Method for forming deep trench capacitor with liquid phase deposition oxide as collar oxide
A method for forming a deep trench capacitor mainly utilizes a liquid phase deposition (LPD) oxide to form a collar oxide layer in the trench, followed by forming a conductive layer serving as an upper electrode of the deep trench capacitor, thereby avoiding collar oxide residue in the conductive layer and thus forming good electrical connection. And, the method of the present invention does not need a dry etch to remove the unnecessary collar oxide layer such that the process can be simplified.
Latest Nanya Technology Corporation Patents:
- Method for preparing memory device having protrusion of word line
- Semiconductor device with bit line contacts of different pitches
- Vertical memory structure with air gaps and method for preparing the same
- Semiconductor device with conductive cap layer over conductive plug and method for preparinging the same
- Transmission device
1. Field of the Invention
The present invention relates to a semiconductor process, more specifically, to a method for forming a deep trench capacitor of a semiconductor memory.
2. Description of the Prior Art
Deep trench capacitors have been widely employed in the conventional semiconductor memory (such as DRAM) process, in order to reduce the occupied areas and to increase capacitances.
However, as shown in
Therefore, a need for overcoming the above problem is required. The present invention fulfils this need.
SUMMARY OF THE INVENTIONA purpose of the present invention is to provide a method for forming a trench capacitor, which can prevent the insulation layer acting as the collar oxide layer from remaining in the conductive layer acting as the upper electrode, so that a good electrical connection between the conductive layer used as the upper electrode and the conductive layer used as the connection electrode can be formed.
Another purpose of the present invention is to provide a method for forming a trench capacitor, which does not require the dry etch to remove the unnecessary collar oxide layer/insulation layer on the upper electrode conductive layer, so that the process is simplified.
In accordance with an aspect of the present invention, a method for forming a trench capacitor comprises steps of providing a substrate; forming a mask layer of a predetermined pattern on the substrate to expose a portion of the substrate; forming a trench in the exposed portion of the substrate; forming a conductive diffusion region in the substrate at the periphery of the lower portion of the trench; forming a dielectric layer on the surface of the trench; filling the trench with a photoresist layer, and making the top of the photoresist layer at least not lower than the top of the conductive diffusion region; removing the dielectric layer on the surface of the trench not covered by the photoresist layer; forming a low temperature oxide layer on the surface of the trench not coverd by the photoresist layer; removing the photoresist layer in the trench; and filling the trench with a conductive layer and making the top of the conductive layer lower than the bottom of the low temperature oxide layer.
In accordance with another aspect of the present invention, a method for forming a trench capacitor comprises steps of providing a substrate; forming a mask layer of a predetermined pattern on the substrate to expose a portion of the substrate; forming a trench in the exposed portion of the substrate; filling the lower portion of the trench with a photoresist layer; forming a low temperature oxide layer on the surface of the trench not covered by the photoresist layer; removing the photoresist layer in the trench; forming a conductive diffusion region in the substrate at the periphery of the portion of the trench not covered by the low temperature oxide layer; forming a dielectric layer on the surfaces of the trench and the low temperature oxide layer; and filling the trench with a conductive layer, and making the top of the conductive layer lower than the bottom of the low temperature oxide layer.
In accordance with another aspect of the present invention, in the aforementioned methods, the top of the conductive diffusion region or the photoresist is lower than the bottom of a transistor adjacent to the trench and subsequently formed.
In accordance with another aspect of the present invention, in the aforementioned methods, the low temperature oxide layer is a liquid phase deposition layer
BRIEF DESCRIPTION OF THE DRAWINGSThe following drawings are not drawn according to practical dimensions and ratios and are only for illustrating the mutual relationships between the respective portions. In addition, the like reference numbers indicate the similar elements.
The embodiments of the present invention will be described in detail with reference to the accompanying drawings
Please refer to
In
As shown in
Please refer to
In another embodiment shown in
As shown in
In
Please refer to
Then, as what has been well known, a connecting electrode (not shown) and a buried strap (BS) (not shown) are formed on the conductive layers 29 and 39, so as to engage the transistor formed in the adjacent active region.
According to the method of the present invention for forming a deep trench capacitor, prior to forming the conductive layers 29 and 39, which are used as the upper electrodes of the deep trench capacitors, the liquid phase deposition (LPD) oxide layers 28 and 36 used as the collar oxide layers have been formed. By that there will be no poor electrical connection created due to the residual oxide layer in the recess, as the conventional techniques presented in
While the embodiments of the present invention are illustrated and described, various modifications and alterations can be made by persons skilled in this art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention may not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.
Claims
1-7. (canceled)
8. A method for forming a trench capacitor comprising the steps of:
- providing a substrate;
- forming a mask layer of a predetermined pattern on the substrate to expose a portion of the substrate;
- forming a trench in the exposed portion of the substrate;
- filling the lower portion of the trench with a photoresist layer;
- forming a low temperature oxide layer on the surface of the trench not covered by the photoresist layer;
- removing the photoresist layer in the trench;
- forming a conductive diffusion region in the substrate at the periphery of the portion of the trench not covered by the low temperature oxide layer;
- forming a dielectric layer on the surfaces of the trench and the low temperature oxide layer; and
- filling the trench with a conductive layer, and making the top of the conductive layer lower than the bottom of the low temperature oxide layer.
9. (canceled)
10. The method as claimed in claim 8, wherein the low temperature oxide layer is a liquid phase deposition oxide layer.
11. The method as claimed in claim 8, wherein the conductive diffusion region is formed by use of Arsenic Silicon Glass (ASG) and heat treatment, or Gas Phase Diffusion (GDP).
12. The method as claimed in claim 8, wherein the dielectric layer comprises a nitride layer.
13. The method as claimed in claim 12, wherein the dielectric layer also comprises an oxide layer.
14. The method as claimed in claim 8, wherein the conductive layer comprises a polysilicon layer.
15. The method as claimed in claim 8, further comprising a step of removing the dielectric layer on the surface of the low temperature oxide layer, after the filling with the conductive layer.
Type: Application
Filed: Jan 24, 2005
Publication Date: Nov 3, 2005
Applicant: Nanya Technology Corporation (Taoyuan)
Inventors: Sam Liao (Taichung City), Shian-Jyh Lin (Yonghe City), Chia-Sheng Yu (Banciao City)
Application Number: 11/039,843