CN1195315C - Multiple-layer type dielectric antireflection layer and its forming method - Google Patents

Abstract

A multi-layer dielectric anti-reflection layer is suitable for use between a substrate and a photoresist layer. A first dielectric anti-reflection layer is sequentially formed on the substrate, and then a special dielectric anti-reflection layer is formed on the first dielectric anti-reflection layer. The plasma treatment, such as N ₂ O plasma enhanced, forms the first plasma thin film. Wherein the first dielectric anti-reflection layer and the first plasma thin film form an anti-reflection layer combination. Then sequentially form N layers of the antireflection layer combination on the first plasma film to form a multilayer dielectric antireflection layer, wherein N is a natural number between 1-4.

Description

Multilayer dielectric anti-reflection layer and method for forming same

technical field

The present invention relates to a semiconductor lithography process, in particular to an anti-reflection layer in the lithography process, and more specifically to a multi-layer dielectric anti-reflection layer and its forming method.

Background technique

With the improvement of the integration level of semiconductor components, the line width requirements of semiconductor components are getting smaller and smaller, and the control of critical dimension (CD) is becoming more and more important. In the photolithography process, since the surface of the wafer has a height difference, when the photoresist covers the surface of the wafer, the thickness of the photoresist layer will vary with the planarization of the photoresist. . When the lithography light travels in the photoresist, the reflected light on the wafer surface and the incident light will form a gain/loss interference phenomenon, thus producing the so-called swing effect. The uneven thickness of the above-mentioned photoresist and the swing effect will both cause adverse effects of critical dimension changes.

Due to the widespread use of more and more highly reflective substrates, such as silicon substrates or metal substrates, the reflection problem in the deep ultraviolet light band is greater than that in the visible light band, which leads to standing wave effect and notching effect in the photoresist layer It will be more serious, so that the pattern transfer reliability of the photolithography process will be greatly reduced.

In order to avoid the swing effect, the following two methods are generally used. The first way is achieved by spin coating the bottom anti-reflection layer (Bottom Anti-Reflection Coating, BARC). FIG. 1 shows a photolithographic structure 1 of an existing bottom anti-reflection layer, illustrating the existing design of improving the swing effect by using the BARC layer. Generally, before coating the photoresist layer 16, a layer of bottom anti-reflection layer (BARC) 14 is coated on the substrate 10 in a spin-on manner, with a thickness of about 1000-2000 Å, and then coated on it. A photoresist layer 16 is laid. Generally, the bottom anti-reflection layer (BARC) 14 often adopts an organic thin film. When projecting a lithography irradiation light 11 on the substrate, the organic component (Organic Dye) in the organic thin film can absorb the light reflected by the substrate to reduce the line width. variation. However, this coating still produces fluctuations with the flatness of the wafer surface, such as the device 12 , and cannot achieve stable phase shift.

The second way is to use chemical vapor deposition (CVD) to grow a dielectric anti-reflection layer (Dielectric Anti-Reflection Coating, DARC). Figure 2 shows a photolithographic structure of an existing dielectric anti-reflection coating, illustrating the existing design of improving the swing effect with a DARC layer. Mainly, a dielectric anti-reflection layer with a thickness of about 300 Å is formed on the substrate 20 by chemical vapor deposition (CVD), and then a photoresist layer 26 is formed thereon. This method is especially suitable for deep ultraviolet lithography. The DARC layer is less affected by the layout fluctuation of the wafer surface, such as element 22, and the main feature of this method is that it can adjust the material (Si, O, N or C) ratio of the DARC layer or change the CVD process parameters. Such as gas flow rate, pressure, etc., the refractive index (refractive index) n and absorption coefficient (extinction coefficient) k value of the DARC layer can be adjusted to achieve a good phase shift, and form lossy interference to eliminate the reflected light of the substrate 20 .

However, adjusting the n and k values of the above-mentioned DARC layer thickness often has different technical difficulties according to different process requirements. If you want to adjust the n and k values of the DARC layer to the best conditions according to different process requirements, so that the light reflected by the substrate can form good lossy interference and be eliminated, you need to constantly adjust the process of forming the DARC layer. various conditions.

Contents of the invention

In order to provide greater flexibility to adjust the n and k values of the DARC layer, an object of the present invention is to provide a multilayer dielectric antireflection layer and a method for forming the same, so as to achieve the optimal relationship between the refractive index n and the absorption coefficient k value.

In order to achieve the above object, the present invention provides a multi-layer dielectric anti-reflection layer, which is suitable for use between a substrate and a photoresist layer, comprising: a first dielectric anti-reflection layer located on the substrate; a first The plasma film is located on the first dielectric anti-reflection layer; and the combination of N layers of anti-reflection layers is located on the first plasma film, wherein N is a natural number between 1-4, and each anti-reflection The reflective layer combination includes a dielectric antireflection layer and a plasma thin film on the dielectric antireflection layer.

The multi-layer dielectric antireflection layer also includes a top layer dielectric antireflection layer located on the N-layer antireflection layer combination.

The N layers are 3 layers.

The dielectric anti-reflection layer is silicon oxynitride formed by plasma enhanced chemical vapor deposition.

The plasma thin film is formed by N ₂ O plasma treatment.

The plasma thin film is formed by one or a combination of the following plasma treatments: He, Ar, O ₂ , and N ₂ .

The total thickness of the multilayer dielectric anti-reflection layer is between 1000 and 2000 Å.

The present invention also provides a method for forming a multilayer dielectric anti-reflection layer, which is suitable for use between a substrate and a photoresist layer, and includes the following steps: forming a first dielectric anti-reflection layer on the substrate; The first dielectric antireflection layer is placed in a gas plasma to form a first plasma film on the first dielectric antireflection layer; and repeatedly forming N layers of antireflection layer combinations on the first plasma film , wherein N is a natural number between 1-4, and wherein each anti-reflection layer combination includes a dielectric anti-reflection layer and a plasma film on the dielectric anti-reflection layer.

The method for forming a multi-layer dielectric antireflection layer further includes a step of forming a top dielectric antireflection layer on the combination of N layers of antireflection layers.

The N layers are 3 layers.

The dielectric anti-reflection layer is silicon oxynitride formed by plasma enhanced chemical vapor deposition.

The gas plasma is N ₂ O plasma.

The gas plasma is selected from one or a combination of the following plasmas: He, Ar, O ₂ and N ₂ .

The total thickness of the multilayer dielectric anti-reflection layer is between 1000 and 2000 Å.

The dielectric anti-reflection layer is placed in the gas plasma for 5 to 20 seconds.

The present invention also provides a method for forming a multi-layer dielectric anti-reflection layer, which includes the following steps: a. depositing a dielectric anti-reflection layer; b. placing the dielectric anti-reflection layer in a plasma gas for the above-mentioned A plasma thin film is formed on the dielectric antireflection layer, wherein the dielectric antireflection layer and the plasma thin film on the dielectric antireflection layer constitute a first antireflection layer combination; c. measure the first antireflection layer combination absorption coefficient and refractive index; and repeating steps a, b and c to form a multilayer dielectric anti-reflection layer, which also includes performing simulation trials based on the measured absorption coefficient and refractive index before repeating step a to Determine the composition, thickness and plasma treatment process conditions of each anti-reflection layer in the multi-layer dielectric anti-reflection layer.

The dielectric anti-reflection layer is silicon oxynitride formed by plasma enhanced chemical vapor deposition.

The plasma gas is N ₂ O plasma.

The gas plasma is selected from one or a combination of the following plasmas: He, Ar, O ₂ and N ₂ .

The steps a and b are repeated 2 to 5 times.

The total thickness of the multilayer dielectric anti-reflection layer is between 1000 and 2000 Å.

The step b is to place the dielectric anti-reflection layer in the gas plasma for 5 to 20 seconds.

A multi-layer dielectric anti-reflection layer and its forming method according to the present invention are suitable for use between a substrate and a photoresist layer. A first dielectric anti-reflection layer is first formed on the substrate, and then the first dielectric anti-reflection layer is formed. A dielectric antireflection layer is placed in a gas plasma to form a first plasma film, and wherein the first dielectric antireflection layer and the first plasma film form an antireflection layer combination. Next, N layers of the anti-reflection layer combination are sequentially formed on the first plasma thin film, wherein N is a natural number between 1-4. Through the above method, a multi-layer dielectric anti-reflection layer structure is formed.

In the above structure, it may further include a top dielectric anti-reflection layer formed on the N layer of the anti-reflection layer combination.

In a preferred embodiment, the value of N is 3, so as to form a total of four anti-reflection layer combinations as a multi-layer dielectric anti-reflection layer. The dielectric anti-reflection layer mentioned therein can be formed by plasma enhanced chemical vapor deposition (PECVD) to form a silicon oxynitride film (SiOxNyHz). The gas plasma mentioned above can be N ₂ O, He, Ar, N ₂ , O ₂ . In the above structure, the dielectric layer can be placed in the gas plasma for 5 to 20 seconds to complete the plasma treatment reaction. The total thickness of the multilayer dielectric anti-reflection layer can be between 1000 and 2000 Å.

In order to make the above objects, features, and advantages of the present invention more comprehensible, a detailed description is given below with reference to the accompanying drawings.

Description of drawings

Fig. 1 shows the lithographic structure of an existing bottom anti-reflection layer;

Fig. 2 shows the lithographic structure of an existing dielectric anti-reflection coating;

Fig. 3 shows that in an embodiment of the present invention, the first structure of the anti-reflection coating;

Fig. 4 shows that in an embodiment of the present invention, the second structure of the anti-reflection coating;

FIG. 5 shows the third structure of the anti-reflection coating in an embodiment of the present invention.

Detailed ways

Fig. 3 to Fig. 5 have represented the structure of three kinds of antireflection coatings in one embodiment of the present invention, and the comparison of the multilayer dielectric antireflection layer according to this embodiment and two kinds of dielectric antireflection layer structures in detail below result. The equipment used is the Producer machine of Taiwan Applied Materials Company, and the measured values are all measured by Thermal Wave OP 5340.

structure one

Figure 3 shows structure 1, a common anti-reflection layer structure. On the substrate 30, a 1200 Å SiON dielectric layer 32 is deposited by chemical vapor deposition. After the deposition, it is divided into three processing methods, respectively forming a plasma film 34 on the dielectric layer 32, such as utilizing N ₂ O plasma for 20 seconds (I), or utilizing He plasma for 20 seconds (II), or No plasma treatment (III) was performed.

structure two

Figure 4 shows structure 2, a dielectric anti-reflection layer structure deposited multiple times. On the substrate 40, four layers of SiON dielectric layers with a thickness of 300 Å are deposited four times by chemical vapor deposition to form a dielectric layer with a total thickness of 1200 Å as the anti-reflection layer 42 . However, no plasma treatment was performed between any interfaces in between.

Structure three

FIG. 5 shows structure three, a multilayer dielectric antireflection layer structure according to an embodiment of the present invention. On the substrate 50, a layer of 300 Å silicon oxynitride film (SiOxNyHz) is deposited as the SiON dielectric layer 52 by means of plasma enhanced chemical vapor deposition. Then N2O plasma is used for 20 seconds to form a plasma thin film 54 thereon. The SiON dielectric layer 52 and the plasma film 54 form an anti-reflection combination X. Then, three layers of anti-reflection combination X are formed repeatedly in sequence to form a total dielectric anti-reflection layer of a total of four anti-reflection combinations with a dielectric layer interspersed with a plasma thin film. Next, Table 1 illustrates the comparison results of the above three structures.

Table 1

T ^* /NU ^# % RI ^** /NU ^# % k ^*** /NU ^# % 300  structure two 307/1.09 1.853/2.04 0.6757/3.12 Structure three 302/1.10 1.772/1.86 0.6487/3.21 900  structure two 867/0.86 1.990/0.18 0.410/1.30 Structure three 872/0.76 1.924/0.22 0.372/2.30

1200  Structure one (I) 1170/0.91 1.971/0.505 0.446/5.07 Structure one (II) 1171/0.89 1.987/0.245 0.443/3.86 Structure One (III) 1177/0.90 1.989/0.226 0.443/2.205 structure two 1146/0.87 1.983/0.30 0.43 14/3.235 Structure three 1152/0.78 1.936/1.85 0.3713/4.638

^* : thickness (Thickness, T)

^** : Refractive Index (Refractive Index, RI) n

^*** : Absorption Coefficient (Extinction Coefficient) k

#: Non-uniformity (Non-Uniformity, NU)

In Table 1, firstly, I, II and III of structure 1 in which only 1200 Å of the antireflection layer is deposited once are compared. Where T is the actual measured thickness of the deposited DARC layer. Comparing the RI(n) and k values of the three, it can be seen that there is no big difference between III without plasma treatment, 1 treated with N ₂ O for 20 seconds, and II treated with He for 20 seconds. After a DARC layer with a sufficient thickness, whether it undergoes plasma treatment or not has little change in its thickness and n and k values.

Next, the property changes of structures 2 and 3 at a thickness of 300 Å were compared. It can be seen from the data in the table that the RI(n) and k values of structure 2 without plasma treatment and structure 3 treated with N ₂ O for 20 seconds are significantly different. It is shown that the n and k values of the anti-reflection layer can be significantly changed after the first part of the thickness is deposited and treated by plasma.

Next, the property changes of structures 2 and 3 at a thickness of 900 Å were compared. The change of the data in the table shows the same trend, there is also a significant difference between the n and k values in the 900 Å layer between the structure 2 without plasma treatment and the structure 3 treated with N ₂ O for 20 seconds.

Compare the property changes of structure 1 (I), structure 2 and structure 3 in the same 1200 Å layer. Pairwise comparisons show that the n and k values of structure 1 (I) deposited at a time of 1200 Å and structure 2 after 20 seconds of N2O plasma treatment, or structure 3, have obvious differences. And the difference of n and k values between structure 2 and structure 3 is quite obvious.

Overall, the n and k values of the multilayer dielectric antireflection layer structure III designed according to the present invention and treated with N ₂ O plasma for 20 seconds tend to decrease. And compared with structure II without plasma treatment, both are significantly different.

Therefore, through the comparison of the above three structures, it can be clearly known that the value of n and k of each anti-reflection combination x can be adjusted and changed by using the multi-layer anti-reflection layer. Referring to Figure 5, a multi-layer DARC structure is used instead of a single layer of anti-reflection. When the lithography light 51 enters the photoresist layer, the reflected light at the interface 54 of each layer and the substrate 50 can achieve effective loss due to the adjustment of the n and k values of the dielectric anti-reflection layer and the plasma-enhanced anti-reflection layer Sexual interference, eliminating the interference of the reflected light from the bottom substrate on the photolithography process.

Therefore, according to the present invention, a method for forming a multi-layer dielectric anti-reflection layer is proposed to realize the adjustment of RI and K values, which can be realized by a multi-stage plasma-enhanced chemical vapor deposition method, each stage forming Part of the overall thickness. The interlayer concentration of the anti-reflection layer can be changed by proper plasma surface treatment, and the optical properties of the anti-reflection layer can be properly adjusted by adjusting the composition or the conditions of plasma treatment.

Referring to FIG. 5, a method for forming a multilayer dielectric anti-reflection layer according to the present invention will be described. First, a dielectric layer 52 is deposited on the substrate 50 . Wherein, the substrate 50 can be a semiconductor silicon base, which includes multiple semiconductor elements, and the dielectric layer 52 can use plasma enhanced chemical vapor deposition (PECVD) 300 Å silicon oxynitride film (SiOxNyHz) as the SiON dielectric layer 52, then The material and forming method of the dielectric layer are not limited thereto.

Then the dielectric layer 52 is treated with plasma for an appropriate time, such as N ₂ O plasma for 5 to 20 seconds, so as to form a plasma film 54 . In this way, the dielectric layer 52 and the plasma film 54 form an anti-reflection combination X. Next, several layers of anti-reflection layers are formed sequentially and repeatedly as required, preferably 2-5 anti-reflection combinations X are formed, more preferably four layers of anti-reflection combinations X are formed on the substrate 50 . Finally, a multi-layer dielectric anti-reflection layer is formed between the dielectric layer and the plasma thin film, the total thickness of which can be between 500-2000 Å, preferably about 1000 Å. Finally, a photoresist layer 56 is formed thereon.

In the above method, the preferred plasma treatment condition is to introduce about 85% N ₂ O gas, mixed with 15% oxygen, and activate the plasma with RF energy ranging from 500 to 1500 watts. Other plasma gases that may be employed may include _O2 , _N2 , Ar, He, and the like.

In the present invention, the above-mentioned multi-layer dielectric anti-reflection layer structure can be simulated first to determine the composition, thickness and plasma treatment conditions of each layer according to different processes and adjustment conditions. By choosing an anti-reflection combination with different numbers of layers. Between the substrate and the photoresist layer, a 2-5-layer anti-reflection composite stack structure can be formed, so as to obtain the best N and K values according to various process conditions, and realize the ideal elimination of reflected light in the photolithography process Purpose.

In the above-mentioned multi-layer dielectric anti-reflection layer structure, the thickness range of each layer can also be adjusted according to the process requirements and effects. The thickness of each anti-reflection combination X can be the same or different, and can be adjusted according to its anti-reflection effect. The deposition thickness of each dielectric layer in each anti-reflection combination X may be the same or different, depending on its anti-reflection performance.

Although the present invention is disclosed above through preferred embodiments, it is not intended to limit the present invention. Those skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention What is defined in the claims shall prevail.

Claims (22)

1. a multiple-layer type dielectric antireflection layer is applicable between a substrate and the photoresist layer, it is characterized in that it comprises:

One first dielectric anti-reflective layer is positioned on this substrate;

One first plasma foil is positioned on this first dielectric anti-reflective layer; And

The combination of the anti-reflecting layer of N layer is positioned on this first plasma book film, and wherein N is a natural number, and between 1-4, and wherein each anti-reflecting layer combination comprises a dielectric anti-reflective layer and and is positioned at plasma foil on this dielectric anti-reflective layer.

2. multiple-layer type dielectric antireflection layer as claimed in claim 1 is characterized in that also comprising a top layer dielectric anti-reflective layer, is positioned on the described N layer anti-reflecting layer combination.

3. multiple-layer type dielectric antireflection layer as claimed in claim 1 is characterized in that described N layer is 3 layers.

4. multiple-layer type dielectric antireflection layer as claimed in claim 1 is characterized in that described dielectric anti-reflective layer is for passing through the formed silicon oxynitride of plasma enhanced chemical vapor deposition.

5. multiple-layer type dielectric antireflection layer as claimed in claim 1 is characterized in that described plasma foil is with N ₂O plasma treatment and forming.

6. multiple-layer type dielectric antireflection layer as claimed in claim 1 is characterized in that described plasma foil is to be formed by one of following plasma or its combined treatment: He, Ar, O ₂, and N ₂

7. multiple-layer type dielectric antireflection layer as claimed in claim 1, the gross thickness that it is characterized in that described multiple-layer type dielectric antireflection layer is between between 1000 to 2000 .

8. a method that forms multiple-layer type dielectric antireflection layer is applicable between a substrate and the photoresist layer, is to comprise the following step:

On this substrate, form one first dielectric anti-reflective layer;

This first dielectric anti-reflective is placed in the gaseous plasma, on the described first dielectric anti-reflective layer, to form one first plasma foil; And

Repeat to form N layer anti-reflecting layer combination on this first plasma foil, wherein N is a natural number, and between 1-4, and wherein each anti-reflecting layer combination comprises a dielectric anti-reflective layer and and is positioned at plasma foil on this dielectric anti-reflective layer.

9. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that, also comprises a step: form a top layer dielectric anti-reflective layer in described N layer anti-reflecting layer combination.

10. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that described N layer is 3 layers.

11. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that described dielectric anti-reflective layer is by the formed silicon oxynitride of plasma enhanced chemical vapor deposition.

12. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that described gaseous plasma is N ₂The O plasma.

13. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that described gaseous plasma is to be selected from one of following plasma or its combination: He, Ar, O ₂With N ₂

14. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8, the gross thickness that it is characterized in that described multiple-layer type dielectric antireflection layer is between between 1000 to 2000 .

15. the method for formation multiple-layer type dielectric antireflection layer as claimed in claim 8 is characterized in that described dielectric anti-reflective was placed in the gaseous plasma 5 to 20 seconds.

16. the formation method of a multiple-layer type dielectric antireflection layer is characterized in that it comprises the following step:

A. deposit a dielectric anti-reflective layer;

B. this dielectric anti-reflective is placed in the plasma gas, to form a plasma film on above-mentioned dielectric anti-reflective layer, wherein this dielectric anti-reflective layer constitutes the combination of one first anti-reflecting layer with this plasma film that is positioned on this dielectric anti-reflective layer;

C. measure the absorption coefficient and the refractive index of this first anti-reflecting layer combination; And

Repeating step a, b and c, to form a multiple-layer type dielectric antireflection layer, wherein also be included in before the repeating step a, simulate composition, thickness and the plasma-treating technology condition of tentative calculation according to measured absorption coefficient and refractive index earlier to determine each anti-reflecting layer in the described multiple-layer type dielectric antireflection layer.

17. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16 is characterized in that described dielectric anti-reflective layer is by the formed silicon oxynitride of plasma enhanced chemical vapor deposition.

18. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16 is characterized in that described plasma gas is N ₂The O plasma.

19. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16 is characterized in that described gaseous plasma is to be selected from one of following plasma or its combination: He, Ar, O ₂With N ₂

20. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16 is characterized in that described step a and b are repetition 2 to 5 times.

21. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16, the gross thickness that it is characterized in that described multiple-layer type dielectric antireflection layer are between 1000 to 2000 .

22. the formation method of multiple-layer type dielectric antireflection layer as claimed in claim 16 is characterized in that described step b was placed on described dielectric anti-reflective in the gaseous plasma 5 to 20 seconds.

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