KR101290957B1 - Film formation method and film formation apparatus - Google Patents

Abstract

An object of the present invention is to cause a film formation reaction in a reaction rate region, so that even a contact hole having a large aspect ratio is formed into a thinner and better coverage titanium film, thereby reducing the resistance of the contact hole.
A high frequency power supply for supplying the susceptor 112 for loading the substrate W, the shower head 120 for supplying the processing gas into the process chamber 111, and the high frequency for generating plasma to the shower head at a predetermined power ( 143, the exhaust device 152 which exhausts the inside of the processing chamber and reduces the pressure to a predetermined pressure, and the flow rate of the reducing gas so that the flow rate of the film forming gas to be applied to the film forming process of the titanium film enters the reaction rate rate region of the film forming process. The controller 190 which controls the reaction rate region by changing any one of pressure in the processing chamber and high frequency power was provided.

Description

TECHNICAL FIELD [0001] The present invention relates to a film forming method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method and a film forming apparatus for depositing a predetermined film on a substrate to be processed, such as a semiconductor wafer, a flat panel display (FPD) substrate, a liquid crystal substrate, or a solar cell substrate.

A semiconductor device such as a CMOS transistor has a connection structure such as a wiring layer and a substrate, and a wiring layer and a wiring layer. Specifically, for example, as shown in FIG. 17, a contact hole 20 is formed between the p / n impurity diffusion layer (diffusion layer) 10 of the Si substrate (Si wafer) and the first wiring. The via hole 30 is formed between the wiring and the second wiring. Such contact holes 20 and via holes 30 are filled with a metal such as tungsten or copper, and the Si substrate and the wiring layer are electrically connected to each other. In recent years, barrier layers such as Ti / TiN laminated films are formed in the contact holes 20 and the via holes 30 prior to the embedding of the metal, so that the barrier layers 22 and 32 are formed.

Conventionally, physical vapor deposition (PVD) has been used to form such a Ti film or a TiN film. By the way, in the present time of miniaturization and high integration of a semiconductor device, the aspect ratio (ratio of a diameter and a depth) of a contact hole and a via hole becomes extremely large. For this reason, the chemical vapor deposition (CVD) method with favorable step coverage is employ | adopted for formation of a barrier layer.

By the way, in order to lower the contact resistance of the metal in the diffusion layer 10 and the contact hole 20, for example, an alloy layer 12 such as a TiSi _x film (titanium silicide film) is provided between the barrier layer 22 and the diffusion layer 10. It is preferable to lower the Schottky barrier based on the work function difference by adjusting the work function at the interface between the barrier layer 22 and the diffusion layer 10 through the?).

For example, plasma CVD can be used to form such a TiSi _x film. In this method, TiCl ₄ is used as the source gas and H ₂ gas or the like is used as the reducing gas, and a Ti film is formed at a temperature of about 650 ° C., and at the same time, a portion thereof is reacted with the Si substrate to self-align the alloy layer. (12) is formed (for example, refer patent document 1).

Japanese Patent Application Laid-open No. 2000-049142

By the way, when forming the above-mentioned Ti film | membrane conventionally, since the flow rate ratio of the film-forming gas with respect to reducing gas was reduced in order to raise a film-forming rate like patent document 1, and to raise a film-forming efficiency (patent document 1 in flow rate ratio 0.01 Degree), when the TiCl ₄ gas was supplied, the film formation reaction occurred in the feed rate region where the reaction proceeds with TiCl ₄ gas.

That is, in the supply rate region, the deposition rate increases as the flow rate ratio of the deposition gas increases. On the other hand, in general, in the reaction rate region, since the film formation reaction is controlled at a temperature, all of the supplied film forming gases do not react, and the film forming efficiency is significantly reduced.

However, in the conventional film formation reaction in the supply rate region, the film formation reaction occurs near the substrate surface, and the film forming gas is consumed therein, so that the hole diameter of the contact hole is small, and the aspect ratio becomes hard to reach the bottom. In particular, in recent years, since the aspect ratio of the contact hole and the via hole (a ratio between the diameter and the depth) is gradually increasing, the film thickness of the bottom of such a contact hole becomes thinner than the film thickness of the substrate surface, resulting in a deterioration in coverage. have.

Accordingly, the present invention has been made in view of the above problems, and its object is to cause a film formation reaction in the reaction rate region, so that even a contact hole having a large aspect ratio can form a thinner and better coverage titanium film. The present invention provides a film forming method capable of reducing the resistance of the bottom of a contact hole.

In order to solve the said subject, according to some aspect of this invention, it is a method of forming a titanium film on a to-be-processed substrate by supplying the process gas containing a titanium containing film-forming gas and a reducing gas to a process chamber, and forming a plasma, The said Among the high frequency power applied to the electrode for generating the flow rate of the reducing gas, the pressure in the processing chamber, and the plasma so that the flow rate of the film forming gas to be applied to the film forming process of the titanium film enters the reaction rate region of the film forming process. By changing any one of them, there is provided a film forming method characterized by controlling the reaction rate region.

In this case, you may control so that the flow volume of the said source gas used as the boundary of the reaction rate speed area | region of the said film-forming process may become large by increasing the said reducing gas flow volume. Moreover, you may make it control so that the flow volume of the said source gas used as the boundary of the reaction rate speed area | region of the said film-forming process may become large by increasing the pressure in the said process chamber. Moreover, you may control so that the flow volume of the said source gas used as the boundary of the reaction rate speed area | region of the said film-forming process may become large by increasing the said high frequency power.

The flow rate of the film forming gas is preferably set in a range such that the flow rate ratio of the film forming gas to the reducing gas flow rate is 13 sccm / 100 sccm or more and 55 sccm / 100 sccm or less. The flow rate of the film forming gas may be set in a range such that the flow rate ratio of the film forming gas to the reducing gas flow rate is 13 sccm / 100 sccm or more and 45.6 sccm / 100 sccm or less, and the flow rate ratio of the film forming gas to the reducing gas flow rate is 45.6 sccm. You may set in the range which becomes / 100sccm or more and 55sccm / 100sccm or less.

In order to solve the above problems, according to another aspect of the present invention, there is provided a method of forming a titanium film on a substrate to be treated by supplying a processing gas containing a titanium-containing film forming gas and a reducing gas into the processing chamber to generate a plasma. The film formation in the reaction rate region of the film forming process determined by the processing conditions of the film forming process including a flow rate of the film forming gas, a flow rate of the reducing gas, a pressure in the processing chamber, and a high frequency power applied to an electrode to generate the plasma. A film forming method is provided by reacting a gas with a reducing gas to form a titanium film on the substrate to be processed.

In order to solve the above problems, according to another aspect of the present invention, by forming a plasma by supplying a processing gas containing a titanium-containing film forming gas and a reducing gas into the processing chamber, to form a titanium film on the substrate to be processed contact hole formed A film forming apparatus, comprising: a susceptor for loading the substrate to be processed, a shower head for supplying the processing gas into the processing chamber, and a high frequency wave for generating a plasma between the susceptor with a predetermined power to the shower head. The high-frequency power supply to be exhausted, the exhaust device for evacuating the inside of the processing chamber to reduce the pressure to a predetermined pressure, and the flow rate of the film forming gas to be applied to the film forming process of the titanium film to enter the reaction rate rate region of the film forming process. The reaction is performed by changing one of a gas flow rate, a pressure in the processing chamber, and the high frequency power. The film forming apparatus comprising a control unit for controlling the inside region.

According to the present invention, the film formation reaction can be caused in the reaction rate region, so that even a contact hole having a large aspect ratio can form a thinner and better coverage titanium film, thereby reducing the resistance of the contact hole.

1 is a cross-sectional view showing a configuration of a film forming apparatus according to an embodiment of the present invention.
FIG. 2A is a process chart for explaining a film forming process according to the embodiment of FIG. 1. FIG.
FIG. 2B is a process chart for explaining the film forming process according to the embodiment of FIG. 1. FIG.
3 is a conceptual diagram for explaining the coverage in the case where a Ti film is formed in a contact hole having a large aspect in the supply rate mode.
4 is a conceptual diagram for explaining the coverage when a Ti film is formed in a contact hole having a large aspect in the reaction rate mode.
Fig. 5 is a graph showing the relationship between the flow rate of TiCl ₄ gas and the film formation rate in the case where a Ti film is formed on a Si film.
Fig. 6 is a graph showing the relationship between the flow rate of TiCl ₄ gas and the film formation rate when a Ti film is formed on a SiO ₂ film.
7 shows experimental results for evaluating the H ₂ gas flow rate dependency in a reaction rate region.
FIG. 8 is a diagram showing a relationship between the flow rate of the H ₂ gas shown in FIG. 7 and the flow rate of the TiCl ₄ gas at the boundary between the reaction rate region. FIG.
9 is a graph showing experimental results for evaluating pressure dependency in a processing chamber of a reaction rate region.
FIG. 10 is a diagram showing a relationship between the pressure in the processing chamber shown in FIG. 9 and the flow rate of TiCl ₄ gas at the boundary between the reaction rate region. FIG.
11 shows experimental results for evaluating the RF power dependency of the reaction rate region.
FIG. 12 is a diagram showing a relationship between the RF power and the flow rate of TiCl ₄ gas at the boundary between the reaction rate region shown in FIG. 11; FIG.
Fig. 13 is a graph showing the relationship between the flow rate of TiCl ₄ gas and the specific resistance of the formed Ti film.
FIG. 14 is a diagram of a graph of the film formation rate when the H ₂ gas flow rate 30 sccm and RF power 500 W shown in FIG. 6 overlap with the graph of the specific resistance shown in FIG. 13.
FIG. 15 is a diagram showing experimental results when a Ti film was actually formed in a contact hole. FIG.
16 is a partially enlarged view of each part (upper part, side part, lower part) shown in FIG. 15;
17 is a schematic diagram illustrating a wiring structure of a semiconductor device.

Best Modes for Carrying Out the Invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description will be omitted.

(Film forming apparatus)

The structural example of the film-forming apparatus which can implement the film-forming method which concerns on embodiment of this invention is demonstrated, referring drawings. 1 is a diagram illustrating a schematic configuration of a film forming apparatus according to the present embodiment. The film forming apparatus 100 is an example in which the film forming apparatus 100 is configured as a plasma CVD apparatus which forms a Ti film on a Si substrate W as a substrate to be processed by plasma CVD (plasma-enhanced chemical vapor deposition).

As shown in FIG. 1, the film-forming apparatus 100 is equipped with the process chamber (chamber) 111 comprised by the substantially cylindrical process container comprised airtight. In the processing chamber 111, a susceptor 112 for horizontally supporting the Si substrate W is disposed in a state supported by a cylindrical support member 113 provided below the center thereof. The susceptor 112 is made of ceramics such as AlN, and a guide ring 114 for guiding the Si substrate W is provided at an outer edge thereof.

In addition, a heater 115 is embedded in the susceptor 112, and the heater 115 feeds power from the heater power supply 140 to heat the Si substrate W to a predetermined temperature. That is, the heater 115 and the heater power supply 140 constitute a temperature adjusting means. The lower electrode 116 is embedded in the susceptor 112 on the heater 115, and the lower electrode 116 is grounded, for example.

The shower head 120 is provided in the ceiling wall 111A of the processing chamber 111 through the insulating member 119. The shower head 120 is largely divided into an upper base member 121 and a shower plate 122 provided below the base member 121. A heater 123 for heating the shower head 120 is embedded in the base member 121. The heater power source 141 is connected to this heater 123. The controller controls the shower head 120 to be heated to a predetermined temperature by controlling the heater 123 by the heater power source 141.

The shower plate 122 is provided with a plurality of discharge holes 124 for discharging gas in the processing chamber 111. Each discharge hole 124 communicates with the gas diffusion space 125 formed between the base member 121 and the shower plate 122. The gas introduction port 126 for supplying a process gas to the gas diffusion space 125 is provided in the center part of the base member 121. The gas introduction port 126 is connected to the mixed gas supply line 138 of the gas supply means 130 described later.

The gas supply means 130 includes a TiCl ₄ gas source 131 for supplying TiCl ₄ gas, which is a Ti compound gas, an Ar gas supply source 132 for supplying Ar gas, and an H ₂ gas supply source for supplying H ₂ gas, which is a reducing gas. Has 133.

And, TiCl ₄ gas supply source 131, the TiCl ₄ gas supply line and the (131L) are connected, Ar-gas supply source 132, the Ar gas supply line (132L) is is connected, H ₂ gas supply source 133 is The H ₂ gas supply line 133L is connected. Each of the gas lines 131L to 133L is provided with two valves 131V to 133V between the mass flow controllers (MFC) 131C to 133C and the mass flow controllers 131C to 133C, respectively.

The gas mixing unit 137 has a function of mixing the above-described process gas and supplying it to the shower head 120. The gas inlet side has a process gas supply source 131 to 133 through each gas line 131L to 133L. The shower head 120 is connected to the gas outflow side via the mixed gas supply line 138.

In the process, a gas selected from one of TiCl ₄ gas, Ar gas, and H ₂ gas or a mixed gas of a plurality of gases passes through the gas introduction port 126 and the gas diffusion space 125 of the shower head 120. And is introduced into the processing chamber 111 from the plurality of discharge holes 124.

Thus, although the shower head 120 which concerns on this embodiment is comprised by what is called a pre-mix type which mixes process gas in advance and supplies it to the process chamber 111, the post mix which supplies each process gas independently into the process chamber 111 is shown. It may be configured as a type.

The high frequency (RF) power source 143 is connected to the shower head 120 via the matching unit 142, and at the time of film formation, the high frequency power of 450 kHz from the high frequency power source 143 to the shower head 120, for example. By supplying the RF, a high frequency electric field is generated between the shower head 120 and the lower electrode 116, and the process gas supplied into the processing chamber 111 is converted into a plasma to form a Ti film.

The circular hole 117 is formed in the center part of the bottom wall 111B of the process chamber 111, and the exhaust chamber 150 which protrudes below so that this hole 117 is covered is provided in the bottom wall 111B. . An exhaust pipe 151 is connected to the side surface of the exhaust chamber 150, and an exhaust device 152 is connected to the exhaust pipe 151. The exhaust device 152 can reduce the pressure in the processing chamber 111 to a predetermined vacuum pressure.

The susceptor 112 includes a plurality of support pins (for example, three lift pins) 160 for supporting and elevating the Si substrate W so as to protrude from the surface of the susceptor 112. These support pins 160 are fixed to the support plate 161. And the support pin 160 is lifted up and down via the support plate 161 by the drive mechanism 162, such as an air cylinder. A sidewall 111C of the processing chamber 111 is provided with a carry-in / out port 118 for carrying in and out of the Si substrate W, and a gate valve G for opening and closing the carry-in and out ports 118.

These support pins 160 raise and lower the Si substrate W when carrying in and out of the processing chamber 111. Specifically, when bringing the Si substrate W into the processing chamber 111, the support pins 160 are raised. And the Si board | substrate W is carried in from the carrying in / out port 118 by the conveyance arm which is not shown in figure, and is mounted in the support pin 160. FIG. Subsequently, the support pin 160 is lowered to load the Si substrate W on the susceptor 112. In addition, when carrying out Si substrate W from the process chamber 111, the support pin 160 is raised and the Si substrate W is lifted up. And the Si board | substrate W is received by the conveyance arm which is not shown in figure, and it carries out from the carrying in / out port 118. FIG.

A control unit (bonding control device) 190 is connected to the film forming apparatus 100, and each part of the film forming apparatus 100 is controlled by the control unit 190. In addition, the control unit 190 includes an operation unit 192 including a keyboard on which an operator inputs a command to manage the film forming apparatus 100, and a display which visualizes and displays the operation state of the film forming apparatus 100. Connected.

In addition, the control unit 190 includes a process necessary for executing a program or a program for realizing various processes (such as a film forming process for the Si substrate W) performed in the film forming apparatus 100 under the control of the control unit 190. The storage unit 194 in which the conditions (recipes) and the like are stored is connected.

In the storage unit 194, for example, data used in a plurality of processing conditions (recipe) is stored. Among the processing conditions, a plurality of parameter values such as control parameters and setting parameters for controlling the units of the film forming apparatus 100 are summarized. Each processing condition has parameter values, such as flow ratio of film-forming gas and reducing gas, the pressure in the process chamber 111, high frequency power, etc., for example.

In addition, these programs and processing conditions may be stored in a hard disk or a semiconductor memory, and set in a predetermined position of the storage unit 194 in a state stored in a storage medium that can be read by a portable computer such as a CD-ROM or a DVD. You may be.

The control unit 190 executes the desired processing in the film forming apparatus 100 by reading the desired program and processing conditions from the storage unit 194 and controlling each unit based on an instruction from the operation unit 192 or the like. In addition, processing conditions can be edited by an operation from the operation unit 192.

(Film forming treatment)

Next, the film forming process performed by the film forming apparatus 100 according to the present embodiment will be described. 2A and 2B are process charts for explaining the film formation process according to the present embodiment. The film-forming apparatus 100 processes the Si substrate 200 which has a film structure as shown, for example in FIG. 2A. The Si substrate 200 forms an interlayer insulating film 204 such as a SiO ₂ film on the Si substrate 202, forms contact holes 205 by etching, and bottoms of the contact holes 205. The Si surface 203 is exposed.

Here, a Ti film is formed on the interlayer insulating film 204 and the contact hole 205 as shown in FIG. 2A, and a TiSi _x film (Ti silicide film) is formed on the Si surface 203 of the bottom of the contact hole 205. Take the case of forming). The film-forming apparatus 100 which concerns on this embodiment carries in the Si film 200 as shown in FIG. 2A, and performs the film-forming process of a Ti film.

First, when the Si substrate 200 is loaded into the processing chamber 111 and loaded on the susceptor 112, the gate valve G is closed, and the susceptor 112 and the shower head are heated by the heaters 115 and 123. 120 is heated to a predetermined temperature. And the inside of the process chamber 111 is pressure-reduced by the exhaust apparatus 152 to predetermined | prescribed vacuum pressure.

In this state, as shown in FIG. 2A, Ti-containing film forming gas such as TiCl ₄ gas and reducing gas such as H ₂ gas are supplied, and a predetermined high frequency is applied to the shower head 120 by the high frequency power source 143. The plasma is supplied by supplying at a predetermined power. As a result, the film forming gas reacts with the reducing gas to form a Ti film on the Si substrate 200. In this manner, as shown in FIG. 2B, a Ti film 206 is formed on the surface of the Si surface 203 and the interlayer insulating film 204, while the surface of the Si surface 203, that is, the contact hole 205. At the bottom, the deposited Ti is silicified (silicided) with Si on the underlying Si surface 203, whereby the TiSi _x film 207 is formed in a self-aligned manner.

However, if in this manner create a plasma to generate a Ti film, by introducing the reducing gas (in this case, H ₂ gas) is excessive, the flow rate of TiCl ₄ gas to the reducing gas is lowered. For this reason, the film-forming reaction of the Ti film is mainly performed by the so-called transfer limited mode in which the reaction proceeds with TiCl ₄ gas supplied therethrough.

In the film forming reaction by the feed rate mode, the film forming reaction occurs near the substrate surface, and since TiCl ₄ gas is consumed, the smaller the hole diameter of the contact hole 205 and the larger the aspect ratio, the more difficult it is to reach the bottom. For this reason, when the hole diameter of the contact hole 205 is small and the aspect ratio is large, as shown in FIG. 3, the film thickness of the bottom part of the contact hole 205 becomes thin compared with the film thickness of the board | substrate surface, and coverage There is a problem that is worsened.

For this reason, the present inventors reduced the H ₂ gas and increased the flow rate of the TiCl ₄ gas to increase the flow rate ratio of the TiCl ₄ gas to the H ₂ gas. As shown in FIG. 4, the Ti film has a contact hole. The film thickness of the bottom of 205 became approximately equal to the film thickness of the substrate surface, thereby improving coverage.

Which, by increasing the flow rate of TiCl ₄ gas, Ti film formation reaction is a reaction by the supply of all the so-called reaction rate determining mode (reaction limited mode) is proceeding side of the film forming reaction of TiCl ₄ gas is thought to be due mainly .

In this case, if the flow rate ratio of the TiCl ₄ gas at the boundary which is switched from the feed rate mode to the reaction rate mode is known, the flow rate of the TiCl ₄ gas is more than the flow rate at the boundary so that the film formation reaction is always caused by the reaction rate mode having good coverage. can do. Therefore, an experiment was performed to determine the flow rate ratio of the TiCl ₄ gas at the boundary of switching from the feed rate mode to the reaction rate mode.

First, the result of having performed the experiment which forms a Ti film on the Si film of the bare substrate which formed the Si film in the whole surface is demonstrated. The bare substrate of the Si film was used to evaluate the film formation reaction on the Si surface 203 of the bottom of the contact hole 205. In this experiment, as the processing gas, the flow rate of H ₂ gas, which is a reducing gas, was fixed at 100 sccm, the flow rate of TiCl ₄ gas was changed between 12 sccm and 80 sccm, and the Ti film was formed to obtain a film formation rate.

5 shows the results of this experiment. FIG. 5 graphically shows the relationship between the flow rate of the TiCl ₄ gas and the deposition rate in the case where the Ti axis is formed on the vertical axis, the TiCl ₄ gas is flown on the horizontal axis, and the Ti film is formed on the Si film. In addition, according to the other treatment conditions according to this experiment, the temperature of the lower electrode 116 is 550 ° C, the temperature of the shower head 120 is 420 ° C, the pressure in the processing chamber 111 is 666 kPa, the TiCl ₄ gas and H ₂ In addition to the gas, 2000 sccm of Ar gas was supplied to the shower head 120, and 450 GHz of high frequency (RF) was supplied at 800 W to generate plasma, and film formation was performed for 30 seconds.

Fig. According to the experimental results shown in Figure 5, the flow rate of TiCl ₄ gas as a reaction rate determining a boundary for switching modes from the feed rate determining mode is found to be 25.3sccm. That is, the region where the flow rate ratio of TiCl ₄ gas is less than or equal to the boundary flow rate 25.3 sccm becomes the supply rate region, which is a reaction region by the supply rate mode. The region of the TiCl ₄ gas having a flow rate of 25.3 sccm or more at the boundary flow rate is a reaction rate region, which is a reaction region by the reaction rate mode. Represents the boundary of a reaction flow rate determining area (the flow rate of the flow rate / H ₂ gas, TiCl ₄ gas) flow rate of TiCl ₄ gas to H ₂ gas, and the 25.3sccm / 100sccm.

In the supply rate region, the deposition rate of the Ti film increases as the flow rate of the TiCl ₄ gas increases, and the deposition rate becomes maximum at the boundary flow rate 25.3 sccm. On the other hand, in the reaction rate region, the deposition rate of the Ti film decreases as the flow rate of TiCl ₄ gas increases. In addition, when the flow rate of the TiCl ₄ gas is increased, the decrease becomes gentle. Accordingly, it can be seen that the flow rate of TiCl ₄ gas as a saturated tendency when in excess.

Next, SiO ₂ film will be described the result of experiment that Ti film is formed on the SiO ₂ film of a bare board is formed on the entire surface. The bare substrate of the SiO ₂ film was used to evaluate the film formation reaction on the interlayer insulating film 204 constituting the substrate surface and the opening surface or the inner wall portion surface of the contact hole 205. Here, the Ti film was formed under the same processing conditions as when the bare substrate of the Si film was used.

6 shows the results of this experiment. FIG. 6 graphically shows the relationship between the flow rate of the TiCl ₄ gas and the deposition rate in the case where the Ti axis is formed on the vertical axis, the TiCl ₄ gas is flown on the horizontal axis, and the Ti film is formed on the SiO ₂ film. In addition, the graph shown in FIG. 5 is superimposed on the graph of FIG.

The dotted line graph in FIG. 6 shows the film forming result of the Ti film on the SiO ₂ film predicted from the film forming result of the Ti film on the Si film. In the deposition of a Ti film by ordinary plasma CVD, it is known that there is a constant change in the deposition rate on the Si film and the SiO ₂ film by the film formation temperature. When the substrate temperature becomes high, on the Si film, a reduction reaction of Ti by H ₂ gas occurs simultaneously with the reduction reaction of Ti by Si of the substrate during the formation of the Ti film. Therefore, the deposition rate on the Si film is increased by the deposition rate on the SiO ₂ film. Greater than

In addition, on the Si film, the reduction reaction of Ti by Si of the substrate and the silicideation reaction of Si and Ti also proceed in parallel, but these reaction rates are determined by the substrate temperature. Become. Therefore, the graph of the deposition rate on the SiO ₂ film can be estimated from a graph of the deposition rate on the Si film. In this experiment, it indicates the predicted value of the deposition rate on the SiO ₂ film to 2/3, and 6, calculated as the actual measurement value of the deposition rate on the Si film as a predictive graph (dotted graph) of the deposition rate on the SiO ₂ film.

According to the experimental results shown in Figure 6, as with the Si layer even in the SiO ₂ film, a flow rate of TiCl ₄ gas as a reaction rate determining a boundary for switching modes from the feed rate determining mode it is found to be 25.3sccm. That is, the region where the flow rate of TiCl ₄ gas is 25.3 sccm or less at the boundary flow rate becomes the supply rate region, which is a reaction region by the supply rate mode. The region where the flow rate of TiCl ₄ gas is 25.3 sccm or more at the boundary flow rate is the reaction rate region, which is the reaction region by the reaction rate mode.

Also on the SiO ₂ film, similarly to the Si film, in the feed rate region, the deposition rate of the Ti film increases as the flow rate of the TiCl ₄ gas increases, and the deposition rate becomes maximum at the boundary flow rate 25.3 sccm. On the other hand, in the reaction rate region, the deposition rate of the Ti film decreases as the flow rate of TiCl ₄ gas increases. In addition, when the flow rate of TiCl ₄ gas is increased, the decrease becomes gentle. According to this, when a flow rate in excess of even TiCl ₄ gas on the SiO ₂ film can be seen that the saturation tendency.

By the way, in a region, that is, saturation tendency that the actual graph, the flow rate is 12 to 40sccm-in area of the TiCl ₄ gas of the deposition rate on the SiO ₂ film as compared to approximately match the predicted graph, the flow rate of TiCl ₄ gas exceeds 40sccm It can be seen that the measured graph is lower than the predicted graph in the region where there is.

This is considered to be due to an increase in the flow rate of the TiCl ₄ gas, and simultaneously an etching reaction of the Ti film and a film forming reaction of the Ti film. According to the experiment of FIG. 6, in the region where the flow rate of TiCl ₄ gas is 45.6 sccm or more at the boundary flow rate, the etching reaction occurs simultaneously with the film forming reaction. It represents the boundary of the flow rate that the etching reaction (rate of flow / H ₂ gas, TiCl ₄ gas) flow rate of TiCl ₄ gas to H ₂ gas, and the 45.6sccm / 100sccm.

For the following, this film formation reaction and an etching reaction in the same, as compared to the reaction and the reaction on the Si film on the SiO ₂ film, will be described in detail. In the Ti film deposition on the SiO ₂ film, TiCl ₄ gas decomposed by the assist of plasma in the gas phase reacts with H ₂ gas or H radical, which is a reducing gas, on the substrate surface to form a Ti film. However, by the film deposition Ti TiCl ₄ gas is decomposed gas generated Cl or Cl radical, as a reaction to occur in the Cl + Ti → TiClx, it is considered that the deposition and etch reactions occur simultaneously.

On the other hand, in the Ti film deposition on the Si film, the decomposed TiClx gas reacts with Si by H ₂ gas, H ₂ gas, reducing gas of H radicals, or thermal energy to form Ti silicide (TiSix). Since the Ti silicide formed by this silicide reaction is firmly bonded to Ti atoms and Si atoms, the Ti silicide cannot react with Cl gas or Cl radicals generated by the decomposition of TiCl ₄ gas, and no etching reaction occurs.

In this way, the Cl gas or the concentration of Cl radical in the flow boundary flow 45.6sccm or more areas of the TiCl ₄ gas, along with the increase in the flow rate of TiCl ₄ gas is TiCl ₄ gas is decomposed in the gas phase occurs as shown in Figure 6 As a result of the increase in the etching reaction, the measured graph of the film forming rate on the SiO ₂ film is considered to be lower than the predicted graph.

In addition, to increase the flow rate of TiCl ₄ gas as described above, compared to the SiO ₂ film On the etching reaction takes place at the same time as the film forming reaction, On the Si film, the etching reaction does not occur, larger even if the flow rate of TiCl ₄ gas, Si It can be seen that the film phase is not damaged by etching.

According to the above, by allowing the flow rate of TiCl ₄ gas to enter the reaction rate region shown in FIG. 6, even in the contact holes 205 having a small hole diameter and a large aspect, the coverage of the Ti film can be significantly improved. Able to know.

That is, in the reaction rate region, since the substrate temperature is a rate rate process of the reaction, even if the TiCl ₄ gas is consumed near the substrate surface and the flow rate of the TiCl ₄ gas in the contact hole 205 is reduced, the film formation rate does not change. Therefore, a Ti film having a better coverage than that in the case of the supply rate region can be formed in the contact hole 205, and a Ti film thicker than that in the case of the supply rate region is formed on the Si surface 203 of the bottom of the contact hole 205. can do.

Further, by allowing the flow rate of TiCl ₄ gas to enter the region with etching reaction in the reaction rate region shown in FIG. 6, a thicker Ti film can be formed on the Si surface 203 of the bottom of the contact hole 205. . That is, in the region with the etching reaction, on the interlayer insulating film 204 such as the SiO ₂ film constituting the substrate surface, on the Si surface 203 of the bottom of the contact hole 205, while the film forming reaction and the etching reaction occur simultaneously. Etching reaction does not occur. For this reason, the Ti film formed in the Si surface 203 of the bottom part of the contact hole 205 can be thickened rather than the Ti film formed in the substrate surface relatively.

By the way, the flow rate of TiCl ₄ gas in the boundary region of the feed rate determining the reaction rate determining region of the Ti film formed in the above reaction can be adjusted by changing the processing conditions other than the flow rate of TiCl ₄ gas. According to this, the reaction rate region of the Ti film forming reaction can be controlled by processing conditions other than the flow rate of the TiCl ₄ gas.

Specifically, since the reaction rate region can be controlled by the flow rate of reducing gas such as H ₂ gas, the pressure in the processing chamber 111, and the RF power of the high frequency power supply 143, the results of the experiment will be described below. Further, the supply boundary of the rate determining area, and the reaction rate determining regions as described in Figure 6 because it is the same as in the case of Ti film is formed on the road, SiO ₂ film if the Ti film is formed on the Si film, the following experiments SiO ₂ A Ti film was formed on the SiO ₂ film by using a bare substrate of the film.

(H ₂ gas flow rate dependence of reaction rate range)

First, a description will be given of a result of an experiment evaluating the H ₂ gas flow rate dependence of the reaction rate determining area. In this experiment, the flow rate of H ₂ gas 30sccm to changing between 100sccm, the flow rate in each of H ₂ gas, as in the case of Figure 6 performs the Ti film formation process on the bare substrate SiO ₂ film, obtain a film-forming rate It was. In addition, other processing conditions are the same as that of the experiment shown in FIG.

7 and 8 show the results of this experiment. Fig. 7 shows the graphs of the film formation rates when the film formation rate is taken along the vertical axis, the TiCl ₄ gas flow rate is taken along the horizontal axis, and the flow rate of the H ₂ gas is 30sccm, 40sccm, 50sccm, 100sccm. 8 shows the flow rate of TiCl ₄ gas at the boundary of the reaction rate region on the vertical axis, and the flow rate of H ₂ gas on the horizontal axis, and summarizes these relationships. The flow rate of the TiCl ₄ gas at the boundary of the reaction rate region in FIG. 8 is the flow rate of the TiCl ₄ gas when the film formation rate is the peak in FIG. 7.

According to the experimental results of FIGS. 7 and 8, with the increase in the flow rate of H ₂ gas, it can be seen that the flow rate of TiCl ₄ gas at the boundary of the reaction rate region also tends to increase relatively. By this, it is possible to control so that, by increasing the flow rate of H ₂ gas, the flow rate of TiCl ₄ gas in the perimeter of the reaction zone increases the rate limiting.

(Pressure dependence in the process chamber in the reaction rate range)

Next, the result of having performed the experiment which evaluates the pressure dependence in the process chamber of a reaction rate area | region is demonstrated. In this experiment, the pressure in the processing chamber 111 was changed to 400 kPa, 500 kPa, and 666 kPa when the RF power was 1000 W, and the flow rate of the TiCl ₄ gas was changed between 12 sccm and 80 sccm at respective pressures. Similarly, subjected to film forming the Ti film on the bare substrate SiO ₂ film was determined the film-forming rate. Moreover, when RF power was 800W, the pressure in the process chamber 111 was changed to 500 kPa and 666 kPa, and the film-forming process similar to the above was performed, and the film-forming rate was calculated | required. In addition, other processing conditions are the same as that of the experiment shown in FIG.

9 and 10 show the results of this experiment. 9 shows the film formation rate on the vertical axis, the flow rate of TiCl ₄ gas on the horizontal axis, and superimposes the graphs of the film formation rate on each film forming process. Fig. 10 shows the flow rate of TiCl ₄ gas at the boundary of the reaction rate region on the vertical axis, and the pressure in the processing chamber on the horizontal axis, to summarize these relationships. The flow rate of the TiCl ₄ gas at the boundary of the reaction rate region in FIG. 10 is the flow rate of the TiCl ₄ gas when the film formation rate is the peak in FIG. 9.

According to the experimental results of FIGS. 9 and 10, it can be seen that with the increase in the pressure in the process chamber, the flow rate of TiCl ₄ gas at the boundary of the reaction rate region also tends to increase slightly. By this, it is possible to control also, so that the flow rate of TiCl ₄ gas in the boundary between the reaction rate determining area increased by increasing the chamber pressure.

(RF power dependence of response rate range)

Next, the result of experiment which evaluates the RF power dependency of the reaction rate area | region is demonstrated.

In this experiment, the flow rate of the H ₂ gas was fixed at 100 sccm, and the RF power of the high frequency power supply 143 was changed to 500 W, 800 W, 1000 W, and 1200 W so that the Ti film was deposited on the SiO ₂ film of the bare substrate as in the case of FIG. The film forming process was performed to obtain a film forming rate. In addition, the H ₂ gas was fixed at 30 sccm, the RF power was changed to 500 W and 800 W, and the Ti film was formed on the SiO ₂ film of the bare substrate in the same manner as described above to obtain a film formation rate. In addition, other processing conditions are the same as that of the experiment shown in FIG.

11 and 12 show the results of this experiment. 11 shows the film formation rate on the vertical axis, the flow rate of TiCl ₄ gas on the horizontal axis, and superimposes the graphs of the film formation rate on each film forming process. Fig. 12 shows the flow rate of TiCl ₄ gas at the boundary of the reaction rate region on the vertical axis, RF power on the horizontal axis, and summarizes these relationships. The flow rate of the TiCl ₄ gas at the boundary of the reaction rate region in FIG. 12 is the flow rate of the TiCl ₄ gas when the film formation rate is the peak in FIG. 11.

According to the experimental results of FIGS. 11 and 12, not only when the flow rate of the H ₂ gas is large (100 sccm), but also when the flow rate of the H ₂ gas is small (30 sccm), with the increase of the RF power, It can be seen that the flow rate of TiCl ₄ gas at the boundary also tends to increase relatively large. By this, it is possible to control so as to also increase the flow rate of TiCl ₄ gas in the boundary between the reaction rate determining area by increasing the RF power.

In this way, the reaction rate region of the Ti film forming reaction can be controlled by processing conditions other than the flow rate of the TiCl ₄ gas, for example, the flow rate of the H ₂ gas, the pressure in the processing chamber, and the RF power. Moreover, the area | region with the etching reaction shown in FIG. 6 can also be controlled by these process conditions.

Therefore, in the film forming process of the Ti film according to the present embodiment, the processing conditions other than the flow rate of the TiCl ₄ gas are changed so that the flow rate of the TiCl ₄ gas to be applied to the film forming process enters the reaction rate region or the region with the etching reaction. This controls the reaction rate region or the region with the etching reaction. Thereby, since a film-forming process can always be performed in a reaction rate area | region, even if the contact hole with a large aspect ratio is formed, a Ti film with a good coverage can always be formed.

By the way, in order to perform film-forming process in a reaction zone or area of the rate determining that the etching reaction, and is also simply thought that increasing the flow rate of TiCl ₄ gas. By the way, the flow rate of TiCl ₄ gas is too large, the film forming the Ti film resistivity was found to have a problem that it rises. For this reason, it is necessary to increase the flow rate of TiCl ₄ gas in the range of the specific resistance does not increase.

Here, FIG. 13 shows the results of experiments on the relationship between the flow rate of the TiCl ₄ gas and the specific resistance of the formed Ti film. In this experiment, the pressure in the processing chamber was 500 kPa and the RF power was 1000 W. The other processing conditions were the same as those in FIG. 5, and the Ti film was formed on the Si film of the bare substrate, thereby forming Ti. The resistivity of the membrane was measured.

FIG. 13 graphically shows the relationship between the flow rate of TiCl ₄ gas and the specific resistance of the formed Ti film by taking the specific resistance on the vertical axis and the flow rate of TiCl ₄ gas on the horizontal axis. According to this, where the flow rate of the TiCl ₄ gas exceeds 55 sccm, the specific resistance starts to rise.

By the above experimental results on the basis, a description will be given, with Ti in the film deposition process, refer to the drawings for a practical range of the flow rate of TiCl ₄ gas most appropriate. FIG. 14 shows a graph of a film formation rate (FIG. 11) and a graph of specific resistance (FIG. 13) at which the flow rate of TiCl ₄ gas at the boundary of the reaction rate region in the above-described experiment was 13 sccm, which was the smallest.

According to this, when the practical range of the flow rate of TiCl ₄ gas is expressed by the flow rate ratio (flow rate of TiCl ₄ gas / flow rate of H ₂ gas), the Ti film having good coverage can be formed by setting it in the range of 13sccm / 100sccm to 55sccm / 100sccm. Can be. In addition, when the bottom of the contact hole 205 is desired to be thickened, it is preferable to set it in the range of 45.6 sccm / 100 sccm to 55 sccm / 100 sccm which is an area with etching reaction, and when it is not desired to proceed the etching reaction, it is 13 sccm / 100 sccm It is preferable to set in the range of 45.6sccm / 100sccm.

Next, Fig. 15 and Fig. 16 show experimental results when a Ti film is actually formed in a contact hole. 15 is in the case shown in Fig. 6 when the film formation in the feed rate determining area, the flow rate of TiCl ₄ gas to 12sccm, and to the flow rate of TiCl ₄ gas as 40sccm and the reaction rate determining area, also a film-forming in the area of that etch It is a figure which shows the whole contact hole about a case. FIG. 16 is an enlarged view of the top, side, and bottom of the contact hole shown in FIG. 15. Table 1 below summarizes the film thickness and coverage of each part shown in FIGS. 15 and 16.

According to Table 1, in the case of the reaction rate region shown in FIG. 6 (here is also the region with etching), the thickness of the bottom of the contact hole is significantly improved from 69% to 207.3% compared to the case of the supply rate region. I can see that there is.

In addition, in the case of the supply rate region, the film thickness on the sidewall of the contact hole also decreases from the top to the bottom. On the other hand, in the case of the reaction rate region, the film thickness is substantially constant from the top to the bottom, and the coverage is improved as compared with the case of the supply rate region. According to this, it turns out that it can form into a film at a film formation rate substantially equal from the upper part to the lower part in a contact hole.

In the case of the reaction rate region, the film thickness of the substrate surface is also thinner at 12.4 nm to 5.1 nm than in the case of the supply rate region. According to this, it turns out that the etching reaction in the surface of a board | substrate is progressing. By reducing the thickness of the substrate surface, the coverage to the contact hole sidewall can be greatly improved.

Thereby, the barrier film (for example, TiN film) and the contact plug film (for example, tungsten film) performed after this Ti film film-forming process can be formed in good coverage. In addition, since a Ti film having a sufficient thickness is formed on the sidewalls of the contact holes, it is also possible to form a contact plug film directly on the Ti film without forming a barrier film, thereby improving the throughput and reducing the manufacturing cost. .

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It is apparent to those skilled in the art that various modifications or modifications can be made within the scope described in the claims, and that they naturally belong to the technical scope of the present invention.

[Industrial Availability]

INDUSTRIAL APPLICABILITY The present invention is applicable to a film forming method and a film forming apparatus for forming a predetermined film on a substrate to be processed, such as a semiconductor wafer, an FPD substrate, a liquid crystal substrate, or a solar cell substrate.

100: Deposition device
111: treatment chamber
111A: Ceiling Wall
111B: Bottom Wall
111C: sidewall
112: susceptor
113: support member
114: guide ring
115: heater
116: lower electrode
117: circular hole
118: carrying in and out
119: insulation member
120: shower head
121: base member
122: shower plate
123: heater
124: discharge hole
125: gas diffusion space
126 gas introduction port
130: gas supply means
131 to 133: each gas supply source
131C to 133C: Mass Flow Controller
131V to 133V: Valve
131L to 133L: each gas supply line
137 gas mixing unit
138: mixed gas supply line
140, 141: heater power
142: matcher
143: high frequency power
150: exhaust chamber
151: exhaust pipe
152: exhaust device
160: support pin
161: support plate
162: drive mechanism
190:
192: control panel
194 memory
200, W: Si substrate
202 Si substrate
203: Si surface
204: interlayer insulating film
205: contact hole

Claims (9)

It is a method of forming a titanium film on the to-be-processed substrate by which the contact hole was formed by supplying the process gas containing a titanium containing film-forming gas and a reducing gas into a process chamber,
High frequency power applied to the electrode to generate the flow rate of the reducing gas, the pressure in the processing chamber, and the plasma so that the flow rate of the film forming gas to be applied to the film forming process of the titanium film enters the reaction rate region of the film forming process. By changing any one of the, to control the reaction rate region,
The film forming method, wherein the flow rate of the film forming gas, which is the boundary of the reaction rate region of the film forming process, is increased by increasing one of the reducing gas flow rate, the pressure in the processing chamber, and the high frequency power. delete delete delete The film forming method according to claim 1, wherein the flow rate of the film forming gas is set in a range such that the flow rate ratio of the film forming gas to the reducing gas flow rate is 13 sccm / 100 sccm or more and 55 sccm / 100 sccm or less. The film forming method according to claim 5, wherein the flow rate of the film forming gas is set in a range such that the flow rate ratio of the film forming gas to the reducing gas flow rate is 13 sccm / 100 sccm or more and 45.6 sccm / 100 sccm or less. The film forming method according to claim 5, wherein the flow rate of the film forming gas is set in a range such that a flow rate ratio of the film forming gas to the reducing gas flow rate is 45.6 sccm / 100 sccm or more and 55 sccm / 100 sccm or less. 2. The film forming process according to claim 1, wherein the film forming process is determined by a process condition of the film forming process including a flow rate of the film forming gas, a flow rate of the reducing gas, a pressure in the processing chamber, and a high frequency power applied to an electrode to generate the plasma. A titanium film is formed on the substrate to be treated by reacting the film forming gas with a reducing gas in a reaction rate region of. It is a film-forming apparatus which forms a titanium film on the to-be-processed substrate in which the contact hole was formed by supplying the process gas containing a titanium containing film-forming gas and a reducing gas into a process chamber,
A susceptor for loading the substrate to be processed;
A shower head for supplying the processing gas into the processing chamber;
A high frequency power supply for supplying a high frequency for generating plasma between the susceptor and the shower head with a predetermined power;
An exhaust device for exhausting the inside of the processing chamber and reducing the pressure to a predetermined pressure;
The reaction is performed by changing one of the flow rate of the reducing gas, the pressure in the processing chamber, and the high frequency power so that the flow rate of the film forming gas to be applied to the film forming process of the titanium film enters the reaction rate region of the film forming process. A control unit for controlling the speed range region,
The control unit controls to increase the flow rate of the film forming gas, which is a boundary of the reaction rate region of the film forming process, by increasing any one of the reducing gas flow rate, the pressure in the processing chamber, and the high frequency power. Device.

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