TW201303962A - Method for forming contact holes - Google Patents

Abstract

In an exemplary method for forming contact holes, a substrate overlaid with an etching stop layer and an interlayer dielectric layer in that order is firstly provided. A first etching process then is performed to form at least a first contact opening in the interlayer dielectric layer. A first carbon-containing dielectric layer subsequently is formed overlying the interlayer dielectric layer and filling into the first contact opening. After that, a first anti-reflective layer and a first patterned photo resist layer are sequentially formed in that order overlying the carbon-containing dielectric layer. Next, a second etching process is performed by using the first patterned photo resist layer as an etching mask to form at least a second contact opening in the interlayer dielectric layer.

Description

Contact hole forming method

The present invention relates to a method of forming a contact hole on a semiconductor element, and more particularly to a method of forming a contact hole using a double patterning technique.

With advances in semiconductor processes and miniaturization of microelectronic components, the density of semiconductor components on a single wafer is increasing, and the spacing between opposing components is becoming smaller. This makes the contact hole etching process more difficult.

The conventional contact hole method uses a photoresist layer as a mask to etch the underlying inner layer dielectric (ILD) layer. Especially in the 28 nm process, the pitch of the contact hole etching, that is, the distance between the center points of the two adjacent contact holes, must be less than 110 nm, and the after development inspect critical dimension, ADICD) must be approximately 55 to 70 nm. With regard to the current single exposure patterning (SP) yellow light machine technology, contact holes with a pitch of less than 110 nm cannot be completed in one exposure process.

In order to solve the above problems, it is common practice in the industry to form a contact hole by using a double patterning technique. For example, using a lithography-lithography-etching (LLEho-Litho-Etch (LLE) process, two photoresist layers are used to expose the photoresist layer twice, and then an etch is performed to allow the underlying dielectric layer to be underneath. A contact hole is formed in the middle. Or use the lithography-etching-lithography-etching (Litho-Etch-Litho-Etch, LELE) process, using two masks to expose the two photoresist layers twice, and to etch the light twice. The resist pattern is transferred into the hard mask layer and an etching is performed to form a contact hole in the lower dielectric layer.

However, since the yellow light process is often developed due to critical dimensions (Critical Dimension, CD), or misalignment or defocus, the yellow light process needs to be stripped of the photoresist for rework. This may damage the pattern formed by the first photoresist layer development (or etching) process on the photoresist or hard mask, thereby affecting subsequent process yield.

Therefore, there is a need to provide a contact hole forming method that is not affected by photoresist rework to improve the process yield of a semiconductor device.

In view of the above, an object of the present invention is to provide a contact hole forming method comprising the steps of first providing a substrate on which an etch stop layer and an inner dielectric layer are sequentially covered. A first etching process is then performed to form at least one first opening in the inner dielectric layer. A first carbon-containing dielectric layer is formed over the inner dielectric layer to fill the first opening. Thereafter, a first anti-reflective layer and a first patterned photoresist layer are sequentially formed on the first carbon-containing dielectric layer. Then, the first patterned photoresist layer is used as an etching mask, and a second etching process is performed to form at least one second opening in the inner dielectric layer.

In an embodiment of the invention, the forming of the first anti-reflective layer and the first patterned photoresist layer may include a photoresist rework process.

In an embodiment of the invention, the forming of the first anti-reflective layer comprises the steps of first forming a first bottom anti-reflective coating (BARC) on the first carbon-containing dielectric layer. Then, a first dielectric anti-reflective coating (DARC) is formed on the first bottom anti-reflective layer.

In an embodiment of the invention, the forming of the first opening includes the steps of: sequentially forming a second carbon-containing dielectric layer, a second anti-reflective layer, and a second patterning on the inner dielectric layer. Photoresist layer. Then, the second patterned photoresist layer is used as an etching mask, and a first etching process is performed to form a first opening in the inner dielectric layer.

In an embodiment of the invention, after the forming the first opening, further comprising stripping the second carbon-containing dielectric layer, the second anti-reflective layer, and the second patterned photoresist layer.

In an embodiment of the invention, the forming of the second anti-reflective layer comprises the step of forming a second bottom anti-reflective layer on the second carbon-containing dielectric layer. A second dielectric anti-reflective layer is formed on the second bottom anti-reflective layer.

In an embodiment of the invention, the first dielectric anti-reflective layer and the second dielectric anti-reflective layer are respectively a germanium-containing dielectric layer. The material of the germanium-containing dielectric layer is selected from the group consisting of cerium oxide, cerium nitride, cerium oxynitride, cerium oxynitride, and any combination thereof. In an embodiment of the invention, the first bottom anti-reflective layer and the second bottom anti-reflective layer are both composed of a polymer containing carbon and oxygen (CHO).

In one embodiment of the invention, the first opening and the second opening both extend through the inner dielectric layer and the etch stop layer to expose the substrate to the outside.

In accordance with the above-described embodiments, embodiments of the present invention provide an advanced method of forming contact holes in a semiconductor substrate using a two-time lithography process. Forming at least one first opening in the inner dielectric layer of the semiconductor substrate by using a first lithography etching step; filling the first opening with a carbon-containing dielectric layer, and using yellow light The process, on the carbon-containing dielectric layer, forms an anti-reflective layer and a patterned photoresist layer. Then, a second etching process is performed to form at least one second opening in the inner dielectric layer.

Since the first opening formed by the first lithography process can be covered by the carbon-containing dielectric layer, it is completely unaffected by the second lithography process. Even if the yellow light process of forming the second opening requires a photoresist rework step, the first opening is not damaged or the critical dimension of the first opening is increased. Therefore, the problem of increasing the critical dimension of the contact hole due to the photoresist rework step of the second lithography process can be prevented, and the object of improving the process yield of the semiconductor device can be achieved.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

SUMMARY OF THE INVENTION An object of the present invention is to provide a contact hole forming method for preventing critical dimensions from being affected by photoresist rework to improve the process yield of a semiconductor device. The above and other objects, features and advantages of the present invention will become more <RTIgt;

Referring to FIG. 1A to FIG. 1D, FIG. 1A to FIG. 1D are cross-sectional views showing a process of forming a contact hole in a semiconductor device according to a preferred embodiment of the present invention.

Among them, the method of forming the contact hole includes the following steps: First, a substrate 101 is provided. For example, a wafer is provided or a semiconductor substrate such as a Silicon On Isolator (SOI) is provided.

Next, an etch stop layer 102 and an inner dielectric layer 103 are sequentially formed on the substrate 101 to cover the substrate 101. The inner dielectric layer 103 can be formed by a thin film deposition technique such as a plasma enhanced chemical vapor deposition process. The material may include undoped xenon, doped with oxygen, such as Tetetra-Ethyl-Ortho-Silicate (TEOS), or borophosphonium, fluorophosphonium, phosphorus, oxygen, boron Niobium oxide, low dielectric constant (Low K) material, ultra low dielectric constant (Ultra Low K) material or any combination of the above.

Then, on the inner dielectric layer 103, a first etching process is performed to form at least one contact opening 109 in the inner dielectric layer 103.

In a preferred embodiment of the present invention, before performing the first etching process, the carbon-containing dielectric layer 104, the anti-reflective layer, and the patterned photoresist layer 107 are sequentially formed on the inner dielectric layer 103. .

The patterned photoresist layer 107 has at least one pattern opening 108 (as shown in FIG. 1A). The carbon-containing dielectric layer 104 is preferably a hard mask formed on the inner dielectric layer 103 by a Plasma-Enhanced Chemical Vapor Deposition (PECVD) method. In the present embodiment, the carbon-containing dielectric layer 104 is an Advanced Patterning Film (APF) provided by Applied Materials. The anti-reflective layer is formed by a bottom anti-reflective layer 105 above the carbon-containing dielectric layer 104 and a dielectric anti-reflective layer 106 above the bottom anti-reflective layer 105. The dielectric anti-reflective layer 106 is preferably a germanium-containing dielectric layer selected from the group consisting of cerium oxide, cerium nitride, cerium oxynitride, cerium oxynitride, and any combination thereof. The bottom anti-reflective layer 105 is an organic material, such as a hydrocarbon containing carbon-oxygen (CHO), spin-on over a carbon-containing dielectric layer 104 containing a hydrocarbon-hydrogen (CHO) polymer. Preferably, it consists of ethyl lactate or propylene glycol mono-methyl ether acetate or a combination of the two.

In addition, in other embodiments of the present invention, the patterned photoresist layer 107 forming the contact opening 109 may be a tri-layer photoresist structure including sequentially stacked ArF photoresist layers. , an organic photoresist layer (SHB) containing an antimony and an I-line photoresist layer (not shown). And before performing the first etching process, further comprising performing a pattern transfer step of first performing the at least one dry etching process by using the pattern opening 108 formed in the ArF photoresist layer by exposure and development, and then using the ArF photoresist layer as a mask. The pattern of the pattern openings 108 is sequentially transferred to the SHB photoresist layer and the I-line photoresist layer.

Next, using the patterned photoresist layer 107 as a mask, a first etching process is performed, and at least one contact opening 109 is formed in the inner dielectric layer 103. In a preferred embodiment of the present invention, the first etching process uses a dry etching process to expose the contact opening 109 through the inner dielectric layer 103 and the etch stop layer 102 to expose the substrate 101 to the outside. However, in other embodiments, the contact opening 109 extends only into the inner dielectric layer 103 and does not extend through the inner dielectric layer 103 and the etch stop layer 102.

After the contact opening 109 is formed, the patterned photoresist layer 107, the bottom anti-reflective layer 105, and the dielectric anti-reflective layer 106 are stripped (as shown in FIG. 1B). Thereafter, another carbon-containing dielectric layer 110 is formed on the inner dielectric layer 103, thereby filling the opening 109. Like the carbon-containing dielectric layer 104, the carbon-containing dielectric layer 110 is preferably a hard mask formed by plasma-assisted chemical vapor deposition. In the present embodiment, the carbon-containing dielectric layer 110 is also an advanced film provided by Applied Materials. However, in other embodiments, the carbon-containing dielectric layers 104 and 110 may be made of different materials.

Thereafter, a bottom anti-reflective layer 111, a dielectric anti-reflective layer 112, and a patterned photoresist layer 113 are sequentially formed on the carbon-containing dielectric layer 110. The patterned photoresist layer 113 further has at least one pattern opening 114 (as shown in FIG. 1C). In a preferred embodiment of the present invention, the dielectric anti-reflective layer 112 is a germanium-containing dielectric layer selected from the group consisting of cerium oxide, cerium nitride, cerium oxynitride, cerium oxynitride, and any combination thereof. One of the groups that make up. The bottom anti-reflective layer 111 is spin-coated on the carbon-containing dielectric layer 110 by an organic material such as a hydrocarbon-containing (CHO)-containing polymer. The poly(hydrocarbyloxy) (CHO)-containing polymer preferably consists of ethyl lactate, propylene glycol methyl ether acetate or a combination of the two.

It should be noted that, in the above embodiment, the materials of the dielectric anti-reflective layer 112, the bottom anti-reflective layer 111 and the patterned photoresist layer 113 are preferably respectively combined with the dielectric anti-reflective layer 105 and the bottom anti-reflective layer 106. The patterned photoresist layer 107 is the same. However, the material of the dielectric anti-reflective layer 112, the bottom anti-reflective layer 111, and the patterned photoresist layer 113 may be respectively combined with the dielectric anti-reflective layer 106 and the bottom anti-reflective layer 105, and in other embodiments. The patterned photoresist layer 107 is different. Since the steps and materials for forming the patterned photoresist layer, the dielectric anti-reflective layer, and the bottom anti-reflective layer are well known to those skilled in the art, the related steps and materials should not be described herein.

Next, the second photoresist process is performed by using the patterned photoresist layer 113 as a mask. In the inner dielectric layer 103, at least one contact opening 115 is formed (as shown in FIG. 1D). In a preferred embodiment of the present invention, the second etching process uses a dry etching process to expose the contact opening 115 through the inner dielectric layer 103 and the etch stop layer 102 to expose the substrate 101 to the outside. However, in other embodiments, the contact opening 115 extends only into the inner dielectric layer 103 and does not penetrate the inner dielectric layer 103 and the etch stop layer 102.

Thereafter, the carbon-containing dielectric layer 110 remaining on the inner dielectric layer 103 is stripped to form a contact hole (contact openings 109 and 115) as shown in FIG. 1E.

In accordance with the above-described embodiments, embodiments of the present invention provide an advanced method of forming contact holes in a semiconductor substrate using a two-time lithography process. Forming at least one first opening in the inner dielectric layer of the semiconductor substrate by using a first lithography etching step; filling the first opening with a carbon-containing dielectric layer, and using yellow light The process, on the carbon-containing dielectric layer, forms an anti-reflective layer and a patterned photoresist layer. Then, a second etching process is performed to form at least one second opening in the inner dielectric layer.

Since the first opening formed by the first lithography process can be covered by the carbon-containing dielectric layer, it is completely unaffected by the second lithography process. Even if the yellow light process of forming the second opening requires a photoresist rework step, the first opening is not damaged or the critical dimension of the first opening is increased. Therefore, the problem of increasing the critical dimension of the contact hole due to the photoresist rework step of the second lithography process can be prevented, and the object of improving the process yield of the semiconductor device can be achieved.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

101. . . Substrate

102. . . Etch stop layer

103. . . Inner dielectric layer

104. . . Carbon-containing dielectric layer

106. . . Dielectric anti-reflection layer

105. . . Bottom anti-reflection layer

107. . . Patterned photoresist layer

108. . . Pattern opening

109. . . Contact opening

110. . . Carbon-containing dielectric layer

112. . . Dielectric anti-reflection layer

111. . . Bottom anti-reflection layer

113. . . Patterned photoresist layer

114. . . Pattern opening

115. . . Contact opening

1A through 1D are cross-sectional views showing a process of forming a contact hole in a semiconductor device in accordance with a preferred embodiment of the present invention.

1E is a cross-sectional view showing the structure of a contact hole formed in accordance with the process of FIGS. 1A to 1D.

101. . . Substrate

102. . . Etch stop layer

103. . . Inner dielectric layer

110. . . Carbon-containing dielectric layer

112. . . Dielectric anti-reflection layer

111. . . Bottom anti-reflection layer

113. . . Patterned photoresist layer

114. . . Pattern opening

Claims (13)

A method for forming a contact hole, comprising: providing a substrate on which an etch stop layer and an inner dielectric layer are sequentially covered; performing a first etching process to form at least a first layer in the inner dielectric layer Opening a first carbon-containing dielectric layer on the inner layer dielectric layer (ILD) to fill the first opening; forming a first layer on the first carbon-containing dielectric layer An anti-reflective layer and a first patterned photoresist layer, and the first patterned photoresist layer is an etching mask, performing a second etching process to form at least a second layer in the inner dielectric layer Opening. The contact hole forming method of claim 1, wherein the forming of the first anti-reflective layer and the first patterned photoresist layer may include a photoresist rework step. The method for forming a contact hole according to claim 1, wherein the step of forming the first anti-reflective layer comprises: forming a first bottom anti-reflective coating (BARC) in the first And forming a first dielectric anti-reflective coating (DARC) on the first bottom anti-reflective layer. The contact hole forming method according to claim 3, wherein the first bottom anti-reflection layer is composed of a polymer containing carbon oxyhydrogen (CHO). The contact hole forming method of claim 3, wherein the first dielectric anti-reflective layer is a germanium-containing dielectric layer. The method for forming a contact hole according to claim 5, wherein the material of the germanium-containing dielectric layer is selected from the group consisting of cerium oxide, cerium nitride, cerium oxynitride, cerium oxynitride, and any combination thereof. Form a group of people. The method for forming a contact hole according to claim 1, wherein the step of forming the first opening comprises: sequentially forming a second carbon-containing dielectric layer and a second on the inner dielectric layer The first anti-reflective layer and the second patterned photoresist layer; and the second patterned photoresist layer is an etch mask, the first etching process is performed, and the first opening is formed in the inner dielectric layer. The contact hole forming method of claim 7, wherein after forming the first opening, further comprising stripping the second carbon-containing dielectric layer, the second anti-reflective layer, and the second patterned light Resistance layer. The method for forming a contact hole according to claim 7, wherein the forming the second anti-reflective layer comprises: forming a second bottom anti-reflective layer on the second carbon-containing dielectric layer; and forming a A second dielectric anti-reflective layer is on the second bottom anti-reflective layer. The contact hole forming method according to claim 9, wherein the second bottom anti-reflective layer is composed of a polymer containing carbon oxyhydrogen (CHO). The contact hole forming method of claim 9, wherein the second dielectric anti-reflective layer is a germanium-containing dielectric layer. The method for forming a contact hole according to claim 11, wherein the material of the germanium-containing dielectric layer is selected from the group consisting of cerium oxide, cerium nitride, cerium oxynitride, cerium oxynitride, and any combination thereof. Form a group of people. The contact hole forming method of claim 1, wherein the first opening and the second opening penetrate the inner dielectric layer and the etch stop layer to expose the substrate to the outside.