JP2002176053A - Manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a semiconductor device which comprises a nitride film and is high in any of an integration degree, a reliability and a performance, at low cost. SOLUTION: In a semiconductor device, a nitride film is formed of first and second materials not containing hydrogen. Therefore, a even though the nitride film is formed, the hydrogen is not diffused in a base body. As the activated first material is transferred on the base body by a diffusion or the pressure difference, the kinetic energy of the first material transferred on the base body is low and damage to the base body is little. Moreover, as the second neutral material is also transferred on the base body, the charge-up of the base body is little.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device including a nitride film.

[0002]

2. Description of the Related Art For example, when manufacturing a MOS transistor on a silicon substrate, it is necessary to form a gate oxide film as a silicon oxide film on the surface of the silicon substrate. Also, when manufacturing a thin film transistor, it is necessary to form a gate oxide film, which is a silicon oxide film, on the surface of a silicon layer provided on an insulating substrate. Therefore, the silicon oxide film is required to have a high dielectric breakdown voltage and a long-term reliability, and the silicon oxide film plays a role in the reliability of the semiconductor device.

With the increase in the degree of integration of semiconductor devices, the thickness of the gate oxide film of a MOS transistor is also becoming thinner, and the thickness of the gate oxide film in a MOS transistor having a gate length of 0.1 μm is expected to be about 2 nm. . The method of forming a silicon oxide film on the surface of a silicon substrate or the like can be roughly classified into a dry oxidation method of supplying sufficiently dried O ₂ to a heated silicon substrate or the like, and a method in which a high-temperature carrier gas containing water vapor is applied to silicon. There is a humidifying oxidation method for supplying to a substrate or the like. In general, a silicon oxide film formed by a humidifying oxidation method is more reliable than a dry oxidation method.

In recent CMOS transistors, the voltage has been reduced in order to reduce the power consumption.
There is a demand for sufficiently low and symmetrical threshold voltages for the PMOS transistor and the NMOS transistor. In order to cope with such a demand, in a PMOS transistor, a gate electrode having a polycrystalline silicon film containing a p-type impurity is used instead of a conventional gate electrode having a polycrystalline silicon film containing an n-type impurity. It has become.

However, since boron, which is generally used as a p-type impurity, has a large diffusion coefficient, it is diffused from the gate electrode by various heat treatments in a process after forming the gate electrode, passes through the gate oxide film, and forms a silicon substrate. To easily change the threshold voltage of the PMOS transistor. This phenomenon appears more conspicuously when the gate oxide film is further thinned to reduce the voltage.

The diffusion of boron into a silicon substrate as described above
Of the threshold voltage of the PMOS transistor caused by the
Control the silicon nitride film
A method of laminating on a passivated film has been attempted, and boron diffusion
The effect of suppressing the occurrence has also been confirmed. Form silicon nitride film
As a first method of forming, for example, SiH_FourAnd NH _Three
By a thermal CVD method using a mixed gas of
The method of forming a con nitride film is described in the document "Ultra Thin (<20
Å) CVD Si_ThreeN_FourGate Dielectric for Deep-Sub-Micron
CMOS Devices ", S.C.Song, et al., 1998, IEDM
It is listed.

As a second method for forming a silicon nitride film, an ECR plasma CVD apparatus or a parallel plate type C
A silicon-based material gas such as SiCl ₄ and Si ₂ Cl ₆ and a nitrogen-based material gas such as N ₂ , NO, N ₂ O and NO ₂ are supplied to a VD device or the like, and a microwave of 2.45 GHz, for example, is supplied as a material gas A method of forming a silicon nitride film by irradiating the silicon nitride film has been considered.

[0008]

However, in the above-mentioned first method for forming a silicon nitride film, N ₂ which is easy to handle but difficult to thermally decompose cannot be used as a nitrogen-based material gas. Silicon nitride film and PMO
It is difficult to form an S transistor at low cost.

Further, SiH ₄ which is a silicon-based material gas is used.
And because it contains hydrogen both the NH ₃ is a nitrogen-based material gas, hydrogen diffuses into the underlying silicon oxide film by heat-treating these materials gases, the gate insulating film of the reliability Degradation etc. occur, and a highly reliable PMOS
It is difficult to manufacture a transistor.

On the other hand, in the above-described second method for forming a silicon nitride film, since a high temperature is not required for forming a silicon nitride film, re-diffusion of impurities in a silicon substrate or the like does not occur. In addition, since the silicon nitride film is formed by irradiation with electromagnetic waves, N ₂ , which is difficult to thermally decompose but easy to handle, can be used as a material gas. Further, since neither the silicon-based material gas nor the nitrogen-based material gas contains hydrogen, even if a silicon nitride film is formed, hydrogen does not diffuse into the underlying silicon oxide film.

However, according to the second method, the material converted into plasma is accelerated by an electric field or a magnetic field and is transferred to the vicinity of the silicon substrate or the like. At a high cost, the lower silicon oxide film is often damaged by the impact of the material, and the silicon oxide film is often charged up. For this reason, it is difficult to manufacture a high performance PMOS transistor by the second method.

Accordingly, the present invention provides a method of manufacturing a semiconductor device which includes a nitride film and which can manufacture a semiconductor device having a high degree of integration, reliability and performance at a low cost. The purpose is.

[0013]

In the method of manufacturing a semiconductor device according to the present invention, since the first material containing nitrogen is activated by electric discharge, a high temperature is required to activate the first material. It is not necessary, and it is possible to prevent re-diffusion of impurities in the substrate when forming the nitride film. Also, since the first and second materials do not contain hydrogen,
Even if a nitride film is formed, hydrogen does not diffuse into the substrate. Also,
Since the activated first material is transferred onto the substrate by diffusion or pressure difference, the kinetic energy of the first material transferred onto the substrate is low, and the impact force of the first material on the substrate is weak, Less damage to the substrate.

Further, since the activated first material is transferred onto the substrate by diffusion or pressure difference, the ionized first material is not transferred onto the substrate preferentially.
The neutral first material is also transferred onto the substrate, so that the substrate is less charged up. In addition, since the first material containing nitrogen is activated by electric discharge, nitrogen that is hardly activated by heat treatment can be activated to react easily with the second material, which facilitates handling. Nitrogen can be used as the first material.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first and second embodiments of the present invention applied to the manufacture of a PMOS transistor will be described with reference to FIGS. 1 and 2 show a nitride film forming apparatus and an oxide film forming apparatus suitable for implementing the first embodiment, respectively. The oxide film forming apparatus 11 shown in FIG. 2 is of a batch type, and a reaction chamber 12 is provided in the forming apparatus 11.

A gas introduction section 13 is provided at the top of the reaction chamber 12, and a quartz pipe 14 connected to the gas introduction section 13 is provided outside the reaction chamber 12. A heater 15 is provided outside the reaction chamber 12 and the quartz pipe 14, and the semiconductor substrate 16 introduced into the reaction chamber 12 and the gas passing through the quartz pipe 14 toward the gas introduction unit 13 are heated. Table 15
Heated by An elevating mechanism 21 is provided below the reaction chamber 12.
The mounting table 22 of the semiconductor substrate 16 is moved up and down by the elevating mechanism 21.

An apparatus 23 for forming a nitride film shown in FIG.
Is a single wafer type, and a reaction chamber 24 is provided in a forming apparatus 23. A mounting table 25 for the semiconductor substrate 16 is provided in the reaction chamber 24, and a heater 26 for heating the semiconductor substrate 16 is provided below the mounting table 25. Reaction chamber 2
4 is provided with a gas discharge part 31 on the side thereof.
4 is provided with a plasma generation chamber 32 above.

A microwave waveguide 33 is connected to the top of the plasma generation chamber 32, and the microwave waveguide 33 is provided with a magnetron 34. The microwave generated by the magnetron 34 is supplied to the plasma generation chamber 32 via the microwave waveguide 33. Plasma generation chamber 32
A gas introduction unit 35 is provided at the top of the chamber, and a gas introduction unit 36 is provided between the plasma generation chamber 32 and the reaction chamber 24.

FIGS. 3 and 4 show the first embodiment.
In the first embodiment, as shown in FIG. 3A, a LOC is added to a semiconductor substrate 16 which is an N-type silicon wafer having a diameter of 8 inches and manufactured by the CZ method and doped with phosphorus.
An element isolation region 41 having an OS structure is formed. In addition,
The element isolation region 41 may have a trench structure, or may be a combination of a LOCOS structure and a trench structure.

Thereafter, a well (not shown) is formed.
Ion implantation and channel stopper (not shown)
For adjusting the threshold voltage and ion implantation for
Perform each on-injection. And NH_FourOH / H_TwoO_Twowater
Wash with solution and add HCl / H _TwoO_TwoWhen washed with aqueous solution
Attached to the semiconductor substrate 16 by the RCA cleaning.
Removes fine particles and metal impurities, and furthermore, hydrofluoric acid aqueous solution
The surface of the semiconductor substrate 16 is cleaned with a liquid and pure water.

Next, the oxide film forming apparatus 11 shown in FIG.
The semiconductor substrate 16 is carried in from a door (not shown), and the semiconductor substrate 16 is mounted on the mounting table 22. Then, while introducing N ₂ into the reaction chamber 12 through the quartz pipe 14 and the gas introduction unit 13, the mounting table 22 is raised by the elevating mechanism 21, and the mounting table 22 is introduced into the reaction chamber 12.

Thereafter, the introduction of N ₂ is stopped and the heater 15
By heating the semiconductor substrate 16 and introducing dry O ₂ into the reaction chamber 12 through the quartz pipe 14 and the gas introduction part 13, the oxide film 42, which is a silicon oxide film having a thickness of 1 nm, is formed on the semiconductor substrate 16. It is formed on the surface of the element active region. The conditions for forming the oxide film 42 are shown below. Note that humidified O ₂ may be introduced instead of dry O ₂ .

[Conditions for Forming Oxide Film] Dry O ₂ flow rate: 10 SLM Semiconductor substrate temperature: 800 ° C.

Next, the nitride film forming apparatus 11 shown in FIG.
The semiconductor substrate 16 is carried in through a door (not shown), and the semiconductor substrate 16 is mounted on the mounting table 25. Then, N ₂ and He, which are nitrogen-based material gases containing no hydrogen, are introduced from the gas introduction unit 35 into the plasma generation chamber 32,
SiC which is a silicon-based material gas containing no hydrogen
l ₄ is introduced from the gas introduction part 36 to an intermediate point between the plasma generation chamber 32 and the reaction chamber 24. And SiCl ₄ and N ₂
At the same time, microwave power is supplied to the magnetron 34, and the microwave generated by the magnetron 34 is introduced into the plasma generation chamber 32 via the microwave waveguide 33.

[0025] As a result, discharge plasma generating chamber 32 is caused, N ₂ plasma is generated N ₂ is ionized, excited nitrogen is produced by N ₂ plasma. This excited nitrogen and S
and LiCl ₄ is, by diffusion or pressure difference rather than accelerated by the electric field and the magnetic field is transferred into the reaction chamber 24. Then, on the semiconductor substrate 16 heated by the heater 26, Si
Cl ₄ is decomposed to generate excited silicon, and the excited silicon and the excited nitrogen react to deposit a nitride film 43 as a silicon nitride film on the semiconductor substrate 16. The conditions for forming the nitride film 43 are shown below.

[Conditions for forming nitride film] Microwave power: 1 kW Microwave frequency: 2.45 GHz N ₂ flow rate: 5.0 SLM SiCl ₄ flow rate: 10.0 SLM He flow rate: 100 SLM Atmospheric pressure: 0.16 Pa Semiconductor substrate temperature: 700 ° C

Up to this point, a gate insulating film in which the nitride film 43 is laminated on the oxide film 42 is formed. As is clear from the above description, the action of the plasma is basically only the excitation of nitrogen. The decomposition of the silicon-based material gas, the excitation of silicon, and the deposition of the nitride film 43 by the reaction between nitrogen and silicon are performed by thermal CVD. Done by law. Therefore, damage of the oxide film 42 due to the impact of the ionized silicon is small.
Further, since the deposition rate of the nitride film 43 is lower than that of the plasma CVD method, it is suitable for forming a thin film such as a gate insulating film. Incidentally, He has been introduced to promote ease in to ionization of N ₂ discharge in N _2, A instead of He
r or the like may be introduced.

Next, the semiconductor substrate 16 is unloaded from the forming apparatus 23, and the semiconductor substrate 16 is loaded into a conventionally known CVD apparatus (not shown). Thereafter, as shown in FIG. 3B, a conductive film 44 which is a polycrystalline Si film containing no impurities and a conductive film 45 which is a WSi film are formed by CVD.
Are sequentially deposited by a method. Then, the conductive films 45 and 44, the nitride film 43, and the oxide film 42 are processed into a gate electrode pattern by photolithography and dry etching.

Next, a p-type impurity such as boron is ion-implanted into the semiconductor substrate 16 using the conductive films 45 and 44 and the element isolation region 41 as a mask, so that p-type impurities are
At the same time as introducing a type impurity, a low concentration diffusion layer 46 is formed in the semiconductor substrate 16 as shown in FIG. Thus far, a gate electrode having a polycide structure in which the conductive film 45 is stacked on the conductive film 44 is formed. afterwards,
By depositing an insulating film on the entire surface and etching back the entire surface of the insulating film by anisotropic dry etching, FIG.
As shown in (a), a side wall spacer 51 made of this insulating film is formed on the side surfaces of the conductive films 44 and 45 and the like.

Next, the side wall spacer 51, the conductive films 45,
4 and the element isolation region 41 as a mask,
As shown in FIG. 4B, a p-type impurity such as boron is ion-implanted into the
2 are formed in the semiconductor substrate 16. Then, impurities in the conductive film 44 and the diffusion layers 46 and 52 are activated by the heat treatment. Up to this point, the L composed of the diffusion layers 46 and 52
A source / drain region having a DD structure is formed.

Next, as shown in FIG. 4C, an insulating film 53 is deposited on the entire surface by the CVD method, and a connection hole 54 reaching the diffusion layer 52 and the conductive film 45 is formed in the insulating film 53. I do.
Then, a conductive film for wiring is formed on the entire surface of the insulating film 53 including the inside of the connection hole 54 by a sputtering method, and the wiring 55 is formed by patterning the conductive film.

The PM manufactured in the first embodiment as described above
In the gate insulating film of the OS transistor, a nitride film 43 is stacked on the oxide film. For this reason, boron in the conductive film 44 forming the gate electrode becomes conductive film 4 by various heat treatments in a process after forming the gate electrode.
4 and passes through the gate insulating film to form the semiconductor substrate 16.
, The fluctuation of the threshold voltage of the PMOS transistor is suppressed.

Moreover, in the first embodiment, when the nitride film 43 is formed, SiCl ₄ as a silicon-based material gas is used.
And N ₂ as a nitrogen-based material gas, and none of these material gases contains hydrogen. Therefore, even if these material gases are heat-treated, the underlying oxide film 4
Hydrogen is not diffused into the gate electrode 2 and a decrease in the reliability of the gate insulating film is prevented, so that a highly reliable PMOS transistor is manufactured.

FIG. 5 shows an oxide film forming apparatus used in the second embodiment. This forming apparatus 61 is a single wafer type, and a reaction chamber 62 is provided in the forming apparatus 61. A mounting table 63 for the semiconductor substrate 16 is provided in the reaction chamber 62, and the mounting table 63 is surrounded by a heater 64. A gas inlet 65 and a gas outlet 66 are provided on one side and the other side of the reaction chamber 62, respectively.

In the second embodiment, after the steps up to the formation of the element isolation region 41 are performed in the same manner as in the first embodiment, a door (not shown) is inserted into the oxide film forming apparatus 61 shown in FIG. Then, the semiconductor substrate 16 is carried in, and the semiconductor substrate 16 is mounted on the mounting table 63. Then, the semiconductor substrate 16 is heated by the heater 64, and the reaction chamber 6 is
By introducing O ₂ into the substrate 2, an oxide film 42, which is a silicon oxide film having a thickness of 1 nm, is formed on the surface of the active region of the semiconductor substrate 16. The conditions for forming the oxide film 42 are shown below. Thereafter, the same steps as those in the first embodiment are performed again.

[Conditions for Forming Oxide Film] Flow rate of O ₂ : 10 SLM Temperature of semiconductor substrate: 800 ° C.

In the first and second embodiments described above, the PMO having a gate insulating film having a laminated structure including the nitride film 43 is used.
The invention of the present application is applied to the manufacture of an S transistor. For example, the invention of the present application is also applied to the manufacture of a PMOS transistor in which a sidewall spacer 51 is formed of a nitride film, and the manufacture of a semiconductor device other than a PMOS transistor. can do.

[0038]

According to the method of manufacturing a semiconductor device according to the present invention, it is possible to prevent the re-diffusion of impurities in the substrate during the formation of the nitride film, so that a semiconductor device having a high degree of integration can be manufactured. Further, since hydrogen does not diffuse into the base even when the nitride film is formed, a highly reliable semiconductor device can be manufactured. Further, a semiconductor device having high performance can be manufactured because damage to the base and charge-up are small. Further, since nitrogen that is easy to handle can be used as the first material, a semiconductor device can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a nitride film forming apparatus suitable for implementing a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of an oxide film forming apparatus suitable for implementing the first embodiment of the present invention.

FIG. 3 is a side sectional view sequentially showing a first half of a process according to the first embodiment of the present invention;

FIG. 4 is a side sectional view sequentially showing the latter half of the steps in the first embodiment of the present invention.

FIG. 5 is a conceptual diagram of an oxide film forming apparatus suitable for implementing a second embodiment of the present invention.

[Explanation of symbols]

16: semiconductor substrate (base), 42: oxide film (base), 4
3 ... nitride film

Continued on the front page F term (reference) 4K030 AA03 AA06 AA18 BA38 BA40 CA04 CA12 DA02 DA03 FA01 HA01 JA05 LA02 LA15 5F040 DA01 DC01 EC01 EC04 EC07 EC13 ED01 ED05 EF02 EK01 EK02 EK05 FA03 FB02 5F045 AA03 AC17 AC12 AE15 AF03 BB16 DC51 DP03 DP19 DQ05 EH18 5F058 BA20 BD01 BD04 BD10 BF07 BF24 BF30 BF55 BF62 BJ01

Claims (2)

[Claims] 1. A step of activating a first material containing nitrogen and no hydrogen by discharge, and transferring the activated first material onto a substrate by diffusion or pressure difference. A method of manufacturing a semiconductor device, comprising: reacting the first material on the base with a second material not containing hydrogen to form a nitride film on the base. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a silicon nitride film is formed as said nitride film using said second material containing silicon.