TWI684668B - Method for producing silicon nitride film, and silicon nitride film - Google Patents

Abstract

One object of the present invention is to provide a method for producing a silicon nitride film, which has high resistance to hydrofluoric acid and humidity, and appropriate internal stress, on a substrate having a temperature adjusted to 250℃ or less, the present invention provides a method for producing a silicon nitride film 30 having desired resistance to hydrofluoric acid and humidity, and internal stress on a substrate 20 having a temperature adjusted to 250℃ or less by a plasma chemical gas phase growing method using organosilane gas a raw material gas, wherein a treatment gas which is obtained by adding 200 to 2,000 volume flow of hydrogen reducing gas to 1 volume flow of the organosilane gas, a pressure in a process chamber for storing the substrate 20 is adjusted to a range from 35 to 400 Pa, and a power density of high frequency applied to an electrode in the process chamber is adjusted to a range from 0.2 to 3.5W/cm².

Description

Manufacturing method of silicon nitride film and silicon nitride film

The invention relates to a method for manufacturing a silicon nitride film and an invention of a silicon nitride film.

The silicon nitride film has excellent chemical stability, so it is used as a masking material in the manufacturing steps of semiconductor devices such as electronic devices and optical devices, as well as metal diffusion prevention films, oxidation barrier films, and passivation films that constitute semiconductor devices ) And insulating films.

As a method of manufacturing a silicon nitride film on a substrate, it is widely used: a thermal chemical vapor deposition method (thermal CVD) in which a mixed gas of chlorinated silane and ammonia is supplied on a substrate heated to 700°C or higher ), or plasma active chemical vapor deposition (plasma CVD) that supplies the active species obtained by plasma excitation of a mixed gas of silane and ammonia onto a substrate heated to above 350°C and then forms a film Wait.

In recent years, with the miniaturization/high integration of semiconductor devices and the expanded use of silicon nitride films, substrates or substrates for manufacturing silicon nitride films have diversified, and substrates with low heat resistance have increased. Therefore, in the plasma CVD method, it is desirable to manufacture the silicon nitride film at 300°C or lower, and at 250°C or lower.

However, in general, when the film-forming temperature is lowered, it becomes difficult to control the atomic composition of the film or the bonding state between atoms. Therefore, compared with plasma CVD at a substrate temperature exceeding 350°C, the film structure becomes rougher. Furthermore, it is known that the bonding between silicon atoms and hydrogen atoms, nitrogen atoms and hydrogen atoms will increase, and the chemical stability will be increased. reduce.

On the other hand, in the case of manufacturing other thin films on silicon nitride films used for insulating layers, etc., there is a possibility of contaminants such as organic substances or particles adhering to the surface of the silicon nitride layer, so before manufacturing other thin films, In some cases, the surface of the silicon nitride layer is immersed in a cleaning solution such as dilute hydrofluoric acid to perform cleaning treatment to remove contaminants. For this treatment, if the silicon nitride film is thinned, the intended function cannot be exerted, so the silicon nitride film is required to have high hydrofluoric acid resistance.

Similarly, when used as an etching stopper layer in the etching step of the manufacturing device structure, a high hydrofluoric acid resistance is also required for the silicon nitride film. Therefore, for the above reasons, when the chemical stability of the silicon nitride film is reduced, there is a possibility that it cannot function as a metal diffusion prevention film, an oxidation barrier film, a passivation film, an insulating film, and the like.

In response to such a problem, Patent Document 1 discloses a method of manufacturing a silicon nitride film with a wet etching speed of a hydrofluoric acid solution (1% HF aqueous solution) of less than 50 nm/min in a high-density plasma CVD apparatus. However, the substrate temperature is around 450°C, which does not meet the above expectations of 250°C or lower. This system means that it is difficult to manufacture a silicon nitride film with high hydrofluoric acid resistance.

In addition, in Patent Document 2, as the substrate temperature 200 The method of manufacturing a SiNCH film with hydrofluoric acid resistance and low leakage current value (high insulation) up to 400°C reveals a plasma CVD method using an organic silazane compound. However, there is no indication of quantitative values for hydrofluoric acid resistance and insulation. Also, there is no mention of the humidity resistance required for oxidation barrier films and passivation films.

In addition, Patent Document 3 discloses a plasma CVD method for manufacturing a silicon nitride film effective for a passivation film at 200° C. or lower. However, only the gas permeability of the membrane characteristics is mentioned, and the hydrofluoric acid resistance necessary and indispensable in the construction of the manufacturing device is not mentioned.

Incidentally, in order to use a silicon nitride film as a thin film constituting a semiconductor device, it is necessary to manufacture a silicon nitride film with low internal stress for the purpose of preventing deformation of the substrate or film peeling. Patent Document 4 discloses a method for manufacturing a silicon nitride film. In the examples, the internal stress of the silicon nitride film manufactured in the range of 25 to 250°C is in the range of -200 MPa to 200 MPa. However, there is no description about the film properties other than internal stress.

In addition, Patent Document 5 discloses that in a plasma CVD method using silane or disilazane, by controlling the flow rate of hydrogen gas and microwave output, the film stress of a silicon nitride film formed on a substrate below 100°C can be controlled The technology in the range of -400 to +100 MPa, but the impact on moisture resistance and insulation is not described at all.

[Prior Technical Literature] (Patent Literature)

[Patent Document 1] Japanese Patent No. 5269903

[Patent Document 2] Japanese Patent No. 4048112

[Patent Document 3] Japanese Patent Laid-Open No. 2011-89186

[Patent Document 4] Japanese Patent Laid-Open No. 9-186153

[Patent Document 5] Japanese Unexamined Patent Publication No. 2012-188735

Incidentally, in recent years, what is desired for the production of silicon nitride films by the plasma CVD method is that the wet etching rate is lower than that of conventional silicon nitride films manufactured at a substrate temperature of 350°C or higher. Films with moisture resistance equal to or higher are manufactured on a substrate controlled at a low temperature of 250°C or lower, and the internal stress in the film can be arbitrarily controlled.

However, lowering the substrate temperature is related to the problem of reducing various characteristics such as high hydrofluoric acid resistance, high barrier properties, adjustment of appropriate internal stress, and high insulation required for thin films constituting semiconductor devices and the like.

Also, as mentioned above, although attempts have been made to improve the characteristics of the film by adjusting the conditions of film formation, since the influence of the characteristics of each film will vary with each condition factor, it has not yet been established that it is simultaneously satisfied in a low temperature environment. Method for manufacturing silicon nitride film with multiple film characteristics.

Therefore, the present invention is made in view of the above circumstances, and the object is to provide a method for manufacturing a silicon nitride film and a silicon nitride film, which can provide high hydrofluoric acid resistance, high humidity resistance, and device side The silicon nitride film with appropriate internal stress should be formed below 250℃ due to the expected internal stress Manufactured in temperature.

In general, it is known that when there are many hydrogen atoms in the silicon nitride film, that is, when there are many Si-H bonds or N-H bonds, for example, hydrofluoric acid resistance and moisture resistance will deteriorate. In particular, in the case of the plasma CVD method, as the interatomic bonds in the raw material gas dissociate, a large amount of hydrogen atoms are released and taken into the film, so it is difficult to produce a high-quality film. As a countermeasure, it is known that by using a carbon-containing raw material gas and adding carbon atoms to the silicon nitride film, hydrofluoric acid resistance can be improved. On the other hand, it is known that the above-mentioned measures deteriorate the insulation.

The inventors of the present application have extensively studied and discussed in order to solve these opposite problems, and have completed the invention of the present application. That is, a method of improving the effect of improving hydrofluoric acid resistance and moisture resistance while suppressing the amount of carbon added to the silicon nitride film was invented. Specifically, it is an invention that enables the direct exhaust of either or both of the excessive carbon atoms and hydrogen atoms in the plasma space, and the appropriate amount of carbon atoms in a bonded state with low conductivity. The technology taken into the film is a method that has both by appropriately adjusting the condition factors for the production of a plurality of silicon nitride films.

In addition, although the structure of the silicon nitride film itself has not been ascertained, according to the above method, it is found that the wet etching rate is lower and the humidity resistance is lower than that of the conventional silicon nitride film manufactured at a substrate temperature of 350° C. or higher. The silicon nitride film is more than equal and has moderate internal stress. Specifically, if the above method is used, it is found that (a) the etching rate by the hydrofluoric acid solution is 10 nm/min or less, (b) at 208 kPa, 121 The formation rate of silicon oxide generated during exposure in a saturated water vapor environment at ℃ is converted to a silicon oxide film of 2 nm/hr or less, and (c) the internal stress in the film is nitriding in the range of -1000 to 1000 MPa Silicon film.

That is, the present invention has the following configurations (1) to (8).

(1) The present invention provides a method for manufacturing a silicon nitride film, which uses organic silane gas as a raw material gas and is manufactured by a plasma chemical vapor deposition method on a substrate at a temperature of 250°C or less with the following ( The method of the silicon nitride film with the film characteristics shown in a) to (c) is characterized in that, relative to 1 volume flow of the aforementioned organosilane gas, a processing gas added with hydrogen reducing gas at a volume flow of 200 to 2000 is used, Adjust the pressure in the process chamber that has housed the substrate to the range of 35 to 400 Pa, and adjust the high-frequency power density applied to the electrodes installed in the process chamber to the range of 0.2 to 3.5 W/cm ² Inside.

(a) The etching rate by hydrofluoric acid solution is 10 nm/min or less

(b) The formation rate of silicon oxide generated during exposure in a saturated water vapor environment of 208 kPa and 121°C, converted to a silicon oxide film of 2 nm/hr or less

(c) The internal stress in the film is in the range of -1000 to 1000MPa

In the above manufacturing method, it is preferable to adjust the linear velocity of the processing gas introduced into the processing chamber to a range of 0.3 to 5.0 cm/sec.

In addition, the above "linear velocity" means a value calculated from the total flow rate of supplied gas ÷ plasma generation area × (atmospheric pressure ÷ process pressure).

In addition, the above-mentioned plasma generation area means an electrode area for generating plasma.

(2) The method for manufacturing a silicon nitride film as described in (1), which In the process, the linear velocity of the processing gas introduced into the processing chamber is adjusted to the range of 0.3 to 5.0 cm/sec.

(3) The method of manufacturing a silicon nitride film as described in (1) or (2), wherein the organic silane gas system formula (R ¹ R ² N) _n SiH _4-n (where R ¹ and R ² is an independent hydrocarbon group, and n is an organic silane gas shown in any number of 2, 3, and 4.

(4) The method for manufacturing a silicon nitride film according to (3), wherein the hydrocarbon group is a methyl group or an ethyl group.

(5) The method for manufacturing a silicon nitride film as described in (1), wherein the organic silane gas contains dimethylaminosilane, para-dimethylaminosilane, bisdimethylaminosilane, and Diethylamino silane, bis diethyl amine silane, bis diethyl amine silane, ethyl ethyl methyl amine silane, gin ethyl methyl amine silane, bis ethyl methyl amine silane More than one of them.

(6) The method for manufacturing a silicon nitride film according to any one of (1) to (5), wherein the hydrogen reducing gas contains hydrogen atoms.

(7) The method for producing a silicon nitride film according to (6), wherein the hydrogen reducing gas contains any one or more of ammonia, amine, and hydrocarbon.

(8) To provide a silicon nitride film, which is a silicon nitride film having the film characteristics shown in the following (a) to (c), characterized in that in a plasma chemical vapor deposition method, an organic silane is used Gas is used as the raw material gas, and the film-forming temperature is set to 250°C or less, and the processing gas added with hydrogen reducing gas at a volume flow of 200 to 2000 is used for the volume of the aforementioned organosilane gas at a volume flow of 1 to 2000, and the pressure in the processing chamber It is adjusted to the range of 35 to 400 Pa, and the high-frequency power density applied to the electrode provided in the aforementioned processing chamber is adjusted to the range of 0.2 to 3.5 W/cm ² to form a film.

(a) The etching rate by hydrofluoric acid solution is 10 nm/min or less

(b) The formation rate of silicon oxide generated during exposure in a saturated water vapor environment of 208 kPa and 121°C, converted to a silicon oxide film of 2 nm/hr or less

(c) The internal stress in the film is in the range of -1000 to 1000 MPa.

The method for manufacturing a silicon nitride film of the present invention uses an organic silane gas as a raw material gas, and when the silicon nitride film is manufactured by a plasma chemical vapor deposition method at a film forming temperature of 250°C or less, relative to 1 volume flow rate The organic silane gas, using a processing gas with a hydrogen reduction gas added at a volume flow of 200 to 2000, adjusts the pressure within the processing chamber of the contained substrate to a range of 35 to 400 Pa, which will apply a high pressure to the electrodes installed in the processing chamber The frequency power density is adjusted to the range of 0.2 to 3.5W/cm ² . By this, a silicon nitride film having high hydrofluoric acid resistance, high moisture resistance, and appropriate internal stress on the device side due to the desired can be manufactured.

Secondly, the silicon nitride film of the present invention uses organic silane gas as the raw material gas in the plasma chemical vapor deposition method, while setting the film forming temperature to 250°C or less, relative to 1 volume flow of organic Silane gas, using 200 to 2000 volume flow of processing gas added with hydrogen reducing gas, adjust the pressure in the processing chamber to the range of 35 to 400 Pa, and adjust the high-frequency power density applied to the electrodes installed in the processing chamber to 0.2 If the film is formed within the range of 3.5W/cm ² , it can provide a silicon nitride film with high hydrofluoric acid resistance, high moisture resistance, and appropriate internal stress on the device side due to the desired.

20‧‧‧ substrate

30‧‧‧Silicon nitride film

40‧‧‧ processing room

41‧‧‧Platform

44a, 44b ‧‧‧ heater

45‧‧‧Lamp head gas introduction department

46a, 46b ‧‧‧ power supply

47‧‧‧Vacuum pump

48‧‧‧Exhaust flow regulator

49‧‧‧Control Department

50‧‧‧Organic silane gas supply source

51‧‧‧Gas flow regulator

52‧‧‧The first hydrogen reducing gas supply source

53‧‧‧Gas flow regulator

54‧‧‧Second hydrogen reducing gas supply source

55‧‧‧Gas flow regulator

60‧‧‧Computer

100‧‧‧Plasma CVD device

S‧‧‧Insulation Department

L1‧‧‧Gas supply line

L2‧‧‧The first hydrogen reducing gas supply line

L3‧‧‧Second hydrogen reducing gas supply line

L4‧‧‧Exhaust line

C1, C2, C3, C4, C5, C6, C7, C8

P1, P2‧‧‧Power wiring

FIG. 1 is a diagram showing a configuration example of a plasma CVD apparatus used in a method of manufacturing a silicon nitride film according to an embodiment of the present invention.

Figure 2 is a graph showing the relationship between the gas ratio and the BHF etching rate.

Figure 3 is a graph showing the relationship between the gas ratio and the rate of oxide film formation.

Figure 4 is a graph showing the relationship between the gas ratio and the film formation speed of the silicon nitride film.

Figure 5 is a graph showing the relationship between pressure and BHF etching rate.

Figure 6 is a graph showing the relationship between pressure and the rate of oxide film formation.

Figure 7 is a graph showing the relationship between linear velocity and BHF etching rate.

Figure 8 is a graph showing the relationship between the linear velocity and the rate of oxide film formation.

Figure 9 is a graph showing the relationship between high-frequency power density and BHF etching rate.

FIG. 10 is a graph showing the relationship between high-frequency power density and oxide film formation rate.

Hereinafter, the method for manufacturing a silicon nitride film according to an embodiment of the present invention will be described in detail using drawings. Also, in the following description In the drawings used in the drawings, for the sake of easy understanding of the characteristics, and for the sake of convenience, the features may be enlarged, and the size ratios of the components may not be the same as the actual ones.

<Manufacture device of silicon nitride film>

First, the configuration of a silicon nitride film manufacturing apparatus that can be used in the method for manufacturing a silicon nitride film according to an embodiment of the present invention will be described. That is, an example of the configuration of the plasma chemical vapor deposition apparatus (plasma CVD) used in the method of manufacturing the silicon nitride film of this embodiment will be described.

FIG. 1 is a diagram showing an example of the configuration of a plasma CVD apparatus used in the method for manufacturing a silicon nitride film according to an embodiment of the present invention. As shown in FIG. 1, the plasma CVD apparatus 100 accommodates the substrate 20 and includes: a processing chamber 40, a stage 41, heaters 44a, 44b, a shower head gas introduction part 45, and a power supply 46a, 46b, vacuum pump 47, exhaust flow regulator 48, control unit 49, organosilane gas supply source 50, first hydrogen reducing gas supply source 52, second hydrogen reducing gas supply source 54, gas flow regulators 51, 53, 55 , The schematic structure of the computer 60 and the insulating portion S.

The substrate 20 is provided on the stage 41, and the silicon nitride film 30 is manufactured on the substrate 20. The material of the substrate is not particularly limited as long as it has heat resistance at a film formation temperature of 250°C. Specifically, for example, quartz or the like can be used.

The processing chamber 40 accommodates the substrate 20 and has a platform 41, heaters 44a and 44b, and a shower head gas introduction part 45. The organosilane gas supply source 50 supplies the organosilane gas from the first hydrogen reducing gas supply source 52 and the second hydrogen reducing gas The source 54 supplies hydrogen reducing gas into the processing chamber 40 to manufacture the silicon nitride film 30.

The platform 41 is provided near the center of the processing chamber 40.

The heater 44a is provided above the showerhead gas introduction part 45 and the side of the processing chamber 40, and the heater 44b is provided below the platform 41, and the temperature in the processing chamber 40 and the substrate 20 can be adjusted. Although the upper limit of the substrate temperature is not particularly limited, it is preferably set to 250° C. or less in view of the background required for low-temperature film formation.

The shower head gas introduction part 45 is provided in the upper part of the processing chamber 40, and introduces the organosilane gas and hydrogen reducing gas into the treatment chamber 40 via the shower head gas introduction part 45.

The power supply 46a is connected to the shower head gas introduction part 45 via the power supply wiring P1. On the other hand, the power supply 46b is connected to the platform 41 via the power supply wiring P2. The power supply 46a can plasmatize the gas mixed with the organosilane gas and the hydrogen reducing gas discharged from the shower head gas introduction part 45 by applying electric power of a specific frequency to the shower head gas introduction part 45. The platform 41 is supplied with power at a specific frequency by the power source 46b as needed, and supplies the generated plasma to the substrate 20 on the platform 41. On the substrate 20 exposed to the plasma, a silicon nitride film 30 is manufactured. The power sources 46a and 46b are not particularly limited, but specifically, for example, a high-frequency power source or the like can be used. Also, a plurality of power supplies can be used at the same time.

The vacuum pump 47 is connected to the processing chamber 40 through the exhaust line L4. By the vacuum pump 47, the decompression in the processing chamber 40 and the exhaust of the gas generated after the silicon nitride film 30 is manufactured can be performed.

The exhaust flow rate adjuster 48 is provided in the exhaust line L4, and the exhaust flow rate of the discharged gas can be adjusted by the vacuum pump 47. The exhaust gas flow regulator 48 is not particularly limited, but it may be controlled manually or it may be automatically controlled by an external control device.

The control unit 49 is connected to the heater 44a through the signal line C1, connected to the heater 44b through the signal line C2, connected to the power supply 46a through the signal line C3, connected to the power supply 46b through the signal line C4, and connected through the signal line C5 It is connected to the gas flow regulator 51, to the gas flow regulator 53 via the signal line C6, to the gas flow regulator 55 via the signal line C7, and to the exhaust flow regulator 48 via the signal line C8. The control unit 49 can control the heaters 44a and 44b, the power sources 46a and 46b, the gas flow regulators 51, 53, 55 and the exhaust flow regulator 48. The control unit 49 is connected to the computer 60.

The organic silane gas supply source 50 is connected to the shower head gas introduction part 45 provided in the processing chamber 40 through the gas supply line L1, and can supply the organic silane gas into the processing chamber 40. The organic silane gas supply source 50 is not particularly limited, but specifically, for example, a cylinder filled with organic silane gas may be used.

In addition, the organic silane gas is not particularly limited, but specifically, for example, dimethylaminosilane, paradimethylaminosilane, bisdimethylaminosilane, and diethylamine can be used. Amino silane, bis diethyl amine silane, bis diethyl amine silane, ethyl ethyl amine silane, gin ethyl amine silane, bis ethyl methyl amine silane, etc.

The first hydrogen reducing gas supply source 52 is through the first hydrogen reducing gas The supply line L2 and the gas supply line L1 are connected to the shower head gas introduction part 45 provided in the processing chamber 40 so that the hydrogen reducing gas can be supplied into the processing chamber 40. The first hydrogen reducing gas supply source 52 is not particularly limited, but specifically, for example, a cylinder filled with a hydrogen reducing gas supply source may be used.

The hydrogen reducing gas is not particularly limited, but specifically, for example, hydrogen gas (H ₂ ), ammonia gas (NH ₃ ), amines, hydrocarbons, etc. can be used.

The second hydrogen reducing gas supply source 54 is connected to the showerhead gas introduction part 45 provided in the processing chamber 40 through the second hydrogen reducing gas supply line L3 and the gas supply line L1, and can supply hydrogen reducing gas into the processing chamber 40 . In addition, by using the second hydrogen reducing gas supply source 54 in addition to the first hydrogen reducing gas supply source 52, a mixture of two types of hydrogen reducing gas can be used. The second hydrogen reducing gas supply source 54 is not particularly limited, but specifically, for example, a cylinder filled with a hydrogen reducing gas supply source may be used.

The gas flow regulator 51 is provided on the primary side of the junction of the gas supply line L1 and the first hydrogen reducing gas supply line L2, and can adjust the flow rate of the organosilane gas supplied from the organosilane gas supply source 50. In addition, the gas flow regulator 53 is provided in the first hydrogen reducing gas supply line L2 and can adjust the flow rate of the hydrogen reducing gas supplied from the first hydrogen reducing gas supply source 52. Moreover, the gas flow regulator 55 is provided in the second hydrogen reducing gas supply line L3, and can adjust the flow rate of the hydrogen reducing gas supplied from the second hydrogen reducing gas supply source 54. As gas flow regulators 51, 53, 55, although there are no special restrictions, but it can be controlled manually, or it can be automatically controlled by an external control device.

The insulating portion S is provided between the shower head gas introduction portion 45 and the processing chamber 40, and can electrically insulate the shower head gas introduction portion 45 and the processing chamber 40. In addition, the insulating portion S is also provided between the platform 41 and the processing chamber 40, and the platform 41 and the processing chamber 40 can be electrically insulated.

<Manufacturing method of silicon nitride film>

Next, a method of manufacturing the silicon nitride film of the present embodiment using the plasma CVD apparatus 100 described above (hereinafter, simply referred to as "manufacturing method") will be described.

The manufacturing method of this embodiment includes the steps of introducing the processing gas into the processing chamber 40 under a specific gas introduction condition, the step of exciting the processing gas plasma by applying high-frequency power, and using the plasma active species The plasma chemical vapor deposition method (plasma CVD method) of the step of manufacturing the silicon nitride film 30 on the substrate 20, and the method of manufacturing the silicon nitride film with required film characteristics. More specifically, in the above plasma CVD method, the organosilane gas is used as the raw material gas, and the film formation temperature is set to 250° C. or less, and 200 to 2000 volumes are used with respect to 1 volume of the organosilane gas. The processing gas added with hydrogen reducing gas at a flow rate adjusts the pressure in the processing chamber 40 to a range of 35 to 400 Pa, and adjusts the high-frequency power density applied to the shower head gas introduction part 45 provided in the processing chamber 40 to 0.2 To the range of 3.5W/cm ² . In addition, the evaluation method of the film characteristics will be described later.

Hereinafter, the manufacturing method according to this embodiment will be described in detail.

First, the substrate 20 is set on the stage 41 until the substrate 20 reaches a specific temperature, and is heated by the heater 44b. Although the upper limit of the substrate temperature is not particularly limited, it is preferably set to 250° C. or less from the background of requirements for low-temperature film formation.

Next, after the organic silane gas supplied from the organic silane gas supply source 50 is diluted with a large amount of hydrogen reducing gas supplied from the first hydrogen reducing gas supply source 52 and the second hydrogen reducing gas supply source 54, it is passed through the gas supply line L1 And supplied into the processing chamber 40. In addition, by performing the above-described dilution operation, in addition to the effect of reducing the amount of carbon atoms and hydrogen atoms taken into the film, the effect of not forming C=C bonds with low bonding energy in the film can also be obtained.

Here, regarding the relationship between the gas ratio of the hydrogen reducing gas relative to the volumetric flow rate of the organosilane gas and the membrane characteristics, the results reviewed by the inventors of the present application are shown in FIGS. 2 to 4 respectively.

Figure 2 is a graph showing the relationship between the gas ratio and the BHF etching rate. In the second graph, the horizontal axis represents the gas ratio of hydrogen reducing gas relative to 1 volume flow of organosilane gas. On the other hand, the vertical axis represents the BHF etching rate, and the smaller the value, the higher the hydrofluoric acid resistance.

As can be seen from FIG. 2, in the manufacturing method of this embodiment, when the above gas ratio is increased, the hydrofluoric acid resistance tends to increase. On the other hand, it can be seen that when the above gas ratio is reduced, the hydrofluoric acid resistance tends to decrease.

Figure 3 is a graph showing the relationship between the gas ratio and the rate of oxide film formation. In Fig. 3, the horizontal axis represents the gas ratio of the hydrogen reducing gas to the organic silane gas at a volume flow rate. On the other hand, the vertical axis represents the oxide film formation rate, and the smaller the value, the higher the moisture resistance. Also, in this In the silicon nitride film of the invention of the application, the formation of the oxide film is carried out from the surface side of the silicon nitride film, and through another experiment, it was confirmed that moisture does not penetrate to the depth of the film thickness of the generated oxide film Time. As can be seen from FIG. 3, in the manufacturing method of this embodiment, when the above gas ratio is increased, the moisture resistance tends to be improved. On the other hand, it can be seen that when the above gas ratio is reduced, the moisture resistance tends to decrease.

FIG. 4 is a graph showing the relationship between the gas ratio and the film formation speed of the silicon nitride film. In FIG. 4, the horizontal axis represents the gas ratio of hydrogen reducing gas relative to 1 volume flow of organosilane gas. On the other hand, the vertical axis represents the film formation speed of the silicon nitride film, and the larger the value, the faster the film formation speed of the silicon nitride film. As can be seen from FIG. 4, in the manufacturing method of this embodiment, when the gas ratio is increased, the film formation speed of the silicon nitride film tends to decrease. On the other hand, it can be seen that when the gas ratio is reduced, the film formation speed of the silicon nitride film tends to increase.

From the results of the above review, it can be seen that the higher the gas ratio of the hydrogen reducing gas relative to 1 volume flow of organosilane gas, the hydrofluoric acid resistance and moisture resistance will increase, but on the other hand, the film formation rate will decrease and the productivity Will fall. Therefore, in the manufacturing method of this embodiment, it is preferable to use a processing gas added with a hydrogen reducing gas at a volume flow rate of 200 to 2000 with respect to 1 volume flow rate of organosilane gas.

In addition, the adjustment of the above gas ratio is performed by adjusting the flow rate of each gas. Specifically, the flow rate of the organosilane gas is adjusted by the gas flow regulator 51, and the flow rate of the hydrogen reducing gas supplied by the first hydrogen reducing gas supply source 52 is adjusted by the gas flow regulator 53, and The flow rate of the hydrogen reducing gas supplied from the second hydrogen reducing gas supply source 54 is adjusted by the gas flow regulator 55.

On the other hand, in the processing chamber 40 to which the processing gas is supplied, the internal pressure is controlled by the vacuum pump 47. The pressure in the processing chamber 40 affects the residence time in the processing chamber 40, the plasma discharge state, and the conflict frequency after the raw material gas is decomposed in the plasma until it reacts on the substrate 20. As a result, It will affect the film characteristics of the manufactured silicon nitride film. Specifically, when the pressure is gradually lowered, the frequency of collisions will decrease and become insufficiently dissociated, and when it is further lowered, the state of the plasma becomes unstable and becomes insufficient. On the other hand, when gradually increasing, the average free stroke will become shorter and sufficient acceleration energy cannot be obtained, and when further increasing, the maintenance of the plasma state will become difficult.

Here, regarding the relationship between the pressure in the processing chamber 40 and the membrane characteristics, the results of the review by the inventor of the present application are shown in FIG. 5 and FIG. 6, respectively.

Figure 5 is a graph showing the relationship between pressure and BHF etching rate. In FIG. 5, the horizontal axis represents the pressure in the processing chamber 40. On the other hand, the vertical axis represents the BHF etching rate, and the smaller the value, the higher the hydrofluoric acid resistance. As can be seen from FIG. 5, in the manufacturing method of this embodiment, when the pressure in the processing chamber 40 is increased, the hydrofluoric acid resistance tends to decrease. On the other hand, it can be seen that when the pressure in the processing chamber 40 is reduced, the hydrofluoric acid resistance tends to increase.

Fig. 6 is a graph showing the relationship between pressure and oxide film formation rate. In FIG. 6, the horizontal axis represents the pressure in the processing chamber 40. another On the other hand, the vertical axis represents the oxide film formation rate, and the smaller the value, the higher the moisture resistance. As can be seen from FIG. 6, in the manufacturing method of this embodiment, when the pressure in the processing chamber 40 is increased, the moisture resistance tends to increase. On the other hand, it can be seen that when the pressure in the processing chamber 40 is reduced, the moisture resistance tends to decrease.

From the results of the above review, it can be seen that increasing the pressure in the processing chamber 40 increases the moisture resistance, but on the other hand, the hydrofluoric acid resistance decreases. Therefore, in the manufacturing method of this embodiment, it is preferable to adjust the pressure in the processing chamber 40 to the range of 35 to 400 Pa.

In addition, the linear velocity of the processing gas supplied into the processing chamber 40 is controlled by the gas flow regulators 51, 53, 55 and the pressure. Like the pressure in the processing chamber 40, the linear velocity of the processing gas also affects the residence time in the chamber after the decomposition of the raw material gas in the plasma and the reaction on the substrate, the plasma discharge state, and the conflict frequency.

Here, regarding the relationship between the linear velocity of the processing gas and the film characteristics, the examination results of the inventors of the present application are shown in FIG. 7 and FIG. 8, respectively.

Fig. 7 is a graph showing the relationship between linear velocity and BHF etching rate. In Figure 7, the horizontal axis represents the linear velocity of the processing gas. On the other hand, the vertical axis represents the BHF etching rate, and the smaller the value, the higher the hydrofluoric acid resistance. As can be seen from FIG. 7, in the manufacturing method of this embodiment, the linear velocity is around 1.0 cm/sec, the BHF etching rate is extremely small, and the hydrofluoric acid resistance becomes the best.

Fig. 8 is a graph showing the relationship between the linear velocity and the rate of oxide film formation. In Fig. 8, the horizontal axis represents the linear velocity of the processing gas. another On the one hand, the vertical axis represents the formation rate of the oxide film, and the smaller the value, the higher the moisture resistance. As can be seen from FIG. 8, in the manufacturing method of this embodiment, the linear velocity is around 3.0 cm/sec, the moisture resistance index obtains an extremely small value, and the moisture resistance becomes the best.

From the results of the above review, it can be seen that with regard to the linear velocity, if the speed is too fast or too slow, the generation efficiency of the active species in a moderately dissociated state will decrease, and a good film will not be obtained. Therefore, in the manufacturing method of the present embodiment, the linear velocity of the processing gas is preferably adjusted in the range of 0.3 to 5.0 cm/sec.

Next, a specific frequency power is applied to the shower head gas introduction part 45 by the power source 46a to excite the processing gas containing the organosilane gas and hydrogen reducing gas supplied from the gas supply line L1 to form a plasma.

In addition, in the manufacturing method of the present embodiment, although the frequency of applying electric power is not particularly limited, it can be appropriately selected from frequencies below 60 MHz. As an example, it is either 380 kHz or 13.56 MHz, or both at the same time, and it is used continuously or intermittently, and at least a part of the effects of this embodiment can be exerted. The applied power has an effect on the dissociation state of organosilane gas and hydrogen reducing gas.

Here, regarding the relationship between the high-frequency power density and the film characteristics, the examination results of the inventors of the present application are shown in FIG. 9 and FIG. 10, respectively.

FIG. 9 is a graph showing the relationship between high-frequency power density and BHF etching rate. In Fig. 9, the horizontal axis represents the high-frequency power density. On the other hand, the vertical axis represents the BHF etching rate, the smaller the value, the hydrofluoric acid The higher the endurance. As can be seen from FIG. 9, in the manufacturing method of this embodiment, when the high-frequency power density is increased, the hydrofluoric acid resistance tends to increase. On the other hand, it can be seen that when the high-frequency power density is reduced, the hydrofluoric acid resistance tends to decrease.

Fig. 10 is a graph showing the relationship between high-frequency power density and moisture resistance index. In Fig. 10, the horizontal axis represents power density. On the other hand, the vertical axis represents the oxide film formation rate, and the smaller the value, the higher the moisture resistance. As can be seen from FIG. 10, in the manufacturing method of this embodiment, when the high-frequency power density is increased, the moisture resistance tends to be improved. On the other hand, it can be seen that when the high-frequency power density is reduced, the moisture resistance tends to decrease.

From the results of the above review, it can be seen that as the high-frequency power density increases, the hydrofluoric acid resistance and moisture resistance will increase. However, on the other hand, in order to avoid unsuitable initial investment in high-frequency power sources, cost of power consumption, and durability of plasma generator components, the high-frequency power density is preferably 3.0 W/cm ² or less.

In addition, when the high-frequency power density is 0.4 W/cm ² or more, the raw materials are decomposed, and the film forming speed becomes 1 nm/min or more, which is preferable from the viewpoint of productivity.

When it is 0.2 W/cm ² or less, the raw material is difficult to decompose and it is difficult to form SiN, so it is not good in terms of productivity.

When 3.5W/cm ² , the substrate will be damaged depending on the device, which will deteriorate the device performance.

Therefore, in consideration of the above effects and unsuitable points, in the method for manufacturing a silicon nitride film of the present invention, the high-frequency power density is preferably adjusted in the range of 0.4 to 3.0 W/cm ² .

Further, the high frequency power density, based in the case of 452cm ² value of the high frequency applied to the electrode area, to be set at 0.2W / cm ² or more, the high-frequency power 90W or more, then to set, is set to be 3.5 W/cm ² or less may be 1583W or less.

Finally, by supplying the formed plasma to the substrate 20, the silicon nitride film 30 is manufactured on the substrate 20. After the silicon nitride film 30 is manufactured, gas is generated, but the generated gas is exhausted to the outside of the processing chamber 40 by the vacuum pump 47 through the exhaust line L4. In this way, a silicon nitride film having the film characteristics shown below can be manufactured.

<silicon nitride film>

The silicon nitride film obtained by the manufacturing method of the present embodiment described above, that is, using the plasma CVD apparatus 100, using the organic silane gas as the raw material gas, and setting the film forming temperature to 250° C. or less, relative to 1 volume flow of organosilane gas, using 200 to 2000 volume flow of processing gas added with hydrogen reducing gas, the pressure in the processing chamber 40 is adjusted to the range of 35 to 400 Pa, the electrode provided in the processing chamber 40 The silicon nitride film formed by adjusting the applied high-frequency power density in the range of 0.2 to 3.5 W/cm ² has the film characteristics shown in (a) to (c) below.

(a) The etching rate by hydrofluoric acid solution is below 10nm/min

(b) The formation rate of silicon oxide generated during exposure in a saturated water vapor environment of 208 kPa and 121°C, converted to a silicon oxide film of 2 nm/hr or less

(c) The internal stress in the film is in the range of -1000 to 1000 MPa.

As described above, according to the manufacturing method of this embodiment, the following configuration is adopted: using organic silane gas as the raw material gas, and producing silicon nitride by the plasma chemical vapor deposition method at a film forming temperature of 250°C or lower In the case of membranes, the processing gas added with hydrogen reducing gas at a volume flow rate of 200 to 2000 is used to adjust the pressure in the processing chamber 40 containing the substrate to a range of 35 to 400 Pa relative to 1 volume flow rate of organosilane gas. The high-frequency power density applied to the electrodes provided in the processing chamber 40 is adjusted to the range of 0.2 to 3.5 W/cm ² . By this, a silicon nitride film having high hydrofluoric acid resistance, high moisture resistance, and appropriate internal stress (ie, the film characteristics of (a) to (c) above) according to the device side can be produced.

In addition, according to the manufacturing method of this embodiment, it is preferable to adjust the linear velocity of the processing gas introduced into the processing chamber to the range of 0.3 to 5.0 cm/sec.

In the PCT results described below, the formation rate of the silicon oxide film of 2 nm/hr is the same as 0.2 g/m ² /day of the general moisture permeability evaluation method.

In addition, the technical scope of the present invention is not limited by the above-mentioned embodiment, and various changes can be added within the scope not departing from the gist of the present invention. For example, in the manufacturing method of the above embodiment, although the first hydrogen reducing gas supply source 52 and the second hydrogen reducing gas supply source 54 are used to describe an example of using two kinds of hydrogen reducing gas, it may be one Hydrogen reducing gas supply source.

[Example] <Manufacture of silicon nitride film>

As Examples 1 to 8, according to the method for manufacturing a silicon nitride film of the present invention, a silicon nitride film is manufactured on a silicon substrate controlled at 250°C or lower.

As the organic silane gas, para-dimethylaminosilane (3DMAS) or dimethylaminosilane (4DMAS) is used, and as the hydrogen reducing gas, hydrogen gas (H ₂ ) is used.

The frequency of the applied power is set to 380kHz or 13.56MHz.

The following Table 1 shows the manufacturing conditions such as the ratio of the flow rate of the hydrogen reducing gas to the flow rate of the organosilane gas, the linear velocity, the pressure in the processing chamber, and the power density in each example.

As Comparative Examples 1 and 2, silane gas was used to manufacture a silicon nitride film on a silicon substrate controlled at 200°C or 250°C under the most suitable conditions from the viewpoint of film characteristics.

The manufacturing conditions of Comparative Examples 1 and 2 are shown in Table 1 below.

As Comparative Example 3, silane gas was used to manufacture a silicon nitride film on a silicon substrate controlled at 350°C.

The manufacturing conditions of Comparative Example 3 are shown in Table 1 below.

As Comparative Examples 4 and 5, para-dimethylaminosilane (3DMAS) was used as the organic silane gas, and hydrogen (H ₂ ) was used as the hydrogen reducing gas. Nitrogen was produced on a silicon substrate controlled at 200°C Chemical silicon film.

<Evaluation method of membrane characteristics>

For the silicon nitride film manufactured under the above conditions, the film characteristics were evaluated. The following describes each evaluation method.

(Membrane composition)

The bonding state between the atoms of the silicon nitride film was evaluated by measuring the infrared absorption spectrum using FTIR (Fourier Transform Infrared Absorption Spectrophotometer, spectrum 400 manufactured by Perkinelmer). Specifically, the information of Si-N bond, Si-H bond, N-H bond, C=N bond, C=C bond, and Si-O bond is collected and analyzed.

(Moisture resistance)

The moisture resistance of the silicon nitride film was evaluated by FT-IR collecting information on Si-O bonds in the film before and after the pressure cooker test (PCT). The direct results obtained here represent the moisture absorption of the film. Here, when the moisture absorption is equivalent to the SiO ₂ film thickness of 1 nm, the silicon nitride film with a film thickness of 1 nm is converted from the SiO ₂ film to prevent the penetration of moisture. A film with less moisture absorption means higher moisture barrier.

In addition, the PCT conditions are set to 208 kPa and 121°C. This is equivalent to an accelerated test of 10,000 times under normal temperature and pressure.

(Hydrofluoric acid resistance)

The resistance of the silicon nitride film to hydrofluoric acid was evaluated using BHF (buffered hydrofluoric acid) solution. Specifically, the silicon nitride film is immersed in 16BHF (containing 20.8% NH ₄ HF ₂ aqueous solution, manufactured by Morita Chemical Industry Co., Ltd.), and after a certain period of time, it is immediately rinsed with pure water, dried by blowing nitrogen, etc., and used The following formula (1) evaluates the BHF etching rate R. In the following formula (1), d ₁ is the film thickness before the immersion treatment, d ₂ is the film thickness after the immersion treatment, t is the immersion time, and the film thickness is the spectroscopic ellipsometry described later. To measure.

R=(d ₁ -d ₂ )÷t…(1)

(Internal stress of membrane)

The internal stress of the silicon nitride film is measured by a thin-film stress measuring device (FLX-2320-R manufactured by Topeng Technology), which is derived from the bending change amount of the substrate as a measuring principle.

(Insulation)

The insulation of the silicon nitride film was evaluated by using a mercury probe (probe) type IV measuring device (SSM 495 manufactured by Solid State Measurement). Specifically, the leakage current value when the electric field strength is 1 MV/cm is evaluated.

(Refractive index and film thickness)

The refractive index and thickness of the silicon nitride film were measured using spectroscopic ellipsometry (GES 5E manufactured by SOPRA).

<Results of evaluation of membrane characteristics>

The following Table 2 shows the evaluation results of the film characteristics of Examples 1 to 8 and Comparative Examples 1 to 3.

In any of Examples 1 to 8, the etching rate by hydrofluoric acid solution The rates are all 10 nm/min or less, and it is understood that it has higher hydrofluoric acid resistance than Comparative Example 3. In addition, as shown in Comparative Examples 1 and 2, it can be seen that silane gas cannot obtain sufficient hydrofluoric acid resistance.

Similarly, during exposure to a saturated water vapor environment of 208 kPa and 121°C, the generation rate of silicon oxide generated is 2 nm/hr in terms of silicon oxide film. It can be seen that Examples 1 to 8 have the same value as Comparative Examples 1 to 3. The above high moisture resistance and moisture barrier.

In addition, as shown in Examples 1 and 4, it can be seen that a silicon nitride film having a characteristic of having extremely low internal stress can be manufactured. In addition, the internal stresses of Examples 1 to 8 respectively show a significantly different value ranging from negative 562 MPa to positive 728 MPa, and it can be seen that the silicon nitride film having high hydrofluoric acid resistance and high humidity resistance can be adjusted to Manufactured under specific internal stress.

In addition to Example 7, the leakage current value when an electric field strength of 1 MV/cm was applied was 1.0×10 ⁻⁶ A/cm ² or less, and it was found that it also had high insulation. In particular, regarding Example 1, although it is inferior to the comparative example in which silane gas is used as the raw material gas, it has excellent insulation of 7×10 ^-8 A/cm ² or less.

On the other hand, in Comparative Example 4, when the flow ratio of the organic silane gas and the hydrogen reducing gas in the manufacturing conditions of the silicon nitride film was set to 133, it was generated during exposure to a saturated water vapor environment of 208 kPa and 121°C. The generation rate of silicon oxide, converted to a silicon oxide film is 2.3nm/hr, it can be seen that moisture resistance and moisture barrier properties will decrease.

Also, in Comparative Example 5, when the linear velocity in the manufacturing conditions of the silicon nitride film was set to 0.2 cm/sec, it was exposed to saturation at 208 kPa and 121°C The formation rate of silicon oxide generated during the period in the water vapor environment is 29.2 nm/hr in terms of silicon oxide film. It can be seen that moisture resistance and moisture barrier properties will decrease.

[Industry availability]

The method for manufacturing a silicon nitride film and the silicon nitride film of the present invention include a mask material used in the manufacturing steps of semiconductor devices such as electronic devices and optical devices, a metal diffusion preventing film constituting the semiconductor device, an oxidation barrier film, The availability of passivation films, insulating films, etc. and their manufacturing methods.

20‧‧‧ substrate

30‧‧‧Silicon nitride film

40‧‧‧ processing room

41‧‧‧Platform

44a, 44b ‧‧‧ heater

45‧‧‧Lamp head gas introduction department

46a, 46b ‧‧‧ power supply

47‧‧‧Vacuum pump

48‧‧‧Exhaust flow regulator

49‧‧‧Control Department

50‧‧‧Organic silane gas supply source

51‧‧‧Gas flow regulator

52‧‧‧The first hydrogen reducing gas supply source

53‧‧‧Gas flow regulator

54‧‧‧Second hydrogen reducing gas supply source

55‧‧‧Gas flow regulator

60‧‧‧Computer

100‧‧‧Plasma CVD device

S‧‧‧Insulation Department

L1‧‧‧Gas supply line

L2‧‧‧The first hydrogen reducing gas supply line

L3‧‧‧Second hydrogen reducing gas supply line

L4‧‧‧Exhaust line

C1, C2, C3, C4, C5, C6, C7, C8

P1, P2‧‧‧Power wiring

Claims (7)

A method for manufacturing a silicon nitride film, which uses organic silane gas as a raw material gas, is manufactured by plasma chemical vapor deposition on a substrate at a temperature below 250°C, as shown in (a) to (c) below The method of the silicon nitride film of the film characteristic, wherein, relative to 1 volume flow of the aforementioned organosilane gas, 200 to 2000 volume flow of the processing gas added with hydrogen reducing gas is used to pressure the processing chamber that has contained the substrate Adjust within the range of 35 to 400 Pa, adjust the high-frequency power density applied to the electrode provided in the aforementioned processing chamber to within the range of 0.2 to 3.5 W/cm ² , (a) the etching rate by hydrofluoric acid solution It is below 10nm/min (b) during 208kPa, 121℃ saturated water vapor exposure period, the generation rate of silicon oxide is converted into silicon oxide film is below 2nm/hr (c) internal stress in the film Within the range of -1000 to 1000MPa, the aforementioned organosilane gas is an organosilane gas represented by the formula (R ¹ R ² N) _n SiH _4-n , where R ¹ and R ² are separate hydrocarbon groups, n Any number among 2, 3, and 4. The method for manufacturing a silicon nitride film as described in item 1 of the patent application scope, wherein the linear velocity of the processing gas introduced into the processing chamber is adjusted Round to the range of 0.3 to 5.0 cm/sec. The method for manufacturing a silicon nitride film as described in item 1 of the patent application range, wherein the hydrocarbon group is methyl or ethyl. The method for manufacturing a silicon nitride film as described in item 1 of the scope of the patent application, wherein the organic silane gas contains dimethylaminosilane, para-dimethylaminosilane, bisdimethylaminosilane, and Diethylamino silane, bis diethyl amine silane, bis diethyl amine silane, ethyl ethyl methyl amine silane, gin ethyl methyl amine silane, bis ethyl methyl amine silane More than one of them. The method for manufacturing a silicon nitride film according to any one of claims 1 to 4, wherein the hydrogen reducing gas contains hydrogen atoms. The method for manufacturing a silicon nitride film as described in item 5 of the patent application range, wherein the hydrogen reducing gas contains any one or more of ammonia, amine, and hydrocarbon. A silicon nitride film, which is a silicon nitride film having the film characteristics shown in the following (a) to (c), in which organic silane gas is used as a raw material gas in a plasma chemical vapor deposition method, While the film-forming temperature is set below 250°C, the processing gas added with hydrogen reducing gas at a volume flow rate of 200 to 2000 is used to adjust the pressure in the processing chamber to 35 to 400 Pa with respect to the aforementioned volume flow rate of the organosilane gas. Within the range, the high-frequency power density applied to the electrode provided in the aforementioned processing chamber is adjusted to the range of 0.2 to 3.5 W/cm ² and a film is formed, (a) the etching rate by the hydrofluoric acid solution is 10 nm/ Below min (b) During the exposure to saturated water vapor at 208kPa and 121°C, the generation rate of the generated silicon oxide is converted to a silicon oxide film below 2nm/hr. (c) The internal stress in the film is -1000 In the range of up to 1000MPa, the aforementioned organosilane gas is an organosilane gas represented by the formula (R ¹ R ² N) _n SiH _4-n , where R ¹ and R ² are separate hydrocarbon groups, and n is 2, 3 , Any number in 4.

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