JP2004119486A - Substrate processor and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade troubles in valve mechanism, valveless mechanism, etc. and perform quickly change of two or more kinds of reactant gasses. <P>SOLUTION: A substrate processor is provided with a treatment room 20 for treating a wafer 20, a material gas charging line 21 whose one end is connected with the room 20, a vaporizer 22 which is connected with the other end of the line 21 and evaporates the liquid material, and a liquid material control unit 23 for controlling the amount of supply of liquid material to be supplied to the the vaporizer 22. The control unit 23 is constituted of a screw feeder 50 or a dispenser 70 which spout liquid material to the vaporizer 22. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device and a substrate processing apparatus used for implementing the method, and more particularly to a technique using a source gas generated by vaporizing a liquid source.
[0002]
[Prior art]
In recent years, with the lowering of the film forming temperature, a method of forming films one by one, such as ALD (Atomic Layer Deposition), from CVD film formation by thermal decomposition has been adopted. In the case of forming an atomic layer, for example, it is necessary to switch the reaction gas every time one CVD film is formed.
[0003]
A valve mechanism is known for switching the reaction gas. FIG. 3 shows an example in which two types of reaction gases A and B are alternately flown into the processing chamber 7 by a valve mechanism.
[Reaction gas A supply step]
The reaction gas A flows into the processing chamber 7 under the condition that the valves 1 and 3 are closed and the valve 2 is opened. At this time, the reaction gas B flows to the vent side by opening the valve 4 and closing the valve 5. Further, at this time, the valve 6 is opened, so that the N ₂ gas flows from the supply line of the reaction gas B to the processing chamber 7.
[Reaction gas B supply step]
On the other hand, the reaction gas B flows to the processing chamber 7 under the condition that the valves 4 and 6 are closed and the valve 5 is opened. At this time, the reaction gas A flows to the vent side by opening the valve 1 and closing the valve 2. Further, at this time, by opening the valve 3, the N ₂ gas flows from the supply line of the reaction gas A to the processing chamber 7. The supply amounts of the reaction gases A and B can be controlled by the opening degrees of the valves 2 and 5, respectively.
[0004]
4 shows a reaction gas A, shows B, and the timing chart of the N ₂ gas supply. First, in the reaction gas A supply step, the reaction gas A is introduced into the processing chamber 7 ((1)). Then, the processing chamber 7 is purged by the _{N 2} gas (▲ 2 ▼). Next, in the reaction gas B supply step, the reaction gas B is introduced into the processing chamber 7 ((3)). Next, the processing chamber 7 is purged again with N ₂ gas ((4)). The introduction of each gas is repeated with these four steps (1) to (4) as one cycle.
[0005]
Further, a valveless mechanism is also known for switching the reaction gas. In this method, ON / OFF of each gas is performed by using a flow rate of N ₂ gas without using a valve. As an example, FIG. 5 shows that the reaction gas A is turned on / off using a valveless mechanism.
In FIG. 5, _{N 2} gas introduced from the first _{N 2} gas inlet 8, MFC through the (mass flow controller) 9, flows into the vent line 10 and the main supply pipe 11. The reaction gas A introduced from the reaction gas introduction part 12 flows to the processing chamber 7 through the main supply pipe 11. _{N 2} gas introduced from the second _{N 2} gas inlet 13, flows through the MFC14 to the main supply pipe 11. However, the N ₂ gas is introduced into the main supply pipe 11 in a direction against the flow of the reaction gas A.
[0006]
Then, as shown in FIG. 5A, when it is desired to introduce the reaction gas A into the processing chamber 7, the flow rate in the MFC 14 is set to a predetermined value or less. Thereby, the reaction gas A overcomes the flow of the N ₂ gas introduced into the main supply pipe 11 and flows down the main supply pipe 11 to reach the processing chamber 7. At this time, by setting the flow rate in the MFC 9 to an appropriate value, the reaction gas A flowing through the main supply pipe 11 is prevented from escaping to the vent 10 side.
On the other hand, as shown in FIG. 5B, when the reaction gas A is not introduced into the processing chamber 7, the flow rate in the MFC 14 is set to a predetermined value or more. Thus, the flow of the N ₂ gas introduced into the main supply pipe 11 through the MFC 14 prevents the flow of the reaction gas A in the main supply pipe 11 from flowing down. Therefore, the reaction gas A does not flow to the processing chamber 7 but escapes to the vent 10 side. At this time, by setting the flow rate in the MFC 9 to a predetermined flow rate or less, it is possible to prevent the reaction gas A from flowing to the vent 10 side.
Therefore, the reaction gas A can be intermittently introduced into the processing chamber 7 by alternately repeating the state of FIG. 5A and the state of FIG. 5B.
[0007]
[Problems to be solved by the invention]
The prior art has the following problems. That is, when the valve mechanism is used, the number of times of opening and closing each of the valves 1 to 6 is about 500 times when, for example, a film formation process of 50 nm is performed in the processing chamber 7. Therefore, the load applied to each of the valves 1 to 6 is large, and there is a problem that the life of these valves is exhausted in several months. In addition, the cost required for replacing the valve is high, which is a major obstacle to atomic layer deposition.
[0008]
On the other hand, in the case of using a valveless mechanism, although the problem caused by the valve can be avoided, it is difficult to control the supply amount of the reaction gas, and when the pressure balance between the reaction gas and the N ₂ gas is lost, a sealing function is provided. There is a problem that is lost. Specifically, for example, in FIG. 5B, if the flow rate in the MFC 14 is too small, the reaction gas A that should not normally flow into the processing chamber 7 leaks into the processing chamber 7. Further, in the case where a plurality of types of reaction gases are switched using a valveless mechanism, there is a problem that mixing of the reaction gases cannot be avoided at the time of the switching.
[0009]
In addition, in the method in which the reaction gas is switched every time one film is formed as described above, it is an important issue how to switch the reaction gas in a short time in order to improve the processing efficiency as much as possible. Specifically, for example, when performing atomic layer deposition, the time per cycle (n1 + n2 + n3 + n4) is 4 seconds or less and the time (n1, n2, n3, n4) of each process is 1 second or less in FIG. Is required.
[0010]
An object of the present invention is to provide a technique capable of avoiding the problems in the valve mechanism, the valveless mechanism, and the like, and rapidly switching a plurality of types of reaction gases.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, a processing chamber for processing a substrate, a source gas supply pipe having one end connected to the processing chamber, and a source connected to the other end of the source gas supply pipe for vaporizing the liquid source A vaporizer, and a liquid raw material control unit for controlling a supply amount of a liquid raw material supplied to the vaporizer, wherein the liquid raw material control unit has a screw feeder or a dispenser for discharging the liquid raw material to the vaporizer. A substrate processing apparatus is provided. Examples of the substrate include a semiconductor substrate such as a silicon wafer and a glass substrate.
[0012]
In the first aspect, a raw material gas is generated by vaporizing a liquid raw material in a vaporizer. Supply / stop of the raw material gas to the processing chamber can be realized by driving / stopping a screw feeder or a dispenser. The supply amount of the raw material gas can be controlled by the driving rate per unit time of the screw feeder or the dispenser. If the screw feeder or the dispenser is stopped, the supply of the liquid raw material is stopped, and the generation of the raw material gas is also stopped, so that the raw material gas does not leak to the processing chamber, and the gas supplied to the processing chamber while maintaining the sealing function. Can be immediately switched to another gas.
[0013]
According to the second aspect of the present invention, a processing chamber for processing a substrate, a source gas supply pipe having one end connected to the processing chamber, and a liquid source connected to the other end of the source gas supply pipe to vaporize the liquid source And a liquid material control unit for controlling a supply amount of the liquid material supplied to the vaporizer, wherein the liquid material control unit discharges the liquid material to the vaporizer in a pulsed manner at predetermined intervals. And a substrate processing apparatus characterized by having a discharge means for performing the discharge. The discharge means can be constituted by a screw feeder or a dispenser.
[0014]
In the second aspect, the supply amount of the source gas to the processing chamber can be determined by the supply amount of the liquid source per discharge by the discharge unit and the number of discharges per unit time. In this way, the supply amount of the source gas can be adjusted irrespective of the valve opening. When the discharging operation of the liquid material by the discharging means is stopped, the generation of the raw material gas is also stopped, so that the raw material gas does not leak to the processing chamber, and the gas supplied to the processing chamber is immediately separated while maintaining the sealing function. Gas can be switched.
[0015]
According to the third aspect of the present invention, a processing chamber for processing a substrate, a source gas supply pipe having one end connected to the processing chamber, and a source connected to the other end of the source gas supply pipe for vaporizing the liquid source A vaporizer, wherein a plurality of liquid material supply units for supplying a liquid material to the vaporizer are connected to the vaporizer, wherein each of the liquid material supply units is connected to the liquid material. And a dispenser for discharging the substrate to the vaporizer.
[0016]
In the third aspect, the switching of the liquid source to be supplied to the vaporizer can be quickly performed by driving / stopping the screw feeder or the dispenser constituting each liquid source supply unit. In this case, it is preferable to supply the inert gas to the vaporizer from the liquid material supply unit that does not discharge the liquid material.
[0017]
According to a fourth aspect of the present invention, a step of supplying a liquid raw material to a vaporizer by a screw feeder or a dispenser, a step of generating a raw material gas by vaporizing the supplied liquid raw material by the vaporizer, Supplying the raw material gas to the substrate, thereby processing the substrate.
[0018]
According to the fifth aspect of the present invention, a liquid source supply step of supplying a liquid source to a vaporizer, a source gas generation step of generating a source gas by vaporizing the supplied liquid source with the vaporizer, Supplying the generated raw material gas to the substrate, thereby processing the substrate. In the liquid raw material supplying step, the liquid raw material is supplied to the vaporizer in a pulsed manner at predetermined intervals. There is also provided a method of manufacturing a semiconductor device characterized by the following.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a substrate processing apparatus according to an embodiment. This is a single wafer type CVD apparatus. The substrate processing apparatus includes a processing chamber 20 for processing a wafer W, a source gas supply pipe 21 having one end connected to the processing chamber 20, and a source gas supply pipe 21 connected to the other end of the source gas supply pipe 21 for vaporizing a liquid source. And a liquid source control unit 23 that controls the supply amount of the liquid source supplied to the vaporizer 22. The greatest feature of the substrate processing apparatus is that the liquid material control unit 23 includes a screw feeder (see FIG. 2A) 50 for discharging the liquid material to the vaporizer 22.
[0020]
A heater 24 is provided in the processing chamber 20. A susceptor 25 is arranged on the heater 24, and the wafer W is mounted on the susceptor 25. The wafer W is heated to a predetermined temperature by the heater 24. Outside the processing chamber 20, a rotation unit 26 is provided. When the heater 24 is rotated by the rotation unit 26, the susceptor 25 and the wafer W on the heater 24 are rotated.
[0021]
In the processing chamber 20, a shower head 27 having a large number of holes 271, 271 is provided above the susceptor 25. The shower head 27 is partitioned by a partition plate 28 into a film-forming shower head 27a and a radical shower head 27b. A source gas supply pipe 21 for supplying an inert gas and / or a source gas is connected to the film forming shower head 27a. A radical supply pipe 34 described later is connected to the radical shower head 27b.
On the other hand, an exhaust port 29 for exhausting the inside of the processing chamber 20 is formed at a predetermined position in the processing chamber 20. An exhaust pipe 30 is connected to the exhaust port 29, and a raw material recovery trap 31 is provided in the exhaust pipe 30.
[0022]
Outside the processing chamber 20, a radical generating unit 32 for generating radicals is provided. A tube through which radicals generated by the radical generating unit 32 pass is connected to the radical generating unit 32. The pipe is bifurcated on the way to the downstream, and one of the branched pipes is a radical supply pipe 34 connected to the radical shower head 27b via a valve 33, and the other pipe is a The bypass pipe 36 is connected to the raw material recovery trap 31 via the valve 35.
[0023]
A vaporizer 22 is connected to the other end of the source gas supply pipe 21 whose one end is connected to the film forming shower head 27a of the processing chamber 20. In addition, the raw material gas supply pipe 21 may be provided with a pipe heater over the entire length. The vaporizer 22 includes a chamber 22a that forms a vaporization chamber, and a heater 22b that heats an inner wall of the chamber 22a.
[0024]
An outlet 36 and an inlet 37 are formed in the chamber 22a. The source gas supply pipe 21 is connected to the outlet 36. On the other hand, a liquid material introduction pipe 38 and an inert gas introduction pipe 39 are connected to the introduction port 37. The connecting portions of these pipes 38 and 39 to the inlet 37 have a double pipe structure in which the inert gas introducing pipe 39 is an outer pipe and the liquid raw material introducing pipe 38 is an inner pipe. Further, the tip of the liquid material introduction pipe 38 is a spray nozzle 38a.
[0025]
The liquid material control section 23 is connected to the other end of the liquid material introduction pipe 38 whose one end is connected to the introduction port 37. The other end of the inert gas introduction pipe 39 whose one end is connected to the introduction port 37 is connected to an inert gas supply unit 41 via a valve 40. The inert gas supply unit 41 supplies N ₂ gas as an inert gas. Note that Ar, He, or the like can be used as the inert gas.
[0026]
Next, the configuration of the liquid material control unit 23 will be described with reference to FIG. FIG. 2A shows a main configuration of the liquid raw material control unit 23. The liquid raw material control unit 23 includes a screw feeder 50 and a control unit 60. The screw feeder 50 has a cylindrical casing 53 having one end serving as a liquid raw material charging section 51 and the other end serving as a liquid raw material discharging section 52, and a rotation extending to a cylinder core in the cylindrical casing 53. A shaft 54 and a screw blade 55 that is spirally mounted on the rotating shaft 54 and rotates integrally with the rotating shaft 54 are provided. The screw blade 55 and the inner peripheral wall of the casing 53 are in airtight contact with each other, and the liquid raw material introduced between the screw blade 55 and the casing 53 is sequentially sent to the discharge unit 52 side with the rotation of the rotating shaft 54. It is going to go. Note that the discharge unit 52 is connected to the nozzle 38a.
[0027]
The controller 60 adjusts the supply amount of the liquid raw material according to the number of rotations of the rotating shaft 54. Here, the control unit 60 can also perform pulse control of the rotation speed of the rotation shaft 54. In this case, assuming that the number of rotation pitches of the screw blade 55 per pulse is n, the liquid raw material for one shot is kept airtight in the space S between the screw blade 55 and the casing 53 over n pitches. become. Then, by the pulse control by the control unit 60, the liquid raw material can be discharged to the vaporizer 22 in a pulsed manner for each predetermined amount (one shot of the liquid raw material). Therefore, in this case, the supply amount of the raw material gas to the processing chamber 20 can be determined by the amount of the liquid raw material for one shot and the number of discharges per unit time (the number of rotations of the rotating shaft 54).
[0028]
Note that the liquid material control unit 23 can also be configured by a dispenser 70 and a control unit 80, as shown in FIG. The dispenser 70 includes a syringe 73 having a filling portion S in which a liquid material input port 71 and a discharge port 72 are formed and filled with one shot of the liquid material, and a filling device S filled in the filling portion S of the syringe 73. A piston 74 for discharging a shot of liquid material from the discharge port 72; Note that the discharge unit 72 is connected to the nozzle 38a.
[0029]
FIG. 2B shows a state where the piston 74 is located at the top dead center. When the piston 74 is located at the bottom dead center, the piston 74 closes the inlet 71. That is, when the piston 74 is located at the top dead center, the liquid material is supplied from the charging port 71, and the filling section S is filled with the liquid material for one shot. Next, when the piston 74 descends to the bottom dead center, the liquid material filled in the filling section S is pushed out from the discharge port 72. Such an operation is repeated.
The control unit 80 adjusts the supply amount of the liquid raw material according to the number of operations of the piston 74.
Also in this case, the control unit 80 can discharge the liquid raw material to the vaporizer 22 in a pulsed manner for each predetermined amount (one shot of the liquid raw material).
[0030]
Hereinafter, a process of forming, for example, an HfO ₂ film by MOCVD (Metal Organic Chemical Vapor Deposition) using the present substrate processing apparatus as one step of a semiconductor device manufacturing process will be described.
It is assumed that the valve 33 is closed and the valve 35 is open. First, the valve 40 is opened, and only the N ₂ gas from the inert gas supply unit 41 flows into the processing chamber 20 for a predetermined period. Thereafter, the wafer W is placed on the susceptor 25, and then heated to a predetermined film forming temperature (for example, 350 to 500 ° C.) by the heater 24 while rotating the wafer W by the rotation unit 26.
[0031]
[Raw material supply process]
Next, the liquid raw material controller 23 supplies the liquid raw material to the vaporizer 22 until the valve 40 is opened. Specifically, it drives the screw feeder 50 or the dispenser. Then, the liquid raw material discharged from the liquid raw material control unit 23 is sprayed from the spray nozzle 38a, and is stirred by an inert gas (here, N ₂ gas) as a surrounding carrier gas, and instantaneously in the vaporizer 21. Vaporize. As a result, a source gas is generated. At this time, the vaporizer 21 is heated to, for example, 150C to 250C. Here, Hf (OC (CH ₃ ) ₂ CH ₂ OCH ₃ ) ₄ can be used as the liquid raw material.
[0032]
The generated source gas is supplied from the film-forming shower head 27a onto the wafer W in a shower shape. The source gas is supplied at a rate of, for example, 0.1 g / min for about 10 seconds.
During this raw material supply step and the RPO processing step to be described later, the valve 40 is kept open, and N ₂ gas is always flowed.
[0033]
[First N ₂ supply step]
Next, the supply of the liquid material in the liquid material control unit 23 is stopped. Specifically, the driving of the screw feeder 50 or the dispenser is stopped. Thereby, only the N ₂ gas supplied from the inert gas supply unit 41 is supplied to the processing chamber 20 via the vaporizer 21 and the raw material gas supply pipe 21. Thereby, the inside of the processing chamber 20 is purged.
[0034]
[RPO processing step]
Next, an RPO (Remote Plasma Oxidation) process is performed. The RPO process refers to a process of oxidizing a film in an oxygen radical atmosphere in which an oxygen-containing gas (for example, O ₂ , N ₂ , O, NO) is decomposed by plasma. Specifically, first, the valve 33 is opened, while the valve 35 is closed. Thereby, oxygen radicals generated in the radical generating unit 32 are supplied from the radical shower head 27b onto the wafer W in a shower shape. The supply of oxygen radicals is performed, for example, for 15 seconds.
[0035]
When the oxygen radicals are supplied to the unreacted source gas adhering to the wafer W, a reaction for forcibly forming the HfO ₂ film occurs. Therefore, the HfO ₂ film is deposited on the wafer W by several to several tens of degrees.
[0036]
[Second N ₂ supply step]
Next, the valve 33 is closed while the valve 35 is opened. Thereby, oxygen radicals generated in the radical generating unit 32 are exhausted to the raw material recovery trap 31 via the bypass pipe 36 without passing through the inside of the processing chamber 20. In this manner, during the processing of the substrate W, the flow of the radicals in the radical generating unit 32 can be constantly stopped without stopping.
At this time, only the N ₂ gas supplied from the inert gas supply unit 41 is supplied to the processing chamber 20 via the vaporizer 21 and the source gas supply pipe 21. Thereby, the inside of the processing chamber 20 is purged.
[0037]
By repeatedly performing the above-described raw material supply step to the second N ₂ supply step, an HfO ₂ film having a desired thickness can be formed.
[0038]
In the present embodiment, in the substrate processing apparatus having the liquid source supply system for supplying the liquid source to the vaporizer, the supply of the liquid source is performed by the screw feeder 50 or the dispenser 70. can get.
(1) The supply / stop of the raw material gas to / from the processing chamber 20 can be quickly and easily performed only by driving / stopping the screw feeder 50 or the dispenser 70 without using a valve or controlling the flow rate of an inert gas.
(2) The supply amount of the raw material gas can be easily controlled by the driving rate per unit time of the screw feeder 50 or the dispenser 70 without depending on the opening degree of the valve. Since there is no need to use a valve mechanism or a valveless mechanism as described in (1) and (2) above, these problems can be avoided.
(3) When the screw feeder 50 or the dispenser 70 is stopped, the supply of the liquid raw material is stopped, and the generation of the raw material gas is also stopped. Therefore, the raw material gas does not leak to the processing chamber 20 and the sealing function is maintained. The gas supplied to the processing chamber 20 can be immediately switched to oxygen radicals. Thereby, the throughput of the film forming process can be improved.
[0039]
The embodiment of the present invention has been described above, but the present invention is not limited to this. For example, the present invention can be applied to a case where two types of liquid raw materials LA and LB are alternately supplied to the vaporizer from individual liquid raw material supply units A and B, respectively. That is, also in this case, if both the liquid material supply units A and B are configured using the screw feeder 50 or the dispenser 70, respectively, the screw feeders or dispensers constituting the liquid material supply units A and B are driven / synchronized. By stopping the operation, the liquid materials to be supplied to the vaporizer can be quickly switched while the sealing function is maintained well without mixing the two liquid materials in the vaporizer.
[0040]
Further, in this case, it is preferable to supply an inert gas (purge gas, carrier gas) to the vaporizer from the liquid material supply unit that does not discharge the liquid material. That is, when the liquid raw material is supplied from one liquid raw material supply section A (B) to the reaction chamber, it is preferable to flow the purge gas from the other liquid raw material supply section B (A) to the vaporizer. Then, the gas of the liquid material LA (LB) vaporized in the vaporizer can be prevented from flowing into the liquid material supply unit B (A).
[0041]
As the liquid _{material, Hf (OC (CH 3)} 3) 4, Hf (O-Si- (CH 3)) 4, Hf for forming a _{HfO 2 (OC 4 H 9)} 4 ( Tetra butoxy Haufuniumu), Ta for forming the _{Ta 2 O 5 (OC 2 H} 5) 5 ( penta-ethoxy-tantalum), Nb for forming a NbO ₅ (niobium pentoxide) _(OC 2 H5) ₅ (pentaethoxyniobium), Ti (OC ₃ H ₇ ) ₄ (tetra-isopropyl-titanium) for forming TiOx (titanium oxide), and Zr (for forming ZrO ₂ (zirconium dioxide). OC ₄ H ₉ ) ₄ (tetra-butoxy-zirconium) or the like can also be used.
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while being able to avoid the problem in a valve mechanism, a valveless mechanism, etc., switching of several types of reaction gases can be performed quickly.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a substrate processing apparatus according to an embodiment.
FIGS. 2A and 2B are diagrams illustrating a main configuration of a liquid material control unit according to the embodiment, in which FIG. 2A illustrates a screw feeder, and FIG. 2B illustrates a dispenser.
FIG. 3 is a schematic diagram for explaining a conventional valve mechanism.
FIG. 4 is a diagram showing a timing chart of each gas in a conventional valve mechanism.
FIG. 5 is a schematic diagram for explaining a conventional valveless mechanism.
[Explanation of symbols]
Reference numeral 20: processing chamber, 21: source gas supply pipe, 22: vaporizer, 23: liquid source control unit (liquid source supply unit), 50: screw feeder (discharge unit), 70: dispenser (discharge unit), W: wafer (substrate).

Claims (2)

A processing chamber for processing substrates,
A source gas supply pipe having one end connected to the processing chamber,
A vaporizer connected to the other end of the raw material gas supply pipe and vaporizing the liquid raw material;
A liquid material control unit that controls the supply amount of the liquid material supplied to the vaporizer,
The substrate processing apparatus, wherein the liquid material control unit includes a screw feeder or a dispenser that discharges the liquid material to the vaporizer. A step of supplying a liquid raw material to a vaporizer by a screw feeder or a dispenser,
Vaporizing the supplied liquid raw material with the vaporizer to generate a raw material gas;
Supplying the generated source gas to the substrate to process the substrate.

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