JPH0373524A - Etching - Google Patents

Abstract

PURPOSE:To execute an etching operation whose controllability is good and which is uniform while an anisotropy of the etching operation is being increased by a method wherein an object to be etched is placed on the front of an electrode, a fluororesin or a heat-resistant polymer material is formed around the object to be etched and the object to be etched is etched. CONSTITUTION:A semiconductor substrate W where an aluminum silicon film (a) has been formed on its surface is placed on an electrostatic chuck 5; an etching auxiliary sheet 8 formed of a fluororesin or a heat-resistant high-polymer material is attached around the semiconductor substrate W on the electrostatic chuck 5. High-frequency electric power is applied to a support electrode 3; an etching gas is supplied through a gas introduction port 7; the aluminum silicon film (a) on its surface is etched.

Description

[Detailed Description of the Invention] [Summary] Regarding the etching method, for the purpose of increasing the etching anisotropy and performing uniform etching with good controllability, the etching object is placed on the electrode with ar11', The etching process also includes providing a fluorine resin or a heat-resistant polymer material around the object to be etched, converting the etching gas into plasma, and etching the object to be etched.

[Industrial application field]

The present invention relates to an etching method.

[Conventional technology]

In an apparatus for etching a film on the surface of a semiconductor substrate by converting etching gas into plasma, as shown in FIG. However, when the supporting electrode 52 is etched during etching, the surface of the semiconductor substrate W is contaminated by impurities generated by the etching.
The i52 is picked up by a quartz plate 51 to prevent etching.

However, according to this apparatus, since the quartz plate 51 is difficult to be etched, the etchant concentration around the semiconductor substrate W becomes high and the etching rate around the semiconductor substrate W becomes large (
There are some inconveniences.

Unfortunately, a public company has proposed using a polyolefin resin plate instead of the quartz plate 51 that surrounds the semiconductor substrate W, and using this plate to consume the etchant and uniformly enchant the entire surface of the semiconductor substrate W. This method is proposed in Japanese Patent No. 60-198821.

[Problems to be Solved by the Invention] However, when the temperature of the supporting electrode 52 is set at around 140'C, polyolefin resin becomes easily vaporized by plasma. The amount of vaporized resin coming out of the plate increases, and the etching chamber 54 is not kept under a high vacuum, which increases the isotropy of etching or the phenomenon of redeposition of etched materials.

For this reason, if over-etching is performed to remove etching residue after patterning the film on the surface of the semiconductor substrate W, problems such as thinning of the pattern and roughening of the surface of the semiconductor substrate W occur.

In this case, it is possible to reduce the amount of vaporization of the polyolefin resin by reducing the power of the high-frequency power source R applied to the supporting electrode 52, but this has the disadvantage that isotropic etching is more likely to occur due to the reduction in power. .

Furthermore, the amount of evaporation of the polyolefin resin can be lowered by lowering the temperature of the supporting electrode 51, but there are disadvantages such as difficulty in controlling the amount of evaporation, lack of reproducibility, and time-consuming temperature control.

The present invention has been made in view of these problems, and it is an object of the present invention to provide an etching method that can perform uniform etching with good controllability while increasing the anisotropy of etching.

[Means to solve the problem]

The above-mentioned problem is to place the object to be etched in front of the electrode, provide a fluororesin or a heat-resistant polymer material around the object, and use a plasma etching method to etch the object. This problem is solved by an etching method characterized by:

[For production]

According to the present invention, as shown in FIG. 1, a fluororesin or a heat-resistant polymer material is placed around the object to be etched, and this is plasma-etched together with the object to be etched. The etchant is physically or chemically consumed not only by the object to be etched but also by the fluororesin and the heat-resistant polymer material, thereby making it possible to eliminate unevenness in the etching concentration around the object to be etched.

By the way, fluorocarbon resin has heat resistance of 250 to 300
Even when heated to ℃, the amount of etching does not increase rapidly and is stable, so it does not interfere with creating a high vacuum in the etching chamber. This makes it possible to increase the anisotropy of the etching residue, and prevents the pattern width from narrowing during the time when etching residues are removed, and the substrate from becoming rough due to re-deposition of etching materials.

A similar effect can also be obtained with heat-resistant polymers.

Examples of this heat-resistant polymer include polyimide and polybenzylindazole.

When buttering the film by etching, as shown in Figure 4, the fluorine compound released from the fluororesin or the polymer of the heat-resistant polymer material may adhere to the side walls of the pattern or alienate the etchant. Therefore, it is possible to perform anisotropic etching without pattern shift by suppressing lateral etching. Moreover, it becomes easy to control the etching speed and adjust the taper angle of the pattern sidewall by changing the power of the high-frequency voltage applied to the electrode, the temperature of the electrode, and the amount of etching gas supplied.

〔Example〕

Therefore, embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram showing an example of an etching apparatus used to carry out the present invention, and reference numeral 1 in the figure is an etching chamber, in which a high-frequency electric i! A support electrode 3 connected to the support electrode 12 and a grounded counter electric bridge 4 facing the support electrode 3 are arranged to face each other.

A plate-shaped electrostatic chuck 5 on which a semiconductor substrate W is placed is attached to the center of the supporting electrode 3 facing the counter electrode 4, and a quartz plate covering the supporting electrode 3 is placed around the electrostatic chuck 5. Board 6! ! Furthermore, the counter electrode 4 is provided with a gas inlet 7 facing the center of the electrostatic chuck 5, and the etching gas introduced from the gas inlet 7 is passed between the support electrode 3 and the counter electrode 4. It is configured to turn into plasma.

Reference numeral 8 denotes an etching auxiliary plate made of a fluorocarbon resin or a heat-resistant polymer material. %
It is attached around the semiconductor substrate W on the electric chunk 5, and is configured so that its surface is etched and vaporized at the same time as the film on the surface of the semiconductor substrate W. Here, examples of the heat-resistant polymer include polyimide and polybenzimidazole.

Further, the etching auxiliary plate is not necessarily formed in an annular shape, and can be placed in a part around the substrate W.
i! ! It may also be placed in an enclosed space.

Note that the reference numeral 9 in the figure indicates an exhaust port provided in the chamber 1, and an IO port provided in the chamber 1.
indicates a temperature regulator provided in the support substrate 3.

In the above-described embodiment, the semiconductor substrate W having the aluminum silicon film a formed on its surface is placed on the electrostatic chuck 5, and the pressure inside the chamber 1 is reduced to 0 through the exhaust port 9 by a vacuum pump (not shown). .018~0
．． Set it to about 050 Torr.

Then, a high frequency power of 180 to 300 W/cd is applied to the supporting electrode 3, and the temperature of the supporting electrode 3 is adjusted from room temperature to 300° C. using the temperature regulator 10 in accordance with desired processing conditions.

Further, an etching gas containing chlorine and boron trichloride is supplied through the gas inlet 7 at approximately 50 to 1503 CCM each under selected conditions.

Under these conditions, an etchant is supplied onto the semiconductor substrate 1w, and the aluminum silicon 1lla on the surface thereof is etched.

In this case, the etchant is supplied not only to the semiconductor substrate vj, W but also to the etching auxiliary plate 8, and the fluororesin or heat-resistant polymer material constituting this etching auxiliary plate 8 is also etched. The etchant concentration around the W does not become high, and the entire surface of the semiconductor substrate W is etched almost uniformly, but
As shown in FIG. 2, the etching rate tends to decrease between the center of the semiconductor substrate W below the gas inlet 7 and its outer periphery. This is thought to be because the gas inlet 7 is provided at the center of the counter electrode 4, and the electric field strength is strongest around it.

Therefore, as shown in FIG. 2, the etching progresses in two directions: the center and the outer periphery of the semiconductor substrate, which has a great effect on shortening the etching time and greatly contributes to improving the throughput.

By the way, fluorocarbon resins and heat-resistant polymers have excellent heat resistance, and even when heated to 250 to 300°C, the etching residue does not increase rapidly and remains stable.
This does not interfere with creating a high vacuum in the etching chamber. Therefore, it is possible to create a high vacuum in the etching chamber to increase the anisotropy of etching, and remove etching residue on the semiconductor substrate by over-etching. At the same time, the pattern width does not become narrow or the surface of the semiconductor substrate 1 becomes rough.

In addition, as shown in Fig. 3, when buttering aluminum silicon lumi using resist mask R, fluorine compounds released from fluororesin (F in the figure) or heat-resistant polymer materials are used. Since the polymer (H in the figure) adheres to the sidewalls of the pattern, etching in the lateral direction of the pattern can be suppressed and etching can be performed with low pattern shift.

Moreover, by controlling the etching speed by changing the power of the high-frequency voltage applied to the support electrode 3, the temperature of the support electrode 3, and the amount of etching gas introduced, the etching rate and etching selection ratio can be changed, and the Taber angle of the pattern sidewall can be adjusted. It becomes easier to do.

Here, as shown in FIG.
When etching was performed until there was no etching residue, the resist pattern was approximately 1 µm apart.
00% transcription of VfI was confirmed.

Note that if the etching residue is removed by over-etching using a polyolefin resin as an etching auxiliary plate as in the past, the pattern width will be reduced by about 20%.
It has been confirmed that etching accuracy has decreased.

In addition, polyolefin resin has a large amount of volatilization during etching, and the pressure inside the etching chamber i is 0.15 to 0.1.
The vacuum level is approximately 0 Torr, and it has been confirmed that under the same conditions, it is advantageous to increase the degree of vacuum higher than that.

〔Effect of the invention〕

As described above, according to the present invention, a fluororesin or a heat-resistant polymer material is placed around the object to be etched. Since the etchant is etched together with the object to be etched, the etchant is consumed not only by the object to be etched but also by the fluororesin and heat-resistant polymer material, which reduces the etching concentration around the object to be etched. Bias can be eliminated.

Moreover, fluorocarbon resin and heat-resistant polymers are heat-resistant, and 2
Even when heated to 50 to 300°C, the amount of etching does not increase rapidly and is stable, so it does not interfere with creating a high vacuum in the etching chamber. For this reason,
It becomes possible to increase the anisotropy of etching by making the etching chamber a high vacuum, and it is possible to prevent the pattern width from narrowing and the substrate from becoming rough when etching residues are removed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention, FIG. 2 is an etching distribution diagram according to the present invention, and FIG. 3 is a diagram showing an etching distribution according to the present invention.
4(a) and 4(b) are sectional views showing an example of the etching state according to the present invention. FIG. 4(a) and (b) are sectional views showing the removal of etching residue according to the present invention. FIG. FIG. (Explanation of symbols) 1... Etching chamber, 2... High frequency power supply, 3... Support electrode, 4... Counter electrode, 5... Electrostatic chuck, 6... Quartz plate, 7. ...Gas supply port, 8...Etching auxiliary plate, 9...Exhaust port. 5. Electrostatic Charosk Schematic diagram showing an example of a device for carrying out the present invention (Figure j11) Applicant: Fujitsu Limited

Claims (1)

[Claims] An object to be etched is placed on an electrode, a fluororesin or a heat-resistant polymer material is provided around the object, and the etching object is etched by turning the etching gas into plasma. An etching method characterized by: