Low-K dielectric gapfill by flowable deposition

• US 9,412,581 B2
• Filed: 07/16/2014
• Issued: 08/09/2016
• Est. Priority Date: 07/16/2014
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Thadani, Kiran V., Liang, Jingmei, Lee, Young S., Srinivasan, Mukund
• Primary Examiner(s): Rizkallah, Kimberly
• Assistant Examiner(s): Turner, Brian
• Application Number:
  US14/333,262
• Publication Number:
  US 20160020089A1
• Time in Patent Office: 755 Days
• Field of Search: 438/424, 438/435, 438/788, 257/E21.24, 257/E21.241, 257/E21.277
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02216 the compound being a molecule comprising at least one silicon-oxygen bond and the compound having hydrogen or an organic group attached to the silicon or oxygen, e.g. a siloxane
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]

Abstract

Methods are described for forming a flowable low-k dielectric layer on a patterned substrate. The film may be a silicon-carbon-oxygen (Si—C—O) layer in which the silicon and carbon constituents come from a silicon and carbon containing precursor while the oxygen may come from an oxygen-containing precursor activated in a remote plasma region. A similarly deposited silicon oxide layer may be deposited first to improve the gapfill capabilities. Alternatively, or in combination, the flow of a silicon-and-carbon-containing precursor may be reduced during deposition to change the properties from low-k to high strength roughly following the filling of features of the patterned substrate.

Claims

1. A method of filling a trench, the method comprising:

transferring a patterned substrate comprising the trench into a substrate processing region of a substrate processing chamber;

flowing an oxygen-containing precursor into a remote plasma region while igniting a remote plasma to form a radical-oxygen precursor;

flowing the radical oxygen precursor into the substrate processing region;

flowing a first silicon-and-carbon-containing precursor into the substrate processing region without first passing the first silicon-and-carbon-containing precursor through a plasma, wherein the first silicon-and-carbon-containing precursor has a Si—

O;

Si ratio of less than 3;

flowing a second silicon-and-carbon-containing precursor into the substrate processing region without first passing the second silicon-and-carbon-containing precursor through a plasma, wherein the second silicon-and-carbon-containing precursor has a Si—

O;

Si ratio of greater than 2;

combining the first silicon-and-carbon-containing precursor, the second silicon-and-carbon-containing precursor and the radical oxygen precursor in the substrate processing region to form a low-k dielectric layer on the patterned substrate, wherein a portion of the low-k dielectric layer deposits on the substrate and flows along the surface during formation of the low-k dielectric layer to fill the trench, and wherein a partial pressure ratio of the first silicon-and-carbon-containing precursor to the second silicon-and-carbon-containing precursor within the substrate processing region is reduced during formation of the low-k dielectric layer, wherein a second partial pressure ratio of the first silicon-and-carbon-containing precursor to the second silicon-and-carbon-containing precursor measured in the substrate processing region at the end of the formation of the low-k dielectric layer is less than a first partial pressure ratio at the beginning of the formation of the low-k dielectric layer by at least 25%; and

solidifying the low-k dielectric layer within the trench.

2. The method of claim 1, wherein the low-k dielectric layer has a dielectric constant of between 2.2 and 3.0 following solidification.

3. The method of claim 1, wherein a temperature of the substrate during formation of the low-k dielectric layer is less than 150°

C.

4. The method of claim 1, wherein the first silicon-and-carbon-containing precursor is octamethylcyclotetrasiloxane or tetramethylcyclotetrasiloxane.

5. The method of claim 1, wherein the first silicon-and-carbon-containing precursor has a Si—

O;

Si ratio of 1.

6. The method of claim 1, wherein the second silicon-and-carbon-containing precursor has a Si—

O;

Si ratio of 4.

7. The method of claim 1, wherein the second silicon-and-carbon-containing precursor is tetramethyl orthosilicate.