CN1316564C - Composite photoresist layer structure - Google Patents

Abstract

The invention provides a composite photoresist layer structure, which comprises a first organic layer arranged on a surface to be etched; a sacrificial layer disposed on the first organic layer; and a second organic layer disposed on the sacrificial layer. Wherein the first organic layer is made of an organic material that is easily removable by plasma to prevent damage to the surface to be etched during a pattern transfer process.

Description

Composite photoresist layer structure

technical field

The invention relates to a photoresist layer structure, in particular to a composite photoresist layer structure used for the transfer of micro-sized patterns in semiconductor technology.

Background technique

Generally speaking, the photolithographic process and etching process in the semiconductor process are used to define various electronic units and interconnection structures in the integrated circuit. With the increasing demand for integration of integrated circuits, the exposure light source in the photolithography process has gradually shifted from g-line (436nm) or I-line (365nm) to light in the deep ultraviolet region, such as wavelengths of 248nm and 193nm exposure light source. For light sources with shorter wavelengths, the thickness of the corresponding photoresist is thinner. However, the photoresist is too thin to resist subsequent etching. Therefore, for a photolithography process using a short-wavelength exposure light source, it is necessary to find a suitable photoresist layer structure for the photolithography process and etching process.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a conventional photoresist layer structure. As shown in FIG. 1 , a semiconductor wafer 10 includes a substrate 12 , an antireflection layer 14 and a photoresist layer 16 . Since the wavelength of the exposure light source is directly proportional to the depth of focus (DOF), in order to accurately transfer the pattern on the mask to the photoresist layer 16, the thickness of the photoresist layer 16 must match The wavelength of the exposure light source, so for the light source in the deep ultraviolet region (such as less than 248nm), the thickness of the photoresist layer 16 can not be too thick, so as to ensure that the surface end near the photoresist layer 16 or The photoresist molecules on its bottom all have approximately the same focus. However, in the subsequent etching process, one of the functions of the photoresist layer 16 is to serve as an etching mask for the substrate 12. If the thickness of the photoresist layer 16 is too thin, it cannot effectively resist the etching process. invasion.

Please refer to FIG. 2 . FIG. 2 is a schematic diagram of another existing photoresist layer structure, which aims to overcome the above-mentioned problems. As shown in FIG. 2 , a semiconductor wafer 20 includes a substrate 22 , a silicon oxynitride layer 24 , an anti-reflection layer 26 and a photoresist layer 28 . The silicon oxynitride layer 24 is used as a hard mask to make up for the fact that the thickness of the photoresist layer 28 is too thin to resist the erosion of the etching process. In addition, after the pattern on the photomask is transferred into the substrate 22, the silicon oxynitride layer 24, the anti-reflection layer 26 and the photoresist layer 28 are subsequently removed. However, the removal step of the silicon oxynitride layer 24 is often The structure of the substrate 22 will be damaged.

In addition, the solution to the insufficient thickness of the photoresist layer also includes, one is to use the double-layer photoresist structure technology (US Patent No. 6,323,287), and the other is to use the top surface mapping (TSI (topsurface image)) technology (US Patent No. 6,296,989). However, these two methods must introduce a new photoresist material. For example, in the TSI technology, the photoresist layer is a silicon-containing photoresist material. And this will inevitably increase the complexity and difficulty of the process. In addition, the introduction of new photoresist materials will also increase the process cost. Therefore, it is necessary to seek a suitable photoresist layer structure for the photolithography process and the etching process. necessary.

Contents of the invention

The object of the present invention is to provide a composite photoresist layer structure for transfer printing of micro-sized patterns in semiconductor process, so as to solve the aforementioned problems.

According to the purpose of the present invention, a kind of composite photoresist layer structure is provided in the preferred embodiment of the present invention, and this composite photoresist layer structure comprises a first organic layer, is located on a surface to be etched, It is made of organic low dielectric constant material or spin-on-glass; a sacrificial layer is set on the first organic layer; and a second organic layer is set on the sacrificial layer. Wherein the first organic layer is made of an organic material that is easy to be removed by plasma, so as to avoid damaging the surface to be etched during the pattern transfer process.

The invention provides a composite photoresist layer structure, which includes a first organic layer, an inorganic sacrificial layer and a second organic layer. Due to the existence of the sacrificial layer and the first organic layer, the thickness of the second organic layer can be adjusted according to the wavelength of the exposure light source, and there will be no photoresist layer that is too thin to resist etching. Therefore, the photomask The predetermined pattern on the semiconductor wafer can be accurately transferred to the semiconductor wafer, and a preferred critical dimension (critical dimension, CD) control can be obtained. In addition, the first organic layer can be regarded as a hard mask, which can be easily removed by plasma, and the removal of the first organic layer causes relatively little damage to the substrate.

Description of drawings

Fig. 1 is the structural representation of existing photoresist layer;

Fig. 2 is a schematic diagram of another existing photoresist layer structure;

Fig. 3 is composite photoresist layer structure schematic diagram of the present invention;

4(A) to 4(F) are schematic diagrams utilizing a composite photoresist layer 30 in an etching process; and

FIG. 5 is a schematic diagram of the structure of a composite photoresist layer according to another embodiment of the present invention.

The reference signs in the accompanying drawings are explained as follows:

10 semiconductor wafer 12 substrate

14 anti-reflective layer 16 photoresist layer

20 semiconductor wafer 22 substrate

24 silicon oxynitride layer 26 anti-reflection layer

28 photoresist layer 30 composite photoresist layer

30a first organic layer 30b sacrificial layer

30c second organic layer 40 semiconductor wafer

42 substrates 50 semiconductor wafers

50a first organic layer 50b sacrificial layer

50c anti-reflection layer 50d second organic layer

Detailed ways

Please refer to FIG. 3 , which is a schematic diagram of the composite photoresist layer structure of the present invention. As shown in FIG. 3 , the composite photoresist layer 30 includes a first organic layer 30a, a sacrificial layer 30b disposed on the first organic layer 30a, and a second organic layer 30c disposed on the sacrificial layer 30b. Both the first organic layer 30a and the second organic layer 30c are made of organic materials, while the sacrificial layer 30b is made of inorganic materials.

Wherein, the first organic layer 30a can be easily removed by plasma, the first organic layer 30a can be made of organic low dielectric constant material (such as SiLK ^TM material), in addition, it can also be made of spin-on-glass (SOG (spin-on) glass)) layer, and the plasma can be oxygen, nitrogen, hydrogen, argon, C _x F _y , C _{x Hy} F _z or helium plasma. The sacrificial layer 30b can be composed of inorganic anti-reflection materials, such as silicon oxynitride (SiON) and silicon nitride. In addition, the sacrificial layer 30b can also be made of hard mask materials, such as silicon nitride and silicon oxide. And the second organic layer 30c can be an organic photoresist layer, and it can be positive photoresist and negative photoresist, in addition, the second organic layer 30c is not limited to organic photoresist material , which can also be made of organic materials suitable for e-beam lithography. The composite photoresist layer 30 can be applied to any photolithography process in the semiconductor process, so the thicknesses of the first organic layer 30a, the sacrificial layer 30b and the second organic layer 30c are adjusted according to the needs of the process, which should be are well known to those skilled in the art.

Please refer to FIG. 4(A) to FIG. 4(F). FIG. 4(A) to FIG. 4(F) are schematic diagrams of using the composite photoresist layer 30 in the etching process. As shown in FIG. 4A, a semiconductor wafer 40 includes a substrate 42 to be etched, and the composite photoresist layer 30 is formed on the substrate 42 to be etched, wherein the substrate 42 to be etched includes a silicon substrate, a metal Substrate and dielectric layer, etc. First, as shown in FIG. 4(B) and FIG. 4(C), an exposure process and a development process are performed to transfer the predetermined pattern on the photomask into the second organic layer 30c. Then, using the second organic layer 30c as an etching mask, the sacrificial layer 30b is subjected to an etching process so as to transfer the predetermined pattern in the second organic layer 30c to the sacrificial layer 30b. In addition, in another embodiment of the present invention, the predetermined pattern can also be formed in the second organic layer 30c by using electron beam lithography.

Next, as shown in FIG. 4(D) to FIG. 4(F), an anisotropic etching process is performed, and the sacrificial layer 30b is used as an etching mask to transfer the predetermined pattern in the sacrificial layer 30b to the first An organic layer 30a. Next, use the sacrificial layer 30b and the first organic layer 30a as an etching mask, and perform an etching process to transfer the predetermined pattern in the first organic layer 30a and the sacrificial layer 30b to the substrate 42 to be etched . Wherein, during the process of etching the substrate 42 to be etched, the sacrificial layer 30b will be removed together. After the predetermined pattern in the first organic layer 30 a is transferred into the substrate 42 to be etched, the first organic layer 30 a is removed immediately, and the pattern on the photomask is successfully transferred to the substrate 42 to be etched. Wherein, the first organic layer 30a can be regarded as a hard mask, which can make up for the insufficient thickness of the second organic layer 30c to resist the defects of etching. Therefore, the composite photoresist layer 30 of the present invention can be used for deep ultraviolet Exposure light source in the light area (such as laser light source with wavelength less than 248nm). In addition, the removal step of traditional hard mask materials (such as silicon nitride or silicon oxide) is usually performed in an acid bath, and this step often seriously damages the substrate 42 to be etched. However, the first organic layer 30a can be removed only by using plasma, which causes less damage to the substrate 42 to be etched.

Please refer to FIG. 5 , which is a schematic diagram of a composite photoresist layer structure according to another embodiment of the present invention. As shown in Figure 5, a composite photoresist layer 50 includes a first organic layer 50a, a sacrificial layer 50b disposed on the first organic layer 50a, an anti-reflection layer 50c disposed on the sacrificial layer 50b, And a second organic layer 50d disposed on the antireflection layer 50c. The first organic layer 50a is made of organic low dielectric constant material or SOG, which can be easily removed by plasma. The sacrificial layer 50b is made of a hard mask material including silicon nitride and silicon oxide. The anti-reflection layer 50c is an organic anti-reflection material (organic bottom ARC) such as polyimide (polyimide) and the like. In addition, the anti-reflection layer 50c may also be made of an inorganic anti-reflection material, such as silicon oxynitride (SiON). The second organic layer 50d can be an organic photoresist layer, which can be a positive photoresist or a negative photoresist. In addition, the second organic layer 50d is not limited to the organic photoresist material. , which can also be made of organic materials suitable for e-beam lithography. The anti-reflection layer 50c is used to prevent the incident light from being reflected back to the photoresist layer through the substrate, thereby forming a standing wave (standing wave) in the second organic layer 50d, thereby causing changes in the line width of the photoresist. . As mentioned above, the composite photoresist layer 50 can also be applied to any photolithography process in the semiconductor process, so the thicknesses of the first organic layer 50a, the sacrificial layer 50b, the antireflection layer 50c and the second organic layer 50d are It should be adjusted according to the needs of the process, which should be well known to those skilled in the art.

Compared with the prior art, the present invention provides a composite photoresist layer structure, which includes a first organic layer, an inorganic sacrificial layer and a second organic layer. The thickness of the second organic layer can be adjusted according to the wavelength of the exposure light source, and by adjusting the thicknesses of the sacrificial layer and the first organic layer, a sufficiently thick composite photoresist layer structure is provided to resist the erosion of the etching process, Therefore, the predetermined pattern on the photomask can be accurately transferred to the semiconductor wafer, and a preferred critical dimension (CD) control can be obtained. In addition, the first organic layer can be regarded as a hard mask, but it can be easily removed by plasma, and the removal step of the first organic layer will not cause serious damage to the substrate.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the patent of the present invention.

Claims (27)

1. A composite photoresist layer structure, comprising: A first organic layer, located on a surface to be etched, made of organic low dielectric constant material or spin-on-glass; a sacrificial layer disposed on the first organic layer; and A second organic layer is arranged on the sacrificial layer. 2. The composite photoresist layer structure as claimed in claim 1, wherein the surface to be etched is a silicon surface, a metal surface, or a dielectric layer surface. 3. The composite photoresist layer structure as claimed in claim 1, wherein the first organic layer is made of an organic material that is easy to be removed by plasma, so as to avoid damaging the surface to be etched during a pattern transfer process. 4. The composite photoresist layer structure of claim 3, wherein the plasma is oxygen _, nitrogen, hydrogen, _argon , _{CxFy , CxHyFz} or helium plasma. 5. The composite photoresist layer structure as claimed in claim 1, wherein the sacrificial layer is made of inorganic anti-reflection material. 6. The composite photoresist layer structure as claimed in claim 1, wherein the sacrificial layer is composed of silicon nitride, silicon oxide or silicon oxynitride. 7. The composite photoresist layer structure as claimed in claim 1, wherein the second organic layer is composed of an organic photoresist capable of absorbing light with a wavelength below 248 nm. 8. The composite photoresist layer structure as claimed in claim 1, wherein the second organic layer is suitable for electron beam lithography. 9. A photoresist layer structure for the transfer of micro-sized patterns in semiconductor technology, the photoresist layer structure comprising: A first organic layer, located on a surface to be etched; a sacrificial layer disposed on the organic layer; an anti-reflection layer disposed on the sacrificial layer; and A second organic layer is arranged on the anti-reflection layer. 10. The photoresist layer structure as claimed in claim 9, wherein the surface to be etched is a silicon surface, a metal surface, or a dielectric layer surface. 11. The photoresist layer structure as claimed in claim 9, wherein the first organic layer is made of an organic material that is easily removed by plasma, so as to avoid damaging the surface to be etched during a pattern transfer process. 12. The photoresist layer structure as claimed in claim 11, wherein the first organic layer is made of organic low dielectric constant material or spin-on-glass. 13. The photoresist layer structure of claim 11, wherein the _plasma is oxygen, nitrogen, hydrogen, _argon , _{CxFy , CxHyFz} or helium plasma. 14. The photoresist layer structure as claimed in claim 9, wherein the sacrificial layer is made of silicon nitride or silicon oxide. 15. The photoresist layer structure as claimed in claim 9, wherein the anti-reflection layer is made of organic anti-reflection material. 16. The photoresist layer structure as claimed in claim 15, wherein the antireflection layer is made of polyimide. 17. The photoresist layer structure as claimed in claim 9, wherein the anti-reflection layer is composed of inorganic anti-reflection materials. 18. The photoresist layer structure as claimed in claim 17, wherein the antireflection layer is composed of silicon nitride or silicon oxynitride. 19. The photoresist layer structure as claimed in claim 9, wherein the sacrificial layer is removed during a predetermined pattern transfer to the surface to be etched, and the first organic layer is in the predetermined pattern After being transferred to the surface to be etched, it is removed by plasma. 20. The photoresist layer structure as claimed in claim 9, wherein the second organic layer is composed of an organic photoresist capable of absorbing light with a wavelength below 248 nm. 21. The photoresist layer structure as claimed in claim 9, wherein the second organic layer is suitable for electron beam lithography. 22. A method of making a semiconductor element, comprising: providing a substrate; sequentially forming a first organic layer, a sacrificial layer, and a second organic layer on the substrate; performing a photolithography process to form a predetermined pattern in the second organic layer; using the second organic layer as an etching mask to etch the sacrificial layer to expose the surface of the first organic layer, so as to transfer the predetermined pattern into the sacrificial layer; using the sacrificial layer as an etching mask, etching the first organic layer up to the surface of the substrate, so as to transfer the predetermined pattern into the first organic layer; using the sacrificial layer and the first organic layer as an etching mask to etch the substrate to transfer the predetermined pattern into the substrate; and removing the first organic layer by plasma; Wherein the first organic layer is made of organic low dielectric constant material or spin-on-glass. 23. The method of claim 22 _, wherein the plasma is an oxygen, nitrogen, hydrogen, _argon , _{CxFy , CxHyFz} or helium plasma. 24. The method of claim 22, wherein the sacrificial layer is formed of silicon nitride or silicon oxide. 25. The method of claim 22, wherein the second organic layer is made of organic photoresist that can absorb light with a wavelength below 248 nm. 26. The method of claim 22, wherein the second organic layer is suitable for electron beam lithography. 27. The method of claim 22, wherein the substrate is a silicon substrate, a metal substrate, or a dielectric layer.

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