JPH0348423A - End point determination method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Minute Hand] The present invention relates to an end point determination method and apparatus, and more particularly to an end point determination method and apparatus suitable for dry etching processing performed by changing processes.

[Conventional technology]

Conventional dry etching end point determination is performed by using an optical filter, a photoelectric transformer, and an AD converter in the apparatus when etching a semiconductor substrate by plasma dry etching, for example, as described in Tokushima No. 58-21530. a. By inserting a memory circuit or the like and comparing the light intensity of a specific wavelength before etching and the light intensity during etching, it was possible to accurately determine the end point of etching.

[The problem that the invention attempts to solve]

The above-mentioned conventional technology does not take into consideration the fact that the plasma emission intensity changes when the process conditions are changed during etching, and there is a problem that it becomes impossible to determine the end point of etching.

An object of the present invention is to provide an end point determination method and apparatus that can determine the end point of etching even when process conditions are changed during etching.

[Means to solve the problem]

In order to achieve the above object, a means for inputting light emission of a specific wavelength among the plasma light emission in the processing chamber, a means for converting the amount of the input light emission into an electrical signal, and a means for inputting light emission of a specific wavelength among the plasma light emission in the processing chamber, means for inputting only electrical signals when processed according to process conditions; means for converting the input electrical signals into continuous data; and means for determining an end point using the continuously converted data. The device is equipped with the following: When etching is performed using two or more types of processes intermittently, only the data signals to be processed under specific process conditions are input, and the data to be input is continuously input. The continuously converted data is used to determine the end point.

[For production]

When determining the depth point when etching is performed using two or more types of processes intermittently, IM! Input only data when processed under one or two types of specific process conditions, convert the intermittent input data into continuous data, and detect changes in the data or differences between the two types of data. Since the end point is determined based on the change in
Even when process conditions are changed during etching, the end point of etching can be determined.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the structure of a dry etching apparatus.

A sample stage 2 is provided in a vacuum container l, which is a processing chamber, and a sample 3 is placed on the sample stage 2. The vacuum container 1 is evacuated to a vacuum via a variable conductance valve 4 in a vacuum evacuation device 15. In addition, the process gas supply device 1i6 is connected to the vacuum container l.
is connected to supply process gas to the vacuum vessel 1. A high frequency power source 7 for plasma excitation is connected to the sample stage 2 and supplies high frequency power to the sample stage 2 . A lighting window 8 for monitoring plasma emission is provided in the vacuum container 1, and a filter 9 for passing light at a specific wave end and a photomultiplier tube 10 are connected.

The control device 100 outputs a pressure control signal 49200 for controlling the pressure inside the vacuum vessel 1 to the variable conductance valve 4, and selects a process gas. A gas control signal 202 for setting the tR amount is output to the process gas supply*[6, and an RF output control signal 201 for controlling the output of plasma excitation power.
is output to the high frequency power source 7, and an end point determination request compensation code 203 is output.
A plasma state number 204 assigned in accordance with the process conditions is output to the end point determination device 1i 101. A signal proportional to the plasma emission intensity obtained by the photomultiplier tube 10 is amplified by amplifier (2) and output as a plasma emission signal 205 to the end point determination gtfj 1101. End point determination device! !
101 is an end point determination request code 20 from the control device 100.
3, a plasma emission signal 205 is input to determine the end point.

When the end point is detected, the end point detection signal 206 is sent to the control device 100.
output to and finish etching.

At *i shown in FIG. 1, an etching gas is poured into a vacuum container l as shown in FIG. The debossing gas was introduced alternately for t2 seconds, and the debossing gas supply was stopped t.
The process of supplying plasma excitation power for tl+ts seconds from 3 seconds before stopping the etching gas supply to generate plasma discharge is one cycle, and this cycle L; is repeated in row f. The processing conditions are set in the control device 1101. l
When the cycle is subdivided, the period t3 is divided into a deposition period A, the period 11 is an etching period B*, and the period t2-t3 is a plasma discharge stop period C. Further, FIG. 2 shows an example of the plasma emission intensity in this example.

Next, a case will be described in which the plasma emission intensities of the processing period A and the processing period B are used as data for end point determination when processing sample 3.

After starting the process, the control device l00 outputs pressure control signals 200,
The treatment is performed while changing the gas control signal 202 and the RF output control signal 201 according to the process sequence shown in FIG. Control equipment! Too sets the process conditions for the deposition period, simultaneously sets the end point establishment request signal 203, and outputs data @A'' to the plasma state signal 204. When the deposition period ends, the end point determination request signal is sent. Recept 203.

Next, the process conditions are set for the etching period B, and at the same time, the end point determination request code 203 is set, and data @B'' is outputted to the plasma state signal 204.

When the etching period B ends, the end point determination request signal 203
Reset. Next, process conditions are set for the plasma discharge stop period C, and data "C" is set for the plasma state signal 204 at the same time. Thereafter, similar control is repeated until the end point detection signal 206 is received.

Next, an embodiment of the end point determination method will be described.

When the end point determination device it lot detects the end point determination request signal 203, it checks the plasma status signal 49 204. If it is "one person", then it considers the subsequent plasma emission signal 205 as an input value regarding the status person, and if it is "B", it determines the subsequent plasma emission. signal 20
5 is regarded as an input value related to state B, and the end point determination process is performed. This process is repeated until the paper point determination request compensation code 203 is reset.

When the end point determination request signal 203 is set, the plasma emission signal 205 is sampled at predetermined sampling intervals, and sampling is continued until the end point determination request signal 203 is reset. When the end point determination request signal 206 is reset, the average of the sampling points from when the end point determination signal 206 is set until it is reset is determined. If the plasma state signal 204 at this time is @A# and it is the nth deposition period, this average value is A. Binding, ″″
If it is the nth etching period for B'', this average value is Bn
be memorized as .

Next, when the values of sAll and Bn are determined, the difference 8■ between Bn-An is determined. When the value of Sn becomes smaller than the preset value, it is regarded as the end point and the end point detection signal 2 is output.
Outputs 06. If the time for 1 cycle is shorter than the time until the end of the process, it is also possible to obtain the first difference or the second difference between the values of sn and use changes in these values to determine the end point.

Note that the criteria for determining the end point are the value of the difference Sn and the value of the difference an of 1?, depending on the way the values change. :K difference or difference S. It is detected that the value of the second difference of has become larger or smaller than the preset value, or that the value of the first or second difference of the difference Sn has reached the maximum or minimum value. , or it may be detected that a predetermined threshold value is blocked in the plus or minus direction.

Next, as another embodiment of the end point determination, a method of determining the end point only during the etching period B will be described with reference to FIG.

The end point determination request signal @203 from the control device 1j 100 is set only for the etching period B. End point determination device 101
When detecting the end point determination request signal 203, after a predetermined period of time tw until the plasma stabilizes, the plasma emission signal 203 is output at a predetermined sampling interval.
Sample 5. Second! Let Bnm be the m-th sampling value of the In-th plasma-like flB. This continues until the end point determination request compensation code 203 is reset, and finally, when sampled m times, Bn 1 "" B
Obtain sampling value data up to mn. Only at the time of the first end point determination request code 203, the end point determination data bll to blm, which are sampling data of Bjl""Blm, are used. This is because, at the first time, there is no need to be concerned about a decrease in the amount of light emitted from the plasma emitted while processing the sample 2. When the n-th end point determination request signal 203 is detected from the second time onwards, the plasma start signal 205 is sampled once after waiting a certain period of time tW as in the first time, and this value is set to Bn. shall be. At this time, the difference (
Calculate b(n-om Bnt ), I)(n-1
) m and Bn. Bn. so that the values are the same. Add the above difference to .

Let this difference be the offset value. The offset value is added to the next and subsequent sampling values Bnm to obtain bnm=Bnm+(t)(n-D Bn1) as data for end point determination, and this value of bnm is used as data for end point determination. Thereafter, each time the end point determination request signal 203 is set, the offset value is updated to give continuity to the end point determination data, and the end point determination is performed.

When performing the end point determination using the first difference of the end point determination data, use a method similar to the method described above so that the first difference value is the same, and when performing the end point determination using the second difference of the end point determination data, use the same method. Set the offset value so that the secondary difference values are the same. Thereafter, the end point is determined using the same end point determination criteria as in the above embodiment.

As another embodiment of the end point determination device, the transmission wavelength of the filter 9 may be switched using two types of plasma state signals 205.

In this embodiment, the control device It 100 and the end point determination device 101
Although these are provided individually, it is also possible to combine them into one control device and manage and process the end point I1 constant demand compensation signal 203, plasma state signal 204, and end point detection signal 206 as data on a storage device. good.

A brief summary of these embodiments is as follows.

During etching under any two or less process conditions, the plasma emission intensity under one process condition,
The difference between the plasma emission intensity under the other process condition, I?
: The end point is determined by comparing the K difference and the secondary difference value. At this time, under one process condition (a), the plasma emission intensity changes greatly, and under the other process condition (b), the plasma emission intensity does not change much, or under process condition (j) Select process conditions that change in the opposite direction to the change in plasma emission intensity. Further, the process condition (b) may be a plasma stop period. If a change in the amount of plasma light emission cannot be expected based on the process conditions alone, plasma light emission *i of different wavelengths may be detected under process conditions (a) and (b).

When determining the end point using only one type of process condition, only the plasma emission intensity during the etching period under the specified one type of process condition is detected, and the plasma emission intensity ti1 under the same process condition up to the previous time is detected. An offset value is added to the detected value to provide end point determination data so as to maintain continuity with the measured value, and the end point determination is performed by regarding the data detected and calculated several times as continuous data.

As described above, according to this embodiment, it is possible to determine the end point even when the process conditions are changed during etching, and it is possible to improve the etching accuracy and reproducibility in submicron processing such as TM (time modulation) etching. I can do it.

〔Effect of the invention〕

According to the present invention, the end point of etching can be determined even when the process conditions are changed during etching.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an end point determination device according to an embodiment of the present invention, FIG. 2 is a timing chart showing an example of processing conditions for the device in FIG. 1, and FIG. 3 is an end point determination device in the device in FIG. FIG. 3 is a timing chart diagram illustrating an example of determination amount data. 1... Vacuum container, 9... Filter,
10... Photomultiplier tube, 100... Control device d% 101... End point determination device, 203... End point determination request signal, 204 Plasma state signal, 205 Plasma emission signal, 206 Zets --- East detection 4S

Claims (1)

[Claims] A method for determining an end point when etching is performed using one or more types of processes intermittently, including inputting only data signals when processing is performed under specific process conditions;
A patent determination method characterized in that the intermittent input data is converted into continuous data, and the continuously converted data is used to determine an end point. 2. Setting two types of specific process conditions,
The end point determination according to claim 1, wherein the end point is determined based on either the magnitude of the difference in luminous intensity between the two processing states, the amount of the difference in the luminous intensity expressed, or the rate of change in the difference in the luminous intensity. Method. 3. For the conversion into the continuous data, use either the average value of the intermittent input data, the input data value a predetermined time after the input point, or the input data value a predetermined time before the input stop point. An end point determination method according to claim 1. 4. As for the conversion to continuous data, match the final value of the previous data with the initial value of the current data,
The end point determination method according to claim 1, which adds an offset to the current input data value. 5. As for the conversion to the continuous data, either the magnitude of the difference in luminescence intensity, the amount of change in the difference in luminescence intensity, or the rate of change in the difference in luminescence intensity in the processing conditions of two specific processes is continuous. The end point determination method according to claim 1, wherein an offset is added so that the end point determination method is performed. 6. Means for inputting light emission of a specific wavelength among the light emission of plasma in the processing chamber, means for converting the input amount of light emission into an electrical signal, and a means for inputting light emission of a specific wavelength among the light emission of plasma in the processing chamber, means for inputting only the electrical signal when the electrical signal is input, means for converting the input electrical signal into continuous data, and means for determining an end point using the continuously converted data. An end point determination device. 7. The means for converting the electrical signal into continuous data,
7. The end point determination device according to claim 6, wherein an offset is added to the current input data value so that the final value of the previous data and the initial value of the current data match. 8. The means for converting the electrical signal into continuous data,
Claim 6: Obtaining either the average value of the electrical signal of the specific process condition that is intermittently input, the input value a predetermined time after the input point, or the input value a predetermined time before the input stop point. The end point determination device described. 9. The means for changing the electrical signal into continuous data,
Claims in which an offset is added so that either the magnitude of the difference in luminescence intensity, the amount of change in the difference in luminescence intensity, or the rate of change in the difference in luminescence intensity between two types of specific processes is continuous. The end point determination device according to item 6. 10. The means for determining the end point is based on the magnitude of the difference in luminescence intensity between two types of specific process processing conditions;
7. The end point determination device according to claim 6, which performs the determination based on either the amount of change in the difference in emitted light intensity or the rate of change in the difference in emitted light intensity.