JP6233538B2 - Mask blank substrate and mask blank - Google Patents

Description

  The present invention relates to a mask blank substrate and a mask blank.

  In the field of semiconductor manufacturing, when a pattern is formed on a substrate to be processed such as a silicon wafer, a pattern transfer technique using exposure light and a mask is used.

  In this pattern transfer technology, the pattern of the mask can be transferred to the surface of the substrate to be processed (usually the resist surface) by irradiating the substrate to be processed with exposure light through the mask (hereinafter, this process). Is also referred to as “transfer process”). Thereafter, by developing the resist, a substrate to be processed on which a resist having a desired pattern is placed can be obtained.

  In particular, recently, in order to enable fine pattern transfer, attention has been focused on ArF exposure technology using ArF excimer laser light and EUV exposure technology using EUV exposure light.

  For example, in the EUV exposure technology, EUV (Extreme Ultra-Violet) light having a shorter wavelength than ArF excimer laser light is used as exposure light. Here, the EUV light includes soft X-rays and vacuum ultraviolet light, and specifically has a wavelength of about 0.2 nm to 100 nm. At present, EUV light having a wavelength of about 13.5 nm is mainly studied as exposure light.

  In general, in the transfer process described above, a mask is used in a state of being mounted (chucked) on a stage of an exposure apparatus such as a stepper.

  However, it is often accepted that the mask is deformed when the mask is chucked to the stage.

  Such mask deformation may reduce the accuracy of the transfer process. In particular, in recent ArF exposure technology and EUV exposure technology, since the wavelength of the exposure light is short, slight deformation of the mask can greatly affect the accuracy of the transfer process. As a result, there may arise a problem that it becomes difficult to transfer a desired pattern to the substrate to be processed.

  The present invention has been made in view of such a background, and the present invention provides a mask blank substrate and a mask blank capable of significantly suppressing deformation when a mask is chucked on an exposure apparatus. With the goal.

In the present invention, a mask blank substrate having first and second main surfaces facing each other,
Wherein the first substantially central portion of the main surface, a side length of present standard region in the shape of a square L _2,
The standard area is composed of a frame-like area corresponding to the outer peripheral part of the standard area, and an inner area surrounded by the frame-like area,
The interior region has a length _{L 3} of a side a square 132 mm,
The frame-like region has an outer frame consisting of four sides that match each square side of the standard region, and an inner frame consisting of four sides that match each side of the square of the inner region, and the outer frame Corresponds to the shape of the inner frame expanded such that each side of the inner frame translates outward by 8 mm,
When the vertices of the outer frame of the frame-shaped region are vertices A ₂ , B ₂ , C _2, and D ₂ , respectively, the frame-shaped region has first to first corners. a fourth corner regions, a first corner region comprises a vertex a _2, the second corner region comprises a vertex B _2, third corner region comprises a vertex C _2, the fourth corner region includes vertex D _2, each corner region with a side length of a square-shaped 8 mm,
In the frame-like region, a square first central region having a side length of 8 mm is defined at an intermediate position between the first corner region and the fourth corner region. A second central region having a square length of 8 mm is defined at an intermediate position of the second corner region, and one side is positioned at an intermediate position between the second corner region and the third corner region. A square third central region having a length of 8 mm is partitioned, and a square fourth central region having a side length of 8 mm is provided at an intermediate position between the third corner region and the fourth corner region. Is partitioned,
(I) The flatness F _in1 of the inner region defined based on the least square plane PP ₁ of the standard region is 100 nm or less,
(Ii) One corner area of the frame-shaped area is defined as an nth corner area, and two central areas closest to the nth corner area are defined as a first adjacent central area and a second adjacent central area, respectively. ,
The maximum height of the n-th corner area defined based on the least square plane PP ₁ is H _max (C _n ), the minimum height is H _min (C _n ), and the maximum of the first adjacent central area is The height is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second adjacent central region is H _max (M ₂ ), and the minimum height is H _min (M 1). ₂ )
In any of n = 1 to 4, the following formula (1)

ΔD = Max {H _max (C _n ) −H _min (M ₁ ), H _max (C _n ) −H _min (M ₂ ), H _max (M ₁ ) −H _min (C _n ), H _max (M _{2) -H min (C n)} } (1) formula

The maximum height difference ΔD represented by is 100 nm or less,
_{Here, Max {x 1, x 2} , x 3, x 4} _means the maximum value of x 1 ~x _4, the mask blank substrate is provided.

In the present invention, a mask blank having a substrate,
The mask blank has a first main surface and a second main surface;
The second main surface is a main surface on the side where a circuit pattern layer is disposed,
Wherein the first substantially central portion of the main surface, a side length of present standard region in the shape of a square L _2,
The standard area is composed of a frame-like area corresponding to the outer peripheral part of the standard area, and an inner area surrounded by the frame-like area,
The interior region has a length _{L 3} of a side a square 132 mm,
The frame-like region has an outer frame consisting of four sides that match each square side of the standard region, and an inner frame consisting of four sides that match each side of the square of the inner region, and the outer frame Corresponds to the shape of the inner frame expanded such that each side of the inner frame translates outward by 8 mm,
When the vertices of the outer frame of the frame-shaped region are vertices A ₂ , B ₂ , C _2, and D ₂ , respectively, the frame-shaped region has first to first corners. a fourth corner regions, a first corner region comprises a vertex a _2, the second corner region comprises a vertex B _2, third corner region comprises a vertex C _2, the fourth corner region includes vertex D _2, each corner region with a side length of a square-shaped 8 mm,
In the frame-like region, a square first central region having a side length of 8 mm is defined at an intermediate position between the first corner region and the fourth corner region. A second central region having a square length of 8 mm is defined at an intermediate position of the second corner region, and one side is positioned at an intermediate position between the second corner region and the third corner region. A square third central region having a length of 8 mm is partitioned, and a square fourth central region having a side length of 8 mm is provided at an intermediate position between the third corner region and the fourth corner region. Is partitioned,
(Iii) The flatness F _in1 of the inner region determined based on the least square plane PP ₁ of the standard region is 200 nm or less,
(Iv) One corner area of the frame-shaped area is an nth corner area, and two central areas closest to the nth corner area are a first adjacent central area and a second adjacent central area, respectively. ,
The maximum height of the n-th corner area defined based on the least square plane PP ₁ is H _max (C _n ), the minimum height is H _min (C _n ), and the maximum of the first adjacent central area is The height is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second adjacent central region is H _max (M ₂ ), and the minimum height is H _min (M 1). ₂ )
In any of n = 1 to 4, the following formula (1)

ΔD = Max {H _max (C _n ) −H _min (M ₁ ), H _max (C _n ) −H _min (M ₂ ), H _max (M ₁ ) −H _min (C _n ), H _max (M _{2) -H min (C n)} } (1) formula

The maximum height difference ΔD represented by is 150 nm or less,
_{Here, Max {x 1, x 2} , x 3, x 4} _means the maximum value of x 1 ~x _4, the mask blank is provided.

  According to the present invention, it is possible to provide a mask blank substrate and a mask blank that can significantly suppress deformation when the exposure apparatus chucks the mask.

It is the top view which showed typically an example of the board | substrate for mask blanks by one Embodiment of this invention. It is sectional drawing which showed typically an example of the structure of the reflective mask blank by one Embodiment of this invention. It is sectional drawing which showed typically an example of the structure of the transmissive | pervious mask blank by one Embodiment of this invention. In Example 1, it is the figure which showed typically distribution of the contour line in the 1st main surface assumed in the case of local polishing process. In Example 2, it is the figure which showed typically distribution of the contour line in the 1st main surface assumed in the case of local polishing process. In Example 3, it is the figure which showed typically distribution of the contour line in the 1st main surface assumed in the case of local polishing process. It is the graph which plotted the relationship between the maximum height difference (DELTA) D obtained in each sample, and the flatness _Fin2 of the 2nd main surface at the time of chucking. It is the graph which plotted the relationship between the maximum height difference (DELTA) D obtained in each mask blank, and the flatness _Fin2 of the 2nd main surface at the time of chucking.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the present application, “mask blank” means a substrate having a layer before being patterned into a desired pattern on one main surface, unlike a mask having a layer patterned on one main surface. Thus, in the usual case, in the “mask blank” phase, the layer is placed over the entire major surface of the substrate. Further, the “mask blank substrate” means a substrate before the above-described layer is provided on the main surface.

(Mask blank substrate according to an embodiment of the present invention)
An embodiment of the present invention will be described with reference to FIG. FIG. 1 schematically shows an example of a mask blank substrate according to an embodiment of the present invention.

As shown in FIG. 1, a mask blank substrate (hereinafter referred to as “first substrate”) 100 according to an embodiment of the present invention includes a first main surface 102 and a second main surface 104 that face each other. Have. The first substrate 100 (a first main surface 102 of) has a substantially square shape, the length _{L 1} of one side is, for example, 152 mm.

The first substrate 100 has a standard region 120 (a region within a frame indicated by a thick frame in FIG. 1) substantially at the center of the first main surface 102. Standard area 120, the length of one side is a square L _2. The length _{L 2} is 148 mm. In the example shown in FIG. 1, the contour line (square) 110 of the first main surface 102 coincides with a shape in which each side of the standard region 120 is expanded outward by 2 mm, for example.

  The standard area 120 includes a frame-shaped area 130 corresponding to the outer peripheral portion of the standard area 120 and an internal area 140 surrounded by the frame-shaped area 130. In other words, the frame-shaped region 130 corresponds to a region obtained by removing the internal region 140 from the standard region 120.

Interior region 140 is present in the substantially central portion of the standard region 120, the length _{L 3} of a side of a square-shaped 132 mm. The sides of the inner region 140 are referred to as a first side (upper side) 142, a second side 144, a third side (lower side) 146, and a fourth side 148, respectively, counterclockwise from the upper side.

  The frame-like region 130 is partitioned by an outer frame and an inner frame. The outer frame of the frame-shaped region 130 includes first outer sides 143 to fourth outer sides 149 that coincide with the respective sides of the standard region 120. In addition, the inner frame of the frame-shaped region 130 includes first inner side 142 to fourth inner side 148 that coincide with the respective sides of the inner region 140.

  In addition, in the outer frame and the inner frame of the frame-shaped region 130, the interval between the corresponding outer side and inner side (for example, the first inner side 142 and the first outer side 143) parallel to each other, that is, The width of the frame-like region 130 (see the length W in FIG. 1) is 8 mm for all.

Hereinafter, for the sake of clarification, the four points corresponding to the corners of the outline 110 of the first main surface 102 in the first substrate 100 are referred to as points A ₁ to D ₁ , respectively. Here, as shown in FIG. 1, each point is designated as a point B ₁ to a point D _{1 in the} counterclockwise direction, with the upper left corner being a point A ₁ .

Similarly, in the first substrate 100, the four points corresponding to the corners of the standard region 120 are referred to as points A ₂ to D ₂ , respectively. Further, the four points corresponding to the corners of the inner region 140 are referred to as points A ₃ to D ₃ , respectively. These naming methods are the same as in the case of the corner of the first main surface 102.

Furthermore, as shown in FIG. 1, an extension line of the first inner side 142 (which is also the first side of the inner region 140) of the frame-shaped region 130 on the first main surface 102 is the point of intersection with the second and fourth outer edges 145,149, respectively, and the points _{D 2} and the point _{E 2.} In addition, an extension line of the second inner side 144 (which is also the second side of the inner region 140) of the frame-shaped region 130 intersects with the third and first outer sides 147 and 143 of the frame-shaped region 130. , respectively, to a point _{F 2} and the point _{G 2.} In addition, an extension line of the third inner side 146 of the frame-like region 130 (which is also the third side of the inner region 140) intersects with the fourth and second outer sides 149 and 145 of the frame-like region 130. , Point H ₂ and point I ₂ , respectively. Further, an extension line of the fourth inner side 148 of the frame-like region 130 (which is also the fourth side of the inner region 140) intersects with the first and third outer sides 143 and 147 of the frame-like region 130. , Point J ₂ and point K ₂ , respectively.

As a result, the first corner region 161 surrounded by the squares A ₂ D ₂ A ₃ G ₂ is defined at the upper left corner of the frame-shaped region 130. In addition, a second corner region 162 surrounded by a square B ₂ F ₂ B ₃ I ₂ is defined at the lower left corner of the frame region 130, and a square C ₂ H ₂ C _{3 is formed at the} lower right corner of the frame region 130. A third corner region 163 surrounded by K ₂ is partitioned, and a fourth corner region 164 surrounded by a square D ₂ J ₂ D ₃ E ₂ is partitioned at the upper right corner of the frame-shaped region 130. Each of these corner regions 161 to 164 has a side length of 8 mm.

  In addition, as shown in FIG. 1, in the frame-shaped region 130, a square portion that is exactly in the middle between the first corner region 161 and the fourth corner region 164 is referred to as a first central region 171, and the first corner A square portion that is exactly in the middle between the region 161 and the second corner region 162 is referred to as a second central region 172, and a square portion that is exactly in the middle between the second corner region 162 and the third corner region 163 is 3, and a square portion just in the middle between the third corner region 163 and the fourth corner region 164 is referred to as a fourth central region 174.

These central regions 171 to 174 have a square shape with a side length of 8 mm. For example, the first central region 171 is represented by a square of T ₂ T ₃ M ₃ M ₂ , and the second central region 172 is represented by a square of N ₂ N ₃ O ₃ O ₂ , and the third center The region 173 is represented by a square of Q ₂ Q ₃ P ₃ P ₂ , and the fourth central region 174 is represented by a square of S ₂ S ₃ R ₃ R ₂ . Note that the points T ₂ , M ₂ , N ₂ , O ₂ , P ₂ , Q ₂ , R ₂ , and S ₂ are points on the outer sides 143, 145, 147, and 149 of the frame-like region 130, respectively. Further, the points T ₃ , M ₃ , N ₃ , O ₃ , P ₃ , Q ₃ , R ₃ , S ₃ are points on the inner sides 142, 144, 146, 148 of the frame-shaped region 130, respectively.

Here, the first substrate 100 is
(I) is determined based on the least square plane PP ₁ standard region 120, it has a characteristic that the flatness _{F in1} of the inner area 140 is 100nm or less.

The “flatness F _in1 ” of the inner region 140 can be obtained from the difference between the maximum height and the minimum height of the surface unevenness of the inner region 140 when the least square plane PP ₁ of the standard region 120 is used as a reference. .

In addition, the first substrate 100 is
(Ii) One corner area of the frame-shaped area 130 is an n-th corner area, and two central areas closest to the n-th corner area are a first adjacent central area and a second adjacent central area, respectively. ,
The maximum height of the n-th corner area defined based on the least square plane PP ₁ is H _max (C _n ), the minimum height is H _min (C _n ), and the maximum of the first adjacent central area is The height is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second adjacent central region is H _max (M ₂ ), and the minimum height is H _min (M 1). ₂ )
In any of n = 1 to 4, the following formula (1)

ΔD = Max {H _max (C _n ) −H _min (M ₁ ), H _max (C _n ) −H _min (M ₂ ), H _max (M ₁ ) −H _min (C _n ), H _max (M _{2) -H min (C n)} } (1) formula

The maximum height difference ΔD expressed by is characterized by being 100 nm or less.

_{Here, Max {x 1, x 2} , x 3, x 4} _means the maximum value of x 1 ~x _4.

  For example, when n = 1, with respect to the first corner region 161 of the frame-like region 130, the two central regions closest to the first corner region 161 are the first central region 171 and the second central region 172. It becomes.

Accordingly, the maximum height of the first corner region 161 determined based on the least square plane PP ₁ of the standard region 120 is H _max (C ₁ ), the minimum height is H _min (C ₁ ), and the first The maximum height of the central region 171 is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second central region 172 is H _max (M ₂ ), and the minimum height is When the _height is H _min (M ₂ ),
The first substrate 100 is configured such that the maximum height difference ΔD represented by the above-described equation (1) is 100 nm or less.

  When n = 2, with respect to the second corner region 162 of the frame-shaped region 130, the two central regions closest to the second corner region 162 are the second central region 172 and the third central region 173. It becomes.

Therefore, it is determined based on the least square plane PP ₁ standard region 120, the maximum height of the second corner region 162 and _H max _{(C 2),} the minimum height and _H min _{(C 2),} the second The maximum height of the central region 172 is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the third central region 173 is H _max (M ₂ ), and the minimum height is When the _height is H _min (M ₂ ),
The first substrate 100 is configured such that the maximum height difference ΔD represented by the above-described equation (1) is 100 nm or less.

  Similarly, when n = 3, with respect to the third corner region 163 of the frame-shaped region 130, the two central regions closest to the third corner region 163 are the third central region 173 and the fourth central region. 174.

Therefore, it is determined based on the least square plane PP ₁ standard region 120, the maximum height of the third corner region 163 and _H max _{(C 3),} the minimum height and _H min _{(C 3),} third The maximum height of the central region 173 is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the fourth central region 174 is H _max (M ₂ ), and the minimum height is When the _height is H _min (M ₂ ),
The first substrate 100 is configured such that the maximum height difference ΔD represented by the above-described equation (1) is 100 nm or less.

  Furthermore, when n = 4, with respect to the fourth corner region 164 of the frame-shaped region 130, the two central regions closest to the fourth corner region 164 are the fourth central region 174 and the first central region 171. It becomes.

Therefore, the maximum height of the fourth corner region 164 determined based on the least square plane PP ₁ of the standard region 120 is H _max (C ₄ ), the minimum height is H _min (C ₄ ), and the fourth The maximum height of the central region 174 is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the first central region 171 is H _max (M ₂ ), and the minimum height is When the _height is H _min (M ₂ ),
The first substrate 100 is configured such that the maximum height difference ΔD represented by the above-described equation (1) is 100 nm or less.

Here, the flatness _Fin1 of the inner region of the mask blank substrate is preferably 80 nm or less, and more preferably 50 nm or less. Further, the maximum height difference ΔD of the mask blank substrate is preferably 75 nm or less, and more preferably 50 nm or less.

  As will be described in detail later, when the mask blank substrate is configured to have the above-described features (i) and (ii), it is transferred to the film formation surface of the mask blank configured from such a mask blank substrate. When the mask provided with the pattern is chucked to the exposure apparatus, the deformation of the mask can be significantly suppressed.

  Therefore, when the first substrate 100 is applied to the mask, the conventional problem that the accuracy of the transfer process is lowered as described above can be significantly suppressed. In particular, in the case of the first substrate 100, such an effect can be exhibited even when the first substrate 100 is applied to a mask for ArF exposure technology and EUV exposure technology.

(Other features)
The first substrate 100 is made of a transparent material. For the first substrate 100, for example, quartz glass containing 90% by mass or more of SiO ₂ can be preferably used. The upper limit of the SiO ₂ content in the quartz glass is 100% by mass. Quartz glass has a smaller coefficient of linear expansion and less dimensional change due to temperature changes than general soda lime glass. Quartz glass may contain TiO ₂ in addition to SiO ₂ . Quartz glass may contain 90 to 95% by mass of SiO ₂ and 5 to 10% by mass of TiO ₂ . When the TiO ₂ content is 5 to 10% by mass, the linear expansion coefficient near room temperature is substantially zero, and the dimensional change near room temperature hardly occurs.

  Specifically, a low expansion glass having a thermal expansion coefficient at 20 ° C. of 0 ± 30 ppb / ° C. is preferable, an ultra low expansion glass having a thermal expansion coefficient at 20 ° C. of 0 ± 10 ppb / ° C. is more preferable, and a thermal expansion coefficient at 20 ° C. Particularly preferred is an ultra-low expansion glass having a 0 ± 5 ppb / ° C.

If the transmission type mask or the reflection type mask is made of glass having such a low thermal expansion coefficient, a high-definition circuit pattern can be satisfactorily transferred in response to a temperature change in the semiconductor manufacturing process. Quartz glass may contain trace components other than SiO ₂ and TiO ₂ , but preferably does not contain trace components.

  The thickness of the first substrate 100 is, for example, in the range of 6.25 mm to 6.45 mm.

  As described above, the first substrate 100 can significantly suppress deformation when chucked on the exposure apparatus as a mask.

  For example, the first substrate 100 has a flatness of the second main surface 104 when the first main surface 102 is brought into contact with the stage and the first substrate 100 is mounted on the stage by the “entire chuck method”. , 50 nm or less.

  Here, the “full-face chuck method” means “two-side chuck method” in which only two sides are chucked on the stage, or four sides are chucked on the stage in the form of a frame. Unlike the “four-side chuck method”, it means a method in which the entire main surface of the object to be mounted is chucked on the stage.

Further, the flatness of second main surface 104 (hereinafter referred to as second flatness F _in2 ) is defined in the same manner as flatness F _in1 of internal region 140 in first main surface 102 as described above. . That is, in the second main surface 104, the region corresponding to the standard region 120 on the first main surface 102 is referred to as a “back surface standard region”, and the region corresponding to the internal region 140 on the first main surface 102 is “ when the back internal region ", the second flatness F _in2, based on the least square plane PP ₂ backside standard region can be determined from the difference between the maximum surface irregularity height and minimum height of the back inner region .

  The features of the mask blank substrate according to the embodiment of the present invention have been described above using the first substrate 100 as an example. However, the above description is merely an example, and it will be apparent to those skilled in the art that the mask blank substrate according to the present invention may have other forms and / or features.

For example, in the example shown in FIG. 1, the first major surface 102 of the first substrate 100, the length of one side _{L 1} has a square shape of 152 mm. However, the length L ₁ of one side of the first main surface 102 and the shape of the first main surface 102 are not limited to this. That is, the first major surface 102, noted that as far as possible that the length L ₂ of one side to define a standard region 120 of 148 mm, the dimensions and shape of the first major surface 102 is not particularly limited There is a need to.

(First substrate manufacturing method)
Next, an example of a method for manufacturing the first substrate 100 having the above-described features will be briefly described.

  However, it should be noted that the method described below is merely an example, and the first substrate 100 may be manufactured by other methods. Here, a method for manufacturing the first substrate 100 will be described by taking as an example the case where the substrate is a glass substrate.

The manufacturing method of the first substrate 100 (hereinafter referred to as “first manufacturing method”)
(1) a glass substrate information acquisition step;
(2) a glass substrate polishing step;
Have

  Hereinafter, each step will be described.

(1. Information acquisition process)
First, a base glass substrate is prepared. The glass substrate has first and second main surfaces. The glass substrate has, for example, a square shape with a side length of 152 mm.

  Next, the surface unevenness profile of the first and second main surfaces of the glass substrate, the least square plane, and the PV value (difference between the maximum height and the minimum height) (hereinafter these are collectively referred to as “surface parameters”). ) Is measured. Thereby, information (hereinafter referred to as “initial surface parameter”) regarding the uneven shape of the main surface of the glass substrate before processing is acquired.

(2. Polishing process)
Next, the glass substrate is polished.

  The polishing of the glass substrate includes a preliminary polishing step, a local polishing step, and a final polishing step. Hereinafter, each process will be briefly described.

(Pre-polishing process)
First, the glass substrate is preliminarily polished.

  In this preliminary polishing step, the glass substrate is roughly polished so that the surface roughness and PV value of the first and second main surfaces of the glass substrate are within a predetermined range. At this time, the glass substrate is roughly polished based on the information on the initial surface parameters acquired in the information acquisition step.

  A known method can be applied to the preliminary polishing step. For example, the first and second main surfaces of the glass substrate may be preliminarily polished by continuously using a plurality of double-sided lapping apparatuses. At this time, a hard urethane foam or a suede pad may be used as the polishing cloth, and cerium oxide having a particle diameter of 0.5 μm to 2 μm may be used as the abrasive.

  After the preliminary polishing step, the surface parameters of the first and second main surfaces are measured again to confirm the surface state.

(Local polishing process)
Next, the first main surface of the glass substrate is locally polished.

  This local polishing step is performed by scanning a local processing tool on the first main surface of the glass substrate. A well-known thing can be used for a local processing tool. For example, an ion beam etching method, a gas cluster ion beam (GCIB) etching method, a plasma etching method, a wet etching method, a polishing method using a magnetic fluid, or a polishing method using a rotary polishing tool may be used.

  Here, the local polishing step is performed on the first main surface of the glass substrate so as to obtain the features (i) and (ii) as the first substrate 100 has. For this reason, the local polishing step may be performed assuming a distribution of contour lines on the first main surface by simulation.

  In the middle of the local polishing process, the surface parameter measurement as described above may be performed on the first main surface for confirmation.

  As a result of the measurement, when it is confirmed that the above-mentioned features (i) and (ii) are obtained on the first main surface of the glass substrate, the local polishing step is completed.

(Finishing polishing process)
Next, the first and second main surfaces of the glass substrate are finally polished.

  At this time, a polishing pad having an area larger than the main surface of the glass substrate may be used, and the main surface of the glass substrate may be polished while supplying the polishing slurry. The reason for using a large polishing pad is to polish the entire main surface of the glass substrate simultaneously.

  As a polishing pad, for example, a polishing pad having a polyurethane resin foam layer obtained by impregnating a polyurethane resin into a base fabric such as a nonwoven fabric can be used.

  The polishing slurry is usually composed of abrasive particles and a dispersion medium thereof. The polishing slurry may contain colloidal silica or cerium oxide. Colloidal silica is preferable because the glass substrate can be precisely polished.

  Examples of the dispersion medium for the abrasive particles include water and organic solvents.

  Thereby, the first and second main surfaces of the glass substrate are finally finished.

  Through the above steps, the first substrate 100 having the features (i) and (ii) described above can be manufactured.

(Mask blank according to an embodiment of the present invention)
Next, an example of a mask blank according to an embodiment of the present invention will be described. Here, each of the reflective mask blank and the transmissive mask blank will be described with reference to the drawings.

(Reflective mask blank)
FIG. 2 schematically shows a cross section of a reflective mask blank according to an embodiment of the present invention.

  As shown in FIG. 2, the reflective mask blank (hereinafter referred to as “first mask blank”) 10 has a substrate 200.

  The substrate 200 has a first main surface 202 and a second main surface 204 that face each other. A first layer 250 is disposed on the first main surface 202 of the substrate 200, and a second layer 280 is disposed on the second main surface 204 of the substrate 200.

  As shown in FIG. 2, in the first mask blank 10, the main surface on the first layer 250 side is referred to as the first main surface 12 of the first mask blank 10, and the second layer 280 side. Is referred to as the second main surface 14 of the first mask blank 10.

  The first layer 250 is a conductive film, and is made of, for example, chromium nitride. By providing the first layer 250, the first mask blank 10 can be electrostatically chucked on the stage.

  On the other hand, the second layer 280 is composed of a plurality of films. That is, the second layer 280 includes the reflective film 282, the protective film 284, the absorption film 286, and the like in order from the side close to the substrate 200.

  Among these, the reflective film 282 has a function of reflecting light such as EUV exposure light. The reflective film 282 may have, for example, a Mo film / Si film repeating structure.

  The protective film 284 has a role of protecting the reflective film 282 when the absorption film 286 is patterned. The protective film 284 may be made of, for example, Ru or a Ru compound. However, the protective film 284 is not an essential structure and may be omitted.

  The absorption film 286 is made of a material that absorbs exposure light. The absorbing film 286 is provided to have a patterned structure when the first mask blank 10 is used as a mask, and this pattern can be transferred to a substrate to be processed in a transfer process.

  Note that a low reflection film (for example, TaON or TaO) may be formed on the opposite side of the absorption film 286 from the reflection film 282. The low reflection film has lower reflection characteristics than the absorption film 286 with respect to the inspection light of the circuit pattern of the absorption film 286. Here, the reflectance of the inspection light by the low reflection film is lower than the reflectance of the inspection light by the absorption film 286.

  Note that the specifications and formation method of the first layer 250 and the second layer 280 are the same as those of the conventional reflective mask blank. Therefore, no further explanation will be given here.

  Such a 1st mask blank 10 is utilized for EUV exposure technique etc., for example.

  In the EUV exposure technique, when the first mask blank 10 is actually used as a mask, the first main surface 12 side is the side to be chucked by the stage of the exposure apparatus. Further, the second main surface 14 side is the exposure light irradiation side.

  Here, the first mask blank 10 is configured to have the above-described features (iii) and (iv).

In the features (iii) and (iv), the preferred range of the flatness F _in1 and the maximum height difference ΔD of the inner region of the first mask blank 10 is the flatness F of the first mask blank substrate 100 described above. _This is somewhat different from the preferred range of _in1 and maximum height difference ΔD.

This is because the mask blank substrate is warped by film stress when a film is formed on the mask blank substrate in order to manufacture a mask blank. As a result, in a normal case, the flatness F _in1 and the maximum height difference ΔD of the main surface of the mask blank are larger than the _{Fin 1} and ΔD of the mask blank substrate.

  However, even if such deformation occurs, if the mask blank is configured to have the above-mentioned features (iii) and (iv), the mask manufactured from the mask blank is chucked by the exposure apparatus. Therefore, the deformation of the mask can be significantly suppressed as compared with the conventional case. This also makes it possible to transfer a desired pattern to the substrate to be processed with high accuracy.

In the first mask blank 10, the flatness _Fin1 of the inner region is preferably 180 nm or less, more preferably 150 nm or less, and the maximum height difference ΔD is preferably 125 nm or less, more preferably 100 nm or less.

  Therefore, when the mask constituted by the first mask blank 10 is chucked by the exposure apparatus, the deformation of the mask can be significantly suppressed as compared with the conventional case. This also makes it possible to transfer a desired pattern to the substrate to be processed with high accuracy.

(Transparent mask blank)
FIG. 3 schematically shows a cross section of a transmission type mask blank according to an embodiment of the present invention.

  As shown in FIG. 3, the transmissive mask blank (hereinafter referred to as “second mask blank”) 20 includes a substrate 300.

  The substrate 300 has a first main surface 302 and a second main surface 304 that face each other. A first layer 380 is disposed on the first main surface 302 of the substrate 300.

  As shown in FIG. 3, in the second mask blank 20, the main surface on the first layer 380 side is referred to as the first main surface 22 of the second mask blank 20, and the main surface on the opposite side is This is referred to as the second main surface 24 of the second mask blank 20.

  Although not clear from FIG. 3, the first layer 380 may be composed of a plurality of films. Such a film may be, for example, a light shielding film and / or a halftone film.

  The specification and formation method of the first layer 380 are the same as those of a conventional transmission type mask blank. Therefore, no further explanation will be given here.

  Such a second mask blank 20 is used, for example, for ArF exposure technology.

  In the ArF exposure technique, when the second mask blank 20 is actually used as a mask, the side of the first main surface 302 of the substrate 300 is the side to be chucked by the stage of the exposure apparatus. The second main surface 304 side is the exposure light irradiation side.

  Here, the second mask blank 20 is configured to have the above-described features (iii) and (iv).

  Also in this case, when the mask constituted by the second mask blank 20 is chucked by the exposure apparatus, the deformation of the mask can be significantly suppressed as compared with the conventional case. This also makes it possible to transfer a desired pattern to the substrate to be processed with high accuracy.

  In the second mask blank 20, the maximum height difference ΔD is preferably 125 nm or less, and more preferably 100 nm or less.

  Next, examples of the present invention will be described. In the following description, Example 1 is an example, and Examples 2 and 3 are comparative examples.

(Advance preparation)
First, 13 glass substrates were prepared, and each was preliminarily polished.

As the glass substrate, a TiO ₂ doped glass substrate was used. These glass substrates have a square shape of 152 mm long × 152 mm wide.

  After preliminary polishing, the surface parameters of the first and second main surfaces of each glass substrate were measured. As a result, the difference between the maximum height and the minimum height on the first main surface of each glass substrate was in the range of 200 nm to 350 nm. The difference between the maximum height and the minimum height was measured using a flatness measuring machine manufactured by Fujinon.

  Further, the surface roughness (arithmetic average roughness Ra) on the first main surface was measured in a range of 2.8 mm × 2.1 mm using a white interferometer. As a result, the arithmetic average roughness Ra was 0.8 nm to 1.2 nm. Similar values were obtained on the second main surface.

  The thickness of each glass substrate after preliminary polishing was in the range of 6.448 mm to 6.449 mm.

(Example 1)
The first main surface was locally polished on seven pre-polished glass substrates. For local polishing, a rotary small processing tool having a polishing area of φ15 mm was used.

The local polishing conditions are as follows:
Abrasive: cerium oxide with an average particle size (D50) of 2 μm;
Polishing pad: Soft pad (Beratrix N7512, manufactured by Filwel Corporation);
Number of rotations of the polished portion: 400 rpm;
Polishing pressure: 2.5 g weight / mm ² .

  The local polishing treatment was performed on the assumption that a contour distribution as shown in FIG. 4 was obtained on the first main surface.

  FIG. 4 schematically shows the distribution of contour lines on the first main surface assumed in the local polishing process in Example 1.

  As shown in FIG. 4, the first main surface 402 includes a standard area 420 (148 mm × 148 mm), and the standard area 420 is divided into a frame-shaped area 430 and an internal area 440 (132 mm × 132 mm). Each of the contour lines 411 to 415 has a substantially square shape with rounded corners, and the center of each square coincides with the center of the first main surface 402.

  The contour lines 411 to 415 indicate that the level becomes higher (ie, the surface becomes higher) as the size of the square becomes larger, and conversely, the level becomes lower (ie, the surface becomes smaller as the size of the square becomes smaller). It will be lower). The difference in height level between adjacent contour lines is about 100 nm.

  Here, in the local polishing process, attention was paid so that the frame-shaped region 430 does not intersect as many contour lines as possible. For example, in the example of FIG. 4, only one contour line 414 that intersects the frame-like region 430 at four corner regions is introduced into the frame-like region 430, and this contour line 414 is substantially the frame-like region. It coincides with the outer frame of 430 (therefore, the portion other than the corner region of the frame-like region 430 is not substantially intersected).

  After completion of such local polishing treatment, finish polishing was performed on both main surfaces of each glass substrate.

The finish polishing conditions are as follows:
Polishing tester: Double-sided 24B polishing machine (manufactured by Hamai Sangyo Co., Ltd.);
Polishing pad: Veratrix N7512 (manufactured by Filwel);
Polishing platen rotation speed: 10 rpm;
Polishing time: 30 minutes;
Polishing load: 0.52 g weight / mm ² ;
Polishing amount: 0.06 μm / surface;
Dilution water: pure water (0.1 μm or more foreign matter filtration);
Polishing slurry: 20% by mass of colloidal silica having an average primary particle size of less than 20 nm;
Polishing slurry flow rate: 10 l / min.

  Through the above steps, seven mask blank substrates were obtained. Each mask blank substrate is referred to as Sample 1-1 to Sample 1-7.

  After the finish polishing step, the difference between the maximum height and the minimum height of each mask blank substrate was measured with a flatness measuring machine manufactured by Fujinon.

(Example 2)
In the same manner as in Example 1, the first main surface was locally polished for four pre-polished glass substrates.

  However, in Example 2, the local polishing treatment was performed assuming that the contour distribution as shown in FIG. 5 is obtained on the first main surface.

  FIG. 5 schematically shows the distribution of contour lines on the first main surface assumed in the local polishing process in Example 2.

  As shown in FIG. 5, the first main surface 402 includes a standard region 420 (148 mm × 148 mm), and the standard region 420 is divided into a frame-shaped region 430 and an inner region 440 (132 mm × 132 mm). Contour lines 511 to 515 are substantially circular, and the center of each circle coincides with the center of first main surface 402.

  The contour lines 511 to 515 indicate that the level becomes higher (that is, the surface becomes higher) as the diameter of the circle becomes larger, and conversely, the level becomes lower (that is, the surface becomes smaller as the diameter of the circle becomes smaller). It will be lower). The difference in height level between adjacent contour lines is about 100 nm.

  In this example, two contour lines 514 and 515 intersect the frame-like region 430. In the four corner regions of the frame-like region 430, there are two different height regions, a region between the contour lines 514 and 515 and a region outside the contour line 515.

  After completion of such local polishing treatment, finish polishing similar to that in Example 1 was performed on both main surfaces of each glass substrate.

  The obtained mask blank substrates are referred to as Sample 2-1 to Sample 2-4, respectively.

(Example 3)
By the same method as in Example 1, the first main surface was locally polished on two pre-polished glass substrates.

  However, in Example 3, the local polishing treatment was performed on the assumption that the contour distribution as shown in FIG. 6 was obtained on the first main surface.

  FIG. 6 schematically shows the distribution of contour lines on the first main surface assumed in the local polishing process in Example 3.

  As shown in FIG. 6, the first main surface 402 includes a standard area 420 (148 mm × 148 mm), and the standard area 420 is divided into a frame-shaped area 430 and an internal area 440 (132 mm × 132 mm). Each contour line 611 to 617 has a substantially square shape with rounded corners, and the center of each square coincides with the center of the first main surface 402.

  The contour lines 611 to 617 indicate that the level increases as the square dimension increases (that is, the surface increases). Conversely, as the square dimension decreases, the level decreases (that is, the surface decreases). It will be lower). The difference in height level between adjacent contour lines is about 100 nm.

  In this example, only one contour line 616 that intersects the frame-like region 430 at four corner regions is introduced into the frame-like region 430, and this contour line 616 is substantially the outer frame of the frame-like region 430. (Accordingly, the portion other than the corner region of the frame-like region 430 is not substantially intersected).

  After completion of such local polishing treatment, finish polishing similar to that in Example 1 was performed on both main surfaces of each glass substrate.

  The obtained mask blank substrates are referred to as Sample 3-1 and Sample 3-2, respectively.

(Evaluation)
The following evaluation was performed on each sample prepared as described above.

  Hereinafter, each region of the first main surface of each sample is represented by the name shown in FIG.

(Flatness F _{in1 of the} inner region)
On the first main surface of each sample, the flatness F _in1 of the inner region (L ₂ = 132 mm square region) of the central portion was evaluated.

As described above, the flatness F _in1 of the inner region was calculated based on the least square plane PP ₁ measured by measuring the least square plane PP ₁ in the standard region.

(Maximum height difference ΔD)
On the first main surface of each sample, the maximum height difference ΔD represented by the above-described equation (1) was calculated.

Table 1 below collectively shows the flatness _Fin1 and the maximum height difference ΔD of the inner region obtained in each sample.

（チャック時の平坦度）
次に、各サンプルを全面チャック方式でステージに真空装着させ、サンプルに生じる変形状態を評価した。評価の際、各サンプルは、第１の主表面の側がステージと接触するようにして、真空装着させた。

(Flatness when chucking)
Next, each sample was vacuum-mounted on the stage by the whole surface chuck method, and the deformation state generated in the sample was evaluated. During the evaluation, each sample was vacuum-mounted so that the first main surface side was in contact with the stage.

The state of deformation was evaluated by the second flatness _Fin2 on the second main surface of the sample. The second flatness F _in2, as described above, based on the least square plane PP ₂ backside standard region is defined.

  The evaluation results obtained for each sample are collectively shown in the column of “Flatness during chucking” in Table 1 above.

From Table 1, it can be seen that in Samples 1-7, the flatness _{Fin1 of the} inner region is 100 nm or less. In contrast, in samples 3-1 and 3-2, it can be seen that the flatness _{F in1} of the inner area is greater than 100 nm.

  In Samples 1-7, it can be seen that the maximum height difference ΔD is 100 nm or less. On the other hand, in samples 2-1 to 2-4, it can be seen that the maximum height difference ΔD exceeds 100 nm.

  Further, in Sample 1-7, the flatness at the time of chucking is 30 nm or less, whereas in Samples 2-1 to 2-4 and Samples 3-1, 3-2, the flatness at the time of chucking is It was found that the flatness exceeded 50.

  FIG. 7 shows a graph in which the relationship between the maximum height difference ΔD obtained in each sample and the flatness at the time of chucking is plotted.

  From FIG. 7, it can be seen that in Samples 2-1 to 2-4 and 3-1, 3-2, the flatness at the time of chucking exceeds 50 nm, and a very good flatness is not obtained. On the other hand, in samples 1-1 to 1-7, the flatness at the time of chucking is 50 nm or less, particularly 30 nm or less, and it can be seen that good results are obtained.

  Thus, it was confirmed that the deformation at the time of chucking is significantly suppressed by manufacturing the mask blank substrate so as to satisfy the above-mentioned features (i) and (ii).

(Example 11)
A mask blank was manufactured by the following method using Sample 1-1 obtained by the above-described method.

(Formation of conductive film)
A conductive film was formed on the first main surface of Sample 1-1 by magnetron sputtering. The conductive film was a CrNH film.

The conditions for forming the conductive film are as follows:
Target; Cr target Vacuum degree: 1 × 10 ⁻⁴ Pa or less Sputtering gas: Mixed gas of Ar, N ₂ and H ₂ (Ar: 58.2 vol%, N ₂ : 40 vol%, H ₂ : 1.8 vol%)
Gas pressure: 0.1 Pa
Input power: 1500W
Deposition rate: 0.18 nm / sec
The target film thickness of the conductive film was 185 nm.

(Formation of reflective film)
Next, a reflective film was formed on the second main surface of Sample 1-1 by ion beam sputtering.

  The reflective film was a Mo / Si multilayer reflective film. More specifically, the Mo / Si multilayer reflective film with a thickness of 340 nm is formed by alternately repeating the film formation of the Mo layer with a target thickness of 2.3 nm and the film formation of the Si layer with a target thickness of 4.5 nm. Formed.

The conditions for forming the Mo layer are as follows:
Target; Mo target
Sputtering gas; Ar gas (gas pressure: 0.02 Pa)
Voltage: 700V
Deposition rate: 0.064 nm / sec
On the other hand, the deposition conditions for the Si layer are as follows:
Target; Si target (boron doped)
Sputtering gas; Ar gas (gas pressure: 0.02 Pa)
Voltage: 700V
Deposition rate: 0.077 nm / sec.

(Formation of protective film)
Next, a protective film was formed on the reflective film using an ion beam sputtering method. The protective film was a Ru layer.

The conditions for forming the protective film are as follows:
Target; Ru target
Sputtering gas; Ar gas (gas pressure: 0.02 Pa)
Voltage: 700V
Deposition rate: 0.052 nm / sec
The target thickness of the protective film was 2.5 nm.

(Formation of absorption film)
Next, an absorption film was formed on the protective film by using a magnetron sputtering method. The absorption film was a TaN layer.

The conditions for forming the absorption film are as follows:
Target; Ta target sputtering gas; mixed gas of Ar and _{N 2 (Ar: 86vol%,} N 2: 14vol%)
Gas pressure; 0.3Pa
Input power: 150W
Deposition rate: 7.2 nm / min
The target thickness of the absorption film was 60 nm.

(Formation of low reflection film)
Next, a low reflection film was formed on the absorption film by using a magnetron sputtering method. The low reflection film was a TaON layer.

The conditions for forming the low reflection film are as follows:
Target; Ta target Sputtering gas; Mixed gas of Ar, O ₂ and N ₂ (Ar: 49 vol%, O ₂ : 37 vol%, N ₂ : 14 vol%)
Gas pressure; 0.3Pa
Input power: 250W
Deposition rate: 2.0 nm / min
The thickness of the low reflection film was targeted at 8 nm.

  Through the above steps, a mask blank including Sample 1-1 (hereinafter referred to as “mask blank 11”) was manufactured.

  A difference between the maximum height and the minimum height of the mask blank 11 was measured using a flatness measuring machine manufactured by Fujinon.

(Example 12 to Example 17)
Mask blank 12 to mask blank 17 were produced using Sample 1-2 to Sample 1-7, respectively, in the same manner as in Example 11.

(Example 21 to Example 24)
Mask blank 21 to mask blank 24 were produced using Sample 2-1 to Sample 2-4 by the same method as in Example 11, respectively.

(Example 31 to Example 32)
Mask blank 31 to mask blank 32 were produced using Sample 3-1 to Sample 3-2 by the same method as in Example 11, respectively.

(Evaluation)
Evaluation similar to the evaluation performed with respect to each sample was performed using each mask blank.

  Table 2 below summarizes the evaluation results obtained for each mask blank.

表２に示すように、マスクブランク１１〜マスクブランク１７では、いずれも内部領域の平坦度Ｆ_ｉｎ１が２００ｎｍ以下となっていることがわかる。これに対して、サンプル３１およびサンプル３２では、内部領域の平坦度Ｆ_ｉｎ１が２００ｎｍを超えていることがわかる。

As shown in Table 2, in the mask blank 11 to the mask blank 17, it can be seen that the flatness _{Fin1 of the} inner region is 200 nm or less. On the other hand, in sample 31 and sample 32, it can be seen that the flatness _Fin1 of the inner region exceeds 200 nm.

  Further, it can be seen that in the mask blank 11 to the mask blank 17, the maximum height difference ΔD is 150 nm or less. On the other hand, in the mask blank 21 to the mask blank 24, it can be seen that the maximum height difference ΔD exceeds 150 nm.

  Further, in the mask blank 11 to the mask blank 17, the flatness at the time of chucking is 30 nm or less, whereas in the mask blank 21 to the mask blank 24 and the mask blank 31 to the mask blank 32, at the time of chucking It was found that the flatness of the film exceeded 50.

  FIG. 8 is a graph plotting the relationship between the maximum height difference ΔD obtained in each mask blank and the flatness at the time of chucking.

  From FIG. 8, it can be seen that in the mask blank 21 to mask blank 24 and the mask blank 31 to mask blank 32, the flatness at the time of chucking exceeds 50 nm, and a very good flatness is not obtained. On the other hand, in the mask blank 11 to the mask blank 17, the flatness at the time of chucking is 50 nm or less, particularly 30 nm or less, and it can be seen that good results are obtained.

  As described above, it was confirmed that the deformation at the time of chucking was significantly suppressed by manufacturing the mask blank so as to satisfy the characteristics of (iii) and (iv) described above.

DESCRIPTION OF SYMBOLS 10 Reflective mask blank 12 1st main surface 14 2nd main surface 20 Transmission type mask blank 22 1st main surface 24 2nd main surface 100 Mask blank substrate 102 1st main surface 104 2nd main Surface 110 Outline 120 Standard area 130 Frame area 140 Internal area 142 First side (first inner side)
143 First outer side 144 Second side (second inner side)
145 Second outer side 146 Third side (third inner side)
147 Third outer side 148 Fourth side (fourth inner side)
149 Fourth outer side 161 First corner region 162 Second corner region 163 Third corner region 164 Fourth corner region 171 First central region 172 Second central region 173 Third central region 174 Second 4 Central region 200 Substrate 202 First main surface 204 Second main surface 250 First layer 280 Second layer 282 Reflective film 284 Protective film 286 Absorbing film 300 Substrate 302 First main surface 304 Second main surface Surface 380 First layer 402 First main surface 420 Standard region 430 Frame region 440 Internal region 411-415 Contour line 511-515 Contour line 611-617 Contour line

Claims (10)

A mask blank substrate having first and second main surfaces facing each other,
Wherein the first substantially central portion of the main surface, a side length of present standard region in the shape of a square L _2,
The standard area is composed of a frame-like area corresponding to the outer peripheral part of the standard area, and an inner area surrounded by the frame-like area,
The interior region has a length _{L 3} of a side a square 132 mm,
The frame-like region has an outer frame consisting of four sides that match each square side of the standard region, and an inner frame consisting of four sides that match each side of the square of the inner region, and the outer frame Corresponds to the shape of the inner frame expanded such that each side of the inner frame translates outward by 8 mm,
When the vertices of the outer frame of the frame-shaped region are vertices A ₂ , B ₂ , C _2, and D ₂ , respectively, the frame-shaped region has first to first corners. a fourth corner regions, a first corner region comprises a vertex a _2, the second corner region comprises a vertex B _2, third corner region comprises a vertex C _2, the fourth corner region includes vertex D _2, each corner region with a side length of a square-shaped 8 mm,
In the frame-like region, a square first central region having a side length of 8 mm is defined at an intermediate position between the first corner region and the fourth corner region. A second central region having a square length of 8 mm is defined at an intermediate position of the second corner region, and one side is positioned at an intermediate position between the second corner region and the third corner region. A square third central region having a length of 8 mm is partitioned, and a square fourth central region having a side length of 8 mm is provided at an intermediate position between the third corner region and the fourth corner region. Is partitioned,
(I) The flatness F _in1 of the inner region defined based on the least square plane PP ₁ of the standard region is 100 nm or less,
(Ii) One corner area of the frame-shaped area is defined as an nth corner area, and two central areas closest to the nth corner area are defined as a first adjacent central area and a second adjacent central area, respectively. ,
The maximum height of the n-th corner area defined based on the least square plane PP ₁ is H _max (C _n ), the minimum height is H _min (C _n ), and the maximum of the first adjacent central area is The height is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second adjacent central region is H _max (M ₂ ), and the minimum height is H _min (M 1). ₂ )
In any of n = 1 to 4, the following formula (1)

ΔD = Max {H _max (C _n ) −H _min (M ₁ ), H _max (C _n ) −H _min (M ₂ ), H _max (M ₁ ) −H _min (C _n ), H _max (M _{2) -H min (C n)} } (1) formula

The maximum height difference ΔD represented by is 100 nm or less,
_{Here, Max {x 1, x 2} , x 3, x 4} _means the maximum value of x 1 ~x _4, a substrate for a mask blank. 2. The mask blank substrate according to claim 1, wherein the first main surface has a square shape with a side length L ₁ of 152 mm.   The mask blank substrate according to claim 1, wherein the mask blank substrate is a glass substrate. A mask blank having a substrate,
The mask blank has a first main surface and a second main surface;
The second main surface is a main surface on the side where a circuit pattern layer is disposed,
Wherein the first substantially central portion of the main surface, a side length of present standard region in the shape of a square L _2,
The standard area is composed of a frame-like area corresponding to the outer peripheral part of the standard area, and an inner area surrounded by the frame-like area,
The interior region has a length _{L 3} of a side a square 132 mm,
The frame-like region has an outer frame consisting of four sides that match each square side of the standard region, and an inner frame consisting of four sides that match each side of the square of the inner region, and the outer frame Corresponds to the shape of the inner frame expanded such that each side of the inner frame translates outward by 8 mm,
When the vertices of the outer frame of the frame-shaped region are vertices A ₂ , B ₂ , C _2, and D ₂ , respectively, the frame-shaped region has first to first corners. a fourth corner regions, a first corner region comprises a vertex a _2, the second corner region comprises a vertex B _2, third corner region comprises a vertex C _2, the fourth corner region includes vertex D _2, each corner region with a side length of a square-shaped 8 mm,
In the frame-like region, a square first central region having a side length of 8 mm is defined at an intermediate position between the first corner region and the fourth corner region. A second central region having a square length of 8 mm is defined at an intermediate position of the second corner region, and one side is positioned at an intermediate position between the second corner region and the third corner region. A square third central region having a length of 8 mm is partitioned, and a square fourth central region having a side length of 8 mm is provided at an intermediate position between the third corner region and the fourth corner region. Is partitioned,
(Iii) The flatness F _in1 of the inner region determined based on the least square plane PP ₁ of the standard region is 200 nm or less,
(Iv) One corner area of the frame-shaped area is an nth corner area, and two central areas closest to the nth corner area are a first adjacent central area and a second adjacent central area, respectively. ,
The maximum height of the n-th corner area defined based on the least square plane PP ₁ is H _max (C _n ), the minimum height is H _min (C _n ), and the maximum of the first adjacent central area is The height is H _max (M ₁ ), the minimum height is H _min (M ₁ ), the maximum height of the second adjacent central region is H _max (M ₂ ), and the minimum height is H _min (M 1). ₂ )
In any of n = 1 to 4, the following formula (1)

ΔD = Max {H _max (C _n ) −H _min (M ₁ ), H _max (C _n ) −H _min (M ₂ ), H _max (M ₁ ) −H _min (C _n ), H _max (M _{2) -H min (C n)} } (1) formula

The maximum height difference ΔD represented by is 150 nm or less,
_{Here, Max {x 1, x 2} , x 3, x 4} _means the maximum value of x 1 ~x _4, the mask blank. It said first major surface, the length L ₁ of one side is a square 152 mm, the mask blank according to claim 4.   The mask blank according to claim 4 or 5, wherein the substrate is a glass substrate.   The mask blank according to claim 4, wherein the circuit pattern layer includes a light shielding film that shields light.   The circuit pattern layer includes an absorption film that absorbs light, and further includes a reflection film that reflects the light between the absorption film and the substrate. The mask blank described in 1.   The circuit pattern layer is formed in order of the reflection film that reflects light, the absorption film that absorbs the light, and the inspection light of the circuit pattern of the absorption film in the order closer to the second main surface of the glass substrate. The mask blank according to claim 4, further comprising a low-reflection film having lower reflection characteristics than the absorption film.   The mask blank according to claim 8 or 9, comprising a conductive film on the first main surface.

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