Method for forming a dielectric zone in a semiconductor substrate

• US 6,613,644 B2
• Filed: 08/22/2001
• Issued: 09/02/2003
• Est. Priority Date: 08/22/2000
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Lachner, Rudolf
• Primary Examiner(s): Everhart, Caridad
• Assistant Examiner(s): Luu, Chuong A
• Application Number:
  US09/935,560
• Publication Number:
  US 20020052092A1
• Time in Patent Office: 741 Days
• Field of Search: 438/425, 438/424, 438/426, 438/427, 438/439, 438/296, 438/435
• US Class Current: 438/424
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: H01L 21/764 Air gaps H01L21/76264 takes precedence

Abstract

A method for forming a dielectric zone in a region of a semiconductor substrate is described. A first trench and a second trench are formed in the region of the semiconductor substrate resulting in a web being formed between the first trench and the second trench. Afterward, a first dielectric layer is deposited in the first trench and the second trench. The web is subsequently removed, a third trench thereby being produced in the semiconductor substrate. Afterwards, a second dielectric layer is formed in the third trench. The first dielectric layer and the second dielectric layer together form a dielectric zone in the semiconductor substrate, on which it is advantageously possible to dispose components with substrate decoupling.

Claims

1. A method for forming a dielectric zone in a region of a semiconductor substrate, which comprises the steps of:

forming a first trench and a second trench in the region of the semiconductor substrate resulting in a web being formed between the first trench and the second trench;

providing a first dielectric layer in an upper region of the first and second trenches and forming a first cavity in a lower region of the first trench below the upper region of the first trench and terming a second cavity in a lower region of the second trench below the upper region of the second trench;

providing a first dielectric layer in the first trench and the second trench;

removing the web, a third trench thereby being produced;

wherein the first, second, and third trenches have an aspect ratio of greater than 1; and

providing a second dielectric layer in an upper region of the third trench and forming a third cavity contiguous with the first cavity in a lower region of the third trench below the upper region of the third trench.

2. The method according to claim 1, which comprises planarizing the first dielectric layer.

3. The method according to claim 1, which comprises removing the web with one of isotropic etching and anisotropic etching.

4. The method according to claim 1, which comprises using a mask for forming the first trench.

5. The method according to claim 1, which comprises using a mask selected from the group consisting of resist masks and hard masks for forming the third trench.

6. The method according to claim 1, which comprises providing the first dielectric layer in an upper region of the first trench and a cavity is formed in a lower region of the first trench that is disposed below the upper region of the first trench.

7. The method according to claim 6, which comprises providing the second dielectric layer in an upper region of the third trench and a further cavity is formed in a lower region of the third trench which is disposed below the upper region of the third trench.

8. The method according to claim 7, which comprises forming the cavity and the further cavity in a contiguous manner.

9. The method according to claim 1, which comprises forming the third cavity contiguous with the first and second cavities.