JPH0632889B2 - Wafer-Automatic peripheral processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an automatic wafer outer peripheral processing apparatus for grinding a thick edge-grooved portion on the outer peripheral portion of a wafer generated in a wafer manufacturing process used for a light emitting diode or the like. Regarding

[Conventional technology]

Generally, in the outer peripheral portion of a wafer manufactured by an epitaxial method, there is a disordered portion of crystals called edge growth. Therefore, the outer peripheral portion is raised and becomes thicker, and the thickness is not constant within the wafer or between the wafers. Therefore, when shipping as a product, this portion must be removed to some extent. However, the wafer has a circular shape with a diameter of 40 to 60 mm, which is slightly deviated from the true circle, and the price per unit area is high. Therefore, do not grind evenly into a perfect circle. The product is shipped after confirming that it is within the specified thickness specifications by the user, cutting the area as small as possible with a scriber by hand, and polishing the periphery to make it smooth.

[Problems to be solved by the invention]

However, this manual cutting takes a lot of time, and when the production amount increases, the number of workers must be increased significantly, which causes an increase in production cost. In addition, it is difficult to cut because it is cleaved and cannot be shipped because it is manually cut, or because it is easy to work, it is difficult to cut less than 1 mm, and there is a tendency to cut too much, so yield loss Is 1
It reaches 5 to 20%. Therefore, it is conceivable to work with mechanical force using an existing grinding machine, but the outer circumference of a perfect circle wafer with a radius of 2.5 cm is 0.25
Assuming that grinding is performed in a uniform circular shape with a uniform cm, the yield loss will be 19%, and the yield improvement due to mechanization cannot be obtained.

Further, in order to improve the yield, it is most desirable to create a thickness map of the outer peripheral portion of the wafer in advance, or grind to the spec thickness while monitoring the thickness,
The equipment becomes very complicated.

The present invention has been made in view of such circumstances, utilizing the fact that there is a positive correlation between the maximum thickness of each outer periphery of the wafer and the amount of grinding, by measuring the maximum thickness of each outer periphery of the wafer, the visual and manual An object of the present invention is to provide an automatic wafer outer periphery processing apparatus that can control the grinding amount based on the measured value without depending on the intuition to improve the yield and reduce the production cost.

[Means for solving problems]

Therefore, the wafer automatic outer peripheral processing apparatus of the present invention, the measuring means for measuring the maximum thickness at each position separated by a predetermined interval of the wafer outer peripheral portion, the arithmetic means for calculating the grinding amount based on the measurement result, the maximum thickness or A storage means for storing a grinding amount, and a wafer grinding means which is drive-controlled so as to change any one parameter of a rotation speed, a pressing force on the wafer, and a contact time on the wafer according to the grinding amount are provided. Is characterized by.

[Action]

In the wafer automatic outer periphery processing apparatus of the present invention, the maximum thickness of each part of the wafer outer periphery is measured at predetermined intervals, the grinding amount is calculated from the measurement result at each position, and the measurement result or the calculation result is stored in the memory and calculated. The outer periphery of the wafer is ground according to the grinding amount, and based on the maximum thickness of the edge gloss, the grinding part is driven and controlled so that the thick part increases the grinding amount and the thin part decreases the grinding amount. The wafer grinding amount can be reduced.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the wafer, FIG. 2 is a diagram showing the relationship between the maximum thickness of the edge growth and the stock removal, FIG. 3 is a diagram showing thickness measurement points on the outer periphery of the wafer, and FIG. 4 is each thickness measurement point and grinding. FIG. 5 is a diagram showing the relationship of the grindstone rotation speed, FIG. 5 is a diagram showing a wafer processing step, and FIG. 6 is a diagram showing a configuration of a wafer grinding apparatus. In the figure, 1 is a wafer to be ground, 2 is a substrate, 3 is an epitaxial layer, 4 is an orientation flat, 5 is an edge gloss, T _{1 to} T ₁₁ are maximum thickness measurement points, 6 is a center point of the orientation flat, and 7 is grinding. Starting point,
8 is a grinding end point, 9 is a thickness measurement stage, 10 is a storage device, 11 is an arithmetic unit, 12 is a grinding stage, 13 is a grindstone, 14 is a cleaning / drying process, 15 is a thickness confirmation stage,
Reference numeral 16 is an arm, 17 is an arm support portion, and 18 and 19 are valves.

In the figure, the maximum thickness d _max (μm) of the edge gloss generated on the outer peripheral portion of the wafer and the machining allowance (mm) when grinding to meet the specifications with the smallest possible grinding amount are shown in the cross section of the wafer. When measured by a micrograph and plotting the relationship, an almost positive correlation is seen as shown in FIG. Therefore, if the maximum thickness of the edge gloss is measured and the amount of grinding is proportional to this, it is possible to perform grinding that meets the specifications with the least amount of grinding possible.

By the way, when performing grinding with a grindstone, if other parameters such as pressing force and contact time are constant, the grinding amount is proportional to the rotation speed of the grindstone, so the maximum thickness of each point on the wafer is measured and If the grinding is performed at the corresponding rotational speed of the grindstone, it is possible to perform grinding that meets the specifications with the smallest possible grinding amount.

Therefore, as shown in FIG. 3, except for the portion of the orientation flat 4 which is not ground (left and right χ ° (range of about 0 to 30 °) with reference to the center 6 of the figure), for example, T ₁ to T at regular intervals. _{The 11} measurement points are set, the maximum thickness is measured, and the rotational speed of the grindstone is determined as shown in FIG. 4 according to the maximum thickness of each measurement point.

Therefore, the grinding step will be described. The wafer 1 supplied by a belt (not shown) is placed on the thickness measuring stage 9 and the center is aligned with the orientation flat 4 of the wafer 1 as a reference. And on the center line of orientation flat 4, orientation flat 4
The point on the opposite side to T ₁ is T _1, and for example, T _{2 to} T _{11 at} every 30 °
(However, the reference orientation flat portion is excluded) is set, and the maximum thickness of the portion within 3 mm of the outer circumference of T _{1 to} T ₁₁ is measured by the contact method. The measured value of the maximum thickness at T _{1 to} T ₁₁ is stored in the storage device 10. next,
The wafer 1 is placed on the grinding stage 12, the center is aligned with the orientation flat 4 as a reference, as in the case of being placed on the thickness measuring stage 9, the wafer 1 is fixed by a vacuum chuck or the like, and rotated at a predetermined speed. Grinding start point, and from the angle χ ° in the center of the orientation flat 4 to the end of the orientation flat 4 performs the order of _{T 7, T 8, T 9} ......... T 6, the grindstone 13
The rotation speeds of T _{1 to} T previously stored in the storage device 10
Based on the maximum thickness at _11, determined by the arithmetic unit 11, a ₇ as shown in FIG. _{4, a 8, a 9 ......... a} 6 to alter. At this time, between the points T _{1 to} T ₁₁ , if the rotation speed can be suddenly changed, the outer peripheral shape becomes uneven or chipping occurs, so in order to prevent such a trouble,
The rotation speed is changed linearly between the points as shown in the figure.
Thus, the wafer is rotated until the grinding end point (360-χ) ° is ground, and the grinding is completed. Even if the measured thickness of the edge gloss 5 is smaller than the specification, the crystal in the peripheral portion of the wafer 1 is often disordered, so a certain amount of grinding is performed. Therefore, the rotation speed of the grindstone 13 also becomes a certain value or more. Further, instead of storing the measured value, the calculation result may be stored.

It should be noted that the grinding with the grindstone 13 is performed while pouring water, and the grinding stage 12 and its peripheral parts are contaminated, so it is desirable to perform automatic cleaning at regular intervals.

Next, water is sprayed onto the wafer 1 to wash shavings generated during grinding, and the wafer 1 is dried 14 with nitrogen gas or the like. After that, the wafer 1 is placed on the thickness confirmation stage 15, the stage is rotated, and the maximum thickness is measured over the entire circumference of the portion within 2 mm of the outer peripheral portion by a contact method or the like, and it is checked whether the maximum thickness is smaller than the specification. If it passes, it will be shipped.

As a grinding apparatus, as shown in FIG. 6, a grindstone 13 rotatably driven by a driving means such as a motor (not shown) is applied to the outer peripheral portion of the wafer 1 with a constant pressing force by adjusting valves 18 and 19. Grinding is performed by bringing them into contact. At this time, the grindstone 13 is supported by the arm 16 and the wafer 1
Is rotated once while being fixed on the grinding stage 12 by a vacuum chuck, and the wafer 1 is rotated once to complete the grinding.

Instead of controlling the rotation speed, the valves 18, 19 may be adjusted based on the measured values of the respective maximum thicknesses to change the pressing force of the grindstone 13 on the wafer 1 to control the grinding amount. The amount of grinding may be controlled by changing the contact time with respect to the wafer.

〔The invention's effect〕

As described above, the present invention focuses on the fact that the maximum thickness of the edge gloss outer peripheral portion produced on the wafer is proportional to the machining allowance in grinding, and measures the maximum thickness of the edge gloss outer peripheral portion to determine the maximum edge gloss. Since the amount of grinding is controlled based on the thickness, it is possible to perform grinding that meets the desired specifications with the least amount of grinding possible without relying on visual or manual intuition, improving yield. ,
The production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of the wafer, FIG. 2 is a diagram showing the relationship between the maximum thickness of the edge gloss and the stock removal, FIG. 3 is a diagram showing the outer peripheral thickness measurement points of the wafer, and FIG. 4 is each thickness measurement point. FIG. 5 is a diagram showing the relationship of the grinding wheel rotation speed, FIG. 5 is a diagram showing a wafer processing step, and FIG. 6 is a diagram showing a configuration of a wafer grinding apparatus. 1 ...... grinding target wafer, 2 ...... substrate, 3 ...... epitaxial layer, 4 ...... orientation flat, 5 ...... edge growth, T ₁ through T ₁₁ ...... thickness measuring points, 6 ...... orientation flat of the center point, 7 ... Grinding start point,
8 ... Grinding end point, 9 ... Thickness measurement stage, 10 ...
Storage device, 11 ... Computing device, 12 ... Grinding stage,
13 …… Whetstone, 14 …… Washing / drying stage, 15 ……
Thickness confirmation stage, 16 ... arm, 17 ... arm support, 18,19 ... valve

Claims (3)

[Claims] 1. A measuring means for measuring the maximum thickness at each position on the outer peripheral portion of the wafer separated by a predetermined distance, a calculating means for calculating a grinding amount based on the measurement result, and a storing means for storing the maximum thickness or the grinding amount. And a wafer grinding means which is drive-controlled so as to change any one parameter of a rotation speed, a pressing force on a wafer, and a contact time on a wafer according to the grinding amount. 2. The grinding means is controlled so that the maximum thickness linearly changes from the immediately preceding measuring point to the immediately following measuring point between the positions separated by the predetermined distance. A wafer automatic peripheral processing apparatus according to the first aspect of the invention. 3. The automatic wafer outer periphery processing apparatus according to claim 1, wherein when the maximum thickness is smaller than a predetermined value, the grinding means is driven and controlled so that the grinding amount becomes constant. .