JPH04346228A - Method for grinding semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide a method for performing finish grinding of a semiconductor wafer requesting high quality, high and accurate flatness, large diameter and extremely small thickness by using an automatic plane grinding machine. CONSTITUTION:A chuck mechanism 2, a semiconductor wafer W, a cup wheel type grinding whetstone 3, and a spindle axis 6 with an elevation means 4 are provided, the cup wheel type grinding whetstone 3 is lowered to the semiconductor wafer W at an extremely slow speed by the elevation means 4 for finish- grinding, elevation is stopped for a certain amount of time after grinding is completed, and at the same time the semiconductor wafer W is raised at an extremely slow speed when leaving the cup wheel type grinding whetstone 3. Thus a grinding machining can cope with a semiconductor wafer W which needs to be of large diameter, and extremely small thickness, and which has a brittleness and furthermore the grinding whetstone makes no mark on a semiconductor wafer upon separating from the wafer.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for grinding semiconductor wafers using an automatic surface grinder, and more specifically, the present invention relates to a method for grinding semiconductor wafers using an automatic surface grinder. The present invention relates to a method for high-quality finish grinding with high performance.

0002

[Prior art and its problems] In recent years, this type of semiconductor wafer has been required to have a highly accurate finished surface, as well as to be ultra-thin and enlarged in diameter due to product yield issues. Automatic grinding machines that grind semiconductor wafers are also required to have a mechanism that can handle higher precision finished surfaces, ultra-thin surfaces, and larger diameters, which is an urgent task.

[0003] Conventional grinding methods involve dividing the predetermined cutting allowance of the semiconductor wafer into several stages, setting the depth of cut, and lowering the grinding wheel for grinding, or grinding by lowering the grinding wheel, which is set to a constant depth of cut. This method involves cutting horizontally from the outer circumference of one side of the semiconductor wafer to the other side.Brittle semiconductor wafers that require high quality, ultra-thinness, and enlargement in diameter are prone to cracking, chipping, or , the grinding process leaves damage and cannot be called efficient, and the grinding surface of the cup wheel type grinding wheel must be lifted and removed from the top surface of the semiconductor wafer immediately after the grinding process is performed. Therefore, due to the elasticity of the cup wheel type grinding wheel itself, the elasticity of the spindle shaft, the support strength of the spindle shaft, the precision of the bearing, etc., a cup wheel type grinding wheel is formed on the top surface of the semiconductor wafer. When the grinding surface of the grinding wheel detaches, a slight linear trace remains, which hinders the improvement of finishing accuracy such as thickness, parallelism, flatness, and surface roughness of semiconductor wafers after grinding. .

[Purpose of the invention]

[0004] In view of the above-mentioned reasons, the present invention has been made as a result of intensive research to solve the above-mentioned problems, and is capable of sufficiently coping with the improvement of quality, ultra-thinness, and diameter expansion of semiconductor wafers.
We have created a grinding method that improves finish accuracy in terms of thickness, parallelism, flatness, surface roughness, etc. by preventing separation marks from the grinding wheel that form on the top surface of mirror-finished semiconductor wafers. The purpose is to provide

[Structure of the invention]

The configuration of the present invention includes a chuck mechanism, a semiconductor wafer, a cup wheel type grinding wheel, and a spindle shaft supported on a base so that it can be raised and lowered by interposing a lifting means, and the rotating shaft of the chuck mechanism Using an automatic surface grinder in which the core and the rotational axis of the spindle shaft are approximately parallel to each other, and the grinding surface of the cup wheel type grinding wheel is arranged at a constant interval passing through the center point of the semiconductor wafer, The cup wheel type grinding wheel is lowered onto the semiconductor wafer at a very low speed by the lifting means to perform final grinding, and after finishing the grinding, the lifting and lowering is stopped for a certain period of time at the lowest position, and the semiconductor wafer and the cup wheel type grinding wheel are separated. It is meant to be raised at a very slow rate.

[Embodiments of the invention]

The semiconductor wafer grinding method of the present invention, which achieves the above object, will be explained with reference to the drawings of the embodiments.

FIG. 1 is a schematic plan view for explaining an automatic surface grinder according to an embodiment of the present invention, and FIG. 2 is a schematic side view for explaining the present invention.

The present invention provides a semiconductor wafer W for an automatic surface grinding machine.
Regarding the grinding method of semiconductor wafer W.
This method relates to a method for mirror-finishing the upper surface by stopping the lifting and lowering for a certain period of time after grinding is completed, and raising the grinding wheel at a very slow speed when separating the semiconductor wafer W and the cup wheel type grinding wheel 3. A chuck mechanism 2 that is fitted onto the table 1 and rotates by itself, and a semiconductor wafer W that is vacuum-adsorbed to the chuck mechanism 2.
, a cup wheel type grinding wheel 3 disposed above for mirror-grinding the upper surface of the semiconductor wafer W, and a cup wheel type grinding wheel 3 fixed to the lower end and movable up and down with a lifting means 4 interposed therebetween. and a spindle shaft 6 which is supported on the base body 5 and rotates by itself, and the rotation axis a of the chuck mechanism 2 is
and the rotational axis b of the spindle shaft 6 are substantially parallel to each other, and the grinding surface of the cup wheel type grinding wheel 3 is arranged at a constant interval so as to pass through at least the center point of the semiconductor wafer W. Using a disk, the cup wheel type grinding wheel 3 is lowered to the upper surface of the semiconductor wafer W at a constant slow speed by the elevating means 4 to perform finish grinding to remove a set amount of cutting allowance, and after finishing the grinding, the set amount of cutting allowance is completed. The vertical movement is stopped for a certain period of time at the lowest position of the semiconductor wafer W, and when the upper surface of the semiconductor wafer W and the grinding surface of the cup wheel type grinding wheel 3 are separated, the vertical movement is raised at a very slow speed by the vertical movement means 4.

To specifically explain the operating state of a semiconductor wafer W, which is normally an object to be ground in this type of automatic surface grinding machine, as shown in FIG. Semiconductor wafers W are guided onto the delivery-side conveyor belt 12 provided on the lower side immediately before the delivery-side cartridge 11 which is stored in a ladder-shaped partition frame and is movable up and down and whose front side is open. The semiconductor wafer W placed on the delivery-side conveyor belt 12 is attracted to a suction pad 14 provided at the tip of a delivery-side reversing arm 13 located below and capable of reversing, and the delivery-side reversing arm 13 is reversed. The semiconductor wafer W is then placed on the preposition 15 by vacuum suction on the lower surface of a suction pad 17 provided at the tip of a wafer transfer arm 16 which can be raised and lowered and has a rotation mechanism in the horizontal direction. It is transferred onto the rotary table 1 of the board.

The rotary table 1 is equipped with a plurality of self-rotating circular vacuum suction chuck mechanisms 2, and the rotary table 1 automatically rotates and stops intermittently, and when the stop position is reached. Then, the spindle shaft 6 to which the cup wheel type grinding wheel 3 is fixed descends from above to the tip of each chuck mechanism 2, and the upper surface of the semiconductor wafer W is ground by a preset cutting allowance on each chuck mechanism 2. It is something.

The semiconductor wafer W is transferred to the wafer transfer arm 1.
At 6, the semiconductor wafer W is accurately set on the chuck mechanism 2 and vacuum-adsorbed onto the chuck mechanism 2, and the semiconductor wafer W is moved to the next processing position by the rotation of the rotary table 1 together with the chuck mechanism 2. When the grinding is completed to the required thickness at each processing position, the spindle shaft 6 is raised, and the rotary table 1 rotates again to carry it to the next stop position. Another spindle shaft 6 is lowered to perform grinding one after another, and then is cleaned at a cleaning position, and the rotary table 1 is rotated intermittently and endlessly while maintaining a fixed stop time.

After the semiconductor wafer W is subjected to final finishing grinding and cleaning, the suction pad 19 of the wafer transfer arm 18 is moved by the reverse action of the wafer transfer arm 16 described above.
It is adsorbed, washed and dried by a washing and drying device 20, placed on a storage conveyor belt 23 by a suction pad 22 provided on a reversing arm 21 on a storage side, and a ladder-shaped partition provided on a side wall inside a cartridge 24 on a storage side. By raising and lowering the cartridge into the frame, each item is again collected and stored.

The automatic surface grinding machine embodying the present invention is constructed as described above, and the above-mentioned operations are automatically and regularly repeated, and the semiconductor wafers W delivered from the delivery cartridge 11 are sequentially moved to movable positions. The material is guided to the surface, ground, cleaned, and stored.

That is, the rotary table 1 of the automatic surface grinding machine repeatedly rotates and stops intermittently, and the plurality of chuck mechanisms 2 are fitted into each other with their top surfaces protruding. Each of the chuck mechanisms 2 shares the rotational drive source of the rotary table 1 and rotates independently, and a vacuum pump is operated by a ventilation system passing through the rotary table 1. When the semiconductor wafer W is firmly vacuum-adsorbed onto the upper surface of the chuck mechanism 2 by the vacuum mechanism, a cup wheel type grinding wheel 3 fixed to the lower end of the spindle shaft 6 from above the chuck mechanism 2 is attached. It descends and starts grinding.

The spindle shaft 6 is moved to the base body 5 by means of elevating and lowering the means 4.
The grinding wheel 3 is supported in such a way that it can be raised and lowered freely, and is self-rotating by a drive source such as an electric motor M, and the cup wheel type grinding wheel 3 is also rotated accordingly. As shown in FIG. 2, an electric motor M as a drive source is assembled on a base 5, and a rotation adjustment mechanism 4 is attached to a rotation shaft 4a of the electric motor M.
A spindle shaft 6 is provided with a bar-shaped thread 4c interposed therebetween, and a guide 4d having a female thread that engages with the thread 4c.
Therefore, it does not matter if a mechanical mechanism, pneumatic pressure, hydraulic pressure, etc. are used, as long as the fine speed adjustment is possible without damaging the fragile semiconductor wafer W.

The rotation axis a of the chuck mechanism 2 and the rotation axis b of the spindle shaft 6 are maintained in a substantially parallel state, that is, the upper surface of the semiconductor wafer W and the grinding surface of the cup wheel type grinding wheel 3. Both are in a nearly parallel state,
The substantially parallel state means that the grinding surface of the cup wheel type grinding wheel 3 and the top surface of the semiconductor wafer W are slightly inclined to reduce the grinding resistance and to avoid leaving small protrusions on the center of rotation of the semiconductor wafer W. The spindle shaft 6 is slightly oscillated at the center of each rotating axis a. so that the grinding surface of the cup wheel type grinding wheel 3 passes through at least the center point of the semiconductor wafer W. b are arranged at regular intervals to keep the circumferential speed constant in the interference region during grinding between the grinding surface of the cup wheel type grinding wheel 3 and the upper surface of the semiconductor wafer W to be ground.

The cup wheel type grinding wheel 3 is lowered to the upper surface of the semiconductor wafer W at a constant slow speed by the elevating means 4 to finish grinding a set amount of cutting stock, and after the grinding is finished, the set amount of cutting stock is finished. The lifting and lowering is stopped for a certain period of time at the lowest position of the grinding wheel, and the amount of deflection due to the elasticity of the cup wheel type grinding wheel itself, the elasticity of the spindle shaft, the support strength of the spindle shaft, the accuracy of the bearing, etc. is restored, and When separating the upper surface of the semiconductor wafer W from the grinding surface of the cup wheel type grinding wheel 3, the elevating means 4
By raising the semiconductor wafer W at a very slow speed, there are no separation marks left on the top surface of the semiconductor wafer W in the past.
Semiconductor wafers W that require higher precision, larger diameter, and ultra-thinness
The method of the present invention is applied in the final finish grinding process, but in order to obtain a more accurate finished surface and to balance the time of all processes, the method of the present invention is applied during the entire grinding process. It is okay to do so.

Although the method of the present invention has been described above with respect to a rotating rotary table, the present invention is not limited thereto, and can be applied to a chuck mechanism such as an indexing type index table.

[0019]

[Effects of the Invention] The effects of the present invention are achieved by the above-mentioned configuration.
By raising and lowering the spindle shaft of an automatic surface grinding machine at a very slow speed using a lifting means, grinding is performed, stopping at the lowest position for a certain period of time, and raising the shaft at a very slow speed. It is possible to handle the grinding of semiconductor wafers that are required and have brittle characteristics.In addition, it is possible to prevent the separation marks of the grinding wheel from being formed on the mirror surface of the semiconductor wafer after final grinding, and it can be applied over the entire surface of the semiconductor wafer. This is an innovative grinding method that improves the precision of the finished surface, is highly reliable, and can produce extremely significant effects.

[0020]

[Brief explanation of drawings]

FIG. 1 is a schematic plan view for explaining an automatic surface grinder according to an embodiment of the present invention.

FIG. 2 is a schematic side view of the present invention.

[0021]

[Explanation of symbols]

W Semiconductor wafer a Rotation axis of chuck mechanism b
Spindle shaft rotation axis 1 Table 2 Chuck mechanism 3 Cup wheel type grinding wheel 4
Lifting means 4a Rotation shaft 4b Rotation adjustment mechanism 4c Thread 4d Guide 5 Base 6 Spindle shaft M Electric motor 11 Sending-side cartridge 12 Sending-side conveyor belt 13 Sending-side reversing arm 14 Suction pad 15 Pre-position 16 Wafer transfer arm 17 Suction pad 18 Wafer Transfer arm 19 Suction pad 20 Washing/drying device 21 Storage side reversing arm 22 Suction pad 23 Storage side conveyor belt 24 Storage side cartridge

Claims (1)

[Claims] 1. A chuck mechanism that is fitted onto a table and rotates on its own, a semiconductor wafer that is vacuum-adsorbed to the chuck mechanism, and a cup wheel type disposed above for mirror-grinding the top surface of the semiconductor wafer. A grinding wheel, a spindle shaft which fixes the cup wheel type grinding wheel to the lower end and is supported on a base so as to be able to rise and fall freely with a lifting means interposed therebetween, and which rotates by itself, and the rotational axis of the chuck mechanism and the spindle shaft The semiconductor wafer is ground using an automatic surface grinder, which is disposed substantially parallel to the rotation axis of the semiconductor wafer and with the grinding surface of the cup wheel type grinding wheel having a constant interval passing through at least the center point of the semiconductor wafer. A cup wheel type grinding wheel is lowered to the upper surface at a constant slow speed by the lifting means to finish grinding a set amount of cutting allowance, and after finishing grinding the set amount of cutting allowance, the lifting and lowering is stopped for a certain period of time at the lowest position. With,
A method for grinding a semiconductor wafer, characterized in that when the upper surface of the semiconductor wafer and the grinding surface of the cup wheel type grinding wheel are separated, the lifting means raises the grinding wheel at a very low speed.