JP6953190B2 - Film formation equipment and film formation method - Google Patents

Description

The present invention relates to a film forming apparatus and a film forming method capable of producing low-defect mask blanks by controlling a non-erosion region generated in a target.

In the manufacturing process of a semiconductor device, a fine pattern is formed by a photolithography method. At that time, a photomask is used to form a fine pattern. This photomask is obtained by forming a desired fine pattern on a light-shielding film constituting a photomask blank.

Such a light-shielding film is usually formed by a sputtering method [Patent Document 1]. In the sputtering method, a high DC voltage is applied between the substrate and the target (plate-shaped film forming material: Cr, Ti) while introducing an inert gas (for example, Ar gas) into the film forming chamber (in vacuum). This is a method in which ionized Ar (plasma) is made to collide with a target to form a film of the repelled target substance (also referred to as sputtered particles) on a substrate. In addition to adhering to the substrate, the sputtered particles also adhere to the inner wall of the film forming chamber, the shield located near the target, and the like.

In the sputtering method, a region that is easily sputtered (erosion region) and a region that is difficult to sputter (non-erosion region) are more or less generated on the target surface. In the erosion region, the target surface is sequentially sputtered, resulting in a clean surface. On the other hand, in the non-erosion region, the plasma hardly hits and the target substance does not scatter from the target surface. Therefore, a phenomenon occurs in which sputtered particles scattered from the erosion region are reattached to the target surface in the non-erosion region. The deposits (also called particles) containing the reattached sputter particles are likely to fall off. When the deposits in the non-erosion region reach the substrate for some reason and are incorporated into the thin film during film formation, there is a problem that the number of defects in the thin film increases.

Focusing on the relationship between the above-mentioned deposits (particles) in the non-erosion region and the number of defects (pinholes) in the thin film, it is manufactured using a device having a mechanism for reducing film formation on the non-sputtered region of the target and the shield surface. A method for producing a photomask blank has been proposed [Patent Document 2]. Thereby, the manufacturing method of Patent Document 2 makes it possible to provide a phase shift mask blank or the like in which the number of particles or pinholes having a diameter larger than the diameter substantially equal to the exposure wavelength is reduced as much as possible.

However, in recent years, in addition to the number of particles and pinholes having a diameter larger than the diameter approximately equal to the exposure wavelength, the number of particles and pinholes having a diameter smaller than the exposure wavelength can also be reduced. It was expected to develop a possible film forming apparatus and film forming method.

Japanese Unexamined Patent Publication No. 2015-125353 Japanese Unexamined Patent Publication No. 2003-231965

The present invention has been made in view of the above circumstances, and particles having a diameter smaller than the exposure wavelength (in addition to the number of particles or pinholes having a diameter larger than the diameter substantially equal to the exposure wavelength). It is an object of the present invention to provide a film forming apparatus and a film forming method capable of reducing the number of pinholes and pinholes.

(1) The film forming apparatus of the present invention is a film forming apparatus using a sputtering method for manufacturing a mask blank, and includes a film forming chamber including a vacuum chamber capable of reducing the pressure. A transport means that passes through a predetermined position facing the sputtering surface of the target while holding the backing plate on which the target is placed, the magnetron cathode on which the target and the backing plate are mounted, and the substrate to be processed. And an earth shield arranged so as to maintain a constant separation distance D from the outer peripheral end constituting the sputter surface of the target, and the earth shield locally provides a portion different from the separation distance D. manner to possess, the earth shield, at the site different from the distance D, without local recesses in a direction away from the outer peripheral edge constituting the sputtering surface of the target, the recess in addition to the distance D further comprising a distance d1 in a direction away from the outer peripheral edge, the distance d1 is characterized der Rukoto than 0.5mm or less 0.3 mm.

(2) The film forming apparatus of the present invention is characterized in that, in the above (1) , the outer peripheral end constituting the sputtering surface of the target has an oval shape.

(3) The onset Ming film forming apparatus in the above (1) or (2), portions different from the distance D is the outer peripheral edge constituting the sputtering surface of the target, changes from the straight portion to the corner portion It is characterized in that it is provided in the area to be used.

(4) In the film forming apparatus of the present invention , in any one of the above (1) to (3) , the sputtering surface of the target is arranged upward with respect to the direction of gravity and is exposed by the opening of the conveying means. It is characterized in that a desired film is formed in a predetermined region on the lower surface of the substrate, depending on the target and the process gas.

(5) In the film forming method of the present invention, the film forming apparatus according to any one of (1) to (4) above is used, and a constant separation distance D from the outer peripheral edge constituting the sputtering surface of the target is set. It is characterized in that an earth shield adjusted to locally have a portion different from the separation distance D is used with respect to the earth shield arranged so as to be maintained.

The film forming apparatus according to the present invention includes an earth shield arranged so as to maintain a constant separation distance D from the outer peripheral end constituting the sputtering surface of the target, and a portion where the earth shield is different from the separation distance D is provided. Have locally. It was found that by providing this configuration, the distance between the target and the earth shield can be adjusted, and the non-erosion region generated in the target can be controlled. At that time, it is not necessary to change the target shape or the film forming conditions (sputter power, gas flow rate, film forming pressure, etc.) for each film forming condition.
As a result, according to the above configuration, in addition to the number of particles and pinholes having a diameter larger than the diameter substantially equal to the exposure wavelength, the number of particles and pinholes having a diameter smaller than the exposure wavelength is also increased. It is possible to reduce it.
Therefore, the present invention provides a film forming apparatus for manufacturing a mask blank, which can stably obtain a high-quality fine pattern with little damage when a desired fine pattern is formed on a light-shielding film constituting a photomask blank. Contribute to the offer.

In the film forming method according to the present invention, the above-mentioned film forming apparatus is used, and the separation distance D is relative to an earth shield arranged so as to maintain a constant separation distance D from the outer peripheral end constituting the sputtering surface of the target. Use an earth shield adjusted to have a part different from that locally. Thereby, the separation distance D can be locally changed as needed. Therefore, according to the present invention, it is possible to locally and appropriately adjust the separation distance D only in the non-erosion region where particles are particularly generated, without changing the target shape at all.
Therefore, the present invention stably obtains a high-quality fine pattern with little damage when a desired fine pattern is formed on the light-shielding film constituting the photomask blank without depending on the target shape. It provides a film forming method for blank production.

It is a schematic diagram which shows the film-forming apparatus for manufacturing a mask blank which concerns on this invention, (a) is the sectional view which shows the whole film-forming apparatus, (b) is the enlarged sectional view which shows the vicinity of cathode (region J). It is a schematic view which shows the relationship between the target and the earth seal in the film forming apparatus of FIG. The graph which shows the result of the number of defects and the yield before and after the improvement of Experimental Example 1. The graph which shows the result of the number of defects and the yield before and after the improvement of Experimental Example 2. The graph which shows the result of the number of defects and the yield before and after the improvement of Experimental Example 3. The graph which shows the result of the number of defects and the yield before and after the improvement of Experimental Example 4. The graph which shows the result of the number of defects and the yield before and after the improvement of Experimental Example 5. The schematic diagram which shows the case where the tip part of the earth shield is located in the area inside the outer peripheral edge of a target. The schematic diagram which shows the case where the outer peripheral edge of a target and the tip of the earth shield are at the same position. The schematic diagram which shows the case where the tip part of the earth shield is located in the area outside the outer peripheral edge of a target.

Hereinafter, an embodiment of the film forming apparatus according to the present invention will be described with reference to the drawings.
1A and 1B are schematic views showing a film forming apparatus for manufacturing a mask blank according to the present invention, in which FIG. 1A is a cross-sectional view showing the entire film forming apparatus, and FIG. 1B is an enlarged view showing the vicinity of the cathode (region J). It is a cross-sectional view.

The film forming apparatus 200 of FIG. 1 is a film forming apparatus provided with three film forming chambers capable of forming a Cr-based thin film by using a DC sputtering method. In the film forming apparatus 200 of FIG. 1, each process chamber is connected and arranged in series, and a carrier 101 composed of a substrate S to be processed and a tray T on which the substrate S is mounted passes through each process chamber in order. Thereby, a desired thin film constituting the mask blank according to the present invention is produced on one surface S1 of the substrate S.
In the following description, the Cr-based thin films formed in the first film forming chamber (S1), the second film forming chamber (S2), and the third film forming chamber (S3), which will be described later, are described in order of the first film and the second film. Also called a membrane or a third membrane.

As shown in FIG. 1A, the film forming apparatus 200 includes a charging chamber (L) 251 and a heating chamber (H) 252, a first film forming chamber (S1) 253, a second isolation chamber (EX2) 254, and a first. The two film forming chambers (S2) 255, the third isolation chamber (EX3) 256, the third film forming chamber (S3) 257, the third isolation chamber (EX4) 258, and the take-out chamber (UL) 259 are provided. In the film forming apparatus 200, the carrier 101 composed of the substrate S and the tray T on which the substrate S is mounted can move only in the forward direction (direction of arrow Y) from the charging chamber 251 to the taking-out chamber 259. That is, the reference numeral Y is the direction in which the carrier (board S) moves.

As shown in FIG. 1B, in the film forming apparatus 200, the carrier 101 is a substrate S on which the peripheral edge portion and the side surface portion of the one surface S1 are covered with the tray T and held. As a result, the central portion of one surface S1 of the substrate S is exposed toward the cathode. In this state, the substrate S passes over, for example, the cathode CA31. At that time, a thin film is formed on the exposed central portion of the one surface S1 of the substrate S. The film forming apparatus 200 is a so-called spatter-up type.
In FIGS. 1A and 1B, the arrow X represents the depth direction of the paper surface, the arrow Y represents the direction in which the carrier 101 (that is, the substrate S) passes, and the arrow Z represents the upward direction of the paper surface. There is.

As shown in FIG. 2A, the cathode CA31 is composed of a desired target 10, a backing plate 12 on which the target 10 is placed, and a magnet 14 internally arranged on the backing plate 12. The cathode CA51 and the cathode CA71 also have the same configuration as the cathode CA31.
In FIG. 2A, the “solid line” showing the sputtering surface (surface) of the target 10 represents the state after erosion is generated by sputtering. The "dashed-dotted line" represents the state (flat state) before the occurrence of erosion.
Reference numeral 14 is a magnet. Reference numeral D is a constant separation distance provided between the outer peripheral end 10E forming the sputter surface of the target 10 and the tip portion 16E of the earth shield 16. Reference numeral Y is a transport direction of the carrier 101 on which the substrate S is mounted.

As shown in FIG. 2B, the outer peripheral end 10E constituting the sputter surface of the target 10 has an oval shape. The arm portion 16A of the earth shield 16 is provided so that the tip portion 16E of the earth shield 16 is arranged at a position of a predetermined separation distance D, which is outside the outer peripheral end 10E of the target 10. ..

Hereinafter, in the film forming apparatus 200 described above, the movement of the carrier 101 (that is, the substrate S) moving in each room will be described.
The carrier 101 carried into the charging chamber 251 is moved from the charging chamber 251 to the heating chamber 252 after the desired depressurized atmosphere is obtained, and is heat-treated at the point A by a heating means (not shown). At that time, the atmosphere of the heating chamber 252 in which the carrier 101 on which the substrate S is mounted is housed is adjusted according to the atmospheric conditions when the first film is formed in the next first film forming chamber 253. The heating chamber 252 is provided with a heating means (not shown), and the temperature of the substrate S is adjusted so as to be a temperature preferable for producing the first film.

Next, the temperature-controlled substrate S is moved to the first film forming chamber 253 and passes over the first cathode CA31 from the point B1 to the point B2. At that time, a state in which the first film is formed on one surface S1 side of the substrate S is obtained by the DC sputtering method using the first target TG31 provided in the first cathode CA31.

Next, the carrier 101 on which the substrate S on which the first film is formed is moved to the second isolation chamber 254 and reaches the point C. Then, the atmosphere of the second isolation chamber 254 in which the carrier 101 on which the substrate S is mounted is housed is adjusted according to the atmospheric conditions when the second film is formed in the next second film forming chamber 255. The second isolation chamber 254 may include a heating means (not shown), and the temperature of the substrate S may be adjusted to a temperature preferable for producing the second film.

Next, the substrate S is moved from the second isolation chamber 254 to the second film forming chamber 255, and passes over the second cathode CA51 from the point D1 to the point D2. At that time, a state in which the second film is formed on the first film on the S1 side of one surface of the substrate S is obtained by the DC sputtering method using the second target TG51 provided in the second cathode CA51.

Next, the carrier 101 on which the substrate S on which the second film is formed is moved to the third isolation chamber 256 and reaches the point E. Then, the atmosphere of the third isolation chamber 256 in which the carrier 101 on which the substrate S is mounted is housed is adjusted according to the atmospheric conditions when the third film is formed in the next third film forming chamber 257. The third isolation chamber 256 may include a heating means (not shown), and the temperature of the substrate S may be adjusted to a temperature preferable for producing the third film.

Next, the substrate S is moved from the third isolation chamber 256 to the third film forming chamber 257, and passes over the third cathode CA71 from the point F1 to the point F2. At that time, a state in which the third film is formed on the second film on the S1 side of one surface of the substrate S can be obtained by the DC sputtering method using the third target TG71 provided in the third cathode CA71.

Next, the carrier 101 on which the substrate S on which the third film is formed is moved to the fourth isolation chamber 258 and reaches the point G. Then, the atmosphere of the fourth isolation chamber 256 in which the carrier 101 on which the substrate S is mounted is housed is adjusted according to the atmospheric conditions of the next take-out chamber 259. The fourth isolation chamber 258 is provided with a cooling means (not shown), and the temperature of the substrate S may be adjusted so as to be a preferable temperature when the substrate S is opened to the atmosphere in the take-out chamber 259.

Next, the substrate S is moved from the fourth isolation chamber 258 to the take-out chamber 259 and reaches the point H. After that, by setting the inside of the take-out chamber 259 to atmospheric pressure, the sample in which the first film, the second film, and the third film are laminated in this order on one surface S1 side of the substrate S is carried out to the outside of the film forming apparatus 200. Will be done.

Three isolation chambers (second isolation chamber 254, third isolation chamber 256, and fourth isolation chamber) arranged between the first film formation chamber 253, the second film formation chamber 255, and the third film formation chamber 257, respectively. 258) functions to separate the atmosphere of each film forming chamber and to maintain an independent atmosphere in each film forming chamber. Means having similar functions may be arranged between the rooms. Examples of such means include a partition valve, a door valve, and a differential pressure valve. As a result, the problem that the particles and gas generated in each film forming chamber flow out to each other's internal space and are taken into the film formed in each film forming chamber is solved.

In particular, in the present invention, as shown in FIG. 2B, the earth shield 16 is provided so as to maintain a constant separation distance D from the outer peripheral end 10E constituting the sputter surface of the target 10. The tip portion 16E of the earth shield 16 is configured to locally have a portion 16L1 (or 16L2) different from the separation distance D. The portion 16L1 (or 16L2) different from the separation distance D is oriented so as to move outward from the target 10 when viewed from the outer peripheral end 10E of the target 10. For example, the separation bending at the portion 16L1 is (D + d1), and the separation distance at the portion 16L2 is (D + d2).

As will be described later, by providing the above configuration, the distance between the target and the earth shield can be adjusted, and the non-erosion region generated in the target can be controlled (in particular, the non-erosion region near the outer peripheral end 10E of the target 10). The present inventors have found that it can be controlled so that the occurrence of the above is almost nonexistent. As a result, it was also found that it is not necessary to change the target shape or the film forming conditions (sputter power, gas flow rate, film forming pressure, etc.) for each film forming condition.

Further, as described later, according to the above configuration, in addition to the number of particles and pinholes having a diameter larger than the diameter substantially equal to the exposure wavelength, the number of particles and pinholes having a diameter smaller than the exposure wavelength. It was also found that (the number of defects of 1.0 μm or less) can be reduced. This is because, as a result of making fine adjustments to locally increase the distance of the earth shield 16 from the outer peripheral end 10E of the target 10 to the outside, almost no non-erosion region is generated in the vicinity of the outer peripheral end 10E of the target 10. It is thought that this is the cause.

Therefore, the present invention provides a film forming apparatus for manufacturing a mask blank, which can stably obtain a high-quality fine pattern with little damage when a desired fine pattern is formed on a light-shielding film constituting a photomask blank. It contributes to the provision.
In other words, the present invention can reduce foreign matter generated from the target non-erosion region and is effective for producing chromium low defect blanks. Further, the present invention is excellent in productivity and economy because it is possible to set the film forming conditions in which the film characteristics are prioritized for each of a plurality of film types and it is not necessary to set the target shape for each film type.

Hereinafter, each example in which a Cr-based thin film is formed by changing the film forming conditions will be described.
In each embodiment, common film forming conditions (gas conditions, film forming pressure, substrate transfer) in the three film forming chambers (first film forming chamber 253, second film forming chamber 255, and third film forming chamber 257). The speed) shall be as shown in Table 1 below. The targets used in the three film forming chambers were all pure Cr (purity 5N), and the substrate used was a glass substrate (152.4 mm × 152.4 mm × 6.35 mmt).
In the film forming apparatus shown in FIGS. 1 and 2, the glass substrate moves over the target 10 so as to cross the range of the straight portion SA of the target 10 in the direction of the arrow Y. That is, it does not pass over the corner CA.

(Example 1)
In this example, the second film forming chamber 255 and the third film forming chamber 257 are used, and a Cr nitride film (thickness 30 nm) is used as the first layer and a Cr oxide film (thickness 25 nm) is used as the second layer on the glass substrate. Was formed. At that time, the film forming pressure of the second film forming chamber 255 was 0.23 (Pa), and the film forming pressure of the third film forming chamber 257 was 0.25 (Pa). The substrate temperature at the time of film formation was in the range of 100 to 120 (° C.).

When the separation distance D between the target (T) and the earth shield (ES) is 2.0 (mm), when the distance D is 0.3 (mm) locally outward with respect to this setting [ When (D + d1) = 2.3 mm] and when further separated by 0.3 (mm) [when (D + d1) = 2.6 mm], film formation was performed 88 to 89 times, respectively, and the non-defective rate was determined. The yield and the number of defects in the formed thin film were evaluated.

Table 2 is a list summarizing the results. Each item in Table 2 is shown below.
The “distance between T and ES” is the distance between the target (T) and the earth shield (ES), that is, the separation distance.
In "display", "-" represents the reference distance D, "after improvement" represents (D + d1), and "+" represents (D + 2 × d1).
The “good product” is defined as “particles larger than 0.5 μm and having no pinholes”, and the number of films formed corresponding to this good product is the “number of non-defective products”.
The "yield" is calculated by multiplying (the number of non-defective products / the number of films formed) x 100, and the "relative yield" sets the separation distance D between the target (T) and the earth shield (ES) to 2.0 (mm). ), And the difference between the yield when the separation distance D is changed. In other words, if the difference is "positive", it means that the yield has improved.
The "number of defects" is the result of measuring minute defects (concave defects, convex defects) on the surface of the thin film with a defect inspection device (MAGICS6640 manufactured by Lasertec). The “−0.15” column represents the number of defects having a defect size of less than 0.15 (μm). The “−0.30” column represents the number of defects having a defect size of 0.15 (μm) or more and 0.30 (μm) or less. The “2.00-” column represents the number of defects having a defect size of 2.00 (μm) or more.

FIG. 3 is a graph showing the results of Table 2. FIG. 3A shows the “relative yield”, and FIG. 3B shows the number of defects.

Table 3 below summarizes the non-erosion area ratios of the targets with respect to Table 2. Here, the non-erosion area ratio of the target is defined as "non-erosion area generated on the target surface / target surface area" or "target end face erosion area / target surface area".

From Table 2, Table 3 and FIG. 3, the following points (A1) to (A3) were clarified.
(A1) By locally expanding the distance D between T and ES by 0.3 mm outward, all evaluation items (relative yield: 18.9%, number of defects: 18.6 → 9.7, The non-erosion area ratio of the target: 0.30 → 0.00) was improved.
(A2) By locally expanding the distance D between T and ES to the outside by 0.3 mm, all evaluation items (relative yield: 3.0%, number of defects: 9.7 → 17.6). , Target non-erosion area ratio: 0.00 → -0.26) deteriorated. Here, "-" means an erosion area generated in the end face portion of the target when the erosion portion spreads beyond the surface of the target.
(A3) In particular, after improvement, the number of small defect sizes (-0.15 μm :, −0.30 μm, −0.50 μm) is significantly reduced.
From the above, it was found that the number of defects generated in the film can be suppressed by appropriately providing a local recess in the earth shield. Under the film forming conditions of this example, the local recess d1 = 0.3 mm was an appropriate value with respect to the separation distance D = 2.0 mm.

(Example 2)
In this example, the second film forming chamber 255 and the third film forming chamber 257 are used, and a Cr nitride film (thickness 45 nm) is used as the first layer and a Cr oxide film (thickness 25 nm) is used as the second layer on the glass substrate. Was formed. At that time, the film forming pressure of the second film forming chamber 255 was 0.23 (Pa), and the film forming pressure of the third film forming chamber 257 was 0.25 (Pa). The substrate temperature at the time of film formation was in the range of 100 to 120 (° C.).

When the separation distance D between the target (T) and the earth shield (ES) is 2.0 (mm), when the distance D is 0.3 (mm) locally outward with respect to this setting [ When (D + d1) = 2.3 mm] and when further separated by 0.3 (mm) [when (D + d1) = 2.6 mm], film formation was performed 102 to 149 times, respectively, and the non-defective rate was determined. The yield and the number of defects in the formed thin film were evaluated.

Table 4 is a list summarizing the results. In Table 4, the definitions of “distance between T and ES”, “display”, “number of non-defective products”, “yield”, “relative yield”, and “number of defects” are the same as those in the first embodiment.
FIG. 4 is a graph showing the results of Table 4. FIG. 4A shows the “relative yield”, and FIG. 4B shows the number of defects.

Table 5 below summarizes the non-erosion area ratios of the targets with respect to Table 4. The definition of the non-erosion area ratio of the target is the same as in Example 1.

From Table 4, Table 5 and FIG. 4, the following points (B1) to (B3) were clarified.
(B1) By locally expanding the distance D between T and ES by 0.3 mm outward, all evaluation items (relative yield: 22.0%, number of defects: 10.8 → 6.9, Target non-erosion area ratio: 0.32 → 0.00) improved.
(B2) By locally expanding the distance D between T and ES to the outside by 0.3 mm, all evaluation items (relative yield: -1.5%, number of defects: 6.9 → 11.0). The non-erosion area ratio of the target: 0.00 → -0.26) deteriorated.
(B3) In particular, after improvement, the number of small defect sizes (-0.15 μm :, −0.30 μm, −0.50 μm) is significantly reduced.
From the above, it was found that the number of defects generated in the film can be suppressed by appropriately providing a local recess in the earth shield. Under the film forming conditions of this example, the local recess d1 = 0.3 mm was an appropriate value with respect to the separation distance D = 2.0 mm.

(Example 3)
In this example, the second film forming chamber 255 and the third film forming chamber 257 are used, and a Cr nitride film (thickness 45 nm) is used as the first layer and a Cr oxide film (thickness 25 nm) is used as the second layer on the glass substrate. Was formed. At that time, the film forming pressure of the second film forming chamber 255 was set to 0.25 (Pa), and the film forming pressure of the third film forming chamber 257 was set to 0.25 (Pa). The substrate temperature at the time of film formation was in the range of 100 to 120 (° C.).

When the separation distance D between the target (T) and the earth shield (ES) is 2.0 (mm), when the distance D is 0.4 (mm) locally outward with respect to this setting [ When (D + d1) = 2.4 mm] and when further separated by 0.4 (mm) [when (D + d1) = 2.8 mm], 100 to 150 times of film formation were performed, respectively, and the non-defective rate was determined. The yield and the number of defects in the formed thin film were evaluated.

Table 6 is a list summarizing the results. In Table 6, the definitions of “distance between T and ES”, “display”, “number of non-defective products”, “yield”, “relative yield”, and “number of defects” are the same as those in the first embodiment.
FIG. 5 is a graph showing the results of Table 6. FIG. 5A shows the “relative yield”, and FIG. 5B shows the number of defects.

Table 7 below summarizes the non-erosion area ratios of the targets with respect to Table 6. The definition of the non-erosion area ratio of the target is the same as in Example 1.

From Table 6, Table 7 and FIG. 5, the following points (C1) to (C3) were clarified.
(C1) By locally expanding the distance D between T and ES by 0.4 mm outward, all evaluation items (relative yield: 24.7%, number of defects: 11.0 → 7.5, The non-erosion area ratio of the target: 0.41 → 0.00) was improved.
(C2) By locally expanding the distance D between T and ES to the outside by 0.4 mm, all evaluation items (relative yield: 5.4%, number of defects: 7.5 → 10.6). , Target non-erosion area ratio: 0.00 → -0.42) deteriorated.
(C3) In particular, after improvement, the number of small defect sizes (-0.15 μm :, −0.30 μm, −0.50 μm) is significantly reduced.
From the above, it was found that the number of defects generated in the film can be suppressed by appropriately providing a local recess in the earth shield. Under the film forming conditions of this example, the local recess d1 = 0.4 mm was an appropriate value with respect to the separation distance D = 2.0 mm.

(Example 4)
In this example, the second film forming chamber 255 and the third film forming chamber 257 are used, and a Cr nitride film (thickness 45 nm) is used as the first layer and a Cr oxide film (thickness 25 nm) is used as the second layer on the glass substrate. Was formed. At that time, the film forming pressure of the second film forming chamber 255 was 0.26 (Pa), and the film forming pressure of the third film forming chamber 257 was 0.25 (Pa). The substrate temperature at the time of film formation was in the range of 100 to 120 (° C.).

When the separation distance D between the target (T) and the earth shield (ES) is 2.0 (mm), when the distance D is 0.5 (mm) locally outward with respect to this setting [ When (D + d1) = 2.5 mm] and when further separated by 0.5 (mm) [when (D + d1) = 3.0 mm], film formation was performed 81 to 85 times, respectively, and the non-defective rate was determined. The yield and the number of defects in the formed thin film were evaluated.

Table 8 is a list summarizing the results. In Table 8, the definitions of “distance between T and ES”, “display”, “number of non-defective products”, “yield”, “relative yield”, and “number of defects” are the same as those in the first embodiment.
FIG. 6 is a graph showing the results of Table 8. FIG. 6A shows the “relative yield”, and FIG. 6B shows the number of defects.

Table 9 below summarizes the non-erosion area ratios of the targets with respect to Table 8. The definition of the non-erosion area ratio of the target is the same as in Example 1.

From Table 8, Table 9 and FIG. 6, the following points (D1) to (D3) became clear.
(D1) By locally expanding the distance D between T and ES by 0.5 mm outward, all evaluation items (relative yield: 30.1%, number of defects: 18.1 → 9.4, The non-erosion area ratio of the target: 0.48 → 0.00) was improved.
(D2) By locally expanding the distance D between T and ES to the outside by 0.5 mm, all evaluation items (relative yield: 7.6%, number of defects: 9.4 → 13.9). , Target non-erosion area ratio: 0.00 → -0.48) deteriorated.
(D3) In particular, after improvement, the number of small defect sizes (-0.15 μm :, −0.30 μm, −0.50 μm) is significantly reduced.
From the above, it was found that the number of defects generated in the film can be suppressed by appropriately providing a local recess in the earth shield. Under the film forming conditions of this example, the local recess d1 = 0.5 mm was an appropriate value with respect to the separation distance D = 2.0 mm.

(Example 5)
In this example, the first film forming chamber 253, the second film forming chamber 255, and the third film forming chamber 257 are used, and a Cr nitride film (thickness 25 nm) is used as the first layer on the glass substrate and nitrided as the second layer. A Cr oxide film (thickness 25 nm) was formed by using the Cr film (thickness 50 nm) as the third layer. At that time, the film forming pressure of the first film forming chamber 253 is 0.23 (Pa), the film forming pressure of the second film forming chamber 255 is 0.26 (Pa), and the film forming pressure of the third film forming chamber 257 is 0.23 (Pa). It was set to 0.25 (Pa). The substrate temperature at the time of film formation was in the range of 100 to 120 (° C.).

When the separation distance D between the target (T) and the earth shield (ES) is 2.0 (mm), when the distance D is 0.5 (mm) locally outward with respect to this setting [ When (D + d1) = 2.5 mm] and when further separated by 0.5 (mm) [when (D + d1) = 3.0 mm], 100 to 168 film formations were performed, respectively, and the non-defective rate was determined. The yield and the number of defects in the formed thin film were evaluated.

Table 10 is a list summarizing the results. In Table 10, the definitions of “distance between T and ES”, “display”, “number of non-defective products”, “yield”, “relative yield”, and “number of defects” are the same as those in the first embodiment.
FIG. 7 is a graph showing the results of Table 10. FIG. 7 (a) shows the “relative yield”, and FIG. 7 (b) shows the number of defects.

Table 11 below summarizes the non-erosion area ratios of the targets with respect to Table 10. The definition of the non-erosion area ratio of the target is the same as in Example 1.

From Table 10, Table 11 and FIG. 7, the following points (E1) to (E3) were clarified.
(E1) By locally expanding the distance D between T and ES by 0.5 mm outward, all evaluation items (relative yield: 17.7%, number of defects: 13.9 → 7.6, The non-erosion area ratio of the target: 0.48 → 0.00) was improved.
(E2) By locally expanding the distance D between T and ES to the outside by 0.5 mm, all evaluation items (relative yield: 7.0%, number of defects: 7.6 → 12.5) , Target non-erosion area ratio: 0.00 → -0.41) deteriorated.
(E3) In particular, after improvement, the number of occurrences of the two defect sizes (-0.15 μm: -0.50 μm) is significantly reduced, while the number of occurrences of the intermediate defect size (-0.30 μm) is significantly reduced. increased.
From the above, it was found that the number of defects generated in the film can be suppressed by appropriately providing a local recess in the earth shield. Under the film forming conditions of this example, the local recess d1 = 0.5 mm is an appropriate value with respect to the separation distance D = 2.0 mm. However, under the film forming conditions of this example, the number of intermediate defect sizes (-0.30 μm) generated increased, and it was found that there is still room for improvement.

According to the above-mentioned results (Examples 1 to 5), according to the film forming apparatus and the film forming method according to the present invention, in addition to the number of particles and pinholes having a diameter larger than the diameter substantially equal to the exposure wavelength. It was also confirmed that the number of particles and pinholes with a diameter smaller than the exposure wavelength can be reduced.

In the above-mentioned examples, an example applied to the production of a mask blank having a Cr-based thin film has been described, but the present invention is not limited to the Cr-based thin film. For example, the present invention is also effective for Ta-based thin films and Ti-based thin films.

Further, in the above-described embodiment, the configuration in which the recess 16L1 is provided at the end portion 16E of the earth shield located at the position facing the straight portion SA of the target has been described in detail, but the present invention is not limited thereto. For example, as shown in FIG. 2B, the present invention is also applicable to a configuration in which a recess 16L2 is provided at the end 16E of the earth shield located at a position facing the corner CA of the target.

Further, the film forming apparatus of the present invention discloses a sputter-up type (a type in which a target is arranged below in the direction of gravity and a substrate is stationary or passes above the target), but the present invention is limited thereto. It is not something that is done. For example, the spatter-down type (a type in which the target is placed above in the direction of gravity and the substrate passes below it at rest) or the side sputter type (a type in which the target is placed parallel to the direction of gravity and the target is placed with this target). The present invention is also applicable to a type in which the substrates stand still or pass so as to face each other).

The present invention is widely applicable to a film forming apparatus and a film forming method for producing a mask blank. Such a film forming apparatus and a film forming method can reduce foreign matters generated from a target non-erosion region, and are effective for producing chromium low defect blanks. Further, in the present invention, it is possible to set the film forming conditions in which the film characteristics are prioritized for each of a plurality of film types, and since it is not necessary to set the target shape for each film type, it is excellent in productivity and economy. Contributes to low cost.

Corner part of CA target, CA31, CA51, CA71 cathode, separation distance between the outer peripheral edge constituting the sputter surface of D target and the earth shield, S board, straight part of SA target, one side of S1 board, other side of S2 board , T tray, Y carrier (board S) movement direction, 10 target, 10E target outer peripheral edge, 12 backing plate, 14 magnetron cathode (magnet), 16 earth shield, 16A earth shield arm, 16E earth shield tip Part, 16L1, 16L2 The part where the tip of the earth shield is different from the separation distance D, 101 carrier (conveying means), 200 film forming equipment, 251 charging room, 252 heating room, 253 first film forming room, 254 second isolation room , 255 Second film formation room, 256 Third isolation room, 257 Third film formation room, 258 Third isolation room, 259 Extraction room.

Claims (5)

This is a film forming apparatus using a sputtering method for manufacturing mask blanks.
Includes a film formation chamber consisting of a vacuum chamber capable of depressurizing
The film forming chamber faces the sputtered surface of the target while holding the target, the backing plate on which the target is placed, the magnetron cathode on which the target and the backing plate are mounted, and the substrate to be processed. It is provided with at least a transport means that passes through the predetermined position and an earth shield that is arranged so as to maintain a constant separation distance D from the outer peripheral end constituting the sputter surface of the target.
The earth shield, a portion different from the distance D, locally perforated,
The earth shield forms a local recess in a portion different from the separation distance D in a direction away from the outer peripheral end constituting the sputter surface of the target.
The recess has a distance d1 in a direction further away from the outer peripheral end in addition to the separation distance D.
The distance d1 is the film forming apparatus according to claim der Rukoto than 0.5mm or less 0.3 mm. The film forming apparatus according to claim 1, wherein the outer peripheral end constituting the sputtered surface of the target has an oval shape. The film forming apparatus according to claim 1 or 2 , wherein a portion different from the separation distance D is provided in a region where the outer peripheral end constituting the sputtering surface of the target changes from a straight portion to a corner portion. The sputtered surface of the target is arranged upward with respect to the direction of gravity.
The invention according to any one of claims 1 to 3, wherein a desired film is formed on a predetermined region on the lower surface of the substrate exposed by the opening of the transport means according to the target and the process gas. The film forming apparatus according to the above. Using the film forming apparatus according to any one of claims 1 to 4, the distance from the earth shield arranged so as to maintain a constant distance D from the outer peripheral end constituting the sputter surface of the target. A film forming method for manufacturing a mask blank, which comprises using an earth shield adjusted so as to locally have a portion different from the distance D.

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