JPH08102439A - Unnecessary resist exposure device on wafer - Google Patents

Abstract

(57) [Summary] [Object] To provide an unnecessary resist exposure apparatus on a wafer which can shorten the exposure processing time and can perform uniform exposure processing on unnecessary resist. A light irradiation means and a light emitting end of the light irradiation means are relatively positioned with respect to the wafer so that an area irradiated by the light irradiation means is scanned on the wafer in one direction and in another direction perpendicular thereto. And means for moving,
The irradiation area LB by the light irradiation means is the one direction (X
Direction), and the contour of at least one end side of the irradiation region LB extends in an oblique direction of substantially 45 degrees with respect to one direction Lbx extending in the one direction and another side Lby extending in the other direction.
It is characterized by having a right-angled top part by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unnecessary resist exposure apparatus on a wafer, which is required for removing an unnecessary resist on a wafer in a developing process.

[0002]

2. Description of the Related Art In a manufacturing process of, for example, an IC or an LSI, a resist is applied on the surface of a semiconductor wafer such as a silicon wafer, and then a circuit pattern is exposed and developed to form a resist pattern. It is being appreciated.
Here, as a method of applying the resist, a spin coating method is generally used in which 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. Therefore, the resist is applied to the peripheral portion of the wafer, but the peripheral portion of the wafer is rarely used for the pattern formation region. This is because, when a wafer is subjected to various processing steps, the wafer is often transported and held using its peripheral portion, and pattern distortion is likely to occur in the peripheral portion, resulting in poor yield. Therefore, when the resist is a positive type resist, the peripheral portion is not exposed and therefore the resist remains on the peripheral portion even after development, and this resist contaminates peripheral equipment during the transportation and holding of the wafer, and eventually the wafer. This has been a cause of surface contamination and a reduction in yield.
Therefore, in order to remove the unnecessary resist in the peripheral portion of the wafer in the developing process, peripheral exposure is performed in which the unnecessary resist in the peripheral portion of the wafer is exposed separately from the exposure step of the circuit pattern in the pattern formation region.

On the other hand, in recent years, a wafer surface is divided by a successive movement type reduction projection exposure apparatus (stepper) so that it is divided like a grid pattern and successively exposed. The pattern formation region in this case has a square shape or a step shape.

FIG. 1 is an explanatory view showing a procedure for exposing a wafer W having a stepwise pattern formation region to an unnecessary resist applied to the outside of the pattern formation region. The exposure process of the unnecessary resist is usually performed in the order of wafer alignment, exposure process in the first quadrant, exposure process in the second quadrant, exposure process in the third quadrant, and exposure process in the fourth quadrant. The procedure will be described below with reference to FIG.

(1) Alignment of wafer W: The wafer W is aligned using an orientation flat F (orientation flat) parallel to the outer peripheral edge of the pattern formation region P. Specifically, the wafer W is rotated so that the orientation flat F and the X direction are parallel to each other (FIG. 1A). (2) Exposure processing in the first quadrant: square irradiation area L
Scan in the direction of the arrow (X → Y → X direction) [FIG.
(B)]. Hereinafter, scanning of the irradiation region is repeated while sequentially shifting the scanning path. As a result, the shaded area in FIG. 1C is exposed. (3) Exposure process in the second quadrant: The wafer W is rotated 90 degrees, and the irradiation region is repeatedly scanned in the same manner as above. As a result, the shaded area in FIG. 1D is exposed. (4) Exposure process in the third quadrant: 90 more wafers W
The irradiation area is repeatedly scanned in the same manner as above. As a result, the shaded area in FIG. 1 (e) is exposed. (5) Exposure processing in the fourth quadrant: 90 more wafers W
The irradiation area is repeatedly scanned in the same manner as above. As a result, the shaded portion (entire range outside the pattern formation area) in FIG. 1F is exposed.

FIG. 2 is a partially enlarged view (part C) of FIG.
Is an enlarged view of the irradiation area L when the rectangular irradiation area L is scanned along the outer periphery of the pattern formation area P.
The scanning locus of is shown. The numbers in parentheses in the irradiation area L represent the scanning order. In the figure, p
x and py are outer peripheral edges that extend in the X direction and the Y direction to define the pattern formation region P, respectively, and po is an intersection of the outer peripheral edge px and the outer peripheral edge py. The irradiation area L is
It has a rectangular shape with a length of 10 mm and a width of 3 mm. This irradiation area L
Is, for example, 2 in the X and Y directions as necessary.
Scanning is performed while shifting the scanning path so as to have an overlap of about mm.

[0007]

However, IC and LS
In the manufacturing process such as I, it is preferable to perform the exposure process of the unnecessary resist in the shortest possible time from the viewpoint of improving the manufacturing efficiency. Then, as a means for shortening the exposure processing time, it is conceivable to set a large irradiation area (effective irradiation area) to be scanned along the outer periphery of the pattern formation area. This is because if the irradiation area is set to be large, a wide range can be exposed in one scanning process.

However, if the irradiation area is set to be large, the variation of the light irradiation time with respect to the unnecessary resist on the wafer becomes large, so that the exposure processing is performed on all the unnecessary resist to be removed under uniform conditions. There is a problem that you can not do this. Hereinafter, the relationship between the “size of the irradiation area” and the “variation of the light irradiation time” will be described.

FIG. 3 shows a scanning locus of the irradiation area LA when the irradiation area LA having a square shape is scanned along the outer periphery of the pattern formation area. In the figure, (a)
(I) are sampling points on the wafer surface, and the distance between adjacent sampling points is 10 mm.
On the other hand, the length of one side of the irradiation area LA is 20 mm. The irradiation area LA is scanned so that the apex QA at one end thereof moves on the outer peripheral edges px, py of the pattern formation area in the direction of the arrow v, and the sampling point (a ) To (h) are irradiated with light.

FIG. 4 is a graph in which the presence or absence of light irradiation at the sampling points (a) to (h) is traced over time when the irradiation area LA shown in FIG. , Means that the sampling point is irradiated with light in the meantime). As shown in the figure, the relative ratio of light irradiation time (a: b: c: d: e: f: g: h) at the sampling point is 1: 2 :.
It becomes 2: 2: 3: 2: 2: 2. This relationship is shown in (I) of Table 1 below.

When a square irradiation area (not shown) having a side length of 30 mm is scanned instead of the irradiation area LA, the sampling point (a) is obtained by the first scanning process. ~ (I) is irradiated with light. Then, the relative ratio of the light irradiation time at the sampling point (a: b:
c: d: e: f: g: h: f) is 1: 2: 2: 3: 3:
It is 3: 4: 4: 5. This relationship is shown in (II) of Table 1 below.

[0012]

[Table 1]

As shown in Table 1 above, when scanning a rectangular irradiation area, (1) the larger the irradiation area, the greater the variation in light irradiation time, and (2) the intersection point po of the outer peripheral edge. The larger the separation distance, the longer the light irradiation time.

In the case of scanning the irradiation area LA, when the light irradiation time at the point (a) is appropriate, the light irradiation time at other sampling points, particularly near the point (e), is too long. . As a result, in the vicinity of these other sampling points, the resist reacts with excessive light (ultraviolet rays) to cause bubbling, and particles generated thereby may contaminate the wafer surface and peripheral devices.

On the other hand, in the case of scanning the irradiation area LA, when the light irradiation time at the point (e) is appropriate, the light irradiation time at other sampling points, especially near the point (a), is too short. . As a result, the amount of exposure to the unnecessary resist in the vicinity of these other sampling points becomes insufficient, and the unnecessary resist cannot be sufficiently removed, and a part thereof may remain.

As described above, it is preferable to set the irradiation area large in order to shorten the exposure processing time. However, if the irradiation area is set large, the light irradiation time (integrated exposure amount) for the unnecessary resist on the wafer is increased. (2) becomes large and the exposure process cannot be performed under uniform conditions, resulting in the above problems.

The present invention has been made based on the above circumstances. An object of the present invention is to provide an unnecessary resist exposure apparatus on a wafer which can shorten the exposure processing time and can perform uniform exposure processing on the unnecessary resist.

[0018]

In the unnecessary resist exposure apparatus on the wafer of the present invention, the light irradiation means and the irradiation area by the light irradiation means are scanned on the wafer in one direction and the other direction perpendicular thereto. Moving means for moving the light emitting end of the light irradiating means relative to the wafer, and the irradiation area by the light irradiating means is in an oblique direction of substantially 45 degrees with respect to the one direction. The contour of at least one end side of the extended irradiation region is characterized by having a right-angled apex formed by one side extending in the one direction and another side extending in the other direction.

In the unnecessary resist exposure apparatus on the wafer of the present invention, the light irradiation means includes a light source section, an optical fiber which receives light from the light source section from one end and guides the light to the other end, and other optical fibers. A lens unit connected to the end, and by blocking a part of the light traveling from the light emitting end of the lens unit to the wafer surface, at least at the top of the contour of the irradiation area by the light irradiation means. It is preferable that a light shielding means for shaping the contour is provided.

[0020]

The irradiation area by the light irradiation means is scanned in one direction and the other direction on the wafer so that the top part of the contour on the one end side moves along the outer peripheral edge of the pattern formation area. At this time, since the irradiation region scanned in one direction and the other direction extends in an oblique direction of substantially 45 degrees with respect to the one direction, it is uniform with respect to the unnecessary resist regardless of the size of the irradiation region. Various exposure processes can be performed. Here, “substantially 45 degrees” means 45 degrees ± 20
Angle ranges up to degrees are to be included.

FIG. 5 shows a scanning locus of the irradiation region LB when the irradiation region LB extending obliquely at 45 degrees with respect to the X direction is scanned along the outer periphery of the pattern formation region. In the figure, (j) to (m) are sampling points on the wafer surface. In this irradiation area LB, the apex QB on one end side is the outer peripheral edge p of the pattern formation area.
Scanning is performed so as to move in the order of p1 → p2 → po → p3 → p4 on x and py.

Here, sampling points (j) to (m)
Have different distances from the intersection point po of the outer peripheral edge, and when a rectangular irradiation region including each point is scanned, the light irradiation time to each point varies. However, when the irradiation region LB extending in the oblique direction is scanned, the light irradiation time to each point is all the same (light is irradiated to each point while the apex QB moves from p2 to p3). .

When the irradiation area LB extending obliquely at 45 degrees with respect to the X direction is scanned to scan a square irradiation area having a diagonal line from one end to the other end of the irradiation area LB. It is possible to perform the exposure processing in the same range as the above, and it is possible to shorten the exposure processing time accompanying the expansion of the processing range while maintaining the uniformity of the light irradiation conditions.

Further, the contour on one end side of the irradiation area LB is
Since it has a right-angled apex by one side (Lbx) extending in the X direction and another side (Lby) extending in the Y direction,
By scanning the irradiation area LB so that the top moves on the outer peripheral edges px, py, the corner portion of the outer peripheral edge (the portion surrounded by the points po, p2, j, p3) is surely subjected to the exposure processing. You can

[0025]

Embodiments of the present invention will be described below. FIG.
It is explanatory drawing which shows one Example of the unnecessary resist exposure apparatus of this invention. The unnecessary resist exposure apparatus of the present invention includes a light irradiation unit 10, a wafer rotating unit 20, a moving unit 30, and a wafer alignment unit 40.

The light irradiating means 10 is a means for irradiating the surface of the unnecessary resist on the peripheral portion of the wafer W (outside the pattern formation region). The light irradiating means 10 includes a lamp 11 formed of an ultra-high pressure mercury lamp, an elliptical reflecting mirror 12 that collects and reflects the light of the lamp 11, and a reflecting mirror 13 that reflects the light from the elliptic reflecting mirror 12. It has an optical fiber 14 that receives the light from the reflecting mirror 13 from one end and guides it to the other end, and a lens unit 15 that is connected to the other end of the optical fiber 14 and irradiates the wafer surface with parallel light.

Thus, the unnecessary resist exposure apparatus of this embodiment has a characteristic point in the shape of the irradiation area by the light irradiation means. FIG. 7 is an explanatory view showing the shape of the irradiation area LC by the light irradiation means 10, and the numerical values in the drawing show the dimensions (mm). In this irradiation area LC, a square irradiation area whose one side is 5.7 mm is 0.5 mm ×
4 diagonally with an overlap of 0.5 mm
It has the same shape as the one that is connected. This irradiation area L
The shape of C is formed by the end surface shape of the other end of the optical fiber 14 (the shape of the irradiation region LC is usually similar to the end surface shape of the other end). Since the optical fiber 14 is composed of a bundle of thousands of optical fibers, its end face shape can be any shape including the shape shown in FIG. 7.

The wafer rotating means 20 comprises a megatorque motor 21 and a turntable 22 on which the wafer W is placed.
The turntable 22 is provided with a vacuum suction hole (not shown) for holding the wafer W.

The moving means 30 is provided at the other end of the optical fiber 14 so that the irradiation area by the light irradiation means 10 is scanned on the wafer W in one direction (X direction) and the other direction (Y direction) perpendicular thereto. This is means for moving the light emitting end of the connected lens unit 15 relative to the wafer W. The moving means 30 is attached to the X table 31, a motor 32 that reciprocates the X table 31 in the X direction, a Y table 33, a motor 34 that reciprocates the Y table 33 in the Y direction, and is attached to the Y table 33. , And a support arm 35 that holds the light emitting end of the lens unit 15. In FIG. 6, the Y direction is the lens unit 1.
5 is a direction from the light emitting end of 5 toward the center of rotation of the turntable 22, and the X direction is a direction perpendicular to the Y direction. Therefore, the light emitting end of the lens unit 15 is connected to the X table 31.
The movement of the Y table 33 moves the peripheral portion of the wafer W.

The wafer alignment means 40 is the rotary table 2
2 is a means for detecting the mounting state of the wafer W on the wafer 2. The wafer alignment means 40 is composed of, for example, a CCD sensor and detects whether or not the orientation flat of the wafer W and the X direction are exactly parallel to each other.
The megatorque motor 21 is rotated for fine adjustment. The eccentricity error of the wafer W with respect to the rotation center of the rotary table 22 can be corrected based on the detection data of the wafer alignment means 40.

FIG. 8 shows a scanning locus of the irradiation area LC when the irradiation area LC shown in FIG. 7 is scanned along the outer periphery of the pattern forming area. In the figure,
(N), (q), (s) and (t) are sampling points on the wafer surface. In the irradiation area LC, the apex QC on one end side is the outer peripheral edges px, p of the pattern formation area.
Scanning is performed on y in the order of p5 → p6 → po → p7 → p8.

Here, sampling points (n), (q),
In (s) and (t), the distances from the intersection point po of the outer peripheral edge are different, and when the rectangular irradiation area including each point is scanned, the light irradiation time to each point varies. It will be. However, when scanning the irradiation region LC extending in the oblique direction, the light irradiation time to each point is all the same (that is, light is irradiated to each point while the vertex QC moves from p6 to p7). ). As described above, there is no variation in the light irradiation time in the range in which the irradiation region LC is scanned, and therefore, the exposure process can be performed on the unnecessary resist in such a range under uniform conditions.

By scanning the irradiation region LC extending in the oblique direction, a straight line (QC-Q) connecting the apex QC on one end side and the apex QC 'on the other end side of the irradiation region LC.
It is possible to perform the exposure processing in the same range as in the case of scanning a square irradiation area having C ′) as a diagonal line, and it is possible to expand the processing range while maintaining the uniformity of light irradiation conditions. .

Further, the contour on one end side of the irradiation region LC is
Since it has a right-angled apex by one side (Lcx) extending in the X direction and another side (Lcy) extending in the Y direction,
The corner portion of the outer peripheral edge (the portion surrounded by the points po, p6, n, and p7) can be surely exposed.

As mentioned above, the shape of the irradiation area is formed by the end surface shape at the other end of the optical fiber.
It can also be formed by using a light blocking means for blocking a part of the light from the light emitting end. FIG. 9 is a schematic explanatory view showing an example of the light shielding means. In the figure, 50 is a box-shaped light shielding means, 14 'is an optical fiber, and 15' is a lens unit. The light shielding means 50 is attached so as to cover the lens unit 15 ', and the wafer W is removed from the lens unit 15'.
Out of the light emitted to the surface of, the light which is not completely parallel light due to light interference and goes to a region other than the range to be exposed (for example, the pattern formation region P) is blocked. Reference numeral 51 denotes an opening window of the light shielding means 50, the peripheral edge of the opening window 51 is formed in a knife edge shape, and the contour of the irradiation region is formed by the peripheral edge shape of the opening window 51.

By providing the light shielding means 50 in the unnecessary resist exposure apparatus of this embodiment, the following effects can be obtained. (1) Even if the end face shape at the other end of the optical fiber 14 'is not strictly formed, a complicated contour shape in the irradiation region can be formed. (2) Since the peripheral edge of the opening window 51 is formed in the shape of a knife edge, the boundary between the area to be exposed (for example, the peripheral area) and the area that should not be exposed (for example, the pattern forming area) is clearly defined. The resist remaining after the development process has a small taper width at the boundary. (3) Since it is not necessary for the lens unit 15 'to make perfect parallel light, the lens system of the lens unit can have a simple structure.

[Experimental Example] The unnecessary resist on the wafer was exposed by using the exposure apparatus of this embodiment shown in FIG. Here, the wafer sample has a stepwise pattern region as shown in FIG. 10 and is coated with a novolac positive resist (wafer size: 150 m).
m, shot size: sx = 14.38 mm, sy = 1
4.73 mm) was used. The exposure processing operations include loading of a wafer sample, alignment of a wafer sample, exposure processing in the first quadrant, exposure processing in the second quadrant, exposure processing in the third quadrant,
The exposure process in the fourth quadrant is performed in order, and in the exposure process in each quadrant, the illuminance in the irradiation region LC is 2500 to 2600.
mW / cm ² and scanning speed of irradiation area LC is 30 mm
/ Sec. As a result, the throughput time required for the exposure processing of one upper sample was as short as 63 seconds (wafer loading time: 15 seconds, wafer alignment time: 12 seconds, exposure processing time: 36 seconds). And
When this wafer sample was developed, the unnecessary resist in the entire area outside the pattern formation area was completely removed.

[0038]

According to the unnecessary resist exposure apparatus on the wafer of the present invention, since the unnecessary resist can be uniformly exposed, and the processing range is wide in one scanning step, the exposure processing is performed. The time can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a procedure of exposing a unnecessary resist applied to the outside of a pattern formation region on a wafer surface.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is an explanatory diagram showing a scanning locus of the irradiation area LA when the irradiation area LA is scanned along the outer periphery of the pattern formation area.

FIG. 4 is a graph in which the presence / absence of light irradiation at a sampling point is traced with time when the irradiation area LA is scanned.

FIG. 5 is an explanatory diagram showing a scanning locus of the irradiation region LB when the irradiation region LB is scanned along the outer periphery of the pattern formation region.

FIG. 6 is an explanatory view showing an embodiment of the unnecessary resist exposure apparatus of the present invention.

FIG. 7 is an explanatory diagram showing a shape of an irradiation area LC formed by a light irradiation unit.

FIG. 8 is an explanatory diagram showing a scanning locus of the irradiation region LC when the irradiation region LC is scanned along the outer periphery of the pattern formation region.

FIG. 9 is a schematic explanatory diagram illustrating an example of a light shielding unit.

FIG. 10 is an illustration showing a pattern formation region in a wafer sample.

[Explanation of symbols]

 10 Light Irradiating Means 11 Lamp 12 Elliptic Reflecting Mirror 13 Reflecting Mirror 14 Optical Fiber 15 Lens Unit 20 Wafer Rotating Means 21 Megatorque Motor 22 Rotating Stand 30 Moving Means 31 X Table 32 Motor 33 Y Table 34 Motor 35 Support Arm 40 Wafer Aligning Means 50 Light-shielding means 51 Opening windows L, LA, LB, LC Irradiation area P Pattern forming area px, py Outer peripheral edge of pattern forming area

Claims (2)

[Claims] 1. A light irradiating means and a light emitting end of the light irradiating means relative to the wafer so that an area irradiated by the light irradiating means is scanned on the wafer in one direction and in another direction perpendicular thereto. The irradiation area by the light irradiation means extends in an oblique direction of substantially 45 degrees with respect to the one direction, and the contour of at least one end side of the irradiation area is the one direction. An unnecessary resist exposure apparatus on a wafer, which has a right-angled top portion formed by one side extending in the other direction and another side extending in the other direction. 2. The light irradiating means includes a light source section, an optical fiber that receives light from the light source section from one end and guides it to the other end, and a lens unit connected to the other end of the optical fiber. Light-shielding means for shaping at least the contour of at least the top of the contour of the irradiation area by the light irradiation means is provided by blocking a part of the light traveling from the light emitting end of the lens unit toward the wafer surface. The unnecessary resist exposure apparatus on a wafer according to claim 1, wherein