JP2003218106A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form such a film that has superior adhesion to the base film of a substrate and has less failure on a boundary. <P>SOLUTION: When SiH<SB>2</SB>Cl<SB>2</SB>and NH<SB>3</SB>are used to form an Si<SB>3</SB>N<SB>4</SB>film, the SiH<SB>2</SB>Cl<SB>2</SB>and NH<SB>3</SB>excited by plasma or the like are allowed to flow alternately in a first step, and a thin Si<SB>3</SB>N<SB>4</SB>film is formed on a base film by ALD method. Then, the SiH<SB>2</SB>Cl<SB>2</SB>and NH<SB>3</SB>are allowed to flow at the same time in a second step, and an Si<SB>3</SB>N<SB>4</SB>film than that formed in the first step is formed on the film formed therein by CVD method in a second step. The temperature is set at 350-600°C in the first step and at 600-800°C in the second step. <P>COPYRIGHT: (C)2003,JPO

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, and more particularly to a semiconductor device having an improved interface between films formed on a substrate.

[0002]

2. Description of the Related Art As a method of manufacturing a semiconductor device, for example, a method of forming a film on a semiconductor substrate, a CVD (Chemical Vapor Depth) method is used.
osition) is known. This is a method of forming a film by using a surface reaction and a gas phase reaction. Conventionally, by using this CVD film forming method, a plurality of kinds of gases that contribute to film formation are simultaneously flown to form a film having a predetermined film thickness in one step. These gases form reaction intermediates by reacting in the gas phase. The reaction intermediate deposits on the base film on the substrate and reacts with the base film to form a film. The film thickness is controlled by time, and the film formation temperature is 600 to
It is a relatively high temperature of 800 ° C.

[0003]

However, in the conventional method in which a plurality of kinds of gases are simultaneously flowed to form a film in one step, the adhesion between the film formation and the substrate is poor, and defects in the interface occur. There was a problem that there were many.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for manufacturing a semiconductor device which has good adhesion at the interface between the film formation and the substrate and has few interface defects. is there.

[0005]

According to a first aspect of the present invention, when a film is formed on a substrate using a plurality of kinds of gases, a part of the plurality of kinds of gas that contributes to the film formation is used. And then another gas is alternately flowed, and this is repeated to form a film on the substrate, which contributes to the film formation on the first step and on the film formed in the first step. And a second step of forming a film by causing the plurality of kinds of gases to flow simultaneously at the same time. According to this, since the film formation is performed using the first step which has a good reaction with the substrate before the film formation using the second step, the film having good adhesion and few interface defects. Can be formed on the substrate.

In the above invention, the first step may be a step of forming a film on the substrate by repeating the flow of each of the plurality of kinds of gases contributing to the film formation. This also makes it possible to form a film having good adhesion and few interface defects on the substrate.

A second aspect of the invention is the second aspect of the first aspect of the invention.
The step is characterized in that the film is formed at a higher temperature than the first step. When the film formation in the second step is performed at a higher temperature than that in the first step, the film formation rate in the second step can be increased.

In the first and second inventions, the first
When a gas that needs to be excited among the plural kinds of gases is excited and flowed in the step, the film can be formed at a reaction temperature of a gas that does not need to be excited, so that the film can be formed at a low temperature.

If the film formed in the second step is thicker than the film formed in the first step, the ratio of the first step film formation time to the entire film formation time becomes small, so that the entire film formation is completed. A film having a predetermined film thickness can be obtained without significantly reducing the film speed. Therefore, it is possible to suppress a decrease in throughput while forming a film having good adhesion and few interface defects.

Further, when the ALD (Atomic Layer Deposition) method of forming one atomic layer at a time in the first step is used,
Since the reaction with the substrate becomes good, it is possible to form a film having better adhesion and less defects at the interface on the substrate.

Further, a plurality of kinds of gases are SiH ₂ Cl ₂ and N.
H ₃ and is preferably used when the film to be formed is a Si ₃ N ₄ film. In particular, when the Si ₃ N ₄ film is used as the dielectric film of the capacitive element, a film having excellent capacitance characteristics can be obtained.

Further, the gas excited in the first step is NH
_When it is ₃ , it becomes possible to form a film at a low temperature like SiH ₂ Cl ₂ which does not need to be excited.

Further, as a semiconductor manufacturing apparatus for carrying out the first and second inventions, a processing chamber for processing a substrate, a gas supply means for supplying a plurality of kinds of gases into the processing chamber, and a substrate in the processing chamber are heated. Of the gas in the first and second steps so that the plural kinds of gases are alternately and repeatedly flowed one by one in the first step, and then the plural kinds of gas are simultaneously flowed in the second step. A semiconductor manufacturing apparatus having a gas supply control means for controlling the flow method and a temperature control means for controlling the film formation temperature in each step can be provided. With a simple structure of controlling the gas flow and temperature, a film having good adhesion and few interface defects can be formed on the substrate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The method of manufacturing a semiconductor device according to the present invention is divided into two steps below to form a Si film on a base film on a substrate.
An embodiment applied to a method of forming a ₃ N ₄ film (hereinafter referred to as a two-step film forming method) will be described.

FIG. 1 is a timing chart of flowing a gas required for the two-step film forming method, and FIG. 2 shows the film forming temperature. FIG. 3 shows a cross-sectional view of a main part of a wafer formed according to the embodiment.

The two-step film forming method comprises a first step and a second step. The first step uses the ALD method for forming a film for each one atomic layer. SiH ₂ Cl
₂ (DCS: dichlorosilane) and NH ₃ are alternately flowed one by one to form one atomic layer, and by repeating this, the first Si ₃ N ₄ layer is formed on the base film of the substrate.
Form a film. The film forming temperature A is, for example, 350 to 600 ° C. In the first step, since two kinds of gases that contribute to film formation do not exist in the gas phase at the same time, the gases are adsorbed on the surface of the base and react with the base film. Therefore, the first film of Si ₃ N ₄ is formed that has good adhesion to the base film and has few defects at the interface with the base film.

In the second step following the first step, the CVD method of simultaneously supplying DCS and NH ₃ is used. The film forming temperature B is higher than the temperature in the first step and is, for example, 600 to 800 ° C. The above two kinds of gas undergo a gas phase reaction to form a reaction intermediate. The reaction intermediate causes a surface reaction with the first film to form a second film of Si ₃ N ₄ on the first film. Since the film forming temperature in the second step is set higher than the temperature in the first step, a thick film is formed in a shorter time than in the first step.

FIG. 3 shows the window obtained by this embodiment.
It is an important section sectional view of wafer W. Condensed on the board
A dielectric film is formed on the base film 11 serving as the lower electrode of the substrate.
Si ₃N_FourThe film 12 is formed by the method of the above embodiment.
Has been. This is a DRAM (Dynamic Randam Access)
Formed a dielectric film of the capacity used for the memory cell
It is a thing. The base film 11 has a surface as shown in the drawing.
Is a hemispherical surface ((HSG (Hemispherical Grain))
It has a rough shape. The base film 11 is uneven
To increase the surface area and increase the capacity.
ing.

Of the Si ₃ N ₄ film 12, the first film 12a is thinly formed by the ALD method, which has a slow film formation rate. Second film 1
2b is formed thick by using a CVD method with a high film formation rate.
In FIG. 3, the first film 12a and the second film 12b are hatched differently for the sake of convenience.
2a and the second film 12b are different only in the adhesiveness to the base film 11 and are not different in film quality. Therefore, the film 12 functions integrally as a dielectric film of the capacitor.

As described above, according to the two-step film forming method of the present embodiment, during the initial film forming of the first step,
Since the ALD film is formed so that it reacts well with the base film, a film having good adhesion to the base film and few interface defects can be formed on the base film.

In the second step after the ALD film formation, C
Since the VD film formation is performed and the film formation temperature is set higher than the ALD film formation temperature, the film formation rate in the second step can be further increased. Therefore, if the film formed in the second step is made thicker than the film formed in the first step, the ratio of the first step film formation time to the entire film formation time can be reduced, so that the entire film formation is completed. It is possible to obtain a dielectric film having a predetermined thickness without significantly reducing the film speed. As a result, it is possible to suppress a decrease in throughput while forming a film having good adhesion and few interface defects.

The two-step film forming method according to the above-described embodiment can be carried out regardless of the single wafer method or the batch method.

Next, a semiconductor manufacturing apparatus using each method for implementing the semiconductor device manufacturing method will be described.
FIG. 4 shows a single-wafer type semiconductor manufacturing apparatus, and FIG. 5 shows a batch-type semiconductor manufacturing apparatus.

FIG. 4 shows a schematic configuration diagram of a single-wafer type thin film forming apparatus utilizing ALD (hereinafter, simply referred to as a single-wafer type ALD apparatus). The single-wafer ALD apparatus includes a quartz reaction tube 21 for forming a film on a substrate W such as a silicon wafer, and a reaction tube 21.
Two gas supply systems 22 and 23 for supplying gas into the interior,
An exhaust system 25 for exhausting the inside of the reaction tube 21 and the reaction tubes 21 and 2
A quartz discharge tube 24, which is provided between one of the gas supply systems 22 and 23 of the system and which generates active species by exciting the gas with plasma, is provided.

One gas supply system 23 of the two systems
A gas that needs to be excited, for example, NH ₃ gas, is flowed to this. A gas that does not need to be excited in the other gas supply system 22,
For example, DCS is flown. Therefore, the other gas supply system 22
Are directly connected to the reaction tube 21 without the discharge tube 24.

Although not shown, an induction coil is wound around the discharge tube 24, and high frequency power is applied to the induction coil. When high frequency energy is applied to the gas passing through the discharge tube 24 by this application, the gas is turned into plasma and active species are generated. The active species are carried from the discharge tube 24 into the reaction tube 21. The exhaust system 25 includes the reaction tube 21.
Is provided on the gas downstream side opposite to the gas supply systems 22 and 23. The exhaust system 25 is connected to an exhaust pump 26 so that the inside of the reaction tube 21 can be evacuated.

A region in the discharge tube 24 where plasma is generated is called a plasma generation region 28. Further, a region in the reaction tube 21 where the substrate W is placed is referred to as a substrate region 27. In addition, from the above-mentioned discharge tube 24, induction coil, high-frequency power source,
Gas is plasma-excited outside the substrate region 27 to cause the substrate region 27
A remote plasma unit to be supplied inside is constructed.

FIG. 5 is a schematic block diagram of a batch type vertical thin film forming apparatus utilizing ALD (hereinafter, simply referred to as vertical type ALD apparatus). 5A is a vertical sectional view, and FIG. 5B is a horizontal sectional view. A reaction tube 32 for processing a substrate is provided inside the heater 31. The lower end of the reaction tube 32 is hermetically closed by a seal cap 35, and a boat 39 is erected on the seal cap 35 and inserted into the reaction tube 32. Substrates W to be batch processed are loaded on the boat 39 in a horizontal posture in multiple stages in the tube axis direction. The heater 31 heats the substrate W in the reaction tube 32 to a predetermined temperature.

A plurality of gas supply systems for supplying a plurality of kinds of gases are provided in the reaction tube 32. Here, the one gas supply system 38 is connected via the remote plasma unit 37.
The other gas supply system 41 is the remote plasma unit 3
Each of the reaction tubes 32 is connected to one side of the reaction tube 32 without passing through 7. Therefore, there are two types of gas supplied to the plurality of substrates W in the reaction tube 32: a gas supplied as active species by plasma excitation and a gas supplied without being excited by plasma. An exhaust system 40 is provided on the other side of the reaction tube 32.

The remote plasma unit 37 is connected to the nozzle 30 standing upright along the boat 39 in the reaction tube 32. The nozzle 30 is provided with a large number of outlet holes 34 along the axial direction of the nozzle so as to face the large number of substrates stacked in multiple stages.

In order to uniformly supply the excited gas or the non-excited gas from the gas upstream substrate W to the gas downstream substrate W, the outlet hole 34 has a small gas upstream outlet hole diameter and a gas downstream outlet. The conductance is changed by increasing the hole diameter so that the gas is blown out evenly in the upstream and the downstream.

Also, two kinds of gas flow methods and the substrate W are used.
A control system for controlling the processing temperature is provided. The control system is
In the first step, two types of gases are alternately and repeatedly flowed, and then, in the second step, the two types of gases are simultaneously flowed, and the gas flow method in the first step and the second step is controlled. It has a gas supply control means 43 and a temperature control means 42 for controlling the film formation temperature by heating the heater in each step. It should be noted that although a description of such a control system is omitted in FIG. 4, it has a control system similar to that of FIG.

Since the film forming method using the apparatus shown in FIGS. 4 and 5 is common, the Si ₃ N ₄ film is formed by using the batch type semiconductor manufacturing apparatus shown in FIG. The method will be described.

First, the substrate W on which a film is to be formed is placed on the boat 39.
And is loaded into the reaction tube 32 (hereinafter simply referred to as the furnace). Next, a Si ₃ N ₄ film is formed on the substrate by the first step. The first step uses the ALD method for forming a film for each one atomic layer. Either one of DCS and NH ₃ is flowed. Here, first, DCS is supplied from the gas supply system 41. The furnace temperature is, for example, 350 to 600 ° C.
Is. The pressure in the furnace is 266-931 Pa and is 6-
Supply for 20 seconds. Only DCS is flowing into the furnace, and NH ₃ is not present. Therefore, the gas phase reaction does not occur, and the DCS surface reacts with the base film on the substrate W.

Next, NH ₃ is supplied from the gas supply system 38. Since NH ₃ has a higher reaction temperature than DCS, it does not react at the furnace temperature. Therefore, it is excited by the remote plasma unit 37 to form active species and then flowed. As a result, the temperature inside the furnace is 350 to 60, which is the same as DCS.
0 ° C is sufficient. In the case of NH ₃ , the pressure in the furnace is 40-60 Pa
For 5 to 120 seconds. DCS on the base film and NH _{3 which} is excited by plasma and becomes an active species undergoes a surface reaction to form a Si ₃ N ₄ film.

The step of alternately flowing DCS and NH ₃ is defined as one cycle. By repeating this cycle for one cycle or more, the film of Si ₃ N ₄ is formed, and the cycle is repeated until the film thickness covers the entire surface of the base film, specifically, 0.1 nm or more. According to the first step, the first film has good adhesion to the base film 11 and has few interface defects.
A film is formed.

In the second step following the first step, the CVD method of simultaneously supplying DCS and NH ₃ is used. DCS is supplied without excitation and NH ₃ is also supplied without excitation. DCS flow rate is 80 sccm, NH ₃ flow rate is 8
It is 00 sccm. The temperature in the furnace is higher than the temperature in the first step, for example, 600 to 800 ° C., here 7
The temperature is 60 ° C. Furnace pressure is 20 Pa, film formation rate is 1.5
~ 2.0 nm. The above two kinds of gas undergo a gas phase reaction to form a reaction intermediate. This reaction intermediate is the first
By causing a surface reaction with the film, a second film of Si ₃ N ₄ is continuously formed on the first film.

As described above, the ALD method is used in which the two types of gases contributing to film formation are alternately flowed in the first step using the vertical ALD apparatus. In this ALD method, since two kinds of gases that contribute to film formation do not exist in the vapor phase at the same time, the gas is adsorbed on the surface of the base and reacts with the base film. Therefore, a film having good adhesion to the base film can be obtained, and the defects at the interface are reduced as compared with the direct film formation by the CVD method.

In the first step, the NH ₃ gas that needs to be excited among the plurality of kinds of gases is excited to flow, so that film formation can be performed at a reaction temperature of DCS gas that does not require excitation. The film can be formed at a low temperature of 600 ° C.

Further, the film forming method by the ALD method has a lower film forming speed than the CVD film forming. But in the second step,
Performs conventional CVD film formation with high film formation speed
Since the process is performed at a temperature higher than the step, the throughput can be increased as compared with the film formation by only the ALD method. Further, in the second step, two kinds of gas may be supplied simultaneously, so that it is easier to create a control program for the control system than in the first step.

In addition, plural kinds of gases are SiH ₂ Cl ₂ and N.
Is H _3, film formation when a Si ₃ N ₄ film, in particular, using an Si ₃ N ₄ film is deposited on the thus HSG treated base film 11 as a capacitor dielectric film At this time, if the adhesion is good and the number of defects on the interface is small, a large capacity can be obtained, which is a great advantage.

Although the ALD method utilizing the reaction with the underlying film is used in the first step in the above-mentioned embodiment,
The method used in the first step is not limited to this. In general, in order to improve the adhesion with the underlying film, the process parameters (reactor temperature, furnace pressure, gas flow rate, etc.) with good adhesion were found from the experimental results, although the deposition rate was slow in the initial growth process. The film may be formed based on the found parameters.

Although the case where the reaction furnaces (chambers) for performing the first step and the second step are the same has been described, the reaction furnaces may be clustered and performed separately. The occupied area can be reduced when the first step and the second step are performed in a single chamber, but when the first step and the second step are shared among a plurality of chambers by clustering, the chamber alone can be used. Since one type of process is performed in, the structure of the chamber is simplified.

Further, in the embodiment, when the film is formed on the substrate by using the two kinds of gas, the first step is performed by alternately flowing the two kinds of gases contributing to the film formation one by one. By doing so, the film was formed on the substrate,
When film formation is performed on a substrate using multiple types of gas, some of the multiple types of gas that contribute to film formation are made to flow, then other types of gas are made to flow alternately The film may be formed on the substrate by repeating.

[0045]

According to the present invention, it is possible to form a film having good adhesion at the interface between the film formation and the substrate and having few defects at the interface.

[Brief description of drawings]

FIG. 1 is a timing chart of flowing a gas required for a two-step film forming method according to an embodiment.

FIG. 2 shows a deposition temperature of a two-step deposition method according to an embodiment.

FIG. 3 shows a cross-sectional view of a main part of a wafer formed according to an embodiment.

FIG. 4 is a schematic configuration diagram of a single-wafer type semiconductor manufacturing apparatus for carrying out the semiconductor device manufacturing method of the present invention.

FIG. 5 shows a schematic configuration diagram of a batch-type semiconductor manufacturing apparatus for carrying out the semiconductor device manufacturing method of the present invention,
(A) is a longitudinal sectional view and (b) is a lateral sectional view.

[Explanation of symbols]

21 Reaction tube 22, 23 gas supply system 24 discharge tubes W board

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Claims (2)

[Claims] 1. When forming a film on a substrate by using a plurality of kinds of gases, some kinds of gases among the plurality of kinds of gases contributing to the film formation are caused to flow, and then another kind of gas is supplied. Alternately flow, and by repeating this, a first step of forming a film on the substrate, and simultaneously flowing the plurality of kinds of gases contributing to the film formation on the film formed in the first step. And a second step of forming a film by the method of manufacturing a semiconductor device. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the film formation is performed at a higher temperature in the second step than in the first step.