CN103972080A - ONO structure and manufacturing method for ONO capacitor - Google Patents

Abstract

The invention discloses a method for manufacturing an ONO structure, comprising growing a first silicon oxide layer on a wafer surface by a plasma-enhanced atomic layer deposition process; growing nitrogen on the first oxide layer by a plasma-enhanced atomic layer deposition process a silicon nitride layer; and growing a second silicon oxide layer on the nitride layer by a plasma-enhanced atomic layer deposition process. The above steps are performed in situ in a plasma-enhanced atomic layer deposition apparatus. The invention can manufacture ONO structures with superior performance in the same equipment and the same process menu.

Description

ONO structure and manufacturing method of ONO capacitor

technical field

The invention relates to the technical field of integrated circuit manufacturing, in particular to an ONO structure and a method for manufacturing an ONO capacitor.

Background technique

Capacitor is a basic device in integrated circuit manufacturing. Since silicon oxide has a higher breakdown voltage and silicon nitride has a higher dielectric constant, in addition, silicon oxide has better adhesion to the upper and lower electrode plates, so ONO The (silicon oxide-silicon nitride-silicon oxide) structure is widely used as a dielectric capacitor.

The ONO structure is a stacked structure. For multi-layer composite films, the commonly used method in the prior art is that the top and bottom layers of silicon oxide are formed by thermal oxidation, and the middle layer of silicon nitride is formed by CVD deposition. But in this way, the three-layer film of ONO structure needs to be formed in different film growth machines (thermal oxidation equipment, CVD deposition equipment), which reduces the production efficiency; and the thickness control of each layer of film is also a difficult point in the production process. In addition, in the prior art, there is also a one-stop method of forming a three-layer film on the same machine, such as the sequential deposition of silicon oxide-silicon nitride-silicon oxide in PECVD. However, the quality of the film grown by PECVD deposition, especially the step Coverage and uniformity are not satisfactory.

Therefore, it is necessary to propose a method that can realize the fabrication of ONO structure in the same equipment, and the quality and performance of the formed ONO film are superior.

Contents of the invention

The main purpose of the present invention is to overcome the defects of the prior art, and provide a method that can complete the ONO structure fabrication with superior performance in the same equipment and the same process menu.

The present invention adopts the following technical scheme: a method for manufacturing an ONO structure, comprising the following steps: step 1, growing a first silicon oxide layer on the surface of a wafer by a plasma-enhanced atomic layer deposition process; step 2, using plasma-enhanced atomic layer deposition A deposition process grows a silicon nitride layer on the first oxide layer; and step 3, grows a second silicon oxide layer on the nitride layer by a plasma-enhanced atomic layer deposition process, wherein the above steps 1 and 2 and step 3 are performed in situ in a plasma-enhanced atomic layer deposition apparatus.

In a preferred technical solution of the present invention, step 1 includes: step 11, introducing a precursor into the chamber of the plasma atomic layer deposition equipment, and the precursor is adsorbed on the surface of the wafer; step 12, injecting Purge the chamber with inert gas; step 13, pass oxygen into the chamber and ionize it into oxygen plasma to oxidize the precursor to form the first silicon oxide thin layer; repeat the above steps 11 to 13 until the The first silicon oxide thin layer reaches a predetermined thickness to form the first silicon oxide layer.

In a preferred technical solution of the present invention, step 2 includes: step 21, introducing the precursor into the chamber of the plasma atomic layer deposition equipment, and the precursor is adsorbed on the surface of the first silicon oxide layer; step 22, blowing the inert gas into the chamber for purging; step 23, blowing nitrogen gas into the chamber and ionizing it into a nitrogen plasma to nitride the precursor to form a silicon nitride thin layer; repeat the above steps 21-23 until the silicon nitride thin layer reaches a predetermined thickness to form the silicon nitride layer.

In a preferred technical solution of the present invention, step 3 includes: step 31, introducing the precursor into the chamber of the plasma atomic layer deposition equipment, and the precursor is adsorbed on the surface of the silicon nitride layer; step 32 , pass the inert gas into the chamber for purging; step 33, pass oxygen into the chamber and ionize it into an oxygen plasma to oxidize the precursor to form a second silicon oxide thin layer; repeat the above step 31 ~33 until the second silicon oxide thin layer reaches a predetermined thickness to form the second silicon oxide layer.

In a preferred technical solution of the present invention, the temperature of the plasma atomic layer deposition process is 200°C to 400°C.

In a preferred technical solution of the present invention, the precursor is gaseous aminosilane.

In a preferred technical solution of the present invention, the inert gas is selected from nitrogen, argon or helium. .

The present invention also provides a kind of manufacture method of ONO electric capacity, comprise the following steps: provide substrate, be formed with lower electrode plate on described substrate; Form intermediate dielectric layer on described lower electrode plate, described intermediate dielectric layer is ONO structure; and forming an upper electrode plate on the intermediate dielectric layer, wherein the intermediate dielectric layer is formed by the above-mentioned ONO structure manufacturing method.

In a preferred technical solution of the present invention, the material of the upper electrode plate and the lower electrode plate is polysilicon or metal.

Compared with the prior art, the present invention can obtain silicon oxide and silicon nitride films with excellent performance (good uniformity and high breakdown voltage) through the one-stop growth ONO structure on PEALD equipment, and for the two kinds of films The thickness can be precisely controlled, which can significantly improve the quality of products that require precise control of capacitance performance.

Description of drawings

FIG. 1 is a flowchart of a method for fabricating an ONO structure according to an embodiment of the present invention.

Detailed ways

In order to make the content of the present invention clearer and easier to understand, the content of the present invention will be further described below in conjunction with the accompanying drawings. Of course, the present invention is not limited to this specific embodiment, and general replacements known to those skilled in the art are also covered within the protection scope of the present invention.

Please refer to 1, which shows a schematic flow chart of the ONO structure forming process proposed by the present invention.

The ONO structure is grown in situ in a plasma-enhanced atomic layer deposition (PEALD) device, and its fabrication method includes the following steps:

Step 1: growing the first silicon oxide layer.

In this step, the first silicon oxide layer is grown on the surface of the wafer by a plasma-enhanced atomic layer deposition (PEALD) process, and the specific process steps are as follows:

First, the precursor is introduced into the process chamber of the PEALD equipment. In this embodiment, the precursor is a gaseous aminosilane, such as gaseous 2Nte, and Ar is used as a carrier gas to pass into the chamber. During this process, 2Nte will be adsorbed on the surface of the wafer. The carrier gas used can be, but not limited to, Ar.

Next, an inert gas, such as Ar, is introduced into the process chamber for purging. The purpose of purging the chamber with a large flow of Ar is to remove the excess 2Nte on the wafer surface, so that the thickness of the 2Nte on the wafer surface meets the process requirements, such as leaving only the thickness of one molecular layer. The amount of inert gas used in this step can be based on requirements, and the excess precursor can be removed. In this embodiment, the inert gas used as the purge gas and the carrier gas are both Ar, and there is no need to introduce other gases in the process, and the process is less difficult to realize. In addition, the Ar as the carrier gas can be set at the same flow rate as the Ar for purging.

After that, oxygen gas is introduced into the process chamber and ionized to form oxygen plasma, and the oxygen plasma oxidizes the remaining 2Nte on the surface of the wafer to finally obtain the first silicon oxide thin layer. The thickness of the first silicon oxide thin layer is about 1A.

Then, repeat the above steps, on the surface of the wafer on which the first thin layer of silicon oxide has been formed, the adsorption of the precursor 2Nte, the purging of the inert gas Ar, and the steps of plasma oxidation are performed to form the second layer of the first oxide layer. thin layer of silicon. The above steps are repeated for several times, and the thickness of the first silicon oxide thin layer is controlled to reach a predetermined thickness through the number of cycles to form the first silicon oxide layer.

Step 2, growing the silicon nitride layer.

In this step, a silicon nitride layer is also grown on the surface of the first silicon oxide layer by the PEALD process. The process steps include the steps of 2Nte adsorption-Ar gas purging-nitrogen plasma oxidation, as follows:

First, the gaseous 2Nte precursor is introduced into the process chamber of the PEALD equipment with Ar as the carrier gas. During this process, 2Nte will be adsorbed on the surface of the first silicon oxide layer. The carrier gas used can be, but not limited to, Ar.

Next, pass Ar inert gas into the process chamber, and pass into the chamber with a large flow of Ar for purging, the purpose is to remove the excess 2Nte on the surface of the first silicon oxide layer, so that the thickness of 2Nte on the surface meets the process requirements, Such as the thickness of only one molecular layer. The amount of inert gas used in this step can be based on requirements, and the excess precursor can be removed. In this embodiment, the inert gas used as the purge gas and the carrier gas are both Ar, and there is no need to introduce other gases in the process, and the process is less difficult to realize. In addition, the Ar as the carrier gas can be set at the same flow rate as the Ar for purging.

Afterwards, nitrogen gas is introduced into the process chamber and ionized to form nitrogen plasma. The nitrogen plasma oxidizes 2Nte with a thickness of one molecular layer on the surface of the first silicon oxide layer, and finally obtains a thin silicon nitride layer. The thickness of the silicon nitride thin layer is about 0.2A.

The above-mentioned steps are repeated several times. Since a silicon nitride thin layer with a thickness of about 0.2A can be formed each time the above-mentioned steps are repeated, the thickness of the silicon nitride thin layer can reach a predetermined thickness by controlling the number of cycles to form an intermediate silicon nitride layer.

Step 3: growing the second silicon oxide layer.

In this step, the second silicon oxide layer is still grown on the surface of the silicon nitride layer by the PEALD process, and the process steps include the steps of 2Nte adsorption-Ar gas purging-oxygen plasma oxidation, as follows:

First, the gaseous 2Nte precursor is introduced into the process chamber of the PEALD equipment with Ar as the carrier gas. During this process 2Nte will be adsorbed on the surface of the silicon nitride layer. The carrier gas used can be, but not limited to, Ar.

Next, purge Ar inert gas into the process chamber, and pass a large flow of Ar into the chamber for purging. The purpose is to remove the excess 2Nte on the surface of the silicon nitride layer, so that the thickness of 2Nte on the surface meets the process requirements. Such as the thickness of only one molecular layer. The inert gas used in this step can be set according to requirements, and the excess precursor can be removed. In this embodiment, the inert gas used as the purge gas and the carrier gas are both Ar, and there is no need to introduce other gases in the process, and the process is less difficult to realize. In addition, the Ar as the carrier gas can be set at the same flow rate as the Ar for purging.

After that, oxygen gas is introduced into the process chamber and ionized to form oxygen plasma. The oxygen plasma oxidizes 2Nte with a thickness of one molecular layer on the surface of the silicon nitride layer, and finally obtains a second silicon oxide thin layer. The thickness of the second silicon oxide thin layer is about 1A.

Repeat the above steps for several times, since the second silicon oxide thin layer with a thickness of about 1A can be formed by repeating the above steps each time, the thickness of the second silicon oxide thin layer can reach a predetermined thickness by controlling the number of cycles to form second silicon oxide layer.

Since the formation of the above three thin films can be realized through one process menu in the same process chamber, the growth efficiency of the ONO structure is improved. Since the PEALD process relies on plasma-driven reactions, the temperature requirements are relatively low. In this embodiment, the process temperature of the PEALD process is 200°C-400°C. In addition, the film grown by the PEALD process has excellent quality, good uniformity and high breakdown voltage. It should be noted that in this embodiment, gaseous 2Nte is used as the precursor for surface adsorption, but in other embodiments, the precursor can also be other aminosilanes. In addition to Ar, the inert gas for purging the precursor may also be He or H ₂ .

Based on the manufacturing method of the above ONO structure, the present invention also proposes a manufacturing method of the ONO capacitor. The manufacturing method of the ONO capacitor will be described below in combination with specific embodiments.

For example, the dielectric thickness of the intermediate dielectric layer needs to be formed to meet the following requirements of the ONO capacitor structure: the intermediate dielectric layer is an ONO structure, wherein the thickness of the first silicon oxide layer is 30A, the thickness of the middle silicon nitride layer is 100A, and the second silicon oxide layer The layer thickness is 30A. The production steps are as follows:

First, a substrate is provided on which a Cu lower electrode plate is formed.

Then, create a craft menu Recipe that meets the requirements on the PEALD equipment. This crafting menu recipe is divided into three main steps.

First, the first silicon oxide layer is deposited according to the process shown in Figure 1, and the first silicon oxide layer is formed by performing the steps of "precursor adsorption-inert gas purge- _O2 plasma oxidation" in multiple cycles. The specific parameter settings can refer to the following:

The flow rate of gaseous aminosilane 2Nte is 1 mg/min, the carrier gas is Ar, and the carrier gas flow rate is 5000 sccm;

The inert gas used as purge gas is Ar, the flow rate is 5000 sccm, and the purge time is 1s;

The flow rate of oxygen _O2 for plasma treatment is 4000sccm, the radio frequency power RF for generating plasma is 2500W, and the plasma treatment time is 1.5s;

Since the first silicon oxide thin layer with a thickness of 1A is obtained each time the above steps are performed, the total number of cycles is set to be about 30, and a first silicon oxide layer of 30A will be obtained.

Then, the silicon nitride layer is deposited, and the silicon nitride layer is formed by performing the steps of "precursor adsorption-inert gas purging-N2 plasma nitriding" in multiple cycles. The specific parameter settings can refer to the following:

Gaseous aminosilane 2Nte flow rate: 1mg/min, the carrier gas is Ar, and the carrier gas flow rate is 5000sccm;

The inert gas used as purge gas is Ar, the flow rate is 5000 sccm, and the purge time is 1s;

The flow rate of nitrogen N2 for plasma treatment is 4000sccm, the radio frequency power RF for generating plasma is 2500W, and the plasma treatment time is 1.5s;

Since the first silicon oxide thin layer with a thickness of 0.2 Å is obtained each time the above steps are performed, the total number of cycles is about 500, and a silicon nitride layer of 100 Å will be obtained.

Finally, the deposition of the second silicon oxide layer is carried out, and its process and parameter settings are the same as those of the deposition of the first silicon oxide layer, which will not be repeated here.

When the deposition of the three-layer film is completed, the ONO dielectric structure is formed. Finally, the Cu upper electrode plate is deposited to obtain the corresponding ONO capacitor structure. In this embodiment, the upper and lower electrode plates are made of metal, but in other embodiments, the material of the upper and lower electrode plates may also be polysilicon.

In summary, the present invention realizes the one-stop growth of the ONO dielectric structure on the PEALD equipment by performing the in-situ deposition of the ONO structure by the PEALD process, thereby obtaining an excellent performance (good uniformity, high breakdown voltage) Silicon oxide and silicon nitride films, and the thickness of the two films can be precisely controlled, which has significant advantages for the manufacture of products that require precise control of capacitance performance.

Although the present invention has been disclosed as above with preferred embodiments, the various embodiments described are only examples for convenience of description, and are not intended to limit the present invention. Those skilled in the art can Some changes and modifications are made, and the scope of protection claimed by the present invention should be based on the claims.

Claims (9)

1. a manufacture method for ONO structure, is characterized in that, comprises the following steps:

Step 1, with plasma enhanced atomic layer deposition technique in crystal column surface growth regulation one silica layer;

Step 2, with plasma enhanced atomic layer deposition technique grown silicon nitride layer in described the first oxide layer; And

Step 3, with plasma enhanced atomic layer deposition technique growth regulation silicon dioxide layer on described nitration case,

Wherein, above-mentioned steps 1, step 2 and step 3 are carried out at plasma enhanced atomic layer deposition equipment situ.

2. the manufacture method of ONO structure according to claim 1, is characterized in that, step 1 comprises:

Step 11 passes into predecessor in the chamber of described plasma atomic layer deposition apparatus, and this predecessor is adsorbed in the surface of described wafer;

Step 12 passes into inert gas purge in described chamber;

Step 13, to passing into oxygen in described chamber and ionization is oxidized to form the first thin layer of silicon oxide for oxygen gas plasma to this predecessor;

Repeat above-mentioned steps 11～13 until described the first thin layer of silicon oxide reaches predetermined thickness and forms described the first silicon oxide layer.

3. the manufacture method of ONO structure according to claim 2, is characterized in that, step 2 comprises:

Step 21 passes into this predecessor in the chamber of described plasma atomic layer deposition apparatus, and this predecessor is adsorbed in the surface of described the first silicon oxide layer;

Step 22 passes into this inert gas purge in described chamber;

Step 23, carries out nitrogenize to form thin layer of sin to this predecessor to passing into nitrogen ionization in described chamber for nitrogen gas plasma;

Repeat above-mentioned steps 21～23 until described thin layer of sin reaches predetermined thickness and forms described silicon nitride layer.

4. the manufacture method of ONO structure according to claim 3, is characterized in that, step 3 comprises:

Step 31 passes into this predecessor in the chamber of described plasma atomic layer deposition apparatus, and this predecessor is adsorbed in the surface of described silicon nitride layer;

Step 32 passes into this inert gas purge in described chamber;

Step 33, to passing into oxygen in described chamber and ionization is oxidized to form the second thin layer of silicon oxide for oxygen gas plasma to this predecessor;

Repeat above-mentioned steps 31～33 until described the second thin layer of silicon oxide reaches predetermined thickness and forms described the second silicon oxide layer.

5. the manufacture method of ONO structure according to claim 4, is characterized in that, the temperature of described plasma atom layer deposition process is 200 DEG C～400 DEG C.

6. according to the manufacture method of the ONO structure described in claim 1～5 any one, it is characterized in that, described predecessor is gaseous ammonia base silane.

7. according to the manufacture method of the ONO structure described in claim 1～5 any one, it is characterized in that, described inert gas is selected from nitrogen, argon gas or helium.

8. a manufacture method for ONO electric capacity, is characterized in that, comprises the following steps:

Substrate is provided, on described substrate, is formed with lower electrode plate;

On described lower electrode plate, form middle dielectric layer, described middle dielectric layer is ONO structure; And

On described middle dielectric layer, form electric pole plate,

Wherein, described middle dielectric layer forms by the manufacture method described in claim 1～7 any one.

9. the manufacture method of ONO electric capacity according to claim 8, is characterized in that, the material of described electric pole plate and lower electrode plate is polysilicon or metal.