JPH06258816A - Phase shift mask manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] Forming phase shifter for phase shift mask
Highly selective etching of transparent film for glass substrate
Perform in a dry process while maintaining selectivity. [Structure] A Cr light-shielding film 2 formed on a glass substrate 1
Thin SiO coated_xN _yForm the stop layer 3 and
SiO_xFlatten with transparent film 4 and form resist mask 5
To achieve. SiO_xN_yStop layer 3 and SiO₂Deflection of transparent film 4
Fold rates should be the same. S₂F₂SiO using gas₂
When the transparent film 4 is etched, SiO_xN _yStop layer 3
When exposed, the dangling of N atoms generated on the surface
Free S (sulfur) in plasma is bound to the long bond
Mainly polythiazil (SN) _xSurface protection consisting of
A film is formed and high selectivity is achieved. After this, SiO
_xN _yThe exposed portion of the stop layer 3 is also removed by etching, and the phase shift
Complete Task 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a phase shift mask used as a photomask (reticle) for photolithography in the field of manufacturing semiconductor devices, and more particularly to etching a phase shifter on a transparent substrate. The present invention relates to a method capable of performing dry etching while ensuring a high selection ratio for a transparent substrate.

[0002]

2. Description of the Related Art In the field of semiconductor integrated circuits, sub-micron level processing has already been realized in mass-production plants, and quarter-micron level processing will become essential in the future half-micron level and further in the 64-Mbit DRAM class.
Research on level processing is underway.

Photolithography is a key technology for the progress of such fine processing, and the conventional progress has been achieved mainly by improving the optical system of the stepper (reduction projection exposure apparatus). The limit resolution R of this optical system is represented by the following equation known as the Rayleigh equation. R = k ₁ × λ / NA where k ₁ is a proportional constant determined by the resist material and process, λ is the exposure wavelength, and NA is the numerical aperture of the reduction projection lens. Conventionally, i-line (365 nm) of high pressure mercury lamp
Alternatively, efforts are being made to shorten the exposure wavelength represented by the use of far ultraviolet rays such as KrF excimer laser light (248 nm) and to increase the numerical aperture (NA) of the reduction projection lens of the stepper (reduction projection exposure apparatus). It has come off. However, these improvements have practically reached the limit. In addition, shortening the wavelength and increasing the numerical aperture require DOF (= k ₂ × λ / N).
A ^2: k ₂ is because it leads to a decrease in the proportional constant), there is a limit to the pursuit of critical resolution R.

Under such circumstances, a so-called super-resolution technique has been attracting attention, in which the numerical aperture NA is suppressed to a certain level and a practical level of depth of focus is secured, and then the harmonic component of the exposure light is used to increase the resolution. There is. One of this super-resolution technology,
There is a phase shift method. This is a method for improving the resolution by giving a phase difference to the exposure light transmitted through the photomask and utilizing the mutual interference of the transmitted light. This phase difference is usually set to 180 °, that is, the inverted state.

The principle of resolution improvement by the phase shift method is roughly classified into spatial frequency modulation and edge enhancement, and various kinds of phase shift masks have been proposed by combining these principles and a mask structure. Typical examples thereof include a Levenson type phase shift mask, a phase shift mask with an auxiliary pattern, a self-aligned phase shift mask, and a transmission type phase shift mask.

In the phase shift method, in order to generate a phase difference, it is necessary to form a phase shifter in a specific pattern on a glass substrate which constitutes a reticle. This phase shifter is most commonly formed by patterning a transparent film such as SOG (spin on glass) having a refractive index different from that of the glass substrate. As another type of phase shifter, there is one in which a groove portion is formed by etching the glass substrate itself in a predetermined pattern. In this case, since only the depth of the groove is replaced with the air layer having a different refractive index from the glass substrate, a phase difference occurs between the light transmitted through the groove and the light transmitted around it. However, it is easier to control the film thickness of the transparent film than to control the etching depth of the groove.

[0007]

By the way, in the case of patterning a transparent film on a transparent substrate, a conventional general method is to perform etching by an electron beam resist material by direct writing and development processing by an electron beam writing apparatus.・
A mask is formed and etching is performed through this mask. As the etching method at this time, wet etching was the mainstream.

However, if the design rules of semiconductor devices are further miniaturized in the future, it can be said that the pattern size on the reticle is five times larger than that on the semiconductor wafer.
Significantly reduced than before. In such a case, in order to realize a sharp phase inversion at the edge portion of the phase shifter, it becomes necessary to control the cross-sectional shape of the phase shifter to a good anisotropic shape. From this point of view, dry etching that can achieve anisotropic processing by an ion assist mechanism is more advantageous than wet etching in which an isotropic etching reaction proceeds.

Further, when the pattern on the reticle becomes finer, when the transparent substrate is immersed in the etching solution in wet etching, the Cr light-shielding film and the transparent substrate are not sufficiently adhered to each other, resulting in the Cr light-shielding film. May peel off,
From this viewpoint as well, there is an increasing need to consider dry etching.

Further, as an essential problem in the etching of the phase shifter, since the transparent substrate and the phase shifter are often made of the same type of material, it is difficult to secure sufficient selectivity between them. Is mentioned. In order to deal with this problem, SnO is provided between the transparent substrate and the transparent film.
It has been proposed to interpose an etching stop layer made of ₂ (tin oxide) or the like. However, even with this technology, sufficient selectivity has not yet been achieved, and the actual situation is that the results are not as good as the cost increase accompanying the increase in the number of processes.

Therefore, the present invention ensures a sufficiently large selection ratio for a transparent substrate by dry etching,
An object of the present invention is to provide a method of manufacturing a phase shift mask, which is capable of forming a phase shifter by etching a transparent film.

[0012]

The method of manufacturing a phase shift mask of the present invention is proposed to achieve the above-mentioned object, and a transparent film is etched on a transparent substrate to form a desired pattern. When forming a phase shifter having, an etching stopper layer containing nitrogen as a constituent element is provided between the transparent substrate and the transparent film in advance, and releases free sulfur into plasma under discharge dissociation conditions. The transparent film is etched using an etching gas containing the obtained sulfur-based compound, and the sulfur nitride-based compound is deposited on the exposed surface of the etching stopper layer near the end point of this etching.

The present invention also provides that the sulfur compound is S ₂
It is characterized in that it is at least one kind of sulfur fluoride selected from F ₂ , SF ₂ , SF ₄ , and S ₂ F ₁₀ .

The present invention is also characterized in that the sulfur compound has a thiocarbonyl group and a halogen atom in the molecule.

The present invention also provides that the etching gas comprises:
It is characterized by containing at least one halogen / radical consuming compound selected from H ₂ , H ₂ S and silane compounds.

The present invention is also characterized in that both the transparent substrate and the transparent film are made of a SiO _x material.

The present invention is further characterized in that the transparent film and the etching stopper layer have substantially the same refractive index, and the exposed etching stopper layer is also removed after the etching of the transparent film is completed.

[0018]

In the present invention, it is assumed that the transparent substrate and the transparent film for obtaining the phase shifter are mainly formed of SiO _x type material as in the conventional case, and the sulfur (S) released in the plasma under discharge dissociation conditions is used. The two points are to use an etching gas containing a sulfur-based compound capable of releasing oxygen and to provide a material layer having nitrogen as a constituent element as an etching stop layer between the transparent substrate and the transparent film.

S is a sublimable substance which can be removed without leaving any contamination when heated to about 90 ° C. under a reduced pressure such that ordinary etching is carried out. However, the temperature of the substrate is preferably lower than this. It is also a depositable substance that deposits on the surface and protects the surface if it is controlled at room temperature or lower.

Here, the site where S can be deposited on the surface of the substrate is the site where vertical incidence of ions does not occur or a large amount of oxygen (O) atoms are not supplied due to etching. These parts mean the phase shift of the present invention.
Considering the mask manufacturing process, the pattern side wall surface, the upper surface and side wall surface of the resist mask, the exposed surface of the etching stop layer, and the like. Such deposition of S achieves the anisotropic shape of the phase shifter and ensures high selectivity to the resist mask.

On the contrary, the site where S cannot be deposited is the ion normal incidence surface of the SiO _x -based material layer which releases a large amount of O atoms with etching. That is, at this site, S combines with sputtered out O atoms to produce SO _x , which is burned and removed. Therefore, the etching of the SiO _x material layer proceeds smoothly. After the etching is completed, S can be easily burned and removed in the ashing step for removing the resist mask. Therefore, S does not cause any particle contamination.

When the etching further progresses and the etching stopper layer containing nitrogen as a constituent element begins to be exposed, a sulfur nitride compound is formed on the surface thereof. Regarding the use of a sulfur nitride-based compound for the surface protection of a substrate during etching, the applicant of the present invention has previously filed Japanese Patent Application No. 3-15545.
It is as first proposed and detailed in No. 4 specification.

In the present invention, a typical sulfur nitride compound expected to have a side wall protecting effect is polythiazyl (S).
N) _x . This polymer is S--N-- in the crystalline state.
It has a structure in which covalently bonded chains having a repeating structure of S-N -... are oriented in parallel, and shows higher resistance to attack of etching species than S of simple substance. In the system in which F ^* is present in plasma, thiazyl fluoride in which a halogen atom is bonded to the S atom of the above (SN) _x can be produced, and in the system in which H ^* is present, thiazyl hydrogen can be produced.

Further, depending on the conditions, a cyclic sulfur nitride compound in which the number of S atoms and N atoms in the molecule are unbalanced, or an imide type compound in which an H atom is bonded to the N atom of these cyclic sulfur nitride compounds is also produced. It is possible.

Although depending on the conditions, the sulfur nitride compound can be deposited on the surface of the substrate if the substrate is maintained at a temperature lower than about 130.degree. Moreover,
Since it is easily removed by a mechanism such as sublimation, decomposition, and combustion in a usual ashing process performed after the end of etching, it does not cause any particle contamination.

Regarding the deposition of S and sulfur nitride compounds
As described above, SiO _xOne of the transparent films
In order to remove Si, which is a constituent element of
High energy bond between radicals, especially Si atoms
Can generate F^*Exists in the etching reaction system
It is convenient. S used in the present invention₂F₂, SF₂, S
F_Four, S₂F_TenThe four types of sulfur fluoride are
The compound selected from the viewpoint,
It is proposed in Kaihei 4-84427. this
Produced from sulfur fluoride^*Is SiO_xInside S
i atom is SiF_xVolatilized in the form of.

The other of the sulfur compounds proposed in the present invention is a compound having a thiocarbonyl group (> C = S) and an F atom in the molecule. In addition to the above-described S as a depositable substance, this compound can also generate a carbon-based polymer. This carbon-based polymer has much higher etching resistance than the fluorocarbon-based polymer that has played the role of protecting the side wall in the conventional dry etching. This is because the C—S bond (69) is larger than the C—F bond (536 kJ / mol) in the comparison of interatomic bond energies.
(9 kJ / mol) is incorporated into the molecular structure, and thiocarbonyl having a dipole is incorporated into the molecular structure, which increases the electrostatic adsorption force to the negatively charged substrate during etching. It depends on the reason such as being present.

In the present invention, a method for further improving the selectivity
As H for the etching gas ₂, H₂S, silane
At least one F selected from the group of compounds^*Added
To improve the production efficiency of S or sulfur nitride compounds.
Suggest that. These F^*Release from consumable compounds
H done^*And / or Si^*Is F^*Capture the
It is removed from the etching reaction system by changing it to a highly emissive compound.
Play the role of leaving. Therefore, the etching reaction system
Apparent S / F ratio (ratio of the number of S atoms to the number of F atoms) rises
However, the surface protection effect can be enhanced.

By the way, the phase shifter formed in the present invention is not composed only of the transparent film, and the etching stop layer thereunder is also patterned to form a part thereof. Generally, the phase shifter film thickness d required to invert the phase by 180 ° in the phase shift mask
Is represented by d = λ / 2 (n−1) (λ is the exposure wavelength and 1 is the refractive index of air). That is, the film thickness d depends on the refractive index n. The etching stop layer is generally a thin layer, but if it is formed by coating a Cr light-shielding film, for example, the film thickness when viewed in a direction perpendicular to the photomask substrate locally varies. In such a case, if the etching stop layer and the transparent film have different refractive indices, it becomes extremely difficult to design the film thicknesses of the two, and there is a great possibility that the manufacture of the phase shift mask itself becomes impractical.

Therefore, as a practical process, it is proposed to make the refractive indexes of the etching stop layer and the transparent film substantially the same. By doing so, both of these material layers can be handled as a single material layer, and the phase shifter can be easily designed by keeping the total thickness of both materials constant. That is, in the manufacturing process, when the transparent film is formed, the surface of the substrate may be flattened by the transparent film.

[0031]

EXAMPLES Specific examples of the present invention will be described below based on experimental results.

Example 1 This example is a process for manufacturing a Levenson type phase shift mask.
In this case, SiO on the glass substrate_xN_yThrough the stop layer
Formed by SiO_xTransparent film, S₂F₂Using
This is an example of ching. This process is shown in FIG.
I will explain. In this example, etching sample
The mask substrate used as is shown in FIG. this
The mask substrate is provided on the glass substrate 1 with the openings 2a separated from each other.
And a Cr light-shielding film 2 formed in a predetermined pattern.
Furthermore, the entire surface of the substrate is thin and SiO _xN_yCoated on stop layer 3
And the entire surface is SiO_xFlattened by transparent film 4
And the SiO_xAs an etching mask on the transparent film 4
The resist mask 5 is formed in a predetermined pattern
It is a thing.

Here, the SiO _x N _y stop layer 3 is formed, for example, by performing plasma CVD under the following conditions. SiH ₄ flow rate 350 SCCM NH ₃ flow rate 10-50 SCCM O ₂ flow rate 100-200 SCCM gas pressure 1000 Pa RF power density 3.1 W / cm ² (13.56)
MHz) Substrate temperature 300 ° C. The refractive index n of the SiO _x N _y stop layer 3 formed by this process was about 1.45.

On the other hand, the SiO _x transparent film 4 is formed, for example, by performing ECR-CVD under the following conditions. SiH ₄ flow rate 10 SCCM O ₂ flow rate 20 SCCM Ar flow rate 10 SCCM Gas pressure 0.1 Pa Microwave power 800 W (2.45 GHz) Substrate temperature 300 ° C. Refractive index n of SiO _x transparent film 4 formed by this process
Is about 1.45, and the refractive index n of the SiO _x N _y stop layer 3 is
I was able to match.

As described above, it is necessary to match the refractive indexes of the SiO _x N _y stop layer 3 and the SiO _x transparent film 4 with each other. This SiO _x N _y stop layer 3 is also the phase shifter 6 finally. [See FIG. 1 (c). ] Is a part of the above.
If the refractive indices do not match, the layer thickness of the SiO _x N _y stop layer 3 as viewed in the direction perpendicular to the glass substrate 1 at the edge of the opening 2a (that is, the portion in contact with the Cr light shielding film 2) is Since it is large, the amount of phase shift goes wrong in this part.

In the case of the present embodiment, the film thickness d of the phase shifter 6 is set such that the SiO _x N _y stop layer 3 and the Si in the opening 2 a are the same.
It may be considered as the total thickness of the O _x transparent film 4. here,
The phase shift mask to be manufactured is an i-line stepper (λ = 3
65 nm), the above equation d = λ /
From 2 (n-1), the total thickness of both films was set to 405 nm.

The resist mask 4 is formed by adjoining Cr.
It is formed so as to cover every other opening 2a between the light shielding films 2. This is to achieve the purpose of the Levenson-type mask of inverting the phase of transmitted light by 180 ° between fine adjacent patterns in a periodic pattern such as line-and-space.

Next, the above mask substrate was set in an RF bias application type magnetic field microwave plasma etching apparatus, and as an example, the SiO _x transparent film 4 was etched under the following conditions. S ₂ F ₂ flow rate 30 SCCM Gas pressure 1 Pa Microwave power 800 W (2.45 GHz) RF bias power 30 W (2 MHz) Substrate temperature −10 ° C. (using ethanol-based refrigerant) SF generated by dissociation from S ₂ F _{2 in} this process By the ion mode etching due to the contribution of ions such as _x ⁺ , the SiO _x transparent film 4 was selectively removed in the form of SiF _x , SO _{x and the} like. Further, S was also released from S ₂ F ₂ .

The behavior of S will be described with reference to FIGS. 1 (b) and 2. FIG. 2 is an enlarged schematic view of a part of the region to be etched in FIG.
S was deposited on the pattern side wall surface on the cooled mask substrate to form the side wall protective film 7, which contributed to anisotropic processing.
On the other hand, on the ion vertical incidence surface of the SiO _x transparent film 4, since O atoms are released from this film by the sputtering action of the incident ions, S adsorbed to this portion is immediately changed to SO _x and burned and removed. . Therefore, on this exposed surface, S
Was not deposited, and the etching proceeded smoothly. Further, at the ion normal incidence surface of the resist mask 5, the deposition of S and the removal of spatter competed with each other, and a high selection ratio with respect to the resist mask 5 was secured.

As a result, the SiO _x transparent film pattern 4a having an anisotropic shape was formed.

When etching of the SiO _x transparent film 4 is almost completed and the underlying SiO _x N _y stop layer 3 is exposed, Si atoms are extracted from the surface layer portion by F ^{* in} the plasma, and dangling of the generated N atoms is performed. Free S immediately bound to the ring bond. As a result, the surface of the SiO _x N _y stop layer 3 was covered with the surface protective film 8 of a sulfur nitride based compound mainly composed of (SN) _x and protected from the attack of etching species.

Next, the side wall protective film 7 and the surface protective film 8 were removed by heating the mask substrate to 130 ° C. or higher or lightly performing O ₂ plasma ashing. Furthermore, the exposed portion of the SiO _x N _y stop layer 3 was selectively etched under the following conditions as an example.

CH ₂ F ₂ flow rate 20 SCCM CO ₂ flow rate 20 SCCM Gas pressure 1 Pa Microwave power 800 W (2.45 GHz) RF bias power 30 W (2 MHz) Substrate temperature −10 ° C. (using ethanol-based refrigerant)

The above gas composition is S on the SiO _x type material layer.
For the purpose of selectively etching the i _x N _y based material layer, the applicant of the present application is based on the technique previously disclosed in Japanese Patent Laid-Open No. 61-142744. That is, CH ₂
When a relatively large amount of CO as described above is added to a gas having a small F / C ratio (ratio of the number of F atoms to the number of C atoms in the molecule) such as F ₂ , a part of F ^* is in the form of COF. Removed by CF
In the ₂ ⁺ or ion due to the fact that F ^* recombine CF ₃ ⁺
Is suppressed. Since CF ₃ ⁺ is the main etching species of the glass substrate 1, this reduction of ions is
Will lead to a lower etching rate. On the other hand, SiO _x N
The etching of the _y stop layer 3 is performed using ions other than CF ₃ ⁺ or F
^* Proceeds sufficiently due to the above.

As a result, as shown in FIG. 1 (c),
The SiO _x N _y stop layer 3 is selectively removed without damaging the glass substrate 1, it was possible to form the SiO _x N _y stop layer pattern 3a. This SiO _x N _y stop layer pattern 3a is the above-mentioned SiO _x transparent film pattern 4a.
Together, it functions as the phase shifter 6.

After that, the mask substrate was transferred to an ashing device and ordinary O ₂ plasma ashing was performed. As a result, as shown in FIG. 1D, the resist mask 5
Was removed. In some cases, this ashing also completely removed a trace amount of S and sulfur nitride compounds remaining on the mask substrate. The phase shift mask thus formed is mounted on the i-line stepper, and the i-line (h
When ν) is incident, the phases of the transmitted light are mutually inverted between the adjacent openings 2a opened in the Cr light-shielding film 2 and the light intensity at the boundary becomes 0, which is based on the principle of spatial frequency modulation. Different patterns can be separated.

Example 2 In this example, an etching gas prepared by adding H ₂ as an F ^* consuming compound to S ₂ F ₂ used in Example 1 was used.
This is an example in which the production efficiency of S is increased to improve the selectivity. The mask substrate used in this example is the same as in Example 1. This mask substrate was set in a magnetic field microwave plasma etching apparatus, and as an example, SiO 2 was formed under the following conditions.
_{x The} transparent film 4 was etched.

S ₂ F ₂ flow rate 25 SCCM H ₂ flow rate 10 SCCM Gas pressure 1 Pa Microwave power 800 W (2.45 GHz) RF bias power 25 W (2 MHz) Substrate temperature −10 ° C. (ethanol-based refrigerant used) In the above gas system, Part of F ^* generated from S ₂ F ₂ is trapped by H ^* generated from H ₂ to generate HF (hydrogen fluoride).
, The apparent S / F ratio of the etching reaction system increased. As a result, the sidewall protection film 7 made of S
And the formation of the surface protective film 8 of the sulfur nitride compound were efficiently performed, and the selectivity was further improved as compared with the first embodiment.

The subsequent etching method of the SiO _x N _y stop layer 3 is the same as that of the first embodiment.

Example 3 In this example, SiO_xWith the etching gas for the transparent film 4
Then CSF₂Example using (thiocarbonyl fluoride)
It An example of etching conditions is shown below. CSF₂Flow rate 30SCCM Gas pressure 1Pa Microwave power 800W (2.45GHz) RF bias power 25W (2MHz) Substrate temperature -10 ° C (ethanol-based refrigerant
Use) In this etching process, SiO_xOn the exposed surface of the transparent film 4
At CSF₂Dissociated from F^*By deer
Le reaction is also CSF₂CF generated from_x ⁺, CS
⁺, SF_x ⁺Is assisted by the incident energy of ions such as
Etching progressed by the mechanism. At this time, CSF₂
At the same time, carbon-based polymer and S were also produced. these
The depositable material forms the side wall protective film 7 on the side wall surface of the pattern.
Made of SiO_xSO on the ion vertical incidence surface of the transparent film 4
_x, CO_xBurned away in the form of

Also in this example, good high selective anisotropic etching was realized.

Example 4 In this example, an etching gas in which H ₂ was added to the CSF ₂ used in Example 3 as an F ^* consuming compound was used to enhance the deposition efficiency of S and improve the selectivity. Here is an example. Using the mask substrate shown in FIG. 1A, as an example, the SiO _x transparent film 4 was etched under the following conditions.

CSF ₂ flow rate 25 SCCM H ₂ flow rate 5 SCCM Gas pressure 1 Pa Microwave power 800 W (2.45 GHz) RF bias power 25 W (2 MHz) Substrate temperature −10 ° C. (Ethanol based refrigerant used) CSF _{2 in the} above gas system Part of F ^* generated from H is consumed by H ^* , and the apparent S of the etching reaction system is
By increasing the / F ratio, the selectivity was further improved as compared with Example 3.

Although the present invention has been described based on the four examples, the present invention is not limited to these examples. For example, sulfur fluoride is S ₂ F
_{Although 2} has been described as an example, basically the same result can be obtained by using other sulfur fluorides limited in the present invention. Although H ₂ has been described as an example of the F ^* consuming compound, similar results can be obtained by using other H ₂ S or silane compounds limited in the present invention. H ₂ S is S
Since it is also a supply source of S, the effect of increasing the S / F ratio of the etching reaction system is great. In addition, since the silane-based compound contributes to the trapping of F ^* in addition to H ^* , Si ^* also contributes to S / F.
Greatly increases the ratio.

As the etching gas used in the present invention, various additive gases may be used for the purpose of changing etching characteristics. For example, when a nitrogen-based compound such as N ₂ is added, the sulfur nitride-based compound can be deposited also on the side wall surface of the pattern. Further, it is possible to obtain a cooling effect, a dilution effect and a sputtering effect by adding a rare gas such as He and Ar.

Further, in each of the above-mentioned embodiments, the production of the Levenson-type mask based on the principle of the spatial frequency modulation has been described.
As the mask, there are a transmission type phase shift mask which does not have a Cr light-shielding film and is based on the principle of spatial frequency modulation, a mask with an auxiliary pattern based on the principle of edge enhancement, and also a self-aligned mask.

Particularly, in the case of a transmission type phase shift mask having no Cr light shielding film, the etching stop layer is formed on a flat transparent substrate and has a uniform film thickness. You can leave it as it is after doing. Moreover, if this etching stop layer is considered as a part of the substrate, it is not necessary to match the refractive index with that of the transparent film.

Further, the SiO _x N _y stop layer, the transparent film and the S
It goes without saying that the film forming conditions, film thickness, exposure wavelength, etching conditions, etc. of i can be changed as appropriate.

[0059]

As is apparent from the above description, by applying the present invention, the etching of the phase shifter, which was conventionally performed mainly by wet etching, can be performed by dry etching. Therefore,
Corresponding to the future reduction of design rules of semiconductor devices, it is possible to anisotropically process a phase shifter having a fine pattern while maintaining high selectivity with respect to a transparent substrate, which is highly reliable. It becomes possible to manufacture phase shift masks.

The present invention is extremely promising as a life prolonging measure for i-line lithography, and as a result, 0.35 to 0.4 μm
It becomes possible to manufacture a semiconductor device such as a 64 Mbit DRAM or a 16 Mbit SRAM whose main pattern rule is according to the above with high reliability.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a Levenson type phase shift mask manufactured by the present invention.
An example of a process applied to manufacturing is shown according to the order of steps.
It is a schematic cross-sectional view, (a) is Cr light shielding on a glass substrate
Film, SiO_xN_yStop layer, SiO_xTransparent film, resist
A state where masks are sequentially formed, (b) is SiO_xTransparent film
(C) is SiO2_xN _ystop
Stop layer etching is completed, (d) is ashing
Shows the state where the resist mask is removed by
You

FIG. 2 is a schematic cross-sectional view showing an enlargement of a part of a region to be etched in FIG. 1 (b).

[Explanation of symbols]

1 ... Glass substrate 2 ... Cr light-shielding film 3 ... SiO _x N _y stop layer 4 ... SiO _x transparent film 5 ... Resist mask 6 ... Phase shifter 7 ... Side wall protection Membrane (S) 8 ... Surface protection film (sulfur nitride compound)

Claims (6)

[Claims] 1. A method of manufacturing a phase shift mask, wherein a transparent film laminated on a transparent substrate is etched to form a phase shifter for shifting a phase of exposure light in a desired pattern. An etching stop layer containing nitrogen as a constituent element is provided between the transparent film and the transparent film using an etching gas containing a sulfur-based compound capable of releasing free sulfur into plasma under discharge dissociation conditions. A method for manufacturing a phase shift mask, characterized in that etching is performed, and a sulfur nitride-based compound is deposited on the exposed surface of the etching stopper layer near the end point of the etching. 2. The sulfur-based compound is S ₂ F ₂ , S
_{2. The} method for manufacturing a phase shift mask according to claim 1, wherein at least one kind of sulfur fluoride selected from F ₂ , SF ₄ , and S ₂ F ₁₀ is used. 3. The method of manufacturing a phase shift mask according to claim 1, wherein the sulfur compound has a thiocarbonyl group and a fluorine atom in the molecule. 4. The etching gas is H ₂ , H ₂ .
_The method for producing a phase shift mask according to claim 1, further comprising at least one kind of fluorine radical consuming compound selected from ₂ S and silane compounds. 5. The transparent substrate and the transparent film are both made of SiO 2.
_{5. The} method of manufacturing a phase shift mask according to claim 1, wherein the phase shift mask is made of an _x- based material. 6. The transparent film and the etching stopper layer have substantially the same refractive index, and the exposed etching stopper layer is also removed after the etching of the transparent film is completed. Item 7. A method for manufacturing a phase shift mask according to any one of items 5.