JPH065504A - Apparatus and method for applying focused beam - Google Patents

Abstract

PURPOSE:To furnish an apparatus and a method for applying a focused beam which enable checking of the reliability of an application pattern of the focused beam by a simple technique. CONSTITUTION:On the occasion when a desired wiring pattern is formed by applying a beam spot to a resist on a semiconductor wafer 1, an apparatus 100 for applying an electron beam determines the shape/dimension (size) of the beam spot at random for each position of application of the beam spot executed intermittently, by control means 33 to 35 thereof. An application sequence determining means 36 determines the sequence of application of the beam spot of which the shape/dimension is determined, to the discrete positions of application, on the basis of a prescribed random function. According to this sequence, a pattern transfer device makes a shot of the beam. By a plotting method using this apparatus, the wiring pattern of TEG for diagnosis of short- circuit/opening is formed on the semiconductor wafer 1, and by executing continuity inspection of this wiring pattern, the reliability of a plotting apparatus can be inspected simply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor technology, and more particularly to a technology effective when applied to a pattern forming technology of a semiconductor integrated circuit using a focused beam such as an electron beam, and in particular, inspection of reliability of the focused beam device. The present invention relates to a technique useful for creating a diagnostic pattern for performing.

[0002]

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

In particular, an integrated circuit pattern is formed by irradiating a semiconductor wafer coated with an electron beam resist with an electron beam.
The electron beam drawing technology for drawing (exposure) directly on the resist is capable of forming a finer integrated circuit pattern than the conventional light exposure technology by transfer using a photomask, and the processing is performed at high speed. Are better. In the processing technique using such a focused beam, the cross-sectional shape, size (size), irradiation position, etc. of the focused beam to be irradiated are computer-controlled and irradiated based on the design data (drawing data) of the integrated circuit, Therefore, the desired drawing pattern is accurately achieved.

In this direct writing method using a focused beam, the focused beam is stabilized while writing a pattern on the resist, that is, at a desired position, a desired size, and a desired dose amount. It is necessary to irradiate for a predetermined time. Further, since the beam is intermittently irradiated to form a pattern in which the irradiation spots by the beam spot are continuous, it is necessary to perform the positioning of the beam spot with high accuracy so that the irradiation trace is not interrupted. Even in this case, stable irradiation must be performed over a long period of time. For example, when an LSI design pattern of about 100 K gate is formed on a resist by using an electron beam drawing technique, irradiation of a beam is performed more than 10 ⁷ times per chip. Then, during this shot, if an error such as size, irradiation position, and irradiation amount occurs in the beam even only once, the desired drawing pattern cannot be obtained, and the circuit in the manufactured product LSI is not obtained. Defects will occur.

The cause of such an error is that when electrical noise or surge occurs during the drawing process and the drawing apparatus malfunctions, when a specific irradiation position data is input, it is displayed on a computer program. It is conceivable that a defect may cause accidental drawing at an incorrect irradiation position. Therefore, when actually manufacturing an LSI, an inspection is performed for each drawing process as to whether or not a defect or pattern abnormality has occurred in the drawing pattern using a focused beam.
As a result, the reliability of the wiring pattern of the product LSI is maintained.

As an example of this inspection method, for example, a wiring layer and a resist are formed on an inspection mask substrate made of quartz, a pattern of a semiconductor integrated circuit is drawn on the resist, and the wiring of the drawing pattern is masked. Formed on the substrate,
There are methods such as comparing and collating this wiring pattern with design data which is the basis of pattern formation, and checking the gap between the actually formed adjacent patterns.

There is also a method of detecting abnormalities that may occur during conversion processing of pattern data formed by adding various checking programs to the computer itself of the drawing apparatus.

[0008]

However, in the method of comparing and collating the actually formed circuit pattern with the design pattern, the circuit pattern is formed by applying light to the circuit pattern and reading the reflected light. Since the recognized shape is recognized and the recognized data is compared with the design pattern data, the time required for the pattern inspection is about 10 times as long as the drawing time, which is an advantage of the electron beam drawing process. Is shortened. In addition, a separate inspection device is required, which leads to an increase in cost. Further, in the inspection method using the computer program, in order to inspect the drawing pattern data converted by the ultra-high-speed format conversion for drawing processing, it is necessary to match the ultra-high-speed computer processing. Ultra-high-speed check is required, and it is difficult to actually give a check function to a computer program.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a focused beam irradiation apparatus and an irradiation method capable of checking the reliability of a focused beam irradiation pattern by a simple method. . Regarding the above and other objects and novel features of the present invention,
It will be apparent from the description of this specification and the accompanying drawings.

[0010]

The typical ones of the inventions disclosed in the present application will be outlined below. That is, in intermittently irradiating a large number of beam spots on a sample, the shape, size, and irradiation position are randomly determined for each beam spot irradiated at one time,
Furthermore, the order of irradiation to the large number of irradiation positions is determined according to a random function.

[0011]

According to the above-mentioned means, a large control load can be intentionally added to the focused beam irradiation device when a wiring pattern of a diagnostic TEG is formed at a predetermined position on a semiconductor wafer, and a load is applied. The reliability of the pattern obtained by the irradiation can be inspected by inspecting a disconnection / short circuit of the TEG wiring pattern obtained in this state with a commercially available probe tester or the like.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the overall configuration of an electron beam drawing apparatus (focused beam irradiation apparatus) 100 of the present embodiment, and FIG. 2 is a perspective view showing a main part of a pattern transfer apparatus out of the drawing apparatus 100, FIG. 3 is a flow chart showing a wiring pattern forming process by the drawing apparatus. Incidentally, the electron beam drawing apparatus 10 applied in the present embodiment
Reference numeral 0 is a variable shaping type electron beam drawing apparatus capable of appropriately adjusting the shape and size of the beam spot.

A drawing apparatus 100 will be described below with reference to FIGS. 1 and 2.
The configuration of will be described. In this electron beam drawing apparatus, based on predetermined drawing data (wiring pattern), a wiring pattern of a product LSI and a wiring pattern for diagnosing the operation accuracy of the drawing apparatus (diagnostic for wiring) are formed on the semiconductor wafer 1. The wiring pattern of TEG (test element group) is formed in the same process. In this case, in drawing the wiring pattern of the product LSI, the control load on the electron beam drawing apparatus is made as small as possible (the control is simplified) so that the drawing pattern does not have an error that causes a disconnection or a short circuit. For example, the beam spots to be irradiated have the same shape, and the beam spots are sequentially irradiated so as to be continuously connected so that the moving width thereof becomes small.

On the other hand, in the drawing of the wiring pattern of the diagnostic TEG, the control load applied to the drawing apparatus is made as large as possible (control is complicated), and the wiring pattern is intentionally liable to be broken or short-circuited. . Therefore, the wiring pattern formed under such a large control load is inspected for disconnection / short circuit. If no error such as disconnection / short circuit occurs in the wiring pattern, the product LSI drawn with a small load is drawn. It can be determined that no error has occurred in the wiring pattern.

The procedure of drawing the wiring pattern of the diagnostic TEG among the wiring patterns formed on the semiconductor wafer 1 will be described below. As shown in FIG. 1, drawing data representing the wiring pattern is sent from the drawing data storage unit 31 to the drawing shape control unit 32, and the shape and size of the wiring pattern are recognized. The control unit 32 sends the recognized data to the beam shape determining unit 33 and the beam size determining unit 34 as the form determining unit, and further to the irradiation position determining unit 35, and these units generate a beam spot of any shape and size. , How to arrange the wiring patterns is determined. In this case, for example, if the shape of the beam spot is determined in advance, the data is sent to the beam dimension determining means 34 together with the data regarding the wiring pattern via the drawing shape control portion 32, and the determining means 34 applies the data. Determine the size of the beam spot. Then, the determined dimension data is returned to the drawing shape control unit 32 and sent from the control unit 32 to the irradiation position determining means 35, which means 35 determines the irradiation position of the beam spot based on these dimension data and shape data. To decide. The data on the shape, size, and irradiation position of the beam spot determined by the respective determining means 33, 34, and 35 are all sent to the irradiation operation determining means 37.

Further, the drawing shape control unit 32 determines the irradiation order of the beam spots of the shapes / dimensions determined for each irradiation position according to the random numbers generated by the built-in random function means (not shown). Deciding means 36
Are connected. The data representing the irradiation order determined for each irradiation position by the irradiation order determination means 36 is
It is adapted to be sent to the irradiation operation determining means 37.

The irradiation operation determining means 37 determines the shape / dimension of the beam spot for each irradiation of the pattern transfer device based on each data sent from each of the determining means.
By recognizing the irradiation position, data representing the shape / dimension of the beam spot to be irradiated this time is sent to the shaping device control unit 40, and data representing the irradiation position is sent to the rotary lens control unit 41 and the deflection control unit 42. As a result, the electron beam 4 emitted from the electron gun 3 is adjusted into a predetermined shape / dimension by the shaper 20 to form a beam spot having a predetermined shape, and thereafter, by the action of the rotating lens 11a, the deflectors 8 and 13, and the like. The beam spot is irradiated onto a predetermined irradiation position of the semiconductor wafer 1 mounted on the upper surface of the sample table 2. still,
The objective lens 21 shown in FIG.
Is controlled by the function of the sample table 2 and the sample table 2 is composed of an XY stage.
It is designed to be step-moved in the Y direction.

The main part of the pattern transfer device of the electron beam drawing device for carrying out the drawing process according to the above procedure has the structure shown in FIG. That is, a semiconductor wafer (sample) 1 having a surface coated with an electron beam sensitive resist is mounted on a sample table 2 composed of an XY stage movable in a horizontal plane. Then, on the semiconductor wafer 1 mounted on the sample table 2,
The electron beam 4 emitted from the electron gun 3 is irradiated onto a predetermined position of the wafer after being converted into a desired form.

Specifically, in the path from the electron gun 3 to the sample stage 2, 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. Electron beam 4 focused by 6
The first mask 7 having a rectangular opening pattern 7a formed therein, the deflector 8 and the beam shaping lens 9, and the second mask 1 having a rectangular opening pattern 10a formed therethrough.
0, a reduction lens 11 that reduces the cross-sectional shape of the electron beam 4 that has passed through the second mask 10, and a projection lens 1 that focuses the electron beam 4 on the semiconductor wafer 1.
2. An electron optical system including a position deflector 13 for controlling the irradiation position of the electron beam 4 on the semiconductor wafer 1 is provided. Then, the electron beam 4 generated from the electron gun 3 is shaped by passing through the above-mentioned two masks to form a beam spot having a rectangular cross section. The beam spot thus formed is further reduced by the reduction lens 11, the rotation lens 11a, the projection lens 12, and the position deflector 13 so that the focus position is adjusted,
Moreover, the irradiation position is controlled. still,
The irradiation lens 6, the first mask 7, the beam shaping lens 9, the second mask 10, the reduction lens 11 and the like function as the shaping device 20 shown in FIG.

Next, a wiring pattern forming method using the electron beam drawing apparatus and an inspection method using the diagnostic TEG will be described according to the flow shown in FIG.
In this flow, only the procedure for drawing the wiring pattern of the diagnostic TEG will be described. However, in the actual drawing process, the shape / dimension / irradiation position / irradiation order of the beam shot used for forming the wiring pattern is determined. The shape of the beam shot of the wiring pattern of the product LSI is determined separately by different processing, and the beam irradiation is performed by one diagnostic TE.
The G wiring pattern and the wiring pattern of one product LSI are alternately arranged. In this case, product L
When drawing a wiring pattern of SI, the control load on the drawing apparatus is reduced, and drawing of the wiring pattern of the diagnostic TEG is performed with a large control load. As shown in this flow, first, by performing the respective steps 01 to 03 of the block A, the product LSI of the semiconductor wafer 1 is previously manufactured.
A semiconductor element is formed in the region where the
1) Then, a conductive film such as an aluminum thin film is formed on the entire surface of the semiconductor wafer 1 (step 02), and an electron sensitive resist is applied to the upper surface of this conductive film (step 0).
3).

On the other hand, steps 04 to 08 of block B
By executing the above, the wiring pattern drawn by the electron beam drawing apparatus is determined (step 04), the size of the beam spot for each shot of the beam used for this drawing is determined (step 05), and the shape of the beam spot is determined. Determination (step 06), determination of irradiation position of the beam spot having the determined size / shape (step 07),
The irradiation order of the beam spots determined for each irradiation position is determined (step 08).

As described above, the process up to immediately before the process of forming the wiring pattern of the semiconductor wafer 1 is performed in the block A, and each control parameter (size, shape, etc.) for drawing the wiring pattern of the diagnostic TEG is processed in the block B. When the determination is made, the process proceeds to block C, where the semiconductor wafer 1 on the sample table 2 is actually irradiated with the beam spot, and the wiring pattern of the diagnostic TEG is drawn. This drawing process is performed according to the control parameter determined in the block B, and the irradiation of the beam spot is performed in the irradiation order determined according to the random function (step 09).

When the electron beam resist on the wafer is irradiated with the beam spot in this manner, the resist is then developed (step 10), the conductive film is etched using the developed resist (step 11), and the resist is removed. The removal (step 12) is sequentially performed, whereby the wiring pattern of the diagnostic TEG is formed on the semiconductor wafer. Since the wiring pattern formed in this way is obtained with a relatively large control load applied to the drawing apparatus as described above, if there is no abnormality in this wiring pattern, the wiring pattern of the product LSI It can be considered that no abnormality has occurred. In order to confirm this, in the next step 13, a probe test using the wiring pattern of the diagnostic TEG is performed. Further, the next step 14
Then, a visual inspection is performed. This is because the abnormalities that can be detected by the above-mentioned inspection include defects in the exposure, development, and etching processing processes due to foreign matter adhering to the sample, as well as shot abnormalities in the drawing device, and process processing conditions. This is because there is a variation due to variations, and this appearance inspection determines shot abnormalities in the drawing apparatus, excluding abnormalities due to the above-mentioned foreign matter, variations in process processing conditions, and the like (step 15).

As mentioned above, the diagnostic TEG is
The wiring pattern of the diagnostic TEG is provided on the same semiconductor wafer as the product LSI, and is formed in the same processing step using the same drawing device as the wiring pattern of the product LSI. By thus forming the wiring pattern of the diagnostic TEG on the same semiconductor wafer in the same process, the diagnostic TE can be manufactured under the same conditions as the product LSI.
The G wiring pattern is formed, and the reliability of the diagnosis result is improved.

Next, a procedure for determining the size, shape, irradiation position, irradiation order, etc. of the beam spot using a random function when drawing the wiring pattern of the diagnostic TEG will be described. FIG. 4 is a plan view showing a wiring pattern of a typical diagnostic TEG (open defect diagnostic TEG). In this wiring pattern, one elongated metal wiring (aluminum wiring) is formed in a woven shape. Therefore, when a beam miss-shot occurs in forming this wiring pattern, a shot omission appears and a disconnection occurs immediately. Therefore, the probe test causes the conductive test terminals (pads) A and (pads). By applying a voltage to B and checking the resistance value, an abnormality in the wiring pattern can be detected.

In forming this wiring pattern, first, the drawing data of the electrode pads A and B for probe inspection and the relay wirings C _{1 to} C ₆ for conductively connecting the respective wiring rows l ₁ to ₁₇ are formed. The drawing data and fixed data are set in advance. Then, drawing data for forming each wiring array l ₁ to l ₆ (size of the beam spot, the shape, the irradiation position) is determined at random, then further randomly determines the irradiation order of each beam spot.

In order to simplify the description, a procedure for determining drawing data for forming only the uppermost wiring line l ₁ in FIG. 4 will be described below. Now, temporarily change the length of the wiring line l ₁ to “7
Consider a method for determining the drawing pattern when the width is "0" and the width is "1". In order to simplify the description, the shape / dimensions of the beam spots are, as shown in FIG. 5, five patterns (1) having the same width “1” and lengths “1” to “5”.
~ (5) will be randomly selected.

The program shown in FIG. 6 is used to determine the drawing pattern of the wiring line l ₁ by combining these five patterns. That is, in FIG. 6, random numbers “0” to “4” are appropriately determined, and the random number values are made to correspond to the five shot patterns (1) to (5), respectively. Is a PAD (problem analysis diagram) in which the programs that are sequentially applied to the sequence of
The array shown in FIG. 7 schematically represents the shot pattern of the wiring line l ₁ .

When this program is started, the array is declared and then the initial values (N ₁ , N ₂ ) of the random numbers are read, and random numbers 0 to 9 are generated based on these initial values. Is generated. Then, the generated random number is further divided by 5 from “0” to “4”.
5 is converted into one random number, and the shapes of the beam spots corresponding to the random numbers "0" to "4" are shown in FIG.
It is appropriately selected from the pattern of (5).

As described above, the beam spots selected based on the generated random numbers are sequentially incorporated into the 70 array patterns schematically shown in FIG. The total length of the beam spots thus randomly determined is the sum of the identification numbers (1) to (5). When this sum exceeds the length 70, the difference between the total sum immediately before exceeding the length and the length 70 is automatically determined from the patterns (1) to (5) so as to be the length of the last beam spot. Pattern is selected (the length of the last beam spot is “2” in the example of FIG. 7).

The arrangement pattern of the beam spots of the wiring line l ₁ thus determined is the same notation as in the schematic diagram of FIG. 7 by executing the latter half program shown in FIG.
It is printed out so that it is possible to confirm what shape / dimension of the beam spot combination was used to draw the wiring pattern.

When the size / shape of the beam spot is determined for each irradiation position in this manner, a program process (not shown) is performed for each irradiation position according to a random function.
The irradiation order is determined. Then, the electron beam drawing apparatus draws the wiring pattern of the diagnostic TEG under a high control load according to the drawing data thus determined.

FIG. 8 is a plan view showing a wiring pattern of the TEG for short-circuit defect diagnosis, which is drawn by the electron beam drawing apparatus having the above structure. This wiring pattern comprises a pair of conductive test terminals C and D, and a pair of opposing comb-shaped wiring patterns E and F connected to the terminals C and D, respectively. When also forming the wiring pattern, the order of occurrence of the shot, for example, after the i-th irradiation to e ₁ position, the irradiation position in the degree referred to perform than distant e ₂ located in the (i + 1) -th irradiation this It is decided at random. A pair of opposing comb-shaped wiring patterns obtained by drawing on the resist in accordance with this pattern data, developing the resist, and etching the conductive film are used for the electrical connection between the pads C and D. By measuring the resistance, it is possible to diagnose whether or not there is an abnormality in the drawing device. According to this method, it is easy to connect the comb-shaped patterns in which the shot errors (shifts of the shot positions) are meshed with each other, so that the shot errors are patterned.
It becomes a short cut and is efficiently detected. In addition, by combining the short-circuit defect diagnosing TEG (FIG. 8) and the above-described open defect diagnosing TEG (FIG. 4) on the same semiconductor wafer, and performing the inspection, the shot omission can be prevented.
Abnormality of shot position shift can be detected efficiently.

The invention made by the present inventor has been specifically described based on the embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in the present embodiment, the size and the turning position of the beam spot by the drawing device are limited for the convenience of computer processing. However, this processing algorithm is used for the actual pattern.
It can be easily expanded to correspond to the pattern generation of the pattern writing device. Further, in the above-described embodiment, the wiring pattern of the diagnostic TEG is formed in the state where the control load is increased, and the reliability of the drawing device is inspected by the probe inspection for the abnormality of the wiring pattern using this TEG. In determining the property, the reliability of the drawing apparatus may be determined by comparing the wiring pattern with a large control load with the wiring pattern drawn with a small control load. Further, in this embodiment, the exposure pattern of the resist of the semiconductor wafer has been described as the pattern to be drawn, but it may be applied to other general processing techniques. In the above description, an example in which the invention made by the present inventor is mainly applied to an electron beam drawing apparatus which is a field of application as the background has been described, but other electron optical systems, for example, focusing of a laser beam, an ion beam, etc. The present invention can be applied to a beam generator in general.

[0035]

The effects obtained by the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, according to the present invention, it is possible to confirm whether or not the beam spot is accurately irradiated, that is, the reliability of the drawing apparatus, by a simple method.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an electron beam drawing apparatus of this embodiment.

FIG. 2 is a perspective view showing a main part of a pattern transfer device of the electron beam drawing device.

FIG. 3 is a flowchart showing a TEG wiring pattern forming process using an electron beam drawing apparatus.

FIG. 4 is a plan view showing a wiring pattern of an open defect diagnosing TEG.

FIG. 5: Shape of beam spot used in this embodiment /
It is explanatory drawing which shows a dimension (size).

FIG. 6 is a PAD showing a program for selecting five shot patterns (1) to (5) corresponding to a random number value and determining a drawing pattern by a beam of the wiring line l ₁ .

FIG. 7 is an explanatory diagram schematically showing a state in which shot patterns selected by the program are arranged in order and a wiring line l ₁ is drawn.

FIG. 8 is a plan view showing a wiring pattern of a TEG for short circuit defect diagnosis.

[Explanation of symbols]

 1 Semiconductor Wafer (Sample) 3 Electron Gun 8, 13 Deflector 20 Molder 11a Rotating Lens 33 Beam Shape Determining Means (Form Determining Means) 34 Beam Dimension Determining Means (Form Determining Means) 35 Irradiation Position Determining Means 36 Irradiation Sequence Determining Means 37 Irradiation operation determining means 100 Electron beam drawing device (focused beam irradiation device)

Claims (3)

[Claims] 1. A focused beam irradiation apparatus comprising irradiation control means for irradiating a desired position on a sample with a beam spot in a predetermined form, wherein the irradiation control means is provided with at least one of the shape and size of the beam spot. Form determining means for determining, irradiation position determining means for determining the irradiation position of the beam spot, and irradiation order of the beam spot having a predetermined shape and size determined for each beam spot to the irradiation position is predetermined. A focused beam drawing apparatus comprising: an irradiation order determining unit that determines an irradiation order based on a random function. 2. When irradiating a pattern of a predetermined shape on a sample with a focused beam, the shape and / or the size of each shot of a plurality of beam spots is determined, and the beam spot is irradiated. Determine the position to be
An irradiation method of a focused beam, wherein an irradiation order of beam spots to the irradiation position is randomly determined, and irradiation of the focused beam is executed according to the order. 3. The pattern irradiated by the focused beam according to claim 1 or 2 is an exposure pattern of a resist formed on a wafer, and the wafer is diagnosed by etching using the exposure pattern. An irradiation method using a focused beam, characterized in that a wiring pattern is formed.