JPH02228486A - Etching method and device - Google Patents

Abstract

PURPOSE:To simultaneously attain the acceleration of etching and the formation of a specular etched surface by wet-etching a body to be etched under heating by irradiation with IR. CONSTITUTION:An IR heater 11 is set above the cover 2 of an etching vessel 1 and the surface of a body 4 to be etched is heated by irradiation with IR through the cover 2. An electric resistance heater 12 may be interposed between the body 4 to be etched and a support stand 3 as a heating means. When the temp. of the body 4 to be etched is made higher than that of an etching soln. 7, reactions by which reactive ions adsorbed on the surface of the body 4 accept electrons from the body 4 and simultaneously the contact surface part of the body 4 dissolves as ions are accelerated to increase the etching rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an etching method that can be used for chemical etching of metals, semiconductor materials, etc. with high efficiency and high quality of processed surfaces, and an apparatus used therefor.

[Conventional technology]

In so-called wet etching, which uses a chemical liquid to etch the surface of a workpiece, conventionally the concentration and temperature of the etching liquid in a container are kept constant, and the etching process is carried out by means such as rotating a groove 2 or using ultrasonic waves. A commonly used method is to immerse a workpiece in an etching solution for a certain period of time while stirring the etching solution. In this case, the etching solution is stirred to obtain the following two effects. One is the effect of suppressing local changes in acidity and temperature within the entire etching solution, which prevents the etching rate from becoming non-uniform over the entire processed surface. The other reason is that the diffusion layer existing at the interface where the etching solution is in contact with the etching surface is not thinned by the liquid flow generated by stirring, and reactive ions are supplied from inside the etching solution to the etching surface and etching is carried out from the etching surface. This has the effect of improving processing characteristics such as etching speed and surface condition as a result of rapid removal of reaction products into the liquid.

Therefore, such conventional wet etching has the advantage that processing characteristics such as etching speed and processed surface condition can be stably reproduced by keeping etching conditions such as liquid concentration, temperature, and stirring method constant. However, when the etching rate is increased by adjusting the concentration and temperature of the etching solution, the surface roughness and flatness deteriorate, and on the other hand, in order to improve the surface condition, it is necessary to increase the etching speed. The drawback was that it wouldn't make a sound unless it was lowered.

In general, when the etching rate is low, the amount of reactant ions supplied and the amount of reaction product removal lids are also small, so conventional stirring methods such as the rotation of the globber or ultrasonic waves described above can be used, but the etching rate increases. In such cases, the amount of reactant ions supplied and the amount of reaction products removed increase, so that the above-mentioned conventional stirring method has a weak stirring effect and cannot be used. As a result, the etching rate becomes non-uniform and the surface roughness and flatness of the processed surface deteriorate.

In order to avoid such problems, we have applied for the
In No. 219935, an etching apparatus and an etching method using the same as shown in FIG. 5 were proposed. In Figure 5, 1 is an etching container, 2 is a container cover.
3 is a workpiece support stand, 4 is a workpiece, 5 is a workpiece fixing frame, 6 is an etching gap formed between the container cover 2 and the workpiece 4, 7 is an etching liquid, 8 is a gas, 9 is gas 8
Round mixing mixer 10 that mixes and etching liquid 7
is a bubble-containing etching liquid containing bubbles caused by gas 8.

The flow of the etching solution is such that the etching solution 7 is sent by a pressurized pump from a liquid tank (not shown) in which the etching solution 7 is stored, and is introduced from one end of the etching container 1 into a mixing mixer 9 together with a gas 8 to form a mixture containing air bubbles. The etching liquid 10 is circulated through the etching gap 6, leaving the etching container 1 and returning to the liquid bath.

Because the etching device has such a configuration, when the etching liquid 10 containing air bubbles is forcibly fed into the etching gap 6, it becomes a high-speed flow with an extremely complicated flow pattern on the processing surface of the workpiece 4. 9. Great stirring effect can be obtained. Therefore, the etching gap 6 here should be as narrow as possible in order to achieve high-speed flow. However, in actual etching, even when such an etching device is used, there is a limit to the improvement of the etching speed and the condition of the machined surface due to limitations such as the material of the workpiece and the size of the etching device.

[Problem to be solved by the invention]

In order to increase the etching speed and improve the condition of the machined surface, it is necessary to control the concentration and temperature of the etching solution, but these fluctuation factors have limits such as maximum solubility and boiling point, so etching Increasing the speed is practically difficult.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a new etching method and apparatus for use in the method, which can simultaneously increase the etching speed and make the processed surface mirror-finished in wet etching using a chemical solution.

[Means to solve the problem]

In order to achieve the above object, the etching method of the present invention etches the workpiece while heating it by irradiating the workpiece with infrared rays or bringing the workpiece into contact with a high-temperature body. It is characterized by

Another feature of the present invention is that in order to realize such an etching method, an etching apparatus is used which is equipped with a heating means for heating the processed surface of the workpiece.

[Effect]

According to such an etching method and etching apparatus, it is possible to raise the temperature of the processed surface of the workpiece without increasing the temperature of the etching solution, so that the etching speed and processing speed can be increased compared to the conventional etching method. Machining characteristics such as surface condition can be improved.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a first embodiment in which an infrared heater is used as a heating means for the processing surface of a workpiece.

As an etching method for etching the processed surface of the workpiece by exposing it to an etching solution, a method using a high-speed mixed flow using a bubble-containing etching solution as shown in FIG. 5 was employed. Among the first factors, the same parts as those in FIG. 5 are given the same reference numerals, and the explanation thereof will be omitted. In the case of Fig. 1, the infrared heater 1 is installed on the upper side of the container cup 4-2 of the etching container J, and can heat the processed surface by irradiating infrared rays onto the processed surface of the workpiece 4 through the container container 2. It looks like this. Therefore, in this embodiment, quartz glass with good light transmittance is used as the container cover 2. Further, the workpiece 4 is a silicon single crystal substrate, and the etching liquid 7 is potassium hydroxide (
KOH) is used.

Regarding the etching method using a high-speed mixed flow using a bubble-containing etching liquid IO without a heating means, see Section 5.
This is the same as the conventional technique shown in the figure (FI Application No. 63-219935).

In this embodiment, when infrared rays are irradiated from above the container force 2, depending on the nozzle of the infrared heater 1,
The temperature of the workpiece 4 can be made higher than that of the etching liquid 7. For example, the workpiece support stand 3 is in a hollow state,
A silicon single crystal substrate, which is the workpiece 4, is fixed on the upper surface, and a thermocouple is brought into contact with the lower surface of the opposite side, and the temperature of the silicon single crystal substrate is measured when infrared rays are irradiated. When the temperature of the etching solution 7 was 50°C and 80°C, the temperatures of the silicon single crystal substrate were 90°C and 115°C, respectively. In this case, the thickness of the workpiece support 3 in contact with the workpiece 4 is α5■.

FIG. 2 shows the relationship between the infrared heater power and the etching rate in the first embodiment, where the horizontal axis is the infrared heater power. The vertical axis is the etching speed. Here, graph A indicates that in order to efficiently transmit the energy of the infrared heater 1 to the processing surface of the workpiece 4, when the workpiece 4 is attached to the inner surface of the container cover 2, the graph 27B is Place the object 4 on the workpiece support stand 3 as shown in Figure 1.
When the infrared heater 1 is installed in the infrared heater 1 and part of its energy is taken away by the etching liquid 7, etc., resulting in poor heat transfer efficiency, point C is when no heating means is used, and point C is when the conventional immersion method is used. The figure shows the etching speed. When using the heating means according to the present invention, both graph A and graph B
The etching speed improves as the infrared heater power increases, and especially in the case of graphite heater power L2kW.
The etching speed was more than three times that of the conventional immersion method and more than twice that of the case without heating means, and at the same time, the etched surface was mirror-like with a surface roughness of 2 μm or less. Furthermore, when graphs A1, G2, and B are compared, the difference in energy transfer efficiency clearly appears. In this way, by making it possible to have a large stirring effect on the etching surface due to the high-speed mixed flow using the bubble-containing etching liquid IO, and to raise the temperature of the processed surface of the workpiece 4 higher than the liquid temperature by infrared irradiation, We were able to achieve high-speed etching and mirror-finished processed surfaces due to high-speed etching.

As in this embodiment, when the workpiece 4 is heated to increase its temperature, the reactive ions adsorbed on the surface of the workpiece 4 receive electrons from the workpiece 4 (reduction reaction), and at the same time A reaction (
As a result, the etching rate increases. In this way, the method of directly heating the workpiece 4 is as follows:
This is particularly effective when the etching rate is the rate-limiting reaction, and it is also effective because it heats only the areas necessary for etching and there is no need to raise the temperature of unnecessary areas (e.g. the etching bath or other areas). It is also superior in terms of efficiency.

In the first embodiment, an infrared heater 1 was used as a heating means for the workpiece, but it is not necessary to use an infrared heater for this purpose.

FIG. 3 shows a second embodiment in which an electric resistance heater 12, which is a high-temperature body, is used as a heating means in place of the infrared heater power. In FIG. 3, the same parts as in FIG. The explanation will be omitted. In the case of FIG. 3, the electric resistance heater 12 was installed between the workpiece 4 and the workpiece support 3.

The etching gap 6 was 1 m, and other conditions were the same as in the first embodiment.

FIG. 4 shows a third embodiment in which an electric resistance heater 12 is used, and the workpiece support 3 itself is used as a high-temperature body. Therefore, the electric resistance heater 12 is attached to the inner surface of the hollow workpiece support 3, and the workpiece 4 is attached to the outer surface of the workpiece support 3. In Figure 4, 1st
The same parts as those in the figures are given the same reference numerals and the explanation thereof will be omitted.

In the case of FIG. 4, when the temperature of the electric resistance heater 12, which is a heating element, rises, the heat is transferred to the workpiece support 3 and raises its temperature, so the workpiece support 3 becomes a high-temperature body. Become. When the temperature of the workpiece support 3 rises, this is in turn transmitted to the workpiece 4, increasing its temperature. Therefore, the thickness of the workpiece support 3 between the workpiece 4 and the electric resistance heater 120 is set to α5■ in order to improve the thermal energy transfer efficiency. In the case of this etching as well, there was only one etching gap 6, and the other conditions were also the same as in the first embodiment.

Since the basic etching conditions are the same as in the first example, the second and third examples also have a large stirring effect on the processed surface and a lower substrate temperature. As a result, the etching speed was increased and the machined surface became mirror-finished due to the high-speed etching.

Furthermore, it goes without saying that even when the etching method using the heating means of the present invention is applied to the conventional immersion method, it is possible to increase the etching speed and to make the processed surface mirror-finished by high-speed etching.

〔Effect of the invention〕

As explained above, in the etching method using the etching apparatus according to the present invention, the temperature of the etching liquid and the temperature of the workpiece can be set independently. Even if
The etching rate can be improved by increasing the temperature of the workpiece. Therefore, in wet etching using a chemical solution, seven things can be achieved by simultaneously increasing the etching speed and making the processed surface a fiR surface.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an etching apparatus using a high-speed mixed flow using an infrared heater to heat a workpiece, which is a first embodiment of the present invention, and FIG. 2 is a diagram showing an etching device according to a first embodiment of the present invention. FIGS. 3 and 4 are characteristic diagrams showing an example of the relationship between the infrared heater non-warmer and the etching speed according to the method, and FIGS. FIG. 5 is a block diagram showing an etching apparatus using a high-speed mixed flow in the case of a conventional etching apparatus using a high-speed mixed flow. FIG. l...Etching container, 2...Container cover 3...
・Workpiece support stand, 4... Workpiece, 5... Workpiece fixing frame, 6... Etching gap, 7 River etching liquid, 8... Gas, 9... Mixing mixer 1o ... Etching liquid containing bubbles, 1. ... Infrared heater, 12.
...Electric resistance heater. 1: Processing/etching story 2: Container cover 3 - Workpiece support 4: Workpiece 7: Etching liquid 8: Gas 1 9: Foot stand mixer 10: Bubble-containing processing/etching liquid 11: Infrared heater Figure 1 Figure Figure Figure Figure

Claims (3)

[Claims] (1) An etching method in which the processed surface of a workpiece is etched by exposing the processed surface to an etching solution, the etching method comprising etching the processed surface while irradiating the processed surface with infrared rays. (2) An etching method in which the processed surface of the workpiece is etched by exposing it to an etching solution, the etching method comprising etching the workpiece while it is in contact with a high-temperature body. (3) An etching apparatus that etches the processed surface of a workpiece by exposing the processed surface to an etching solution, the etching apparatus comprising a heating means for heating the workpiece.