JP2526295B2 - How to make an exposure mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] Regarding the method for producing an exposure mask, more specifically,
Regarding the method of making an exposure mask that includes the step of forming a chromium film as a light-shielding film and a chromium oxide film as an antireflection film by sputtering, mix Si particles uniformly in the chromium film or chromium oxide film on the mask substrate. With the aim of providing a method for producing an exposure mask that can reduce the internal stress of these chromium films and chromium oxide films uniformly and improve the accuracy of the mask pattern, a chromium or chromium oxide target is provided. When a piece of material containing silicon is placed on the surface and the chromium or chromium oxide is sputtered, at the same time, the piece of material containing silicon is also sputtered to form a chromium film or a chromium oxide film containing silicon particles on the mask substrate. It is composed including that.

[Industrial applications]

The present invention relates to a method for making an exposure mask, and more particularly to a method for making an exposure mask including a step of forming a chromium film as a light-shielding film and a chromium oxide film as an antireflection film by a sputtering method.

[Conventional technology]

Conventionally, in an exposure mask used in a photo process of a semiconductor device, as shown in FIG. 2, a chromium film 3 serving as a light shielding film and a chromium oxide film 2 serving as an antireflection film are formed on a mask substrate 1 made of quartz. The structure sandwiched between 4 and 4 is used, and these are formed by the sputtering method.

However, when a fine pattern is formed, since strain occurs in the chromium film 3 or the chromium oxide films 2 and 4 due to the difference in strain stress between the chromium film 3 or the chromium oxide films 2 and 4 and the mask substrate 1. There was a problem that a dimensional error of the mask pattern 13 shown in FIG. 3 occurred. Further, due to the reduction of the contact area, there is a problem in the adhesion between the mask substrate and the chromium film 3 or the chromium oxide films 2 and 4.

Therefore, in order to solve these problems, as shown in FIG. 4, by mixing a small amount of Si particles into the chromium film 3 and the chromium oxide films 2 and 4 by the ion implantation method, the force acting between the chromium crystal particles is increased. By adjusting the strain stress by changing it, the adhesion is also improved.

[Problems to be Solved by the Invention]

By the way, as the size of the mask substrate 1 becomes larger as the diameter of the wafer becomes larger, the chromium film 3 and the chromium oxide film are formed.
When a small amount of silicon particles are mixed in 2, 4 by the ion implantation method, variations in the amount of silicon implantation in the chromium film 3 and the chromium oxide films 2, 4 due to uneven distribution of the ion current between the periphery and the center. There is a problem that it becomes large and the strain stress cannot be adjusted uniformly.

Therefore, the present invention has been made in view of such conventional problems, in which the Si particles are uniformly mixed in the chromium film or the chromium oxide film on the mask substrate to form the chromium film or the chromium oxide film. It is an object of the present invention to provide a method for producing an exposure mask that can uniformly reduce internal stress and improve the accuracy of a mask pattern.

[Means for solving the problem]

The problem is that when a material piece containing silicon is placed on the target surface of chromium or chromium oxide and the chromium or chromium oxide is sputtered, the material piece containing silicon is also sputtered simultaneously, and silicon particles are contained on the mask substrate. This is achieved by a method for producing an exposure mask, which comprises forming a chromium film or a chromium oxide film.

[Action]

In the method for manufacturing a semiconductor device of the present invention, when a chromium film as a light-shielding film or a chromium oxide film as an antireflection film is formed on a mask substrate by a sputtering method, a material piece containing silicon is also sputtered at the same time as silicon particles. Is mixed in the chromium film or the chromium oxide film, silicon particles are mixed in the chromium film or the chromium oxide film at a relatively uniform concentration.

As a result, the force acting between the crystal grains of the formed chromium film or chromium oxide film can be uniformly adjusted by interposing the silicon particles, so that the internal stress of these films can be uniformly adjusted. . Therefore, the strain stress between these films and the mask substrate can be uniformly reduced.

Further, since the amount of silicon particles mixed into the chromium film or the chromium oxide film can be adjusted simply by adjusting the amount of the material piece containing silicon, the strain stress of the chromium film or the chromium oxide film can be easily adjusted. be able to. Further, since a special device and an ion implantation process as in the case of the conventional ion implantation method are not required, the mask can be produced at low cost.

〔Example〕

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view for explaining a method of forming an exposure mask according to the embodiment of the present invention, showing a state in which the mask 9a is being formed inside the depressurization processing chamber of the sputtering apparatus.

In the figure, 5 is a mask substrate made of quartz glass,
6 is a chromium oxide film having a thickness of about 300Å as an antireflection film in which Si particles already mixed on the mask substrate 5 are mixed,
7 is a chromium film as a light-shielding film which is being formed on the chromium oxide film 6, 11 is a target of chromium, 10 is a quartz glass plate (SiO ₂ plate) placed on the target 11, and the total surface area of the target 11 is The amount is adjusted to occupy a surface area of about 1/7 to 1/6. Further, 12 is a power supply for fixing the target 11 to a negative potential.

Next, a case of forming the chromium film 6 in which Si particles are mixed on the chromium oxide film 6 will be described.

First, an appropriate amount of quartz glass plate 10 is placed on a chromium target 11, and the mask substrate 5 is placed with the chromium oxide film 6 formed on the mask substrate 5 facing the target 11.

Then, flow the argon (Ar) gas into the decompression chamber at a flow rate of 60.
Introduce it under the condition of cc / min and adjust the pressure in the room to 5 mTorr. Then, from the power supply 12 to the target 11, −450V
Voltage is applied to ionize the Ar gas, and a current of 4.5 amperes is caused to flow between the electrode (not shown) connected to the mask substrate 5 and the target 11.

Then, the target 11 and the quartz glass piece 10 are sputtered by the collision of Ar ions, the chromium particles and the Si particles fly toward the chromium oxide film 6 on the mask substrate 5, and the Si particles are mixed in an appropriate ratio. The chromium film 7 thus deposited is deposited on the chromium oxide film 6. At this time, simultaneously with the deposition of the chromium film 7.
Since the Si particles are mixed into the chromium film 7, the chromium film 7 containing the Si particles having a relatively uniform concentration is formed.

After the chromium film 7 having a thickness of about 600 to 700Å is thus deposited, the chromium target is replaced with a chromium oxide target. Then, by depositing a chromium oxide film (not shown) on the chromium film 7 in the same manner as when the chromium film 7 is formed, as shown in FIG. Deposition of 7,8 is completed.

Then, as shown in FIG. 3, these films 6, 7 and 8 are patterned to complete the preparation of the exposure mask.

Next, by comparing the internal stress of each of the chromium film containing Si directly formed on the glass substrate and the chromium film not containing Si directly formed on the glass substrate by the same method as described above, The latter is 1 × 10 ⁹ N / m ^2, whereas the former is 1 × 10 ⁸ N / m ^{2, which} is an order of magnitude smaller. This reduction in stress improves the accuracy of the mask pattern by about 5 μm in terms of positional deviation, and the effect of improving the mask accuracy by mixing Si particles is great. The internal stress was determined by measuring the amount of warpage of the film by a photobalance method and further calculating it.

Further, when comparing the in-plane distribution of the internal stress between the chromium film containing Si produced by the conventional ion implantation method and the method of the embodiment of the present invention, the variation is considerably smaller in the embodiment of the present invention. , It was confirmed that the accuracy of the mask was significantly improved.

As described above, according to the embodiment of the present invention, Si particles are mixed into the chromium film 7 at the same time as the deposition of the chromium film 7 and the chromium oxide films 6 and 8 shown in FIG. Even if the
The chromium film 7 and the chromium oxide films 6 and 8 containing Si particles are formed. As a result, the chromium film 7 and the chromium oxide film to be created
Since the force acting between the crystal grains of 6, 8 can be adjusted uniformly by interposing Si particles, the internal stress of these films 6, 7, 8 can be adjusted uniformly.

Therefore, the in-plane distribution of the internal stress of the chromium film 7 and the chromium oxides 6, 8 becomes uniform, and the strain stress with the mask substrate 5 can be reduced uniformly. As a result, the displacement of the mask pattern 14 shown in the third vinegar from the normal position can be improved, so that the mask can be created with high accuracy.

Further, in order to adjust the amount of Si particles mixed into the chromium film 7 and the chromium oxide films 6 and 8, it is only necessary to adjust the amount of the material piece containing Si. Therefore, the chromium film 7 and the chromium oxide films 6 and 8 can be adjusted. The strain stress of can be easily adjusted. Furthermore, since no special device or ion implantation process is required unlike in the case of the conventional ion implantation method, the exposure mask 9a can be produced at low cost.

Although the quartz glass plate 10 is used as the material piece containing Si in the examples of the present invention, a Si ₃ N ₄ plate, a Si plate or the like may be used.

〔The invention's effect〕

As described above, according to the method for manufacturing a semiconductor device of the present invention, the chromium film or the chromium oxide film and the material piece containing silicon are simultaneously sputtered by the sputtering method. The particles are mixed into the chromium film and the chromium oxide film. Therefore, even when the mask size is increased, a chromium film containing silicon particles having a relatively uniform concentration is formed. Therefore, the in-plane distribution of the internal stress of the chromium film or the chromium oxide film becomes uniform, and the strain stress with the mask substrate can be uniformly reduced. As a result, the displacement of the mask pattern from the normal position can be improved, and the mask can be created with high accuracy.

Further, in order to adjust the amount of silicon particles mixed into the chromium film or the chromium oxide film, it is only necessary to adjust the amount of the material piece containing silicon, so that the strain stress of the chromium film or the chromium oxide film can be easily adjusted. be able to. Further, since a special device and an ion implantation process, which are used in the conventional ion implantation method, are not required, an exposure mask can be produced at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a method for producing an exposure mask according to an embodiment of the present invention, FIG. 2 is a sectional view of an exposure mask before pattern formation, and FIG. 3 is a sectional view of an exposure mask. FIG. 4 is a cross-sectional view illustrating a method of forming a conventional exposure mask. [Explanation of reference numerals] 1,5 ... Mask substrate, 2,4,6,8 ... Chromium oxide film, 3,7 ... Chrome film, 9,9a ... Exposure mask, 10 ... Quartz glass plate (SiO 2
₂ plates), 11 ... Target, 12 ... Power supply, 13, 14 ... Mask pattern.

Claims (1)

(57) [Claims] 1. When a piece of material containing silicon is placed on a target surface of chromium or chromium oxide and the chromium or chromium oxide is sputtered, at the same time, the piece of material containing silicon is also sputtered to deposit silicon particles on a mask substrate. A method for producing an exposure mask, which comprises forming a chromium film or a chromium oxide film to be contained.