JP2002373840A - Device and method for exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner which is reducible in manufacturing cost by eliminating the need for test exposure. SOLUTION: This aligner comprises a light source 1, a shutter 2, a reticle stage 3 where a photomask 15 is set, a projection lens 4, a wafer stage 5 which is movable along X and Y axes and where a wafer 11 is set, a photodetector 6 which is buried in the wafer stage 5, a shield plate 9 which has a through hole 10 bored and covers the photodetector 6 and is provided with the through hole 10, a shutter operation control unit 7 which controls a shutter operation time and drives a shutter, and an exposure quantity calculation part 8 which calculates a pattern rate. The exposure quantity calculation part 8 automatically measures the pattern rate, and optimizes the exposure time of a photoresist film according to the pattern rate to eliminate the need for test exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus used in a photolithography process.

[0002]

2. Description of the Related Art When transferring a pattern of a photomask onto a wafer or the like, which is a substrate to be processed, by using an exposure apparatus, how to process a photoresist film covering the wafer to the dimensions according to the photomask. Is important. At this time, factors that greatly influence the resist dimensions (dimensions when the photoresist film is processed) include the type of the photoresist film, the thickness of the photoresist film, the exposure amount, the type of the developing solution, and the developing time. Usually, the relationship between the exposure time and the resist dimensions is grasped from experimental data in which these are entered as parameters, and the exposure time is determined so that the resist dimensions are within an allowable value for the photomask dimensions.

FIG. 5 is a block diagram of a main portion of a conventional exposure apparatus, and FIG. 6 is a block diagram of a main portion of a portion D in FIG. The light emitted from the light source unit 51 passes through a shutter unit 52 for determining an exposure time, a photomask 65 on which a reticle stage unit 53 is set, and a wafer 61 set on a wafer stage unit 55 via a projection lens unit 54. It reaches a photoresist film (not shown) covering the top. This light is set so that the pattern of the photomask 65 is accurately projected on the photoresist film. Also, as shown in FIG. 7, the photodetector section 56 embedded in the wafer stage section 55 is moved in the direction of arrow b by moving the wafer stage section 55 in the X direction and the Y direction.
Set to position 2.

[0006] Without setting the photomask 65, the light from the light source 51 is received by the photodetector 56, and the amount of the received light (illuminance) is converted into an electric signal. Transmit the signal. When the amount of light radiated from the light source unit 51 is reduced, the shutter operation control unit 57 controls the shutter unit 52 so as to increase the exposure time by increasing the exposure time. Increase volume. Thus, in the conventional device, when the light amount of the light source unit 51 itself decreases,
It has the function of increasing the amount of exposure.

[0005]

However, in the conventional exposure apparatus, the area of the pattern 64 of the photomask 65 used at the time of exposure (opaque (black) of a letter F in the figure).
The size of the resist (wafer 61) depends on the size of the area.
The size of the pattern 63 of the photoresist film when the photoresist film covering the upper portion is processed) varies.

For example, even with a stripe pattern having the same width, there is a difference in the resist size when the number of stripes is large or small. When the number of stripes is small, the amount of photoresist to be removed increases, and when developing with a constant amount of developing solution, the developing solution per sheet tends to be short. When the development cannot be performed sufficiently, the remaining development is left, the stripe width becomes wider than a predetermined width, and the resist dimension becomes larger than a predetermined value.

In order to avoid such inconvenience, in the conventional apparatus, an exposure time at which a resist dimension becomes a predetermined dimension in a preceding trial exposure is determined for each photomask having a different pattern, and thereafter, a main exposure is performed. I was going. If the number of photomasks is large to perform the test exposure, the number of manufacturing steps is increased and the manufacturing cost is increased. SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure apparatus which eliminates the need for test exposure and can reduce manufacturing costs.

[0008]

In order to achieve the above object, a light source section, a shutter section for determining an exposure time for a photoresist film, a reticle stage section for setting a photomask, and A projection lens unit for projecting a pattern of a photomask, a substrate stage unit for setting a substrate to be processed coated with the photoresist film, and a light source unit that receives the light from the light source unit and converts the light into an electric signal. In an exposure apparatus including a photodetector unit for conversion and a shutter operation control unit for controlling the shutter unit using an electric signal from the photodetector unit, the light is projected onto the substrate stage unit via the projection lens unit. A signal for controlling the opening / closing time of the shutter unit according to the ratio of the pattern drawn in the exposure area (pattern ratio). The a structure in which an exposure amount calculating unit to be output to the shutter operation control unit.

When the total area of the exposure region projected on the substrate stage is defined as S0, and the pattern of the photomask is defined as S1, the total area of the pattern region projected on the substrate stage is defined as: The pattern rate is S1
It is preferable to provide the exposure amount calculation unit having a function of calculating the pattern ratio, which is calculated by / S0. Further, it is preferable to include an exposure amount calculating unit that outputs the signal to the shutter operation control unit that shortens the time of the open state of the shutter unit when the pattern ratio is large, and lengthens the time of the open state when the pattern ratio is small. .

[0010] Further, the photodetector unit is covered.
It is preferable to provide a shielding plate provided with a through hole. In an exposure method in which a photoresist film covering a substrate to be processed is exposed through a photomask on which a pattern is formed, an exposure amount is determined in accordance with a ratio (pattern ratio) of a pattern drawn in an exposure region to an exposure region. Should be controlled.

Further, it is preferable that the exposure amount is controlled by the exposure time.

[0012]

FIG. 1 is a block diagram of a main part of an exposure apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a main part of a portion C in FIG. As the exposure apparatus, the case of a reduced projection exposure apparatus has been described as an example. The exposure apparatus includes a light source unit 1, a shutter unit 2, a reticle stage unit 3 for setting a photomask 15, a projection lens unit 4, and a wafer stage that can move in the X and Y directions and sets a wafer 11. Part 5, a photodetector part 6 embedded in the wafer stage part 5, and a shield plate 9 having a through hole 10 in which a through hole 10 is formed to cover the photodetector part 6.
And a shutter operation controller 7 for controlling and driving the shutter time, and an exposure calculator 8 for calculating the transmittance of the photomask 15.

The wafer stage section 5 is moved in the X and Y directions to move the photodetector section 6 to the position of the exposure area 12 (moves in the direction of arrow a). Next, light 20 of the mercury lamp of the light source unit 1 is passed through the shutter unit 2, the photomask 15 set on the reticle stage unit 3, the projection lens unit 4, and the through hole 9 provided in the shielding plate 9. Irradiation is performed on the photodetector unit 6 embedded in the wafer stage unit 5 as shown in FIG.

Next, the electric signal of the photodetector 6 is calculated by an exposure amount calculator 8 to calculate a pattern rate, and the magnitude of the pattern rate is converted into an electric signal, which is output to a shutter operation controller 7. Upon receiving the electric signal, the shutter operation control unit 7 sets the opening and closing time of the shutter unit 2.
The relationship between the pattern ratio and the time of the open state of the shutter unit 2 will be described later.

The pattern ratio is defined as the pattern 13 drawn on the exposure region 12 with respect to the total area S0 of the exposure region 12.
(S1 / S0) of the area (pattern area S1). Here, the pattern means a planar shape of the photoresist film in which the photoresist film remains after the development.
The planar shape of the photoresist film becomes an aluminum wiring pattern or the like.

Next, the wafer 1 on the wafer stage 5
1 is moved below the projection lens unit 4 to expose a photoresist film (not shown) on the wafer 11. FIG. 4 is a diagram illustrating an example of a method of calculating a pattern ratio. The first position of the through hole 10 is one corner (upper left corner in the figure) of the exposure area 12. The size of the through hole 10 is 1 mmφ, and the size of the exposure area 12 is 22 mm □. This through hole 10 is moved in the X direction at a pitch of 1 mm,
At the point where m is reached, the lens is moved by 1 mm in the Y direction, and is moved in the X direction in reverse at a pitch of 1 mm. Further, at a position where the distance reaches 22 mm, the head is moved by 1 mm in the Y direction and is moved at a pitch of 1 mm in the X direction. This operation is repeated so as to cover the entire exposure area 12. Needless to say, if the photodetector has a photodetector of 1 mmφ, the shielding plate 9 is unnecessary.

As shown in FIG. 2, for example, the pattern ratio in the case where the F pattern 14 is formed in a region that does not transmit light on the photomask 15 is calculated as follows. When the light 20 enters the through hole 10, the photodetector unit 6 receives the light, and when the light 20 does not enter,
The photo detector unit 6 does not receive light. As shown in FIG. 4, the exposure area 12 has a size of 22 mm □, and the entire exposure area is moved in the through hole 10 at a pitch of 1 mm, and passes through the through hole 10 at the photodetector section 6 below the through hole 10. The presence or absence and intensity of light are detected. The number of detection points is 52
9 points. The presence / absence and intensity of the light are converted into electric signals and transmitted to the exposure amount calculation unit 8.

This electric signal is represented by A in FIG.
When the location of the area is detected by the photodetector unit 6,
The level of the electric signal output from the photodetector unit 6 becomes zero, and the level of the electric signal becomes high when detecting the location in the area B to which light is applied. Level is in the middle. The exposure amount calculating section 8 processes the transmitted electric signal and sets a predetermined level (for example, a 50% value of a high level of the electric signal).
The following electric signals have no light, that is, are determined to be pattern portions, and are counted as “1”. An electric signal exceeding a predetermined level is determined to have no pattern, and is counted as “0”. That is, the area A where the light does not hit is counted as “1”, and the area B where the light does not hit is “0” in FIG.
Is counted.

As described above, the pattern ratio is a ratio occupied by the pattern 13 in the exposure region 12,
This is the ratio counted as "1". Specifically, in this example, the pattern rate is represented by (number counted as “1”) ÷ 529. The magnitude of the pattern ratio is converted into an electric signal, and the electric signal is transmitted to the shutter operation control unit 7. The shutter operation control unit 7 controls the opening and closing of the shutter unit 2 based on the magnitude of the pattern ratio.

When the pattern ratio increases, the development is sufficiently performed because the amount of the photoresist to be removed is small. Therefore, the time during which the shutter unit 2 is open is shortened, and the exposure time is shortened. In addition, when the pattern ratio decreases, the amount of photoresist to be removed increases, so that the developer per wafer tends to be insufficient, and it is difficult to sufficiently perform development. Therefore, in order to promote development, the time during which the shutter unit 2 is in the open state is lengthened, and the exposure time is lengthened.

According to the pattern ratio, an optimal shutter unit 2 having a constant resist size under a constant developing condition.
The opening / closing time is determined by an experiment, and the data is programmed in the exposure amount calculation unit 8, so that even when the pattern ratio is different, the main exposure is performed without the test exposure, so that the resist dimension becomes a predetermined value. be able to. By automatically performing this series of operations, it is possible to omit the test exposure process required in the conventional exposure apparatus, and to reduce the manufacturing cost.

[0022]

According to the present invention, by providing the exposure amount calculating section for calculating the pattern ratio, a predetermined resist dimension can be obtained even if the test exposure step is deleted, and the test exposure step is deleted. By doing so, manufacturing costs can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a main part of a part C in FIG. 1;

FIG. 3 is an essential part cross-sectional view showing a positional relationship between a photodetector unit, a shielding plate, and a projection lens

FIG. 4 is a view for explaining an example of a method of calculating a pattern ratio.

FIG. 5 is a block diagram of a main part of a configuration of a conventional exposure apparatus.

6 is a configuration diagram of a main part of a D part in FIG. 5;

FIG. 7 is a cross-sectional view of a main part of a photodetector section embedded in a wafer stage section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source part 2 Shutter part 3 Reticle stage part 4 Projection lens part 5 Wafer stage part 6 Photodetector part 7 Shutter operation control part 8 Exposure amount calculation part 9 Shielding plate 10 Through hole 11 Wafer 12 Exposure area 13, 14 Pattern 15 Photomask

Claims (6)

[Claims] A light source section, a shutter section for determining an exposure time to a photoresist film, a reticle stage section for setting a photomask, a projection lens section for projecting a pattern of the photomask on the photoresist film, A substrate stage section for setting a substrate to be processed coated with a photoresist film, a photodetector section installed on the substrate stage section for receiving light from a light source section and converting the light into an electric signal, and opening and closing the shutter section And a shutter operation control unit for controlling the ratio of a pattern (pattern rate) occupied in an exposure area projected onto the substrate stage unit through the projection lens unit using an electric signal from a photodetector unit. ) That outputs a signal for controlling the opening and closing time of the shutter unit to the shutter operation control unit. An exposure apparatus comprising a light amount calculation unit. 2. When the total area of an exposure area projected on the substrate stage is defined as S0 and the pattern of the photomask is defined as S1 as a total area of a pattern area projected on the substrate stage. The pattern ratio is S1 / S
2. The exposure apparatus according to claim 1, further comprising the exposure amount calculation unit having a function of calculating the pattern ratio, which is calculated as 0. 3. An exposure amount calculating section for outputting to the shutter operation control section a signal for shortening an open state time of the shutter section when the pattern ratio is large and lengthening the open state time when the pattern rate is small. The exposure apparatus according to claim 1, further comprising: 4. An exposure apparatus according to claim 1, further comprising a shielding plate provided with a through-hole and covering the photodetector portion. 5. An exposure method for exposing a photoresist film covering a substrate to be processed through a photomask on which a pattern is formed, according to a ratio (pattern ratio) of a pattern drawn in the exposure region to the exposure region. And controlling the exposure amount. 6. The exposure method according to claim 5, wherein the exposure amount is controlled by an exposure time.