KR101182082B1 - Method of manufacturing multi-gray scale photomask and multi-gray scale photomask - Google Patents

Abstract

The manufacturing method of the multi-gradation photomask which concerns on this invention is a process of preparing the photomask blank by which the electroconductive film, semi-transmissive film, and light shielding film which have electroconductivity was laminated | stacked in this order on the transparent substrate, and formed on the photomask blank Using the first resist pattern as a mask, at least a first etching step of etching the light shielding film, and after removing the first resist pattern, a second resist pattern is formed on the photomask blank on which the first etching step is performed, and the second A second etching step of etching the semitransmissive film using the resist pattern and the light shielding film as a mask, and a film reduction step of reducing a predetermined amount of the exposed semitransmissive film after removing the second resist pattern.

Description

METHOD OF MANUFACTURING MULTI-GRAY SCALE PHOTOMASK AND MULTI-GRAY SCALE PHOTOMASK}

TECHNICAL FIELD This invention relates to the manufacturing method of the multi-gradation photomask used for manufacture of a flat panel display (henceforth FPD hereafter), such as a liquid crystal display device, and a multi-gradation photomask, for example.

For example, the TFT (thin film transistor) substrate used for a liquid crystal display device uses the photomask in which the transfer pattern which consists of a light shielding part and a light transmission part was formed on the transparent substrate, for example, through 5 to 6 photolithography processes. It has been manufactured. In recent years, in order to reduce the number of photolithography processes, a multi-gradation photomask in which a transfer pattern including a light shielding portion, a translucent portion, and a light transmitting portion is formed on a transparent substrate has been used.

The multi-gradation photomask described above masks a process of preparing a photomask blank in which a semi-transmissive film and a light shielding film are laminated in this order on a transparent substrate, and a first resist pattern formed on the photomask blank. After the first etching step of etching the light shielding film and the first resist pattern is removed, a second resist pattern is formed on the photomask blank on which the first etching step is performed, and the second resist pattern and the light shielding film are used as a mask. Can be produced by performing a second etching step of etching the translucent film (see Patent Document 1: Japanese Unexamined Patent Publication No. 2007-249198).

In addition, the photomask for FPD manufacture is large, for example, one side is a square of 300 mm or more, or in recent years which raised the panel manufacturing efficiency, one side is also a square of 1000 mm or more. For this reason, the wet etching which does not require a vacuum etching chamber is advantageous as an etching method of a light shielding film.

The evaluation of the multi-gradation photomask is mainly performed by measuring the pattern line width (CD), measuring the light transmittance of the semi-transmissive portion, and measuring the presence or absence of a defect. In particular, by precisely controlling the light transmittance of the semi-transmissive portion, the production yield of FPD using a multi-gradation photomask can be improved.

As a result of earnestly researching the control method of the light transmittance of a semi-transmissive part, the inventor discovered that the light transmittance of a semi-transmissive part can be adjusted precisely by selecting the film | membrane structure of a multi-gradation photomask and a material of a semi-transmissive part suitably. Got. That is, after removing the above-mentioned second resist pattern, a predetermined chemical liquid is brought into contact with the exposed semi-transmissive film to perform a film-reduction step of reducing the film thickness of the exposed semi-transmissive film by a predetermined amount, thereby reducing the light transmittance of the semi-transmissive portion. It was found that it could be adjusted.

However, according to an example of the inventor's research, when the above-described film-reducing step is carried out, the film-reduction amount of the semi-transmissive film brought into contact with the chemical liquid varies depending on the in-plane position, so that the light transmittance of the semi-transmissive part becomes uneven across the plane. there was. For example, in a multi-gradation photomask for manufacturing a large size FPD, it is preferable to keep the in-plane variation in the light transmittance of the semi-transmissive portion within 2%, which is a reference value. Transmittance changed beyond the above-mentioned reference value, and the light transmittance of the semi-transmissive part might become nonuniform over the surface. In particular, it has been found that the local change in the amount of reduction of the translucent film has a correlation with the shape of the transfer pattern formed on the transparent substrate. In addition, the said subject is not limited to the case where chemical | medical solution is supplied to a semi-transmissive film for the purpose of adjustment of light transmittance, For example, when chemical liquid is supplied for the purpose of washing | cleaning after implementation of a 2nd etching process, etc. It may also occur when the light-transmitting film is coated. That is, even if the semi-transmissive film of the film thickness which assumed the film-reduction amount previously is formed, it is difficult to reach the intended light transmittance unless the amount of in-plane film-reduction is uniform by the shape of a transfer pattern.

Therefore, an object of the present invention is to suppress the change of the local film amount when the translucent film of the multi-gradation photomask is reduced and the transmittance is changed, and to improve the in-plane uniformity of the light transmittance.

A first aspect of the present invention is a manufacturing method of a multi-gradation photomask which forms a predetermined transfer pattern including a light shielding portion, a light transmitting portion, and a semi-transmissive portion on a transparent substrate, comprising a conductive film having conductivity, a semi-transmissive film, And a step of preparing a photomask blank in which the light shielding film is laminated on the transparent substrate in this order; a first etching step of etching the light shielding film at least using the first resist pattern formed on the photomask blank as a mask; And removing the first resist pattern, forming a second resist pattern on the photomask blank on which the first etching process is performed, and etching the semitransmissive film using the second resist pattern and the light shielding film as masks. A multi-gradation photoma having a two-etching step and a film-reducing step of removing a predetermined amount of the exposed semi-transmissive film after removing the second resist pattern. A method of producing greater.

The 2nd aspect of this invention is a manufacturing method of the multi-gradation photomask as described in a 1st aspect which makes a chemical | medical solution contact the said semi-transmissive film in the said photosensitive process.

In a third aspect of the present invention, the conductive film is a multi-gradation photomask according to the first or second aspect having conductivity in which the sheet resistance value is 20 kPa / square or less.

According to a fourth aspect of the present invention, the multi-gradation photomask is a multi-gradation photomask for manufacturing a liquid crystal display device, and the transfer pattern includes a predetermined pixel pattern and a peripheral pattern different in pattern shape from the pixel pattern. It is a multi-gradation photomask as described in any one of the 1st-3rd to say.

A fifth aspect of the present invention is a multi-gradation photomask in which a predetermined transfer pattern including a light shielding portion, a light transmitting portion, and a semi-transmissive portion is formed on a transparent substrate, wherein the light shielding portion has a conductive conductive film, a semi-transparent film, And a light shielding film are laminated on the transparent substrate in this order. The semi-transmissive portion is formed by stacking the conductive film and the semi-transmissive film on the transparent substrate in this order. It is exposed so that the film thickness of the semi-transmissive film constituting the translucent portion is reduced to be smaller than the film thickness of the semi-transmissive film constituting the light-shielding portion, and the in-plane of the light transmittance of the semi-transmissive film constituting the semi-transmissive portion Distribution is a multi-gradation photomask whose wavelength is 2% or less with respect to light of 365 nm or more and 436 nm or less.

According to a sixth aspect of the present invention, the difference between the film thickness of the semitransmissive film constituting the translucent portion and the film thickness of the semitransmissive film constituting the light shielding portion is in a range of 0.5 nm to 15 nm. It is a multi-gradation photomask.

A seventh aspect of the present invention is a multi-gradation photomask in which a predetermined transfer pattern including a light shielding portion, a light transmitting portion, a first semi-transmissive portion, and a second semi-transmissive portion is formed on a transparent substrate, wherein the light shielding portion has conductivity. A conductive film, a translucent film, and a light shielding film are laminated on the transparent substrate in this order, and the first translucent portion is formed by laminating the conductive film and the translucent film on the transparent substrate in this order. And the second translucent portion is formed by exposing an upper surface of the conductive film formed on the transparent substrate, and the translucent portion is formed by exposing the transparent substrate and forming the first translucent portion. The film thickness is reduced so that the film thickness becomes smaller than the film thickness of the transflective film which comprises the said light-shielding part, and the in-plane distribution of the light transmittance of the transflective film which comprises the said 1st translucent part is Sheets of a multi-gradation photomask less than 2% with respect to light of less than 365㎚ 436㎚.

According to the present invention, it is possible to suppress the change in the local film amount when the semi-transmissive film of the multi-gradation photomask is reduced and the transmittance is changed, thereby improving the in-plane uniformity of the light transmittance.

1A is a partial sectional view (schematic diagram) of a multi-gradation photomask according to an embodiment of the present invention.
1B is a partial cross-sectional view of a resist pattern formed on a transfer object by a pattern transfer process using the multi-gradation photomask of FIG. 1A.
2 is a schematic diagram illustrating a flow of a manufacturing process of a multi-gradation photomask according to an embodiment of the present invention.
3A is a partial sectional view (schematic diagram) of a multi-gradation photomask according to another embodiment of the present invention.
FIG. 3B is a partial cross-sectional view of a resist pattern formed on a transfer object by a pattern transfer process using the multi-gradation photomask of FIG. 3A. FIG.
4 is a schematic diagram illustrating a flow of a manufacturing process of a multi-gradation photomask according to another embodiment of the present invention.
5 is a partial cross-sectional view (schematic diagram) of a multi-gradation photomask according to still another embodiment of the present invention.
Fig. 6A is a schematic diagram showing a state in which the composition of the translucent film is locally different in the etching process of the light shielding film when the conventional multi-gradation photomask is manufactured.
Fig. 6B is a schematic diagram showing a state in which the amount of film reduction of the semi-transmissive film is locally different in the process of film reduction of the semi-transmissive film when a conventional multi-gradation photomask is manufactured.
Fig. 7A is a schematic diagram showing a state in which local compositional change of the translucent film is suppressed by forming a conductive film.
FIG. 7B is a schematic diagram showing a state in which the amount of reduction of the translucent film is equalized in plane by forming the conductive film; FIG.
8 is a graph according to an embodiment of the present invention, showing the measurement result of the light transmittance of the semi-transmissive film when the film forming process is repeated.
9 is a graph according to a comparative example, illustrating a measurement result of light transmittance of a semi-transmissive film when the film forming step is repeatedly performed.
10A is a schematic diagram showing a measurement system of an etching rate.
It is a figure which shows the measurement result of each etching rate of the Cr single plate, the Cr board which comprises a Cr-Mo laminated board, the Mo board which comprises a Cr-Mo laminated board, and the Mo single plate.

<One embodiment of the present invention>

EMBODIMENT OF THE INVENTION Below, one Embodiment of this invention is described, referring mainly FIG. 1A, FIG. 1B, FIG. 2, FIG. 7A, and FIG. 7B.

FIG. 1A is a partial cross-sectional view (schematic diagram) of a multi-gradation photomask according to the present embodiment, and FIG. 1B is a partial cross-sectional view of a resist pattern formed on a transfer object by a pattern transfer process using the multi-gradation photomask. 2 is a schematic diagram illustrating a flow of a manufacturing process of a multi-gradation photomask according to the present embodiment. FIG. 7A is a schematic diagram showing a state in which the local compositional change of the translucent film is suppressed by forming the conductive film, and FIG. 7B is a schematic diagram showing a state in which the reduced film amount of the translucent film is equalized in plane by forming the conductive film.

(1) Composition of multi-gradation photomask

The multi-gradation photomask 100 shown in FIG. 1A is used, for example, when manufacturing thin film transistors (TFTs), color filters, plasma display panels (PDPs), etc. of liquid crystal displays (LCDs). However, FIG. 1A illustrates a laminated structure of a photomask, and the actual pattern is not the same as this.

The multi-gradation photomask 100 includes, for example, a light shielding portion 121 for shielding exposure light (light transmittance of approximately 0%) when the multi-gradation photomask 100 is used, and a light transmittance of exposure light as an example. The transfer pattern includes a translucent portion 122 for reducing the light transmittance to 60% (when the light transmittance is 100%) and a transmissive portion 123 for transmitting the exposure light 100%.

The light shielding portion 121 is formed by stacking a conductive conductive film 111, a translucent film 112, and a light shielding film 113 on the transparent substrate 110 in this order. In addition, the semi-transmissive part 122 consists of the electroconductive film 111 and the semi-transmissive film 112 laminated | stacked in this order on the transparent substrate 110, and the upper surface of the translucent film 112 is exposed. In addition, the transparent part 110 is exposed to the transmissive part 123. Here, another film may be present between the above films and above and below the same range as long as the effects of the present invention are not impaired. The upper surface of the light shielding film 113 constituting the light shielding portion 121 is not limited to being exposed, and another film may be formed on the light shielding film 113. In addition, as described later, instead of the upper surface of the transparent substrate 110 being exposed, the conductive film 111 having a high light transmittance may remain in the light transmitting portion 123.

Here, the film thickness of the transflective film 112 which comprises the translucent part 122 is reduced so that it may become smaller than the film thickness of the transflective film 112 which comprises the light shield part 121. Specifically, the difference between the film thickness of the transflective film 112 constituting the translucent portion 122 and the film thickness of the transflective film 112 constituting the light shield portion 121 is, for example, 0.5 to 15 nm. It is configured to be in the range of. And the in-plane distribution of the light transmittance of the transflective film 112 which comprises the translucent part 122 is comprised so that it may be 2% or less with respect to the light whose wavelength is 365 nm-436 nm, for example. Preferably, the wavelength is 2% or less with respect to the wavelength of any of the range of 365 to 436 nm. At this time, the film thickness distribution of the translucent film 112 is 2% or less in surface.

In addition, the state in which the electroconductive film 111, the transflective film 112, and the light shielding film 113 are patterned is mentioned later.

The transparent substrate 110 is configured as a flat plate made of, for example, quartz (SiO ₂ ) glass, low expansion glass containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , RO, R ₂ O, or the like. have. The main surfaces (surface and back surface) of the transparent substrate 110 are flat and smooth, for example, polished. The transparent substrate 110 can be, for example, a rectangle of 300 mm or more on one side, and can be a rectangle of 1000 mm to 2400 mm on one side, for example. The thickness of the transparent substrate 110 can be 3 mm-20 mm, for example.

The electroconductive film 111 is comprised as a film | membrane with electroconductivity which becomes 20 kPa / square or less, Preferably it is 5 kPa / square or less, More preferably, it is 2 kPa / square or less with a sheet resistance value. The film thickness of the conductive film 111 may be 20 kPa to 500 kPa, for example, preferably 50 kPa to 300 kPa. The conductive film 111 can be configured as a film made of a metal or a metal compound. Cr, Al, Co, W, Ni, Mo or the like can be used as the metal, and oxides, nitrides, carbides, oxynitrides, carbide nitrides, oxynitride carbides and the like of the metals can be used. However, when the metal content is made too small, it becomes difficult to secure the above-mentioned conductivity, so it is preferable to set it as the composition which secured predetermined metal content. For example, 70 at% or more, More preferably, it can be 75% or more.

Moreover, it is preferable that an electroconductive film has etching tolerance with respect to the etching liquid (or etching gas) used for the etching of the translucent film 112. In this case, the conductive film 111 can function as an etching stopper layer when etching the translucent film 112 as described later.

The exposure light transmittance of the conductive film 111 is not particularly limited. In addition, the conductive film 111 patterns the light shielding film 113 and the translucent film 112, respectively, and finishes the function described later as the conductive film for equalizing the potential in the translucent film 112, and then the light transmitting portion 123 Can be removed. On the other hand, at least a portion of the conductive film 111 may be left on the light transmitting portion 123 and used as part of the multi-gradation photomask 100. In such a case, it is preferable that the exposure light transmittance of the film used for the conductive film 111 is 60% or more. For example, the conductive film 111 may be left as it is, or a portion of the film may be left as it is and used as the light-transmitting portion 123 of the multi-gradation photomask 100. In this case, it is preferable to use a film having an exposure light transmittance of 80% or more with respect to the transparent substrate 110. As a film | membrane material with high light transmittance at this time, it can be set as ITO (indium tin oxide), AS (antimony containing tin oxide), zinc oxide, antimony tin, magnesium hydroxide, tin oxide, etc., for example. In this case, it is more preferable that the light transmittance of the conductive film 111 with respect to the exposure light is set to 85% or more with respect to the transparent substrate 110.

In addition, in this embodiment, the light shielding part 121, the conductive film 111, and the semi-transmissive film which the conductive film 111, the semi-transmissive film 112, and the light shielding film 113 were laminated | stacked on the transparent substrate 110 were carried out. The semi-transmissive portion 122 laminated by the 112 and the transmissive portion 123 on which the transparent substrate 110 is exposed are provided. In addition, at least a portion of the conductive film 111 remains on the transparent substrate 110. You may be equipped with the 2nd translucent part. As will be described later, when the exposure light transmittance of the conductive film 111 is appropriately selected, it can be used as a four-gradation photomask, and the light transmittance can be adjusted by the selection of the film thickness. Although the light transmittance of the electroconductive film 111 in this case is determined by the processing conditions of the device to manufacture using the multi-gradation photomask 100, it can select within 60%-80% of range, for example. have.

The translucent film 112 is made of chromium compound, molybdenum silicide or the compound thereof, and may be made of CrO, CrN, CrC, MoSix, MoSiN, MoSiON, MoSiCON, or the like. The semitransmissive film 112 is preferably configured to be etchable using a fluorine (F) -based etching solution (or etching gas). Moreover, it is preferable that the semi-transmissive film 112 has the etching tolerance with respect to the etching liquid (or etching gas) for chromium mentioned above. In this case, the semi-transmissive film 112 can function as an etching stopper layer when etching the light shielding film 113 using the chromium etching solution as described later. In addition, the thickness of the transflective film 112 which comprises the translucent part 122 can be reduced so that it may become smaller than the thickness of the transflective film 112 which comprises the light shielding part 121. FIG. This makes it possible to precisely adjust the light transmittance of the semi-transmissive portion 122 to a desired value.

It is preferable that the light transmittance with respect to the exposure light of the semi-transmissive film 112 is 5%-80%, for example. More preferably, they are 7%-70%. By carrying out light transmittance in such a range, the yield at the time of manufacturing display apparatuses, such as FPD, can be improved. This light transmittance can be obtained by selection of said material and selection of a film thickness.

The light shielding film 113 can consist essentially of chromium (Cr). In addition, when a layer of Cr compound (CrO, CrC, CrN, etc.) is formed on the surface of the light shielding film 113, it is possible to give the surface a reflection suppression function. The light shielding film 113 is comprised so that it can be etched using the etching liquid for chromium which contains, for example, ferric ammonium nitrate ((NH ₄ ) 2 Ce (NO ₃ ) ₆ ) and perchloric acid (HClO ₄ ).

A partial cross-sectional view of the resist pattern 4p formed on the transfer object 1 by the pattern transfer process using the multi-gradation photomask 100 is illustrated in FIG. 1B. The resist pattern 4p is formed by irradiating and developing exposure light to the positive resist film 4 formed on the to-be-transferred body 1 through the multi-gradation photomask 100. The to-be-transferred body 1 is equipped with the board | substrate 2 and arbitrary to-be-processed layers 3a-3c, such as a metal thin film, an insulating layer, and a semiconductor layer laminated | stacked in this order on the board | substrate 2, and are positive type It is assumed that the resist film 4 is previously formed with a uniform thickness on the processing layer 3c. In addition, the processing layer 3b may be configured to be resistant to etching of the processing layer 3c, and the processing layer 3a may be configured to be resistant to etching of the processing layer 3b.

When the exposure light is irradiated to the positive resist film 4 through the multi-gradation photomask 100, the exposure light does not pass through the light blocking part 121, and the semi-transmissive part 122 and the light transmitting part 123 are not exposed. The amount of light of exposure light increases in steps in order. The positive resist film 4 is gradually thinned in the regions corresponding to the light shielding portion 121 and the semi-transmissive portion 122, and is removed in the region corresponding to the light transmitting portion 123. In this manner, a resist pattern 4p having a different film thickness in steps is formed on the transfer target 1.

When the resist pattern 4p is formed, the to-be-processed layers 3c-3a exposed in the area | region (region corresponding to the light transmission part 123) which are not covered with the resist pattern 4p are sequentially from the surface side. It is etched and removed (1st etching). Then, the resist pattern 4p is reduced to remove the region having the smallest film thickness (the region corresponding to the semi-transmissive portion 122), and the newly exposed target layers 3c and 3b are sequentially etched and removed ( Second etching). In this manner, by using the resist pattern 4p having different film thicknesses in steps, a conventional process for two photomasks can be performed, the number of masks can be reduced, and the photolithography process can be simplified.

(2) Manufacturing method of multi-gradation photomask

Next, the manufacturing method of the multi-gradation photomask 100 which concerns on this embodiment is demonstrated, referring FIG.

(Photomask Blank Preparation Process)

First, as illustrated in FIG. 2A, a conductive film 111 having a conductivity, a translucent film 112, and a light shielding film 113 are stacked on the transparent substrate 110 in this order. The mask blank 100b is prepared. Thus, the photomask blank 100b which concerns on this embodiment is the conducting part of the material which has a some electrical conductivity (here, the translucent film 112 which consists of molybdenum silicide or its compound, and the light shielding film which has Cr as a main component) Contact surface 113).

The first resist film 131 is formed on the light shielding film 113. The first resist film 131 can be made of a positive photoresist material or a negative photoresist material. In the following description, the first resist film 131 is formed from a positive photoresist material. The first resist film 131 can be formed using, for example, a method such as spin coating or a slit coater.

(First Etching Step)

Next, drawing exposure is performed by a laser drawing machine or the like, a part of the first resist film 131 is exposed to light, and a developer is supplied to the first resist film 131 by a spraying method or the like to develop the light shielding portion. The first resist pattern 131p covering the region to be formed of 121 is formed. A state in which the first resist pattern 131p is formed is illustrated in FIG. 2B.

Next, the light shielding film 113 is etched using the formed first resist pattern 131p as a mask to form the light shielding film pattern 113p, and the upper surface of the semitransmissive film 112 is partially exposed. A state in which the light shielding film pattern 113p is formed is illustrated in FIG. 2C. Etching is performed by the above-mentioned etching liquid for chromium which contains a ferric ammonium nitrate ((NH ₄ ) 2 Ce (NO ₃ ) ₆ ) and perchloric acid (HClO ₄ ). This etching liquid has electrical conductivity and acts as an electrolyte solution.

In addition, when the semi-transmissive film 112 is at least partially exposed as the etching of the light-shielding film 113 progresses, a dissimilar metal (metal included in each of the light-shielding film 113 and the semi-transmissive film 112) is formed. It becomes the state immersed in electrolyte solution (etching liquid) in the state which has a junction part mutually.

In addition, when the conventional photomask blank (the photomask blank in which the translucent film 112 and the light shielding film 113 are laminated | stacked in this order on the transparent substrate 110, and does not have the conductive film 111) is used, When the electrolyte solution comes into contact with the exposed semi-transmissive membrane 112, Mo ionization occurs due to a difference in the tendency of ionization of Mo (molybdenum) in the exposed semi-transparent membrane 112 and Cr in the light-shielding membrane 113. Is promoted. However, Mo ionization at this time becomes nonuniform in surface. For example, in the part of the pattern in which Cr is largely present, Mo is eluted as a cation while supplying electrons to Cr. However, in the part of the pattern with little Cr, Mo is unlikely to elute. As a result, the amount of Mo eluted locally varies depending on the part of the translucent film 112, and the composition of the translucent film 112 may become nonuniform in surface. That is, a region (hereinafter referred to as Si-rich region) having a smaller Mo content than the stoichiometric composition ratio of the MoSi constituting the translucent film or the compound thereof, or the substance constituting the translucent film (MoSi or the compound thereof) In some cases, a region having a composition close to the stoichiometric composition ratio of hereinafter (hereinafter, also referred to as Mo-rich region) may be locally formed.

That is, as a result of earnestly studying the inventors, the inventors have found that the above-described phenomenon is related to the shape of the transfer pattern. That is, the semi-transmissive film 112 is exposed, so that the dissimilar metals included in each of the light-shielding film and the semi-transmissive film are immersed in the electrolyte (etching solution) in a state where the dissimilar metals in each of the light-transmitting film and the semi-transmissive film have a junction portion with each other. The electrons are supplied from the Mo in the 112 to the Cr in the light shielding film 113, that is, a kind of chemical battery is formed at the junction, thereby causing a change in the tendency of the ionization of Mo. Since the strength of the battery effect is related to at least one of the difference between the in-plane pattern shape, the density, or the area ratio of the light blocking portion and the semi-transmissive portion, the composition of the translucent film 112 is thereby localized. We got knowledge that phenomenon that became different happened. In addition, the inventor of the present invention causes a local change in the composition of the translucent film 112 to cause a local change in the amount of the film of the translucent film 112 when performing the photoresist step described later. The knowledge that the in-plane uniformity of the light transmittance of the film 112 falls was acquired.

With respect to such a problem, in the photomask blank 100b according to the present embodiment, the conductive film 111 having conductivity is formed on the lower layer side of the translucent film 112. As a result, the electrons supplied when the Mo ions are eluted can be freely moved, and the in-plane potential becomes equal, so that the elution tendency of Mo becomes uniform in the plane. As a result, the elution tendency of Mo in the translucent film 112 can be equalized regardless of the shape of the transfer pattern. At this time, the composition of the translucent film 112 is uniform over the surface. As a result, the change of the local film amount of the semi-transmissive film 112 at the time of performing the below-mentioned film-reduction process can be suppressed, and the in-plane uniformity of the light transmittance of the semi-transmissive film 112 can be improved. In addition, the effect by forming the electroconductive film 111 is mentioned later.

When formation of the light shielding film pattern 113p is completed, the first resist pattern 131p is peeled off and removed. A second resist film 132 is formed to cover the remaining light shielding film 113 (light shielding film pattern 113p) and the upper surface of the exposed semi-transmissive film 112, respectively. The second resist film 132 can be made of a positive photoresist material or a negative photoresist material. In the following description, it is assumed that the second resist film 132 is formed from a positive photoresist material. The second resist film 132 can be formed using, for example, a method such as spin coating or a slit coater. A state in which the second resist film 132 is formed is illustrated in FIG. 2D.

(Second etching step)

Next, drawing exposure is performed using a laser drawing machine or the like, a part of the second resist film 132 is exposed to light, and a developer is supplied to the second resist film 132 by a method such as a spray method to be developed, and at least semi-permeable. The second resist pattern 132p covering the region to be formed of the light portion 122 is formed. A state in which the second resist pattern 132p is formed is illustrated in FIG. 2E.

Next, the semi-transmissive film 112 and the conductive film 111 are sequentially etched using the formed second resist pattern 132p as a mask to form the semi-transmissive film pattern 112p and the conductive film pattern 111p. In addition, the transparent substrate 110 is partially exposed. In addition, the etching of the semi-transmissive film 112 can be performed using the above-mentioned fluorine (F) type etching liquid (or etching gas). In addition, etching of the conductive film 111 can be performed by the etching liquid (or etching gas) appropriately selected according to the material which comprises the conductive film 111.

(Filming process)

After peeling and removing the second resist pattern 132p, the chemical liquid is supplied to the upper surface of the remaining semi-transmissive film 112 (the semi-transmissive film pattern 112p), and the semi-transmissive film 112 (the semi-transmissive film) The film thickness of the pattern 112p is reduced, and the manufacturing method of the multi-gradation photomask 100 which concerns on this embodiment is complete | finished. In addition, you may wash after completion | finish of a 2nd etching process simultaneously with this film forming process.

In addition, in this process, the difference between the film thickness of the transflective film 112 which comprises the translucent part 122, and the film thickness of the transflective film 112 which comprises the light shielding part 121 is 0.5-, for example. The film can be reduced to be in the range of 15 nm. More preferably, it can be filmed so that it may become a range of 0.5-4 nm. When the amount of the film is within these ranges, the amount of the film is easily controlled, and the film can also suppress the occurrence of problems such as an increase in the in-plane unevenness of the transmissivity of the semi-transmissive portion and can perform a high quality film-reduction process. . The amount of film reduction at this time can be selected by the necessary transmittance adjustment amount. Here, the film reduction amount can be determined in consideration of the relationship between the film thickness before the film reduction, the light transmittance at that time, and the transmittance required after the film reduction of the semi-transmissive film 112 constituting the translucent portion 122. Preferably, the transmittance can be adjusted within a range of about 2% to 15%. More preferably, the transmittance can be adjusted within a range of about 2% to 10%. In addition, in the above aspect, the photoresist process is used as the final step of the photomask manufacturing process. However, the photoresist process may be performed after etching the light shielding film 113 using the first resist pattern 131p as a mask. As the chemical liquid for reducing the semi-transmissive film 112, for example, a fluorine (F) -based etching solution, an acid, an alkali, or the like can be used.

(3) Effect by Forming Conductive Film

As described above, when etching proceeds in the first etching process, the light shielding film 113 is partially removed, thereby partially exposing the light transmissive film 112, and the light shielding film 113 and the translucent film 112 are bonded to each other. It becomes the state which was immersed together in electrolyte solution (etching liquid) in the state which has a part. Here, the light shielding film 113 and the semitransmissive film 112 are materials containing different metals, respectively, and have a certain degree of conductivity, so that the light shielding film and the semitransmissive film immersed in the electrolyte are similar to, for example, a galvano battery. Construct a chemical cell. From this point on, the ionization behavior of Mo in the translucent film 112, the etching rate of the light shielding film 113, and the like are affected by the electron movement by the formed battery (also referred to as a battery effect). According to the inventor's knowledge, the composition of the translucent film 112 exposed by such a battery effect may change locally. This battery effect will be described with reference to FIGS. 10A and 10B.

10A shows a measurement system of an etching rate, and shows a Cr single plate made of Cr, a Mo single plate made of Mo, and a Cr-Mo stacked plate (the different metals are in contact with each other and conducting), wherein the Cr plate and Mo plate are stacked together. The state immersed in the above-mentioned chromium etching liquid is shown, respectively. It is a graph which shows the measurement result of each etching rate of Cr single plate, Cr-Mo laminated board, and Mo single board. According to FIG. 10B, it turns out that the etching rate of Cr in a Cr-Mo laminated board reduces to less than half of the etching rate of Cr of a Cr single plate. Moreover, it turns out that the etching rate of Mo in Cr-Mo laminated board is increasing more than the etching rate of Mo of Mo single board. That is, when immersing dissimilar metals that are conductive with each other in an electrolyte solution, the etching rate is affected, and the etching rate of the metal (here, Cr) with the smaller tendency of ionization is lowered, and the metal having the higher tendency of ionization ( It can be seen that the etching rate of Mo) is increased here. From the above results, in the wet etching of the multi-gradation photomask 100, the light shielding film 113 and the translucent film 112 containing different metals each have predetermined conductivity, and both are in a conductive state. When the light shielding film 113 or the semi-transmissive film 112 is immersed in the etching solution alone by contacting the etching liquid, etching behavior may be different, and it is understood that the elution tendency of the metal in the film changes.

Here, the magnitude of the elution tendency of the translucent film 112 by performing the said 1st etching process changes locally according to the shape of a transfer pattern. That is, depending on the shape of the transfer pattern, many light shielding film patterns exist in the vicinity, or there are no light shielding film patterns in the vicinity. In the part where the area of a semi-transmissive part is large, like the latter, there is no light shielding film pattern in the vicinity, or it is easy to be in a small state. According to the findings of the inventors, in the conventional manufacturing process of a multi-gradation photomask, the strength of the battery effect described above is determined by the area of the translucent portion of the transfer pattern to be obtained, the area ratio with the light shielding portion, the mutual distance, and the difference between the shapes. As a result, the elution tendency of Mo from the translucent film 112 becomes nonuniform, and as a result, the elution amount of Mo from the translucent film 112 is locally different, resulting in a semi-translucent film. The composition of (112) may become nonuniform in surface. For example, a phenomenon may occur in which Si-rich regions and Mo-rich regions are locally formed. This phenomenon is considered to be as shown in Figs. 6A and 6B.

FIG. 6A is a schematic diagram showing a state in which the amount of Mo elution from the translucent film 112 is locally different in the etching process of the light shielding film 113 when a conventional multi-gradation photomask is manufactured, FIG. 6B Is a schematic diagram showing a state in which the amount of reduction of the translucent film is locally different in the process of reducing the translucent film 112 when manufacturing a conventional multi-gradation photomask. 6A and 6B show cross-sectional views of pixel patterns (TFT patterns), respectively. In the pixel pattern, the translucent film 112 made of MoSi and the light shielding film 113 made of Cr are stacked in this order on the transparent substrate 110 without interposing the conductive film 111. The light shielding film 113 is formed by etching the light shielding film 113 using the chromium etching solution (electrolyte solution) described above using the resist pattern 131p formed on the light shielding film 113 as a mask. The upper surface of the light transmitting film 112 is partially exposed. 6A and 6B show cross-sectional views of the peripheral pattern (PAD pattern) configured as a pattern different from the pixel pattern. As above, the upper surface of the translucent film 112 is partially exposed. The pixel pattern may have a line width of 10 to 300 µm, and the peripheral pattern may have a line width of 20 to 8000 µm, for example, and the transfer pattern may have a larger line width of the peripheral pattern than the line width of the pixel pattern.

As shown in FIG. 6A, when the semi-transmissive film 112 is exposed to contact the etching liquid (electrolyte), Mo included in the translucent film 112 is ionized, for example, Mo → Mo ³⁺ + 3e ^−. Reactions occur. Here, in the semi-transmissive film 112 constituting the left pixel pattern in the figure, the light-shielding film pattern 113p (light-shielding film 113) and the semi-transmissive film 112, which are the sources of electrons (e-), are electrically bonded to each other. Therefore, the above-mentioned ionization is promoted (the amount of Mo elution increases because the tendency of the ionization of Mo is large compared with Cr contained in the light shielding film). On the other hand, in the figure, the semi-transmissive film 112 constituting the peripheral pattern on the right side is not electrically bonded to the light-shielding film 113 and the semi-transmissive film 112 serving as electrons in the same state as the pixel pattern portion. Compared to the semi-transmissive film 112 constituting the pixel pattern, the above-mentioned ionization proceeds less promoted (the area where the light-shielding film 113 and the semi-transmissive film 112 are bonded to each other, or the light-shielding film 113 and the semi-transmissive light). Since the contact area with each etching liquid of the film 112 is different in the pixel pattern and the peripheral pattern, the electrons between the light shielding film 113 and the translucent film 112 in the peripheral pattern compared with the pixel pattern. The method of generating a battery effect is different, such as the exchange of is difficult, in which case the amount of Mo elution is relatively small compared to the pixel pattern portion). As a result, the surface of the semi-transmissive film 112 constituting the pixel pattern is formed as a region (Si-rich region) having a lower Mo content than the stoichiometric composition ratio of the semi-transmissive film composition containing MoSi. (Modified). In addition, the surface of the semi-transmissive film 112 constituting the peripheral pattern has a region (Mo-rich region) having a composition close to the stoichiometric composition ratio of the semi-transmissive film composition containing MoSi.

As described above, when the above-mentioned chemical liquid is supplied to the translucent film 112 having a locally changed composition, and the translucent film 112 is reduced, as shown in FIG. 6B, the amount of the reduced film is localized according to the composition. As a result, the light transmittance of the translucent film 112 becomes uneven in plane. For example, since the composition is modified as a Si rich region in the vicinity of the surface of the semi-transmissive film 112 constituting the pixel pattern on the left side in the drawing, the amount of film reduction due to supply of the chemical liquid is relatively large. In addition, since the vicinity of the surface of the translucent film 112 which comprises the peripheral pattern on the right side is formed as Mo rich area | region, the amount of film reduction by supplying chemical liquid becomes comparatively small. As a result, the light transmittance of the transflective film 112 which comprises a pixel pattern becomes larger than the light transmittance of the transflective film 112 which comprises a peripheral pattern.

With respect to such a problem, in the present embodiment, the conductive film 111 having conductivity is formed on the lower layer side of the translucent film 112 so that the composition change of the translucent film 112 is equalized over the surface, and the chemical liquid is formed. Local changes in the amount of the film with the supply are suppressed.

FIG. 7A is a schematic diagram showing a state in which the change in composition of the translucent film 112 is equalized in plane by forming the conductive film 111, and FIG. 7B is a semi-translucent film by forming the conductive film 111. It is a schematic diagram which shows the state in which the film-reduction amount of 112 is equalized in surface. 7A and 7B show cross-sectional views of pixel patterns (TFT patterns), respectively. In the pixel pattern, the translucent film 112 made of MoSi and the light shield film 113 made of Cr are shown on FIGS. 7A and 7B on the transparent substrate 110 via the conductive film 111 made of a metal or a metal compound. They are stacked in the order shown. The light shielding film 113 is formed by etching the light shielding film 113 using the chromium etching solution (electrolyte solution) described above using the resist pattern 131p formed on the light shielding film 113 as a mask. The upper surface of the light transmitting film 112 is partially exposed. 7A and 7B show cross sections of a peripheral pattern (PAD pattern) configured as a pattern different from the pixel pattern. Similarly, in the peripheral pattern, the upper surface of the translucent film 112 is partially exposed with the progress of etching.

As shown in FIG. 7A, when the semi-transmissive film 112 is exposed to contact the etching liquid (electrolyte), Mo included in the translucent film 112 is ionized, for example, Mo → Mo ³⁺ + 3e ^−. Reactions occur. Also in the present embodiment, in the semi-transmissive film 112 constituting the left pixel pattern in the drawing, the light-shielding film 113 serving as the source of electrons (e-) and the semi-transmissive film 112 are electrically bonded to each other. The transflective film 112 which comprises the peripheral pattern on the right side is not joined by the light shielding film 113 which accepts an electron, and the translucent film 112 in the state similar to a pixel pattern (as in the case of a conventional example). In the pixel pattern and the peripheral pattern, a battery effect generation method is mainly different from the pattern shape difference). However, in this embodiment, the semi-transmissive film 112 which comprises the pixel pattern of the left side in the figure, and the semi-transmissive film 112 which comprises the peripheral pattern of the right side in the figure are made through the electroconductive film 111 which is a base. It is electrically bonded. That is, the transflective film 112 which comprises the peripheral pattern of the right side in the figure is comprised so that electron (e-) can be supplied to the transflective film 112 which comprises the pixel pattern of the left side in the figure. . As a result, the tendency of ionization of Mo contained in the translucent film 112 is equalized over the surface. As a result, the composition of the translucent film 112 is equalized over the surface. That is, the elution tendency of Mo contained in the semitransmissive film 112 constituting the pixel pattern and the elution tendency of Mo contained in the semitransmissive film 112 constituting the peripheral pattern are equalized to form a pixel pattern. The composition of the translucent film 112 and the composition of the translucent film 112 constituting the peripheral pattern are equalized.

Thus, when the above-mentioned chemical | medical solution is supplied to the translucent film 112 in the state which suppressed the local change of a composition, and the photoresist film is performed, as shown in FIG. 7B, a translucent film Local changes in the film-reduction amount of 112 can be avoided, and the in-plane uniformity of the light transmittance can be improved. For example, the amount of reduction of the semi-transmissive film 112 constituting the right pixel pattern in the figure and the amount of reduction of the semi-transmissive film 112 constituting the right peripheral pattern in the figure can be equalized. The light transmittance can be equalized.

The measurement result which supports the above-mentioned effect is further demonstrated using FIG. 8 and FIG. 8 is a graph according to the embodiment of the present invention, and shows the measurement results of the light transmittance of the semi-transmissive film when the film-reducing process is repeated. In this embodiment, the photomask blank 100b in which the conductive film 111, the translucent film 112, and the light shielding film 113, which are conductive, are laminated in this order on the transparent substrate 110 is prepared, and described above. One first etching step and second etching step were performed. Thereafter, a photoresist step of supplying a chemical solution to the upper surface of the remaining semi-transmissive film 112 was performed three times. In addition, in the figure, a mark indicates the light transmittance of the semitransmissive film 112 constituting the pixel pattern, and a mark in the figure indicates the light transmittance of the semitransmissive film 112 constituting the peripheral pattern.

According to FIG. 8, even when the film reduction process is performed three times, the difference between the light transmittance of the semitransmissive film 112 constituting the pixel pattern and the light transmittance of the semitransmissive film 112 constituting the peripheral pattern is about 2 It can be seen that it is suppressed within%. That is, it is understood that by forming the conductive film 111, it is possible to suppress the change of the local film amount in the translucent film 112, thereby improving the in-plane uniformity of the light transmittance of the translucent portion 122. Can be.

9 is a graph according to a comparative example, and shows the measurement results of the light transmittance of the semitransmissive film when the film forming step was repeated. In this comparative example, the photomask blank in which the transflective film 112 and the light shielding film 113 were laminated | stacked in this order on the transparent substrate 110, without forming the electroconductive conductive film 111, The same process as that of the 1st etching process and the 2nd etching process which were mentioned above was implemented. Thereafter, the photoresist step of supplying the chemical liquid to the upper surface of the remaining semi-transmissive film 112 was performed twice (the third time was not performed). In addition, in the figure, the mark indicates the light transmittance of the semi-transmissive film 112 constituting the pixel pattern, and the mark in the figure indicates the light transmittance of the semi-transmissive film 112 constituting the peripheral pattern.

9, the difference between the light transmittance of the transflective film 112 constituting the pixel pattern and the light transmittance of the transflective film 112 constituting the peripheral pattern increases each time the photoresist process is repeated. Able to know. And it turns out that the difference in light transmittance will increase to 12.5% by performing two film reduction processes.

As described above, according to the present embodiment, by forming the conductive film 111, it is possible to suppress the change of the local film amount in the semi-transmissive portion 122 regardless of the shape of the transfer pattern, thereby in-plane of the light transmittance. It can be seen that uniformity can be improved. Thereby, it becomes possible to improve the manufacturing yield of a multi-gradation photomask, FPD, etc.

In addition, the effect which concerns on this embodiment is remarkable when both the translucent film 112 and the light shielding film 113 have some degree of electroconductivity. In such a case, it is because the above-mentioned battery is comprised by performing a 1st etching process (wet etching). Therefore, for example, when both the translucent film 112 and the light shielding film 113 are made of a conductive material of 20 k? /? Or less, moreover, 5 k? /? Or less, the effect of the present embodiment is remarkably obtained. .

In addition, the conductive film 111 which concerns on this embodiment should just have electroconductivity of the grade which exhibits the electron carrying action and supply action for equalizing in-plane etching behavior. Moreover, it is more preferable to have electroconductivity (low sheet resistance value) higher than the electroconductivity which the transflective film 112 and the light shielding film 113 have. Moreover, it is preferable to have the sheet resistance value of 1/5 or less of the value of the sheet resistance which the transflective film 112 and the light shielding film 113 have, respectively. Thereby, even if a transfer pattern has various shape distribution and density distribution in surface inside, the effect which electron supply is performed smoothly is fully achieved and the in-plane electric potential in the whole transfer pattern can be equalized. In the present invention, the PAD pattern may be formed outside the region of the pixel pattern for measuring the transmittance of the semi-transmissive portion of the photomask. For example, it can be formed as a square semi-transmissive film pattern of one side 3 mm or more. At this time, according to the present invention, in order to make the film-reduction amount of the in-plane semi-transmissive film 112 uniform, it can also be used as an index indicating the transmittance of the semi-transmissive film 112 in the pixel pattern portion.

<Other embodiments of the present invention>

The multi-gradation photomask 100 'according to the present embodiment is different from the above-described embodiment in that the multi-gradation photomask 100' is configured as a 4-gradation photomask.

FIG. 3A is a partial cross-sectional view (schematic diagram) of the multi-gradation photomask 100 'according to the present embodiment, and FIG. 3B shows the transfer object 1 by a pattern transfer process using the multi-gradation photomask 100'. It is a partial cross section of a resist pattern formed on it. 4 is a schematic diagram illustrating a flow of a manufacturing process of the multi-gradation photomask 100 'according to the present embodiment.

(1) Composition of multi-gradation photomask

The multi-gradation photomask 100 'according to the present embodiment includes a light shielding portion 121 for shielding exposure light (light transmittance of approximately 0%) when the multi-gradation photomask 100' is used, and the exposure light. 5% or more and 70% or less (when the light transmittance of the light transmitting portion 123 is 100%. The same applies hereinafter), preferably the first semi-transmissive portion 122a is reduced to about 5% or more and 50% or less. And a second semi-transmissive portion 122b for reducing the light transmittance of the exposure light to 5% or more and 80% or less, preferably 7% or more and 70% or less, and a transfer portion including the light-transmitting portion 123 for transmitting the exposure light 100%. It has a pattern.

In the light shielding portion 121, similarly to the above-described embodiment, the conductive conductive film 111, the translucent film 112, and the light shielding film 113 are laminated on the transparent substrate 110 in this order. The first semi-transmissive portion 122a is formed by stacking the conductive film 111 and the translucent film 112 on the transparent substrate 110 in this order, similarly to the semi-transmissive portion 122 of the above-described embodiment. . The second translucent portion 122b is formed by exposing the conductive film 111 formed on the transparent substrate 110. In the light transmitting portion 123, the transparent substrate 110 is partially exposed as in the above-described embodiment. Here, the upper surface of the light shielding film 113 constituting the light shielding portion 121 is not limited to being exposed, and another film may be formed on the light shielding film 113. In addition, the state in which the conductive film 111, the transflective film 112, and the light shielding film 113 are patterned is mentioned later.

The structures of the transparent substrate 110, the conductive film 111, the translucent film 112, and the light shielding film 113 are the same as in the above-described embodiment. Moreover, even if the thickness of the conductive film 111 which comprises the 2nd semi-transmissive part 122b is thinner than the thickness of the conductive film 111 which comprises the light shielding part 121 and the 1st semi-transmissive part 122a, it may be reduced. do. This makes it possible to precisely adjust the light transmittance of the second semi-transmissive portion 122b to a desired value.

A partial cross-sectional view of the resist pattern 4p 'formed on the transfer object 1 by the pattern transfer process using the multi-gradation photomask 100' is illustrated in FIG. 3B. The resist pattern 4p 'is formed by irradiating and developing exposure light to the positive resist film 4 formed on the to-be-transferred body 1 through the multi-gradation photomask 100'. The to-be-transferred body 1 is equipped with the board | substrate 2 and arbitrary to-be-processed layers 3a-3c, such as a metal thin film, an insulating layer, and a semiconductor layer laminated | stacked in this order on the board | substrate 2, and are positive type It is assumed that the resist film 4 is previously formed with a uniform thickness on the processing layer 3c. In addition, the processing layer 3b may be configured to be resistant to etching of the processing layer 3c, and the processing layer 3a may be configured to be resistant to etching of the processing layer 3b.

When the exposure light is irradiated to the positive resist film 4 through the multi-gradation photomask 100 ', the exposure light does not pass through the light shielding portion 121, and the first semi-transmissive portion 122a and the second semi-transmissive layer are exposed. The light amount of the exposure light increases step by step in the order of the light portion 122b and the light transmitting portion 123. In the positive resist film 4, the film thickness becomes thinner in order in the regions corresponding to each of the light blocking portion 121, the first semi-transmissive portion 122a, and the second semi-transmissive portion 122b, and thus the light-transmitting portion 123 is used. Is removed from the area corresponding to). In this manner, a resist pattern 4p 'having a different film thickness in steps is formed on the transfer target 1.

When the resist pattern 4p 'is formed, the to-be-processed layers 3c-3a exposed in the area | region which is not covered with the resist pattern 4p' (region corresponding to the light transmission part 123) are sequentially ordered from the surface side. Can be removed by etching (first etching). Then, the resist pattern 4p 'is filmed (ashed) to remove the region having the smallest film thickness (region corresponding to the second translucent portion 122b), and the newly exposed target layers 3c and 3b are sequentially removed. It is removed by etching (second etching). Then, the resist pattern 4p 'is further reduced to remove the next thin region (region corresponding to the first translucent portion 122a), and the newly exposed workpiece layer 3c is etched and removed. (Third etching). In this manner, by using the resist pattern 4p 'having a different film thickness stepwise, the conventional three-step process for the photomask can be performed, the number of masks can be reduced, and the photolithography process can be simplified.

(2) Manufacturing method of multi-gradation photomask

Next, the manufacturing method of the multi-gradation photomask 100 'which concerns on this embodiment is demonstrated, referring FIG.

(Photomask Blank Preparation Process)

First, as illustrated in FIG. 4A, a conductive film 111 having a conductivity, a translucent film 112, and a light shielding film 113 are laminated on the transparent substrate 110 in this order. The mask blank 100b is prepared. The first resist film 131 is formed on the light shielding film 113.

(First Etching Step)

Next, drawing exposure is performed by a laser drawing machine or the like, a part of the first resist film 131 is exposed to light, and a developer is supplied to the first resist film 131 by a spraying method or the like to develop the light shielding portion. The first resist pattern 131p covering the region to be formed of 121 is formed. A state in which the first resist pattern 131p is formed is illustrated in FIG. 4B.

Next, the light shielding film 113 is etched using the formed first resist pattern 131p as a mask to form the light shielding film pattern 113p, and the upper surface of the semitransmissive film 112 is partially exposed. A state in which the light shielding film pattern 113p is formed is illustrated in FIG. 4C. Etching is performed by the etching liquid for chromium mentioned above. This etching liquid has electrical conductivity and acts as an electrolyte solution.

After the first resist pattern 131p is removed by peeling or the like, a second resist film 132 is formed to cover the upper surfaces of the remaining light shielding film 113 and the exposed semi-transmissive film 112, respectively. A state in which the second resist film 132 is formed is illustrated in FIG. 4D.

(Second etching step)

Next, drawing exposure is performed using a laser drawing machine or the like, a part of the second resist film 132 is exposed to light, and a developer is supplied to the second resist film 132 by a method such as a spray method to be developed, and at least the The second resist pattern 132p covering the region where the first translucent portion 122a is to be formed is formed. A state in which the second resist pattern 132p is formed is illustrated in FIG. 4E. In addition, as illustrated in FIG. 4E, the second resist pattern 132p is formed to cover not only the region where the first translucent portion 122a is to be formed, but also part or all of the light shielding film pattern 113p. can do.

Next, the semitransmissive film 112 is etched using the formed light shielding film pattern 113p and the second resist pattern 132p as a mask to form the semitransmissive film pattern 112p, and The top surface is partially exposed.

After the second resist pattern 132p is removed by peeling or the like, a third resist film 133 covering the upper surfaces of the remaining light shielding film 113, the semitransmissive film 112, and the exposed conductive film 111, respectively. ). A state in which the third resist film 133 is formed is illustrated in FIG. 4F.

(3rd patterning process)

Next, drawing exposure is performed by a laser drawing machine or the like, a part of the third resist film 133 is exposed to light, and a developer is supplied to the third resist film 133 by a method such as a spray method to be developed, and at least, The third resist pattern 133p covering the region where the semi-transparent portion 122b is to be formed is formed. A state in which the third resist pattern 133p is formed is illustrated in FIG. 4G. As illustrated in FIG. 4G, the third resist pattern 133p includes not only the region where the second translucent portion 122b is to be formed, but also the light shielding film pattern 113p and the semitransmissive film pattern 112p. It forms to cover part or all of.

Next, the conductive film 111 is etched using the formed third resist pattern 133p as a mask to form the conductive film pattern 111p, and the upper surface of the transparent substrate 110 is partially exposed.

(Filming process)

After the third resist pattern 133p is peeled off and removed, the chemical liquid is supplied to the upper surface of the remaining semi-transmissive film 112 (the semi-transmissive film pattern 112p), and the semi-transmissive film 112 (the semi-transmissive film) The film thickness of the pattern 112p is reduced, and the manufacturing method of the multi-gradation photomask 100 'which concerns on this embodiment is complete | finished. The photoresist of the translucent film 112 is performed for the purpose of, for example, fine adjustment of the light transmittance of the translucent portion 122.

In addition, in this process, the difference between the film thickness of the transflective film 112 which comprises the translucent part 122, and the film thickness of the transflective film 112 which comprises the light shield part 121 is 0.5 nm, for example. The film is reduced to have a range of 15 nm or less. In addition, in the said aspect, although the photosensitive process of a 2nd semi-transmissive layer was made into the last step of a photomask manufacturing process, you may perform after the etching of the light shielding film 113 which made the said 1st resist pattern 131p the mask. As the chemical liquid for reducing the semi-transmissive film 112, for example, a fluorine (F) -based etching solution, an acid, an alkali, or the like can be used.

Also by this embodiment, it is possible to exhibit the same effect as embodiment mentioned above. That is, by forming the conductive film 111, it becomes possible to improve the in-plane uniformity of the light transmittance in the translucent portion 122 regardless of the shape of the transfer pattern. Thereby, it becomes possible to improve the manufacturing yield of a multi-gradation photomask, FPD, etc.

<Another embodiment of the present invention>

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to embodiment mentioned above, It can variously change in the range which does not deviate from the summary.

For example, as illustrated in FIG. 5, the light transmitting part 123 included in the multi-gradation photomask 100 described above is configured such that the conductive film 111 formed on the transparent substrate 110 is exposed. You may be.

100, 100 ': Multi-gradation photo mask
100b: photomask blank
110: transparent substrate
111: conductive film
112: translucent membrane
113: light shielding film
121: light shield
122: translucent part
122a: first translucent part
122b: second translucent portion
123: floodlight

Claims (8)

A manufacturing method of a multi-gradation photomask which forms a predetermined transfer pattern including a light shielding portion, a light transmitting portion, and a semi-transmissive portion on a transparent substrate,
Preparing a photomask blank in which a conductive film having a conductivity, a translucent film, and a light shielding film are laminated on the transparent substrate in this order;
A first etching step of etching the light shielding film at least using a first resist pattern formed on the photomask blank as a mask;
After removing the first resist pattern, a second resist pattern is formed on the photomask blank on which the first etching process is performed, and the second resist pattern is etched using the second resist pattern and the light shielding film as masks. Etching process,
After removing the second resist pattern, a film reduction process of reducing the exposed semi-transmissive film by a predetermined amount
Method for producing a multi-gradation photomask having a. The method of claim 1,
The method of manufacturing a multi-gradation photomask, wherein the chemical solution is brought into contact with the exposed semi-transmissive film in the photoresist step. The method according to claim 1 or 2,
The said electroconductive film has electroconductivity that a sheet resistance value becomes 20 kPa / square or less, The manufacturing method of the multi-gradation photomask characterized by the above-mentioned. The method according to claim 1 or 2,
The multi-gradation photomask is used for the manufacture of a liquid crystal display device,
The transfer pattern is,
A predetermined pixel pattern,
And a peripheral pattern different in pattern shape from the pixel pattern. A multi-gradation photomask in which a predetermined transfer pattern including a light shielding portion, a light transmitting portion, and a semi-transmissive portion is formed on a transparent substrate,
The light shielding portion is formed by stacking a conductive conductive film, a semi-transmissive film, and a light shielding film on the transparent substrate in this order,
The semi-transmissive portion is formed by stacking the conductive film and the translucent film on the transparent substrate in this order,
The light transmitting portion is formed by exposing the transparent substrate,
The film thickness of the said transflective film which comprises the said translucent part is reduced so that it may become smaller than the film thickness of the said transflective film which comprises the said light shielding part,
In-plane distribution of the light transmittance of the said transflective film which comprises the said transflective part is 2% or less with respect to the light whose wavelength is 365 nm or more and 436 nm or less.
Multi-gradation photomask, characterized in that. The method of claim 5,
The difference between the film thickness of the said translucent film which comprises the said translucent part, and the film thickness of the said translucent film which comprises the said light shielding part is the range of 0.5 nm or more and 15 nm or less. A multi-gradation photomask in which a predetermined transfer pattern including a light blocking portion, a light transmitting portion, a first semi-transmissive portion, and a second semi-transmissive portion is formed on a transparent substrate,
The light shielding portion is formed by stacking a conductive conductive film, a semi-transmissive film, and a light shielding film on the transparent substrate in this order,
The first translucent portion is formed by laminating the conductive film and the translucent film on the transparent substrate in this order,
The second translucent portion is formed by exposing an upper surface of the conductive film formed on the transparent substrate,
The light transmitting portion is formed by exposing the transparent substrate,
The film thickness of the said transflective film which comprises the said 1st translucent part is reduced so that it may become smaller than the film thickness of the said transflective film which comprises the said light shielding part,
The in-plane distribution of the light transmittance of the said transflective film which comprises the said 1st translucent part is 2% or less with respect to the light whose wavelength is 365 nm or more and 436 nm or less. As a photomask blank for manufacturing a multi-gradation photomask in which a predetermined transfer pattern including a light shielding portion, a light transmitting portion, and a semi-transmissive portion is formed on a transparent substrate,
A photomask blank having a layer structure in which a conductive film, a translucent film, and a light shielding film are laminated in contact with each other in this order,
The translucent film is made of molybdenum silicide or a compound thereof,
The light shielding film is made of chromium or a chromium compound,
The sheet resistance value of the said electroconductive film and the sheet resistance value of the said translucent film are 20 kPa / square or less, respectively.
A photomask blank.

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