JPH06103661B2 - Asssing device - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an ashing device.

(Prior art and its problems) Advances in semiconductor technology are remarkable, and it is reported that 1Mbit and 2Mbit ICs have been developed one after another, considering that 256Kbit integrated circuits (ICs) have recently entered the mass production process. .

In such an ultra-ultra LSI, the formation area of each element, such as an active element and a wiring, is narrowed, and the interval between the elements is also narrowed. In such an IC manufacturing process, removal of unnecessary films is a usual method when manufacturing an IC by a mask process.

The ashing process using plasma is the mainstream as a means for removing such an unnecessary film.

However, as described above, in the ultra-ultra LSI, when processed in a plasma atmosphere, the damage of the wafer caused by the discharge between the elements such as the wiring is large and the yield is lowered.

As a means for removing the unnecessary film which has improved the damage of the wafer due to such a cause, there is a means for causing the ashing gas to flow to the surface of the semiconductor wafer under the irradiation of ultraviolet rays.

In the development of this ashing apparatus, the applicant of the present invention has found that good ashing can be performed without irradiating ultraviolet rays. This technique was known from Japanese Patent Application Laid-Open No. 52-20766. As a result of developing this device, when observing the ashing distribution in the entire region of the semiconductor wafer surface, there was a problem that ashing unevenness was considerably generated. As a result of various research and development as means for solving this problem, a large number of ashing gas outflow holes are provided in the vicinity of the ashing surface of the semiconductor wafer. It was found that it exerts a blocking effect on the inflow of inflowing ashing gas and causes ashing unevenness. Furthermore, the above-mentioned staying gas is convectively contacted with many ashing gas outflow surfaces having a temperature difference from the surface of the semiconductor wafer. There was also the problem that kimonos would occur.

In the mass production process, the generation of the adhered matter is liable to be peeled off due to the stacking of the adhered matter, which causes a problem that a foreign matter is generated.

(Object of the Invention) The present invention has been made in consideration of the above points, and provides an ashing apparatus which prevents adhesion of gas after ashing processing to an ashing surface of a substrate to be processed and improves an ashing rate. It is a thing.

(Means for Solving the Problems) The present invention is to obtain an ashing device in which a surface of a substrate to be processed facing the ashing surface is formed of an insulating plate.

(Advantageous Effects) According to the present invention, the surface facing the ashing surface of the substrate to be processed is made of an insulating plate, so that the surface temperature of the insulating plate can be set to almost the same temperature as the ashing surface, and a high ashing rate can be obtained. it can.

(Embodiment of the Invention) Next, an embodiment in which the device of the present invention is applied to an ashing device for a semiconductor wafer will be described with reference to the drawings.

A disk-shaped semiconductor wafer mounting table (2) is provided in the confidential container (1). The mounting table (2) has a heater (4) for setting the wafer (3) at a predetermined temperature.
Is built in.

The predetermined gap between the surface of the wafer (3) provided on the mounting table (2) configured as above and the predetermined gap is, for example, 0.2 mm to 10 m.
As set to m, an insulating plate, for example, a quartz disk-shaped glass plate (5) having a thickness of 3 mm is arranged facing the wafer (3). The glass plate (5) is suitable for application of Pyrex glass from the viewpoint of use at high temperature.

The center of the gas plate (5) and the center of the wafer (3) are arranged so as to be coaxial with each other. At the center of the glass plate (5), an ejection hole (6) for letting out ashing gas is provided. A diffusion net (7) for diffusing the ashing gas is provided in the ejection hole (6). The diameter of this ejection hole (6) is, for example, 3
× 2 mmφ is used. As shown in FIG. 2, the diffusion net (7) is provided with a plurality of holes (71) having a size of 0.5 mmφ, for example, ten holes. In this way, the semiconductor wafer asher (8) is constructed.

In this asher (8), since the gap between the wafer (3) and the glass plate (5) is narrow, the steps of loading and unloading the wafer (3) can be performed as follows. That is, the wafer (3) is loaded and mounted with the gap between the mounting table (2) and the glass plate (5) relatively widened.

This relatively widening means comprises, for example, a glass plate (5) and a part corresponding to a lid for supporting the glass plate (5), which can be moved up and down, and a system including the glass plate (5) is moved upward. Making it wider is one means.

Next, the ashing operation by the above device will be described below.

That is, by moving the system including the glass plate (5) upward,
The wafer (3) is mounted on the mounting table (2) at a predetermined position. If necessary, wafer alignment adjustment is performed. After that, the system including the glass plate (5) is moved downward to form the airtight container (1). The inside of the container (1) is exhausted by an exhaust pump (not shown) as necessary.
This exhaust may flow out before the outflow of the ashing gas. For example, the exhaust process may be preceded by 2 to 3 seconds. It is desirable that the wafer (3) is heated to an ashing temperature of, for example, 300 ° C. before the evacuation. This is because the ashing reaction causes the wafer to reach the set temperature of 300 ° C.
Since it is heated to a high temperature, it has the effect of preventing gas generation at this time.

That is, since the gap between the wafer (3) and the glass plate (5) is as narrow as 0.5 mm to 2 mm, unnecessary gas is generated during the ashing reaction against new ashing gas inflow and exhaust gas outflow after ashing. This is because it becomes an obstacle.

After such a step, the heater (4) built in the mounting table (2) stabilizes the temperature to a preset temperature, for example, 300 ° C. In this set temperature state, the ashing gas is caused to flow out from the ejection hole (6) provided in the center of the glass plate (5), and the ashing step is executed.

An example of characteristics of this ashing process will be described below.

FIG. 3 shows the ashing rate when the flow rate of O ₂ when the gas containing ozone (O ₃ ) was flown out as the ashing gas in the central portion of the wafer (3) was changed. It can be seen that the higher the O ₂ flow rate, the higher the ashing rate. This property is in O ₃ concentration 4Omegati%, gap 0.5mm between the inner surface of the wafer interior surface and the glass plate of (3) (5), the temperature 300 ° C. of the wafer (3), processing time 30 seconds, O ₂ flow rate 10l / min, 8l
Characteristics examples of / min, 6l / min, 4l / min, 2l / min, 1l / min.

The ashing rate characteristics when the gap is set to 1 mm and 2 mm are shown in FIGS. 4 (A) and 4 (B).

At this time, the temperature of the wafer (3) is 300 ° C. and the O ₃ concentration is 4 ωt.
%, The O ₂ flow rate at a treatment time of 30 seconds shows a distribution of 10 l / min and 5 l / min.

FIG. 5 shows the influence of the gap size of the characteristics shown in FIGS. 3 and 4 on the same coordinates. Figure 5 shows O ₃
Flow rate 1 l / min, wafer (3) temperature 300 ° C, O ₃ concentration 4ωt
%, The processing time is 30 seconds.

Next, FIG. 6 shows the characteristics of the ashing rate when the O ₃ concentration was changed. Figure (A) shows (B) when O ₂ flow rate is 10 l / min.
The figure shows the distribution of the ashing rate on the surface of the wafer (3) at 5 l / min.

The higher the O ₃ concentration, the higher the ashing rate, which is 10 from the center.
It is noticeable in the range of 0 mm to 40 mm. Further, the lower the O ₃ concentration, the better the uniformity over the entire surface of the wafer (3).

The gap in this characteristic is 0.5 mm, the temperature of the wafer (3) is 300
C, O ₂ flow rate 10 l / min.

Next, FIG. 7 shows the wafer distribution characteristic of the ashing rate when the temperature of the glass plate (3) was changed. The figure (A) shows an O ₂ flow rate of 10 l / min, and the figure (B) shows an O ₂ flow rate of 5 l / min. In addition,
The common conditions at this time were O ₃ flow rate of 10 l / min, O ₃ concentration of 65 g / m ³ (4.5
ωt%), the wafer temperature is 300 ° C., and the gap is 0.5 mm. It can be seen that the higher the glass temperature is, the higher the ashing rate is, especially in the area within 50 mm from the center. At this time, almost no deposit was found on the inner surface of the glass plate (3) at high temperature.

Next, the residual film distribution characteristic when the ashing time was changed was
As shown in the figure.

This characteristic is that the gap is 0.5 mm, the O ₂ flow rate is 10 l / min, and the O ₃ concentration is 4ω.
t%, the temperature of the wafer (3) is 300 ° C.

It can be seen that good ashing characteristics are obtained when the ashing time is 30 seconds or more.

Next, FIG. 9 shows the distribution characteristics on the ashing rate wafer when the ashing time is changed. The common conditions at this time are: O ₃ concentration 4ωt%, O ₂ flow rate 10 l / min, wafer temperature 300 ° C,
The gap is 0.5 mm.

FIG. 10 shows the distribution characteristics of the ashing rate over the entire surface of the wafer when there is no glass plate (5). It can be seen that the ashing rate is significantly reduced without the glass plate (5). However, a uniform ashing rate is obtained.
The ashing rate is improved at the ashing gas outlet. The condition at this time is O ₃ concentration 4
ωt%, O ₂ flow rate 10 l / min, and wafer temperature 300 ° C.

Thus, it was found that the ashing rate was improved by making the surface facing the wafer a glass surface.

In the above embodiments, the ashing of the resist film on the surface of the semiconductor wafer was explained as the ashing target substrate, but not limited to the semiconductor wafer, the step of forming the TFT circuit formed on the glass substrate of the liquid crystal display device, and the printed circuit board It can be applied to any ashing process such as ashing process.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the device of the present invention, FIG. 2 is an explanatory view of the diffusion network of FIG. 1, and FIGS. 3 and 4 are of the wafer surface when the O ₂ flow rate of FIG. 1 is changed. Ashing distribution characteristic curve diagram,
5 is an ashing distribution characteristic curve diagram of the wafer surface when the reaction gap of FIG. 1 is changed, and FIG. 6 is an ashing distribution characteristic curve diagram of the wafer surface when the O ₃ concentration of FIG. 1 is changed,
FIG. 7 is a ashing distribution characteristic curve diagram of the wafer surface when the glass temperature of FIG. 1 is changed, and FIG. 8 is a residual film distribution characteristic curve diagram of the wafer surface when the ashing time of FIG. 1 is changed, 9 is a ashing rate distribution characteristic curve diagram of the wafer surface when the ashing time is changed in FIG. 1, and FIG. 10 is an ashing rate characteristic curve diagram of the wafer surface when the glass plate is removed in FIG. is there. In the figure, 3 ... semiconductor wafer, 5 ... glass plate, 6 ... spout hole

Claims (4)

[Claims] 1. An ashing device for flowing ashing gas to a substrate to be processed for ashing, wherein an insulating plate is provided so as to face a surface of the substrate to be processed for ashing. 2. The ashing apparatus according to claim 1, wherein the ashing gas is caused to flow to the central portion of the substrate to be processed for ashing processing. 3. The ashing device according to claim 1, wherein the substrate to be processed is a semiconductor wafer. 4. The ashing device according to claim 1, wherein the insulating plate facing the ashing surface is a glass plate.