JPS60135583A - Automatic etching device - Google Patents

Abstract

PURPOSE:To provide a titled device which performs automatically and surely etching to a desired thickness by detecting the actual progressing condition of etching under the actual conditions under which the various conditions for determining the progressing state of the etching are overlapped and setting the time for etching. CONSTITUTION:A body to be etched such as a semiconductor wafer or the like is immersed in an etching liquid 1 in a liquid tank 3 and the liquid temp. in said stage is detected 5. The liquid temp. introduced into a control part 9 for data collection is stored for the read-in time set in an arithmetic part 10, for example, 60sec and 120sec after the point of the time when the etching is started and the change rate (k) of the temp. is calculated. More specifically, a gradient (k) is calculated in the part 10 from the change in the liquid temp. T with respect to the lapse time (t) from the point of the time when the etching is started, i.e., the difference between the liquid temp. T1 in 60sec and the difference in the liquid temp. T2 in 120sec. On the other hand, the data of the relation between the change rate (k) of the liquid 1 at the body to be etched and the reaction rate (k) is empirically determined and is preliminarily programmed in the part 10. The data on the change rate (k) and the etching speed gamma are compared in the control part 9 and the time for obtaining the desired etching thickness is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic etching apparatus suitable for use, for example, in obtaining semiconductor wafers having a desired thickness.

BACKGROUND ART AND PROBLEMS Semiconductor wafers for producing various semiconductor devices are usually obtained by slicing a single crystal semiconductor, lashing the slices, and then etching the entire surface to obtain a semiconductor wafer having a desired thickness. Etching in this case is usually carried out by using a mixed solution of hydrofluoric acid, nitric acid, acetic acid, etc. as an etching solution, and immersing the semiconductor wafer in this etching solution. In this case, the desired thickness is etched, i.e. the wafer is finally of the desired thickness.
l=jru. 14 of the tth etching, the so-called 9th round (down, normal () etching processing time) jLk ((
I have set it up and am doing it. When using Method J and Method Z, the thickness of the obtained semiconductor wafers varied widely, and for example, the thickness accuracy ranged to about ±25 inches. In other words, for example, according to etching, it is 5
In the case of a thickness of 0 μm, a variation of ±12.5 μm occurs, and this variation is a major problem. Therefore, in order to minimize the variation and perform etching with high thickness accuracy, the temperature and composition of the etching solution must be set accurately, and the time the etching solution is allowed to stand after being prepared must be set within a certain amount of time. However, even with this method, the etching rate still varies depending on the conductivity type of the semiconductor wafer, the type and concentration of impurities, and the etching rate also varies depending on the crystal orientation of the wafer. Therefore, it is insufficient to control the etching thickness simply by the etching time.

OBJECTS OF THE INVENTION As described above, the present invention is capable of automatically and reliably etching a desired thickness despite the existence of numerous factors that cause etching variations, such as achieving a desired final etching thickness. An object of the present invention is to provide an automatic etching apparatus that can easily obtain a semiconductor wafer with a thickness of .

Summary of the Invention The present invention provides an etching liquid tank equipped with a stirring device and containing an etching liquid, a temperature detection means for detecting the temperature of the etching liquid, and a control valve that controls the supply of pure water into the etching liquid tank. a pure water supply means comprising:
It has at least a combination of an integrated control circuit section and a microcomputer section (8), detects the temperature of the etching solution by a temperature detection means, measures and calculates the rate of change in temperature over time, and calculates this in advance. The time required to obtain the desired etching thickness is calculated by comparing the data of the programmed rate of change in liquid temperature and etching speed, and when this time is reached, the control valve of the pure water supply means is opened to stop the etching liquid. The etching is stopped by substantially replacing the etching solution in the tank with pure water.

That is, in the present invention, the temperature of the etching solution increases as the etching progresses, that is, the reaction progresses, and the slope of the increase, that is, the rate of change in the solution temperature, and the etching rate, that is, the etching rate r, depend on the material to be etched. Utilizing the fact that there is a predetermined relationship, the relationship between the rate of change in the temperature of the etching solution and the etching rate r can be measured in advance, and the measured data can be input into a computer to perform the actual etching process described above. The etching rate in this etching state is calculated by comparing it with the temperature gradient measured during the process, and the time required to etch the desired thickness is calculated based on this. It controls processing time.

Embodiment An example of an automatic etching apparatus according to the present invention will be explained in detail with reference to FIG.

In the present invention, an etching liquid tank (3) containing an etching liquid (1) and provided with means (2) for stirring the etching liquid (1) is provided. This stirring device (2) includes, for example, a motor (4), which causes the liquid tank (3) to
By rotating itself, the etching liquid (11) contained in the liquid tank (3) can be agitated.

Furthermore, a means (5) for detecting the temperature of the etching liquid immersed in the etching liquid (1) is provided. This detection means (5) can use, for example, a copper-constantan thermocouple.

Further, a pure water supply means (force) is provided to control the supply of pure water to the etching liquid tank (3). This pure water supply means (force control valve (6) is constituted by, for example, a solenoid valve, and a relay ( This is controlled to open and close by energizing and deenergizing 8).On the other hand, for example, the HP-9 manufactured by Hewlett and Mother Tsucard Co., Ltd.
A data integration control circuit (9) based on a combination of 915A and HP-9815SA is provided, and a microcomputer (CPU) (1) such as HP-3421A manufactured by Hewlett-Gout Card Co., Ltd. is provided in combination. 0υ is 1 shows a display device, for example a cathode ray tube, for a monitor.

In such a configuration, when an object to be etched, for example a semiconductor wafer, is immersed in the etching liquid (1) in the liquid bath (3), etching starts, but the temperature of the liquid changes accordingly. This liquid temperature is determined by temperature detection means, that is, a thermocouple (5
) and introduced into the data integration control circuit (9). memorize it,
The temperature gradient, that is, the temperature change rate k is calculated. That is, as shown in FIG. 2, the change in the liquid temperature T with respect to the elapsed time t from the start of etching is expressed as the liquid temperature 'P1 at 60 seconds and 120 seconds.
While the gradient k is calculated by a computer based on the difference in the solution temperature T2 in minutes, the rate of change, or gradient, of the etching solution in the constituent material of the object to be etched, such as a semiconductor wafer, as shown in FIG. That is, data on the relationship with the etching rate r is experimentally obtained and programmed into a computer, and the data on the rate of change in liquid temperature, that is, the slope, and the data on the etching rate, that is, the etching rate r, are set as r.
- Calculate the time required to obtain the desired etching thickness by comparison in the data integrated control circuit section. This allows the relationship between the necessary etching margin and etching time to be determined, and when the etching time set for the margin is reached, the relay (8) is activated by the output from the r-wave integration control section (9). The electromagnetic valve (6) is opened to send pure water into the liquid tank (3) when the electric power is turned on or off, that is, when the electric current is turned on or off. In this way, pure water is fed in, and a signal is sent from the data control circuit (9) to close the solenoid valve when the etching liquid in the liquid tank (3) has been replaced with pure water. This causes the solenoid valve (6) to stop and the supply of pure water to be stopped.

Next, a specific example will be explained. For example, temperature detection means (
5) That is, if the data integration control circuit section (9) obtains the relationship between the change in liquid temperature T and the passage of time t as shown in FIG. 2 based on the output of the thermocouple (5), then
The slope includes k - (35-25)'C/min - 10°C
/minute. On the other hand, if the relationship between the gradient of the liquid temperature change of the object to be etched and the etching rate, that is, the etching rate r, is input in advance as shown in FIG.
In this case, this can be determined during eratin bleaching. Therefore, the time S until the etching stops is given as 5--(seconds) when the etching margin is μ, so if the etching margin is set to 0 and the etching margin is set to 50 μm and the etching is started, 5= -0,2
At 33 = 215 seconds, the pure water electromagnetic valve opens and etching is stopped.

In the above example, the data integration control circuit section, !
Although the microcomputer section is provided separately, it is obvious that various modifications can be made, such as using an integrated structure in which these sections are provided separately.

Effects of the Invention As described above, according to the etching apparatus according to the present invention, in the progress state of etching, under actual conditions in which various conditions determining the progress state of etching overlap, Since the progress state is detected and the etching speed time is set based on this, the etching time can be reliably set to correspond to the desired set etching thickness, and the etching margin can be reduced. It can be controlled with variations. Incidentally, when using the apparatus of the present invention, the etching margin could be kept to a small level of about ±8%.

[Brief explanation of the drawing]

Fig. 1 is a line configuration diagram of an example of an automatic etching apparatus according to the present invention, Fig. 2 is a diagram showing the relationship between etching time and liquid temperature to provide an explanation thereof, and Fig. 3 is a diagram showing the gradient of change in liquid temperature and etching speed. This is a diagram showing the relationship between (1) is an etching liquid, (3) is its liquid tank, (5) is a liquid temperature detection means, (A is a pure water supply means, (9) is a data integration control circuit section, and 0I is a microcomputer section. No. 1-7 1 -- -- 3 JP-A No. 135583 (4) Time t (sea) → I3 Amended procedure February 20, 1980 1゜ Indication of incident 1982 Patent Application No. 242544 2. Benefits of the invention: automatic etching device 3, relationship with the case of the person making the amendment Patent applicant address: 6-7-35, 6-7-35, Tokyo Parts and Omens
8+ Sony Corporation Representative Director Norio Ohga 4, Agent 1-8-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (
Shinjuku Hill) Tokyo (03) 343-5821 (Representative) (3388) Patent attorney Tei Ito 5, Date of amendment order Showa 1920, Month, Day 6, Number of inventions increased by amendment (1) In the specification, patent The scope of claims is amended as shown in Attachment 5. (2) Same, page 2, line 4, “wrapping” is corrected to “wrapping”. (3) On the same page, lines 10 and 11, ``etching to a desired thickness'' are deleted. (4) Delete "thickness, so-called" in line 12 of the same page. (5) ``Thickness'' on page 3, line 15, page 5, line 6, and page 9, line 17, are corrected to ``toshiro'' (5). (6) Same, page 4, line 4, "Data integration control circuit section" is corrected to "Data integration control section (9)". (7) Same page, line 5 “Microcomputer section (8)”
is corrected as [calculation unit tllJ. +81 Same, same line R10, "Thickness" is corrected to "Toshiro". (9) Same, page 5, line 2 [r m for computer]
, corrected to iJ. un Same, page 6, lines 7-10 ")if'-9915A・
In addition to providing the data multiplication control (2) section (9) of HP-3421A, for example, HP-3421A data multiplication control (2) section (9) is provided, and this K, for example, HP-9915A and HP-981 of HP-3421A.
5SA in combination with the arithmetic unit aα based on the combination K.'' 0υ Same, same page, lines 17-18 “Data...Circuit (9)
" should be corrected to "data accumulation control unit (9)." (13, same page, lines 18-19 “Microphone o = CPUQ
Gj is corrected as "computing unit (1 ["). 031 Same, page 7, line 4, "120 minutes" is corrected as "120 seconds". 0 滲 Same, page 7, line 5, "computer" is changed to "computing unit a" (151, same page, line 9, "rate of change" is corrected as "liquid temperature change rate". (1G) same page, lines 13-14, 1'f - ta... circuit section ' r RJ! 'frB QQI j tofJ,
iE -, r 6゜tllj Same, page 8, lines 4-5 ``Data...Circuit section (9)'' is Fr. ■ Same, same λ10 line and 9I (5-(ko1te [Kaboichi XJ circuit part], 2F unloaded city l' part). a9 Same, page 9 line 6 "Micro "Computer Department"
Corrected as "Arithmetic section." ■ Same, page 10, lines 10-11 “Data... Circulation part 1
Qυ Corrected "Microcomputer section" on line 11 of the same page to "Data integration control section-1."
Corrected as "Arithmetic section." What is claimed above is an etching liquid tank equipped with a stirring device, an etching liquid temperature detection means, a pure water supply means equipped with a control valve for controlling the supply of pure water to the etching liquid tank, and a data accumulation control section. and an arithmetic unit, the temperature detection means detects the temperature of the etching solution, measures and calculates the rate of change in temperature over time, and calculates the relationship between the rate of change in liquid temperature and the etching rate programmed in advance. Compare the data and calculate the time required to obtain the desired etching margin.
An automatic etching apparatus characterized in that the control valve of the pure water supply means is opened to stop etching at the time when the above-mentioned time has elapsed.

Claims (1)

[Claims] An etching liquid tank equipped with a stirring device, an etching liquid temperature detection means, a pure water supply means equipped with a control valve for controlling the supply of pure water to the etching liquid tank, a data integration control circuit section, and a microcomputer. detecting the temperature of the etching solution by the temperature detection means, measuring and calculating the rate of change in temperature over time;
The desired etching level is determined by comparing the temperature and rate of change of the liquid that has been prepared in advance and the etching speed.
・Inclusive 4 - Benefit? , the automatic etching apparatus is characterized in that the 0 time A is reached, and the control valve of the pure water supply means is opened to stop etching at the time when the 0 time A is reached.