JPH0897208A - Plasma chemical vapor deposition method and its equipment and manufacture of multilayered interconnection - Google Patents

Abstract

PURPOSE: To provide a plasma CVD film wherein step coverage is excellent, submicron space between aluminum wirings can be embedded, water content in a film is little, and crack resistance, stress migration resistance, through holes, and insulation are excellent, and realize the improvement of yield, the cost reduction by reducing the number of processes, and the high reliability of a multilayered interconnection. CONSTITUTION: TEOS and ozone are used as reaction gas. Pulses of a 40-80% duty factor are produced at 1 second intervals by a pulse generator 40. High frequency power applied to a shower electrode 19 from high frequency power supplies 36 and 39 is switched at 1 cycle per second for a duty factor of 40-60%. Thereby the following are repeated, the formation of a thermal CVD film of TEOS and ozone of about 1nm in thickness, the modification of the thermal CVD film to a plasma film, and the formation of a plasma TEOS CVD film of about 10nm in thickness. Thereby an interlayer insulating film is formed which has the same film quality as the plasma TEOS CVD film and is excellent in step coverage and fine wiring embedding property.

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 chemical vapor deposition method for 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 and applies a constant output of high-frequency power between opposing electrodes in a reaction vessel to generate plasma of a constant intensity. The desired thin film was formed on the substrate to be processed.

FIG. 9 shows a schematic view of a conventional plasma vapor phase growth apparatus. TEOS (tetraethyl orthosilicate) gas as a silicon raw material is obtained by bubbling liquid TEOS 131 contained in a bubbler 132 with helium (He) gas whose flow rate is adjusted by a flow rate controller 123, and
EOS is produced by evaporation. Ozone-containing oxygen is generated by passing the oxygen gas whose flow rate is adjusted by the flow rate controller 120 through the ozone generator 165 and containing ozone at a concentration of about 10%. TEOS gas and ozone-containing oxygen gas are
It is introduced into the manifold 136 through the TEOS inlet 138 and the oxygen / ozone inlet 139, and the manifold 136
The gas is mixed inside, diffuses upon hitting the gas diffusion plate 140, and is evenly dispersed through the shower electrode 142.
Sprayed on the surface of 47. The substrate 147 is mounted on the SiC susceptor 144, is optically heated by the heating lamp 146 through the quartz plate 145, and is maintained at a temperature of about 350 ° C. The shower electrode 142 has an insulating ring 14
13. It is electrically insulated from other parts by 1.
The high frequency voltage of two frequencies generated by the 56 MHz high frequency power supply 129 and the high pass filter 130, the 450 kHz high frequency power supply 133 and the low pass filter 134 is applied through the matching box 135. The exhaust pipe 148 is connected to the vacuum pump 149, and the pressure of the reaction chamber 143 is maintained at several Torr.

Usually, in the above-mentioned apparatus, first, TE
A mixed gas of OS gas and oxygen is sprayed from the shower electrode 142 to the substrate 147, and after confirming the stability of pressure and the like, a constant high-frequency voltage is applied to the shower electrode 142 to remove TEOS.
And oxygen is decomposed to form a desired film on the substrate 147.

In such a simple method, the step coverage with respect to the underlying step of the formed film (step coverage)
It has been found that is extremely bad (about 50%), and it has been attempted to alternately perform the plasma chemical vapor deposition method and the thermochemical vapor deposition method of ozone and TEOS. FIG. 10 shows changes in 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. The number of oxygen ions is maximum during plasma chemical vapor deposition and high frequency power is applied, but ozone thermal chemical vapor deposition is performed and oxygen radio frequency is zero during high frequency power. The number of ions is also zero. Further, since the high-frequency power is set to zero and ozone starts to flow, it takes a certain time until the ozone concentration rises.

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, the first plasma CDV film 154 is formed on the aluminum wiring 153 formed on the base substrate as shown in (b). Next, as shown in (c), a first thermal CVD film 155 is formed to fill the narrow space between the aluminum wirings. Further, as shown in (d), the second plasma CVD film 156 is formed. By repeating such steps, a film is formed to a desired film thickness, and as shown in FIG.
A multi-layered film is formed. Particularly, 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 planarizing insulating film for a multi-layer wiring using the conventional plasma chemical vapor deposition method and silica coating method. First, as shown in Figures (a) and (b),
On the aluminum wiring 158 formed on the substrate 157, the plasma CVD film 159 is formed to a thickness such that no void can be formed in the space between the wirings. Next, apply a silica coating solution as shown in FIG.
A heat treatment at 00 ° C. and a heat treatment at about 300 ° C. for improving the film quality are performed to form a silica coating film (one-time coating) 160.
Since the flatness is not sufficient as it is, the silica coating and heat treatment steps performed in FIG. 6C are performed as shown in FIG.
Silica coating film (applied multiple times) 16 times
1 is formed. Further, it is etched back 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 film 162 is dented in the space between aluminum wiring steps. Finally, the plasma CVD film 163 is formed again to complete the interlayer film.

[0008]

The conventional plasma-enhanced chemical vapor deposition method described above has a step coverage.
Was extremely bad, and it was not possible to fill the space between the submicron aluminum wires. In order to bury the space between the submicron aluminum wirings, the plasma chemical vapor deposition method and the thermochemical vapor deposition method of ozone and TEOS are alternately performed as shown in FIG. 11, or as shown in FIG. It is necessary to form the silica coating film many times. However, the ozone-TEOS thermal CVD film and the silica coating film formed under a reduced pressure of about 10 Torr have a large amount of water contained in the film and have problems in mechanical strength, insulation characteristics, etc. There is a drawback that a connection failure of a through hole connecting the upper layer 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 etching back step are very complicated,
It also has the drawback of increasing the number of steps and lowering the yield.

[0009]

According to the plasma chemical vapor deposition method of the present invention, at least a part of a source gas contains organic silane and oxygen or oxygen containing ozone, and the intensity of plasma irradiation on a substrate surface is periodically changed. While forming a desired film. At this time, as a means for changing the plasma irradiation intensity, the generation state and the non-generation state of the plasma are repeatedly performed, the irradiation and non-irradiation of the plasma to the substrate surface are repeated, and the opposite electrodes in the reaction vessel are connected to each other. A high frequency voltage having a frequency of at least one kind is applied, and a part or all of the high frequency power is periodically changed.

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

Further, the method of manufacturing a multilayer wiring according to the present invention is
An insulating film is formed on a metal wiring by the chemical vapor deposition method according to claim 1 or 2 in which organic silane and oxygen are used as source gases and the plasma irradiation intensity on the substrate surface is periodically changed. It includes a step of forming a film having a film thickness equal to or larger than the height of the metal wiring, a step of forming a flattening film such as a resist film or an organic silica film, and a step of etching back by a reactive ion etching method.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 system showing Example 1 of the present invention. FIG. 2 shows the first
The operation of the plasma-enhanced chemical vapor deposition apparatus in the figure is represented with respect to the applied high-frequency power, the number of oxygen ions, and the ozone concentration with time. FIG. 3 is a model diagram showing the outline of the principle of the present invention. FIG. 4 shows a case where the operation shown in FIG. 2 is performed.
6 is a vertical cross-sectional view showing a time course and a film growth process, and FIG.
Shows the high frequency on-time (t
The relationship between the ratio of _ON ) (duty D), the film growth rate, the step coverage, and the absorption coefficient of the OH group is shown.

In the plasma enhanced chemical vapor deposition apparatus of FIG. 1, ethyl silicate (hereinafter referred to as TEOS) gas as a silicon raw material is supplied from a TEOS tank not shown in this figure, and liquid TEOS is mass flowed. It is produced by being mixed with the helium whose flow rate is adjusted by the liquid flow rate controller 3 of the mold, completely vaporized by the evaporator 12, and whose flow rate is controlled by the flow rate controller 4. The ozone-containing oxygen is the silent discharge type ozone generator 11 obtained by adjusting the flow rate of the oxygen adjusted by the flow rate controller 2.
It is produced by introducing 1 to 10% of ozone. The TEOS gas and the ozone-containing oxygen gas thus generated are introduced into the manifold 15 through the TEOS inlet 14 and the ozone inlet 13. In the manifold, these gases are mixed and hit the gas diffusion plate 17 to diffuse almost uniformly. Further, when it hits the shower electrode 19, it is dispersed more evenly, and the substrate 2
8 is sprayed on the surface. The substrate 28 is mounted on the SiC susceptor 21, and the heat lamp 2 is passed through the quartz plate 22.
It is heated by light from 3 and is maintained at a temperature of about 200 to 450 ° C. The shower head electrode 19 is electrically insulated from other parts by the insulating ring 18.
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 two frequencies generated in 5 are applied through the matching box 37. The exhaust pipe 24 is connected to a vacuum pump 26, and the pressure of the reaction chamber 20 is maintained at 0.1 to several + Torr.

In the present embodiment, inside the matching box 37 connected to the shower electrode 19, there is a mixer section for mixing high frequency voltages of two frequencies, a matching section for impedance matching, a dummy load, and a semiconductor. There is a switch, and the high frequency voltage applied to the shower electrode 19 can be turned on / off. It is also possible to change the outputs of the high frequency power supplies 35 and 36 and change the high frequency voltage applied to the shower electrode 19 in synchronization with the pulse generated by the pulse generator 40. These operations, including the substrate temperature and the reaction chamber pressure, are controlled by the process controller 41. Transmission paths for these control signals and pulses are indicated by broken lines in FIG.

Here, the operation of this device 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. 2 to 5.

The bottom of FIG. 2 shows the relationship between the film formation time and the high frequency power. Time t when the high frequency power is on
_{During ON} , plasma is generated between the shower head electrode 19 and the substrate 28 or the SiC susceptor 21, oxygen or ozone is decomposed, and oxygen ions are generated. The middle part of FIG. 2 shows the change in the number of oxygen ions. It takes a certain period of time from the start of application of high-frequency power to the stabilization of the plasma state, and the waveform is like a shoulder. Since ozone is less stable than oxygen, the ionization efficiency by applying a high frequency voltage 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 considerably decreases.

FIGS. 3 (a) and 3 (b) are model diagrams showing states near the substrate surface when the high frequency is on and off, respectively. When the high frequency is turned on, plasma is generated between the shower head electrode 19 and the substrate 28 shown in FIG. In plasma,
Oxygen molecules and TEOS molecules have 45 electrons and 4 oxygen ions.
7, TEOS dissociation molecules 46, oxygen radicals 55 and the like are dissociated. Further, 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. Furthermore, the formation film 51 is formed by reacting with oxygen radicals or the like on the surface of the formation film. At this time, since the surface of the forming film 51 is bombarded with a large number of oxygen ions, the life of the film forming precursor 50 is considerably short and the density on the surface of the forming film is low. Further, the oxygen ion bombardment has a function of hardening the forming film 51, has a good film quality, and is useful for forming a film having compressive stress.

Now, once the high frequency is turned off (see FIG.
(See (b)), the number of electrons and oxygen ions rapidly decreases, but TEOS dissociated molecules 46 and oxygen radicals 55 are
It still remains. These diffuse into the surface of the formation film 51 and become the film formation precursor 50, and eventually decrease. further,
The TEOS molecules 54 and ozone molecules 56 also diffuse toward the film surface and react with each other to become TEOS dissociated molecules and film forming precursors. On the surface of the forming film 51, since the film forming reaction is only a thermochemical reaction, the film forming precursor is present at a high density on the surface of the forming film, and the film forming precursor pseudo liquid layer 59 is formed. Since the film-forming precursor pseudo liquid layer 59 exhibits liquid properties,
The film thickness of the lower side surface of the step formed on the substrate 52 is increased, and the inclination of the side surface of the step is relaxed.

FIG. 4 is a vertical cross-sectional view showing a model of the lapse of time and the state of film formation when high frequency power is applied as in FIG. First, as shown in FIG. 4A, time t
_{During ON} (0.5 seconds in FIG. 2), the high frequency is turned on, and the first plasma CVD film 60 of about 10 nm is formed.
Next, as shown in FIG. 4B, the first thermal CVD film 62 is formed during the time t _OFF (0.5 seconds). The time t _OFF is very short, 0.5 seconds, and the thickness of the first thermal CVD film 62 is about 1 nm. Therefore, at the initial _stage of the next t _ON , the film quality is modified by oxygen ion bombardment or the like, and the film quality becomes equivalent to that of the plasma CVD film. Therefore, as shown in FIG. 4C, the modified 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. Due to the effect of the film-forming precursor pseudo-liquid layer, the thermal CVD film can fill the narrow spaces between the wirings and the corners of the step lower portion to make the shape smooth, so that the plasma irradiation at the initial stage of the subsequent plasma CVD film growth can be performed. As a result, the formation film 64 before growth of the second plasma CVD film having the same shape as the thermal CVD and the film quality similar to that of the plasma CVD is formed. Since the lower portion of the step has a rounded shape due to the formation film 64 before the growth of the second plasma CVD film, the second plasma CVD film 6 formed thereon is rounded.
The shape of 3 is also rounded as shown in FIG. Forming film 64 before second plasma CVD film growth and second plasma C
Since the VD film 63 is indistinguishable, the subsequent second thermal CVD is performed.
In the growth stage (d) of the film 65, the lower film is the second plasma C
It becomes the formation film 66 after the VD film growth.

By repeating the above steps a number of times, there is no void in the space between the aluminum wirings 61 as shown in FIG. A film-forming film 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.
The relationship between the value of 100 (%), the growth rate, the step coverage, and the absorption coefficient of OH groups in the film is shown. Figure 5
From the bottom, it can be seen that the growth rate increases as the D increases, and from the middle, the step coverage begins to deteriorate when D exceeds 50%. From the top, the OH group is
It can be seen that if the ratio exceeds 40%, it becomes sufficiently small. From FIG. 4, the step coverage and the water content in the film (OH absorption coefficient in the film) tend to contradict each other, but the value of the duty ratio D is set to an appropriate range (40 to 60% in the case of this embodiment). By doing so, it turns out that both can be prevented from being damaged.

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), tri (dimethylamino) silane _{(SiH (N (CH 3)} 2) 3) also using a silicon-containing compound such as The result of is obtained. Even if ozone is not present in the reaction gas, the life of oxygen radicals and TEOS dissociated molecules is quite long, so
Similar results can be obtained if the value of the duty ratio is properly selected. Further, similar results are obtained when a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, a hydride such as phosphorus, boron, arsenic, 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, but the high frequency power, the reaction chamber pressure, the substrate temperature, the gas flow rate are synchronized with the pulse generated by the pulse generator 40. And the like, a better step coverage can be obtained.

FIG. 6 shows a reaction chamber of a plasma enhanced chemical vapor deposition apparatus according to Embodiment 2 of the present invention, (a) is a plan view thereof, and (b) is a two-dot chain line AA 'of (a). FIG. Note that (a) is a plan view taken along the alternate long and short dash line BB 'in (b). The reaction chamber 72 is divided into six fan-shaped regions, and the fan-shaped portion in the 3 o'clock direction of the clock is a thermal CVD region 70. Clockwise, the plasma CVD region and the thermal CV are provided.
The regions D and the plasma CVD regions 166 are alternately arranged. The substrate 69 is mounted on a susceptor 71 that rotates about a rotation shaft 79, and alternately passes through a thermal CVD region and a plasma CVD region.

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

In the plasma CVD region 166, TEOS is formed.
TEOS gas and oxygen gas are introduced through the introduction port 73 and the oxygen introduction port 74, and the gas dispersion plate 83 ′ and the shower electrode 78 are introduced.
Are evenly dispersed 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 the insulating ring 82 and the insulator 76,
13.56MHz or 450k from RF introduction terminal 77
A high frequency voltage of Hz is applied. By applying these high-frequency voltages, the shower electrode 78 and the substrate 69 'or
Plasma is excited between the susceptors 71, and plasma C
A VD film is formed.

As described above, the substrate 69, together with the rotating susceptor 71, has a plasma CVD region and a thermal CVD region.
Plasma CVD film and thermal CV
D films are formed alternately. At this time, if the rotation speed of the susceptor 71 is set to about 10 revolutions per minute, the thermal CVD region 70
The film thickness of the thermal CVD film formed by is about 2 nm,
Plasma irradiation is performed in the initial stage of film formation in the adjacent plasma CVD regions, and the film quality becomes similar to that of the plasma CVD film. In this way, the film quality is the same as that described in FIG.
Similar to the film, a CVD film having excellent step coverage and step filling property is formed.

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

Further, in this embodiment, the susceptor 71 is formed into a flat turntable shape and the shower injector and the shower electrode are provided above the susceptor. However, the susceptor is formed into a cylindrical or polygonal column shape, and the substrate is attached to 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 ) 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), tri (dimethylamino) silane _{(SiH (N (CH 3)} 2) 3) also using a silicon-containing compound such as The result of is obtained. Even if ozone is not present in the reaction gas, the life of oxygen radicals and TEOS dissociated molecules is quite long, so
Similar results can be obtained if the duty ratio value is appropriately selected. Further, similar results are obtained when the reaction gas is mixed with a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, or a hydride or organic compound such as phosphorus, boron, arsenic, or antimony.

FIG. 7 schematically shows a plasma enhanced chemical vapor deposition apparatus according to the third embodiment of the present invention. Oxygen gas O ₂ whose flow rate is adjusted by the flow rate controller 103 and argon gas Ar whose flow rate is adjusted by the flow rate controller 87 are supplied to the ion source cavity 93, and the pressure is kept at p = 1 mTorr. Also,
A microwave having a frequency of 2.45 GHz is supplied from the microwave power source 84 via the waveguide 85 and the transmission window 86. Further, an electron cyclotron resonance (ECR) occurs in the ion source cavity 93 by the magnetic field of 875 Gauss created 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 divergent magnetic field of the main electromagnet coil 94 and the auxiliary coil 96, and are irradiated onto the substrate 106.

The TEOS gas used as the silicon raw material is 80
TEOS1 kept in a constant temperature container 112 kept at ℃
The TEOS gas evaporated from 11 is introduced into the reaction chamber through the TEOS inlet 107 with the flow rate controller 113 adjusting the flow rate. Further, the oxygen gas whose flow rate is adjusted by the flow rate controller 101 passes through the ozone generator 98 to become ozone-containing oxygen, which is supplied from the ozone inlet 97. The substrate 106 is
It is mounted on the susceptor 109 and heated to 300 ° C. by the heater 110. The pressure in the reaction chamber is
The flow rate is adjusted by the flow rate controller 88, and the Ar inlet 10
Argon gas for dilution supplied from 8 and vacuum pump 10
5 keeps about 1 mTorr.

In the plasma CVD apparatus of this embodiment, first, oxygen plasma is generated in the ion source cavity 93.
The current supplied to the auxiliary coils 96 and 96 'is set to a small value in the direction in which the magnetic field from the ion source toward the substrate is generated, and is set to a level at which the oxygen plasma irradiation is uniform.
In addition, the current flowing through the reflection magnet coils 102 and 102 'is also
A small value is set in the direction of generating a magnetic field from the ion source toward the substrate. In this state, when the surface of the substrate 106 is irradiated with oxygen ions and TEOS gas is supplied, ECR plasma vapor phase growth occurs, and a plasma CVD film with good film quality is formed. Next, the value of the current flowing through the auxiliary coils 96 and 96 'is increased so that a mirror type magnetic field is formed near the outlet of the ion source cavity, and the main electromagnet coils 94 and 94' are formed.
The electrons and ions flowing out from the plasma are repelled by the diverging magnetic field of. Then, on the substrate 106,
Only the TEOS gas and neutral particles such as oxygen radicals and oxygen molecules diffused from the ion source are supplied, and only thermal CVD-like reaction occurs, so that film formation with good step coverage is performed. Therefore, if the current flowing through the auxiliary coils 96 and 96 'is changed in a cycle of about 1 to 10 seconds, the substrate 1
The number of oxygen ions irradiated to 06 periodically changes, plasma CVD films and thermal CVD films are alternately formed, and
The thermal CVD film is also modified into a plasma CVD film, and plasma CVD excellent in step coverage and step filling is formed as in FIG. In particular, in this embodiment, since the reaction chamber pressure is set to about 1 mTorr, it is possible to embed a groove having a large aspect ratio.

The mirror type magnetic field formed by the auxiliary coil 94 is used as a means for changing the oxygen ions with which the substrate 106 is irradiated.
A cusp-type magnetic field formed by 02, 102 'or a recoil electric field formed by applying a positive voltage to the susceptor 109 may be used. Also, although not shown in FIG.
Similar results are obtained with a mechanical shutter.
However, when a structure that prevents diffusion of oxygen radicals is formed by using a mechanical shutter or the like, the ozone generator 9
Needless to say, it is better to operate 8 to supply ozone in the vicinity of the substrate to promote the thermochemical vapor deposition and the growth of the thermal CVD film.

In the above embodiment, the electron cyclotron resonance (ECR) ion source was used as the ion source, but if the intensity of oxygen ions can be changed, the same result 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), tri (dimethylamino) silane _{(SiH (N (CH 3)} 2) 3) also using a silicon-containing compound such as The result of is obtained. Further, similar results are obtained when the reaction gas is mixed with a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, or a hydride or organic compound such as phosphorus, boron, arsenic, or antimony.

FIG. 8 is a vertical cross-sectional view showing a method for flattening an interlayer insulating film of aluminum multilayer wiring according to the fourth embodiment of the present invention.

In this embodiment, first, the aluminum wiring 114 is formed on the substrate 115 on which semiconductor elements and the like are formed (FIG. 8).
(A)). Next, using the plasma enhanced chemical vapor deposition apparatus of Example 1 of the present invention, the CVD film 116 of the present invention is formed thicker than the film thickness of the aluminum wiring, as shown in FIGS. A resist 117 is applied and hard baking is performed. Using the reactive ion etching method in which the resist 117 and the CVD film 116 of the present invention are adjusted to have the same etching rate, etching back is performed to make the surface of the CVD film flat. Then, the planarized interlayer film 118
Is completed.

In this embodiment, the resist is used for flattening, but the same result can be obtained by using polystyrene or organic SOG. 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 the method of operation of Example 5 using the plasma enhanced chemical vapor deposition apparatus of Example 1 of FIG. In FIG. 13, 13.56 MHz high frequency power, 4
It represents about 50 kHz high frequency power, ion current density, and average ion energy. However, all the values are standardized by the maximum value of each value.

In the operation method of this embodiment, the high frequency power sources 39 and 36 having two frequencies of 13.56 MHz and 450 kHz in FIG. 1 are used as in the first and second stages from the bottom of FIG.
Then, a pulse is sent from the pulse generator 40 so that the maximum outputs of the high frequencies of the two frequencies have opposite phases, and the voltage is applied to the shower electrode 19. Then, as shown in FIG.
As in the third and fourth steps from the bottom, the change in ion current density is small, but the average ion energy is 450 kHz.
Takes the maximum value when the high frequency power is maximum, 13.56MH
It can be minimized when the high frequency power is 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. As described above, when only the ion energy is changed without changing the ion current density, the intensity of ion bombardment changes periodically, the film quality is not deteriorated, and the step coverage and the groove filling property are improved. The same as Example 1, but there is an advantage that the change in the film growth rate can be reduced to about 10% as in the uppermost stage of FIG.

Although the apparatus of FIG. 1 is used in this embodiment, the same result can be obtained by using the apparatus of FIGS. 6 and 7 shown in other embodiments of the present patent.

In this example, 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), tri (dimethylamino) silane _{(SiH (N (CH 3)} 2) 3) also using a silicon-containing compound such as The result of is obtained. Even if ozone is not present in the reaction gas, the life of oxygen radicals and TEOS dissociated molecules is quite long, so
Similar results can be obtained if the value of the duty ratio is properly selected. Further, similar results are obtained when the reaction gas is mixed with a silicon inorganic compound such as silane, a nitrogen compound such as ammonia, or a hydride or organic compound such as phosphorus, boron, arsenic, or antimony.

Further, in the present embodiment, only the high frequency power applied to the shower electrode 19 is changed, but the high frequency power, the reaction chamber pressure, the substrate temperature, the gas flow rate are synchronized with the pulse generated by the pulse generator 40. And the like, a better step coverage can be obtained.

[0046]

As described above, according to the plasma chemical vapor deposition method of the present invention, the thermal CVD film of ozone and TEOS having excellent step coverage can be obtained while periodically changing the plasma irradiation intensity on the substrate surface. Formation and its thermal CVD
Modification of the film to a film quality equivalent to the plasma CVD film, and
Since the plasma TEOS / CVD film is repeatedly formed, it has an excellent step coverage so that it is possible to fill a fine groove having a large aspect ratio, the amount of water in the film and the stress in the film are small, and a good film quality is obtained. Plasma C having
There is an effect that a VD film can be formed.

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

Further, the method for producing a multi-layer wiring of the present invention uses the chemical vapor deposition method described in the present patent, in which organosilane and oxygen are used as source gases and the plasma irradiation intensity on the substrate surface is periodically changed. Since the method includes a step of forming an insulating film that does not generate voids between metal wirings by a film thickness equal to or higher than the height of the metal wirings, the interlayer film is different from the conventional method of manufacturing a multilayer wiring using a silica coating film. The amount of water in the inside is significantly reduced, and crack resistance is improved, stress migration is reduced, and conduction characteristics of through holes are improved. Further, since the number of steps of the method for manufacturing a multilayer wiring of the present invention is remarkably reduced as compared with the conventional method, there is an effect that the yield is improved and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a plasma enhanced chemical vapor deposition apparatus showing Example 1 of the present invention.

FIG. 2 shows the operation of the plasma enhanced chemical vapor deposition apparatus shown in FIG. 1 with respect to applied RF power, oxygen ion number, and ozone concentration with time.

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

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

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

FIG. 6 shows a reaction chamber of a plasma enhanced chemical vapor deposition apparatus according to a second embodiment of the present invention, (a) is a schematic plan view, and (b) is a schematic view.
Is a vertical sectional view taken along the chain double-dashed line AA ′ in (a) (note that
(A) is a plan view taken along one-dot chain line BB ′ in (b).

FIG. 7 is a vertical cross-sectional view illustrating the outline of a plasma enhanced chemical vapor deposition apparatus according to a third embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view showing a method of flattening 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 vapor deposition apparatus.

FIG. 10: Plasma enhanced chemical vapor deposition, ozone and TEO
Of 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 in the conventional method that alternately uses the thermochemical vapor deposition method of S,
It is a change figure with respect to film-forming time.

FIG. 11 is a vertical cross-sectional view showing film growth when the plasma chemical vapor deposition method and the ozone thermal chemical vapor deposition method are alternately performed.

FIG. 12 is a vertical cross-sectional view showing a conventional method for forming a planarizing insulating film for multilayer wiring, which uses a plasma 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.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/31 C 21/3205 21/768 H05H 1/46 C 9216-2G

Claims (9)

[Claims] 1. A plasma chemical vapor phase, characterized in that a desired thin film is formed by applying a high frequency voltage of two or more frequencies and periodically changing a part or all of the high frequency power. Growth method. 2. A plasma-enhanced chemical vapor deposition apparatus having a mechanism for supplying organosilane, a mechanism for supplying oxygen, and a mechanism for periodically changing plasma generation intensity. apparatus. 3. The plasma chemical vapor deposition apparatus has a mechanism for supplying organic silane, a mechanism for supplying ozone-containing oxygen, and a mechanism for periodically changing plasma generation intensity. The plasma chemical vapor deposition apparatus described. 4. A plasma vapor deposition apparatus, a mechanism for supplying organosilane and ozone-containing oxygen to a wafer surface, an oxygen plasma ion source, a mechanical shutter for periodically changing plasma irradiation intensity, or A plasma enhanced chemical vapor deposition apparatus having an electromagnetic shutter. 5. A plasma vapor deposition apparatus, a mechanism for supplying organic silane and ozone-containing oxygen to a wafer surface, an oxygen plasma ion source, a mechanical shutter for periodically changing plasma irradiation intensity, or A plasma enhanced chemical vapor deposition apparatus having an electromagnetic shutter. 6. A mechanism for supplying an organic silane, a mechanism for supplying oxygen, a plurality of plasma irradiation mechanisms having different plasma intensities provided in one reaction vessel, and a substrate between the plurality of plasma irradiation mechanisms. And a mechanism for moving the plasma. 7. A mechanism for supplying an organosilane, a mechanism for supplying ozone-containing oxygen, a plurality of plasma irradiation mechanisms having different plasma intensities provided in one reaction chamber, and the plurality of plasma irradiation mechanisms. A plasma-enhanced chemical vapor deposition apparatus having a mechanism for moving a substrate. 8. A plasma-enhanced chemical vapor deposition apparatus having a mechanism for applying a high frequency voltage of two or more frequencies, characterized in that it has a mechanism for periodically changing a part or all of the high frequency power. Plasma chemical vapor deposition equipment for use. 9. A metal is produced by a chemical vapor deposition method according to any one of claims 1 to 5, wherein the irradiation intensity of plasma on the surface of the substrate is periodically changed by using organic silane and oxygen as source gases. Includes a step of forming an insulating film on the wiring to a thickness not less than the height of the metal wiring, a step of forming a flattening film such as a resist film or an organic silica film, and a step of etching back by a reactive ion etching method. A method for manufacturing a multi-layer wiring, characterized by the above.