JP2005158761A - Thin film manufacturing method, semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique to form a low resistance barrier film at a low temperature. <P>SOLUTION: A catalyst material 21 is placed within a vacuum vessel 11, it is then heated, a raw material gas and a reactive gas are alternately introduced into the vacuum vessel 11, the raw material gas adsorbed to the surface of a film forming object 40 and the reactive gas are reacted with a radical which is decomposed to generate with the catalyst material 21. Accordingly, a thin film is laminated. A row resistance barrier film can be obtained at a low temperature. As the reactive gas, H<SB>2</SB>gas, NH<SB>3</SB>gas, and SiH<SB>4</SB>gas or the like can be used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the formation of a thin film, and more particularly to a technique for forming a metal barrier film at a low temperature.

  In order to form a thin film on the surface of a semiconductor substrate, a CVD apparatus or a sputtering apparatus is used.

  A conventional thin film manufacturing method will be described by taking a plasma CVD method as an example. Reference numeral 101 in FIG. 12 denotes a conventional CVD apparatus.

  Referring to this, this CVD apparatus 101 has a vacuum chamber 120, a hot plate 121 is disposed on the bottom wall inside the vacuum chamber 120, and a high-frequency electrode 122 is located near the interior ceiling. Has been placed.

  Lift pins 124 are inserted into the hot plate 121, and the lift pins 124 are operated to place the film formation target on the hot plate 121. A reference numeral 102 in FIG. 12 indicates a film formation target in that state. The film formation target 102 is heated by a heater in the hot plate 121.

  A raw material gas introduction system 127 and a high frequency power source 126 are connected to the high frequency electrode 122. A shower nozzle 123 is provided on the bottom surface of the high-frequency electrode 122, and the source gas supplied from the source gas introduction system 127 to the high-frequency electrode 122 is dispersed from the shower nozzle 123 into the vacuum chamber.

  When a high-frequency voltage is applied from the high-frequency power source 126 to the high-frequency electrode 122 in this state, source gas plasma is generated, and a thin film grows on Si or metal on the surface of the semiconductor substrate.

  However, in the film forming method, it is necessary to heat an object to be formed to a high temperature, and it cannot cope with a recent low temperature process.

Therefore, in the prior art, a method for forming a thin film at a low temperature has been studied. However, when a metal wiring or a metal barrier film is formed, there is a problem that the specific resistance of the obtained film is high.
JP, 2000-269163, A When a Cu film is partially exposed on a semiconductor substrate of a film formation object, copper oxide and a fluorine (F) component adhering in the previous etching process on the surface Since the carbon (C) component and the like remain, if an attempt is made to form a metal barrier film on the surface of the Cu film in this state, ohmic contact cannot be obtained between the metal barrier film and Cu.

  Therefore, in the prior art, in the process of cleaning the surface of the Cu film, hydrogen gas is introduced into the vacuum chamber and turned into plasma by applying a high frequency such as RF, and oxides on the Cu surface by excited hydrogen ions, The F component and C component insulators were removed. The Cu film surface to be processed is at the bottom of a fine hole (Via Hole). In a typical example in recent years, the hole diameter is about 0.13 μm, the hole depth is about 0.85 μm, and the aspect ratio is 5 or more.

  In the case of such a high aspect ratio, in general, even in a method such as RIE (Reactive Ion Etching), which has a high directivity of ions with respect to holes and grooves, hydrogen ions move into the holes due to the charge-up of the semiconductor substrate surface due to ion collisions. It is known that the entry of is inhibited.

  On the other hand, as a method that does not use plasma, there is a cleaning method that removes oxygen of copper oxide by a hydrogen reduction reaction. In this method, in order to perform the reduction reaction efficiently, the substrate temperature is 350 ° C. or higher. Because it is necessary, it cannot answer the recent demand for process temperature reduction.

  The present invention was created to solve the above-described disadvantages of the prior art, and an object thereof is to provide a technique for forming a low resistance barrier film at a low temperature.

In order to solve the above-mentioned problems, the invention according to claim 1 has a raw material gas introduction step of introducing a thin film raw material gas into a vacuum chamber, and has hydrogen atoms in the chemical structure in a state where the introduction of the raw material gas is stopped. A reactive gas is introduced into the vacuum chamber, and a reactive gas introduction step in which the reactive gas is brought into contact with a heated catalyst body is repeated, and a thin film is formed on the surface of the film formation target disposed in the vacuum chamber. A thin film manufacturing method to be formed.
According to a second aspect of the present invention, the vacuum chamber is evacuated with the introduction of both the source gas and the reactive gas stopped after the source gas introduction step and before the reactive gas introduction step. The thin film manufacturing method according to claim 1, further comprising a raw material gas exhausting step.
According to a third aspect of the present invention, the vacuum chamber is evacuated with the introduction of both the source gas and the reactive gas stopped after the reactive gas introduction step and before returning to the source gas introduction step. The thin film manufacturing method according to claim 1, further comprising a reactive gas exhausting step of exhausting.
According to a fourth aspect of the present invention, the reactive gas is one or more gases selected from the group consisting of H ₂ gas, NH ₃ gas, SiH ₄ gas, NH ₂ NH ₂ gas, and H ₂ O gas. The thin film manufacturing method according to any one of claims 1 to 3, wherein:
A fifth aspect of the present invention is the thin film manufacturing method according to any one of the first to fourth aspects, wherein the source gas is an organometallic gas.
A sixth aspect of the present invention is the thin film manufacturing method according to any one of the first to fifth aspects, wherein a metal wiring film is exposed on at least a part of the surface of the film formation target.
The invention according to claim 7 is the thin film manufacturing method according to claim 6, wherein an insulating film is disposed on the metal wiring film, and the metal wiring film is exposed at a bottom surface of the hole formed in the insulating film.
The invention according to claim 8 is the thin film manufacturing method according to any one of claims 1 to 7, wherein the thin film is formed after performing the pretreatment, wherein the pretreatment is performed in the vacuum chamber. In the state where the film formation target is arranged and the catalyst body is heated, the reactive gas is introduced into the vacuum chamber without introducing the source gas, and the reactive gas is brought into contact with the catalyst body. It is a thin film manufacturing method.
According to a ninth aspect of the present invention, there is provided a semiconductor device in which the film formation target is a semiconductor device, and the thin film is formed on the semiconductor device by the thin film manufacturing method according to any one of the first to eighth aspects. It is a manufacturing method.
A tenth aspect of the present invention is a semiconductor device comprising a thin film formed by the thin film manufacturing method according to any one of the first to eighth aspects.

  The present invention is configured as described above. A catalyst body made of W, Ta or the like is placed in a vacuum chamber, the atmosphere in the vacuum chamber is evacuated, and the catalyst body is placed in a vacuum atmosphere to 1500 to 500. Heated to 2000 ° C.

  The catalyst bodies are usually thin wires having a diameter of about 0.5 mm, and one or a plurality of catalyst bodies can be arranged in parallel or in a net shape.

  In this state, when a reactive gas having a hydrogen atom in the chemical structure is introduced into the vacuum chamber and brought into contact with the heated catalyst body, the reactive gas is decomposed and radicals are generated.

For example, when the reactive gas is H ₂ gas, H atoms are generated, and when the reactive gas is NH ₃ gas, NH and NH ₂ (general formula NH _x ) are generated. H atoms, NH, and NH ₂ are radicals.

  Radicals are extremely reactive and highly reducible, and even when the substrate temperature is 200 ° C. or lower, metal oxides, fluorides, carbides, etc. on the metal thin film surface or semiconductor surface are easily reduced, A clean surface of a thin film or semiconductor can be exposed.

  Further, when the source gas is introduced together with the introduction of the reactive gas, the source gas reacts with the radical, and a thin film is formed on the surface of the film formation target disposed in the vacuum chamber.

Even if a reactive gas is introduced and radicals are generated after the introduction of the source gas, the source gas adsorbed on the surface of the film formation target reacts to form a thin film.
If the introduction of the source gas and the introduction of the reactive gas are repeated, the thin film is laminated.

  Radical generation by introduction of a reactive gas can also be used for cleaning the surface of a film formation target. In particular, the surface of the semiconductor or metal thin film is exposed at the bottom of the fine groove or hole formed in the insulating film of the semiconductor manufacturing apparatus, but radicals easily reach the bottom of the fine groove or hole by diffusion. it can. Even when the film formation target is at a low temperature of 200 ° C. or lower, the surface of the bottom of the fine groove or hole can be cleaned.

  On the other hand, when plasma is used like RIE, ions are generated by collision of accelerated electrons and source gas in a three-dimensional space, and oxides and the like are decomposed by the ions.

Radicals such as H atoms and NH _x are electrically neutral and the film formation target does not charge up, whereas elements inside the semiconductor substrate are irradiated with ions on the film formation target. Damage may occur due to charge up.

  In addition, since the ions also cut the insulating film, the pattern shape of the insulating film falls. Furthermore, the decomposition efficiency of RIE oxide and the like is lower than that of the method of the present invention. (The decomposition efficiency of the present invention is expected to be about 10 to 100 times higher than that of plasma.)

A low resistance metal film can be formed at a low temperature.
Although it is particularly suitable for forming a barrier film on the surface of a copper thin film, it can also be used for forming a barrier film on the surface of a metal other than copper or a semiconductor.

<Vacuum processing equipment>
Reference numeral 10 in FIG. 1 is a vacuum processing apparatus that can be used in the method of the present invention, and has a vacuum chamber 11. A hot plate 13 is disposed on the bottom wall of the vacuum chamber 11. A clamp 15 is provided around the hot plate 13, and is configured to hold the processing object by the clamp 15 when the processing object is placed on the hot plate 13.

  A catalyst body 21 is disposed at a position directly above the hot plate 13 inside the vacuum chamber 11. The catalyst body 21 is connected to a power source 22. When the power source 22 is operated and a direct current or an alternating current is passed through the catalyst body 21, the catalyst body 21 generates heat to a high temperature. Here, a tungsten wire having a length of φ0.5 mm and 340 mm was used for the catalyst body 21.

  An evacuation system 36 is connected to the vacuum chamber 11, and the inside of the vacuum chamber 11 is configured to be in a high vacuum atmosphere. The catalyst body 21 is energized in a state where the inside of the vacuum chamber 11 is in a vacuum atmosphere, and generates heat to a high temperature.

  A gas inlet 34 is disposed at a position directly above the catalyst body 21 on the wall surface (ceiling) of the vacuum chamber 11. First to third gas introduction systems 31 to 33 are disposed outside the vacuum chamber 11, and the first to third gas introduction systems 31 to 33 are connected to the gas introduction port 34, respectively. .

The first to third gas introduction systems 31 to 33 have gas cylinders filled with different kinds of reactive gases. Here, the gas cylinders of the first to third gas introduction systems 31 to 33 are filled with H ₂ gas, NH ₃ gas, and SiH ₄ gas as reactive gases, respectively.

  In this vacuum processing apparatus 10, the reactive gas can be introduced into the vacuum chamber 11 from the gas introduction port 34 from any one or a plurality of systems of the first to third gas introduction systems 31 to 33 while controlling the flow rate. It is configured as follows.

  FIG. 2 is a schematic cross-sectional view of a film formation target 40 to which the method of the present invention is applied. The film formation target 40 is a semiconductor substrate in which the semiconductor manufacturing process has been performed halfway. On the silicon substrate 41, the first insulating film 42, the metal wiring film 43, and the second insulating film 44 are arranged in this order. It is formed with. Grooves and holes 45 are formed in the second insulating film 44, and the metal wiring film 43 is exposed on the bottom surfaces of the grooves and holes 45. The metal wiring film 43 is typically a copper thin film and is patterned into a predetermined planar shape. A part of the metal wiring film 43 is connected to an electric element formed on the silicon substrate 41.

  The inside of the vacuum chamber 11 is placed in a vacuum atmosphere, and the film formation target 40 as described above is carried into the vacuum chamber 11 while maintaining the vacuum state, and the surface on which the groove or hole 45 is located faces the catalyst body 21, and hot Place on the plate 13.

<Pretreatment>
The hot plate 13 is energized in advance, the film formation target 40 is placed, and the temperature is raised to 170 to 270 ° C.

Then, the reactive gas is introduced from the first to third gas introduction systems 31 to 33 in a state where the catalyst body 21 is energized to generate heat and the temperature is raised to a predetermined temperature. Here, only H ₂ gas was introduced from the first gas introduction system 31 as the reactive gas.

  The introduction amount (flow rate) was 200 sccm, and the pressure in the vacuum chamber 11 was set in the range of 0.8 to 65 Pa by controlling the evacuation speed.

  A tungsten wire having a diameter of 0.5 mm and a length of 300 mm is used for the catalyst body 21. The input power to the catalyst body 21 is set to a DC voltage of 13.0 V and 14.0 A, and the temperature of the catalyst body 21 is raised to about 1700 ° C.

  The reactive gas in contact with the catalyst body 21 generates hydrogen radicals, and the hydrogen radicals reduce oxides on the surface of the metal wiring film 43 exposed in the grooves of the film formation target 40 and the bottom surfaces of the holes 45, thereby cleaning them. The surface of a thin copper film is exposed.

Here, when the reactive gas (H ₂ gas) was introduced for 60 seconds with the catalyst body 21 at a high temperature, the oxide on the surface of the metal wiring film 43 on the bottom surface of the groove and hole 45 was removed.

Different from the above, in the case where NH ₃ gas alone or SiH ₄ gas alone is used as a reactive gas, mixing in which two or more of H ₂ gas, NH ₃ gas and SiH ₄ gas are selected and mixed Even when the gas is used as the reactive gas, the oxide on the surface of the metal wiring film 43 on the bottom surface of the groove or the hole 45 can be removed as in the case of the H ₂ gas.

<Example 1>
In the vacuum processing apparatus 10 of FIG. 1, reference numeral 35 denotes a barrier film source gas introduction system, and a barrier film source 38 is disposed in a container 36.

As the raw material 38, TIMATA (Ta [NC (CH ₃ ) ₂ C ₂ H ₅ ] [N (CH ₃ ) ₂ ] ₃ ), which is an organic metal source, is disposed, and the container 36 is heated to 80 ° C. By introducing and bubbling a carrier gas whose TIMATA is in a liquid state and whose flow rate is controlled, the TIMATA gas is generated as a raw material gas and introduced into the vacuum chamber 11 through the pipe 39. Here, Ar gas of 100 sccm was used as the carrier gas.

  The piping 39 and the vacuum chamber 11 were heated to 80 to 90 ° C. so that TIMATA was not liquefied in the raw material gas introduction path.

  The energization amount to the hot plate 13 is increased, the temperature of the film formation target 40 after the oxide removal by the above <pretreatment> is increased to 300 to 380 ° C., and the source gas and the reactive gas are simultaneously introduced into the chamber. The pressure in the vacuum chamber 11 was maintained at 2.0 Pa.

The temperature of the catalyst body 21 is maintained at about 1700 ° C., and the introduced reactive gas is decomposed by the heated tungsten wire to generate radicals. For example, NH and NH ₂ radicals are generated from NH ₃ gas.

These radicals and TIMATA, which is a metal source gas, cause a chemical vapor reaction (CVD) on the heated film formation target 40, and as shown in FIG. 3, the surface of the insulating film 44, grooves and holes 45. A thin film 46 is formed on the surface of the metal wiring film 43 exposed on the bottom surface and side surfaces of the metal wiring film 43. The thin film 46 formed in this embodiment is a Ta _x N film, and functions as a barrier film that prevents diffusion of the copper film formed on the thin film 46.

Here, NH ₃ gas is used as the reactive gas, but H ₂ gas, SiH ₄ gas, NH ₂ NH ₂ gas, or H ₂ O gas may be used. Any one of them may be used, or two or more of them may be used together.

<Measurement results>
FIG. 4 shows the specific resistance of the Ta _x N film and the temperature of the film formation target when the film is formed under the above conditions and when the catalyst body 21 is not heated and is formed under the same conditions as in the conventional thermal CVD method. It is the graph which showed this relationship.

  According to the method of the present invention, it can be seen that the specific resistance decreases as the temperature rises until the temperature of the film formation object reaches 370 ° C.

  On the other hand, in the conventional thermal CVD method, the specific resistance of the TaN film decreases only to a little less than 20000 μΩcm even when the temperature of the film formation target is increased.

  Next, FIGS. 5 and 6 are the results of AES analysis of the TaN film formed by raising the temperature of the film formation target to 350 ° C., respectively, and the horizontal axis represents the etching time, that is, the depth in the film thickness direction. Yes, the vertical axis represents the concentration of the constituent atoms. FIG. 5 shows the analysis result of the film formed according to the present invention, and FIG. 6 shows the analysis result of the film formed by the conventional thermal CVD method in which the catalyst body is not heated. From this result, it was found that the TaN film of the present invention has a carbon content of 2.4% lower than that of the prior art TaN film.

FIG. 7 shows the relationship between the specific resistance and the atomic ratio of the C component contained in the TaN film having a O ₂ content of 2.5% and a 5.4% TaN film prepared according to the present invention. is there. According to this result, it can be seen that the specific resistance rapidly decreases as the carbon component decreases.

  The reason why the specific resistance of the TaN film of the present invention is lower than that of the TaN film formed by the conventional thermal CVD method is considered to be because the content of the carbon component is low.

  As described above, according to the present invention, a TaN film having better film quality can be formed as compared with the conventional thermal CVD method.

<Example 2>
However, from the graph of FIG. 4, it is necessary to heat the film formation target to 375 ° C. in order to obtain a 2200 μΩcm TaN film. Since the current process temperature requirement for the Cu wiring process is 300 ° C. or lower, it is necessary to further lower the temperature.

While the vacuum chamber 11 is evacuated, a film formation target is placed in the vacuum chamber 11, the catalyst body 21 is heated, and then the evacuation and heating of the catalyst body 21 are continued while the source gas (TIMATA) Reactive gas (NH ₃ gas or H ₂ gas) is introduced alternately.

FIG. 8 is a timing chart of introduction of each gas, where symbol t ₁ is the introduction time of the source gas, symbol t ₂ is the exhaust time until the introduction of the reactive gas after stopping the introduction of the source gas, symbol t ₃ is the introduction time of the reactive gas, and t ₄ is the exhaust time until the introduction of the raw material gas after the introduction of the reactive gas is stopped.

The raw material gas during the introduction time t ₁ is the reactive gas is not introduced during the reaction gas introduction time t ₃ is the raw material gas is not introduced.

  Since the inside of the vacuum chamber 11 is continuously evacuated by the evacuation system, the residual gas inside the vacuum chamber is evacuated when the introduction of the source gas and the introduction of the reactive gas are stopped.

FIG. 9 shows the relationship between the introduction time t ₁ of the source gas and the specific resistance of the obtained TaN film.

The source gas introduction time t ₁ is 3 to 10 seconds, the time t ₂ until the introduction of the reactive gas after stopping the introduction of the source gas is 5 seconds, the reactive gas introduction time t ₃ is 20 seconds, the reaction time The time t ₄ from when the introduction of the property gas is stopped to when the raw material gas is introduced is 5 seconds.

There are three types of temperatures of the film formation target: 280 ° C., 300 ° C., and 320 ° C. Other conditions are the same as those in the first embodiment.
When the time t _{1 to} t ₄ is one cycle, a TaN film was formed repeatedly for 150 cycles.

  The result is shown in FIG. The horizontal axis represents the raw material gas introduction time, and the vertical axis represents the specific resistance. It can be seen that the shorter the introduction time of the source gas, the smaller the specific resistance. It is considered that only the atomic layer in the vicinity of the surface of the source gas adsorbed on the surface of the film formation target reacts with the radical, but the shorter the introduction time of the source gas in one cycle, Since the atomic layer adsorbed on the surface becomes thin, the ratio of low resistance TaN reacted with radicals is large and the residual amount of C is reduced. As a result, the specific resistance of the formed TaN film is considered to decrease.

  Therefore, it is expected that the specific resistance will be further reduced if the introduction time of the source gas in one cycle is further shortened.

<Example 3>
FIG. 10 shows the reactive gas (H ₂ gas) when the temperature of the film formation target is 300 ° C., the introduction time t ₁ of the source gas (TIMATA) is 3 seconds, and the exhaust times t ₂ and t ₄ are 5 seconds. is a graph showing the resistivity of the relationship between TaN film formed with the introduction time t _3.

  Although 300 ° C. is the upper limit temperature of the Cu wiring process, the result of FIG. 10 shows that the specific resistance was 2000 μΩcm even when the heating temperature of the film formation target was 300 ° C.

  FIG. 11 shows the result of AES analysis of the TaN film. The content of the carbon component that causes the deterioration of the film quality is extremely low as compared with the conventional CVD method, and is about 1.5%. This value is lower than in the case of FIG.

From these facts, the method of the present invention is a requirement for the Cu wiring process.
(1) Substrate temperature below 300 ° C
(2) Good quality film without carbon component
(3) Good STEP COVERAGE
Can be satisfied.

  Although the above description has been given of the case where the TaN film is formed, the present invention is not limited to the formation of the TaN film, but the raw material gas and the reactive gas are introduced into the vacuum atmosphere to react with the heated catalyst body. The radicals produced by contacting the reactive gas can be widely used in processes in which a raw material gas is chemically reacted to form a thin film on the surface of the film formation target.

Vacuum device that can be used in the present invention Deposition target of the present invention Diagram of a state where a thin film is formed on the film formation target The graph which shows the relationship between the film-forming temperature and specific resistance in this invention The graph which shows content of the depth direction of the impurity in the thin film formed by this invention A graph showing the depth content of impurities in a thin film formed by a conventional thermal CVD method The graph which showed the relationship between the atomic ratio of the C component contained in the TaN film formed by this invention, and specific resistance Gas introduction timing chart Graph showing the relationship between the introduction time of the source gas and the specific resistance of the TaN film Graph showing the relationship between the reactive gas introduction time and the resistivity of the formed TaN film Graph showing the results of AES analysis of the TaN film Conventional film deposition system

Explanation of symbols

10 …… Vacuum processing apparatus 11 …… Vacuum chamber 21 …… Catalyst body 40 …… Object for film formation

Claims (10)

  A raw material gas introducing step for introducing a thin film raw material gas into the vacuum chamber, and a reactive gas having a hydrogen atom in the chemical structure was introduced into the vacuum chamber in a state where the introduction of the raw material gas was stopped and heated. A method for producing a thin film, wherein a reactive gas introduction step for bringing the reactive gas into contact with a catalyst body is repeated, and a thin film is formed on the surface of a film formation target disposed in the vacuum chamber.   A source gas exhausting step for evacuating the vacuum chamber in a state where introduction of both the source gas and the reactive gas is stopped after the source gas introducing step and before the reactive gas introducing step. Item 2. The method for producing a thin film according to Item 1.   After the reactive gas introducing step, before returning to the raw material gas introducing step, a reactive gas exhausting step of evacuating the vacuum chamber in a state where introduction of both the raw material gas and the reactive gas is stopped is performed. The thin film manufacturing method of any one of Claim 1 or Claim 2 which has. The reactive gas is one or more gases selected from the group consisting of H ₂ gas, NH ₃ gas, SiH ₄ gas, NH ₂ NH ₂ gas, and H ₂ O gas. The thin film manufacturing method of any one of Claim 3.   The thin film manufacturing method according to any one of claims 1 to 4, wherein the source gas is an organometallic gas.   The thin film manufacturing method according to claim 1, wherein a metal wiring film is exposed on at least a part of the surface of the film formation target.   The thin film manufacturing method according to claim 6, wherein an insulating film is disposed on the metal film, and the metal wiring film is exposed at a bottom surface of the hole formed in the insulating film. The thin film manufacturing method according to any one of claims 1 to 7, wherein the thin film is formed after performing pretreatment.
In the pretreatment, the film-forming target is placed in the vacuum chamber, the reactive gas is introduced into the vacuum chamber without introducing the source gas, and the catalyst is heated. A method for producing a thin film, wherein the reactive gas is brought into contact with a medium.   The method for manufacturing a semiconductor device, wherein the film formation target is a semiconductor device, and the thin film is formed on the semiconductor device by the thin film manufacturing method according to claim 1.   A semiconductor device comprising a thin film formed by the thin film manufacturing method according to claim 1.

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