JP2003045811A - Method for manufacturing semiconductor device and wafer processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device and a wafer processing system for forming silicon germanium film excellent in film thickness and germanium ratio in-plane and plane-to-plane uniformity by a low-pressure CVD method by using mono-silane and mono-germanium. SOLUTION: The method for manufacturing a semiconductor device and the wafer processing system comprises the steps of: applying gas including mono-silane and mono-germanium to the surface of the wafer 4 loaded on boats 3 in a reactor furnace 11 heated with a heater 6; depositing polysilicon germanium film on the surface of the wafer 4; and feeding the mono-germanium into a reactor 11 through a plurality of nozzles 12a to 12e having different lengths in the reactor 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method and a substrate processing apparatus, and more particularly to low pressure CVD.
The present invention relates to a method for manufacturing a semiconductor device and a substrate processing apparatus for forming a film of poly or amorphous silicon germanium by a chemical vapor deposition method.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor device such as an IC and an LSI, a low pressure CVD method (chemical vapor deposition method) is used.
According to this, a thin film is formed on a substrate. As one of such film forming processes, low pressure CVD
It has been tried to form a polysilicon germanium film on the gate electrode portion of a MOS transistor by the method.

Conventionally, silicon has been used for the gate electrode portion of a MOS transistor, but with the recent thinning of the gate insulating film, depletion of the gate when a bias voltage is applied to the gate and heat treatment process are performed. Penetration of the dopant from the electrode to the channel portion has been a major problem that deteriorates device characteristics. It has been found that the above problems are greatly improved by using silicon germanium instead of silicon.

[0004]

When silicon germanium is used instead of silicon, the same film forming conditions (50
The film formation rate at 0 ° C. increases about 6 times when the germanium ratio is 20% and about 14 times when the germanium ratio is 30% as compared with the case of silicon. Along with that, the consumption of the reaction gas when passing through the reaction furnace also increases, and the increase rate of the consumption is remarkable because germanium has a mass per cm ^{3 of} about 2.3 times larger than that of silicon. . When monogermane, which is the source gas of germanium, is fed into the furnace from the lower part of the reaction furnace with one nozzle,
Due to the consumption of monogermane, the gas concentration is significantly different between the upstream side and the downstream side in the reaction furnace, and the in-plane / in-plane uniformity of the film thickness and the germanium ratio is significantly deteriorated.

An object of the present invention is to solve the above problems and to obtain a silicon germanium film having good in-plane / in-plane uniformity of film thickness and germanium ratio by a low pressure CVD method using monosilane and monogermane. To provide a method for manufacturing a semiconductor device formed on a substrate and a substrate processing apparatus.

[0006]

In order to solve the above-mentioned problems, the present invention uses a monosilane and a monogermane as a reaction gas as described in claim 1 and uses a low pressure CVD method in a reaction furnace. According to the method of manufacturing a semiconductor device in which a poly or amorphous silicon germanium film is formed on a substrate, the monogermane is supplied midway into the reaction furnace by using a plurality of nozzles having different lengths. A device manufacturing method is configured.

Further, according to the present invention, as described in claim 2, a reaction tube for processing a substrate, a heater for heating the substrate, a nozzle for supplying monosilane into the reaction tube,
And a nozzle for supplying monomonogermane into the reaction tube, and the nozzle for supplying monomonogermane comprises a plurality of nozzles having different lengths.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a substrate processing apparatus which is an embodiment of the present invention.

In the method for manufacturing a semiconductor device of the present invention, monosilane and monogermane are used as reaction gases, and a low pressure CVD method is used in the reaction furnace 11.
In a method of manufacturing a semiconductor device in which a silicon germanium film is formed on a wafer 4 which is a substrate, monogermane is supplied into a furnace through a large number of nozzles 12a to 12e having different lengths as shown in FIG. And

In the preliminary consideration before the present invention was made, in order to obtain good in-plane / in-plane uniformity of the film thickness and the germanium ratio (3% or less), the film was formed along the flow of the reaction gas. Experience shows that it is necessary to keep the consumption of monosilane gas and monogermane gas, especially monogermane gas at 10% or less from the point where the reaction starts to the point where film formation ends. Has been.

Monogermane gas was fed from the bottom of the reactor 1 to 1
The monogermane flow rate required to keep the consumption of monogermane gas at 10% or less in the form of supplying the gas into the furnace with this nozzle is 26 cm in inner diameter for an 8-inch wafer and 130 in height.
When the surface area of the portion where the film is formed (inner wall of the reaction tube and the surface of the wafer) and the actual film formation rate (experimental value) are estimated in a cm reaction tube, it is about 1 when the germanium ratio is 20%
It becomes 40 sccm. Actually 1 reaction gas for safety
Since it is diluted to about 0% and used, 1400 sccm of diluted monogermane is used. The flow rate of monosilane required at this time is 20% germanium and the film formation temperature is 50%.
At 0 ° C., it is about 2800 sccm (undiluted). If the germanium ratio is increased to improve the device characteristics, increasing the germanium ratio increases the film formation rate as described above.
At that time, the flow rates of monogermane and monosilane required to keep the consumption of monogermane gas at 10% or less are 500 sccm (actually 5000 sccm diluted monogermane) and 5000 sccm (undiluted), respectively. Is required to bring the inside of the reaction furnace to a general process pressure (30 to 60 Pa), a pump with an extra large exhaust capacity is required, which is not realistic.

From these calculation results, monogermane was supplied into the furnace halfway through the use of a large number of nozzles, and the consumption of monogermane was detected along with the flow of the reaction gas in the film formation reaction from the point where the film formation reaction started. It can be said that maintaining 10% or less until the end is important for forming a silicon germanium film having good in-plane / in-plane uniformity of film thickness and germanium ratio. The present invention has been made based on such considerations. Although the silicon germanium film formed under such conditions is a polysilicon germanium film, an amorphous silicon germanium film may be formed under conditions different from this.

As an example of the substrate processing apparatus according to the present invention,
Monosilane (SiH _Four) And Monogerman
(GeH_Four) And use multiple sheets in a boat in the reactor
With the wafers in the vertical direction stacked and supported,
Gas was introduced to raise it in the vertical direction, and that gas was used.
Low pressure C for forming a thin film on the wafer by the CVD method
A schematic structure of the VD device is shown in FIG.

Inside the heater 6 divided into four zones, an outer tube 1 made of quartz which is an outer cylinder of the reaction furnace 11 and an inner tube 2 which is a reaction tube inside the outer tube 1 are installed. A vacuum is evacuated between the tubes using the mechanical booster pump 7 and the dry pump 8. Therefore, the reaction gas introduced into the inner tube 2 rises in the inner tube 2 and descends between the two types of tubes 1 and 2 to be exhausted.
The quartz boat 3 loaded with the wafer 4 is placed in the inner tube 2, and when exposed to the reaction gas, a thin film is formed on the wafer 4 by the reaction in the gas phase and on the surface of the wafer 4. The heat insulating plate 5 is for heat insulating between the boat 3 and the lower part of the device. Further, in FIG. 1, 9 is a boat rotating shaft, and 10 is a stainless lid.

The boat 3 is provided with a total of 172 slots for supporting the wafers 4, and the dummy wafers 4 up to the tenth slot counting from the bottom slot.
However, from the 11th to the 167th slot, product wafer 4
However, the dummy wafer 4 is supported from the 168th slot to the 172nd slot. Further, the top area, the center area, and the bottom area in FIG. 1 are the area where the wafer 4 of the product from the 129th to 167th slot exists, and the area where the wafer 4 of the product from the 37th to 128th slot exists, respectively. , 11 to the 36th slot, the area where the wafer 4 of the product exists. Further, among the four heater zones, the lowermost L (Lower) zone corresponds to a region below the first slot where almost no wafer exists, and the second CL (Center) from the bottom The Lower) zone corresponds to a region where the dummy wafer 4 and the product wafer 4 coexist from the 2nd to the 56th slots, and the third CU (Center Upper) zone from the bottom, that is, the second from the top, is from 57. It corresponds to an area where the product wafer 4 and the dummy wafer 4 are mixed up to the 172th slot, and the fourth U from the bottom, that is, the uppermost U (Upper) zone is an area where no upper wafer exists. It corresponds.

The quartz nozzles 12a to 12e for supplying monogermane (GeH ₄ ) into the reaction furnace 11 have different lengths,
There are 5 in total, and 12a is monosilane (SiH
₄ ) is provided at the furnace opening (lower left in the figure) together with a nozzle for supplying 12b, 12c, 12d and 12e.
Are provided so as to pass through the furnace opening and the respective ejection ports correspond to the positions of the 30th slot, the 70th slot, the 110th slot and the 150th slot. By using the plurality of nozzles 12a to 12e having different lengths, monogermane can be supplied into the reaction furnace 11 halfway.

Further, the heat insulating plate 5 is installed below the heater 6 corresponding to the L zone.

As an example of the method for manufacturing a semiconductor device according to the present invention, FIG. 2 shows a film forming procedure using the substrate processing apparatus shown in FIG.

First, after stabilizing the inside of the reaction furnace 11 to the film formation temperature, the boat 3 loaded with the wafer 4 as the substrate is loaded (inserted) into the reaction furnace 11. Reactor (Reactor 1
1) The inside is evacuated, and N ₂ purge is performed in order to desorb the water and the like adsorbed on the boat 3 and the tubes 1 and 2. After performing a leak check in the reactor (reaction furnace 11), the flow rates of monosilane and monogermane are set, and gas is flowed in the reaction furnace 11 to stabilize the pressure and form a film. In the pipe After deposition is complete and the cycle purged with N _2, returning the reactor to atmospheric pressure with N _2. After returning to atmospheric pressure, the boat 3 is unloaded and the wafer 4 is naturally cooled. Finally the wafer 4
Is taken out of the boat 3.

[Embodiment Example] (Supply of monogermane using plural nozzles halfway) FIG.
In the substrate processing apparatus illustrated in Fig. 1, by supplying monogermane into the reaction furnace halfway using multiple nozzles of different lengths, polysilicon germanium with good in-plane / in-plane uniformity of film thickness and germanium ratio is obtained. A film can be formed.

As a result of an actual experiment, the in-plane / in-plane uniformity of the obtained film thickness and germanium ratio, including the conventional example, are shown in FIG.

In FIG. 3, "1 nozzle" corresponds to the conventional example. In this case, there is only one nozzle of monogermane, and its ejection port is near the ejection port of monosilane. On the other hand, "3 nozzles" and "5 nozzles" are the forms in the present invention, and in the case of 3 nozzles, the ejection ports of the three monogermane nozzles are close to the monosilane ejection port and the boat 3 Near the 70th slot and near the 150th slot, and in the case of 5 nozzles, the nozzles of the five monogermane nozzles are near the monosilane nozzle and near the 30th slot of the boat 3. , 70th slot, 110th slot, and 150th slot. Almost the same amount of monogermane is ejected from each ejection port.

The film forming temperature is 500 ° C. and the vapor phase pressure is 30 P.
a, the germanium ratio is 20%, and the total flow rate of monogermane (undiluted) is as shown in the bottom line (Total GeH) of FIG.
_{As shown in (4} flow rate display), 5 for 1 nozzle
58 sc for 0 sccm, 3 nozzles and 5 nozzles
cm. Monosilane and monogermane are diluted with hydrogen about 10 times and supplied to the reactor.

In-plane uniformity of the film thickness and in-plane uniformity of the germanium ratio (expressed as Ge ratio) obtained as a result of the experiment.
The face-to-face uniformity is shown in the figure.

As is apparent from FIG. 3, by supplying monogermane into the furnace by using a large number of nozzles, the film thickness can be drastically increased as compared with the case of supplying only one nozzle (conventional example). It can be seen that the in-plane / in-plane uniformity of the germanium ratio is improved.

[0026]

According to the present invention, a silicon germanium film having good in-plane / in-plane uniformity of film thickness and germanium ratio is formed on a substrate by a low pressure CVD method using monosilane and monogermane. It is possible to provide a semiconductor device manufacturing method and a substrate processing apparatus.

[Brief description of drawings]

FIG. 1 shows a monosilane (S) as a reaction gas according to the present invention.
FIG. 3 is a structural schematic diagram of a low pressure CVD apparatus for forming a thin film using iH ₄ ) and monogermane (GeH ₄ ).

FIG. 2 is a diagram illustrating a film forming procedure by a low pressure CVD method.

FIG. 3 is a diagram showing a comparison of in-plane / in-plane uniformity of film thickness and germanium ratio in a monogermane supply mode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer tube, 2 ... Inner tube, 3 ... Boat, 4 ... Wafer, 5 ... Insulation plate, 6 ... Heater, 7 ... Mechanical booster pump, 8 ... Dry pump, 9 ... Boat rotating shaft, 10 ... Stainless lid, 11 ... Reactor, 12a
~ 12e ... Nozzle.

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Claims (2)

[Claims] 1. Using monosilane and monogermane as a reaction gas, and by a low pressure CVD method in a reaction furnace,
In a method for manufacturing a semiconductor device in which a poly or amorphous silicon germanium film is formed on a substrate, the monogermane is supplied to the reaction furnace halfway using a plurality of nozzles having different lengths. Production method. 2. A monotube containing a reaction tube for processing a substrate, a heater for heating the substrate, a nozzle for supplying monosilane into the reaction tube, and a nozzle for supplying monomonogermane into the reaction tube. The substrate processing apparatus is characterized in that the nozzles for supplying the liquid are composed of a plurality of nozzles having different lengths.