JPH08264533A - Pattern formation method - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the occurrence of short circuit or disconnection due to pattern burr. [Structure] On a substrate 1, a lower layer resist 6 and an upper layer resist 7 which is exposed by the same exposure source as the lower layer resist 6 and has an elution rate of an unexposed portion at the time of development smaller than that of the lower layer resist 6. A resist film 8 is formed, the resist film 8 is exposed and developed to form a resist pattern 9, and a pattern such as a metal thin film is formed by a lift-off method using the resist pattern 9. [Effect] It is possible to prevent the metal attached to the side surface of the resist pattern 9 from remaining on the substrate 1 without significantly increasing the number of steps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal pattern of a semiconductor device by using a lift-off method.

[0002]

2. Description of the Related Art An example of a method of forming a pattern of a metal thin film using a lift-off method will be described with reference to FIG. FIG. 3 is a sectional view of a substrate on which a pattern is formed. First, the resist film formed on the substrate 1 is exposed and developed by an exposure device so that a desired pattern is obtained, and a resist pattern 2 as shown in FIG. Next, as shown in (b), a metal thin film 3 is formed on the entire surface of the substrate 1 including the resist pattern 2 by vapor deposition or sputtering, and then the resist pattern 2 is removed by elution with an organic solvent or the like. Then, as shown in (c), the metal deposited on the resist pattern 2 is removed from the substrate 1 together with the resist pattern 2.
Then, the pattern 4 made of metal is formed on the portion of the substrate 1 where the resist pattern 2 was not formed.

[0003]

However, in the pattern forming method using the single-layer resist pattern 2 as shown in FIG. 3, the cross-sectional shape of the resist pattern 2 is
The taper shape (trapezoidal shape) having a wider width on the substrate 1 side. Therefore, the metal attached by vapor deposition or sputtering is also deposited on the side surface of the resist pattern 2. As a result, even if the resist pattern 2 is removed by elution, the metal deposited on the side surface of the resist pattern 2 remains, and burrs 4a and the like as shown in (c) occur to cause a short circuit or disconnection defect. There was a problem.

Therefore, in order to prevent deposition of a thin film of metal or the like on the side surface of the resist pattern, it is necessary to make the cross-sectional shape of the resist pattern a reverse taper shape (reverse trapezoidal shape) whose width is narrower on the substrate side. . However, a resist pattern having such a shape could not be obtained only by exposing and developing a conventional single-layer resist.

The present invention has been made in view of the above problems, and an object thereof is to prevent deposition of a metal thin film or the like on the side surface of a resist pattern, and to prevent short circuit or disconnection due to burrs or the like. Another object of the present invention is to provide a pattern forming method capable of preventing the occurrence of defects.

[0006]

In order to achieve the above-mentioned object, the pattern forming method according to claim 1, wherein a substrate is exposed to light with a lower layer resist and the same exposure source as the lower layer resist, and is not exposed during development. Forming a resist film having a two-layer structure composed of an upper layer resist having an elution rate of an exposed portion smaller than that of the lower layer resist, exposing the resist film with radiant light or electron beam and developing to form a resist pattern, The resist pattern is used to form a pattern such as a metal thin film by a lift-off method.

According to a second aspect of the present invention, there is provided a pattern forming method comprising: a lower layer resist on a substrate; and an upper layer resist which is more susceptible to deformation than the lower layer resist when exposed by the same exposure source as the lower layer resist. A resist film having a two-layer structure is formed, and the resist film is exposed by radiant light or electron beam and developed to form a resist pattern, which is then heated to deform the upper layer resist, and lift-off is performed using the resist pattern. The method is characterized in that a pattern of a metal thin film or the like is formed by a method.

[0008]

The pattern forming method according to claim 1 or 2 forms a resist pattern using a resist film in which two types of resists (lower layer resist and upper layer resist) having different properties are laminated, and The cross-sectional shape of the resist pattern is configured such that the resist on the substrate side (lower layer resist) has a substantially inverse tapered shape in which the width is narrower than that of the upper layer resist.

In the pattern forming method according to the first aspect, the lower layer resist and the upper layer resist are exposed by the same exposure source, and the upper layer resist has a smaller elution rate of the unexposed portion during development than the lower layer resist. First, the materials of the lower layer resist and the upper layer resist are selected. The upper layer resist and the lower layer resist are configured as described above,
When this resist film (upper layer resist and lower layer resist) is exposed to form a resist pattern and is developed longer than the just developing time for developing the lower layer resist, the lower layer resist is side-etched more than the upper layer resist. Therefore, the cross-sectional shape of the formed two-layer structure resist pattern is a substantially reverse taper shape in which the lower layer resist on the substrate side has a narrower width than the upper layer resist. Therefore, when a metal or the like is attached to the entire surface of the substrate by vapor deposition or sputtering, it is possible to prevent the metal or the like from attaching to the side surface of the lower layer resist. After that, when the resist pattern is eluted and removed with an organic solvent or the like,
Metal, etc. adhered to the upper and side surfaces of the upper layer resist,
It is removed from the substrate together with the upper layer resist, and as a result, a pattern made of metal or the like remains only on the surface of the substrate where the resist pattern has not been formed, so that a pattern without burr can be obtained.

In the pattern forming method according to the second aspect, the materials of the upper layer resist and the lower layer resist are selected so that the upper layer resist is more easily deformed than the lower layer resist when heated. The upper layer resist and the lower layer resist are configured in this way, and after this resist film (the upper layer resist and the lower layer resist) is exposed and developed to form a resist pattern, post-baking is performed in a temperature range where the upper layer resist is easily deformed. By doing so, the upper layer resist is thermally deformed to cause sagging, and the cross-sectional shape of the resist pattern having a two-layer structure is a substantially reverse taper shape in which the lower layer resist on the substrate side has a narrower width than the upper layer resist. Therefore, when a metal or the like is attached to the entire surface of the substrate by vapor deposition or sputtering, it is possible to prevent the metal or the like from attaching to the side surface of the lower layer resist. After that, when the resist pattern is eluted and removed with an organic solvent or the like, the metal or the like adhering to the upper layer resist is removed from the substrate together with the upper layer resist, and as a result, the metal only on the substrate surface where the resist pattern was not formed is formed. Since a pattern composed of etc. remains, a pattern without burr etc. can be obtained.

[0011]

EXAMPLE An example of the pattern forming method of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a substrate on which a pattern is formed. First, as shown in (a), a lower layer resist 6 and an upper layer resist 7 are applied on a substrate 5 to form 2
A resist film 8 having a layered structure is formed, exposed by radiant light or electron beam, and developed. Here, the materials of the lower layer resist 6 and the upper layer resist 7 are set so that the elution rate of the unexposed part of the upper layer resist 7 becomes smaller than the elution rate of the unexposed part of the lower layer resist 6 with respect to a predetermined developing solution. Select. In the middle of the development, as shown in (b), the state is just developed, but as shown in (c), further development is performed so that the lower layer resist 6 is side-etched more than the upper layer resist 7. A resist pattern 9 is formed.

Next, as shown in (d), a metal or the like is deposited on the entire surface of the substrate 1 by vapor deposition, sputtering or the like to form the thin film 1.
Form 0. Finally, when the resist pattern 9 (the lower layer resist 6 and the upper layer resist 7) is eluted and removed with an organic solvent or the like, a pattern 11 made of metal or the like is left on the substrate 1 neatly as shown in (e). become.

A different embodiment of the pattern forming method of the present invention will be described with reference to FIG. FIG. 2 is a sectional view of a substrate on which a pattern is formed. First, as shown in (a), the lower layer resist 13 and the upper layer resist 1 are formed on the substrate 12.
4 is applied to form a resist film 15 having a two-layer structure. In this case, when the upper layer resist 14 is heated, the lower layer resist 1 is more easily deformed than the lower layer resist 13.
3 and the material of the upper layer resist 14 are selected. next,
After exposure with radiant light or electron beam, development is performed until the resist film 15 is in a just developed state, as shown in (b).

Next, when the upper layer resist 14 is post-baked in a temperature range where it is likely to be thermally deformed, the upper layer resist 14 is deformed due to heat, and the width of the cross-sectional shape of the upper layer resist 14 becomes lower as shown in FIG. A resist pattern 16 wider than the width of the resist 13 in cross section is formed.
Further, as shown in (d), a metal or the like is attached to the entire surface of the substrate 12 by vapor deposition, sputtering or the like to form a thin film 17. Finally, as shown in (e), when the lower layer resist 13 and the upper layer resist 14 are eluted and removed with an organic solvent or the like, the pattern 18 made of metal or the like is left beautifully on the substrate 12.

[0015]

According to the pattern forming method of the first or second aspect, in the pattern formation of the metal thin film or the like by the lift-off method, the pattern is attached to the side surface of the resist pattern without significantly increasing the number of steps. Since it is possible to prevent metal or the like from remaining on the substrate, it is possible to significantly reduce defects such as short circuits or disconnection due to burrs or the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pattern forming method of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the pattern forming method of the present invention.

FIG. 3 is a cross-sectional view showing an example of a conventional pattern forming method.

[Explanation of symbols]

 1,10 Substrate 6,13 Lower layer resist 7,14 Upper layer resist 8,15 Resist film 9,16 Resist pattern

Claims (2)

[Claims] 1. A two-layer structure comprising a lower layer resist and an upper layer resist which is exposed to the same exposure source as that of the lower layer resist on a substrate and has an elution rate of an unexposed portion during development which is smaller than that of the lower layer resist. A resist film having a structure is formed, the resist film is exposed to radiation or electron beams and developed to form a resist pattern, and the resist pattern is used to form a pattern such as a metal thin film by a lift-off method. Pattern formation method. 2. A resist having a two-layer structure comprising a lower layer resist on a substrate, and an upper layer resist which is more susceptible to deformation than the lower layer resist when exposed to the same exposure source as the lower layer resist and heated. A film is formed, and the resist film is exposed by radiant light or electron beam and developed to form a resist pattern, and the resist is heated to deform the upper layer resist, and a pattern such as a metal thin film is formed by a lift-off method using the resist pattern. A method for forming a pattern, which comprises: