JPH07221034A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an HSG polysilicon film and a phosphorus doped polysilicon film while removing a natural oxide film using a general diffusion furnace. CONSTITUTION:The natural oxide film is removed from a silicon substrate 100 and is put in a furnace for the heat treatment. At the time of forming an HSG polysilicon film on the surface of a phosphorus doped amorphous silicon film 105, HCl gas diluted with superpure N2 gas is introduced, the natural oxide film formed again on the surface of the phosphorus doped amorphous silicon film 105 is etched off with silicon by etching and a highly clean silicon plane is provided. Thus, the capacity increase rate of the capacity electrode formed of the HSG polysilicon film 107, an insulating film 108 and the phosphorus doped silicon film 109 is increased or the contact resistance of the phosphorus doped polysilicon film to be buried in the contact hole is reduced.

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 method for heat treating the surface of a silicon substrate or a silicon film, and a method for forming a silicon film on the surface.

[0002]

2. Description of the Related Art For example, as a means for securing a stored charge capacity in a capacitor electrode which is required in accordance with high integration of various elements of a semiconductor device, for example, high integration of DRAM, for example, Applied Physics Letters.
Vol. 61 (1992) 159-161, HSG (Hemisp) having fine irregularities on the surface.
It has been proposed to form a (herring grained) polysilicon film on the stack capacitance electrode.

When this HSG polysilicon film is formed on the surface of the capacitor electrode, for example, after removing the natural oxide film on the surface of the phosphorus-doped amorphous silicon film patterned in the shape of the capacitor electrode with dilute hydrofluoric acid. , This is washed with water, and subsequently at a low temperature of 400 ° C. or lower so that regrowth of a natural oxide film does not occur, and in a furnace previously kept in an ultra-high vacuum atmosphere at 570-580 ° C.
It is heated in the ultra-high vacuum atmosphere to the temperature of. After that, at this temperature, SiH ₄ or Si ₂ H ₆ gas is supplied for 10 to 20 SC.
The gas is introduced into the furnace at a flow rate of CM for several minutes to nucleate (nucleate) HSGs on the phosphorus-doped amorphous silicon film, and then the gas introduction is stopped and heat treatment (post-annealing) is performed for several minutes. By this treatment, the HSG polysilicon film is formed on the surface of the phosphorus-doped amorphous silicon film.

In forming such an HSG polysilicon film, it is necessary to set the phosphorus-doped amorphous silicon film in the furnace in an ultrahigh vacuum atmosphere so that a natural oxide film is not regrown on the surface thereof. Therefore, conventionally, a batch type diffusion furnace having a load lock chamber as shown in FIG. 9 is used. In this batch type diffusion furnace, an outer tube 1, an inner tube 2, and a gantry 3 form a furnace chamber, and a resistance heating furnace 4 is provided around the furnace chamber. Further, the exhaust port 5 connected to the furnace chamber is used to exhaust the inside of the furnace chamber, and various gases can be introduced into the furnace chamber from the gas inlet port 6. A quartz boat 9 for stacking and supporting the silicon substrates 8 by the boat elevator 7 can be installed in the furnace chamber. In addition, a load lock chamber 10 is provided below the pedestal 3 and the exhaust port 1
By evacuating through 1, the inside can be made into an ultra-high vacuum atmosphere. A substrate transfer chamber 14, a substrate transfer machine 15, and a cassette chamber 16 are connected to the load lock chamber 10 via gate valves 12 and 13, and a substrate cassette is set in the furnace chamber by these and the boat elevator 7. It is configured to be possible. Reference numeral 17 is an exhaust port of the cassette chamber 16.

On the other hand, it is known that the contact hole diameter for connecting the silicon substrate and the conductive film above it is reduced due to the high integration of the device, which increases the contact resistance and adversely affects the device characteristics. Has been. As one of the means for solving this, for example,
There has been proposed a method of connecting a silicon substrate and an upper conductive film by burying a contact hole with phosphorus-doped polysilicon whose resistance has been reduced by increasing the particle diameter by crystallization heat treatment from phosphorus-doped amorphous silicon. In this case, remove the natural oxide film of the silicon substrate with the contact holes previously opened with dilute hydrofluoric acid for the purpose of lowering the contact resistance, and then wash it with water to prevent re-growth of the natural oxide film. 40
At a low temperature of 0 ° C. or less, and further, by loading in a furnace shown in FIG. 9 which was previously kept in an ultra-high vacuum atmosphere by a load lock mechanism, and heated in an ultra-high vacuum atmosphere to a temperature of 450 to 550 ° C., at this temperature SiH ₄ or Si ₂ H ₆ gas is introduced into the furnace at a flow rate of 100 to 200 SCCM, and PH ₃ gas is introduced into the furnace at a flow rate of 120 to 240 SCCM to form a phosphorus-doped amorphous silicon film. afterwards,
A crystallization heat treatment (annealing) is used to form a phosphorus-doped polysilicon film.

However, in forming the above-mentioned HSG polysilicon film and phosphorus-doped polysilicon film, an ultrahigh vacuum atmosphere diffusion furnace having a load lock chamber shown in FIG. 9 is required. Therefore, since the load lock chamber 10, the substrate transfer chamber 14, the gate valves 12 and 13, or the turbo molecular pump for ultra-high vacuum disposal is provided, the cost of the diffusion furnace is the same as that of an ordinary diffusion furnace or LPCVD furnace. There is a problem that it takes more than double. Further, since the structure of the diffusion furnace is extremely complicated, there is a problem that maintenance work is difficult.

Further, when the phosphorus-doped polysilicon film is embedded in the contact hole, if fluorine or carbon enters from the etching gas near the surface of the silicon substrate in the contact hole during the dry etching of the contact hole opening, this naturally occurs. Since it cannot be removed by the dilute hydrofluoric acid treatment for removing the oxide film, even if phosphorus-doped amorphous silicon is grown in the furnace shown in FIG. 9 immediately after the dilute hydrofluoric acid treatment, the contact resistance does not decrease so much due to these contaminations. There is.

Therefore, the HS shown in FIG.
A method of forming a G polysilicon film or a phosphorus-doped polysilicon film has been proposed, for example, Japanese Patent Laid-Open No. 32522/1993.
As shown in 7 JP, on the surface of phosphorus-doped amorphous silicon film and a high temperature heat treatment in an H ₂ atmosphere, or after removal of the natural oxide film on the opening surface of the silicon substrate of the contact hole, HSG There is a method of performing HSG formation or amorphous silicon growth by lowering the temperature to the polysilicon formation temperature or the phosphorus-doped amorphous silicon growth temperature. Alternatively, as shown in Japanese Patent Publication No. 63-41210, a natural oxide film on the surface of the phosphorus-doped amorphous silicon film or on the surface of the silicon substrate with the contact holes opened is subjected to a high temperature heat treatment in an H ₂ atmosphere. After the removal, there is a method in which HSG formation or amorphous silicon growth is performed by introducing HCl gas into the furnace to lower the temperature up to the HSG polysilicon formation temperature or the phosphorus-doped amorphous silicon growth temperature to prevent natural oxide film regrowth. .

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the methods of Japanese Patent No. 2527 and Japanese Patent Publication No. 63-41210, although the furnace as shown in FIG.
When a G polysilicon film is to be formed, it is necessary to heat the substrate at a temperature higher than the HSG formation temperature in order to perform a high temperature heat treatment in an H ₂ atmosphere. There is a problem that crystallization is caused, resulting in hindering the formation of the HSG polysilicon film. On the other hand, in the case of filling the contact hole, there is a problem that the process time per batch becomes long because the amorphous silicon is grown by lowering the temperature after the high temperature heat treatment in the H ₂ atmosphere and the throughput is reduced.

[0010]

It is an object of the present invention to prevent natural oxide film regeneration in a general diffusion furnace without the need for a diffusion furnace having a complicated structure such as a diffusion furnace having a load lock chamber. Another object of the present invention is to provide a method for manufacturing a semiconductor device, which enables the heat treatment of 1. Further, another object of the present invention is to
Provided is a method for manufacturing a semiconductor device, which is capable of forming an HSG polysilicon film suitably using a general diffusion furnace. In this case, the present invention further provides a method of manufacturing a semiconductor device, in which an HSG polysilicon film having an increased capacity increase rate of a capacitor electrode formed of a silicon film is formed. Still another object of the present invention is to provide a method of manufacturing a semiconductor device, which can embed a polysilicon film containing impurities in a contact hole using a general diffusion furnace and without increasing the process time. provide. In this case, the present invention further provides a method for manufacturing a semiconductor device capable of forming a polysilicon film having a low contact resistance.

[0011]

According to the present invention, when a silicon film placed in a furnace is treated at a high temperature, HCl gas diluted with ultra-high purity N ₂ gas is heated in the furnace when the silicon film is heated. And removing the natural oxide film on the surface of the silicon film and heat treating the silicon film.

That is, according to the present invention, when the HSG polysilicon film is formed on the surface of the silicon film placed in the furnace,
H diluted with ultra-high purity N ₂ gas when heating the silicon film
Cl gas is introduced into the furnace to remove the natural oxide film on the surface of the silicon film, and to remove HSG on the surface of the silicon film.
It is characterized in that a polysilicon film is formed. The present invention also provides an ultra-high purity N ₂ gas when heating the phosphorus-doped amorphous silicon film when forming the HSG polysilicon film on the surface of the phosphorus-doped amorphous silicon film formed on the substrate placed in the furnace. HC diluted with
l gas is introduced into the furnace to remove the natural oxide film on the surface of the phosphorus-doped amorphous silicon film, and form an HSG polysilicon film on the surface of the phosphorus-doped amorphous silicon film.

For example, when forming a polysilicon film having impurities introduced on the surface of a silicon substrate placed in a furnace, HCl gas diluted with ultra-high purity N ₂ gas is heated in the furnace when the silicon substrate is heated. Then, the native oxide film on the surface of the silicon substrate is removed, and the polysilicon film is formed on the surface of the silicon substrate. Alternatively, when an insulating film is formed on the surface of a silicon substrate placed in a furnace, and a polysilicon film having impurities introduced into contact with the silicon substrate is formed in a contact hole opened in the insulating film, the silicon At the time of heating the substrate, HCl gas diluted with ultra-high purity N ₂ gas is introduced into the furnace to remove the natural oxide film on the surface of the silicon substrate in the contact hole, and to remove the silicon substrate in the contact hole. The polysilicon film is formed on the surface.

[0014]

According to the present invention, when an amorphous silicon film or a silicon substrate whose natural oxide film has been previously removed by dilute hydrofluoric acid is loaded into a batch type furnace and heated, the natural oxide film is regrown. Even if there is, the natural oxide film is etched together with silicon by the action of HCl gas diluted with ultra-high purity N ₂ gas. Therefore, the HSG polysilicon film can be formed even by using a general diffusion furnace, and the polysilicon film containing impurities can be embedded in the contact hole, so that the device can be manufactured at a low cost. Further, by forming the HSG polysilicon film after completely removing the natural oxide film, the capacity increase rate of the capacitor electrode can be increased.

On the other hand, when the polysilicon film is embedded in the contact hole, the contamination of fluorine, carbon, etc. generated in the dry etching of the contact hole is also removed when the silicon is etched by HCl, so that the contact resistance can be lowered. It will be possible. Further, it is not necessary to lower the temperature once, and high-throughput manufacturing becomes possible.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic view of a diffusion furnace used in this example,
It is a low pressure chemical vapor synthesis furnace that has been generally provided in the past. That is, the outer tube 1, the inner tube 2, and the gantry 3 constitute a furnace chamber, and the resistance heating furnace 4 is arranged around the furnace chamber. Further, an exhaust port 5 is provided in the furnace chamber to exhaust the inside of the furnace chamber to reduce the pressure, and a gas introduction port 6 is provided in the furnace chamber so that various gases can be introduced into the furnace chamber. Further, a quartz boat 9 for placing the silicon substrates 8 in a stacked state by the boat elevator 7 is arranged in the furnace chamber.

(Embodiment 1) In the present embodiment 1, an example of forming an HSG polysilicon film using the diffusion furnace shown in FIG. 1 will be described. First, as shown in Fig. 2 (a), the diameter is 150m.
An element isolation film 101 made of a silicon oxide film is formed on the P-type silicon substrate (silicon wafer) 100 of m by a selective thermal oxidation method or the like by 4000 Å, and then an N-type diffusion layer 102 is formed by ion implantation of phosphorus. Accelerating voltage is 50 Ke
V and the dose amount are 5E13 cm2. After that, the insulating film 103 such as a silicon oxide film is formed by the CVD method at 8000Å
After growing, the insulating film 103 is selectively etched by a photolithography technique to open a contact hole 104 having a diameter of 0.5 μm. A phosphorus-doped amorphous silicon film 105 is grown on the silicon substrate 100 by LPCVD at a growth temperature of 500 ° C., a growth pressure of 20 Pa, and Si ₂ H _6.
Flow rate 100 SCCM, He dilution 1%, PH ₃ flow rate 120
Grow 8000Å under SCCM conditions.

After that, as shown in FIG. 2B, the phosphorus-doped amorphous silicon film 105 is patterned into a desired shape as a capacitor electrode 106 by a photolithography technique. Next, after immersing the silicon substrate 100 in 1% hydrofluoric acid for 1 minute, water washing is performed for 2 minutes,
The natural oxide film on the surface of the capacitor electrode 106 is removed. Then, within 1 hour, the substrate is put into the furnace shown in FIG. 1 by the boat elevator 7 at room temperature. Fifty silicon substrates were horizontally loaded on the quartz boat 9.

Next, H on the surface of the capacitance electrode 106.
An SG polysilicon film is formed. At this time, a phosphorus-doped amorphous silicon film 105 having a shape of a capacitor electrode is formed.
If the natural oxide film is regrown on the surface of the amorphous silicon, or if part of it is crystallized, surface diffusion of silicon atoms on the amorphous silicon surface is hindered, and
SG formation will be hindered. Therefore, FIG. 3 (a)
Heat treatment is performed in the sequence of. That is, first, 1E-
Vacuumed down to about 3 torr, ultra-high purity N ₂ gas with water content of 1 ppm or less 1 SLM + HCl gas 100 SC
CM was introduced into the furnace and heated to 575 ° C. at a pressure of 1 torr. As a result, the regrown natural oxide film is removed.

After that, the ultra-high purity N ₂ gas + HCl gas was stopped and the inside of the furnace was sufficiently evacuated. Then, as shown in FIG. 2 (c), nuclei were formed on the surface of the capacitive electrode 106 under the conditions of SiH ₄ flow rate of 20 SCCM and 3 min. Apply attachment process. Next, SiH ₄
By stopping the gas and post annealing for 1 min,
As shown in FIG. 2D, the HSG polysilicon film 107 is formed on the surface of the capacitor electrode 106. Then, the temperature is lowered in an N ₂ atmosphere. Further, the amorphous silicon film 105 forming the capacitor electrode 106 is heat-treated for crystallization (850 ° C., 10
min, after heat treatment) in an N ₂ atmosphere, the grown silicon oxide film 108 of 100Å by a CVD method as a capacitance film on the surface of the HSG polysilicon film 107, the phosphorus doped polysilicon film 109 as the upper capacitor electrode is formed thereon 1000Å grow.

A reference sample is formed for comparison with the HSG polysilicon film thus formed. The reference sample 1 is the same as that of the first embodiment except that the furnace shown in FIG. 9 is used only for forming the HSG polysilicon film. In this case, in the step of forming the HSG polysilicon film, the substrate was previously immersed in 1% dilute hydrofluoric acid for 1 min, and then washed with water for 2 min to remove the native oxide film on the surface, and then within 1 hour as shown in FIG. Set 50 silicon substrates in the cassette chamber 16 and then set the cassette chamber 16 to 1E-7.
Exhaust to torr. The gate valves 12 and 13 are opened, and the substrate transfer machine 15 is used to move through the substrate transfer chamber 14.
The silicon substrate is transferred to the quartz boat 9 in the load lock chamber 10 that has been evacuated to 1E-8 torr in advance. Furthermore, the boat elevator 7 is installed in the furnace chamber. After that, HSG formation is performed in a sequence as shown in FIG. At this time, the nucleating condition and the post-annealing condition are the same as in the first embodiment.

For the reference sample 2, the step of forming the HSG polysilicon film was performed using the furnace shown in FIG. 1, and the heat treatment sequence was as shown in FIG. 4 (b). The method of 63-41210 is combined. That is, during heating, the atmosphere is H ₂ and the pressure is 1 torr. High temperature heat treatment at 600 ° C, ie H ₂
Baking is performed at a pressure of 1 torr for 4 minutes to perform capacitive electrode 1
After removing the natural oxide film on the phosphorus-doped amorphous silicon film as 06, the temperature was lowered to 575 ° C. in an H ₂ + HCl atmosphere while suppressing the natural oxide film regrowth under the conditions of H ₂ flow rate 1 SLM / HCl flow rate 100 SCCM and pressure 1 torr. did. After that, an HSG polysilicon film was formed under the same conditions as in Example 1, and the temperature was lowered in an N ₂ atmosphere. The other steps are exactly the same as in Example 1.

The capacitance increase rate (accumulated charge capacitance ratio) of the capacitance electrodes having the HSG polysilicon films of Example 1 and Reference Samples 1 and 2 formed as described above is shown in comparison with FIG. As can be seen from this figure, the capacity increase rate of Example 1 is 1.8, which is the same as that of Reference Sample 1, while that of Reference Sample 2 is 1.4.
Met. This result is explained as follows. That is,
When the substrate is heated, the water partial pressure in the furnace is adjusted by the evaporation of the water adsorbed on the substrate due to the pretreatment or the re-adhesion of the water adsorbed on the furnace wall (the water originally entered into the furnace due to the air entrainment during loading). It rises due to evaporation. As a result, a natural oxide film is regrown on the phosphorus-doped amorphous silicon film 105 (106).
When the etching rate of silicon by l gas increases,
Since the natural oxide film is etched together with silicon by the HCl gas, the surface of the phosphorus-doped amorphous silicon film 105 (106) is clean by the time HSG is formed.

Therefore, in the case of Example 1, sufficient HSG formation was achieved in the same manner as in the furnace of FIG. 9 used for the reference sample 1 having a complicated load-lock mechanism for suppressing the amount of water carried into the substrate and the amount of water carried into the atmosphere. Will be done.
Moreover, since this is simply connected to the ultra-high purity N ₂ gas + HCl gas pipe to a simple furnace having no load lock mechanism, the apparatus cost is low and maintenance is easy. On the other hand, in the case of the reference sample 2, 6 in the H ₂ atmosphere.
In order to heat the substrate to a temperature higher than the HSG formation temperature for high temperature treatment at 00 ° C., partial crystallization is caused inside the phosphorus-doped amorphous silicon film 105 (106), which hinders the HSG formation and results in a capacitance. The rate of increase decreases.

(Embodiment 2) Next, a second embodiment 2 of the present invention
Will be described. In the second embodiment, phosphorus-doped amorphous silicon is grown in a contact hole formed in an insulating film on a silicon substrate, and then a crystallization heat treatment is performed to form a phosphorus-doped polysilicon film,
This is an example of manufacturing a semiconductor device in which this is embedded in a contact hole.

First, as shown in FIG. 5 (a), the diameter is 150 m.
The element isolation film 201 made of a silicon oxide film is formed on the P-type silicon substrate 200 of m by a selective oxidation method of silicon.
After the formation of 00Å, the N type diffusion layer 202 is formed by ion implantation of phosphorus. The acceleration voltage at this time is 100 Ke
V and dose amount are set to 1E16 cm2. After that, an insulating film 203 such as a silicon oxide film is formed by a CVD method at 8000Å
grow up. Further, as shown in FIG. 5B, the diameter of the insulating film 203 is 0.2 to 1.2 μm by the photolithography technique.
The contact hole 204 is opened. This board 200
Was soaked in 1% hydrofluoric acid for 1 min and then washed with water for 2 mi.
Then, the natural oxide film on the surface of the silicon substrate in the contact hole 204 is removed. After that, within 1 hour
The substrate was put into the furnace shown in FIG. Fifty substrates are horizontally loaded on the quartz boat 9.

After that, amorphous silicon is grown in the sequence shown in FIG. That is, first, 1E-
Vacuumed down to about 3 torr, ultra-high purity N ₂ gas with water content of 1 ppm or less 1 SLM + HCl gas 100 SC
CM is introduced into the furnace and heated to 500 ° C. at a pressure of 1 torr. After that, the ultra-high purity N ₂ gas + HCl gas was stopped, the inside of the furnace was sufficiently evacuated, and then, as shown in FIG.
The phosphorus-doped amorphous silicon film 205 is grown at a growth temperature of 500 ° C., a growth pressure of 20 Pa, and a Si ₂ H ₆ flow rate of 100 S.
CCM, He diluted 1% PH ₃ grow under the condition of 120 SCCM flow rate. Then, the temperature is lowered in an N ₂ atmosphere.

Then, as shown in FIG. 5 (d), at 850 ° C.,
Crystallization heat treatment was performed in an N ₂ atmosphere for 10 minutes to form a phosphorus-doped polysilicon film 206. Further, after the phosphorus-doped polysilicon film 206 on the insulating film 203 is dry-etched, aluminum is sputtered and this is patterned to form an aluminum wiring 207.

On the other hand, in order to compare the contact resistance, reference samples 3 and 4 are manufactured. As the reference sample 3, the furnace shown in FIG. 9 is used only for forming the phosphorus-doped amorphous silicon film, and the other conditions are the same as those of the second embodiment. In this case, in the step of forming the phosphorus-doped amorphous silicon film, the substrate is previously immersed in 1% dilute hydrofluoric acid for 1 min, followed by washing with water for 2 min to remove the natural oxide film on the surface of the silicon substrate in the contact hole. Within one hour, 50 substrates are set in the cassette chamber 16 shown in FIG. 9, and then the cassette chamber 16 is evacuated to 1E-7 torr. The gate valves 12 and 13 are opened, and the substrate is transferred to the quartz boat 9 in the load lock chamber 10 that has been evacuated to 1E-8 torr through the substrate transfer chamber 14 using the substrate transfer machine 15. Furthermore, the boat elevator 7 is installed in the furnace chamber. Then, a phosphorus-doped amorphous silicon film is formed in the sequence as shown in FIG. The phosphorus-doped amorphous silicon growth conditions were the same as in Example 2.

In the reference sample 4, the step of forming the phosphorus-doped amorphous silicon film was performed using the furnace shown in FIG. 1, and only the heat treatment sequence was performed as in Japanese Patent Laid-Open No. 3-22527 as shown in FIG. 6B. The method disclosed in JP-A-63-41210 is combined. That is, when heating, H ₂
The atmosphere is used and the pressure is 1 torr. After high temperature heat treatment at 600 ° C., that is, H ₂ bake at a pressure of 1 torr for 4 minutes to remove the natural oxide film on the surface of the silicon substrate in the contact hole, H ₂ flow rate 1 SLM / HCl flow rate 10
The temperature was lowered to 500 ° C. in an H ₂ + HCl atmosphere while suppressing the natural oxide film regrowth under the conditions of 0 SCCM and a pressure of 1 torr. Then, a phosphorus-doped amorphous silicon film is grown under the same conditions as in Example 2, and the temperature is lowered in N ₂ atmosphere.
The other steps are exactly the same as in the second embodiment.

Each phosphorus-doped polysilicon film (206) of Example 2, Reference Samples 3 and 4 formed as described above
The results of comparing the contact resistances of the above are shown in FIG. The contact resistance is measured by applying a bias of 3 V to both ends of the chain of 10,000 contacts, and the measured value is converted into the resistance per contact, and the aluminum wiring resistance and diffusion layer resistance are subtracted from the polysilicon plug. The resistance and the polysilicon / substrate interface resistance were taken as the contact resistance.

As shown in FIG. 7, the contact resistances of Example 2 and Reference Sample 4 are exactly the same, while the contact resistance of Reference Sample 3 is high. In the case of Example 2, the natural oxide film re-growth occurs due to the effect of the residual moisture in the furnace when the substrate is heated. However, the natural oxide film is etched together with silicon by HCl gas, and the fluorine by dry etching at the time of opening the contact hole is increased. Contamination such as carbon is also etched at the same time. On the other hand, in the case of the reference sample 4, the natural oxide film is etched due to the H 2 treatment at a high temperature, and the contaminations such as fluorine and carbon are also etched at the same time. Therefore, in these cases, since the natural oxide film, the contamination of fluorine, carbon, etc. are not present at the interface between the phosphorus-doped polysilicon film 15 and the substrate, the contact resistance becomes low. However, in the case of the reference sample 3, although the natural oxide film is removed by the dilute hydrofluoric acid treatment, the contamination such as fluorine and carbon is not removed, so that the contact resistance becomes high.

FIG. 8 shows the results of comparison of the throughput of phosphorus-doped amorphous silicon growth between Example 2 and Reference Samples 3 and 4. In Example 2 and Reference Sample 3, the number is 37.5 sheets / hour, whereas in Reference Sample 4, it is 25.
Sheets / hour. This is because the reference sample 4 undergoes a high temperature heat treatment once in an H ₂ atmosphere and then the temperature is lowered to grow amorphous silicon, so that the process time per batch becomes long.

Although the first and second embodiments are examples of amorphous silicon and polysilicon doped with phosphorus, the present invention is similarly applied to amorphous silicon and polysilicon doped with other impurities. It is possible to Further, the heat treatment in the present invention can be similarly applied to the heat treatment other than the formation of the HSG polysilicon film on the capacitor electrode and the formation of the polysilicon film embedded in the contact hole.

[0035]

As described above, according to the present invention, when the silicon film placed in the furnace is processed at a high temperature, the HCl gas diluted with the ultra-high purity N ₂ gas is heated in the furnace when the silicon film is heated. Introduced into the chamber, the natural oxide film on the surface of the silicon film is removed and the silicon film is heat-treated, so that the HSG polysilicon film can be formed using a diffusion furnace without a load lock chamber, and the contact Embedding with phosphorus-doped polysilicon can be realized. As a result, it is possible to manufacture with a simple configuration in which the piping of ultra-high purity N ₂ gas + HCl gas is simply connected to the conventional batch type furnace, and the effect of reducing the cost of the diffusion furnace and easy maintainability can be obtained. it can.

In particular, when the HSG polysilicon film is formed on the capacitor electrode, it is possible to manufacture a capacitor electrode having a high capacity increase rate of the capacitor electrode. In addition, when burying phosphorus-doped polysilicon in the contact hole,
Since the contamination of fluorine and carbon generated during dry etching of the contact hole is also removed during the etching of silicon by the above, it is possible to reduce the contact resistance. Further, since it becomes possible to embed phosphorus-doped polysilicon in the contact hole without temporarily lowering the temperature of the substrate, high throughput can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an example of a batch type diffusion furnace used in the present invention.

FIG. 2 is a cross-sectional view showing the main steps of the manufacturing method according to the first embodiment of the present invention.

FIG. 3 is a process sequence diagram showing a comparison between the first embodiment of the present invention and the conventional method.

FIG. 4 is a diagram showing a comparison of the capacitance increase rates of the capacitance electrodes of the HSG polysilicon films of Example 1 and Reference Samples 1 and 2, respectively.

FIG. 5 is a cross-sectional view showing the main steps of a manufacturing method according to a second embodiment of the present invention.

FIG. 6 is a process sequence diagram showing a comparison between a second embodiment of the present invention and a conventional method.

FIG. 7 is a diagram showing contact resistances of the phosphorus-doped amorphous silicon films of Example 2 and reference samples 3 and 4 for comparison.

FIG. 8 is a diagram showing a comparison between the throughputs of the phosphorus-doped amorphous silicon films of Example 2 and reference samples 3 and 4;

FIG. 9 is a cross-sectional view of an example of a batch type diffusion furnace having a load lock chamber.

[Explanation of symbols]

 100 Silicon Substrate 103 Insulating Film 105 Phosphorus-Doped Amorphous Silicon Film 106 Capacitive Electrode 107 HSG Polysilicon Film 108 Insulating Film 109 Non-Doping Polysilicon Film 200 Silicon Substrate 203 Insulating Film 204 Contact Hole 205 Phosphorous Doping Amorphous Silicon Film 206 Phosphorus Doping Polysilicon Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/3065

Claims (5)

[Claims] 1. When processing a silicon film placed in a furnace at a high temperature, an HCl gas diluted with an ultrahigh-purity N ₂ gas is introduced into the furnace when the silicon film is heated, and the silicon film A method of manufacturing a semiconductor device, which comprises removing a natural oxide film on a surface and heat-treating the silicon film. 2. The surface of a silicon film placed in a furnace is H
When forming the SG polysilicon film, HCl gas diluted with ultra-high purity N ₂ gas is introduced into the furnace when the silicon film is heated to remove the natural oxide film on the surface of the silicon film and to remove the silicon. A method of manufacturing a semiconductor device, comprising forming an HSG polysilicon film on the surface of the film. 3. When forming an HSG polysilicon film on the surface of a phosphorus-doped amorphous silicon film formed on a substrate placed in a furnace, an ultrahigh-purity N ₂ gas is used when the phosphorus-doped amorphous silicon film is heated. The diluted HCl gas is introduced into the furnace to remove the natural oxide film on the surface of the phosphorus-doped amorphous silicon film, and the HS on the surface of the phosphorus-doped amorphous silicon film.
A method for manufacturing a semiconductor device, which comprises forming a G polysilicon film. 4. When forming a polysilicon film having impurities introduced on the surface of a silicon substrate placed in a furnace, H that has been diluted with ultra-high purity N ₂ gas at the time of heating the silicon substrate is used.
A method of manufacturing a semiconductor device, comprising introducing Cl gas into a furnace to remove a natural oxide film on the surface of the silicon substrate and forming the polysilicon film on the surface of the silicon substrate. 5. When forming an insulating film on the surface of a silicon substrate placed in a furnace, and forming a polysilicon film into which impurities contacting the silicon substrate are introduced in a contact hole opened in the insulating film. At the time of heating the silicon substrate, HCl gas diluted with ultra-high purity N ₂ gas is introduced into the furnace to remove the natural oxide film on the surface of the silicon substrate in the contact hole, and A method of manufacturing a semiconductor device, comprising forming the polysilicon film on a surface of a silicon substrate.