JP3248496B2 - Electron beam exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam exposure method in which photolithography and electron beam exposure are mixed in a method of manufacturing a semiconductor device. And a correction method for superimposing.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device is manufactured by mixing optical lithography and electron beam exposure, electron beam exposure provides high resolution, but the throughput is low because patterns are sequentially processed and drawn. There are drawbacks. In addition, optical lithography using a light source such as i-line or KrF is a batch transfer using a mask (reticle), so that the throughput is high, but there is a disadvantage that the resolution is limited by the wavelength of the light source. .

Therefore, in order to achieve both high resolution of electron beam exposure and high productivity of photolithography, a MIX & MATCH technique of electron beam exposure and photolithography has been proposed (Japanese Patent Application No. 56-071235). , T. Ohiwa et
al.Ext.Abstr.17th Conf.Solid State Devices and
Materials (1985) 345, Y. Gotoh et al. Jpn. J. Appl. P
hys.12B (1997) 7541).

FIGS. 8 to 14 illustrate a conventional electron beam exposure method using a mixture of photolithography and electron beam exposure. FIG. 8 shows a flowchart of a conventional electron beam exposure method in which photolithography and electron beam exposure are mixed. First, electron beam exposure apparatus 107 or pattern 10 position measurement mark 102 measurable by the coordinate measuring instrument is placed in a suitable pitch
1 is exposed on the semiconductor wafer 100 using a stepper for measuring distortion. The pattern 101
The upper group of position measurement marks 102 is desirably arranged over the entire maximum transfer area W of the stepper so that distortion over the entire surface of the lens of the stepper can be measured.

Next, as shown in FIG.
The position of each of the position measurement marks 101 exposed above is measured by an electron beam exposure device 107 or a coordinate measuring device or the like, and the position shift amount 104 of each mark from the ideal lattice 103 is measured.
Is measured.

According to the measurement result, the selected displacement amount 10
4, that is, the distortion data is obtained by removing primary components 105 such as shift components, rotation components, and magnification components, which can be corrected by the alignment of the electron beam exposure apparatus as shown in FIG. First, position shift data 106 due to lens distortion is set.

A high-order polynomial approximation of the obtained displacement data 106 is performed using the least squares method as a function of the X and Y coordinates in the chip. This is for obtaining the amount of positional deviation at each coordinate in the chip, and the amount of positional deviation may be obtained by an interpolation method between the fixed points on each side.

[0008] Next, based on the measurement results, the semiconductor wafer 1
The method of exposing at 00 will be described. FIG. 13 is a schematic diagram of an electron beam exposure apparatus. The pattern data is stored in the first storage device 108 of the electron beam exposure apparatus 107. Further, the distortion data obtained by the above-described procedure is also stored in the second storage device 109 of the electron beam exposure apparatus 107. The electron beam exposure apparatus 107 detects alignment marks arranged at the four corners of each chip, and corrects the shift, gain, and rotation (primary component) of each chip based on the position information. Thereafter, the pattern data is divided into rectangles, and the position information of each rectangle is transmitted to the positioning deflector 111 via the positioning deflector control unit 110, and the semiconductor wafer 100 is subjected to electron beam exposure by the electron gun 112. In this case, the distortion data of the light exposure apparatus (hereinafter, referred to as a stepper) corresponding to each position is superimposed on each rectangular position information. Further, depending on the electron beam exposure apparatus 107, the correction is performed not in each rectangular unit but in each deflection area.

As a result, the correction amount corresponding to the position coordinates is added to the original position coordinates of each pattern and each deflection area on the semiconductor wafer 100. Therefore, higher-order lens distortion correction, which could not be performed conventionally, can be performed, and high registration accuracy between optical lithography and electron beam exposure can be ensured.

[0010]

However, the amount and shape of the lens distortion differs for each stepper. When there are a plurality of layers to be superimposed by electron beam exposure and the layers are exposed by a plurality of different steppers, for example, the gate layers and bit lines of the DRAM and the electron When exposing the capacitive contact by line exposure , the two steppers each expose the gate layer, one of the steppers exposes the pincushion type, and the other stepper exposes the bit line, the barrel type disposes the barrel type. have. When performing distortion correction on one of the steppers on which the gate layer is exposed when performing exposure of the capacitor contact, the overlay on the bit line exposed on the other stepper becomes defective as shown in FIG.

As described above, in the conventional method, when distortion correction is performed on a plurality of one stepper, there has been a problem that overlay accuracy on a base exposed by another stepper deteriorates.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and even in the case of overlay exposure using an electron beam on a layer exposed by a plurality of steppers, a high overlay is applied to a plurality of layers. It is an object of the present invention to provide an electron beam exposure method that can ensure alignment accuracy.

[0013]

According to the first aspect of the present invention, there is provided an electronic exposure method, wherein at least two or more layers are exposed to a plurality of light exposures.
Exposed with light device, further in the electron beam exposure method of a semiconductor device for electron beam exposure, the plurality of previously measured distortion of the optical exposure apparatus, the plurality of Disutoshi
Husband the correction data of the electron beam exposure pattern from tio down of data
From these correction data, multiple light exposure patterns
Final correction data for the alignment of the electron beam
A plurality of layers that have been subjected to exposure processing by the plurality of light exposure devices are subjected to overlay exposure using an electron beam based on the final correction data.

In the present invention, the correction data, before
The electron beam exposure was performed for each distortion data.
Allowable value when superimposing the pattern on the light exposure pattern
Is extracted by extracting the components of the distortion in the direction
Therefore, the final correction data is
Averaging young distortion component extracted for each over data
Properly is a weighted average, or the respective distortion de
By performing processing that combines the addition average and the weighted average on the distortion component extracted for each data
You can ask .

[0015] In the present invention, the final correction de
Over data it can also <br/> was superposed on the position information of the electron beam exposure light pattern.

In an electron exposure method according to a second aspect of the present invention, in the electron beam exposure method for a semiconductor device having at least two or more layers, the distortion of a plurality of light exposure apparatuses is measured in advance, and each measurement data of the distortion is converted into the data. Of the layers, the layer subjected to the exposure processing by the light exposure apparatus is divided in a direction in which the measurement data is added, a directional component having a smaller allowable value is extracted, and the layer is subjected to the exposure processing of performing electron beam exposure. The present invention is characterized in that a permissible superimposition value in the direction with respect to the layer being calculated is calculated, and an averaging process of the permissible value is performed.

According to a third aspect of the present invention, in the electron beam exposure method for a semiconductor device having at least two or more layers, the distortion of a plurality of light exposure apparatuses is measured in advance, and each of the measured data of the distortion is obtained. Of the layers, the layer subjected to the exposure processing by the light exposure apparatus is divided in a direction in which the measurement data is weighted, a direction component having a smaller allowable value is extracted, and the layer is subjected to the exposure processing of performing electron beam exposure. The present invention is characterized in that a superimposition allowable value in the direction with respect to the layer being calculated is calculated, and a weighted average process of the allowable value is performed.

In the present invention, the direction is preferably a first direction and a second direction orthogonal to the first direction. More preferably, the directions are the first direction and the first direction.
This is a direction obtained by rotating a coordinate axis composed of a second direction orthogonal to the direction at an arbitrary angle.

In the present invention, high overlay accuracy can be ensured for a plurality of layers even in the case of overlay exposure using an electron beam on a layer exposed by a plurality of steppers.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the accompanying drawings. FIG. 1 is a flowchart of an electron beam exposure method according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a device exposed according to an embodiment of the present invention. FIG. 3A is a diagram illustrating the lens distortion of the stepper A, and FIG. 3B is a vector diagram illustrating the extracted data. 4 (a) is a diagram showing a lens distortion of the stepper B,
(B) is a vector diagram showing the extracted data.
FIG. 5 is a vector diagram showing the correction data of the present embodiment.

In the DRAM 1 shown in FIG. 2, the gate layer 2 as the first layer is exposed by the stepper A by the electron beam exposure method according to the present embodiment, and the second layer is exposed by the stepper B.
The bit line 3 as a layer is exposed. Then, the capacitor contact layer 4 is overlaid by electron beam exposure on the underlying layer on which the gate layer 2 and the bit line 3 have been exposed.

The electron beam exposure method in this embodiment will be described. First, the lens distortion of the steppers A and B for exposing the underlayer is measured in advance.
The measured lens distortion data is stored in a storage device of the electron beam exposure apparatus. As shown in FIG. 3A, each lens distortion data is
A stepper B having a pincushion-type distortion 6 in which an image is formed in a pincushion shape with respect to the ideal lattice 5;
Has a barrel-type distortion 7 in which an image is formed in a barrel shape on the ideal grating 5 as shown in FIG. The horizontal axis of the ideal lattice 5 is defined as the first direction X, and the vertical axis is defined as the second direction Y.

Next, the capacitive contact layer 4 exposed by the electron beam is formed by the gate layer 2 and the bit line 3 in the first direction X and the second direction Y perpendicular to the first direction.
It is determined which of the layers has a smaller allowable value.

The capacitance contact layer 4 exposed by the electron beam has a small allowable value for the gate layer 2 in the first direction X and a small allowable value for the bit line layer 3 in the second direction Y.

Next, as shown in FIG.
The X component in the first direction, which has a smaller overlay tolerance than the distortion data of the first direction, is extracted. Similarly, as shown in FIG. 4B, a second direction Y component having a smaller overlay allowable value (margin) is extracted from the distortion data of the stepper B. Then, the extracted respectively the distortion data processing to a obtain the final correction data 8. In the present embodiment, as shown in FIG. 5, a vector sum of each of the extracted distortion data is taken as distortion data used for correction. The final correction data 8 is obtained by superimposing the position information of the distortion data on the position information corresponding to each of the patterns to be subjected to the electron beam exposure.

Electron beam exposure is performed on the underlying layer using the final correction data 8. As a result, in the first direction X, optimal correction is performed on the gate layer 2 having a small overlay tolerance, and in the second direction Y, optimal correction is performed on the bit line layer 3. The gate layer 2 and the bit line layer 3
Can be performed with high accuracy.

As in the present embodiment, it is possible to obtain the final correction data 8 of the distortion by averaging a plurality of distortion data.

In this embodiment, the distortion data is divided in the first direction X and the second direction Y, but is not particularly limited, and can be divided into arbitrary coordinate axes. For example, it can be divided into polar coordinates and oblique coordinates.

In this embodiment, the description has been made using the example of two steppers. However, the present invention is not limited to this, and three or more steppers are used to measure the respective distortion data. Alternatively, correction data may be extracted from the measurement result to obtain a vector sum. Electron beam exposure can be performed using the obtained vector sum as final correction data.

Another embodiment according to the present invention will be described with reference to the accompanying drawings. The same components as those in the embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 6 is a schematic view of a device exposed by an electron beam exposure method according to another embodiment of the present invention. FIG. 7 is a diagram showing distortion correction data according to another embodiment of the present invention.

In this embodiment, as shown in FIG. 6, the gate layer 2 exposed by the stepper A and the field layer 9 exposed by the stepper B are different from the embodiment shown in FIGS. On the other hand, the exposure of the bit contact 10 by electron beam exposure is different . Otherwise, including lens distortion data of the stepper A and stepper B, to FIG. 1
It is an example and the same shown in FIG.

In this embodiment, the bit contact 10
Of the gate layer 2 and the field layer 9
Is smaller in the first direction X. In the case of the present embodiment, the allowable overlapping value of the bit contact 10 for the gate layer 2 is 40 nm, and the allowable overlapping value of the bit layer 10 for the field layer 9 is 60 nm.

When performing the distortion correction on the steppers A and B, the distortion data of the stepper A and the distortion data of the stepper B are multiplied by an arbitrary constant to obtain a vector sum to obtain distortion data used for correction. An arbitrary constant to be multiplied is set to a large value for the stepper A having a small overlay tolerance and a small value for the stepper B having a large overlay value. As shown in FIG. 7, a vector sum is obtained by multiplying stepper A by 0.6 and stepper B by 0.4 to obtain distortion data. The position information of the distortion data is superimposed on the position information corresponding to each of the patterns to be subjected to the electron beam exposure to obtain final correction data 8.

As in the present embodiment, it is also possible to calculate the distortion correction data 11 by weighted averaging of a plurality of distortion data.

In this embodiment, the correction data 11 is obtained by weighted averaging of a plurality of distortion data. However, the present invention is not limited to this. Only the distortion data of the stepper A in the first direction X is obtained. In the second direction Y, various types of processing can be performed, such as taking a weighted average of the steppers A and B.

[0036] In any of the above embodiments, the case of obtaining the final correction data, although handles with averaging processing and weighted averaging processing alone, but the invention is not limited thereto The final correction data can be obtained by combining the averaging process and the weighted averaging process.

[0037]

As described above in detail, according to the present invention, the distortion is measured and processed for each stepper, so that the layer exposed by the plurality of steppers is superposed by the electron beam. However, high overlay accuracy can be ensured for a plurality of layers.

[Brief description of the drawings]

FIG. 1 is a view showing a flowchart of an electron beam exposure method according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a device exposed by an electron beam exposure method according to an embodiment of the present invention.

3A is a diagram illustrating a lens distortion of a stepper A, and FIG. 3B is a vector diagram illustrating extracted data.

4A is a diagram illustrating a lens distortion of a stepper B, and FIG. 4B is a vector diagram illustrating extracted data.

FIG. 5 is a vector diagram showing correction data of the present embodiment.

FIG. 6 is a schematic view of a device exposed by an electron beam exposure method according to another embodiment of the present invention.

FIG. 7 is a vector diagram showing distortion correction data according to another embodiment of the present invention.

FIG. 8 is a view showing a flowchart of a conventional electron beam exposure method.

FIG. 9A is a schematic diagram illustrating a method for measuring lens distortion, and FIG. 9B is a schematic diagram illustrating a pattern in which position measurement marks are arranged at an appropriate pitch.

FIG. 10 is a diagram illustrating a positional shift amount of a lens from an ideal grating.

FIG. 11 is a diagram showing a primary component.

FIG. 12 is a diagram showing displacement data due to distortion.

FIG. 13 is a schematic view of an electron beam exposure apparatus.

FIG. 14 is a vector diagram showing overlay failure of a capacitor contact with a bit line.

[Explanation of symbols]

 1; DRAM 2; Gate layer 3; Bit line 4; Capacitance contact 5; Ideal lattice 6, 7; Distortion 8, 11; Final correction data 9; Field 10; Bit contact 100; Semiconductor wafer 101; Pattern 102; Measurement mark 103; ideal grating 104; displacement amount 105; primary component 106; displacement data 107; electronic exposure device 108; first storage device 109; second storage device 111; positioning deflector 112; One direction Y; Second direction W; Maximum transfer width of stepper

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/20 H01L 21/027

Claims (9)

(57) [Claims] 1. A method according to claim 1, wherein at least two layers have a plurality of light beams.
Exposure is performed by an exposure apparatus, and further in an electron beam exposure method of a semiconductor device that performs electron beam exposure, the distortion of the plurality of light exposure apparatuses is measured in advance.
Beforehand , from the data of this multiple distortion
Husband the correction data of the line exposure pattern 's request, these correction
From data, multiple light exposure patterns and electron beam exposure patterns
The final correction data of alignment with the pattern is obtained, and for the plurality of layers that have been subjected to the exposure processing by the plurality of light exposure devices,
An electron beam exposure method, comprising performing overlay exposure using an electron beam based on the final correction data. 2. The method according to claim 1, wherein the correction data includes the respective distortions.
Exposure data for the electron beam exposure pattern
The data in the direction in which the tolerance when overlapping the pattern
Extraction of the components of the distortion
Data was extracted for each of the distortion data.
The electron beam exposure method according to claim 1, wherein the distortion component is obtained by averaging the distortion components . 3. The correction data according to claim 1, wherein
Exposure data for the electron beam exposure pattern
The data in the direction in which the tolerance when overlapping the pattern
Extraction of the components of the distortion
Data was extracted for each of the distortion data.
The electron beam exposure method according to claim 1, wherein the distortion component is obtained by weighted averaging. 4. The correction data according to claim 1, wherein each of the distortions is
Exposure data for the electron beam exposure pattern
The data in the direction in which the tolerance when overlapping the pattern
Extraction of the components of the distortion
Data was extracted for each of the distortion data.
2. The electron beam exposure method according to claim 1, wherein the distortion component is obtained by performing a process in which an addition average and a weighted average are combined. Wherein said final correction data is any one of claims 1 to 4, characterized in that superimposed on the position information of the electron beam exposure light path data <br/> over emissions 3. The electron beam exposure method according to item 1. 6. An electron beam exposure method for a semiconductor device having at least two or more layers, wherein a distortion of a plurality of light exposure devices is measured in advance, and each of the measured data of the distortion is measured by the light exposure device among the layers. For the layer that has been subjected to the exposure processing, the measurement data is divided in the direction in which the measurement data is added, a direction component having a smaller allowable value is extracted, and the electron beam exposure is performed. An electron beam exposure method, comprising calculating an allowable value and performing an averaging process of the allowable value. 7. An electron beam exposure method for a semiconductor device having at least two or more layers, wherein a distortion of a plurality of light exposure devices is measured in advance, and each measurement data of the distortion is measured by the light exposure device among the layers. For the layer that has undergone the exposure processing, the measurement data is divided in a direction in which the measurement data is weighted, a direction component having a small allowable value is extracted, and the direction is superimposed on the layer that has undergone the exposure processing, which performs electron beam exposure An electron beam exposure method, comprising calculating an allowable value and performing a weighted average processing of the allowable value. 8. The apparatus according to claim 6, wherein the direction is a first direction and a second direction orthogonal to the first direction.
Or the electron beam exposure method according to 7. 9. The apparatus according to claim 6, wherein the direction is a direction obtained by rotating a coordinate axis including a first direction and a second direction orthogonal to the first direction by an arbitrary angle.
3. The electron beam exposure method according to item 1.