TWI883821B - Method for forming patterns - Google Patents

Abstract

The present disclosure provides a method for forming patterns. The method includes following steps. A first material layer is formed on a base layer. A hard mask pattern is formed on the first material layer in which a top surface of the first material layer includes regions exposed by the hard mask pattern. A surface treatment is performed on a top surface and sidewalls of the hard mask pattern and on the regions of the first material layer to form a protective material layer. Portions of the protective material layer that form on the top surface of the hard mask pattern and on the regions of the first material layer are removed to form a protective layer on sidewalls of the hard mask pattern. The first material layer exposed by the protective layer and the hard mask pattern is removed to form first patterns exposing the base layer.

Description

Method of forming pattern

The present invention relates to a method for forming a pattern, and more particularly to a method for forming a pattern in a semiconductor manufacturing process.

As the size of electronic devices continues to shrink and users' requirements for the performance of electronic devices continue to increase, how to form fine patterns has become one of the goals that technical personnel in this field are eager to work on.

In the current patterning process, the mask pattern formed on the material layer to be patterned usually includes a hard mask layer, so that the patterned material layer is formed into a fine pattern with excellent profile. However, in some patterning processes that use anisotropic etching (such as dry etching), the sidewalls of the hard mask layer will also be affected by the anisotropic etching, so that the width of the hard mask layer will become smaller and smaller due to the severity of the side etching (the side etching may become more and more severe as the etching time increases), so that the pattern cannot be well transferred to the material layer below. Therefore, technical personnel in this field are still continuing to improve the above-mentioned side etching situation.

The present invention provides a method for forming a pattern, which mitigates the effect of side etching by forming a protective layer on the sidewalls of a hard mask pattern. In this way, in a patterning process using anisotropic etching (e.g., dry etching), it is possible to prevent the hard mask layer from being severely etched and causing the pattern to be poorly transferred to the underlying material layer.

An embodiment of the present invention provides a method for forming a pattern, which includes: forming a first material layer on a base layer; forming a hard mask pattern on the first material layer, wherein the top surface of the first material layer includes an area exposed by the hard mask pattern; performing surface treatment on the top surface and side walls of the hard mask pattern and the area of the first material layer to form a protective material layer; removing a portion of the protective material layer formed on the top surface of the hard mask pattern and a portion of the protective material layer formed on the area of the first material layer to form a protective layer on the side walls of the hard mask pattern; and removing the first material layer exposed by the protective layer and the hard mask pattern to form a first pattern exposing the base layer.

In some embodiments, the surface treatment includes an oxidation process, and the protective material layer includes an oxide.

In some embodiments, the oxidation process is performed by controlling the temperature of the etching chamber between 20° C. and 60° C. and introducing a first process gas containing O ₂ and N ₂ into the etching chamber.

In some embodiments, the process of removing the portion of the protective material layer formed on the top surface of the hard mask pattern and the portion of the protective material layer formed in the region of the first material layer includes a cleaning process for removing native oxide.

In some embodiments, the cleaning process is performed in an etching chamber.

In some embodiments, the cleaning process includes introducing a second process gas containing _CF4 and Ar into the etching chamber.

In some embodiments, removing the first material layer exposed by the protective layer and the hard mask pattern is performed in the etching chamber.

In some embodiments, during the step of removing the first material layer exposed by the protective layer and the hard mask pattern, the protective layer is also removed.

In some embodiments, after forming the protection layer, the first material layer includes a groove formed under the protection layer.

In some embodiments, a top width of the first pattern is less than a width of the hard mask pattern, and a bottom width of the first pattern is approximately equal to a width of the hard mask pattern.

Based on the above, in the above-mentioned method for forming a pattern, the protective layer formed on the sidewall of the hard mask pattern can mitigate the effect caused by side etching, so that in a patterning process using anisotropic etching (such as dry etching), it can be avoided that the hard mask layer cannot be well transferred to the underlying material layer due to severe side etching.

The present invention is more fully described with reference to the drawings of the present embodiment. However, the present invention may be embodied in various forms and should not be limited to the embodiments described herein. The thickness of layers and regions in the drawings are exaggerated for clarity. The same or similar reference numbers represent the same or similar elements, and the following paragraphs will not be repeated one by one.

It should be understood that when an element is referred to as being "on" or "connected to" another element, it may be directly on or connected to another element, or there may be an intermediate element. If an element is referred to as being "directly on" or "directly connected to" another element, there are no intermediate elements. As used herein, "connection" may refer to physical and/or electrical connection, and "electrical connection" or "coupling" may be the presence of other elements between two elements. As used herein, "electrical connection" may include physical connection (e.g., wired connection) and physical disconnection (e.g., wireless connection).

As used herein, "about", "approximately" or "substantially" includes the referenced value and the average value within an acceptable deviation range of a specific value that can be determined by a person of ordinary skill in the art, taking into account the measurement in question and the specific amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, as used herein, "about", "approximately" or "substantially" can select a more acceptable deviation range or standard deviation depending on the optical properties, etching properties or other properties, and can apply to all properties without a single standard deviation.

The terms used herein are used to describe exemplary embodiments only, rather than to limit the present disclosure. In this case, unless otherwise explained in the context, the singular form includes the plural form.

1 to 4 are cross-sectional schematic views of a method for forming a pattern according to an embodiment of the present invention.

In some embodiments, a method of forming a pattern (such as the first pattern 114 shown in FIG. 4 ) may include the following steps.

First, referring to FIG. 1 , a first material layer 110 is formed on a base layer 100 .

The base layer 100 may include a semiconductor substrate and/or a dielectric layer and/or a conductor layer formed on the semiconductor substrate. That is, the base layer 100 may be a semiconductor substrate and/or a film layer and/or a structure formed in a front end of line (FEOL) and/or a back end of line (BEOL) process. For example, the base layer 100 may include components such as a semiconductor substrate, an inner dielectric layer and/or a contact window, an interlayer dielectric layer and/or a via window (such as an inner connection structure), an active element (such as a PMOS, NMOS, CMOS, JFET, BJT or a diode) or a driving element. However, for the sake of convenience of explanation, these components are not shown in the drawings.

The semiconductor material in the semiconductor substrate may include an elemental semiconductor, an alloy semiconductor, or a compound semiconductor. For example, the elemental semiconductor may include Si or Ge. The alloy semiconductor may include SiGe, SiGeC, etc. The compound semiconductor may include SiC, a III-V semiconductor material, or a II-VI semiconductor material. The III-V semiconductor material may include GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInNP, GaInNAs, GaInPAs, InAlNP, InAlNAs, or InAlPAs. Group II-VI semiconductor materials may include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnS e. CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe or HgZnSTe. The semiconductor material may be doped with a first conductivity type dopant or a second conductivity type dopant complementary to the first conductivity type. For example, the first conductivity type may be N type and the second conductivity type may be P type. The first material layer 110 may include SiCN.

Next, a hard mask pattern 120 is formed on the first material layer 110, wherein the top surface of the first material layer 110 includes an area exposed by the hard mask pattern 120. The hard mask pattern 120 may include silicon-rich SiON (may be represented as Si-SiON). In some embodiments, the hard mask pattern 120 may be formed by forming a hard mask material layer (not shown) on the first material layer 110 and then performing a patterning process on the hard mask material layer.

Then, referring to FIG. 1 and FIG. 2 , the top surface and sidewalls of the hard mask pattern 120 and the region of the first material layer 110 exposed by the hard mask pattern 120 are subjected to surface treatment to form a protective material layer 130. The protective material layer 130 may be conformally formed on the top surface and sidewalls of the hard mask pattern 122 and on the top surface of the first material layer 112 exposed by the hard mask pattern 122. In some embodiments, the surface treatment may include an oxidation process, and the protective material layer 130 may include an oxide such as silicon oxide (SiOx). In some embodiments, the oxidation process is to oxidize the portion of the top surface and the sidewall adjacent to the hard mask pattern 120 and the portion of the top surface of the first material layer 110 adjacent to the hard mask pattern 120, so that these portions are converted into oxides to form the protective material layer 130 containing the oxides. In some embodiments, the oxidation process is, for example, to control the temperature of the etching chamber between 20° C. and 60° C. and to introduce a first process gas containing O ₂ and N ₂ into the etching chamber. In semiconductor manufacturing processes, subtractive processes such as etching and additive processes such as deposition are generally performed in different chambers, and the process of forming the protective material layer 130 is scheduled after the subtractive process (for example, patterning the hard mask material layer to form the hard mask pattern 120), and the subsequent formation of the protective layer 132 shown in FIG. 3 and the first pattern 114 shown in FIG. 4 are also subtractive processes. Therefore, forming the protective material layer 130 in the etching chamber can avoid frequent switching of wafers between two different chambers, which has additional considerations such as stability, yield, time, and cost.

Then, referring to FIG. 2 and FIG. 3 , the portion of the protective material layer 130 formed on the top surface of the hard mask pattern 122 and the portion of the protective material layer 130 formed on the first material layer 112 are removed to form the protective layer 132 on the sidewall of the hard mask pattern 122. In some embodiments, the process of removing the portion of the protective material layer 130 formed on the top surface of the hard mask pattern 122 and the portion of the protective material layer 130 formed on the first material layer 112 includes a cleaning process for removing native oxide. In some embodiments, the cleaning process is performed in the same etching chamber as the one in which the protective material layer 130 is formed. In some embodiments, the cleaning process includes introducing a second process gas containing _CF4 and Ar into the etching chamber. In some embodiments, after forming the protection layer 132 , the first material layer 112 includes a groove formed under the protection layer 132 (communicating with the opening OP defined by the hard mask pattern 122 and the protection layer 132 ).

3 and 4, the first material layer 112 exposed by the protective layer 132 and the hard mask pattern 122 is removed through the opening OP to form a first pattern 114 exposing the base layer 100. The protective layer 132 formed on the sidewall of the hard mask pattern 122 can mitigate the effect of side etching, so that in a patterning process using anisotropic etching (e.g., dry etching), it can be avoided that the hard mask pattern 122 cannot be well transferred to the first material layer 112 below due to severe side etching. In some embodiments, removing the first material layer 112 exposed by the protective layer 132 and the hard mask pattern 122 is performed in the same etching chamber as that for forming the protective material layer 130 . In some embodiments, when the first pattern 114 has a high aspect ratio, the protective layer 132 formed on the sidewall of the hard mask pattern 122 can withstand severe etching conditions (e.g., a long etching time). Therefore, even if the protective layer 132 is removed during the step of removing the first material layer 112 exposed by the protective layer 132 and the hard mask pattern 122, the remaining hard mask pattern 124 is still sufficient to transfer the pattern to the underlying material layer well, so that the first pattern 114 has a desired pattern or profile. In some embodiments, the top width of the first pattern 114 may be smaller than the width of the hard mask pattern 124 , and the bottom width of the first pattern 114 may be approximately equal to the width of the hard mask pattern 124 .

In summary, in the method for forming a pattern of the above-mentioned embodiment, the protective layer formed on the sidewall of the hard mask pattern can mitigate the influence caused by the side etching. Thus, in the patterning process using anisotropic etching (e.g., dry etching), it can be avoided that the hard mask layer cannot be well transferred to the underlying material layer due to severe side etching.

100: base layer 110, 112: first material layer 114: first pattern 120, 122, 124: hard mask pattern 130: protective material layer 132: protective layer OP: opening

1 to 4 are cross-sectional schematic views of a method for forming a pattern according to an embodiment of the present invention.

100: Base layer

112: First material layer

122:Hard cover screen pattern

130: Protective material layer

Claims (9)

A method for forming a pattern, comprising: forming a first material layer on a base layer; forming a hard mask pattern on the first material layer, wherein the top surface of the first material layer includes an area exposed by the hard mask pattern; performing surface treatment on the top surface and side walls of the hard mask pattern and the area of the first material layer to form a protective material layer; removing the protective material layer formed on the top surface of the hard mask pattern; The protective layer is formed on the side wall of the hard mask pattern by removing the protective layer and the portion of the protective material layer formed on the area of the first material layer; and the first material layer exposed by the protective layer and the hard mask pattern is removed to form a first pattern exposing the base layer, wherein in the step of removing the first material layer exposed by the protective layer and the hard mask pattern, the protective layer is also removed. A method as described in claim 1, wherein the surface treatment includes an oxidation process, and the protective material layer includes an oxide. The method as claimed in claim 2, wherein the oxidation process is to control the temperature of the etching chamber between 20°C and 60°C and to introduce a first processing gas containing _O2 and _N2 into the etching chamber. The method of claim 3, wherein the process of removing the portion of the protective material layer formed on the top surface of the hard mask pattern and the portion of the protective material layer formed on the region of the first material layer includes a cleaning process for removing native oxide. A method as described in claim 4, wherein the cleaning process is performed in the etching chamber. A method as described in claim 5, wherein the cleaning process includes introducing a second processing gas containing _CF4 and Ar into the etching chamber. The method of claim 5, wherein the removal of the first material layer exposed by the protective layer and the hard mask pattern is performed in the etching chamber. The method of claim 1, wherein after forming the protective layer, the first material layer includes a groove formed under the protective layer. The method of claim 1, wherein the top width of the first pattern is smaller than the width of the hard mask pattern, and the bottom width of the first pattern is approximately equal to the width of the hard mask pattern.

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