JP2004153185A - Substrate processing method - Google Patents

Abstract

Provided is a processing method capable of reducing the number of times a load lock chamber is opened even when a dummy wafer is used.
According to a processing method, dummy wafers are accommodated together with a plurality of semiconductor wafers to be processed in wafer cassettes (30a, 30b) set in load lock chambers (16a, 16b). I'm going to do it. This eliminates the need to replace the semiconductor wafer to be processed and the dummy wafer, thereby reducing the number of times the load lock chamber is opened.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a substrate processing method performed by a substrate processing apparatus such as a single wafer type semiconductor manufacturing apparatus.
[0002]
[Prior art]
In a single-wafer multi-chamber type semiconductor manufacturing apparatus, a plurality of semiconductor wafers are generally set in a load lock chamber in a load lock chamber, and the semiconductor wafers are transferred one by one to a processing chamber to perform processing. It is supposed to be. In the load lock chamber, the semiconductor wafer is set in a state housed in a wafer cassette. Conventionally, a wafer cassette accommodates one lot (usually 25) of semiconductor wafers (see Patent Document 1).
[0003]
The load lock chamber is connected to a high-purity atmospheric pressure chamber called a factory interface. A plurality of wafer cassettes accommodating one lot (25 wafers) of semiconductor wafers are also set in the factory interface, and semiconductor wafers are transferred between the wafer cassettes and the wafer cassettes in the load lock chamber. It is performed in units of one lot.
[0004]
[Patent Document 1]
JP 2001-127136 A (FIG. 1)
[0005]
[Problems to be solved by the invention]
In such a semiconductor manufacturing apparatus, at least one of the processing chambers may require a dummy wafer. For example, in a semiconductor manufacturing apparatus having a processing chamber for plasma etching of a polysilicon film, dry cleaning by plasma may be performed in order to remove carbon components and the like deposited on the inner wall surface of the chamber. A dummy wafer is used. This is because the surface of an electrostatic chuck used in an etching process chamber is often a dielectric layer made of an organic material such as polyimide, and such a dielectric layer is affected by plasma. This is because the body layer is covered and protected by the dummy wafer.
[0006]
However, conventionally, when a dummy wafer is used, the load lock chamber is opened after all the semiconductor wafers contained in the wafer cassette in the load lock chamber have been etched, and the semiconductor wafer is taken out and replaced with the dummy wafer. It was necessary to work. Then, the pressure in the load lock chamber is reduced, and thereafter, cleaning is performed using a dummy wafer, and seasoning is performed using another dummy wafer as necessary. Thereafter, when the etching is restarted, it is necessary to open the load lock chamber again and replace the used dummy wafer with a new semiconductor wafer.
[0007]
Further, in such a processing method, there is also a problem that the load lock chamber is opened many times. That is, after the load lock chamber is opened, it is necessary to reduce the pressure for the next step. However, since the reduction requires a relatively long time, there is a problem that the efficiency of the semiconductor manufacturing apparatus is low.
[0008]
Therefore, an object of the present invention is to provide a substrate processing method that can solve the above-described problem when using a dummy wafer.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a substrate processing method according to the present invention opens a load lock chamber in a single-wafer-type substrate processing apparatus such as a single-wafer-type semiconductor manufacturing apparatus, and processes a substrate to be processed such as a semiconductor wafer to be processed. A dummy substrate such as a dummy wafer is accommodated in a wafer cassette in the load lock chamber, and then the load lock chamber is closed to reduce the inside pressure to a predetermined degree of vacuum. After performing the processing and the predetermined processing of the dummy substrate, and after the predetermined processing of the substrate to be processed and the predetermined processing of the dummy substrate are completed, the inside of the load lock chamber is opened, and the processing of the substrate to be processed is taken out of the wafer cassette. Features. Along with taking out the substrate to be processed, a dummy substrate may be taken out. In this method, it is not necessary to replace the substrate to be processed and the dummy substrate, and it is possible to save the time required for decompression of the load lock chamber.
[0010]
The predetermined processing of the substrate to be processed may be a plasma processing such as plasma etching, and the predetermined processing of the dummy substrate may be cleaning or seasoning.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 shows a semiconductor manufacturing apparatus (substrate processing apparatus) to which the present invention can be applied. The illustrated semiconductor manufacturing apparatus 10 is a so-called single wafer type multi-chamber type. That is, in the semiconductor manufacturing apparatus 10, a plurality of processing chambers 14a, 14b, 14c, 14d and load lock chambers 16a, 16b are connected around a base block called a main frame monolith 12. Using the transfer robot 20 provided in the transfer chamber 18 in the monolith 12, semiconductor wafers (substrates to be processed) W are transferred one by one between the load lock chambers 16a and 16b and the processing chambers 14a to 14d and processed. You can do it. As such a single-wafer multi-chamber type semiconductor manufacturing apparatus, for example, “Centure (registered trademark)”, “Producer (registered trademark)”, “Endura (registered trademark)” and the like by Applied Materials, Inc. of the United States. What is manufactured and sold under the name is known.
[0013]
In the present embodiment, the processing chambers 14a to 14d are used for plasma etching of the polysilicon film on the semiconductor wafer W, and all have the same configuration, in order to facilitate understanding. In the plasma etching of the polysilicon film, a deposit (for example, a deposit such as a carbon component contained in a photoresist) attached to the inner wall surfaces of the processing chambers 14a to 14d by the plasma etching process is cleaned every predetermined number of sheets. This cleaning is performed by introducing a cleaning gas into the processing chambers 14a to 14d to generate plasma. After the cleaning, seasoning is usually performed. Seasoning refers to a process of performing etching using a dummy wafer (dummy substrate) in order to stabilize process conditions in the processing chambers 14a to 14d after cleaning.
[0014]
A pedestal (substrate support) 22 on which the semiconductor wafer W is placed is disposed inside each of the processing chambers 14a to 14d. On the upper surface of the pedestal 22, the semiconductor wafer W is fixed by electrostatic attraction. Is provided. The electrostatic chuck 24 is composed of a dielectric layer such as polyimide and an electrode disposed below the dielectric layer, and the semiconductor wafer W is placed and fixed on the upper surface of the dielectric layer. become.
[0015]
In FIG. 1, reference numeral 26 denotes an orientation chamber for aligning the direction of the semiconductor wafer W, and reference numeral 28 denotes a cool-down chamber for lowering the temperature of the processed semiconductor wafer W.
[0016]
In the load lock chambers 16a and 16b, wafer cassettes 30a and 30b for accommodating a plurality of semiconductor wafers W at predetermined intervals in the vertical direction are set. As shown in FIG. 2, the wafer cassette 30a (the same configuration as the wafer cassette 30b) includes left and right side plates 32 and 34, and an upper plate 36 and a lower plate 38 connecting between upper and lower ends thereof. It is an open, so-called pass-through type. A shelf 40 is formed on each of the opposing surfaces of the left and right side plates 32 and 34, and the semiconductor wafer W is placed thereon. In the present embodiment, the number of the shelf stages 40 is 29, and it is possible to accommodate 29 semiconductor wafers W. Conventionally, in general, the number of stages is 25 for one lot, that is, when one lot has 25 sheets, but it should be noted that in the present embodiment, the number of stages is larger than that. This number of stages will be described in more detail below. In FIG. 2, the number of shelf steps 40 is less than 29 for simplicity.
[0017]
The wafer cassettes 30a and 30b are set in a cassette indexer 42 provided in the load lock chambers 16a and 16b. The cassette indexer 42 mainly includes a cassette stage 44 on which the wafer cassettes 30a and 30b are placed, and a stepping motor 46 for moving the cassette stage up and down. The cassette stage 44 is controlled by controlling the stepping motor 46. It is possible to arrange the wafer cassettes 30a and 30b on 44 at a desired height position. Thus, the semiconductor wafer W placed on the shelf 40 of the wafer cassettes 30a and 30b is appropriately selected and transferred to the wafer support blade 48 of the transfer robot 20, or the wafer cassettes 30a and 30b are transferred by the transfer robot 20. The processed wafer W can be accommodated in a desired shelf 40b of 30b.
[0018]
A factory interface 50 is connected to the load lock chambers 16a and 16b. The factory interface 50 is a relatively large chamber whose inside is maintained at atmospheric pressure and a predetermined cleanliness. The factory interface 50 has a plurality of (four in the illustrated embodiment) portable wafer cassettes 52a, 52b, 52c, 52d, a bay area 54 in which external setting is possible, and a bay area 54 set in the bay area 54. And a transfer area 58 provided with a transfer robot 56 for transferring semiconductor wafers W between the wafer cassettes 52a to 52d and the wafer cassettes 30a and 30b in the load lock chambers 16a and 16b.
[0019]
The semiconductor wafers W are accommodated in lots in the cassette wafers 52a to 52d placed in the bay area 54 of the factory interface 50 as in the related art. That is, in this embodiment, since one lot is 25 wafers, each wafer cassette 52a to 52d can accommodate 25 semiconductor wafers W.
[0020]
Next, a procedure for plasma etching a polysilicon film on a semiconductor wafer W according to the substrate processing method of the present invention in the semiconductor manufacturing apparatus 10 having the above configuration will be described. In the present embodiment, the four processing chambers 14a to 14d execute the same etching process, and each of the processing chambers 14a to 14d performs a dry process every time the etching of six semiconductor wafers W is completed. Cleaning and subsequent seasoning are performed.
[0021]
First, three wafer cassettes 52a to 52c accommodating 25 semiconductor wafers W to be processed and one wafer cassette 52d accommodating 25 dummy wafers (not particularly shown) are prepared in the factory interface 50. At a predetermined position in the bay area 54. When the setting of the wafer cassettes 52a to 52d is completed, the factory interface 50 is shut off from the outside.
[0022]
Next, the doors 60a, 60b on the factory interface 50 side of the two load lock chambers 16a, 16b are opened, and the transfer robot 56 is used to move the two wafer cassettes 52a, 52b in the bay area 54 into the load lock chambers 16a, 16b. 25 semiconductor wafers W are transferred to each of the wafer cassettes 30a and 30b. Further, the transfer robot 56 takes out the dummy wafers from the wafer cassette 52d and inserts four wafers into each of the wafer cassettes 30a and 30b in the load lock chambers 16a and 16b. When the semiconductor wafer W and the dummy wafer are transferred, it is preferable that one wafer cassette 30a accommodates dummy wafers in the upper four stages and the other wafer cassette 30b accommodates dummy wafers in the lower four stages. This takes into account that the cassette indexer 42 normally takes out the semiconductor wafers W in order from above the wafer cassettes 30a and 30b, but the present invention is not particularly limited to this accommodation method.
[0023]
When the transfer of the semiconductor wafer W and the dummy wafer is completed, the doors 60a, 60b of the load lock chambers 16a, 16b on the factory interface 50 side are closed, and the pressure inside the load lock chambers 16a, 16b is reduced to a predetermined degree of vacuum. Thereafter, the door 62a on the transfer chamber 18 side of the one load lock chamber 16a is opened, and the semiconductor wafers W are taken out one by one from the wafer cassette 30a by using the transfer robot 20 in the transfer chamber 18, and the four processing chambers 14a To 14d, and placed and fixed on the electrostatic chuck 24. Then, plasma etching of the polysilicon film of the semiconductor wafer W is performed in each of the processing chambers 14a to 14d according to a predetermined process. For each of the processing chambers 14a to 14d for which etching has been completed, the processed semiconductor wafer W is taken out therefrom and returned to the original position of the wafer cassette 30a. The doors 62a and 62b of the load lock chambers 16a and 16b are closed except when the wafer is loaded or unloaded.
[0024]
After the etching of a predetermined number (six in this embodiment) of the semiconductor wafers W in each of the processing chambers 14a to 14d is completed, cleaning of the processing chambers 14a to 14d is performed. When performing cleaning, a dummy wafer is taken out of the wafer cassette 30a, and is placed and fixed on the electrostatic chuck 24 in the processing chambers 14a to 14d. Then, by introducing a cleaning gas into the processing chambers 14a to 14d to generate plasma, deposits such as carbon components adhered to the inner wall surfaces of the chambers are removed. The removed deposit is discharged out of the chambers 14a to 14d by a vacuum pump (not shown). At the time of this cleaning, even if the surface of the electrostatic chuck 24 is a dielectric layer made of an organic material such as polyimide, the surface of the electrostatic chuck is protected from plasma by the presence of the dummy wafer, and the influence on the dielectric layer is prevented or suppressed. When the cleaning is completed, the dummy wafer is taken out of the processing chambers 14a to 14d and returned to the original position of the wafer cassette 30a.
[0025]
When the etching of the 24 semiconductor wafers W is completed in this way and the cleaning using the four dummy wafers is also completed, the other load lock is performed to season each of the processing chambers 14a to 14d. The door 62b of the chamber 16b on the side of the transfer chamber 18 is opened, and a dummy wafer is taken out from the wafer cassette 30b therein and transferred onto the electrostatic chuck 24 in each of the processing chambers 14a to 14d. When the seasoning of at least one processing chamber 14a is completed, etching in the processing chamber 14a becomes possible, so that one remaining semiconductor wafer W in the load lock chamber 16a is transferred there, and the etching is performed. Do.
[0026]
When the necessary processing is performed on all of the semiconductor wafers W and the dummy wafers in one load lock chamber 16a in the processing chambers 14a to 14d, the door 60a on the factory interface 50 side of the load lock chamber 16a is closed. After opening, the transfer robot 56 returns the semiconductor wafer W and the dummy wafer to the original positions of the wafer cassettes 52a and 52d, respectively. Then, 25 new semiconductor wafers W are taken out from the wafer cassette 52c and transferred to the wafer cassette 30a in the load lock chamber 16a, and four new dummy wafers are transferred from the wafer cassette 52d to the wafer cassette 30a. Thereafter, the door 60a of the load lock chamber 16a is closed and the inside thereof is depressurized, so that the processing can be performed at any time.
[0027]
When the seasoning for the remaining three processing chambers 14b to 14d is also completed, the etching processing of the semiconductor wafer W in the load lock chamber 16b is performed together with the other processing chamber 14a. Become.
[0028]
As described above, it is not necessary to open the doors 60a and 60b on the factory interface 50 side of the load lock chambers 16a and 16b immediately after the processing of one lot of the semiconductor wafer W is completed, and the dummy lock is performed by using the dummy wafer. Since the cleaning can be performed after the cleaning or the seasoning, the number of times of opening the doors 60a and 60b can be reduced. Each time the doors 60a and 60b are opened, a process of reducing the pressure inside the load lock chambers 16a and 16b is required. Therefore, the reduction in the number of times the doors are opened increases the processing time and thus improves the efficiency of the semiconductor manufacturing apparatus 10. It will be.
[0029]
In the above-described embodiment, in the semiconductor manufacturing apparatus 10, all of the four processing chambers 14a and 14b are the same etching chamber. However, for example, only one processing chamber is used for etching, and the other chamber is used for CVD or PVD. Etc. for other processing. In this case, since the number of dummy wafers required during processing of one lot of semiconductor wafers W is different, it is necessary to store four dummy wafers in the wafer cassettes 30a and 30b as in the above embodiment. Instead, one to three sheets may be used. If five or more dummy wafers are required, the number of wafers accommodated in the wafer cassettes 30a and 30b may be the number obtained by adding the required number of dummy wafers to the number of wafers for one lot.
[0030]
Further, the processing chamber requiring a dummy wafer is not limited to the etching chamber, but may be variously conceived such as a polysilicon CVD processing chamber. The present invention can be applied to a semiconductor manufacturing apparatus having such a processing chamber. Further, the present invention is not limited to a semiconductor manufacturing apparatus, but can be similarly applied to a substrate processing apparatus for a substrate for a liquid crystal display.
[0031]
【The invention's effect】
As described above, according to the present invention, even when a dummy substrate is used, two types of substrates, a substrate to be processed and a dummy substrate, can be arranged in the load lock chamber. There is no need to replace the.
[0032]
Since the replacement work is not required, the number of times the load lock chamber is opened, that is, the number of times the load lock chamber is depressurized is reduced, and the processable time of the substrate to be processed is increased accordingly. Therefore, processing efficiency is improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing a semiconductor manufacturing apparatus to which the present invention can be applied.
FIG. 2 is a perspective view schematically showing a form of a wafer cassette disposed in a load lock chamber in the semiconductor manufacturing apparatus of FIG.
[Explanation of symbols]
10 semiconductor manufacturing apparatus (substrate processing apparatus), 14a, 14b, 14c, 14d processing chamber, 16a, 16b load lock chamber, 18 transport chamber, 20 transport robot, 24 electrostatic chuck, 30a, 30b Wafer cassette, 42: cassette indexer, 50 factory interface, 52a, 52b, 52c, 52d: wafer cassette, 56: transfer robot.

Claims (3)

The load lock chamber in the single-wafer type substrate processing apparatus is opened, and the substrate to be processed and the dummy substrate are accommodated in a wafer cassette in the load lock chamber,
After closing the load lock chamber and depressurizing the inside to a predetermined degree of vacuum, the substrate processing apparatus performs predetermined processing of the target substrate and predetermined processing of the dummy substrate,
After the predetermined processing of the substrate to be processed and the predetermined processing of the dummy substrate are completed, the inside of the load lock chamber is opened, and the substrate to be processed is taken out of the wafer cassette.
A substrate processing method characterized by the above-mentioned. The substrate processing method according to claim 1, wherein the predetermined processing of the substrate to be processed is a plasma processing. 3. The substrate processing method according to claim 1, wherein the predetermined processing of the dummy substrate is cleaning or seasoning.

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