JPH10209010A - Method and apparatus for charge beam exposure, and pallet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the throughput. SOLUTION: An unexposed sensitive substrate 10 is fixed to a pallet 9. A first alignment between the substrate 10 and the pallet 9 is measured during a pattern exposure of another substrate. The aligned substrate 10 and the pallet 9 are laid on an x-y stage 7 to measure a second alignment of the pallet 9 to the x-y stage. Based on the first and the second alignment measurement, the substrate 10 is aligned with the x-y stage 7 while the stage 7 and the optical source are controlled for the exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged beam exposure technique for improving throughput.

[0002]

2. Description of the Related Art In lithography for manufacturing semiconductor integrated circuits, pattern exposure is performed a plurality of times on the same area, that is, so-called pattern exposure. that time,
The position of an alignment mark used for accurate alignment of the wafer is measured. As an example, in an exposure apparatus using a charged beam, a plurality of alignment marks formed on a wafer by etching are scanned with the charged beam, scattering particles from the wafer are detected, the position of the alignment mark is measured, and exposure is performed. The position coordinates of the power chip pattern are determined. The wafer is placed on the stage via a pallet, and the position of the alignment mark on the wafer is detected as the xy position of the stage.

In some charged beam exposure apparatuses, the position of an alignment mark is detected by off-axis using light such as laser light. In this alignment mark position detection method, the wafer is once moved by a predetermined distance from the optical axis of the projection lens by moving the stage, and the alignment mark is scanned at that position by a laser beam to detect reflected light, thereby detecting each alignment mark. Measure the position of the mark. After measuring all the alignment mark positions in this manner, the wafer is moved on the optical axis and exposure is performed by using the charged beam.

[0004]

However, in any of the alignment mark position detection methods, since the exposure step and the alignment mark position measurement step are performed sequentially, there is a disadvantage that the overall throughput is reduced by the measurement time. . In particular, as the number of alignment marks on a wafer increases, the time from the start of alignment to the start of exposure increases, and there is a high demand for improving throughput.

An object of the present invention is to provide a charged beam exposure method and an exposure apparatus capable of improving the throughput. Another object is to provide a pallet used in such an exposure method and an exposure apparatus.

[0006]

An embodiment of the present invention will be described with reference to FIGS. (1) Explaining with reference to FIG. 4, the invention according to claim 1 is a method in which a plurality of sensitive substrates 101 and 102
a, 9b, which is applied to a charged beam exposure method for exposing a pattern by sequentially placing the sensitive substrates 101, 102 fixed on the pallets 9a, 9b on an exposure stage 7 of a charged beam exposure apparatus. After performing the first alignment measurement between the sensitive substrate 102 and the pallet 9b to which the sensitive substrate 102 is fixed during the pattern exposure of another sensitive substrate 101, the sensitive substrate on which the first alignment measurement is performed 102 and the pallet 9b are placed on the exposure stage 7, and the pallet 9b and the exposure stage 7
The above-mentioned object is achieved by performing the second alignment measurement with the above. (2) According to FIG. 3, according to the second aspect of the present invention, a sensitive substrate 10 fixed on a pallet 9 is placed on an exposure stage 7 and a pattern is formed on the sensitive substrate 10 by a charged beam B from a light source. A first alignment measurement of a sensitive substrate 10 before exposure and a pallet 9 to which the sensitive substrate 10 is fixed is performed during pattern exposure of another sensitive substrate. The alignment measurement means 8, 17, 18, 12x, 12y, the sensitive substrate 10 and the pallet 9 on which the first alignment measurement has been performed are mounted on the exposure stage 7, and the second Second alignment measuring means 15, 16, 11x, 11y for performing alignment measurement, and sensitive substrate 1 based on the results of the first and second alignment measurement.
The above-described object is achieved by providing the exposure stage 7 and a control unit for controlling the light source so as to perform exposure by performing alignment with the exposure stage 7. (3) The charged beam exposure apparatus according to the second aspect of the present invention provides the charged beam exposure apparatus, wherein
Light such as laser light was used for the alignment measurement. (4) Explaining with reference to FIG. 1, the invention according to claim 4 is the charged beam exposure apparatus according to claim 2 or 3, wherein a plurality of alignment marks 10a on the sensitive substrate 10 are used in the first alignment measurement. The relative positional relationship between the alignment marks 14a and 14b on the pallet 9 is measured. (5) Explaining in connection with FIG. 2, the invention of claim 5 is a pallet 9 used in the charged beam exposure apparatus according to any one of claims 2 to 4, wherein the first and second alignments are provided. A plurality of detection marks 14 used for measurement
a and 14b to achieve the above object.

[0007] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to the embodiment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing an embodiment of the present invention, and is a plan view schematically showing a charged beam exposure apparatus. 1 is a sample chamber, 2 is a supply chamber formed integrally with the sample chamber 1, 3 is an intermediate chamber, 4 is an atmosphere chamber,
The supply chamber 2 and the intermediate chamber 3 and the intermediate chamber 3 and the atmosphere chamber 4 are connected via valves 5 and 6, respectively, and the sample chamber 1 and the supply chamber 2 are directly connected without using a valve. The chamber including the sample chamber 1 and the supply chamber 2 and the intermediate chamber 3 are each configured to be evacuated by a vacuum exhaust device (not shown). Reference numerals 7 and 8 denote xy stages on which a sensitive substrate 10 such as a wafer fixed to a pallet 9 is placed, and 11x and 11y and 12x and 12y denote x, respectively.
This is a laser interferometer that measures the positions of the y stages 7 and 8. The sensitive substrate 10 is provided with a plurality of alignment marks 10a.

FIG. 2 is a perspective view of the pallet 9, and an electrostatic chuck 1 for fixing a sensitive substrate 10 on the upper surface of the pallet 9.
3, while the alignment marks 14a, 14
b is also provided. Alignment marks 14a, 14
b is a pattern obtained by depositing a heavy metal (Au, Ta, W, etc.) on a silicon substrate.

FIG. 3 is a front view of the exposure apparatus shown in FIG. 1, and a charged beam source 1 for generating a charged beam is provided in a sample chamber 1.
A charged beam optical system 15 including an electromagnetic lens 51, an electromagnetic lens 152, a deflector 153, and the like is provided. The charged substrate B placed on the stage 7 is irradiated with a charged beam B from the charged beam optical system 15 to perform a predetermined exposure. Done. The sample chamber 1 is also provided with a detector 16 for detecting scattered charged particles generated when the alignment marks 14a and 14b of the pallet 9 are scanned with the charged beam B, and is used for alignment mark position measurement described later. On the other hand, He-
Light source 171 and lens 172 for generating light such as Ne laser
And an alignment optical system 17 having an alignment mark 1 formed on the sensitive substrate 10.
0a (see FIG. 1) and the alignment mark 1 of the pallet 9
There is also provided a detector 18 for detecting diffracted light generated when the light is radiated to 4a and 14b. Note that FIG.
Then, the laser interferometers 11y and 12y and the standard mark 14
As for b, not shown in the figure, only parenthesized symbols are shown.

Here, measurement of the alignment mark position in each of the supply chamber 2 and the sample chamber 1 will be described. In the supply chamber 2, the relative positional relationship between the pallet 9 and a plurality of points on the sensitive substrate 10 is measured, and in the sample chamber 1, the relative positional relationship between the pallet 9 and the stage 7 is measured. Thereby, in the sample chamber 1, the relative positional relationship between the stage 7 and a plurality of points on the sensitive substrate 10 is indirectly known, and alignment is performed.

That is, in the supply chamber 2, the alignment marks 10 a formed on the sensitive substrate 10 and the alignment marks 14 a and 14 b formed on the pallet 9 are respectively scanned by the laser light, and the diffracted light is detected by the detector 18. Detects the detected data and the laser interferometer 12
The positional relationship between the alignment marks 14a and 14b and each alignment mark 10a is obtained based on the position of the xy stage 8 by x and 12y. That is, the coordinate system of the pallet 9 is determined from the position coordinates (x1, y1) of the alignment mark 14a and the position coordinates (x2, y2) of the alignment mark 14b, and the position of each alignment mark 10a on the sensitive substrate 10 with respect to the coordinate system. A position is required.

As described above, in the supply chamber 2, the pallet 9
When the relative positional relationship between the pallet 9 on the stage 7 of the sample chamber 1 and the pallet 9 on the stage 8 of the supply chamber 2 is measured by a transfer device (not shown), Replace at the same time. At this time,
Each pallet 9 has a sensitive substrate 10 and an electrostatic chuck 1 respectively.
In the sample chamber 1, the two alignment marks 14a and 14b are charged by the charged beam because the pallet 9 is placed on the xy stages 7 and 8 while being fixed to The position of the stage 7 is detected based on the detected data and the position data of the stage 7 measured by the laser interferometers 11x and 11y.
Of the pallet 9 with respect to. And
By using the relative positional relationship between the pallet 9 measured in the supply chamber 2 and the alignment mark 10a on the sensitive substrate 10 and the position coordinates of the pallet 9 with respect to the stage 7 measured in the sample chamber 1, the pattern to be exposed is determined. The position is determined.

Next, a series of operations of the exposure apparatus will be described with reference to FIG. In FIG. 4, pallets 9a to 9c are provided in the intermediate chamber 3, the supply chamber 2 and the sample chamber 1, respectively, and 101 to 105 are sensitive substrates. FIG.
In (a), the description starts assuming that the valve 5 is initially opened and the valve 6 is closed, and the chambers 1 to 3 are all evacuated. In the step shown in FIG. 4A, first, the valve 5 is closed to return the pressure of the intermediate chamber 3 to the atmospheric pressure. When the pressure in the intermediate chamber 3 reaches the atmospheric pressure, the valve 6 is opened, and the sensitive substrate 101 is transported from the atmospheric chamber 4 onto the pallet 9a of the intermediate chamber 3 by a transport device (not shown), and the electrostatic chuck 13 (see FIG. 3). To fix by electrostatic attraction.

In the step shown in FIG. 4B, the valve 6 is closed and the intermediate chamber 3 is evacuated to a predetermined pressure. Intermediate room 3
When the pressure reaches a predetermined pressure, the valve 5 is opened and the supply chamber 2 is opened.
Of the pallet 9b of the intermediate chamber 3 and the pallet 9a in the state where the sensitive substrate 101 is fixed. Thereafter, the valve 5 is closed to return the pressure in the intermediate chamber 3 to the atmospheric pressure, and then the valve 6 is opened, and the sensitive substrate 102 in the atmospheric chamber 4 is placed on the electrostatic chuck 13 of the pallet 9b in the intermediate chamber 3 and fixed. I do.
On the other hand, in the supply chamber 2, the above-described relative positional relationship between the alignment mark 10a of the sensitive substrate 101 and the pallet 9a (hereinafter, referred to as first alignment measurement) is performed.

In the step shown in FIG. 4C, the valve 6 is closed, the intermediate chamber 3 is evacuated, and the valve 5 is opened when a predetermined pressure is reached. Then, the pallet 9c of the sample chamber 1 and the pallet 9a of the supply chamber 2 are exchanged, and the pallet 9c transported to the supply chamber 2 and the pallet 9b of the intermediate chamber 3 are exchanged. Thereafter, the valve 5 is closed, and the positions of the alignment marks 14a and 14b of the pallet 9a are measured in the sample chamber 1 (hereinafter, referred to as second alignment measurement).
Based on this measurement result and the first alignment measurement result in the supply chamber 2, the stage 7 of the sample chamber 1 and the sensitive substrate 10
The relative positional relationship with the alignment mark 10a on the first substrate 1 is obtained, and thereafter the pattern exposure is performed on the sensitive substrate 101.
In parallel with the position measurement and the exposure step, the first alignment measurement of the pallet 9b and the alignment mark 10a on the sensitive substrate 102 is performed in the supply chamber 2. on the other hand,
After returning the intermediate chamber 3 to the atmospheric pressure, the valve 6 is opened to fix the sensitive substrate 103 to the pallet 9c. The sensitive substrate 1
The oblique line applied to 01 indicates that the pattern has been exposed.

In the step shown in FIG. 4D, the valve 6 is closed, the intermediate chamber 3 is evacuated, and the valve 5 is opened when a predetermined pressure is reached. Then, the pallet 9a of the sample chamber 1 is exchanged with the pallet 9b of the supply chamber 2, and the pallet 9a transported to the supply chamber 2 and the pallet 9c of the intermediate chamber 3 are exchanged. Thereafter, the valve 5 is closed, the second alignment measurement similar to that performed on the sensitive substrate 101 in FIG. 4C is performed in the sample chamber 1, and the stage 7 and the sensitive substrate 1 are measured.
After obtaining the relative positional relationship with the alignment mark 10a on the substrate 02, the photosensitive substrate 102 is subjected to pattern exposure. In parallel with this series of steps, the pallet 9
A first alignment measurement between c and the sensitive substrate 103 is performed. On the other hand, after returning the intermediate chamber 3 to the atmospheric pressure, the valve 6 is opened and the exposed sensitive substrate 101 on the pallet 9a is transported to the atmosphere chamber 4, and then the sensitive substrate 104 is placed on the pallet 9a.
Is transported and fixed. In this way, alignment and pattern exposure of the sensitive substrate are performed one after another. FIG.
(A) to FIG. 5 (c) show a first alignment measurement step in the supply chamber 2, a second alignment measurement step in the sample chamber 1,
3 shows a time chart of an exposure step in the sample chamber 1.

As can be seen from FIGS. 5A to 5C, in parallel with the second alignment measurement step and the exposure step for the sensitive substrate 101 in the sample chamber 1, the supply chamber 2 Since the first alignment measurement is performed, the throughput is improved. On the other hand, in the conventional case, the position of the alignment mark 10a on the sensitive substrate 101 is measured in the sample chamber 1, the alignment with the stage 7 is performed directly without passing through the pallet 9a, and then the exposure is performed. As shown in FIG. 5D, the efficiency is deteriorated, and the processing time t2 (the processing time of the alignment measurement step and the exposure step) per one sensitive substrate is reduced to the processing time t1 by the apparatus of the present embodiment. Longer than.

In the above-described exposure apparatus, as described in the step of FIG. 4C, the first alignment measurement (occupying most of the alignment time) between the alignment mark 10a and the pallet 9b on the sensitive substrate 102 is performed. Sensitive substrate 10
1 is performed in parallel during the exposure of the pallet 9 when the second alignment measurement of the sensitive substrate 102 in the sample chamber 1 is performed.
b, only two alignment marks 14a,
14b (see FIG. 3) need only be detected. Therefore, the ratio of the alignment measurement time to the throughput is reduced as compared with the conventional case, and the throughput can be improved.

In the above-described embodiment, the mark is detected using light at the time of the first alignment measurement, but a charged beam may be used. It is also possible to provide an alignment optical system 17 or the like in the intermediate chamber 3 instead of the supply chamber 2 to perform the first alignment measurement in the intermediate chamber 3, but the intermediate chamber 3 is evacuated or returned to atmospheric pressure. Therefore, the position of the sensitive substrate may be shifted after the alignment measurement, and the supply chamber 2 in a stable vacuum state is more suitable for the alignment measurement. Furthermore, in the above-described exposure apparatus, the first alignment measurement is performed in the exposure apparatus. However, the first alignment measurement does not necessarily have to be performed in the same apparatus. During the exposure of the wafer, the first alignment measurement between the pallet and the multiple points on the sensitive substrate is performed by the alignment measuring device provided separately from the exposure device, and the measured sensitive substrate and the pallet are transferred to the exposure device. Then, the second alignment measurement may be performed, and then the pattern exposure may be performed.

Further, conventionally, mark detection has been performed using a charged beam used for exposure, and the mark is scanned a plurality of times with the charged beam at the time of mark detection to improve the S / N ratio of a detection signal. Let me. By the way, recently, in order to achieve high throughput, a method of dividing a chip pattern into a plurality of small regions and exposing the pattern to each small region has been proposed, but the charged beam used in this method has a current density of Since it is low, it is difficult to obtain a high S / N ratio. However, when the mark detection is performed by light as in the exposure apparatus shown in FIG. 1, S is independent of the current density of the charged beam.
There is an advantage that detection with a good / N ratio can be performed.

In the correspondence between the embodiment of the invention described above and the elements of the claims, the laser interferometers 11x and 11x
The y, charged beam optical system 15 and detector 16 constitute first alignment measuring means, and the alignment optical system 17, detector 18, laser interferometers 12x, 12y and xy stage 8 constitute second alignment measuring means, respectively. .

[0023]

As described above, according to the present invention,
The first alignment measurement between the sensitive substrate and the pallet is performed in parallel during the exposure of the other sensitive substrate. For the sensitive substrate and the pallet placed on the exposure stage, the second alignment measurement between the pallet and the exposure stage is performed. All that is required is to perform alignment measurement. Therefore, the ratio of the alignment measurement time to the throughput is reduced as compared with the conventional case, and the throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a charged beam exposure apparatus.

FIG. 2 is a perspective view of a pallet 9;

FIG. 3 is a front view of the charged beam exposure apparatus shown in FIG.

FIG. 4 is a diagram for explaining the operation of the exposure apparatus, and FIGS.
(D) shows each step.

FIG. 5 is a time chart of an alignment measurement step and an exposure step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sample chamber 2 Supply chamber 3 Intermediate chamber 4 Atmosphere chamber 7,8 xy stage 9,9a-9c Pallet 10,101-105 Sensitive substrate 10a, 14a, 14b Alignment mark 11x, 11y, 12x, 12y Laser interferometer 15 Charge beam Optical system 16, 18 Detector 17 Alignment optical system

Claims (5)

[Claims] 1. A charged beam exposure method for exposing a pattern by fixing a plurality of sensitive substrates on a pallet and sequentially placing the sensitive substrates fixed on the pallet on an exposure stage of a charged beam exposure apparatus to expose a pattern. After performing the first alignment measurement between the sensitive substrate and the pallet to which the sensitive substrate is fixed during the pattern exposure of another sensitive substrate, the sensitive substrate and the pallet on which the first alignment measurement has been performed are removed. A charged beam exposure method, wherein the charged stage is mounted on the exposure stage, and a second alignment measurement between the mounted pallet and the exposure stage is performed. 2. A charged beam exposure apparatus for placing a sensitive substrate fixed on a pallet on an exposure stage and exposing a pattern on the sensitive substrate by a charged beam from a light source, wherein the sensitive substrate before exposure and the sensitive substrate A first alignment measuring means for performing a first alignment measurement with a pallet to which is fixed during pattern exposure of another sensitive substrate, and exposing the sensitive substrate and the pallet on which the first alignment measurement has been performed to the exposure A second alignment measuring unit mounted on a stage for performing a second alignment measurement between the pallet and the exposure stage; a sensitive substrate and the exposure stage based on a result of the first and second alignment measurements; Control means for controlling the exposure stage and the light source so as to perform exposure by performing alignment with, and Beam exposure equipment. 3. The charged beam exposure apparatus according to claim 2, wherein light such as laser light is used for the first alignment measurement between the sensitive substrate and the pallet. 4. The charged beam exposure apparatus according to claim 2, wherein in the first alignment measurement, a relative positional relationship between a plurality of alignment marks on the sensitive substrate and the alignment marks on the pallet is measured. A charged beam exposure apparatus. 5. A pallet used in the charged beam exposure apparatus according to claim 2, comprising a plurality of detection marks used for the first and second alignment measurements. Pallet to feature.