JP2689395B2 - Wafer peripheral exposure equipment - Google Patents

Description

The present invention relates to a semiconductor substrate typified by a silicon wafer, a dielectric, or a semiconductor substrate in the process of forming a circuit pattern in the production of ICs, LSIs, and other electronic devices.
The present invention relates to exposure of a peripheral portion of a wafer for removing an unnecessary resist in the peripheral portion of the wafer among resists applied to a substrate such as a metal or an insulator (collectively referred to as a wafer in the present application) in a developing process.

[Conventional technology]

In the manufacturing process of ICs, LSIs, etc., when forming a fine circuit pattern, a resist is applied to the surface of a silicon wafer or the like, and then exposed and developed to form a resist pattern. Next, processes such as ion implantation, etching, and lift-off are performed using the resist pattern as a mask.

Usually, the resist is applied by a spin coating method. The wafer is rotated while pouring the resist on the center position of the wafer surface, and the resist is applied to the entire surface of the wafer by centrifugal force.

The exposure for forming the pattern is performed by a sequential moving reduction projection exposure apparatus (hereinafter referred to as a stepper).
FIG. 4 is a diagram schematically showing the wafer exposed by the stepper. As shown in FIG. 4, the wafer is stepwise exposed by a stepper in a grid pattern for each chip portion T. However, as is clear from FIG. 4, in the chip portion Tp in the peripheral portion of the wafer, I cannot draw the circuit pattern correctly and completely. Therefore, the tip portion Tp
It is also practiced to omit the step exposure for the above to increase the throughput of exposure for one wafer. In any case, the resist in the portion where the circuit pattern is not drawn correctly and completely remains as an unnecessary resist even after development.

The presence of unnecessary resist around the wafer that remains after such development causes the following problems. That is, the wafer on which the resist is applied is transported by various processing steps and various methods. At this time, the peripheral portion of the wafer is mechanically grasped and held, or the peripheral portion of the wafer rubs against the wall of a container such as a wafer cassette. At this time, if unnecessary resist around the wafer is removed and adheres to the pattern forming portion of the wafer, correct pattern formation cannot be performed,
Reduce yield.

It is a serious problem that the unnecessary resist around the wafer becomes "dust" and the yield is lowered, especially in the present situation where the performance and miniaturization of integrated circuits are progressing.

Therefore, as a technique for removing the unnecessary resist in the peripheral portion of the wafer, it is conceivable to separately perform the exposure in order to remove the unnecessary resist in the peripheral portion of the wafer in the developing process, separately from the exposure process for forming the pattern. ing.

[Technical problem to be solved by the invention]

The following several methods are conceivable as the above-mentioned wafer peripheral exposure method. FIG. 5 is a view for explaining the outline of such a possible wafer peripheral exposure method.

One method is as shown in FIG.
While rotating the, the light from the light source lamp 1
This is a method of guiding by means of 40 and irradiating the wafer peripheral portion Wp.
With this method, it is necessary to perform exposure with a considerably high illuminance and to perform it at a high rotation speed in order to prevent the productivity from decreasing, but when the resist is exposed with a high illuminance, foaming of the resist or the like occurs. Further, as shown in FIG. 4, the boundary line Wt between the unnecessary resist in the peripheral portion of the wafer and the resist in the pattern forming portion actually has a step-like shape.
In the wafer periphery exposure method shown in FIG. 6A, it is quite difficult to expose only the unnecessary resist on the periphery of the wafer along the stepwise boundary line Wt.

As another method, as shown in FIG. 5 (b), a reticle 6 in which a reticle pattern is formed so as to expose an unnecessary resist pattern is used, and the same exposure as in ordinary photolithography is performed. Is. This method may be a projection method in addition to the contact method or proximity method as shown in FIG. 5B, but it is necessary to illuminate the reticle 6 to cover the portion where the reticle pattern is formed. The light is also applied to the central part of the reticle 6, while it is the peripheral part of the reticle 6.
There is a lot of wasted light. Further, since the same illumination optical system I as that of the exposure apparatus used for ordinary photolithography is required, the apparatus becomes large in size, and it becomes difficult to mount it on, for example, a resist coating machine or a developing machine.

It is also conceivable that the shape of the emission end face of the optical fiber is formed in the same manner as an unnecessary resist pattern, and the light from the emission end face is directly imaged on the wafer by the imaging lens. This is not practical because the image of each strand of fiber is transferred.

[Object of the invention]

The present invention has been made in consideration of the above problems. In a wafer peripheral portion exposure apparatus that exposes unnecessary resist on the wafer peripheral portion, it is not necessary to perform exposure with high illuminance, and along a stepped boundary line. The purpose is to be able to expose only unnecessary resist, not to waste light, and to make the device compact.

[Configuration of the invention]

In order to achieve such an object, a wafer peripheral portion exposure apparatus of the present invention includes a light source lamp, a reticle on which a reticle pattern is formed so as to expose a resist unnecessary for forming a circuit pattern, and a reticle pattern of which the emission end surface is the reticle. And an optical fiber having a ring shape for guiding light from a light source lamp so as to illuminate only a ring-shaped peripheral region including the light source lamp.

[Action]

In the wafer peripheral exposure apparatus of the present invention according to the above configuration, the light from the light source lamp is guided by the optical fiber,
The light is emitted from the emission end face having a ring shape to illuminate the ring-shaped peripheral region including the portion of the reticle pattern. Light from the reticle is applied to an unnecessary portion of the resist applied to the wafer, and the reticle pattern previously formed as the pattern of the unnecessary resist is transferred to the resist.

〔Example〕

 Examples of the present invention will be invented below.

FIG. 1 is a schematic explanatory view of a wafer peripheral portion exposure apparatus of an embodiment of the present invention. H is a light source device, 4 is an optical fiber, 5
Is a lens, 6 is a reticle, 7 is an imaging lens, and W is a wafer.

FIG. 2 is an illustration of a reticle illuminated with light from the optical fiber of FIG. Reference numeral 61 indicates a reticle pattern formed so as to expose only a resist unnecessary for forming a circuit pattern, and reference numeral 62 indicates a peripheral region including the reticle pattern 61.

In FIG. 1, a light source device H includes a light source lamp 1 such as a short arc type ultra-high pressure mercury lamp, an elliptical focusing mirror 2, a plane reflecting mirror 3 and the like. The light source device H is arranged separately from the main body M of the wafer peripheral portion exposure device shown by the dotted line. Therefore, the main body M can be designed compactly and can be easily arranged in a narrow place such as when mounted on a resist coating machine or the like.

In FIG. 1, the light from the light source lamp 1 is condensed by the elliptical condenser mirror 2, reflected by the plane reflecting mirror 3, and enters the optical fiber 4. The light that has entered the optical fiber 4 is guided by the optical fiber 4 and exits from the exit end face.
To illuminate. Then, the light from the reticle pattern 61 of the illuminated reticle 6 is coupled to the wafer W by the imaging lens 5, and the reticle pattern 61 is transferred to the resist on the wafer W.

Here, on the output side of the optical fiber 4 in FIG. 1, the strands of wire are bundled in a hakama-like shape so as to illuminate a ring-shaped peripheral region 62 including the reticle pattern 61 shown in FIG. It has a shape of. Therefore, the optical fiber 4
The light guided by is the ring-shaped peripheral region shown in FIG.
There is no waste of light by illuminating only 62. However, in the resist applied on the wafer W, the central chip portion may not be necessary at several places, and the exposure by the stepper may be omitted. Therefore, the reticle pattern 61 and the fiber 4 may be exposed at the same time. May be configured. Further, when there is a separate portion to be held by a wafer clamp or the like in a later step, the reticle pattern 61 and the fiber 4 may be configured so that the resist in the holding portion is also exposed. In any case, in this embodiment, unlike the method shown in FIG. 5A, since the reticle transfer method is used, it is possible to freely expose only the unnecessary resist. The lens 5 is for allowing the light from the reticle 6 to enter the imaging lens 7 correctly.

FIG. 3 is a schematic explanatory view of another embodiment of the present invention.
As shown in FIG. 3, instead of the lens 5 shown in FIG. 1, the output side of the optical fiber 4 is manufactured so as to be inclined toward the center of the ring, and the light from the reticle is correctly incident on the imaging lens. I am trying to let you. Although the optical fiber 4 is slightly more difficult to manufacture than the embodiment shown in FIG. 1,
Since the lens 5 is not required, the cost is correspondingly low and the device can be made compact.

In the embodiment shown in FIGS. 1 and 3, the imaging lens 7
Is used to form an image of the reticle pattern 61 on the wafer W to expose the peripheral portion of the wafer W, the boundary line Wt shown in FIG. 4 can be exposed sharply and accurately. However, the exposure may be performed by the contact method or the proximity method without using the imaging lens 7.

By the exposure described above, it is possible to omit all the step exposure for the chip portion Tp shown in FIG. 4 in the exposure step for forming the circuit pattern by the stepper, and it is expected that the throughput in the exposure step is improved.

〔The invention's effect〕

As described above, the wafer peripheral exposure apparatus of the present invention includes a light source lamp, a reticle on which a reticle pattern is formed so as to expose a resist unnecessary for forming a circuit pattern, and an emission end surface including the reticle pattern of the reticle. Since the optical fiber having the ring shape and guiding the light from the light source lamp is provided so as to illuminate the ring-shaped peripheral region, the following respective effects are achieved.

There is no need to expose with high illuminance.

Only unnecessary resist can be exposed along the stepped boundary line.

There is no waste of light.

The device can be made compact.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a wafer peripheral portion exposure apparatus of an embodiment of the present invention, FIG. 2 is an explanatory view of a mask illuminated by light from an optical fiber of FIG. 1, and FIG. FIG. 4 is a diagram schematically illustrating another embodiment of the invention, FIG. 4 is a diagram schematically showing a wafer exposed by a stepper, and FIG. 5 is a diagram schematically illustrating a possible wafer peripheral portion exposure method. In the figure, 1 ... Light source lamp 4 ... Optical fiber 41 ... Output end face of optical fiber 6 ... Reticle 61 ... Reticle pattern 62 ... Peripheral area 7 ... Imaging lens W ... Wafer Wp ... Wafer peripheral part Indicates.

Claims (1)

(57) [Claims] 1. A light source lamp, a reticle on which a reticle pattern is formed so as to expose a resist unnecessary for forming a circuit pattern, and a ring so that an emission end face illuminates a ring-shaped peripheral region including the reticle pattern of the reticle. And an optical fiber for guiding light from a light source lamp, the wafer peripheral exposure apparatus.