CN103107124A

CN103107124A - Method of improving planarization of surface of shallow trench isolation silicon oxide film

Info

Publication number: CN103107124A
Application number: CN2011103564197A
Authority: CN
Inventors: 刘俊
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2011-11-11
Filing date: 2011-11-11
Publication date: 2013-05-15

Abstract

The invention discloses a method of improving planarization of surface of a shallow trench isolation silicon oxide film. The method of improving the planarization of surface of the shallow trench isolation silicon oxide film includes the following steps of with regard to silicon oxide filling a shallow trench, lapping the silicon oxide by means of chemical machinery of shallow trench isolation (STI) at first, and then etching the silicon oxide of an active area (AA) compact zone by means of mask, thereby improving the planarization of surface of the shallow trench isolation silicon oxide film. The method of improving the planarization of surface of the shallow trench isolation silicon oxide film can greatly lower requirements to photoetching registration precision, and for instance, a requirement of original 0.1 micrometer is relaxed up to 0.3 micrometer. Due to the fact that etching quantity is reduced, applying a wet etching technology with higher selectivity can be considered. In addition, the method of improving the planarization of surface of the shallow trench isolation silicon oxide film can increase flexibility of the technology, namely, the method of improving the planarization of surface of the shallow trench isolation silicon oxide film can adjust etching time according to different products so as to independently adjust the height of the silicon oxide of the shallow trench isolation in AA compact zone within a certain range (such as +/- 5000A).

Description

Improve the method for shallow-trench isolation silicon oxide film flattening surface

Technical field

The present invention relates to a kind of method of shallow-trench isolation silicon oxide film flattening surface, particularly relate to a kind of method of improving shallow-trench isolation silicon oxide film flattening surface.

Background technology

In semiconductor fabrication, shallow trench isolation is from (Shallow Trench Isolation, STI) to have an isolation effect good for technique, the advantages such as area occupied is little, typical STI technological process comprises: the cmp (CMP) of the inserting of the silica on silicon substrate (pad oxide) and silicon nitride deposition, STI silicon groove etching, silica (HDP Oxide), silica, the removal of silicon nitride and silica (pad oxide).

In the manufacture craft process of (STI), CMP technique is used to remove and the high-density plasma silica (HDP oxide) of filling out (over-filled) is crossed in leveling at shallow trench isolation.Depression (dishing) and erosion (erosion) effect due to CMP, the method of traditional shallow-trench isolation silicon oxide film flattening surface be first by reverse mask (anti-mask) dry etching AA (active area: the active area) silica of compact district, then adopt cmp (CMP) to reach planarization.

Yet traditional reverse mask technique (as shown in Figure 1) has certain requirement for the mask alignment precision, the special place that dotted line marks in Fig. 1, and left avertence or right avertence all can cause the deleterious of planarization.In addition, for reverse mask etching, if half SiO of etching only ₂, help limited to the silicon oxide film flattening surface; Etch into Si ₃N ₄, the flexibility of technique just is restricted, and namely can not follow according to different products, does to adjust flexibly.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of method of improving shallow-trench isolation silicon oxide film flattening surface, and the method can significantly reduce the requirement to this layer photoetching alignment precision, and increases technological flexibility.

For solving the problems of the technologies described above, the method of improving shallow-trench isolation silicon oxide film flattening surface of the present invention, comprise: for the silica that fills up shallow slot, the first cmp (CMP) by STI, then adopt the silica of mask (mask) etching AA compact district, thereby improve the planarization on shallow-trench isolation silicon oxide film surface.

Said method, its concrete steps comprise:

(1) complete filling up of silica in shallow slot by existing STI technique after, carry out STI CMP, then, carry out the photoetching of opening in the AA compact district;

(2) to the SiO of silicon nitride high selectivity ₂Carry out etching, make the SiO of AA compact district ₂The loose zone of film height and AA is consistent, or reaches desired height;

(3) remove photoresist.

In described step (2), the method for etching comprises: wet etching, dry etching; The time of etching can adjust accordingly according to the needs of product, namely according to different products, adopts different etch periods.

Beneficial effect of the present invention is as follows:

(1) can significantly reduce requirement to the lithography alignment precision, such as from original 0.1 μ m left and right, more than being loosened to 0.3 μ m;

(2) due to the minimizing of etch amount, can consider the wet-etching technology of taking selectivity higher;

(3) increase the flexibility of technique, namely can follow according to product differently, done the adjustment of corresponding etch period, so that within the specific limits (such as ± 500A) be adjusted in separately AA compact district shallow trench isolation from the oxide layer height of (STI);

(4) when be adjusted in separately AA compact district shallow trench isolation from the oxide layer height time, do not affect other regional shallow trench isolations from the oxide layer height.

Description of drawings

The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:

Fig. 1 is traditional reverse mask artwork;

Fig. 2 is artwork of the present invention;

Fig. 3 is the photoetching figure that the carrying out in the present invention opened in the AA compact district;

Fig. 4 be in the present invention to STI SiO ₂Carry out the schematic diagram of etching.

Embodiment

The method of improving shallow-trench isolation silicon oxide film flattening surface of the present invention, its artwork as shown in Figure 2, step comprises:

(1) according to existing STI technological process, carry out silica on silicon substrate and silicon nitride deposition, STI silicon groove etching, HDP silica insert (filling up) after, then after STI CMP, carry out the photoetching (as shown in Figure 3) of opening in the AA compact district, in this photoetching process, photoresist thickness is about 1 μ m, uses the I-line mask aligner to expose;

Wherein, the AA compact district can for: in any 10 μ m of chip internal * 10 μ m scopes, the AA area occupied surpass the gross area 40% or more than;

(2) use the SiO to silicon nitride high selectivity (greater than 10: 1) of set time ₂Wet etching or dry etching, as shown in Figure 4, make AA compact district shallow trench isolation from SiO ₂The loose zone of film height and AA is consistent, or reach desired height (such as in ± 500A scope all can);

In this step, before and after the etching, can to AA compact district shallow trench isolation from oxide layer (SiO ₂Film) thickness is measured, so that the monitoring etch amount;

Due to the minimizing of etch amount, this step can be preferred, the wet-etching technology that selectivity is higher, simultaneously, can adopt different etch periods according to different products so that within the specific limits (such as ± 500A) be adjusted in separately AA compact district shallow trench isolation from the oxide layer height;

(3) use conventional dry method to add wet method, remove photoresist.

The present invention first passes through cmp, then adopt the silica of mask etching AA compact district, can reach the effect of improving shallow-trench isolation silicon oxide film flattening surface, and can significantly reduce requirement to the lithography alignment precision, as dotted portion indication part in Fig. 2, such as from about 0.1 original μ m, more than being loosened to 0.3 μ m.

In addition, the present invention can also increase the flexibility of etching technics, namely can follow according to product differently, does the adjustment of corresponding etch period so that within the specific limits (such as ± 500A) be adjusted in separately AA compact district shallow trench isolation from the oxide layer height.

Claims

1. a method of improving shallow-trench isolation silicon oxide film flattening surface, is characterized in that, comprising: for the silica that fills up shallow slot, first by the cmp of STI, then adopt the silica of mask etching AA compact district.

2. the method for claim 1 is characterized in that: described method, and step comprises:

(3) remove photoresist.

3. method as claimed in claim 2, is characterized in that: in described step (2), to the silicon nitride high selectivity be: greater than 10: 1.

4. method as claimed in claim 2, it is characterized in that: in described step (2), the method for etching comprises: wet etching, dry etching.

5. method as claimed in claim 4, it is characterized in that: in described step (2), the method for etching is wet etching.

6. method as claimed in claim 2 is characterized in that: in described step (2), desired height is in ± 500A scope.