JPH088161A - Transfer simulator device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a transfer simulator device capable of easily performing mask pattern correction, mask pattern defect inspection, and the like. The transfer simulator apparatus includes an illumination light source having a wavelength λ2, a condenser lens 2, a projection lens 6, a projection lens diaphragm 7, a light receiving element 13, and a data processing device 14.
And a liquid crystal mask 12 and a liquid crystal control device 15.
The wavelength λ2 of the illumination light source 1 is larger than the wavelength λ1 of the light emitted from the illumination light source in the actual exposure apparatus. The light receiving element 13 is connected to the data processing device 14, and the liquid crystal mask 12 is connected to the liquid crystal control device 15. The data processing device 14 and the liquid crystal control device 15 are connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer simulator device for verifying pattern exposure performed in a semiconductor integrated circuit manufacturing process.

[0002]

2. Description of the Related Art In recent years, the demand for high integration of devices has been increasing. Along with this, miniaturization of patterns in semiconductor integrated circuits has been required. In the manufacturing process of a semiconductor integrated circuit, there is an exposure process as one process for forming a pattern in the semiconductor integrated circuit.
FIG. 5 is a schematic diagram showing a schematic configuration of a conventional reduction projection exposure apparatus used in such an exposure process.

Referring to FIG. 5, the reduction projection exposure apparatus includes an illumination light source 11 which emits light of wavelength λ1, and this illumination light source 11
The condenser lens 2 arranged below, the mask holder 5 arranged below the condenser lens 2, and the mask holder 5
The projection lens 6 and the projection lens diaphragm 7 arranged below
And a wafer stage 10. A photomask 3 having a predetermined mask pattern 4 formed thereon is placed on the mask holder 5. An exposure substrate 8 on which a predetermined resist pattern 9 is formed is placed on the wafer stage 10.

In the exposure apparatus having the above structure, the light emitted from the illumination light source 11 is emitted from the condenser lens 2,
Photomask 3, projection lens 6 and projection lens diaphragm 7
And is irradiated onto the exposed substrate 8. At this time, a photosensitive material such as a resist is applied to the surface of the exposed substrate 8. The light is irradiated onto the photosensitive material. Then, the resist pattern 9 is formed on the surface of the exposure substrate 8 through the developing process. Using this resist pattern 9, various patterns are formed in the semiconductor integrated circuit.

As described above, with the miniaturization of patterns,
The resist pattern 9 is also required to have a fine pattern shape. As a method for forming such a fine resist pattern 9, there is a method of using light of a short wavelength such as i-line. The wavelength λ of this i-line is
It is about 365 nm. By using light such as i-line having a short wavelength, it is possible to form a fine pattern. To form even finer patterns in the future,
It is conceivable to use light having a shorter wavelength than the i-line.

When performing exposure using light of a short wavelength as described above, it is difficult to convert the light intensity of the actually exposed pattern into an electric signal by a light receiving element or the like. Therefore, as a method of examining defects on the mask,
A method that uses image processing with broadband light and a method that detects scattered light by applying a laser light to a mask have been used.

[0007]

However, it is difficult to detect a semitransparent defect or a very small defect with the above method. Therefore, it has been attempted to discover the defects of the mask by actually transferring the pattern to the resist.

However, the method of actually transferring the mask pattern to the resist and finding the defect of the mask is complicated,
It has been difficult to find defects due to finer patterns, more complicated patterns, and wider exposure areas. Also, due to the miniaturization of exposure patterns, complication, and widening of the exposure area, it will be difficult to find areas where normal exposure is not possible unless the locations where exposure is difficult are considered in advance. It has become to.

Further, with the miniaturization of patterns, it becomes difficult to set different patterns on the same mask to the target size with the same exposure amount when transferring the mask pattern to the resist. Therefore, it has become necessary to adjust the pattern size on the mask in advance. Further, it is necessary to use an expensive lens as the lens used in the exposure apparatus that uses light of a short wavelength as described above.

The present invention has been made to solve the above problems. An object of the present invention is to provide an inexpensive transfer simulator device in which a mask defect can be easily found and an exposure pattern can be easily verified.

[0011]

In one aspect, a transfer simulator apparatus according to the present invention uses a light beam having a first wavelength λ1 for pattern exposure performed by an exposure apparatus having an optical system having a first numerical aperture NA1. It is assumed that it is a transfer simulator device for verification. In one aspect, the transfer simulator device includes a light source, a mask, first and second optical systems, a light receiving element, and a data processing device. The light source emits light having a second wavelength λ2, which is a longer wavelength than the first wavelength λ1. The mask is arranged under the light source. The first and second optical systems are arranged under the light source so as to sandwich the mask from above and below, and (λ2 / λ1) × N
It has a second numerical aperture NA2 represented by A1. The second optical system is located under the mask. The light receiving element is the second
It is placed under the optical system of. The data processing device is connected to the light receiving element and processes data detected by the light receiving element. In the present specification, the “light receiving element” means C
A device such as a CD (Charge Coupled Device) or an image pickup tube that can detect irradiated light and convert it into an electric signal will be referred to.

A transfer simulator device according to the present invention is
In another aspect, the first and second light sources, the mask, the first and second optical systems, the third and fourth optical systems, the first and second light receiving elements, and the data processing device. With. The first and second light sources emit light having a second wavelength λ2, which is a longer wavelength than the first wavelength λ1. The mask is arranged under the first and second light sources, and the first and second patterns having the same shape are formed on the mask. The first and second optical systems are arranged under the first light source so as to sandwich the first pattern from above and below, and have a second numerical aperture NA2 represented by (λ2 / λ1) × NA1. The second optical system is arranged under the mask. The third and fourth optics are arranged under the second light source to
Are arranged so as to sandwich the pattern from above and below, and (λ2 / λ
1) has a second numerical aperture NA2 represented by NA1. The fourth optical system is arranged under the mask. The first light receiving element is arranged under the second optical system. The second light receiving element is arranged under the fourth optical system. The data processing device is the first
Is connected to the second light receiving element, and the data detected by the first and second light receiving elements are compared.

[0013]

According to the transfer simulator apparatus according to the present invention, in one aspect, light having a wavelength longer than the wavelength of light actually used for exposure is used. This makes it possible to use such long-wavelength light by adjusting the numerical aperture of the optical system in the transfer simulator device. As described above, by using the light having the long wavelength, it is possible to detect the intensity of the light exposed by the light receiving element such as the CCD and the image pickup tube. The data detected in this way is
It is sent to the data processing device. Then, in the data processing device, the pattern data to be actually exposed is compared with the data detected by the light receiving element. Thereby, it becomes possible to easily find or correct a mask defect or an exposure pattern defect.

According to the transfer simulator apparatus according to the present invention, in another aspect, the first and second identical shapes are formed on the mask.
Pattern is formed. The exposure patterns according to the first and second patterns are detected by the first and second light receiving elements, respectively. Both the first and second light receiving elements are connected to the same data processing device. Thereby, it becomes possible to compare the data detected by the first and second light receiving elements. This makes it possible to detect mask defects and
It is also possible to determine the tolerance of defect size.

[0015]

1 is a block diagram of an embodiment according to the present invention.
~ It demonstrates using FIG.

(First Embodiment) First, a first embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a schematic configuration of a transfer simulator device according to a first embodiment of the present invention.

Referring to FIG. 1, the transfer simulator device includes an illumination light source 1 which emits light of wavelength λ2, a condenser lens 2, a projection lens 6, a projection lens diaphragm 7, a light receiving element 13, and a data processing device. 14 and the liquid crystal mask 12
And a liquid crystal control device 15.

The wavelength λ2 of the light emitted from the illumination light source 1
Is longer than the wavelength λ1 of light actually used for exposure. Specifically, the wavelength λ2 is 400 nm to 50
It is about 0 nm or more. A mercury lamp or the like can be used as the illumination light source 1. By using such relatively long wavelength light, the exposed light is
It can be detected by the light receiving element 13 such as a CD.

The numerical aperture NA2 of the condenser lens 2 and the projection lens 6 is expressed by the following equation. NA2 = (λ2 / λ1) × NA1 In this way, by defining the numerical aperture NA2 of the condenser lens 2 and the projection lens 6, these are determined by the condenser lens 2 and the projection lens 6 of the exposure apparatus in which exposure is actually performed. Which is mathematically equivalent. As a result, a transfer simulator device capable of reproducing a phenomenon extremely close to an actual exposure phenomenon by using light having a wavelength longer than the wavelength of light used for actual exposure can be obtained.

The liquid crystal mask 12 is a mask made of liquid crystal. The liquid crystal mask 12 has the liquid crystal mask 1
A liquid crystal control device 15 for controlling the pattern shape formed on the second layer is connected. By including the liquid crystal control device 15, it becomes possible to easily change the pattern shape formed on the liquid crystal mask 12 to various shapes. The liquid crystal control device 15 is connected to the data processing device 14. The data processing device 14 is connected to the light receiving element 13.

When actually performing a simulator using the transfer simulator device having the above-described structure, first, the liquid crystal mask 12 having a pattern of a predetermined shape is set at a predetermined position. Then, the illumination light source 1 irradiates light having a wavelength λ2, which is longer than the actual exposure wavelength λ1. This light passes through the condenser lens 2 and is applied to the liquid crystal mask 12. Then, the light according to the pattern of the liquid crystal mask 12 is transmitted to the light receiving element 13 through the projection lens 6 and the projection lens diaphragm 7. Then, the light intensity of the image formed by the light receiving element 13 is detected.
In this way, the data detected by the light receiving element 13 is sent to the data processing device 14. At this time, the pattern data to be actually exposed is stored in the data processing device 14 in advance. This pattern data is compared with the data detected by the light receiving element 13. When the pattern data and the detection data are deviated, the correction value is calculated and the data is fed back to the liquid crystal control device 15. Then, according to this data, the shape of the mask pattern 4 of the liquid crystal mask 12 is appropriately corrected by the liquid crystal control device 15. At this time, the liquid crystal 1
In 2, the mask pattern having the size represented by the following formula is formed.

(Size of pattern data to be actually exposed) × (λ2 / λ1) × (projection magnification of the present optical system) As described above, the pattern of the exposed light is detected using the light receiving element 13, The operation of feeding it back is repeated. As a result, the mask pattern shape can be corrected so that the pattern data to be actually exposed can be obtained. As a result, it is possible to easily form a photomask having a mask pattern that does not cause deviation of the resist dimension due to optical factors when actually exposed.

(Second Embodiment) Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing a transfer simulator device according to a second embodiment of the present invention.

Referring to FIG. 2, the mask holder 5 is provided in the transfer simulator apparatus of this embodiment. Then, on the mask holder 5, the photomask 3 whose mask pattern is corrected by using the transfer simulator device according to the first embodiment is placed. Further, in this embodiment, the liquid crystal mask 12 and the liquid crystal control device 15 are not provided. The other structure is the same as that of the transfer simulator device in the first embodiment shown in FIG.

By placing the photomask 3 on the mask holder 5 and performing the exposure simulation as described above, it is possible to verify whether or not the mask pattern 4 of the photomask 3 is manufactured as intended. .
That is, it becomes possible to perform verification after correction of the mask pattern.

(Third Embodiment) Next, a third embodiment according to the present invention will be described.
The transfer simulator device in this embodiment will be described. FIG. 3 is a schematic diagram showing a schematic configuration of a transfer simulator device according to a third embodiment of the present invention.

Referring to FIG. 3, the transfer simulator apparatus in the present embodiment is a light source 1a, 1 which emits light of wavelength λ2.
b, the condenser lenses 2a and 2b, and the photomask 3
, The projection lenses 6a and 6b, and the projection lens diaphragms 7a and 7
b and light receiving elements 13a and 13b. Then, on the mask holder 5, the mask patterns 4a having the same shape,
The photomask 3 having 4b is placed.

According to the above transfer simulator, two types of data with the same mask pattern are detected by the light receiving elements 13a and 13b, respectively. And
By comparing the two types of data by the data processing device 14, it becomes possible to perform a comparative inspection for defects in the mask pattern. Further, at this time, since the optical system used in the transfer simulator device is equivalent to the optical system of the exposure device that actually performs the exposure, it is possible to make a determination including the tolerance of the defect size. .

(Fourth Embodiment) Next, a transfer simulator apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing a schematic configuration of a transfer simulator device according to a fourth embodiment of the present invention.

With reference to FIG. 4, the transfer simulator apparatus of this embodiment is provided with an elevating device 16 for moving the light receiving element 13 in the vertical direction. The lifting device 16 is connected to the data processing device 14. The other structure is similar to that of the transfer simulator apparatus according to the second embodiment shown in FIG.

As described above, by providing the elevating device 16, the light receiving element 13 can be moved in the vertical direction. Thereby, it becomes possible to estimate the depth of focus of the pattern. Specifically, by moving the light-receiving element 13 in the height direction by an amount represented by (the height moved on the actual substrate) × (λ1 / λ2), the height direction on the actual substrate is increased. It is possible to estimate in advance the allowable value of.

[0032]

As described above, according to the present invention, since exposure is performed using light having a wavelength longer than the wavelength actually used for exposure, it is possible to detect the exposure pattern by the light receiving element. Becomes At this time, since the optical system used in the transfer simulator apparatus is equivalent to the optical system used in the actual exposure apparatus, a result similar to that of the actual exposure apparatus can be obtained. From the above, it is possible to perform operations such as mask pattern correction, mask pattern defect inspection, and pattern depth of focus estimation without actually transferring to a resist as in the conventional example. As a result, the above-mentioned work can be performed more easily than in the conventional example. Further, since light having a relatively long wavelength is used, the optical system used in the transfer simulator device can be made cheaper than the conventional example.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a transfer simulator device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a transfer simulator device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a transfer simulator device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram showing a transfer simulator device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram showing a schematic configuration of a conventional reduction projection exposure apparatus.

[Explanation of symbols]

1, 11 Illumination light source, 2 Condenser lens, 3 Photomask, 4 Mask pattern, 5 Mask holder, 6
Projection lens, 7 Projection lens diaphragm, 8 Exposure substrate, 9
Resist pattern, 10 wafer stage, 12 liquid crystal mask, 13 light receiving element, 14 data processing device, 15
Liquid crystal control device, 16 lifting device.

Claims (4)

[Claims] 1. A transfer simulator apparatus for verifying pattern exposure performed by an exposure apparatus having an optical system having a first numerical aperture NA1 using light having a first wavelength λ1. A light source that emits light having a second wavelength λ2 that is longer than λ1, a mask that is arranged under the light source, and a mask that is arranged under the light source so as to sandwich the mask from above and below, and (λ2 / λ1) × NA1 The first and second optical systems having the second numerical aperture NA2 represented by, a light receiving element arranged under the second optical system, and a light receiving element connected to the light receiving element and detected by the light receiving element. A data processing device for processing data, and a transfer simulator device. 2. The liquid crystal mask, wherein the mask is a liquid crystal mask made of liquid crystal, and a liquid crystal control device for controlling the pattern shape of the liquid crystal mask based on the data processed by the data processing device. The transfer simulator device according to claim 1, which is connected. 3. The transfer simulator device further comprises:
The transfer simulator device according to claim 1, further comprising moving means for moving the light receiving element up and down. 4. A transfer simulator apparatus for verifying pattern exposure performed by an exposure apparatus having an optical system having a first numerical aperture NA1 using light having a first wavelength λ1. Second wavelength λ2, which is a longer wavelength than λ1
A first and a second light source which emits light, a mask which is arranged under the first and the second light source, and on which the first and second patterns having the same shape are formed, and under the first light source First and second optical systems which are arranged so as to sandwich the first pattern from above and below and which have a second numerical aperture NA2 represented by (λ2 / λ1) × NA1; and under the second light source, Third and fourth optical systems arranged so as to sandwich the second pattern from above and below and having a second numerical aperture NA2 represented by (λ2 / λ1) × NA1, and the second and fourth optical systems. First and second light receiving elements respectively arranged below, and the first and second light receiving elements connected to the first and second light receiving elements.
And a data processing device for comparing the data detected by the light receiving element of.