JP4644359B2 - Deposition method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film forming technique used when manufacturing a semiconductor device or an electronic device, and in particular, a method of forming a metal film, a metal oxide film, and a metal nitride film using a CVD (chemical vapor deposition) method. It is about.
[0002]
[Prior art]
In semiconductor devices such as semiconductor memories, logic LSIs, and system LSIs, and electronic devices such as liquid crystals and plasma displays and printed boards, metals that form wirings, insulating films, barrier films, etc. (in this specification, metals include Si) ) Film, metal oxide film, and metal nitride film are used. These films are often formed by sputtering, vacuum deposition, plating, or the like. Of these film formation methods, sputtering and vacuum deposition are relatively simple film formation methods. Although uniform film formation is possible on a flat surface, uniform film formation on an uneven surface is possible. Have difficulty. In particular, film formation on the bottom and side walls of deep holes and grooves is difficult.
In addition, the plating method can form a uniform film on an uneven surface, but it is generally difficult to control the formation of a thin film because the film formation speed is high. Further, it is a wet film forming method that is immersed in a chemical solution, and a chemical solution containing metal also wraps around in an undesired portion, causing contamination.
[0003]
[Problems to be solved by the invention]
In contrast to these methods, the CVD (Chemical Vapor Deposition) method, particularly the LPCVD (Low Pressure CVD) method, which forms a film at an atmospheric pressure below atmospheric pressure, can deposit a thin film with good controllability on an uneven surface. Although it is a film | membrane method, the raw material which can transport a raw material to the film-forming surface in a gaseous phase is required.
[0004]
As a method of depositing a metal and its compound by the CVD method, a method using a metal halide obtained by reacting a halogen such as Cl (chlorine) with a metal, or an organic metal such as TMA (trimethylaluminum) or TEA (triethylaluminum). There is a MOCVD (Metal Organic CVD) method that uses metal halide, but in the method using a metal halide, halogen such as Cl remains in the obtained film, and there is a concern about deterioration due to corrosion or the like for a long time use. The In addition, the MOCVD method using an organic metal is not concerned with deterioration due to residual halogen, but selection and synthesis of an appropriate organic metal raw material is an important issue, and there is always an appropriate organic metal raw material for a desired metal material. Not necessarily.
[0005]
An object of the present invention is to solve the above-described problems of the prior art, and its purpose is to control the metal and its compound evenly even if the film formation surface of a semiconductor device or an electronic device is uneven. It is possible to manufacture a semiconductor device and an electronic device having good performance so that they can be deposited with good performance.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention , one or a plurality of M [N (C ₂ H ₅ ) ₂ ] ₄ (where M is a metal (including Si, hereinafter the same) ) Elemental material) is introduced, and a metal (including alloy) film is deposited by chemical vapor deposition (CVD). After deposition, the temperature is 50 to 200 ° C. higher than the temperature during deposition. There is provided a film forming method characterized by performing heat treatment at a temperature. According to the present invention, one or more kinds of M [N (C ₂ H ₅ ) ₂ ] ₄ (wherein M is a metal (including Si, excluding Ti, the same shall apply hereinafter) element in the film forming chamber. ), A metal compound film is deposited by a chemical vapor deposition (CVD) method, and heat treatment is performed at a temperature 50 to 200 ° C. higher than the temperature during the deposition after the deposition. A film forming method is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an example of a film forming apparatus for explaining an embodiment of the present invention. In the present invention, film formation is performed using, for example, a cold wall type LPCVD apparatus shown in FIG. A heater block 2 for heating the substrate is installed in the film forming chamber 1, and a substrate 4 is mounted thereon via a substrate table 3.
The temperature of the substrate 4 during film formation is controlled to, for example, 100 to 600 ° C. by the heater in the heater block 2. When step coverage is prioritized, a substrate temperature of 450 ° C. or lower, more preferably 400 ° C. or lower is selected. For example, Ta [N (C ₂ H ₅ ) ₂ ] ₄ 6 is supplied into the bubbler 5 as a raw material, and the source gas is transported to the film forming chamber 1 by flowing H ₂ gas as a carrier gas while being heated by the heater 7. The supply amount of the source gas is controlled by adjusting the flow rate of the H ₂ gas by the mass flow controller 8a.
The inside of the film forming chamber 1 is evacuated by a combination of a turbo molecular pump 10 and a rotary pump 11 through an orifice 9, and the pressure in the film forming chamber at the time of film deposition is controlled to 1 to 100 Torr (133.3 to 13332 Pa), for example. Is done.
[0008]
In the case of forming a Ta film that is a metal film, only Ta [N (C ₂ H ₅ ) ₂ ] ₄ is supplied as a source gas [however, as will be described later, Ta [N (C ₂ H ₅ )]. ₂ ] ₄ is mixed with NC ₂ H ₅ Ta [N (C ₂ H ₅ ) ₂ ] ₃ ]. When a Hf (hafnium) film, a Zr (zirconium) film, a Ti (titanium) film, or a Si (silicon) film, which is another metal film, is used instead of the Ta film, Hf [N (C ₂ H ₅ ) ₂ ] ₄ , Zr [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (C ₂ H ₅ ) ₂ ] ₄ or Si [N (C ₂ H ₅ ) ₂ ] ₄ are supplied. Further, when forming an alloy film of these metals, a plurality of raw materials among them are supplied simultaneously. For example, when TiSi is formed, Ti [N (C ₂ H ₅ ) ₂ ] ₄ gas and Si [N (C ₂ H ₅ ) ₂ ] ₄ gas are simultaneously supplied into the film formation chamber.
After the metal (including alloy) film is formed, heat treatment is performed at a temperature higher by 50 to 200 ° C. than the temperature at the time of film formation. As a result, C, N, etc. which are released and remaining in the film can be released, and the film quality can be increased and the sheet resistance can be reduced. This heat treatment is desirably performed at a temperature of 400 ° C. or higher. This is because it is difficult to sufficiently improve the film quality at temperatures below this. The heat treatment after the film deposition can be performed following the film deposition in the film formation chamber 1, but the heat treatment may be performed using a lamp annealer taken out from the film formation chamber.
[0009]
When forming a metal oxide film, M [N (C ₂ H ₅ ) ₂ ] ₄ (where M is a metal element) and a material capable of supplying oxygen onto the substrate 4, such as O _2, are formed in the film formation chamber 1. To supply. The flow rate of O ₂ gas is adjusted by the mass flow controller 8b.
For example, when forming a Ta ₂ O ₅ film, O ₂ is introduced into the film forming chamber together with Ta [N (C ₂ H ₅ ) ₂ ] ₄ gas. Instead of O ₂ , N ₂ O, NO, H ₂ O may be used, or a plurality of these oxidizing gases may be supplied simultaneously.
When an alloy oxide film or a metal oxide mixture film is formed, an oxidizing gas is supplied together with a plurality of types of M [N (C ₂ H ₅ ) ₂ ] ₄ .
[0010]
In the case of forming a metal nitride film, M [N (C ₂ H ₅ ) ₂ ] ₄ (where M is a metal element) and a material capable of supplying nitrogen onto the substrate 4, for example, NH _3, are formed in the film formation chamber 1. Introduce. The flow rate of NH ₃ gas is adjusted by the mass flow controller 8c.
For example, when forming a TiN film, NH ₃ is introduced into the film forming chamber together with Ti [N (C ₂ H ₅ ) ₂ ] ₄ gas. N ₂ may be used instead of NH ₃ , and both NH ₃ gas and N ₂ gas may be supplied simultaneously.
When forming an alloy nitride film or a metal nitride mixture film, a nitriding gas is supplied together with a plurality of types of M [N (C ₂ H ₅ ) ₂ ] ₄ .
[0011]
FIG. 2 shows the molecular structure obtained as a result of analyzing an organometallic raw material in which M (metal element) is Ta using a technique such as chromatography. It became clear that this organic raw material actually contains two kinds of molecules having different structures. When the central metal element M was Hf, Zr, Ti, or Si instead of Ta, the structure was M [N (C ₂ H ₅ ) ₂ ] ₄ as shown in FIG.
[0012]
【Example】
Next, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[Example 1]
As Example 1, a Ta film was formed using Ta [N (C ₂ H ₅ ) ₂ ] ₄ gas as a source gas by the LPCVD apparatus shown in FIG.
The substrate 4 is an untreated Si substrate, a SiO ₂ substrate prepared by thermally oxidizing the surface of the Si substrate, and a substrate obtained by processing a groove having a width of 2.0 μm and a depth of 5 μm (aspect ratio = 2.5) on the Si substrate. Using.
In order to prevent liquefaction of the source gas inside the pipe, the pipe from the bubbler 5 to the film forming chamber 1 was heated to about 80 ° C. by means not shown. In this embodiment, the substrate temperature is changed to 100 to 600 ° C. by controlling the heater in the heater block 2, the temperature of the heater 7 is maintained at 60 ° C., and the H ₂ gas flow rate is adjusted to 10 sccm by the mass flow controller 8a. . Further, the pressure in the film forming chamber 1 was maintained at 10 Torr (1333 Pa).
After film deposition, the temperature was raised by 50 to 200 ° C. above the film deposition temperature, and heat treatment was applied for 1 second to 1 hour.
[0013]
The film thickness of the deposited film is measured by a step gauge and SEM (scanning electron microscope), the resistance of the film is measured by a four-probe method, and the crystal structure of the film is observed by a TEM (transparent electron microscope). The impurities in the film were examined by SIMS (secondary ion mass spectroscopy).
When the deposition temperature was 400 ° C. or lower, a rapid decrease in the growth rate was observed as the temperature decreased. However, when the deposition temperature was 400 ° C. or higher, a substantially constant growth rate was obtained regardless of the substrate temperature. According to the result of SEM observation after forming the film on the substrate on which the groove was processed, it was confirmed that almost constant film thickness was achieved at the top, bottom and side surfaces of the groove at a substrate temperature of 400 ° C. or lower. It was. This result is an excellent feature that cannot be achieved at all by the conventional sputtering method performed for comparison. When the substrate temperature is raised to 450 ° C., the groove bottom film thickness / flat film thickness, which is an indicator of step coverage, is reduced to about 0.75, but sufficient film thickness necessary to ensure barrier properties is obtained. I was able to.
[0014]
The resistivity of the film was lower as the substrate temperature was higher, and 0.01-1.0 Ω · cm could be obtained at a substrate temperature of 400 to 600 ° C. Therefore, according to the present invention, it has been found that a film having both characteristics of step coverage and low resistance necessary for forming an LSI barrier film can be formed. However, for the sample not subjected to post heat treatment after deposition, since the residual C in the film was large and the film density was low, the resistance value was 10 to 100 times that after the heat treatment. According to the analysis using SIMS, the obtained film showed a composition containing a small amount of C and N in Ta, and no component such as Cl contributing to the deterioration of the film was found. Further, according to the analysis by TEM, the film deposited at 400 ° C. had an amorphous structure.
[0015]
Using the same apparatus, Hf [N (C ₂ H ₅ ) ₂ ] ₄ , Zr [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (C ₂ H ₅ ) ₂ ] ₄ , Si [N (C ₂ H ₅ ) ₂ ] ₄ , the temperature of the heater 7 of the bubbler 5 is selected to a value suitable for each raw material according to the respective characteristics, so that Ta [N (C ₂ H ₅ ) ₂ ] ₄ The film could be formed as in the case. Furthermore, an alloy film could be formed by supplying two or more kinds of raw materials simultaneously. With regard to this alloy film formation, advantages such as easy control of the composition were obtained by using a material having a similar material structure compared to other methods.
[0016]
[Example 2]
The LPCVD apparatus shown in FIG. 1 is used in the same manner as in Example 1, the other conditions are the same, and O ₂ is simultaneously supplied to Ta [N (C ₂ H ₅ ) ₂ ] ₄ by the mass flow controller 5b. When adjusted to 0.01 to 1000 ml and supplied into the deposition chamber, a Ta oxide film could be deposited. The amount of oxygen in the film increased as the O ₂ flow rate increased, and was saturated at a stoichiometric value. A similar change was also observed in the dielectric constant.
Instead of Ta [N (C ₂ H ₅ ) ₂ ] ₄ , Hf [N (C ₂ H ₅ ) ₂ ] ₄ , Zr [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (C ₂ H ₅ ) ₂ ] ₄ , Si [N (C ₂ H ₅ ) ₂ ] _4, etc. were supplied simultaneously with O _2, and metal oxide films of the respective materials could be formed. For these materials, the amount of oxygen in the film increased as the O ₂ flow rate increased, and was saturated at a stoichiometric value. Further, in the same manner as in Example 1, two or more kinds of raw materials were simultaneously supplied to obtain an alloy oxide.
[0017]
Any of these metal oxide films has a high dielectric constant, and can be used as a dielectric in a semiconductor device or an electronic device. An oxide made of an alloy of another metal and Si is called a silicate and is known to be thermally stable. Further, instead of O _2, or O ₂ at the same time as N ₂ O, NO, likewise metal oxide film be supplied of H ₂ O, etc. were obtained. Compared to the sputtered film deposited for comparison, it has better penetration into trench holes, etc., and it is possible to form a uniform film on any surface and affect the reliability of Cl, etc. It was the same as in Example 1 that there were no residual impurities, the density was improved by the heat treatment after deposition, and other characteristics were also improved.
[0018]
[Example 3]
As in Example 1, the LPCVD apparatus shown in FIG. 1 was used, and the other conditions were the same. At the same time as Ta [N (C ₂ H ₅ ) ₂ ] ₄ , the mass flow controller 8c changed the flow rate to 0. When NH ₃ was supplied into the film forming chamber 1 after adjusting to 01 to 1000 ml, a Ta nitride film was formed. The amount of nitrogen in the film increased as the NH ₃ flow rate increased, and saturated with the stoichiometric value.
Further, instead of Ta [N (C ₂ H ₅ ) ₂ ] ₄ , Hf [N (C ₂ H ₅ ) ₂ ] ₄ , Zr [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (C ₂ H ₅ ) When ₂ ] ₄ , Si [N (C ₂ H ₅ ) ₂ ] _{4 and the} like are simultaneously supplied with 0.01 to 1000 ml of NH ₃ per minute, a metal nitride film of each material can be formed. did it. Also in the metal nitride films of these materials, the amount of nitrogen in the film increased as the NH ₃ flow rate increased, and was saturated at a stoichiometric value. Further, in the same manner as in Example 1, two or more kinds of raw materials were supplied simultaneously to obtain an alloy nitride.
[0019]
Any of these metal nitride films has a high ability to prevent diffusion of other metals, and can be used as a barrier film in a semiconductor device or an electronic device. In FIG. 4, a TiN (titanium nitride) thin film is deposited on a Si substrate to a thickness of 0.1 μm at 400 ° C., heat treated at 470 ° C. for 30 minutes, Cu is deposited thereon, and then It is a figure which shows the result of having performed the post-heat treatment for 1 hour at 550 degreeC, and evaluating the barrier performance with respect to Cu of a TiN thin film. The horizontal axis represents depth, and the vertical axis represents Cu concentration. As is apparent from this figure, it is understood that Cu diffusion is prevented by the TiN thin film.
Similarly, the metal nitride film be also or supplying NH ₃ at the same time N ₂ with N ₂ was obtained instead of NH _3. Compared to the sputtered film deposited for comparison, it has better penetration into trench holes, etc., and it is possible to form a uniform film on any surface and affect the reliability of Cl, etc. It was confirmed in the same manner as in Example 1 and Example 2 that there were no residual impurities, and that the density was improved by the heat treatment after deposition and other characteristics were improved.
[0020]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and appropriate modifications can be made without departing from the scope of the present invention. .
[0021]
【The invention's effect】
As described above, the metal film, metal oxide film, or metal nitride film deposition method according to the present invention uses Hf [N (C ₂ H ₅ ) ₂ ] ₄ , Ta [N (C ₂ ) as the organometallic raw material. H ₅ ) ₂ ] ₄ , Zr [N (C ₂ H ₅ ) ₂ ] ₄ , Ti [N (C ₂ H ₅ ) ₂ ] ₄ , Si [N (C ₂ H ₅ ) ₂ ] ₄ Since each metal film is heat treated at a temperature higher than the temperature during deposition, the metal and its compounds (oxides, nitrides, etc.), which are indispensable for manufacturing semiconductor devices and electronic devices, are formed on the uneven surface. Can be deposited with good controllability, and semiconductor devices and electronic devices having good performance can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view of an LPCVD apparatus for explaining embodiments and examples of the present invention.
FIG. 2 is a molecular structure diagram of raw materials used in the present invention (part 1).
FIG. 3 is a molecular structure diagram of raw materials used in the present invention (part 2).
FIG. 4 is a view showing barrier performance against Cu of a TiN thin film formed on a Si substrate.
[Explanation of symbols]
1 Deposition chamber 2 Heater block 3 Substrate base 4 Substrate 5 Bubbler 6 Ta [N (C ₂ H ₅ ) ₂ ] ₄
7 Heaters 8a to 8c Mass flow controller 9 Orifice 10 Turbo molecular pump 11 Rotary pump

Claims (13)

An organic material represented by one or more kinds of M [N (C ₂ H ₅ ) ₂ ] ₄ (where M is a metal (including Si, hereinafter the same) element) is introduced into the deposition chamber, A film forming method comprising depositing a metal (including alloy) film by a chemical vapor deposition (CVD) method, and performing a heat treatment at a temperature higher by 50 to 200 ° C. than the temperature during the deposition after the deposition. .  One or more types of M [N (C ₂ H _Five ) ₂ ] _Four (However, M is an organic material represented by a metal (including Si and excluding Ti, the same applies below)), and a metal compound film is deposited by a chemical vapor deposition (CVD) method. A film forming method comprising performing heat treatment at a temperature 50 to 200 ° C. higher than a temperature during deposition after deposition.  2. The film forming method according to claim 1, wherein the M is any one of Hf, Ta, Zr, Ti, and Si.  The film forming method according to claim 2, wherein the M is any one of Hf, Ta, Zr, and Si. And accumulation of the metal film, the film forming method according to claim 1 or 3, characterized in that the post-deposition heat treatment in an atmosphere containing no vacuum or oxygen. The metal oxide film is deposited by supplying one or more of O ₂ , N ₂ O, NO, and H ₂ O simultaneously with the organic material in the film forming chamber. 5. The film forming method according to 2 or 4 . The film forming method according to claim 6 , wherein the heat treatment after the metal oxide film is deposited is performed in an atmosphere containing oxygen. The deposition chamber, the organic raw material at the same time, formed according to claim 2 or 4 by supplying either one or both in the N _2, NH _3, characterized in that depositing a metal nitride film Membrane method. 9. The film forming method according to claim 8 , wherein the heat treatment after depositing the metal nitride film is performed in an atmosphere containing nitrogen. When M is Ta, N (C ₂ H ₅ ) Ta [N (C ₂ H ₅ ) ₂ ] ₃ is introduced into the deposition chamber in addition to Ta [N (C ₂ H ₅ ) ₂ ] _4. The film forming method according to any one of claims 1 to 9, wherein The film forming method according to any one of claims 1-10, characterized in that H ₂ is used as a carrier gas for the organic raw material. The film forming method according to any one of claims 1 to 11, characterized in that the film deposited at 450 ° C. or lower. The film forming method according to any one of claims 1 to 12, characterized in that performing the heat treatment at 400 ° C. or higher.

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