JPH07102368A - Formation of thin film - Google Patents

Abstract

PURPOSE:To provide a thin film forming method capable of preventing the warpage of a substrate caused by the stress of a thin film. CONSTITUTION:The thin film is formed by laminating a film 21 with tensile stress and a film 31 with compressive stress constituted of the material same as that of the film 2 with tensile stress at the time of forming a Cr thin film on a glass substrate 1, working the thin film and producing a device. The thin film is formed in a state where the substrate 1 is previously warped in a direction opposite to the warping direction of the substrate 1 by film stress after film forming. The thin film is formed on the substrate 1 after a buffer film is previously formed thereon, or a buffer film is formed on a thin film formed on the substrate 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a thin film. More specifically, in a manufacturing process of a large-sized display device such as a liquid crystal display device and an electroluminescence display device, and a large-scale photoelectric conversion device such as a contact image sensor, it is possible to reduce a warp of a substrate that occurs after a thin film is formed. The present invention relates to a method for forming a thin film.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of large display devices such as liquid crystal display devices and electroluminescence display devices and large photoelectric conversion devices such as contact image sensors, large glass substrates of 300 mm square or larger are used. However, when attempting to form a film on such a large-sized substrate while maintaining physical properties other than stress, such as adhesion, it is sometimes necessary to form a thin film having large stress. 9 and 10 are schematic explanatory views showing the state of the substrate before and after the thin film is formed by such a conventional thin film forming method. 9 (a) and 10
FIG. 9A shows the state of the substrate before the thin film is formed.
FIG. 10B and FIG. 10B show the state of the base material after the thin film is formed on the substrate. After the thin film has been formed in this manner, FIG. 9B and FIG.
As shown in FIG. 9, the substrate is largely warped, and the warp width (a in FIG. 9B, b in FIG. 10B, and so on) is
Usually, it is about 200 to 500 μm.

When the substrate is thus largely warped, the substrate and the stage are subjected to vacuum suction from a stage provided on the lower surface of the substrate in order to fix the substrate in the subsequent patterning process. Since there is a gap between them, the substrate cannot be sufficiently fixed by vacuum suction, or when the warpage width caused by such warpage exceeds 200 μm at the time of photolithography, the exposure focus It causes inconvenience that
There is a problem that the manufacturing yield of the device is drastically reduced.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and provides a method for forming a thin film capable of keeping the warp width of a substrate warped by the stress of the thin film within 200 μm. The purpose is to

[0005]

According to the present invention, when a thin film is formed on a substrate and the thin film is processed to manufacture a device,
A method for forming a thin film, characterized in that a thin film is formed by laminating a tensile stress film and a compressive stress film made of the same material as the tensile stress film so that the stress of the thin film is relaxed. 1) forming a thin film on a substrate, and processing the thin film to manufacture a device, a direction opposite to the direction in which the substrate warps due to a film stress after the film is formed before the film is formed. A thin film forming method (hereinafter referred to as a second thin film forming method), characterized in that the thin film is formed in a state in which the substrate is warped so that the stress of the thin film is relaxed. When manufacturing a device by processing a thin film, a buffer film for relaxing the stress is formed in advance on the substrate so that the stress of the thin film is relaxed, and then the thin film is formed ( Hereinafter, referred to as a third thin film forming method), A thin film is formed on a substrate and a substrate, and a buffer film is formed on the thin film so that stress of the thin film is relaxed when the thin film is processed to manufacture a device (hereinafter , Referred to as a fourth thin film forming method).

[0006]

First, according to the first thin film forming method of the present invention, when a thin film is formed on a substrate and the thin film is processed to manufacture a device, the stress of the thin film is relaxed. Then, a thin film is formed by laminating a tensile stress film and a compressive stress film made of the same material as the tensile stress film.

The substrate is not particularly limited as long as it is a commonly used substrate. For example, one side has a length of 1
Examples thereof include a glass substrate, a Si wafer, and a ceramics substrate having a thickness of about 00 to 1000 mm and a thickness of about 0.5 to 1.5 mm.

The tensile stress film is a film having a density lower than that of the substance forming the film, and is formed by using, for example, a material such as Cr, SiO ₂ or SiN by, for example, a sputtering method. be able to.

The film of compressive stress is a film having a density higher than that of the substance forming the film, and is made of the same material as the film of tensile stress, for example, plasma C
It can be formed by a VD (chemical vapor deposition) method or the like.

In the present invention, since the film of tensile stress and the film of compressive stress are formed at the same time, the substrate itself is less likely to warp.

The tensile stress film and the compressive stress film are
Either of them may be formed first, but in consideration of the adhesion to the substrate, it is preferable that the film having tensile stress is formed on the substrate first.

When the tensile stress film and the compressive stress film are laminated, the number of laminated films is not particularly limited, and may be, for example, one layer each, or 3 to 10 layers. Although the number of layers may be approximately, if the stresses of the outermost surface layer and the lowermost layer are the same, they are odd layers.

The method for processing the thin film is not particularly limited, and a usual method such as photoetching can be used.

The second thin film forming method of the present invention is
This is a method that can be suitably used when the base material warps due to the stress of the film when a film with tensile stress or a film with compressive stress is formed. In the opposite direction, a thin film is formed in a state where the substrate is warped in advance by the amount that the substrate is warped by the film stress.

The method of bending the substrate is not particularly limited. For example, a height adjusting jig having a shape curved in a direction opposite to the warping direction of the substrate is attached to the mounting jig of the substrate, and the substrate is fixed. There is a method of attaching it so that it fits the height adjustment jig. Note that the substrate is generally warped in a direction opposite to the warp so that the substrate does not warp after film formation.

The method of forming the thin film is not particularly limited, and for example, a metal sputtering method or plasma C is used.
Examples thereof include a method of forming by a method such as VD method.

The number of layers of the thin film is not particularly limited,
If it is too much, it tends to be complicated, so that it is usually preferable to have about 1 to 15 layers.

In the third method for forming a thin film of the present invention, a thin film is formed after forming a buffer film for relaxing stress on a substrate in advance.

As the buffer film for relieving the stress, a compressive stress film is used when the thin film has a tensile stress, and a tensile stress film is used when the thin film has a compressive stress. Used.

The thickness of the buffer film is 0.1 to 1.0 μm.
Is preferred. The thickness of the buffer film is 0.1μ
If it is less than m, it is difficult to control the film thickness, and if it exceeds 1.0 μm, the throughput of film formation tends to decrease.

The thin film may be a single layer, a laminate of a plurality of layers, or a processed film.

In the fourth method for forming a thin film of the present invention, the buffer film is formed not above the thin film but above the thin film.

According to the thin film forming method of the present invention, as described above, it is possible to reduce the warp of the substrate that occurs after the thin film is formed.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Embodiment 1] FIG. 1 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the method for forming a thin film according to Embodiment 1 of the present invention.

First, the 300 mm shown in FIG.
A film of 0.25 μm thick tensile stress film made of Cr (tensile stress: 1.0 ×) was formed on a glass substrate 1 having a corner and a thickness of 1.1 mm.
10 ⁹ N / m ² ) 21 was formed by the sputtering method under the condition that the film forming rate was high, that is, under the high film forming power.
FIG. 1B shows a state where a tensile stress film 21 made of Cr is formed on the glass substrate 1. Then, on the tensile stress film 21 made of Cr, a film thickness of 0.25 made of Cr is formed.
By forming the film 31 having a compressive stress of μm by the plasma CVD method under the condition that the film forming rate is slow, that is, the film forming power is low, a Cr film having a film thickness of 0.5 μm (compressive stress: 0.5 ×
10 ⁹ N / m ² ) was formed.

As a result, the tensile stress film 21 made of Cr is formed.
And the compressive stress film 31 made of Cr cancel each other out, and the stress becomes very small in the whole thin film.
As shown in (c), the warp width of the glass substrate 1 is 20.
It was very small, 0 μm or less, and it was possible to avoid defocusing of exposure during photolithography.

[Embodiment 2] FIG. 2 shows a thin film having a thickness of 300 mm formed by the method for forming a thin film according to Embodiment 2 of the present invention.
It is a schematic explanatory view showing a state of a glass substrate having a corner and a thickness of 1.1 mm. As shown in FIG. 2, a tensile stress film (tensile stress: 1.0 × 10 ⁹ N / m ² ) 21 made of Cr formed by a sputtering method and a compression made of Cr formed by a plasma CVD method. Cr was formed in the same manner as in Example 1 except that a stress film (compressive stress: 0.5 × 10 ⁹ N / m ² ) 31 and 0.15 μm each were alternately laminated in four layers.
When the thin film of No. 2 was formed, the warp width of the glass substrate was as very small as 200 μm or less as in Example 1, and it was possible to avoid defocusing of exposure during photolithography.

[Embodiment 3] FIG. 3 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the method for forming a thin film according to Embodiment 3 of the present invention.

First, a jig 5 for mounting the glass substrate 1
Then, the height adjusting jig 4 is attached, and the glass substrate 1 having a 300 mm square and a thickness of 1.1 mm is attached along the jig 4, so that the film stress after film formation is increased as shown in FIG. The glass substrate 1 was bent in a direction (convex downward) opposite to the direction in which the glass substrate 1 was bent. Warp width is 500
was μm.

Next, with the glass substrate 1 warped,
On the glass substrate 1, a film having a compressive stress (compressive stress:
0.5 × 10 ⁹ N / m ² ) 32 was formed. Figure 3 (b)
And a compressive stress film 32 made of SiN on the glass substrate 1.
Shows the state in which the is formed.

After film formation, the height adjusting jig 4 to the glass substrate 1
When the film was removed, a compressive stress film 32 made of SiN was obtained.
Tries to warp upward with the thin film surface facing upward, but since the glass substrate 1 was warped downward convex before film formation,
As shown in (c), the warp of the glass substrate 1 was very small, and the warp width was 100 μm or less.

[Embodiment 4] FIG. 4 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the method for forming a thin film of Embodiment 4 of the present invention.

The glass substrate 1 is warped in a direction (convex upward) opposite to the warping direction by film formation (see FIG. 4 (a)), and a film made of Cr and having a tensile stress of 0.25 μm is formed by a sputtering method. (Tensile stress: 1.0 × 10 ⁹ N / m ² ) 22
A thin film was formed in the same manner as in Example 3 except that the above was formed (see FIG. 4B), and the height adjusting jig 4 was used to form the glass substrate 1.
After removing the film, the tensile stress film 2 made of Cr was formed.
2 was formed. The warp of the glass substrate 1 was very small as shown in FIG. 4C, and the warp width was 100 μm or less.

[Embodiment 5] FIG. 5 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the method for forming a thin film of Embodiment 5 of the present invention.

A compressive stress film 33 made of SiN having a film thickness of 0.7 μm is formed on the glass substrate 1 of 300 mm square and 1.1 mm in thickness shown in FIG. 5A by the plasma CVD method.
(Compressive stress: 0.7 × 10 ⁹ N / m ² ) was formed as a buffer film. FIG. 5B shows a state in which the buffer film is formed on the glass substrate 1.

Next, a tensile stress film made of Cr having a film thickness of 0.5 μm (tensile stress:
1.0 × 10 ⁹ N / m ² ) 22 was formed. As a result, the compressive stress of the buffer film and the tensile stress of the tensile stress film 22 of Cr buffer each other, and the overall film stress becomes extremely small. As shown in FIG. The warp of the substrate 1 is extremely small and the warp width is 100 μm.
It was below.

Similar results were obtained in the case of an electronic device formed by providing a buffer film having a stress opposite to the stress that the thin film has as a whole between the glass substrate 1 and the thin film.

[Sixth Embodiment] FIG. 6 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by a thin film forming method of a sixth embodiment of the present invention.

On the glass substrate 1 of 300 mm square and 1.1 mm in thickness shown in FIG. 6A, a film having a tensile stress of SiO _{2 having a} film thickness of 0.5 μm (tensile stress: 1. 0 × 10 ⁹ N / m ² ) 23 was formed as a buffer film. FIG. 6B shows a state in which the buffer film is formed on the glass substrate 1.

Next, a film thickness of 0.
A film of compressive stress composed of 5 μm SiN (compressive stress: 0.
7 × 10 ⁹ N / m ² ) 32 was formed. As a result, the buffer film having tensile stress and the compressive stress film 32 made of SiN are formed.
As a result, the film stress as a whole became extremely small by buffering each other, and as shown in FIG. 6C, the warp of the glass substrate 1 was extremely small and the warp width was 200 μm or less.

[Embodiments 7 to 8] FIGS. 7 and 8 are schematic explanatory views showing a state of a glass substrate when a thin film is formed by the method for forming a thin film of Embodiments 7 and 8 of the present invention, respectively.

A thin film transistor 34 having a compressive stress of about 2 × 10 ⁹ N / m ² was formed on a glass substrate 1 having a 300 mm square and a thickness of 1.1 mm. FIG. 7A shows a state in which the thin film transistor 34 having a compressive stress is formed on the glass substrate 1. Then, a tensile stress film (tensile stress: 1.0 × 10 ⁹ N / m ² ) 23 made of SiO _{2 having a} film thickness of 0.5 μm was formed thereon as a buffer film by a sputtering method. FIG. 7B shows a state in which a buffer film is formed on the thin film transistor 34 having the compressive stress (Example 7).

Further, a thin film transistor 24 having a tensile stress of about 2 × 10 ⁹ N / m ² was formed on the glass substrate 1 having a 300 mm square and a thickness of 1.1 mm. FIG. 8A shows a thin film transistor 24 having tensile stress on the glass substrate 1.
Shows the state in which the is formed.

Next, a 0.5 μm-thick film of SiN having a compressive stress (compressive stress: 0.7 × 10 ⁹ N / m ² ) 33 was formed thereon as a buffer film by the plasma CVD method. FIG. 8B shows a state in which a buffer film is formed on the thin film transistor 24 having the tensile stress (Example 8). When the glass substrate was observed, the stress of the thin film transistor was relieved by the buffer film, and as shown in FIGS. 7B and 8B, the warp of the glass substrate 1 was extremely small and the warp width was 200 μm or less. It was

[0046]

According to the present invention, when a thin film is formed on a substrate, the internal stress of the thin film is relaxed, so that the warp of the substrate due to the stress can be prevented and, for example, a vacuum suction defect due to the warp can be eliminated. be able to.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by a thin film forming method according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a state of a glass substrate on which a thin film has been formed by the thin film forming method of Example 2 of the present invention.

FIG. 3 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 3 of the present invention.

FIG. 4 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 4 of the present invention.

FIG. 5 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 5 of the present invention.

FIG. 6 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 6 of the present invention.

FIG. 7 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 7 of the present invention.

FIG. 8 is a schematic explanatory view showing a state of a glass substrate when a thin film is formed by the thin film forming method of Example 8 of the present invention.

FIG. 9 is a schematic explanatory view showing a state of a substrate before and after a thin film is formed by a conventional thin film forming method.

FIG. 10 is a schematic explanatory view showing a state of a substrate before and after a thin film is formed by a conventional thin film forming method.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H01L 21/205 (72) Inventor Masaki Nakabori 997 Miyoshi, Nishigoshi-cho, Kikuchi-gun, Kumamoto Prefecture Advanced Display Co., Ltd. ( 72) Inventor Hiromasa Morita, 997 Miyoshi, Nishigoshi-cho, Kikuchi-gun, Kumamoto Prefecture, Advanced Display Co., Ltd. (72) Inventor, Masaru Yamada, 997 Miyoshi, Nishigoshi-cho, Kikuchi-gun, Kumamoto Prefecture, Advanced Display, Inc.

Claims (4)

[Claims] 1. A tensile stress film and the same material as the tensile stress film so that the stress of the thin film is relaxed when a thin film is formed on a substrate and the thin film is processed to manufacture a device. A method of forming a thin film, which comprises laminating a film of compressive stress to form a thin film. 2. When a thin film is formed on a substrate and a device is manufactured by processing the thin film, stress of the thin film is applied in a direction opposite to a direction in which the substrate warps due to a film stress after the film is formed before the film is formed. A method for forming a thin film, which comprises forming the thin film in a state in which the substrate is warped so as to alleviate the temperature. 3. A thin film is formed on a substrate, and a buffer film for relaxing stress is formed on the substrate in advance so that the stress of the thin film is relaxed when the thin film is processed to manufacture a device. Forming a thin film. 4. A thin film is formed on a substrate, and a buffer film is formed on the thin film so that stress of the thin film is relaxed when the thin film is processed to manufacture a device. Forming method.