JP3746793B2 - Semiconductor manufacturing method and semiconductor manufacturing apparatus - Google Patents

Description

[0001]
[Industrial application fields]
Semiconductor manufacturing method and a semiconductor manufacturing device, in particular relates to and boat loading drawer when loading drawer boat boats to hold the wafer into the reaction furnace.
[0002]
[Prior art]
Semiconductor manufacturing processes include film deposition by vapor phase growth reaction on wafers, diffusion of impurities such as phosphorus or boron, and other processes for heat treatment of wafers. Hold the number, and load and withdraw this boat into the reaction chamber.
[0003]
An outline of a semiconductor manufacturing apparatus, particularly a semiconductor manufacturing apparatus having a vertical furnace will be described with reference to FIG.
[0004]
1 is a cassette loader located on the front side of the semiconductor manufacturing apparatus, 2 is a cassette stocker, 3 is a buffer cassette stocker, 4 is a wafer transfer machine, 5 is a boat elevator, and 6 is a reactor.
[0005]
Wafers are transported in a state in which they are loaded in a wafer cassette, and the wafer cassette is placed on a cassette insertion / removal machine 7 of the cassette loader 1. The wafer cassette is loaded and unloaded at a required position of the stocker 3.
[0006]
The wafer transfer device 4 has a chucking head 8 that can move up and down, rotate, and move in the horizontal direction. The boat elevator 5 receives a boat 9 via a boat cap 11, and It is moved up and down and charged into the reactor 6. The wafer transfer device 4 transfers the wafer 10 from the wafer cassette of the cassette stocker 2 to the boat 9 by the chucking head 8 while the boat 9 is lowered.
[0007]
The boat elevator 5 is loaded with the boat 9 into the reaction furnace 6, the wafer 10 is heated in the reaction furnace 6, and the reaction furnace 6 is evacuated after a certain time so that the wafer 10 reaches the reaction temperature. Then, a predetermined degree of vacuum is controlled, and a reaction gas is introduced into the reaction furnace 6 to perform a required process. After the heat treatment, the inside of the reaction furnace 6 is replaced with an inert gas, and the boat 9 is lowered by the boat elevator 5 and pulled out from the reaction furnace 6. The boat 9 and the wafer 10 are cooled outside the furnace, and the wafer 10 is transferred from the boat 9 to the wafer cassette of the cassette stocker 2 by the wafer transfer device 4 while the boat 9 is lowered.
[0008]
Further, the wafer 10 to be processed next is transferred to the boat 9 by the wafer transfer device 4, and the wafer processing is repeated.
[0009]
[Problems to be solved by the invention]
As described above, the boat 9 is loaded into and pulled out of the furnace in accordance with the wafer processing. However, in the conventional semiconductor manufacturing method, the wafer processing is completed, and the boat 9 waits outside the furnace until the next wafer processing. is doing. For this reason, there is a problem described below when the processing interval is large.
[0010]
Even in a clean room maintained normally, particles and other contaminants (Na, Al, Cu, and other metal substances) are floating in a small amount. When these particles and other contaminants adhere to the wafer 10 during the semiconductor manufacturing process, they cause disconnection of a semiconductor element to be manufactured, deterioration of electrical characteristics, and the like.
[0011]
The particles and other contaminants are generated from the clothes of the worker, and are contained in the breath and sweat of the worker, and are also generated for various reasons such as the evaporation of grease or oil used in automatic robots. However, floating contaminants cannot be avoided.
[0012]
Accordingly, when the boat 9 is pulled out of the furnace, the chance of the contaminants adhering to the boat 9 or dummy wafers loaded in the boat 9 increases. Contaminants adhering to the boat 9 and the dummy wafer may contaminate the processing wafer, which greatly affects the processing quality of the wafer. Actually, when the number of particles is measured with a particle counter after processing the wafer, it is known that the number of particles increases as the time that the boat 9 is waiting outside the furnace is longer.
[0013]
In addition, when an oxide film is formed on the wafer surface in a diffusion device, if there is a contaminant such as a metal substance on the wafer surface, the oxidation rate increases only at the contaminated part, and the film thickness locally increases. At the same time, there is a problem of affecting the film quality.
[0014]
Further, in an apparatus for depositing a nitride film (composition: Si ₃ N ₄ ) on the wafer 10 by a vapor phase growth reaction, the boat 9 is lowered after the heat treatment of the wafer 10 and left for a long time. The reaction by-product attached to the cap 11 and the dummy wafer after cooling becomes easy to peel off. In the next processing step, when the boat 9 is charged into the furnace and the inside of the furnace is evacuated, the reaction attached to the boat cap 11 and the like. By-products are scattered as particles, adhere to the wafer 10, and abnormal film growth is observed. Protrusions (stars) that appear to give up stars in the night sky are formed on the wafer 10.
[0015]
In addition, in the deposition, diffusion and other heat treatment of various wafers 10 by CVD, the boat 9 is pulled out of the furnace for each batch, but the processing wafer 10 is put into the boat 9 in the next processing step. The time from loading to loading the boat 9 into the furnace is not constant. Therefore, the temperature drop of the boat cap 11, boat 9, dummy wafer, etc. varies, the furnace temperature stabilizes after the boat 9 is placed in the furnace, and there is a difference in the time when the processing wafer approaches the reaction chamber temperature. Arise. Curve A in FIG. 3 shows the temperature rise curve of the wafer when the boat is left outside the furnace for 2 hours or more and curve B is left for 30 minutes to 1 hour.
[0016]
If a sufficiently long time is taken for the processing wafer 10 to approach the reaction chamber temperature, the temperature difference of the processing wafer 10 in each batch disappears and the reaction chamber temperature approaches sufficiently, but the processing time in each processing step Contrary to the requirement to shorten When a film doped with impurities (phosphorus, boron, etc.) is formed on the processed wafer 10, the diffusion of the impurities in the film proceeds, and the thermal history of the processed wafer 10 increases with the length of the temperature rise time. There is also the problem of changing. Therefore, when the waiting time between batches is different, a difference occurs in the temperature during the reaction of the processed wafer 10, resulting in a difference in wafer processing such as film formation and impurity diffusion.
[0017]
In view of such circumstances, the present invention is intended to improve the processing quality by preventing contamination by contaminants such as particles outside the boat furnace and eliminating variations in wafer processing temperatures between batches.
[0018]
[Means for Solving the Problems]
The present invention relates to a semiconductor manufacturing method in which a wafer held in a boat is loaded into a reaction furnace and the wafer is processed, and after the wafer is processed, the boat is pulled out and the wafer is taken out from the boat and then processed. up in boat waiting until loaded into the boat, Ri relates to a semiconductor manufacturing process to be charged with the boat in a furnace, for holding a reaction furnace for processing Matau Eha, a wafer in the reaction furnace A semiconductor manufacturing apparatus comprising a boat and a boat elevator for taking out the wafer from the boat after processing the wafer and loading the boat into the reaction furnace during standby until the next wafer is loaded into the boat the engagement is, after processing the charged the wafer held on a further in or boat to the reactor wafer, the boat after drawn from the reactor, the wafer unloading from the boat Then, in a semiconductor manufacturing method in which a wafer to be processed next in the reaction furnace is placed on the boat, and the boat is again inserted into the reaction furnace, the boat is taken out of the reaction furnace and then The present invention relates to a semiconductor manufacturing method in which the time until a wafer to be processed is placed on a boat and loaded into the reaction furnace is a time during which the boat is not completely cooled, and is kept constant.
[0019]
[Action]
Since the boat is taken out of the furnace only when necessary, the contamination of the boat and the dummy wafer with the contaminant is suppressed, and the variation in the temperature drop of the boat or the like is prevented from batch to batch, thereby improving the product quality. I can plan.
[0020]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is an explanatory view showing a main part of a semiconductor manufacturing apparatus in which the present embodiment is implemented.
[0022]
In FIG. 1, the same components as those shown in FIG. 2 are denoted by the same reference numerals.
[0023]
The reaction furnace 6 comprises an external reaction tube 12 and an internal reaction tube 13, and a heater 14 is provided so as to cover the periphery of the external reaction tube 12. A reaction chamber 18 is defined inside the internal reaction tube 13, a reaction gas introduction tube 15 communicates with the reaction chamber, and an exhaust pipe is formed in a cylindrical space between the external reaction tube 12 and the internal reaction tube 13. 16 communicates.
[0024]
In the figure, reference numeral 17 denotes a shutter that closes the furnace port portion when the boat 9 is lowered. The upper and lower portions of the boat 9 are loaded with a required number of dummy wafers 10a, and the processing wafers 10b are loaded between the dummy wafers 10a.
[0025]
This embodiment is a boat loading and unloading method in which the boat is loaded into the furnace while waiting for the boat in the semiconductor manufacturing apparatus, and the time for the boat to be pulled out of the furnace is made constant, This is a boat loading / unloading method in which the temperature drop of the boat being pulled out, the boat cap, etc. is kept constant.
[0026]
More specifically, the boat 9 is pulled out of the reaction chamber 18 only when the wafer 10 is transferred to the boat 9, and the boat 9 is loaded into the reaction chamber 18 at other times. As a result, the time during which the boat 9 and the like are exposed to the reaction chamber 18 is shortened, and particles enter the reaction chamber 18 and particles and contaminants adhere to the boat 9, the boat cap 11, the dummy wafer 10a, and the like. Can be prevented. Thus, the adhesion of particles to the processed wafer 10b can be suppressed, and when the oxidation process is performed by the diffusion device, it is possible to suppress the local increase in the thickness of the oxide film.
[0027]
In addition, in the Si ₃ N ₄ film generation apparatus of the low pressure CVD apparatus, the time during which the boat 9 is taken out of the reaction chamber can be minimized and kept constant, so that the temperature drop of the boat 9 and the boat cap 11 can be suppressed. Can suppress the separation of reaction by-products from the boat cap 11 and the like, and prevents the occurrence of abnormal protrusions (stars) on the film when the Si ₃ N ₄ film is deposited on the processing wafer 10b.
[0028]
In the process of performing wafer processing, when the same recipe is executed in the same apparatus and wafer processing (CVD, diffusion processing) is performed, the average film thickness in each batch is compared, and the film thickness is 0. Only an error of about 5 to 2% is allowed, and it is necessary to control the film thickness from several angstroms to several tens of angstroms. As described above, in this embodiment, the boat is pulled out only at the time of wafer transfer, and the boat 9 is loaded into the reactor 6 during standby, so that the temperature drop is kept constant regardless of the time difference between batches. Thus, it is possible to prevent variation in processing quality due to a difference in processing temperature.
[0029]
In addition, although the said Example demonstrated the semiconductor manufacturing apparatus provided with the vertical reactor, it cannot be overemphasized that it can implement similarly also about the semiconductor manufacturing apparatus provided with the horizontal reactor.
[0030]
【The invention's effect】
As described above, according to the present invention, since the waiting state of the boat is charged in the furnace, it is possible to prevent the difference in the reaction temperature based on the contamination of the boat and the like by pollutants such as particles, the length of the waiting time, It is possible to improve the processing quality of the wafer and to make the processing quality uniform between batches by preventing the contaminants from adhering to the wafer via the boat.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a main part of a semiconductor manufacturing apparatus in which the present invention is implemented.
FIG. 2 is a perspective view showing an outline of a semiconductor manufacturing apparatus.
FIG. 3 is a diagram showing a temperature rise curve in a furnace of a processing wafer based on a difference in time when the boat is taken out of the furnace.
[Explanation of symbols]
5 Boat elevator 6 Reactor 8 Chucking head 9 Boat 10 Wafer 11 Boat cap

Claims (3)

  In a semiconductor manufacturing method in which a wafer held in a boat is loaded into a reaction furnace and a wafer is processed, the wafer is pulled out after the wafer is processed, the wafer is taken out from the boat, and a wafer to be processed next is transferred to the boat. A semiconductor manufacturing method, wherein the boat is charged in a furnace while waiting for the boat to be loaded.   A reaction furnace for processing wafers, a boat for holding wafers in the reaction furnace, and after waiting for a boat to be taken out from the boat after the wafer has been processed, A semiconductor manufacturing apparatus comprising a boat elevator charged in a furnace.   After the wafer held in the boat is loaded into the reactor and the wafer is processed, the boat is pulled out of the reactor, and then the wafer is taken out of the boat, and then the wafer to be processed next in the reactor is In the semiconductor manufacturing method of placing the boat in the reactor again, the wafer to be processed next is placed on the boat after the boat is taken out of the reactor. A method for manufacturing a semiconductor, characterized in that the time until charging is set as a time during which the boat is not completely cooled and is kept constant.

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