JPH08172046A - Semiconductor production device - Google Patents

Abstract

PURPOSE: To prevent the generation of the variation of the size of a photo-resist film due to the leaving of a wafer by computing the leaving time of the wafer until the photo-resist film is exposed after the photo-resist film is thermally treated and controlling exposure on the basis of the computed time. CONSTITUTION: A coater 1 and stepper 9 exposing and treating wafers are connected through an interface section 8. When the exposure treatment of wafers is started by the step 9, the information of the time when pre-baking is completed, lot numbers at every wafer, wafer numbers, the kinds of photo-resists used for the wafers, etc., is transmitted to an exposure control means 11 through a data transmission means 13 from a storage means 10. The leaving time of the wafers is computed on the basis of transmitted data in the exposure control means 11. The optimum quantities of each wafer exposed are obtained by referring to exposure sensitibility fluctuation characteristic data stored in the exposure control means 11. The stepper 9 is controlled by the obtained optimum quantities of the wafers exposed, and the wafers are exposed and treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and is particularly suitable for application to an exposure apparatus for exposing a photoresist coated on a wafer.

[0002]

2. Description of the Related Art In a lithography process in a conventional semiconductor manufacturing apparatus, an oxide film or a nitride film deposited on a wafer,
Alternatively, in order to pattern a metal film or selectively introduce impurities into the wafer, a photoresist is applied to the surface of the wafer, and the photoresist is exposed using light or an electron beam, and then exposed. The photoresist pattern is formed on the wafer by developing the photoresist. That is,
The usual lithography process includes a coating process for coating a photoresist on a wafer, a pre-baking process for performing a baking process for removing a solvent in the photoresist (hereinafter referred to as a pre-baking process), and an exposure for exposing the photoresist. In general, the process comprises a developing process of developing the exposed photoresist.

A conventional semiconductor manufacturing apparatus for performing lithography (hereinafter referred to as a lithography apparatus) is shown in FIG.
Will be described with reference to. FIG. 3 is a block diagram showing a configuration of a conventional lithographic apparatus.

In a conventional lithographic apparatus, a photoresist coating apparatus 1 (hereinafter referred to as a coater) and an exposure apparatus 9 (hereinafter referred to as a stepper) that performs exposure processing via a photomask or a reticle on which a pattern is drawn are provided. Stepper 9
The in-line type was connected via the interface section 8 for loading and unloading the wafer.

Here, the coater 1 uses, for example, 25 wafers.
A loader unit 2 having a wafer carrier (not shown) capable of accommodating one wafer, a pretreatment baking furnace 3 for performing a heat treatment on the wafer before applying the photoresist, and a resist applying unit 4 for applying the photoresist on the wafer by rotation. A pre-bake furnace 5 for heating and evaporating the solvent remaining in the photoresist film applied to the wafer in order to improve the adhesion between the wafer and the photoresist film; , A buffer unit 6 which also serves as a temporary wafer storage location and which connects the pre-bake furnace 5 and the elevator unit 7, and a buffer (not shown) of the interface unit 8 for vertically transporting the wafers accommodated in the buffer unit 6. And an elevator section 7 for supplying a wafer to the section. In addition, arrows 15, 16 shown in FIG.
Reference numeral 17 indicates the direction in which the wafer is transferred. Also,
A wafer transfer unit (not shown) for loading and unloading the wafer while holding the wafer on the arm is provided between the respective units, and the wafer transfer unit is capable of horizontal rotation, horizontal movement, and vertical movement.

In the lithographic apparatus operating in such an in-line format, the coater 1 is based on the number of delivered wafers sent from the loader unit 2 to the stepper 9 and the number of arriving wafers arriving at the interface unit 8 from the coater 1 side. The wafer is sent from the side to the stepper 9 side to perform each processing.

Since the stepper 9 is the heart of the lithography process, which is one of the most important steps in the manufacturing process of a semiconductor device, and is expensive, the stepper 9 performs the maximum wafer processing with the minimum number of steps. It was usual to operate so that the wafer processing capacity (throughput) per unit time of (1) was always kept at the maximum value. Therefore, during the operation of the lithographic apparatus, when the wafers are successively transferred from the coater 1 to the stepper 9 every one minute while receiving each processing, the processing of one lot of 25 to 50 wafers is performed. In the case where the stepper 9 has a trouble during this and the exposure process cannot be performed, the wafer being processed by each unit in the coater 1 is provided in the buffer unit 6 after the photoresist is applied as it is. It is temporarily stored in a wafer carrier (not shown). After the troubled stepper 9 is recovered, the wafer is taken out from the buffer section 6 again and sent to the stepper 9.

Therefore, in the case of the conventional lithographic apparatus, the waiting time of the wafer from the pre-baking process of the photoresist film in the pre-baking furnace 5 to the exposure process of the stepper 9 is longer than that of a normal wafer in which no trouble occurs. The length of time was significantly long, and it was necessary to perform exposure processing on a wafer that had been left for several hours after the prebake processing depending on the nature of the trouble. A conventional lithographic apparatus is described in, for example, Japanese Patent Laid-Open No. 4-85812.

[0009]

However, if the wafer leaving time after the pre-baking process becomes longer than the normal wafer leaving time due to a trouble of the stepper 9 or the like, the exposure sensitivity of the photoresist film during the exposure process is increased. However, there is a problem that the dimension of the photoresist film after development is varied between wafers or lots.

Therefore, an object of the present invention is to change the dimension of the photoresist film after development even if the exposure sensitivity of the photoresist film changes due to leaving the wafer from the prebaking process to the exposure process. It is an object of the present invention to provide a semiconductor manufacturing apparatus that can prevent the occurrence of the problem.

[0011]

In order to solve the above-mentioned problems, a semiconductor manufacturing apparatus of the present invention comprises an exposing means for exposing a photoresist film coated on a wafer, and an exposing means for coating the wafer. Storage means for storing the time at which the photoresist film is heat-treated, and the exposure means based on the leaving time of the wafer from the time stored in the storage means until the exposure is performed by the exposure means. And an exposure amount control means for controlling the exposure amount.

[0012]

According to the present invention, the exposure time of the wafer from the heat treatment of the photoresist film to the exposure by the exposure means is calculated, and the exposure amount of the exposure means is calculated based on the calculated exposure time. The exposure amount at the time of exposing the photoresist can be optimized by controlling the temperature, and even if the exposure sensitivity of the photoresist film fluctuates due to leaving the wafer from the heat treatment to the exposure treatment, It is possible to prevent fluctuations in the dimensions of the film.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A lithographic apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the arrangement of a lithographic apparatus according to an embodiment of the present invention.

In FIG. 1, a coater 1 and a stepper 9 that performs exposure processing via a photomask or reticle on which a pattern is drawn are connected to each other via an interface section 8 that carries a wafer in and out.

Here, the coater 1 uses, for example, 25 wafers.
A loader unit 2 having a wafer carrier (not shown) capable of accommodating one wafer, a pretreatment baking furnace 3 for performing a heat treatment on a wafer before photoresist coating, and a resist coating unit 4 for rotationally coating photoresist on a wafer. A pre-bake furnace 5 for heating and evaporating the solvent remaining in the photoresist film applied to the wafer in order to improve the adhesion between the wafer and the photoresist film; , A buffer unit 6 which also serves as a temporary wafer storage location and which connects the pre-bake furnace 5 and the elevator unit 7, and a buffer (not shown) of the interface unit 8 for vertically transporting the wafers accommodated in the buffer unit 6. And an elevator section 7 for supplying a wafer to the section. The arrows 15, 16 shown in FIG.
Reference numeral 17 indicates the direction in which the wafer is transferred. Also,
A wafer transfer unit (not shown) for loading and unloading the wafer while holding the wafer on the arm is provided between the respective units, and the wafer transfer unit is capable of horizontal rotation, horizontal movement, and vertical movement.

Further, the coater 1 is provided with a storage means 10 for storing information such as the time when the prebaking is completed, the lot number of each wafer, the wafer number, and the type of photoresist used for the wafer. It is stored in the memory provided in the. Data exchange between the coater 1 and the storage means 10 is performed via the data transmission means 12 such as a wiring cable. Further, the stepper 9 is provided with an exposure amount control means 11, and the exposure amount control means 11 and an arithmetic processing means such as a microprocessor for calculating the leaving time of the wafer from the end of the prebaking to the exposure processing and a photo. The optimum exposure dose data (exposure sensitivity variation characteristic data), which is the target value of the dimension of the photoresist film corresponding to the standing time from the prebaking process of the wafer coated with the resist film to the exposure, is stored for each resist type. And a storage means such as a memory. Data exchange between the storage unit 10 and the exposure amount control unit 11 is as follows.
Data is exchanged between the exposure amount control unit 11 and the stepper 9 via the data transmission unit 13 via the data transmission unit 14.

FIG. 2 is a graph showing the relationship between the standing time from the prebaking process of a wafer coated with a photoresist film to the exposure and the exposure amount in the stepper 9 where the dimension of the photoresist film is a target value. Show. Since this exposure sensitivity variation characteristic data generally greatly differs depending on the type of photoresist and the manufacturer, it is necessary to quantitatively grasp the characteristic in advance and store it in the storage means provided in the exposure amount control means 11. is there. The exposure sensitivity variation characteristic curve shown in FIG. 2 shows the optimum exposure amount in which the variation in the resist dimension after development does not occur depending on the standing time. If the exposure is not performed with this optimum exposure amount, the resist dimension becomes thin or thick. As shown in FIG. 2, depending on the type of resist, the resist size after development becomes thick unless the exposure amount is increased due to fluctuations in the exposure sensitivity of the resist as it is left for a long time.

The operation of the lithographic apparatus according to one embodiment of the invention will now be described.

First, when the exposure process of the wafer after the pre-baking in the photoresist coating process is started by the stepper 9, the time when the pre-baking is completed, the lot number for each wafer, the wafer number, and the photoresist used for the wafer. Information such as type is transferred from the storage means 10 to the data transmission means 1
3 is transmitted to the exposure amount control means 11.

Next, in the exposure amount control means 11, the prebaking is completed for each wafer number or lot number based on the data such as the wafer number supplied from the storage means 10 and the time when the prebaking is completed, and the exposure processing is performed. The wafer leaving time until the start of is calculated. Here, the wafer leaving time is the time obtained by subtracting the prebaking end time of each wafer stored in the storage means 10 from the exposure processing start time of each wafer in the stepper 9. Further, the wafers exposed by the stepper 9 are adapted to correspond to the wafers processed in the prebaking furnace 5 by the wafer number and the lot number stored in the storage means 10.

Next, by referring to the exposure sensitivity variation characteristic data stored in the exposure amount control means 11, the optimum exposure amount of each wafer is obtained from the leaving time of the wafer. Then, the exposure process is performed by controlling the stepper 9 so that the optimal exposure amount obtained by the exposure amount control means 11 is used instead of the normal exposure amount when performing the exposure process.

Next, an exposure processing method using the lithographic apparatus according to one embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, the wafer which has been subjected to the pretreatment is stored in a wafer carrier (not shown) arranged in the loader 2 by a transfer means (not shown). The wafer stored in the loader 2 is transferred to a chemical liquid coating device (not shown) by a transfer means (not shown), and an HM for increasing the adhesiveness of the resist.
After a chemical liquid such as DS ((CH ₃ ) ₃ SiNHSi (CH ₃ ) ₃ ) is applied, it is transferred into the pretreatment bake furnace 3 by a transfer means (not shown), and a heat treatment (not shown) of the pretreatment bake furnace 3 is performed. It is heat-treated by means.

After that, the wafer heated by the pretreatment baking furnace 3 is transferred to the resist coating section 4 by a transfer means (not shown), and the resist solution is spin-coated on the surface of the wafer. The wafer on which the resist has been applied is transferred into the pre-bake furnace 5 by a transfer means (not shown), and the photoresist film applied on the wafer is pre-baked by a heating processing means (not shown) in the pre-bake furnace 5. .
This pre-baking process is performed at a temperature of about 100 ° C. on a constant temperature plate (not shown) in the pre-baking furnace 5. The wafer for which the pre-baking process has been completed is once carried to the buffer section 6 by a carrying means (not shown).

The buffer section 6 is also used as a storage location for temporarily evacuating the wafer when a trouble occurs in the entire system including the coater 1 and the stepper 9. For example, when a trouble occurs in the stepper 9 and the exposure process cannot be performed, the wafer being processed in each unit of the coater 1 is continuously processed in the photoresist coating process and provided in the buffer unit 6. It is temporarily stored in a wafer carrier (not shown).

Further, in case that the wafer is left for a long period of time after the prebaking is completed and before the exposure process is performed due to a trouble of a stepper or the like, the prebaking is completed and the exposure process is not completed for each wafer. ,Lot number,
Data such as the wafer number, the pre-baking end time, and information on the type of photoresist used is supplied to the storage means 10 via the data transmission means 12 arranged in the pre-baking furnace 5 and provided in the storage means 10. Stored in the memory.

Then, when the stepper 9 is restored, the wafer accommodated in the buffer section 6 is taken out again and is transferred to the interface section 8 by the elevator section 7. At this time, data such as the lot number, the wafer number, the pre-baking end time, the information about the type of photoresist used, and the like stored in the storage means 10 are the data transmission means 13.
Exposure amount control means 1 arranged on the stepper 9 side via
1, the exposure time of the wafer is calculated based on these data, and the exposure sensitivity variation characteristic data as shown in FIG. Determine the exposure dose. The optimum exposure amount obtained by the exposure amount control means 11 is the data transmission means 14
Is sent to the stepper 9 via.

The stepper 9 performs the exposure process by changing the normal exposure amount when there is no trouble to the optimum exposure amount obtained by the standing time for each wafer. That is, the wafer on which the photoresist coating process has been completed is carried onto a stage (not shown) in the stepper 9 by a carrying means (not shown), and a latent image of a photomask or a reticle is formed on the photoresist coated on the surface of the wafer. It The exposed wafer is transported to the developing section. In the developing section, the photoresist is developed by a paddle method or the like using a developing solution such as an aqueous solution of tetramethylammonium hydroxide. The wafer that has undergone the development processing is transported to subsequent steps such as a pure water rinse step, a drying step, and a photoresist stripping step.

As described above, according to the semiconductor manufacturing apparatus of this embodiment, the resist film is exposed after the pre-baking step, which is the final step of the photoresist coating step, and before the next exposure processing step. Even if the sensitivity fluctuates, the optimal exposure amount is calculated based on the wafer leaving time and the exposure amount in the exposure process is optimized, so that the resist dimension is changed between the wafers in the developing process performed after the exposure process. Or, it can be surely prevented from changing between lots.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various effective modifications and applications are possible within the scope of the concept of the present invention. For example, the storage unit 10 and the exposure amount control unit 11
1 has described the example in which the coater 1 and the stepper 9 are separately arranged from the main body, as shown in FIG. 1, but the arithmetic processing function and the memory function built in the coater and the stepper 9 are within or within the range. If the extension can handle it,
The exposure amount may be controlled by using these functions. The same applies to the data transmission means 12, 13, and 14. Further, it is necessary that the coater 1 and the stepper 9 have a clock common to both, which is, for example,
This can be easily realized by making the clock (clock) incorporated in the computer of either the coater 1 or the stepper 9 referable to either device via the data transmission means 13. Furthermore, when changing the exposure amount of the stepper 9, the illuminance on the photosensitive surface may be changed or the exposure time may be changed. As a method of changing the illuminance on the photosensitive surface, a stepper 9
There is a method of controlling the light amount of the light source, a method of using a squeezing means, and the like.

[0031]

As described above, according to the present invention, even if the exposure sensitivity of the photoresist film varies due to leaving the wafer from the pre-baking process to the exposure process, the photoresist film is changed between lots or wafers. It is possible to prevent the size of the element from changing.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a lithographic apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a standing time from a prebaking process of a wafer coated with a photoresist film to an exposure and an exposure amount at which a dimension of the photoresist film is a target value.

FIG. 3 is a block diagram showing a configuration of a conventional lithographic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoresist coating device (coater) 2 Loader section 3 Pretreatment bake furnace 4 Resist coating section 5 Prebake furnace 6 Buffer section 7 Elevator section 8 Interface section 9 Stepper 10 Detecting means 11 Exposure amount controlling means 12, 13, 14 Data transmitting means

Claims (1)

[Claims] 1. An exposure unit for exposing a photoresist film coated on a wafer, a storage unit for storing the time when the photoresist film coated on the wafer is subjected to heat treatment, and the storage unit. And an exposure amount control unit for controlling the exposure amount of the exposure unit on the basis of the leaving time of the wafer from the time stored in the exposure unit to the exposure by the exposure unit. .