JP2000353732A - Method for processing substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process a substrate stably by deciding whether or not a cooling unit, to which a substrate can be carrier from a heating unit within a predetermined time, is idle when a carrying means is to receive the substrate from the heating unit or after receiving it. SOLUTION: After a wafer W is heated in a heating unit 23, it is to be carried into a cooling unit 24 therefrom within a predetermined time, so that the wafer W is still hot and does not exceed a predetermined time, even after it is carried from the heating unit 23, namely, the overbaking can be prevented and the excessive thinning of a resist film be also prevented. Furthermore, since the influence of in-plane temperature distribution is eliminated midway of transfer of the wafer, variation in the film thickness can be prevented. After the wafer is delivered to the cooling unit 24, a variation of temperature stabilizing time is eliminated, so that the film thickness can be kept uniform. As a result, a resist can be applied stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing apparatus for applying, exposing and developing a resist solution on a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display.

[0002]

2. Description of the Related Art In a photolithography technique in a semiconductor device manufacturing process, a resist is applied to a surface of a semiconductor wafer (hereinafter, referred to as a wafer), the coated resist is exposed to a predetermined pattern, and further developed to develop a predetermined pattern. A resist film is formed. Such a series of processing is performed by a system in which an exposure apparatus is connected to a coating / developing apparatus.

FIG. 7 is a schematic view showing a conventional example of such an apparatus. A substrate cassette C containing 25 substrates, for example, 25 semiconductor wafers, is carried into a cassette stage 1 of a cassette station CS. A coating block S1 and a developing block S2 are connected to the cassette station CS in this order, and an exposure apparatus S3 is connected to the developing block S2 via an interface station IF. The wafer W in the cassette C on the cassette stage 1 is taken out by a transfer arm (not shown) and sent to the coating block S1 via the transfer table 11.
In the coating block S1, the wafer W
A resist is applied thereon, and then the wafer W is transferred to the main arm MA1 → the transfer table 13 → the main arm MA2 of the developing block S2 → the transfer table 14 → the interface I.
F → conveyed along the path of the exposure device S3 to be exposed. In the coating unit S1, pre-processing and post-processing are respectively performed in the shelf unit 15 before and after the application of the resist.

The exposed wafer W is conveyed to the developing block S2 by the reverse route and developed by the developing unit 16, and then the main arm MA2 → the transfer table 13 → the main arm.
The transfer is performed along a route from the master MA1 to the transfer table 11 to the cassette C. In the developing unit S2, pre-processing and post-processing are respectively performed in the shelf unit 17 before and after the developing processing.

[0005]

A heating unit and a cooling unit are assigned to the shelf unit 15. The heating unit and the cooling unit are provided with a heating plate and a cooling plate, respectively. Has become. The substrate coated with the resist is first transported to a heating unit and heated to volatilize a solvent, and then transported to a cooling unit and cooled. FIG. 8 shows a temporal change in the temperature of the substrate in this flow.
Is a time zone during which the sheet is transported from the heating unit to the cooling unit.

[0006] Incidentally, the shelf unit 15 is actually also provided at the position of the transfer tables 11 and 13, and a part of the shelf unit 15 is assigned to the transfer tables 11 and 13. Further, the heating unit and the cooling unit are dispersedly arranged on these shelf units 15. Therefore, when the heating process of the substrate is completed, the control unit searches for a vacant cooling unit and transfers it to the vacant cooling unit. However, the transfer time T0 varies depending on the combination of the heating unit and the cooling unit.

However, if the transport time T0 is long,
The board is exposed to a hotter state than expected,
The evaporation of the solvent proceeds too much, and the film thickness of the resist becomes thin. Further, if the substrate is at a high temperature in a state away from the heating unit, the surroundings cool down, so that a temperature distribution is formed, which is reflected in the film thickness distribution. Furthermore, the temperature stabilization time in the cooling unit varies depending on the transport time T0. When the device thickness is large, such a problem is not a problem. However, when the device is miniaturized and the film thickness is reduced, variation in the transport time T0 affects the thickness and distribution of the resist film. The degree increases, which causes a decrease in yield.

In the case of a chemically amplified resist, when heating after exposure, it is necessary to control the heating time with high precision, and the variation in the transport time also has a great effect on the development processing. In order to avoid such a problem, it is effective to arrange a heating plate and a cooling plate on the same shelf and to incorporate a transporting means for exclusively transporting between them.
The device becomes large-scale.

The present invention has been made under such circumstances, and an object of the present invention is to provide a substrate processing method capable of performing stable processing.

[0010]

According to the present invention, a plurality of heating units and a plurality of cooling units are used to heat a substrate, which has been subjected to a predetermined process, by one of the plurality of heating units, and then by a transfer means. In the method of cooling by transferring to one of a plurality of cooling units, when the transfer means goes to receive a substrate with respect to the heating unit or after receiving the substrate, the transfer unit transfers the substrate within a preset time from the heating unit. It is characterized in that it includes a step of determining whether or not a cooling unit capable of performing the operation is available, and a step of transporting a heated substrate to an available cooling unit, if any.

Therefore, according to the present invention, overbaking is suppressed, so that a predetermined process, for example, a resist coating process is stabilized. In this case, an alarm may be issued when the cooling unit capable of being conveyed within the preset time is not empty. Further, when the cooling unit that can be transported within the preset time is not empty, for example, the substrate is transported to another empty cooling unit, and the process history of the substrate may be left. This makes it easier to analyze the processing results later.
Further, when the cooling unit that can be transported within the preset time is not empty, the substrate is transported to another empty cooling unit, and the subsequent processing is interrupted for the substrate and the result of the processing is examined. Alternatively, the subsequent processing may not be performed on the substrate.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The coating method of the present invention is described below.
An embodiment applied to a pattern forming apparatus for forming a resist pattern on the surface of a substrate will be described. 1 and 2 are a schematic plan view and an overall view of the entire pattern forming apparatus, respectively. In FIG. 1, CS is a cassette station, which includes a coating block 100 and a developing block 20.
0, the exposure apparatus 300 is connected, for example, along a straight line.

The cassette station CS mounts a cassette stage, for example, four cassettes C, on which a wafer cassette (hereinafter simply referred to as a cassette) C, which is a substrate cassette containing a plurality of substrates, for example, 25 wafers W, is mounted. A cassette stage 21 is provided, and a transfer arm 22 is a transfer unit for transferring a wafer W between the cassette stage 21 and the cassette C on the cassette stage 21.
The transfer arm 22 is configured to be movable up and down, movable in X and Y directions, and movable around a vertical axis. The coating block 100 is connected to the cassette station CS, and includes a coating unit 3 as a processing unit, three shelf units R1, R2 and R3 having multi-stage shelves, and two main arms as transfer means. 2 and 3 (not shown in FIG. 2 for convenience), and a buffer carrier 20 as a dedicated storage unit. The coating units 3 are provided two by two in two layers. For example, when an antireflection film is formed on a wafer W as a substrate, a resist coating unit is provided in two upper units and an antireflection film is provided in two lower units. Of coating units are respectively assigned. The coating unit 3 is, for example, a so-called spin coating apparatus in which a wafer W is placed on a holding table, a coating liquid is supplied from above, the holding table is rotated, and the coating liquid is extended by the centrifugal force. The main arms 31 and 32 transfer the wafer W to the shelf units R1, R2 and R3 and the coating unit 3.

The shelf unit R1 (R2, R3) includes a heating unit 23 for heating the wafer W, as shown in FIG.
A cooling unit 24 for cooling the wafer, a transfer unit 25 provided with a transfer table for transferring the wafer W, and a positioning unit 26 for positioning the wafer W are vertically arranged. Further, for example, the shelf unit R2 is provided with a transfer table 20 for transferring the wafer W between the main arms 31 and 32. In FIG. 3, the shelf units R2 and R3 are shown side by side for convenience. The arrangement shown in FIG. 3 is an example for showing an image, and is not limited to this arrangement.

As shown in FIG. 3, the heating unit 23 is provided with a heating plate 23b having a built-in heater (not shown) in a shelf main body 23a.
For example, three pins (not shown) project from the heating plate 23b to lift the wafer W, and the wafer W is transferred from the space between the wafer W and the surface of the heating plate 23b. This is performed by retracting (or entering) the arms 31 and 32. These pins are arranged at positions where they do not interfere with the main arms 31 and 32 in a planar manner. The cooling unit 24 has the same configuration except that a cooling plate that can be adjusted to a predetermined cooling temperature by using, for example, a Peltier element or a cooling liquid is provided instead of the heating plate. .

As shown in FIG. 4, the main arms 31 and 32 include an arm 41 for holding a wafer W, a base 42 for supporting the arm 41 so as to be able to move forward and backward, and a base 42 for supporting the base 42 so as to be able to move up and down. And a rotation drive unit 44 for driving the base 43 rotatably about a vertical axis. The arm 41 has a three-stage configuration so as to be able to hold the wafer W, and the peripheral edge of the wafer W is placed on, for example, three pieces of claw portions 45 provided at each stage. .

Here, a control system of the main arm 31 (32) will be described with reference to FIG. The computer constituting the control system includes a memory M1 for storing the usage status of the heating unit 23 and the cooling unit 24, and a table describing whether or not the heating unit 23 can be conveyed from the heating unit 23 to the cooling unit 24 within a predetermined time. A memory M2;
A memory M3 for recording the history of the wafer W, and a CPU
(Central processing unit) 46.

The memory M1 stores information as to whether each of the heating units 23 and the cooling units 24 are currently in use or empty. The memory M2 stores, for each heating unit 23, the time from when the wafer W is delivered to the main arm 31 (32) by the heating unit 23 to when the wafer W is delivered to each cooling unit 24 in advance. The information on whether the time is within a predetermined time or takes a longer time is stored. In FIG. 5, the case within a predetermined time is indicated by “○”, and the case longer than that is indicated by “×”. This predetermined time, after applying and heating the resist solution, the time until the transfer to the cooling unit, the thickness of the resist film and its distribution are checked,
It is set as the time when it is determined that there is no problem. In FIG. 5, BA is a bus, 40 is an alarm generator, 47 is an arm drive, and the main arm 31 (32) is driven and controlled by the arm drive 47 based on a command from a computer.

The developing block 200 includes a shelf unit R on the back side and the left side, respectively, as viewed from the cassette station CS.
4, R5 are provided, and two developing units 5 are provided on the right side. Shelf units R4, R5
Has almost the same configuration as the shelf units R1 to R3. In this example, the heating units and the cooling units are dispersedly arranged. In the case of transport from the heating unit to the cooling unit, the transport and the processing are performed in the same manner by the same control system as shown in FIG.

The developing unit 5 has substantially the same structure as the coating unit 3, except that the developing solution supply nozzle is provided with a large number of supply holes arranged in the diameter direction of the wafer W. At the center of the developing block 300, a main arm 5 similar to the main arms 31 and 32 is provided.
1 is provided, and the wafer W is transferred between the transfer unit of the shelf unit R3, the shelf units R4 and R5, and the developing unit 5.
Is carried.

An interface station 61 is connected next to the development block 200. An exposure apparatus 30 for exposing a wafer W on which a resist film is formed is provided behind the interface station 61.
0 is connected. Interface station 6
1 includes a transfer arm 62 that is movable in the X and Y directions and up and down directions and that is rotatable about a vertical axis. The transfer arm 62 includes a developing block 200 and an exposure device 30.
The transfer of the wafer W is performed between 0.

Next, the operation of the above embodiment will be described. First, a cassette C containing, for example, 25 wafers W is loaded into the cassette stage 21 by an automatic transfer robot (or an operator), and the wafer W is taken out of the cassette C by the transfer arm 22 to be stored in the shelf unit of the coating block 100. It is placed in the transfer section 26 in R1. The wafer W is coated with a coating unit 3 for an anti-reflection film.
After the formation of the anti-reflection film, the film is transported to the resist coating unit 3 where the resist is coated.

FIG. 6 is a flow chart showing the flow from the point where the resist is applied to the wafer W. When the resist is applied in step S1, the wafer W is transferred to the heating unit 24 and heated for a predetermined time. (Step S2). Specifically, the CPU 46 refers to the data in the memory M1 and refers to the vacant heating unit 2
The main arm 31 (or 32) is transferred via the arm drive unit 47 so as to transfer the wafer W after resist application to the wafer 3
Control.

The wafer W is mounted on the heating plate 23b of the heating unit 23 from the main arm 31 as described above, and is heated at a temperature of, for example, 90 to 100 ° C. for a predetermined time to evaporate the solvent in the resist film. Let it.

After that, the main arm 31 is
3b (step S3), and the CPU
Reference numeral 46 refers to the table in the memory M2 to search for a cooling unit (a nearby cooling unit) 24 that can be transported within a predetermined time. For example, now the main arm 31 is
If the wafer W is received from (HP3), “○”
It is marked. Cooling unit 24 (in this case CP2
CPm) is read out, and it is checked with reference to the memory M1 whether any of the cooling units 24 (CP2 to CPm) is vacant (step S4).
If there is an empty cooling unit 24, the main arm 3
1 (32) transfers the wafer W to one of the cooling units 24 (step S5). The wafer W is cooled to, for example, 23 ° C. by the cooling unit 24. on the other hand,
When the cooling unit 24 (a nearby cooling unit) that can be transported within the predetermined time is not empty, the cooling unit 24 is transported to the cooling unit 24 (remote cooling unit) marked “x” in the memory M2 (step S6), for example, a buzzer or the like. An alarm (alarm) such as turning on an alarm lamp or a message to a panel is issued by an alarm generating unit 40 (step S7) to notify an operator, and a processing history indicating that the wafer W has been processed by the remote cooling unit 24. Is stored in the memory M3 (step S8) and stored in the buffer carrier 20. The wafer W in the carrier C is subjected to a resist film thickness test.
Perform exposure processing.

In the above, the transfer of the wafer W between the main arms 31 and 32 is performed, for example, via the transfer table 20 provided in the shelf unit R3. Therefore, what corresponds to the remote cooling unit 24 with respect to the heating unit 23 in the shelf unit R1 corresponds to, for example, the heating unit in the shelf unit R2.

The cooled wafer W is transported along the path of the transfer table 25 in the shelf unit R2 → the main arm 51 of the developing block 200 → the transfer table in the shelf unit R4 → the transfer arm 62 → the exposure block 300.
After being subjected to the exposure processing in the exposure block, it is returned to the developing block 200 through the reverse route. Then, the toner is conveyed to the developing unit 5 by the main arm 51 and subjected to a developing process. Also in this development processing, heating and cooling are performed as pre-processing, and heating and cooling are performed as post-processing. In the pretreatment, the wafer W is heated to, for example, 120 ° C. to 130 ° C.,
Thereafter, it is cooled to, for example, 23 ° C. When a chemically amplified resist is used, the wafer W
Since it is necessary to accurately manage the time during which the heating is performed, similar to the case of heating and cooling after resist application, when a heating unit searches for a nearby cooling unit and is transported to a remote cooling unit , Processing such as storing a processing history is performed. The developed wafer W is
After passing through the application block 100, the carrier is returned to the original carrier C via the transfer arm 22.

According to the above-described embodiment, the wafer W is heated by the heating unit 23 and then transferred from the heating unit 23 to the cooling unit 24 which can be transferred within a predetermined time. After leaving the unit 23, the time that remains hot does not exceed a predetermined time, that is, overbake can be suppressed,
It is possible to prevent the resist film from becoming too thin. Further, while the degree of the in-plane temperature distribution is large during the transfer of the wafer W, according to this method, the influence of the in-plane temperature distribution in this case is small, and the unevenness of the film thickness can be suppressed. Further, after being transferred to the cooling unit 24, there is no variation in the temperature stabilization time, and from this point, the film thickness is stabilized, and eventually, a stable resist coating process can be performed.

Further, as will be understood later, the history of the wafer W that cannot be transferred from the heating unit 23 to the cooling unit 24 within a predetermined time is stored in a dedicated storage unit, for example, the buffer carrier 20, and the resist film is formed. Since the thickness test is performed, the state of the processing can be grasped in advance before proceeding to the subsequent exposure and development steps, and unnecessary processing can be avoided. When the history is left as described above, the subsequent processing may be continued as it is. In this case, the history can be grasped later, so that the analysis of the processing result becomes easy. When the adjacent cooling unit 24 is not vacant, the processing may be stopped for the substrate, and the processing may be performed again, for example, by removing the resist film with a solvent. Also, during the pre-processing of development, those which cannot be conveyed from the heating unit 23 to the cooling unit 24 in the vicinity are stopped, so that the subsequent useless processing can be avoided.

In the present invention, the timing for searching for an empty cooling unit 24 by the memories M1 and M2 may be before the main arms 31 and 32 receive the wafer W from the heating unit 23. The substrate is not limited to a wafer, but may be a glass substrate for a liquid crystal display.

[0031]

As described above, according to the present invention, a stable processing can be performed when heating and cooling the substrate that has been subjected to the predetermined processing.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a pattern forming apparatus used in an embodiment of the method of the present invention.

FIG. 2 is a schematic view showing the pattern forming apparatus.

FIG. 3 is a schematic side view showing the pattern forming apparatus.

FIG. 4 is a perspective view showing a main arm.

FIG. 5 is an explanatory diagram showing a control system of a main arm.

FIG. 6 is a flowchart showing a flow when the sheet is conveyed from the heating unit to the cooling unit.

FIG. 7 is a schematic plan view showing a conventional pattern forming apparatus.

FIG. 8 is a characteristic diagram showing a temperature change of a wafer.

[Explanation of symbols]

 CS cassette station W Wafer W 22 Delivery arm 23 Heating unit 24 Cooling unit 100 Coating block 200 Developing block 300 Exposure device 3 Coating unit 31, 32, 51 Main arm M1 Unit usage status memory M2 memory M3 Processing history memory 40 Alarm generator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H01L 21/027 H01L 21/30 562 566 F term (reference) 2H096 AA00 AA25 AA27 DA01 FA01 GB00 GB07 HA01 4F042 AA07 DB01 DF15 DF25 DF34 DH02 5F031 CA02 CA05 DA01 FA01 FA02 FA07 FA11 FA12 FA15 GA03 GA06 GA45 GA47 GA48 GA49 HA08 HA33 HA37 HA38 JA22 JA45 JA51 MA02 MA03 MA13 MA26 MA27 MA33 PA01 PA02 PA11 5F046 CD01 CD05 CD06 DA29 JA04 JA04 JA22 KA04

Claims (6)

[Claims] A plurality of heating units and a plurality of cooling units, wherein a substrate on which predetermined processing has been performed is heated by one of the plurality of heating units, and then transferred to one of the plurality of cooling units by a transporting means. In the method of transporting and cooling, when the transport means goes to the heating unit to receive the substrate or after receiving the substrate, a cooling unit that can be transported from the heating unit within a preset time is vacant. A substrate processing method, comprising: a step of determining whether or not a cooling unit is vacant, and a step of transporting a heated substrate to an empty cooling unit, if any. 2. The substrate processing method according to claim 1, wherein an alarm is issued when the cooling unit that can be transported within the preset time is not empty. 3. The cooling unit according to claim 1, wherein the substrate is transferred to another vacant cooling unit when there is no vacant cooling unit that can be transferred within the preset time. Substrate processing method. 4. The substrate processing method according to claim 3, wherein a history of the process is left for the substrate transported to another vacant cooling unit. 5. The substrate processing method according to claim 3, wherein the processing of the substrate transferred to another vacant cooling unit is checked thereafter. 6. The substrate according to claim 1, wherein no further processing is performed on the substrate when no cooling unit capable of carrying the substrate within the preset time is available. A method for processing a substrate as described in the above.