JP2006286716A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device which can further improve the lateral uniformity of film thickness by solving the problem that a sufficient lateral uniformity of film thickness cannot be achieved even if a ring board is used. <P>SOLUTION: In this manufacturing method of a semiconductor device, at least a first processing gas and a second processing gas are alternately supplied into a processing chamber to form a desired film on the surface of a substrate. The manufacturing method comprises processes of supplying the first processing gas into the processing chamber, removing the first processing gas remaining in the processing chamber out of the processing chamber, supplying the second processing gas into the processing chamber, and removing the second processing gas remaining in the processing chamber out of the processing chamber. In the first processing gas supplying process and/or the second gas supplying process, a carrier gas is supplied together with the processing gas, changing an amount of the carrier gas to be supplied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for manufacturing a semiconductor device, and in particular, using a substrate processing apparatus, an ALD (Atomic Layer D) which is one of the CVD methods on a substrate surface such as a silicon wafer.
The present invention relates to a method of manufacturing a semiconductor device by forming a thin film by an evaporation method.

As an example of a substrate processing apparatus, a semiconductor manufacturing apparatus using a batch type vertical furnace that batch-processes a plurality of substrates is used. In such a vertical furnace, the substrate is vertically oriented. If the film is formed by holding the raw material parallel to the substrate surface from a nozzle attached between the reaction tube and the substrate in parallel at equal intervals, depending on the raw material used for film formation, The film thickness of the film becomes extremely large, and the in-plane uniformity of the film thickness may be extremely deteriorated.

In such a vertical furnace, the uniformity is improved by using a ring boat against the deterioration of the in-plane uniformity of the film thickness. This ring boat is a substrate holding jig in which a donut-shaped ring is arranged between substrates, and a large amount of film is formed on the periphery of the substrate on the ring that covers the periphery of the substrate. It is consumed to improve the in-plane uniformity of the film thickness.

However, by using a ring boat, Al ₂ O ₃ (aluminum oxide) by the ALD method
Some film types, such as a film, can sufficiently improve the in-plane uniformity of film thickness.
Some film types, such as an O ₂ (hafnium oxide) film, improve the in-plane uniformity of the film thickness but do not reach a sufficient improvement.

The object of the present invention is to solve the problem that in-plane uniformity of sufficient film thickness cannot be obtained even if a ring boat is used in some film types in the ALD method, and the in-plane uniformity of film thickness is further improved. An object of the present invention is to provide a method of manufacturing a semiconductor device that can be used.

According to the present invention,
A method of manufacturing a semiconductor device, wherein at least a first processing gas and a second processing gas are alternately supplied into a processing chamber, and a desired film is formed on a substrate surface,
Supplying the first processing gas into the processing chamber;
Removing the first processing gas remaining in the processing chamber from the processing chamber;
Supplying the second processing gas into the processing chamber;
Removing the second processing gas remaining in the processing chamber from the processing chamber;
Including
At least in any one of the first processing gas supply step and the second processing gas supply step, a carrier gas is supplied simultaneously with the processing gas, and the supply amount of the carrier gas is changed and supplied. A method for manufacturing a semiconductor device is provided.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor device which improved the film thickness in-plane uniformity of the thin film produced | generated on the substrate surface can be provided.

Next, a preferred embodiment of the present invention will be described.
First, an outline of a substrate processing apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS.

<Configuration of substrate processing apparatus>
The structure of the substrate processing apparatus of this invention is demonstrated using drawing.
In the following description, a case where a vertical apparatus (hereinafter simply referred to as a processing apparatus) that performs diffusion processing, CVD processing, or the like is applied to the substrate as the substrate processing apparatus will be described. FIG. 1 is an external perspective view of a processing apparatus applied to the present invention. This figure is drawn as a perspective view. FIG. 2 is a side view of the processing apparatus shown in FIG.

The processing apparatus of the present invention inserts a pod (substrate storage container) 100 containing a wafer (substrate) 200 made of silicon or the like into the casing 101 from the outside, and vice versa.
An I / O stage (holding member transfer member) 105 for paying out from the inside to the outside is attached to the front surface of the casing 101, and a cassette shelf for storing the inserted pod 100 in the casing 101 (
(Placing means) 109 is laid. In addition, an N ₂ purge chamber (airtight chamber) 102 serving as a transfer area for the wafer 200 and serving as a loading / unloading space for a boat (substrate holding means) 217 to be described later is provided. N2 purge chamber 10 when processing the wafer 200
The interior of ₂ is filled with an inert gas such as N ₂ gas to prevent a natural oxide film on the wafer 200, and the N ₂ purge chamber 102 is a sealed container.

As the pod 100 described above, the type FOUP is currently used in the mainstream,
By closing an opening provided on one side surface of the pod 100 with a lid (not shown), the wafer 200 can be transported while being isolated from the atmosphere, and by removing the lid, the wafer 200 is moved into and out of the pod 100. Can do. A pod opener (opening / closing means) 108 is provided on the front side of the N ₂ purge chamber 102 in order to remove the lid of the pod 100 and to communicate the atmosphere in the pod and the atmosphere of the N ₂ purge chamber 102. Yes. Pod opener 108, cassette shelf 109,
The pod 100 is transported between the I / O stage 105 by a cassette transfer machine 114. In the transfer space of the pod 100 by the cassette transfer machine 114, the housing 101
The air purified by a clean unit (not shown) provided in the is made to flow.

Inside the N ₂ purge chamber 102, a boat 217 for loading a plurality of wafers 200 in multiple stages, a substrate alignment device 106 for adjusting the position of the notch (or orientation flat) of the wafers 200 to an arbitrary position, and a pod opener 108 A wafer transfer machine (carrying means) 112 that carries the wafer 200 between the upper pod 100, the substrate alignment device 106, and the boat 217 is provided. In addition, a processing furnace 202 for processing the wafer 200 is provided at the upper part of the N ₂ purge chamber 102, and the boat 217 is loaded into the processing furnace 202 by the boat elevator (lifting means) 115 or unloaded from the processing furnace 202. Can be loaded.

<Operation of substrate processing apparatus>
Next, the operation of the substrate processing apparatus of the present invention will be described.

First, the pod 100 that has been transported from the outside of the housing 101 by AGV, OHT, or the like is placed on the I / O stage 105. Pod 100 placed on I / O stage 105
Is transferred directly onto the pod opener 108 by the cassette transfer device 114, or once stored on the cassette shelf 109 and then transferred onto the pod opener 108.
The pod 100 transferred onto the pod opener 108 is removed by the pod opener 108, and the atmosphere inside the pod 100 is communicated with the atmosphere in the N ₂ purge chamber 102.

Next, the wafer 200 is taken out from the pod 100 in communication with the atmosphere of the N ₂ purge chamber 102 by the wafer transfer device 112. The taken-out wafer 200 is aligned so that a notch is determined at an arbitrary position by the substrate alignment device 106, and is transferred to the boat 217 after alignment.

When the transfer of the wafer 200 to the boat 217 is completed, the furnace port shutter 116 of the processing chamber 201 is opened, and the boat 217 loaded with the wafer 200 is loaded by the boat elevator 115.

After loading, arbitrary processing is performed on the wafer 200 in the processing furnace 202. After the processing, the wafer 200 and the pod 100 are discharged out of the housing 101 in the reverse procedure described above.

Next, the outline of the processing furnace of the substrate processing apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS.

In addition, AL is an example of a process performed on a substrate such as a wafer performed in the embodiment of the present invention.
A film forming process using the D method will be briefly described.

In the ALD method, under one film formation condition (temperature, time, etc.), two kinds (or more) of raw material gases used for film formation are alternately supplied onto the substrate one by one, and one atomic layer unit. Adsorbed with
This is a technique for performing film formation using surface reaction.

That is, chemical reactions utilizing, for example, in the case of HfO ₂ film formed ALD method TEMAH (H
f [NCH ₃ C ₂ H ₅ ] ₄ , tetrakismethylethylaminohafnium) and O ₃ (ozone)
Can be used to form a high-quality film at a low temperature of 180 to 250 ° C. Further, the gas supply alternately supplies a plurality of types of reactive gases one by one. And film thickness control is controlled by the cycle number of reactive gas supply. (For example, assuming that the film formation rate is 1 mm / cycle, the process is performed 20 cycles when a film of 20 mm is formed.)

<Processing furnace configuration>
FIG. 3 is a schematic configuration diagram of a vertical substrate processing furnace according to the present embodiment, showing a processing furnace portion in a vertical cross section, and FIG. 4 is a schematic configuration of the vertical substrate processing furnace according to the present embodiment. It is a figure and shows a processing furnace part in a cross section. A reaction tube 203 is provided as a reaction vessel for processing the wafer 200 as a substrate inside a heater 207 as a heating means, and the lower end opening of the reaction tube 203 is an O-ring as an airtight member by a seal cap 219 as a lid. The process furnace 202 is formed by at least the heater 207, the reaction tube 203, and the seal cap 219. A boat 217 as a substrate holding means is erected on the seal cap 219 via a quartz cap 218, and the quartz cap 218 serves as a holding body for holding the boat. Then, the boat 217 is inserted into the processing furnace 202. A plurality of wafers 200 to be batch-processed are stacked on the boat 217 in a horizontal posture in multiple stages in the tube axis direction. The heater 207 heats the wafer 200 inserted into the processing furnace 202 to a predetermined temperature.

The processing furnace 202 is provided with two gas supply pipes 232a and 232b as supply pipes for supplying a plurality of types, here two types of gases. When the raw material supplied from the first gas supply pipe 232a is liquid, the first gas supply pipe 232a includes a liquid mass flow controller 240 that is a flow control means, a vaporizer 241 and a first valve 243a that is an on-off valve. The reaction gas is supplied to the processing furnace 202 through the first nozzle 233a, and merges with the first carrier gas supply pipe 234a. When the raw material supplied from the first gas supply pipe 232a is gas, the liquid mass flow controller 240 is exchanged for gas, and the vaporizer 241 becomes unnecessary. Further, the second gas supply pipe 232b merges with the second carrier gas supply pipe 234b via the first mass flow controller 241a which is a flow rate control means and the second valve 243b which is an on-off valve, and further the second gas supply pipe 232b. The reaction gas is supplied to the processing furnace 202 through the nozzle 233b.

The processing furnace 202 has a fifth valve 24 by a gas exhaust pipe 231 that is an exhaust pipe for exhausting gas.
3e is connected to a vacuum pump 246 which is an evacuation means, and is evacuated. The fifth valve 243e is an open / close valve that can open and close the valve to stop evacuation / evacuation of the processing furnace 202, and can adjust the pressure by adjusting the valve opening.

In the arc-shaped space between the inner wall of the reaction tube 203 constituting the processing furnace 202 and the wafer 200, a first nozzle is formed along the loading direction of the wafer 200 on the inner wall above the lower portion of the reaction tube 203. 233a and the second nozzle 233b are provided, and the first nozzle 233a is provided.
The first gas supply hole 24 is a supply hole for supplying gas to the side surface of the second nozzle 233b.
8a and a second gas supply hole 248b are provided. This first gas supply hole 2
The 48 a and the second gas supply hole 248 b are opened toward the center of the reaction tube 203. The first gas supply hole 248a and the second gas supply hole 248b have the same opening area from the lower part to the upper part, and are provided at the same opening pitch.

A boat 217 for mounting a plurality of wafers 200 in multiple stages at the same interval is provided at the center of the reaction tube 203. The boat 217 can enter and exit the reaction tube 203 by a boat elevator mechanism (not shown). It has become. In order to improve processing uniformity, boat 2
A boat rotating mechanism 267 that is a rotating means for rotating the boat 17 is provided, and the boat 217 held by the quartz cap 218 is rotated by rotating the boat rotating mechanism 267.

The controller 121, which is a control means, includes a liquid mass flow controller 240, first to third mass flow controllers 241a, 241b, 241c, and first to fifth valves 243.
a, 243b, 243c, 243d, 243e, heater 207, vacuum pump 246, boat rotation mechanism 267, boat lifting mechanism not shown in the figure, connected to liquid mass flow controller 240, first to fourth mass flow controllers 241a, 241b, 241c flow rate adjustment, first to fourth valves 243a, 243b, 243c, 243d open / close operation, fifth valve 243e open / close and pressure adjustment operation, heater 207 temperature adjustment, vacuum pump 246
Is started / stopped, the rotation speed of the boat rotating mechanism 267 is adjusted, and the lifting / lowering operation of the boat lifting / lowering mechanism is controlled.

<Process furnace operation and film formation example>
Next, an example of film formation by the ALD method will be described using an example in which an HfO ₂ film is formed using TEMAH and O 3.

First, a wafer 200 to be deposited is loaded into a boat 217 and loaded into a processing furnace 202. After carrying in, the following three steps are sequentially executed.

[Step 1]
In Step 1, TEMAH and carrier gas (N ₂ ) are flowed. First, the first gas supply pipe 2
A first valve 243a provided on the first gas supply line 32a and a third valve provided on the first carrier gas supply pipe 234a;
And the fifth valve 243e provided in the gas exhaust pipe 231 are both opened,
The flow rate is adjusted by the liquid mass flow controller 240 from the first gas supply pipe 232a,
From the TEMAH vaporized by the vaporizer 242 and the first carrier gas supply pipe 234a, the second
The gas exhaust pipe 2 is mixed with the carrier gas whose flow rate is adjusted by the mass flow controller 241b of the first nozzle 233a and supplied to the processing furnace 202 from the first gas supply hole 248a of the first nozzle 233a.
31 is exhausted. The supply flow rate of TEMAH controlled by the liquid mass flow controller 240 is 0.01 to 0.1 g / min. Time to expose wafer 200 to TEMAH gas is 30
~ 180 seconds. At this time, the temperature of the heater 207 is set so that the wafer becomes 180 to 250 ° C.

[Step 2]
In step 2, the first valve 243a of the first gas supply pipe 232a and the third valve 243c of the first carrier gas supply pipe 234a are closed to stop the supply of TEMAH and carrier gas. The fifth valve 243e of the gas exhaust pipe 231 is kept open and the vacuum pump 2
46, the processing furnace 202 is evacuated to 20 Pa or less, and residual TEMAH is removed from the processing furnace 202. At this time, if an inert gas such as N ₂ is supplied to the processing furnace 202, the effect of eliminating residual TEMAH is further enhanced.

[Step 3]
In step 3, O ₃ and carrier gas (N ₂ ) are flowed. First, the second gas supply pipe 232b
The second valve 243b provided at the second and the fourth valve 243d provided at the second carrier gas supply pipe 234b are both opened, and the flow rate is adjusted by the first mass flow controller 241a from the second gas supply pipe 232b. ₃ and the carrier gas whose flow rate is adjusted by the third mass flow controller 241c are mixed from the second carrier gas supply pipe 234b, and the gas is supplied to the processing furnace 202 from the second gas supply hole 248b of the second nozzle 233b. Exhaust from the exhaust pipe 231. The time for exposing the wafer 200 to O ₃ is 10 to 120 seconds. The wafer temperature at this time is 180 to 250 ° C. as in the case of supplying the TEMAH gas. By supplying O ₃ , TEMAH and O ₃ on the base film react with each other, and an HfO film is formed on the wafer 200. After film formation, the second valve 243b and the fourth valve 243d are closed and the vacuum pump 246 is closed.
Thus, the processing furnace 202 is evacuated to eliminate the gas after contributing to the remaining O ₃ film formation.
At this time, if an inert gas such as N ₂ is supplied to the processing furnace 202, the effect of removing the remaining gas from the processing furnace 202 after contributing to the film formation of O ₃ is enhanced.

Steps 1 to 3 are defined as one cycle, and this cycle is repeated a plurality of times to form a HfO film having a predetermined thickness on the wafer.

<Example>
A preferred embodiment of the present invention will be described with reference to the drawings. 5 to 10, the first carrier gas is a carrier gas mixed with the first raw material, and the second carrier gas is a carrier gas mixed with the second raw material.

(1) An embodiment in which the flow rate of the carrier gas is changed from a small amount to a large amount (FIG. 5).
The flow rate of the carrier gas mixed with the first raw material and / or the second raw material is small in the first half,
The second half changes a lot. Thereby, the first half of the supply of the first raw material and / or the second raw material adsorbs the raw material around the outer extension of the substrate, and the latter half adsorbs the raw material around the central portion of the substrate.

(2) An embodiment in which the flow rate of the carrier gas is changed from a large amount to a small amount (FIG. 6).
Contrary to the above-described embodiment (1), the flow rate of the carrier gas mixed with the first raw material and / or the second raw material is changed to a large amount in the first half and a small amount in the second half. Thereby, the first half of the supply of the first raw material and / or the second raw material adsorbs the raw material around the central portion of the substrate, and the second half adsorbs the raw material around the extended portion of the substrate.

(3) An embodiment in which the flow rate of the carrier gas is changed in three stages or more (FIG. 7).
Although the change in the flow rate of the carrier gas in the above-described embodiments (1) and (2) was two steps, in this method, the flow rate of the carrier gas mixed into the first raw material and / or the second raw material is set in three steps. Change to above. As a result, the beginning of the supply of the first raw material and / or the second raw material is centered on the outer extension of the substrate, the middle is centered around the middle between the outer extension and the center of the substrate, and the final is the center of the substrate. The raw material is adsorbed around the center.

(4) An embodiment in which the flow rate of the carrier gas is changed linearly (FIG. 8).
In the above-described embodiments (1) to (3), the flow rate of the carrier gas is changed stepwise, but in this method, the flow rate of the carrier gas mixed with the first raw material and / or the second raw material is linear. Change. As a result, the part where the density of the raw material molecules is high on the substrate is gradually changed from the extended part to the central part, and the raw material is adsorbed on the entire surface of the substrate.

(5) Embodiment in which the flow rate of the carrier gas is changed from a small amount to a large amount and from a large amount to a small amount again (FIG. 9).
).
In the above-described Examples (1) to (4), the change in the flow rate of the carrier gas was from a small amount to a large amount or vice versa. In this method, the carrier mixed with the first raw material and / or the second raw material is used. Change the gas flow rate from small to large and from large to small again. Thus, at the beginning of the supply of the first raw material and / or the second raw material, the initial stage is centered on the outer extension of the substrate, the middle stage is centered on the central part of the substrate, and the final stage is again centered on the outer extension of the substrate. Adsorb.

(6) Embodiment in which the flow rate of the carrier gas is changed from a large amount to a small amount and from a small amount to a large amount again (FIG. 1).
0).
Contrary to the above-described embodiment (5), in this method, the flow rate of the carrier gas mixed with the first raw material and / or the second raw material is changed from a large amount to a small amount, and again from a small amount to a large amount again. Thereby, the beginning of the supply of the first raw material and / or the second raw material is centered on the central portion of the substrate,
In the middle plate, the raw material is adsorbed around the extended portion of the substrate, and in the final plate, the central portion of the substrate is again adsorbed.

As described above, according to a preferred embodiment of the present invention, it is possible to solve the problem that in-plane uniformity with a sufficient film thickness cannot be obtained even when a ring boat is used in some film types in the ALD method.

That is, conventionally, the flow rate of the carrier gas mixed at the time of supplying the raw material is constant, but when the flow rate of the carrier gas is changed, the following change appears in the in-plane distribution of the film thickness.

When the flow rate of the carrier gas is small, the distribution of the film thickness is such that the outer extension part of the substrate is thick and the central part is thin. This is because the total amount of raw material and carrier gas is small, so the raw material does not enter the central part, the density of the raw material molecules on the substrate is lower in the central part than the extended part, and the adsorbed amount of raw material molecules in the extended part of the substrate is This is thought to increase.

On the other hand, when the flow rate of the carrier gas is increased, the distribution of the film thickness is such that the outer extension portion of the substrate is thin and the central portion is thick. This is because the total amount of raw material and carrier gas is large, so that the raw material enters the central part, the density of raw material molecules on the substrate is higher in the central part than in the outer extension part, and the amount of raw material molecules adsorbed in the central part of the substrate is large. It is thought to be.

Taking Example (1) as an example, the phenomenon that the in-plane distribution of the film thickness changes depending on the flow rate of the carrier gas mixed with the raw material is used, and the first raw material and / or the second raw material in each period of the ALD method is used. When the raw material is supplied, the flow rate of the carrier gas mixed with the first raw material and / or the second raw material is changed so that the first half is a small amount and the second half is a large amount.
As a result, the first half of the first raw material and / or the second raw material at the time of supplying the first raw material adsorbs the raw material around the outer extension of the substrate, and the second half adsorbs the raw material around the central portion of the substrate. The unevenness of adsorption on the substrate at the time of supplying the raw material and / or the second raw material is eliminated, the in-plane uniformity of each layer to be laminated is improved, and the in-plane uniformity of the film finally formed is increased. can get.

FIG. 1 is a schematic configuration diagram of a vertical substrate processing apparatus according to an embodiment of the present invention, and is a view showing the substrate processing apparatus in an external perspective view. FIG. 2 is a side view of the substrate processing apparatus shown in FIG. FIG. 3 is a schematic configuration diagram of a vertical substrate processing furnace according to the embodiment of the present invention, and is a view showing a processing furnace part in a vertical section. 4 is a cross-sectional view of the processing furnace portion of the substrate processing furnace shown in FIG. FIG. 5 is a diagram showing an embodiment of the present invention. FIG. 6 is a diagram showing an embodiment of the present invention. FIG. 7 shows an embodiment of the present invention. FIG. 8 is a diagram showing an embodiment of the present invention. FIG. 9 is a diagram showing an embodiment of the present invention. FIG. 10 is a diagram showing an embodiment of the present invention.

Explanation of symbols

100 pod 101 housing 102 N ₂ purge chamber 105 I / O stage 106 the substrate alignment apparatus 108 opener 109 cassette shelf 112 wafer loader 114 cassette loader 115 boat elevator 116 furnace port shutter 121 controller 200 wafer 202 processing furnace 203 reaction tube 207 heater 217 boat 218 quartz cap 219 seal cap 220 O-ring 231 gas exhaust tube 232a first gas supply tube 232b second gas supply tube 233a first nozzle 233b second nozzle 234a first carrier gas Supply pipe 234b Second carrier gas supply pipe 240 Liquid mass flow controller 241a First mass flow controller 241b Second mass flow controller 241c Third mass flow controller Controller 242 carburetor 243a first valve 243b second valve 243c third valve 243d fourth valve 243e fifth valve 246 vacuum pump 248a first gas supply holes 248b second gas supply hole 267 boat rotation mechanism

Claims (1)

A method of manufacturing a semiconductor device, wherein at least a first processing gas and a second processing gas are alternately supplied into a processing chamber, and a desired film is formed on a substrate surface,
Supplying the first processing gas into the processing chamber;
Removing the first processing gas remaining in the processing chamber from the processing chamber;
Supplying the second processing gas into the processing chamber;
Removing the second processing gas remaining in the processing chamber from the processing chamber;
Including
At least in any one of the first processing gas supply step and the second processing gas supply step, a carrier gas is supplied simultaneously with the processing gas, and the supply amount of the carrier gas is changed and supplied. A method for manufacturing a semiconductor device.

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