JP4877959B2 - Electron beam exposure data creation method, electron beam exposure method, semiconductor device manufacturing method, and electron beam exposure apparatus - Google Patents

Description

  The present invention relates to an electron beam exposure data creation method, an electron beam exposure method, a semiconductor device manufacturing method, and an electron beam drawing apparatus, and more particularly, a field connection technique for improving a process margin and a manufacturing yield. The present invention relates to an electron beam exposure data creation method, an electron beam exposure method, a semiconductor device manufacturing method, and an electron beam exposure apparatus.

  In electron beam drawing, electrons are deflected by a deflector and drawn at an arbitrary position on the wafer with high accuracy. However, the range in which electrons can be deflected by this deflector is limited and varies depending on the type of deflector, but since it is from several tens of μm □ to several mm □, the entire LSI chip is around 20 mm □. Is drawn by connecting the deflection ranges (fields).

  That is, when it is desired to draw an area outside the deflection range, the wafer position is moved by moving the wafer stage, and the drawing is carried out within a range that can be covered by the deflector of the exposure apparatus.

In addition, in a normal electron beam drawing apparatus, there is a case where not only one deflector but a main deflector that can cover a wide range and a sub-deflector that can draw accurately and quickly in a small range are used in combination. In many cases, the process of joining the deflection ranges of the small sub-deflectors with the main deflector having a large deflection range is also added. Here, referring to FIG. A drawing method will be described.
Here, for the sake of simplicity, all the connections between these deflection regions are called field connections.

See FIG.
Figure 7 is an explanatory view of an electron beam lithography method, approximate location on the wafer 44 with the electron beam 41 by the main deflector 42 which can cover a wide range as shown in the left diagram, i.e., the predetermined main field 46 ₁ The sub-field 47 _{1 is} then deflected to the sub-field 47 ₁ , and then the inside of the predetermined sub-field 47 ₁ is drawn with the electron beam 41 by the sub-deflector 43 capable of drawing with high accuracy and high speed within a small range.

Next, as shown in the right figure, when the drawing in the predetermined subfield 47 ₁ is finished, the electron beam 41 is deflected to the adjacent subfield 47 ₂ by the main deflector 42 and again by the sub deflector 43. a subfield 47 in ₂ drawing an electron beam 41.

When this process is sequentially repeated by all the rendering sub-field 47 in the main field 46 ₁ ends, in turn, becomes the main field 46 ₂ the deflection region of the main deflector 42 to move the wafer stage 45 is adjacent In this way, drawing is again performed by the sub deflector 43.

  When LSI pattern data is actually drawn with such a device configuration, data is divided into fields determined in advance by the specifications of the device, and drawing is performed for each divided data. The situation will be described with reference to FIG.

See FIG.
FIG. 8 is an explanatory diagram of a field dividing method, and the upper diagram is an explanatory diagram of an example of a drawing pattern. Here, two rectangular patterns 56 and 57 are opposed to each other via a space 58 and one rectangular shape is illustrated. A case where the pattern 57 is divided by two subfields 51 and 52 is shown.

Further, a certain range from the field boundary 53 of the two subfields 51 and 52 is provided as “margin” as the field margin areas 54 and 55.
That is, even if it is a deflection area, it is often used in a range where there is still a margin in the deflection range of the deflector, and the deflection area can be expanded to some extent, which is called a field margin. Generally, the width is about several μm.

Here, as shown in the middle diagram, if field division is performed at the field boundary 53 without considering the division location, there arises a problem that the number of shots increases or a very small pattern is generated.
That is, in the subfield 51, draws the rectangular pattern 56 and the divided rectangular patterns 57 ₁ and have subfield 52 should be drawn other divided rectangular patterns 57 ₂ occurs.

  In addition, the connection accuracy of field connection generally deteriorates more than the connection accuracy of each shot in the deflection region, and is the performance of the drawing apparatus itself. If the data is sufficiently large, there is no major problem where the data is divided, but as the miniaturization progresses, the proportion of the device-specific connection accuracy occupies the pattern dimensions and pitch, and the data exists where the pattern exists. If the pattern is divided, there is a problem that the pattern dimension changes at the time of drawing.

  Here, when a pattern exists in the field boundary 53 as shown in the middle diagram, a method is proposed in which the pattern is not divided as much as possible using the field margin regions 54 and 55 as shown in the lower diagram ( For example, see Patent Document 1).

In this case, when the data is divided, the field is divided so that the pattern is absorbed as much as possible in the field margin areas 54 and 55 so that the pattern is not divided.
That is, the process recognizes the presence of a pattern and takes the pattern into its own field area as much as possible.
In this case, the moved boundary 59 becomes a substantial field boundary.
Japanese Unexamined Patent Publication No. 01-297823

  In the case of a gate layer that occupies a relatively small pattern area, there are few problems with the above method, but in the case of a layer with a pattern density exceeding 50%, such as an LSI wiring layer, the pattern existing region In some cases, there are many patterns in which a portion without a pattern is narrow.

In recent years, this tendency is particularly noticeable especially in the damascene method, which is frequently used in LSI wiring layers, etc., but when there is a space near the resolution limit sandwiched between relatively large patterns, If the field is divided by this rule, the field is divided at the corresponding space part avoiding the pattern part. Therefore, the space part may be drawn smaller than the design value due to the field connection accuracy during actual drawing. Since there is a possibility that the process margin is reduced or the worst case is short-circuited, the situation will be described with reference to FIG.
In the case of a relatively large pattern, besides the field connection accuracy, the space is not formed with a predetermined width due to the influence of back scattering, and defects such as a short circuit are likely to occur.

See FIG.
FIG. 9 is an explanatory diagram of problems in the conventional field division method. The upper diagram shows two rectangular patterns 66 and 67 facing each other through a space 68 near the resolution limit, and one of the rectangular patterns. A case where the pattern 67 is divided by two subfields 61 and 62 is shown.

  In this case, even when the space 68 comes to the field boundary near the small space without the process margin between the minimum design space and the large pattern, the field boundary 63 is changed to the space 68 as shown in the middle diagram. It moves and splits as a boundary 69.

Therefore, as shown in the lower diagram, there is a problem that the space portion 70 is narrowed due to the field connection accuracy, the process margin is reduced, and in the worst case, a short circuit occurs.
On the contrary, if a field is generated as it is in order to avoid it, there is a problem that the pattern is divided below the minimum pattern as shown in the middle diagram of FIG.

  Therefore, an object of the present invention is to improve the process margin associated with field connection and improve the manufacturing yield.

FIG. 1 is a diagram illustrating the basic configuration of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
Refer to FIG. 1. In order to solve the above-described problem, the present invention is a method for dividing data for each field of a deflector when converting design data into electron beam exposure data, and determines a field boundary 4. At this time, for the field boundary 4 and the patterns 1 and 2 closest to the field boundary 4 or the patterns 1 and 2 divided by the field boundary 4 and the space 3 adjacent thereto, a determination table consisting of the pattern size and the space size is created. Only when the determination criteria of this table are satisfied, field division is performed at the corresponding location, and when the determination criteria are not satisfied, the field boundary 4 is shifted within the field margin, and field division is performed where the determination criteria are satisfied. To do.

  By adopting such a configuration, it becomes possible to divide the field where the process margin can be taken within the variable range of the field boundary 4 in the field division determination performed by the presence or absence of the patterns 1 and 2. It is possible to improve the manufacturing margin by improving the process margin associated with the field connection.

  In this case, in creating the determination table, a table is created for each type of resist used in drawing and the performance of the deflector, and a table corresponding to the type of resist actually used and the deflector is selected and divided into fields. good.

  In addition, when changing the field position, it is desirable to set in advance an additional condition related to position movement different from the determination table, and to move the field position according to a predetermined rule. It is possible to prevent the process margin from being unavoidable and the occurrence of a short circuit.

  As a field division method in this case, a field division method in which a deflector is a sub-deflector and a field to be divided is a sub-field is a typical method. It can also be applied to the division method.

  Further, by performing exposure using the electron beam exposure data created by the above-described electron beam exposure data creation method, it is possible to perform electron beam drawing with little decrease in process margin and no occurrence of short circuit.

  In addition, an electron beam drawing apparatus capable of drawing an electron beam with less process margin reduction and no short-circuiting is realized by providing a function for creating electron beam exposure data by the above-described electron beam exposure data creation method. can do.

  According to the present invention, it is possible to divide a field where a process margin can be obtained within the variable range of the field boundary in the determination of field division, thereby improving the process margin associated with field connection and improving the manufacturing yield. It becomes possible.

  In the present invention, when data is divided for each field of a deflector when converting design data into electron beam exposure data, the field boundary is determined by determining the field boundary and the closest pattern or field boundary. Create a judgment table consisting of the pattern size and space size for the pattern to be divided and the space adjacent to it, and perform field division at the relevant location only when the judgment criteria of this table are satisfied, and the judgment criteria are satisfied. If not, the field boundary is shifted within the field margin, and field division is performed where the determination criterion is satisfied.

Here, with reference to FIG. 2 thru | or FIG. 6, the preparation method of the data for electron beam exposure of Example 1 of this invention is demonstrated.
See FIG. 2 and FIG.
FIG. 2 is an explanatory diagram of a determination table used in the electron beam exposure data creation method according to the first embodiment of the present invention. In this case, FIG. 2 is an example of a determination table for a 0.13 μm design rule. 3 is an explanatory diagram of a space size and a pattern size in the determination table, and the pattern size in the determination table means the size of one pattern closest to the field boundary.

As shown in FIG. 2, when the space size d is less than 0.2 μm, field division is performed inside the pattern when the pattern size L is 0.2 μm or more.
When the space size d is 0.2 μm ≦ d <0.4 μm, when the pattern size L is less than 0.4 μm, the field is divided in the space, and the pattern size L is 0.4 μm or more. First, the field is divided in the pattern.
When the space size d is 0.4 μm or more, all fields are divided within the space d.
Note that, in the 0.13 μm design rule, the space size d and the pattern size L are both designed to be less than 0.2 μm. Therefore, in FIG. When it is less than 2 μm, it is NG.

In addition, as a rule other than the determination table, two additional conditions regarding the division size are set. First, as additional condition 1,
L ₁ , L ₂ > 0.05 μm (= 50 nm)
And prohibiting the division when at least one of the division sizes is 0.05 μm.
Further, as an additional condition 2, | L ₁ −L ₂ | is determined to be the smallest within the field margin, and is set so that the size of the two divided patterns is as large as possible.

See Figure 4
FIG. 4 is a flowchart of a method for creating electron beam exposure data according to the first embodiment of the present invention.
A. Generate a field boundary based on the deflection performance of the deflector for the design data,
B. If the field boundary does not satisfy the condition of the determination table shown in FIG. 3, the position of the field boundary is changed until the condition of the determination table is satisfied by changing the position of the field boundary.

C. If the field boundary meets the conditions of the judgment table, proceed to judgment of additional conditions,
D. It is determined whether or not the additional condition is satisfied. If the additional condition is not satisfied, the position of the field boundary is changed until the condition of the determination table and the additional condition are satisfied.

E. If the field boundary satisfies the additional conditions, field division is performed at the field boundary,
F. By determining field division for all fields, electron beam exposure data is created.
Thereafter, the exposure on the wafer is performed by deflecting the electron beam based on the electron beam exposure data thus created.

See Figure 5
FIG. 5 is an explanatory diagram of an example of a method of creating electron beam exposure data according to the first embodiment of the present invention. Here, as shown in the upper diagram, large patterns 16 and 17 having a length L of 2 μm are zero. This shows a case where the space 18 is less than 2 μm, that is, facing through the minimum space set in the determination table.

In this case, it is assumed that the field boundary 13 between the subfield 11 and the subfield 12 covers the large pattern 17 so that L ₁ = 0.02 μm.
Reference numerals 14 and 15 denote field margin areas of the subfields 11 and 12, respectively.

In this case, in this state, the space d <0.2 μm and the pattern L = 2 μm. However, since the conditions of L ₁ and L ₂ > 0.05 μm of the additional condition 1 are not satisfied, the field boundary 13 needs to be moved. There is.

Therefore, as shown in the middle diagram, when the field boundary 13 is moved to the space 18 as in the conventional method, in the determination table,
Space (<0.2 μm) & Pattern (≧ 0.6 μm) = p
Since this condition is not satisfied, such field division is prohibited.

Therefore, as shown in the lower diagram,
Space (<0.2 μm) & Pattern (≧ 0.6 μm) = p
The field boundary 13 is moved within the field margin area 15 so as to divide the large pattern 17 so as to satisfy the above condition.
However, in this case, division is performed so that | L ₁ −L ₂ | is minimized within the field margin region 15 so as to satisfy the additional condition 2.

See FIG.
FIG. 6 is an explanatory diagram of the effect of the present invention. For example, assuming that the margin allowed for the process of the minimum space portion is 12 nm, as shown in the upper diagram, the field connection accuracy varies in a normal distribution. It is assumed that the dispersion is σ = 7 nm, and the shot connection accuracy varies in a normal distribution as shown in the figure below, and the dispersion is σ = 2 nm.

  At this time, when the field boundary comes to the minimum space portion, the margin 12 nm is about 1.7σ as shown in the above figure, so about 10% is out of the process margin range and a short circuit occurs.

On the other hand, when the field boundary is set with the minimum space removed, the margin 12 nm is about 6σ as shown in the figure below, and the ratio outside the process margin range is almost close to 0. There is nothing.
Therefore, if a short in the minimum space portion determines the yield, it is possible to expect a yield improvement of about 10% by dividing the field so that the field boundary removes the minimum space.

  The first embodiment of the present invention has been described above, but the present invention is not limited to the configuration, conditions, and numerical values shown in the first embodiment, and various modifications are necessary. For example, the determination table and the additional condition 1 , 2 is based on the 0.13 μm design rule, and is appropriately changed so that a short circuit does not occur when the design rule is further miniaturized.

  In the first embodiment, the pattern sizes are the same for the sake of simplicity, but the patterns 16 and 17 formed on both sides of the space 18 are different in size. If the field boundary can be moved over the pattern, it is determined at which position on which pattern the field boundary is set according to the determination table and the additional conditions.

For example, if one pattern size is 0.3 μm, the other pattern size is 0.5 μm, and the space size is 0.3 μm, the pattern size of 0.3 μm and the space size of 0.3 μm are determined by the determination table, and the space A field boundary is set for the portion. If a pattern size of 0.5 μm and a space size of 0.3 μm are determined by the determination table, a field boundary can be set for the pattern portion.
In this case, the problem of short between patterns can be avoided by setting the field boundary on the pattern of 0.5 μm.

  Even when the design rule is the same, the photosensitivity varies depending on the type of resist used for drawing, and the deflection performance varies depending on the deflector provided in the electron beam drawing apparatus. It is necessary to create a table for each performance and select a table corresponding to the type of resist and deflector actually used.

  In the above embodiment, only the method for creating the electron beam exposure data has been described. However, as the electron beam drawing method, the electron beam exposure data creation method described in the first embodiment is used. The line exposure data is drawn using the sub deflector.

  In addition, as the electron beam drawing apparatus, a program for dividing the electron beam exposure data shown in the first embodiment is stored in the electron beam drawing apparatus, and the design input from the outside in the electron beam drawing apparatus. Data for electron beam exposure may be created from the data, and electron beam drawing may be performed based on the created data for electron beam exposure.

  Further, in the description of the above embodiment, the case where the resist provided on the wafer in the manufacturing process of the semiconductor device is exposed is described. However, the present invention is not limited to the manufacturing process of the semiconductor device. It is also applied to the manufacturing process.

Here, referring to FIG. 1 again, the detailed features of the present invention will be described again.
Again see Figure 1
(Supplementary Note 1) A method of dividing data for each field of a deflector when converting design data into electron beam exposure data, and in determining the field boundary 4, the field boundary 4 is closest to the field boundary 4. For patterns 1 and 2 or patterns 1 and 2 divided by boundary 4 of the field and space 3 adjacent thereto, a determination table consisting of pattern size and space size is created, and the determination criteria of this table are satisfied The electron beam exposure data is characterized in that the field division is performed at the corresponding portion only when the field is determined and the field boundary 4 is shifted within the field margin when the determination standard is not satisfied, and the field is divided at the position satisfying the determination standard. How to make.
(Additional remark 2) It is a method of dividing design data for each field of the electron beam exposure device, and the size of the patterns 1 and 2 to be drawn and the space 3 formed between the pattern 1 and the other pattern 2 A determination table that determines whether the boundary 4 of the field is arranged on the patterns 1 and 2 or the space 3 based on the size of the field, and based on the determination table, And a step of determining the position of the boundary 4 of the field.
(Additional remark 3) The said determination table arrange | positions the said boundary 4 on the said space 3 when the size of the said space 3 is more than a 1st threshold value, The data for electron beam exposure of Additional remark 2 characterized by the above-mentioned How to make.
(Additional remark 4) The said determination table arrange | positions the said boundary 4 on the patterns 1 and 2, when the size of the said space 3 is below the 2nd threshold value smaller than the said 1st threshold value, The additional note characterized by the above-mentioned. 4. The method for creating data for electron beam exposure according to 3.
(Additional remark 5) In preparation of the said determination table, a table is created for every kind of resist used by drawing and the performance of the said deflector, the table corresponding to the kind of resist actually used and a deflector is selected, and it is a field. The electron beam exposure data creation method according to appendix 1, wherein the data is divided.
(Additional remark 6) The said determination table is produced for every kind of resist used by electronic exposure, The data production method for electron beam exposure of any one of Additional remark 2 thru | or 4 characterized by the above-mentioned.
(Supplementary note 7) The electron beam exposure data creation method according to any one of supplementary notes 2 to 5, wherein the determination table is created for each deflector used in electronic exposure.
(Additional remark 8) When changing the said field position, the additional condition regarding position movement different from the said determination table is predetermined, and the said field position is moved by the said predetermined rule, It is characterized by the above-mentioned. The electron beam exposure data creation method according to appendix 1 or 5. (Additional remark 9) When the said boundary 4 is arrange | positioned on the said patterns 1 and 2, the additional condition regarding the width | variety of the 1st division | segmentation pattern produced | generated and divided | segmented by the said boundary 4 and a 2nd division | segmentation pattern is defined. 6. The electron beam exposure data creation method according to any one of appendices 2 to 5, wherein the position of the boundary is moved based on a step and the additional condition.
(Supplementary Note 10) Based on the size of the drawn patterns 1 and 2 and the size of the space 3 formed between the pattern 1 and the other pattern 2, the field boundary 4 is defined on the patterns 1 and 2. Creating a determination table that determines whether to arrange on the space 3, determining the position of the boundary 4 of the field based on the determination table, and determining the position of the boundary 4 A step of dividing the fields 1 and 2 and performing electron beam exposure.
(Supplementary Note 11) Based on the size of the drawn patterns 1 and 2 and the size of the space 3 formed between the pattern 1 and the other pattern 2, the field boundary 4 is defined on the patterns 1 and 2. Or a step of creating a determination table that determines whether to arrange on the space 3, a step of determining the position of the boundary 4 of the field based on the determination table, and the position of the boundary 4 And a step of performing electron beam exposure by dividing the field.
(Supplementary Note 12) Based on the size of the drawn patterns 1 and 2 and the size of the space 3 formed between the pattern 1 and the other pattern 2, the field boundary 4 is set on the patterns 1 and 2. An electron beam exposure apparatus comprising: a determination table that determines whether to place the field boundary 4 on the space 3; and means for determining a position of the boundary 4 of the field based on the determination table .

  As a practical example of the present invention, a field division method for field connection of a subfield which is a deflection region of a sub deflector is typical. However, for field connection of a main field which is a deflection region of a main deflector. It also applies to occasions.

It is explanatory drawing of the fundamental structure of this invention. It is explanatory drawing of the determination table used for the preparation method of the data for electron beam exposure of Example 1 of this invention. It is explanatory drawing of the space size and pattern size in a determination table. It is a flowchart of the preparation method of the data for electron beam exposure of Example 1 of this invention. It is explanatory drawing of an example of the preparation method of the data for electron beam exposure of Example 1 of this invention. It is explanatory drawing of the effect of this invention. It is explanatory drawing of an electron beam drawing method. It is explanatory drawing of a field division method. It is explanatory drawing of the problem of the conventional field division | segmentation method.

Explanation of symbols

1 pattern 2 pattern 3 space 4 boundary 11 subfield 12 subfield 13 field boundary 14 field margin area 15 field margin area 16 large pattern 17 large pattern 18 space 41 electron beam 42 main deflector 43 sub deflector 44 wafer 45 wafer stage 46 Main field 47 Subfield 51 Subfield 52 Subfield 53 Field boundary 54 Field margin area 55 Field margin area 56 Rectangular pattern 57 Rectangular pattern 57 ₁ divided rectangular pattern 57 ₂ divided rectangular pattern 58 Space 59 Boundary 61 Subfield 62 Subfield 63 Field Boundary 64 Field margin area 65 Field margin area 66 Rectangular pattern 67 Rectangular pattern 68 Space 69 Field 70 space portion

Claims (5)

A method of dividing design data for each field of an electron beam exposure device, wherein the field of the field is determined based on the size of a pattern to be drawn and the size of a space formed between the pattern and another pattern. Creating a determination table that defines whether a boundary is to be arranged on the pattern or the space, and determining a position of the boundary of the field based on the determination table A method for creating electron beam exposure data. When the boundary is arranged on the pattern, a step of determining an additional condition regarding the width of the first divided pattern and the second divided pattern generated by the boundary, and based on the additional condition The electron beam exposure data creation method according to claim 1, wherein the position of the boundary is moved. Based on the size of the pattern to be drawn and the size of the space formed between the pattern and another pattern, it is determined whether the field boundary is arranged on the pattern or the space. A step of creating a determination table, a step of determining a boundary position of the field based on the determination table, and a step of performing the electron beam exposure by dividing the field at the determined boundary position. An electron beam exposure method comprising: Based on the size of the pattern to be drawn and the size of the space formed between the pattern and another pattern, it is determined whether the field boundary is arranged on the pattern or the space. And a step of determining a boundary position of the field based on the determination table, and a step of performing the electron beam exposure by dividing the field at the boundary position. A method of manufacturing a semiconductor device. Based on the size of the pattern to be drawn and the size of the space formed between the pattern and another pattern, it is determined whether the field boundary is arranged on the pattern or the space. An electron beam drawing apparatus comprising a determination table and a function of determining a boundary position of the field based on the determination table.

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