KR100363699B1 - Method for forming semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and in particular, this method can inject oxygen and hydrogen gas simultaneously in a high temperature and low pressure atmosphere by rapid temperature increase using a rapid heat treatment method to uniformly oxidize a silicon surface. Is applied to the trench isolation layer manufacturing method, sacrificial oxide and liner oxide to remove the etch damaged silicon of the trench sidewalls during the manufacturing process to uniform thickness of the trench sidewalls and the bottom oxide layer to minimize the loss of the active region device operation margin Can be secured.

Description

Method for manufacturing semiconductor device {Method for forming semiconductor device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and in particular, a technique capable of improving the yield reduction of a semiconductor device due to a nonuniform oxide film generated by a high temperature dry oxidation process and a low temperature wet oxidation process.

Recently, as the development of semiconductor device manufacturing technology and the application of memory devices have been expanded, the development of large-capacity memory devices has been progressed. It has been promoted by a memory cell study. In particular, the reduction of the device isolation film that separates the devices has emerged as one of the important items in the technology of miniaturization of memory devices.

Conventional device isolation technology has mainly been a LOCal Oxidation of Silicon (LOCOS) technology to selectively grow a thick oxide film on the semiconductor substrate to form a device isolation film. However, the LOCOS technique cannot reduce the width of the device isolation region due to side diffusion and bird's beak of the device isolation layer. Therefore, the LOCOS technology cannot be applied to a large-capacity memory device whose device design dimension is reduced to submicron or less, so a new device isolation technology is required.

Accordingly, a trench capable of electrically separating devices by forming trenches having a width of 0.2 μm or less and a depth of several thousand to tens of thousands in the semiconductor substrate due to the necessity of a new device isolation technology and the development of etching technology. Device isolation technology with The device isolation technology using this trench can reduce the device isolation region by nearly 80% compared to the conventional LOCOS technology.

Moreover, recently, the STI (Shallow Trench Isolation) process, which greatly reduces the stress applied to the wafer substrate and improves the problem of the trench isolation layer, has emerged. In other words, the STI process is a technique of forming a device isolation film by forming a trench having a predetermined depth in the semiconductor substrate, depositing an oxide film on the trench by chemical vapor deposition, and etching an unnecessary oxide film by a chemical mechanical polishing process.

However, the STI process must remove the etch damage present on the inner surface of the trench to improve the junction leakage current characteristics. In order to compensate for the damage generated during the trench etching in the substrate and to obtain a profile of the interface between the etching surface and the device isolation layer, two high temperature oxidation processes are usually performed. That is, the sacrificial oxide film is formed in the trench of the substrate by first oxidizing and removing the sacrificial oxide film, and then the second oxidation process is performed again to form the sidewall oxide film to compensate for the etching damage on the substrate surface inside the trench.

1 is a cross-sectional view illustrating a structure of an STI type isolation layer according to the prior art. Referring to this, a conventional STI type isolation layer manufacturing process is as follows.

The pad oxide film 12 is formed on the silicon substrate 10 as a semiconductor substrate, and the pad nitride film 14 is laminated thereon. The pad nitride layer 14 and the pad oxide layer 12 are patterned by a photolithography and an etching process using a device isolation mask, and the substrate exposed by the patterned layer is selectively etched to form trenches up to a predetermined depth. As described above, in order to compensate for the trench etch damage, the sacrificial oxide film 16 is grown by about 150 to 200 microseconds and then the grown sacrificial oxide film is removed. Then, an oxidation process is performed again to grow the liner oxide film 18 in the trench at about 150 to 200 kPa. Then, the trench is completely filled with the gapfill oxide film 20, and the pad nitride film is used as an etch stop film, and the nitride film 14 remaining after the planarization of the gapfill oxide film 20 is removed by a chemical mechanical polishing process to remove the STI device isolation film. Form.

2A and 2B are cross-sectional views illustrating defects in trench portions generated in a conventional STI device manufacturing process, and FIG. 1A is an enlarged view of a trench corner portion.

The sacrificial oxide film and the liner oxide film which are frequently used in the STI device isolation film have poor trenches or uneven growth depending on the oxidation process conditions. Usually the sacrificial oxide and liner oxide are formed in the furnace by dry oxidation by oxygen molecules (O) or wet oxidation by moisture (H ₂ O), where oxides (16, 18) in the trench sidewalls are more than the trench bottom. It is formed thick and causes stress in the silicon substrate. This increases the leakage current to the silicon substrate in the source / drain regions. The stresses generated in the production of liner oxides are due to the corner rounding at the top of the trench, the corner rounding at the bottom of the trench, the formation of sharp facets at the corners, and the oxide uniformity and layer covering at the bottom of the trench.

Referring to FIG. 2A, when the sacrificial oxide and the liner oxide are formed by a wet oxidation process in a furnace at 1000 ° C. or less, for example, 900 ° C., the oxide thickness of the trench bottom is relatively thin and the shape of the trench upper edge is sharp. As a result, the gate oxide film and the leakage current characteristics deteriorate.

Referring to FIG. 2B, when the sacrificial oxide film and the liner oxide film are formed by a dry oxidation process in a furnace of 1000 ° C. or higher, for example, 1100 ° C., an inclined surface f is formed at the bottom edge of the trench to generate defects in a subsequent process.

As a result, when the oxide film is grown in the trench region by a high temperature dry oxidation process or a low temperature wet oxidation process, more silicon is lost in the sidewall (ie, oxidation), thereby narrowing the active area of the substrate on which the device is to be formed. Increasing the thickness of the pad oxide film plays a role of deteriorating the surface characteristics of the active region, thereby failing to secure sufficient active region, thereby lowering the electrical characteristics of the device.

SUMMARY OF THE INVENTION An object of the present invention is to manufacture a semiconductor device capable of uniformly oxidizing a silicon surface by simultaneously injecting oxygen and hydrogen gas in a high temperature and low pressure atmosphere due to rapid temperature increase by using a rapid heat treatment method to solve the problems of the prior art. To provide a method.

Another object of the present invention is to provide a uniform sacrificial oxide film and a liner oxide film by oxidizing the silicon surface in the trench by injecting oxygen and hydrogen gas at the same time in a high temperature and low pressure atmosphere due to rapid temperature increase using a rapid heat treatment method during the trench type device isolation film manufacturing process It is to provide a method of manufacturing a semiconductor device that can form a.

It is still another object of the present invention to provide a semiconductor device capable of uniformly growing a gate oxide film on a silicon surface by simultaneously injecting oxygen and hydrogen gas in a high temperature and low pressure atmosphere due to rapid temperature increase using a rapid heat treatment method during a gate oxide film manufacturing process. It is to provide a manufacturing method.

1 is a cross-sectional view showing a STI type device isolation film structure according to the prior art;

2A and 2B are cross-sectional views illustrating defects in trench portions generated in a conventional STI device manufacturing process;

3 is a cross-sectional view illustrating an STI type isolation film manufacturing process as an example of a method of manufacturing a semiconductor device according to the present invention;

4 is a cross-sectional view showing an oxide film uniformly grown on the trench bottom and sidewall portions by the STI device isolation process according to the present invention;

5 is a cross-sectional view for explaining a gate oxide film production process as another example of the method for manufacturing a semiconductor device according to the present invention.

Explanation of symbols on the main parts of the drawings

100,200: silicon substrate 102,202: pad oxide film

104: pad nitride film 106: sacrificial oxide film

108: liner oxide film 110: gap fill oxide film

204: gate oxide film

In order to achieve the above object, the present invention provides a method for manufacturing an oxide film of a semiconductor device, wherein oxygen and hydrogen gas are injected after loading a wafer into a chamber for rapid heat treatment, and oxygen and hydrogen gas react with oxygen and hydrogen gas on a silicon surface. It is characterized by growing an oxide film of uniform thickness in an oxidizing atmosphere in which OH is formed.

In the production method of the present invention, the temperature of the reaction chamber during the oxide film production process is 800 ~ 1200 ℃, the pressure is 0 ~ 200 Torr, the temperature increase and temperature lowering rate is 10 ℃ / sec ~ 200 ℃ / sec, oxygen gas And hydrogen gas are preferably supplied at a flow rate of 0 to 30 slm, respectively.

In order to achieve the above object, the present invention provides a method of forming a device isolation film having a trench structure, sequentially depositing a pad oxide film and a nitride film on an upper surface of a semiconductor substrate, and performing a photo and etching process using a device isolation mask. Forming a trench to a predetermined depth of the substrate after patterning the oxide film, and loading the substrate having the trench formed in the rapid heat treatment chamber, and then injecting oxygen and hydrogen gas to grow the sacrificial oxide film on the trench sidewalls and bottom and then removing the trench. And forming a device isolation film by filling the gap fill oxide film in the trench of the substrate and planarizing it, and then removing the nitride film.

In the manufacturing method of the present invention, prior to forming the gap fill oxide film, further comprising the step of forming a liner oxide film on the trench sidewall and bottom by injecting oxygen and hydrogen gas after loading the substrate in the rapid heat treatment chamber. .

In order to achieve the above another object, the present invention provides a method for manufacturing a gate oxide film of a semiconductor device, by injecting oxygen and hydrogen gas after loading a wafer into a chamber for rapid heat treatment, by reaction of oxygen and hydrogen gas on a silicon surface. A gate oxide film having a uniform thickness is grown on a silicon substrate surface in an oxidizing atmosphere in which oxygen atoms and OH are formed. Here, the silicon substrate surface is cleaned with hydrofluoric acid and ammonia water before forming the gate oxide film.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the method of manufacturing an oxide film of a semiconductor device, an oxygen atom and OH are reacted by oxygen and hydrogen gas injecting oxygen and hydrogen gas after loading a wafer into a chamber for a rapid thermal process. An oxide film having a uniform thickness is grown in the formed oxidizing atmosphere.

3 is a cross-sectional view illustrating an STI type isolation layer manufacturing process as an example of a method of manufacturing a semiconductor device according to the present invention. Referring to this, the STI type isolation layer manufacturing method of the present invention is as follows.

The pad oxide film 102 is formed on the silicon substrate 100 as a semiconductor substrate, and the pad nitride film 104 is laminated thereon. The pad nitride layer 104 and the pad oxide layer 102 are patterned by a photolithography and an etching process using a device isolation mask, and the substrate exposed by the patterned layer is selectively etched to form trenches up to a predetermined depth. Next, in order to compensate for the trench etch damage, the sacrificial oxide film 106 is grown to about 10 to 300 GPa. In the present invention, after the substrate 100 having the trench is formed in the rapid heat treatment chamber, oxygen and hydrogen gas are injected to inject the trench. The sacrificial oxide film 106 is grown on the sidewalls and the bottom.

Here, the temperature of the reaction chamber during the manufacturing process of the sacrificial oxide film 106 is 800 ~ 1200 ℃, the pressure is 0 ~ 200 Torr, the temperature rising and temperature lowering rate is 10 ℃ / sec to 200 ℃ / sec. Oxygen gas and hydrogen gas are each supplied at a flow rate of 0 to 30 slm. Accordingly, the sacrificial oxide film 106 has the same thickness on the trench sidewalls and the bottom,

Next, after the sacrificial oxide film 106 is removed, the liner oxide film 108 is grown in the trench by about 10 to 300 kPa. The liner oxide film 108 is also grown under the same process conditions as the sacrificial oxide film 106.

Next, the gapfill oxide film 110 is buried in the trench of the substrate using a high density plasma (HDP) method. If the gap fill oxide film 110 is polished until the nitride film 104 is exposed by a planarization process such as chemical mechanical polishing or etch back, the nitride film 104 is removed using a phosphoric acid solution. An STI type device isolation film according to the present invention is formed on a substrate.

FIG. 4 is a cross-sectional view illustrating an oxide film uniformly grown on a trench bottom and a sidewall by an STI device isolation process according to the present invention, and an enlarged trench corner portion of FIG.

As shown in FIG. 4, according to the STI type isolation layer manufacturing method of the present invention, the thickness of the sacrificial oxide layer and the liner oxide layer 106 and 108 is uniform in both the trench bottom Wb, the sidewall Ws, and the edge, and thus, the isolation layer. Since it is very effective for the defect removal and the corner rounding effect of (110), it is possible to prevent the reduction of the active area and the occurrence of stress in advance.

5 is a cross-sectional view illustrating a gate oxide film manufacturing process as another example of a method of manufacturing a semiconductor device according to the present invention. Referring to this, a method of manufacturing a gate oxide film according to another embodiment of the present invention will be described below.

First, the device isolation film 202 is formed by performing an STI process on the silicon substrate 200 as a semiconductor substrate.

Then, the silicon substrate surface is cleaned with hydrofluoric acid and ammonia water before forming the gate oxide film.

Then, the gate oxide film manufacturing process according to the present invention is carried out, which is loaded with oxygen and hydrogen gas after the wafer 100 is loaded into the chamber for rapid heat treatment, and reacts with oxygen atoms by oxygen and hydrogen gas on the silicon surface. A gate oxide film 204 having a uniform thickness is grown on the silicon substrate surface in an OH atmosphere. In this case, the thickness of the gate oxide film 204 may vary depending on the electrical characteristics of the semiconductor device, but is preferably 10 to 100 microseconds.

As described above, when the present invention is used in the manufacturing process of the gate oxide film, the gate oxide film 204 is prevented from decreasing in thickness of the gate oxide film 204 at the edge caused by the step difference between the active region of the substrate 200 and the device isolation film 202. Can improve the breakdown voltage strength. In addition, the characteristics of the very thin gate oxide film 204 of 40 kV or less can be improved, and the thickness of the gate oxide film can be reduced in the highly integrated semiconductor device.

As described above, when the oxide film manufacturing method of the present invention is applied to the trench device isolation film manufacturing method, the thickness of the sacrificial oxide and the liner oxide film is adjusted to be thin by forming the oxide sidewalls and the bottom oxide layer uniformly, thereby minimizing the loss of the active region. The operation margin of the device can be secured. In addition, it is possible to prevent the occurrence of stress in the silicon substrate and to prevent the generation of defects, thereby improving leakage current and refresh characteristics. In addition, in the present invention, the oxygen atom and the OH can oxidize the nitride film to some extent, thereby increasing the trench edge rounding effect and omitting the liner oxide film filling the moat, thereby simplifying the device isolation film manufacturing process. .

When the oxide film production method of the present invention is applied to the gate oxide film production method, the breakdown voltage strength of the gate oxide film can be improved by preventing the gate oxide film thickness from decreasing at the edge caused by the step difference between the active region of the substrate and the device isolation film. have.

In addition, since the present invention adopts a rapid heat treatment method, the process time (10 hours each in the case of the furnace) required for the oxide film manufacturing process is reduced to about 1/2 (5 hours each for 100 sheets), thereby greatly increasing productivity.

Meanwhile, the present invention is not limited to the above-described embodiments, and various modifications may be made by those skilled in the art within the spirit and scope of the present invention.

Claims (13)

In the oxide film production method of a semiconductor device, Loading the wafer into a chamber for rapid heat treatment; Injecting oxygen and hydrogen gas into the rapid heat treatment chamber; And growing an oxide film having a uniform thickness in an oxygen atmosphere in which oxygen and hydrogen gas are reacted on the silicon surface of the wafer to form an oxygen atom and OH. The method of manufacturing a semiconductor device according to claim 1, wherein the reaction chamber has a temperature of 800 to 1200 ° C and a pressure of 0 to 200 Torr. The method of manufacturing a semiconductor device according to claim 1, wherein the temperature increase and the temperature decrease rate during the oxide film production process are 10 ° C / sec to 200 ° C / sec. The method of manufacturing a semiconductor device according to claim 1, wherein the oxygen gas and the hydrogen gas are supplied at a flow rate of 0 to 30 slm, respectively. In forming a device isolation film having a trench structure, Sequentially depositing a pad oxide film and a nitride film on the semiconductor substrate; Forming a trench to a predetermined depth of the substrate after patterning the nitride layer and the oxide layer by performing a photolithography and an etching process using a device isolation mask; Loading the substrate on which the trench is formed in the chamber for rapid heat treatment, injecting oxygen and hydrogen gas to grow a sacrificial oxide film on the sidewalls and bottom of the trench, and then removing it; And And forming a device isolation film by filling a gap fill oxide film in the trench of the substrate, and then planarizing the nitride film. The method of claim 5, further comprising forming a liner oxide film on the sidewalls and the bottom of the trench by injecting oxygen and hydrogen gas after loading the substrate in the rapid heat treatment chamber before forming the gapfill oxide film. A semiconductor device manufacturing method. The method of claim 5, wherein the temperature and pressure of the reaction chamber during the manufacturing process of the sacrificial oxide film is 800 to 1200 ℃ and 0 to 200 Torr to have the same thickness on the trench sidewall and the bottom, but having a thickness of 10 ~ 300Å A method for manufacturing a semiconductor device. The method of claim 6, wherein the temperature and pressure of the reaction chamber during the production process of the liner oxide film is 800 to 1200 ℃ and 0 to 200 Torr to form the same thickness on the trench sidewall and the bottom, but having a thickness of 10 ~ 300Å A method for manufacturing a semiconductor device. The method of manufacturing a semiconductor device according to claim 6, wherein the temperature increase and the temperature decrease rate during the manufacturing process of the liner oxide film are 10 ° C / sec to 200 ° C / sec. The method of manufacturing a semiconductor device according to claim 5, wherein the oxygen gas and the hydrogen gas are supplied at a flow rate of 0 to 30 slm, respectively. In the method of manufacturing a gate oxide film of a semiconductor device, Loading the wafer into a chamber for rapid heat treatment; Injecting oxygen and hydrogen gas into the rapid heat treatment chamber; And growing an oxide film having a uniform thickness in an oxygen atmosphere in which oxygen and hydrogen gas are reacted on the silicon surface of the wafer to form an oxygen atom and OH. The method of manufacturing a semiconductor device according to claim 11, wherein the surface of the silicon substrate is cleaned with hydrofluoric acid and aqueous ammonia before forming the gate oxide film. The method of manufacturing a semiconductor device according to claim 11, wherein the gate oxide film has a thickness of 10 to 100 microseconds.