JPH08236427A - Exposure method and scanning type exposure apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] An exposure method that solves the problem of dimensional difference and the like with a simple structure, even for exposed materials that may cause unevenness in exposure due to steps and the like and dimensional difference A scanning exposure apparatus is provided. [Structure] When performing exposure by irradiating an exposed portion such as a wafer with the exposure light 2, the exposure light illuminance is obtained by irradiating the exposed portion through the liquid crystal 31 ... And controlling the liquid crystal. Take control. In a scanning type exposure apparatus that performs exposure by scanning the exposure light irradiation part relative to the exposed part, a liquid crystal partitioned between the exposure light irradiation part and the exposed part is arranged in the slit 5 or the like, The partitioned liquid crystal is configured to be controllable for each partition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and a scanning type exposure apparatus. INDUSTRIAL APPLICABILITY The present invention can be applied to various exposure techniques, and can be preferably used when exposing a photoresist in a photolithography process in manufacturing a semiconductor device, for example.

[0002]

[Prior art and its problems] In the field of application of processing technology using exposure, the miniaturization of processing is progressing more and more. Typically, the miniaturization and integration of electronic materials, especially semiconductor devices, is remarkable. For example, miniaturization of semiconductor devices is now in the sub-half micron region, and along with this, the required semiconductor chip size is increasing. Therefore, it is required to expand the possible exposure field of the exposure apparatus.

By the way, conventionally, the reduction projection exposure apparatus has been
The larger the lens diameter, the more difficult it becomes to manufacture it.
The lens scan method and the mirror scan method, which require a relatively small lens, have been attracting attention as one method for expanding the exposure field.

On the other hand, the entire exposed surface of the exposed material is not always flat and may have steps. For example, in the semiconductor device, as shown in FIG. 9, a step c is relatively large in a portion near the boundary between the peripheral circuit portion a and the memory cell array portion b.
Since resist coating in the photolithography process is generally a spin coating method, in these peripheral circuit parts,
Conformal film formation is difficult. Therefore, a film thickness difference occurs in the resist d between the central portion and the peripheral portion. In FIG. 9, the different film thicknesses are indicated by T1 to T3. As shown in the figure, the resist film thickness T1 of the portion near the step c of the peripheral circuit part a is larger than the resist film thicknesses T2 and T3 of the memory cell part b, and the resist film thicknesses T2 and T3 of the memory cell part b are also. , There is a difference depending on the distance from the step c. Reference numeral e designates the peripheral circuit section a
And the memory cell part b and the boundary (reference point) are shown. The difference in the film thickness of the resist d produces a result that a dimensional difference occurs especially near the boundary of the cell portion due to the in-film multiple interference effect (standing wave effect) of the resist and the bulk effect.

To avoid this, near the boundary between the memory cell array portion b of the reticle and the peripheral circuit (near the reference point e).
There is a method of changing the dimensions of the mask pattern in advance according to the dimension difference that should occur. However, in this method, since the amount of dimensional difference generated changes when the resist type changes, it is necessary to make dimensional changes corresponding to each. Therefore, this method is complicated and not easy to put into practical use.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and can be applied to a material to be exposed which may cause unevenness of exposure due to a step or the like to cause a dimensional difference with a simple structure. An object of the present invention is to provide an exposure method and a scanning type exposure apparatus that solve the problems such as the occurrence of dimensional difference.

[0007]

An exposure method of the present invention is an exposure method in which exposure light is applied to an exposed portion to perform exposure, and the exposure light is applied to the exposed portion via a liquid crystal, The illuminance of the exposure light is controlled by controlling the liquid crystal, and the above object is achieved by this.

The scanning type exposure apparatus of the present invention is a scanning type exposure apparatus that performs exposure by scanning the exposure light irradiation part relative to the exposed part, and between the exposure light irradiation part and the exposed part. It is characterized in that partitioned liquid crystals are arranged, and the partitioned liquid crystals can be controlled for each partition.
This achieves the above object.

In this case, it can be preferably embodied as a scanning type exposure apparatus in which the exposure light in a pattern form is scanned by scanning the exposed portion through a slit and the slit is made of liquid crystal.

Another exposure method of the present invention is an exposure method in which exposure light is scanned relative to an exposed portion to perform exposure, and the scanning speed is controlled according to the exposed position of the exposed portion. By doing so, the illuminance of the exposure light is controlled to achieve the above object.

In a further scanning type exposure apparatus of the present invention, one or both of a reticle on which an exposure pattern is formed and an exposed portion are moved to relatively scan the exposed portion with respect to exposure light. In the scanning exposure apparatus for performing the exposure, the moving speed of the reticle and / or the exposed portion is controlled to achieve the above object.

More specifically, the present invention can be preferably configured in a scanning type exposure method and an exposure apparatus in which the slit portion for scanning the reticle is composed of a liquid crystal block. .

Further, it is preferably embodied in a mode in which the dimensional variation of the resist image actually printed is reduced by electrically controlling the liquid crystal block to change the gradation and changing the illuminance depending on the irradiation position of the reticle. can do.

In the scanning type exposure apparatus, the speed of scanning the reticle and the speed of scanning the exposed material (exposed wafer, etc.) are as follows.
Both speeds are generally synchronized with each other, but it can be implemented as an exposure method for improving resolution by intentionally changing each speed to cause a change in illuminance.

[0015]

According to the present invention, it is possible to eliminate the occurrence of a dimensional difference due to a step or the like in the exposure technique. That is,
The exposure light at each exposed position can be controlled by irradiating the exposed portion to the exposed portion through the liquid crystal and controlling the exposure light illuminance by controlling the liquid crystal. Exposure is possible and the final dimensional difference can be eliminated.

In this case, a partitioning liquid crystal is arranged between the exposure light irradiating section and the exposed section, and the partitioning liquid crystal can be assembled as a scanning type exposure apparatus in a configuration that can be controlled for each partition. . This scanning type exposure apparatus can be configured such that the exposure light is scanned by scanning the exposure light in a pattern through the slit through the slit, and the slit is made of liquid crystal.

Further, in another invention, since the illuminance of the exposure light is controlled by controlling the scanning speed in accordance with the exposed position of the exposed portion, the exposure at each exposed position is also achieved by this. It is possible to control and perform appropriate exposure according to each exposure position, and it is possible to eliminate the final dimensional difference.

In this case, by moving one or both of the reticle on which the exposure pattern is formed and the exposed portion, the reticle is used when the exposed portion is relatively scanned with respect to the exposure light for exposure. And / or it can be embodied as a scanning type exposure apparatus configured to control the moving speed of the exposed portion.

For example, in the case of a memory semiconductor device, two or more semiconductor devices are usually manufactured, and accordingly, the dimensional difference between the scan direction and the vertical direction is controlled by controlling the gradation of the liquid crystal block. Can be provided to reduce the dimensional difference. The dimensional difference in the scanning direction can be reduced by changing the synchronous speed of the reticle stage and the wafer, which are moving in synchronization, to prevent the dimensional difference from occurring. Such an embodiment will be described in detail in Example 1 described later.

[0020]

EXAMPLES Examples of the present invention will be specifically described below. However, needless to say, the present invention is not limited by the following examples.

Embodiment 1 This embodiment embodies the present invention when exposing a resist in a photolithography process in the case of manufacturing a semiconductor device such as a miniaturized memory device.
The configuration of this embodiment is shown in FIG. 1 and will be described below.

In this embodiment, as shown in FIG.
When the exposure light 2 is applied to the surface of the substrate wafer that is the material to be exposed 1 to perform exposure, the exposure light 2 is applied to the liquid crystals 31, 32, ... 3n.
The exposed portion of the exposed material 1 is irradiated via the. At this time,
The exposure light illuminance is controlled by controlling the liquid crystals 31 ... Reference numeral 4 denotes a reticle (mask) on which a pattern is formed, and a pattern that has been magnified about 5 times is reduced and projected on the exposed material 1 as schematically shown in FIG. A 1x mask is also acceptable).

Here, the exposure apparatus of the present embodiment is a scanning type apparatus which performs exposure by scanning the exposure light irradiation part relative to the exposed part, and between the exposure light irradiation part and the exposed part. .. are arranged, and the partitioned liquid crystals 31, ... Are configured to be controllable by electrical control or the like for each partition.

In this embodiment, the exposure light is scanned by scanning the exposed portion through the slit 5 through the slit 5, and the slit is made of liquid crystal. In the present embodiment, the exposure light irradiation portion and the exposed portion of the exposed material 1 may be moved relative to each other to perform the scanning exposure, but in general, the slit 5 is fixed and the reticle 4 and / or the exposed portion 1 is exposed. Exposure material 1
Since the (wafer) is moved, the position of the slit 5 is fixed in this embodiment as well, and the reticle 4 and the material 1 to be exposed are both moved (in the case of 5 × reduction projection, the reticle 4 is basically covered). It means that it moves at 1/5 the speed of exposed material 1.)

A more specific description will be given below. 4 here
An example of a reticle for exposing individual memory chips will be described.

Here, a case where the size of the peripheral portion of the cell (the portion indicated by symbol a in FIG. 9) is thick will be described as an example. The resist is assumed to be positive. When the four reticles are schematically shown, it is assumed that the same chips 41 to 44 are arranged in a square pattern on the reticle 4, as shown in FIG. According to the assumption of the present embodiment, if scanning exposure is performed using the conventional technique, the size of the central portion B of the memory cell array portion is small as shown in FIG. 3, although it depends on the set resist film thickness. The peripheral portion A corresponding to the peripheral circuit is thickly finished.

In this embodiment, as shown in FIG. 4, liquid crystals 31, 32, ...
These liquid crystals are divided into blocks and arranged vertically in the longitudinal direction of the slit 5. Each liquid crystal can be controlled independently. It should be noted that the illustration of the slit 5 is conceptual, and actually, the slit 5 is narrower and elongated. Here, the liquid crystal in the center is made white. The bright areas have thin dimensions. That is, in this embodiment, as shown in FIG. 5, the liquid crystal of the slit 5 is white in the central portions 3B ₁ and 3B ₂ and the other portions 3A ₁ , 3A ₂ and 3A ₃ are transparent. Was made larger. The peripheral circuits are exposed at the portions corresponding to 3A ₁ , 3A ₂ and 3A ₃ .

Therefore, as a result of controlling the liquid crystal as described above, as shown in FIG. 6, the portions corresponding to the peripheral circuit portion are brightened by the exposure light with high illuminance as indicated by reference numerals 30A _1, 30A _2, 30A _3. Exposed. Since the positive resist is used here for the bright part, the dimensions are finished fine. Therefore, the pattern width of the peripheral circuit portion, which tends to be thicker in the conventional technique, is offset here, and the line width is finished with an appropriate uniform line width. The central portion of the memory cell portion is designated by reference numeral
0B _1, since it is relatively dark exposure white liquid crystal as indicated by 30B _2, it became possible to control the uniformity of the line width due to such exposure control. On the contrary, when the peripheral circuit section is thin and the memory cell array section is thick, the operation may be reversed.

Here, in the vertical direction of FIG. 5 and FIG. 6 (direction perpendicular to the scanning direction S), line width uniformity can be achieved by the control by the block-shaped liquid crystal, but in the horizontal direction (scanning direction S). Can not be controlled by the liquid crystal. Therefore, in this embodiment, in the scanning direction S, as shown in FIG. 7, the exposure of the portion corresponding to the peripheral circuit portion is performed at a slow speed as indicated by reference symbols R ₁ , R ₂ , R ₃ and R _4. The exposure of the portion corresponding to the memory cell array portion is performed at a high speed, as indicated by the symbols Q ₁ and Q ₂ .

As a result of this, since the effective exposure amount increases in the slow speed portion, the line width can be reduced. Therefore, since the peripheral circuit portion exposed at the slow speeds R ₁ , R ₂ , R ₃ , and R ₄ is originally a portion that tends to be finished in a thick size, it is possible to achieve a balance by this.
Exposure that provides a uniform line width can be realized. Also in this case, when the tendency of the dimensional difference to occur is opposite, the speed may also be oppositely controlled.

By doing so, the dimensional difference between the periphery and the center of the memory cell array portion can be eliminated in both the X and Y directions. As a result, highly accurate device fabrication is possible.

In the present embodiment, as described above, it is possible to manufacture a memory device with higher accuracy and less variation in operating speed.

Embodiment 2 This embodiment is applied to the case where finer control is required. Here, the liquid crystal slit has a grid pattern as shown in FIG. The eye-shaped liquid crystal of the base is indicated by reference numerals 311 and 3
12, ...; 321, ... By using this liquid crystal slit, it is possible to make various parts brighter or darker and perform precise control.

In this embodiment, since the checkerboard pattern is formed as described above, it is not necessary to change the speed of the lower stage and the reticle stage as shown in FIG. It is possible to control both in the X and Y directions. In this case, a similar operation can be realized by providing a liquid crystal part having the same size as the reticle, arranging a slit on the liquid crystal part (the slit has no liquid crystal), and scanning the slit at a constant speed.

Embodiment 3 In this embodiment, the uniformity of exposure is eliminated only by controlling the scan speed without using liquid crystal.

In the present embodiment, as described above with reference to FIG. 7, when exposure is performed by scanning the exposure light relative to the exposed portion, the exposure position is changed according to the exposed position of the exposed portion. The illuminance of the exposure light is controlled by controlling the scanning speed.

In this case, by moving one or both of the reticle on which the exposure pattern is formed and the exposed portion, the exposure is performed by scanning the exposed portion relative to the exposure light. The apparatus can be configured to control the moving speed of the reticle and / or the exposed portion.

Specifically, in this embodiment, this control is performed by changing the lower stage (speed of the wafer as the material to be exposed) and the reticle speed.

In this embodiment, in the exposure method in which the exposure light is relatively scanned with respect to the exposed portion to perform the exposure, the scanning speed is controlled according to the exposed position of the exposed portion. By adopting a configuration that controls the illuminance of exposure light by
This achieved the uniformity of exposure that was the object of the present invention. This method can be applied not only to one direction of the X direction and the Y direction but also to both directions.

In each of the above-described embodiments, a specific memory of four memory cells has been described, but it goes without saying that the principle does not change when two memory cells or six memory cells are used.

[0041]

As described above, the exposure method and the scanning type exposure apparatus of the present invention can be easily applied to the exposed material which may cause unevenness in exposure due to steps or the like, resulting in dimensional difference. Proper exposure is possible with the configuration, and problems such as the occurrence of dimensional differences can be solved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

FIG. 2 is a schematic diagram of a reticle used in Example 1.

FIG. 3 is a schematic diagram illustrating dimensional nonuniformity.

FIG. 4 is a configuration diagram showing a slit according to the first embodiment.

FIG. 5 is an explanatory diagram showing control of the liquid crystal according to the first embodiment.

FIG. 6 is an explanatory diagram showing exposure control according to the first embodiment.

FIG. 7 is an explanatory diagram showing exposure control based on a scanning speed in the first embodiment.

FIG. 8 is a configuration diagram showing a slit according to a second embodiment.

FIG. 9 is a diagram showing a problem of the conventional technique.

[Explanation of symbols]

1 Exposed Material (Semiconductor Wafer) 2 Exposure Light 31, 32, ... 3n; 311, 312, 321
Liquid crystal 4 Reticle 5 Slit

Claims (6)

[Claims] 1. An exposure method in which exposure light is applied to an exposed portion to perform exposure, and the exposure light illuminance is controlled by irradiating the exposed portion to the exposed portion through a liquid crystal and controlling the liquid crystal. An exposure method characterized by being configured. 2. A scanning type exposure apparatus for performing exposure by scanning an exposure light irradiation part relative to an exposed part, wherein a liquid crystal is arranged between the exposure light irradiation part and the exposed part. The scanning type exposure apparatus is characterized in that the partitioned liquid crystal can be controlled for each partition. 3. A scanning type exposure apparatus according to claim 2, wherein the exposed portion is exposed to light by scanning the exposed portion through a slit, and the slit is made of liquid crystal. 4. An exposure method for performing exposure by scanning exposure light relative to an exposed portion, wherein the illuminance of the exposure light is controlled by controlling the scanning speed according to the exposed position of the exposed portion. An exposure method characterized in that it is configured to control. 5. A reticle on which an exposure pattern is formed and one or both of the exposed portions are moved,
A scanning type exposure apparatus which performs exposure by relatively scanning an exposed portion with respect to exposure light, wherein the moving speed of the reticle and / or the exposed portion is controlled. 6. A scanning type exposure apparatus for performing exposure by scanning an exposure light irradiation part relative to an exposed part, wherein a liquid crystal is arranged between the exposure light irradiation part and the exposed part. The partitioned liquid crystal is configured to be controllable for each partition, and the illuminance of the exposure light is controlled by controlling the scanning speed according to the exposed position of the exposed portion. Scanning exposure device.