JP2004260204A - Substrate processing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the conventional problem of supplying an etching gas to do uniform etching, and eventually do uniform cleaning of the inside of a reaction pipe. <P>SOLUTION: In order to bring about a state of exhaust from a gas exhaust pipe being stopped while a cleaning gas is supplied from a gas introduction pipe to a reaction pipe, a cleaning process is carried out at least one cycle or more to clean the inside wall of the reaction pipe, the cleaning process including the first step of removing extraneous matter adhering to the inside of the reaction pipe by filling it with the cleaning gas and the second step of removing the atmosphere filling the reaction pipe from the gas exhaust pipe after the first step, while stopping gas exhaust from the gas exhaust pipe or making the gas exhaust amount so much as not to influence the flow of the cleaning gas in the reaction pipe during the time from a designated point of time before supplying the cleaning gas from the gas introduction pipe into the reaction gas until when several seconds have passed after the start of the cleaning gas supply into the reaction pipe. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

DETAILED DESCRIPTION OF THE INVENTION

Technical field to which the invention belongs

  The present invention relates to a substrate processing apparatus, which is an apparatus for manufacturing a semiconductor device used when manufacturing a semiconductor device on a substrate such as Si, and particularly to a technology for cleaning a reaction chamber.

Conventional technology

In this type of substrate processing apparatus, it is known that cleaning is performed by supplying and exhausting a cleaning gas to a reaction chamber (see Patent Document 1).
A conventional semiconductor device manufacturing apparatus will be described with reference to FIG. It is sectional drawing which shows the concept of the reaction furnace of FIG.
In a self-cleaning step for removing a reaction by-product adhered to the inner wall of the reaction tube 1 or the like by a desired film forming process, the etching gas 4 as a cleaning gas is controlled at a constant flow rate and continuously. The gas was supplied from the gas introduction pipe 2 through the gas nozzle 7 into the reaction tube 1 through the plurality of holes 8.
Further, the inside of the reaction tube 1 is maintained at a constant pressure by exhausting a desired amount of gas by adjusting the opening degree of the pressure adjustment bubble 5 connected to the gas exhaust tube 3. .

JP 2002-47571 A

  However, the conventional systems and methods have a problem that uneven etching and etching residue occur.

This is considered to be because the following events have occurred since the etching gas is supplied while exhausting gas.
(A) Depending on the shape of the reaction tube 1 or the positional relationship between the gas supply position and the exhaust position, a “flow” from the gas introduction tube 2 to the gas exhaust tube 3 occurs, and the etching gas is generated at an upstream portion of the “flow”. A large amount is consumed, and it is difficult for the etching gas to reach the downstream portion.
(B) While the degree of gas diffusion is high in a place where the pressure is low as viewed from the reaction tube 1 (that is, in the vicinity of the gas exhaust pipe), in a place where the pressure is high as viewed from the reaction tube 1 (that is, in the upper end portion of the reaction tube 1). The degree of gas diffusion is small, and it is difficult for the etching gas to reach a location where the pressure is high when viewed from inside the reaction tube 1.
That is, a “flow” from the gas introduction pipe 2 to the gas exhaust pipe 3 is generated, and it is difficult for the etching gas to reach a portion not along the “flow”.
Specifically, as shown by the arrow in FIG. 7, a strong flow portion 11 along the gas flow is generated from the substantially middle position of the reaction tube 1 to the gas exhaust pipe 3 side, while the upper part of the reaction tube 1 is formed. On the side, a weak flow portion 12 against the gas flow was generated, and the gas flow rate and the partial pressure were not constant in the reaction tube 1.
In this specification, the term “flow” refers to an intentional gas flow generated by an exhaust action, and excludes a gas flow caused by gas diffusion.

The present invention solves the problem of conventional etching gas supply in a semiconductor device manufacturing apparatus (substrate processing apparatus) that performs self-cleaning using an etching gas such as NF3, and achieves uniform etching and, consequently, uniform cleaning in a reaction tube. The purpose is to do.

  In order to solve the above problems, a first feature of the present invention is a substrate processing apparatus including a gas introduction pipe communicating with a reaction pipe and a gas exhaust pipe having a closing member. Before supplying the cleaning gas from the gas introduction pipe to the inside of the reaction tube, so that the exhaust from the gas exhaust pipe is stopped while supplying the cleaning gas into the reaction pipe. From a predetermined point in time to a point in time when several seconds have elapsed from the start of supplying the cleaning gas into the reaction tube, a control unit that controls the opening degree of the closing member so as to substantially stop the exhaust, and is controlled by the control unit. The substrate processing apparatus fills the inside of the reaction tube with a cleaning gas. Here, “substantially stop” means not only completely stopping the exhaust of the gas but also allowing a small amount of exhaust as long as the cleaning gas diffuses substantially uniformly in the reaction tube. Therefore, the flow of the cleaning gas in the reaction tube can be substantially stopped, and the inside of the reaction tube can be filled with the cleaning gas by diffusion, so that not only the partial pressure of the etching gas becomes uniform in the reaction tube, but also the pressure of the etching gas. , The etching rate (cleaning rate) can be improved.

The exhaust from the gas exhaust pipe may be stopped substantially simultaneously with the start of the supply of the cleaning gas from the gas introduction pipe or before the start of the supply of the cleaning gas. The exhaust from the gas exhaust pipe may be substantially stopped. When the exhaust is stopped after the start of the supply of the cleaning gas from the gas introduction pipe, the timing of the exhaust stop is determined by the time required to close the exhaust pipe and the time required for the cleaning gas to be easily diffused into the entirety of the reaction tube. Time is taken into account. For example, if the time required to close the exhaust pipe is 2 seconds and it takes 5 seconds for the cleaning gas to easily diffuse almost entirely in the reaction tube, it takes 7 seconds in total, and the exhaust is stopped within 7 seconds. Is preferred. The reason for taking a 5 second margin is that the exhaust is stopped after the gas flow is generated in the reaction tube. Therefore, when the distance between the gas supply port and the exhaust port is long and the path is complicated, the cleaning gas is used. This is because it can reach the whole quickly.

According to a second feature of the present invention, in a substrate processing apparatus including a gas introduction pipe communicating with a reaction pipe and a gas exhaust pipe having a closing member, a cleaning gas is supplied from the gas introduction pipe into the reaction pipe. During the supply, in order to have a state in which the exhaust from the gas exhaust pipe is stopped, a predetermined point in time before the cleaning gas is supplied from the gas introduction pipe into the reaction pipe into the reaction pipe. By the time when several seconds have elapsed from the start of the supply of the cleaning gas, the control unit controls the opening degree of the closing member so as to substantially stop the exhaust, and the control unit controls the inside of the reaction tube with the cleaning gas. A first stage of filling and, after the first stage, a second stage of evacuating the reaction chamber, wherein the substrate processing is performed by repeating the first and second stages at least one cycle or more. Apparatus is in. In the second stage, since the reactant after the cleaning reaction disturbs the subsequent cleaning reaction, the cleaning efficiency can be improved by once evacuating. The number of repetitions of the first step and the second step depends on the thickness of the applied film and the like.
(Embodiment of the invention)

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a substrate processing apparatus 20 according to an embodiment of the present invention. The substrate processing apparatus 20 is, for example, a vertical type and has a housing 22 in which a main part is arranged. A pod stage 24 is connected to the housing 22, and a pod 26 is transported to the pod stage 24. The pod 26 accommodates, for example, 25 substrates, and is set on the pod stage 24 with a lid (not shown) closed.

In the housing 22, a pod transport device 28 is disposed at a position facing the pod stage 24. A pod shelf 30, a pod opener 32, and a substrate number detector 34 are arranged near the pod transport device 28. The pod transport device 28 transports the pod 26 between the pod stage 24, the pod shelf 30, and the pod opener 32. The pod opener 32 opens the lid of the pod 26, and the number of substrates in the pod 26 with the lid opened is detected by the substrate number detector 34.

Further, a substrate transfer machine 36, a notch aligner 38, and a substrate support 40 (boat) are arranged in the housing 22. The substrate transfer machine 36 has an arm 42 from which, for example, five substrates can be taken out, and by moving this arm 42, the pod 26 placed at the position of the pod opener 32, the notch aligner 38, and the substrate support The substrate is transported between 40. The notch aligner 38 aligns the substrates by detecting notches or orientation flats formed on the substrates.

In FIG. 2, a reactor 50 is shown. The reaction furnace 50 has a reaction tube 52 into which the above-described substrate support is inserted. The lower part of the reaction tube 52 is opened for inserting a substrate support, and this opened part is sealed by a seal cap 54 (also shown in FIG. 1). A heater 56 (shown in FIG. 3) is arranged around the reaction tube 52. The reaction tube 52 is connected to a gas introduction tube 58 for supplying a reaction gas and a cleaning gas, and a gas exhaust tube 60 for exhausting the reaction gas and the cleaning gas. The gas supplied from the gas introduction pipe 58 is supplied into the reaction tube 52 from a number of holes 64 of a gas nozzle 62 formed in the reaction tube 52. Further, the gas exhaust pipe 60 is provided with a closing member 66 composed of, for example, a pressure adjusting valve, and the closing member 66 has a shut-off function.

Next, a substrate processing process by the substrate processing apparatus 20 configured as described above will be described.
First, when the pod 26 accommodating a plurality of substrates is set on the pod stage 24, the pod 26 is transported from the pod stage 24 to the pod shelf 30 by the pod transport device 28 and stocked on the pod shelf 30. Next, the pod 26 stocked on the pod shelf 30 is transported to the pod opener 32 and set by the pod transport device 28, the lid of the pod 26 is opened by the pod opener 32, and the pod 26 is detected by the substrate number detector 34. The number of substrates accommodated in the device is detected.

Next, the substrate is taken out from the pod 26 at the position of the pod opener 32 by the substrate transfer machine 36 and transferred to the notch aligner 38. In the notch aligner 38, the notch is detected while rotating the substrate, and the plurality of substrates are aligned at the same position based on the detected information. Next, the substrate is taken out from the notch aligner 38 by the substrate transfer device 36 and transferred to the substrate support 40.

In this way, when a batch of substrates is transferred to the substrate support 40, the substrate support 40 loaded with a plurality of substrates is loaded into the reaction furnace 50 set at a predetermined temperature, and the seal cap The inside of the reaction tube 52 is sealed by 54. Next, a reaction gas is supplied from the gas introduction pipe 58. Then, while monitoring the temperature inside the reaction tube 52, the substrate processing is performed according to a preset temperature raising / lowering program.

When the substrate processing is completed, after the temperature is lowered to a predetermined temperature, the substrate support 40 is unloaded from the reaction furnace 50, and the substrate support 40 is kept at a predetermined position until all the substrates supported by the substrate support 40 cool. Have to wait. Next, when the substrate of the substrate support 40 in a standby state is cooled to a predetermined temperature, the substrate is taken out from the substrate support 40 by the substrate transfer device 36 and is transferred to the empty pod 26 set in the pod opener 32. Transport and house. Next, the pod 26 accommodating the substrate is transported to the pod shelf 30 by the pod transport device 28 and further transported to the pod stage 24 to complete the process.

FIG. 3 shows a gas system of the substrate processing apparatus.
The first storage tank 68 storing the N2 gas for purging is provided with a first manual valve 70, a first opening / closing valve 72, a first flow control valve 74, a second opening / closing valve 76, and the above-described gas introduction. The tube 58 is connected to the reaction tube 52. The second storage tank 78 in which the cleaning gas is stored includes a second manual valve 80, a third opening / closing valve 82, a second flow control valve 84, a fourth opening / closing valve 86, and the gas introduction pipe 58 described above. It is connected to the reaction tube 52 through the. The third storage tank 88 storing the first reaction gas is provided with a third manual valve 90, a fifth opening / closing valve 92, a third flow control valve 94, a sixth opening / closing valve 96, and the above-described gas introduction. The tube 58 is connected to the reaction tube 52. The third storage tank 98 in which the second reaction gas is stored includes a fourth manual valve 100, a seventh opening / closing valve 102, a fourth flow control valve 104, an eighth opening / closing valve 106, and the above-described gas introduction. The tube 58 is connected to the reaction tube 52.

The gas exhaust pipe 60 having the above-described closing member 66 is connected to a dry pump 108, and the inside of the reaction tube 52 is depressurized by the operation of the dry pump 108.

The control device (control unit) 110 is composed of, for example, a computer, and opens and closes the on-off valves 72, 76, 82, 86, 92, 96, 102, 106, the flow rates of the flow control valves 74, 84, 94, 104, and the heater 56. , The opening degree of the closing member 66, the driving of the dry pump 108, and the like.

Next, the cleaning process will be described.
As described above, when the substrate processing is repeated for several batches, the reaction product accumulates in the reaction space, for example, the inner wall of the reaction tube 52, and the accumulated by-product is peeled off with time, resulting in particles, which become particles on the substrate. To reduce the yield.

Therefore, it is necessary to periodically clean the reaction space. In this embodiment, the reaction space is self-cleaned by supplying an etching gas (for example, NF3 gas) as a cleaning gas. Although not shown in FIG. 2, the cleaning process is performed with the substrate support inserted into the reaction tube 52, and the by-products deposited on the substrate support are also removed.

FIG. 4 is a flowchart illustrating an example of a control operation in the cleaning process of the control device 110 described above. FIG. 5 shows a time chart in the control operation example.

First, in step S10, the closing member 66 is closed with the inside of the reaction tube 52 set to the base pressure. Next, in step S12, the fourth opening / closing valve 86 is opened. In the next step S14, the flow rate of the second flow control valve 84 is set to a first set value. The first set value is, for example, 1.5 slm. In the next step S16, the third opening / closing valve 82 is opened to start supplying the etching gas (t0 in FIG. 5). Thereby, the pressure in the reaction tube 52 gradually increases. This state is maintained for the time t1, and the pressure in the reaction tube 52 at the time when the time t1 has elapsed reaches p1. t1 is, for example, 25 seconds, and p1 is, for example, 10 Torr. When the time t1 has elapsed, in the next step S18, the flow rate of the second flow rate control valve 84 is set to the second set value. The second set value is, for example, 0.25 slm. Thereby, the pressure in the reaction tube 52 rises from p1 to p2 or is maintained at p1. In this embodiment, p2 is, for example, 10 Torr, which is equal to p1. This state is maintained for the time t2. t2 is, for example, 65 seconds.
The following effects can be obtained by reducing the flow rate of the second flow control valve 84 from the first set value (for example, 1.5 slm) to the second set value (for example, 0.25 slm).
(A) By supplying the etching gas at the first set value higher than the second set value, the pressure can be quickly increased to a pressure at which an effective etching rate can be obtained.
(B) By supplying the etching gas at a second set value lower than the first set value, the concentration of the etching gas in the vicinity of the hole 64 of the gas nozzle 62 is reduced, and the uniformity of the etching gas in the reaction tube is further increased. Can be.
(C) By supplying the etching gas at the second set value lower than the first set value, the etching gas consumed by the etching can be replenished and the partial pressure of the etching gas due to the etching can be prevented from lowering.
Alternatively, the pressure in the reaction tube 52 may be maintained at p2 for a time t4. t4 is, for example, 45 seconds.

This is the first stage, in which the etching gas is supplied from the gas introduction pipe 58 through the gas nozzle 62 extending in the longitudinal direction of the reaction pipe 52 to the gas exhaust pipe 60 while flowing into the reaction pipe 52 from the many holes 64. By closing the closing member 66, the reaction tube 52 is filled with gas and sealed.
Thereby, the biased flow of the etching gas 112 toward the gas exhaust pipe 60 is reduced, the etching gas diffuses throughout the reaction tube 52, and the partial pressure of the etching gas 112 in the reaction tube 52 becomes uniform. .

In FIG. 2, reference numeral 114 indicates a state in which the etching gas 112 is diffused after being supplied into the reaction tube 52, and reference numeral 116 indicates that the etching gas 112 diffuses throughout the reaction tube 52, and the gas is diffused. 5 shows a virtual region indicating a uniform state.

Also, regarding the consumption of the etching gas 112 and the change in the partial pressure of the etching gas upstream and downstream of the gas due to the gas generated by the etching, the partial pressure of the etching gas is uniform due to the diffusion of the gas generated by the etching gas and the etching gas. It becomes.

That is, the removal of the reaction products deposited on the inner wall of the reaction tube 52 can be expressed by the following principle. The reaction product (solid state) Si3N4 and the etching gas 4NF3 react with each other to generate a product gas of 3SiF4 and 4N2, thereby removing the reaction product.
During this time, the temperature inside the reaction tube 52 by the heater 56 is maintained at, for example, 630 ° C.
If a gas flow is present in the reaction tube as in the conventional case, NF3 is consumed on the upstream side of the gas flow, while SiF4 and N2 are present in a large amount, and the partial pressure of the etching gas differs between the upstream and downstream sides. I will.
However, since the gas of NF3, SiF4, and N2 is easily diffused by containing the gas without forming the gas flow as in the embodiment of the present invention, the gas partial pressure of each gas becomes equal, and A uniform etching gas can be supplied into the tube 52. This enables uniform cleaning.

In the first stage, while the gas is not exhausted while the etching gas is being supplied, the pressure in the reaction tube 52 increases. However, the increase in the pressure can be expected to increase the etching rate.

As described above, when the time t2 has elapsed since the second flow control valve 84 was set to the second set value in step S18, the process proceeds to the next step S20. In this step S20, the third opening / closing valve 82 is closed. In the next step S22, the fourth opening / closing valve 86 is closed. In the next step S24, the closing member 66 is opened. As a result, the etching gas in the reaction tube 52 is exhausted through the gas exhaust tube 60, and the pressure in the reaction tube 52 rapidly decreases to the base pressure.

This is the second stage, in which the etching gas and the generated gas are exhausted from the reaction tube 52.

In the next step S26, it is determined whether or not the processing of the first and second steps has been repeated a desired number of times. If it is determined in step S26 that the desired number of times has been repeated, the process proceeds to the next process (substrate process). On the other hand, if it is determined in step S26 that the desired number of times has not been repeated, the process returns to step S10, and the processes in the first and second stages are repeatedly executed. After the closing member 66 is opened in step S22, the etching gas and the generated gas in the reaction tube 52 are sufficiently exhausted after waiting for a time t3, and the closing member 66 in step S10 in the next cycle is closed. This time t3 is, for example, 4 seconds.

As described above, by performing the cleaning step in the reaction tube 52 in the first stage and the second stage separately, uniform cleaning can be performed. By repeating the cycles of the first stage and the second stage at least one cycle or more, uniform etching without etching residue can be performed.

Thus, according to the cleaning method provided by the embodiment of the present invention, uniform cleaning of the inside of the reaction tube becomes possible.

In addition, if a substrate processing apparatus in which the inside of the reaction tube is self-cleaned in the above-described cleaning step is used, high-quality semiconductor devices can be produced.

The present invention is not limited to the above-described embodiment, and various changes can be made.
That is, in the first stage, even if the exhaust of the gas is not completely stopped, the flow of the etching gas supplied into the reaction tube does not become non-uniform, and the exhaust amount does not affect the uniform diffusion of the gas. If so, the etching gas may be supplied while exhausting gas.

In the case of performing the first step again after the second step in the second step, the supply of the etching gas may be somewhat stopped without completely stopping the supply. If the first step is not performed again after the second step, it is preferable to completely stop and exhaust the etching gas in order to prevent a residual gas (etching gas) from being left in the next processing.

As described above, in the first stage, various changes are possible as long as the cleaning gas is uniformly diffused in the reaction tube.

FIG. 6 shows another embodiment. In this other embodiment, as compared with the above-described embodiment, in the above-described embodiment, the closing member was closed and the exhaust was stopped before the cleaning gas supply was started, whereas the closing member was closed after the cleaning gas supply was started. The difference is that the exhaust is stopped.

That is, in this embodiment, first, the processing of steps S12, S14, and S16 is executed to supply the cleaning gas to the reaction tube. Thereafter, after a predetermined time has elapsed, the processing of step S10 is executed to stop the exhaust. Here, the predetermined time takes into account the time required to close the closing member and the time required for the cleaning gas to diffuse easily into almost the entire reaction tube in the reaction tube. For example, if the time required to close the gas exhaust pipe is 2 seconds and it takes 5 seconds for the cleaning gas to easily diffuse into almost the entirety of the reaction tube, it takes 7 seconds in total, and the exhaust is stopped within 7 seconds. Is preferred. The reason for setting a margin of 5 seconds is that the exhaust is stopped after the gas flow is generated in the reaction tube, so that the gas supply port (for example, the outlet of the fourth on-off valve 86) and the exhaust port (for the gas exhaust pipe 60) are used. This is because when the distance between the cleaning gas and the inlet is long and the path is complicated, the cleaning gas can reach the whole quickly.

In the description of the above embodiments and examples, a batch processing apparatus for processing a plurality of substrates is used as the substrate processing apparatus. However, the present invention is not limited to this, and may be a single wafer processing apparatus. You may.

As described above, the present invention is characterized by the matters described in the claims, and further includes the following embodiments.
(1) a reaction tube, a gas introduction tube communicating with the reaction tube, a gas exhaust tube communicating with the reaction tube and having an opening / closing member, an exhaust stop means provided in the gas exhaust tube, and the gas introduction Cleaning gas supply means for supplying a cleaning gas to the tube; and exhausting from the gas exhaust pipe is stopped while the cleaning gas supply means supplies the cleaning gas into the reaction tube via the gas introduction pipe. In order to ensure that there is no exhaust gas, exhaust gas is substantially exhausted from a predetermined point in time before the supply of the cleaning gas from the gas introduction pipe into the reaction tube to a point in time when several seconds have elapsed from the start of the supply of the cleaning gas into the reaction tube. And a control means for controlling an opening degree of the closing member so as to stop the operation.
(2) The cleaning from the gas introduction pipe into the reaction tube is performed so that the exhaust from the gas exhaust pipe is stopped while the cleaning gas is supplied from the gas introduction pipe into the reaction tube. A substrate for substantially stopping the exhaust from a predetermined point in time before supplying the gas to a point in time when several seconds have elapsed from the start of supplying the cleaning gas into the reaction tube, and filling the inside of the reaction tube with the cleaning gas under the control of the control unit. A method for manufacturing a semiconductor device having a processing step.

  As described above, according to the present invention, while the cleaning gas is being supplied from the gas introduction pipe into the reaction tube, the gas introduction is performed so that the exhaust from the gas exhaust pipe is stopped. From a predetermined point in time before the supply of the cleaning gas into the reaction tube from the tube to a point in time when several seconds have elapsed from the start of the supply of the cleaning gas into the reaction tube, the exhaust is substantially stopped, and the inside of the reaction tube is filled with the cleaning gas. Therefore, the cleaning gas can be uniformly diffused in the reaction tube, and the inside of the reaction tube can be uniformly cleaned.

1 is a perspective view illustrating a substrate processing apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a reaction furnace used in the substrate processing apparatus according to the embodiment of the present invention. FIG. 2 is a gas system diagram showing a gas system of the substrate processing apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating a processing flow of a cleaning step in the substrate processing apparatus according to the embodiment of the present invention. 6 is a time chart of a cleaning step in the substrate processing apparatus according to the embodiment of the present invention. 9 is a flowchart illustrating a processing flow of a cleaning process in a substrate processing apparatus according to another embodiment of the present invention. It is sectional drawing which shows the conventional reaction furnace.

Explanation of reference numerals

Reference Signs List 20 substrate processing device 52 reaction tube 58 gas introduction tube 60 gas exhaust tube 66 closing member 110 control device

Claims (1)

In a substrate processing apparatus including a gas introduction pipe communicating with the reaction pipe and a gas exhaust pipe having a closing member,
While supplying the cleaning gas from the gas introduction pipe into the reaction tube, in order that there is a state in which the exhaust from the gas exhaust pipe is stopped,
From a predetermined point in time before the supply of the cleaning gas into the reaction tube from the gas introduction pipe to a point in time when several seconds have elapsed from the start of supply of the cleaning gas into the reaction tube,
A control unit that controls an opening degree of the closing member so as to substantially stop the exhaust,
A substrate processing apparatus, wherein the inside of the reaction tube is filled with a cleaning gas under the control of the control unit.

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