JPH04333230A - Etching termination detector in plasma etching device - Google Patents

Abstract

PURPOSE:To enable the title detector to detect the etching termination constantly in the best condition even in the case of plasma fluctuation or in the case of the modification of the gaps between upper and lower electrodes within the title plasma etching device. CONSTITUTION:Within the title etching termination detector of a plasma etching device etching a wafer 5 held by either one electrode out of opposing two electrodes 2, 3 whereon high-frequency power is impressed to produce plasma after feeding a reactive gas, a bar type quartz glass 19 passing through either one out of said electrodes 2, 3 is provided. Next, an optical fiber 21 is connected to said quartz fiber 19 to detect the plasma beams for detecting the etching termination by the fluctuation in the plasma beams on the other hand, when said quartz glass 19 is rod type, a guide tube 12 encircling said quartz glass 19 is provided to feed the reactive gas from the peripheral parts of the quartz glass 19 while when said quartz glass 19 is made of a tube, the reactive gas is to be fed from the hollow part of the quartz glass 19.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching end point detection device for a plasma etching device, which is one type of semiconductor manufacturing device.

0002

2. Description of the Related Art One of the semiconductor manufacturing processes is a process of plasma etching the entire surface or a specific portion of a thin film formed on the surface of a silicon wafer.

[0003] When plasma etching is performed, a spectrum peculiar to the material being etched is generated, and by monitoring this spectrum, it is possible to determine whether etching of the thin film has been completed.

A conventional etching end point detection device will be explained with reference to FIG. Upper electrodes 2 are disposed vertically facing each other in the vacuum container 1.
, a lower electrode 3 is provided, and a reaction gas supply pipe 4 is provided passing through the upper electrode 2. A wafer 5 which is an object to be etched is placed on the lower electrode 3, and the wafer 5 is provided with a reaction gas between the upper electrode 2 and the lower electrode 3 while being supplied with a reaction gas from the reaction gas supply pipe 4. Etching is performed by applying high frequency power and generating plasma. In the figure, 10 indicates an upper electrode cover, and 11 indicates an electromagnetic shield.

As described above, when the etching of the film to be etched is completed, the generated spectrum changes, so by monitoring the spectrum, the end point of etching can be detected.

A see-through hole 6 is bored in the side wall of the vacuum container 1, and the see-through hole 6 is hermetically closed with a quartz glass plate 7 and further covered with a flange 8. The flange 8 has E
A PD (END POINT DETECTOR) probe 9 is attached, and the state of plasma generation, that is, the spectrum is detected via the EPD probe 9.

[0007]

[Problems to be Solved by the Invention] The conventional etching end point detection device described above has
Since detection is performed from the vertical direction, if the plasma fluctuates due to changes in the magnetic field, it will be affected by this plasma fluctuation. Therefore, depending on the etching state, a plurality of parts having different etching rates may be simultaneously monitored, making it impossible to accurately detect the etching end point.

[0008] Also, in the etching apparatus, there are an upper electrode 2,
There is a device in which the interval between the lower electrodes 3 is changed, but when the interval between the upper electrode 2 and the lower electrode 3 is changed, the optimum detection point in the vertical direction moves and deviates from the monitoring point of the EPD probe 9. Therefore, there is a problem in that the detection conditions change and accurate etching end point detection cannot be performed.

[0009] In view of these circumstances, the present invention aims to enable etching end point detection to always be performed under optimal conditions even when there are fluctuations in plasma or when the spacing between the upper and lower electrodes is changed. It is something to do.

0010

[Means for Solving the Problems] The present invention provides a method for generating plasma by supplying a reactive gas and applying high frequency power between two electrodes facing each other to generate a plasma on a wafer held by one of the electrodes. In an etching end point detection device of a plasma etching apparatus that performs etching, a guide tube is provided by penetrating one of the electrodes, and the reaction gas is supplied from the middle part of the guide tube, and the inside of the guide tube is A quartz glass rod is airtightly inserted into the quartz glass rod, an optical fiber is connected to the exposed end of the quartz glass rod, and a quartz glass tube is airtightly provided by passing one of the electrodes through the quartz glass rod. An optical fiber is connected to the exposed end, and a reaction gas is supplied from the hollow part of the quartz glass tube.

[0011]

[Operation] To determine the state of the plasma, the plasma light transmitted through the quartz glass rod or quartz glass tube is further guided to a required determination section through an optical fiber to detect the end point of etching. Further, the reaction gas necessary for the etching process is supplied from the guide tube or the hollow part of the quartz glass tube.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same components as those shown in FIG. 2 are given the same reference numerals. A guide tube 12 is provided airtightly passing through the center of the upper electrode 2 in the vertical direction. The guide tube 12 is made of metal, has a mirror-finished inner surface, and has a flange 14 fixed to its upper end. Further, a branch pipe 13 extending horizontally is provided in a portion of the guide tube 12 that protrudes from the vacuum vessel 1, and the branch pipe 13 is connected to a reaction gas supply source (not shown).

A nut seat 15 is provided on the upper surface of the flange 14.
to fix. A mortar-shaped recess 16 is formed on the inner edge of the upper surface of the nut seat 15, and an O-ring 17 is fitted into the recess 16 with one portion protruding. A bowl-shaped nut 18 having a through hole in the center is screwed onto the nut seat 15.

[0015] The quartz glass rod 19 is attached to the bowl-shaped nut 1.
8. Pass through the O-ring 17 and insert the guide tube 12
, so that the lower end surface of the quartz glass rod 19 faces the inside of the vacuum vessel 1. By tightening the bowl-shaped nut 18, the O-ring 17 is crushed and the quartz glass rod 19 is held airtight.

An optical fiber connector 22 is fixed to the upper surface of the bowl-shaped nut 18, and the optical fiber 21 connected to the end point detection/judgment section 20 via the optical fiber connector 22 is connected to the quartz glass rod 19. Connect to the top of the

The operation will be explained below. The light emitted by the plasma passes through the quartz glass rod 19 and is further guided to the end point detection/judgment section 20 via the optical fiber 21 . Since the inner surface of the guide tube 12 has a mirror finish, the guide tube 12 can be effectively guided out from the quartz glass rod 19 with little loss.

The end point detection/judgment section 20 detects the optical fiber 2.
The plasma light that has arrived through step 1 is subjected to necessary signal processing such as photoelectric conversion, and the plasma light emission is monitored, and the end point of etching is determined based on the change in the light emission state.

In the above embodiment, plasma light is monitored in the same direction as the direction in which high frequency power is applied. Therefore, the light emission from a specific portion of the wafer is constantly monitored, and the detection results have little error and are not affected by the magnetic field. Moreover, since the monitoring position is at the center of the electrode, it is the place where the plasma is most stable.

Furthermore, although a strong magnetic field is generated inside the electromagnetic shield 11 due to high-frequency power and plasma generation, as described above, the detection signal is an optical signal that reaches a location outside the electromagnetic shield 11 that is not affected by the magnetic field. Since the signal is transmitted by

[0021] In the above embodiment, the plasma light was emitted using a quartz glass rod, but a quartz glass tube may also be used. In this case, the reaction gas is supplied from the hollow part of the quartz glass tube. Moreover, it is of course possible to implement the present invention even if the electrodes are of a left-right facing type.

[0022]

[Effects of the Invention] As described above, according to the present invention, the following excellent effects are achieved.

(2) Since it is not affected by fluctuations in the plasma due to changes in the magnetic field, stable etching end point detection can be performed at all times.

(2) Since the plasma light is derived using a rod made of quartz glass, there is little loss of the detection light, and changes in the plasma light can be detected accurately.

(2) The reactive gas can be introduced from the center of the electrode as in the conventional method, without impairing the uniformity of etching.

(2) Even if the electrode spacing changes, the etching end point can always be detected under optimal conditions without adjusting the detection position.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

2 Upper electrode 3 Lower electrode 5 Wafer 12 Guide tube 19 Quartz glass rod 21 Optical fiber

Claims (2)

[Claims] 1. Etching of a plasma etching apparatus that supplies a reactive gas, applies high frequency power between two opposing electrodes to generate plasma, and etches a wafer held by one of the electrodes. In the end point detection device, a guide tube is provided by penetrating one of the electrodes, the reaction gas is supplied from the middle part of the guide tube, and a quartz glass rod is airtightly inserted into the guide tube. An etching end point detection device for a plasma etching apparatus, characterized in that an optical fiber is connected to the exposed end of the quartz glass rod. 2. Etching of a plasma etching apparatus that supplies a reactive gas, applies high frequency power between two opposing electrodes to generate plasma, and etches a wafer held by one of the electrodes. In the end point detection device, a quartz glass tube is installed airtight with one of the electrodes passed through, an optical fiber is connected to the exposed end of the quartz glass tube, and a reaction gas is supplied from the hollow part of the quartz glass tube. An etching end point detection device in a plasma etching device configured to do so.