JPS6344824Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pellicle structure that eliminates the occurrence of defects when attached to a reticle.

In order to process large amounts of information at high speed, information processing devices are becoming more and more advanced and smaller, and along with this, the parts used are also becoming smaller, and this trend is particularly noticeable in semiconductor devices such as ICs and LSIs.

Here, electronic circuits such as minute unit elements and conductor patterns connecting them are often formed using thin film formation technology and photolithography.

For example, in the case of semiconductor devices, this photo-etching technology uses a spin coating method etc. on a semiconductor substrate to be processed.
A thin layer of resist is coated, and the electronic circuit pattern drawn on the chrome (Cr) mask is projected onto the resist film by irradiating it with ultraviolet rays through a pre-formed photomask. part becomes insoluble in the developer,
On the other hand, when using a positive resist, a resist film pattern is created by utilizing the soluble phenomenon, and chemical etching or dry etching is performed using this resist as a mask to remove a semiconductor substrate or a metal film formed thereon. Fine patterns are created by etching.

Here, the Cr mask pattern used for projection exposure is called a reticle, and the cover body provided across the reticle for dust prevention is called a pellicle.

In other words, the reticle is approximately 3mm thick and 5mm in size.
A thin Cr film with an anti-reflection film of chromium oxide (Cr ₂ O ₃ ) is formed on an inch square or 6 inch square transparent quartz plate using a vapor deposition method, and then a Cr mask that becomes the original image is created using photo-etching technology. It is formed by
A fine pattern is created by reducing the size of this to 1/5 or 1/10 and exposing it on the substrate to be processed.

Here, the reticle is attached to a projection exposure machine called a stepper, and the same pattern is continuously created by moving the substrate to be processed one pitch at a time for reduction exposure, and in this case, the reticle If there is dust on the surface, this dust will also be projected and exposed, resulting in a defective product.

Therefore, a cover body with a transparent pellicle film on the front and back surfaces of the reticle is provided to sandwich the reticle, thereby reducing the influence of dust.

In other words, by converging the projected light from the light source using a lens and focusing it on the reticle surface, even if there is dust on the pellicle film, the focus will shift and the reticle will become out of focus. It is constructed so as not to adversely affect exposure.

Pellicles are attached to both sides of the reticle for this purpose, but dust may enter the reticle during the attachment process and adhere to the reticle, or it may not be detected by visual inspection of the reticle but may be detected by inspection after the pellicle is attached. In such cases, the pellicle needs to be replaced.

However, since pellicles are expensive, there is a need for a pellicle attachment method that does not require relining.

[Conventional technology]

FIG. 2 is a cross-sectional view showing the state of the pellicle 2 attached to the front and back surfaces of the reticle 1.

That is, a pellicle film 5 made of nitrocellulose is provided on both sides of a reticle 1 made of quartz having a mask pattern 3 made of Cr on its lower surface, and a pellicle film 5 made of nitrocellulose is provided on the upper side of a frame 4 made of aluminum (Al) alloy. There is an adhesive layer 6, which prevents dust from adhering to the front and back surfaces of the mask pattern 3 by adhering it to the substrate of the reticle 1 from both sides.

However, as mentioned above, if the presence of dust is detected during the mask inspection using a laser beam after attaching the pellicle, and the reticle 1 becomes defective, it is necessary to peel off the pellicle 2 and reapply it, which saves man-hours. In addition, the pellicle 5 is expensive and cannot be reused, so an improvement is necessary.

[Problem that the invention attempts to solve]

As explained above, if dust is detected after attaching the pellicle, remove the pellicle, blow out a cleaning gas such as nitrogen (N ₂ ) gas from the nozzle onto the surface of the reticle, clean it, and then reinstall the reticle with a new one. It is necessary to attach a pellicle, and the problem is that conventional pellicles cannot be reused in this case.

[Means for solving problems]

The above problem occurs when the upper pellicle is composed of a lower pellicle with an adhesive layer on the lower surface that adheres to the reticle, and an upper pellicle with a pellicle film on the upper surface and whose lower surface is detachable from the upper surface of the lower pellicle. and a rubber layer provided on the lower surface of the upper pellicle, an insertion pin fixed to one pellicle and protruding through the rubber layer, and an insertion pin formed through the rubber layer at a corresponding position of the other pellicle. This problem can be solved by using a removable pellicle that fits into the hole and has the rubber layers in close contact with each other.

[Effect]

The pellicle according to the present invention is composed of a single layer of an Al alloy frame, whereas the conventional pellicle is composed of a single layer of an Al alloy frame.
The two-layer structure of the upper pellicle and lower pellicle allows both to be attached and detached, making it possible to reuse the pellicle membrane, and the provision of a rubber layer makes it easy to attach and detach both. It is possible to ensure close contact and avoid contamination of foreign substances.

〔Example〕

FIG. 1 is an embodiment showing the structure of the present invention, FIG. 1B is a plan view of the lower pellicle, and FIG. 1A is a sectional view of the upper pellicle and the lower pellicle taken along line X-X'.

In other words, in this embodiment, an 8 cm square pellicle is mounted on a 5 inch square reticle 7, but this pellicle is formed separately into an upper pellicle 8 and a lower pellicle 9, both of which are connected to the lower pellicle. The structure is such that they are connected to each other by an insertion pin 10 having a spring mechanism on the upper surface of the two parts 9 and are integrated.

That is, the lower pellicle 9 is provided with insertion pins 10 having a diameter of 2 mm and a height of 3 mm at the four corners of the frame and at the middle of each side, while the insertion pins 10 are fitted into the corresponding lower surface of the upper pellicle 8. Matching insertion hole 1
1 is provided.

Here, an adhesive layer 12 is provided on the lower surface of the lower pellicle 9, and a rubber layer 13 with a thickness of about 0.5 mm is provided on the upper surface where the insertion pin 10 is provided.

Also, the thickness of the lower surface of the upper pellicle 8 is approximately 0.5 mm.
A rubber layer 14 is provided so that after the insertion pin 10 is fitted, the two come into close contact with each other to prevent dust from entering.

Further, a pellicle film 5 is placed on the upper surface of the upper pellicle 8 as in the conventional case.

In this example, the height of the lower pellicle 9 is 3 mm, the height of the upper pellicle 8 is 5 mm, or
The thickness of the pellicle frame made of Al alloy is 6 mm.

The method for attaching the pellicle is to attach the lower pellicle 9 using an adhesive layer 12 centering on the mask pattern 3 of the reticle 7, which has been freed from dust by spraying with N ₂ gas, and then position the upper pellicle to this. Insert and mate.

If dust is detected during automatic inspection of the mask pattern 3 using laser light, remove the upper pellicle 8, clean it by blowing a cleaning gas such as N ₂ , and then fit the upper pellicle 8 again. That's fine.

Unlike conventional pellicles, the pellicle of the present invention has a two-layer structure, so even if dust is present inside, it can be used continuously after cleaning.

[Effect of idea]

As described above, by using the pellicle according to the present invention, it is possible to eliminate pellicle attachment defects,
This makes it possible to improve the yield from about 90% to 100%.

[Brief explanation of the drawing]

Figure 1 shows the state in which the pellicle according to the present invention is attached to a reticle, Figure B is a plan view of the lower pellicle, Figure A is a sectional view of the upper and lower pellicles at the X-X' position, FIG. 2 is a cross-sectional view of a conventional pellicle. In the figure, 1 and 7 are reticles, 2 is a pellicle, 3 is a mask pattern, 4 is a frame, 5 is a pellicle film, 6 and 12 are adhesive layers, 8 is an upper pellicle, and 9
1 is a lower pellicle, 10 is an insertion pin, 11 is an insertion hole, and 13 is a rubber layer.

Claims (1)

[Scope of utility model registration request] In a pellicle consisting of a lower pellicle having an adhesive layer on the lower surface that adheres to the reticle, and an upper pellicle having a pellicle film on the upper surface and whose lower surface is detachable from the upper surface of the lower pellicle, the upper surface of the lower pellicle and the upper A rubber layer is provided on the lower surface of the pellicle, and an insertion pin fixed to one pellicle and protruding through the rubber layer is fitted into an insertion hole formed through the rubber layer at a corresponding position of the other pellicle. A removable pellicle characterized in that the rubber layers are in close contact with each other.