JP3242122B2 - Pattern forming method and semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming technology and a semiconductor device manufacturing technology, and more particularly, to a technology effective when applied to a semiconductor device manufacturing technology for transferring a pattern by irradiation of a charged particle beam such as an electron beam. It is about.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor integrated circuit device, an electron circuit or a laser beam is used to draw an integrated circuit pattern on a photomask (reticle) or a semiconductor wafer.
2. Description of the Related Art Fine processing techniques for an integrated circuit pattern using various focused beams, such as correcting a defective portion of an integrated circuit pattern using a focused ion beam, have been put to practical use.

Among the above focused beam processing techniques, an electron beam direct writing technique for directly writing (exposing) an integrated circuit pattern on a wafer by irradiating an electron beam on a wafer coated with an electron beam resist is known as a method for forming an image on a photomask. In recent years, it has been particularly noted that an integrated circuit pattern can be formed finer than a conventional light exposure technique of transferring the integrated circuit pattern onto a wafer.

In the above focused beam processing technology, high precision fine processing is realized by controlling a focused beam by computer based on design data of an integrated circuit and by accurately aligning the beam with a sample. .

Further, a semiconductor substrate on which a pattern is drawn has a distortion and a surface step generated during repetition of many steps. In response to this, it is necessary to correct an exposed figure drawn by an electron beam. It is indispensable to maintain the overlay accuracy and dimensional accuracy of the exposed figures.
The control computer performs predetermined correction on the drawing data for each unit exposure area, and then sends the data to individual control circuits of the electron optical system.

[0006] In the exposure method using a charged particle beam, the pattern is generally filled with an extremely finely converged beam, so that throughput is a problem. Therefore, as a countermeasure, for example, a technique of transferring a mask image in the same manner as in the case of light exposure is described in, for example, Press Journal Co., Ltd., published on June 20, 2001, “Semiconductor World”, July 1990, p. It is described in documents such as P175. That is, a relatively large pattern is transferred by one irradiation by forming an opening pattern of a specific shape in a small area of the mask by selectively transmitting a beam having a relatively large diameter.

[0007]

The above-described conventional mask image transfer technology using a charged particle beam has been proposed as a promising means for improving the throughput, but has the following problems. Found by the inventor.

In order to transfer a mask image using a charged particle beam, it is necessary to reduce the alignment error between the transfer mask and the workpiece. In particular, when applied to a semiconductor integrated circuit device, it is necessary to switch and use a plurality of types of transfer masks for each process.

At this time, it is essential that the alignment error of the transfer mask can be easily corrected.

In particular, within the alignment error, the position of the mask,
The magnification may be corrected by the beam control system, but the rotation of the mask has a problem that the error cannot be easily measured, so that the correction becomes difficult.

Further, pattern defects and adhered foreign substances on the transfer mask are transferred in the same manner as in the case of the optical mask, and become defects in the semiconductor integrated circuit device. In addition, when selecting and transferring from a plurality of masks, a mask pattern cannot be directly seen, so that a mask selection error occurs. However, eliminating this error is an important issue.

An object of the present invention is to provide a pattern forming technique and a pattern forming technique capable of achieving both an improvement in throughput by using a mask and an improvement in pattern transfer accuracy in pattern transfer using a charged particle beam formed by a mask. An object of the present invention is to provide a semiconductor device manufacturing technique.

Another object of the present invention is to provide a pattern forming technique and a semiconductor device manufacturing technique capable of accurately verifying a plurality of masks and an opening pattern formed in the masks.

It is still another object of the present invention to provide a pattern forming technique and a semiconductor device manufacturing technique capable of quickly exchanging a plurality of types of masks.

Still another object of the present invention is to provide a pattern forming technique and a semiconductor device manufacturing technique capable of preventing occurrence of an error due to distortion of a vacuum load lock mechanism or the like.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0017]

Means for Solving the Problems Among the inventions disclosed in the present application, the outline of a representative invention will be briefly described.
It is as follows.

That is, according to the present invention, a first mask having a rectangular opening and a second mask having a plurality of figure-shaped openings are arranged on a path from an electron beam source to a sample on a stage for irradiating the electron beam. A pattern forming step of irradiating a sample with an electron beam formed by selecting and combining transfer pattern openings of a second mask by deflecting a transmitted electron beam of the first mask to form a pattern; In the second mask, a pair of beam calibration rectangular apertures that can be selected at a time by an electron beam are provided at positions two-dimensionally arranged so that the irradiation areas of the transmitted electron beam of the first mask do not overlap. And a plurality of transfer pattern openings. A pair of beam calibration rectangular openings on the second mask is selected by the electron beam deflection control means to transmit the transmitted electron beam. Detected with an scanning Faraday cup having a knife edge which is provided on the stage the arm,
After calibrating an error including a rotation error of the electron beam transmitted through the second mask, a combination of the transfer pattern openings is selected and irradiated with the electron beam to form a pattern on the sample.

Further, according to the present invention, a first mask having a rectangular opening and a second mask having a plurality of figure-shaped openings are arranged on a path from an electron beam source to a sample on a stage for irradiating the electron beam. And controlling the deflection of the transmitted electron beam of the first mask to irradiate the sample with an electron beam formed by selecting and combining the transfer pattern openings of the second mask to form a pattern. In the manufacturing method, an XY plane moving unit of the second mask is provided as a unit for selecting a transfer pattern opening of the second mask, and the second mask is selected by moving the second mask. A pair of beam calibration rectangles that can be selected at a time by an electron beam are placed at positions two-dimensionally arranged so that the transmission electron beam irradiation regions of the first mask do not overlap in the region A knife edge in which an opening and a plurality of transfer pattern openings are provided, and a pair of beam calibration rectangular openings on the second mask are selected by the electron beam deflecting means, and the transmitted electron beam is provided on the stage. After detecting the error including the rotation error of the electron beam transmitted through the second mask by detecting the Faraday cup by scanning, etc., select the combination of the transfer pattern openings and irradiate the electron beam to irradiate the electron beam to pattern the sample. To form. According to the present invention, in the pattern forming method described above, the graphic-shaped opening of the second mask is a part of the integrated circuit pattern, and the integrated circuit pattern is formed on the sample.
Further, the present invention is a method of manufacturing a semiconductor device for forming an integrated circuit pattern on a semiconductor wafer as a sample using the above-described pattern forming method.

In the above method of manufacturing a semiconductor device, the second mask is mounted on a part of the lens barrel, the lens barrel is provided with a vacuum load lock chamber, and the degree of vacuum of the beam irradiation system is reduced. The second mask is replaced without lowering, and a desired pattern is drawn.

[0021]

[0022]

[0023]

[0024]

According to the pattern forming technique and the semiconductor device manufacturing technique of the present invention described above, an electron beam that passes through at least two isolated positioning opening patterns at a time in the beam deflection area is placed on the stage. By detecting by scanning a Faraday cup having a provided knife edge, the transfer position of the opening pattern on the mask onto the sample can be corrected, and the second position can be corrected without causing a magnification or rotation error. Pattern transfer by irradiation of a charged particle beam selectively transmitted through the opening pattern of the mask can be performed with high accuracy. That is, it is possible to achieve both an improvement in throughput by the mask method and an improvement in pattern transfer accuracy.

Further, based on the state of generation of charged particles from the second mask and the like when the charged particle beam passes through the second mask, identification of each second mask, identification of the opening pattern, and confirmation of the shape are performed. , Etc. can be accurately verified.

Further, by exchanging the second mask through the first vacuum load lock chamber provided in the lens barrel, the mask can be quickly exchanged without impairing the degree of vacuum in the lens barrel. This is effective in improving the throughput in the transfer step.

Further, the deformation caused by a change in air pressure in the second vacuum load lock chamber due to a deformation absorbing mechanism provided in the second vacuum load lock chamber for exchanging a sample causes distortion of a pattern transfer device such as a lens barrel. It is prevented from spreading to the main body side, and the pattern transfer accuracy can be improved.

[0028]

Embodiment 1 FIG. 1 is a perspective view showing an essential part of a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to an embodiment of the present invention are carried out. A semiconductor wafer 1 as a sample is mounted on a stage 2 including an XY stage movable in a horizontal plane. The surface of the semiconductor wafer 1 is coated with, for example, an electron beam resist or the like. An electron gun 3 is provided above the stage 2 so that an electron beam 4 is emitted toward the semiconductor wafer 1.

On the path of the electron beam 4 from the electron gun 3 to the stage 2, there are provided a blanking electrode 5 for controlling the emission of the electron beam 4, an irradiation lens 6 for converging the electron beam 4, and the irradiation lens 6. The electron beam 4 converged by the first mask 7 passes through, for example, a first mask 7 on which a rectangular opening pattern 7a is formed, a deflector 8, a beam shaping lens 9,
A second mask 10 on which a plurality of desired opening patterns 10a are formed as described below, a reduction lens 11 for reducing the cross-sectional shape of the electron beam 4 passing through the second mask 10, a direction around the optical axis of the electron beam 4. An electron optical system including a rotary lens 11a for performing rotation correction and the like, a projection lens 12 for performing focusing and the like of the electron beam 4 on the semiconductor wafer 1, a position deflector 13 for controlling an irradiation position of the electron beam 4 on the semiconductor wafer 1, and the like. Is provided.

FIG. 2 is an explanatory view showing an example of the structure and operation of the second mask 10. As shown in FIG.

As shown in FIG. 2A, a deflectable range of the electron beam 4 by the deflector 8 located between the second mask 10 and the first mask 7 in the preceding stage is provided on the second mask 10. A plurality of opening patterns 10a each having a size that can be accommodated therein are arranged in a lattice shape, and each opening pattern 10a includes, for example, a plurality of independent transfer patterns A to I.

In this case, a part of the transfer patterns A to I includes, for example, a pair of isolated patterns i1 and i2 which can be simultaneously selected by the electron beam 4 passing through the first mask 7 at both corners in the diagonal direction. Are formed.

Then, at the time of collective transfer of each of the transfer patterns A to I onto the semiconductor wafer 1, the misalignment of the second mask 10 is corrected by appropriately using the isolated patterns i1 and i2.

That is, by using two isolated patterns i1 and i2 which can be simultaneously selected by the electron beam 4,
Correction is possible by measuring in advance the relationship between the exciting current and the magnification of the reduction lens 11 and the relationship between the rotation lens 11a and the rotation angle of the reduction lens 11 constituting the electron optical system after the second mask 10. However, in the case of the isolated patterns i1 and i2 provided in a region that can be selected at a time by the electron beam 4,
Since the distance between them is small, it is necessary to increase the detection accuracy of the beam position. Therefore, in the case of the present embodiment, a not-shown Faraday cup portion having a knife edge provided on the stage 2 on which the semiconductor wafer is mounted is scanned a plurality of times in both the X-axis and the Y-axis directions to determine the beam position. Improve detection conditions. The method of detecting the reflected electrons by scanning the step marks on the semiconductor wafer has a low detection accuracy.

It is also conceivable to form isolated patterns c and g at both corners of the opening pattern 10a, the distance between each of which is larger than the above-mentioned isolated patterns i1 and i2. However, in this case, since the individual isolated patterns c and g cannot be selected at one time, it is necessary to adjust the beam deflection for individually selecting the two and the beam swingback after the selection, and the correction work becomes slightly complicated. Become.

FIG. 2B is a schematic diagram showing a detection signal waveform when scanning a Faraday cup (not shown) by the electron beam 4 passing through the isolated patterns i1 and i2 for each of the X-direction scanning and the Y-direction scanning. This is shown in FIG. The distances lx and ly are obtained from the peak positions of the detected waveforms in the respective scanning directions, and the magnification error M and the rotation error of the transfer patterns A to I can be measured by Expressions (1) and (2). And the second mask 1
The correction of the relationship between the exciting current of the reduction lens 11 and the magnification, the relationship between the rotation lens 11a and the rotation angle, and the correction of the scanning direction and scanning width of the electron beam 4 are performed. Further, in the case of the present embodiment, the isolated pattern i1,
Since the positional relationship of i2 is set in the diagonal direction of the transfer patterns A to I, when the two electron beams 4 that have passed through the individual isolated patterns i1 and i2 are used, the XY biaxial scanning of the electron beam 4 is performed. This makes it easier to measure.

Hereinafter, an example of the operation of the pattern forming method and the method of manufacturing the semiconductor device performed by the pattern transfer apparatus of this embodiment will be described.

First, the second mask driving mechanism 14
The target opening pattern 10a in the mask 10 is positioned on the optical axis of the electron optical system.

Next, the electron beam 4 having passed through the first mask 7 is converted by the deflector 8 into an isolated pattern formed on one of the transfer patterns A to I (in this case I) included in the opening pattern 10a. The electron beam is led to i1 and i2, passes through the isolated pattern i1 and i2, and is irradiated as two electron beams 4 on the stage 2 side. And the stage 2
By scanning a Faraday cup (not shown) provided in the printer, a transfer error such as a rotational error or a magnification error of the isolated patterns i1 and i2 around the optical axis is measured and stored.

Thereafter, the opening pattern 7a of the first mask 7 is formed.
The electron beam 4 that has passed through is guided by the deflector 8 to the target transfer patterns A to I of the opening pattern 10a, the cross-sectional shape of the electron beam 4 is shaped, and the shaped electron beam 4 is subjected to the above-described measurement. Lens 11 and rotating lens 11 whose operations are corrected by the correction values obtained by
a, by controlling the projection lens 12, the position deflector 13 and the like, the transfer patterns A to
Irradiation is performed in the shape of I to expose the electron beam resist on the surface of the semiconductor wafer 1.

As described above, according to the pattern transfer apparatus of this embodiment, the target transfer patterns A to I by the irradiation of the electron beam 4 formed by the combination of the first mask 7 and the second mask 10 are collectively collected. It is possible to achieve both an improvement in throughput by transfer and an improvement in transfer accuracy.

[0042]

[Embodiment 2] FIG. 3 is an explanatory view showing a main part of the configuration of a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to another embodiment of the present invention are performed. In the case of the second embodiment, charged particles such as reflected electrons and secondary electrons generated when the second mask 10 is scanned by the electron beam 4 are disposed between the beam shaping lens 9 and the second mask 10. A sensor 20 for detecting an amount is arranged.

The output of the sensor 20 is one input of a comparator 23 via an amplifier 21 and a changeover switch 22. A memory 24 for storing measurement data via the changeover switch 22 is provided to the other input of the comparator 23.
It is connected via a changeover switch 25. Further, the changeover switch 25 is also connected to a memory 26 in which design data 27 of the transfer patterns A to I in the second mask 10 is stored.

The electron beam 4 passes through the first mask 7 and scans the opening pattern 10a of the second mask 10 under the control of the deflector 8 and the beam shaping lens 9, and the charged particles obtained at this time are scanned. The detection signal is stored in the memory 24, and when a part of the plurality of opening patterns 10a on the second mask 10 is selected later, the memory 24
The verification of the shapes and types of the selected transfer patterns A to I is performed by comparing with the detection signals held in the transfer patterns. Further, it is also possible to compare the detection signal during the transfer operation with the design data 27 of the transfer patterns A to I of the second mask 10. However, since the detection signal of the actual pattern of the second mask 10 and the signal obtained from the design data have, for example, different roundness at the pattern corners, data processing corresponding thereto is performed as necessary.

As described above, in the case of the second embodiment, the second
The shape, type, and the like of the opening pattern 10a of the mask 10 can be verified. For example, a transfer error due to a foreign substance attached to the second mask 10, an erroneous loading of the second mask 10, or an erroneous selection of the opening pattern 10a. A mistake in the transfer operation due to, for example, the above can be reliably prevented. This means that many secondary
This is particularly effective for maintaining and improving the reliability of the pattern transfer operation in a mass production process using the mask 10 or the like.

[0046]

Third Embodiment FIG. 4 is a schematic sectional view showing an example of the configuration of a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to another embodiment of the present invention are performed.

The housing 30 containing the stage 2 composed of an XY table or the like is connected with the lens barrel 40 containing the electron optical system having the structure illustrated in FIG. .

The inside of the housing 30 and the lens barrel 40 is evacuated to a desired degree of vacuum by a vacuum pump 31. Further, a part of the housing 30 is provided with a stage driving unit 32 for driving the stage 2, a laser length measuring device 33 for accurately measuring the displacement of the stage 2, and the like. An arbitrary portion of the semiconductor wafer 1 can be positioned on the optical axis of the electron optical system provided in the lens barrel 40.

A part of the housing 30 has a well-known vacuum load that allows the semiconductor wafer 1 mounted on the stage 2 to be moved in and out of the housing without impairing the degree of vacuum in the housing 30. The lock chamber 34 is connected via a gate valve 35.

In this case, a deformation absorbing mechanism 36 made of, for example, a bellows is provided on a part of the wall surface of the vacuum load lock chamber 34. Thus, the vacuum load lock chamber 34 is generated in accordance with a change in the internal pressure when the vacuum load lock chamber 34 is evacuated or returned to the atmospheric pressure.
This serves to absorb the mechanical deformation and distortion of the body 30 by the deformation of the deformation absorbing mechanism 36 itself, and to prevent the deformation and distortion from spreading to the housing 30 and the lens barrel 40 side.

Further, in the case of the present embodiment, a vacuum load lock chamber 42 is connected via a gate valve 41 to a portion of the lens barrel 40 where the second mask 10 is loaded. No loss of vacuum inside
The structure allows the mask 10 to be replaced at any time.

As described above, in the third embodiment, the pattern transfer operation using the electron optical system provided in the lens barrel 40 and the transfer of the semiconductor wafer 1 through the vacuum load lock chamber 34 are performed in parallel. In this case, the distortion caused by the change in the internal pressure of the vacuum load lock chamber 34 does not spread to the housing 30 and the lens barrel 40, and the electron beam 4 controlled by the electron optical system allows the semiconductor wafer 1 to be highly accurate. Can be performed.

Further, the replacement operation of the second mask 10 can be performed simply and quickly through the vacuum load lock chamber 42 provided in the lens barrel 40 without impairing the degree of vacuum inside the lens barrel 40 and the housing 30. And the operation rate of the pattern transfer apparatus is improved.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist of the invention. Needless to say.

For example, the configuration of the electron optical system is not limited to those illustrated in the above-described embodiments, but may be another configuration.

As an example of pattern transfer, a case where the present invention is applied to an exposure process of a semiconductor wafer has been described. However, it goes without saying that the present invention may be applied to a general processing technique using a charged particle beam formed by a mask.

[0057]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

That is, according to the pattern forming method and the semiconductor device manufacturing method of the present invention, in the pattern transfer using the charged particle beam by the mask method, the throughput is improved by using the mask and the pattern transfer accuracy is improved. The effect that both can be achieved is obtained.

According to the pattern forming method and the semiconductor device manufacturing method of the present invention, it is possible to obtain an effect that a plurality of masks and an opening pattern formed on the mask can be accurately verified.

Further, according to the pattern forming method and the semiconductor device manufacturing method of the present invention, there is obtained an effect that a plurality of types of masks can be easily and quickly exchanged.

Further, according to the pattern forming method and the semiconductor device manufacturing method of the present invention, it is possible to prevent the occurrence of a transfer pattern error due to a distortion or the like in a vacuum load lock mechanism spreading to a housing or a lens barrel. Is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to one embodiment of the present invention are performed.

FIG. 2 is an explanatory diagram showing an example of the configuration and operation of a mask used in a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to one embodiment of the present invention are implemented.

FIG. 3 is an explanatory view showing a main part of a configuration of a pattern transfer apparatus in which a pattern forming method and a semiconductor device manufacturing method according to another embodiment of the present invention are implemented.

FIG. 4 is a schematic cross-sectional view showing an example of a configuration of a pattern transfer device in which a pattern forming method and a semiconductor device manufacturing method according to another embodiment of the present invention are performed.

[Explanation of symbols]

 i1 isolated pattern i2 isolated pattern c isolated pattern g isolated pattern 1 semiconductor wafer 2 stage 3 electron gun 4 electron beam 5 blanking electrode 6 irradiation lens 7 first mask 7a opening pattern 8 deflector 9 beam shaping lens 10 second mask 10a opening Pattern 11 Reduction lens 11a Rotating lens 12 Projection lens 13 Position deflector 14 Mask driving mechanism 20 Sensor 21 Amplifier 22 Changeover switch 23 Comparator 24 Memory 25 Changeover switch 26 Memory 27 Design data 30 Housing 31 Vacuum pump 32 Stage driving unit 33 Laser Length measuring device 34 Vacuum load lock chamber (second vacuum load lock chamber) 35 Gate valve 36 Deformation absorption mechanism 40 Lens tube 41 Gate valve 42 Vacuum load lock chamber (first vacuum load lock chamber)

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

Claims (4)

(57) [Claims] An electron beam is emitted from an electron beam source.
The path to the sample on the stage has a rectangular opening
One mask and a second mask having a plurality of graphic shaped openings.
A mask, and deflects the transmitted electron beam of the first mask.
The transfer pattern of the second mask.
The electron beam formed by selecting and combining the electron beam openings.
Pattern including a step of patterning by irradiating the sample
In the method, the second mask may be formed by the first mask.
Make sure that the irradiation areas of the transmitted electron beam do not overlap.
Select at one time with the electron beam at the dimensional arrangement position
Possible pair of beam calibration rectangular aperture and multiple transfer patterns
And an electron beam deflection control means.
A pair of the beam calibration rectangles on the second mask.
Select an aperture and transfer the transmitted electron beam to the stay.
Running of Faraday cup with knife edge set on the top
Inspection, etc., and transmitted through the second mask.
After calibrating the error including the electron beam rotation error,
Select the combination of the photo-pattern openings and select the electron beam
Irradiating to form a pattern on the sample.
Pattern formation method . 2. An electron beam is emitted from an electron beam source.
The path to the sample on the stage has a rectangular opening
One mask and a second mask having a plurality of graphic shaped openings.
A mask, and deflects the transmitted electron beam of the first mask.
The transfer pattern of the second mask.
The electron beam formed by selecting and combining the electron beam openings.
Pattern including a step of patterning by irradiating the sample
Forming a transfer pattern of the second mask.
As means for selecting a mask opening, X of the second mask is used.
Y-plane moving means is provided, and the second mask
In the area selected by moving the mask,
The irradiation areas of the transmitted electron beam of the first mask do not overlap.
Once in the two-dimensionally arranged position with the electron beam
Selectable pair of beam calibration rectangular apertures and multiple transfers
A pattern opening is provided for the electron beam deflecting means.
Thus, the pair of beam calibration rectangles on the second mask
The aperture is selected and the transmitted electron beam is
Of a Faraday cup with a knife edge
Before being detected by scanning or the like and having passed through the second mask
After calibrating the error including the rotation error of the electron beam,
Select the combination of the transfer pattern opening and the electron beam
And forming a pattern on the sample.
Pattern forming method . 3. A pattern forming method according to claim 1 or 2.
Wherein the figure-shaped opening of the second mask is
Part of an integrated circuit pattern, wherein the integrated circuit
Pattern forming method characterized by forming a pattern
Law. 4. A pattern according to claim 1, 2 or 3.
Integrated on a semiconductor wafer as the sample by using
Forming a circuit pattern;
Production method.