阅读说明：本技术 热处理装置和成膜方法 (Heat treatment apparatus and film forming method ) 是由 小原一辉 山口达也 菊池康晃 草岛龙司 名须川信也 菊池一行 于 2020-03-10 设计创作，主要内容包括：本发明所要解决的技术问题在于：提供一种能够改善大流量处理中的温度均匀性的技术。本发明解决技术问题的方法在于：本发明的一个方式的热处理装置具有：多段收纳多个基板并进行处理的可减压的处理容器；对上述处理容器内的上述基板进行加热的第一加热器；向上述处理容器内的高度不同的位置供给气体的多个气体供给管；和设置于上述多个气体供给管中的向最下方位置供给气体的气体供给管并对上述气体进行加热的第二加热器。(The technical problem to be solved by the invention is as follows: provided is a technique capable of improving temperature uniformity in large-flow processing. The method for solving the technical problem of the invention comprises the following steps: a heat treatment apparatus according to an embodiment of the present invention includes: a processing container capable of reducing pressure for storing and processing a plurality of substrates in multiple stages; a first heater for heating the substrate in the processing container; a plurality of gas supply pipes for supplying gas to positions having different heights in the processing container; and a second heater provided in a gas supply pipe that supplies a gas to a lowermost position among the plurality of gas supply pipes, and configured to heat the gas.)

1. A heat treatment apparatus comprising:

a processing container capable of reducing pressure for storing and processing a plurality of substrates in multiple stages;

a first heater for heating the substrate in the processing container;

a second heater provided in a gas supply pipe that supplies a gas to a lowermost position among the plurality of gas supply pipes, and configured to heat the gas; and

and a second heater provided in a gas supply pipe for supplying a gas to a lowermost position among the plurality of gas supply pipes, and configured to heat the gas.

2. The thermal processing apparatus of claim 1, wherein:

the second heater is provided in 2 or more of the plurality of gas supply pipes.

3. The heat treatment apparatus according to claim 1 or 2, wherein:

the plurality of gas supply pipes are configured to supply the same gas.

4. The heat treatment apparatus according to any one of claims 1 to 3, wherein:

the gas is a purge gas.

5. A film forming method is characterized in that:

depositing a reaction product of a first reactive gas and a second reactive gas on a substrate by alternately supplying the first reactive gas and the second reactive gas into a process container accommodating the substrate with a purge gas interposed therebetween,

at least 1 of the first reactive gas, the second reactive gas and the purge gas is supplied by heating the gases.

6. The film forming method according to claim 5, wherein:

the gas is supplied into the processing container from a plurality of gas supply pipes at the same time.

7. The film forming method according to claim 6, wherein:

a plurality of substrates are accommodated in the processing container in a plurality of stages,

the plurality of gas supply pipes supply gas to positions having different heights in the processing container.

8. The film forming method according to claim 7, wherein:

the temperature of the gas supplied from one of the plurality of gas supply pipes is higher than the temperature of the gas supplied from another gas supply pipe that supplies the gas to a position above the one gas supply pipe.

9. The film forming method according to any one of claims 5 to 8, wherein:

at least 1 of the first reactive gas, the second reactive gas, and the purge gas is the purge gas.

10. The film forming method according to any one of claims 5 to 8, wherein:

the second reaction gas is a nitriding gas or an oxidizing gas,

at least 1 of the first reactive gas, the second reactive gas, and the purge gas is the second reactive gas.

Technical Field

The present invention relates to a heat treatment apparatus and a film forming method.

Background

The following techniques are known: before supplying the process gas into the process container, the process gas is preheated to a predetermined temperature by a heater provided outside the process container, and the activated and heated process gas is supplied into the process container (see, for example, patent document 1).

Disclosure of Invention

Technical problem to be solved by the invention

The invention provides a technique capable of improving temperature uniformity in large-flow processing.

Technical solution for solving technical problem

A heat treatment apparatus according to an embodiment of the present invention includes: a processing container capable of reducing pressure for storing and processing a plurality of substrates in multiple stages; a first heater for heating the substrate in the processing container; a plurality of gas supply pipes for supplying gas to positions having different heights in the processing container; and a second heater provided in a gas supply pipe that supplies a gas to a lowermost position among the plurality of gas supply pipes, and configured to heat the gas.

Effects of the invention

The invention can improve the temperature uniformity in large-flow treatment.

Drawings

Fig. 1 is a sectional view showing an example of the structure of a heat treatment apparatus according to a first embodiment.

Fig. 2 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 1.

FIG. 3 is a flowchart showing an example of the ALD method.

Fig. 4 is a diagram (1) for explaining the effects of the heat treatment apparatus of the first embodiment.

Fig. 5 is a diagram (2) for explaining the effects of the heat treatment apparatus of the first embodiment.

Fig. 6 is a sectional view showing an example of the structure of a heat treatment apparatus according to a second embodiment.

Fig. 7 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 6.

Fig. 8 is a diagram (1) for explaining the effects of the heat treatment apparatus of the second embodiment.

Fig. 9 is a diagram (2) for explaining the effects of the heat treatment apparatus of the second embodiment.

Fig. 10 is a sectional view showing an example of the structure of a heat treatment apparatus according to a third embodiment.

Fig. 11 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 10.

Description of the reference numerals

1A, 1B, 1C heat treatment apparatus

10 treatment vessel

62. 64, 66-1 to 5 gas supply pipes

62c, 64c, 66-1 c-5 c heaters

Detailed Description

Hereinafter, exemplary embodiments not limiting the present invention will be described with reference to the drawings. In all the drawings, the same or corresponding components or parts are denoted by the same or corresponding reference numerals, and redundant description thereof is omitted.

[ first embodiment ]

(Heat treatment apparatus)

A heat treatment apparatus according to a first embodiment will be described. Fig. 1 is a sectional view showing an example of the structure of a heat treatment apparatus according to a first embodiment. Fig. 2 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 1.

The heat treatment apparatus 1A includes a treatment container 10 capable of depressurizing the inside. The processing container 10 accommodates semiconductor wafers (hereinafter, referred to as "wafers W") as substrates.

The processing container 10 has an inner tube 12 having a cylindrical shape with a top portion and an open lower end, and an outer tube 14 having a cylindrical shape with a top portion and an open lower end and covering the outer side of the inner tube 12. The inner tube 12 and the outer tube 14 are made of a heat-resistant material such as quartz, and are coaxially arranged to form a double-tube structure. In the processing container 10, a wafer boat 16 holding a plurality of wafers W in a rack shape (multiple stages) with a predetermined interval in the height direction is carried in and out.

The top of the inner tube 12 is, for example, flat. A nozzle housing 18 for housing a gas supply pipe along the longitudinal direction (vertical direction) is formed on one side of the inner pipe 12. The nozzle housing 18 is formed by forming a protrusion 20 by projecting a part of the side wall of the inner tube 12 outward, and forming the protrusion 20 as the nozzle housing 18. A rectangular opening 22 having a width L1 is formed along the longitudinal direction (vertical direction) of the side wall opposite to the inner tube 12 and facing the nozzle housing portion 18. The width L1 is in the range of about 10mm to 400 mm. The opening 22 is a gas exhaust port formed to be able to exhaust the gas in the inner tube 12.

The lower end of the processing vessel 10 is supported by a cylindrical manifold 30 formed of, for example, stainless steel. A flange 32 is formed at the upper end of the header pipe 30, and the lower end of the outer pipe 14 is supported by the flange 32. A sealing member 34 such as an O-ring is interposed between the flange portion 32 and the lower end of the outer tube 14 to make the inside of the outer tube 14 airtight.

An annular support portion 36 is provided on the inner wall of the upper portion of the manifold 30, and the lower end of the inner tube 12 is provided on the support portion 36 to be supported. A lid 38 is airtightly attached to the opening at the lower end of the manifold 30 via a seal member 40 such as an O-ring, and the opening at the lower end of the processing container 10, that is, the opening of the manifold 30 is airtightly closed. The cover 38 is formed of, for example, stainless steel.

A rotary shaft 44 is provided through the center of the lid 38 via a magnetic fluid seal 42. The lower portion of the rotating shaft 44 is rotatably supported by an arm 48 of an elevating unit 46 formed by a boat elevator, and is rotatable by a motor.

A turntable 50 is provided at the upper end of the rotary shaft 44, and the wafer boat 16 holding the wafers W is placed on the turntable 50 via a quartz heat-insulating table 52. Therefore, by moving the elevating unit 46 up and down, the lid 38 moves up and down integrally with the boat 16, and the boat 16 can be carried into and out of the processing container 10.

The gas supply unit 60A is provided in the manifold 30 and supplies a predetermined gas such as a process gas or a purge gas into the inner pipe 12. The gas supply unit 60A includes a plurality of (e.g., 3) gas supply pipes 62, 64, and 66 made of quartz having the same length. The gas supply pipes 62, 64, and 66 are provided along the longitudinal direction in the inner pipe 12, and have base ends bent in an L-shape and are supported so as to penetrate through the header pipe 30.

As shown in fig. 2, the gas supply pipes 62, 64, 66 are arranged in a row along the circumferential direction in the nozzle housing portion 18 of the inner pipe 12. The gas supply pipes 62, 64, and 66 have a plurality of gas holes 62a, 64a, and 66a formed therein at predetermined intervals along the longitudinal direction thereof. The gas holes 62a, 64a, and 66a discharge the respective gases in the horizontal direction. The predetermined interval is set to be, for example, the same as the interval of the wafers W supported by the boat 16. The height direction position is set so that the gas holes 62a, 64a, and 66a are located at the middle between vertically adjacent wafers W, and the gas can be efficiently supplied to the space between the wafers W. As an example, the gas supply pipe 62 is a nozzle for supplying a first reaction gas, the gas supply pipe 64 is a nozzle for supplying a second reaction gas that reacts with the first reaction gas to form a reaction product, and the gas supply pipe 66 is a nozzle for supplying a purge gas. Examples of the first reactive gas include a silicon-containing gas and a metal-containing gas. Examples of the second reactive gas include a nitriding gas and an oxidizing gas. As the purge gas, for example, an inert gas can be cited.

The gas supply pipes 62, 64, and 66 supply the first reactive gas, the second reactive gas, and the purge gas through the gas pipes 62b, 64b, and 66b, respectively.

The gas pipes 62b, 64b, and 66b are provided with valves (not shown), mass flow controllers (not shown), heaters 62c, 64c, and 66c, and pipe heaters 62d, 64d, and 66d, respectively.

The heaters 62c, 64c, and 66c heat the gas flowing through the gas pipes 62b, 64b, and 66b, respectively. The set temperature of the heaters 62c, 64c, and 66c may be, for example, 100 to 200 ℃.

The pipe heaters 62d, 64d, and 66d suppress a temperature drop of the gas heated by the heaters 62c, 64c, and 66c when the gas flows through the gas pipes 62b, 64b, and 66b, respectively. The set temperature of the pipe heaters 62d, 64d, and 66d may be, for example, the same as the set temperature of the heaters 62c, 64c, and 66c, and may be, for example, 100 to 200 ℃.

A gas outlet 70 is formed in the upper side wall of the header pipe 30 above the support 36, and the gas in the inner pipe 12 discharged from the opening 22 can be discharged through a space 72 between the inner pipe 12 and the outer pipe 14. The gas outlet 70 is provided with an exhaust portion 74. The exhaust portion 74 has an exhaust passage 76 connected to the gas outlet 70. The exhaust passage 76 is provided with a pressure regulating valve 78 and a vacuum pump 80 in this order, and the inside of the processing container 10 can be evacuated.

A cylindrical heater 90 is provided on the outer peripheral side of the outer tube 14 so as to cover the outer tube 14. The heater 90 heats the wafers W stored in the processing container 10. The heater 90 is divided into a plurality of zones, and has 7 heaters 90a to 90g provided from the upper side to the lower side in the vertical direction. Hereinafter, the regions where the heaters 90a, 90b, 90c, 90d, 90e, 90f, and 90g are provided are referred to as "region 1", "region 2", "region 3", "region 4", "region 5", "region 6", and "region 7", respectively. The heaters 90a to 90g are configured to be capable of independently controlling the amount of heat generation by a power controller (not shown).

In fig. 1, the heater 90 is shown as being divided into 7 regions, but the present invention is not limited to this, and may be divided into 6 or less regions or 8 or more regions from the upper side to the lower side in the vertical direction, for example. The heater 90 may be divided into a plurality of zones, or may be constituted by 1 zone.

The overall operation of the heat processing apparatus 1A is controlled by a controller 95 such as a computer. A computer program for executing all operations of the heat processing apparatus 1A is stored in the storage medium 96. The storage medium 96 may be, for example, a floppy disk, a mini disk, a hard disk, a flash memory, a DVD, or the like.

(film Forming method)

As an example of the film formation method by the heat treatment apparatus 1A, a method of forming a silicon nitride film on a wafer W by an Atomic Layer Deposition (ALD) method will be described. FIG. 3 is a flowchart showing an example of the ALD method.

First, the boat 16 holding a plurality of wafers W is carried into the processing container 10 by the elevating unit 46, and the opening at the lower end of the processing container 10 is hermetically closed by the lid 38. Next, the evacuation section 74 evacuates the processing container 10 to a predetermined pressure, and the heater 90 heats the wafers W in the processing container 10 to rotate the boat 16.

Next, a silicon-containing gas from the gas supply pipe 62 (step S1), an inert gas from the gas supply pipe 66 (step S2), a nitriding gas from the gas supply pipe 64 (step S3), and an inert gas from the gas supply pipe 66 are intermittently supplied in this order (step S4). Thus, in the first step S1 of supplying the silicon-containing gas, the silicon-containing gas is adsorbed on the wafer W, and in the next step S2 of supplying the inert gas, the excess silicon-containing gas is purged. Then, in the next step S3 of supplying the nitriding gas, the supplied nitriding gas is reacted with the silicon-containing gas, and the excess nitriding gas is purged in the next step S4 of supplying the inert gas, thereby forming a thin cell film of substantially a monolayer. The series of cycles is performed a predetermined number of times (step S5), and a silicon nitride film having a desired film thickness is formed.

In this way, in the ALD method, the silicon-containing gas and the nitriding gas are alternately supplied into the process container 10 at intervals of the purge gas in a short time. Therefore, in order to supply a predetermined amount of gas for a predetermined time, it is preferable that a large flow rate (for example, 10slm or more) of gas be supplied from the gas supply pipes 62, 64, and 66.

However, in the heat processing apparatus 1A, since each gas is discharged in the horizontal direction from the plurality of gas holes 62a, 64a, and 66a, the gas is supplied from the peripheral edge side to the wafer W, and the gas flows from the peripheral edge portion to the central portion over the wafer W. Therefore, when a large flow rate of gas is supplied into the processing container 10, if the gas discharged from the gas holes 62a, 64a, and 66a is not sufficiently heated, the temperature of the peripheral portion of the wafer W is lowered by the gas. As a result, a temperature difference occurs between the central portion and the peripheral portion of the wafer W, and the in-plane uniformity of the wafer temperature is deteriorated.

In the heat treatment apparatus 1A, the gas flows upward from below in the gas supply pipes 62, 64, and 66 provided along the longitudinal direction in the inner pipe 12. At this time, if the gas supplied to the gas supply pipes 62, 64, 66 is not sufficiently heated, the gas is heated by the heater 90 when flowing through the gas supply pipes 62, 64, 66. Therefore, the temperature of the gas supplied to the lower region in the process container 10 is lower than the temperature of the gas supplied to the upper region in the process container 10. As a result, the inter-surface uniformity of the wafer temperature is deteriorated. The temperature difference increases as the flow rate of the gas supplied from the gas supply pipes 62, 64, and 66 into the processing chamber 10 increases.

Therefore, in the first embodiment, when a gas having a large flow rate is supplied into the processing container 10, the gas is heated to a predetermined temperature by the heaters 62c, 64c, and 66c and the pipe heaters 62d, 64d, and 66 d. Thus, when a large flow rate of gas is supplied into the process container 10, the sufficiently heated gas is supplied into the process container 10, and thus a temperature drop in the peripheral portion of the wafer W can be suppressed. As a result, the in-plane uniformity of the wafer temperature is improved. Further, since the temperature difference between the gas supplied to the lower region and the gas supplied to the upper region in the processing container 10 is small, the inter-surface uniformity of the wafer temperature is improved.

In the ALD method, the purge gas is often supplied at a larger flow rate than the first reactant gas and the second reactant gas in order to purge the first reactant gas and the second reactant gas remaining in the process container 10 in a short time. Therefore, the purge gas can be heated by the heater 66c and the pipe heater 66d, and the first reaction gas and the second reaction gas can be heated only by the pipe heaters 62d and 64 d. When the distances between the gas supply pipes 62, 64, and 66 and the heaters 62c, 64c, and 66c are short, the pipe heaters 62d, 64d, and 66d may not be provided.

In the above-described embodiments, the ALD method is described as an example of the film formation method, but the present invention is not limited thereto, and the present invention can be applied to a Chemical Vapor Deposition (CVD) method, for example.

(evaluation)

The evaluation results performed to confirm the effects of the first embodiment will be described with the heat treatment apparatus 1A.

First, the wafer boat 16 holding a plurality of wafers W is accommodated in the processing container 10, and the amount of heat generated by the heaters 90a to 90g is adjusted by controlling the power supplied to the heaters 90a to 90g so that the temperature of the wafers W becomes 240 ℃. The set temperature of the heater 66c was adjusted to 200 ℃ and the set temperature of the in-line heater 66d was adjusted to 100 ℃, and heated nitrogen (N) was supplied into the process container 10 from the gas supply pipe 66 at a flow rate of 40slm₂) A gas.

Next, the temperatures of 1 portion in the central portion and 10 portions in the peripheral portion of some of the plurality of wafers W held by the wafer boat 16 were measured. The measurement results are shown in fig. 4. In fig. 4, the horizontal axis represents the wafer position in the wafer boat 16, the first vertical axis represents the wafer temperature [ ° c ], and the second vertical axis represents the power [% ] supplied to the heater 90. In fig. 4, the uppermost position of the wafer boat 16 is indicated by a wafer position "1", and the lowermost position is indicated by a wafer position "115". In fig. 4, the measurement results of the central portion O of the wafer W are shown by solid lines, the measurement results of the peripheral portions a to J of the wafer W are shown by broken lines, and the power supplied to the heater 90 is shown by alternate long and short dash lines. Further, nitrogen gas is supplied from the peripheral edge F side of the wafer W.

For comparison, the wafer boat 16 holding a plurality of wafers W is accommodated in the processing container 10, and the amount of heat generated by the heaters 90a to 90g is adjusted by controlling the power supplied to the heaters 90a to 90g so that the temperature of the wafers W becomes 240 ℃. Further, the heater 66c was turned off, the set temperature of the pipe heater 66d was adjusted to 100 ℃, and nitrogen gas was supplied into the process container 10 from the gas supply pipe 66 at a flow rate of 40 slm.

Next, the temperatures of 1 portion in the central portion and 10 portions in the peripheral portion of some of the plurality of wafers W held by the wafer boat 16 were measured. The measurement results are shown in fig. 5. In fig. 5, the horizontal axis represents the wafer position in the wafer boat 16, the first vertical axis represents the wafer temperature [ ° c ], and the second vertical axis represents the power [% ] supplied to the heater 90. In fig. 5, the uppermost position of the wafer boat 16 is indicated by a wafer position "1", and the lowermost position is indicated by a wafer position "115". In fig. 5, the measurement results of the central portion O of the wafer W are shown by solid lines, the measurement results of the peripheral portions a to J of the wafer W are shown by broken lines, and the power supplied to the heater 90 is shown by alternate long and short dash lines. Further, nitrogen gas is supplied from the peripheral edge F side of the wafer W.

As shown in fig. 4, when the nitrogen gas is heated by the heater 66c, the inter-surface uniformity and the intra-surface uniformity of the wafer temperature are good. On the other hand, as shown in fig. 5, when the nitrogen gas is not heated by the heater 66c, the wafer temperature in the vicinity (for example, the peripheral edge F) of the gas supply pipe 66 becomes low. In addition, in the lower region of the processing container 10 (for example, wafer positions 85 to 115), the temperature of the wafer is significantly lowered.

From the above results, it is considered that the temperature uniformity in the large flow rate process can be improved by the film forming method according to the first embodiment.

[ second embodiment ]

(Heat treatment apparatus)

A heat treatment apparatus according to a second embodiment will be described. Fig. 6 is a sectional view showing an example of the structure of a heat treatment apparatus according to a second embodiment. Fig. 7 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 6.

The heat treatment apparatus 1B of the second embodiment is different from the heat treatment apparatus 1A of the first embodiment in that nozzles for supplying purge gas are formed by 2 gas supply pipes 66-1 and 66-2 having the same length. In addition, since the other points are the same as those of the heat treatment apparatus 1A of the first embodiment, the description will be mainly given of different points.

The gas supply unit 60B is provided in the manifold 30 and supplies a predetermined gas such as a process gas or a purge gas into the inner pipe 12. The gas supply unit 60B has a plurality of (e.g., 4) quartz gas supply pipes 62, 64, 66-1, 66-2 having the same length. The gas supply pipes 62, 64, 66-1, 66-2 are provided along the longitudinal direction in the inner pipe 12, and have base ends bent in an L-shape and are supported so as to penetrate through the header pipe 30.

As shown in fig. 7, the gas supply pipes 62, 64, 66-1, 66-2 are arranged in a row in the circumferential direction in the nozzle housing portion 18 of the inner pipe 12. In each of the gas supply pipes 62, 64, 66-1, 66-2, a plurality of gas holes 62a, 64a, 66-1 a, 66-2 a are formed at predetermined intervals along the longitudinal direction thereof. The gas holes 62a, 64a, 66-1 a, 66-2 a discharge the gas in the horizontal direction. The predetermined interval is set to be, for example, the same as the interval of the wafers W supported by the boat 16. The height direction position is set so that the gas holes 62a, 64a, 66-1 a, and 66-2 a are located at the middle between vertically adjacent wafers W, and the gas can be efficiently supplied to the space between the wafers W. For example, the gas supply pipe 62 is a nozzle for supplying a first reaction gas, the gas supply pipe 64 is a nozzle for supplying a second reaction gas that reacts with the first reaction gas to form a reaction product, and the gas supply pipes 66-1 and 66-2 are nozzles for supplying purge gases. Examples of the first reactive gas include a silicon-containing gas and a metal-containing gas. Examples of the second reactive gas include a nitriding gas and an oxidizing gas. As the purge gas, for example, an inert gas can be cited.

The gas supply pipe 62 supplies the first reaction gas through a gas pipe 62 b. The gas supply pipe 64 supplies the second reaction gas through a gas pipe 64 b. The gas supply pipes 66-1 and 66-2 supply purge gas through gas pipes 66-1 b and 66-2 b, respectively.

The gas pipes 62b, 64b, 66-1 b, and 66-2 b are provided with valves (not shown), mass flow controllers (not shown), heaters 62c, 64c, 66-1 c, and 66-2 c, and pipe heaters 62d, 64d, 66-1 d, and 66-2 d, respectively.

The heaters 62c, 64c, 66-1 c, and 66-2 c heat the gas flowing through the gas pipes 62b, 64b, 66-1 b, and 66-2 b, respectively. The set temperature of the heaters 62c, 64c, 66-1 c, 66-2 c may be, for example, 100 ℃ to 200 ℃.

The pipe heaters 62d, 64d, 66-1 d, and 66-2 d suppress a temperature drop of the gas heated by the heaters 62c, 64c, 66-1 c, and 66-2 c when the gas flows through the gas pipes 62b, 64b, 66-1 b, and 66-2 b, respectively. The set temperature of the piping heaters 62d, 64d, 66-1 d, 66-2 d may be, for example, the same as the set temperature of the heaters 62c, 64c, 66-1 c, 66-2 c, and may be, for example, 100 to 200 ℃.

(film Forming method)

As an example of the film formation method by the heat treatment apparatus 1B, a method of forming a silicon nitride film on the wafer W by the ALD method will be described.

First, the boat 16 holding a plurality of wafers W is carried into the processing container 10 by the elevating unit 46, and the opening at the lower end of the processing container 10 is hermetically closed by the lid 38. Next, the evacuation section 74 evacuates the processing container 10 to a predetermined pressure, and the heater 90 heats the wafers W in the processing container 10 to rotate the boat 16.

Next, the Si-containing gas from the gas supply pipe 62, the inert gas from the gas supply pipes 66-1, 66-2, the nitriding gas from the gas supply pipe 64, and the inert gas from the gas supply pipes 66-1, 66-2 are intermittently supplied in this order. Thus, in the first step of supplying the silicon-containing gas, the silicon-containing gas is adsorbed on the wafer W, and in the subsequent step of supplying the inert gas, the excess silicon-containing gas is purged. Then, in the next step of supplying the nitriding gas, the supplied nitriding gas is reacted with the silicon-containing gas, and the excess nitriding gas is purged in the next step of supplying the inert gas, thereby forming a thin cell film of substantially a monolayer. The series of cycles is performed a predetermined number of times to form a silicon nitride film having a desired film thickness.

In this way, in the ALD method, the silicon-containing gas and the nitriding gas are alternately supplied into the process container 10 at intervals of the purge gas in a short time. Therefore, in order to supply a predetermined amount of gas for a predetermined time, it is preferable that a large flow rate (for example, 10slm or more) of gas be supplied from the gas supply pipes 62, 64, 66-1, 66-2.

However, in the heat treatment apparatus 1B, since each gas is discharged in the horizontal direction from the plurality of gas holes 62a, 64a, 66-1 a, and 66-2 a, the gas is supplied from the peripheral edge side to the wafer W, and flows from the peripheral edge portion to the central portion over the wafer W. Therefore, when a large flow rate of gas is supplied into the processing container 10, if the gas discharged from the gas holes 62a, 64a, 66-1 a, and 66-2 a is not sufficiently heated, the temperature of the peripheral portion of the wafer W is lowered by the gas. As a result, a temperature difference occurs between the central portion and the peripheral portion of the wafer W, and the in-plane uniformity of the wafer temperature is deteriorated.

In the heat treatment apparatus 1B, the gas flows upward from below in the gas supply pipes 62, 64, 66-1, 66-2 provided along the longitudinal direction in the inner pipe 12. At this time, in the case where the gas supplied to the gas supply pipes 62, 64, 66-1, 66-2 is not sufficiently heated, the gas is heated by the heater 90 while flowing in the gas supply pipes 62, 64, 66-1, 66-2. Therefore, the temperature of the gas supplied to the lower region in the process container 10 is lower than the temperature of the gas supplied to the upper region in the process container 10. As a result, the inter-surface uniformity of the wafer temperature is deteriorated. The temperature difference increases as the flow rate of the gas supplied from the gas supply pipes 62, 64, 66-1, 66-2 into the processing container 10 increases.

Therefore, in the second embodiment, when a gas having a large flow rate is supplied into the processing container 10, the gas is heated to a predetermined temperature by the heaters 62c, 64c, 66-1 c, and 66-2 c and the pipe heaters 62d, 64d, 66-1 d, and 66-2 d. Accordingly, even when a large flow rate of gas is supplied into the processing container 10, the temperature drop of the peripheral portion of the wafer W can be suppressed by supplying the gas heated sufficiently into the processing container 10. As a result, the in-plane uniformity of the wafer temperature is improved. Further, since the temperature difference of the gas supplied to the lower region and the upper region in the processing container 10 is reduced, the inter-surface uniformity of the wafer temperature is improved.

In particular, in the second embodiment, a large amount of purge gas supplied at a large flow rate is simultaneously supplied into the process container 10 through 2 gas supply pipes 66-1 and 66-2. Therefore, the purge gas is easily heated as compared with the case where the same flow rate of the purge gas is supplied from the 1 gas supply pipe 66. As a result, the in-plane uniformity and the inter-plane uniformity of the wafer temperature are further improved.

In the ALD method, the purge gas is often supplied at a larger flow rate than the first reactant gas and/or the second reactant gas in order to purge the first reactant gas and the second reactant gas remaining in the process container 10 in a short time. Therefore, the purge gas can be heated by the heaters 66-1 c and 66-2 c and the pipe heaters 66-1 d and 66-2 d, and the first reaction gas and the second reaction gas can be heated only by the pipe heaters 62d and 64 d. In addition, when the distances between the gas supply pipes 62, 64, 66-1, 66-2 and the heaters 62c, 64c, 66-1 c, 66-2 c are short, the piping heaters 62d, 64d, 66-1 d, 66-2 d may not be provided.

In the above-described embodiments, the ALD method is described as an example of the film formation method, but the present invention is not limited thereto, and the present invention can be similarly applied to the CVD method, for example.

In the above-described embodiment, the case where the purge gas is supplied from 2 gas supply pipes 66-1 and 66-2 having the same length has been described, but the present invention is not limited thereto, and the purge gas may be supplied from 3 or more gas supply pipes having the same length, for example. In addition, the first reactive gas and/or the second reactive gas may be supplied by a plurality of gas supply pipes having the same length.

(evaluation)

The evaluation results performed to confirm the effects of the second embodiment will be described with the heat treatment apparatus 1B.

First, the wafer boat 16 holding a plurality of wafers W is accommodated in the processing container 10, and the amount of heat generated by the heaters 90a to 90g is adjusted so that the temperature of the wafers W becomes 240 ℃ by controlling the power supplied to the heaters 90a to 90 g. Further, the heaters 66-1 c and 66-2 c were turned off, the set temperatures of the pipe heaters 66-1 d and 66-2 d were adjusted to 100 ℃, and nitrogen gas was supplied into the processing container 10 from the 2 gas supply pipes 66-1 and 66-2 at a flow rate of 20slm (40 slm in total).

Next, the temperatures of 1 portion in the central portion and 10 portions in the peripheral portion of some of the plurality of wafers W held by the wafer boat 16 were measured. The measurement results are shown in fig. 8. In fig. 8, the horizontal axis represents the wafer position in the wafer boat 16, the first vertical axis represents the wafer temperature [ ° c ], and the second vertical axis represents the power [% ] supplied to the heater 90. In fig. 8, the uppermost position of the wafer boat 16 is indicated by a wafer position "1", and the lowermost position is indicated by a wafer position "115". In fig. 8, the measurement results of the central portion O of the wafer W are shown by solid lines, the measurement results of the peripheral portions a to J of the wafer W are shown by broken lines, and the power supplied to the heater 90 is shown by alternate long and short dash lines. Further, nitrogen gas is supplied from the peripheral edge F side of the wafer W.

For comparison, in the heat processing apparatus 1A, the wafer boat 16 holding a plurality of wafers W is accommodated in the processing container 10, and the amounts of heat generation of the heaters 90a to 90g are adjusted so that the temperature of the wafers W becomes 240 ℃. Further, the heater 66c was turned off, the set temperature of the pipe heater 66d was adjusted to 100 ℃, and nitrogen gas was supplied into the process container 10 from 1 gas supply pipe 66 at a flow rate of 40 slm.

Next, the temperatures of 1 portion in the central portion and 10 portions in the peripheral portion of some of the plurality of wafers W held by the wafer boat 16 were measured. The measurement results are shown in fig. 9. In fig. 9, the horizontal axis represents the wafer position in the wafer boat 16, the first vertical axis represents the wafer temperature [ ° c ], and the second vertical axis represents the power [% ] supplied to the heater 90. In fig. 9, the uppermost position of the wafer boat 16 is indicated by a wafer position "1", and the lowermost position is indicated by a wafer position "115". In fig. 9, the measurement results of the central portion O of the wafer W are shown by solid lines, the measurement results of the peripheral portions a to J of the wafer W are shown by broken lines, and the power supplied to the heater 90 is shown by alternate long and short dash lines. Further, nitrogen gas is supplied from the peripheral edge F side of the wafer W.

As shown in fig. 8 and 9, when nitrogen gas is supplied into the process container 10 from the 2 gas supply pipes 66-1 and 66-2, the in-plane uniformity and the inter-plane uniformity of the wafer temperature are improved as compared with the case where nitrogen gas is supplied into the process container 10 from the 1 gas supply pipe 66.

From the above results, it is considered that the temperature uniformity in the large flow rate process can be improved by the film forming method according to the second embodiment.

[ third embodiment ]

(Heat treatment apparatus)

A heat treatment apparatus according to a third embodiment will be described. Fig. 10 is a sectional view showing an example of the structure of a heat treatment apparatus according to a third embodiment. Fig. 11 is a diagram for explaining the arrangement of gas supply pipes in the heat treatment apparatus of fig. 10. In fig. 10, the gas supply pipes 62 and 64 are not shown for convenience of explanation.

The heat treatment apparatus 1C of the third embodiment is different from the heat treatment apparatus 1A of the first embodiment in that a nozzle for supplying purge gas is formed by 3 gas supply pipes 66-3, 66-4, 66-5 having different lengths. In addition, since the other points are the same as those of the heat treatment apparatus 1A of the first embodiment, the description will be mainly given of different points.

The gas supply unit 60C is provided in the manifold 30 and supplies a predetermined gas such as a process gas or a purge gas into the inner pipe 12. The gas supply section 60C has quartz gas supply pipes 62 and 64 of the same length and quartz gas supply pipes 66-3, 66-4, and 66-5 of different lengths. The gas supply pipes 62, 64, 66-3, 66-4, 66-5 are provided in the inner pipe 12 along the longitudinal direction thereof, and the base ends thereof are bent in an L-shape and pass through and are supported by the header pipe 30. As shown in fig. 11, the gas supply pipes 62, 64, 66-3, 66-4, 66-5 are arranged in a row in the circumferential direction in the nozzle housing portion 18 of the inner pipe 12. The gas supply pipes 62 and 64 have the same configuration as that of the first embodiment.

In each of the gas supply pipes 66-3, 66-4, 66-5, a plurality of gas holes 66-3 a, 66-4 a, 66-5 a are formed at predetermined intervals along the longitudinal direction of the upper portion in the inner pipe 12. The gas holes 66-3 a, 66-4 a, 66-5 a eject gas in the horizontal direction.

Thus, the gas supply pipes 66-3, 66-4, and 66-5 can independently discharge gas to the upper portion, the central portion, and the lower portion of the inner pipe 12. The predetermined interval is set to be, for example, the same as the interval of the wafers W supported by the boat 16. The height direction position is set so that the gas holes 66-3 a, 66-4 a, and 66-5 a are located at the middle between vertically adjacent wafers W, and the gas can be efficiently supplied to the space between the wafers W. As an example, the gas supply pipes 66-3, 66-4, 66-5 are nozzles for supplying purge gas. As the purge gas, for example, an inert gas can be cited.

The gas supply pipes 66-3, 66-4, and 66-5 supply purge gas through gas pipes 66-3 b, 66-4 b, and 66-5 b, respectively.

The gas pipes 66-3 b, 66-4 b, and 66-5 b are provided with valves (not shown), mass flow controllers (not shown), heaters 66-3 c, 66-4 c, and 66-5 c, and pipe heaters 66-3 d, 66-4 d, and 66-5 d, respectively.

The heaters 66-3 c, 66-4 c, and 66-5 c heat the gas flowing through the gas pipes 66-3 b, 66-4 b, and 66-5 b, respectively. The set temperature of the heaters 66-3 c, 66-4 c, 66-5 c may be, for example, 100 ℃ to 200 ℃.

The piping heaters 66-3 d, 66-4 d, and 66-5 d suppress a temperature drop of the gas heated by the heaters 66-3 c, 66-4 c, and 66-5 c when the gas flows through the gas piping 66-3 b, 66-4 b, and 66-5 b, respectively. The set temperature of the piping heaters 66-3 d, 66-4 d, and 66-5 d may be, for example, the same as the set temperature of the heaters 66-3 c, 66-4 c, and 66-5 c, and may be, for example, 100 to 200 ℃.

(film Forming method)

A method for forming a silicon nitride film on a wafer W by the ALD method will be described as an example of a film forming method by the heat treatment apparatus 1C.

First, the boat 16 holding a plurality of wafers W is carried into the processing container 10 by the elevating unit 46, and the opening at the lower end of the processing container 10 is hermetically closed by the lid 38. Next, the evacuation section 74 evacuates the processing container 10 to a predetermined pressure, and the heater 90 heats the wafers W in the processing container 10 to rotate the boat 16.

Next, a silicon-containing gas from the gas supply pipe 62, an inert gas from the gas supply pipes 66-3, 66-4, 66-5, a nitriding gas from the gas supply pipe 64, and an inert gas from the gas supply pipes 66-3, 66-4, 66-5 are intermittently supplied in this order. Thus, in the first step of supplying the silicon-containing gas, the silicon-containing gas is adsorbed on the wafer W, and in the subsequent step of supplying the inert gas, the excess silicon-containing gas is purged. Then, in the next step of supplying the nitriding gas, the supplied nitriding gas is reacted with the silicon-containing gas, and the excess nitriding gas is purged in the next step of supplying the inert gas, thereby forming a thin cell film of substantially a monolayer. The series of cycles is performed a predetermined number of times to form a silicon nitride film having a desired film thickness.

In this way, in the ALD method, the silicon-containing gas and the nitriding gas are alternately supplied into the process container 10 at intervals of the purge gas in a short time. Therefore, in order to supply a predetermined amount of gas for a predetermined time, it is preferable that a large flow rate (for example, 10slm or more) of gas be supplied from the gas supply pipes 62, 64, 66-3, 66-4, 66-5.

In the heat treatment apparatus 1C, however, each gas is discharged in the horizontal direction from the plurality of gas holes 62a, 64a, 66-3 a, 66-4 a, and 66-5 a, and the gas is supplied from the peripheral edge side to the wafer W, and flows from the peripheral edge portion to the central portion over the wafer W. Therefore, when a large flow rate of gas is supplied into the processing container 10, if the gas discharged from the gas holes 62a, 64a, 66-3 a, 66-4 a, and 66-5 a is not sufficiently heated, the temperature of the peripheral portion of the wafer W is lowered by the gas. As a result, a temperature difference occurs between the central portion and the peripheral portion of the wafer W, and the in-plane uniformity of the wafer temperature is deteriorated.

In the heat treatment apparatus 1C, the gas flows upward from below in the gas supply pipes 62, 64, 66-3, 66-4, 66-5 provided along the longitudinal direction of the inner pipe 12.

At this time, in the case where the gas supplied to the gas supply pipes 62, 64, 66-3, 66-4, 66-5 is not sufficiently heated, the gas is heated by the heater 90 while flowing in the gas supply pipes 62, 64, 66-3, 66-4, 66-5. Therefore, the temperature of the gas supplied to the lower region in the process container 10 is lower than the temperature of the gas supplied to the upper region in the process container 10. As a result, the inter-surface uniformity of the wafer temperature is deteriorated. The temperature difference increases as the flow rate of the gas supplied from the gas supply pipes 62, 64, 66-3, 66-4, and 66-5 into the processing container 10 increases.

Therefore, in the third embodiment, when a large flow rate of gas is supplied into the processing container 10, the gas is heated to a predetermined temperature by the heaters 62c, 64c, 66-3 c, 66-4 c, 66-5 c and the pipe heaters 62d, 64d, 66-3 d, 66-4 d, 66-5 d. Accordingly, even when a large flow rate of gas is supplied into the process container 10, the sufficiently heated gas is supplied into the process container 10, and therefore, a temperature drop in the peripheral portion of the wafer W can be suppressed.

As a result, the in-plane uniformity of the wafer temperature is improved. Further, since the temperature difference between the gas supplied to the lower region and the gas supplied to the upper region in the processing container 10 is small, the inter-surface uniformity of the wafer temperature is improved.

In particular, in the third embodiment, a large number of purge gases supplied at a large flow rate are simultaneously supplied into the process container 10 through the 3 gas supply pipes 66-3, 66-4, and 66-5 having different lengths. Therefore, the purge gas is easily heated as compared with the case where the same flow rate of the purge gas is supplied from the 1 gas supply pipe 66. As a result, the in-plane uniformity and the inter-plane uniformity of the wafer temperature are further improved.

In addition, in the third embodiment, the heaters 66-3 c, 66-4 c, 66-5 c are provided in the 3 gas supply pipes 66-3, 66-4, 66-5 of different lengths, respectively. Thus, the temperature of the gas supplied to the gas supply pipes 66-3, 66-4, 66-5 can be adjusted by controlling the set temperatures of the heaters 66-3 c, 66-4 c, 66-5 c. For example, the temperature of the purge gas supplied to the gas supply pipe 66-5 at the lowermost position is adjusted to be higher than the temperature of the gas supplied to the gas supply pipe 66-4 at the central position. This makes it possible to set the temperature of the gas supplied to the lower portion of the inner tube 12, which is not easily heated in the process container 10, higher than the temperature of the gas supplied to the central portion of the inner tube 12. Further, for example, the temperature of the purge gas supplied to the gas supply pipe 66-4 at the center position is adjusted to be higher than the temperature of the gas supplied to the gas supply pipe 66-3 at the uppermost position. Thus, the temperature of the gas supplied to the central portion of the inner tube 12, which is not easily heated in the process container 10, can be set higher than the temperature of the gas supplied to the upper portion of the inner tube 12. As a result, the temperature difference of the purge gas supplied to the upper portion, the central portion, and the lower portion of the inner tube 12 is reduced, and the inter-surface uniformity of the wafer temperature is improved.

In the ALD method, the purge gas is often supplied at a larger flow rate than the first reactant gas and/or the second reactant gas in order to purge the first reactant gas and the second reactant gas remaining in the process container 10 in a short time. Therefore, the purge gas can be heated by the heaters 66-3 c, 66-4 c, and 66-5 c and the pipe heaters 66-3 d, 66-4 d, and 66-5 d, and the first reaction gas and the second reaction gas can be heated only by the pipe heaters 62d and 64 d. When the distance between the gas supply pipes 62, 64, 66-3, 66-4, 66-5 and the heaters 62c, 64c, 66-3 c, 66-4 c, 66-5 c is short, the piping heaters 62d, 64d, 66-3 d, 66-4 d, 66-5 d may not be provided.

In the above-described embodiments, the ALD method is described as an example of the film formation method, but the present invention is not limited thereto, and for example, the present invention can be similarly applied to the CVD method.

In the above-described embodiment, the case where the purge gas is supplied through the 3 gas supply pipes 66-3, 66-4, and 66-5 having different lengths has been described, but the present invention is not limited to this, and the purge gas may be supplied through, for example, 2 gas supply pipes having different lengths or 4 or more gas supply pipes having different lengths. Further, the first reactive gas and the second reactive gas may be supplied through a plurality of gas supply pipes having different lengths.

In the above-described embodiment, the heater 90 is an example of a first heater, and the heaters 62c, 64c, 66-1 c, 66-2 c, 66-3 c, 66-4 c, and 66-5 c are examples of a second heater.

The present embodiments are to be considered in all respects as illustrative and not restrictive. The above-described embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the present invention.

In the above-described embodiments, the case where the substrate is a semiconductor wafer is exemplified, but the present invention is not limited thereto. For example, the substrate may be a large substrate for a Flat Panel Display (FPD), or a substrate for an EL device or a solar cell.