DOPANT MARKER FOR PRECISE RECESS CONTROL
Recess markers are implanted in a material during deposition and used during etching of the material for in-situ removal rate and removal homogeneity-over-radius definitions. An embodiment includes depositing a material on a substrate, implanting two dopants at two predetermined times, respectively, during deposition of the material, etching the material, detecting depths of the two dopants during etching, calculating the removal rate of the material in situ from the depths of the two dopants, and determining from the removal rate an etching stop position. Embodiments further include laterally implanting two dopants in a material at a predetermined depth during deposition, etching the material, detecting the positions and intensities of the two dopants during etching, and calculating lateral homogeneity of the material in situ from intensities of the dopants. Embodiments further include in situ corrective action for the removal process based on the determined removal rate and lateral homogeneity.
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This application is a divisional of U.S. application Ser. No. 12/947,150, filed Nov. 16, 2010, the entirety of which is incorporated herein by reference.
TECHNICAL FIELDThe present disclosure relates to improved recess control in material removal processes. The present disclosure is particularly applicable to fabrication of semiconductors.
BACKGROUNDIn semiconductor fabrication, in material removal processes such as chemical mechanical polishing (CMP), etching, or etchback, the stopping point is conventionally controlled by employing etch stops or by setting particular removal times. However, such methods do not guarantee homogenous and controlled material removal. Often if the removal rate or removal homogeneity is not sufficiently precise, the currently processed wafer is misprocessed and corrective action is performed only for subsequent wafers. This may lead to substantial losses.
A need therefore exists for methodology enabling in-situ removal rate definition and removal homogeneity-over-radius definition as well as in-situ corrective action.
SUMMARYAn aspect of the present disclosure is an improved method of forming a semiconductor by employing recess markers at different depths for in-situ removal rate definition.
Another aspect of the present disclosure is an improved method of forming a semiconductor by employing recess markers at different lateral positions for in-situ removal homogeneity-over-radius definition.
Another aspect of the present disclosure is an improved method of forming a semiconductor by employing recess markers for in-situ correction of a material removal process.
Additional aspects and other features of the present disclosure will be set forth in the description which follows and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the present disclosure. The advantages of the present disclosure may be realized and obtained as particularly pointed out in the appended claims.
According to the present disclosure, some technical effects may be achieved in part by a method of fabricating a semiconductor device, the method comprising: depositing a layer of material on a substrate; during deposition of the material: after a first predetermined period of time, implanting a first dopant in the material; after a second predetermined period of time, implanting a second dopant in the material, the first and second predetermined periods of time together being less than the total deposition time; etching the material; during etching, detecting the depths of the first and second dopants; calculating the removal rate of the material in situ from the depths of the first and second dopants; and determining from the removal rate a stop position for etching.
Aspects of the present disclosure include implanting dopants that do not change the electrical properties of the material. Further aspects include detecting the depths of the first and second dopants by detecting and analyzing a physical, spectral, or chemical property of the first and second dopants. Another aspect includes the first and second dopants being different. Other aspects include implanting the first dopant by temporarily depositing the first dopant simultaneously with the material after the first predetermined period of time; and implanting the second dopant by temporarily depositing the second dopant simultaneously with the material after the second predetermined period of time. Additional aspects include after a third predetermined period of time, implanting a third dopant in the material, the first, second, and third predetermined periods of time together being less than the total deposition time; during etching, detecting the depth of the third dopant; verifying the calculated removal rate of the material from the depth of the third dopant. Further aspects include the first, second, and third dopants being equally spaced through the layer thickness. Other aspects include the first, second, and third dopants being asymmetrically spaced through the layer thickness.
Another aspect of the present disclosure is a method of fabricating a semiconductor device, the method comprising: depositing a layer of material on a substrate; during deposition of the material, at a predetermined depth, laterally implanting a first dopant and a second dopant in the material; etching the material; during etching, detecting the positions and intensities of the first and second dopants; and calculating lateral homogeneity of the material in situ from the intensities of the first and second dopants.
Aspects include implanting dopants that do not change the electrical properties of the material. Further aspects include detecting the positions and intensities of the first and second dopants by detecting and analyzing a physical, spectral, or chemical property of the first and second dopants. Other aspects include implanting the first and second dopants by beam implantation. Another aspect includes implanting the first and second dopants as concentric rings. Additional aspects include implanting the first and second dopants at a depth of ¼ to ¾ of the thickness of the layer of material. Further aspects include implanting a third dopant in the material as a third concentric ring; during etching, detecting the position and intensity of the third dopant; and verifying the calculated lateral homogeneity of the material from the position and intensity of the third dopant.
Another aspect of the present disclosure is a method of fabricating a semiconductor device, the method comprising: depositing a layer of material on a substrate; implanting at least two dopants in the material during deposition; removing the material; during material removal, detecting the dopants; calculating the removal rate of the material in situ from the depths of the dopants and/or calculating lateral homogeneity of the material in situ from the appearance of the dopants; and correcting the removal process to improve the removal rate and/or the lateral homogeneity of the material.
Aspects include correcting the removal process by controlling the relative intensity or relative timing. Further aspects include removing by CMP, and correcting the removal process by changing pressure settings for the CMP to improve the lateral homogeneity of the material. Other aspects include removing by plasma etching, and correcting the removal process by biasing the edges of the layer. Additional aspects include implanting three dopants in the material during deposition.
Additional aspects and technical effects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description wherein embodiments of the present disclosure are described simply by way of illustration of the best mode contemplated to carry out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawing and in which like reference numerals refer to similar elements and in which:
In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments. It should be apparent, however, that exemplary embodiments may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring exemplary embodiments. In addition, unless otherwise indicated, all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.”
The present disclosure addresses and solves the current problems of unreliable recess control and non-homogeneous removal attendant upon etching or polishing a layer of material. In accordance with embodiments of the present disclosure, recess markers are implanted during deposition of the layer. The markers leave short traces which are then detected and analyzed during the etching or polishing process. From the detected traces, removal rates, precise definition of the stop point, and lateral homogeneity can be in-situ calculated. Further, any needed corrective action may be determined and performed in-situ.
Methodology in accordance with embodiments of the present disclosure includes depositing a layer of material on a substrate, during deposition of the material, after first and second predetermined periods of time, implanting first and second dopants, respectively, in the material, the first and second predetermined periods of time together being less than the total deposition time, etching the material, during etching, detecting the depths of the first and second dopants, calculating the removal rate of the material in situ from the depths of the first and second dopants, and determining from the removal rate a stop position for etching.
Still other aspects, features, and technical effects will be readily apparent to those skilled in this art from the following detailed description, wherein preferred embodiments are shown and described, simply by way of illustration of the best mode contemplated. The disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
Reference markers d1, d2, and d3 may be the same or different. Each dopant employed must not change electrical or other properties of the material being deposited. Further, the dopants must be detectable by physical, spectral, or chemical analysis. For example, if the material being deposited is Tetraethyl orthosilicate (TEOS), such as for forming an interlayer dielectric (ILD), dopants d1, d2, and d3 may be boron (B), nitrogen (N), and/or phosphorus (P). Although three recess markers d1, d2, and d3 are shown in
The embodiments of the present disclosure can achieve several technical effects, including homogeneous material removal both laterally and vertically, precise stop point definition, and in-situ correction of removal rates, thereby reducing losses and increasing output. The present disclosure enjoys industrial applicability in any of various types of semiconductor devices.
In the preceding description, the present disclosure is described with reference to specifically exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure, as set forth in the claims. The specification and drawings are, accordingly, to be regarded as illustrative and not as restrictive. It is understood that the present disclosure is capable of using various other combinations and embodiments and is capable of any changes or modifications within the scope of the inventive concept as expressed herein.
Claims
1. A method comprising:
- depositing a layer of material on a substrate;
- implanting at least two dopants at different depths in the material during deposition;
- removing the material;
- during material removal, detecting the dopants;
- calculating the removal rate of the material in situ from the depths of the dopants; and
- correcting the removal process to improve the removal rate of the material in situ.
2. The method according to claim 1, comprising calculating the removal rate by calculating the time between detection of consecutive dopants.
3. The method according to claim 1, comprising calculating the removal rate by calculating pressure between detection of consecutive dopants.
4. The method according to claim 1, further comprising calculating a stop point for material removal based on detection of the dopants and the calculated removal rate.
5. The method according to claim 4, comprising correcting the removal process based on the calculated removal rate and calculated stop point.
6. The method according to claim 1, comprising removing the material by etching.
7. The method according to claim 1, comprising removing the material by polishing.
8. The method according to claim 1, comprising implanting three dopants in the material during deposition.
9. The method according to claim 1, wherein the material comprises an interlayer dielectric (ILD), and the dopants comprise boron (B), nitrogen (N), and/or phosphorus (P).
10. The method according to claim 9, wherein the ILD comprises tetraethyl orthosilicate (TEOS).
11. A method comprising:
- depositing a layer of material on a substrate;
- implanting at least two dopants at a predetermined depth, laterally separated, in the material during deposition;
- removing the material;
- during material removal, detecting the dopants;
- calculating the lateral homogeneity of the material in situ from the appearance of the dopants; and
- correcting the removal process to improve the lateral homogeneity of the material in situ.
12. The method according to claim 11, comprising calculating lateral homogeneity by recording intensity versus relative positions of the dopants and calculating lag time of detection of successive dopants.
13. The method according to claim 12, comprising correcting the removal process by controlling a relative intensity.
14. The method according to claim 12, comprising correcting the removal process by controlling a relative timing.
15. The method according to claim 11, wherein removing comprises chemical mechanical polishing (CMP), and correcting the removal process comprises changing pressure settings for the CMP.
16. The method according to claim 11, wherein removing comprises plasma etching, and correcting the removal process comprises biasing edges of the layer.
17. The method according to claim 11, comprising implanting three dopants in the material during deposition.
18. The method according to claim 17, wherein the material comprises an interlayer dielectric (ILD), and the dopants comprise boron (B), nitrogen (N), and/or phosphorus (P).
19. The method according to claim 18, wherein the ILD comprises tetraethyl orthosilicate (TEOS).
20. A method comprising:
- depositing an interlayer dielectric (ILD) on a substrate;
- implanting at least three dopants comprising boron (B), nitrogen (N), and/or phosphorus (P) at different depths and/or at different lateral positions in the ILD during deposition;
- removing the ILD by etching or polishing;
- during ILD removal, detecting the dopants;
- calculating the removal rate and/or lateral homogeneity of the ILD in situ from the appearance of the dopants; and
- correcting the removal process to improve the removal rate and/or lateral homogeneity of the ILD in situ by controlling a relative intensity or a relative timing, by biasing edges of the layer, and/or by changing pressure settings.
Type: Application
Filed: May 15, 2012
Publication Date: Nov 8, 2012
Applicant: GLOBALFOUNDRIES INC. (Grand Cayman)
Inventors: Dmytro Chumakov (Dresden), Peter Baars (Dresden)
Application Number: 13/471,756
International Classification: H01L 21/66 (20060101); H01L 21/306 (20060101);