JPH08203893A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE: To deposit a high quality oxide with high planarization at low temperature as an interlayer insulation film. CONSTITUTION: An oxide film 10 is grown under low pressure using TEOS and ozone as principal materials and exposed, within one production system, to a plasma 11 containing oxygen, ozone, helium and water and a plasma 13 containing oxygen, ozone and helium, as required. The oxide film 10 does not absorb the atmospheric moisture when it is taken out of the production system and it is not affected by the following high temperature heat treatment. When high frequencies of 200 to 450kHz and 1MHz or above coexist at the time of plasma generation, a stabilized plasma can be generated and the corner of oxide is rounded better while enhancing the filling performance of the recess.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device in which a high quality interlayer insulating film can be formed with good flatness at a low temperature.

[0002]

2. Description of the Related Art With the miniaturization of semiconductor elements, the adoption of multilayer wiring, reduction of wiring width and wiring spacing, aspect ratio (wiring film thickness (= wiring height)) has been adopted as the construction of semiconductor devices.
/ Wiring interval) is increasing.

When multi-layered wiring is adopted, it is necessary to separate it with an interlayer insulating film, but the focus in the photolithography process is applied to the surface of the interlayer insulating film in which the lower wiring is embedded.
If there is a large step that exceeds the margin, it becomes difficult to form a fine upper layer wiring.

Therefore, in the recent formation of the interlayer insulating film, the filling property between the lower layer wirings and the smoothness (flatness) of the surface of the interlayer insulating film are very important.

As a conventional method for forming an interlayer insulating film satisfying these requirements, especially when the lower wiring is composed of a polysilicon film or a refractory metal polycide film, for example, Japanese Patent Application Laid-Open No. 63-37638 discloses. As disclosed, a method of reflowing a BPSG film has been applied.

More specifically, referring to FIG. 9A, a gate having a polycide structure formed by stacking a gate polysilicon film 3 and a titanium silicide film 7 on a silicon substrate 1 and n and a source and a drain are formed. -Diffusion layer 4 and n +
Lightly Doped Drain (Li
Consider formation of an interlayer insulating film on a wafer in which a salicide structure having a titanium silicide film 8 on the n + diffusion layer 6 is formed by forming a ghtly Doped Drain (referred to as “LDD structure”).

Here, as shown in FIG. 9B, atmospheric pressure chemical vapor deposition (atmospheric pr) using silane and oxygen as raw materials.
essure CVD, abbreviated as "APCVD")
The oxide film 9 is formed at 00 ° C.

Next, as shown in FIG. 9C, tetraethyl orthosilicate (TEOS: Si (OC
₂ H ₅ ) ₄ ) and trimethylborate (TMB: B (OC
H _{3) 3),} phosphine, oxygen, etc. as raw materials, approximately 1T
low pressure chemical vapor deposition (low pressure CVD, "L
A boron phosphorus-containing silicon oxide (BPSG) film 71 is formed at about 630 ° C. by using the PCVD method.

Finally, as shown in FIG. 9 (D), heat treatment is performed at 850 ° C. for about 30 minutes in a nitrogen atmosphere, and BPS is performed.
The G film 72 is reflowed and flattened.

The reflow heat treatment at such a high temperature causes the problem that the titanium silicide films 7 and 8 on the gate polysilicon film 3 and the n + diffusion layer 6 are aggregated and disconnected, and the n +
There arises a problem that impurities are redistributed in the diffusion layer 6.

The reflow temperature is 80 if the B or P concentration is increased.
It is possible to lower the temperature to 0 ° C or lower, but high concentrations of B and P
The BPSG film containing P has problems such as absorption of moisture in the air and generation of precipitates of BP-Silicon-Oxygen associated with heat treatment that causes pattern defects in the aluminum wiring layer.

As a method for compensating for the above-mentioned drawbacks, for example, Japanese Patent Laid-Open No. 4-167431 proposes a method for improving the film quality of an insulating film formed by a low temperature thermal CVD method. Technical contents disclosed in (1st
The conventional example ”) will be described below in consideration of the application to the salicide structure shown in FIG. 9A.

TEOS and trimethyl phosphate (T
MPO: PO (OCH ₃ ) ₃ ) and triethylborate (T
EB: B (OC ₂ H ₅ ) ₃ ) and ozone-containing oxygen as main raw materials at 350 ° C. to 450 ° C. at APCVD method or LP
A BPSG film 71 is deposited by using the CVD method (FIG. 9).
(See (C)). Next, in another plasma processing apparatus, this BPSG film 71 is exposed to nitrogen or other inert gas or oxygen gas that has been turned into plasma, and the film quality is improved at 350 ° C. to 450 ° C. (see FIG. 9D). ). Further, it is characterized in that the deposition and the modification are repeated twice or more. By using this method, it is possible to prevent moisture or the like from entering from the outside of the BPSG film.

Further, the technical contents (referred to as "second conventional example") disclosed in Japanese Patent Application No. 4-501476 (Japanese Patent Publication No. 4-812535) will be described below. In the publication, a silicon oxide film forming a flat insulating film is formed on a substrate in a reaction chamber by exciting an organic silane or organic siloxane gas and a gas containing H and OH to react in a gas phase or on the substrate. Techniques for forming have been proposed.

Water is supplied to the reaction chamber together with TEOS and nitrogen as a carrier gas, and a plasma-enhanced CVD method is used to deposit an oxygen film containing an organic group and having fluidity on a low-temperature substrate near room temperature.

Since this oxide film has fluidity, it is excellent in embedding in recesses, but the reaction has not progressed sufficiently and the film quality is extremely poor.

Then, next, in the same apparatus, the TEOS is cut off, the high frequency is applied, and the film is processed under plasma excitation in an atmosphere in which only water is supplied to densify the film. In order to deposit the required film thickness, the above-described deposition and densification are repeated using a pulse-modulated high frequency to form a flat and dense oxide film.

Further, Japanese Patent Laid-Open No. 4-343456 discloses a method of manufacturing a semiconductor device capable of forming a flat and dense high-quality silicon oxide film at a relatively low temperature without damaging a substrate or the like by plasma. Thermal CVD in an atmosphere containing organic silane gas and at least water molecules or hydroxyl groups and hydrogen atoms for the purpose of providing
A method of forming a silicon oxide film only by the method is disclosed (referred to as "third conventional example"). That is, in the publication, the substrate temperature is set to about 450 ° C., and the LPCVD method in which excited water, oxygen, ozone, hydroxyl groups, and hydrogen atoms are simultaneously supplied to an organic silane gas such as TEOS is used. It is shown that a good quality interlayer insulating film can be obtained without the need for heat treatment after film formation, which is required in the second conventional example.

[0019]

The first conventional example is as follows.
This is a method of modifying the oxide film by exposing the insulating film after film formation to nitrogen or other inert gas or oxygen gas that has been converted to plasma. The quality of the oxide film is high and the quality of the oxide film is changed to a high-quality oxide film having a strong Si—O bond.

However, since the surface is transformed into a good quality oxide film, the dehydration and oxidation reactions in the deep part of the film are hindered, and there is a problem that the modification of the deep part of the film does not proceed. This is 400
Even when exposed to oxygen plasma under substrate heating at about ℃, dehydration occurs from the silanol bond (Si-OH) in the surface layer and a siloxane bond (Si-O) is formed. Is not done.

Further, in the CVD film to which tensile stress is applied due to the difference in thermal expansion coefficient from the substrate, the surface layer changes to weak compressive stress by the plasma treatment. As a result, a distorted siloxane bond is formed at the interface between the surface BPSG film having a good film quality and the deep BPSG film having a poor film quality, and the siloxane bond is not recombined only by the dehydration condensation reaction, and the dehydration and oxidation in the deep region do not proceed.

Further, when the BPSG film is exposed to a plasma of nitrogen or other inert gas, there is no oxidative effect, so that only plasma bombardment or dehydration with energy from active plasma species is expected. Therefore, the modified layer becomes thinner, and conversely, oxygen deficiency occurs because there is no oxidizing agent.

In particular, when exposed to nitrogen plasma, a nitride film showing a strong compressive stress is formed in the outermost surface layer, which hinders modification of the film in the deep region.

Moreover, there is a problem that even if the plasma power is increased, the depth direction is not so much influenced, and the surface irregularities become severe.

Next, although the second conventional example is excellent in the flatness of the oxide film, it cannot solve the problem of film quality. That is, since a film having fluidity containing an unreacted organic group is deposited, the filling property is naturally excellent.

However, the densification treatment for hydrolyzing and dehydrating and condensing a large amount of organic substances present in the deposited film by performing the plasma treatment in an atmosphere of only water has the following problems.

That is, it is observed in the infrared absorption spectrum that the dehydration condensation reaction does not proceed sufficiently in the plasma treatment at the substrate temperature of about 400 ° C. and the film still contains a large amount of silanol groups. Further, even in a narrow groove portion or a wide groove portion, a thick film is formed at the end portion in comparison with the flat portion at the time of stacking. The condensation reaction does not proceed sufficiently, and as a result, film peeling or "voids" occur at such portions, resulting in a loss of reliability as an interlayer insulating film.

In the third conventional example, the modifying action is included during the growth without performing a heat treatment in another process after the film deposition. This technology has a wiring width of 1 μm
As described above, for the aspect ratio of about 0.4, it is possible to form the interlayer insulating film capable of ensuring the flatness that can be incorporated into the integrated circuit process.

However, in the integrated circuit, the wiring width is currently 0.
It is becoming 25 μm or less, and accordingly, for example, in a gate of polysilicon, the wiring height is 0.15 to 0.3 μm.
The so-called aspect ratio is 0.6 to 1.2, or the Al wiring has a wiring height of 0.5 to 0.75 μm and an aspect ratio of 2 to 3, and the wiring interval is about the same as the wiring width. Is becoming.

When the third conventional example is applied to the structure of the semiconductor device which has been miniaturized as described above, it is apparent that the flatness cannot be ensured within the focus margin in the subsequent lithography process. Became.
Therefore, if it is judged only by the flatness, the method of separately performing the film deposition process and the heat treatment process for improving the film quality is excellent as in the first and second conventional examples. For an integrated circuit process having a cut wiring width, establishment of a technique for forming an interlayer insulating film that satisfies both film quality and flatness is a major technical issue.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device in which a good quality oxide film is formed as an interlayer insulating film with good flatness and at low temperature. To provide.

[0032]

In order to achieve the above object, the present invention provides a step of forming an insulating film on an object to be formed by a chemical vapor deposition method, the insulating film containing oxygen, ozone, water and helium. And a step of exposing to the introduced plasma gas, to provide a method for manufacturing a semiconductor device.

In the method for manufacturing a semiconductor device of the present invention, preferably, (a) low pressure chemical vapor deposition is used to form tetraethyl orthosilicate (TEOS: Si (OC) on the object to be formed.
₂ H ₅ ) ₄ ), a step of forming a silicon oxide film from oxygen and ozone, and (b) under a lower pressure than when the silicon oxide film is formed in the same device in which the silicon oxide film is formed. Exposing the silicon oxide film to a plasma gas into which oxygen, ozone, water and helium have been introduced.

The semiconductor device manufacturing method of the present invention is
Preferably, (a) a reduced pressure chemical vapor deposition method is used to form tetraethyl orthosilicate (TEOS: Si on the substrate to be formed.
(OC ₂ H ₅ ) ₄ ), a step of forming a silicon oxide film from oxygen and ozone, and (b) a lower pressure than that at the time of forming the silicon oxide film in the same device in which the silicon oxide film is formed. In the step of exposing the silicon oxide film to a plasma gas into which oxygen, ozone, water and helium are introduced, (c) the silicon oxide film is formed under a lower pressure than when the silicon oxide film is formed in the same apparatus. Exposure to a plasma gas into which oxygen, ozone and helium have been introduced.

Further, in the present invention, a source gas such as tetraethyl orthosilicate (TEOS: Si (OC ₂ H ₅ ) ₄ ) and oxygen and ozone is used by using a chemical vapor deposition method such as a low pressure chemical vapor deposition method. After the step of forming an insulating film by using, the step of exposing to the plasma gas containing oxygen, ozone, water, and helium, or the step of exposing to the plasma gas containing oxygen, ozone, and helium is repeated a plurality of times. It goes without saying that this is also effective.

In the present invention, in plasma generation in the above process, preferably, in a parallel plate type plasma apparatus, plasma excitation is high frequency having at least one frequency exceeding 1 MHz, and 200 kHz to 450 kHz.
By forming at least two high frequencies having at least one frequency in the range of Hz, plasma is stably generated, and reforming of the formed oxide film by exposure to plasma gas is efficiently performed. You can proceed. Particularly, in the exposure process in the parallel plate type plasma device, when the substrate temperature is set in the range of 250 ° C. to 450 ° C. and the pressure is set in the range of 0.1 Torr to 20 Torr, the oxide film is efficiently modified.

[0037]

According to the present invention, an oxide film deposited at a low temperature is modified from the surface so as to obtain a film quality equivalent to a high temperature heat treatment by a low temperature process. Conventionally, only a region of several tens nm from the surface is modified. For example, the number 1
It can be easily modified to a depth of 00 nm.

This is because the addition of water at the time of modifying the oxide film promotes hydration of the siloxane bond and rearrangement of the bond.
It is considered that ozone addition and plasma bombardment promote dehydration and oxidation from smooth silanol bonds.

Further, according to the present invention, by applying a high frequency of 200 kHz to 450 kHz in addition to the high frequency of 13.56 MHz capable of stably generating plasma in a low vacuum, the substrate surface temperature due to ion bombardment can be improved. It is possible to raise the temperature and effectively promote the modification of the oxide film.

Further, according to the present invention, since the film growth and the plasma reforming are performed in the same apparatus, it is possible to increase the B concentration to a high level.
Even if P and P are added, there is no moisture absorption from the atmosphere, and the excess B and P scatter during the reforming process, so precipitation during temperature reduction after heat treatment can also be suppressed. As a result, there is no disconnection due to the above-mentioned precipitate of aluminum that is the upper layer wiring, and no corrosion of aluminum due to phosphoric acid generated by excess P.

The operation of the present invention will be described below in detail based on an experiment conducted by the inventors of the present invention on the effect of modifying an oxide film (also referred to as an "insulating film").

FIG. 5 is a view showing a cross section of an experimental sample,
FIG. 8 shows an LPCVD apparatus used for film formation and heat treatment.
6 and 7 show experimental results by the inventors of the present application.

More specifically, referring to FIG. 5A, the wet oxide film 32 is formed on the surface of the silicon substrate 31 at about 980 ° C.
Was formed, and then an oxide film (BPSG film) 33 was deposited to a thickness of about 600 nm by the LPCVD apparatus shown in FIG. LPC
VD is 400 from TEOS and oxygen containing ozone
It was carried out at 60 ° C. and 60 Torr.

Next, the oxide film is modified by continuously exposing it to the plasma 34 containing ozone-containing oxygen, water and helium at the substrate temperature of 400 ° C. for 10 minutes in the same apparatus.

For the generation of plasma for this modification, referring to FIG. 8, the distance between the showerhead electrode 620 and the substrate 626 is set to 5 mm.
mm, the internal pressure of the device is 3.0 Torr, 13.56M
Two types of high frequencies of Hz, 200 W, 450 kHz, and 300 W are applied simultaneously.

The atmosphere was measured by introducing 2500 sccm of ozone-containing oxygen having an ozone concentration of 9 vol% and 1000 sccm of helium-converted water vapor with helium as a carrier gas (this sample is referred to as "Sample A").

To explain the introduction of water in more detail, when the flow rate controller (MFC) 606d shown in FIG. 8 introduces helium into the constant temperature bath 633 in which about 400 sccm of water is prepared, it is observed by the flow rate measuring instrument 634. Flow rate is 1400
sccm, which means that water was introduced into the 1000 sccm apparatus in the form of water vapor in terms of helium gas. In addition, helium was also introduced from the flow regulator of another system, and the total flow rate with helium, which is the carrier gas of water, was 50
It was adjusted to be 0 sccm.

For comparison, a sample without plasma treatment (referred to as “Sample B”), a sample subjected to high-temperature heat treatment in nitrogen at 950 ° C. for 60 minutes using a heat treatment furnace (referred to as “Sample C”), and plasma gas species were used. A sample containing oxygen and helium (referred to as “Sample D”) and a sample containing ozone-containing oxygen and helium (referred to as “Sample E”) were prepared.

The film quality of the oxide film was evaluated by an etching rate (see FIG. 6) and an infrared absorption spectrum (see FIG. 7) using a buffered diluted hydrofluoric acid solution diluted 30 times with pure water.

Referring to FIG. 6, in Samples D and E, the region where the etching rate is half that of Sample B is only a few nm from the surface, and 40 nm and about 60 nm, respectively.
At a depth of nm, the modifying effect is no longer visible.

On the other hand, in the sample B of the present invention, the region where the etching rate is halved reaches 40 nm and the modification is performed to the deep portion.

Although the sample C subjected to the high temperature heat treatment at 950 ° C. certainly improved the film quality, in the case of the BPSG film to which B or P was added at a high concentration, when the temperature was lowered after the heat treatment, as described above, Needless to say, it cannot be applied to the salicide structure because of the occurrence of.

Next, each sample was left in the atmosphere after growth,
The results of evaluation of the hygroscopicity of the film by the infrared absorption spectrum are shown in FIG.

Referring to FIG. 7, in the vicinity of 3650 cm ^-1 , isolated silanol (indicated as Si-OH in the figure), 3330c
An absorption spectrum due to the aggregated silanol (indicated as H ₂ O in the figure) around m ⁻¹ can be seen.

In samples B and D, aggregate silanol around 3330 cm ^-1 was clearly seen, indicating that a large amount of water was contained. On the other hand, in sample E, the peak corresponding to water decreases, but there is a skirt on the small wavenumber side of 3650 cm ⁻¹ , and it can be seen that the isolated silanol does not decrease. This is because the dehydration and oxidation are performed near the surface, but the oxidation does not proceed in the deep portion.

On the other hand, in the sample B of the present invention, 3650 cm
The tail on the small wavenumber side of the ^-1 peak is not seen, and the isolated silanol is also reduced.

This is because, as a result of adding water to the plasma, the siloxane bond is hydrolyzed to form a silanol bond, and the switching of the bond progresses, and ozone and oxygen are generated near the stable bond angle and bond length. As a result of dehydration and oxidation due to, it is considered that the reforming proceeds even to the deep part.

The modified oxide film is in a stress-free state at 400 ° C., and when it returns to room temperature, it exhibits a compressive stress due to the difference in the coefficient of thermal expansion with the silicon substrate.

Incidentally, the sample subjected to the high temperature heat treatment at 950 ° C. has no isolated silanol and aggregate silanol, and exhibits compressive stress at room temperature.

[0060]

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

[0061]

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 are schematic cross-sectional views for explaining the manufacturing method according to the first embodiment of the present invention in the order of steps.

In this embodiment, a CV whose schematic structure is shown in FIG.
An interlayer insulating film is formed using the D device. First, FIG.
The CVD apparatus will be described with reference to FIG.

As shown in FIG. 8, the CVD apparatus is supplied with TEOS, TMPO, TEB, and oxygen containing ozone to form a BPSG film, and is formed in the same chamber. Water (H ₂ O), ozone-containing oxygen and helium can be supplied so that the film can be modified.

In this CVD apparatus, a silicon substrate 626 is used.
Mounted on a SiC susceptor 628 and a quartz plate 629.
Light is heated from the heating lamp 630 through 200 to 4
It can be maintained at a temperature of about 50 ° C.

The exhaust pipe 631 is connected to a vacuum pump 632, and the pressure in the reaction chamber 627 is 0.1 to several hundreds of T.
held in orr.

As the reaction gas, ozone-containing oxygen was introduced into the silent discharge type ozone generator 603 by adjusting the flow rate of the oxygen (O ₂ ) by the flow rate controller 601 to obtain 1 to 10% by volume of ozone (O ₃ ). To be produced.

TEOS and TM which are raw materials of silicon
PO and TEB are supplied from respective tanks (not shown) provided corresponding to each other, the flow rate is adjusted by the mass flow type liquid flow rate controllers 604a, 604b, 604c, and completely vaporized by the evaporators 608a, 608b, 608c. And mixed with the helium whose flow rate is adjusted by the flow rate adjusters 606a, 606b, 606c, and the respective inlets 61
It is introduced into the manifold 617 from 2, 613 and 614.

The water used for plasma reforming is the flow rate controller 6
Helium whose flow rate is adjusted at 06d is used as a carrier gas and is introduced into the manifold 617 from the water inlet 615 by using the bubbling method. The flow rate of water is a value obtained by subtracting the flow rate value of the flow rate controller 606d from the flow rate value of the flow rate measuring device 634, and is a helium conversion value.

The flow rate of helium was adjusted by the flow rate controller 609 to adjust the pressure and stabilize the plasma.
It is introduced into the reaction chamber 627 from the inlet 616. The flow rate controller 609 is adjusted so that the total flow rate of helium becomes constant. In the manifold 617, these gases are mixed and hit the gas diffusion plate 618 to diffuse almost uniformly. Then, when it hits the shower electrode 620, it is more uniformly dispersed and sprayed on the surface of the substrate 626 to form a film.

When the oxide film is plasma modified, ozone-containing oxygen gas, H ₂ O gas and helium are introduced into the manifold 617.

The shower electrode 620 is an insulating ring 619.
It is electrically insulated from other parts by 13.5.
6MHz high frequency power source 621 and high pass filter (high pass filter) 622, 450kHz high frequency power source 6
23 and low pass filter (low pass filter) 6
The two high frequencies supplied from 24 are configured to be simultaneously applied via the matching box 625.

The film formation according to this embodiment will be described below with reference to FIGS. 1 and 2.

FIG. 1 (A) is the same as FIG. 9 used for explaining the conventional example.
Similar to (A), it shows a stage where the salicide structure is completed. In the following, a gate having a polycide structure formed by stacking a gate polysilicon film 3 and a titanium silicide film 7 on a silicon substrate 1 and an LDD structure formed by an n − diffusion layer 4 and an n + diffusion layer 6 in a source and a drain are formed. The formation of the interlayer insulating film on the wafer which is formed and has the salicide structure having the titanium silicide film 8 formed on the n + diffusion layer 6 will be described.

First, as shown in FIG. 1B, silane and oxygen are used as raw materials on the entire surface by an APCVD method at about 400.degree.
Then, an oxide film 9 is deposited on the entire surface by about 100 nm.

Further, as shown in FIG. 1 (C), TEO
Approximately 400 ° C, 60T using S and ozone-containing oxygen as raw materials
Approximately 800 n of oxide film 10 by LPCVD under orr
m.

Next, as shown in FIG. 2D, a sample containing ozone-containing oxygen (O ₃ + O ₂ ), water (H ₂ O), and helium (He) was prepared in the same apparatus. The oxide film 10 is modified by being exposed to the plasma.

As a condition for generating plasma, 3.0T
under orr, each power is 200W and 300W by using two frequencies of 13.56MHz and 450MHz.
And

With an ozone concentration of 9% by volume, an ozone-containing oxygen flow rate of 2500 sccm was introduced, and helium was used as a carrier gas.
By introducing 0 sccm and adding helium from another system, the total flow rate of helium introduced into the device is 5
00 sccm. The wafer temperature is about 400 ° C,
The plasma modification treatment was performed for 20 minutes.

Next, as shown in FIG. 2 (E), the sample is exposed to a plasma containing ozone-containing oxygen and helium for 20 minutes in the same apparatus to form a further modified oxide film 14. . In this step, plasma generation conditions, various gas flow rates, and wafer temperatures are the same as those described in the description with reference to FIG. 2D except that water (H ₂ O) is not added.

Finally, as shown in FIG. 2F, a heat treatment furnace is used to perform heat treatment for 30 minutes in a nitrogen atmosphere at 750 ° C. to form an annealed oxide film 15.

In this embodiment, the steps of hydrolysis, dehydration condensation and oxidation in the step of FIG.
The dehydration condensation and oxidation steps shown in Fig. 2 were added.
If the amount of water is reduced in the step (D), the hydrolysis reaction per unit time is suppressed, and the treatment time is lengthened, the result shown in FIG.
The step of is unnecessary.

In this embodiment, the steps of hydrolysis, dehydration condensation and oxidation shown in FIG. 2D and dehydration condensation shown in FIG.
Although the oxidation process is performed only once, it goes without saying that a reforming effect can be obtained even for a thicker film by repeating these two processes several times.

[0083]

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.

Since FIGS. 3 (A) and 3 (B) are the same as FIGS. 1 (A) and 1 (B) referred to in the description of the first embodiment, the description thereof will be omitted. The process of FIG. 3C will be described.

Referring to FIG. 3C, first, an oxide film (BPSG film) is formed by using the apparatus of FIG. 8 using TEOS and oxygen containing ozone as raw materials at a substrate temperature of 400 ° C. and a pressure of 60 Torr.
21 is deposited to a thickness of about 20 nm.

Next, as shown in FIG. 4 (D), the sample was subjected to ozone-containing oxygen (O ₃ ) at 400 ° C. for 1 minute.
The modified oxide film 23 is formed by exposing the modified oxide film 23 to the plasma 22 containing + O ₂ ), water (H ₂ O), and helium (He). Plasma generation conditions are pressure 3.0 Torr
Then, two frequencies of 13.56 MHz and 450 kHz are used, and the respective powers are set to 200 W and 300 W.

2500 sccm of ozone-containing oxygen having an ozone concentration of 9% by volume was introduced into the atmosphere, 1000 sccm of water in terms of helium was introduced using helium as a carrier gas, and helium was added from another system to give a total flow rate of 500 s.
ccm was introduced into the device.

A high frequency of 13.56 MHz is effective only for sustaining stable plasma generation.
The high frequency of 0 kHz ion-etches the oxide film 23 on the shoulder portion of the gate and causes a temperature rise on the surface of the oxide film due to ion bombardment, and the surface shape is flattened.

Note that, as shown in FIG.
If the oxide film deposition step of (C) and the modification step of FIG. 4 (D) are repeated several times in the same apparatus, a thick oxide film 24 having excellent insulating properties can be formed.

Finally, as shown in FIG. 4F, heat treatment is performed in a nitrogen atmosphere at 750 ° C. for 10 minutes in a heat treatment furnace, and the oxide film 25 is tightened as a precaution.
Then, the interlayer insulating film forming step is completed.

In this embodiment, the quality of the oxide film was improved only by the steps of hydrolysis, dehydration condensation, and oxidation. However, as shown in the first embodiment, the water content with a large amount of water was added first. The same effect can be obtained by removing water after the decomposition reaction and adding dehydration condensation and oxidation steps.

In the first and second embodiments, the substrate temperature in the exposure process, which is the process of modifying the oxide film, is 40.
The case of 0 ° C was described, but the substrate temperature is 2
The effect of the present invention was obtained when the temperature was 50 ° C. or higher.

When the underlying layer has Al wiring or the like, the upper limit of the temperature is preferably 450 ° C. or lower.

In the above embodiment, the pressure in the exposure process is 3
Although Torr was used, valid results were obtained between 0.1 Torr and 20 Torr.

Plasma excitation is carried out at a high frequency having at least one frequency exceeding 1 MHz and from 200 kHz to 45 kHz.
It is understood that stable plasma is excited up to an extremely low pressure of 0.1 Torr by performing at least two high frequencies having at least one frequency in the range of 0 kHz, and the desired effect is obtained.

The higher the pressure is, the more effective the effect of modifying the oxide film is. However, if it exceeds 20 Torr, it becomes difficult to generate stable plasma, and if there is a transistor or the like under the base, the plasma is damaged.

The amount of water introduced into the apparatus in the process of modifying the oxide film is 10 as a helium-equivalent steam flow rate.
It was experimentally sought that it should be performed between 0 sccm and 2000 sccm.

In the above embodiment, the oxide film 10 or 2 is used.
No impurities were added to the sample No. 1, but PH ₃ , trimethyl phosphate (TMPO: PO (OC
H _{3) 3),} trimethyl phosphite (TMP: P (O
CH ₃ ) ₃ ), triethylphosphite (TEP: P
(OC ₂ H ₅ ) ₃ ), TMPO, or the like as a raw material to which P is added, or BH ₃ or triethyl borate (TEB: B (OC ₂ H _2
5 ) ₃ ) and trimethylborate (TMB: B (OC
A film in which B is added to a raw material such as H ₃ ) ₃ ) or a film in which both P and B are added may be used.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments,
As a matter of course, it includes various aspects according to the principle of the present invention.

[0100]

As described above, according to the present invention, there is shown a method of modifying an oxide film deposited at a low temperature from the surface to obtain a film quality equivalent to that of a high temperature heat treatment in a low temperature process,
Conventionally, the modification is limited to only a region of several tens nm at the most from the surface, but it has an effect that the modification can be easily performed to a deep part of several 100 nm.

This is because the addition of water at the time of modifying the oxide film promotes hydration of the siloxane bond and rearrangement of the bond.
It is considered that ozone addition and plasma bombardment promote dehydration and oxidation from smooth silanol bonds.

According to the present invention, by applying a high frequency of 200 kHz to 450 kHz in addition to a high frequency of 13.56 MHz capable of stably generating plasma in a low vacuum, the substrate surface temperature rise due to ion bombardment. It is possible to effectively promote the above reaction. Ions in plasma cannot follow 1 MHz or more, and the ion bombarding effect on the substrate is thin and the film modifying effect is small. On the other hand, 1M
With only a high frequency of Hz or less, the degree of vacuum is 1 Torr or less for stable oscillation of plasma, and the absolute amount of oxidizing species such as oxygen, ozone, and water reaching the substrate is small, and the reforming and flattening effects are also reduced. . Naturally, 200k
The increase in the high frequency power from Hz to 450 kHz makes the effect of modifying and flattening the oxide film more remarkable. Further, in the present invention, the sputter etching effect of helium contributes to chamfering of the oxide film in the gate stage and filling of the recess.

Further, according to the present invention, since film growth and plasma reforming are performed in the same apparatus, B and P can be highly concentrated.
Even if added, there is no moisture absorption from the atmosphere and excess B
Since P and P scatter in the reforming process, precipitation at the time of temperature reduction after heat treatment can also be suppressed. As a result, there is no disconnection due to the above-mentioned precipitate of aluminum that is the upper layer wiring, and no corrosion of aluminum due to phosphoric acid generated by excess P.

Further, since the heat treatment temperature after the film growth is 750 ° C., there is no aggregation of the titanium silicide film. Therefore, the manufacturing method according to the present invention is applied to the salicide structure wiring using the titanium silicide film. it can.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of a semiconductor device for explaining a first embodiment of the present invention in the order of steps.

FIG. 2 is a schematic view showing a cross section of a semiconductor device for explaining the first embodiment of the present invention in the order of steps.

FIG. 3 is a schematic view showing a cross section of a semiconductor device for explaining a second embodiment of the present invention in the order of steps.

FIG. 4 is a schematic view showing a cross section of a semiconductor device for explaining a second embodiment of the present invention in process order.

FIG. 5 is a cross-sectional view illustrating a sample for an experiment of the manufacturing method according to the present invention.

FIG. 6 is a diagram illustrating an experimental result of an etching rate of an oxide film by a manufacturing method according to the present invention.

FIG. 7 is a diagram illustrating an experimental result of an infrared absorption spectrum of an oxide film according to the manufacturing method of the present invention.

FIG. 8 is a diagram illustrating a configuration of a chemical vapor deposition apparatus used in an example of the present invention.

FIG. 9 is a schematic cross-sectional view for explaining the manufacturing method of the conventional example in the order of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Gate oxide film 3 Gate polysilicon film 4 n- Diffusion layer 5 Sidewall oxide film 6 n + Diffusion layer 7 Titanium silicide film 8 Titanium silicide film 9 Oxide film 10 Oxide film 11 Plasma 12 Modified oxide film 13 Plasma 14 Further modified oxide film 15 Annealed oxide film 21 Oxide film 22 Plasma 23 Modified oxide film 24 Modified thick oxide film 25 Annealed oxide film 31 Silicon substrate 32 Oxide film 33 Oxide film (BPSG film) 34 Plasma 35 Modified oxide film (BPSG film) 601 Flow rate controller 602 Valve 603 Ozone generator 604a to 604c Liquid flow rate controller 605a to 605c Valve 606a to 606d Flow rate controller 607a to 607d Valve 608a to 608c Evaporator 609 Flow rate control Bowl 610 Bed 611 ozone-containing oxygen inlet 612 TEOS inlet 613 TMPO inlet 614 TEB inlet 615 H ₂ O inlet 616 the He inlet 617 manifold 618 gas diffusion plate 619 insulating ring 620 shower head electrode 621 13.56 MHz RF power source 622 pass filter 623 450 kHz high frequency power supply 624 Low pass filter 625 Matching box 626 Substrate 627 Reaction chamber 628 SiC susceptor 629 Quartz plate 630 Heating lamp 631 Exhaust pipe 632 Vacuum pump 633 Constant temperature chamber 634 Flow rate meter 71 BPSG film 72 High temperature annealed BPSG film 73 Silicide film 74 Broken titanium silicide film

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 1, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Further, in the CVD film which exhibits tensile stress due to the difference in thermal expansion coefficient from the substrate, the surface layer changes to weak compressive stress by the plasma treatment. As a result, a distorted siloxane bond is formed at the interface between the surface BPSG film having a good film quality and the deep BPSG film having a poor film quality, and the siloxane bond is not recombined only by the dehydration condensation reaction, and the dehydration and oxidation in the deep region do not proceed.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

[0037]

According to the present invention, an oxide film deposited at a low temperature is modified from the surface so as to obtain a film quality equivalent to a high temperature heat treatment by a low temperature process. Conventionally, only a region of several tens nm from the surface is modified. For example, about 1
It can be easily modified to a depth of 00 nm.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0098

[Correction method] Change

[Correction content]

In the above embodiment, the oxide film 10 or 2 is used.
No impurities were added to the sample No. 1, but PH ₃ , trimethyl phosphate (TMPO: PO (OC
H _{3) 3),} trimethyl phosphite (TMP: P (O
CH ₃ ) ₃ ), triethylphosphite (TEP: P
(OC ₂ H ₅ ) ₃ ), TMPO, or the like as a raw material to which P is added, or BH ₃ or triethyl borate (TEB: B (OC ₂ H _2
5 ) ₃ ) and trimethylborate (TMB: B (OC
A film in which B is added to a raw material such as H ₃ ) ₃ ) or a film in which both P and B are added may be used.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0100

[Correction method] Change

[Correction content]

[0100]

As described above, according to the present invention, there is shown a method of modifying an oxide film deposited at a low temperature from the surface to obtain a film quality equivalent to that of a high temperature heat treatment in a low temperature process,
Conventionally, the modification has been limited to only a region of several tens nm at the most from the surface, but it has an effect that it can be easily modified to a deep portion of about 100 nm.

Claims (7)

[Claims] 1. A process of forming an insulating film on an object to be formed by chemical vapor deposition, and a process of exposing the insulating film to a plasma gas containing oxygen, ozone, water and helium. A method of manufacturing a semiconductor device, comprising: 2. A method of manufacturing a semiconductor device for forming an interlayer insulating film, comprising: (a) using a low pressure chemical vapor deposition method to form tetraethyl orthosilicate (TEOS: Si (OC ₂ H ₅ )) on an object to be formed.
₄ ), a step of forming a silicon oxide film from oxygen and ozone, and (b) the silicon oxide film under a lower pressure than when the silicon oxide film is formed in the same device in which the silicon oxide film is formed. Is exposed to a plasma gas into which oxygen, ozone, water, and helium are introduced, and a method of manufacturing a semiconductor device. 3. A method of manufacturing a semiconductor device for forming an interlayer insulating film, comprising: (a) using a low pressure chemical vapor deposition method to form tetraethyl orthosilicate (TEOS: Si (OC ₂ H ₅ )) on an object to be formed.
₄ ), a step of forming a silicon oxide film from oxygen and ozone, and (b) the silicon oxide film under a lower pressure than when the silicon oxide film is formed in the same device in which the silicon oxide film is formed. Is exposed to a plasma gas into which oxygen, ozone, water and helium are introduced, and (c) the silicon oxide film is exposed to oxygen, ozone and helium under a lower pressure than when the silicon oxide film is formed in the same apparatus. And a step of exposing to a plasma gas into which is introduced. 4. The step (b) of exposing the oxide film to a plasma gas containing oxygen, ozone, water and helium.
And / or, the step (c) of exposing the oxide film to a plasma gas into which oxygen, ozone and helium are introduced
4. The method for manufacturing a semiconductor device according to claim 3, wherein the step is repeated a plurality of times. 5. The step of exposing the oxide film to the plasma gas is performed in a parallel plate type plasma apparatus by plasma excitation.
5. At least two high frequencies consisting of a high frequency having at least one frequency exceeding 1 MHz and a high frequency having at least one frequency in the range of 200 kHz to 450 kHz. A method for manufacturing a semiconductor device as described above. 6. The step of exposing the oxide film to the plasma gas is performed in a parallel plate type plasma apparatus at a substrate temperature of 25.
The temperature is in the range of 0 ℃ to 450 ℃, and the pressure is 0.1Torr.
To 20 Torr. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the range is from 20 to 20 Torr. 7. A method of manufacturing a semiconductor device, wherein an insulating film is formed on an object to be formed by repeating the manufacturing method according to claim 1 a plurality of times.