JPH1012561A - Semiconductor treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly treat the entire wafer surface with little dust by treating the wafer in a first reactor, taking it out, inserting it in a second reactor, changing the orientation of the wafer, relative to a mean gas flowing direction between the first and second reactors and treating it similarly as before. SOLUTION: A wafer 1 is carried from a cassette chamber 2 into a reactor 3 by a wafer conveyer 5 with its orientation flat, being the most remote from the conveyer 5, a reactive gas is flowed at a specified rate from the near side of the conveyer 5 to the far side for treating the wafer 1. Then the wafer is taken out of the reactor 3 and inserted into a reactor 5 while the orientation flat is nearest the conveyer 5. Nearly the same condition is held in the reactor 4 as in the reactor 3, while the reactive gas is flowed at nearly the same rate as in the reactor 3, from the near side of the conveyer 5 to the far side. This improves the uniformity of the treatment of the wafer and prevents production of dust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor processing apparatus.

[0002]

2. Description of the Related Art At present, in a semiconductor heat treatment process such as oxidation, annealing, and thermal CVD, a batch type apparatus (vertical diffusion apparatus, vertical CVD apparatus) for processing a plurality of wafers at once is mainly used. However, in order to cope with high integration of semiconductor devices, formation of very thin oxide film or shallow diffusion layer of about several nm and prevention technology of natural oxide film are indispensable. Is suitable for short-time processing of several minutes or less, and can easily deal with cluster units and large-diameter wafers. It processes one wafer at a time or processes several wafers at a time. Pseudo-single-wafer devices are advantageous. Also, in a line in which a batch-type apparatus and other single-wafer-type apparatuses (such as an etching apparatus and a sputtering apparatus) are mixed, it is difficult to manufacture an element in a short time, and a single-wafer-type heat treatment apparatus is indispensable. Is coming.

In a single-wafer heat treatment apparatus, there is a means for rotating a wafer as an example to make the processing performed on the wafer uniform over the entire surface of the wafer. For example, electronic material 19
March 1995 pp. As shown in 67-70, the wafer placed on the support is rotated together with the support. This is because if the gas is flowing in one direction on average to the apparatus without rotating the wafer, the degree of processing of the wafer is different between upstream and downstream of the flow, but by rotating the wafer, The difference between the upstream and the downstream is canceled out, and the processing performed on the wafer is made uniform.

[0004]

A semiconductor processing apparatus having a drive unit such as a rotating mechanism in a reaction furnace generates more dust than a device without a drive unit. However, from the viewpoint of the uniformity of the processing performed on the wafer over the entire surface of the wafer, the method of rotating the wafer has a remarkable effect. Further, if a wafer rotation mechanism is provided to obtain uniformity, the number of wafers that can be processed at one time tends to be limited to one, and the number of wafers that can be processed in a given time is reduced.

The reason that the provision of the rotation mechanism tends to limit the number of wafers that can be processed at one time to one wafer is as follows. Here, since it is intended to achieve the purpose of manufacturing a semiconductor element in a short time, a batch-type apparatus requiring a long processing time is not targeted. In a single-wafer processing apparatus in which one process is performed in a short time, a lamp is often used to heat a wafer to a predetermined temperature. In heating using a lamp, it is important that the reaction furnace is made of a transparent material such as quartz and that the light of the lamp efficiently reaches the wafer.
Therefore, only the wafer and the wafer support are heated by the lamp, and the walls of the reactor made of a transparent material are hardly heated. It is assumed that the wafer on the support is heated from the upper part and the lower part has a rotating mechanism. Here, if two or more wafers are stacked, the light of the lamp does not reach one wafer by one wafer, and uniform heating by the lamp becomes impossible. As another heating method, there is a method of heating the entire reaction furnace. In this method, the reaction furnace is covered with a heat insulating material so that the heat is dissipated as little as possible, and the reaction furnace is heated by flowing an electric current through a resistance wire. However, even with this method, when processing a plurality of wafers at the same time and trying to rotate them further, a part of the heat insulating material is cut out,
Since heat is dissipated therefrom, it becomes difficult to uniformly heat the entire surface of the wafer. Therefore, in order to process a plurality of wafers at once, it is necessary to eliminate the rotation of the wafers.

An object of the present invention is to provide a semiconductor processing apparatus and a semiconductor processing method in which processing performed on a wafer by a single-wafer apparatus is uniform over the entire surface of the wafer, generates less dust, and increases the number of processed wafers in a given time. It is in.

[0007]

The above object can be attained by processing a wafer in a reactor, removing the wafer, inserting the wafer into another reactor, and performing substantially the same processing as described above. . At this time, the direction of the wafer with respect to the average gas flow direction in the reactor used for the first process and the direction of the wafer with respect to the average gas flow direction in the reactor used for the next process are different. Is important. Alternatively, the problem can be solved by processing the wafer in a reaction furnace, taking out the wafer, changing the orientation of the wafer there, inserting the wafer into the original reaction furnace, and performing substantially the same processing as described above. Further, since a wafer rotation mechanism is not provided in the reaction furnace, a plurality of wafers can be processed at one time, and the number of wafers that can be processed in a given time can be increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. Wafer 1
Are transferred into the cassette chamber 2 in cassette units, are transferred from the cassette chamber by the wafer transfer device 5 according to the number of sheets that can be processed in the reaction furnace 3 or the reaction furnace 4, and are inserted into the reaction furnace 3. The orientation of the wafer 1 is set so that the orientation flat is farthest from the wafer transfer device 5. In the reaction furnace 3, the wafer 1 is maintained at a predetermined pressure, the wafer 1 is heated to a predetermined temperature, and a predetermined amount of reactive gas is flowed from a portion closer to the wafer transfer device 5 to a portion farther from the wafer transfer device 5. Process. After finishing this process, the wafer 1 is taken out of the reaction furnace 3 by the wafer transfer device 5 and inserted into the reaction furnace 4. The orientation of the wafer 1 is set so that the orientation flat is closest to the wafer transfer device 5. In the reaction furnace 4, a reactive gas flows at a flow rate substantially the same as the flow rate of the reaction furnace 3 from a position closer to the wafer transfer device 5 to a position farther from the wafer transfer device 5 while maintaining conditions substantially equal to pressure and temperature conditions in the reaction furnace 3. Thus, the wafer 1 is processed again. Before the processing of the wafer 1 is completed and before the wafer 1 is taken out of the present apparatus, it may be necessary to put the wafer 1 in the cooling chamber 6 or 7 and to lower its temperature appropriately. The capacity and number of cooling chambers may be determined according to the processing speed of the wafer, and the number of cooling chambers and the number of reaction furnaces do not necessarily have to match.

The uniformity of processing on the wafer 1 is considered as follows. The orientation flat of wafer 1 is
Is located at the most downstream side of the wafer 1 in the processing in the above, whereas the processing in the reaction furnace 4 is located at the most upstream side of the wafer 1, and the effects of the upstream and the downstream are substantially offset. Will be. Considering the above process as CVD, the growth rate g (x) of the CVD film on the wafer is determined by the concentration C (x) of the source gas.
When it is proportional to, the uniformity q of the growth rate of the CVD film on the wafer can be considered as follows. Here, it is assumed that the wafer 1 is a perfect circle, the flow can be approximated in one dimension, and only the growth rate distribution in a direction parallel to the flow (x direction) is considered. The origin of x is set at the most upstream position of the wafer 1. Assuming that the average flow velocity is u, time t can be converted to t = x / u, and g (x) ∝C (x) = C (0) exp (−kx / u)
It is. k is the rate at which the raw material disappears per unit time. The uniformity q is defined as q = (maximum value of g−minimum value of g) / (g
Is defined as (maximum value of g + minimum value of g), the uniformity q ₁ when treated only in the reactor 3 is

[0011]

Q ₁ = (1−exp (−kd / u)) / (1 + exp (−kd / u)) (Equation 1) Here, d is the diameter of the wafer. On the other hand, according to the present embodiment, the uniformity q ₂ is

[0012]

## EQU2 ## q ₂ = (1 + exp (−kd / u) −exp (−kd / 2u)) / (1 + exp (−kd / u) + exp (−kd / 2u)) = ((1−exp (−kd / 2u) / (1 + exp (−kd / 2u)) ² (Equation 2) At this time, if a ratio of q ₁ and q ₂ is taken for comparison,

[0013]

## EQU3 ## q ₁ / q ₂ = (1 + exp (−kd / 2u)) ³ / (1 + exp (−kd / u)) / (1−exp (−kd / 2u)) = (1 + exp (−kd / 2u) )) ² / (1 + exp (−kd / u)) * (1 + exp (−kd / 2u)) / (1−exp (−kd / 2u)) (Equation 3) Under the condition of 0 <k <∞, u> 0,

[0014]

Q ₁ / q ₂ > 1 (Equation 4) It can be seen that the present invention increases the uniformity of processing on the wafer.

Next, another embodiment of the present invention will be described. In this embodiment, after a predetermined process is performed in the reaction furnace 3, the wafer 1 is taken out of the reaction furnace 3 by the wafer transfer device 5, and the direction of the wafer 1 is changed and inserted into the reaction furnace 3 again. The processing is substantially the same as that described above, and the processing of the wafer 1 can be made uniform even with a single reactor.

In both the first embodiment and the second embodiment, the processing in the reactor, the removal of the wafer, the change of the orientation of the wafer outside the reactor, and the insertion of the wafer into the reactor may be repeated a plurality of times. It is possible, by changing the direction of the wafer little by little,
It is also possible to obtain substantially the same effect as rotating a wafer in a reaction furnace.

At this time, the degree of dust generation differs greatly between rotating the wafer inside the reaction furnace and rotating the wafer outside the reaction furnace. Usually, in a reaction furnace, a reactive gas is introduced to process a wafer, so that parts other than the wafer are exposed to an environment substantially equal to that of the wafer in the reaction furnace.
That is, when a film is grown on a wafer, the film also grows on a portion other than the wafer in the reaction furnace, and therefore, the film grows on a mechanism for rotating the wafer. If the wafer is rotated with the film adhered to the rotation mechanism, the adhered film is peeled off, causing dust.

In the present invention, however, the rotation mechanism is provided outside the reaction furnace, and is separated from the reaction furnace by a gate valve or the like when processing the wafer in the reaction furnace. Therefore, according to the present invention, there is no generation of dust involved in at least the processing of the wafer in the reaction furnace and the rotating mechanism in the reaction furnace.

Although the semiconductor processing apparatus shown in FIG. 1 has only two reactors, the same effect can be obtained by using more reactors. Also, in FIG. 1, the processing in the reaction furnace 3 and the processing in the reaction furnace 4 are performed almost simultaneously on different wafers, and further, the sequence of the wafer transfer and the processing is considered so that the waiting time of the wafer is minimized. As a result, efficient use of the reactor becomes possible.

In the above-described embodiment, since the wafer rotating mechanism does not exist in the reaction furnace 3 or the reaction furnace 4, the reaction furnace 3 or the reaction furnace 4 can process two wafers at a time. . FIG. 2 shows an example of a sectional view of the reaction furnace 3 at this time. In the reaction furnace 3, two wafers are placed on a wafer support 8 so as to be stacked horizontally. Wafer 1
Are heated by heaters 9 located above and below. Also,
The reactor 3 and the heater 9 are covered with a heat insulating material 10 so as to heat two wafers uniformly.
At this time, the distance from the upper wafer to the inner wall of the reaction furnace and the distance from the lower wafer to the upper wafer are substantially equal. This is to make the processes performed on the upper wafer and the lower wafer uniform. Also, the reactor 3
The maximum number of wafers that can be simultaneously loaded in a wafer is two. In order to heat the wafer uniformly in a short time, it is not possible to insert three or more wafers. Since the wafers are heated by the heat radiation, the upper and lower wafers receive the heat radiation from the upper and lower walls of the reaction furnace 3 respectively. If three or more wafers are stacked almost horizontally, the centrally located wafer is less likely to receive heat radiation from the walls of the reaction furnace, and cannot have a uniform temperature in a short time. .

Although the present invention has been described with reference to the CVD, the present invention is not limited to the CVD but can be applied to epitaxial growth, oxidation, etching, and the like.

[0022]

According to the present invention, the processing of two wafers at a time can be made uniform over the entire surface of the wafer without providing a wafer rotating mechanism in the reactor. Further, since there is no wafer rotating mechanism in the reaction furnace, dust generation due to wafer processing can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a semiconductor processing apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view of a reactor according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Cassette chamber, 3 ... Reaction furnace, 4 ... Other reaction furnace, 5 ... Wafer transfer device, 6 ... Cooling room, 7 ... Other cooling room.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/68 H01L 21/302 B

Claims (1)

[Claims] 1. A semiconductor processing apparatus having a plurality of reactors for processing wafers in said reactor, wherein said wafers are processed in a first reactor and then taken out of said first reactor. The direction of the wafer is adjusted outside the first and second reactors so that the relationship between the direction of the wafer and the average gas flow differs between the first and second reactors. Then, the semiconductor processing apparatus is characterized in that the wafer is placed in the second reaction furnace and subjected to substantially the same processing as the above processing.