JPH0613356A - Method of forming thin film pattern - Google Patents

Abstract

PURPOSE:To make fine a thin film pattern, and shorten and simplify a process by securely performing patterning without use of a wet process. CONSTITUTION:A stencil 2 is patterned on the surface 1S of a substrate 1, and thereafter a thin film 3 to be formed is deposited on the stencil 2. Further, the stencil 2 is irradiated with an energy beam from the back surface 1R side of the substrate 1 as indicated by an arrow L to be exfoliated for patterning of the thin film 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film pattern forming method used in a manufacturing process of various semiconductor devices and the like.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, A
A so-called lift-off method is used as a method of avoiding damage due to the deposition of the film forming material on a region other than the pattern formation region when patterning the l wiring or the like.

This lift-off method will be described with reference to FIGS. 6A to 6C showing an example of the manufacturing process. First, as shown in FIG. 6A, a resist 31 having a required pattern, that is, a stencil is provided on the upper surface side. Then, it is formed on the substrate 1 in a so-called undercut shape so as to have a narrow pattern on the base side, and as shown in FIG. 6B, it is formed of metal, a conductive material, an insulating material, or the like. The thin film 32 is formed on the entire surface by sputtering or the like.
Then, by dissolving the resist 31 with a solvent and removing it, as shown in FIG. 6C, the thin film 32 waiting on the resist 31 is also removed at the same time, and the thin film 32 having a predetermined pattern is formed on the substrate 1. To form.

However, as described above, in such a lift-off method, when depositing the thin film 33 to be formed as shown in FIG. 6B by sputtering or the like, the thin film material adhered to the side wall of the resist 31. Since 34 remains, it is difficult to melt and remove the resist 31, or as shown in FIG. 6C, there is a problem that the deposit 34 remains in an unnecessary area other than the area where the thin film pattern is to be formed. is there.

In order to solve such a problem, a method of applying ultrasonic waves of about 80 kHz to 200 kHz at the time of stencil peeling (Japanese Patent Publication No. 1-19256) has been proposed. When a sound wave is applied, there is a risk of damaging the thin film to be formed in a desired pattern, the underlying film underlying this, or the substrate. Further, such a conventional technique has a disadvantage that it is difficult to sufficiently obtain the effect when the resist is not undercut.

[0006]

The applicant of the present invention, in the Japanese Patent Application No. 3-100805 filed previously, applied heat treatment to the resist pattern to expand it, thereby removing the residue attached to the sidewall of the resist pattern. Only unnecessary films such as objects are destroyed to make removal of these unnecessary films easy and reliable.

However, in these methods, the step of immersing the resist pattern, that is, the stencil in a solvent is indispensable, that is, the so-called wet process. Therefore, when the thin film to be patterned is deposited relatively thickly, the stencil is used. The upper and side wall portions are almost covered with this thin film, and the above-described effects may not be sufficiently exhibited. Further, in such a method, it takes a considerable time to peel off the stencil, so that it is difficult to shorten the process.

According to the present invention, in the method of forming a thin film pattern as described above, it is possible to perform reliable patterning without using a wet process to form a finer pattern and to shorten the process. Try to simplify.

[0009]

The thin film pattern forming method of the present invention comprises a stencil 2 formed on a surface 1S of a substrate 1 as shown in FIGS. A thin film 3 to be formed on the substrate 2 is deposited, and an energy beam is irradiated from the back surface 1R side of the substrate 1 as shown by an arrow L to peel off the stencil 2 and pattern the thin film 3.

In the present invention, as shown in FIGS. 2A to 2C, which are manufacturing process diagrams, a stencil 2 is patterned on a surface 1S of a substrate 1, and then a thin film 3 to be formed on the stencil 2 is formed. The thin film 3 is deposited and irradiated with an energy beam from the surface 3S side of the thin film 3 as shown by an arrow L to peel off the stencil 2 and pattern the thin film 3.

[0011]

As described above, according to the method of the present invention, the surface 1 of the substrate 1 is
After patterning the stencil 2 on the S, a desired thin film 3 is deposited and formed on the S, and the stencil 2 is peeled off by irradiating an energy beam from the back surface 1R side of the substrate 1 or the upper surface 3S side of the thin film 3. Causes so-called ablation. That is, at this time, the stencil 2 absorbs the energy beam and is removed to the outside together with the thin film deposited thereon as shown by the arrow a, so that the pattern of the stencil 2 is reversed on the substrate 1. A thin film of the pattern is formed.

[0012]

EXAMPLES The energy beam used in the present invention is one that can efficiently pass through a substrate or a thin film and can cause ablation of a stencil. For example, laser light can be used.
In particular, an excimer laser with a large output and a short pulse and a large beam area can perform ablation over a large area in a short time without depending on the material type of the stencil. is there.

As the stencil, any photoresist and electron beam resist can be used.
When these resists are used, the stencil pattern can be formed by a conventional photolithography method.

Here, the film thickness of the stencil can be made much smaller than 1 μm required for ordinary photolithography, and even if the film thickness is 100 nm or less, thin film pattern formation can be achieved according to the present invention. is doing. Since the thickness of the stencil can be reduced in this way, there is an advantage that finer patterning of the stencil is possible.

Alternatively, the stencil may be formed by forming a non-photosensitive organic polymer film on the substrate by a method such as spin coating, vapor deposition, or plasma polymerization. In this case, pattern formation of the stencil is performed by ablation by irradiating a predetermined section by batch or stepping with light of a laser or the like through the aperture, or by scanning and irradiating a beam of laser or the like without passing through the aperture. Ablation can be performed by direct drawing.

The thin film formed on the stencil is made of a material that is not ablated by the energy beam applied. As a method of depositing this thin film,
Physical deposition methods such as vacuum deposition and sputtering, as well as thermal CVD
Either a (chemical vapor deposition) method or a chemical deposition method such as a plasma CVD method can be used, and the stencil as a base is not damaged during film formation, that is, the stencil resistance is maintained. I wish I had it.

For example, when an organic material such as polyimide having a high heat resistance is used as the stencil material, the resist material may lose its shape, have an effect, or be carbonized in the patterning with a normal photoresist. Which cannot be performed at 200 ℃
The thin film material can be formed by a relatively high temperature process of up to 400 ° C., and according to the present invention, such thin film can be easily patterned. Even if the stencil is made of an inorganic material, if it is a material such as hydrogenated amorphous silicon that can be ablated with relatively weak energy, peeling can occur without damaging the thin film to be patterned and the substrate. You can

In the present invention, the stencil is irradiated with an energy beam for peeling. For example, when a hydrogen storage metal such as palladium is used as the stencil, a thin film is entirely deposited on the stencil. When an energy beam such as a laser beam is irradiated, hydrogen gas in palladium is released all at once, and the thin film deposited on the hydrogen gas can be removed to form a thin film pattern.

On the other hand, it is necessary to optimize the irradiation condition of the energy beam in consideration of the material of the stencil, the threshold energy of ablation, and the like. However, in general, by inputting energy above the threshold value, the upper thin film is sufficiently removed. However, irradiation with a beam having excessively large energy may damage parts other than the thin film to be removed, and it is necessary to appropriately select the upper limit energy value.

For example, when an excimer laser is used, it is possible to perform almost ablation, that is, lift-off, by irradiation with one pulse, but in order to reliably avoid stencil residue, it may be more effective to perform pulse irradiation several times. . When the energy condition is optimized, a thin film pattern can be formed without causing damage even if several pulse irradiations are performed on the same portion.

The atmosphere for irradiation with the energy beam may be either vacuum or the atmosphere. When a stencil made of an organic material is used, irradiation with a cooling gas such as helium or an oxygen stream can be performed to form a clean pattern without leaving a carbide residue.

Next, each example of the thin film pattern forming method of the present invention will be described in detail with reference to the drawings. First, the example shown in FIG. 1 shows a case in which the base 1 is made of a transparent substrate, for example, a glass substrate, and a mask pattern made of Cr or the like is formed thereon. As shown in FIG. 1A, a stencil 2 made of photoresist or the like is applied on the surface 1S of the substrate 1 by resist coating,
A pattern is formed through steps such as pattern exposure and development. In this case, the pattern of the stencil 2 is formed as an inverted pattern of the desired thin film pattern.
After this, as shown in FIG. 1B, a thin film 3 is deposited over the entire surface of the stencil 2 by the CVD method or the like. Next, as shown in FIG. 1C, an arrow L is drawn from the rear surface 1R side of the substrate 1.
An energy beam such as an excimer laser is irradiated as indicated by. The stencil 2 is peeled off as shown by the arrow a,
The thin film 3 on the stencil 2 is removed to form a thin film 3 having a predetermined pattern as shown in FIG. 1D. With such a method, a large area Cr mask can be formed in a short time without leaving unnecessary deposits.

Further, in this case, since the undercut of the stencil which is required in the above-mentioned conventional example is not necessary, a combined pattern of etching and lift-off can be formed in one photoresist process, so that a thin film embedding structure is formed. A device having

Next, referring to FIG. 2, the thin film 3 on the substrate 1
The case where a pattern is formed by irradiating an energy beam from the surface 3S side of the above. In this example, a transparent electrode made of SnO ₂ is formed on a glass substrate, and amorphous silicon is formed on the transparent electrode to form a solar cell.

First, as shown in FIG. 2A, a stencil made of polyimide or the like is patterned on a substrate 1 made of a glass substrate or the like, and a thin film 3 made of a transparent conductive material such as SnO ₂ is entirely sputtered thereon. And so on. Then, after this, the entire surface of the thin film 3 is irradiated with laser light having a predetermined energy from the surface 3S side as indicated by an arrow L. At this time, the stencil 2 peels off and S
The nO ₂ thin film is removed and the thin film 3 or the transparent electrode can be patterned. Then, an amorphous silicon (a-Si) layer 5 and an electrode layer 6 made of Al or the like are sequentially patterned thereon to form a solar cell.

Next, the case of patterning the Al wiring layer will be described with reference to FIG. In this example, a substrate 1 made of a glass substrate having a transmittance of about 75% for a XeCl excimer laser having a wavelength of 308 nm is prepared, and as shown in FIG. Then, a photoresist having a thickness of 600 nm is applied by spin coating or the like, and a stencil having a pattern of 10 μm width is formed by mask exposure and development. Further, an Al thin film 3 having a film thickness of about 200 nm is formed on the entire surface by vacuum evaporation or the like. Next, a XeCl excimer laser having an energy density of 70 mJ / cm ² is irradiated from the back surface 1R side of the substrate 1 to remove the stencil 2 as shown by an arrow a in FIG. 3B, and an Al wiring pattern is satisfactorily formed. Can be formed.

Then, for example, as shown in FIG. 4, after the Al wiring layer 12 is formed on the substrate 1 by the above-mentioned method, the insulating layer 13 made of SiN _x or the like is entirely formed on this, the intrinsic hydrogenated amorphous silicon, etc. A channel layer 14 made of Al is deposited, and a source / drain region 15 made of hydrogenated amorphous silicon or the like doped with a high concentration of n-type impurities and an electrode 16 made of Al are patterned and formed. A so-called bottom gate type thin film transistor having the Al wiring layer 12 as a gate can be obtained.

Next, referring to FIG. 5, a case where a stencil made of a high heat resistant material is patterned by irradiation with an excimer laser through an aperture mask instead of the ordinary photolithography is shown. In this example, as shown in FIG. 5A, a stencil material layer 2a made of a heat-resistant organic material such as photosensitive polyimide is formed on a substrate 1, and a material is formed through a mask 4 as shown by an arrow L _1. A laser beam is irradiated from the upper surface side of the layer 2a as shown by an arrow L ₁ , and only the irradiated portion is peeled off to form the stencil 2 having a predetermined pattern as shown in FIG. 5B. And on top of this ITO (I
A thin film 3 made of a complex oxide of n and Sn) is formed over the entire surface. In this case, the film is formed by a relatively high temperature process, but since a material having poor heat resistance such as photoresist is not used as the material of the stencil 2, the film can be surely formed. Then, as shown in FIG. 5C,
A second laser beam is irradiated from the back surface 1R side of the substrate 1 as shown by an arrow L ₂ , and the stencil 2 is separated as shown by an arrow a to form a thin film 3 having a predetermined pattern.

In this case, when the thin film 3 is patterned, the ITO thin film 3 can be simultaneously irradiated with light to perform a modification treatment. That is, in the normal ITO manufacturing process, annealing is performed to reduce the resistance after film formation, but according to the present invention, such an annealing process is unnecessary, and the manufacturing process is simplified. be able to.

When the conventional lift-off method is used as the ITO patterning method, it is difficult to form a submicron pattern. However, applying the present invention, for example, as a stencil material, a normal novolac positive resist. In the case of patterning by stencil peeling by irradiating with a laser beam using, it was possible to form a fine ITO conductive pattern with an interval of about 0.8 μm.

Needless to say, the present invention is not limited to the above-mentioned embodiments, and the method of the present invention can be applied to patterning a thin film made of various other materials.

[0032]

As described above, according to the method of the present invention,
Since the pattern can be formed by a dry process without using a wet process, the manufacturing time can be shortened and it is advantageous in forming a large area pattern.

Further, since the thickness of the stencil can be made small, the fine pattern of the stencil can be easily formed, that is, the thin film pattern can be miniaturized. In particular, it is suitable for patterning ITO, which has been difficult to perform fine patterning in the sub-micron unit in the past, and in this case, modification such as reduction of resistance by light irradiation can be performed and the manufacturing process can be simplified. it can.

Further, in the method of the present invention, since the undercut of the stencil is not necessary, a combination pattern of etching and lift-off can be formed in one photoresist step, and therefore a device having a thin film embedded structure can be manufactured. Is possible.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of an example of a thin film pattern forming method.

FIG. 2 is a manufacturing process diagram of another example of the thin film pattern forming method.

FIG. 3 is a manufacturing process diagram of another example of the thin film pattern forming method.

FIG. 4 is a schematic enlarged cross-sectional view of an example of a thin film transistor.

FIG. 5 is a manufacturing process diagram of another example of the method of forming a thin film pattern.

FIG. 6 is a manufacturing process diagram of another example of the conventional method of forming a thin film pattern.

[Explanation of symbols]

 1 substrate 2 stencil 3 thin film

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/3205 31/04 // H01L 29/784 9056-4M H01L 29/78 311 F (72) Inventor Usui Setsuo 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (2)

[Claims] 1. After patterning a stencil on the surface of a substrate, a thin film to be formed is deposited on the stencil, and an energy beam is irradiated from the back side of the substrate to peel off the stencil. A method of forming a thin film pattern, which comprises patterning the above thin film. 2. After patterning a stencil on the surface of a substrate, a thin film to be formed is deposited on the stencil, and an energy beam is irradiated from the surface side of the thin film to peel off the stencil. A method of forming a thin film pattern, which comprises patterning the above thin film.