JPH01236633A - Etching end point detection - Google Patents

Abstract

PURPOSE:To enable the accurate etching terminal to be detected automatically by a method wherein the apparent weight of wafers is measured every time when the wafers are picked up from an etchant in proper times corresponding to the advancement of etching process to detect the terminal of the etching processes by detecting that the apparent weight has declined to almost specific value. CONSTITUTION:A weight measuring/discriminating device 60 gives a command to a lift mechanism 50 in the lapse of specific time after starting the etching process to pick up a cage 30 from all etchant 71 simultaneously the device 60 receives a signal from a weight sensor 41 to measure the weight on a balance 40. Then, in the lapse of specific time, the device 60 gives another command again to pick up the cage 30 and after measuring.recording the apparent weight of wafers 10, the cage 30 is immersed in the etchant 71. Later, said procedures are repeated. Thus, the terminal of etching processes is detected by detecting that the apparent weight has declined to almost specific value. Through these procedures, the etching terminal can be detected accurately without resorting to any manual operations.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the etching end point of a wafer used for ICs and the like.

Conventionally (2) Removal Conventionally, for example, when wet-etching a hydrophilic layer of a wafer in which a hydrophobic layer and a hydrophilic layer were successively formed on a base substrate, the end point of etching was visually confirmed. That is, the wafer is pulled out of the etching solution and the color of the wafer and the degree to which the etching solution is repelled are checked to determine whether etching has been completed. Furthermore, when the thickness of the layer to be etched is known, the end point of etching is determined by the etching time.

However, visually determining the end point of etching based on the color of the wafer and the repellency of the etching solution not only requires human labor, but also makes it difficult to accurately detect the end point. Furthermore, the end point of etching is determined by the etching time because the etching rate changes depending on the temperature, concentration, etc. of the etching solution, which may result in excessive or insufficient etching.

The present invention has been made in view of the above, and is an etching end point detection method that enables accurate etching end point detection without the need for human labor and even when there are variations in the etching rate and the thickness of the etched layer. The purpose is to provide law.

In order to solve the above-mentioned problems, the method of the present invention involves submerging a wafer having a hydrophobic layer and a hydrophilic layer formed on this layer in an etching solution to remove the hydrophilic layer. In a method for detecting the end point of etching performed on a layer, the wafer is supported so as to be able to be raised and lowered, and the wafer is lifted from the etching solution an appropriate number of times as etching progresses, and the apparent weight of the wafer is measured; The end point of etching is detected by detecting when this weight decreases to approximately a constant value.

When the prepared wafer is lifted from the etching solution, the etching solution adheres to the surface of the hydrophilic layer while etching is in progress, but when the etching ends and the surface of the hydrophobic layer is exposed, the etching solution is removed. It will no longer adhere to the surface of the hydrophobic layer.

Implementation Team An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is an explanatory diagram of this embodiment, FIG. 2 is a schematic diagram of the configuration of the scale, and FIG. 3 is a graph of temporal changes in the apparent weight of a wafer. FIG. 4 is a cross-sectional view of a portion of the wafer as it is being etched.

In FIG. 1, a carrier 2 containing a wafer 10 is shown.
0 is mounted on a cage 30, and this cage 30 is attached to a scale 40 via a connecting member 31. Further, the scale 40 is attached to a lift mechanism 50 via a connecting member 51 so as to be movable up and down.

Reference numeral 60 denotes a weight measurement/discrimination device, which is connected to the scale 40 and the lift mechanism 5 by signal lines 45 and 52, respectively.
tied to 0. 70 is a tank containing etching liquid 71. In addition, cage 30 and carrier 2
0 is provided with openings (not shown) so that the etching liquid 71 can quickly flow in and out.

The scale 40 includes a case 42, a frame-shaped member 43, and a weight sensor 41, as shown in FIG. A weight sensor 41 using a strain gauge or the like is fixed to the bottom of the case 42, and the upper side 431 of the member 43 is placed and fixed on the weight sensor 41. Side edges 432 protruding from the lower part near both ends of the upper edge 431 slidably pass through the opening 44 of the case 42 , and the tip portions of the side edges 432 are connected by a lower edge 433 . The connecting member 31 is fixed to the lower side 433.

A signal line 45 is attached to the weight sensor 41.

The lift mechanism 50 is connected to the cage 30 at 40.
the cage 30 and the etching liquid 7 in the tank 70.
For example, an electric winch or the like is used. The scale 40 is connected to the lift mechanism 50 via a connecting member 51 fixed to the upper part of the case 42.
It is connected to the.

The wafer 10 to be etched is, for example, as shown in FIG. 4(a).
As shown in the cross section, a wiring film 12 made of a plurality of films such as aluminum, a hydrophobic Si layer 13, and a hydrophilic SiO□ layer are sequentially formed on a base substrate 11. It has 14 layers and 4 layers. In the SiO□ layer 14 layer type 4, a resist 15 is formed leaving a portion to be etched.

Next, a method for detecting the end point of etching will be described.

When the cage 30 is submerged in the etching liquid 71 by operating the lift mechanism 50, the etching liquid 71 flows through the cage 30 into the carrier 20 and comes into contact with the wafer 10 to begin etching. Weight measurement/discrimination device 60
When a predetermined time has elapsed after the start of etching, the device issues a command to the lift mechanism 50 via the signal line 52, lifts the cage 30 from the etching solution, receives a signal from the weight sensor 41 via the signal line 45, and lifts the cage 30 up from the etching solution. Measure the weight on the 40.

By submerging only the carrier 20 and the cage 30 in the etching liquid 71 and then lifting them out, and measuring the weight in this state in advance, the weight on the scale can be calculated from the weight on the scale.
The weight (apparent weight) of the Ever 10 with the etching liquid 71 attached can be measured and recorded.

Thereafter, the weight measurement/discrimination device 60 issues a command to the lift mechanism 50 to submerge the cage 30 into the etching liquid 71.

After a predetermined period of time has elapsed, a command is issued again to the lift mechanism 50 to lift up the cage 30, and after measuring and recording the apparent weight of the wafer 10, the cage 30 is submerged in the etching liquid 71. From now on, this kind of operation is repeated.

FIG. 4('b) shows a state in which etching is in progress. When the wafer IO is pulled up in this state, the etching liquid 71 is attached to the surface of the hydrophilic 5iOz layer 14. In this case, the measured and recorded apparent weight of the wafer 10 is represented as point a in section A of FIG.

This weight remains at an approximately constant value (
heavy ff1W+).

At the final stage of etching, there are parts where etching has not been completed and parts where etching has been completed, that is, parts where the surface of the hydrophobic Si layer 13 is not exposed and parts where it is exposed. 5iJ
The etching liquid 71 still adheres to the surface of the portion where the wafer 113 is not exposed, but since the etching liquid 71 does not adhere to the exposed surface, the appearance of the wafer 10 changes only by the weight of the etching liquid 71 that does not adhere. This means that the weight of is decreasing. Therefore, as the etched area increases, the measured apparent weight increases
As already shown at point B in the figure, it decreases.

When the etching of the wafer 10 is completed, the measured apparent weight is as shown at point C in section C of FIG.
The weight becomes a substantially constant value (weight WZ) lower than the weight W1, and this value does not change even if measurements are repeated.

Therefore, the weight measurement/discrimination device 60 can detect the end point of etching by detecting that the measured apparent weight has decreased by more than the weight W and has reached a substantially constant weight W2. Incidentally, by detecting the end point of etching and issuing an alarm, it is possible to omit the manual effort required to confirm the end point of etching, which is conventionally required.

As explained above, according to the present invention, a wafer having a hydrophobic layer and a hydrophilic layer formed on this layer is lifted out of the etching solution an appropriate number of times as etching progresses. The apparent weight of the wafer is measured each time, and the end point of etching is detected by detecting that this weight has decreased to a substantially constant value.

Therefore, there is an advantage that an accurate end point of etching can be automatically detected without requiring manual labor, and even if there are variations in the etching rate or the thickness of the etched layer.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention. Figure 1 is an explanatory diagram of this embodiment, Figure 2 is a schematic diagram of the configuration of the scale,
FIG. 3 each shows a graph of the temporal change in the apparent weight of the wafer. FIG. 4 is a cross-sectional view of a portion of the wafer as it is being etched. 10... Sea urchin A-113...5i15.14...
SiO□ layer 14.40... Scale, 71... Etching liquid.

Claims (1)

[Claims] (1) In an etching end point detection method in which a wafer having a hydrophobic layer and a hydrophilic layer formed on this layer is submerged in an etching solution and the hydrophilic layer is etched, the wafer is raised and lowered. The wafer is supported freely and lifted from the etching solution an appropriate number of times as etching progresses, the apparent weight of the wafer is measured, and when it is detected that this weight has decreased to a substantially constant value, etching is performed. An etching end point detection method characterized by detecting the end point of.