JPH03159239A - Manufacture of semiconductor device and manufacturing device - Google Patents

Abstract

PURPOSE:To remove efficiently a buried material in a groove by a method wherein a plate is held in almost parallel to a wafer at a slight distance from the surface, which is needed an etching, of the wafer and while running water is fed to the surface, which is not needed an etching, of the wafer, an etchant is fed between the surface, which is needed an etching, of the wafer and the plate to etch the surface which is needed an etching. CONSTITUTION:Water is fed to the surface 3b of a wafer 3 through a running water feed opening 1a, while the mixed solution of a hydrofluoric acid(HF) and a nitric acid(HNO3) is fed between a plate 4 and the rear 3a of the wafer 3 through an etchant feed opening 5 to perform an etching treatment. By feeding the etchant between the wafer 3 and the plate 4, the etchant can be uniformly fed to the whole rear of the wafer 3. That is, the etchant is spread on the whole rear of the wafer 3 by the plate 4 in the same principle as that of a capillarity. Thereby, a polycrystalline silicon film grown on the whole rear 3a of the wafer 3 is completely removed at a uniform etching rate on the whole rear.

Description

Detailed Description of the Invention (Summary) Element isolation is performed using a embedding material such as polycrystalline silicon filled in the element portion IIIrP1 on the surface of the semiconductor substrate.
The purpose of this method is to efficiently remove groove filling material that has grown on the surface of semiconductor substrates using an inexpensive process for manufactured semiconductor devices. The etching process can be performed by holding the plate approximately parallel to the wafer, supplying running water to the side of the wafer that does not require etching, and supplying an etchant between the plate and the side that requires etching, or etching the wafer. The etching process is performed by supplying running water to the surfaces that do not require etching, and supplying a pressurized etchant to the surfaces that require etching.

[Industrial application field]

The present invention relates to a semiconductor device having a structure in which element isolation is performed using a embedding material such as polycrystalline silicon filled in element isolation trenches on the surface of a semiconductor substrate.

Device isolation trench of bipolar transistor (1μ ~ 3μ-
When filling silicon flea crystals into the grooves (width of Since they are arranged in parallel, a film grows not only on the front surface of the semiconductor substrate where the element isolation trench is provided, but also on the back surface thereof. In this case, in order to fill the groove with polycrystalline silicon, it is necessary to make the thickness 1.5μ to 4μ, and the same amount is applied to the back side, depending on the method of setting the crystal during growth. A film with a thickness of . There is no problem with the front surface because it will be flattened by polishing or etchback in a later process, but if the film is left to grow on the back side, the wafer will warp and cause defects. It is necessary to remove the damaged film.

[Conventional technology]

Conventionally, after flattening the 0 surface by an etch-back method using anisotropic etching using the RIE method, the film on the back surface is removed by anisotropic etching using the same <RIE method.
After flattening the surface using a polishing method, the film on the back side is also removed using a polishing method. A method in which the front and back surfaces are treated using a so-called single-sided polishing method. ■ Using a double-sided polishing method, the film on the back surface is stabilized. A method of processing the front and back surfaces by making the polishing speed of the front surface slower than the polishing speed of the back surface in order to remove the surface.Before or after processing the surface, the surface is protected with resist, etc., and a wet method that can process a large number of sheets. Etching (e.g. potassium hydroxide (KO)
A method is known in which the film on the back surface is removed by performing a method such as H).

[Problem to be solved by the invention]

In the conventional examples (1) and (2) above, the front and back surfaces are processed in largely independent processes, and the process is not automated as a single process, resulting in inefficiency and high costs. In addition, the conventional method (2) is inefficient because the polishing speed of the surface must be slowed down as described above, and the double-sided polishing method is generally difficult to automate. There was a problem with inappropriateness.

Furthermore, in the conventional example (2) above, even if the etching itself can be automated, a resist forming process and a resist stripping process are required separately, which increases the total number of processes and increases the cost. However, this method cannot be connected in-line with the surface planarization process (polishing method or etch-back method), making it difficult to automate the entire process.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for manufacturing a semiconductor device that can efficiently remove groove-filling material that has grown on the back surface of a semiconductor substrate using an inexpensive process.

[Means to solve the problem]

The problem mentioned above is that the plate is held approximately parallel to the surface of the wafer that requires etching at a small distance, and running water is supplied to the surface of the wafer that does not require etching, while the surface that requires etching is A method for manufacturing an upper shelf device, characterized in that it includes a step of performing an etching process by supplying an etchant between the plate and the plate, and the etching process includes supplying the etchant for a certain period of time, stopping the supply of the etchant, and performing an etching process. The problem is solved by a manufacturing method characterized by a cycle of holding water for a certain period of time and supplying water for a certain period of time to a surface that requires etching treatment. Or
(c) A method for manufacturing a semiconductor device, characterized in that the etching process is performed by supplying running water to the surface that does not require etching, and supplying a pressurized etchant to the surface that requires etching, The etching process is solved by a manufacturing method characterized by a cycle of supplying an etchant for a certain period of time, stopping the supply of the etchant, and holding the etchant for a certain period of time.

Furthermore, the apparatus of the present invention has a flow bed on which the wafer is placed and which supplies running water from below to the lower surface of the wafer, and a flow bed that is supported above the wafer and substantially parallel to the upper surface at a small distance. an etchant supply port for supplying an etchant between the plate and the upper surface of the wafer, or
It consists of a flow bed on which a wafer is placed, and a flow bed that supplies running water from below to the lower surface of the wafer, and an etchant supply port that supplies pressurized etchant to the upper surface of the wafer.

[Effect]

In the present invention, the etchant is supplied between the plate facing the surface of the wafer that requires etching, or
Etching can be completely removed with a uniform etching rate over the entire surface by simply supplying a pressurized etchant to the surface of the wafer that requires etching. For this reason, compared to conventional methods that required a resist process for etching processing or conventional methods that performed double-sided polishing, it is easier to combine it in-line with a polishing device for flattening processing and automate it as one process. Furthermore, compared to conventional double-sided polishing methods, both sides can be processed more efficiently and manufactured at a lower cost. In addition, the front and back surfaces are treated in separate processes, and
Both processes can be processed efficiently and at low cost even in conventional cases where automation has not been performed as one process.

In this case, since the plate using the above-mentioned plate is processed through a cycle of etchant supply, retention, and water supply, the gas generated during etching can be effectively washed away by water, and etching can be carried out effectively. Moreover, compared to the method of continuously supplying etchant from beginning to end, etchant can be saved and the cost is low. In addition, for those that use pressurized etchant, the process uses a cycle of etchant supply and retention, which saves etchant and costs less than a method that continues to supply etchant from start to finish. Since no plates are used, the gas can simply escape, so there is no need to include a water supply in the cycle.

〔Example〕

FIG. 1 shows a schematic diagram of an etching jig illustrating an embodiment of the present invention. In the figure, 1 is a flowing bed, and there is a running water supply port 1 in the center.
a is provided, and holding bottles 2+, 2 are provided on the upper surface thereof.
2 are erected. 3 is a wafer that has been brought in after its surface has been polished, and is placed between the holding bins 2+ and 22 above the flow bed 1 with the back surface 3a that requires etching removal facing up and the surface 3b that does not require etching facing down. It is placed. A plate 4 has a fine mesh structure, is held substantially parallel to the wafer 3 placed on the flow bed 1, and has an etchant supply port 5 in the center. 6 is a nipyant container. The etching jig is equipped with a D-der (carrying device) on the entrance side and an unloader (carrying out device) on the exit side, and is used as an automatic T-touching machine.

Here, while supplying water from the running water supply port 1a to the surface 3b of the wafer 3 (the one brought in after surface polishing),
■Hydrofluoric acid (HF) and nitric acid (H) are
A mixed solution of NO3) is applied to the plate 4 and the back surface 3 of the wafer 3.
The etching process is performed by supplying the film between the film and the film a. In this case, the reason why water is supplied from the water supply port 1a to the wafer surface 3b is to prevent a single beam from above from entering the wafer surface 3b which has been flattened by polishing. Water supplied to the wafer front surface 3b, wafer back surface 3
The etchant supplied to a is lost through a suitable plowing port. Moreover, the holding bottles 2+ and 22 prevent the wafer 3 from shifting even if water is supplied from the front side and etchant is supplied from the back side 3a.

By the way, it is generally difficult to etch the entire surface with a uniform etching rate using the above-mentioned etchant, and as shown in FIG. (indicated by 10a), the etchant supplied thereafter flows out through this portion (indicated by 11), and the etchant does not act on the remaining unetched polycrystalline silicon film. Therefore, in order to eliminate this problem, it is necessary to supply the etchant to the entire back surface of the wafer 3 without any hesitation, but as shown in FIG. The etchant can be supplied to the entire back surface of the wafer 3 without any retraction. That is, the plate 4 spreads the etchant over the entire back surface of the wafer 3 using the same principle as capillary action. As a result, the polycrystalline silicon film grown on the entire back surface 3a of the wafer 3 is completely removed at a uniform etching rate over the entire surface.

In this case, if the distance between the wafer 3 and the plate 4 is too long, the effect of capillary action will be reduced, so for example 0.6
It is set to about M to 1JIII. With this level of gap, wafer 3. Since it is only necessary to install the plate 4, the parallel alignment at the time of installing the jig does not have to be so strict.

Further, since the plate 4 has a mesh structure, it is possible to effectively release hydrogen gas generated when a polycrystalline silicon film is etched with a mixed solution of hydrofluoric acid and nitric acid. In this case, the mesh structure of the plate 4 is effective because etching of the polycrystalline silicon film at the portions to which hydrogen gas is attached will not progress unless hydrogen gas can be handled. In addition, in order to release hydrogen gas, etchant is supplied for a certain period of time, then stopped and held in that state for a certain period of time), and water is supplied for a certain period of time instead of etchant from the etchant supply port 5 to allow hydrogen gas to flow. It is even more effective to repeat the cycle of removing the etchant and then supplying the etchant again.

In this case, etching continues even during the holding period.

For example, when using a wafer with a polycrystalline silicon film thickness of 3 μm and a diameter of 4 inches, the time required to remove this polycrystalline silicon film is as follows: 2 to 3 cycles (one cycle is T-butyan 5 second feed (approximately 3 Qcc to 40 CC) - 30 second hold - 30 second feed of water (4 Pcg/d)) were required. Note that since the etchant is supplied intermittently, the etchant can be saved and the cost can be kept low compared to a method in which the etchant is continuously supplied from beginning to end.

In the present invention, it is possible to completely remove etching with a uniform etching rate over the entire surface by simply supplying an etchant to the back surface of the wafer 3 from above.
Compared to the conventional example (■) which required a resist process for back side treatment and the conventional example (■) which performed double-sided polishing, it is easier to combine it in-line with a polishing device for surface treatment and automate it as one process. Both sides can be processed more efficiently than the conventional example (2), and it can be manufactured at a lower cost than the conventional examples (2) and (3).

In addition, the front and back surfaces are treated in separate processes, and both surfaces are treated in separate processes.
Conventional examples ① and ②, which did not automate processing as one process, can be processed efficiently and inexpensively.

FIG. 3 shows a schematic diagram illustrating another embodiment of the present invention,
In the figure, the same components as those in FIG. 1 are given the same numbers and their explanations will be omitted. In FIG. 3, numeral 15 is a T-chant container, in which pressure is applied to the etchant with nitrogen gas. 16 is the supply port, the inner diameter is for example 1j
Consists of * nozzles.

Here, when pressure is applied to the etchant in the etchant container 15 with hydrogen gas, the etchant is ejected from the nozzle of the etchant supply port 16 and supplied to the back surface 3a of the wafer 3. In this case, since the etchant is under pressure, it is supplied to the entire surface of the wafer 3 without any retraction, and the same effect as in this embodiment can be obtained without using the plate 4 as shown in the embodiment shown in FIG. Can be done.

In the embodiment shown in FIG. 3, it is sufficient for the etchant to spread over the entire surface of the wafer 3 in the case of a 4-inch diameter wafer, about 3 seconds, and once the etchant has spread, the supply of etchant is stopped and the etchant is kept for a certain period of time (for example, 30 seconds). (Keep it as it is)
Then, the process of supplying the etchant again for about 3 seconds and leaving it in that state for a certain period of time is repeated. In this way, etchant can be saved and costs can be kept low compared to a method in which etchant is continuously supplied from the start to the end of etching. After etching is completed, water is supplied from the etchant supply port 16 instead of the etchant, and the etchant is allowed to flow. Further, clean air or nitrogen gas may be supplied to the wafer 3 to dry it as necessary. Note that the embodiment shown in Fig. 3 does not use a plate like the embodiment shown in Fig. 1, so hydrogen gas escapes each time, and there is no need to include running water treatment in the cycle to release hydrogen gas. good.

■Chant supply (about 3 seconds) - hold - (30 seconds) to 1
When cycled, the thickness of the polycrystalline silicon film is 3 μm.
, the number of cycles required to remove a polycrystalline silicon film on a 4 inch diameter wafer is shown below.

In the above embodiment, polycrystalline silicon was used as the filling material in the element isolation trench, but it goes without saying that other materials may be used.

Further, although the holding pins 2+ and 22 are used as members for holding the wafer 3 on the flow bed 1, a member such as a vacuum chuck may also be used.

Further, although the etchant is supplied from one supply port, a plurality of supply ports may be provided.

Further, in the embodiment shown in FIG. 3, pressure is applied to the etchant using nitrogen gas, but pressure may be applied by a mechanical method.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to perform a complete etching process with a uniform etching rate over the entire surface by simply supplying an etchant to the wafer surface from above, which eliminates the conventional method that required a resist process. Compared to conventional methods that perform double-sided polishing, it is easier to combine in-line with a polishing device for flattening processing and automate it as one process, and it is also possible to process both sides more efficiently than conventional methods of double-sided polishing. , it can be manufactured at a lower cost than these conventional examples.

In addition, it is more efficient than the conventional method where the front and back sides were processed in separate processes and both processes were not automated.
Can be manufactured cheaply.

In this case, since the plate-based etching process uses a cycle of etchant supply, retention, and water supply, the gas generated during etching can be effectively washed away by water, making it possible to perform etching effectively. Moreover, it saves etchant and is low cost. In addition, for those that supply etchant under pressure, the process is carried out in a cycle of etchant supply and retention, which saves etchant and is low cost.Since no plates are used, there is no need for water during the cycle. No need to supply.

6.15 is an I chant container shows.

Claims (1)

[Claims] (1) The surface of the wafer (3) that requires etching (3a)
), the plate (4) is held substantially parallel to the surface (3b) of the wafer (3) that does not require etching at a small distance from the surface (3b) of the wafer (3).
A semiconductor characterized in that it includes a step of performing an etching process by supplying an etchant between the surface (3a) of the wafer (3) that requires etching and the plate (4) while supplying running water to the surface of the wafer (3). Method of manufacturing the device. 7. The etching process is performed using a cycle of supplying the etchant for a certain period of time, stopping the supply of the etchant and holding it for a certain period of time, and supplying water for a certain period of time to the surface (3a) that requires the etching process. A method for manufacturing a semiconductor device according to claim 1. (3) Side of wafer (3) that does not require etching (3)
2. The semiconductor according to claim 1, wherein the etching process is carried out by supplying a pressurized etchant to the surface (3a) of the wafer (3) that requires etching while supplying running water to the semiconductor device according to claim 1. Method of manufacturing the device. 4. The method of manufacturing a semiconductor device according to claim 3, wherein (A) the etching process is performed in a cycle in which the etchant is supplied for a certain period of time, the supply of the etchant is stopped, and the etchant is maintained for a certain period of time. (5) A fluid bed (1) on which a wafer (3) is placed and which supplies running water from below to the lower surface (3b) of the wafer (3); A plate (4) supported above the wafer (3) substantially parallel to the upper surface (3a) of the wafer (3) at a very small distance; ) and an etchant supply port (5) for supplying an etchant between the upper surface (3a) of the semiconductor device and the upper surface (3a) of the semiconductor device. (6) A fluid bed (1) on which a wafer (3) is placed and which supplies running water from below to the lower surface (3b) of the wafer (3); An etchant supply port (16) for supplying a pressurized etchant to the upper surface of the wafer (3).