JPH02269564A - Grinding device for semiconductor wafer - Google Patents

Abstract

PURPOSE:To accurately measure temperatures of a cooling liquid at entrance and also at exit so to systematize the relation between grinding temperature and frequency of generation of nonconforming products by positively collecting the cooling liquid after it absorbs heat, and reducing thermal influences from other internal equipment as little as possible. CONSTITUTION:A cooling liquid introduced from an inlet 4 to the grinding face of a grinding stick 3 cools a semiconductor wafer W i.e. a material to be planed, and is guided from the stage 5 of a rotating table 2 to an outlet 9 via a communicating flow passage 6, a discharge opening 10 and a water collecting channel 8. In this case, the cooling liquid caused to flow toward the periphery of the rotating table 2 by the centrifugal force of the rotating table 2 is prevented from flowing to the outside of the stage 5 by peripheral wall 5a formed at the peripheral edge portion of the stage 5. Next, the cooling liquid is guided from the inside of the peripheral wall 5a to the outside of the rotating table 2 via the communicating flow passage 6 and the discharge opening 10. Thus, by collecting the cooling liquid into the water collecting channel 8 after it absorbs heat, the temperature of the cooling liquid is measured more accurately at the inlet 4 and outlet 9 using respective thermometers 13,14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor wafer grinding apparatus that introduces a cooling liquid to the grinding surface of a grinding wheel to cool and grind a semiconductor wafer as a workpiece.

[Conventional technology]

Conventionally, in this type of grinding device, there was no concept of measuring the grinding temperature by detecting the inlet temperature and outlet temperature of the cooling water. When cooling semiconductor wafers, which are the workpiece material, cooling water continues to flow from the inlet, and after the heat has been absorbed, it is collected by a trench pan installed at the bottom of the equipment, in order to actively collect the cooling water after it has been absorbed. There was no such structure.

[Problem to be solved by the invention]

In the grinding process of semiconductor wafers, particularly in so-called back-grinding after circuit pattern formation on GaAs semiconductor wafers and before dyne leg, the circuit pattern has already been completed, and damage to the wafer during this process poses a major problem in terms of yield.

However, it is known that during the grinding process of semiconductor wafers, structural deformation, grinding burn, grinding cracks, residual stress, etc. that occur in the semiconductor wafer are caused by the grinding heat generated by the grinding. Also,
It is well known from experience that when a grinding abnormality occurs, the grinding heat increases rapidly. For this reason, it has become necessary to measure the grinding temperature by δ1 in order to eliminate the above-mentioned problems or to discover grinding abnormalities.

When measuring the grinding temperature, it is difficult to directly contact the semiconductor wafer with a thermometer, so a simple and reliable method is to measure the temperature difference between the inlet temperature and the outlet temperature of the cooling liquid by δI11
It may be possible to calculate the grinding temperature from the relationship with the flow rate. However, the conventional grinding apparatus does not have a structure that actively collects the coolant after absorbing heat, which is inconvenient for measuring the grinding temperature. In other words, when the coolant is collected at the outlet through the drain pan at the bottom of the device, the coolant may have already dissipated a considerable amount of heat due to stagnation, or may have been thermally affected by other internal devices. Therefore, it is assumed that the measurement of the outlet temperature described above may be inaccurate.

An object of the present invention is to provide a semiconductor wafer grinding apparatus that can obtain an accurate grinding temperature by actively collecting a cooling liquid after absorbing heat.

[Means to solve the problem]

In order to achieve the above objectives, the present invention introduces a cooling liquid to the grinding surface of a grinding wheel through an outlet to cool a semiconductor wafer, which is a workpiece material, and is placed by suction at the center of a stage of a rotary table. In a grinding device for a semiconductor device that grinds from scratch, a continuous flow that communicates between a peripheral wall formed by extending the peripheral edge of a stage upward and an outlet formed on the inside of the peripheral wall and a side surface of a rotary table. a water collection gutter provided along the rotation locus of the outlet, and temperature detection means provided respectively on the upstream side of the coolant inlet and the downstream side of the outlet connected to the water collection gutter. It is characterized by:

[Effect]

The cooling liquid led from the inlet to the grinding surface of the grinding wheel cools the semiconductor wafer to be ground, and is led from the stage of the rotary table to the communication channel, the outlet, and the water collection gutter to the outlet. .

By forming the peripheral wall on the peripheral edge of the stage, the cooling liquid flowing toward the peripheral edge due to the centrifugal force of the rotary table is not obstructed by the peripheral wall and does not flow out to the outside of the stage. Furthermore, by forming a communication channel that communicates the inside of the peripheral wall with the outlet, the cooling liquid can be guided from the inside of the peripheral wall to the outside of the rotary table. Furthermore, by providing a water collection gutter along the rotation locus of the outlet, all the cooling water that has been led to the outside of the rotary table after absorbing heat can be collected in one place. If temperature detection means are provided at the inlet and the outlet, respectively, the inlet and outlet temperatures of the cooling water can be accurately measured.

〔Example〕

A case will be described in which the present invention is implemented in a grinding apparatus that grinds a semiconductor wafer to a predetermined thickness after forming a circuit pattern and before a dicing process.

As shown in FIG. 1, the semiconductor wafer W grinding apparatus] includes a rotary table 2 on which the semiconductor wafer W is placed by suction;
A grinding wheel 3 for grinding the semiconductor wafer W is provided above the rotary table 2, and the rotary table 2 is rotated once with the semiconductor wafer W placed thereon by a drive device (not shown). Further, the grinding wheel 3 is moved up and down while being rotated by a drive device (not shown). With this configuration, the semiconductor wafer W rotates slowly by itself during grinding, and the (100) surface thereof is uniformly ground to a predetermined thickness by the grinding wheel 3 that gradually descends while rotating.

On the other hand, in order to eliminate the thermal influence of the semiconductor wafer W due to grinding, the grinding heat generated by grinding is
It is removed by cooling water such as contaminated water introduced into the grinding surface S composed of the grinding wheel 3 and the grinding wheel 3.

This cooling water is introduced from the inlet 4 to the grinding surface S, and after absorbing the grinding heat on the grinding surface S,
The water passes through a communication channel 6 from above, is led to a water collection gutter 8 attached to the inside of the side table 7, and is drained out of the system through an outlet 9.

To explain this in detail, stage 5 of rotary table 2 includes:
A peripheral wall 5a formed by extending the peripheral edge portion upward, and an annular groove 5b formed inside the peripheral wall 5a along the peripheral wall 5a.
and a plurality of drainage ports 5c connected to the water collection gutter 8 in the annular groove 5b.
The cooling water flowing outward from the center due to the centrifugal force of the rotary table 2 is stopped by the peripheral wall 5a, collected in the annular groove 5b, and guided to the water collection gutter 8 side from the drain port 5C. Also,
The rotary table 2 has a communication channel 6 formed therein, which communicates each drain port 5c with a discharge port 10 formed on the side surface of the rotary table 2.

The water collection gutter 8 is installed on the side table 7 side between the rotary table 2 and the side table 7 surrounding it, and is designed to cope with the rotation of the outlet 10 that rotates together with the rotary table 2. It is formed in an annular shape.The water collection gutter 8 is also provided with a slope so that the cooling water is guided to the outlet 9.

On the other hand, an inlet pipe line 11 connected to the inlet port 4 and an outlet pipe line 12 connected to the outlet port 9 are provided with an inlet side thermometer 13 and an outlet side thermometer 14, respectively, which serve as temperature detection means. The outlet temperature can be measured.

In this way, the grinding temperature can be measured from the temperature difference between the population temperature and the outlet temperature measured with both thermometers 1.3.14 and the flow rate of the coolant, and if this is monitored, the grinding temperature The relationship between this and the frequency of occurrence of defective products such as grinding cracks and warping due to residual stress in the semiconductor wafer W can be numerically determined.

In this embodiment, as shown in the drawings, both thermometers 1314
The inlet temperature and the mouth temperature measured by A control signal is sent to the drive device of the table 2 (or the flow rate adjustment device of the cooling water), and the rotation speed and feed speed of the grinding wheel 3, the rotation speed of the rotary table 2, the flow rate of the cooling water, etc. are controlled selectively or collectively. control.

In this way, grinding defects of the semiconductor wafer W can be significantly reduced.

〔Effect of the invention〕

As described above, according to the present invention, by actively collecting the coolant after absorbing heat and minimizing the thermal influence and heat radiation from other internal devices, the temperature at the outlet as well as the population temperature of the coolant can be reduced. can be measured accurately, and has the effect of systematizing the relationship between grinding temperature and the frequency of defective products.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a semiconductor wafer grinding apparatus embodying the present invention. 1. Grinding device, 2. Rotary table, 3. Grinding wheel,
4... Inlet, 5... Stage, 5a... Peripheral wall,
6 - Communication channel, 7... Side table, 8... Water collection gutter, 9... Stream 1] 10, Co-0... Outlet, ] 3...
・Inflow side thermometer, 14...Outflow side thermometer, W...Semiconductor waeno\. Representative Patent Attorney Yoshiki Hase 6th-

Claims (1)

[Scope of Claims] Grinding of semiconductor wafers, in which a cooling liquid is introduced into the grinding surface of a grinding wheel through an outlet, and the semiconductor wafer, which is a workpiece material, is placed by suction at the center of the stage of a rotary table, and is ground while cooling it. In the apparatus, a peripheral wall formed by extending the periphery of the stage upward, a communication channel that communicates the inside of the peripheral wall with a discharge port formed on the side surface of the rotary table, and a communication flow path that extends along the rotation trajectory of the discharge port. 1. A semiconductor wafer grinding apparatus comprising: a water collection gutter provided with a water collection gutter; and temperature detection means provided respectively on the upstream side of a coolant inlet and the downstream side of an outlet connected to the water collection gutter.