energy is changed without changing the ion current density, the intensity of the ion bombardment changes periodically, there is no deterioration of the film quality, and the step coverage and the groove filling property are improved. 13 is the same as in Example 1, but the change in the film growth rate is
There is an advantage that it can be made as small as possible.

In this embodiment, the apparatus shown in FIG. 1 is used. However, similar results can be obtained by using the apparatus shown in FIGS. 6 and 7 shown in other embodiments of the present invention.

In this embodiment, ethyl silicate (TEOS: Si (OC ₂ H ₅ ) ₄ ) was used as the organic silane gas, but tetramethylsilane (TMS: Si (C
H ₃ ) ₃ ), tetramethylcyclotetrasiloxane (T
MCTS), octamethylcyclotetrasiloxane (O
MCTS), hexamethyldisilazane (HMDS), triethoxysilane (SiH (OC ₂ H ₅ ) ₃ ), and tridimethylaminosilane (SiH (N (CH ₃ ) ₂ ) ₃ ). Is obtained. Also, even if ozone is not present in the reaction gas, the lifetime of oxygen radicals and TEOS dissociated molecules is considerably long,
A similar result can be obtained by appropriately selecting the value of the duty ratio. Further, the same result can be obtained when a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, a hydrogen compound such as phosphorus, boron, arsenic, or antimony or an organic compound is mixed in the reaction gas.

Further, in this embodiment, only the high frequency power applied to the shower electrode 19 is changed. However, in synchronization with the pulse generated by the pulse generator 40, the high frequency power, reaction chamber pressure, substrate temperature, gas flow rate By changing the above, a better step coverage can be obtained.

[0045]

As described above, in the plasma enhanced chemical vapor deposition method of the present invention, while periodically changing the plasma irradiation intensity on the substrate surface, the thermal CVD film of ozone and TEOS having excellent step coverage is obtained. Formation and its thermal CVD
Modification of the film to a film quality equivalent to that of a plasma CVD film, and
Since the plasma TEOS / CVD film is repeatedly formed, it has excellent step coverage so that it can embed fine grooves with a large aspect ratio, has low moisture content and stress in the film, and has good film quality. Having plasma C
There is an effect that a VD film can be formed.

Further, the plasma enhanced chemical vapor deposition apparatus of the present invention includes a mechanism for supplying an organic silane, a mechanism for supplying oxygen or oxygen containing ozone, a mechanism for periodically changing the plasma generation intensity, or one mechanism. A plurality of plasma irradiation mechanisms having different plasma intensities provided in a reaction vessel, a mechanism for moving a substrate between the plurality of plasma irradiation mechanisms, or a mechanical or electromagnetic mechanism for periodically changing the plasma irradiation intensity Since the present invention has an effective shutter, the plasma enhanced chemical vapor deposition method of the present invention can be effectively realized.

Further, the method for manufacturing a multilayer wiring according to the present invention uses the chemical vapor deposition method described in this patent, which uses organosilane and oxygen as source gases and periodically changes the intensity of plasma irradiation on the substrate surface. Since the method includes a step of forming an insulating film having no void between metal wirings to a thickness equal to or greater than the height of the metal wirings, an interlayer film is formed in comparison with a conventional method of manufacturing a multilayer wiring using a silica coating film. The amount of water in the inside is greatly reduced, and crack resistance is improved, stress migration is reduced, and conduction characteristics of through holes are improved. Further, since the number of steps in the method for manufacturing a multilayer wiring according to the present invention is significantly reduced as compared with the conventional method, the yield is improved and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a plasma enhanced chemical vapor deposition apparatus according to a first embodiment of the present invention.

FIG. 2 shows the operation of the plasma-enhanced chemical vapor deposition apparatus of FIG. 1 with respect to changes in applied high-frequency power, the number of oxygen ions, and the ozone concentration over time.

FIG. 3 is a model diagram schematically showing the principle of the present invention.

FIG. 4 is a longitudinal sectional view showing a lapse of time and a film growth process when the operation as shown in FIG. 2 is performed.

FIG. 5 is a diagram showing the relationship between the ratio (duty D) of the high-frequency ON time (t _ON ), the film growth rate, the step coverage, and the absorption coefficient of the OH group when the operation as shown in FIG. 2 is performed.

6A and 6B show a reaction chamber of a plasma enhanced chemical vapor deposition apparatus according to Embodiment 2 of the present invention, wherein FIG. 6A is a schematic plan view and FIG.
Is a longitudinal sectional view taken along a two-dot chain line AA 'in FIG.
(A) is a (b) plan view taken along a chain line BB '.

FIG. 7 is a longitudinal sectional view schematically illustrating a plasma enhanced chemical vapor deposition apparatus according to a third embodiment of the present invention.

FIG. 8 is a longitudinal sectional view illustrating a method of planarizing an interlayer insulating film of an aluminum multilayer wiring according to a fourth embodiment of the present invention.

FIG. 9 is a schematic view of a conventional plasma enhanced chemical vapor deposition apparatus.

FIG. 10: Plasma enhanced chemical vapor deposition method, ozone and TE
Changes in the high-frequency power applied to the shower electrode, the number of oxygen ions in the plasma, and the ozone concentration in the source gas with respect to the film forming time in the conventional method alternately using the thermal chemical vapor deposition of the OS. FIG.

FIG. 11 is a longitudinal sectional view showing film growth in the case where plasma chemical vapor deposition and ozone thermal chemical vapor deposition are alternately performed.

FIG. 12 is a longitudinal sectional view showing a conventional method for forming a planarized insulating film for a multilayer wiring using a plasma enhanced chemical vapor deposition method and a silica coating method.

FIG. 13 is a time change diagram of high-frequency power and the like, showing a method of operation of Example 5 using the plasma enhanced chemical vapor deposition apparatus of Example 1 of FIG. 1;

Claims (8)

(57) [Claims] 1. A method for forming a desired thin film while periodically changing the intensity of plasma irradiation on a substrate surface, the method comprising the steps of:
When the plasma irradiation intensity is high, a plasma chemical vapor deposition film is generated, and when the previous plasma irradiation intensity is low, the thermal chemical vapor deposition film is changed to a film quality equivalent to that of the plasma chemical vapor deposition film. and quality, plasma chemical vapor deposition that features be formed as substantially a plasma chemical vapor deposition film using the film as a whole. 2. The method according to claim 1, wherein the raw material gas contains at least a portion of an organic silane and oxygen containing ozone and forms a desired thin film while periodically changing the plasma irradiation intensity on the substrate surface. to generate a plasma chemical vapor deposition film, modified the previous thermal chemical vapor deposition film that was generated when the plasma irradiation intensity is weak in the same quality and the plasma chemical vapor deposition film, overall the film A plasma enhanced chemical vapor deposition method characterized by being formed substantially as a plasma enhanced chemical vapor deposition film. 3. The plasma-enhanced chemical vapor deposition method according to claim 1, wherein the periodic change of the plasma irradiation intensity is performed by repeating a generation state and a non-generation state of plasma. 4. The plasma chemical vapor deposition method according to claim 1, wherein the periodic change of the plasma irradiation intensity is performed by repeating plasma irradiation and non-irradiation. 5. A reaction vessel on which a substrate on which a chemical vapor deposition film is to be formed is placed, a mechanism for supplying organic silane to the reaction vessel, a mechanism for supplying oxygen, and a high-frequency power to the organic silane and oxygen. A mechanism for generating plasma by application, a mechanism for changing the high-frequency power to periodically change the plasma irradiation intensity, and a thermochemical vapor deposition film formed when the plasma irradiation intensity is low, wherein the plasma intensity is high. A mechanism for controlling a cycle and a duty ratio of a change in the plasma irradiation intensity so as to form a film having a thickness that can be modified to a film of the same quality as a plasma chemical vapor deposition film formed when the plasma intensity is strong. Plasma chemical vapor deposition apparatus characterized by the following. 6. A reaction vessel for mounting a substrate on which a chemical vapor deposition film is to be formed, a mechanism for supplying an organic silane to the reaction vessel, a mechanism for supplying ozone-containing oxygen, A mechanism for applying high-frequency power to generate plasma, a mechanism for changing the high-frequency power to periodically change the plasma irradiation intensity, and a thermochemical vapor deposition film formed when the plasma irradiation intensity is low. When the plasma intensity is high, the period and the duty ratio of the change in the plasma irradiation intensity are controlled so that the film is formed to have a film thickness that can be modified to have the same quality as the plasma chemical vapor deposition film formed when the plasma intensity is high. A plasma enhanced chemical vapor deposition apparatus having a mechanism for performing 7. The plasma enhanced chemical vapor deposition apparatus according to claim 5, wherein the mechanism for periodically changing the plasma irradiation intensity repeats a generation state and a non-generation state of plasma. 8. The plasma enhanced chemical vapor deposition apparatus according to claim 5, wherein the mechanism for periodically changing the plasma irradiation intensity repeats plasma irradiation and non-irradiation.