JP3194256B2 - Film growth method and film growth apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor or metal film growth, and more particularly, to a semiconductor or metal film growth method and apparatus suitable for a semiconductor device manufacturing process.

2. Description of the Related Art High reliability and high speed operation characteristics are required for fine devices such as highly integrated semiconductor devices, and uniform and flat films having desired characteristics, films having small contact resistance, and embedding of good characteristics are required. A film or the like is desired.

[0003]

2. Description of the Related Art Known methods for growing a film include vapor deposition, sputtering, chemical vapor deposition (CVD), liquid phase growth, and molecular beam growth.

In order to form a uniform and flat film on an underlayer, it is necessary to clean the underlayer surface, and it is also necessary to control conditions such as a film forming temperature and a pressure in CVD and the like. is there. Hereinafter, the CVD will be described as an example.

[0005] Selective growth, blanket growth, and the like can be performed by CVD. In these CVD growths, it is necessary to clean the underlying surface by wet or dry pretreatment, and to appropriately set growth factors such as film forming temperature and pressure in the CVD process.

However, even when trying to grow a CVD film having a uniform film thickness, it is difficult to prevent the occurrence of film thickness distribution and the occurrence of unevenness on the surface even when trying to obtain a flat surface. Also, by performing unnecessary pre-processing,
It has been difficult to prevent the opening size defined by the oxide film or the like from being enlarged or damaging the underlying semiconductor substrate.

For example, when trying to clean the surface with plasma, it is difficult to avoid that high-energy particles generated in the plasma collide with and damage the underlying surface.

When a semiconductor device is miniaturized, non-uniformity and deterioration of properties of a film to be formed have a serious influence on a micro device to be formed, resulting in a decrease in device manufacturing yield and inability to realize design performance. connected.

[0009]

As described above,
According to the conventional film growth technology, it has been difficult to grow a uniform and flat film.

An object of the present invention is to provide a film growth method capable of growing a uniform and flat film. Another object of the present invention is to provide a film growth method capable of growing a uniform and flat film with low contact resistance.

Another object of the present invention is to provide a film growth apparatus which can easily grow a uniform and flat film.

[0012]

According to the present invention, there is provided a film growing method comprising:
Forming an adsorption layer of a metal or semiconductor compound on the surface of the semiconductor or metal exposed in the opening formed in the insulating film; and forming a deposition layer of the metal or semiconductor by causing a decomposition reaction of the adsorption layer. And forming a metal or semiconductor growth film on the deposited layer.

FIG. 1 is a diagram illustrating the principle of the present invention. FIG.
(A) shows an adsorption step. An adsorption layer 2 of a metal or semiconductor compound is formed on the surface of the base 1. The adsorption layer 2 is composed of adsorbed molecules and is in a state of physical adsorption or chemical adsorption.

[0014] In the case of chemisorption, precipitation may occur by a reaction according to the chemical reaction kinetics.
If at most one adsorbed molecule has reacted within H, it is also considered as a chemisorption or transition state. The adsorption layer 2 preferably has a thickness of from a monolayer to several tens of ns.

FIG. 1B shows the steps of the decomposition reaction. When the adsorption layer 2 formed on the surface of the base 1 is excited, a decomposition reaction is caused to form a deposition layer 3 of components contained in the adsorption layer 2. This decomposition reaction can be performed, for example, by a heating step or a light irradiation step.

Preferably, after the deposition layer 3 is thus formed on the surface of the underlayer 1, a growth film 5 of a target material is grown thereon as shown in FIG. 1 (C). The growth film 5 can be formed, for example, by CVD.

[0017]

When an adsorbed layer is formed on the surface of an underlayer, the adsorbed layer is decomposed to form a deposited layer, and a metal or semiconductor growth film is formed thereon. Can be obtained.

In film growth, when film-forming molecules adhere to the underlying surface and these molecules form a growth nucleus, the film grows from the growth nucleus. By the way, it is not easy to form the growth nuclei uniformly on the surface, and when a distribution occurs in the growth nuclei, a bias of growth occurs according to the distribution, and a distribution occurs in the thickness of the formed film, It is considered that irregularities occur on the surface.

The adsorption can be performed under a condition that is gentler than the film growth. For example, when a gas is supplied onto a base surface at a low temperature at which CVD growth does not occur, gas molecules are adsorbed on the base surface to form an adsorption layer. Covering the underlayer surface with the adsorption layer can be performed relatively easily.

As described above, by covering the base surface with the adsorption layer and subjecting the adsorption layer to a decomposition reaction, it is possible to form the precipitation layer 3 while leaving only predetermined components of the compound components on the base surface.

The deposited layer thus formed can be easily distributed uniformly on the surface of the base. Even if the deposited layer has a thickness distribution, the effect on the result is small if the thickness of the deposited layer is small. It is considered that if this deposited layer is used as it is as a base surface for film growth, it can function as a uniformly distributed good growth nucleus.
The growth film formed on the deposition layer can have a uniform thickness and a flat surface.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 2, 3, and 4 are cross-sectional views illustrating a film growth method according to an embodiment of the present invention, and FIG. 7 is a schematic diagram illustrating a film growth apparatus suitable for performing these growth methods. It is sectional drawing.

FIG. 2 shows an embodiment in which a W layer is selectively grown on a Si layer. As shown in FIG.
A silicon oxide film 12 is formed thereon, an opening 16 is formed in the silicon oxide film 12, and the surface of the Si layer 11 is exposed.

The underlayer structure formed in this way is used as
It is immersed in a 1 to 2% HF solution for 30 to 60 seconds, and after cleaning the surface by pure water washing (exposure of Si and formation of H-terminated surface), it is dried.

As the pre-treatment, a dry treatment can be adopted in place of the wet treatment. For example, H ₂
Alternatively, the base surface can be cleaned using a reduction reaction with a hydride such as N ₂ H _x .

The underlayer structure prepared in this way is 10 ^-7.
The atmosphere is maintained at 10 to 10 ^-8 Torr and heated to 80 to 240 ° C. The heating time is desirably set to 10 ² L or less in the atmosphere.

On the heated substrate surface, WF₆10 gas
^Four-10^FiveL (L is Langmuir, 1L = 10
^-6Torr · sec). For example,
WF ₆10 gas^-3Torr for 10-100 seconds,
Is 10^-2It is supplied for about 1-10 seconds at Torr. 10^Four
The amount of L gas is important for forming a monolayer on the base surface.
It is an appropriate amount.

By such adsorption, the WF ₆ adsorption layer 13 is selectively formed on the exposed surface of the Si layer 11 as shown in FIG. Note that no adsorption layer is formed on the surrounding Si oxide film 12.

Next, as shown in FIG.
To about 240-500 ° C with the supply of
Temperature rise, WF₆A thermal decomposition reaction of the adsorption layer 13 is caused.
WF ₆Is thermally decomposed, and tungsten (W) is
Deposited on one surface to form a W layer 14.

Although the state in which the continuous W layer 14 is formed is shown in the figure, the W layer is not necessarily required to be microscopically continuous. What is necessary is that they are distributed almost uniformly on the surface of the Si layer 11.

The underlayer structure on which the W layer 14 is formed is carried into a CVD apparatus without being exposed to the atmosphere. As shown in FIG. 2C, in a CVD apparatus, the underlying structure is heated to about 280 ° C., WF ₆ gas and SiH ₄ gas are supplied at a ratio of about 6: 3, and the W layer 14 is formed on the W layer 14 by CVD. A CVDW layer 15, which is a W layer, is deposited. In this CVD, the previously formed W layer 14 functions as a growth nucleus, and uniform film growth occurs.

As described above, the film growth in which the adsorption layer is formed and then the CVD growth is performed without exposing the film to the atmosphere can be performed using, for example, a film growth apparatus as shown in FIG.

In FIG. 7, the adsorption chamber 31 has an adsorption gas introduction port 32 and an exhaust port 33, and can maintain a high vacuum of 10 ⁻⁷ Torr or less. The suction chamber 31 is provided with a heater 34.
And a plurality of substrates 30 loaded into the adsorption chamber
It can be heated to 0-200 ° C.

Gas is adsorbed on the surface of the base in the adsorption chamber 31, and the CVD reaction chamber 3 is supplied one by one through the intermediate chamber 35.
6 and heated by the heater 37, a decomposition reaction of the adsorbed gas can be caused. After causing the decomposition reaction of the adsorbed gas, while heating to a predetermined temperature with the heater 37,
A film can be grown by supplying a source gas from the gas supply system 38 and performing CVD growth.

In the apparatus shown in FIG.
Is a batch type, and the CVD reaction chamber 36 has a single-wafer type structure. However, the present invention is not necessarily limited to this type. For example, the adsorption chamber may be a single wafer type, and the CVD reaction chamber may be a batch type. Note that a heating mechanism may be provided in the intermediate chamber 35 to cause the decomposition reaction of the adsorbed gas in the intermediate chamber 35. It is also possible to carry out a decomposition reaction in the adsorption chamber 31.

Using a film growth apparatus as shown in FIG.
The CVDW layer 15 having low contact resistance can be grown on the Si layer 11 in the high concentration impurity added region or the like by performing the film growth method as shown in FIG.

It has been experimentally confirmed that the CVDW layer 15 grown in this manner has a uniform thickness and a flat surface. The W layer 1 is formed on the Si layer 11.
Although the case of growing 4 and 15 has been described, the material of the base and the growth film is not limited to these.

FIG. 3 shows an embodiment in which a metal layer of Al, Cu, Ti or the like which reacts with Si is grown on Si. As shown in FIG. 3A, Si oxide
A film 12 is formed, an opening 16 is formed in the Si oxide film 12, and the surface of the Si layer 11 is exposed. The base structure thus prepared is cleaned by the same pretreatment as in the embodiment of FIG. Subsequently, the adsorption layer 17 is formed on the exposed surface of the Si layer 11.

For example, Ti (N (C
H _{3) 2) 4} = DMAT and when forming the adsorption layer of the TiCl ₄ gas, the base temperature former to about room temperature to 200 DEG ° C., the latter is heated to 300 to 600 ° C., 10 the DMAT and TiCl ₄ gas Supply ³ to 10 ⁵ L, and adsorb layer 17
To form When forming a WF ₆ gas adsorption layer as the adsorption layer 17, the adsorption layer 17 is formed by the same process as the embodiment of FIG.

Incidentally, DMAT and TiCl ₄ are liquid at normal temperature and normal pressure, and their vapor pressure is low. In contrast, WF ₆
Is a substance having a boiling point of about 17 ° C., and is a gas at room temperature, and has a characteristic of easy handling.

Next, as shown in FIG.
The base structure on which 7 is formed is carried into a reaction chamber, and Ti, TiN, or W is deposited by raising the temperature, thereby forming a contact layer and a barrier layer 18.

When the adsorbing layer 17 is made of WF ₆ , as in the embodiment shown in FIG. 2, the WF ₆ is thermally decomposed to form a W deposition layer. When the adsorption layer 17 is an adsorption layer of TiCl ₄ molecules, when Ti is deposited by thermal decomposition, the Ti reacts with the Si layer 11 to form TiSi ₂ . Due to this silicide reaction, the Si layer 11 is eroded, and the contact layer has a shape in which the Si layer 11 has digged in as shown by a broken line 18a in the figure.

Hydrogen or hydride is added to promote thermal decomposition.
It is desirable to obtain. NH_ThreeAnd N_TwoH _FourHydride
As a result, TiN is used as a barrier layer and T is used as a contact layer.
iSi_TwoCan be formed. SiH_FourIs added, Ti
Si_TwoA film can be formed, and the amount of erosion of the Si layer 11 decreases.
You. DMAT gas forms a TiN film by thermal decomposition
You.

The contact layer 18 thus formed plays a role of preventing a reaction between the Si layer 11 and a metal layer formed on the contact layer 18. Next, FIG.
As shown in (C), a metal layer 19 is selectively grown on the contact layer 18 by CVD. The metal layer 19 is, for example, a metal such as Al, Cu, and Ti.

When the metal layer 19 is an Al layer, the source gases for CVD are TIBA (triisobutylaluminum), TMA (trimethylaluminum), and DMAH.
(Dimethylaluminum hydride) and adding a hydrogen gas or a hydride gas to form a film at a temperature of about 150 to 4
CVD growth is performed at 00 ° C. and a gas pressure of 10 ^{-4 to 1} Torr.

When the metal layer 19 is a Cu layer, Cu (HFA) ₂ (copper hexafluoroacetylacetonate) can be used as a source gas. Thus, S
A metal layer 19 is grown on the i-layer 11 with the contact layer 18 interposed therebetween. The metal layer 19 thus grown has a uniform thickness and a flat surface.

In the step of decomposing the adsorption layer shown in FIG. 3B, the decomposition reaction can be promoted by using a hydride. For example, SiH _{4 is set} to 10 ³ to 10 ⁵ L
The temperature is set to about 200 ° C. The presence of the hydride promotes the decomposition reaction.

Further, a silicide film can be positively formed by adding a silicon hydride and further adjusting the temperature. For example, the base temperature is raised to about 400 ° C., and 10 ³ to 10 ⁵ L of SiH ₄ is supplied. The amount of SiH _{4 to be} supplied is selected such that the adsorption layer 17 becomes a silicide film, but a pure Si film does not grow.

The case where the film is selectively grown in the opening formed in the Si oxide film has been described above, but a blanket film extending also on the Si oxide film can be grown.
FIG. 4 shows a film growth method according to another embodiment of the present invention.

As shown in FIG. 4A, a contact layer 18 is formed on the exposed surface of the underlying Si layer 11 by the same steps as in the above embodiment. If W, Ti, or the like is used as the material of the contact layer 18, low contact resistance with the Si layer 11 can be easily realized. When forming the contact layer 18 with Ti, Ti is the TiSi ₂ silicided.

Next, as shown in FIG. 4B, the base temperature is raised to about 700 ° C., a TiCl ₄ gas and an NH ₃ gas are supplied, and the TiN mat layer 20 is formed by performing CVD. I do. The TiN mat layer 20 is formed not only on the contact layer 18 but also on the surface of the Si oxide layer 12. If a B ₂ H ₆ gas is supplied, a TiB film can be formed.

Next, as shown in FIG. 4C, an electrode layer 21 is formed on the TiN mat layer 20 by CVD.
The electrode layer 21 is formed of a highly conductive metal such as W, Al, Cu, and Au.

The metal electrode layer 21 is formed on the Si layer 11.
Although the case of growth is explained, the base material and the growth film material are
Not limited to these. For example, a Si film is formed on an underlying Si.
When performing long, first use Si_TwoH₆About 10^FourL supply
To form an adsorption layer, and then raise the temperature to about 800 ° C.
Therefore, the growth nucleus of Si is formed by the thermal decomposition reaction of the adsorption layer.
And subsequently by CVD growth of Si
The Si film can be grown. The CV of Si
In D growth, SiH_Four, Si_TwoH₆, SiCl_Two
H_TwoSiHCl_Three, SiH_TwoF _TwoEtc. can be used
You.

Note that these film growth methods can also be performed using a film growth apparatus as shown in FIG. FIG.
Forms an adsorption layer on the base surface by such a method, and forms a deposition layer by reacting the adsorption layer,
FIG. 4 is a diagram illustrating properties of a film when a film is grown thereon.

FIG. 5A shows a structure in which a film is grown according to the same procedure as in the above embodiment. A pattern of polycrystalline Si layer 27 is formed on semiconductor layer 25 covered with insulating layer 26, and a film is grown on this pattern.

An adsorption layer is formed on the surface of the polycrystalline Si layer 27, and is converted into a deposited layer 28 by reacting.
When the growth film 29 is formed on the deposition layer 28, the growth film 2
9 can be grown with a uniform thickness. Observation of the surface of the grown film 29 grown in this way confirmed that it was flat.

On the other hand, when a pattern of a polycrystalline Si layer 27 is formed on a semiconductor layer 25 covered with an insulating layer 26 by a conventional technique and a growth film is formed directly on the surface thereof, FIG.
As shown in the growth film 29a of (B), irregularities were generated on the surface.

The reason for the occurrence of such irregularities is that the surface of the polycrystalline Si layer 27 changes variously due to exposure to the air and the like, and when CVD growth is performed on the surface, generation of growth nuclei occurs. It is thought that the speed varies from place to place.

In the region where the growth nuclei occurred early,
Crystal growth proceeds immediately, and the grown film 29a becomes thicker. In a region where the growth nucleus is not easily generated, the film growth is delayed, and the thickness of the grown film 29a becomes thin. As described above, since the growth varies, it is considered that the film thickness of the growth film 29a is not constant and irregularities are generated on the surface.

FIG. 6 shows the results of an experiment conducted to study the properties of the adsorption layer. Specific resistance 10-20μΩ ・ cm
(Sheet resistance Rs = 240 to 280Ω / □) (10
0) The Si substrate having the plane is kept at 182 ° C.
F ₆ gas was supplied at a flow rate of 10 sccm for a predetermined time. In this state, the sheet resistance was measured. Then at about 407 ° C 3
After heat treatment for 0 minutes, the sheet resistance was measured again.

In FIG. 6, the horizontal axis indicates the supplied amount of the supplied WF ₆ gas in Langmuir (L), and the vertical axis indicates the sheet resistance in Ω / □. In the figure, ○ indicates the result of measuring the sheet resistance before the heat treatment with WF ₆ gas adsorbed.
Indicates the sheet resistance measured after further heat treatment.

As is apparent from the figure, the sheet resistance after the heat treatment is clearly lower than the sheet resistance after the WF ₆ gas is supplied. Therefore, it can be seen that the adsorbed layer was formed by the supply of the WF ₆ gas, and the adsorbed layer was decomposed by the heat treatment and changed to a W layer. It can also be seen that low contact resistance can be achieved by such a film growth method.

Although the case where heating is used as a method of decomposing the adsorption layer has been described, other means can be used as long as it is an excitation means for decomposing the adsorbed molecules. For example, the adsorbed molecules can be decomposed by irradiating light having sufficient photon energy.

As an apparatus for growing a film, an adsorption chamber, an intermediate chamber,
Although the configuration in which the CVD reaction chamber is connected is shown, another configuration may be used as long as an adsorption layer is formed on the base, the decomposition reaction can be performed without exposing to the atmosphere, and then the film growth can be performed. It can also be used.

The base material and the growth film material may be semiconductors or metals. The adsorption gas for forming the adsorption layer is preferably one that can be easily decomposed by heating or the like. For example, group III, group IV, group V hydrides or compounds having at least one halogen atom, W, Ti, C
u, Zr, Mo, Re, Cr, Au, Ta halides, organic compounds, complexes and the like can be used.

The grown film is made of, for example, group III or IV.
Group, group V elements and mixtures thereof, and compounds thereof, W, Ti, Cu, Zr, Mo, Re, Cr, A
Metals of u and Ta and compounds of Si, B and P of these metals can be used. Further, the method of growing the grown film is not limited to CVD.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0068]

As described above, according to the present invention,
A growth film having a uniform thickness and a flat surface can be obtained.

Since a grown film which is excellent in film forming characteristics and electric characteristics and can be mass-produced is obtained, it is easy to manufacture a miniaturized semiconductor device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a cross-sectional view illustrating a film growth method according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a film growth method according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a film growth method according to an embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing a morphology of a grown film grown according to an example of the present invention in comparison with a morphology of a grown film grown according to a reference example.

FIG. 6 shows the sheet resistance of a Si substrate on which an adsorption film is formed,
6 is a graph showing a comparison between sheet resistances after heat treatment.

FIG. 7 is a schematic sectional view showing a film growth apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base 2 Adsorption layer 3 Precipitation layer 5 Growth film 11 Si layer 12 Si oxide film 13 WF ₆ adsorption layer 14 W layer 15 CVDW layer 16 Opening 17 Adsorption layer 18 Contact layer 19 Metal layer 20 TiN mat layer 21 Electrode layer 31 Adsorption chamber 32 Adsorption gas inlet 33 Exhaust port 34 Heater 35 Intermediate chamber 36 CVD reaction chamber 37 Heater 38 Gas supply system

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 16/00-16/56 C23C 14/00-14/58 H01L 21/205 H01L 21/28-21 / 285 H01L 21/31 JICST file (JOIS)

Claims (7)

(57) [Claims] A step of forming an adsorption layer of a metal or a compound of a semiconductor on a surface of a semiconductor or a metal exposed in an opening formed in an insulating film; A film growth method, comprising: forming a deposited layer; and forming a metal or semiconductor grown film on the deposited layer. 2. The adsorption layer contains a gas of the compound at 10 ²
Film growth method according to claim 1, wherein the forming by supplying amount to 10 ⁶ L. 3. The film growth according to claim 1, wherein the step of forming the growth film includes CVD, and the step of forming the adsorption layer is performed at a lower temperature than the step of forming the growth film. Method. 4. The growth film includes a group III element, a group IV element, a group V element, a mixture thereof, a compound thereof, W,
4. The semiconductor device according to claim 1, comprising a metal of Ti, Cu, Zr, Mo, Re, Cr, Au, and Ta and a compound of Si, B, and P of the metal. 5. Film growth method. 5. The step of forming an adsorption layer of the compound,
A hydrogen compound of any one of a group III element, a group IV element, and a group V element, a compound containing at least one halogen atom, or W, Ti, Cu, Zr, Mo, Re, C
The film growth according to any one of claims 1 to 4, comprising adsorbing any gas molecule of any one of a metal of r, Au, and Ta, an organic compound, and a complex on the surface of the base. Method. 6. The method according to claim 1, wherein the step of forming the deposited layer includes one of heating and light irradiation.
The method for growing a film according to Item. 7. An adsorption chamber having a gas inlet for receiving a supply of an adsorption gas from an adsorption gas source, an exhaust port connected to an exhaust device, an adsorption chamber having a heating mechanism, and a CVD apparatus connected to the adsorption chamber for performing CVD. A film growth apparatus having a growth chamber that can be used.