JP2001174976A - Halftone phase shift mask and halftone phase shift mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a halftone phase shift mask capable of nearly perfectly preventing the leakage of light for exposure by a simple structure while making good use of its original advantages and a halftone phase shift mask blank as the material of the halftone phase shift mask. SOLUTION: In a halftone phase shift mask blank with a translucent film 5 comprising a monolayer film which transmits light having such intensity as not to contribute to exposure and shifts the phase of the transmitted light on a transparent substrate 1, a light shielding film 7 comprising a material having resistance to an atmosphere in which the constituent material of the translucent film 5 is etched is disposed on the translucent film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask capable of improving the resolution of a transfer pattern by giving a phase difference between exposure lights passing through a mask.
The light-shielding portion is formed of a semi-transmissive film that transmits light having an intensity that does not substantially contribute to exposure and simultaneously shifts the phase of transmitted light, and light that has passed near the boundary between the light-shielding portion and the light-transmitting portion cancels each other. The present invention relates to a so-called halftone type phase shift mask capable of maintaining a good contrast at a boundary portion in such a manner and a halftone type phase shift mask blank as a material thereof.

[0002]

2. Description of the Related Art In the manufacture of semiconductor LSIs and the like, a phase shift mask is used as one of photomasks serving as a fine pattern transfer mask. This phase shift mask provides a phase difference between exposure light passing through the mask,
This is to improve the resolution of the transfer pattern. As one of the phase shift masks, a phase shift mask described in Japanese Patent Application Laid-Open No. 4-136854 is known, which is particularly suitable for transferring an isolated pattern such as a single hole, dot, line, or space. I have.

FIG. 23 is a sectional view of a phase shift mask described in Japanese Patent Application Laid-Open No. 4-136854. As shown in FIG. 23, the phase shift mask 30 described in this publication
A semi-transmissive film 32 is formed on the transparent substrate 31 for transmitting light having an intensity substantially not contributing to exposure and simultaneously shifting the phase of light passing therethrough. Then, a transfer region I at the center of the transparent substrate 31 is formed. By selectively removing a part of the semi-translucent film 32, a light transmitting portion 33 that transmits light having an intensity substantially contributing to exposure and a light transmitting portion 33 that does not substantially contribute to exposure are transmitted. And a semi-transparent portion 34 to be formed. The phase shift mask 30 shifts the phase of the light passing through the semi-transmissive portion 34 so that the phase of the light passing through the semi-transmissive portion 34 is shifted with respect to the phase of the light passing through the translucent portion 33. In this way, the light that has passed through the vicinity of the boundary between the light-transmitting portion 33 and the semi-light-transmitting portion 34 and diverted by diffraction cancels each other out so as to cancel each other. The contrast can be maintained well. FIG. 24 shows an amplitude distribution and an intensity distribution of the light passing near the boundary between the light transmitting portion 33 and the semi-light transmitting portion 34. This type of phase shift mask is called a so-called halftone type phase shift mask.

[0004]

As described above, the halftone type phase shift mask has a phase shift function and a light blocking function by a semi-transparent portion. That is, the semi-transparent portion functions as a phase shift layer at the boundary of the pattern, and functions as a light-shielding layer at other portions. Therefore, a small amount of leaked light reaches a portion where it is ideal to completely block the exposure light. Normally, the entire exposure is adjusted so that even if the leakage light does not result in substantial exposure.

[0005] Incidentally, the required amount of exposure varies greatly depending on the location of the object to be transferred, such as when the thickness of the resist to be exposed formed on the object varies greatly depending on the location. In such a case, it is absolutely necessary to set the entire exposure amount to a value that can cover the maximum exposure amount among the exposure amounts required at each location of the transfer target. Otherwise, the entire exposure cannot be performed.

However, in such a case, for example, in a thick part where a large exposure amount is required, the influence of the light leaked from the semi-translucent part is small. It has been found that the subsequent film thickness reduction of the resist may exceed the allowable range. FIG. 25 to FIG. 27 are explanatory diagrams of this situation.

FIG. 25 is a view showing an example of an object to be transferred in which the thickness of the resist to be exposed varies depending on the location, and FIG.
FIG. 27 is a view showing a state in which exposure is performed on an object to be transferred of FIG.
FIG. 6 is a view showing a transferred body after performing exposure and development shown in FIG.

[0008] The transfer object shown in FIG.
A conductive film 101 having a step of about 0.5 μm is provided thereon, and a positive resist film 102 for forming a pattern is formed thereon by spin coating. The transfer target is formed by pattern-exposing the resist 102 and developing the resist, forming a resist pattern, and then performing etching using the resist pattern as a mask to form a wiring pattern on the conductive film 101.

[0009] As shown in FIG. 26, the exposure of the resist film 102 is performed by a halftone type phase shift mask 30.
Let's consider the case. In this case, the thickness of the resist 102 in the region B where the thickness of the conductive film 101 is small is larger than the thickness of the resist 102 in the region A where the thickness of the conductive film 101 is large. For this reason, the value of the exposure amount is set to a large value capable of exposing the area B.

Then, as shown in FIG. 27, when the resist 101 is developed, the resist pattern 102a is reduced in film thickness in response to the light leaking from the semi-transparent portion 34.
This film reduction is not an amount that causes a problem at the time of etching in the region B where the resist film 102 is originally sufficiently thick. However, in a region A where the resist film 102 is originally thin, the film thickness may be further reduced, and the function as a mask may not be sufficiently performed at the time of etching. Therefore, it is difficult to set the exposure amount, and in some cases, the optimum exposure amount may not be obtained. This situation is particularly serious when the transmittance of the semi-light-transmitting portion is high (for example, 10 to 15%) because the amount of energy leakage of the exposure light increases.

The halftone type phase shift mask is usually a mask (reticle) of a reduction projection exposure apparatus (stepper) which is an exposure apparatus used in semiconductor manufacturing.
Used as This stepper reduces the projected image obtained by projecting the reticle with exposure light using a projection lens,
In this method, an image is formed on a semiconductor wafer as an object to be transferred and reduced projection exposure is performed. In this reduced projection exposure, usually, the same reticle pattern is repeatedly transferred and exposed at different positions on one semiconductor wafer, and a large number of semiconductor chips are obtained from one wafer. Therefore, when pattern transfer is performed using this stepper, as shown in FIG. 23, only the transfer region I of the phase shift mask 30 (reticle) is exposed by the covering member (aperture) 36 provided on the stepper. Exposure is performed by covering the peripheral region as described above.

However, this aperture 36
It is difficult to mechanically dispose the transfer region so as to expose only the transfer region with high accuracy (for example, accuracy of 1 μm or less), and in many cases, the exposed portion protrudes into the non-transfer region around the outer periphery of the transfer region. Further, even if the aperture has high precision and there is no protruding portion, the exposure light is diffracted and reaches the non-transfer region due to the distance between the aperture and the transfer target.

As described above, when the aperture 36 allows the exposure light to pass through a wider area than the original transfer area, the following problem is found. That is, the halftone type phase shift mask 30 usually has a light semi-transmissive film 32 that transmits light of an intensity that does not substantially contribute to exposure to a non-transfer region.
Are formed. Therefore, as described above, when the aperture 36 allows the exposure light to pass through a wider area than the original transfer area, the exposed portion is exposed to light having an intensity that does not substantially contribute to exposure. Of course, no problem arises with one exposure even if there is such a protruding portion. However, there is a case where the protruding exposed portion (protruding exposed portion) overlaps the transfer area or overlaps with the protruding exposed portion in the next exposure. In the exposure, even if the exposure amounts do not substantially contribute to the exposure, they may be added to reach an amount that contributes to the exposure. Accordingly, this results in the same situation as when exposure is performed on an area that should not be exposed, and a defect occurs. Hereinafter, this point will be specifically described.

FIG. 28 is an explanatory view showing a phenomenon in which the exposed portions overlap. FIG. 9 shows a case where four transfer operations are performed adjacently on a wafer coated with a resist to be exposed for the sake of simplicity, and regions EI1, EI2, EI3, EI4 is the transfer region, and the portions surrounded by the dotted lines outside the respective transfer regions are the protruding portions △ EI1, △ EI2, △ EI3, and △ EI4. The size (length and width) of each transfer area is I, the size (length and width) of the light passing hole of the actual aperture is I ′, and the size (width) of the protrusion is ΔI. The transfer area EI
The relative positions of 1, EI2, EI3, and EI4 are set so as to be accurately aligned by an XY stage of a stepper or the like. Also, in FIG. 28, in order to make the description easy to understand, the protruding portions # EI1, # EI2, and #E
I3 and △ EI4 are shown enlarged.

As is apparent from FIG.
EI1, .DELTA.EI2, .DELTA.EI3, and .DELTA.EI4 are adjacent to each other and have overlapping portions. These overlapping portions are represented by δEI12, δEI24, δEI34, δEI13,
Assuming that δEI234, δEI134, δEI123, δEI124, the overlapping portions δEI12, δEI24, δEI34, δE
Although the number of overlaps of I13 is two times, the overlap portion δE
I234, δEI134, δEI123, δEI124 are three times, and at point O, there are substantially four overlaps. Now, assuming that the light transmittance of the semi-transparent film 32 is 15%,
Exposure of the same amount as in the case of passing through a film with a light transmittance of 30% is applied to the twice overlapping portion, and light transmittance of 45% is applied to the triple overlapping portion.
Exposure is performed in the same amount as in the case of passing through the film, and the same amount of exposure as in the case of passing through the film having a light transmittance of 60% is performed in the four overlapping portions. For this reason, in these overlapping portions, there is a case where exposure is performed to reach an intensity substantially contributing to exposure. As a result, after performing this exposure, the resist is developed, and a predetermined pattern is formed on the wafer by performing a predetermined etching or the like, and an unnecessary pattern is formed in a portion that should not be formed.
A pattern defect will occur.

SUMMARY OF THE INVENTION The present invention has been made under the above-mentioned background, and has a relatively simple structure to substantially eliminate leakage of exposure light, which is a disadvantage of the halftone type phase shift mask, while taking advantage of its inherent advantages. It is an object of the present invention to provide a halftone type phase shift mask which can prevent the occurrence of the phase shift mask and a halftone type phase shift mask blank as a material thereof.

[0017]

Means for Solving the Problems In order to solve the above-mentioned problems, a halftone type phase shift mask blank according to the present invention is characterized in that (Structure 1) a light having an intensity which does not substantially contribute to exposure is formed on a transparent substrate. In a halftone phase shift mask blank having a semi-transmissive film made of a single-layer film that transmits and shifts the phase of the transmitted light, etching of the material constituting the semi-transmissive film is performed on the semi-transparent film. A configuration characterized by having a light-shielding film made of a material having resistance to the environment,

As an embodiment of the first aspect, (the second aspect), the semi-light-transmitting film is made of molybdenum oxynitride, chromium oxide, chromium nitride, chromium fluoride, chromium carbide, or a mixture of these chromium compounds. Or as a configuration characterized by being composed of a material containing a material in which a light absorbing material is mixed with silicon oxide as a main component, as an aspect of Configuration 1 or 2,
(Constitution 3) The material forming the semi-light-transmitting film is a molybdenum oxynitride silicide film, and the material having resistance to the etching environment of the semi-light-transmitting film is a material containing chromium. The configuration was adopted.

Further, according to the method of manufacturing a halftone type phase shift mask according to the present invention, (Structure 4)
A halftone type phase shift mask for producing a halftone type phase shift mask having a pattern of a semi-transmissive film composed of a single layer film that transmits light having an intensity substantially not contributing to exposure and shifts the phase of the transmitted light. In the method of manufacturing a mask, a halftone type phase shift mask blank having a semi-transmissive film and a light-shielding film made of a material having resistance to an etching environment of the semi-transparent film is sequentially formed on a transparent substrate. A resist pattern forming step of forming a resist pattern on the light shielding film of the tone type phase shift mask blank, and a light shielding film pattern forming step of forming a light shielding film pattern by etching the light shielding film using the resist pattern as a mask, Etching the semi-transparent film using the resist pattern and the light-shielding film pattern as a mask Characterized by having a HanToruHikarimaku pattern forming step of forming a semi-transparent film pattern, and a resist removal step of removing the resist pattern remaining the after semi-transparent film pattern forming step by,

As an aspect of the fourth aspect, (the fifth aspect), after the step of forming the semi-transmissive film pattern, etching for removing a part of the light-shielding film pattern is performed, and at least a portion which performs a phase shift function in the transfer region is provided. The method is characterized by including a step of removing the light shielding film. further,
The phase shift mask according to the present invention includes (Configuration 6) Configuration 4
Or, it is manufactured using the method of 5.

According to the above-described structure, the light-shielding film made of a material having resistance to the etching environment of the material forming the semi-light-transmitting film is provided on the semi-light-transmitting film. Each of the optical film and the light-shielding film is prevented from being etched when one of them is etched, so that it is possible to form separate patterns. Thus, the light-shielding portion can perform more complete light-shielding, while the portion that performs the phase shift function can exhibit that function.

[0022]

(Embodiment 1) FIG. 1 is a view showing a configuration of a halftone type phase shift mask according to Embodiment 1 of the present invention, and is an end view of a cross section taken along line II of FIG. FIG. 2 is a plan view of the halftone phase shift mask according to the first embodiment, and FIGS. 3 to 11 are diagrams illustrating the manufacturing process of the halftone phase shift mask according to the first embodiment. Hereinafter, Embodiment 1 will be described with reference to these drawings. The halftone type phase shift mask blank is a material for manufacturing a halftone type phase shift mask, and has a semi-transmissive film constituting a semi-transmissive part on at least a transparent substrate. Since the one having a light-shielding film constituting the light-shielding light-shielding layer above or below the optical film is broadened, the configuration is
Since the description will be made in the description of the manufacturing process of the halftone phase shift mask, the description thereof will be omitted.

In FIGS. 1 and 2, reference numeral 1 denotes a halftone type phase shift mask, reference numeral 2 denotes a transparent substrate, reference numeral 3 denotes a low transmittance layer, reference numeral 4 denotes a high transmittance layer, reference numeral 5 denotes a semi-transparent layer,
Reference numeral 6 denotes a light transmitting portion, and reference numeral 7 denotes a light shielding layer.

The halftone type phase shift mask 1 is formed by removing a part of the film formed on the entire surface of the transparent substrate 2 to form the light transmitting portion 6, thereby forming a patterned semitransparent layer 5.
And a light-shielding layer 7 is formed on the semi-light-transmitting layer 5 at a main portion except for the vicinity of the boundary with the light-transmitting portion 6.

The semi-transmissive layer 5 is constructed by superposing a high transmittance layer 4 mainly affecting the phase shift characteristic on a low transmittance layer 3 mainly affecting the light transmission characteristic.

The light transmitting portion 6 is a portion that transmits light having an intensity substantially contributing to exposure. The semi-translucent layer 5 is a portion that transmits light having an intensity that does not substantially contribute to exposure, and also shifts the phase of light passing through the semi-translucent layer 5 to shift the phase of the light. By making the phase of the light passing through the light transmitting portion 6 different from the phase of the light passing through the light transmitting portion 6, the boundary utilizing the canceling action of the light passing near the boundary between the light transmitting portion 6 and the semi-transparent layer 5 is used. The contrast of the portion can be maintained well.

The region I is a transfer region, and the other region is a non-transfer region. Further, the region I ′ is a light passage region of the aperture of the stepper when the halftone phase shift mask 1 is used as a reticle of the stepper. In this embodiment, the light-shielding layer 7 is formed in a non-transfer area other than the transfer area I.

Thus, when the halftone phase shift mask 1 is used as a reticle of a stepper, the light transmission area I 'of the aperture of the stepper and the transfer area I of the halftone phase shift mask 1 as a reticle are used. Even if there is a slight shift between the exposure light and the non-transfer area of the halftone type phase shift mask 1, the exposure light protrudes to the non-transfer area and is irradiated. Can not do it. This makes it possible to completely prevent the unnecessary exposure light from reaching the non-transfer area on the transfer object, and there is a slight shift between the light passage area of the aperture and the transfer area of the halftone phase shift mask. In this case, it is possible to prevent the occurrence of an exposure defect based on this shift.

The transparent substrate 2 is a quartz glass substrate whose main surface is mirror-polished (dimensions: 6 inches long × 6 inches wide × 0.3 mm thick).
25 inches).

The low transmittance layer 3 constituting the semi-transparent layer 5 is a Cr film having a thickness of 21 nm, and has a transmittance of 15% for exposure light having a wavelength of 365 nm. The high transmittance layer 4 is
SOG (coated glass; spin-on) with a film thickness of 380 nm
Glass) film, and the phase of exposure light having a wavelength of 365 nm is 1
Shift by 80 °.

The light-shielding layer 7 has a thickness of 80 made of Cr.
nm film.

Next, with reference to FIGS. 3 to 11, a description will be given of a manufacturing process of the halftone type phase shift mask 1 having the above-described configuration.

First, a low transmittance film 3a made of Cr is formed on the transparent substrate 2 by a sputtering method. next,
Onto the low transmittance film 3a, a coating solution for forming a SiO2 based coating film (Acuglass # 311 spin-on glass (trade name) manufactured by Allied Signal Co., Ltd.) was dropped, spread over the entire surface by spin coating, and then fired. The organic compound of the binder is volatilized to form a high transmittance film 4a composed of an SOG (spin-on-glass) film, and a semi-transparent film 5a composed of a low transmittance film 3a and a high transmittance film 4a. I do. Next, a Cr film having a thickness of 8 is formed on the high transmittance film 4a by sputtering.
A light-shielding film 7a is formed by forming a film with a thickness of 0 nm. Next, a positive-type electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is applied on the light-shielding film 7a to a thickness of 500 nm and baked to form a resist film 8a (see FIG. 3).

Next, the resist film 8a in the transfer region on the transparent substrate 2 is subjected to electron beam exposure in a desired pattern (see FIG. 4).

Next, a resist pattern 8 is formed by developing the exposed resist film 8a with a developing solution, and the resist pattern 8 is used as a mask to form a light-shielding film 7a.
is etched with a predetermined etchant to form a light-shielding film pattern 7b (see FIG. 5), and then the high transmittance film 4a is dry-etched (see FIG. 6). The dry etching of the high transmittance film 4a is performed using a reactive dry etching (RIE) parallel plate dry etching apparatus under the following conditions. Etching gas: mixed gas of CF4 and O2 Gas pressure: 0.1 Torr High frequency output: 200 W

Next, after the resist pattern 8 is peeled off (see FIG. 7), a positive type electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is coated on the surface of the transparent substrate 2 with a film thickness of 500.
nm and baked to obtain an electron beam resist film 9
is formed (see FIG. 8), and then the electron beam resist film 9a is subjected to electron beam exposure for forming the light shielding layer 7 (see FIG. 9).

Next, the electron beam resist film 9a is developed to form a resist pattern 9 in a region that does not contribute to the phase shift effect (see FIG. 10).

Thereafter, using the resist pattern 9 as a mask, the exposed portions of the light-shielding film pattern 7b and the low transmittance film 3a are etched with a predetermined etching solution to remove the exposed portions of these films (FIG. 11). Then, the remaining resist pattern 9 is removed to obtain the halftone type phase shift mask 1 (see FIG. 1).

FIG. 12 is a diagram showing a comparison between the transfer characteristics of the halftone type phase shift mask 1 of the first embodiment and the transfer characteristics of the conventional halftone type phase shift mask. In the graph of FIG. 12, the vertical axis is the light intensity on the transfer substrate, and the horizontal axis is the pattern dimension (unit;
μm). The solid line curve in the figure is an example, and the dashed line curve is a comparative example. These curves show simulations of light intensity when a pattern is transferred to the surface of the substrate to be transferred by a 1/5 reduction projection type stepper using each halftone type phase shift mask. The dimension W1 of the pattern (light-transmitting portion) of the halftone type phase shift mask is 2.5 μm.
m, the dimension W2 of the part performing the phase shift function is 2.0 μm
m. The dimension W1 'on the transfer substrate is 0.5 .mu.m.
m and W2 'are 0.4 .mu.m.

As can be seen from FIG. 12, when the halftone type phase shift mask of this embodiment is used, the light intensity becomes zero near the boundary between the light transmitting portion 6 and the semi-light transmitting layer 5, and the contrast is high. Further, in a region that does not contribute to the canceling action of the exposure light, the light intensity becomes zero, thereby completely preventing the exposure light from leaking. Therefore, it is possible to obtain a resist pattern with a small film loss on the transferred substrate. Moreover, as is apparent from FIG.
The light intensity of the exposure light having passed through (W1) on the substrate to be transferred is higher in the present example than in the comparative example, and further, within the region of the semi-light-transmitting part, the light-transmitting part and the semi-light-transmitting part (W2) near the boundary with the part and contributing to the offset of the exposure light
Since the light intensity of the exposure light having passed through the substrate on the transfer-receiving substrate is smaller in this embodiment, this embodiment is also advantageous in this respect from the viewpoint of improving the contrast.

In this embodiment, since the boundary between the transfer region and the transfer region on the phase shift mask is also covered with the light shielding layer, it is possible to prevent an unnecessary image from being formed on the transfer substrate. it can.

In this embodiment, the low transmittance layer 3 has a thickness of 2
Although a very thin film of 1 nm is formed, a pinhole is likely to be generated.
Covers most of the semi-translucent layer 5,
Even if a pinhole is generated in the low transmittance layer 3, it is possible to prevent an unnecessary image from being formed at the time of pattern transfer.

In this embodiment, since the same material (Cr) is used for the low transmittance layer 3 and the light shielding layer 7,
The second etching and the etching of the low transmittance layer 3 can be performed simultaneously, and the process can be simplified.

In this embodiment, the low transmittance layer 3 may be made of a material containing chromium, such as chromium oxide, chromium nitride, or chromium carbide, in addition to chromium, or molybdenum, tantalum, or molybdenum. Tungsten may be a material containing silicon, or a material containing nitrogen and / or oxygen.

In addition to the chromium, the light-shielding layer 7 may be, for example, a material containing molybdenum containing silicon, or a film of titanium, aluminum, tungsten, or the like. Also,
The low transmittance layer 3 and the light shielding layer 7 do not necessarily need to be made of the same material.

The light transmittance of the semitransparent layer 5 is usually 1
It is sufficient if it is in the range of 50% to 50%, and practically 5% to 15% is often used.

(Embodiment 2) FIG. 13 shows Embodiment 2 of the present invention.
14 to 20 are cross-sectional views of a halftone type phase shift mask according to the second embodiment. Hereinafter, Embodiment 2 will be described with reference to these drawings. Note that, in this embodiment, since the configuration of the other points except that the semi-translucent layer 5 in the first embodiment is formed of a single layer is almost the same, the following description has the same functions as those of the first embodiment. The fulfilled portions are denoted by the same reference numerals, and a part of the description is omitted.

In this embodiment, the translucent layer 5 is a 180-nm-thick oxynitride MoSi film having a wavelength of 365 nm.
The transmittance for the exposure light of nm is 8%, and the phase of the exposure light is shifted by 180 °.

The light shielding layer 7 is made of Cr and has a thickness of 80 n.
m, which is formed in a region that does not contribute to the phase shift effect.

The halftone type phase shift mask 1 having this configuration can be manufactured as follows.

First, using a molybdenum silicide target on a transparent substrate 1, a single-layer semi-transparent film 5 made of MoSi oxynitride by a reactive sputtering method using an Ar + O2 + N2 gas to simultaneously control the transmittance and the phase difference.
a is formed. Next, Cr is formed to a thickness of 80 nm on the semi-translucent film 5a by a sputtering method to form a light-shielding film 7a. Next, a positive electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is formed on the light-shielding film 7a to a thickness of 5 nm.
It is applied to a thickness of 00 nm and baked to form an electron beam resist film 8a (see FIG. 14).

Next, the electron beam resist film 8 on the transparent substrate 1
a is subjected to electron beam exposure in a desired pattern (see FIG. 15).

Next, the exposed electron beam resist film 8a
Is developed and baked to form a resist pattern 8,
Next, using the resist pattern 8 as a mask, the light-shielding film 7a is etched with a predetermined etching solution to form a light-shielding film pattern 7b (see FIG. 16).

Next, after etching the semi-transparent film 5a,
The resist pattern 8 is removed (see FIG. 17). The etching of the semi-translucent film 5a is performed under the following conditions using a parallel plate type dry etching apparatus of a reactive ion etching type. Etching gas: mixed gas of CF4 and O2 Gas pressure: 0.1 Torr High frequency output: 200 W

Next, a positive type photoresist (AZ-1350: manufactured by Sibley) is applied to a thickness of 600 nm on the entire surface of the substrate, and baked to form a photoresist film 9a (see FIG. 18).

Next, the whole surface is exposed from the back surface of the transparent substrate 1 and exposed using the light-shielding film pattern 7b as a mask (see FIG. 19). At this time, the irradiation amount is set to be larger than that for obtaining a pattern having the same dimensions as the light-shielding film pattern 7b so that the line width of the portion to be patterned is increased. Next, the photoresist 9a is developed, and the light-shielding film pattern 7b is etched with a predetermined etchant using the resist pattern as a mask. At this time, it is also important to make the etching time longer than usual patterning by increasing the exposure amount. Thereafter, the resist is peeled off to obtain the halftone phase shift mask 1 of the second embodiment (see FIG. 13).

According to this embodiment, similarly to the first embodiment, a resist pattern having a high contrast and a small film loss can be obtained, and the boundary between the transfer region and the non-transfer region on the phase shift mask can be formed. Since it is covered with the light shielding layer, it is possible to prevent an unnecessary image from being formed on the transfer target substrate.

Since the semi-light-transmitting layer 5 is made of oxynitride MoSi and the light-shielding layer 7 is made of chromium, both are not etched at the time of etching.

In this embodiment, MoSi oxynitride is used as the semi-transmissive layer and chromium is used as the light-shielding layer. However, the semi-transmissive layer is not limited to this, and one layer can have a predetermined transmittance and phase difference. Any material that can be used as a semi-transparent film, such as a chromium oxide, nitride, fluoride, carbide, or a mixture thereof, or a material in which a light absorbing material is mixed with silicon oxide, may be used as long as it has a film material. be able to. However, when the method as in this embodiment is used, it is necessary to select a material that is resistant to the etching environment of the translucent layer and the light shielding layer.

Further, in the above embodiment, in the back exposure step, the irradiation amount of the back exposure was increased in order to form a light shielding film at a predetermined position. However, as shown in FIG. The reflection substrate 11 in which a high reflection film 13 such as a chromium film is formed on the substrate 12 is disposed so as to face the boundary between the light transmission part on the semi-transmission layer 5 using the reflection effect. May be exposed.

Hereinafter, representative modified examples of the present invention will be described.

In the phase shift mask 1 shown in FIG. 21, the transparent substrate 2 is directly etched to form a part of the transparent substrate into the high transmittance layer 4, and the low transmittance layer 3 is formed on the high transmittance layer 4.
And a light shielding layer 7 is formed on a portion of the low transmittance layer 3 which does not contribute to the phase shift function.

The phase shift mask 1 shown in FIG. 22 has a light shielding layer 7 provided at a predetermined position on a transparent substrate 2 and a single semi-transparent layer 5 formed at a predetermined position thereon. is there.
Note that the semi-transparent layer 5 may have a two-layer structure of a high transmittance layer and a low transmittance layer.

In the present invention, the position where the light-shielding layer is provided is preferably set so that W2 'on the transfer-receiving substrate is as small as possible in the range of 0.2 μm or more.
In other words, when using a 1/5 reduction projection type stepper,
It is preferable that W2 on the mask is as small as possible in the range of 1 μm or more. By making W2 as small as possible, light leakage in the semi-transmissive portion can be minimized. However, when W2 is 1 μm or less, it adversely affects the canceling action near the boundary between the semi-transmissive portion and the translucent portion. This is because there is a possibility. However, since the precision of the dimension (W1) of the pattern is determined by the precision of the dimension of the semi-transparent portion, the precision of the dimension (W1) of the light shielding layer is not so required. Further, a feature of the present invention is (Structure 1) a mask for transferring a fine pattern, wherein a mask pattern formed in a transfer region on a transparent substrate is made transparent by transmitting light having an intensity substantially contributing to exposure. A light portion and a semi-light-transmitting portion that transmits light of an intensity that does not substantially contribute to exposure, and shifts the phase of light passing through the semi-light-transmitting portion to shift the phase of light passing through the semi-light-transmitting portion. By making the phase and the phase of the light passing through the light-transmitting portion different, the contrast at the boundary portion is favorably improved by using the canceling action of the light passing near the boundary between the light-transmitting portion and the semi-light-transmitting portion. In a halftone type phase shift mask capable of being held, at least in the mask pattern transfer region, a semi-transmissive material that does not substantially contribute to a light canceling action near a boundary between the translucent portion and the semi-transmissive portion. A light shielding layer is provided above or below the light section. As a mode of the configuration 1 characterized by the above, (Configuration 2) In the halftone type phase shift mask of the configuration 1, the non-transfer area adjacent to the boundary between the mask pattern transfer area and the non-transfer area is cut in half. Transparent part,
In addition, a light-shielding portion having a predetermined width or more is provided in the semi-transmissive portion of the non-transfer area. Further, the halftone phase shift mask blank according to the present invention,
(Structure 3) A halftone type phase shift mask blank used as a material when manufacturing the halftone type phase shift mask of Structure 1 or 2, wherein a semi-light-transmitting portion is formed on a transparent substrate. A light-shielding film that forms a light-shielding layer above or below the semi-translucent film. According to the above configuration 1, the light-shielding layer is provided at least in the mask pattern transfer region and in the semi-transmissive portion that does not substantially contribute to the light canceling action near the boundary between the translucent portion and the semi-transmissive portion. Thereby, it is possible to suppress the leakage of the exposure light in that portion. Therefore, the film loss of the resist can be reduced. In this case, the pattern accuracy of the mask pattern is determined by the pattern accuracy of the semi-transmissive portion, and the pattern accuracy of the light shielding layer and its thickness accuracy are not so required, so that the design and formation thereof are relatively easy. Therefore, it is possible to almost completely prevent exposure light leakage, which is a disadvantage of the halftone type phase shift mask, while making use of the original advantages. In addition, according to the above configuration, the light intensity of the exposure light passing through the light-transmitting portion on the non-transfer substrate becomes larger than before, and furthermore, in the region of the semi-light-transmitting portion, the light-transmitting portion and the light-transmitting portion It has been confirmed that the light intensity on the non-transfer substrate of the exposure light that passed through the region near the boundary with the portion and did not contribute to the exposure light canceling effect was smaller than before, and the effect of improving the contrast of the actual transfer pattern Has been confirmed to be significant. Also,
According to the configuration 2, the non-transfer area adjacent to the boundary between the mask pattern transfer area and the non-transfer area is a semi-transmissive part, and the semi-transmissive part of the non-transfer area has a light shielding having a predetermined width or more. When the halftone type phase shift mask is used as a reticle of a stepper, there is a slight gap between the light passage area of the aperture of the stepper and the transfer area of the halftone type phase shift mask as a reticle. Even if there is a shift, even if the exposure light protrudes to the semi-transmissive portion in the non-transfer area of the phase shift mask and is applied, the protruded exposure light is blocked by the light shielding portion and cannot be transmitted. This allows
Unnecessary exposure light can be completely prevented from reaching the non-transfer area on the transfer target, and when there is a slight shift between the light passing area of the aperture and the transfer area of the halftone phase shift mask. In addition, it is possible to prevent the occurrence of exposure defects due to this shift. Furthermore, according to Configuration 3, a halftone phase shift mask blank that can easily manufacture the halftone phase shift mask of Configuration 1 or 2 is obtained.

As described in detail above, the halftone type phase shift mask according to the present invention has a light canceling action at least in the mask pattern transfer region and in the vicinity of the boundary between the light transmitting portion and the semi-light transmitting portion. By providing the light shielding layer in the semi-transmissive portion that does not substantially contribute, leakage of exposure light in that portion can be suppressed. Therefore, the film loss of the resist can be reduced. In this case, the pattern accuracy of the mask pattern is determined by the pattern accuracy of the semi-transmissive portion, and the pattern accuracy of the light shielding layer and its thickness accuracy are not so required, so that the design and formation thereof are relatively easy. Therefore, it is possible to almost completely prevent exposure light leakage, which is a disadvantage of the halftone type phase shift mask, while making use of the original advantages.

The non-transfer area adjacent to the boundary between the mask pattern transfer area and the non-transfer area is defined as a semi-transmissive section, and a light-shielding section having a predetermined width or more is formed in the semi-transparent section of the non-transfer area. With this arrangement, when this halftone phase shift mask is used as a reticle of a stepper, there is a slight shift between the light passage area of the aperture of the stepper and the transfer area of the halftone phase shift mask as the reticle. Therefore, even if the exposure light protrudes and irradiates the semi-transmissive portion in the non-transfer area of the phase shift mask, the protruding exposure light is blocked by the light shielding portion and cannot be transmitted. This allows
Unnecessary exposure light can be completely prevented from reaching the non-transfer area on the transfer target, and when there is a slight shift between the light passing area of the aperture and the transfer area of the halftone phase shift mask. In addition, it is possible to prevent the occurrence of exposure defects due to this shift.

Further, according to the halftone type phase shift mask blank of the present invention, a halftone type phase shift mask blank from which the halftone type phase shift mask according to the present invention can be easily manufactured is obtained.

As described above in detail, according to the present invention, a light-shielding film made of a material having resistance to the etching environment of the material constituting the semi-transparent film is provided on the semi-transparent film. This makes it possible to form a separate pattern on each of the semi-transparent film and the light-shielding film so that the other is not etched when one is etched. Thus, while the light-shielding portion provides more complete light-shielding, its function can be exerted in a portion that performs a phase shift action.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a halftone type phase shift mask according to a first embodiment of the present invention, and is an end view taken along a line II of FIG. 2;

FIG. 2 is a plan view of the halftone phase shift mask according to the first embodiment.

FIG. 3 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 4 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 5 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 6 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 7 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 8 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 9 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 10 is an explanatory diagram of a manufacturing process of the halftone type phase shift mask according to the first embodiment.

FIG. 11 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the first embodiment.

FIG. 12 is a diagram showing a comparison between transfer characteristics of a halftone phase shift mask 1 of Example 1 and transfer characteristics of a conventional halftone phase shift mask.

FIG. 13 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 14 is an explanatory diagram of a manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 15 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 16 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 17 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 18 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 19 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 20 is an explanatory diagram of the manufacturing process of the halftone phase shift mask according to the second embodiment.

FIG. 21 is a diagram showing a modification of the present invention.

FIG. 22 is a diagram showing a modification of the present invention.

FIG. 23 is an explanatory diagram of a conventional example of the present invention.

FIG. 24 is an explanatory diagram of a conventional example of the present invention.

FIG. 25 is an explanatory diagram of a conventional example of the present invention.

FIG. 26 is an explanatory diagram of a conventional example of the present invention.

FIG. 27 is an explanatory diagram of a conventional example of the present invention.

FIG. 28 is an explanatory diagram of a conventional example of the present invention.

[Explanation of symbols]

1. Half-tone type phase shift mask, 2. Transparent substrate,
3 ... low transmittance layer, 4 ... high transmittance layer, 5 ... semi-transparent layer, 6 ...
Light-transmitting portion, 7 ... light-shielding layer.

Claims (6)

[Claims] 1. A halftone type phase shift mask blank having a semi-transmissive film made of a single layer for transmitting light having an intensity substantially not contributing to exposure and shifting the phase of the transmitted light on a transparent substrate. A halftone phase shift mask blank, comprising a light-shielding film made of a material having resistance to an etching environment of a material constituting the semi-light-transmitting film, on the semi-light-transmitting film. 2. The semi-transparent film according to claim 1, wherein the light absorbing material is mixed with molybdenum oxynitride, chromium oxide, chromium nitride, chromium fluoride, chromium carbide, a mixture of these chromium compounds, or silicon oxide. 2. The halftone type phase shift mask blank according to claim 1, wherein the halftone type phase shift mask blank is made of a material whose main component is a mixed material. 3. A material forming the semi-light-transmitting film is a molybdenum oxynitride silicide film, and a material having resistance to an etching environment of the semi-light-transmitting film is a material containing chromium. The halftone type phase shift mask blank according to claim 1 or 2, wherein: 4. A halftone type phase having a pattern of a semi-transmissive film composed of a single layer that transmits light having an intensity substantially not contributing to exposure and shifts the phase of the transmitted light on a transparent substrate. A method for manufacturing a halftone phase shift mask for manufacturing a shift mask, comprising: a halftone having, on a transparent substrate, a semi-transparent film and a light-shielding film made of a material resistant to an etching environment of the semi-transparent film. A resist pattern forming step of forming a resist pattern on a light shielding film of the halftone type phase shift mask blank using a mold phase shift mask blank, and etching the light shielding film using the resist pattern as a mask. Forming a light-shielding film pattern, and masking the resist pattern and the light-shielding film pattern. A semi-transparent film pattern forming step of forming a semi-transparent film pattern by etching the semi-transparent film, and a resist removing step of removing a resist pattern remaining after the semi-transparent film pattern forming step. A method for manufacturing a halftone type phase shift mask, comprising: 5. An etching for removing a part of the light shielding film pattern after the semi-translucent film pattern forming step,
The method for manufacturing a halftone phase shift mask according to claim 4, further comprising a step of removing a light-shielding film at least in a portion performing a phase shift function in a transfer region. 6. A halftone type phase shift mask manufactured using the method according to claim 4. Description: