JP3251999B2 - Coating method - Google Patents

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 coating film such as a resist.

[0002]

2. Description of the Related Art In order to increase the degree of integration of semiconductor devices, reduce wiring resistance, increase the degree of freedom in wiring layout, and increase the processing speed, a multilayer wiring structure as shown in FIG. It is performed on devices and the like. This wiring structure is formed on the surface of a semiconductor wafer or a glass substrate 100 by A
The first-layer wiring 101 made of l.
An insulating film 102 is formed on the wiring 101 of the layer, a wiring 103 of the second layer is formed on the insulating film 102, and the wiring 103 of the first layer and the wiring 103 of the second layer are formed on the insulating film 102.
The connection is made through a through hole 104 formed at the bottom.

In order to obtain the above-mentioned multilayer wiring structure, first, FIG.
As shown in FIG. 4B, an insulating film 102 having a uniform thickness is formed on the first layer wiring 101 by CVD, and then, as shown in FIG.
At the same time, the resist film 105 is irradiated with ultraviolet rays through a mask 106 to dissolve and remove, for example, a portion 105a irradiated with the ultraviolet rays.
As shown in (d), the insulating film 1 is interposed via the resist film 105.
02 is etched to form a through hole 104, and then the resist film 105 is removed to form a second layer wiring 103.
Is formed (FIG. 4A).

[0004]

In the above-described resist solution coating process shown in FIG. 4C, the resist solution tends to collect in the recesses. The resist film 1 formed for this purpose
Also in the thickness of 05, the thickness B in the concave portion is larger than the thickness A on the convex portion (Al wiring). The wiring 101 is provided on the substrate 100.
5A, the wiring 101 acts as a weir against the flow of the resist solution as shown in FIG. 5A, and the thickness on the inner peripheral side becomes larger than the thickness on the outer peripheral side. That is, in FIG. 5A, A ₁ > A ₂ and B ₁ > B ₂ . Thus, thickness A and thickness B or thickness A ₁ and A ₂ , thickness B ₁ and B ₂
Are different from each other, the depth of focus at the time of exposure is partially different. For example, as shown in FIG.
05 cannot be accurately patterned, and precise wiring cannot be performed.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to forming a coating film such as a resist on the surface of a semiconductor wafer or a glass substrate by using a rotating cup type coating apparatus. Using a solvent of 110 ° C. or higher,
The viscosity of the coating solution was set to 5 cP or more, and the pressure in the inner cup of the coating device was reduced to 5 Torr or more within 60 seconds from the start of rotation.

[0006]

When the resist solution is applied under the above conditions, the film thickness ratio (A / B) can be made close to 1, that is, conformal coating can be performed. Here, A is the film thickness from the surface of the first-layer wiring, and B is the film thickness from the surface of the plate-like workpiece (the part without wiring). In addition to conformal coating,
The thickness of the left and right resist films becomes substantially equal, with the center of the convex portion of the wiring or the like as the center.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a sectional view of an open state of a rotary cup type coating apparatus used for carrying out the method of the present invention, and FIG. 2 is a sectional view of a closed state of the rotary cup type coating apparatus.

The rotating cup type coating apparatus includes an inner cup 2 inside an annular outer cup 1 fixed to a base plate.
And the inner cup 2 is attached to a shaft of the spinner device 3 to rotate the inner cup 2 at high speed. A vacuum chuck 4 for adsorbing and fixing a semiconductor wafer W as a plate-like workpiece is provided at the center of the bottom of the inner cup 2, and a drain pipe 6 facing a collection passage 5 formed in the outer cup is provided on a side surface of the inner cup 2. Is installed.

An arm 7 is arranged above the outer cup 1 and the inner cup 2. The arm 7 can be moved linearly, rotationally, vertically, or a combination of these. A shaft 8 extending downward is attached to the tip of the arm 7. A nozzle hole 9 is formed in the shaft 8, and the nozzle hole 9 is connected to the joint. And a hose passing through the inside of the arm 7 to a nitrogen gas supply source and a cleaning liquid supply source.

A boss 10 is rotatably fitted to the shaft 8 via a bearing and a magnetic seal, and a disc-shaped poly for closing the upper opening of the inner cup 2 is fitted to the boss 10. A lid 11 made of vinyl chloride is attached. Further, a lid 12 for closing the upper opening of the outer cup 1 is fixed to the lower surface of the tip of the arm 7 above the lid 11.

The lid 12 is vertically slidably held on the outer periphery of a cylindrical body 13 attached to the lower surface of the tip of the arm 7 via a ring-shaped slide member 14, and the inner peripheral edge of the lid 12 is made of Teflon. A bearing 15 is mounted, and a guide post 16 implanted in the cylindrical body 13 is engaged with the bearing 15. When the arm 7 is raised as shown in FIG. 1, the pin 18 fixed to the lid 11 engages with the receiving hole 17 formed in the lid 12 to position the lid 11. When the arm 7 descends and the lids 11 and 12 close the openings of the inner cup 2 and the outer cup 1, respectively, as shown in FIG. 2, the lid 12 moves up along the guide post 16, The pin 18 comes out of the receiving hole 17. A rectifying plate 20 for preventing turbulence in the inner cup 2 is attached to the lower surface of the lid 11 by screws 19.

In the above, in order to apply the resist liquid to the surface of the semiconductor wafer W, the upper surfaces of the cups 1 and 2 are opened, and the resist liquid is dropped on the surface of the semiconductor wafer W fixed on the vacuum chuck 4. Next, as shown in FIG. 1, the arm 7 is rotated on the inner cup 2 and the outer cup 1 so that the lids 11 and 12 face each other. Then, as shown in FIG. When the upper surface of the inner cup 2 is closed with the cover 12 and the upper surface opening of the outer cup 1 is closed with the lid 12, the vacuum chuck 4 and the inner cup 2 are integrally rotated by a spinner, and the resist solution is centrifugally dispensed with the semiconductor wafer. Apply to the surface of W.

When the inner cup 2 rotates at a high speed together with the vacuum chuck 4 as described above, the gas (air) in the inner cup 2 is discharged from the drain pipe 6 to the outside (recovery passage 5), and the inner cup 2 The pressure is reduced.

Here, in the present invention, the pressure in the inner cup 2 is increased by 5 T from the speed before rotation within 60 seconds after the start of rotation.
The pressure is reduced to not less than orr, preferably 5 to 30 Torr. To be able to perform coating under such conditions, a spinner capable of high-speed rotation (1,000 rpm or more) must be used, but it is more important to make the shape of the inner cup 2 as flat as possible. is there. By making the shape flat, the volume inside the inner cup 2 can be reduced, so that a desired reduced pressure can be achieved in a short time, and the acting centrifugal force can be used to the maximum. Further, in order to reduce the pressure by 30 Torr or more before rotation, the structure must be further complicated, which is not preferable.

FIG. 3 is a graph showing the relationship between the film thickness ratio (A / B) and the pressure reduction in the inner cup.
When the pressure is reduced to orr or more, the film thickness ratio (A / B) is infinitely 1
You can see that it approaches. The resist solution used to obtain the results shown in FIG. 3 was OFPR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), the viscosity of the resist solution was 5 cP or more, and the boiling point of the solvent was 110 ° C. or more. The reason why the viscosity is set to 5 cP or more is to make it difficult for the solution accumulated in the convex portion of the wiring to flow into the concave portion due to the reflow effect, and to set the boiling point to 110 ° C. or more because the solution is saturated in the coating atmosphere. This is to make it difficult for the state to occur.

Further, according to the method of the present invention, the film thickness ratio (A / B)
, That is, it is effective to make A / B close to 1 The height of the wiring is 0.2 to 50 μm and the width is 0.3 to 100 μm.
μm, and the distance between adjacent wirings is 0.3 μm to 100 μm.
μm.

[0017]

According to the present invention as described above,
In forming a coating film such as a resist on the surface of a semiconductor wafer or a glass substrate using a rotating cup type coating apparatus, the pressure in the inner cup of the coating apparatus is reduced to 5 Torr or more from before rotation within 60 seconds from the start of rotation. So that
And a solvent having a boiling point of 110 ° C. or higher is used as a coating liquid,
Since a viscosity of 5 cP or more was used, the film thickness ratio (A /
B) can approach 1. Further, according to the present invention, since the resist solution is applied in a closed application space without airflow, drying of the resist solution is suppressed, and the self-flowability of the resist solution is maintained. As a result, FIG. As shown, the thickness A ₁ on the inner circumference side, the thickness A ₂ on the outer circumference side, the thickness B ₁ on the inner circumference side relative to the wiring 101, and the thickness B ₂ on the outer circumference side relative to the wiring 101 are all substantially equal. . Therefore, the photoresist can be applied conformally and symmetrically with respect to the projections, so that the depth of focus can be adjusted on the wiring and where there is no wiring, and more accurate multilayer wiring can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of an open state of a rotating cup type coating apparatus used for carrying out the method of the present invention.

FIG. 2 is a sectional view of the rotating cup type coating apparatus in a closed state.

FIG. 3 shows a film thickness ratio and before and after rotation in an inner cup.
Graph showing the relationship with the pressure difference after 0 seconds

4A is a cross-sectional view showing an example of an ideal multilayer wiring structure, and FIGS. 4B, 4C, and 4D are cross-sectional views showing a procedure for manufacturing a multilayer wiring.

FIG. 5A is a view showing a thickness of a resist film near a wiring when a resist solution is applied by a conventional method, and FIG.
Is a diagram showing the thickness of a resist film near the wiring when a resist solution is applied by the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer cup, 2 ... Inner cup, 4 ... Vacuum chuck, 5 ... Recovery passage, 6 ... Drain pipe.

Continuation of the front page (72) Inventor Hiroki Endo 150 Nakamaruko, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Within Tokyo Ohka Kogyo Co., Ltd. (56) References JP-A-6-218322 (JP, A) JP-A-6-232036 (JP) JP-A-4-78469 (JP, A) JP-A-4-62923 (JP, A) JP-A-4-98823 (JP, A) JP-A-2-188945 (JP, A) 3-30453 (JP, A) JP-A-3-272130 (JP, A) JP-A-55-166923 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027

Claims (2)

(57) [Claims] 1. An inner cup rotated by a spinner is disposed in an outer cup, a plate-like workpiece is set in the inner cup, and a coating liquid is dropped on the surface of the plate-like workpiece. the coating liquid while reducing the pressure in the inner cup by rotation of the film forming method as allowed to diffuse into the plate-shaped object to be processed surface by centrifugal force, the wiring in the plate-shaped object to be processed surface
The coating liquid uses a solvent having a boiling point of 110 ° C. or higher, and the viscosity of the coating liquid is 5 cP or higher, and the pressure in the inner cup is 5 Torr or higher than before rotation within 60 seconds from the start of rotation. A method for forming a coating film, wherein the pressure is reduced. Wherein said unevenness height is 0.2μm or more 50μ
The method according to claim 1, wherein the width is 0.3 m or more and 100 m or less, and the distance between adjacent irregularities is 0.3 m or more and 100 m or less.