JP3221566B2 - Charged beam writing method and charged beam writing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged beam drawing apparatus for controlling the deflection of a charged particle beam such as an electron beam or an ion beam on a sample such as a wafer or a mask and drawing an LSI pattern or the like. The present invention relates to a charged beam writing system suitable for performing pattern writing in a so-called mix-and-match manner using a charged beam writing apparatus with high accuracy and efficiency, and a semiconductor device having a pattern drawn by the system. .

[0002]

2. Description of the Related Art Charged particle beams such as electron beams and ion beams have high resolution and excellent controllability due to their properties, and are used in light exposure apparatuses (stepper exposure apparatuses) for manufacturing semiconductors. It is used in a drawing apparatus for drawing a pattern on a mask to be drawn, a drawing apparatus for drawing a pattern directly on a wafer, and the like. For example, a CAD (Computer Aided Desig) is used in an electron beam drawing apparatus as described in the IEICE Handbook (1988, published by Ohmsha, pp. 732-733).
First, the drawing pattern data designed in n) is subjected to necessary processing in a drawing processing unit, and is used as electron beam deflection data. The deflection data is converted into an analog voltage (current) by a D / A converter and an amplifier, and is applied to a deflector in the electron beam mirror to perform drawing.

Normally, the higher the resolution of a D / A converter, that is, the greater the number of bits, such as 17 bits or 20 bits, the more difficult it is to maintain its linearity. As a conventional technique for solving this problem, for example, as described in JP-A-58-181323,
A technique has been disclosed in which the linearity of an output voltage with respect to bit pattern data is measured using a high-precision voltmeter, correction data for minimizing an error is obtained, and correction is performed so as to approach an ideal straight line.

In an electron beam writing apparatus, when the resist sensitivity is Q, the irradiation current is I, and the irradiation time is T,
The relationship “Q = I × T” holds. Here, the irradiation current (I) is measured by a built-in ammeter, and the irradiation time (T) is generated based on a built-in crystal oscillator. Then, drawing is performed by setting an appropriate dose (Dose, exposure amount) based on the irradiation current (I) and the irradiation time (T).

[0005] Such an electron beam writing apparatus has a lower throughput than an optical exposure apparatus. In order to improve such throughput, a plurality of electron beam writing apparatuses may be arranged and operated in the same maintenance area (for example, in the same clean room). In this case, for example, rather than drawing all the layers of the wafer with one electron beam drawing apparatus, pattern drawing by a mix and match method in which a plurality of electron beam drawing apparatuses are used to draw a pattern on the same wafer is performed. It is efficient.

[0006] In general, mix and match refers to drawing across different types of machines. Here, mix and match refers to the following form. That is, a pattern is drawn at a desired position on the wafer by the first electron beam drawing apparatus, and then, after a predetermined process of the next process other than the first electron beam drawing apparatus, the pattern is drawn on the previously drawn pattern. The second electron beam drawing apparatus is used when another pattern is drawn by superimposing the pattern. By performing pattern writing with a plurality of electron beam writing apparatuses in such a mix-and-match manner, even if the first electron beam writing apparatus is writing a pattern on a wafer of the next lot, another electron beam writing apparatus is not allowed. With the apparatus, another pattern can be drawn on the wafer that has undergone a predetermined process of the next step in a superimposed manner, and efficient pattern drawing can be performed.

When pattern writing is performed in such a mix-and-match manner, it is necessary that the characteristics of a plurality of electron beam writing apparatuses completely match. However, for example, an ammeter for measuring a beam current has an absolute value error and a change over time in characteristics. The time (shot time) during which a beam is irradiated on a wafer or the like coated with a resist is generated based on a reference clock from a crystal oscillator or the like, but the reference clock changes over time. When these changes occur, the dose condition changes, and an appropriate exposure pattern cannot be obtained. In order to deal with such a problem, it is necessary to periodically draw a test pattern and reset the dose condition.

A further problem is the variation in the linearity of the high-accuracy voltmeter used for calibrating the linearity of the D / A converter for converting the drawing pattern data into the deflection voltage (current). For example, when the linearity of the high-accuracy voltmeter built in the first electron beam lithography apparatus is convex and the linearity of the high-accuracy voltmeter built in the second electron beam lithography apparatus is concave,
The difference directly becomes a drawing error.

[0009]

The problem to be solved is that the conventional techniques cannot completely match the respective characteristics of a plurality of charged beam writing apparatuses. An object of the present invention is to solve the problems of the related art, and to perform pattern drawing of a semiconductor device by mix and match using a plurality of charged beam drawing apparatuses, and the like.
An object of the present invention is to provide a charged beam writing system capable of performing the processing with high accuracy and efficiency, and a semiconductor device having a pattern drawn by the system.

[0010]

In order to achieve the above object, a charged beam drawing system according to the present invention uses a plurality of charged beam drawing devices, in which a reference device conventionally provided individually for each charged beam drawing device is replaced by a plurality of charged beam drawing devices. A common configuration is used to reduce drawing errors between charged beam drawing apparatuses. This makes it possible to install a plurality of charged beam writing apparatuses in the same maintenance area and perform wafer pattern writing or the like by mix-and-match with high accuracy. The throughput of the beam writing apparatus can be improved.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the configuration according to the present invention of the charged beam drawing system of the present invention. The charged beam lithography system of the present example includes a first electron beam lithography apparatus 100 and a second electron beam lithography apparatus 200 which are respectively arranged in the same clean room.
And the reference device 300.

The first electron beam drawing apparatus 100 includes a drawing control section 110, an electron beam control section 120, and an electron beam mirror section 130, and draws a high-precision pattern on a wafer or a mask. Incidentally, the mask is further used for drawing a wafer with a light exposure apparatus, and through such a mask or the first electron beam drawing apparatus 1.
The wafer on which the pattern is directly drawn by the process 00 is incorporated into a semiconductor device through processes such as dicing, die bonding, wire bonding / wireless bonding, and sealing.

In the first electron beam drawing apparatus 100, a drawing control section 110 decomposes drawing data generated by CAD or the like into a shot figure which can be drawn to generate deflection control data. Further, the electron beam control unit 120 corrects the characteristics based on the reference device 300, and
The deflection control data generated in step 10 is converted into a voltage (current) signal having a desired size and timing. Then, the electron beam mirror unit 130 controls the electron beam based on the control signal converted by the electron beam control unit 120, and draws a desired figure on a wafer or a mask placed inside.

On the other hand, the second electron beam writing apparatus 200
Is composed of a writing control unit 210, an electron beam control unit 220, and an electron beam mirror unit 230, as in the first electron beam writing apparatus 100. A reference device 300 used for calibrating the electron beam control unit 120 of the beam drawing apparatus 100 is connected, and the reference device 300
The characteristics are calibrated in the same manner as the electron beam control unit 120.

As described above, in this embodiment, the first electron beam writing apparatus 100 and the second electron beam writing apparatus 200
One electron beam writing apparatus is installed in the same clean room, and the respective characteristics are commonly calibrated by one reference apparatus 300. Hereinafter, the detailed configuration and operation of such a charged beam writing system will be described with reference to FIG.

FIG. 2 is a block diagram showing a detailed configuration example of the charged beam drawing system in FIG. First, the configuration and operation of the first electron beam writing apparatus 100 will be described. The electron beam control unit 120 includes a shot time control unit 121, a D / A converter 122, and an ammeter 123. The electron beam mirror unit 130 includes a blanking deflection plate 132 for turning on and off the electron beam 131, A deflector 133 for controlling the deflection of the electron beam 131, and a sample stage 13 on which a sample 134 such as a wafer or a mask is placed.
5 and a current sensor 136 used for measuring the current of the electron beam 131 .

The shot time control unit 121 in the electron beam control unit 120 sends a blanking deflection plate 132 based on the shot time data from the drawing control unit 110 to the
A shot time control signal for turning on / off the electron beam 131 is given. Further, the shot time control unit 121
Generates a blanking signal of the electron beam 131 by counting a clock of a reference oscillator 304 provided in the reference device 300 and comparing the counted clock with shot time data.

The D / A converter 122 is connected to the drawing control unit 110
Is converted into a deflection voltage (current) having a corresponding magnitude, and the deflector 133 is controlled. As a result, the electron beam 131 is deflected to a desired position on the sample 134 such as a wafer or a mask placed on the sample table 135. Therefore, the linearity of the output with respect to the input data of the D / A converter 122 is important for securing the drawing accuracy. The calibration of the linearity is performed before drawing according to the following procedure.

First, the drawing control unit 110 includes the identification unit 307
, The switches 301 and 302 are turned on. Thereafter, the predetermined deflection data is supplied to the D / A converter 122, and the output voltage is measured by the high-accuracy voltmeter 306. This measurement result is sent to the drawing control unit 110 via the switch 301.
Is stored in a memory having predetermined deflection data therein as an address. In this procedure, the predetermined deflection data is incremented at a predetermined pitch.

Further, the drawing control section 110 obtains a linearity error based on the correlation between the data given to the D / A converter 122 and its analog output. Then, the correction data for minimizing the linearity error of the D / A converter 122 thus calculated is calculated. The calculated correction data is stored in a correction data memory having the deflection data as an address. At the time of actual drawing, the drawing pattern data and the contents of the correction data memory read out corresponding to the drawing pattern data are added. As a result of this addition, the linearity of the D / A converter 122 is ensured. Further, by giving the added deflection voltage (current) to the deflector 133, it is possible to perform writing with high deflection accuracy.

The ammeter 123 is used to obtain appropriate shot time data by measuring the current value of the beam 131 applied to a sample 134 such as a wafer or a mask. To this end, high measurement accuracy of the ammeter 123 must be ensured. This ammeter 12
The check of the characteristic of No. 3 is performed at an appropriate time before drawing as follows.

First, the drawing control unit 110 includes the identification unit 307
, The switch 303 is turned on to the reference power supply side. After that, predetermined data is given to the reference power supply 305. As a result, the reference current output from the reference power supply 305 is measured by the ammeter 123, and the reference current measured by the ammeter 123 is stored in the memory of the drawing control unit 110.
This operation is performed while switching the sensitivity of the ammeter 123, and the sensitivity characteristics of the ammeter 123 in a predetermined current value range are obtained. The sensitivity characteristic of the ammeter 123 obtained in this way is
Calibrate based on the given reference current value. Note that the measurement of the electron beam 131 is performed by controlling the sample stage 135 and controlling the electron beam 1.
This is performed by moving the current sensor 136 directly below the current sensor 31 and measuring the output current of the current sensor 136.

The second electron beam lithography apparatus 200 performs the same connection and calibration operation as the first electron beam lithography apparatus 100. For example, the D / A converter 222
When the linearity of is corrected, the drawing control unit 210 turns on the switches 308 and 309 via the identification unit 307.
Then, the linearity is measured by the high-precision voltmeter 306,
The linearity is calibrated based on the result. Similarly, when checking the ammeter 223, the switch 310 is turned on to the reference power supply 305 side. Then, the sensitivity of the ammeter 223 is calibrated by measuring the output current of the reference power supply 305.

FIG. 3 is a block diagram showing a second embodiment of the configuration according to the present invention of the charged beam drawing system of the present invention. In this example, the first electron beam writing apparatus 10
0a and the second electron beam writing apparatus 200a are provided with the same built-in reference devices 310 and 320 as the reference device 300, respectively, and the respective built-in reference devices 310 and 320 are controlled so as to match the reference device 300 at an appropriate frequency. Calibrate. Each of the first electron beam writing apparatus 100a and the second electron beam writing apparatus 200a calibrates various characteristics based on the respective built-in reference devices 310 and 320. Thus, the same effect as that of the system having the configuration shown in FIGS. 1 and 2 can be obtained.

As described above with reference to FIGS. 1 to 3, in the charged beam writing system of the present embodiment, when two electron beam writing apparatuses are installed in the same clean room, each electron beam writing apparatus is used. The reference device required by the device is commonly used. That is, one reference device is used as a reference for two electron beam writing apparatuses. As a result, a writing error between the electron beam writing apparatuses can be reduced, and compatibility can be improved.

That is, in each electron beam writing apparatus, an absolute value error in an ammeter for measuring a beam current, and a temporal change of a reference clock which is a basis of a time during which a beam is irradiated on a wafer or the like (shot time). Characteristics can be matched, a change in the dose condition can be avoided, and an appropriate exposure pattern can be obtained. Therefore, it is not necessary to draw a test pattern periodically and reset the dose condition.

In addition, the linearity variation of the high-accuracy voltmeter itself used to calibrate the linearity of the D / A converter for converting the drawing pattern data into the deflection voltage (current), which has been a conventional problem. Can also deal with. As a result, multiple electron beam lithography systems can be placed in the same clean room to ensure throughput, and can be used in a mix-and-match fashion. This enables efficient pattern circuit lithography built into semiconductor devices. Can be done Further, it is sufficient to provide only one expensive high-precision voltmeter, and the cost of the system can be reduced.

The present invention is not limited to the embodiment described with reference to FIGS. 1 to 3, and can be variously modified without departing from the gist thereof. For example, in this example, the system configuration includes two electron beam writing apparatuses. However, a system configuration including three or four electron beam writing apparatuses according to the production scale may be used. In this example,
The reference device is provided outside the plurality of electron beam writing apparatuses, but may be provided inside any one of the electron beam writing apparatuses.

In this embodiment, an electron beam lithography system is used. However, the invention may be applied to a charged beam lithography system using an ion beam or the like. In this example, a plurality of electron beam lithography apparatuses are arranged in one clean room. However, if the environmental conditions are the same and the maintenance area is the same, each electron beam lithography apparatus is arranged in a separate clean room or the like. You can do it.

[0030]

According to the present invention, various characteristics of a plurality of charged beam drawing apparatuses can be matched, and the wafer and mask can be mixed and matched using a plurality of charged beam drawing apparatuses. Can be drawn,
A highly accurate pattern circuit incorporated in a semiconductor device can be efficiently drawn by a charged beam drawing apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a configuration according to the present invention of a charged beam drawing system according to the present invention.

FIG. 2 is a block diagram showing a detailed configuration example of a charged beam drawing system in FIG. 1;

FIG. 3 is a block diagram showing a second embodiment of the configuration according to the present invention of the charged beam drawing system of the present invention.

[Explanation of symbols]

100, 100a: first electron beam writing apparatus, 20
0,200a: second electron beam writing apparatus, 110,2
10: Drawing control unit, 120, 120a, 220, 220
a: electron beam control unit, 121, 221: shot time control unit, 122, 222: D / A converter, 123, 22
3: ammeter, 130, 230: electron beam mirror, 13
1,231: electron beam, 132,232: blanking deflector, 133,233: deflector, 134,234:
Sample (wafer, mask, etc.), 135, 235: sample stage, 136, 236: current sensor, 300, 300a:
Reference devices, 301 to 303, 308 to 310: switches, 304: reference oscillator, 305: reference power supply, 306:
High-precision voltmeter, 307: identification unit, 310, 320: built-in reference device.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshiyuki Morimura 882 Ma, Hitachinaka-shi, Ibaraki Pref.Hitachi, Ltd.Measurement Equipment Division (72) Inventor Hiroyuki Takahashi 1-280, Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (56) References JP-A-6-216014 (JP, A) JP-A-4-305913 (JP, A) JP-A-3-64195 (JP, A) JP-A-62-7129 (JP, A A) JP-A-63-138732 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 H01J 37/04 H01J 37/305

Claims (2)

(57) [Claims] 1. A same web at a plurality of charged particle beam drawing apparatus
Charged beam drawing method to draw another pattern on top of c
A method, a first charged beam signal from the first shot time control unit
Control the first blanking deflector based on the signal
A first blanking step of turning off the first blanket;
The first charged beam that has undergone on / off control in the charging step
From the first D / A converter with a resolution of 17 bits or more.
Controlling the first deflector according to the voltage to place the
A first deflecting step of deflecting the wafer to a predetermined position, and holding the wafer.
With the first current sensor placed on the first sample stage
A first beam detection for detecting a current of the first charged beam;
Process and transmitting the second charged beam from the second shot time control unit.
Control the second blanking deflector based on the signal
Turning off a second blanking step;
The second charged beam that has undergone on / off control in the charging step
From the second D / A converter with a resolution of 17 bits or more.
A second deflector is controlled according to the voltage so that
A second deflecting step of deflecting the wafer to a predetermined position, and holding the wafer.
With a second current sensor placed on a second sample stage
A second beam detection for detecting a current of the second charged beam;
Step, the first shot time control unit and the second shot time
A first calibration step of calibrating the interval control unit, and a step of calibrating the first D / A converter and the second D / A converter.
Correcting the output of the first D / A converter in the second calibration step of correcting and in the first calibration step.
Voltmeter or ammeter to measure with a barometer or ammeter
A first switch for connecting an ammeter to the first DA converter
And the output of the second DA converter in the first calibration step.
If the voltmeter is to be measured with a voltmeter or ammeter,
Or a second switch for connecting an ammeter to the second DA converter.
And after the first calibration step and the second calibration step,
The wafer is placed on a first sample stage and a first
A first drawing step of drawing a pattern, the first drawing Engineering
After that, the wafer is placed on the second sample stage and
A second drawing step of drawing a second pattern on
Charged beam lithography wherein the that. 2. The same wafer is used by a plurality of charged beam writing apparatuses.
What is claimed is: 1. A charged beam writing system for writing another pattern by overlaying it on a first blanket, wherein the first blankin controls on / off of a first charged beam.
On / off control with the first and second blanking deflectors
Controlled first charged beam on the wafer
A first deflector deflecting to a position and holding the wafer
Drives the first sample stage and the first blanking deflector
A first shot time control unit that performs
Driving voltage or current of 17 bits or more
First D / A converter with resolution and placed on the first sample stage
First current sensor and second blankin for controlling on / off of a second charged beam
On / off control by the deflecting plate and the second blanking deflecting plate.
Controlled second charged beam on the wafer
A second deflector deflecting to a position and holding the wafer
Drives the second sample stage and the second blanking deflector
A second shot time control unit that performs
Driving voltage or current of 17 bits or more
A second D / A converter with resolution and placed on the second sample stage
Calibration of the second current sensor, the first D / A converter, and the second D / A converter
A voltmeter or ammeter to be used and the voltmeter or ammeter output to the first DA converter
A first changeover switch connected for measurement and the voltmeter or ammeter output to the second DA converter.
A second changeover switch unit connected for force measurement, and a first current measuring the current from the first current sensor
Meter and a second current measuring the current from the second current sensor
And a base used for calibration of the first ammeter and the second ammeter.
A charged beam drawing system comprising a quasi power supply .