JP2001307976A - Adjusting method of threshold in transcription by exposure of charged-particle-beam, transcriptional method of the exposure, and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a selective method of an exposure threshold whereto the correspondent line-width variation of a formed pattern is made small even when the blooming quantity of the formed pattern is varied during its exposure operation. SOLUTION: With respect to a pattern (1) or a pattern (2) generated when the variation of the blooming of an optical system is ±10 nm, the relation between the exposure threshold and the line-width variation of each pattern is represented by such lines (1) or lines (2) as shown in the figure. It is understood from an intersection A of both the corresponding lines (1), (2) that the allowable exposure threshold for making small the line-width variations of both the patterns (1), (2) is set to 0.423. The line-width variation corresponding to the intersection A is 2.1 nm. Since the blooming variation is ±10 nm, the ratio of this line-width variation to the blooming variation is about 1/5. When an allowable value of the line-width variation corresponding to the blooming variation of 10 nm is set to 1/3, there is brought a scope θ of the exposure threshold into 0.381<=θ<=0.464, by taking the maximum and minimum among the points whereat four auxiliary lines intersect the line of a line-width variation equal to 10/3 nm=3.33 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adjusting a threshold value in an exposure and transfer apparatus of a type in which a pattern on a mask or a reticle is transferred onto a sensitive substrate surface using a charged particle beam.
The present invention relates to an exposure method and a method for manufacturing a semiconductor device using the exposure method.

[0002]

2. Description of the Related Art In a charged particle beam exposure apparatus for exposing a pattern formed on a mask or a reticle to a sensitive substrate such as a wafer using a charged particle beam, an actual exposure amount is close to the exposure amount due to charged particles reflected from the substrate. There is a proximity effect that changes according to the pattern distribution.

In the proximity effect, charged particles incident on the surface of the sensitive substrate spread while being scattered at a small angle, thereby reducing the energy stored at a predetermined position or causing the charged particles incident on the exposed portion to be largely scattered. It is caused by applying energy to the surrounding unexposed area.

As a method for solving this problem, a method of adjusting the irradiation amount (Japanese Patent Laid-Open No. 11-31658) or changing a pattern shape for forming a mask or a reticle so that the amount of energy stored in the sensitive substrate becomes desirable. Method (Jpn. J. Appl. Phys. Vol. 37 (1998) pp.6774-677
8 Part I, No.12B. December 1998).

On the other hand, the charged particle transfer optical system has blur. Blurring is caused by geometrical aberrations such as spherical aberration that exist as in the case of ordinary light, and repulsion of charged particles in a beam due to Coulomb interaction.

In general, blur caused by geometric aberration increases as the distance from the system axis on the sensitive substrate surface increases. In an exposure apparatus of a divisional projection transfer system for projecting and exposing a part of a reticle at a time, the blur increases as the center of a subfield, which is a unit of one transfer exposure, is farther from a system axis. Also, there is a general tendency that the blur is greater at the end than at the center of the subfield.

On the other hand, the blur due to the Coulomb interaction tends to increase as the pattern area increases and the amount of current increases. Blur reduces the amount of charged particles incident on the intended position on the sensitive substrate surface, and has an effect similar to the proximity effect caused by scattering in the sensitive substrate, so that an unintended increase or decrease in line width is caused. This is a problem.

In the prior art, focus correction is performed in accordance with the distance between the center of the subfield and the system axis, that is, the amount of deflection and the pattern opening area of the subfield, so that there is no difference in blur between the subfields. Was like that. If there is a subfield with a larger blur, a blur is intentionally added to the subfield with a smaller blur by a focus correction lens until a similar blur is obtained. By doing so, the scattering coefficient and the magnitude of blur become uniform on the sensitive substrate. Therefore, if the shape of the reticle pattern is changed in consideration of the scattering coefficient and the size of the blur, the proximity effect and the blur effect can be corrected. Obtainable.

[0009]

However, if the size of the blur differs between the center and the edge of the subfield, the difference between the blurs between the two is eliminated by the above method because both are exposed at once. It is not possible. As a result, unintended variations in pattern size due to blurring must occur in any region of the subfield.

[0010] In addition to the above-described positional dependence of blur, the conventional technique also copes with time-dependent variations in blur caused by a change in the state of the optical system during exposure due to, for example, a rise in temperature. Can not.

Conventionally, there has been no guideline on how the pattern boundary position changes in response to a change in blur of the optical system. Therefore, in order to obtain an intended pattern size, for example, the irradiation amount is changed to obtain an optimum value. It was necessary to carry out such experiments. Also, if the blur of the optical system fluctuates after the desired pattern has been obtained, it is necessary to assign an even greater number of parameters in order to find out how much the pattern boundary position has moved. The relationship with the threshold was not clear.

Even if an optimum threshold value is obtained, the following problem exists. In order to obtain a pattern shape as clear as possible, a resist having a high γ value is desirable. However, generally, a resist having a high γ value tends to have a high required energy threshold. When the photosensitive characteristics are forcibly shifted to lower the energy threshold, the γ value of the resist becomes lower. When a low energy threshold is required, it is necessary to increase the irradiation dose in order to use a resist having a high γ value. In order to increase the irradiation amount, there are two methods of increasing the intensity of the charged particle beam and increasing the irradiation time.
However, the former is not desirable because it increases the blur of the optical system and increases the minimum line width that can be realized. The latter is not desirable because the throughput is reduced.

In view of the above problems, the present invention provides a method of adjusting a threshold value in a charged particle beam exposure transfer, which can reduce a change in the position of a pattern boundary with respect to a change in blur of an optical system of the charged particle beam exposure apparatus. It is an object to provide a method, an exposure transfer method capable of realizing a low threshold value in a high γ resist, and a method for manufacturing a semiconductor device using the same.

[0014]

A first means for solving the above-mentioned problem is to perform exposure transfer by using a charged particle beam exposure apparatus of a system for transferring a pattern on a mask or a reticle onto a sensitive substrate surface. When performing, for the fluctuation of the blur of the optical system, the threshold value in the charged particle beam exposure transfer characterized in that the threshold value is determined so that the fluctuation of the boundary position of the pattern realized on the sensitive substrate falls within a predetermined range. This is an adjustment method (claim 1).

In this specification, the term "threshold" means "a value obtained by dividing an energy value for forming a pattern by a resist by a maximum value of energy that can be accumulated in the resist upon exposure" unless otherwise specified. . That is,
What is generally referred to as a threshold value is an energy value at which the resist forms a pattern, that is, when the resist is developed, the resist disappears (in the case of a positive resist) or remains (in the case of a negative resist). In this specification, this value is defined as the maximum energy value given to the resist at the time of exposure, that is, a scattering radius within the substrate, or a blurring of the optical system that is sufficiently large. When a large pattern (for example, a pattern in which all the subfields are one pattern) is exposed, the value is normalized by dividing by a stored energy value applied to the center of the exposed portion, and is referred to as a threshold. Also, consider that this threshold is obtained by dividing the energy value at which the resist forms a pattern by (irradiation current density) x (irradiation time) x (the ratio of the energy stored in the resist to the energy incident on the resist). Can also.

According to the study results of the inventors, the boundary position of the pattern formed on the sensitive substrate due to the fluctuation of the blur is
Subject to fluctuations by threshold. Therefore, by selecting a threshold value such that the variation of the boundary position of the pattern realized on the sensitive substrate is within a predetermined range, even if the amount of blur changes during exposure, the pattern formed on the sensitive substrate can be changed. Variations in shape can be kept small.

A second means for solving the above-mentioned problems is as follows:
The first means, wherein the fluctuation of the blur of the optical system used for the calculation is obtained in accordance with the distribution of the pattern to be exposed (claim 2).

The relationship between the variation in the amount of blur and the variation in the boundary of the pattern formed on the sensitive substrate is affected not only by the threshold value but also by the distribution of the pattern to be exposed. In this means,
Since the calculation for determining the threshold value takes into account the pattern distribution to be exposed, the variation in the shape of the pattern formed on the sensitive substrate can be further reduced.

A third means for solving the above-mentioned problem is:
The first means or the second means, wherein a resist having an appropriate energy value for forming a pattern is selected for a given irradiation intensity and irradiation time of a charged particle beam ( Claim 3).

In this means, the irradiation intensity and irradiation time of the charged particle beam are determined in advance from the permissible Coulomb effect and throughput, and a resist is selected such that a predetermined threshold can be obtained. I have. Therefore, the effects of the first means or the second means can be exerted while keeping the Coulomb effect and the throughput at predetermined values.

A fourth means for solving the above problem is as follows.
The first means or the second means, wherein an appropriate irradiation time is selected from an irradiation intensity of a given charged particle beam and an energy value of a resist at which pattern formation occurs (claim). Item 4).

In the actual exposure / transfer process, the type of resist must be determined from other restrictive conditions. In addition, even if an attempt is made to select the type of resist by the third means, pattern formation is not possible. In some cases, the resulting resist energy value does not exactly match the desired value. In such a case, the type of the resist is determined first, exposure and transfer are performed based on the irradiation intensity allowed from the Coulomb effect, and the desired threshold value is obtained by changing the irradiation time.

A fifth means for solving the above problem is as follows.
The first means or the second means, wherein an appropriate irradiation intensity is selected from an irradiation time of a given charged particle beam and an energy value of a resist at which pattern formation occurs (claim). Item 5).

This means determines the type of resist first for the same reason as the fourth means, but is applied when there is a margin for changing the irradiation intensity in consideration of the Coulomb effect. After giving priority to the throughput and determining the irradiation time, the target threshold value is obtained by changing the irradiation intensity according to the type of the resist and the irradiation time.

A sixth means for solving the above-mentioned problem is:
Exposing a circuit pattern formed on a mask or a reticle to a sensitive substrate by adjusting a threshold value using any one of the first to fifth means. This is a transfer method (claim 6).

According to this means, even if the blur changes during exposure, the change in the shape of the pattern formed on the sensitive substrate can be reduced.

[0027] A seventh means for solving the above problem is as follows.
Using a charged particle beam exposure system that transfers the pattern on the mask or reticle onto the sensitive substrate surface, apart from the exposure used for the exposure transfer, has a process of uniformly exposing the photosensitive substrate to a pattern-independent exposure An exposure and transfer method (claim 7).

For example, when the third means is adopted,
In some cases, a resist having a low energy value at which pattern formation occurs is required. However, in general, a resist having a low energy value at which pattern formation occurs has a low γ value, and it is difficult to form a clear pattern shape.
In this means, apart from the exposure used for the exposure transfer, uniform exposure is applied to the sensitive substrate, so that even when a resist having a low energy value for pattern formation and a high γ value is used, fluctuation of blur is sensitive. The variation in the line width of the substrate can be made the same as when a resist having a low energy value at which pattern formation occurs is used.

Eighth means for solving the above-mentioned problems is as follows:
A method of manufacturing a semiconductor device, comprising the sixth means or the seventh means in its process (Claim 8)
It is.

According to the present invention, even when the blur is changed during the exposure, the exposure can be performed while the change in the shape of the pattern formed on the sensitive substrate is small, so that a clear pattern shape can be formed. it can. Therefore, a semiconductor device having a fine pattern can be manufactured with high yield. Further, when the seventh means is used, a resist having a high γ value can be used, so that a semiconductor device having a fine pattern can be manufactured with good yield.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present embodiment, a threshold value is selected so that the line width of a pattern formed on a sensitive substrate does not fluctuate with respect to blurring of an optical system. explain.

The energy profile immediately after the charged particle beam has passed through the reticle can be expressed as follows. For simplicity, the calculation is performed in one dimension. That is,
It is assumed that the position is taken only in the x direction and the same pattern is spread in the y direction. DR (x) = 1.0 (when x is the reticle transmission range) DR (x) = 0.0 (when x is the reticle non-transmission range) However, the value of the energy profile DR (x) illuminates the reticle It is normalized by the current density of the charged particle beam.
That is, the value of the stored energy given to the center of the exposed portion when a pattern that is sufficiently larger than the scattering radius in the substrate or the blur of the optical system is exposed is set to 1.

Immediately before the light enters the sensitive substrate surface, the energy profile becomes dull due to blurring of the optical system. The dull energy profile DW (x) immediately before the light enters the sensitive substrate surface due to blurring of the optical system is expressed by the following equation.

[0034]

(Equation 1)

Here, β is a standard deviation appropriately determined when the blur of the optical system is represented by a Gaussian distribution. Charged particles incident on the sensitive substrate are scattered therein and cause a proximity effect. Energy stored on sensitive substrate after scattering
E (x) is represented by the following equation. E (x) = E _b (x) + E _f (x)… (2)

[0036]

(Equation 2)

Here, η is the back scattering coefficient, σ _b is the back scattering diameter, and σ _f is the forward scattering diameter. Also, for simplicity,
It was assumed that all the energy incident on the resist was accumulated in the resist.

First, the reticle pattern is deformed such that the pattern is formed to the intended dimensions for the given threshold value. Exposure transfer magnification is 1:
Considering the case of 1, the reticle pattern having the same pattern as the pattern to be transferred to the sensitive substrate is first considered, and DR (x) is determined accordingly. Then, the energy stored in the resist is obtained by using the equations (1) to (4), and a portion where the stored energy exceeds a threshold value is defined as a portion where a pattern is formed on the sensitive substrate.

Then, the difference between the pattern and the target pattern is obtained, the reticle pattern is changed in a direction to reduce the difference, a new DR (x) is obtained, and the equations (1) to (4) are used again. Then, the energy stored in the resist is obtained, and a portion where the stored energy exceeds a threshold is defined as a portion where a pattern is formed on the sensitive substrate. By repeating this,
A reticle pattern for forming a target pattern on a sensitive substrate is determined.

Using the deformed reticle pattern, the blur of the optical system is changed, and the calculations according to the equations (1) to (4) are performed again to obtain the energy profile stored in the resist. A pattern is obtained when the obtained stored energy profile is cut by a predetermined threshold. The difference between the boundary position of this pattern and the originally intended pattern is the “pattern size variation with respect to blur variation” at the threshold.

When a certain reticle pattern is given,
By examining “pattern size variation with respect to blur variation” while changing the threshold value, it is possible to determine a preferable threshold range in which “pattern size variation with respect to blur variation” can be reduced. In the present embodiment, a modified reticle pattern has been described as an example. However, it is not always necessary to perform pattern deformation, and a preferable threshold range may be obtained without performing deformation.

Here, a reticle pattern to be provided is dense, for example, when there are many patterns having a size of about the backscattering radius, and when there are scattered lines of the minimum formable line width of the apparatus. In some cases, it is assumed that the preferred threshold range is different.

Therefore, a preferable threshold value range is obtained for both of them, and by taking a moderate value, a threshold value capable of suppressing “pattern size fluctuation due to blur fluctuation” can be obtained for any reticle pattern.

In order to specifically obtain the obtained threshold value, three methods are conceivable because the threshold value is a function of the energy value for forming a pattern in the resist, the irradiation current density, and the irradiation time.

The first is a method of selecting a resist having an energy value for forming an appropriate pattern for a predetermined irradiation current density and irradiation time, and the second is a method for selecting a resist having a predetermined resist and irradiation current density. A third method is to select an appropriate irradiation time, and a third method is to select an appropriate irradiation current density for a predetermined resist and irradiation time.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the charged particles used are electrons having an acceleration voltage of 100 keV, the blur of the optical system is 70 nm, the back scattering diameter σ _b = 31.2 μm, and the back scattering coefficient η = 0.
4. The calculation is performed with the forward scattering diameter σ _f = 7 nm. In addition,
In the present specification, blur is assumed to have a Gaussian distribution, and the amount of blur is indicated by blur. The relationship between blur and equation (1) is β ≒ 0.6 * blur. On the other hand, the reticle pattern was deformed such that the intended pattern was burned at a given threshold value.

FIG. 1 is a diagram showing a pattern intended to be formed on a sensitive substrate. The following three types of patterns are used to check the degree of backscattering.

An isolated line having a line width of 100 nm, a large pattern of 50 μm with a space of 100 nm in between, and a 100 nm line adjacent only on one side to a large pattern of 100 μm, with a space of 100 nm in between, and a large pattern of 50 μm on both sides Line An example of a deformed reticle pattern for forming the pattern in FIG. 2 is shown. In order to reduce the effect of fogging due to backscattering, both lines and large patterns are reduced in size.

Similar modifications were made so that the intended pattern dimensions could be obtained for each pattern. 100nm included in the pattern at various thresholds
Table 1 shows the line width after deformation of the reticle of the line No.

[0050]

[Table 1]

With respect to the pattern after the deformation, the blur was varied up to ± 40 nm around 70 nm, and at this time, the increase / decrease of the line width intended to be 100 nm was examined. Table 2 shows this.

[0052]

[Table 2]

FIG. 3 shows the relationship between the threshold value and the line width fluctuation for both patterns when the blur of the optical system fluctuates by ± 10 nm.

In order to reduce the line width variation in both patterns, the threshold value is set to 0.0 from the intersection point A of the line corresponding to FIG.
It is understood that 423 should be set. At this time, the line width variation is 2.1 nm. Since the fluctuation of the blur is ± 10 nm, the ratio is about 1/5. Now, assuming that the line width fluctuation with respect to the fluctuation of blur is allowed up to 1/3, the maximum and minimum of the intersection of the line width fluctuation = 10/3 = 3.33 nm and the four auxiliary lines in FIG. Is 0.381 ≦ θ ≦ 0.464. Similarly, the line width fluctuation with respect to the fluctuation of the blur is 1 /
Table 3 shows the range of the threshold value θ that can be set to 3.

[0055]

[Table 3]

Similarly, when all the patterns are considered, the relationship between the threshold value and the line width variation as shown in Table 2 is graphed, and the same operation is performed. The value of the threshold θ that can minimize the fluctuation can be obtained. That is, assuming that the value of each line width variation for each pattern is W ₁ (θ), W ₂ (θ), and W ₃ (θ), max {W ₁ (θ), W ₂ (θ), W ₃ The value of θ that minimizes (θ)} may be obtained. Even when fluctuation of blur is allowed to some extent, the range of θ where W ₁ (θ), W ₂ (θ), and W ₃ (θ) fall within the range is obtained, and the range of θ common to all is obtained. What is necessary is just a range. 1/2 of line width fluctuation against blur fluctuation
Table 4 shows the range of the threshold value θ.

[0057]

[Table 4]

For an isolated pattern such as
As shown in FIG. 4, the smaller the threshold θ is, the smaller the variation of the pattern size due to the blur of the optical system becomes. However, in general, a resist having a high γ value that can clearly realize a difference between a region where a pattern is formed and a region where a pattern is not formed tends to require a large amount of energy storage. When the photosensitive characteristic is shifted so that the energy storage amount for forming the pattern is reduced, the γ value of the resist is reduced.

FIG. 5 illustrates this state. FIG. 5A shows γ
FIG. 7 is a diagram showing a tendency of a γ value of a resist having a high value and an energy storage amount for forming a pattern. When the energy value exceeds a certain value, the amount of the remaining resist film changes rapidly, so that a high contrast can be obtained between the formed pattern region and the non-formed pattern region. In contrast, FIG.
(B) is a diagram showing a tendency of the γ value of a resist having a low γ value and the amount of stored energy for forming a pattern.

The change in the remaining film amount of the resist starts from a low energy storage amount, but the inclination becomes gentler than that of FIG. Therefore, even if an attempt is made to reduce the threshold value θ, another problem that the boundary of the pattern becomes unclear occurs due to the relationship with the γ value. Is a problem.

When a low threshold θ is required, assuming that the ratio of the energy stored in the resist to the energy incident on the resist is 1, to use a resist having a high γ value, the threshold times the irradiation amount of the charged particle beam. = The amount of stored energy at which the resist pattern is formed,
It is necessary to increase the irradiation dose. In order to increase the irradiation amount, there are two methods, a method of increasing the density of the charged particle beam and a method of increasing the irradiation time. The former is undesirable because it increases the blur of the optical system and pushes up the minimum achievable line width. The latter is problematic because of the reduced throughput.

This problem can be solved by raising the effective threshold value by performing uniform exposure on the sensitive substrate separately from the exposure for transferring the pattern. The principle will be described with reference to FIG.

FIG. 6A shows the amount of energy storage (solid line) determined by the resist, the exposure time, the charged particle beam density, etc., and the amount of energy storage required by the line width stability against blur fluctuation (dashed-dotted line). FIG. The horizontal axis represents a position on the sensitive substrate surface, and the vertical axis represents the amount of stored energy at the position. That is,
In order to reduce line width fluctuation due to blurring, a small amount of energy storage as shown by a dashed line is required, but the required amount of energy storage from the required γ value is shown by a solid line There is a difference between the two.

Therefore, in order to fill in this difference, FIG.
As shown in (2), irradiation of energy corresponding to the difference between the two energy accumulation amounts is uniformly performed on the entire surface of the sensitive substrate. Then, normal exposure transfer is performed next, and the accumulated energy given at this time is set to an amount corresponding to a threshold value for reducing line width fluctuation due to blurring. (Either of the uniform exposure and the normal exposure may be performed first.) By doing so, as shown in FIG. 6B, the energy accumulation amount determined by the resist and the line corresponding to the blur variation The amount of energy storage required from the width stability can be matched. Therefore, a resist having a high γ value can be used.

Hereinafter, an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described. FIG. 7 is a flowchart showing an example of the semiconductor device manufacturing method of the present invention. The manufacturing process of this example includes the following main processes. Wafer manufacturing process for manufacturing a wafer (or wafer preparing process for preparing a wafer) Mask manufacturing process for manufacturing a mask to be used for exposure (or mask preparing process for preparing a mask) Wafer processing process for performing necessary processing on a wafer Wafer Chip assembling step of cutting out the chips formed on the chip one by one to make it operable Chip inspecting step of inspecting the resulting chips Each of the steps further includes several sub-steps.

Among these main steps, the main step that has a decisive effect on the performance of the semiconductor device is the wafer processing step. In this step, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing step includes the following steps. A thin film forming step (using CVD, sputtering, etc.) for forming a dielectric thin film, a wiring portion, or a metal thin film for forming an electrode portion, which serves as an insulating layer. A lithography process of forming a resist pattern using a mask (reticle) in order to selectively process etc. An etching process of processing a thin film layer or a substrate according to a resist pattern (for example, using a dry etching technique) An ion / impurity implantation diffusion process Resist stripping step Inspection step of inspecting the processed wafer Further, the wafer processing step is repeated by a necessary number of layers to manufacture a semiconductor device that operates as designed.

FIG. 8 is a flowchart showing a lithography step which is the core of the wafer processing step shown in FIG. This lithography step includes the following steps. A resist coating step of coating a resist on a wafer on which a circuit pattern has been formed in the preceding step An exposing step of exposing the resist A developing step of developing the exposed resist to obtain a resist pattern Stabilizing the developed resist pattern The above-described semiconductor device manufacturing process, wafer processing process, and lithography process are well known, and will not require further explanation.

In the embodiments of the method for manufacturing a semiconductor device according to the present invention, the rough resist selected according to the present invention and the exposure method according to the present invention are used in the exposure step of exposing the resist.

[0069]

As described above, according to the first aspect of the present invention, even when the amount of blur changes during exposure, a change in the shape of the pattern formed on the sensitive substrate can be suppressed. According to the second aspect of the invention, the variation in the shape of the pattern formed on the sensitive substrate can be further reduced.

According to the third aspect of the present invention, while maintaining the Coulomb effect and the throughput at predetermined values, even when the amount of blur changes during exposure, the variation in the shape of the pattern formed on the sensitive substrate is reduced. Can be suppressed.

According to the fourth aspect of the present invention, a predetermined resist is used, and while the Coulomb effect is suppressed to a predetermined range, even if the amount of blur changes during exposure, the pattern formed on the sensitive substrate can be changed. Can be suppressed to a small extent.

According to the fifth aspect of the present invention, a predetermined resist is used, and a pattern formed on a sensitive substrate can be formed even when the amount of blur changes during exposure while maintaining the throughput at a predetermined value. Can be suppressed to a small extent.

According to the sixth aspect of the invention, even if the blur changes during exposure, the change in the shape of the pattern formed on the sensitive substrate can be reduced. In the invention according to claim 7, even when a resist having a high γ value is used, the fluctuation that the fluctuation of the blur gives to the line width of the sensitive substrate is the same as when a resist having a low energy value at which pattern formation occurs is used. can do.

In the invention according to claim 8,
A semiconductor device having a fine pattern can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pattern intended to be formed on a sensitive substrate.

FIG. 2 is a diagram showing an example of a reticle pattern after deformation for forming a target pattern.

FIG. 3 is a diagram illustrating a relationship between a threshold value and a line width variation for two patterns.

FIG. 4 is a diagram illustrating a relationship between a threshold value and a line width variation for an isolated pattern.

FIG. 5 is a diagram illustrating an example of a relationship between a resist threshold and a γ value.

FIG. 6 is a diagram illustrating a method for obtaining the same effect as a resist having a low threshold value by using a resist having a high γ value.

FIG. 7 is a flowchart illustrating an example of a method for manufacturing a semiconductor device using a resist according to an embodiment of the present invention or using an exposure method according to an embodiment of the present invention.

FIG. 8 is a flowchart showing a lithography process.

Claims (8)

[Claims] When performing exposure transfer using a charged particle beam exposure apparatus of a type that transfers a pattern on a mask or a reticle onto a surface of a sensitive substrate, the photosensitive substrate is exposed to fluctuations in blur of an optical system. A method for adjusting a threshold value in charged particle beam exposure transfer, wherein a threshold value is determined so that a variation in a boundary position of a pattern to be realized falls within a predetermined range. 2. A method for adjusting a threshold value in a charged particle beam exposure transfer according to claim 1, wherein a variation in blur of an optical system used for calculation is obtained according to a distribution of a pattern to be exposed. A method for adjusting a threshold value in a charged particle beam exposure transfer, characterized in that: 3. A method for adjusting a threshold value in a charged particle beam exposure transfer according to claim 1 or 2, wherein pattern formation occurs for a given irradiation intensity and irradiation time of the charged particle beam. A method for adjusting a threshold value in charged particle beam exposure transfer, wherein a resist having an appropriate value is selected. 4. The method for adjusting a threshold value in a charged particle beam exposure transfer according to claim 1 or 2, wherein the irradiation intensity of a given charged particle beam and the energy value of a resist in which pattern formation occurs occur. A method for adjusting a threshold in charged particle beam exposure transfer, which comprises selecting an appropriate irradiation time. 5. The method for adjusting a threshold value in a charged particle beam exposure transfer according to claim 1 or 2, wherein the irradiation time of a given charged particle beam and the energy value of a resist at which pattern formation occurs are determined. A method for adjusting a threshold in charged particle beam exposure transfer, characterized by selecting an appropriate irradiation intensity. 6. One of claims 1 to 5
Adjusting the threshold value using the method for adjusting the threshold value in the charged particle beam exposure transfer described in the paragraph, and transferring a circuit pattern formed on a mask or a reticle to a sensitive substrate. Exposure transfer method. 7. A method for transferring a pattern on a mask or a reticle onto a surface of a sensitive substrate by using a charged particle beam exposure apparatus, wherein exposure independent of the pattern is uniformly applied to the sensitive substrate separately from exposure used for exposure transfer. An exposure transfer method comprising a step of applying. 8. A method for manufacturing a semiconductor device, comprising the step of performing the exposure transfer method according to claim 6 or 7.