WO2016002591A1

WO2016002591A1 - Film formation device

Info

Publication number: WO2016002591A1
Application number: PCT/JP2015/068067
Authority: WO
Inventors: 雅人森嶋
Original assignee: 東京エレクトロン株式会社
Priority date: 2014-07-03
Filing date: 2015-06-23
Publication date: 2016-01-07

Abstract

　In the present invention, a film formation device is provided with a processing container, a platform, a first gas supply part, a second gas supply part, and a high-frequency power source. The platform is provided inside the processing container, a substrate being mounted on the platform. The first gas supply part supplies a reaction gas containing H2/N2 or NH3 into a strong plasma generation space formed inside the processing container. The second gas supply part supplies a silicon compound gas that forms a silicon nitride film on the substrate upon reacting with an active species of the reaction gas in a weak plasma generation space for generating plasma having weaker emission intensity than the plasma formed in the strong plasma generation space that is formed inside the processing container. The high-frequency power source supplies high-frequency power for converting the reaction gas and the silicon compound gas into plasma.

Description

Deposition equipment

Various aspects and embodiments of the present invention relate to a film forming apparatus.

Conventionally, a plasma CVD (Chemical Vapor Deposition) method is known as a method for forming a silicon nitride film on a substrate. In a film forming apparatus that employs a plasma CVD method, for example, active species generated by converting a processing gas containing SiH 4 (monosilane) gas or nitrogen (N 2) gas into plasma using high-frequency power is reacted, and a glass substrate is used. A silicon nitride film is formed on the substrate.

JP 2013-175780 A

However, in a film forming apparatus employing the plasma CVD method, when forming a silicon nitride film, the film forming speed is slowed down in a shape portion where ions are difficult to enter, such as the bottom of a trench groove. There is a problem that the coverage of the silicon nitride film to be formed is lowered. Therefore, it has been desired to improve the coverage of the silicon nitride film formed on the substrate.

The film forming apparatus according to one aspect of the present invention includes a processing container, a mounting table, a first gas supply unit, a second gas supply unit, and a high-frequency power source. The mounting table is a mounting table provided in the processing container for mounting the substrate. The first gas supply unit supplies a reactive gas containing H2 / N2 or NH3 to the strong plasma generation space formed in the processing container. The second gas supply unit reacts with the active species of the reactive gas in the weak plasma generation space that generates plasma having a light emission intensity lower than that of the plasma formed in the processing vessel and formed in the strong plasma generation space. Then, a silicon compound gas for forming a silicon nitride film on the substrate is supplied. The high frequency power supply supplies high frequency power for converting the reaction gas and the silicon compound gas into plasma.

According to various aspects and embodiments of the present invention, a film forming apparatus capable of improving the coverage of a silicon nitride film formed on a substrate is realized.

FIG. 1 is a longitudinal side view of a film forming apparatus according to the first embodiment. FIG. 2 is a perspective view showing an external configuration of the film forming apparatus. FIG. 3 is a partially broken perspective view showing a configuration of an electrode portion provided in the film forming apparatus. FIG. 4 is a plan view of the electrode portion. FIG. 5 is an explanatory diagram illustrating a configuration of a power supply system that supplies high-frequency power to the electrode unit. FIG. 6 is an explanatory view showing the operation of the film forming apparatus. FIG. 7 is an explanatory diagram of a film forming apparatus according to the second embodiment. FIG. 8 is a first explanatory view of a film forming apparatus according to the third embodiment. FIG. 9 is a second explanatory view of a film forming apparatus according to the third embodiment. FIG. 10 is a plan view showing the configuration of the electrode section of the film forming apparatus according to the fourth embodiment. FIG. 11 is a plan view showing a configuration of an electrode portion of a film forming apparatus according to the fifth embodiment. FIG. 12 is a plan view showing the arrangement of electrode portions of the film forming apparatus according to the sixth embodiment. FIG. 13 is an enlarged view of the bottom surface of the electrode portion according to the sixth embodiment. FIG. 14 is a partially broken perspective view of the electrode portion according to the sixth embodiment. FIG. 15 is an explanatory diagram of a power supply system of the film forming apparatus according to the sixth embodiment. FIG. 16 is a plan view showing a modification of the electrode portion according to the sixth embodiment. FIG. 17 is a plan view showing a second modification of the electrode portion according to the sixth embodiment. FIG. 18 is a plan view (No. 1) showing a third modification of the electrode portion according to the sixth embodiment. FIG. 19 is a plan view (No. 2) showing a third modification of the electrode portion according to the sixth embodiment. FIG. 20 is a plan view showing the configuration of the electrode portion when the wafer is rotated. FIG. 21 is an explanatory diagram showing the result of simulating the electron density distribution of the film forming apparatus according to the example. FIG. 22 is a waveform diagram of high-frequency power supplied to the film forming apparatus according to the example. FIG. 23 is a diagram showing experimental results in Comparative Example 1 and Example 3. FIG. 24 is a diagram showing experimental results in Comparative Example 1 and Example 3. FIG. 25 is a diagram showing experimental results in Comparative Example 1 and Example 3. FIG. 26 is a diagram showing the concentration of each atom in the SiN film formed on the substrate after the experiment of Comparative Example 1. FIG. 27 is a diagram showing the concentration of each atom in the SiN film formed on the substrate after the experiment of Example 3. In FIG. FIG. 28 is an enlarged trace view of the cross section of the substrate on which the SiN film is formed by the film forming apparatus shown in FIG. 1 when the temperature of the substrate is 70 ° C. FIG. 29 is a diagram showing step coverage of a substrate on which a SiN film is formed by the film forming apparatus shown in FIG. 1 when the temperature of the substrate is 70 ° C., 150 ° C., or 300 ° C.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

In one embodiment, a film forming apparatus according to this embodiment is provided in a processing container, a mounting table provided in the processing container for mounting a substrate, and a strong plasma generation space formed in the processing container. , A first gas supply unit for supplying a reaction gas containing H2 / N2 or NH3, and weak plasma generation for generating plasma having a light emission intensity lower than that of the plasma formed in the processing vessel and formed in the strong plasma generation space A second gas supply unit for supplying a silicon compound gas for forming a silicon nitride film on the substrate by reacting with reactive species of the reaction gas in the space; and for converting the reaction gas and the silicon compound gas into plasma A high frequency power source for supplying high frequency power.

Further, in one embodiment, the film forming apparatus according to the present embodiment is spaced apart from each other in a vertical orientation in order to form a strong plasma generation space above the substrate placed on the mounting table. And a plurality of electrode portions that form a weak plasma generation space in the gap between the lower end portion and the substrate, and the high-frequency power source is adjacent to the strong plasma generation space among the plurality of electrode portions. By supplying high-frequency power with different phases to a pair of matching electrode parts, the reaction gas and the silicon compound gas are turned into plasma.

In one embodiment, the film forming apparatus according to this embodiment has a power density of high-frequency power supplied from a high-frequency power source of 1 W / cm 2 or more and 3 W / cm 2 or less.

In the film forming apparatus according to this embodiment, in one embodiment, the partial pressure of the silicon compound gas is 1 Pa or more and 4 Pa or less.

Further, in the film forming apparatus according to the present embodiment, in one embodiment, the temperature of the substrate is 70 ° C. or higher and 300 ° C. or lower.

As this embodiment, a capacitively coupled plasma is formed between adjacent electrode portions, and H2 / N2 or NH3 (reactive gas) is activated to react with SiH4 (silicon compound gas) to form silicon as a thin film. An apparatus configuration of a film forming apparatus for forming a nitride film (SiN film) will be described with reference to FIGS.

As shown in FIG. 1, the film forming apparatus 1 reacts with a mounting table 2 on which a substrate S to be formed is mounted and a surface of the substrate S on the mounting table 2 in a processing container 10 that is a vacuum container. A plurality of electrode portions 41 for forming a strong plasma generation space 101 for supplying an active species of gas and forming a weak plasma generation space 102 for advancing the reaction between the active species and the silicon compound gas; The arrangement is arranged. Here, the reactive gas is, for example, a reactive gas containing H2 / N2 or NH3, and the silicon compound gas is, for example, SiH4 or SiH2Cl2. As shown in FIGS. 1 and 2, the processing container 10 is configured as a flat and metal container that can be sealed, and has a size that can store a large glass substrate S of, for example, 1100 mm × 1400 mm or more.

In the figure, 11 is a loading / unloading port through which the short side of the substrate S provided in the processing vessel 10 can pass, and 12 is a gate valve for opening and closing the loading / unloading port 11. In addition, an exhaust pipe 13 for evacuating the inside of the processing container 10 is provided on the side wall surface of the processing container 10, and the processing container is operated by an action of a vacuum pump (not shown) provided downstream of the exhaust pipe 13. The space in 10 can be adjusted to 100 Pa to 400 Pa, for example. Hereinafter, the short side direction of the substrate S installed in the processing container 10 will be described as the vertical direction, and the long side direction of the substrate S will be described as the horizontal direction.

The mounting table 2 made of a dielectric or the like is disposed on the floor surface in the processing container 10, and the substrate S described above is mounted on the mounting table 2 to form a SiN film. The transfer of the substrate S between an external substrate transfer mechanism (not shown) that carries the substrate S in and out and the mounting table 2 is performed by using a lift pin 22 configured to be lifted and lowered by a lift mechanism 25 via a lift plate 24. Done with. In FIG. 1, reference numeral 23 denotes a bellows provided so as to surround the elevating pins 22 in order to keep the inside of the processing vessel 10 in a vacuum atmosphere.

A temperature adjusting unit 21 made of, for example, a resistance heating element is embedded in the mounting table 2, and the temperature adjusting unit 21 generates heat by electric power supplied from a power supply unit (not shown) and passes through the upper surface of the mounting table 2. Thus, the substrate S can be adjusted to a temperature of 70 ° C. to 300 ° C., for example. Here, the temperature adjusting unit 21 is not limited to the one that heats the substrate S, and may employ, for example, a Peltier element that cools the substrate S and adjusts it to a predetermined temperature according to the process conditions.

The film forming apparatus 1 according to the present embodiment supplies active species SiH3 necessary for the growth of the SiN film at a high concentration to a region near the surface of the substrate S, while active species other than SiH3 such as Si, SiH, and SiH2. In order to suppress the supply to the surface of the substrate S with respect to substances that cause deterioration in the quality and coverage of the SiN film, such as higher-order silane and its fine particles, the following effects can be obtained. .

(1) A space to which H2 / N2 or NH3 (reactive gas) is supplied is configured as a strong plasma generation space 101 to obtain N radicals and H radicals which are active species. On the other hand, the space on the upper surface of the substrate S where H radicals and SiH 4 (silicon compound gas) react with each other is configured as a weak plasma generation space 102 that generates plasma having a light emission intensity lower than that of the strong plasma generation space 101. Thus, SiH3 is supplied to the surface of the substrate S at a high concentration while suppressing generation of unnecessary active species.

(2) By quickly exhausting a mixed gas of excess H radicals and SiH4 from the surface of the substrate S, generation of unnecessary active species due to excessive progress of radical reaction between H radicals and SiH4 is suppressed. To do.
Hereinafter, the configuration of the electrode unit 41 and the like provided in the film forming apparatus 1 in order to obtain the above-described operation will be described.

As shown in FIGS. 1, 3, and 6, the film forming apparatus 1 is spaced apart from each other in the lateral direction so as to divide the space in the processing container 10 above the substrate S placed on the mounting table 2. A plurality of plate-like electrode portions 41 arranged with a gap therebetween are arranged. Each electrode part 41 is comprised as an elongate plate-shaped metal member, for example, and is arrange | positioned so that it may extend below from the ceiling part (after-mentioned insulating member 31) of the processing container 10 with a vertical orientation.

The electrode portions 41 are arranged at equal intervals in the direction of the long side (lateral direction) of the substrate S, and thereby, between the two electrode portions 41 adjacent to each other, the short side direction ( An elongated space (strong plasma generation space 101) extending in the vertical direction is formed. Each electrode portion 41 is fixed to the ceiling portion of the processing container 10 via an insulating member 31. Plasma is generated in the strong plasma generation space 101 by supplying high-frequency power to each electrode unit 41 from first and second power supply units 61 and 62 (see FIG. 5) described later. The detailed configuration of the power supply system will be described later.

As shown in FIG. 6, the distance w between the electrode portions 41 arranged adjacent to each other with the strong plasma generation space 101 interposed therebetween is, for example, in the range of 2 mm or more and 20 mm or less, more preferably 4 mm or more and 10 mm or less. It has been adjusted. When the distance between the electrode portions 41 is less than 2 mm, plasma is not generated in the strong plasma generation space 101, while when the distance is greater than 20 mm, the plasma generated in the processing vessel 10 is weakened to generate N radicals. The amount decreases, causing a decrease in film formation rate.

In the electrode part 41, the distance h between the lower surface of the electrode part 41 and the surface of the substrate S is adjusted to 5 mm or more and 100 mm or less, more preferably 7 mm or more and 30 mm or less. When the distance between the electrode part 41 and the substrate S is larger than 100 mm, the plasma generated in the weak plasma generation space 102 becomes too weak and the film speed is reduced. When the distance between the electrode portion 41 and the substrate S is smaller than 5 mm, the intensity of plasma generated in the weak plasma generation space 102 approaches the intensity of plasma generated in the strong plasma generation space 101, and SiH4 Decomposition of the metal proceeds excessively, which causes a decrease in the quality of the SiN film and a decrease in the coverage.

Next, a mechanism for supplying a reactive gas to the strong plasma generating space 101 and the weak plasma generating space 102 and exhausting the reacted gas will be described. As shown in FIGS. 1 and 3, a space is formed between the upper surface side of the insulating member 31 that fixes the electrode portion 41 and the processing container 10, and strong plasma is generated in this space. A supply path 32 for supplying H2 / N2 or NH3 to the space 101 is provided.

The supply path 32 is disposed on the upper side of each strong plasma generation space 101. 3, 4, and 6, the supply path 32 is connected to the supply path 32 along the direction in which the electrode portion 41 extends (that is, the Y direction that is parallel to the substrate S), and the vertical direction ( That is, H2 / N2 or NH3 is supplied into the strong plasma generation space 101 via a branch path 323 extending in the Z direction (perpendicular to the substrate S) and a supply hole 321 drilled in the insulating member 31. Can do.

As shown in FIGS. 1 to 3, the plurality of supply paths 32 are connected to a common supply line 511, and receive H2 / N2 or NH3 from a supply unit 51 including a cylinder and a flow rate adjusting valve. Thus, a predetermined amount of H2 / N2 or NH3 can be supplied to each strong plasma generation space 101. The supply path 32, the supply line 511, the supply part 51, etc. are equivalent to the 1st gas supply part of this example.

As shown in FIG. 1 and FIG. 3, the supply path 42 for supplying SiH 4 to the weak plasma generation space 102 and the reaction gas supplied to the weak plasma generation space 102 are discharged inside each electrode portion 41. An exhaust passage 43 is formed.

As shown by the broken line in FIG. 3, the supply path 42 in this example is provided in a region on the lower side of the electrode portion 41 and in a region close to both side wall surfaces of the electrode portion 41 (two in total). It is formed along the direction in which the electrode part 41 extends (that is, the Y direction that is parallel to the substrate S).

A plurality of branch paths 423 extend downward from each supply path 42 at intervals, and are formed on the lower surface of the electrode portion 41 as shown in FIGS. 3, 4, and 6. SiH 4 can be supplied toward the weak plasma generation space 102 from the supply holes 421 arranged in two rows along the both side wall surfaces before and after the portion 41. Here, the supply hole 421 is not limited to the case where the supply hole 421 is provided on the bottom surface of the electrode part 41. Alternatively, SiH 4 may be supplied to the lower side of the strong plasma generation space 101.

As shown in FIGS. 1 to 3, the supply path 42 formed in each electrode part 41 is connected to a common supply line 521, and the supply part 52 including a cylinder and a flow rate adjusting valve is connected to the SiH4. And a preset amount of SiH4 can be supplied. The supply path 42, the supply line 521, the supply unit 52, and the like correspond to the second gas supply unit of this example.

Moreover, the partial pressure of the silicon compound gas such as SiH 4 supplied from the supply path 42, the supply line 521, and the supply unit 52 is preferably 1 Pa or more and 4 Pa or less, more preferably 2.5 Pa or more and 4 Pa or less. . When the partial pressure of the silicon compound gas supplied from the supply path 42, the supply line 521, and the supply unit 52 is less than 1 Pa, the plasma generated in the weak plasma generation space 102 is weakened. As a result, the SiN film The film formation rate decreases. On the other hand, when the partial pressure of the silicon compound gas supplied from the supply path 42, the supply line 521, and the supply unit 52 is larger than 4 Pa, the active species of the silicon compound gas are polymerized, and the fine particles obtained by the polymerization are obtained. Incorporated into the SiN film, as a result, the quality of the SiN film is deteriorated and the coverage is lowered.

Further, in each electrode portion 41, two exhaust passages 43 are provided in an upper region inside the supply passage 42 described above, and the direction in which the electrode portion 41 extends in parallel with the supply passage 42 (that is, on the substrate S). (Y direction which is a parallel direction). Also from these two exhaust passages 43, a plurality of branch passages 433 extend downward at intervals from each other, and two of the branch passages 433 at the same position of the two exhaust passages are in the middle. And are connected to an exhaust hole 431 formed in the lower surface of the electrode portion 41. As shown in FIG. 4, the exhaust holes 431 are arranged in a row at the center of the lower surface of the electrode portion 41 so as to be sandwiched between the rows of supply holes 421 arranged in two rows.

As shown in FIGS. 1 to 3, the exhaust passage 43 formed in each electrode portion 41 is connected to an external exhaust means 53 constituted by a vacuum pump or the like via a common exhaust line 531. The reactive gas in the weak plasma generation space 102 can be discharged to the outside. The exhaust path 43, the exhaust line 531, the exhaust means 53, and the like correspond to the exhaust part of this example.

Next, a power supply system that supplies high-frequency power to each electrode portion 41 in the processing container 10 will be described. As shown in FIG. 5, the electrode part 41 on one side (indicated as the electrode part 41a in FIG. 5) across the strong plasma generation space 101 is, for example, 13.56 MHz, 2500 W / piece (1 The first power supply unit 61 (first high frequency power supply unit) for applying the high frequency power of the electrode portion) is connected. On the other hand, the other electrode part 41 (denoted as electrode part 41b in FIG. 5) across the strong plasma generation space 101 has a phase of 180 ° with respect to the high-frequency power supplied from the first power supply part 61. It is connected to the second power supply unit 62 (second high-frequency power supply unit) that applies the high-frequency power of, for example, 13.56 MHz and 2500 W / line which is delayed (phase is inverted). In the figure, reference numerals 612 and 622 denote matching units for matching high-frequency power supplied from the

power supply units

61 and 62, respectively.

In the example shown in FIG. 5, the first and second

power supply units

61 and 62 are configured as externally synchronized power sources capable of outputting high frequency power synchronized with a frequency signal input from the outside. When the first and second

power supply units

61 and 62 are connected to the common frequency signal generator 63, the first signal line 611 that connects the first power supply unit 61 and the frequency signal generator 63 is used. The second signal line 621 connecting the second power source 62 and the frequency signal generator 63 is longer than the second power line 62.

Thus, the frequency signal output from the frequency signal generator 63 is input to the second power supply unit 62 with a delay from the timing input to the first power supply unit 61, and the phase of the high frequency power is utilized using this delay. Is adjusted. It has been experimentally confirmed that the phase of the high-frequency power output from each of the

power supply units

61 and 62 can be adjusted by this method, as shown in the embodiments described later.

However, the method of adjusting the phase difference between the first power supply unit 61 and the second power supply unit 62 is not limited to a specific method, and other methods may be adopted. For example, a forced balun circuit is connected to the output of one high frequency power supply unit, one output of the forced balun circuit is applied to the electrode unit 41a, and another output whose phase is inverted from the one output is applied to the electrode unit 41b. It is good also as composition to do.

The 1st power supply part 61 and the 2nd power supply part 62 supply the high frequency electric power which the phase reversed to the electrode part 41 (41a, 41b) which pinches | interposes the strong plasma production space 101 among several electrode parts 41 As a result, H2 / N2 or NH3 supplied to the gap between the electrode parts 41 and SiH4 supplied to the gap between the lower end part of the electrode part 41 and the substrate S are turned into plasma. As a result, a strong plasma generation space 101 is formed in the gap between the electrode portions 41 to generate H radicals by generating H2 / N2 or NH3 into plasma. Further, plasma caused by the high frequency power applied to the electrode unit 41 is also formed between each electrode unit 41 and the substrate S placed on the lower side thereof. The 1st power supply part 61 and the 2nd power supply part 62 are examples of the high frequency power supply which supplies the high frequency electric power for plasma-izing a reaction gas and silicon compound gas.

Here, unlike the strong plasma generation space 101 in which the phases are reversed and a high-frequency power is applied to the

electrode portions

41a and 41b in a so-called push-pull state, the substrate S placed on the placement table 2 is: It is in an electrically floating state. For this reason, plasma weaker than the plasma formed in the strong plasma generation space 101 is generated in the space (weak plasma generation space 102) between the electrode portions 41 and the substrate S.

Here, the relative intensity ratio of the plasma formed in the strong plasma generation space 101 and the weak plasma generation space 102, for example, the ratio of the electron temperature and the electron density in the plasma, is determined as follows. Can be grasped by the ratio of the emission intensity when the image is taken. When the ratio of the emission intensity of the weak plasma generation space 102 to the emission intensity of the strong plasma generation space 101 is less than 1, a weaker plasma than the plasma generated in the strong plasma generation space 101 is generated in the weak plasma generation space 102. It can be said that.

The power density of the high frequency power supplied from the first power supply unit 61 and the second power supply unit 62 is preferably 1 W / cm 2 or more and 3 W / cm 2 or less, more preferably 1.5 W / cm 2 or more. 2 W / cm 2 or less. Here, the power density of the high frequency power is a value obtained by dividing the total input power by the surface area of all the electrodes. When the power density of the high frequency power supplied from the first power supply unit 61 and the second power supply unit 62 is less than 1 W / cm 2, the plasma generated in the weak plasma generation space 102 is weakened. The deposition rate of the SiN film decreases. On the other hand, when the power density of the high frequency power supplied from the first power supply unit 61 and the second power supply unit 62 is larger than 3 W / cm 2, excessive H radicals are generated and the decomposition of SiH 4 proceeds excessively. As a result, the film quality of the SiN film is lowered and the coverage is lowered.

The film forming apparatus 1 having the above-described configuration is connected to the control unit 7 as shown in FIGS. The control unit 7 includes, for example, a computer including a CPU and a storage unit (not shown). The operation of the film forming apparatus 1, that is, the substrate S is loaded into the processing container 10 and placed on the mounting table 2. A program in which a group of steps (commands) for control and the like related to operations from when a SiN film having a predetermined film thickness is formed on the substrate S to be carried out is recorded. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

An example of the action of the film forming apparatus 1 having the above-described configuration will be described. First, when the substrate S is transported by an external substrate transport mechanism, the film forming apparatus 1 opens the gate valve 12 of the loading / unloading port 11 and protrudes the lift pins 22 from the mounting table 2 to remove the substrate S from the substrate transport mechanism. receive.

When the delivery of the substrate S is completed, the substrate transport mechanism is retracted out of the processing container 10 to close the gate valve 12 and the lifting pins 22 are lowered to place the substrate S on the mounting table 2. In parallel with this operation, the processing chamber 10 is evacuated to adjust the processing chamber 10 to, for example, 200 Pa in the range of 100 Pa to 400 Pa, and the temperature adjusting unit 21 brings the substrate S to, for example, 70 ° C. to 300 ° C. Adjust the temperature as follows.

When the pressure adjustment in the processing container 10 and the temperature adjustment of the substrate S are finished, H2 / N2 is supplied to the strong plasma generation space 101 from the supply unit 51 via the supply line 511 and the supply path 32, and the first and second. The high frequency power is applied from the

power supply units

61 and 62 to the electrode units 41 to turn H2 / N2 into plasma. On the other hand, SiH 4 is supplied from the supply unit 52 toward the weak plasma generation space 102 via the supply line 521 and the supply path 42. Here, the ratio of the flow rate of H2 to the flow rate of N2 is preferably H2: N2 = 1: 1 to 2: 1. For example, the flow rate of H2 / N2 / SiH4 is H2 / N2 / SiH4 = 1000/500/20 sccm.

As a result, as schematically shown in FIG. 6, a downward flow is formed in the strong plasma generation space 101 in which H2 / N2 supplied from the supply path 32 flows downward. The H2 / N2 collides with the electrons supplied from the electrode portion 41 to be turned into plasma, thereby forming active species. For example, N radicals are generated as active species from nitrogen plasma. Since H2 is a molecule consisting of only two hydrogen atoms, H radicals are generated as active species from the hydrogen plasma as shown in the following formula (1).
H2 + e− → 2H + e− (1)

On the other hand, SiH 4 flowing out from the supply hole 421 is supplied to the weak plasma generation space 102 between the electrode portion 41 and the substrate S, and is mixed with H radicals flowing from the upstream side to spread the surface of the substrate S. As a result, a mixed gas of H radicals and SiH 4 is supplied to the surface of the substrate S, and a reaction represented by the following formula (2) proceeds in the mixed gas.
SiH4 + H → SiH3 + H2 (2)

By supplying power with an appropriate power density to the electrode portion 41 in this way, an appropriate amount of H radicals can be generated, and a sufficient amount of SiH3 can be supplied to the surface of the substrate S. From the N radicals and SiH3, good quality SiN A film is formed on the surface of the substrate S.

At this time, by forming a weaker plasma in the weak plasma generation space 102 than in the strong plasma generation space 101, Si, SiH, SiH2 or the like is unnecessary as compared with a conventional capacitively coupled film forming apparatus using parallel plates. While maintaining the condition where active species are hardly generated, the progress of the reaction of (2) can be advanced, and ion damage to the substrate S can be reduced.

In addition, for example, when the plasma is formed in the strong plasma generation space 101 by grounding one of the

electrode portions

41a and 41b, for example, the electrode portion 41b, the space between the grounded electrode portion 41b and the substrate S is formed. Is difficult to generate plasma, and relatively strong plasma is generated in the space between the electrode portion 41a and the substrate S. For this reason, a region where plasma is generated in the weak plasma generation space 102 and a region where plasma is not generated are formed, and a good in-plane uniformity may not be obtained in the SiN film formed on the substrate S. .

In contrast, when high-frequency power of opposite phase is applied to both of the

adjacent electrode portions

41a and 41b, weak plasma is uniformly generated in the space between the substrate S for any electrode portion 41. This makes it easier to obtain a SiN film with higher in-plane uniformity. That is, in the structure in which the phase of the high frequency power applied to both of the

adjacent electrode parts

41a and 41b is shifted compared to the structure in which either one of the

electrode parts

41a and 41b, for example, the electrode part 41b is grounded, strong plasma is generated. Strong plasma is easily formed in the space 101 and weak plasma is easily formed in the weak plasma generation space 102. As a result, the in-plane uniformity of the SiN film can be improved.

In addition, in the mixed gas, as time elapses, that is, as the residence time becomes longer, SiH3 generated by the above formula (2) further reacts with H radicals, and SiH2, SiH, and Si are sequentially generated. Higher order silane and fine particles, which are seeds and their polymers, are taken into the SiN film, which causes deterioration of film quality and covering property.

Therefore, in the film forming apparatus 1 according to this embodiment, exhaust holes 431 for exhausting the reaction gas in the weak plasma generation space 102 are provided on the lower surface of each electrode portion 41. The inside of the processing chamber 10 is constantly evacuated through the exhaust hole 431 toward the exhaust passage 43, and the mixed gas spreading in the weak plasma generation space 102 reaches the surface of the substrate S and then moves upward in the flow direction. Then, the gas is quickly exhausted from the processing container 10 through the exhaust hole 431.

By providing the exhaust hole 431 on the lower surface of the electrode portion 41 in this way, the residence time of the mixed gas on the surface of the substrate S is shortened, and even when the reaction between H radicals and SiH 4 proceeds in the weak plasma generation space 102. The generation of unnecessary active species can be suppressed while supplying a high concentration of SiH 3 to the surface of the substrate S, and a SiN film with good film quality can be obtained.

With the configuration described above, (1) a space to which H2 / N2 or NH3 is supplied is configured as a strong plasma generation space 101 to obtain a large amount of N radicals and H radicals as active species, while a space to which SiH4 is supplied. Is formed as a weak plasma generation space 102, and a sufficient amount of SiH3 is supplied to the surface of the substrate S while suppressing ion damage to the substrate S by uniformly forming a weak plasma on the upper surface of the substrate S on which the film is formed. it can. Also, (2) generation of unnecessary active species associated with the radical reaction between H radicals and SiH4 proceeding more than necessary by quickly exhausting the mixed gas of excess H radicals and SiH4 from the surface of the substrate S. Can be suppressed.

In this way, film formation on the surface of the substrate S is performed for a preset time, and when an SiN film having a desired film thickness is obtained, supply of H2 / N2, supply of SiH4, and application of high-frequency power are stopped, and external The substrate S is unloaded from the processing container 10 by the operation opposite to that carried in by the substrate carrying mechanism, and the series of operations is completed.

The film forming apparatus 1 according to this embodiment has the following effects. For example, high-frequency power having a phase difference of 180 ° is applied to one and the other of the plate-like electrode portions 41 that are spaced apart from each other, and plasma is generated in the strong plasma generation space 101 sandwiched between these electrode portions 41. On the other hand, a weaker plasma than the plasma formed in the strong plasma generation space 101 is also formed in the weak plasma generation space 102 where film formation is performed. In the strong plasma generation space 101, N radicals and H radicals are generated, while in the weak plasma generation space 102, the reaction between the H radicals and SiH4 proceeds. As a result, according to the film forming apparatus 1 according to the present embodiment, the coverage of the SiN film formed on the substrate S can be improved.

As described above, the distance w between the adjacent electrode portions 41 is adjusted to a range of 2 to 20 mm, and the distance h between the lower surface of the electrode portion 41 and the substrate S is adjusted to a range of 5 to 100 mm. In the following, techniques for forming a SiN film with higher coverage on the substrate S are listed below.

For example, in FIG. 7, an inclined surface portion 46 is provided on the lower surface of each electrode portion 41 c so as to rise from the both side wall surfaces of the electrode portion 41 c toward the central portion, and the distance from the substrate S to the lower end of the inclined surface portion 46. In this example, the distance h1 from the substrate S to both side wall surfaces of the electrode portion 41c is larger than h2. Both side wall surfaces of the electrode portion 41c correspond to the exit (opening portion) of the strong plasma generation space 101, and it has been confirmed in the simulation described later that uniform plasma is formed in the vicinity of this region.

By disposing the lower end portion of the inclined surface portion 46 closer to the substrate S than the position of the exit of the strong plasma generation space 101, the coupling of electric capacity due to the gap between the lower end portion of the inclined surface portion 46 and the substrate S is made relatively. The plasma intensity at that position can be increased. Therefore, the intensity of the plasma formed near the exit of the strong plasma generation space 101 can be reduced, and the uniformity of the plasma in the weak plasma generation space 102 can be improved. In this example, h2 is adjusted within a range of 5 to 100 mm.

Further, as shown in FIGS. 8 and 9, the mounting table 2 a is supported on the floor surface in the processing container 10 via the caster part 26, and the mounting table 2 a is aligned along the arrangement direction of the electrode parts 41 by the drive mechanism 27. May be reciprocated. Even when the electron density in the vicinity of the exit of the strong plasma generation space 101 is high, the substrate S is moved back and forth in the lateral direction to move the region of the substrate S facing the region having the high electron density, thereby The coverage of the SiN film formed on S can be further improved.

Next, FIG. 10 shows that the distance w between the electrode portions 41 in the region where the deposition rate of the SiN film formed on the substrate S is increased is increased, and the plasma intensity in the strong plasma generation space 101 in the region is increased. The example of the electrode part 41d which improves the in-plane uniformity of a film thickness by reducing is shown. For example, the region on the center side of the substrate S where the supply holes 421 and the exhaust holes 431 are densely packed is an N radical and an H radical compared to the side end region of the substrate S where the supply holes 421 and the exhaust holes 431 are less than the center side. In addition, the amount of SiH4 supplied is large and the film formation rate tends to increase.

Therefore, as shown in the plan view of FIG. 10, the recess 44 is formed on the side wall surface of the electrode part 41d so that the distance w1 between the electrode parts 41d adjacent to each other in the region where the film forming speed is high. As a result, in the region where the film formation rate is low, the distance w2 between the electrode portions 41d is relatively smaller than in the region where the film formation rate is high. By adopting such a configuration, it is possible to reduce the plasma intensity in a region where the film formation rate is high, to uniform the film formation rate, and to improve the in-plane uniformity of the film thickness.

Here, the planar shape of the electrode part 41d is not limited to the example shown in FIG. For example, a preliminary experiment is performed using the electrode unit 41 shown in FIG. 4 to identify a region where the deposition rate is high, and the distance w between the electrode units 41d located in this region is relatively large. Thus, the planar shape of the electrode part 41d can be adjusted as appropriate.

Further, the method for adjusting the interval between the adjacent electrode portions 41 is not limited to the case where the distance between the electrode portions 41d is uniformly changed as shown in FIG. For example, as shown in the electrode portion 41e of FIG. 11, a notch 45 is provided at a distance on the side wall surface of the electrode portion 41e with a distance w, and the distance between the

electrode portions

41e and 41 in the notch 45 is w ′. It may be made to become. The cutout portion 45 is cut so that the average value of the distances between the

electrode portions

41e and 41 in the region where the cutout portion 45 is provided and the region where the cutout portion 45 is not provided is w1 described above. It is recommended to adjust the depth of the notch and the arrangement interval.

Next, a configuration example of a film forming apparatus provided with an electrode portion 41f suitable for film formation on a wafer used for manufacturing a semiconductor device will be described with reference to FIGS. 12 to 15, components having the same functions as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals as those shown in these drawings.

The SiN film formed on the wafer in the semiconductor device manufacturing process is required to have a higher level of in-plane uniformity compared to the case where the SiN film is formed on a substrate for a solar cell.

Therefore, in the film forming apparatus of another embodiment, as shown in FIG. 12, the shape of the bottom surface of the electrode portion 41f is, for example, a square, and these electrode portions 41f are not only in the X-axis direction in the figure but also in the Y-axis direction. In addition, the point that the long and thin plate-like electrode portions 41 are arranged at intervals only in the X-axis direction is different from the film forming apparatus 1 according to the first embodiment in that they are arranged at intervals. In other words, the strong plasma generation space 101 is formed in the crossing direction (X-axis direction) intersecting the direction (Y-axis direction) in which the strong plasma generation space 101 shown in FIG. Thus, it can also be said that the electrode part 41 is configured by being divided also in the Y-axis direction.

On the other hand, also in these electrode parts 41f, the distance between the electrode parts 41f arranged adjacent to each other across the strong plasma generation space 101 is, for example, 2 mm or more and 20 mm or less, more preferably 4 mm or more and 10 mm or less. The first embodiment is that the distance h between the lower surface of the electrode part 41 and the surface of the substrate S is adjusted to 5 mm or more and 100 mm or less, more preferably 7 mm or more and 30 mm or less. The form is the same.

As shown in an enlarged view in FIG. 13, supply holes 421 are provided on the bottom surface of each electrode portion 41 f at, for example, four corners of a square, and exhaust holes are provided in the center surrounded by these supply holes 421. 431 is provided. On the other hand, a strong plasma generation space 101 is formed between adjacent electrode portions 41f. In order to supply H2 / N2 or NH3 to the strong plasma generation space 101, an insulating member 31 that forms a ceiling portion of the processing vessel 10 is provided. The supply hole 321 is provided in the same manner as the film forming apparatus 1 of the first embodiment.

As shown in FIG. 14, for these supply holes 421 and supply holes 321 (see FIG. 13),

supply paths

42 and 32 provided on the upper surface side of the insulating member 31, and the insulating member 31 and the electrode part 41f are provided. H2 / N2, NH3, or SiH4 is supplied through the

branch paths

423 and 323 that penetrate therethrough. Further, the mixed gas flowing into the exhaust hole 431 is discharged to the outside through the branch path 433 and the exhaust path 43. In FIG. 14, only one set of each of the supply /

exhaust passages

42, 32, 43 and the

branch passages

423, 323, 433 is shown in order to avoid complication of the drawing.

Then, as schematically shown in FIG. 15, when each electrode portion 41 f is connected to the first and second

power supply portions

61 and 62 so that high-frequency power whose phase is inverted is applied to the adjacent electrode portion 41 f. As shown separately in white and gray in FIG. 12, the electrode portion 41f to which the electric power with reversed phase is applied is surrounded by a strong plasma generation space 101 extending so as to intersect in a lattice pattern, like a checkered pattern. It will be in the state where it lined up. Here, in FIG. 15, the electrode portion 41 f connected to the first power supply portion 61 is denoted by “41 a”, and the electrode portion 41 f connected to the second power supply portion 62 is denoted by “41 b”. The point which is attached | subjected is the same as that of the case of FIG.

The shape of the bottom surface of the electrode portion 41f is, for example, a square, and these electrode portions 41f are arranged in the front-rear and left-right directions, and by applying power whose phase is reversed to the adjacent electrode portions 41f, only the left-right direction (X-axis direction in FIG. 12) is applied. In addition, the plasma is dispersed in the front-rear direction (Y-axis direction in FIG. 12). Therefore, even if there is a slight difference in the film formation speed in the respective regions below the electrode portion 41f and the strong plasma generation space 101, the regions having different film formation rates are arranged in a distributed manner. Become. As a result, small regions having different film thicknesses are formed on the wafer in a distributed manner over the entire surface of the wafer, and the in-plane uniformity of the film thickness is improved when the entire wafer is viewed. In FIG. 12, the position of the outer periphery of the wafer disposed on the lower side of the electrode portion 41f is indicated by a one-dot chain line.

In FIG. 16, in order to reduce the arrangement density of the electrode portions 41g to 41j on the center side of the wafer and increase on the peripheral edge side, the length of one side of the bottom surface of the electrode portions 41g to 41j formed in a square shape is The example which comprised so that it might become long gradually toward the peripheral part side from the part side is shown. This example corresponds to the example of the electrode part 41d shown in FIG. 10, and the interval between the adjacent electrode parts 41g to 41j is changed so as to cancel out the difference in the arrangement density of the supply holes 421 and the exhaust holes 431, for example. By doing so, the film forming speed is made uniform, and the in-plane uniformity of the film thickness is improved.

Further, the shape of the bottom surface of the electrode portion is not limited to a rectangular shape such as a square, and an electrode portion 41k having a circular bottom surface may be used as shown in FIG. May be. Further, the strong plasma generation spaces 101 that intersect with each other and extend in a lattice shape are not limited to being orthogonal to each other, and the strong plasma generation spaces 101 may be crossed obliquely. In this case, the shape of the bottom surface of the electrode portion is, for example, a rhombus.

FIG. 18 shows an example in which one of the electrode portions 41m (41n) (first electrode portion) is integrated among the

electrode portions

41m and 41n to which high-frequency powers whose phases are reversed are applied. For example, the first electrode portion 41m is made of a wide metal plate that covers the upper side of the plate surface of the wafer, and the second electrode portion 41n (second electrode portion) is disposed at a position where the second electrode portion 41n (second electrode portion) is disposed. An opening 103 that is slightly larger than the planar shape of the electrode portion 41n is formed. Then, by inserting the second electrode portion 41n into the opening 103, there is a gap between the inner surface of the opening 103 and the outer surface of the second electrode portion 41n disposed inside thereof. The gap is formed and the strong plasma generation space 101 is formed. The opening 103 in this example is similar to the electrode part 41f shown in FIG. 12 described above, and is provided with

electrode parts

41m and 41n to which high-frequency power with reversed phase is applied (shown separately in white and gray). Are arranged in a checkered pattern. By integrating the first electrode part 41m as in this example, the number of parts of the first electrode part 41m and the power supply system can be reduced, and the cost can be reduced.

Here, the shapes of the integrated first electrode portion 41m and the second electrode portion 41n inserted into the opening 103 are not limited to the example shown in FIG. FIG. 19 shows an example in which hexagonal openings 103 are regularly arranged in the first electrode part 41о formed in a hexagonal shape, and the second electrode part 41p is inserted into the opening part 103. . In this example, a hexagonal region (indicated by a broken line in FIG. 19) of the first electrode part 41о sandwiched between the openings 103 and the second electrode part 41p are arranged in a honeycomb shape. Thus, the electrode portions 41о and 41p are highly symmetrical as viewed from the wafer. As a result, it is possible to improve the symmetry of the reactant gas flow and the plasma distribution and perform uniform film formation. In addition, as shown in FIG. 17, the shape of the second electrode portion may be other shapes such as a circle, or as shown in FIG. 16, the area of the second electrode portion or the strong plasma generation space 101 Needless to say, the width of the gap forming the gap may be changed between the central portion side and the peripheral portion side of the wafer.

In addition, a rotation axis that rotates around the vertical axis is provided at the center on the lower surface side of the mounting table 2 that supports the wafer, and film formation is performed while the wafer on the mounting table 2 is rotated. In-plane uniformity may be further improved. On the other hand, the disc-shaped wafer is formed in the same size as shown in FIG. 12, for example, because the circumferential length is different between the position on the center side and the position on the outer periphery side. When the wafer is rotated under the electrode part 41f arranged like a checkered pattern, the number of electrode parts 41f passing over the wafer during one rotation is different between the central part side and the outer peripheral part side. End up. As a result, the outer peripheral portion of the wafer is exposed to the plasma concentration portion (for example, the lower region of the strong plasma generation space 101) more frequently than the inner peripheral portion, and the film formation rate is uneven when viewed in the radial direction. There is also a concern that this will expand.

Therefore, when rotating the wafer, as shown in FIG. 20, the strong plasma generation space 101 extending along the circumferential direction of the wafer and the strong plasma extending along the direction intersecting with this direction, that is, along the radial direction of the wafer. An electrode portion 41l divided by the generation space 101 may be provided. Since the number of electrode portions 41l arranged above the electrode portion 41l divided in this way is the same at the position on the center side of the wafer and the position on the outer peripheral portion side, the wafer is rotated one revolution. Further, the number of electrode portions 41l passing above and the number of strong plasma generation spaces 101 extending in the radial direction are uniform, and the film formation rate can be made uniform when viewed in the radial direction.

Further, as a method for adjusting the intensity of the plasma formed in the strong plasma generation space 101, the phase difference of the high frequency power applied from the first and second

power supply units

61 and 62 is smaller than 180 °, for example, 30 °. The plasma intensity may be made smaller than that in the case where the phase is inverted (the phase is shifted by 180 °) by adjusting to a range of from above to less than 180 °. Moreover, the high frequency power applied to the electrode part 41 is not restricted to the example of 13.56 MHz, Of course, other frequencies, for example, 100 MHz or other high frequency power may be applied.

Further, in the film forming apparatus 1 shown in FIG. 1, the example in which the reaction gas in the weak plasma generation space 102 is exhausted to the outside through the exhaust hole 431 opened on the lower surface of the electrode portion 41 is shown. Is not limited to the case of forming in the electrode part 41. For example, when a good film quality can be obtained even if exhaust is performed from the exhaust pipe 13 shown in FIG. 1, the case where the exhaust pipe 13 is used as an exhaust part is not denied.

Furthermore, the present invention is not limited to application to the formation of a SiN film using H2 / N2 or NH3 and SiH4. For example, the present invention can be applied to the case where a SiN film is formed by using a silicon compound gas other than SiH4, for example, SiH2Cl2.

In the above-described embodiment, an example in which the strong plasma generation space 101 and the weak plasma generation space 102 are formed in the processing container 10 using the plurality of electrode portions 41 has been described, but the disclosed technique is not limited thereto. For example, the strong plasma generation space 101 is formed in one of two spaces obtained by dividing the processing vessel 10 using a partition plate or the like in which a through hole is formed, and the weak plasma generation space is formed in the other space. 102 may be formed.

(Simulation 1)
The distribution of the electron density in the weak plasma generation space 102 was simulated when the inclined surface portion 46 was not provided in the electrode portion 41.

A. Simulation conditions (Example 1-1)
In the example shown in FIG. 6, the distance between the electrode portions 41 is w = 10 mm, the distance between the lower surface of the electrode portion 41 and the substrate S is h = 20 mm, and 13.56 MHz, 400 W / piece from the first power supply portion 61. A strong plasma generation space in a state in which a high frequency power of 13.56 MHz and 600 W / line, which is 180 degrees out of phase with the high frequency power of the first power supply unit 61, is applied from the second power supply unit 62. 101, the electron density distribution in the weak plasma generation space 102 was simulated by a plasma fluid model. References for plasma fluid models include M.I. J. et al. Kushner: J.A. Phys. D42, 194013 (2009). The pressure in the processing container 10 was 200 Pa.
Example 1-2
Similar to the example shown in FIG. 7, a simulation was performed under the same conditions as in Example 1-1 except that the inclined surface portion 46 was provided on the lower surface of the electrode portion 41 and h1 = 20 mm and h2 = 10 mm.

B. Simulation Result The simulation result of (Example 1-1) is shown in FIG. 21 (a), and the simulation result of (Example 1-2) is shown in FIG. 21 (b).

According to the result of Example 1-1 shown in FIG. 21A, a region with a high electron density was confirmed on the lower side of the opening of the strong plasma generation space 101. On the other hand, in (Example 1-2) shown in FIG. 21B, an inclined surface portion 46 is provided on the lower surface of the electrode portion 41c so as to be inclined from the both side wall surfaces of the electrode portion 41c toward the central portion. Thus, the region having a high electron density observed in (Example 1-1) is considerably eliminated, and plasma is uniformly formed over the entire weak plasma generation space 102. This is thought to be because the concentration of the electron density at the exit of the strong plasma generation space 101 was alleviated by strengthening the coupling of electric capacity by the gap with the substrate S at the tip of the inclined surface portion 46.

(Experiment 2)
As shown in FIG. 5, the frequency signal generator 63 and the first and second

power supply units

61 and 62 are connected via the first and

second signal lines

611 and 621, and the second signal line 621 is connected. The waveform of the high frequency power output from the first and second

power supply units

61 and 62 when the length was changed was measured with an oscilloscope.
A. Experimental conditions (Example 2-1)
The length of the first signal line 611 from the frequency signal generator 63 to the first power supply unit 61 is 1 m, and the length of the second signal line 621 from the frequency signal generator 63 to the second power supply unit 62 is Was 8.4 m.
(Example 2-2)
Example 2 is the same as Example 2-1 except that the length of the second signal line 621 from the frequency signal generator 63 to the second power supply unit 62 is 2.85 m.
(Example 2-3)
Example 2 is the same as Example 2-1 except that the length of the second signal line 621 from the frequency signal generator 63 to the second power supply unit 62 is 4.7 m.

B. Experimental Results The measurement results of the high-frequency power waveforms in Examples 2-1 to 2-3 are shown in FIGS. 22A to 22C, respectively. In each figure, the waveform of the high frequency power output from the first power supply unit 61 is indicated by a solid line, and the waveform of the high frequency power output from the second power supply unit 62 is indicated by a broken line.

In the case of (Example 2-1) shown in FIG. 22A, the difference between the lengths of the first and

second signal lines

611 and 621 is set to 7.4 m. It was possible to shift the phase difference of the high-frequency power output from the

units

61 and 62 by 180 ° (invert the phase). Also in the case of (Example 2-2) shown in FIG. 22B and (Example 2-3) shown in FIG. 22C, the lengths of the first and

second signal lines

611 and 621, respectively. By setting the difference in height to 1.85 m and 3.7 m, the phase difference of the high-frequency power could be changed to 45 ° and 90 °. From these results, when the high frequency power is output from the first and second

power supply units

61 and 62 in synchronization with the frequency signal input from the frequency signal generator 63 as shown in FIG. It was confirmed that the phase difference of the high-frequency power applied to the adjacent electrode portions 41 can be adjusted by making the lengths of the two

signal lines

611 and 621 different.

(Experiment 3)
In Experiment 3, a film forming apparatus 1 that supplies a reactive gas containing H2 / N2 to the strong plasma generation space 101 and SiH4 to the weak plasma generation space 102, and a general inductively coupled plasma (ICP). The coverage of the SiN film formed on the substrate S and the concentration of each atom in the SiN film were compared with a film forming apparatus using the above.

A. Experimental conditions (Example 3)
Film forming apparatus: Film forming apparatus 1 shown in FIG.
Process gas: H2 / N2 / SiH4 = 1000/500/20 sccm
High frequency power: 1000W
Pressure in processing container 10: 200 Pa
Substrate temperature: 70 ° C
(Comparative Example 1)
Film forming apparatus: Film forming apparatus using ICP Processing gas: H2 / N2 / SiH4 = 1000/500/20 sccm
High frequency power: 1000W
Pressure in processing container 10: 200 Pa
Substrate temperature: 70 ° C

B. Experimental Results FIGS. 23 to 25 are diagrams showing experimental results in Comparative Example 1 and Example 3. FIG. FIG. 23 is a trace view of a photograph in which a cross section of the substrate after the experiment of Comparative Example 1 is enlarged. FIG. 24 is a trace view of a photograph in which a cross section of the substrate after the experiment of Example 3 is enlarged.

FIG. 25 shows the relationship between the step coverage after the experiment in Comparative Example 1 and Example 3 and the partial pressure of SiH4. In FIG. 25, the vertical axis represents step coverage (%), and the horizontal axis represents SiH4 partial pressure (Pa). In FIG. 25, as the step coverage after the experiment in Comparative Example 1 and Example 3, the degree of coverage of the SiN film formed at the bottom of the trench groove on the substrate with respect to the SiN film formed on the flat portion of the substrate is shown. The bottom step coverage (Bottom Step Coverage) shown and the side step coverage (Side Step Coverage) showing the degree of coverage of the SiN film formed on the sidewall of the trench groove on the substrate are shown. In addition, it shows that the coverage of a SiN film | membrane is so high that the value of a bottom step coverage and a side step coverage is large.

As shown in FIGS. 23 to 25, compared with Comparative Example 1 using ICP, the reactive gas containing H2 / N2 is supplied to the strong plasma generation space 101 and SiH4 is supplied to the weak plasma generation space 102. In Example 3, the coverage of the SiN film was improved.

Further, as a result of further earnest research, the inventor has found that when the partial pressure of SiH4 is 1 Pa or more and 4 Pa or less, the coverage of the SiN film can be improved while maintaining the film quality of the SiN film. It was. For this reason, it is preferable that the partial pressure of SiH4 is 1 Pa or more and 4 Pa or less.

FIG. 26 is a diagram showing the concentration of each atom in the SiN film formed on the substrate after the experiment of Comparative Example 1. FIG. FIG. 27 is a diagram showing the concentration of each atom in the SiN film formed on the substrate after the experiment of Example 3. In FIG. In FIG. 26 and FIG. 27, the vertical axis represents the atomic concentration (%). In FIG. 26, the horizontal axis indicates the flow rate (sccm) of SiH4. In FIG. 27, the horizontal axis represents the ratio of the flow rate of SiH4 to the sum of the flow rate of SiH4 and the flow rate of N2.

As shown in FIGS. 26 and 27, in both Comparative Example 1 and Example 3, the concentration of N atoms in the SiN film increased as the flow rate of SiH 4 decreased. That is, in Example 3 in which a reactive gas containing H2 / N2 is supplied to the strong plasma generation space and SiH4 is supplied to the weak plasma generation space, the nitriding reaction is promoted as in Comparative Example 1 using ICP. I understood.

In addition, as a result of further earnest research, the inventor has found that good step coverage can be obtained when the temperature of the substrate S is 70 ° C. or higher and 300 ° C. or lower. Furthermore, it was found that when the temperature of the substrate S is 70 ° C. or higher and 150 ° C. or lower, good step coverage can be obtained and generation of particles due to decomposition of SiH 4 can be suppressed. For this reason, the temperature of the substrate S is preferably 70 ° C. or higher and 300 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower, and most preferably 70 ° C.

FIG. 28 is an enlarged trace view of the cross section of the substrate on which the SiN film is formed by the film forming apparatus shown in FIG. 1 when the substrate temperature is 70 ° C. FIG. 29 is a diagram showing step coverage of a substrate on which a SiN film is formed by the film forming apparatus shown in FIG. 1 when the temperature of the substrate is 70 ° C., 150 ° C., or 300 ° C. In FIG. 29, the vertical axis indicates the distance d (nm) between the SiN films formed on the pair of side walls sandwiching the trench groove on the substrate. The shorter the distance d, the better the step coverage. It is assumed that the distance between the pair of side walls sandwiching the trench groove on the substrate before the SiN film is formed is 30 (nm).

In FIG. 29, “70 ° C.” indicates that the substrate temperature is 70 ° C., “150 ° C.” indicates that the substrate temperature is 150 ° C., and “300 ° C.” indicates that the substrate temperature is Indicates that the temperature is 300 ° C.

As shown in FIGS. 28 and 29, when the substrate temperature is 70 ° C., the distance d is 23.3 (nm). When the substrate temperature was 150 ° C., the distance d was 23.3 (nm). When the substrate temperature was 300 ° C., the distance d was 22.0 (nm). These distances d all satisfy a predetermined allowable specification.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Mounting stand 7 Control part 10 Processing container 32 Supply path 41 Electrode part 42 Supply path 51 Supply part 52 Supply part 61 1st power supply part 62 2nd power supply part 101 Strong plasma generation space 102 Weak plasma generation space 511 Supply line 521 Supply line S Substrate

Claims

A processing vessel;
A mounting table provided in the processing container for mounting a substrate;
A first gas supply unit that supplies a reactive gas containing H2 / N2 or NH3 to the strong plasma generation space formed in the processing container;
Silicon nitride is formed on the substrate by reacting with the active species of the reactive gas in a weak plasma generation space that generates plasma having a light emission intensity lower than that of the plasma formed in the strong plasma generation space. A second gas supply unit for supplying a silicon compound gas for forming the film;
A film forming apparatus comprising: a high-frequency power source that supplies high-frequency power for converting the reaction gas and the silicon compound gas into plasma.
Above the substrate placed on the mounting table, in order to form the strong plasma generation space, they are arranged at intervals in a vertical orientation, and in the gap between the lower end and the substrate. A plurality of electrode portions that form the weak plasma generation space;
The high-frequency power source supplies the high-frequency power having a phase different from each other to a pair of electrode portions adjacent to each other across the strong plasma generation space among the plurality of electrode portions, whereby the reaction gas, the silicon compound gas, The film forming apparatus according to claim 1, wherein the film is converted into plasma.
3. The film forming apparatus according to claim 1, wherein a power density of the high frequency power supplied from the high frequency power source is 1 W / cm 2 or more and 3 W / cm 2 or less.
The film forming apparatus according to claim 1, wherein a partial pressure of the silicon compound gas is 1 Pa or more and 4 Pa or less.
The film forming apparatus according to claim 1, wherein the temperature of the substrate is 70 ° C. or higher and 300 ° C. or lower.