JP3411240B2 - Apparatus and method for processing semiconductor sample - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer processing apparatus and a processing method for performing processing using plasma, and more particularly to an etching apparatus or an ashing apparatus for semiconductor wafers and the like and a method thereof.

[0002]

2. Description of the Related Art The most important and difficult thing in an etching apparatus is to ensure etching uniformity. What is important in determining this uniformity is that the parameters such as plasma, gas flow, pressure, etc. are made uniform on the wafer. Especially as the development of etching equipment for 300 mm,
What is difficult with an etching apparatus for a large diameter is a method of uniformly supplying gas.

In order to make the gas flow uniform in the etching apparatus, the gas must be exhausted uniformly. However, even if the gas is exhausted symmetrically from the peripheral portion of the wafer, the gas supply position is separated from the wafer. In such a case, the gas flow or composition is likely to be nonuniform at the center and edge of the wafer. When a shower head is used, it can be placed directly on the wafer and is widely used as a method for uniformly supplying gas.

However, if the shower head is brought too close to the wafer, it becomes difficult to secure the uniformity of the pressure and the uniformity of the etching characteristics is deteriorated. This problem is particularly serious when dealing with larger diameters. For example, if a parallel plate type etching device is used and a 300 mm etching device with the same gap (distance between upper and lower electrodes or wafer and showerhead) as 200 mm is manufactured, A pressure difference occurs between the center portion and the edge portion of the wafer, and it becomes difficult to obtain uniform etching. Further, if the gap is widened, the advantage that the gas can be supplied from directly above the wafer is diminished.

Next, it is important to secure a wide process window as well as the uniformity of etching. In particular
This is a problem when etching different types of structures such as processing contact holes and wiring and trenches with a single device. This is because a difference in etching characteristics is likely to occur between the wafer center portion where a large amount of by-products (etching products) are supplied from the wafer and the wafer edge portion where there are few objects to be etched around. However, if the structure of the etching target changes, it is extremely difficult to secure the uniformity at the center and the edge by one or more processes.

[0006]

The present invention has been made to solve the above-mentioned conventional problems, and the present invention is to widen the gap in order to ensure the uniformity of the pressure in the processing tank. The gas is supplied from directly above the wafer, and the purpose is to ensure a uniform process even in an etching apparatus for large diameter. In addition, the present invention provides one or more processes, for example, a contact structure in which the surface of the wafer is almost covered with a resist and a wiring structure in which the etching area is half or more, to ensure etching uniformity. Has an aim.

[0007]

In order to achieve this, a semiconductor wafer processing apparatus according to the present invention comprises a lower electrode in a processing tank, and plasma is generated in the processing tank to form a plasma on the lower electrode. In a processing apparatus for processing a placed semiconductor wafer, a gas supply means having a gas supply port for supplying a gas for plasma is provided on the lower electrode, and the gas supply means contains the gas for plasma inside. A plurality of pipes that are circulated and have a large number of gas supply ports ,
A plurality of radial tubes arranged radially from the center, and
A plurality of ring-shaped annular pipes communicating with the radial pipe, and the above-mentioned annular
Multiple vertical pipes that communicate with the pipe and introduce or exhaust the above gases
It is constructed by combining a tube, and wherein the distribution corresponds to the surface of the semiconductor wafer is composed of a large number of the gas supply port of the wide region is adjusted so as to supply the gas.

According to another semiconductor wafer processing apparatus of the present invention, the radial pipe, the annular pipe and the vertical pipe are hollow.
It is characterized in that it is in the shape of a cup .

[0009]

According to another semiconductor wafer processing apparatus of the present invention, the gas supply port of the gas supply means is a semiconductor wafer.
Optimal gas supply at the center and edge of the wafer
It is characterized in that it is adjusted so that

Further, in another semiconductor wafer processing apparatus of the present invention, the gas supplier has the gas supply port and the half
Equipped with control means for variably controlling the distance to the conductor wafer
It is characterized by that.

Further, processing of the semiconductor wafer of the present invention
The device is equipped with the plasma from the top or side of the processing tank.
A gas introduction means for introducing a gas for use
To do.

[0013]

[0014]

[0015]

First Embodiment FIG. 1 is a sectional view showing a schematic structure of an etching apparatus according to an embodiment of the present invention. As shown in FIG. 1, this etching apparatus includes a chamber 10 (processing tank).
A lower stage 11 also serving as a lower electrode installed in the lower part of the chamber, a gas supply part 12 having a gas supply port vertically movable in the chamber, and an upper electrode 13 arranged in the upper part of the chamber. ing. A wafer 15 (semiconductor sample) is placed on the lower stage.
A control unit 14 is arranged below the lower stage 11. The control unit 14 includes a mechanism for moving the gas introduction unit 12 up and down, and includes a power introduction mechanism, an electrostatic chuck-related, a wafer up-and-down mechanism, a wafer temperature adjustment mechanism, and the like.

A discharge is generated in the chamber 10 by introducing power from the upper electrode 13 or an antenna, and plasma is generated. This plasma gas etches the wafer 15 placed on the lower stage 11.

FIG. 2 is a perspective view for explaining a specific structure of the gas introduction part 12 in FIG. Gas supply unit 1
2 is a radial tube 2 which is arranged radially from the center and serves as an axis.
1, a ring-shaped annular pipe 22, and a vertical pipe 23 also serving as a support
The plurality of tubes are in communication with each other so that the gas for plasma is conducted therethrough. Radial tube 21, annular tube 2
The number and arrangement of the two and the vertical tubes 23 can be arbitrarily adjusted. However, the interval of vertical adjacent tube 23 and the wafer diameter or less so that it can insert the wafer 15. The wafer 15 is placed directly below the gas supply unit 12 by the transfer robot.

The vertical pipe 23 is connected to the actuator of the controller 14 and can be moved up and down according to a recipe. The radial pipe 21, the annular pipe 22 and the vertical pipe 23 are hollow pipes, through which the process gas flows. Gas introduction is 1
The gas is discharged from one or several vertical tubes 23, and the gas is similarly discharged from one or several vertical tubes 23.

FIG. 3 is a partially enlarged view of the radial tube 21 or the annular tube 22 as seen from the wafer side. As shown in the figure,
On the wafer side of these pipes, gas ejection holes 2
4 (gas supply port) is opened. The number (density) of the holes 24 can be arbitrarily adjusted, and can be changed between the center portion and the edge portion in order to improve the etching uniformity on the wafer surface. Also, the size of the hole 24 can be changed depending on the center and the edge. Further, the holes 24 may be formed in a diagonally downward direction, a horizontal direction, or an upward direction (toward the opposite side of the wafer, toward the upper electrode) other than directly below.

Next, the specific structure and usage of this etching apparatus will be described. As an example, an example of a parallel plate type oxide film etching apparatus for a 300 mm wafer capable of applying power of different frequencies to the upper and lower electrodes will be given. An example of etching conditions is as follows. Pressure: 40mTorr, Gas flow rate: C4F8 = 50sccm, Ar = 300sccm, CO = 200sccm,
O2 = 30sccm Power: Upper electrode 3000W (13.56MHz), Lower electrode 100
0W (400kHz) It is also possible to ground the lower part and add a magnetic field Gap: 10cm Gas supply height: Variable from a few millimeters to 10cm

In the case of etching under the above conditions, since the gap is sufficiently wide, there is no problem in the uniformity of pressure, and there is no fear of damage or electron shading because the distance from the high electron temperature plasma near the electrode to the wafer is long. When etching is to be performed at a high rate or under conditions in which ions (charged particles) are increased with respect to neutrals such as radicals, the gas supply unit is set to the highest position or the position of the upper electrode. In this case, the conditions are similar to those of the conventional shower head etching. On the other hand, (a) if you want to improve the non-uniformity of the center and the edge, such as improving that the depot property is too strong at the center or reducing the selection ratio at the edge,
Alternatively, when it is desired to improve the selectivity with respect to the resist or SiN or Si by etching with a gas that does not cause dissociation, the height of the gas supply unit is set to, for example, 10 mm.

As described above, the gas supply unit 12 is made of a material having a plasma resistance such as quartz (Quartz) directly above the wafer 15 and has a shower head shape that does not shield the plasma. Since this gas supply unit 12 is not a flat plate, but consists of a pipe through which gas can pass, it can be placed in the plasma, and since the pipe has many holes, it is possible to uniformly supply gas to the wafer. Is. Further, the gas supply unit 12 can be moved up and down according to the recipe, and even if the structure to be etched is changed, the gas supply unit 12 can be set to the optimum height according to the recipe, so that it can be used for any structure or process. Uniform etching is possible.

Next, the operation and action of this etching apparatus will be further described. Generally, there are many byproducts at the center of the wafer, and the depositability is stronger than that at the wafer edge, for example. The best way to reduce this effect is to supply fresh gas from the immediate vicinity of the wafer, but this can be achieved by using this structure. In other words, the gas with a flow rate above a certain level is supplied to the wafer center from the immediate vicinity to expel the gas with a strong depot component with a large proportion of biproducts, and replace it with fresh gas.
The difference in gas composition from the wafer edge can be reduced.

Depending on the structure of the object to be etched, if it is desired to enhance this action, the gas supply part may be brought closer to the wafer by a recipe. The height of the gas supply section greatly affects the degree of gas dissociation. That is, by the time the ejected gas reaches the wafer, it is decomposed into low-order molecules, radicals, and ions in the plasma, but the degree of decomposition is small when the distance from the wafer is short. From this point of view, the optimum height is set for each structure.

As described above, according to the present embodiment, the present invention allows the gap to be widened in order to ensure the uniformity of the pressure in the chamber, while the gas is supplied by the gas supply unit. Since the process is performed right above the wafer, it is possible to secure a uniform process even in an etching apparatus corresponding to a large diameter. In addition, according to this embodiment, one or more processes, for example, both a contact structure in which the surface of the wafer is almost covered with resist and a wiring structure in which the etching area is half or more,
Etching can be performed while ensuring uniformity.

Second Embodiment FIG. 4 is a sectional view showing a schematic structure of an etching apparatus according to another embodiment of the present invention. In this embodiment,
The gas supply unit 12 described in the first embodiment and its control mechanism are added to the conventional etching apparatus that supplies gas from the upper portion or side wall of the chamber 10. Since the reference numerals in the figure are the same as those in FIGS. 1 to 3, detailed description thereof will be omitted. In this etching apparatus, reference numeral g in the figure
As shown in FIG. 5, gas is supplied from the upper portion or side wall of the chamber 10 as in the conventional case. Further, gas is supplied from the gas supply port 23 of the gas supply unit 12 that is connected to the actuator and can be moved up and down according to the recipe, as indicated by the symbol h in the figure. As described above, if the gas is supplied into the chamber 10 by the two methods, the amount of gas supplied and the distribution thereof.
Also, the possibility of controlling the gas velocity and the like can be further increased.

In this case, it is also possible to change the kind of gas by the gas flow g and the gas flow h. For example, total gas flow rate: C ₄ F ₈ = 50sccm, Ar = 300sccm, CO = 200sccm, O
Of ₂ = 30 sccm, C ₄ F _{8 which} does not want to promote dissociation may flow from the plasma as the gas flow h, and other gas may flow from the upper part of the chamber 10 as the gas flow g.

Further, for example, a material related to etching is supplied from the gas supply port 23 of the gas supply unit 12 for the purpose of increasing the selection ratio, for example, in the plasma immediately above the wafer 15. This is the case when SiC, Si, SiN, or C is used as a consumable material for the entire gas supply unit or the wafer surface.

As described above, also in this embodiment, the structure is such that the gas can flow through several concentric rings and several pipes connecting them, and the gas is spouted onto the wafer through the many holes formed in the pipe. Make a hole. As a result, the gas for plasma is supplied from the plasma generation region in the immediate vicinity of the wafer, that is, only the gas supply part can be brought close to the wafer while keeping the upper plate that determines the plasma space.

Further, the height of this gas introduction can be made variable by the recipe, so that the margin for adjusting the uniformity is widened. Furthermore, the gas can be introduced from a large number of holes in a wide area as in the conventional shower head, and since it is in the immediate vicinity of the wafer, adjusting the number of holes, etc., allows the gas to be introduced at the center and edge of the wafer. It becomes easy to optimize the supply amount. This enables uniform etching of large diameter wafers. Quartz is the most suitable material, but by using C, Si, or SiC, it is possible to have scavenging effects such as F directly on the wafer. Also in this embodiment described above,
It goes without saying that the same effect as that of the first embodiment is achieved.

[0031]

As described above, the etching apparatus of the present invention has the following effects. (1) The uniformity of the etching rate within the wafer can be improved. (2) The uniformity of the etching selectivity in the wafer can be improved. (3) The uniformity of the etching shape in the wafer can be improved. (4) The microloading effect can be reduced. (5) It is possible to improve the selection ratio with respect to resist and base. (6) Charge-up damage can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic structure of an etching apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view for explaining a specific structure of a gas supply unit in FIG.

FIG. 3 is a partially enlarged view of a radial pipe or an annular pipe of the gas supply unit in FIG. 2 seen from the wafer side.

FIG. 4 is a sectional view showing a schematic structure of an etching apparatus according to another embodiment of the present invention.

[Explanation of symbols]

10 chambers (processing tanks) 11 Lower stage (lower electrode) 12 Gas supply section 13 Upper electrode 14 Control unit 15 wafers (semiconductor sample) 21 Radial tube 22 annular pipe 23 Vertical pipe 24 holes (gas supply port)

Claims (5)

(57) [Claims] 1. A processing apparatus comprising a lower electrode in a processing tank, wherein plasma is generated in the processing tank to process a semiconductor wafer placed on the lower electrode, wherein a plasma is formed on the lower electrode. A gas supply means having a gas supply port for supplying the gas, the gas supply means is a plurality of pipes through which the plasma gas is circulated and which has a large number of gas supply ports.
The radial tubes arranged radially from the center, and
A plurality of ring-shaped annular pipes communicating with the radial pipe, and
Plural communicating with the annular pipe and introducing or discharging the above gas
And a vertical pipe, and is configured to supply the gas from a large number of gas supply ports in a wide area whose distribution is adjusted corresponding to the surface of the semiconductor wafer. Semiconductor wafer processing equipment. 2. The radial pipe, annular pipe and vertical pipe are hollow.
The semiconductor wafer processing apparatus according to claim 1, wherein the semiconductor wafer processing apparatus has a pipe shape . 3. The gas supply port of the gas supply means is a semiconductor.
The gas supply amount at the center and edge of the body wafer
Adjusted to be optimized.
Or the semiconductor wafer processing apparatus according to 2. 4. The gas supply means is provided with the gas supply port.
Control means for variably controlling the distance to the semiconductor wafer
The semiconductor wafer processing apparatus of claim 1, further comprising: 5. The process is performed from the top or side of the processing tank.
It was equipped with gas introduction means for introducing gas for plasma
The semiconductor wafer processing apparatus according to claim 1 , wherein the semiconductor wafer processing apparatus is a semiconductor wafer processing apparatus.