JP2013069842A - Wet etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a wafer immediately when it is different from a desired state, by monitoring the thickness and shape of the wafer during the wet etching process.SOLUTION: A wet etching apparatus 1 drops etchant 3b from a supply nozzle 3 above the center of a wafer 6 held on a rotary table 2 and spreads the etchant 3b entirely on one surface of the wafer 6 by rotating the rotary table 2 at a predetermined rotational speed. The wafer thickness is measured by means of a thickness gauge 4, and the dropping amount of the etchant 3b is controlled based on the measurement results. When the thickness and shape of the wafer 6 are different from those in the desired state during wet etching proces, they can be corrected immediately. Consequently, re-etching for correcting insufficient etching and discarding of a wafer due to excessive etching can be prevented.

Description

  The present invention relates to an etching apparatus that performs wet etching on a surface of a workpiece.

  In the manufacturing process of semiconductor devices, after forming multiple devices such as ICs and LSIs partitioned by grid-like division lines on the surface of the wafer, the back surface of the wafer is ground and processed to the desired thickness. Then, individual semiconductor chips are manufactured by cutting along the planned dividing lines. By the way, an uneven part is formed by grinding on the back surface of the wafer that has undergone the back grinding process, and if this uneven part remains, it becomes a factor of reducing the bending strength of the device. Therefore, in order to remove the uneven portion, a wet etching apparatus that performs wet etching on the wafer is used.

  In such a wet etching apparatus, the thickness of the wafer, the flatness of the wafer, the thickness variation, and the like are measured with respect to the etched wafer. Then, a wafer that is subsequently put into a wet etching apparatus is corrected based on the measurement result so that its thickness and shape reach desired values (for example, see Patent Documents 1 and 2 below).

Japanese Patent No. 3620528 JP 2007-208074 A

  However, in the wet etching apparatus as described above, since the thickness and shape of the wafer cannot be corrected during the wet etching process, the wafer is etched again in order to correct the etching shortage, or due to excessive etching. There is a problem that the wafer is discarded.

  The present invention has been made in view of the above circumstances. During the wet etching process, the thickness and shape of the wafer are monitored, and if the wafer is different from the desired state, the wafer is immediately corrected. Aim.

  The present invention relates to a spin-type wet etching apparatus that includes at least a nozzle for dropping an etching solution, a table that can hold and rotate a wafer, and a thickness measuring device that can measure the thickness of a wafer being processed. While dropping the etching solution from the nozzle onto one surface of the wafer above the center of the wafer and rotating the table at a predetermined rotational speed, the etching solution is spread over the entire surface of the wafer and wet etching is performed. The thickness of the film is measured to control the dropping amount of the etching solution.

  In addition, the thickness measuring device is capable of reciprocating in the radial direction between the center and the outer peripheral portion of the wafer, and recognizes the shape of the wafer from the wafer thickness measured by the thickness measuring device, and the wafer A control unit that controls the position where the etching solution is dropped based on the thickness of the wafer captured by the shape recognition unit and the amount of the etching solution dropped, and the control unit monitors the shape of the wafer and The wet etching process is controlled according to the above.

  In the present invention, the thickness measuring device can reciprocate in the radial direction from the wafer center to the outer periphery, and the wafer shape recognition unit that recognizes the wafer shape from the wafer thickness measured by the thickness measuring device and the wafer shape recognition unit If the thickness and shape of the wafer differs from the desired state during the wet etching process because it has a control unit that controls the position where the etching solution is dropped and the amount of the etching solution dropped based on the thickness of the wafer. You can make corrections immediately. Therefore, it is possible to prevent the wafer from being etched again to correct the shortage of etching, or the wafer to be discarded due to excessive etching.

It is a perspective view of a wet etching apparatus. It is sectional drawing which shows the operation example of a wet etching apparatus.

  A wet etching apparatus 1 shown in FIG. 1 is an example of a spin-type etching apparatus that holds a workpiece on a rotatable table and drops an etching solution onto the rotating workpiece to perform etching. The wet etching apparatus 1 includes at least a supply nozzle 3 for dropping an etching solution, a rotary table 2 that can hold and rotate a workpiece, and a thickness measuring device 4 that measures the thickness of the workpiece being processed. ing.

  The rotary table 2 shown in FIG. 1 has a disk shape and is supported by a support portion 21 shown in FIG. As shown in FIG. 2, the upper surface of the turntable 2 is provided with a holding unit 20 that holds a workpiece. The rotary table 2 is connected to a rotary shaft 22 connected to the motor 5 via a support portion 21, and the motor 5 is disposed in a motor housing 50 positioned below the rotary table 2 so that the motor 5 is driven. Rotate the rotary shaft 22 and rotate the rotary table 2 together.

  A supply nozzle 3 shown in FIG. 1 is attached to one end of an arm 30 that can pivot in the directions of arrows A1 and A2 in order to drop an etching solution onto a workpiece, and is arranged in the vicinity of the turntable 2. A rotating shaft 31 erected in the vicinity of the turntable 2 is connected to the other end of the arm 30. The supply nozzle 3 can swing in the directions indicated by arrows A1 and A2 as the arm 30 is swung by the rotation of the rotary shaft 31. That is, the supply nozzle 3 can reciprocate in the radial direction between the center of the workpiece and the outer periphery of the workpiece.

  As shown in FIG. 2, the supply nozzle 3 is connected to the chemical solution source 33 via an adjustment unit 32 including a valve for adjusting the dropping position and the dropping amount of the etching solution, and the etching solution 3 b sent from the chemical solution source 33. Can be dropped from the supply port 3a.

  A thickness measuring device 4 shown in FIG. 1 is attached to one end of an arm 40 that can pivot in the directions of arrows B1 and B2 in order to inspect the thickness of a workpiece, and is disposed in the vicinity of the turntable 2. A rotating shaft 41 erected in the vicinity of the turntable 2 is connected to the other end of the arm 40. The thickness measuring device 4 can swing in the directions indicated by arrows B1 and B2 by the arm 40 swinging by the rotation of the rotating shaft 41. That is, similarly to the supply nozzle 3, the thickness measuring device 4 can reciprocate in the radial direction between the center of the workpiece and the outer peripheral portion. Thereby, the thickness of the wafer 6 during the wet etching process can be monitored.

  The thickness measuring device 4 has a function of irradiating a laser beam having a predetermined frequency downward to obtain the thickness of the workpiece from the waveform of the interference wave between the reflected light on the surface of the workpiece and the reflected light on the back surface. . A lens 4a is provided at the lower end of the thickness measuring device 4, and a laser light source (not shown) is provided above the lens 4a. As shown in FIG. 1, the thickness measuring device 4 includes a shape recognition unit 42 that recognizes the thickness and shape of the workpiece. A control unit 43 shown in FIG. 1 is provided to control the operation of the wet etching apparatus 1 according to the present embodiment, and includes a memory and a CPU that store measurement results transmitted from the shape recognition unit 42. A threshold value for the thickness of the wafer W is set in advance. It is connected to the adjustment part 32 which adjusts the dripping amount of etching liquid.

  The shape recognition unit 42 transmits the measurement result to the control unit 43 after measuring the thickness of the workpiece, and the control unit 43 drops a necessary etching solution on the back surface of the workpiece based on the measurement result. The amount of etching solution dropped is controlled. In this way, the thickness measuring device 4 can monitor the shape change such as the thickness of the workpiece, the flatness of the back surface of the workpiece, and the variation in thickness (uneven portions) during the etching process of the workpiece.

  Hereinafter, an operation example of the wet etching apparatus 1 configured as described above will be described. Note that the wafer 6 illustrated in FIG. 1 is an example of a workpiece to be wet-etched.

  First, as shown in FIG. 2, the front surface 6 </ b> B is held on the upper surface of the holding unit 20 of the turntable 2 with the back surface 6 </ b> A of the wafer 6 to be processed by wet etching facing upward. After the wafer 6 is held on the upper surface of the holding unit 20, the motor 5 starts to drive, rotates the rotary shaft 22 and rotates the rotary table 2 at a predetermined rotational speed. Then, as shown in FIG. 2, the supply nozzle 3 is positioned above the vicinity of the center of the wafer 6 by the swing of the arm 30, and the etching solution 3b supplied from the chemical solution source 33 is dropped onto the back surface 6A of the rotating wafer 6. .

  The etching solution 3b spreads toward the outer peripheral portion of the wafer 6 due to the centrifugal force generated in the rotating wafer 6, and spreads over the entire back surface 6A of the wafer 6. After the etching solution 3 b is dropped onto the wafer 6, the supply nozzle 3 retracts from the vicinity of the center of the wafer 6 with the arm 30 swinging in the direction of the arrow A <b> 1 or A <b> 2.

Further, the thickness of the wafer 6 is measured by the thickness measuring device 4 during the wet etching process. Specifically, the rotating shaft 41 shown in FIG. 1 starts rotating, the arm 40 is swung in the directions of arrows B1 and B2, and laser light for detecting the thickness is irradiated toward the wafer 6 from the thickness measuring device 4. Is done. At this time, the thickness measuring instrument 4 is positioned at a position away from the wafer 6 by about 10 cm. Further, in order to prevent the lens 4a from being soiled by the splash of the etching solution 3b, a predetermined amount of N ₂ gas (nitrogen gas) is blown onto the lens 4a during the thickness measurement.

  When the rotating wafer 6 is irradiated with laser light, it is reflected on the back surface 6A and the front surface 6B and returns to the thickness detector 4. The thickness detector 4 determines the thickness of the wafer 6 based on the two interference waves. Further, as described above, since there is a possibility that the thickness of the wafer 6 may vary due to the uneven shape on the back surface 6 </ b> A, the thickness detector 4 scans a plurality of locations while swinging above the wafer 6. . Thereby, the variation in the thickness of the wafer 6 can be recognized for each position on the coordinates, and information for adjusting the dropping position and the dropping amount of the etching solution can be obtained.

  The shape recognition unit 6 shown in FIG. 1 transmits the information to the control unit 43 after acquiring the thickness information of the wafer 6. If the thickness of the wafer 6 is not a desired value, the control unit 43 immediately corrects the thickness of the wafer 6 sent from the thickness detector 4 to correct the preset thickness of the wafer 6. Based on the above, a signal for controlling the dropping amount of the etching solution 3b is transmitted to the adjusting unit 32. Thereafter, in the thickness detector 4, the arm 40 swings in the direction of the arrow B <b> 1 or B <b> 2 and retracts from above the wafer 6.

  When a signal is transmitted to the adjustment unit 32, the arm 30 shown in FIG. 1 swings, and the supply nozzle 3 moves to the dropping position with respect to the wafer 6. Here, the adjustment unit 32 adjusts the dropping amount of the etching solution 3 b based on the signal from the control unit 43 and sends it to the supply nozzle 3, and the supply nozzle 3 drops the etching solution 3 b on the dropping position of the wafer 6. In addition, the control part 43 controls the dripping position of the etching liquid 3b by coordinate information, for example.

  When the etching solution 3b is dropped at all dropping positions, the supply nozzle 3 is retracted from above the wafer 6 to the outer peripheral side, and the thickness detector 4 detects the thickness of the wafer 6 again. Then, the inspection by the thickness detector 4 and the dropping of the etching solution 3b by the supply nozzle 3 are repeated until the thickness of the wafer 6 reaches a desired value. Thus, when the thickness of the wafer 6 reaches a desired value, a series of operations of the wet etching apparatus 1 is completed.

  As described above, in the wet etching apparatus 1, the thickness measuring device 4 measures the thickness of the wafer, and based on the measurement result, the amount of the etching solution can be controlled. If the shape is different from the desired state, it can be corrected immediately. Therefore, it is possible to prevent the wafer from being etched again in order to correct the etching deficiency or to be discarded due to excessive etching.

  Note that the etching solution used in the wet etching apparatus 1 according to the present embodiment is not limited to a specific chemical solution.

  In the case where the thickness detector does not swing, the thickness detector may be configured to measure the thickness of the entire wafer surface so that the back surface of the wafer can be captured with a single scan, for example.

1: wet etching apparatus 2: rotating table 20: holding unit 21: support unit 22: rotating shaft 3: supply nozzle 3a: supply port 3b: etching solution 30: arm 31: rotating shaft 32: adjustment unit 33: chemical solution source 4: Thickness measuring instrument 4a: Lens 40: Arm 41: Rotating shaft 42: Shape recognition unit 43: Control unit 5: Motor 50: Motor housing 6: Wafer 6A: Back surface 6B: Front surface

Claims (2)

In a spin-type wet etching apparatus comprising at least a nozzle for dropping an etching solution, a table that can hold and rotate a wafer, and a thickness measuring device that can measure a wafer thickness during processing,
Etching solution is dripped onto the one surface of the wafer from the nozzle above the center of the wafer held on the table, and the table is rotated at a predetermined number of rotations to spread the etching solution over one surface of the wafer and perform wet etching. A wet etching system that measures the thickness of the wafer and controls the amount of the etchant dropped. The thickness measuring device is capable of reciprocating in the radial direction between the center and the outer periphery of the wafer,
A wafer shape recognition unit for recognizing the shape of the wafer from the thickness of the wafer measured by the thickness meter;
A control unit for controlling the position where the etching solution is dropped based on the thickness of the wafer captured by the wafer shape recognition unit, and the amount of the etching solution dropped,
The wet etching apparatus according to claim 1, wherein the control unit monitors the shape of the wafer and performs wet etching processing control according to the shape.

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