JP7348640B2 - Etching equipment and etching method - Google Patents

Description

The present invention relates to an etching apparatus used for adjusting the thickness of an object to be etched to a predetermined target thickness, and an etching method using such an etching apparatus.

Conventionally, in order to adjust the thickness of the semiconductor layer on a semiconductor substrate to a predetermined target thickness, a technique has been used in which the thickness of the semiconductor layer is measured region by region and locally gas etched (for example, (See Patent Document 1.)

Japanese Patent Application Publication No. 5-190499

However, even if the thickness of the object to be etched is measured and locally etched as described above, the target thickness may not always be achieved because the etching ability of the etching apparatus varies depending on various factors.

SUMMARY OF THE INVENTION In view of the above-mentioned points, it is an object of the present invention to easily adjust the thickness of an etching target to a target thickness with high accuracy.

In order to achieve the above object, the present invention
An etching device that etches an etching target,
a plasma device that generates plasma and supplies it to the etching target;
a process gas supply device that supplies process gas to the plasma device;
a measuring device for measuring the thickness of the etching target;
a moving device that moves the etching target in the main scanning direction and the sub-scanning direction with respect to the plasma device and the measuring device;
A control device that controls the operation of the plasma device, measurement device, and movement device;
Equipped with
The control device moves the etching target in the main scanning direction and the sub-scanning direction to perform etching on the etching target, and then moves the etching target after etching in at least the sub-scanning direction. The measuring device measures the thickness of the etching target in a measurement area that spans the sub-scanning direction and is a partial area in the main scanning direction, and determines the thickness of the etching target to be etched thereafter based on the measurement results. It is characterized in that it is configured to perform etching.

As a result, for example, the thickness of the etching target mainly in the area lined up in the sub-scanning direction is measured and the etching amount is corrected, thereby simplifying the measurement of the thickness of the etching target and shortening the overall processing time. can be easily done.

According to the present invention, it is possible to easily adjust the thickness of an object to be etched to a target thickness with high accuracy.

FIG. 1 is a schematic diagram schematically showing the configuration of an etching apparatus. FIG. 3 is an explanatory diagram showing the scanning direction of etching and thickness measurement.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

(Schematic configuration of etching equipment)
FIG. 1 shows an example of an etching apparatus using downstream plasma etching. A silicon wafer 1 (substrate) is placed on a stage 2 (moving device) housed in a chamber C having a gate valve 10. The stage 2 can be driven in the X-axis and Y-axis directions (main scanning direction A and sub-scanning direction B shown in FIG. 2) by the action of the X-axis drive motor 3 and the Y-axis drive motor 3'. The silicon wafer 1 can be moved in the X-axis and Y-axis directions. Here, in the following description, for convenience, it will be assumed that the tip nozzle 5 and the layer thickness measuring device 11 move relative to the silicon wafer 1.

In a chamber C above the silicon wafer 1, a tip nozzle 5 of a discharge tube 4 for generating plasma is installed. The other end of the discharge tube 4 is connected to a process gas supply line 8 (process gas supply device). Further, a microwave power source 7 is arranged in a portion of the discharge tube 4 corresponding to the plasma generation region 6. The discharge tube 4, the tip nozzle 5, the plasma generation region 6, and the microwave power source 7 constitute a plasma device.

The chamber C is also provided with a layer thickness measuring device 11 that measures the thickness of the semiconductor (to be etched) layer on the silicon wafer 1 .

When performing etching, a vacuum pump (not shown) connected to the chamber C is operated, and sulfur hexafluoride gas, which is a process gas, is introduced from the process gas supply line 8, and the plasma generator is activated. The discharge tube 4 is operated to generate fluorine radicals, which are irradiated onto the silicon wafer 1 from the tip nozzle 5. The silicon wafer 1 is subjected to an etching action by fluorine radicals irradiated from the tip nozzle 5 of the discharge tube 4. Here, the fluorine radicals act locally on the portion of the silicon wafer located below, but since the silicon wafer is driven in the XY axis directions as described above, the entire surface of the wafer is processed. More specifically, the silicon wafer 1 is moved in the secondary direction while the tip nozzle 5 relatively reciprocates in the main scanning direction A shown in FIG. It moves in the scanning direction B by a pitch p. Moreover, when the layer thickness measuring device 11 performs measurement as described later, the layer thickness measuring device 11 moves relatively in the sub-scanning direction B.

The drive control of the stage 2, the operation control of the plasma generator, the measurement of the thickness of the semiconductor layer by the layer thickness measuring device 11, etc. are performed by a control computer 9 (control device).

(thickness control)
With respect to the silicon wafer 1 on which a semiconductor layer is formed on a supporting substrate such as a silicon substrate via an insulating film using the etching apparatus as described above, the layer thickness of the semiconductor layer becomes a predetermined layer thickness for each region. An example of the operation when the etching process is performed as shown in FIG.

(1) First, the thickness of the entire semiconductor layer on the silicon wafer 1 before etching is measured. This measurement may be performed by the layer thickness measuring device 11 provided in the etching device, but it is usually performed by a shape measuring device, etc. outside the device to improve measurement accuracy and speed up the processing. This makes it easier to create new ideas.

(2) For each region of the silicon wafer 1, the etching allowance is determined based on the above measurement results and a preset target layer thickness. (3) Etching is performed while the tip nozzle 5 relatively moves in the main scanning direction and the sub-scanning direction at a speed corresponding to the above-mentioned machining allowance.

(4) When etching is completed, the layer thickness of the semiconductor layer near the center in the main scanning direction A is measured, for example, while the layer thickness measuring device 11 moves in the sub-scanning direction B shown in FIG. If there is a difference between the measured layer thickness and the original target layer thickness, a correction value for the machining allowance is determined in accordance with the difference between the measured layer thickness and the original target layer thickness. The above measurement may be performed on a linear region of the silicon wafer 1 without any movement in the main scanning direction; Alternatively, the process may be performed on a band-shaped area. In any case, by performing the measurement on only a portion of the entire area of the silicon wafer 1, the time required for measurement can be shortened.

(5) After that, the same operations as in (1) to (4) above are repeated for other silicon wafers 1, but in (2), further steps are performed based on the measurement results after etching in (4) above. The machining allowance including correction is required (feedback). Here, although the measurement in (4) above is for some positions in the main scanning direction A, the variation in etching is greater at the position in the sub-scanning direction B than at the position in the main scanning direction A. If there is a strong dependence on A similar correction can be made as follows. Alternatively, correction may be performed at each position in the main scanning direction A based on a value obtained by interpolation calculation based on a measurement value in an area adjacent to the sub-scanning direction B. Further, the correction is not limited to regions having the same position in the sub-scanning direction B, but may be corrected based on the measured value of the region corresponding to the time since plasma generation started.

Note that general correction is performed on machining position information, but in the present invention, machining accuracy is improved by incorporating the concept of performing correction on machining trends that depend on time information. . Further, after the correction is made using the position information, further correction can be made using the time information.

As mentioned above, if the variation in the degree of etching that depends on the position in the sub-scanning direction B is expected to be larger than the variation in the degree of etching that depends on the position in the main-scanning direction A, By measuring the layer thickness of the areas lined up in the scanning direction B and correcting the etching amount, it is possible to simplify the measurement and shorten the overall processing time, improving the feedback frequency and suppressing the time lag related to feedback. This makes it possible to maintain and improve machining accuracy.

(Other matters)
In addition, in the above example, the layer thickness measuring device 11 is provided in the chamber C, but the present invention is not limited to this. may be measured. However, when it is provided in chamber C, it is possible to immediately perform measurement after processing without breaking the vacuum in chamber C, and to facilitate feedback for the next etching. Furthermore, it becomes possible to easily carry out measurement in parallel with the etching process.

Further, the number of layer thickness measuring devices 11 is not limited to one, and a plurality of devices may be provided so that the layer thicknesses of multiple regions on the silicon wafer 1 can be measured simultaneously. In this case, the measurement time can be easily shortened, and the stroke of the stage 2 can be kept short and the chamber C can be kept small.

In addition, although the above example shows an example in which the main scanning direction is a straight line, the present invention is not limited to this. By rotating the silicon wafer, the circumferential direction is the main scanning direction, and the movement in the radial (or diameter) direction is the secondary direction. Even in the case of the scanning direction, correction can be similarly made based on measurements after etching.

In addition, although the above example shows an example in which the semiconductor layer formed on the silicon wafer 1 is processed to a target thickness, the process is not limited to this, and the substrate itself such as silicon or quartz can be etched to the target thickness. Further, the thickness, parallelism, flatness, etc. of the entire substrate may be processed with target values.

Furthermore, when a film formed on a substrate is to be etched, the etching target is a semiconductor film such as silicon (SOI), an insulating film such as a silicon oxide film or a silicon nitride film, or a conductive film such as tantalum. It may also be a film or the like.

1 Silicon wafer
2 stage
3 X-axis drive motor
3' Y-axis drive motor
4 Discharge tube
5 Tip nozzle
6 Plasma generation area
7 Microwave power supply
8 Process gas supply line
9 Control computer
10 Gate valve
11 Layer thickness measuring device

Claims (7)

An etching device that etches an etching target,
a plasma device that generates plasma and supplies it to the etching target;
a process gas supply device that supplies process gas to the plasma device;
a measuring device for measuring the thickness of the etching target;
a moving device that moves the etching target in the main scanning direction and the sub-scanning direction with respect to the plasma device and the measuring device;
A control device that controls the operation of the plasma device, measurement device, and movement device;
Equipped with
The control device moves the etching target in the main scanning direction and the sub-scanning direction to perform etching on the etching target, and then moves the etching target after etching in at least the sub-scanning direction. The measuring device measures the thickness of the etching target in a measurement area that spans the sub-scanning direction and is a partial area in the main scanning direction, and determines the thickness of the etching target to be etched thereafter based on the measurement results. An etching apparatus characterized in that it is configured to perform etching. The etching apparatus according to claim 1,
The etching apparatus is characterized in that the measurement area is a linear or band-shaped area along the sub-scanning direction. The etching apparatus according to any one of claims 1 to 2,
An etching apparatus characterized in that the measuring device is provided in the same chamber as the plasma device. The etching apparatus according to claim 3,
An etching apparatus characterized in that the measuring apparatus is provided so as to be able to measure the thickness of the object to be etched simultaneously with etching by the etching apparatus. The etching apparatus according to any one of claims 1 to 4,
An etching apparatus characterized in that a plurality of the measurement apparatuses are provided, each of which is configured to simultaneously measure the thickness of the etching target in different regions of the etching target. An etching method using the etching apparatus according to any one of claims 1 to 5,
a first measurement step of measuring the thickness of the entire area of the etching target;
an etching step of etching the etching target based on the measurement result of the first measurement step;
A second step of moving the etching target after etching at least in the sub-scanning direction and measuring the thickness of the etching target in a measurement area that spans the sub-scanning direction and is a part of the main scanning direction. measurement process,
a subsequent etching step of etching a subsequent etching target based on the measurement results in the first and second measurement steps ;
An etching method characterized by: The etching method according to claim 6,
An etching method characterized in that the first measuring step is performed before the etching target is introduced into the etching apparatus.

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