TWI634381B - Method for preparing halftone phase shift photomask blank - Google Patents

Abstract

The solution of the present invention is as follows: when the electric power applied to the target is constant and the flow rate of the reactive gas introduced into the reaction chamber is scanned, the flow rate of the reactive gas and the scan of the flow rate of the reactive gas are measured. In the hysteresis curve formed by the target voltage value or the target current value, the reactive gas flow rate below the lower limit of the reactive gas flow rate in the hysteresis region and the lower limit of the reactive gas flow rate in the hysteresis region are set. And the upper limit of the reactive gas flow rate on both sides, and by reactive sputtering, a halftone phase shift film containing one or both of yttrium, nitrogen and oxygen is formed.

The effect of the present invention is as follows: in a halftone phase shift film containing yttrium and one or both selected from nitrogen and oxygen, the in-plane uniformity of optical characteristics can be improved and a predetermined phase difference can be ensured. It is possible to provide a halftone phase shift type blank mask having a halftone phase shift film having good in-plane uniformity.

Description

Method for manufacturing halftone phase shift type blank mask

The present invention relates to a method of manufacturing a halftone phase shift type blank mask of a material of a halftone phase shift type mask used for manufacturing a semiconductor integrated circuit or the like.

In the field of semiconductor technology, research and development for further miniaturization of patterns is actively underway. In particular, in recent years, with the increase in the size of large-scale integrated circuits, the miniaturization of circuit patterns, the thinning of wiring patterns, and the miniaturization of contact hole patterns for interlayer wiring of cells have also progressed. The requirements for fine processing technology are gradually increasing. Along with this, in the field of the manufacturing technology of the photomask used in the photolithography technology step in the microfabrication process, there is a gradual demand for the development of a technique for forming a finer and more accurate circuit pattern (mask pattern). .

In general, when a pattern is formed on a semiconductor substrate by photolithography, a reduction projection is performed. Therefore, the size of the pattern formed on the photomask is usually about four times the size of the pattern formed on the semiconductor substrate. The circuit pattern depicted in the field of photolithography today The size is much lower than the wavelength of the light used for exposure. Therefore, when the size of the circuit pattern is simply set to 4 times to form a reticle pattern, the original shape is not transferred to the photoresist on the semiconductor substrate due to interference of light generated during exposure or the like. The result of the film.

Therefore, by forming the pattern formed on the reticle to form a shape more complicated than the actual circuit pattern, the influence of the above-described interference of light or the like can be alleviated. The shape of the pattern is, for example, a shape in which an actual circuit pattern is subjected to an optical proximity correction (OPC: Optical Proximity Correction). In addition, in order to cope with the miniaturization and high precision of the pattern, technologies such as deformed illumination, liquid wetting technology, and double exposure (double pattern forming photolithography) have also been applied.

One of the resolution enhancement techniques (RET: Resolution Enhancement Technology), the phase shift method can be used. The phase shift method is a pattern in which a film having a phase substantially reversed by 180° is formed on a photomask, and interference of light is applied to enhance the contrast. One of the reticlees to which this method is applied is a halftone phase shift type reticle. The halftone phase shift type reticle is formed on a substrate transparent to the exposure light such as quartz to form a halftone phase shift which substantially reverses the phase by 180° and has a transmittance which does not affect the formation of the pattern. The reticle pattern of the film. A halftone phase shift type reticle has been proposed to have a halftone phase shift film composed of molybdenum oxide (MoSiO) or molybdenum oxynitride (MoSiON) (Japanese Patent Laid-Open No. Hei. 1)).

In addition, in order to obtain a more subtle image by photolithography, the exposure light source uses shorter wavelengths, and is now the most sophisticated practical. In the processing step, the exposure source was converted from KrF excimer laser light (248 nm) to ArF excimer laser light (193 nm). However, due to the use of higher energy ArF excimer laser light, it is known that the reticle damage that cannot be observed in the KrF excimer laser light is generated. One of them is the problem of an impurity-like growth defect on the reticle when the reticle is continuously used. This growth defect is called haze pollution. For this reason, the growth of ammonium sulphate crystal on the surface of the reticle pattern was originally considered, but it has been gradually considered as an organic matter.

For example, Japanese Laid-Open Patent Publication No. 2008-276002 (Patent Document 2) discloses a growth defect caused by irradiating an ArF excimer laser light for a long time in a reticle. The reticle is cleaned in a given stage and the contents of the reticle can be continuously used.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 7-140635

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-276002

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2007-33469

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2007-233179

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2007-241065

In the mask technology, as the miniaturization progresses, the pattern width becomes smaller than the exposure wavelength, so the OPC and the deformation are gradually used as described above. High resolution technology for illumination, liquid immersion exposure, phase shift method, double exposure, etc. The phase shift film, which is thinner, is not only advantageous for pattern formation, but also can reduce the three-dimensional effect, so it is advantageous. Therefore, in the photolithography technique, in order to form a finer pattern, a thinner film is required.

In addition, when a blank mask is used in the process of the mask, when impurities are present on the blank mask, the impurities become defects of the pattern, and therefore, in order to remove the impurities, the blank mask is washed in the process of the mask. many times. Furthermore, when the photomask is used in the photolithography technology step, even if the photomask itself is not defective in the pattern, in the photolithography technique step, if the impurity adheres to the photomask, the pattern is formed using the photomask. On the latter semiconductor substrate, pattern transfer failure occurs, and the mask is still washed repeatedly.

In order to remove the impurities of the blank mask or the mask, most of the cases are chemically washed by a mixture of sulfuric acid and hydrogen peroxide, or a mixture of ozone water, ammonia and hydrogen peroxide. Here, the mixture of sulfuric acid and hydrogen peroxide is a detergent having strong oxidation effect obtained by mixing sulfuric acid and hydrogen peroxide water, and ozone water is used as a mixture of sulfuric acid and hydrogen peroxide in order to dissolve ozone into water. Alternative. In particular, a mixture of ammonia and hydrogen peroxide is a detergent obtained by mixing ammonia water and hydrogen peroxide water. When the organic impurities adhering to the surface are immersed in a mixture of ammonia and hydrogen peroxide, due to the dissolution and peroxidation of ammonia The oxidation of hydrogen causes the organic impurities to be separated from the surface and separated and washed.

Such chemical cleaning according to the chemical liquid is necessary for removing impurities such as particles or contaminants attached to the blank mask or the mask, but also has a halftone phase shift film for the blank mask or the mask. Optical film Suspicion of damage. For example, the surface of the optical film may be deteriorated by the chemical cleaning as described above, and the optical characteristics originally required may be changed. Since the chemical cleaning of the blank mask or the mask is repeated, each cleaning step is performed. The change in characteristics of the optical film produced in the film (for example, the change in phase difference) must be suppressed to the minimum as much as possible.

A film which satisfies this requirement may be a film of ruthenium and nitrogen and/or oxygen, for example, a film composed of ruthenium and nitrogen containing no transition metal, or a ruthenium containing no transition metal and nitrogen and oxygen. Membrane, which enhances chemical resistance.

In general, a film for forming a pattern of a blank mask is formed by sputtering. For example, when a film (SiN film) composed of ruthenium and nitrogen is formed on a transparent substrate, a Si target is usually disposed in a film formation chamber, and a mixed gas of a rare gas such as Ar and nitrogen gas is supplied, and the plasma is plasma-treated. The gas collides with the Si target, thereby causing the flying Si particles to be nitrided in the middle and deposited on the transparent substrate, or reacting with the nitrogen on the surface of the target or reacting on the transparent substrate to form a film by the process. The nitrogen content of the SiN film can be mainly adjusted by increasing or decreasing the mixing ratio of nitrogen in the mixed gas, whereby various nitrogen-containing SiN films can be formed on the transparent substrate.

However, when a SiN film is formed by using a Si target, there is a region where it is difficult to stably form a film due to a difference in the flow rate of nitrogen gas in the mixed gas, and it is difficult to control optical characteristics such as a phase difference or a transmittance of the film, and it is particularly difficult to ensure. A predetermined phase difference, for example, a phase difference of approximately 180°, or a predetermined transmittance, for example, a transmittance of 15% or less, has a problem that it is difficult to obtain a film having uniform in-plane optical characteristics.

The present invention has been made in order to solve the above problems, and an object of the invention is to provide a method for producing a halftone phase shift type blank mask having a halftone phase shift film containing ruthenium and selected from nitrogen and One or both of the oxygen phase shifts the film, and the uniformity of the optical characteristics in the plane is good.

In order to solve the above problems, the inventors of the present invention have focused on a halftone phase shift film containing one or both of nitrogen and oxygen as a halftone phase shift film excellent in chemical resistance, and to secure a predetermined phase difference. The halftone phase shift film having good in-plane uniformity was carefully examined, and as a result, it was found that in the reactive sputtering of the halftone phase shift film forming the film containing ruthenium, a plurality of layers including the first layer and the second layer were used. The halftone phase shift film has a constant electric power applied to the target, and is scanned by reducing the flow rate of the reactive gas introduced into the reaction chamber, thereby reducing the flow rate of the reactive gas and the reactivity. In the hysteresis curve formed by the target voltage value or the target current value measured by the scanning of the gas flow rate, in the first layer and the second layer, the reaction of the hysteresis region is set in the sputtering of one of the layers, respectively. The flow rate of the reactive gas below the lower limit of the gas flow rate is set to be the first in the sputtering of the other layer, and the flow rate of the reactive gas in the inner side of the lower limit and the upper limit of the flow rate of the reactive gas in the hysteresis region is set to form the first And the second layer, thereby forming a halftone phase shift type blank mask having a halftone phase shift film having a good in-plane uniformity of chemical resistance and optical properties, and having excellent reproducibility. Forming a halftone phase with good in-plane uniformity The film is transferred, thus completing the present invention.

Accordingly, the present invention provides a method of manufacturing the following halftone phase shift type blank mask.

Claim 1 is a method for producing a halftone phase shift type blank mask, which comprises using a target containing ruthenium and a reactive gas containing one or both of nitrogen and oxygen, by reactive sputtering A method for producing a halftone phase shift type blank mask in which a halftone phase shift film of one or both of nitrogen and oxygen is formed on a transparent substrate, characterized in that it comprises a plurality of layers including the first layer and the second layer The layer is configured to form the halftone phase shift film, and the electric power applied to the target is constant, and when the flow rate of the reactive gas introduced into the reaction chamber is increased and then decreased, the flow rate of the reactive gas is In the hysteresis curve formed by the target voltage value or the target current value measured by the scanning of the flow rate of the reactive gas, the first layer and the second layer are respectively sputtered in one layer The flow rate of the reactive gas below the lower limit of the flow rate of the reactive gas in the hysteresis region is set, and in the sputtering of the other layer, the reactivity between the lower limit and the upper limit of the flow rate of the reactive gas in the hysteresis region is set. Gas flow, Forming the first layer and the second layer.

Item 2: The method for producing a halftone phase shift type blank mask according to claim 1, wherein the target voltage value V _L and the hysteresis region are set with respect to a lower limit of the reactive gas flow rate of the hysteresis region The difference between the target voltage value V _H at the upper limit of the flow rate of the reactive gas, and the target voltage value V displayed when the target voltage value V _A and the reactive gas flow rate are decreased when the flow rate of the reactive gas is increased The difference in _D is within ±15% of the reactive gas flow rate; or the target current value I _L relative to the lower limit of the reactive gas flow rate in the hysteresis region and the upper limit of the reactive gas flow rate in the hysteresis region The difference between the material current value I _H is such that the difference between the target current value I _A displayed when the flow rate of the reactive gas increases and the target current value I _D when the flow rate of the reactive gas decreases is within ±15%. The flow of reactive gas forms the other layer of the above.

The method of manufacturing a halftone phase shift type blank mask according to claim 1 or 2, wherein the flow rate of the reactive gas is set to be equal to or higher than a lower limit of the upper limit of the reactive gas flow rate in the hysteresis region The other layer above.

The method of producing a halftone phase shift type blank mask according to any one of claims 1 to 3, wherein the reactive gas contains nitrogen (N ₂ ) or oxygen (O ₂ ).

The method of manufacturing a halftone phase shift type blank mask according to any one of claims 1 to 4, wherein the target containing ruthenium is a target composed only of ruthenium.

Request item 6: A method of producing a halftone phase shift type blank mask according to claim 5, wherein said halftone phase shift film does not contain a transition metal.

According to the present invention, it is possible to provide an in-plane uniformity of optical characteristics and to secure a predetermined phase difference in a halftone phase shift film which is excellent in chemical resistance and contains one or both of nitrogen and oxygen. A halftone phase shift type blank mask having a halftone phase shift film with good in-plane uniformity.

Fig. 1 is a view showing a hysteresis curve obtained in Example 1.

The invention is described in more detail below.

In the present invention, a halftone containing one or both of cerium, nitrogen, and oxygen is used by reactive sputtering using a target gas containing cerium and a reactive gas containing one or both of nitrogen and oxygen. The phase shift film is formed on a transparent substrate such as a quartz substrate to produce a halftone phase shift type blank mask.

When reactive sputtering is performed using a target and a reactive gas in a reaction chamber under vacuum or reduced pressure, the electric power applied to the target is made constant, and the state in which the reactive gas is not supplied is slowly When the amount (flow rate) of the reactive gas is increased, the target gas is increased as the reactive gas increases. The voltage measured in the material (target voltage) is slowly reduced. This reduction in voltage exhibits an initial slow (smaller slope) reduction followed by an area that is sharply (with a larger slope) and then slowly (with a smaller slope) again. On the other hand, when the amount of the reactive gas is increased, and the voltage is again passed through the slowly decreasing region, the amount of the reactive gas is decreased by inversion, and the amount of the reactive gas is measured in the target as the reactive gas is decreased. The voltage (target voltage) is slowly increased. This increase in voltage exhibits an initial increase (smaller slope), followed by an area that increases sharply (with a larger slope) and then slowly increases (with a smaller slope) again. However, the target voltage at the time of increasing the amount of the reactive gas and the target voltage at the time of reducing the amount of the reactive gas are determined to reduce the reactive gas in the region where the above-mentioned rapid (large slope) is decreased and increased. The target voltage is lower when the amount is reached.

Further, when reactive sputtering is performed using a target and a reactive gas in a reaction chamber under vacuum or reduced pressure, when the electric power applied to the target is constant and the reactive gas is never supplied, When the amount (flow rate) of the reactive gas is slowly increased, the current (target current) measured in the target gradually increases as the reactive gas increases. This increase in current exhibits an initial increase (smaller slope), followed by an area that increases sharply (with a larger slope) and then slowly increases (with a smaller slope) again. On the other hand, when the amount of the reactive gas is increased, the current is again passed through the slowly decreasing region, and the amount of the reactive gas is decreased by inversion, and the amount of the reactive gas is measured in the target as the reactive gas is decreased. The current (target current) is slowly reduced. This current The reduction is a motion that initially decreases slowly (with a smaller slope), then passes through a region that is sharply (with a larger slope), and then slowly decreases (with a smaller slope) again. However, the target current when the amount of the reactive gas is increased and the target current when the amount of the reactive gas is decreased is determined to decrease the reactive gas in the region where the above-mentioned rapid increase (and large slope) is increased and decreased. The amount of target current is higher.

As described above, in the reactive sputtering, the electric power applied to the target is constant, and when the flow rate of the reactive gas introduced into the reaction chamber is increased and then decreased, the flow rate of the reactive gas is used. The target gas voltage value or the target current value measured by scanning the reactive gas flow rate is similar to the hysteresis curve known as a magnetic hysteresis curve (BH curve), for example, as shown in FIG. Hysteresis curve.

The range of the hysteresis curve (hysteresis region) is formed in the region by increasing the amount of the reactive gas, the target voltage or the target current, and the target voltage or the target current when the amount of the reactive gas is reduced. The lower limit and the upper limit of the amount of the reactive gas may be a target voltage value or a target current value when the amount of the reactive gas is increased, and a target voltage value or a target current when the amount of the reactive gas is decreased. The value is substantially uniform. For example, when the target voltage value when the flow rate of the reactive gas is increased is V _A and the target voltage value when the flow rate of the reactive gas is decreased is V _D , the following formula is used ( 1-1) (V _A - V _D ) / {(V _A + V _D ) / 2} × 100 (1-1)

The rate of change obtained is set to I _A when the flow rate of the reactive gas is increased, and the value of the target current when the flow rate of the reactive gas is decreased is I _D , and the following formula (1) 2) (I _D -I _A )/{(I _A +I _D )/2}×100 (1-2)

The rate of change obtained is gradually decreased from the central portion of the hysteresis region toward the lower limit side or the upper limit side, and can be, for example, a point of 2% or less, in particular, substantially zero, which is a reaction of the hysteresis region. The lower or upper limit of the amount of gas.

In the flow rate of the reactive gas below the lower limit of the hysteresis region, it is considered that during the sputtering, even if the reactive gas is adsorbed on the surface of the target, the sputtered particles are released from the surface of the target, so that the surface of the target is eroded. It remains in the state of the metal (the metal here also contains 矽) (sometimes referred to as the metal mode). Further, in the flow rate of the reactive gas above the upper limit of the hysteresis region, it is considered that the surface of the target reacts with the reactive gas during sputtering, and the surface of the target is completely covered by the metal compound (sometimes referred to as this Reaction mode). On the other hand, in the flow rate of the reactive gas which exceeds the lower limit and does not reach the upper limit of the hysteresis region, a state in which a part of the eroded portion of the target surface is covered with the metal compound (this is sometimes referred to as a transition mode) can be considered.

In the blank mask, the uniformity in the plane of the film is important. The halftone phase shift film is generally used, but in order to make the film have a certain degree of transmittance, it is necessary to add oxygen or nitrogen, etc., in order to form a predetermined phase difference and to have a predetermined transmittance. Membranes containing ruthenium must be formed into a film in a transition mode. However, the film formation in the transition mode is easy to make the in-plane One sex is reduced. Further, in the reaction mode, the film formation rate is slow and the surface of the target is easily insulated. Therefore, in the present invention, reactive sputtering is performed by combining a flow rate of a reactive gas in a metal mode and a flow rate of a reactive gas in a transition mode.

Specifically, the halftone phase shift film is composed of a plurality of layers (preferably 2 to 10 layers) including the first layer and the second layer, and the first layer and the first layer are formed in each of the first layer and the second layer. In the two layers, in the sputtering of one layer, the flow rate of the reactive gas below the lower limit of the flow rate of the reactive gas in the hysteresis region is set, and in the sputtering of the other layer, the reactivity in the hysteresis region is set. The first layer and the second layer are formed by the reactive gas flow rate inside the lower limit and the upper limit of the gas flow rate.

In particular, it is preferable to set the difference between the target voltage value V _L at the lower limit of the flow rate of the reactive gas in the hysteresis region and the target voltage value V _H at the upper limit of the reactive gas flow rate in the hysteresis region, The difference between the target voltage value V _A displayed when the flow rate of the reactive gas is increased and the target voltage value V _D when the flow rate of the reactive gas is decreased is within ±15% (ie, -15% to +15) %), preferably within ±10% (ie, -10% to +10%) of the reactive gas flow rate; or the target current value I _L relative to the lower limit of the reactive gas flow rate in the hysteresis region The difference between the target current value I _H at the upper limit of the reactive gas flow rate in the hysteresis region, and the target displayed when the target gas current value I _A and the reactive gas flow rate are decreased when the flow rate of the reactive gas is increased The difference between the material current value I _D is within ±15% (ie, -15% to +15%), preferably within ±10% (ie, -10% to +10%) of the reactive gas flow rate. The other layer.

At this time, the target voltage value V _L at the lower limit of the reactive gas flow rate in the hysteresis region and the target voltage value V _H at the upper limit of the reactive gas flow rate in the hysteresis region can be respectively applied to increase the amount of the reactive gas. The average of the target voltage and the target voltage at which the amount of reactive gas is reduced. Further, the target current value I _L at the lower limit of the reactive gas flow rate in the hysteresis region and the target current value I _H at the upper limit of the reactive gas flow rate in the hysteresis region can be respectively applied to increase the amount of the reactive gas. The average of the target current and the target current when reducing the amount of reactive gas.

The present invention is particularly effective when the following hysteresis curve is formed, that is, the target voltage value V _L from the lower limit of the reactive gas flow rate in the hysteresis region and the upper limit of the reactive gas flow rate in the hysteresis region In the material voltage value V _H , the following formula (2-1) (V _L - V _H ) / {(V _L + V _H ) / 2} × 100 (2-1)

Obtaining the rate of change, or the target current value I _H of the upper limit of the target current value I _L and the reactive gas flow rate limit of the hysteresis region of the reaction gas flow rate from the hysteresis area, the following Equation (2-2)(I _H -I _L )/{(I _L +I _H )/2}×100 (2-2)

The obtained hysteresis curve with a rate of change of 15% or more.

Further, the present invention is particularly effective when the following hysteresis curve is formed, that is, the target voltage value V _L at the lower limit of the reactive gas flow rate with respect to the hysteresis region and the upper limit of the reactive gas flow rate in the hysteresis region. The difference between the target voltage value V _H and the target voltage value V _A and the reactive gas displayed when the flow rate of the reactive gas is increased in the average value of the lower limit and the upper limit of the reactive gas flow rate in the hysteresis region The difference between the target voltage value V _D displayed when the flow rate is decreased, or the target current value I _L relative to the lower limit of the reactive gas flow rate in the hysteresis region and the upper limit of the reactive gas flow rate in the hysteresis region The difference between the target current value I _H and the target current value I _A and the reactive gas flow rate when the reactive gas flow rate increases in the average value of the lower limit and the upper limit of the reactive gas flow rate in the hysteresis region The difference between the target current value I _D displayed when the decrease is a hysteresis curve of +10% or more or -10% or less.

In the metal mode and the reaction mode, the target voltage value or the target current value when the amount of the reactive gas is increased is substantially the same as the target voltage value or the target current value when the amount of the reactive gas is decreased.

Further, in the present invention, it is preferable to form the other layer by setting the flow rate of the reactive gas such that the lower limit of the flow rate of the reactive gas in the hysteresis region is equal to or higher than the average value of the upper limit. In other words, it is preferable to form the other layer on the side of the reaction mode of the transition mode. In the present invention, by combining a layer formed by a flow rate of a reactive gas in a metal mode and a flow rate of a reactive gas in a transition mode, in particular, a lower limit and an upper limit of a flow rate of a reactive gas in a hysteresis region The two layers of the layer formed by the flow of the reactive gas, in particular, it is difficult to obtain a film having a uniform phase difference, a transmittance, or the like in the surface of the film, that is, a film having a uniformity, that is, 170 to 190°, in particular It is a halftone phase of 175 to 185°, particularly a phase difference of approximately 180°, a transmittance of 15% or less, especially 10% or less, and for example, 3% or more. In the displacement film, a more uniform halftone phase shift film can be formed.

The arrangement of the first layer and the second layer constituting the halftone phase shift film is such that the flow rate of the reactive gas when the first layer is formed is a reactive gas flow rate equal to or lower than the lower limit of the hysteresis region (that is, the metal mode). For example, when the flow rate of the reactive gas at the time of forming the second layer is a reactive gas flow rate (ie, a transition mode) which is more inside the lower limit and the upper limit of the flow rate of the reactive gas in the hysteresis region, for example, The second layer is set to the side farther from the transparent substrate (surface side), and the chemical resistance can be improved. Further, the second layer is formed on the side farther from the transparent substrate (surface side) or the side closest to the transparent substrate ( On the substrate side, the reflectance can be effectively reduced on each side. Further, from the viewpoint of controlling the control at the time of etching the halftone phase shift film, for example, the accuracy of the terminal detection is good, the first layer is formed on the side closest to the substrate, and the second layer is formed in addition thereto. The location other than the location is valid. Specific examples of the plural layer structure include a two-layer structure of the first layer and the second layer, a three-layer structure in which the second layer is provided on the surface side of the first layer and the substrate side, and the first layer and the second layer are alternately provided. Four or more layers of the interbed structure. The halftone phase shift film is preferably 70% to 100%, more preferably 100%, of the film thickness of the halftone phase shift film formed by the first layer and the second layer, in addition to the surface oxide layer described later.

The halftone phase shift film of the present invention is formed by a sputtering method, but any of DC sputtering and RF sputtering may be used. The target and the sputtering gas can be appropriately selected depending on the layer constitution or composition. Examples of the target containing ruthenium include a ruthenium target (a target composed only of ruthenium), a ruthenium nitride target, and a target containing both ruthenium and tantalum nitride. At this time, as a half The hue phase shift film can form a halftone phase shift film of a lanthanoid material which does not contain a transition metal such as ruthenium oxide, ruthenium nitride or ruthenium oxynitride.

In the film formation of the halftone phase shift film, a reactive gas which reacts with the material of the target to form a part of the film component, specifically, nitrogen (N ₂ gas), oxygen (O ₂ gas), and nitrogen oxide can be used. Material gas (N ₂ O gas, NO gas, NO ₂ gas) or the like. Further, as the sputtering gas, helium gas, helium gas, argon gas or the like which is a rare gas can be used. The content of nitrogen and oxygen in the halftone phase shift film may be a reactive gas by using a nitrogen-containing gas or an oxygen-containing gas as a reactive gas in the sputtering gas, and appropriately adjusting the amount of introduction to perform reactive sputtering. And adjust. The sputtering pressure is usually 0.01 to 1 Pa, preferably 0.03 to 0.2 Pa.

In the first layer, for each layer corresponding to the layer, the second layer may be in the film thickness direction in a range corresponding to the flow rate of the reactive gas satisfying each film forming condition for each layer corresponding to the layer. The film formation is carried out under the same film formation conditions, and the film formation conditions may be changed stepwise or continuously to form a film.

In the halftone phase shift film, in order to suppress the film quality change of the halftone phase shift film, a surface oxide layer may be provided as the layer on the surface side (layer of the outermost surface portion). The oxygen content of the surface oxide layer may be 20 atom% or more, and may further be 50 atom% or more. The method of forming the surface oxide layer, specifically, in addition to the oxidation by atmospheric oxidation (natural oxidation), as a method of forcibly performing the oxidation treatment, a film in which a lanthanoid material is treated by ozone gas or ozone water is exemplified. The method, or in the presence of oxygen in the ambient gas, by oven heating, lamp annealing, laser heating, etc. The method of heating to about 300 ° C, and the like. The thickness of the surface oxide layer is preferably 10 nm or less, more preferably 5 nm or less, and particularly preferably 3 nm or less. Usually, when it is 1 nm or more, an effect as an oxide layer can be obtained. The surface oxide layer may also be formed by increasing the amount of oxygen in the sputtering step, but in order to form a layer having fewer defects, it is preferably formed by the above-described atmospheric oxidation or oxidation treatment.

In the halftone phase shift type blank mask of the present invention, a light shielding film can be provided on the halftone phase shift film in the same manner as the previous halftone phase shift type blank mask. By providing a light-shielding film, a region where the exposure light is completely shielded from light can be provided on the halftone phase shift type mask. The material of the light-shielding film can be applied to various materials, and it is preferable to use a film formed of a chromium-based material as an auxiliary film for etching processing. There are many reports on the film structure and the material of the above-mentioned film (for example, JP-A-2007-33469 (Patent Document 3), JP-A-2007-233179 (Patent Document 4), etc.) For example, a light-shielding film of a Cr type or the like is provided, and an anti-reflection film or the like which is a Cr-based or the like which reduces reflection from the light-shielding film is further provided. Both the light-shielding film and the anti-reflection film may be composed of a single layer or a plurality of layers. Examples of the material of the Cr-based light-shielding film or the Cr-based anti-reflection film include a chromium monomer, a chromium oxide (CrO), a chromium nitride (CrN), a chromium carbide (CrC), a chromium oxynitride (CrON), and a chromium. Oxygen carbide (CrOC), chromium nitrogen carbide (CrNC), chromium oxynitride (CrONC), and the like.

The Cr-based light-shielding film and the Cr-based anti-reflection film may be a chromium-based target or a target of one or more selected from the group consisting of oxygen, nitrogen, and carbon, and used in: Rare gas of Ar, He, Ne, etc. In the body, a sputtering gas of a gas selected from an oxygen-containing gas, a nitrogen-containing gas, and a carbon-containing gas is appropriately added in accordance with the composition of the film to be formed, and a film is formed by reactive sputtering.

Further, as another mode in which the light-shielding film is provided, a processing auxiliary film using a chromium-based material (etching as shown in JP-A-2007-241065 (Patent Document 5) may be provided on the halftone phase shift film. The film is stopped as a processing auxiliary film, and a light-shielding film formed of a ruthenium, a ruthenium-based compound or a transition metal ruthenium compound is provided thereon.

A hard mask film can be further formed on the light shielding film. The hard mask film is preferably a film having a different etching property from the light-shielding film. For example, when the light-shielding film is formed into a Cr-based film, it is preferable to use a film which can be etched by a fluorine-based gas such as SF ₆ or CF ₄ . Examples of the film include a ruthenium film, a film containing lanthanum and nitrogen and/or oxygen, and a lanthanide hard mask film further containing a transition metal such as molybdenum, tungsten, niobium or zirconium.

The halftone phase shift type blank mask of the present invention can be constructed as a halftone phase shift type mask by a general method. For example, in a halftone phase shift type blank mask in which a light-shielding film or an anti-reflection film formed of a chromium-based material film is formed on a halftone phase shift film, for example, a halftone phase shift can be produced by the following steps. Type mask.

First, an electron beam resist film is formed on a chromium-based material film of a halftone phase shift type blank mask, and after pattern irradiation of an electron beam, a photoresist pattern is obtained by a predetermined development operation. Next, using the obtained photoresist pattern as an etching mask, the photoresist pattern is transferred to the chromium-based material film by chlorine-based dry etching using oxygen. Then using the obtained chromium-based material film As an etch mask, the pattern is transferred to a halftone phase shift film by fluorine-based dry etching. Then, when there is a chromium-based material film which should remain as a light-shielding film, after forming a photoresist pattern for protecting the portion, the unnecessary chromium-based material film is again peeled off by oxygen-containing chlorine-based dry etching, and is followed. A general method is used to remove the photoresist material, whereby a halftone phase shift type mask can be obtained.

Further, in the light-shielding film or the anti-reflection film formed of the chromium-based material film on the halftone phase shift film, a halftone phase shift type blank mask having a tantalum hard mask film is further formed, for example, A halftone phase shift type mask is manufactured by the following steps.

First, an electron beam photoresist film is formed on a ruthenium hard mask film of a halftone phase shift type blank mask, and after pattern irradiation of an electron beam, a photoresist pattern is obtained by a predetermined development operation. . Next, using the obtained photoresist pattern as an etching mask, the photoresist pattern was transferred to the lanthanide hard mask film by fluorine-based dry etching. Next, the lanthanide hard mask film pattern is transferred to the chromium-based material film by dry etching using chlorine containing oxygen. Then, after the photoresist is removed, the obtained chromium-based material film pattern is used as an etching mask, and the pattern is transferred to the halftone phase shift film by fluorine-based dry etching, and the lanthanide hard mask film is removed. Then, when there is a chromium-based material film which should remain as a light-shielding film, after forming a photoresist pattern for protecting the portion, the unnecessary chromium-based material film is again peeled off by oxygen-containing chlorine-based dry etching, and is followed. A general method is used to remove the photoresist material, whereby a halftone phase shift type mask can be obtained.

A halftone phase shift type mask manufactured by the halftone phase shift type blank mask of the present invention is used for forming a pattern having a half pitch of 50 nm or less, particularly 30 nm or less, particularly 20 nm or less, on a substrate to be processed. In the photolithography technique, it is particularly effective to expose the pattern to the photoresist film formed on the substrate to be processed by exposure light having a wavelength of 200 nm or less, such as ArF excimer laser light (193 nm).

In the pattern exposure method using the halftone phase shift type reticle manufactured by the halftone phase shift type blank mask of the present invention, a halftone phase shift type mask manufactured by a halftone phase shift type blank mask is used. And irradiating the exposure light to the reticle pattern of the pattern containing the halftone phase shift film, and transferring the reticle pattern to the photoresist film of the exposure target formed as the reticle pattern formed on the substrate to be processed. The irradiation of the exposure light may be exposure under dry conditions or liquid immersion exposure, and the pattern exposure method of the present invention is 300 mm or more when the liquid is infiltrated by a liquid having a high cumulative irradiation energy in a relatively short period of time in actual production. The wafer is particularly effective when the reticle pattern is exposed as a substrate to be processed.

[Examples]

Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]

In the reaction chamber of the sputtering apparatus, a quartz substrate of 152 mm square and 6.35 mm thick is provided, and a ruthenium target is used as a sputtering target, and argon gas and nitrogen gas are used as a sputtering gas to apply electric power to the target and argon gas. The flow rate was set to be constant, and the current flowing through the target was measured while changing the flow rate of nitrogen gas, thereby obtaining a hysteresis curve. Specifically, the electricity to be applied to the target The force was set to 1 kW, the argon gas was set to 17 sccm, and sputtering was started in a state where nitrogen gas was flowed through the reaction chamber at 5 sccm, and the flow rate of nitrogen gas was increased at 0.1 sccm per second, and finally the flow rate of nitrogen gas was increased to 50 sccm, and the flow was maintained. After 30 seconds, conversely, the nitrogen flow rate was reduced from 50 sccm to 5 sccm at 0.1 sccm per second. The resulting hysteresis curve is shown in Figure 1. In Fig. 1, the solid line indicates the target current when the nitrogen flow rate is increased, and the broken line indicates the target current when the nitrogen flow rate is decreased.

In Fig. 1, the flow rate of the reactive gas at the position indicated by A is 10.0 sccm, which is a metal mode. Further, in Fig. 1, the flow rate of the reactive gas at the position indicated by C is 30.0 sccm, which is a transition mode which is further inside than the upper and lower limits of the nitrogen gas flow rate in the hysteresis region. The difference between the target current value I _L at the lower limit of the nitrogen gas flow rate in the hysteresis region at this time and the target current value I _H at the upper limit of the nitrogen gas flow rate in the hysteresis region was 0.57 A. Further, at the position indicated by C, the difference between the target current value I _L at the lower limit of the nitrogen gas flow rate with respect to the hysteresis region and the target current value I _H at the upper limit of the nitrogen flow rate in the hysteresis region, reactivity The ratio of the difference between the target current value I _A displayed when the gas flow rate is increased and the target current value I _D when the flow rate of the reactive gas is decreased is 9%.

On the other hand, in Fig. 1, the flow rate of the reactive gas at the position indicated by B was 19.1 sccm, which was a transition mode. At the position indicated by B, the difference between the target current value I _L at the lower limit of the nitrogen flow rate with respect to the hysteresis region and the target current value I _H at the upper limit of the nitrogen flow rate in the hysteresis region, the reactive gas flow rate The ratio of the target current value I _A displayed when the increase was increased to the target current value I _D when the flow rate of the reactive gas was decreased was 14%.

According to the hysteresis curve obtained in the above, a ruthenium target is used as the sputtering target, and nitrogen gas and argon gas are used as the sputtering gas, and the metal mode condition of the lower limit of the nitrogen gas flow rate in the hysteresis region obtained above is used. In the figure, the conditions shown in A are: argon gas flow rate: 17.0 sccm, nitrogen gas flow rate: 10.0 sccm, target applied electric power: 1 kW), and the first layer of the composition ratio is Si:N=62:38 in atomic ratio. The film was formed on a quartz substrate of 152 mm square and 6.35 mm thick. Then, in the above-mentioned transition mode of the upper and lower limits of the nitrogen gas flow rate in the hysteresis region (the condition shown in C in Fig. 1 : argon flow rate: 17.0 sccm, nitrogen flow rate: 30.0 sccm, target application) Electric power: 1 kW), a second layer having a composition ratio of Si:N=46:54 in atomic ratio is formed on the first layer, and a halftone phase of SiN composed of the first layer and the second layer is formed. Displacement membrane. The obtained halftone phase shift film had a phase difference of 177 deg, a transmittance of 6.0%, and a film thickness of 67 nm. In addition, the in-plane distribution has a phase difference of -0.3%, a transmittance of 1.3%, and good in-plane uniformity.

The in-plane distribution of the phase difference and the transmittance is measured at an intersection of a diagonal line of a surface on which a halftone phase shift film is formed on a substrate, and an arbitrary point from a position at a distance of 95 mm from the intersection on the diagonal line. The phase difference and the transmittance are calculated from the measured values of the following equations (3-1) and (3-2).

. In-plane distribution of phase difference [%]=(PS(I)-PS(E))/{(PS(I)+PS(E))/2}×100 (3-1)

(wherein, PS(I) is the phase difference at the intersection, and PS(E) is the above Phase difference at any 1 point)

. In-plane distribution of penetration [%]=(T(I)-T(E))/{(T(I)+T(E))/2}×100 (3-2)

(where T(I) is the penetration at the intersection, and T(E) is the penetration at any of the above points)

[Comparative Example 1]

According to the hysteresis curve obtained in Example 1, a ruthenium target was used as a sputtering target, nitrogen gas and argon gas were used as a sputtering gas, and only the upper and lower limits of the nitrogen gas flow rate in the magnetic hysteresis region obtained in Example 1 were used. The conditions of the inner transition mode (the conditions shown in B in Fig. 1 : argon flow rate: 17.0 sccm, nitrogen flow rate: 19.1 sccm, target applied electric power: 1 kW), and the composition ratio is Si in atomic ratio: A halftone phase shift film of SiN composed of a single layer of N=47:53 was formed on a quartz substrate of 152 mm square and 6.35 mm thick. The obtained halftone phase shift film had a phase difference of 177 deg, a transmittance of 6.0%, and a film thickness of 62 nm. In addition, the in-plane distribution has a phase difference of -1.0%, a transmittance of -10.8%, and in-plane uniformity.

Claims (11)

A method for producing a halftone phase shift type blank mask, which comprises using a target material containing ruthenium and a reactive gas containing one or both of nitrogen and oxygen, and containing ruthenium and nitrogen by reactive sputtering And a method for producing a halftone phase shift type blank mask formed on a transparent substrate, wherein one or both of the oxygen is formed on the transparent substrate, wherein the plurality of layers including the first layer and the second layer are formed The halftone phase shift film has a constant electric power applied to the target, and is scanned by increasing the flow rate of the reactive gas introduced into the reaction chamber, thereby reducing the flow rate of the reactive gas and In the hysteresis curve formed by the target voltage value or the target current value measured by the scanning of the flow rate of the reactive gas, hysteresis is set in the sputtering of one of the first layer and the second layer, respectively. The flow rate of the reactive gas below the lower limit of the flow rate of the reactive gas in the region is set in the sputtering of the other layer, and the flow rate of the reactive gas exceeding the lower limit and not exceeding the upper limit is set to form the first layer and the first layer 2 layer. A method of manufacturing a halftone phase shift type blank mask according to claim 1, wherein the target voltage value V _L at the lower limit of the reactive gas flow rate with respect to the hysteresis region and the reactive gas flow rate in the hysteresis region are set. The difference between the target voltage value V _H at the upper limit is such that the difference between the target voltage value V _A displayed when the flow rate of the reactive gas increases and the target voltage value V _D displayed when the flow rate of the reactive gas decreases is located. The flow rate of the reactive gas within ±15%; or the target current value I at the lower limit of the target gas current I _L relative to the hysteresis region and the upper limit of the reactive gas flow in the hysteresis region The difference between _H is such that the difference between the target current value I _A when the flow rate of the reactive gas is increased and the target current value I _D when the flow rate of the reactive gas is decreased is within ±15% of the reactive gas flow rate. To form the other layer of the above. A method of producing a halftone phase shift type blank mask according to claim 1, wherein the other layer is formed by setting a flow rate of a reactive gas of a lower limit of a reactive gas flow rate in the hysteresis region and an average value of the upper limit. A method of producing a halftone phase shift type blank mask according to claim 1 or 2, wherein said reactive gas contains nitrogen (N ₂ ) or oxygen (O ₂ ). A method of producing a halftone phase shift type blank mask according to claim 3, wherein the reactive gas contains nitrogen (N ₂ ) or oxygen (O ₂ ). The method for producing a halftone phase shift type blank mask according to claim 1 or 2, wherein the target containing ruthenium is a target composed only of ruthenium. A method of producing a halftone phase shift type blank mask according to claim 3, wherein the target containing germanium is a target composed only of tantalum. The method for producing a halftone phase shift type blank mask according to claim 4, wherein the target containing ruthenium is a target composed only of ruthenium. A method of producing a halftone phase shift type blank mask according to claim 6, wherein said halftone phase shift film does not contain a transition metal. The manufacturer of the halftone phase shift type blank mask of claim 7 The method wherein the halftone phase shift film described above does not contain a transition metal. A method of producing a halftone phase shift type blank mask according to claim 8, wherein said halftone phase shift film does not contain a transition metal.